3 resultados para Quantitative history of science

em Universidad Politécnica de Madrid


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Strictly speaking, space related activities at the Escuela Técnica Superior de Ingenieros Aeronáuticos (ETSIA) begun in 1973, when Prof. Ignacio Da Riva got a contract from the European Space Agency (ESA) to compile a handbook on spacecraft thermal control. By the same time, ESA issued an announcement of opportunities offering to the European scientific community the possibility of perform microgravity relevant experiments on board space platform like the European orbital laboratory Spacelab. Prof. Da Riva proposed one of the few selected experiments dealing with fluid physics under microgravity conditions, later flown on Spacelab-1 mission in 1983. These two events were the starting point where Prof. Da Riva, full professor of Aerodynamics at ETSIA, nucleated a small group of young professors and students located at the Laboratorio de Aerodinámica y Mecánica de Fluidos (LAMF) of ETSIA. Such group was leaded by Prof. Da Riva since its creation till 1991, when Prof. Da Riva died, and it was the seed of the more recently created research institute for aerospace science and technology named "Ignacio Da Riva" (IDR) in his honour. In this communication space related activities performed either at LAMF or IDR during the last three decades are briefly described.

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Two scientific schools have been in coexistence from the beginning of genetics, one of them searching for factors of inheritance and the other one applying biometrical models to study the relationships between relatives. With the development of molecular genetics, the possibilities of detecting genes having a noticeable effect in traits augmented. Some genes with large or medium effects were localized in animals, although the most common result was to detect markers linked to these genes, allowing the possibility of assisting selection programs with markers. When a large amount of simple and inexpensive markers were available, the SNPs, new possibilities were opened since they did not need the presence of genes of large or medium effect controlling a trait, because the whole genome was scanned. Using a large amount of SNPs permits having a prediction of the breeding value at birth accurate enough to be used in some cases, like dairy cattle, to halve its generation interval. In other animal breeding programs, the implementation of genomic selection is less clear and the way in which it can be useful should be carefully studied. The need for large populations for associating phenotypic data and markers, plus the need for repeating the process continuously, complicates its application in some cases. The implementation of the information provided by the SNPs in current genetic programs has led to the development of complex statistical tools, joining the efforts of the two schools, factorial and biometrical, that nowadays work closely related.

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The introduction of cover crops in the intercrop period may provide a broad range of ecosystem services derived from the multiple functions they can perform, such as erosion control, recycling of nutrients or forage source. However, the achievement of these services in a particular agrosystem is not always required at the same time or to the same degree. Thus, species selection and definition of targeted objectives is critical when growing cover crops. The goal of the current work was to describe the traits that determine the suitability of five species (barley, rye, triticale, mustard and vetch) for cover cropping. A field trial was established during two seasons (October to April) in Madrid (central Spain). Ground cover and biomass were monitored at regular intervals during each growing season. A Gompertz model characterized ground cover until the decay observed after frosts, while biomass was fitted to Gompertz, logistic and linear-exponential equations. At the end of the experiment, carbon (C), nitrogen (N), and fibre (neutral detergent, acid and lignin) contents, and the N fixed by the legume were determined. The grasses reached the highest ground cover (83–99%) and biomass (1226–1928 g/m2) at the end of the experiment. With the highest C:N ratio (27–39) and dietary fibre (527–600 mg/g) and the lowest residue quality (~680 mg/g), grasses were suitable for erosion control, catch crop and fodder. The vetch presented the lowest N uptake (2·4 and 0·7 g N/m2) due to N fixation (9·8 and 1·6 g N/m2) and low biomass accumulation. The mustard presented high N uptake in the warm year and could act as a catch crop, but low fodder capability in both years. The thermal time before reaching 30% ground cover was a good indicator of early coverage species. Variable quantification allowed finding variability among the species and provided information for further decisions involving cover crop selection and management.