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Aplicaciones de la variabilidad de la frecuencia cardíaca en el entrenamiento físico infantil: un complemento al enfoque clínico
Get PDFMultidisciplinary approach to determine the influence of human pressure on nearshore Antarctic fish
No full textConcentrations of five metals together with hematological and morphological parameters were measured in three coastal fish species collected in two sites of the Antarctic Peninsula. Furthermore, we assessed isotopic niche widths among fish populations to better understand their trophic ecology. Nothotenia coriiceps from Fildes Bay displayed high concentrations of Fe and Cu, while those from South Bay had higher concentrations of Cd. All fish from South Bay had higher Zn levels than specimens from Fildes Bay. Effects such as biomagnification of Fe, increased fish metal levels and niche width expansion of Nothotenia coriiceps and Harpagifer antarcticus could be attributed to suboptimal environmental conditions in Fildes Bay. Our findings suggest that early warning signals in coastal Antarctic fish may be linked to increased metal bioavailability as a result of climate change and increased human pressure
Cyclic behavior of beam-to-upright bolted connections: Experimental study of Chilean steel storage racks
No full textIn this research an experimental study to assess the cyclic behavior of bolted moment connection in racks structures is performed. The effect of bolt pretension in the response is evaluated. Sixteen full-scale steel rack joint configurations were subjected to cyclic load according to the protocol established in AISC Seismic provisions. The cyclic performance was evaluated in terms of hysteretic response, failure mechanism, energy dissipation, stiffness, and rotation on the components. Two different configurations were studied. The results showed that the steel rack connections using a 70 % of bolt pretension can accommodate a 0.8 My at 0.04 rad of drift angle, while the joints without bolt pretension reached values below 0.7 My at 4 % of rotation. The failure mechanism was controlled by weld fracture at 4 % of the rotation. A high dispersion in the energy dissipation pattern was obtained and a drop in energy dissipation of up to 4 times in all specimens tested for a 4 % rotation was developed. This phenomenon is due to the welding rupture between the beam and the L-connector. A degradation of the secant stiffness reached up to 60 % for 2 % rotation. Finally, the most important effect of bolt pretension on the cyclic response of steel rack connections was achieved in the increase of flexural resistance and rotation developed
Utilization of the corporate media ecosystem to build trust under high-uncertainty conditions: a review of the energy sector in Chile,Colombia and Ecuador
Get PDFDurante la pandemia de COVID-19, el sector corporativo mostró un interés significativo no solo en la continuidad del negocio, sino también en la necesidad de comunicar riesgos de manera que modificara comportamientos e inspirara confianza, a pesar de los altos niveles de "infoxificación" entre los principales interesados. Este estudio arroja luz sobre el papel asumido por las empresas como fuentes formales de noticias junto con los medios de comunicación tradicionales durante una emergencia sanitaria que, desde una perspectiva comunicacional, ha sido categorizada como una infodemia dentro de un ecosistema de medios emergentes. El estudio identificó estrategias, narrativas y herramientas empleadas por tres empresas energéticas en Chile, Colombia y Ecuador a través de entrevistas semiestructuradas y un análisis en profundidad de sus informes de sostenibilidad. Se encontró que, en sus esfuerzos por proteger la salud de los trabajadores y fortalecer las reputaciones institucionales, las empresas demostraron una alta adaptabilidad en su uso de herramientas y canales para construir narrativas que inspiraran confianza entre los interesados. A pesar de los altos niveles de incertidumbre, las empresas configuraron un ecosistema de medios eficiente para complementar la dieta comunicacional de los interesados. Esta perspectiva es la principal contribución de este estudio, dado que, en el contexto de COVID-19, el discurso corporativo estaba orientado a inspirar confianza y modificar comportamientos entre los trabajadores y sus familias respecto a las medidas preventivas. En este sentido, el ecosistema de medios corporativo, bajo la construcción de una narrativa de confianza, es un componente adicional de la dieta comunicacional de los interesados y un ingrediente vital para contrarrestar la desinformación, como la infoxificación
Intelligent Classrooms: How AI and IoT Can Reshape Learning Spaces
No full textThis review examines the design and configuration of AI‐powered 21st‐century classrooms to align with modern pedagogical approaches. The objective was to identify the main characteristics of innovative classroom design through a systematic literature review analysing 90 articles from the Scopus database. The SPAR‐4‐SRL protocol guided the selection, organisation and assessment of articles, with analysis conducted using descriptive statistics and topic modelling in AtlasTi. Key findings include (a) determinants like acoustics, lighting, temperature, ventilation and dimensions impact learning; (b) flexible furniture arrangements promote collaboration and active learning over traditional row seating; (c) inclusive designs consider sensory needs of students with disabilities; and (d) technology integration is crucial, including smart boards, cameras and connectivity. This comprehensive synthesis highlights some insights into the effect of the use of Artificial Intelligence and the Internet of Things on the architectural principles and environmental factors that optimise classroom spaces for evolving educational practices. Educators, designers and policymakers can apply these insights to create student‐centred, technology‐enhanced learning environments fostering engagement and inclusivity
Computational Study of the 1,3-Dipolar Cycloaddition between Criegee Intermediates and Linalool: Atmospheric Implications
No full textIn this research, we investigated the essential role of biogenic volatile organic compound emissions in regulating tropospheric ozone levels, atmospheric chemistry, and climate dynamics. We explored linalool ozonolysis and secondary organic aerosol formation mechanisms, providing key insights into atmospheric processes. Computational techniques, such as density functional theory calculations and molecular dynamics simulations, were employed for the analysis. Our study delves into the energetic and mechanistic aspects of the 1,3-dipolar cycloadditions involving linalool and its ozonolysis byproducts, known as Criegee intermediates. A total of 24 reactions were analyzed from the three possible Criegee intermediates formed, resulting from different reactant orientations and their endo/exo isomers. We found that only four of these reactions exhibit large rate constants that can compete with tropospheric reactions. This reactivity pattern was characterized by analyzing reactivity indices from conceptual density functional theory and determining that electron flux originates from linalool to the Criegee intermediates. Greater electrophilicity in the Criegee intermediates results in a lower reaction activation energy, confirmed by the global electrophilicity index. Furthermore, using the activation strain model and energy decomposition analysis, we found that differences in activation energies were primarily driven by nonorbital energy factors. Finally, molecular dynamics simulations showed that the final cycloaddition adducts of the most favorable 1,3-dipolar cycloaddition interact favorably with water molecules in an exergonic process, adsorbing up to 92% of the water molecules after 20 ns. Our findings provide insights that enhance our understanding of the interactions between natural emissions and atmospheric constituents
A Measurement of the Largest-scale CMB E-mode Polarization with CLASS
Get PDFWe present measurements of large-scale cosmic microwave background E-mode polarization from the Cosmology Large Angular Scale Surveyor 90 GHz data. Using 115 det-yr of observations collected through 2024 with a variable-delay polarization modulator, we achieved a polarization sensitivity of 82 mu Karcmin , comparable to Planck at similar frequencies (100 and 143 GHz ). The analysis demonstrates effective mitigation of systematic errors and addresses challenges to large-angular-scale power recovery posed by time-domain filtering in maximum-likelihood map-making. A novel implementation of the pixel-space transfer matrix is introduced, which enables efficient filtering simulations and bias correction in the power spectrum using the quadratic cross-spectrum estimator. Overall, we achieved an unbiased time-domain filtering correction to recover the largest angular scale polarization, with the only power deficit, arising from map-making nonlinearity, being characterized as 30), our results, both independently and in cross-correlation with Planck, remain fully consistent with Planck's measurements
Purification of 1-butanol from rich and lean aqueous heteroazeotropic mixture by sponge-like ionic liquid process
No full textThe Acetone-Butanol-Ethanol (ABE) fermentation process is a promising approach for sustainable biobutanol production. However, separation and purification of butanol following membrane-based or distillation separation processes remain challenging due to the formation of a water-butanol heteroazeotropic mixture (55.5 wt% 1-butanol), requiring multiple distillation columns and generating both lean and rich aqueous phases. In this study, a novel sponge-like ionic liquid extraction process was employed to recover 1-butanol from these aqueous mixtures using 1-Methyl-3-octadecylimidazolium bis(trifluoromethyl sulfonyl)imide (C18MIM[Tf2N]). The liquid C18MIM[Tf2N] was contacted with a rich and lean butanol aqueous phases at temperatures above IL´s melting point (60 °C to 90 °C) and an IL/aqueous ratio of 1:1. After phase separation, the IL solidified at room temperature, allowing the extraction of the dissolved component via centrifugation.
The results indicated that optimal recovery from the lean phase occurred at 80 °C, achieving enhanced solubility of 1-butanol in the IL while minimizing losses. Under these conditions, the remaining aqueous phase contained only 1 wt% 1-butanol, and over 95 % of the butanol was recovered from the IL. For the rich phase, high butanol concentrations altered the hydrophobicity of C18MIM[Tf2N], causing water retention and resulting in an aqueous phase with a higher butanol content. These findings highlight the potential of sponge-like IL extraction for efficient butanol purification, reducing energy-intensive distillation steps
3D Carrollian gravity from 2D Euclidean symmetry
Get PDFCarroll symmetry arises from Poincaré symmetry when the speed of light is sent to zero. In this work, we apply the Lie algebra expansion method to find the Carroll versions of different gravity models in three space-time dimensions. Our starting point is the 2D Euclidean AdS algebra along with its flat version. Novel and already known Carrollian algebras, such as the AdS-Carroll and Carroll–Galilei ones are found, and the Chern–Simons gravity theories based on them are constructed. Remarkably, after the expansion, the vanishing cosmological constant limit applied to the 2D Euclidean AdS algebra converts into a non-relativistic limit in three space-time dimensions. We extend our results to Post-Carroll–Newtonian algebras which can be found by expanding a family of 2D Euclidean algebras
Exact charged and rotating toroidal black hole in the () Einstein-Skyrme model
No full textIn this paper, we construct an exact solution of the () Einstein-Skyrme model in =4 space-time dimensions describing a charged and rotating black hole with toroidal horizon. Rotation is added by applying an improper coordinate transformation to the known static toroidal black hole with Skyrme hair, while the electric charge is supplemented by considering a (1) gauge field interacting with Einstein gravity. We perform the thermal analysis in the grand canonical ensemble, explicitly showing the role that the flavor number plays. Some discussions about stability are also considered