Percorrer por autor "Silva, Luís"
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- Avaliação do risco de fissuração por retração plástica em argamassas de revestimentoPublication . Oliveira, Miguel José Pereira das Dores Santos de; Silva, Luís; Sequeira, Pedro; Gonçalves, José VilhenaA seleção de argamassas de reabilitação ou reposição de edifícios antigos deve basear-se em critérios que garantam a compatibilidade funcional e estética com os materiais antigos remanescentes e toda a construção. A qualidade dos rebocos é um fator importante para a salubridade, conforto, durabilidade e aparência estética dos edifícios antigos e novos. A fissuração é um defeito com um impacto significativo no desempenho do revestimento, nomeadamente na sua impermeabilização e durabilidade, e um dos mais difíceis de avaliar e controlar, devido à sua dependência de vários fatores e também pela complexidade dos fenômenos. Depende de vários fatores que mudam no tempo como a evolução da retração, a relação entre o módulo de elasticidade e a resistência à tração e a capacidade da argamassa para dissipar tensões. Além disso, muitas dessas condições estão fortemente relacionadas com o ligante principal da argamassa. A retração plástica é um fenómeno comum e pode obrigar a cuidados especiais durante a aplicação. Em condições especiais, nomeadamente em grandes superfícies com altos índices de evaporação e altas temperaturas durante a aplicação podem surgir fissurações por retração plástica antes que a argamassa tenha endurecido completamente. Este tipo de fissuração deve ser totalmente evitado. As normas europeias estabelecem métodos de ensaios para argamassa de alvenaria. Por outro lado, apenas algumas entidades de investigação, como o LNEC, apresentam métodos para avaliação da resistência de uma argamassa à fissuração o que limita processos de avaliação expeditos, capazes de fornecer uma resposta preliminar rápida. Neste trabalho, dois métodos de ensaio diferentes são usados para avaliar a suscetibilidade à fissuração plástica em quatro argamassas diferentes. Particularmente um dos métodos é mais expedito e baseia-se na criação de diferentes condições de adesão numa superfície de um tijolo, em ambientes específicos. O segundo método centra-se na aplicação de argamassas em superfícies maiores que são colocadas num túnel de vento com diferentes temperaturas, humidades relativa e velocidade do vento. Através dos resultados obtidos foi possível fazer algumas considerações sobre o âmbito e limitações de cada método.
- The conversion of rockrose (Cistus ladanifer L.) shrubland into biodiverse pasturesPublication . Vieira, João; Filip, Iván Daniel; Soares Curado de Matos, Isabel Cristina; Rodrigues, Alessandra; Trindade, Ana Rita; Silva, Luís; Cassinello, João; Carita, Teresa; Ferreira da Silva da Costa Freitas, Maria de Belém; Neves, Maria AlcindaPastures in the Mediterranean region are vital for sustaining local agriculture and preserving biodiversity. When well-managed, these pastures enhance soil structure and fertility, reduce erosion, and improve water retention. These functions are especially critical in a climate marked by hot, dry summers and mild, wet winters. Moreover, these systems play a key role in carbon sequestration, contributing significantly to climate change mitigation. Mediterranean pastures also support the conservation of endemic plant species and provide essential habitats for a variety of wildlife. Quinta do Freixo (Algarve, Portugal) with an area around 800 hectares, is dedicated to sustainable agriculture and promotes ecological, economic and social sustainability. In addition to organic agriculture production, the farm also produces value-added food products and offers rural tourism experiences. On this farm, a dense shrubland of rockrose (Cistus ladanifer L.) is converted into pastures using a holistic method that includes mechanical cutting of the shrubs, spreading hay an regenerative rotational grazing (RRG) system. As a part of the project -C05-i03-I000237), these restored pastures are regularly monitored. Assessments included measurements of dry matter production and floristic composition. In addition, both the pastures and Cistus ladanifer shrublands were evaluated for the nutritional value and mineral composition of their foliage material. This approach has contributed to the development of species-rich pastures, rich in legumes and grasses and characterized by high protein content, excellent digestibility, and a well-balanced mineral composition. Although Cistus ladanifer had a relatively lower nutritional value due to its lower protein content and digestibility, the analysis showed that its aerial parts can serve as a supplementary feed resource, especially in periods of forage scarcity, contributing to overall feed availability in extensive grazing systems.The control of shrublands through this practice maintains biodiversity and reduces the risk of wildfires by effectively managing fuel loads.
- Palaeobiogeography of NE Atlantic archipelagos during the last Interglacial (MIS 5e): a molluscan approach to the conundrum of Macaronesia as a marine biogeographic unitPublication . Melo, Carlos S.; Marques da Silva, Carlos; Scarponi, Daniele; Martín-González, Esther; Rólán, Emilio; Rojas, Alejandra; Martinez, Sergio; Silva, Luís; Johnson, Markes E.; Cristina Rebelo, Ana; Baptista, Lara; Voelker, Antje; Ramalho, Ricardo S.; Ávila, Sérgio P.In order to understand the complex evolutionary processes and patterns that explain current island biodiversity, large datasets and long-term analysis are required. The Last Interglacial (LIG) was one of the warmest interglacials during the last million years. How species mobility changed during this period in the Macaronesia geographical region has long intrigued scientists. It is well established that the northward range expansion of tropical species occurred in the Macaronesian geographical region, but as a marine biogeographic unit, the term "Macaronesia" has not gained a consensus among the scientific community. For the first time, a thoroughly revised and updated checklist is presented for shallow-water marine molluscs from the Atlantic and Mediterranean during the LIG. Based on these wide ranging data, the status of Macaronesia as a marine biogeographic unit during the LIG was examined and our scientific understanding of how this unit evolved is improved. The analysis shows that during the LIG, the molluscan faunas of the Canary and Cabo Verde archipelagos were part of the same tropical Late Pleistocene Mediterranean West-African Province, whereas those in the Azores, Madeira and Selvagens archipelagos would be included in the subtropical Late Pleistocene French-Iberian Province. This contrasts with the present-day scenario, where the subtropical/warm temperate Azores and "Webbnesia" marine ecoregions (Lusitanian province) are biogeographically distinct from the Cabo Verde biogeographic subprovince, which in turn belongs to the West African Tropical biogeographic province. A further analysis of the coherence of "Macaronesia" as a marine biogeographical unit was accomplished by coupling Pliocene, LIG, and present-day data, showing that the term "Macaronesia", and for the marine realm, should only be used in a geographical connotation.
- Restructuring of the ‘Macaronesia’ biogeographic unit: a marine multi-taxon biogeographical approachPublication . Freitas, Rui; Romeiras, Maria; Silva, Luís; Cordeiro, Ricardo; Madeira, Patrícia; González, José Antonio; Wirtz, Peter; Falcón, Jesús M.; Brito, Alberto; Floeter, Sergio R.; Afonso, Pedro; Porteiro, Filipe; Viera-Rodríguez, María Ascensión; Neto, Ana Isabel; Haroun, Ricardo; Farminhão, João N. M.; Rebelo, Ana Cristina; Baptista, Lara; Melo, Carlos S.; Martínez, Alejandro; Núñez, Jorge; Berning, Björn; Johnson, Markes E.; Ávila, Sérgio P.The Azores, Madeira, Selvagens, Canary Islands and Cabo Verde are commonly united under the term "Macaronesia". This study investigates the coherency and validity of Macaronesia as a biogeographic unit using six marine groups with very different dispersal abilities: coastal fishes, echinoderms, gastropod molluscs, brachyuran decapod crustaceans, polychaete annelids, and macroalgae. We found no support for the current concept of Macaronesia as a coherent marine biogeographic unit. All marine groups studied suggest the exclusion of Cabo Verde from the remaining Macaronesian archipelagos and thus, Cabo Verde should be given the status of a biogeographic subprovince within the West African Transition province. We propose to redefine the Lusitanian biogeographical province, in which we include four ecoregions: the South European Atlantic Shelf, the Saharan Upwelling, the Azores, and a new ecoregion herein named Webbnesia, which comprises the archipelagos of Madeira, Selvagens and the Canary Islands.