Browsing by Author "Uribe Arancibia, Sergio Andrés"

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    Cartografías de la Sangre. Atlas y diagrama
    Laval Possel, Gastón Javier; Uribe Arancibia, Sergio Andrés; Grass Kleiner, Milena Rebeca; Cádiz Cádiz, Rodrigo Fernando
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    Physics-informed neural networks for parameter estimation in blood flow models
    (2024) Garay Labra, Jeremías Esteban; Dunstan Escudero, Jocelyn Mariel; Uribe Arancibia, Sergio Andrés; Sahli Costábal, Francisco
    Background: Physics-informed neural networks (PINNs) have emerged as a powerful tool for solving inverse problems, especially in cases where no complete information about the system is known and scatter measurements are available. This is especially useful in hemodynamics since the boundary information is often difficult to model, and high-quality blood flow measurements are generally hard to obtain. Methods: In this work, we use the PINNs methodology for estimating reduced-order model parameters and the full velocity field from scatter 2D noisy measurements in the aorta. Two different flow regimes, stationary and transient were studied. Results: We show robust and relatively accurate parameter estimations when using the method with simulated data, while the velocity reconstruction accuracy shows dependence on the measurement quality and the flow pattern complexity. Comparison with a Kalman filter approach shows similar results when the number of parameters to be estimated is low to medium. For a higher number of parameters, only PINNs were capable of achieving good results. Conclusion: The method opens a door to deep-learning-driven methods in the simulations of complex coupled physical systems.
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    Regional brain atrophy is related to social cognition impairment in multiple sclerosis
    (ASSOC ARQUIVOS NEURO- PSIQUIATRIA, 2021) Labbe Atenas, Tomás Pablo; Montalba Zalaquett, Cristian Andrés; Zurita Soler, Mariana; Ciampi Diaz, Ethel Leslie; Albornoz Cruz, Juan Pablo; Vásquez Torres, Macarena; Uribe Arancibia, Sergio Andrés; Crossley Karmelic, Nicolás Andrés; Cárcamo Rodríguez, Claudia Andrea
    Background: Multiple sclerosis exhibits specific neuropathological phenomena driving to both global and regional brain atrophy. At the clinical level, the disease is related to functional decline in cognitive domains as the working memory, processing speed, and verbal fluency. However, the compromise of social-cognitive abilities has concentrated some interest in recent years despite the available evidence suggesting the risk of disorganization in social life. Recent studies have used the MiniSEA test to assess the compromise of social cognition and have found relevant relationships with memory and executive functions, as well as with the level of global and regional brain atrophy. Objective: The present article aimed to identify structural changes related to socio-cognitive performance in a sample of patients with relapsing-remitting multiple sclerosis. Methods: 68 relapsing-remitting multiple sclerosis Chilean patients and 50 healthy control subjects underwent MRI scans and neuropsychological evaluation including social-cognition tasks. Total brain, white matter, and gray matter volumes were estimated. Also, voxel-based morphometry was applied to evaluate regional structural changes. Results: Patients exhibited lower scores in all neuropsychological tests. Social cognition exhibited a significant decrease in this group mostly related to the declining social perception. Normalized brain volume and white matter volume were significantly decreased when compared to healthy subjects. The regional brain atrophy analysis showed that changes in the insular cortex and medial frontal cortices are significantly related to the variability of social-cognitive performance among patients. Conclusions: In the present study, social cognition was only correlated with the deterioration of verbal fluency, despite the fact that previous studies have reported its link with memory and executive functions. The identification of specific structural correlates supports the comprehension of this phenomenon as an independent source of cognitive disability in these patients.