Universidad de Magallanes
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Prognostic Value of Consolidation in Lung Tomography in Patients With Acute Respiratory Distress Syndrome
No full textIMPACTO DE LA APLICACIÓN DEL ENFOQUE BASADO EN COMPETENCIAS EN EL RENDIMIENTO ACADÉMICO DE LOS ALUMNOS DE UNA UNIVERSIDAD ESTATAL CHILENA
No full textObjetivo: El objetivo de esta investigación fue analizar los efectos de la aplicación del enfoque basado en competencias en el rendimiento universitario, a través tres indicadores, las tasas de retención, titulación y aprobación; realizando un estudio comparativo histórico.
 
 Marco Teórico: El enfoque basado en competencias se describe a partir de la Declaración de Bolonia, que plantea un diseño de planes de estudios que permiten modernizar el proceso de enseñanza aprendizaje, en forma continuo y capaz de responder a un nuevo paradigma educativo basado en el aprendizaje centrado en el estudiante.
 
 Metodología: Se utilizó un análisis descriptivo, el estudio comprendió una comparación entre las cohortes 2009-2013 y 2014-2018. Además, se calcularon las tendencias lineales y se realizó un análisis de correlación.
 
 Resultado: Los resultados evidencian que la tasa de aprobación ha mejorado con la aplicación de los nuevos planes de estudios, pero, no ocurre lo mismo con las tasas de retención y titulación, que están condicionadas, principalmente, por factores distintos al diseño curricular.
 
 Investigación, Implicaciones Prácticas y Sociales: Este estudio deja de manifiesto que el rendimiento académico no solo está afectado por el enfoque pedagógico aplicado, también inciden otros factores, como la situación socioeconómica de los alumnos, dualidad trabajo y estudio, las normativas de titulación y la integración social, entre otros.
 
 Originalidad/Valor: Este estudio permite visualizar, en forma exploratoria, que la calidad de la docencia no solo se mide en función de los rendimientos académicos y que los diseños curriculares son un medio y no un fin en la formación professional
Tree cavity density is a limiting factor for a secondary cavity nester in second-growth Andean temperate rainforests
No full textCavity-nesting bird populations are most frequently limited by the number of tree cavities available in second-growth forests. However, this possible limitation of a key resource is less clear in old-growth forests. We compared forest attributes (i.e., basal area, density of larger trees, density of dead trees, and tree cavity density) in second-growth and old-growth stands in Andean temperate rainforests in southern Chile. To examine the role of nest-site availability in limiting the populations of Aphrastura spinicauda (Thorn-Tailed Rayadito), we monitored their populations in both forest types during a 5-year period (2008-2013), while we conducted an experiment in which nest boxes were added and then, after two years, removed by blocking cavity entrances. In old-growth forests, as compared to second-growth forests, we found a more than double basal area (99.6 vs. 43.7 m2 ha-1), a 3 times higher density of larger trees (88.2 vs. 36.4 trees ha-1), and a 1.5 times higher number of small cavities (25.9 vs. 10.3 cavities ha-1). The density of cavities also strongly increased with tree diameter and basal area. In second-growth forests, A. spinicauda showed a strong response to the addition, and later to the removal of nest boxes, with population abundance increasing by 13% and then decreasing by 50%, respectively. In contrast, we found no impact on old-growth stands. Our experiment emphasizes the importance of maintaining large and dead trees in second-growth, disturbed, and managed forests. These trees provide suitable cavities for A. spinicauda, and likely many other secondary cavity nesters, increasing their abundance in a Globally significant Biodiversity Hotspot in southern South America. A Spanish translation of this manuscript is available as Supplementary Material. center dot Cavity availability is considered a limiting factor, potentially regulating the breeding population density of avian cavity nesters.center dot We compared forest attributes in second-growth and old-growth stands and assessed the role of nest-site availability in limiting populations of Aphrastura spinicauda (Thorn-Tailed Rayaditos) in Andean temperate rainforests in southern Chile.center dot We conducted an experiment in which nest boxes were added and removed in both forest types during a 5-year period (2008-2013).center dot In old-growth forests compared to second-growth forests, we found 2.3 times higher basal area, 2.4 times higher density of larger trees, and a 2.5 times higher number of small cavities.center dot In second-growth forests, A. spinicauda populations increased by 13% after the nest box addition, and then decreased by 50% after removal, in contrast to no change in old-growth forests.center dot Our findings highlight the importance of maintaining larger trees that provide suitable cavities for this species in second-growth forests. Las poblaciones de aves que nidifican en cavidades están frecuentemente limitadas por el número de cavidades disponibles en bosques de crecimiento secundario. Sin embargo, esta posible limitación de este recurso clave es menos clara en bosques antiguos. Comparamos los atributos del bosque (i.e.,área basal, densidad deárboles grandes, densidad deárboles muertos y densidad de cavidades deárboles) en bosques templados andinos de crecimiento secundario y antiguo del sur de Chile. Para examinar el rol de la disponibilidad de sitios de nidificación en la limitación de poblaciones de Aphrastura spinicauda, monitoreamos sus poblaciones en ambos tipos de bosques durante un periodo de 5 años (2008-2013), mientras realizamos un experimento en el que se agregaron cajas nido y, luego de dos años, se removieron bloqueando la entrada. En los bosques antiguos, en comparación con los bosques de crecimiento secundario, encontramos unárea basal de más del doble (99.6 vs. 43.7 m2 ha-1), una densidad deárboles grandes tres veces mayor (88.2 vs. 36.4árboles ha-1) y un número de cavidades pequeñas 1.5 veces mayor (25.9 vs. 10.3 cavidades ha-1). La densidad de cavidades también aumentó fuertemente con el diámetro de losárboles y elárea basal. En los bosques de crecimiento secundario, A. spinicauda mostró una fuerte respuesta a la adición y subsecuente eliminación de cajas nido, con un aumento en la abundancia poblacional del 13% y luego una disminución del 50%, respectivamente. En contraste, no encontramos impacto en los bosques antiguos. Nuestro experimento enfatiza la importancia de mantenerárboles grandes y muertos en los bosques de crecimiento secundario, degradados y/o manejados. Estosárboles proporcionan cavidades adecuadas para A. spinicauda, y probablemente para muchas otras aves que se reproducen en estas, aumentando sus abundancias en un bosque prioritario para la conservación de biodiversidad a nivel mundial en el cono sur de Sudamérica. Una versión en español de este manuscrito está disponible como material suplementario
Both high and low dispersal? Apparently contradictory genetic patterns in the Antarctic littorinid gastropod Laevilacunaria antarctica
No full textHow the near-shore marine benthic communities survived Quaternary glaciations in Antarctica is a major question for Southern Ocean biogeographers. Several hypotheses that consider life-history traits, such as bathymetric ranges and developmental modes, have been proposed. Near-shore species with high dispersive potential are expected to show star-like genealogies, with broadly distributed haplotypes surrounded by closely related variants at low frequencies, a consequence of rapid population post-glacial expansion mediated by larvae. By contrast, shallow-water taxa with low dispersal potential are expected to evidence marked genetic structure or even consist of separate cryptic species, due to their survival in small refugial populations subject to repeated bottlenecks. In this study we performed phylogeographic analyses on the high-latitude littorinid Laevilacunaria antarctica across its distribution from maritime Antarctica to South Georgia. This species is a highly abundant near-shore gastropod, commonly found on macroalgae, with low autonomous vagility and exhibits benthic protected development with no free-living dispersive stages. Such characteristics make this species a suitable model to test the above hypotheses. Contrary to low dispersal potential predictions, L. antarctica comprises a single unstructured unit across its distribution in maritime Antarctica, exhibiting a typical high-dispersal star-like, short-branched genealogy centered on a dominant broadly distributed haplotype. The South Georgia population, however, consists of a separate genetic unit, strongly differentiated from those of the maritime Antarctic. We estimate that these two genetic groups separated similar to 1.2 My, long before the Last Glacial Maximum and evolved independently in these areas. Our results thus provide partial support for the expected pattern for a near-shore marine benthic species with low innate dispersive potential. On a wider geographic scale (maritime Antarctica vs South Georgia), our results in L. antarctica provide support for the expected pattern for a near-shore marine benthic species with low innate dispersive potential. However, on a narrower scale (maritime Antarctica) life-history characters including the close association of the species with macroalgae, would allow dispersal and a species with low dispersal potential exhibits paradoxically an absence of genetic structure across hundreds of kilometers probably mediated by rafting
How Protein Depletion Balances Thrombosis and Bleeding Risk in the Context of Platelet's Activatory and Negative Signaling
No full textPlatelets are small cell fragments that play a crucial role in hemostasis, requiring fast response times and fine signaling pathway regulation. For this regulation, platelets require a balance between two pathway types: the activatory and negative signaling pathways. Activatory signaling mediators are positive responses that enhance stimuli initiated by a receptor in the platelet membrane. Negative signaling regulates and controls the responses downstream of the same receptors to roll back or even avoid spontaneous thrombotic events. Several blood-related pathologies can be observed when these processes are unregulated, such as massive bleeding in activatory signaling inhibition or thrombotic events for negative signaling inhibition. The study of each protein and metabolite in isolation does not help to understand the role of the protein or how it can be contrasted; however, understanding the balance between active and negative signaling could help develop effective therapies to prevent thrombotic events and bleeding disorders
Orbital modulation of subtropical versus subantarctic moisture sources in the southeast Pacific mid-latitudes
No full textReconstructing rainfall variability and moisture sources is a critical aspect to understand past and future hydroclimate dynamics. Here, we use changes in the deuterium content of land-plant leaf waxes from two marine sediment cores located off Chile to reconstruct changes in rainfall amount and variation in moisture sources over the last ~50 ka. The records indicate increased moisture in central Chile during precession maxima, but an obliquity modulation is evident in southern Chile. While the southern westerly winds are the dominant factor of precipitation in southern Chile by bringing moisture and perturbations from the extratropics, the subtropics represent an additional moisture source during precession maxima due to a stronger subtropical jet increasing moisture transport from the tropics to the mid-latitudes. These findings imply that a combination of orbital modulation of moisture sources and rainfall amount explains the last glacial moisture maximum and early Holocene moisture minimum in south-central Chile
Baroreflex and chemoreflex interaction in high-altitude exposure: possible role on exercise performance
No full textThe hypoxic chemoreflex and the arterial baroreflex are implicated in the ventilatory response to exercise. It is well known that long-term exercise training increases parasympathetic and decreases sympathetic tone, both processes influenced by the arterial baroreflex and hypoxic chemoreflex function. Hypobaric hypoxia (i.e., high altitude [HA]) markedly reduces exercise capacity associated with autonomic reflexes. Indeed, a reduced exercise capacity has been found, paralleled by a baroreflex-related parasympathetic withdrawal and a pronounced chemoreflex potentiation. Additionally, it is well known that the baroreflex and chemoreflex interact, and during activation by hypoxia, the chemoreflex is predominant over the baroreflex. Thus, the baroreflex function impairment may likely facilitate the exercise deterioration through the reduction of parasympathetic tone following acute HA exposure, secondary to the chemoreflex activation. Therefore, the main goal of this review is to describe the main physiological mechanisms controlling baro- and chemoreflex function and their role in exercise capacity during HA exposure
Umbrales estimados (esdB HL) para potenciales evocados auditivos con estímulo Narrow Band CE-Chirp®
No full textABSTRACT Purpose: to correlate pure-tone audiometry thresholds with electrophysiological thresholds, using NB CE-Chirp® stimuli in listeners aged 18 to 30 years from Santiago, Chile, and determine the estimated threshold at 500, 1000, 2000, and 4000 Hz. This can contribute to the battery of objective and subjective tests applicable to children, aiding the timely detection and implementation before 3 months old, as recommended by the Joint Committee on Infant Hearing. Methods: a quantitative, nonexperimental study with a sample of 30 hearing subjects, aged 18 to 30 years. The Pearson´s correlation test was applied, with a significance p-value of 0.01. Results: higher frequencies (2000 and 4000 Hz) have lower correction factors than medium and lower frequencies (1000 and 500 Hz), which tend to be higher as the frequency is lower. Conclusions: the study obtained the following estimated thresholds: 15 dB at 500 Hz, 10 dB at 1000 and 2000 Hz, and 5 dB at 4000 Hz
Estado de conservación de la biota de la región de Atacama
No full textEn los capítulos precedentes se ha descrito la biodiversidad de distintos grupos de organismos que habitan actualmente la región de Atacama. Considerando los resultados hasta el 18º proceso de clasificación de especies en categorías de conservación (2023), en la región de Atacama se han tratado oficialmente 338 taxa de los reinos Plantae, Fungi y Animalia. De ellos, 9 taxa se les consideran extintos (2,7% de los taxa clasificados), 160 taxa están en una categoría de amenaza (CR = En peligro crítico, EN = En peligro, VU = Vulnerable, 47,3%), 153 taxa en categorías que no alcanza el umbral de amenazada (NT = Casi amenazada, LC = Preocupación menor, 45,3%) y 16 taxa (4,7%) clasificadas con Datos Insuficientes (DD)
Associations between physical fitness, body composition, and heart rate variability during exercise in older people: exploring mediating factors
No full textBackground. Age-related changes in body composition affect physical fitness in older adults. However, whether the autonomic response is associated with body fat percentage and its implication for physical fitness is not fully understood. Aim. To understand the association between physical fitness, body composition, and heart rate variability in older people and its mediating factors. Methods. A cross-sectional study with 81 older adults was conducted, assessing Short Physical Performance Battery (SPPB), Two-minute Step Test (TMST), body composition, and cardiac autonomic response. Correlation and mediation analyses were performed. Results. Body fat percentage negatively correlated with physical fitness (SPPB: r = -0.273, p = 0.015; TMST: r = 0.279, p = 0.013) and sympathetic activity (sympathetic nervous system (SNS) index: r = -0.252, p = 0.030), yet positively correlated with parasympathetic tone (root mean square of successive differences (RMSSD): r = 0.253, p = 0.029; standard deviation of NN intervals (SDNN): r = 0.269, p = 0.020). Physical fitness associated with sympathetic nervous system index (SPPB: r = 0.313, p = 0.006; TMST: r = 0.265, p = 0.022) and parasympathetic nervous system index (TMST: r = 0.344, p = 0.003). Muscle mass mediated body fat's impact on physical fitness, while physical fitness mediated body fat's impact on autonomic response. Conclusion. Body composition and cardiac autonomic response to exercise are associated with physical fitness in older people, highlighting a possible protective effect of muscle mass against the decline in physical fitness associated with increased body fat