2024
Authors
Pereira, RC; Abreu, PH; Rodrigues, PP; Figueiredo, MAT;
Publication
EXPERT SYSTEMS WITH APPLICATIONS
Abstract
Experimental assessment of different missing data imputation methods often compute error rates between the original values and the estimated ones. This experimental setup relies on complete datasets that are injected with missing values. The injection process is straightforward for the Missing Completely At Random and Missing At Random mechanisms; however, the Missing Not At Random mechanism poses a major challenge, since the available artificial generation strategies are limited. Furthermore, the studies focused on this latter mechanism tend to disregard a comprehensive baseline of state-of-the-art imputation methods. In this work, both challenges are addressed: four new Missing Not At Random generation strategies are introduced and a benchmark study is conducted to compare six imputation methods in an experimental setup that covers 10 datasets and five missingness levels (10% to 80%). The overall findings are that, for most missing rates and datasets, the best imputation method to deal with Missing Not At Random values is the Multiple Imputation by Chained Equations, whereas for higher missingness rates autoencoders show promising results.
2024
Authors
Silva, A; Mendes Moreira, J; Ferreira, C; Costa, N; Dias, D;
Publication
COMPUTERS AND ELECTRONICS IN AGRICULTURE
Abstract
In this paper, a solution to monitor the location of humans during their activity in the agriculture sector with the aim to boost productivity and efficiency is provided. Our solution is based on map-matching methods, that are used to track the path spanned by a worker along a specific activity in an agriculture culture. Two different cultures are taken into consideration in this study olives and vines. We leverage the symmetry of the geometry of these cultures into our solution and divide the problem three-fold initially, we estimate a path of a worker along the fields, then we apply the map-matching to such path and finally, a post-processing method is applied to ensure local continuity of the sequence obtained from map-matching. The proposed methods are experimentally evaluated using synthetic and real data in the region of Mirandela, Portugal. Evaluation metrics show that results for synthetic data are robust under several sampling periods, while for real-world data, results for the vine culture are on par with synthetic, and for the olive culture performance is reduced.
2024
Authors
Mou, JJ; Brito, PQ;
Publication
LEISURE SCIENCES
Abstract
While place attachment has been a hot research topic in tourism, place meanings generally have received less attention from researchers. By bridging environmental psychology to the context of tourism, this research employs schema theory to explore how the home environment influences place meanings perceived in foreign destinations by tourists belonging to the same cultural group, i.e., Chinese and Macau outbound tourists in Europe. Semi-structured interviews were conducted, and the findings show that there is much overlap in both groups' place meanings regarding Europe as they are culturally Chinese. Nonetheless, the Portuguese symbolic settings of their home environment are profoundly integrated in the Macau interviewees' autobiographical memories and self-identity, which turns them into "vicarious insiders" of Portugal prior to their actual visits, thus rendering Portugal a specifically meaningful destination. This study makes theoretical contributions to the tourism place literature and provides practical implications regarding meaning marketing for destination management organizations.
2024
Authors
Mou, JJ; Brito, PQ;
Publication
JOURNAL OF DESTINATION MARKETING & MANAGEMENT
Abstract
Vicarious experiences in tourism possess significant marketing implications. While numerous studies have explored how various forms of vicarious experiences can impact an individual, the role of different time spans as a key factor determining the extent of said impact has been neglected in prior research. To address this gap, the present study thus bridges environmental psychology with the context of tourism and applies the theory of mental representations. An experiment (n = 359) was designed to examine differences in select mental representation dimensions (cognitive, affective, conative, and sensorial) among male and female Chinese college students who have zero/medium/maximum durations of constant vicarious experiences related to European destinations in their home environment. The results indicate that the medium duration of constant vicarious experiences leads to the most positive changes in cognitive and conative dimensions, while the longest constant vicarious experiences produce desirable affective dimension outcomes. Moreover, male college students seem to be more susceptible to the influences of such constant vicarious experiences.
2024
Authors
adrien.becue@gmail.com, B; Gama, J; Quelhas Brito, P;
Publication
Abstract
2024
Authors
da Silva, FR; Camacho, R; Tavares, JMRS;
Publication
ELECTRONICS
Abstract
Medical image analysis is crucial for the efficient diagnosis of many diseases. Typically, hospitals maintain vast repositories of images, which can be leveraged for various purposes, including research. However, access to such image collections is largely restricted to safeguard the privacy of the individuals whose images are being stored, as data protection concerns come into play. Recently, the development of solutions for Automated Medical Image Analysis has gained significant attention, with Deep Learning being one solution that has achieved remarkable results in this area. One promising approach for medical image analysis is Federated Learning (FL), which enables the use of a set of physically distributed data repositories, usually known as nodes, satisfying the restriction that the data do not leave the repository. Under these conditions, FL can build high-quality, accurate deep-learning models using a lot of available data wherever it is. Therefore, FL can help researchers and clinicians diagnose diseases and support medical decisions more efficiently and robustly. This article provides a systematic survey of FL in medical image analysis, specifically based on Magnetic Resonance Imaging, Computed Tomography, X-radiography, and histology images. Hence, it discusses applications, contributions, limitations, and challenges and is, therefore, suitable for those who want to understand how FL can contribute to the medical imaging domain.
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