Repositorio Institucional UCSC (Univ. Católica de la Santísima Concepción)
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Graduating college students apply here: Communicating family firm ownership and firm size
No full textAttracting business college graduates is a major challenge for the growth and transgenerational success of family firms. Moreover, the institutional context of countries is critical in explaining family firms’ potential advantages and/or disadvantages in attracting nonfamily talent. This study aims to elucidate how communicating firm ownership (family vs. nonfamily), firm size (large vs. small), and type of job offered (professional vs. nonprofessional) influences the perceptions and attitudes of Latin American business graduates toward working in such firms. In an experimental study that uses job advertisement stimuli, we found that communicating family ownership positively influences career development’s perceptions of firm prestige. Large (vs. small) firm size also has a positive influence on job seekers’ perceptions of firms. Importantly, both firm prestige and career development positively influence the attraction of working in family firms. In this paper, we discuss the differences in the results among countries and professional vs. nonprofessional job positions advertised. The results have several implications for family firm owners and managers
Information management in social media to promote engagement and physical activity behavior
Get PDFSocial media can be an effective tool to foster values and lifestyles such as physical activity. However, it is still largely unknown what type of social media information helps to promote physical activity practices. This research aims to (1) identify the combination of variables that explain social media engagement in physical activity (SME-PA) and its relationship with physical activity behavior and (2) determine what type of social media content posted on social media could be most effective in promoting physical activity behaviors. Using a quasi-experimental and an experimental study, the findings showed that the conditions of high levels of information availability, social ties, trust in social media information, and opportunity seeking were present and combined in three of the four solutions (77% of the cases). SME-PA was correlated with the intention to improve physical fitness, and the physical shape, the type of benefit associated with physical activity practice and the gender of the person in the photo practicing physical activity were found to be relevant variables for improving the physical activity-related behavior of social media users. Finally, several implications are proposed to improve the administration of social media content for SME-PA
Spatial and temporal variation of giant kelp, Macrocystis pyrifera, measured from distribution modeling and remote sensing in Chile
Get PDFWorldwide climate-driven shifts in the distribution of species are of special concern when it involves habitat-forming species. In the coastal environment, large Laminarian algae—kelps—form key coastal ecosystems that support complex and diverse food webs. Among kelps, Macrocystis pyrifera is the most widely distributed habitat-forming species and provides essential ecosystem services. The Chapter 1 of this thesis aimed to establish the main drivers of future distributional changes on a global scale and use them to predict future habitat suitability. Using species distribution models (SDM), we examined the changes in global distribution of M. pyrifera under different emission scenarios with a focus on the Southeast Pacific shores. To constrain the drivers of our simulations to the most important factors controlling kelp forest distribution across spatial scales, we explored a suite of environmental variables and validated the predictions derived from the SDMs. Minimum sea surface temperature was the single most important variable explaining the global distribution of suitable habitat for M. pyrifera. Under different climate change scenarios, we always observed a decrease of suitable habitat at low latitudes, while an increase was detected in other regions, mostly at high latitudes. Along the Southeast Pacific, we observed an upper range contraction of −17.08° S of latitude for 2090–2100 under the RCP8.5 scenario, implying a loss of habitat suitability throughout the coast of Peru and poleward to −27.83° S in Chile. Along the area of Northern Chile where a complete habitat loss is predicted by our model, natural stands are under heavy exploitation. The loss of habitat suitability will take place worldwide: Significant impacts on marine biodiversity and ecosystem functioning are likely. Furthermore, changes in habitat suitability are a harbinger of massive impacts in the socio-ecological systems of the Southeast Pacific.
In Chile, a leading kelp exporter, understanding the dynamics of kelp populations is crucial for sustainable management. The extensive and rugged coastline makes monitoring challenging, but remote sensing offers an effective solution for large-scale observation and management of these essential marine ecosystems. The Chapter 2 of this thesis aims to establish patterns of variation in the surface cover of a M. pyrifera forest off Central Chile by linking satellite observations of decadal and seasonal cover with field data and public repositories. Our 23-year time series of a M. pyrifera forest in Central Chile reveals typical year-to-year area fluctuations without discernible trends and no significant association with the El Niño-Southern Oscillation. Furthermore, the seasonal time series using Sentinel-2 data and the NDREB index demonstrated clear seasonal patterns with summer peaks and winter troughs, influenced by local environmental variables such as temperature, nitrate, silicate, and solar radiation. Understanding the seasonality and variables influencing these underwater forests is crucial for the future conservation of these ecosystems and underscores the potential of remote sensing for monitoring extensive and remote coastlines.
This thesis has helped to unveil how the interlinked contributions of environmental variability and climatic oscillations shape the spatio-temporal patterns in global/regional habitat suitability and local seasonal dynamics of M. pyrifera populations. By integrating scientific findings with proactive conservation measures, we can enhance resilience and ensure the future of this crucial habitat
The role of Epithelial-to-Mesenchymal Transition Transcription Factors (EMT-TFs) in acute myeloid Leukemia progression
Get PDFAcute myeloid leukemia (AML) is a diverse malignancy originating from myeloid progenitor cells, with significant genetic and clinical variability. Modern classification systems like those from the World Health Organization (WHO) and European LeukemiaNet use immunophenotyping, molecular genetics, and clinical features to categorize AML subtypes. This classification highlights crucial genetic markers such as FLT3, NPM1 mutations, and MLL-AF9 fusion, which are essential for prognosis and directing targeted therapies. The MLL-AF9 fusion protein is often linked with therapy-resistant AML, highlighting the risk of relapse due to standard chemotherapeutic regimes. In this sense, factors like the ZEB, SNAI, and TWIST gene families, known for their roles in epithelial–mesenchymal transition (EMT) and cancer metastasis, also regulate hematopoiesis and may serve as effective therapeutic targets in AML. These genes contribute to cell proliferation, differentiation, and extramedullary hematopoiesis, suggesting new possibilities for treatment. Advancing our understanding of the molecular mechanisms that promote AML, especially how the bone marrow microenvironment affects invasion and drug resistance, is crucial. This comprehensive insight into the molecular and environmental interactions in AML emphasizes the need for ongoing research and more effective treatments
Effects of 32 weeks of a muscular strength physical training program on the physical condition of Russian children aged 14 to 16 years: Randomized Controlled Trial
Get PDFIntroducción: El entrenamiento de la fuerza muscular ofrece la oportunidad de resolver eficazmente problemas pedagógicos causados por una variedad de actividades motoras.
Objetivo: Analizar los efectos de un programa de 32 semanas de fuerza muscular sobre estudiantes de entre 14 a 16 años.
Métodos: Ensayo controlado, paralelo y aleatorizado con cegado simple. La muestra estuvo compuesta por 40 escolares de 14 a 16 años pertenecientes a la escuela secundaria N.º 1 (Sokolovka, Rusia). Los escolares fueron divididos en un grupo control (n = 20) y un grupo experimental (n = 20); Ambos grupos realizaron las lecciones de educación física de acuerdo con el plan de estudios escolar, sin embargo, el grupo experimental también realizó ejercicios de fuerza muscular. El nivel de fuerza se determinó con pruebas de dinamometría de mano derecha e izquierda, flexoextensiones de brazos (barra y suelo) y elevación de piernas colgantes.
Resultados: El grupo experimental mejoro la dinamometría de mano derecha (21,9%; p < 0,05; d = 6,61) e izquierda (14,7%; p < 0,05; d = 4,93), elevación de piernas colgado de una barra (81,4%; p < 0,05; d = 9,09) flexo extensión de brazos en suelo (5,8%; p < 0,05; d = 5,99) y en barra (38,3%; p < 0,05), mientras que el grupo control solo mejoro significativamente la dinamometría de la mano derecha (21,3%; p < 0,05) y la elevación de piernas colgado de una barra (15,1%; p < 0,05; d = 5,76).
Conclusión: Una serie de ejercicios de fuerza muscular aplicado durante 32 semanas en las lecciones de educación física escolar pueden mejorar significativamente los niveles de fuerza muscular en niños de 14 a 16 años
The SOPHIE search for northern extrasolar planets. XIX. A system including a cold sub-Neptune potentially transiting a V = 6.5 star HD 88986
Get PDFTransiting planets with orbital periods longer than 40 d are extremely rare among the 5000+ planets discovered so far. The lack of discoveries of this population poses a challenge to research into planetary demographics, formation, and evolution. Here, we present the detection and characterization of HD 88986 b, a potentially transiting sub-Neptune, possessing the longest orbital period among known transiting small planets (<4 R⊕) with a precise mass measurement (σM/M > 25%). Additionally, we identified the presence of a massive companion in a wider orbit around HD 88986. To validate this discovery, we used a combination of more than 25 yr of extensive radial velocity (RV) measurements (441 SOPHIE data points, 31 ELODIE data points, and 34 HIRES data points), Gaia DR3 data, 21 yr of photometric observations with the automatic photoelectric telescope (APT), two sectors of TESS data, and a 7-day observation of CHEOPS. Our analysis reveals that HD 88986 b, based on two potential single transits on sector 21 and sector 48 which are both consistent with the predicted transit time from the RV model, is potentially transiting. The joint analysis of RV and photometric data show that HD 88986 b has a radius of 2.49 ± 0.18 R⊕, a mass of 17.2−3.8+4.0 M⊕, and it orbits every 146.05−0.40+0.43 d around a subgiant HD 88986 which is one of the closest and brightest exoplanet host stars (G2Vtype, R = 1.543 ± 0.065 R⊙, V = 6.47 ± 0.01 mag, distance = 33.37 ± 0.04 pc). The nature of the outer, massive companion is still to be confirmed; a joint analysis of RVs, HIPPARCOS, and Gaia astrometric data shows that with a 3σ confidence interval, its semi-major axis is between 16.7 and 38.8 au and its mass is between 68 and 284 MJup. HD 88986 b’s wide orbit suggests the planet did not undergo significant mass loss due to extreme-ultraviolet radiation from its host star. Therefore, it probably maintained its primordial composition, allowing us to probe its formation scenario. Furthermore, the cold nature of HD 88986 b (460 ± 8 K), thanks to its long orbital period, will open up exciting opportunities for future studies of cold atmosphere composition characterization. Moreover, the existence of a massive companion alongside HD 88986 b makes this system an interesting case study for understanding planetary formation and evolution
Revisiting the concept of space in urban mobility: from positivism to the subject's experience of space
Get PDFLos estudios urbanos han comprendido la movilidad desde diversos y complejos puntos de vista y objetos de estudio. Sin embargo, dada la naturaleza inter-disciplinaria del concepto y su compleja historia de enfoques, se ha dificultado la comprensión y la resolución de las problemáticas urbanas. Esto ha impedido sentar las bases de una disciplina esen-cial para la comprensión de la ciudad. Específicamente, la literatura comprende la movilidad como parte de la ciudad, sin embargo, ha variado la forma de entender el espacio de la ciudad y, por tanto, esa movilidad puede ser tradicionalmente categorizada de diferentes maneras. El presente documento se enmarca en esta problematización para aportar a la construcción de un marco teórico a partir de la revisión del concepto de espacio en la movilidad urbana. Mediante una metodología de revisión de literatura narrativa y cualitativa que se desarrolla mediante los siguientes motores de búsqueda: i) movilidad urbana; ii) espacio urbano; iii) historia de la movilidad y iv) estructura urbana. Los resultados relevan el rol del entorno construido y la movilidad en la noción de ciudad desde una visión positivista hacia otras visiones en tanto objeto espacial, sistema o dialéctica. Es posible observar que la movilidad, más allá de considerarse un sinónimo de vencer una distancia en el espacio, puede abordarse, además, desde su dimensión potencial, también conocida como capital de movilidad o la capacidad para ser móvil en el territorio. En esta oportunidad, el rol de la configuración del entorno construido junto a teorizaciones del capital de movilidad puede dar lugar a una comprensión del aprovechamiento socialmente diferenciado del territorio y las oportunidades –o barreras– creadas para la co-presencia y el encuentro en los espacios públicos
Integration of Slurry–Total Reflection X-ray fluorescence and machine learning for monitoring arsenic and lead contamination: Case study in Itata valley agricultural soils, Chile
Get PDFThe accuracy of determining arsenic and lead using the optical technique Slurry–Total Reflection X-ray Fluorescence (Slurry-TXRF) was significantly enhanced through the application of a machine learning method, aimed at improving the ecological risk assessment of agricultural soils. The overlapping of the arsenic Kα signal at 10.55 keV with the lead Lα signal at 10.54 keV due to the relatively low resolution of TXRF could compromise the determination of lead. However, by applying a Partial Least Squares (PLS) machine learning algorithm, we mitigated interference variations, resulting in improved selectivity and accuracy. Specifically, the average percentage error was reduced from 15.6% to 9.4% for arsenic (RMSEP improved from 5.6 mg kg−1 to 3.3 mg kg−1) and from 18.9% to 6.8% for lead (RMSEP improved from 12.3 mg kg−1 to 5.03 mg kg−1) compared to the previous univariable model. This enhanced predictive accuracy, within the set of samples concentration range, is attributable to the efficiency of the multivariate calibration first-order advantage in quantifying the presence of interferents. The evaluation of X-ray fluorescence emission signals for 26 different synthetic calibration mixtures confirmed these improvements, overcoming spectral interferences. Additionally, the application of these models enabled the quantification of arsenic and lead in soils from a viticultural subregion of Chile, facilitating the estimation of ecological risk indices in a fast and reliable manner. The results indicate that the contamination level of these soils with arsenic and lead ranges from moderate to considerable
Simulating the detection of the global 21 cm Signal with MIST for different models of the soil and beam directivity
Get PDFThe Mapper of the IGM Spin Temperature (MIST) is a new ground-based, single-antenna, radio experiment attempting to detect the global 21 cm signal from the Dark Ages and Cosmic Dawn. A significant challenge in this measurement is the frequency dependence, or chromaticity, of the antenna beam directivity. MIST observes with the antenna above the soil and without a metal ground plane, and the beam directivity is sensitive to the electrical characteristics of the soil. In this paper, we use simulated observations with MIST to study how the detection of the global 21 cm signal from Cosmic Dawn is affected by the soil and the MIST beam directivity. We simulate observations using electromagnetic models of the directivity computed for single- and two-layer models of the soil. We test the recovery of the Cosmic Dawn signal with and without beam chromaticity correction applied to the simulated data. We find that our single-layer soil models enable a straightforward recovery of the signal even without chromaticity correction. Two-layer models increase the beam chromaticity and make the recovery more challenging. However, for the model in which the bottom soil layer has a lower electrical conductivity than the top layer, the signal can be recovered even without chromaticity correction. For the other two-layer models, chromaticity correction is necessary for the recovery of the signal, and the accuracy requirements for the soil parameters vary between models. These results will be used as a guideline to select observation sites that are favorable for the detection of the Cosmic Dawn signal
Perceptions and characteristics of adult physical activity during the pandemic. A case study in Chile
Get PDFLa pandemia del COVID-19 modificó los estilos de vida de la población mundial, debido a las medidas de confinamiento para reducir la actividad social masiva. Esto aumentó los niveles de inactividad física y sus riesgos para la salud. Por ello, el Ministerio de Salud de Chile estableció una banda horaria exclusiva para la práctica de actividad física. Los objetivos del estudio fueron conocer las percepciones de los usuarios y las características de la actividad física realizada durante la banda horaria. Se empleó un enfoque interpretativo, de diseño cualitativo, mediante un estudio de caso, con una entrevista personal y presencial. El instrumento fue un guion semiestructurado, aplicado a once sujetos adultos de ambos sexos, con edades entre los 24 y 69 años, que realizaban actividad física en un parque de la ciudad de Concepción, Chile, durante el año 2021. Los resultados indican que las personas realizaban actividades físicas por placer, para cuidar la salud y socializar, y reportaron sentirse con energía durante el día. Manifestaron un alto nivel de satisfacción con esta medida y una alta motivación hacia la práctica de actividad física, pero sugirieron ampliar el horario de la mañana e introducir una nueva banda en la tarde. Por otro lado, realizaron actividades físicas preferiblemente grupales, de cuatro a siete veces por semana, y de una a dos horas de duración. En conclusión, las percepciones hacia la banda horaria fueron positivas, y las características de las prácticas físicas contribuyeron significativamente a mejorar la salud y el bienestar durante el confinamiento