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Publicações

2025

Exploring image and skeleton-based action recognition approaches for clinical in-bed classification of simulated epileptic seizure movements

Autores
Karácsony, T; Fearns, N; Birk, D; Trapp, SD; Ernst, K; Vollmar, C; Rémi, J; Jeni, LA; De la Torre, F; Cunha, JPS;

Publicação
EXPERT SYSTEMS WITH APPLICATIONS

Abstract
Epileptic seizure classification based on seizure semiology requires automated, quantitative approaches to support the diagnosis of epilepsy, which affects 1 % of the world's population. Current approaches address the problem on a seizure level, neglecting the detailed evaluation of the classification of the underlying action features, also known as Movements of Interest (MOIs), which are critical for epileptologists in determining their classifications. Moreover, it hinders objective comparison of these approaches and attribution of performance differences due to datasets, intra-dataset MOI distribution, or architecture variations. Objective evaluation of action recognition techniques is crucial, with MOIs serving as foundational elements of semiology for clinical in-bed applications to facilitate epileptic seizure classification. However, until now, there were no MOI datasets available nor benchmarks comparing different action recognition approaches for this clinical problem. Therefore, as a pilot, we introduced a novel, simulated seizure semiology dataset carried out by 8 experienced epileptologists in an EMU bed, consisting of 7 MOI classes. We compare several computer vision methods for MOI classification, two image-based (I3D and Uniformerv2), and two skeleton-based (ST-GCN++ and PoseC3D) action recognition approaches. This study emphasizes the advantages of a 2-stage skeleton-based action recognition approach in a transfer learning setting (4 classes) and the multi-scale challenge of MOI classification (7 classes), advocating for the integration of skeleton-based methods with hand gesture recognition technologies in the future. The study's controlled MOI simulation dataset provides us with the opportunity to advance the development of automated epileptic seizure classification systems, paving the way for enhancing their performance and having the potential to contribute to improved patient care.

2025

Exploring the role of product attributes in 9-ending pricing strategies: A study on online retailing

Autores
Gonçalves, MG; Barbosa, B; Saura, JR; Mariani, M;

Publicação
JOURNAL OF BUSINESS RESEARCH

Abstract
This study investigates the use of 9-ending pricing strategies in e-commerce by analyzing over 50,000 shoe prices. Using web scraping and a logit model from a German online retailer, the research assesses how product attributes influence the adoption of 9-ending prices. Key findings reveal that 9-ending prices are predominantly used for female and newly introduced products, as well as for items with lower and standard prices. The study also explores the effects of exclusivity and sustainability on pricing strategies, showing that their impact varies with different 9-ending price categories. Overall, this research demonstrates the complex nature of 9-ending pricing strategies, with the 9-zero removal model supporting all hypotheses, whereas the 99c and 95c models show differential effects. This extends our understanding of pricing tactics in online retail and highlights the significance of product attributes for marketing and sales strategies.

2025

ECG Biometrics

Autores
Pinto, JR; Cardoso, S;

Publicação
Encyclopedia of Cryptography, Security and Privacy, Third Edition

Abstract
[No abstract available]

2025

Towards Non-invasive Detection of Gastric Intestinal Metaplasia: A Deep Learning Approach Using Narrow Band Imaging Endoscopy

Autores
Capela, S; Lage, J; Filipe, V;

Publicação
DISTRIBUTED COMPUTING AND ARTIFICIAL INTELLIGENCE, SPECIAL SESSIONS II, 21ST INTERNATIONAL CONFERENCE

Abstract
Gastric cancer, ranking as the sixth most prevalent cancer globally and a leading cause of cancer-related mortality, follows a sequential progression known as Correa's cascade, spanning from chronic gastritis to eventual malignancy. Although endoscopy exams using NarrowBand Imaging are recommended by internationally accepted guidelines for diagnostic Gastric Intestinal Metaplasia, the lack of endoscopists with the skill to assess the NBI image patterns and the disagreement between endoscopists when assessing the same image, have made the use of biopsies the gold standard still used today. This proposal doctoral thesis seeks to address the challenge of developing a Computer-Aided Diagnosis solution for GIM detection in NBI endoscopy exams, aligning with the established guidelines, the Management of Epithelial Precancerous Conditions and Lesions in the Stomach. Our approach will involve a dataset creation that follows the standardized approach for histopathological classification of gastrointestinal biopsies, the Sydney System recommended by MAPS II guidelines, and annotation by gastroenterology experts. Deep learning models, including Convolutional Neural Networks, will be trained and evaluated, aiming to establish an internationally accepted AI-driven alternative to biopsies for GIM detection, promising expedited diagnosis, and cost reduction.

2025

Unipolar and non-volatile RF switches using MoS2 by liquid-liquid interface assembly for millimeter wave applications

Autores
Tomás Mingates; Mohamed Ghatas; Jonas Deuermeier; Joe Neilson; Adam Kelly; Jonathan Coleman; Luís Mendes; João Vaz; Sérgio Matos; Luca Lucci; Antonio Clemente; Zdenek Sofer; Luís Pessoa; Elvira Fortunato; Rodrigo Martins; Asal Kiazadeh;

Publicação

Abstract
Abstract

This study presents the first application-ready demonstration of radio-frequency (RF) switches based on memristors fabricated through a combination of electrochemical exfoliation and liquid-liquid interfacial assembly (EC-LL). This 2D layer fabrication method yields uniform, low-defect bilayer MoS2 nanosheet networks without relying on high-temperature processes or hazardous gases typical of chemical vapor deposition (CVD), offering a low-cost and environmentally friendly route towards CMOS-compatible integration. Remarkably, the resulting devices exhibit robust unipolar resistive switching which simplifies biasing requirements and reduces power consumption. Reproducibility with retention of 104 sec, and endurance of 100 cycles is reported. RF measurements confirm reliable operation at millimeter wave (mmWave) frequencies across 10–110 GHz, demonstrating low insertion loss (0.42–0.9 dB), isolation >18 dB, and an intrinsic cut-off frequency of ~5.4 THz. Integration into Reconfigurable Intelligent Surface Unit Cells (RIS-UCs) further showcases the technology’s utility in next-generation mmWave communication systems, including 5G/6G and satellite applications. Simulations of a 24×24-element RIS panel confirm high gain (>21.6 dBi) and efficient beam steering (-60º, 60º degrees) over the 26.8–29.1 GHz band, while the ultra-low switching energy (~330 pJ per unit cell) enables zero static power consumption—critical for scalable and sustainable 6G infrastructure. This work establishes a new benchmark by delivering the first solution-processed, application-suitable 2D material in solid-state RF switches combining non-volatility, high-frequency operation, and CMOS integration potential. It marks a significant step toward reconfigurable, energy-efficient wireless communication platforms.

2025

Fiber Laser LIBS as a Sensing Tool for Chemical Mapping of Heritage Tiles

Autores
Capela, D; Manso, M; Lopes, T; Cavaco, R; Teixeira, J; Jorge, PAS; Silva, NA; Guimaraes, D;

Publicação
29TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS

Abstract
Heritage preservation requires innovative sensing technologies to analyze their chemical composition while minimizing damage. This study introduces a Laser-induced Breakdown Spectroscopy (LIBS) system featuring a fiber laser source and optical fiber-based collection system for the analysis of heritage ceramics. Comparative experiments with a conventional Nd:YAG laser LIBS system highlight the advantages and trade-offs of the fiber laser system in terms of ablation capability, spectral mapping, and depth profiling. Results were validated against X-ray Fluorescence (XRF). Experiments demonstrate minimal surface alteration and high-quality spectral data for elements such as Pb, Fe, Zn, Sb, Mn, Ti Na, Ba and Ca. The compact design and good results position this system as a transformative tool for heritage conservation.

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