Examinando por Autor "Saavedra, Carolina"

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    Image Quality Assessment to Emulate Experts’ Perception in Lumbar MRI Using Machine Learning
    (MDPI, 2021) Chabert, Steren; Castro, Juan Sebastian; Muñoz, Leonardo; Cox, Pablo; Riveros, Rodrigo; Vielma, Juan; Huerta, Gamaliel; Querales, Marvin; Saavedra, Carolina; Veloz, Alejandro; Salas, Rodrigo
    Medical image quality is crucial to obtaining reliable diagnostics. Most quality controls rely on routine tests using phantoms, which do not reflect closely the reality of images obtained on patients and do not reflect directly the quality perceived by radiologists. The purpose of this work is to develop a method that classifies the image quality perceived by radiologists in MR images. The focus was set on lumbar images as they are widely used with different challenges. Three neuroradiologists evaluated the image quality of a dataset that included T1-weighting images in axial and sagittal orientation, and sagittal T2-weighting. In parallel, we introduced the computational assessment using a wide range of features extracted from the images, then fed them into a classifier system. A total of 95 exams were used, from our local hospital and a public database, and part of the images was manipulated to broaden the distribution quality of the dataset. Good recall of 82% and an area under curve (AUC) of 77% were obtained on average in testing condition, using a Support Vector Machine. Even though the actual implementation still relies on user interaction to extract features, the results are promising with respect to a potential implementation for monitoring image quality online with the acquisition process.
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    Intervención especializada en maltrato infantil en Chile en contexto de crisis por Covid-19: significados de los profesionales intervinientes
    (Universidad De Tarapacá, 2021) Pinto-Cortez, Cristián; Arrendondo Ossandón, Valeria; Lira, Gonzalo; Lobos Sucarrat, Paula; Saavedra, Carolina; Guerra, Cristóbal
    La crisis sociosanitaria por COVID-19 ha afectado la forma en que los centros especializados en apoyo a víctimas de maltrato infantil realizan su labor. El formato de atención ha pasado desde lo presencial a lo online, con los desafíos que eso conlleva tanto en el ámbito práctico como en el ámbito técnico-profesional. Las familias más vulnerables presentan mayores problemas de conexión -con el consecuente aislamiento- y mayores estresores que pueden empeorar la relación al interior de la familia, aumentando la complejidad de las intervenciones. En este contexto el objetivo del estudio fue describir los significados de los profesionales de centros especializados en la atención a víctimas de maltrato infantil respecto de la intervención especializada desarrollada durante la crisis por COVID-19. Participaron 42 profesionales de estos centros, quienes respondieron una entrevista semiestructurada online. Los resultados del análisis de contenido cualitativo dan cuenta de significados asociados a los riesgos asociados a la intervención en este contexto (para los niños y sus familias, para la intervención, asociados a la precarización de condiciones sociomateriales, baja conectividad y confinamiento). No obstante, los participantes también destacan oportunidades y recursos en la intervención (la capacidad de adaptar las intervenciones al nuevo contexto y el trabajo de equipo). Todo lo anterior resulta de utilidad en lo inmediato de forma de visibilizar riesgos y oportunidades en una crisis que parece ser que será más larga de lo originalmente pensado. Es necesario actuar rápidamente para realizar las modificaciones pertinentes en las intervenciones, de forma de disminuir los riesgos y potenciar las oportunidades en beneficio de los niños, niñas y adolescentes.
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    Risk and protective factors for depression and anxiety in professionals supporting victims of child abuse during the Covid-19 crisis
    (Sociedad Mexicana De Psicología, 2021) Guerra, Cristóbal; Arredondo, Valeria; Pinto-Cortez, Cristián; Saavedra, Carolina; Lira, Gonzalo; Arredondo, Alejandro; Lobos, Paula
    The covid-19 crisis has challenged the well-being of professionals supporting abused children. The effects of some risk (i.e., number of nearby infected people and telecommuting and housework hours per day) and protective (i.e., social support, self-efficacy, and self-care) factors on depression and anxiety symptoms were tested in professionals supporting child-abuse victims in Chile during the covid-19 crisis. Professionals (N = 175) answered self-reports. Having infected people nearby and social support predicted depression. The effect of social support on depression was partially mediated by self-efficacy and self-care. The effect of social support on anxiety was completely mediated by self-care. Results show that social and psychological variables are relevant to understand depression and anxiety symptoms in professionals even during the covid-19 crisis.
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    Wavelet-based semblance analysis to determine muscle synergy for different handstand postures of Chilean circus athletes
    (Taylor & Francis, 2021) Calderón-Díaz, Mailyn; Ulloa-Jiménez, Ricardo; Saavedra, Carolina; Salas, Rodrigo
    The handstand is an uncommon posture, highly demanding in terms of muscle and joint stability, used in sporting and artistic practices in a variety of disciplines. Despite its becoming increasingly widespread, there is no specific way to perform a handstand, and the neuromuscular organizational mechanisms involved are unknown. The objective of this study was to determine the muscle synergy of four handstand postures through a semblance analysis based on wavelets of electromyographic signals in the upper limbs of experienced circus performers between 18 and 35 year old. The results show that there is a large difference in positive and negative correlations depending on the posture, which suggests that the more asymmetrical the position of the lower limbs, the greater the number of strategies to maintain the posture. Although it is not a statistically significant data, it is observed that the posture 3 in particular, possesses the greatest number of positive correlations, which suggests it has the greatest synergy.