2024
Authors
Druzsin, K; Biró, P; Klimentova, X; Fleiner, R;
Publication
CENTRAL EUROPEAN JOURNAL OF OPERATIONS RESEARCH
Abstract
In this paper we present simulations for international kidney exchange programmes (KEPs). KEPs are organised in more than ten countries in Europe to facilitate the exchanges of immunologically incompatible donors. The matching runs are typically conducted in every three months for finding optimal exchanges using hierarchical optimisation with integer programming techniques. In recent years several European countries started to organise international exchanges using different collaboration policies. In this paper we conduct simulations for estimating the benefits of such collaborations with a simulator developed by the team of the ENCKEP COST Action. We conduct our simulations on generated datasets mimicking the practice of the three largest KEPs in Europe, the UK, Spanish and the Dutch programmes. Our main performance measure is the number of transplants compared to the number of registrations to the KEP pools over a 5-year period, however, as a novelty we also analyse how the optimisation criteria play a role in the lexicographic and weighted optimisation policies for these countries. Besides analysing the performances on a single instance, we also conduct large number of simulations to obtain robust findings on the performance of specific national programmes and on the possible benefits of international collaborations.
2024
Authors
Ferreira, H; Marta, A; Couto, I; Camara, J; Beirao, JM; Cunha, A;
Publication
WIRELESS MOBILE COMMUNICATION AND HEALTHCARE, MOBIHEALTH 2023
Abstract
Inherited retinal diseases such as Retinitis Pigmentosa and Stargardt's disease are genetic conditions that cause the photoreceptors in the retina to deteriorate over time. This can lead to vision symptoms such as tubular vision, loss of central vision, and nyctalopia (difficulty seeing in low light) or photophobia (high light). Timely healthcare intervention is critical, as most forms of these conditions are currently untreatable and usually focused on minimizing further vision loss. Machine learning (ML) algorithms can play a crucial role in the detection of retinal diseases, especially considering the recent advancements in retinal imaging devices and the limited availability of public datasets on these diseases. These algorithms have the potential to help researchers gain new insights into disease progression from previous classified eye scans and genetic profiles of patients. In this work, multi-class identification between the retinal diseases Retinitis Pigmentosa, Stargardt Disease, and Cone-Rod Dystrophy was performed using three pretrained models, ResNet101, ResNet50, and VGG19 as baseline models, after shown to be effective in our computer vision task. These models were trained and validated on two datasets of autofluorescent retinal images, the first containing raw data, and the second dataset was improved with cropping to obtain better results. The best results were achieved using the ResNet101 model on the improved dataset with an Accuracy (Acc) of 0.903, an Area under the ROC Curve (AUC) of 0.976, an F1-Score of 0.897, a Recall (REC) of 0.903, and a Precision (PRE) of 0.910. To further assess the reliability of these models for future data, an Explainable AI (XAI) analysis was conducted, employing Grad-Cam. Overall, the study showed promising capabilities of Deep Learning for the diagnosis of retinal diseases using medical imaging.
2024
Authors
Perez, ER; Fina, B; Iglár, B; Monsberger, C; Maggauer, K; Weber, AB; Yiasoumas, G; Georghiou, G; Villar, J; Mello, J; Stanev, R;
Publication
Integrated Local Energy Communities: From Concepts and Enabling Conditions to Optimal Planning and Operation
Abstract
Integrated local energy communities (ILECs) introduction involves a set of challenges for the existing energy infrastructure. As a result of the development and research performed in projects on this topic, several guidelines and recommendations are formulated. This chapter recaps major problems of the implementation of ILECs identified in the reviewed literature and provides recommendations to overcome them by covering five dimensions. In the technical dimension, the implementation of strategies to avoid the grid reinforcement as well as coordination between system operators become crucial for the development of ILEC-related technologies. In terms of regulations, tax exemptions, additional financial funding, and simplification of paperwork for projects should be introduced backed by a clear EU strategy. In the environmental dimension, ILECs boost the transition toward decentralized renewable generation contributing to the gradual replacement of fossil-fuel generation plants and this benefit can be maximized by performing deeper environmental assessments. Additionally, there is a need of cost-effective financial tools for planning and management as well as the development of suitable economic incentives. Lastly, the implementation of strategies to increase the social acceptance of the ILEC paradigm through the organization of engagement activities between citizens, stakeholders, and other actors arises as the key action. © 2025 WILEY-VCH GmbH. Published 2025 by WILEY-VCH GmbH. All rights reserved.
2024
Authors
Rocha, J; Pereira, SC; Sousa, P; Campilho, A; Mendonca, AM;
Publication
SCIENTIFIC REPORTS
Abstract
An automatic system for pathology classification in chest X-ray scans needs more than predictive performance, since providing explanations is deemed essential for fostering end-user trust, improving decision-making, and regulatory compliance. CLARE-XR is a novel methodology that, when presented with an X-ray image, identifies the associated pathologies and provides explanations based on the presentation of similar cases. The diagnosis is achieved using a regression model that maps an image into a 2D latent space containing the reference coordinates of all findings. The references are generated once through label embedding, before the regression step, by converting the original binary ground-truth annotations to 2D coordinates. The classification is inferred minding the distance from the coordinates of an inference image to the reference coordinates. Furthermore, as the regressor is trained on a known set of images, the distance from the coordinates of an inference image to the coordinates of the training set images also allows retrieving similar instances, mimicking the common clinical practice of comparing scans to confirm diagnoses. This inherently interpretable framework discloses specific classification rules and visual explanations through automatic image retrieval methods, outperforming the multi-label ResNet50 classification baseline across multiple evaluation settings on the NIH ChestX-ray14 dataset.
2024
Authors
Mendes, J; Berger, GS; Lima, J; Costa, L; Pereira, AI;
Publication
ROBOT 2023: SIXTH IBERIAN ROBOTICS CONFERENCE, VOL 2
Abstract
This study compares two computer vision methods to detect yellow sticky traps using unmanned autonomous vehicles in olive tree cultivation. The traps aim to combat and monitor the density of the Bactrocera oleae, an important pest that damages olive fruit, leading to substantial economic losses annually. The evaluation encompassed two distinct methods: firstly, an algorithm employing conventional segmentation techniques like thresholding and contour localization, and secondly, a contemporary artificial intelligence approach utilizing YOLOv8, a state-of-the-art technology. A specific dataset was created to train and adjust the two algorithms. At the end of the study, both were able to locate the trap precisely. The segmentation algorithm demonstrated superior performance at proximal distances (50 cm), outperforming the outcomes achieved by YOLOv8. In contrast, YOLOv8 exhibited sustained precision, irrespective of the distance under examination. These findings affirm the versatility of both algorithms, highlighting their adaptability to various contexts based on distinct application demands. Consideration of trade-offs between accuracy and processing speed is essential in determining the most appropriate algorithm for a given application.
2024
Authors
Alves, S; Mackie, I;
Publication
DCM
Abstract
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