Browsing by Author "Gouveia, Duarte"
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- ACE: Um Agente de Compras na InternetPublication . Neto, Ana Beatriz; Gouveia, Duarte; Silva, Mário J.Electronic commerce through the Internet is a growing business, but there are still some problems to overcome so that every user can become a buyer. Safe transactions are the most discussed problem, but there are other problems that make shopping on the Internet difficult. When we built ACE (which stands for Agente de Compras Especializado) we aimed at solving one of those problems: finding the product or service that best suits your needs. We designed a scalable model for that purpose (since this software could be used to connect every buyer and every seller on the Internet) and we built a prototype that shows how this model works. We describe our proposed model in detail, based on the software agents paradigm, and the methodology we used to develop it. We conclude with a comparison between ACE and a similar commercial product
- Resilient and sensitive key points of the photosynthetic machinery of Coffea spp. to single and superimposed exposure to severe drought and heat stressesPublication . Dubberstein, Danielly; Lidon, Fernando C.; Rodrigues, Ana P.; Semedo, José N.; Marques, Isabel; Rodrigues, Weverton P.; Gouveia, Duarte; Armengaud, Jean; Semedo, Magda; Martins, Sónia; Simões-Costa, Maria C.; Moura, I.; Ribeiro-Barros, Ana I.; Ramalho, José C.This study unveils the single and combined drought and heat impacts on the photosynthetic performance of Coffea arabica cv. Icatu and C. canephora cv. Conilon Clone 153 (CL153). Well-watered (WW) potted plants were gradually submitted to severe water deficit (SWD) along 20 days under adequate temperature (25/20°C, day/night), and thereafter exposed to a gradual temperature rise up to 42/30°C, followed by a 14-day water and temperature recovery. Single drought affected all gas exchanges (including Amax) and most fluorescence parameters in both genotypes. However, Icatu maintained Fv/Fm and RuBisCO activity, and reinforced electron transport rates, carrier contents, and proton gradient regulation (PGR5) and chloroplast NADH dehydrogenase-like (NDH) complex proteins abundance. This suggested negligible non-stomatal limitations of photosynthesis that were accompanied by a triggering of protective cyclic electron transport (CEF) involving both photosystems (PSs). These findings contrasted with declines in RuBisCO and PSs activities, and cytochromes (b559, f, b563) contents in CL153. Remarkable heat tolerance in potential photosynthetic functioning was detected in WW plants of both genotypes (up to 37/28°C or 39/30°C), likely associated with CEF in Icatu. Yet, at 42/30°C the tolerance limit was exceeded. Reduced Amax and increased Ci values reflected non-stomatal limitations of photosynthesis, agreeing with impairments in energy capture (F0 rise), PSII photochemical efficiency, and RuBisCO and Ru5PK activities. In contrast to PSs activities and electron carrier contents, enzyme activities were highly heat sensitive. Until 37/28°C, stresses interaction was largely absent, and drought played the major role in constraining photosynthesis functioning. Harsher conditions (SWD, 42/30°C) exacerbated impairments to PSs, enzymes, and electron carriers, but uncontrolled energy dissipation was mitigated by photoprotective mechanisms. Most parameters recovered fully between 4 and 14 days after stress relief in both genotypes, although some aftereffects persisted in SWD plants. Icatu was more drought tolerant, with WW and SWD plants usually showing a faster and/or greater recovery than CL153. Heat affected both genotypes mostly at 42/30°C, especially in SWD and Icatu plants. Overall, photochemical components were highly tolerant to heat and to stress interaction in contrast to enzymes that deserve special attention by breeding programs to increase coffee sustainability in climate change scenarios