Ciencia Abierta - ANID

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    Autoregressive model based input and parameter estimation for nonlinear finite element models
    (Universidad de los Andes) Astroza, Rodrigo
    A novel framework to accurately estimate nonlinear structural model parameters and unknown external inputs (i.e., loads) using sparse sensor networks is proposed and validated. The framework assumes a time-varying auto-regressive (TAR) model for unknown loads and develops a strategy to simultaneously estimate those loads and parameters of the nonlinear model using an unscented Kalman filter (UKF). First, it is confirmed that a Kalman filter (KF) allows to estimate TAR parameters for a measured, earthquake, acceleration time-history. The KF-based framework is then coupled to an UKF to jointly identify unmeasured inputs and nonlinear finite element (FE) model parameters. The proposed approach systematically assimilates different structural response quantities to estimate TARandFEmodelparameters and, asa result, updates the FE model and unknown external excitation estimates. The framework is validated using simulated experiments on a realistic three-dimensional nonlinear steel frame subjected to unknown seismic ground motion. It is demonstrated that assuming relatively low order TAR model for the unknown input leads to precise reconstruction and unbiased estimation of nonlinear model parameters that are most sensitive to measured system response.
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    Comparing the use of static versus dynamic images to evaluate a smile
    (Universidad de los Andes) Gutierrez, Javiera
    Statement of problem. Smile analysis, as part of the overall facial analysis, is an important component of diagnosis and treatment planning in the esthetic rehabilitation of a patient. Most studies that refer to smile analysis are based on static images. A more comprehensive evaluation can be made with dynamic video images that can be stopped at the most appropriate frame to ensure the best static images for analysis. Purpose. The purpose of this clinical study was to evaluate the posed and dynamic smiles of both sexes, considering the type of smile, prevalence of gingival display, dental display at rest, dentogingival display at posed and spontaneous smile, and lip mobility, through digital image acquisition (photographs and video clips) manipulated by using a software program. Material and methods. Three photographs and 1 video clip were made for each of the 380 voluntary participants aged between 18 and 32 years by using an iPhone 6 iSight 8 MP camera, Moment lens, and artificial 5500 Kelvin light (IceLight). Digital files were evaluated by using a software program (Keynote), determining each point to be evaluated with posed and spontaneous smiles. Results. With static images, 90% of women and 74% of men had gingival display, with only 35% of women and 21% of men having continuous gingival display. With dynamic analysis, these values increased to 100% of women and 95% of men having gingival display and 62% ofmen and 81%of women having a continuous gingival display (P<.05). The difference between dentogingival display during posed and spontaneous smiles was clear, with 68% of the participants having 2.25 mm more gingival display. Women tend to show slightly more dental display at rest, posed and spontaneous dentogingival display, as well as lip mobility, than men. Conclusions. The type of smile changes significantly when posed and spontaneous smiles are compared. Women generally show more gingiva and teeth in all the parameters evaluated than men. Dental treatments should be individually planned according to each patient’s smile characteristics. (J Prosthet Dent 2020;123:739-46)
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    Constitución y mercado: El modelo económico de la Constitución de 1980
    (Universidad de los Andes) Herrera Orellana, Luis Alfonso
    Análisis de los pilares económicos de la Carta Fundamental de 1980, enfocándose en la libre iniciativa económica y el principio de subsidiariedad.
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    Dynamiccoordination withtimingfrictions: Theoryandapplications
    (Elsevier) Pereira, Ana
    We present a general framework of dynamic coordination with timing frictions. A continuum of agents receive random chances to choose between two actions and remain locked in the selected action until their next opportunity to reoptimize. The instantaneous utility from each action depends on an exogenous fundamental that moves stochastically and on the mass of agents currently playing each action. Agents' decisions are strategic complements and history matters. We review some key theoretical results and show a general method to solve the social planner's problem. We then review applications of this framework to different economic problems: network externalities, statistical discrimination, and business cycles. The positive implications of these models are very similar, but the social planner's solution points to very different results for efficiency in each case. Last, we review extensions of the framework that allow for endogenous hazard rates and ex ante heterogeneous agents.
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    Efectos del entrenamiento respiratorio aislado en las variables respiratorias y vocales
    (Revista de Investigación e Innovación en Ciencias de la Salud, 2020) Acevedo, Karol; Guzmán, Marco
    El propósito de esta revisión es determinar los efectos del entrenamiento muscular respiratorio aislado sobre la función respiratoria y vocal en sujetos con y sin patología. Se concluye que el entrenamiento aislado impacta positivamente en variables respiratorias, pero no necesariamente en la producción vocal.
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    Enhancingtheclassification of social mediaopinionsbyoptimizingthe structural information
    (Universidad de los Andes) Vairetti, Carla; Martínez-Cámarac, Eugenio ; Maldonadoa, Sebastián
    Sentiment Analysis is an extensively studied task, however an important aspect yet to study is the underlying structural information of opinions. An important aspect to tackle is the analysis underlying structural information of opinions. Social media is a great source of user opinions, which are structured in most of the cases in two sections: the title and the content or body of the opinion. We claim that the structure of social media opinions has useful information for the polarity classification task. We propose a model for optimizing the contribution of that underlying structural information for polarity classification. Our model is built by weighting the contribution of each section, title and body. We develop a modified Support Vector Machine that includes a weight parameter, which is optimized via a line-search strategy. We evaluate our proposal on three datasets of reviews from different domains written in two different versions of the Spanish language. The results show that our model outperforms the classification of the joint or individual classification of each section of the opinion. Therefore, our claim holds.
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    La exención de las empresas sanitarias de solicitar permisos municipales de construcción y urbanismo y su naturaleza “estatal” (Comentarios a la sentencia de la Corte Suprema de Justicia Rol 27.106-2019)
    (Universidad de los Andes) Herrera Orellana, Luis Alfonso
    Este trabajo examina la sentencia dictada por la Corte Suprema de Justicia, el 30 de marzo de 2020, en el caso Aguas del Valle S.A. vs. Municipalidad de Ovalle, Rol 27.106-2019, para formular consideraciones críticas tanto al tratamiento dado por el fallo a las competencias municipales en materia de urbanismo y construcción frente a las competencias del Estado nacional en materia de edificación de obras sanitarias, para eximir a este último de la obligación legal de solicitar el permiso municipal de construcción, como a la asimilación de las empresas sanitarias al Estado.
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    Neural stem cell therapy of foetal onset hydrocephalus using the HTx rat as experimental mode
    (Elsevier) Henzi, Roberto
    Foetal onset hydrocephalus is a disease starting early in embryonic life; in many cases it results from a cell junction pathology of neural stem (NSC) and neural progenitor (NPC) cells forming the ventricular zone (VZ) and sub-ventricular zone (SVZ) of the developing brain. This pathology results in disassembling of VZ and loss of NSC/NPC, a phenomenon known as VZ disruption. At the cerebral aqueduct, VZ disruption triggers hydrocephalus while in the telencephalon, it results in abnormal neurogenesis. This may explain why derivative surgery does not cure hydrocephalus. NSC grafting appears as a therapeutic opportunity. The present investigation was designed to find out whether this is a likely possibility. HTx rats develop hereditary hydrocephalus; 30–40% of newborns are hydrocephalic (hyHTx) while their littermates are not (nHTx). NSC/NPC from the VZ/SVZ of nHTx rats were cultured into eurospheres that were then grafted into a lateral ventricle of 1-, 2- or 7-day-old hyHTx. Once in the cerebrospinal fluid, neurospheres disassembled and the freed NSC homed at the areas of VZ disruption. A population of homed cells generated new multiciliated ependyma at the sites where the ependyma was missing due to the inherited pathology. Another population of NSC homed at the disrupted VZ differentiated into βIII-tubulin+ spherical cells likely corresponding to neuroblasts that progressed into the parenchyma. The final fate of these cells could not be established due to the protocol used to label the grafted cells. The functional outcomes of NSC grafting in hydrocephalus remain open. The present study establishes an experimental paradigm of NSC/NPC therapy of foetal onset hydrocephalus, at the etiologic level that needs to be further explored with more analytical methodologies.
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    Towards the Construction of a History of the Schoolbook in Chile (1843-1879)
    Soaje de Elías, Raquel; Fernández, Manuel Salas
    The decade of 1840 marks a before-and-after period for the general history of Chilean education. This article analyzes the production and circulation of schoolbooks as cultural artifacts aimed at civilizing and moralizing the population.