Browsing by Author "Santos, R."
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- Combined effects of potassium and wastewater application on the yield and quality of Bermuda grass (Cynodon dactylon) in the Mediterranean regionsPublication . Beltrão, José; Santos, R.; Correia, P. J.The reuse of treated wastewater is considered as an alternative disposable to potable water in the mediterranean agriculture and landscape, namely in golf courses. Bermuda grass (Cynodon dactylon, Peers) is used very often on the fairways, roughs and tees of golf courses of the Mediterranean Basin due to its tolerance to drought, salinity, high temperatures and damages. The objective of this work is to study the response of this cultivar to the combined effects of municipal wastewater and two levels of potassium fertilization, during Spring and Summer. The experimental design known as sprinkle point source was used to simulate the various levels of wastewater application, expressed by the crop coefficient kc. This procedure is characterized by the assumption that a point creates a linear irrigation gradient from the water point source, producing a gradual change in water application, and a high degree of irrigation uniformity must be obtained in parallel isohyets. Chemical analysis of wastewater irrigation water was monitored through all the experimental period (from April to September). Climatic data was also recorded. Yield (aboveground biomass) and the good visual appearance (GVA) of the lawn were assessed in two sampling dates, May and July. Municipal wastewater can be used to irrigate Bermuda grass, without an apparent decrease on grass quality. As concluding remarks, it may be seen that the irrigation water amount is the most pronounced limiting production factor of bermuda grass (Cynodon dactilon, Peers), when compared with potassium fertilization, but it is possible that there is a positive interaction between water and irrigation. This response is modulated by evaporative air conditions since lower yields were obtained in summer. On the other hand, if the potassium fertilization is increased, two situations may occur: 1) with high amounts of water application, leaching problems may occur, mainly on sandy soils, and production may decrease; 2) if potassium fertilization increases, and irrigation water decreases, yield decreases due to the increase of salinity (potassium fertilizers are salts), mainly on salt affected soils.
- Long-term effects of elevated CO2 on the population dynamics of the seagrass Cymodocea nodosa: Evidence from volcanic seepsPublication . Mishra, A. K.; Cabaço, S.; de los Santos, Carmen B.; Apostolaki, E.T.; Vizzini, S.; Santos, R.Population reconstruction techniques was used to assess for the first time the population dynamics of a seagrass, Cymodocea nodosa, exposed to long-term elevated CO2 near three volcanic seeps and compared them with reference sites away from the seeps. Under high CO2, the density of shoots and of individuals (apical shoots), and the vertical and horizontal elongation and production rates, were higher than at the reference sites. Nitrogen limitation effects on rhizome elongation and production rates and on biomass were more evident than CO2 as these were highest at the location where the limitation of nitrogen was highest. At the seep where the availability of CO2 was highest and nitrogen lowest, density of shoots and individuals were highest, probably due to CO2 effects on shoot differentiation and induced reproductive output, respectively. At the three seeps, there was higher short- and long-term shoot recruitment than at the reference sites, and growth rates was around zero, indicating that elevated CO2 increases the turnover of C. nodosa shoots.
- Mortality predictors in patients with takotsubo cardiomyopathyPublication . Bebiana Faria, B.; Marmelo, B.; Azevedo, Pedro; Ruivo, C.; Santos, R.; Gomes, A.; Vieira, M.; Teles, L.; Marreiros, Ana; Almeida, A.; Calvo, L.; Portugues, J.Takotsubo cardiomyopathy (TC) is characterized by transient left ventricular dysfunction in the absence of artery coronary disease. The prognosis is generally favorable but there are cases of death. TC is a rare disease with a low number of events and because of that, there are few studies that describe mortality predictors.
- Tank and field experiments of short-range acoustic propagation through a seagrass canopyPublication . Felisberto, Paulo; Silva, J. P.; Jesus, Sergio; A.J. Silva; Silva, A.T.; Silva, J.; Santos, R.; Ferreira, H.; Pousao, P.Aiming at monitoring the bubbles released during seagrass photosynthesis in different conditions, three experiments were made: two in an outdoor tank and one in the field. The outdoor tank experiments were conducted in winter and summer conditions with Cymodocea nodosa plants transplanted from a nearby meadow. The field experiment took place in September 2018 on a Posidonia oceanica meadow, where bubbles formation due to plants photosynthesis has been reported. In all the experiments continuous wave pulses in the band 1020 kHz were used to estimate the diel change of effective sound speed and the attenuation over the plants. Additionally, high frequency backscatter images at 0.5, 1, 2 and 4 Mhz were obtained to figure out bubbles signature. The results suggest that even in winter, the tank conditions, without water movement, allows for the formation of a small amount bubbles of small radii. In summer tank conditions, the bubbles formation due to photosynthesis of seagrasses significantly increases, but also algae may contribute for the bubbles formation in the environment. The field experiment was carried out after the peak of a bad weather event. There was no evidence of bubbles formation, what can be related to water movement and leaves stirring, that prevents bubbles formation.
- Women vs. men in takotsubo cardiomyopathyPublication . Margarida Oliveira, M.; Bento, Dina; Santos, R.; Vieira, M. J.; Antunes, H.; Reis, L.; Ruivo, C.; Faria, R.; Marreiros, Ana; Almeida, A. R.Takotsubo cardiomyopathy (TCM) is a cardiac syndrome characterized by transient left ventricular dysfunction in the absence of coronary artery disease. It usually affects postmenopausal women but it can also affect men. Differences between genders regarding TCM are still not clearly defned.