Papers by Ignacio Sánchez Gendriz
Computers in biology and medicine, May 1, 2024
medRxiv (Cold Spring Harbor Laboratory), Mar 13, 2024
Machine learning and knowledge extraction, Feb 5, 2024
Frontiers in artificial intelligence, Dec 7, 2023
Scientific Reports, Aug 8, 2023
Osteoporosis is a disease characterized by impairment of bone microarchitecture that causes high ... more Osteoporosis is a disease characterized by impairment of bone microarchitecture that causes high socioeconomic impacts in the world because of fractures and hospitalizations. Although dual-energy X-ray absorptiometry (DXA) is the gold standard for diagnosing the disease, access to DXA in developing countries is still limited due to its high cost, being present only in specialized hospitals. In this paper, we analyze the performance of Osseus, a low-cost portable device based on electromagnetic waves that measures the attenuation of the signal that crosses the medial phalanx of a patient's middle finger and was developed for osteoporosis screening. The analysis is carried out by predicting changes in bone mineral density using Osseus measurements and additional common risk factors used as input features to a set of supervised classification models, while the results from DXA are taken as target (real) values during the training of the machine learning algorithms. The dataset cons...
Scientific Reports
Dengue is recognized as a health problem that causes significant socioeconomic impacts throughout... more Dengue is recognized as a health problem that causes significant socioeconomic impacts throughout the world, affecting millions of people each year. A commonly used method for monitoring the dengue vector is to count the eggs that Aedes aegypti mosquitoes have laid in spatially distributed ovitraps. Given this approach, the present study uses a database collected from 397 ovitraps allocated across the city of Natal, RN—Brazil. The Egg Density Index for each neighborhood was computed weekly, over four complete years (from 2016 to 2019), and simultaneously analyzed with the dengue case incidence. Our results illustrate that the incidence of dengue is related to the socioeconomic level of the neighborhoods in the city of Natal. A deep learning algorithm was used to predict future dengue case incidence, either based on the previous weeks of dengue incidence or the number of eggs present in the ovitraps. The analysis reveals that ovitrap data allows earlier prediction (four to six weeks)...
Despite the extensive Brazilian coast areas, little is known on underwater acoustic environments ... more Despite the extensive Brazilian coast areas, little is known on underwater acoustic environments in Brazil. Acoustic environments (or soundscape) are composed by biological, geological and man-made sound sources. Soundscapes are strongly linked to ecosystems dynamics, and follow temporal patters that can vary at daily and seasonal scales. Thus, for soundscape characterization, it is necessary to undertake sound recordings for long periods, which demands innovative analyzing methods. Accordingly, the present research focuses in two principal objectives: (1) to develop methods for analyzing long-term acoustic recordings and, (2) to characterize marine soundscapes of selected points in São Paulo State. Four deployment sites were selected for the underwater acoustic monitoring: a point located at the channel entrance of the Santos Harbor, and three marine Protected Areas (PAs) in Sao Paulo state. As a result, the largest underwater acoustic database from Brazilian seas was acquired. The...
The role of sleep on memory consolidation is thought to involve experience-dependent changes in s... more The role of sleep on memory consolidation is thought to involve experience-dependent changes in spindle oscillations and protein phosphorylation, but how these phenomena are related remains poorly understood. To gain insight into this relationship, we used electrophysiological recordings and quantitative phosphoproteomic analysis to assess spindle oscillations and phosphoprotein levels in the hippocampus (HP) and primary somatosensory cortex (S1) of adult male rats recorded across the sleep cycle. Animals were surgically implanted with multielectrode probes and after recovery were exposed or unexposed to novel objects (+ and – groups, respectively). HP and S1 samples were obtained after periods rich in either slow-wave sleep (SWS) or rapid-eye-movement sleep. Bottom-up shotgun mass spectrometry in a two-dimensional liquid chromatography-tandem mass spectrometry setup (MSE mode with label-free quantification) showed that the proteomes differed in the numbers of phosphoproteins identi...
Confins
As cidades inteligentes, como aposta para a gestao urbana, tem despertado a atencao de pesquisado... more As cidades inteligentes, como aposta para a gestao urbana, tem despertado a atencao de pesquisadores e gestores publicos ao redor do mundo. Em 2020, na Regiao Nordeste do Brasil, 36 municipios estao categorizados como “cidades inteligentes”. Este artigo descreve os metodos usados para analisar, visualizar e discutir algumas informacoes sobre essas 36 cidades. A utilizacao de mapas tematicos permitiu demonstrar, numa perspectiva espacial, algumas caracteristicas desses municipios, e sua associacao ao uso de metodos de mineracao de dados e a uma perspectiva teorica critica mostrou-se util para compreender as dinâmicas territoriais das cidades inteligentes. Ao combinar variaveis das cidades pesquisadas, a analise de componentes principais e o agrupamento hierarquico identificaram automaticamente similaridades e diferencas entre elas. Em comparacao com as metropoles e capitais incluidas neste estudo, e tomando-se como referencia a REGIC 2007, os resultados mostram-se uteis para identificar as cidades com potencialidades para melhor promover e/ou abrigar dinâmicas territoriais caracteristicas de cidades inteligentes, que sao: Jaboatao dos Guararapes-PE, Olinda-PE, Igarassu-PE, Sao Lourenco da Mata-PE, Moreno-PE, Itapissuma-PE, que fazem parte da Regiao Metropolitana de Recife; e Parnamirim-RN, pertencente a Regiao Metropolitana de Natal.
Expert Systems with Applications
SÁNCHEZ-GENDRIZ, I.. A Methodology for analyzing data from long-term passive acoustic monitoring.... more SÁNCHEZ-GENDRIZ, I.. A Methodology for analyzing data from long-term passive acoustic monitoring. 2017. 97 f. Doctoral dissertation (Doctorate Candidate in Science.
Brazilian Archives of Biology and Technology
Venous refilling time (VRT) can diagnose the presence of venous diseases in lower limbs. In order... more Venous refilling time (VRT) can diagnose the presence of venous diseases in lower limbs. In order to calculate VRT it is necessary to determine the End of the Emptying Maneuvers (EEM). First Derivative Method (FDM) can be employed for automatic detection of the EEM, but its sensitivity to artifacts and noise can degrade its performance. In contrast, studies report that Area Triangulation Method (ATM) evinces effectiveness in biosignals point finding. This work compares the exactness of ATM and FDM for recognition of the EEM. The annotations made by 3 trained human observers on 37 photoplethysmography records were used as a reference. Bland-Altman graphics supported the analysis of agreement among human observers and methods, which was complemented with Analysis of variance and Multiple Comparisons statistical tests. Results showed that ATM is more accurate than FDM for automatic detection of the EEM, with statistically significant differences (p-value < 0.01).
2012 XVII Symposium of Image, Signal Processing, and Artificial Vision (STSIVA), 2012
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Papers by Ignacio Sánchez Gendriz