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Estimativa da idade cerebral e classificação diagnóstica na doença de Alzheimer via campos de deformação em imagens de ressonância magnética
(Universidade Federal de São Carlos, 2026-09-14) Andrade, Leandro Prado de; Liziér, Mario Augusto de Souza; http://lattes.cnpq.br/1257131701222446; https://orcid.org/0000-0001-9123-5822; Ferrari, Ricardo José; http://lattes.cnpq.br/8460861175344306; https://orcid.org/0000-0003-1197-2553; http://lattes.cnpq.br/6280032570953598; https://orcid.org/0000-0001-9405-906X; Valejo, Alan Demétrius Baria; Oliveira, Lucas Ferrari de; Fernandes, Ricardo Augusto Souza; Travençolo, Bruno Augusto Nassif; http://lattes.cnpq.br/9546164790189830; http://lattes.cnpq.br/3534918669459073; http://lattes.cnpq.br/0880243208789454; http://lattes.cnpq.br/2590427557264952; https://orcid.org/0000-0002-9046-9499; https://orcid.org/0000-0002-8198-0877; https://orcid.org/0000-0003-2361-6505; https://orcid.org/0000-0001-7690-301X
Alzheimer’s disease is a progressive neurodegenerative condition and the leading cause of dementia in the elderly population, highlighting the need for computational methods sensitive to subtle brain alterations. This thesis proposes a framework for structural magnetic resonance imaging analysis based on morphological attributes derived from deformation fields estimated by deformable registration of individual images to population templates built using groupwise registration. The approach combines a multi-region analysis of brain structures, 3D Shape Context descriptors, Jacobian determinants, the strain tensor, and machine learning. The first contribution estimates brain age in cognitively normal individuals, achieving a mean absolute error of 1.66 years for males and 1.81 years for females, with coefficients of determination of 0.84 and 0.80, respectively. The second contribution is a multi-region classification framework for distinguishing cognitively normal individuals, subjects with mild cognitive impairment, and patients with Alzheimer’s disease, achieving an AUC of 0.93 and an accuracy of 88.68% for males, and an AUC of 0.94 with an accuracy of 87.89% for females in the classification between cognitively normal individuals and Alzheimer’s patients. The third contribution proposes a graph-based approach for identifying progressive mild cognitive impairment, integrating displacement attributes, Jacobian volumetric variation, and local strain into a fixed population-level topology processed by a Graph Attention Network. This approach achieved an AUC of 0.92, an accuracy of 81.21%, and an F1-score of 0.79 for males, and an AUC of 0.88, an accuracy of 78.41%, and an F1-score of 0.73 for females. Taken together, the results indicate that morphological attributes derived from deformation fields can characterize brain aging, discriminate diagnostic groups, and contribute to differentiating individuals with stable and progressive mild cognitive impairment.
Comportamento de corrosão eletroquímica de ligas inoxidáveis com efeito de memória de forma Fe-Mn-Si-Cr-Ni-(Co) em soluções simuladas de poro de concreto
(Universidade Federal de São Carlos, 2026-09-14) Aviles, David José Barreto; Silva, Rodrigo; http://lattes.cnpq.br/3763016865133213; https://orcid.org/0000-0002-1381-1334; Rovere, Carlos Alberto Della; http://lattes.cnpq.br/8141224513975606; https://orcid.org/0000-0003-1534-0561; https://lattes.cnpq.br/6135884254948694; https://orcid.org/0000-0002-0946-0033; Magalhães, Danielle Cristina Camilo; Mendes Filho, Anibal de Andrade; http://lattes.cnpq.br/5486724956564584; http://lattes.cnpq.br/4033093647135538; https://orcid.org/0000-0001-5857-4902; https://orcid.org/0000-0002-6230-8196
Fe-Mn-Si-Cr-Ni-(Co) shape memory stainless steel (SMSS) are being studied for structural applications due to their combination of lower cost and properties such as strain recovery, prestressing force generation, and energy dissipation during seismic events. However, their performance in cementitious environments subject to carbonation and chloride contamination - particularly in coastal regions - remains insufficiently understood. This study characterized the microstructure and electrochemical behavior of three SMSSs (A, B, and C) in synthetic concrete pore solutions - pH 13.8 (freshly cured) and pH 8.5 (carbonated), both without and with 0.1 M NaCl - comparing them to SAE 1020 and SAE 304 steels. Techniques employed included OM, SEM/EDS, XRD, potentiodynamic and cyclic polarization, EIS, and XPS. At pH 13.8, all materials exhibited stable passivity with low current densities. Upon reducing the pH to 8.5, the three SMSSs and SAE 304 remained passive, whereas SAE 1020 exhibited active behavior and an icorr approximately 30 times higher; furthermore, it generated a potential difference of ≈ 400 mV , indicating a severe risk of galvanic corrosion. With the addition of chlorides at pH 8.5, SMSSs A and B underwent localized corrosion, with breakdown potentials (Eb) of +677 and +930 mVAg/AgCl, respectively; conversely, SMSS C and AISI 304 remained in a passive state (Eb +1050 mVAg/AgCl). SAE 1020 was the most affected, with its Eb dropping from +1080 to +140 mVAg/AgCl. XPS analysis revealed passive films enriched in Si and Cr and depleted in Fe and Mn on the SMSSs, ensuring protection even in a carbonated environment. It is concluded that SMSS C is the most promising for use in reinforced concrete in saline environments; however, avoiding galvanic contact with carbon steel in carbonated concrete is recommended to ensure durability.