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Identifying a minimum time period of streamflow recession records to analyze the behavior of groundwater storage systems: A study in heterogeneous Chilean watersheds
Get PDFAquifers are complex systems that present significant challenges in terms of characterization due to the lack or absence of watershed-scale hydrogeological information. An alternative to address the need to characterize watershed-scale aquifer behavior is recession flow analysis. Recession flows are flows sustained by groundwater release from the aquifer. Aquifer behavior can be characterized using recession flow records available from gauging stations, and therefore an indirect measure of aquifer behavior is obtained through watershed-scale recession flow records and analysis. This study seeks to identify the minimum time period necessary to characterize the behavior of groundwater storage systems in watersheds with different geological, morphological, and hydrological characteristics. To this end, various watersheds in south-central Chile underwent recession flow analysis, with eight time periods considered (2, 3, 4, 5, 10, 15, 20, and 25 years). The results indicate that 25 years of records are sufficient for the characterization of watershed-scale aquifer behavior, along with the representation of the groundwater storage-release (S-Q) process in watersheds with different geological, morphological, and hydrological characteristics. Additionally, the results show that an initial characterization of the groundwater system behavior in watersheds with different geological characteristics can be carried out with two years of records. This information could be important for practical engineering and the study of groundwater systems in watersheds with limited hydrological and hydrogeological information
The zero-debt puzzle in BRICS countries: Disentangling the financial flexibility and financial constraints hypotheses
Get PDFThis study analyzes the zero-debt decisions of BRICS firms using a bivariate probit model. The leading hypotheses are financial flexibility and financial constraints. On the demand-side, our findings reveal that managerial debt aversion, early lifecycle stage, growth opportunities, solvency, and concentrated ownership contribute to the lack of debt. Similarly, a country's institutional quality correlates with firms' debt-free status. On the supply-side, creditors fund companies with poor financial records in countries with robust markets and economic freedom. Financial flexibility and restrictions leading to zero debt are linked to firm and institutional characteristics in emerging countries
Development of physical fitness through simulation exercises for ski racers aged 13-14. Non-randomized quasi-experimental study
Get PDFIntroducción. En las últimas décadas, el nivel de rendimiento del esquí en Rusia ha disminuido significativamente. Esto plantea nuevos desafíos en la preparación de los atletas para las competiciones y el proceso de entrenamiento.
Objetivo. Analizar los efectos de las herramientas de entrenamiento por simulación sobre la condición física de corredores de esquí de entre 13 y 14 años.
Métodos. Estudio cuasiexperimental, no aleatorizado. 40 esquiadores de fondo de entre 13 y 14 años pertenecientes a la escuela deportiva Korshik Village (Rusia) fueron asignados a un grupo control (n=20) y experimental (n=20). Las clases en el grupo de control se llevaron a cabo según el plan de entrenamiento habitual y en el grupo experimental se utilizaron ejercicios de simulación. Las pruebas de control incluyen dominadas, sentadillas, salto de longitud con dos piernas, escalada simulada de 100 metros y una prueba de carrera de 500 metros.
Resultados. El grupo control no presentó mejoras significativas (p>0,05), mientras que el grupo experimental reportó mejoras significativas en dominadas (22,2%; p<0,05), sentadilla (5,9%; <0,05), salto de longitud a dos piernas (6,8%; <0,05), simulación de escalada de 100 metros (7,8%; <0,05) y carrera de 500 metros (4,2%; p<0,05).
Conclusión. Si en el periodo preparatorio se incluye una serie de ejercicios de simulación en el programa de entrenamiento para esquiadores de 13-14 años, el nivel de condición física de los deportistas mejorará significativamente
Praseodymium doping-induced band structure tunning in bismuth ferrite (Bi1-Pr FeO3) nanofibers for the enhanced photocatalytic properties
No full textThe study investigates the influence of praseodymium (Pr) doping on bismuth ferrite (BiFeO3/BFO) nanofibers and their structural, morphological, magnetic, optical, and photocatalytic properties. A series of bismuth ferrite nanofibers with varying concentration of Pr (Bi1-xPrxFeO3, x = 0.00, 0.05, 0.10, and 0.15 mol%) were successfully synthesized using an electrospinning technique. XRD patterns revealed that structural transformation occurred from rhombohedral to orthorhombic upon effective doping of Pr3+ into BFO nanofibers. The X-ray photoelectron spectroscopy analysis confirmed that Bi, Fe, and O maintained their native oxidation states of +3 and -2, respectively in the bare and doped systems. Furthermore, the optical band gap value was significantly reduced from 2.35 to 2.22 eV as well as the recombination rates of charge carriers in the doped systems, especially in BP0.15O system. The photocatalytic performance of the prepared samples was studied by measuring the decomposition of rhodamine B (RhB) under sunlight irradiation. Outcomes showed that the doped-BFO nanofibers exhibited enhanced photocatalytic performance compared to pure BFO, with the BP0.15O system showing the 98 % degradation in 60 min. This enhancement could be attributed to the presence of Pr-energy levels, which facilitating enhanced separation, and charge transfer to the surface for the effective redox reactions
Which one is your team? Supraordinate identity around the classic match
Get PDFObjective: The article analyzes up to what extent the supraordinate identity made up by the classic match, influences fans’ consumption intention of media and official merchandise, through a justifiability mediation, while assessing a moderation effect that an identity threat has on the proposed model.
Method: The phenomenon was tested through structural equation modeling on a 439 fanbase sample. Participants are fans from both of the clubs who play the Classic match of their league and were randomly allocated into a threat circumstance or a control situation in order to test the identity threat moderation effect.
Results: Findings suggest that this supraordinate identity has a positive impact on media and merchandise consumption intentions, while legitimacy and permeability forecast its existence. These results argue that fans from both teams experience an identity threat either when their club is under menace and when their rival is.
Conclusion: This is the first article examining a supraordinate identity fabricated by salient rivalries, which is counterintuitive, and how these individuals experience an identity threat when their rival is at risk. The Classic denotes an important marketing instrument, where leagues and clubs can develop stories and rivalries to attract broader audiences
Comparative analysis of motor coordination and Body Mass Index in schoolchildren who participate only in physical education classes and extracurricular sports
Get PDFEl estudio tuvo como objetivo comparar la coordinación motora y el Índice de Masa Corporal en escolares que participan solo en las clases de educación física con aquellos que además participan de talleres deportivos extraescolares. El estudio fue transversal, de alcance descriptivo y comparativo. La muestra estuvo compuesta por 96 escolares (41 niñas y 55 niños de 11.7± 0.7 años). Se midieron la talla y el peso corporal. Se calculó el Índice de Masa Corporal (IMC). La evaluación de la coordinación motora se llevó a cabo utilizando la batería de Körperkoordinations test Für Kinder (KTK). Los resultados revelaron diferencias significativas entre el Grupo Deporte Extraescolar (GDEX) y el Grupo Educación Física (GEF), en Saltos Monopedales, Transposición Lateral, puntaje total KTK (p<0.01) y Saltos Laterales (p<0.05), con un tamaño del efecto (TE) moderado (d= 0.40 a 0.66). Igualmente, los escolares del GDEX mostraron mejores valores con respecto al GEF en Peso corporal (p<0.05), e IMC (p<0.01), TE moderado (d= -0.49 y -0.54; respectivamente). Se concluye que los escolares que participan en talleres deportivos extraescolares presentan mejores niveles de coordinación motora, IMC y Peso corporal que aquellos que únicamente participan de las clases de educación física
Citrate-buffered Yamanaka medium allows to produce high-yield bacterial nanocellulose in static culture using Komagataeibacter strains isolated from apple cider vinegar
Get PDFBacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%–98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L−1 d−1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems
Enlarged super-3 algebra and its flat limit
No full textIn this paper we analyze the asymptotic symmetries of the three-dimensional Chern-Simons supergravity for a supersymmetric extension of the semisimple enlargement of the Poincaré algebra, also known as AdSLorentz superalgebra, which is characterized by two fermionic generators. We propose a consistent set of asymptotic boundary conditions for the aforementioned supergravity theory, and we show that the corresponding charge algebra defines a supersymmetric extension of the semisimple enlargement of the bms3 algebra, with three independent central charges. This asymptotic symmetry algebra can alternatively be written as the direct sum of three copies of the Virasoro algebra, two of which are augmented by supersymmetry. Interestingly, we show that the flat limit of the obtained asymptotic algebra corresponds to a deformed super-bms3 algebra, being the charge algebra of the minimal Maxwell supergravity theory in three dimensions
Level of complexity in the implementation of emerging technologies used in educational research in K 12: Latin American literature’ systematic review
Get PDFintroducción: La integración de tecnologías emergentes en educación es importante en la sociedad del siglo XXI. Sin embargo, existen múltiples investigaciones donde se integran tecnologías y, pese a esto, no hay cambios sustanciales en las aulas latinoamericanas.
Método: El objetivo de esta revisión sistemática fue analizar investigaciones publicadas en revistas de alto impacto donde se integren tecnologías emergentes en contextos escolares con el fin de determinar la complejidad investigativa. La búsqueda se realizó en mayo de 2022 utilizando el método PRISMA para la selección de 20 artículos latinoamericanos publicados entre 2018 a 2022. Como criterio de inclusión se consideraron artículos empíricos publicados en bases de datos WOS, Scopus y ProQuest, donde se haya aplicado alguna intervención en escolares utilizando tecnologías emergentes.
Resultados: Los hallazgos muestran gran variedad de tecnologías utilizadas en diversas áreas académicas, donde el nivel de complejidad en los estudios es de adquisición y profundización de conocimiento y donde los estudiantes tuvieron un rol de usuarios individuales durante las investigaciones.
Conclusión: Se concluye que debe haber un cambio de enfoque en las futuras investigaciones para generar una mejor integración de tecnologías emergentes y un cambio profundo en las aulas de clases latinoamericanas