FCT2-Artigos (em revistas ou actas indexadas)
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Percorrer FCT2-Artigos (em revistas ou actas indexadas) por Objetivos de Desenvolvimento Sustentável (ODS) "08:Trabalho Digno e Crescimento Económico"
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- Competitiveness of portuguese montado ewe production systems among the european ewe production systemsPublication . Ferreira da Silva da Costa Freitas, Maria de Belém; Ventura-Lucas, Maria Raquel; Izquierdo, Lola; Deblitz, ClausThe number of ewes in Portugal registers a decrease since 1998. This decrease is felt particularly in the south of the country, which concentrates almost half of the existing ewes, mainly for meat production. One of the most important ewe production systems is the Montado, a High Nature Value ecosystem, occupying ca. 1.2 million ha in Portugal. The competitiveness of this system among the European ewe production systems is an important issue for the future of the Montado ecosystem. So, the objective of this paper is to analyze the ewe production systems in the Montado, using the agri benchmark database, and compare these systems with other European countries’ systems, ranking their competitiveness and e_ciency among other systems in the European Union. We concluded that this methodology facilitated an in-depth understanding not only of the competitiveness and e_ciency of ewe production systems in Portugal but also of their positioning regarding other systems in the European Union. The pattern of returns assures that these farms are competitive in the sense that they depend on the market on their decisions, and thus it is important that market values sheep products. Nevertheless, the diversification to other income sources would be a good option for the future sustainability of these farms and the opportunities and risks that these systems will deal with in a new green economy, with probable new functions and new opportunities for land, will be a challenge for the future.
- Continual learning for object classification: integrating AutoML for binary classification tasks within a modular dynamic architecturePublication . Turner, Daniel; Cardoso, Pedro; Rodrigues, JoaoFor humans it is quite easy to identify a new object after learning to identify existing ones, but not for a machine. Deep neural networks (DNN) are the foundation of the current state-of-the-art methods for training machines to recognize sets of objects. The issue is that any modification to the DNN weights that were trained to classify an initial set of objects has the potential to seriously impair the network’s ability to make those initial classifications; this behaviour is referred to as catastrophic forgetting (CF). This paper presents a continual learning (CL) architecture that can deal with CF. The architecture is composed of two primary parts: (i) The feature extraction component, which is based on the ResNet50 backbone and (ii) the modular dynamic classification (MDC) component. The latter is made up of multiple sub-networks that gradually assemble themselves into a tree-like structure that reorganizes itself as it learns over time, so that each sub-network can operate independently. The MDC relies heavily on binary classification, and here the application of automated machine learning (AutoML) was introduced, where each binary classifier is tailored on-the-fly, and is/can be different from object to object. The strategy involves a calculated selection from a predefined list of model types and parameters, optimizing them for their respective tasks. Results demonstrate that we advanced the adaptability and performance of the network, emphasizing the transformative potential of AutoML in modular CL approaches. Tests on the CORe50 dataset showed accuracy results of 81.1%, which are above the state of the art for CL architectures.
- Mono-trophic seaweed polyculture of sea grapes (Caulerpa lentillifera) and Kappaphycus alvarezii: a case study from Van Phong Bay, Viet NamPublication . Stuthmann, Lara Elisabeth; Costa, Beatrice Brix da; Cordes, Aaron Johannes; Du, Hoang Trung; Kunzmann, Andreas; Springer, KarinKappaphycus alvarezii and Caulerpa lentillifera are economical important seaweeds cultivated in Van Phong Bay, Viet Nam, respectively. The complementary light and nitrogen requirements of the seaweeds introduce the opportunity for a mono-trophic seaweed polyculture. Three different set-ups were tested, namely the integration of K. alvarezii in sea grape ponds, the integration of sea grape plastic cages on longlines and the polyculture of both species in net cages. The relative growth rates (RGRs) of K. alvarezii were highest on longlines, compared to net cages in mono- and polyculture (4.4 ± 0.8 % day− 1 vs 2.1 ± 0.6, 0.6 ± 0.5 % day− 1 ), whereas fragments died off due to warm temperatures and absence of water movement in ponds. Strong recurring water movements at the experimental site caused high losses of K. alvarezii fragments (39 % of initial) and impaired growth of delicate C. lentillifera causing negative RGRs in all treatments (plastic cages without gauze: − 9.8 ± 0.6 % day− 1 , net cages: − 6.4 ± 0.9 % day− 1 ), but with least loss in plastic cages with gauze wrapping (-1.3 ± 0.8 % day− 1 ). Fv´/ Fm´values of both species showed typical midday depression and C. lentilliferas´Fv/Fm were influenced especially by gauze wrapping. Here, we show that the K. alvarezii cultivation on longlines with C. lentillifera integrated below in inexpensive, self-made, customizable plastic cages with additional gauze protection is the most promising set-up from a physiological and economic point of view for Van Phong Bay and beyond. However, further research is needed before implementation of the system.
- On farm non-agricultural activities: recent evolution and dynamics in PortugalPublication . Xavier, António; Rosário, Maria do Socorro; Carvalho, Maria Leonor Silva; Ferreira da Silva da Costa Freitas, Maria de Belémwhich constitute a complement to the farmer’s income and can function as a factor for the development of farms, enhancing the endogenous resources of the territories and contributing to the multifunctionality of rural areas. Therefore, it is relevant to understand the importance of these non-agricultural activities in the territory, their diversification, spatial trends at local level and the relation with farm’s orientation. This paper intends to analyse the OFNAA, using as object of study the Portuguese municipalities. To analyse the diversification of the OFNAA, a diversification index based on entropy is proposed. The relationships between OFNAA diversification and the farms’ technical-economic orientation (TEO) are also analysed using correlation matrixes, while the spatial patterns are studied, using the global Moran I and local Moran-LISA. The results provide important insights of the OFNAA dynamics and diversification. Therefore, this study provides an important tool for policy management and implementation.
- Physiological and psychological benefits of exposure to nature during work in a military bunker—a pilot experimental studyPublication . Silva Fernandes, Maria Jacinta; Bento, Ana Teresa; Gonçalves, Gabriela; Campos, ClariceThe present controlled experimental research addresses the effects of exposure to nature on workers’ well-being and job performance in a work-confined setting. Ten individuals working in an open-space office inside a Portuguese military bunker were exposed to simulated nature (audio sounds and/or video images of nature). Quantitative physiological (heart rate) and self-reported measures (perceived positive and negative emotions, environment restorativeness, and work performance) were taken. Results indicate that exposure to nature during working time in confined places, through simulating a window with a view of nature and/or by introducing sounds of nature, promotes physiological and emotional well-being at work (heart rate significantly decreases, positive emotions significantly increase, and negative emotions decrease), and significantly increases employees’ perception of workplace restorative qualities. The results on work performance were non-significant. The present findings contribute to the evidence of the restorative effects of nature exposure during work. The research bridges a gap by considering workplaces where real nature exposure is not feasible and examining the evidence on the beneficial biophilic interventions (the restorative effects of simulated nature) within confined environments. The strategy to use videos and audio of nature may improve the structural conditions of work, benefiting well-being in these types of work settings.
- Printed circuit boards leaching followed by synthesis of gold nanoparticle clusters using plant extractsPublication . Nobahar, Amir; Lourenço, João P.; Costa, Maria Clara; Carlier, JorgeThis work investigates the potential of 70% ethanolic leaf extracts of Rubus idaeus L., Cistus ladanifer L. and Erica andevalensis in the metal separation from synthetic unimetallic solutions of different metals and a leachate obtained from the leaching of PCBs. Results from the experiments with unimetallic solutions revealed R. idaeus and E. andevalensis extracts induced separation of more than 95% of the initial Au(III), while C. ladanifer separated ~78% of this metal. Thereafter, application of three plant extracts to real Au bearing leachate obtained from PCBs leaching, revealed about 96, 95 and 90% Au recovery with R. idaeus, C. ladanifer and E. andevalensis extracts, respectively with 15–60% co-removal of Pb and less than 15% of other metals. The reduction of Au(III) ions into Au(0) nanoparticles by R. idaeus extract was confirmed by molecular UV–Visible, and FT-IR analysis showed the involvement of plant secondary metabolites in Au bio-reduction and bio-stabilization. Particles obtained from the application of R. idaeus extract to the leachate were initially analyzed with XRD and results confirmed the presence of Au(0) with contamination of PbSO4, which was completely removed by washing with 1 M HCl. Thereafter, results from STEM-EDS analysis showed the presence of Au particles conjugated with organic material and other metals. Consequently, particles were subjected to another washing step with acetone. Afterwards, STEMEDS showed pure Au microparticle clusters (~0.8 μm) with flower-shaped or apparently cubic morphologies, and HRSTEM showed the tiny nanoparticles (~20 nm), which form the clusters.
- Self-organization of social hierarchies studied with Monte-Carlo simulations; self-destroying join-believe-fight system as an inevitable outcomePublication . Stallinga, PeterMonte-Carlo simulations were used to describe the interactions between cellular automata, socio-economic ‘agents’, in society. In a first simulation we repeat work in literature of a system of independent agents. We repeat the finding that the strongest agent will confiscate all wealth. In a second simulation we show how agents can prevent against such theft, or steal better, by joining forces. So-called join-believe fight (joining, believing unquestionably in the narrative of the faction, and fighting other factions). We now take cooperations between factions of joined agents into account. The final outcome is that society obliterates libertarians (those that are reluctant to join forces) and winds up in a situation in which all surviving agents are joined in a single faction. However, it is reasoned that then fights within this single faction will start, since this end situation resembles the starting point of entire society; the single faction has become entire society and the game recommences. It is a snake that bites its own tail and goes around forever attacking.
- Testing the diversifying asset hypothesis between clean energy stock indices and oil pricePublication . Dias, Rui; Galvão, Rosa; Cruz, Sandra P.; Irfan, Mohammad; Alexandre, Paulo; Gonçalves, Sidalina; Teixeira, Nuno; Palma, Cristina; Almeida, LilianaIn theory, geopolitical risk and political uncertainty can directly affect energy markets. Fluctuations lead to the cost of clean energy sources as they compete with traditional energy. The purpose of this study is to analyse financial integration and test the diversifying asset hypothesis between clean energy indices, specifically the Clean Energy Fuels (CLNE), Nasdaq Clean Edge Green Energy (CELS), S&P Global Clean Energy (SPGTCLEN), TISDALE Clean Energy (TCEC.CN), Wilderhill (ECO) and West Texas Intermediate (WTI) stock indices, over the period from 1 January 2018 to 23 November 2023. Analysing the results reveals a scenario where most of the clean energy indices show cointegration with each other, indicating long-term relationships that reflect common trends in the clean energy sector. However, the relative independence of the WTI suggests that Oil still acts as an important and potentially diversifying external factor for investors focused on sustainable energy. Structural breaks in 2021 and 2022 in several indices point to significant events that have altered market dynamics, possibly including changes in environmental policies, technological innovations and the impacts of the COVID-19 pandemic. The cointegration evidence and structural breaks provide valuable information for building investment portfolios. Investors can consider the WTI to diversify portfolios dominated by clean energy assets, taking advantage of Oil’s relative independence. On the other hand, the high correlation between clean energy indices suggests that, within this sector, diversification options are more limited, requiring careful analysis of the specific characteristics of each index and the macroeconomic forces affecting them.
- Tracking tourism waves: insights from automatic identification system (AIS) data on maritime–coastal activitiesPublication . Ramos, Jorge; Drakeford, Benjamin; Costa, Joana; Madiedo Camelo, Ana Maria; Leitão, FranciscoAbstract: The demand for maritime–coastal tourism has been intensifying, but its offerings are sometimes limited to a few activities. Some of these activities do not require specific skills or certifications, while others do. This study aimed to investigate what type of activities are carried out by tourism and recreational vessels in the coastal area of the central Algarve (Portugal). To this end, data from the automatic identification system (AIS) of recreational vessels was used to monitor and categorise these activities in a non-intrusive manner. A model (TORMA) was defined to facilitate the analysis of AIS data and relate them to five independent variables (distance from the coast, boat speed, bathymetry, seabed type, and number of pings). The results of the analysis of more than 11 thousand hourly AIS records for passenger, sailing, and charter vessels showed that the 14 most regular ones had strong seasonal patterns, greater intensity in summer, and spatial patterns with more records near some coastal cliffs. This study provides valuable information on the management of motorised nautical activities near the coast and at sea, contributing to more informed and effective tourism regulation and planning.