42 research outputs found

    Landslides induced by the 2010 Chile megathrust earthquake: a comprehensive inventory and correlations with geological and seismic factors

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    The 2010 Mw=8.8 Maule earthquake, which occurred in the subduction contact between the Nazca and the South American tectonic plates off the coast of Chile, represents an important opportunity to improve understanding of the distribution and controls for the generation of landslides triggered by large megathrust earthquakes in subduction zones. This paper provides the analysis of the comprehensive landslide inventory for the Maule earthquake between 32.5° S and 38.5° S°. In total 1226 landslides were mapped over a total area of c.120,500 km2 , dominantly disrupted slides. The total landslide volume is c. 10.6 Mm3. The events are unevenly distributed in the study area, the majority of landslides located in the Principal Andean Cordillera and a very constrained region near the coast on the Arauco Peninsula, forming landslide clusters. Statistical analysis of our database suggests that relief and lithology are the main geological factors controlling coseismic landslides, while the seismic factor with higher correlation with landslide occurrence is the ratio between peak horizontal and peak vertical ground accelerations. The results and comparison with other seismic events elsewhere suggest that the number of landslides generated by megathrust earthquakes is lower than events triggered by shallow crustal earthquakes by at least one or two orders of magnitude, which is very important to consider in future seismic landslide hazard analysis

    Design of a high-performance optical tweezer for nanoparticle trapping

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    Integrated optical nanotweezers offer a novel paradigm for optical trapping, as their ability to confine light at the nanoscale leads to extremely high gradient forces. To date, nanotweezers have been realized either as photonic crystal or as plasmonic nanocavities. Here, we propose a nanotweezer device based on a hybrid photonic/plasmonic cavity with the goal of achieving a very high quality factor-to-mode volume (Q/V) ratio. The structure includes a 1D photonic crystal dielectric cavity vertically coupled to a bowtie nanoantenna. A very high Q/V ~ 107 (λ/n)−3 with a resonance transmission T = 29 % at λR = 1381.1 nm has been calculated by 3D finite element method, affording strong light–matter interaction and making the hybrid cavity suitable for optical trapping. A maximum optical force F = −4.4 pN, high values of stability S = 30 and optical stiffness k = 90 pN/nm W have been obtained with an input power Pin = 1 mW, for a polystyrene nanoparticle with a diameter of 40 nm. This performance confirms the high efficiency of the optical nanotweezer and its potential for trapping living matter at the nanoscale, such as viruses, proteins and small bacteria

    Variability in the analysis of a single neuroimaging dataset by many teams

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    Data analysis workflows in many scientific domains have become increasingly complex and flexible. To assess the impact of this flexibility on functional magnetic resonance imaging (fMRI) results, the same dataset was independently analyzed by 70 teams, testing nine ex-ante hypotheses. The flexibility of analytic approaches is exemplified by the fact that no two teams chose identical workflows to analyze the data. This flexibility resulted in sizeable variation in hypothesis test results, even for teams whose statistical maps were highly correlated at intermediate stages of their analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Importantly, meta-analytic approaches that aggregated information across teams yielded significant consensus in activated regions across teams. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset. Our findings show that analytic flexibility can have substantial effects on scientific conclusions, and demonstrate factors related to variability in fMRI. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for multiple analyses of the same data. Potential approaches to mitigate issues related to analytical variability are discussed

    Variability in the analysis of a single neuroimaging dataset by many teams

    Get PDF
    Data analysis workflows in many scientific domains have become increasingly complex and flexible. To assess the impact of this flexibility on functional magnetic resonance imaging (fMRI) results, the same dataset was independently analyzed by 70 teams, testing nine ex-ante hypotheses. The flexibility of analytic approaches is exemplified by the fact that no two teams chose identical workflows to analyze the data. This flexibility resulted in sizeable variation in hypothesis test results, even for teams whose statistical maps were highly correlated at intermediate stages of their analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Importantly, meta-analytic approaches that aggregated information across teams yielded significant consensus in activated regions across teams. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset. Our findings show that analytic flexibility can have substantial effects on scientific conclusions, and demonstrate factors related to variability in fMRI. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for multiple analyses of the same data. Potential approaches to mitigate issues related to analytical variability are discussed

    Orientación empática de los estudiantes de dos escuelas de kinesiología de Chile Empathetic orientation of the physical therapist's students from two schools of Chile

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    Objetivo. Conocer la orientación empática de los alumnos de la carrera de kinesiología de dos escuelas de la región metropolitana. Sujetos y métodos. Este trabajo corresponde a una investigación analítica de corte transversal realizada entre los meses de marzo y noviembre del año 2006. Participaron 274 alumnos de un universo de 351 correspondientes a los niveles I, III y V de la carrera de kinesiología de la Universidad de Chile y la Universidad Mayor. Se aplicó la escala de empatía médica de Jefferson (EEMJ). Para el análisis de los datos, se utilizó la prueba U no paramétrica de Wilcoxon-Mann-Whitney y la prueba no paramétrica de Kruskal-Wallis. Resultados. Se obtuvieron mayores puntuaciones en la EEMJ con significación estadística en el tercer y quinto nivel de la carrera con relación al primero (p < 0,05). No se encontraron diferencias significativas en las puntuaciones según sexo. Conclusiones. Existen mayores puntuaciones obtenidas en la EEMJ en los alumnos que están en niveles más avanzados de la carrera de kinesiología, y esta diferencia es significativa en ambas universidades. Las puntuaciones obtenidas en la EEMJ no tienen significación estadística en relación con la variable sexo en ambas universidades.<br>Aim. To know the empathetic orientation of the physical therapist's students in two schools of the metropolitan region. Subjects and methods. This work is an analytical cross-sectional research, carried out between the months on March and November, 2006. 274 out of 351 students participated, who belonged to the levels I, III and V of the Universidad de Chile and Universidad Mayor Physical Therapy Programs. The Jefferson Scale of Physician Empathy (JSPE) was applied. For data analysis, the non-parametrical Wilcoxon-Mann-Whitney test and the non-parametrical Kruskal-Wallis test were used. Results. Higher scores in the JSPE with statistical significance were obtained in the third and fifth level of the program compared with the first one (p < 0.05). No significant differences were found in the scores related to gender. Conclusions. There exists higher scores obtained in the JSPE in students who are in more advanced levels of the Physical Therapy Program, being this difference significant in both universities. The scores obtained in the JSPE do not have statistical significance in relation to the variable gender in both universities
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