Proyectos

El present projecte pretén descriure la visió que els futurs professionals de la salut tenen del cos i els usos que li donen per tal d’afavorir la reflexió sobre el seu impacte en atenció a l’usuari (l’aproximació al cos de l’altre). Conèixer els discursos i les pràctiques realitzades amb el cos dels estudiants de primer curs de ciències de la salut (teràpia ocupacional i infermeria) que expliquem la seva relació amb el “cos”.

Introduction: Ultrasound (US) exams are extensively used in Chile and around the world. This non-invasive imaging technique has many advantages when compared to magnetic resonance, computed tomography, and others because it has a low cost, it does not need ionizing radiation, and it is portable equipment. However, this technique has many challenges; the most known is the balance between resolution and penetration depth. Recently, in 2011, a new technique of US has been described: the ultrasound localization microscopy (ULM). However, it was only in 2015 that this technique gained knowledge with the publication of Errico et al. (2015) who described the ultrafast ultrasound localization microscopy applied in vivo in rats’ brain. ULM eliminates the challenge of the balance between resolution and penetration; but a new challenge emerges: the balance between localization precision of microbubble, microbubble concentration, and acquisition time. The microbubbles (MB) are the contrast agent for the US technique. They have 1-5 µm in diameter and act as a blinking source. These MB are injected into the bloodstream and flow into the circulatory system. ULM is also known as super-resolution imaging; it can produce vascular images with a resolution around 10 µm, 10 times better than the conventional US image. This unprecedented resolution has numerous potential applications. In particular, ULM would have a high impact in oncology because the vascular structure of early tumors, that are in the range of 5 µm to 80 µm, provides information that can help in the early diagnosis and monitor therapy responses. The huge potentiality of ULM has produced a lot of excitement and expectation worldwide, and it became a hot topic in the medical ultrasound community. Unfortunately, this technique is not yet clinically approved because it is still in development stages and presents many challenges that must be solved before translating it into clinics. The mainly limitations to overcome before translating ULM into clinics are the following: contrast-to-tissue ratio (CTR), signal-to-noise ratio (SNR), acquisition time, microbubble concentration, motion, lack of a gold standard, data overdose, exploitation of ultrafast scanner uncommon in the clinic and so on. Therefore, the aim of this study is to optimize the technique to localize microbubbles, and to explore the physics of microbubble to provide a change in the paradigm of the processes to produce ULM by combining the superresolution processing with a controlled exterior force impulse. To achieve this aim, first a numerical study will be performed to simulate microbubbles into small vessels and find a better way to localize them. The robustness of the algorithm will be increased to consider the non-linear interactions between MB and US and to consider the parabolic velocity profile of the vessel/tube. Up to date, the studies on microbubbles localization in ULM are after the image acquisition. There are no tissue/flow simulations of the behavior of microbubbles into the vessels with this technique. To perform the simulation, we will use a computer with excellent storage capacity and great velocity of processing together with the MATLAB algorithm: The Full Wave Solver. Second, an experimental study will be performed to generate super resolution images in a conventional phantom. The state of art will be applied with a phantom made by microtubes and microbubbles and then, the improvement of the aim 1 will be considered into this experiment. The complexity of the phantom will be increased from a medium with only water, then gelatine and finally, we will add some respiratory simulated movement. To the experimental setup we will use the Verasonics Vantage 128 research ultrasound scanner with different types of ultrasound transducers, microbubbles, microtubes, gelatine and the respiratory movement will be simulated with a vibration testing system (Shaker VTS-100). Finally, the physics of microbubble will be explored to provide a change in the paradigm of the processes to produce ULM and to detect the MB in a more direct way, without the need to perform a filter, like the signal value decomposition (SVD). We want to apply the an external know push pulse that will produce differences in the shear waves between the microbubbles and the tissue around and with simulations we will be able to know the response of microbubbles and it may help us to separate them from the tissue. Expected results: As result of this study, we expect to develop a numerical simulation to the ULM method, by considering interactions of the US with the tissue and fluid dynamics of the blood into the vessel and significantly optimize the techniques of MB detection. Besides that, this project will help to improve the first fully programmable ultrasound scanner system in Chile. Potentially, this would open new research areas at the country level, such as ultrasound imaging, ultrasound super-resolution imaging and soft tissue characterization.

Far from simple steric repulsion, i.e., volumetric repulsion, the dynamics of granular systems are driven by a menagerie of interactions: dissipative collisions, van der Waals forces, electrostatic Coulomb and polarization forces, viscous drag and, in the presence of even minute amounts of liquid, capillary bridges or ice coatings. Despite its importance and the development of many powerful experimental, numerical and theoretical tools, until now, a unified description of granular media is lacking, even for the simplest model situation of perfectly spherical, impenetrable and dissipative particles. One of the most important topics in granular media research is clustering, for both fundamental and applied reasons. Clustering produces large gradients, which makes usual gradient perturbations schemes more difficult, which even poses questions about the validity of continuum approaches for these systems. Clustering and coarsening are also relevant for many industrial applications, including grain and powder storage, transport and manipulation, in the food, mining and chemical industries, to mention a few. Electrostatically–induced granular clustering has emerged as a mechanism with fundamental and practical implications. The electrification of such systems occurs through tribocharging—the exchange of charge between contacting surfaces. Despite its importance, how insulators transfer such large amounts of charge during contact is not well-understood. How this can also occur for identical materials during contact is puzzling as well. Furthermore, the nature of the charge carrier is also not settled. Concerning applications, just recently electrostatically–induced granular clustering has been revealed as a possible enhancing mechanism for granular coarsening in a very important and unsolved issue: the formation of planetesimals, which can be considered as baby planets (from 1 km size it is expected that gravity should be the driving accretion force). Indeed, despite clear evidence, our current theoretical understanding is that rocky planets should not exist; a basic ingredient seems to be missing for explaining the clustering of grains in the sub- mm to cm range. We propose that electrification through tribocharging is the missing ingredient. Thus, the main objective of this proposal is to address how different pair-wise interactions and, in general, particle and collisional properties, lead to sustained cluster growth. We are developing two experimental systems to make concrete steps toward this goal. In the first, we are using a free-fall apparatus to observe collisions between sub-mm particles in vacuum and zero-gravity conditions. In the second, we are forging into the new territory of interactions between millimeter-scale particles or clusters with a controlled acoustic levitation setup. In order to understand the microphysics of grain growth in the sub-mm to cm range, our immediate objective is to characterize the sticking efficiencies and dominant forces—including the possibility of same-material tribocharging—in a variety of conditions. In the first experimental setup, we will focus on few-particle interactions and clustering. In the second, we will study controlled collisions between a few up to many-particle clusters. Working on these two experiments in tandem will enable us to characterize collisions over decades of data in cluster size and impact energy, and quantify same-material tribocharging. For both experiments we will use standard dielectric materials (as ZrO2:SiO2 composites) as a benchmark. Then, we will use analog meteorite materials (e.g. San Carlos Olivine) in both setups, and original meteorite grains (Allende meteorite) with the ultrasonic setup, where controlled collisions can be done for smaller amounts of material. The outcome of such experiments will be a phase portrait of collisional aggregation efficiency covering features ranging from particle and cluster size to particle interactions, particle composition and impact energy. One particular contribution we will focus on is the effect of tribocharging on the formation efficiency of larger clusters, which should be relevant toward our current understanding of asteroid and planetesimal formation.

Históricamente, el álgebra escolar ha estado vinculado al uso exclusivo de letras y símbolos matemáticos, lo cual es una mirada muy reducida sobre lo que realmente significa el álgebra en la escuela. En los últimos años, diferentes iniciativas promueven el desarrollo del pensamiento algebraico en la educación básica, tipo de pensamiento matemático que supone prestar la atención a las relaciones que escolares construyen, más que a procedimientos aislados. A pesar de los esfuerzos por incorporar el pensamiento algebraico desde los primeros cursos, todavía existen profesores que creen que el álgebra es el conocimiento de procedimientos mecánicos que involucran el uso de letras y símbolos matemáticos y, por tanto, sus esfuerzos apuntan a ese propósito. Lo anterior cobra fuerza en el contexto de la Formación Inicial Docente por dos razones principales: (a) los conocimientos algebraicos de los futuros profesores chilenos al terminar su formación son preocupantes (Santiago et al., 2013); y (b) el pensamiento algebraico es uno de los focos centrales del currículo matemático nacional (Mineduc, 2012). A partir de lo anterior, surge la necesidad de identificar y comprender cómo se desarrolla el conocimiento profesional sobre álgebra que tienen los futuros profesores de educación básica. Este proyecto adopta la idea que el álgebra y el pensamiento algebraico van más allá del uso de la notación algebraica; se favorece el uso de representaciones tan variadas como el lenguaje natural, representaciones manipulativas, pictóricas, numéricas, tabulares, gráficas, entre otras. En concreto, seguimos el marco conceptual propuesto por Kaput (2008) sobre su forma de entender el álgebra y el pensamiento algebraico: la generalización y su representación constituyen aspectos centrales. Dado que este proyecto se interesa por el conocimiento profesional de los futuros profesores, nos centramos en el la competencia denominada Mirada Profesional (Jacobs et al., 2010), la cual busca reconocer y dar sentido a lo hechos que suceden en la clase de matemáticas para poder explicar e informar el aprendizaje de las matemáticas, lo que apoyará las decisiones que tomen los futuros profesores con el propósito de favorecer el aprendizaje de sus estudiantes. Específicamente, la Mirada Profesional involucra tres habilidades interrelacionadas: (a) prestar atención a las estrategias de los niños; (b) interpretar las comprensiones de los niños; y (c) decidir cómo responder sobre la base de las comprensiones de los niños (toma de decisiones). En términos metodológicos, este proyecto sigue las directrices de la Investigación de Diseño (Cobb, Confrey, diSessa, Lehrer y Schauble, 2003). Concretamente, esta investigación se llevará a cabo a través de un experimento de enseñanza, el cual estudia la naturaleza del desarrollo de ideas, herramientas o modelos en los que están contenidos futuros profesores; y entrevistas individuales semiestructuradas, las cuales permitirán profundizar con mayor detalle en los conocimientos de los futuros profesores. En cuanto a los participantes, esta investigación contará con la colaboración de los futuros profesores matriculados en la cátedra “Enseñanza del Álgebra, Datos y Azar” de la carrera de Pedagogía en Educación Básica con mención en Inglés de la UDD. Este curso es obligatorio y se imparte en el sexto semestre. En lo que respecta al diseño del proyecto, los futuros profesores participarán de 8 sesiones de clases destinadas a la enseñanza y aprendizaje del álgebra, donde se trabajarán los diferentes contenidos algebraicos del modelo conceptual seguido, así como las habilidades propias de la Mirada Profesional. Posteriormente, se observará a un grupo de estos futuros profesores en su Práctica y Seminario III, donde estos podrán conducir secuencias de enseñanza y aprendizaje referidas al álgebra. El foco de análisis de la información estará centrado en las respuestas y producciones (escritas y orales) de los futuros profesores, mediante un análisis de las clases grabadas. El impacto esperado de los resultados influirá en tres áreas principales: (a) investigación e internacionalización, consolidando y posicionando una línea de investigación novedosa en el campo de la Educación Matemática; (b) docencia, enriqueciendo la Formación Inicial Docente, a través del desarrollo y promoción del pensamiento algebraico en sus estudiantes; y (c) redes de colaboración, lo cual permitirá conectar y posicionar a esta investigación con un conjunto de investigadores internacionales que asesoran y avalan la calidad y relevancia de este proyecto de investigación. Referencias Cobb, P., Confrey, J., diSessa, A., Lehrer, R. y Schauble, L. (2003). Design experiments in educational research. Educational Researcher, 32(1), 9-13. Jacobs, V. R., Lamb, L. L. y Philipp, R. (2010). Professional noticing of children’s mathematical thinking. Journal for Research in Mathematics Education, 41(2), 169-202. Kaput, J. (2008). What is algebra? What is the algebraic reasoning? En J. J. Kaput, D. W. Carraher y M. L. Blanton (Eds.), Algebra in the early grades (pp. 5-17). Nueva York, NY: Lawrence Erlbaum Associates. Ministerio de Educación de Chile [MINEDUC] (2012). Bases Curriculares. Primero a Sexto Básico. Santiago, Chile: Autor. Santiago, P., Benavides, F., Danielson, C., Goe, L. y Nusche, D. (2013). Teacher Evaluation in Chile. París: OCDE.

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