Browsing by Issue Date, starting with "2025-12"
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- The spillover effect of ADR activity on stock price synchronicity: empirical evidence in emerging marketsPublication . Viana Junior, Dante Baiardo C.This study investigates the intra-industry spillover effect of American Depositary Receipt (ADR) issuance on the stock price synchronicity of non-ADR firms from emerging markets. Based on a sample of listed firms from six Latin American countries, although I find some evidence of a decrease in stock price synchronicity among ADR issuers in post-ADR issuance periods, the main findings suggest that non-ADR firms from industries with ADR issuance activity have higher levels of synchronicity on average than non-ADR firms from industries with no ADR issuance activity. These cross-country average results are robust to different regression methods and alternative subsamples employed to mitigate endogeneity concerns. Even though this trend is confirmed for the majority of the Latin American countries under review, individual-country analyses indicate a synchronicity-decreasing effect of ADR industry activity, particularly for non-ADR Chilean firms. Complementary, more in-depth empirical analyses suggest that country-level factors and ADR firm characteristics play an essential role in this issue. My main findings document that the overall positive spillover effect of ADR activity on the stock price synchronicity of non-ADR firms in Latin America is non-monotonic. These exploratory findings contribute to the active debate regarding the impact of ADR issuance on local economies, particularly with respect to the informativeness of financial reporting available in the capital markets.
- Nutritional composition of the unexplored mediterranean plant urospermum dalechampii (L.) Scop. ex F.W.Schmidt from TunisiaPublication . Hammami, Nourhen; Rodrigues, Maria João; M’rabet, Yassine; Saadellaoui, Wissal; Hosni, Karim; Stambouli-Essassi, Sondes; Hannachi, HédiaUrospermum dalechampii (L.), commonly known as Mediterranean daisy, is an unexplored herbaceous species from the Asteraceae family. This study aims to compare the proximate composition, mineral content and fatty acid profile of its aerial parts and roots. Carbohydrates (46.60–78.00 %), proteins (5.40–13.50 %) and crude fiber (10.40–24.60 %) were the major components in both parts. Ash content were significantly (p < 0.05) higher in aerial parts (13.80 %) and was predominantly composed of potassium, calcium and sodium as macroelements, while iron, zinc and copper were the major trace elements. The oil contents were low in the both studied parts (1.00–1.50 %) and were mostly composed of unsaturated fatty acids (oleic > linolenic > linoleic in the aerial parts versus oleic > linoleic > linolenic in roots) with high nutritional quality having high UFA/SFA, ω-3/ω-6 ratios, low AI, TI and h/H indexes. These results revealed that Urospermum dalechampii could serves as a source of essential minerals, fatty acids, fiber, protein, carbohydrates reflecting its potential applications in food/feed and pharmaceutical fields.
- Monitoring soil conservation techniques via UAV for sustainable production of intercropped forage cactus with reuse water in the Brazilian semiarid regionPublication . Sousa, Lizandra de Barros de; Montenegro, Abelardo Antônio de Assunção; Isidoro, Jorge; Silva, Thieres George Freire da; Almeida, Thayná Alice Brito; Lima, João Luis Mendes Pedroso de; Giongo, Pedro Rogério; Jardim, Alexandre Maniçoba da Rosa Ferraz; Silva, Marcos Vinícius da; Silva, Ênio Farias de França e; Lima, Breno Leonan de CarvalhoContext: Sustainable agricultural production in semiarid regions is limited by water scarcity and soil degradation. Forage cactus (Opuntia stricta) has high drought tolerance but requires effective water and soil management to maximize yield. Objective: To evaluate the effects of mulching and intercropping with gliricidia and moringa, under treated wastewater irrigation, on forage cactus productivity and soil properties, and to assess the utility of UAV-based remote sensing and machine learning for field-scale monitoring and yield prediction. Materials and methods: A 15-month field experiment was conducted in Northeastern Brazil using a randomized block design (3 × 2 factorial; six treatments; four replicates). Treatments combined mulching (with and without mulch) and intercropping (gliricidia, moringa, or none). Biometric (height, cladode count), biomass (fresh and dry matter yield), and soil (organic carbon, electrical conductivity, moisture) variables were measured. Highresolution UAV multispectral imagery provided vegetation indices. Geostatistical analysis was applied for spatial variability mapping, and a Random Forest model predicted fresh matter yield (R² criterion). Results: Mulching increased forage cactus height by 21 % and fresh matter yield by 70 % (p < 0.05), raised soil organic carbon by 133 %, and reduced salinity by 61 %. Intercropping with gliricidia further improved fresh matter yield by 59.7 % and soil moisture compared to the non-intercropped control. UAV-derived indices (e.g., NDVI, vNDVI) correlated strongly with measured yields (r > 0.75), and the Random Forest model achieved R² = 0.83 in yield prediction. Conclusions: Under irrigation with treated wastewater, mulching and intercropping (particularly intercropping with gliricidia) were associated with the highest forage cactus productivity and improved soil indicators in semiarid conditions. UAV monitoring with machine learning supported field-scale diagnostics and fresh matter yield prediction.
- Labour intensity and systematic riskPublication . Francisco, Paulo MoraisWe examine whether firms labour intensity raises systematic risk. Drawing on 12,250 listed, non financial companies from 93 countries, we analyse CAPM betas over five , three and two year windows and separately evaluate their upside (β+) and downside (β− ) components. OLS results show that a one standard deviation increase in labour intensity lifts the five year beta by 0.08 and loads disproportionately on downside risk. Instrumenting labour intensity in a 2SLS framework magnifies the effect, confirming a causal link. Overall, our evidence shows that labour intensive firms worldwide carry higher betas because fixed wage bills magnify operating leverage; the extra risk is most visible when markets decline, making a company’s workforce composition a key driver of its equity risk.
- Joint model for zero-inflated data combining fishery-dependent and fishery-independent sourcesPublication . Silva, Daniela; Menezes, Raquel; Araújo, Gonçalo; Rosa, Renato; Moreno, Ana; Silva, Alexandra; Garrido, SusanaAccurately identifying spatial patterns of species distribution is crucial for scientific insight and societal benefit, aiding our understanding of species fluctuations. The increasing quantity and quality of ecological datasets present heightened statistical challenges, complicating spatial species dynamics comprehension. Addressing the complex task of integrating multiple data sources to enhance spatial fish distribution understanding in marine ecology, this study introduces a pioneering five-layer Joint model. The model adeptly integrates fishery-independent and fishery-dependent data, accommodating zero-inflated data and distinct sampling processes. A comprehensive simulation study evaluates the model performance across various preferential sampling scenarios and sample sizes, elucidating its advantages and challenges. Our findings highlight the model’s robustness in estimating preferential parameters, emphasizing differentiation between presence–absence and biomass observations. Evaluation of estimation of spatial covariance and prediction performance underscores the model’s reliability. Augmenting sample sizes reduces parameter estimation variability, aligning with the principle that increased information enhances certainty. Assessing the contribution of each data source reveals successful integration, providing a comprehensive representation of biomass patterns. Empirical application within a real-world context further solidifies the model’s efficacy in capturing species’ spatial distribution. This research advances methodologies for integrating diverse datasets with different sampling natures further contributing to a more informed understanding of spatial dynamics of marine species.
- Optimizing chlorella vulgaris production and exploring its impact on germination through microalga-N2-fixing bacteria consortiaPublication . Sanchez-Zurano, Ana; Vilaró-Cos, Silvia; Rodrigues Figueiredo, Daniel; Melkonyan, Lusine; Ferreira, Alice; Acién, Francisco Gabriel; Lafarga, Tomas; Gouveia, LuisaMicroalgal biomass is increasingly valued in industrial and agricultural sectors due to its bioactive compounds. However, large-scale production remains costly, mainly due to nitrogen fertilizer expenses. A promising sustainable alternative is co-cultivation with N2-fixing bacteria, capable of supplying biologically available nitrogen. In this study, Chlorella vulgaris was grown in synthetic medium with and without nitrogen, as well as in co-culture with three different N2-fixing bacteria in nitrogen-free medium. Microalgal growth was assessed by dry weight, Fv/Fm ratio, and flow cytometry, which also allowed evaluation of population dynamics and cell viability. Biomass composition (proteins, carbohydrates, lipids, chlorophyll, and carotenoids) was analyzed under all conditions. Co-cultures in nitrogen-free medium showed comparable biomass productivity to nitrogensupplemented controls, although Fv/Fm values indicated physiological stress in some cases. Moreover, the agricultural potential of the resulting biomass and supernatants was evaluated through germination bioassays using lettuce seeds. All cultures tested at 0.2 g⋅L− 1 significantly improved the germination index. Also, applying the culture supernatant (biomass removed) also yielded positive effects, with GI increases exceeding 40 %. These results suggest that co-cultivation with N2-fixing bacteria can support efficient microalgal production while generating biomass and supernatants with biostimulant potential, contributing to sustainable agriculture and circular bioeconomy strategies.
- EEG responses to auditory cues during speech preparation predict stuttering severity and intervention outcomePublication . Rocha, Mónica; Carmona, Jaqueline; Correia, JoaoStuttering is a variable speech disorder whose brain mechanisms remain unknown. Sensorimotor brain circuits, critical in motor-speech control, including the prediction and monitoring of speech consequences, have been linked to the disorder. Despite considerable advances, it remains unclear whether auditory neural circuits relate to stuttering severity, and whether interventions to persons who stutter can induce underlying brain changes. We employed electroencephalography (EEG), in a group of persons who stutter (PWS), in combination with auditory probes to tap onto the relevance of auditory cortical regions in stuttering severity. Participants produced flexible speech (i.e., describing pictures) and non-flexible speech (i.e., reading syllables), following an auditory cue. More pronounced P200 auditory evoked potentials in response to the auditory cues were observed in participants with more severe stuttering, mainly in the picture task. Interestingly, while speech therapy intervention led to a reduction (albeit non-significant) of the P200 potential, this reduction was marginally correlated to speech fluency improvements. Moreover, EEG response patterns discriminative of cue tone frequency (400 Hz versus 800 Hz) were also predictive of stuttering severity, suggesting the involvement of fine-grained auditory cortical processing in speech preparation and stuttering. Overall, this study confirms a relationship between auditory processing of external sounds and the mechanisms of stuttering during the preparation to speak and highlights the advantage of a picture description task to investigate the relationship between auditory evoked potentials and stuttering severity under relatively ecological conditions.
- Causas do abandono dos idosos pelos seus familiares em contexto hospitalar: um olhar desde a educação socialPublication . Jerónimo, Maria de Lurdes Madeira da Luz; Anica, AuríziaO envelhecimento demográfico em Portugal tem gerado uma série de desafios sociais e económicos, destacando-se o aumento de idosos em situação de dependência e a escassez de recursos familiares e institucionais para garantir os cuidados necessários. Este estudo visa compreender as causas que levam ao abandono de idosos pelos seus familiares em contexto hospitalar, através de uma abordagem qualitativa centrada no Hospital de Faro, na região do Algarve. Esta região, caracterizada por um índice de envelhecimento elevado, reflete de forma particularmente evidente os problemas associados à falta de respostas sociais e de saúde para a terceira idade. Optou-se por desenhar um estudo de caso, tendo sido recolhidos os dados por meio de entrevistas semiestruturadas realizadas a pacientes internados no Hospital e a uma assistente social. Os resultados apontam para a existência de vários fatores que contribuem para o abandono de idosos, incluindo o esgotamento das famílias devido à conciliação entre vida profissional e cuidados ao idoso, a inexistência ou insuficiência de políticas públicas de apoio, e a limitada capacidade das Estruturas Residenciais para Pessoas Idosas (ERPI) e da Rede Nacional de Cuidados Continuados Integrados (RNCCI). Este estudo conclui que o abandono de idosos em hospitais é um reflexo das falhas nas redes de apoio social e familiar, bem como das carências nas políticas públicas. Para mitigar esta problemática, são sugeridas soluções como o reforço das políticas de cuidados domiciliários, o aumento da capacidade de resposta das ERPI e da RNCCI, e a promoção de estratégias de educação social que fortaleçam os laços intergeracionais e a responsabilidade social para com os idosos.