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- Obesity and quality of life in adolescentsPublication . Veiga, Nélio; Amaral, Odete; Pereira, Carlos; Ferreira, Sonya; Tavares, Isabel; Chaves, CláudiaBackground: Obesity may interfere with social, psychological and physical activities. The aim of this study was to analyse the association between obesity and health related quality of life (HRQOL) in adolescents. Methods: In a cross-sectional study, we evaluated 7563 students (54.4% females) aged 12-18 years (14.8±1.8) from Viseu, Portugal. Obesity was evaluated by the body mass index (BMI) calculated by ratio of self-reported weight and square of the height (Kg/m2), according to the Cole et al tables, and classified into three groups: “normal weight” (< 25.0), “overweight” (25.0 to 29.9), and “obese” (> or = 30.0). The HRQOL was assessed by SF36 (ranging from 0 to 100) which includes eight dimensions. Proportions were compared by chi-square test and continuous variables by the Kruskal-Wallis test. Results: The total scores of SF36 are significantly lower in overweight and obese adolescents (80.3±13.5 vs. 79.6±13.8 vs. 75.0±14.3, p<0.01, in the male sex and 74.1±13.5 vs. 73.3±14.2 vs. 69.3±16.0, p<0.01, in the female sex). For all dimensions that compose the scale we can verify lower scores among overweight and obese adolescents. The overweight adolescents referred more feelings of marginality relatively to their colleagues/friends (19.6% vs. 13.7%, p<0.01 in the male sex and 24.6% vs. 16.1%, p<0.01 in the female sex) and more feelings of inferiority relatively to their colleagues/friends (38.8% vs. 11.1%, p<0.01 in the male sex and 29.5% vs. 20.8%, p<0.01 in the female sex). Conclusions: Overweight and obesity were associated with impaired HRQOL, with deterioration of physical and emotional well-being. The impairment of HRQOL found in obese adolescents can be associated with restrictions, even though subtle, in daily life.
- Domínios de Atracção e Velocidades de ConvergênciaPublication . Malva, MadalenaGomes e Pestana (Nonstandard domains of attraction and rates of convergence. New perspectives in theoretical and applied statistics, Wiley Ser. Prob. Math. Statistics, 1987) mostraram que o comportamento pré-assintótico, em valores extremos ocorre em grande variedade de situações e encontraram uma explicação: o domínio de atracção de uma lei estável pode ser particionado num ''domínio de atracção standard`` - em que as constantes de atracção são da forma A n^(1/alpha), onde alpha, é o índice de atracção da estável -, e num domínio de atracção não-standard, em que as constantes de atracção são necessariamente da forma L(n)n^(1/alpha) com L(n), de variação lenta, convergindo para 0, ou infinito. Neste trabalho exploramos a questão da qualidade da aproximação nas caudas no domínio de atracção não standard de uma estável simétrica, impondo um controle extra na sua variação, com um parâmetro de segunda ordem.
- Sistemas de Recepção de Imagens de Satélite: Implementação e AplicaçõesPublication . Carvalheiro, Luis Carlos de OliveiraA presente dissertação pretende focalizar-se sobre algumas aplicações da detecção remota por satélite. Assim, será exposto neste trabalho o resultado do desenvolvimento de sistemas de recepção de imagens obtidas por satélites de órbita polar e geostacionária, assim como um conjunto de três aplicações implementadas: a detecção de focos de incêndio em Portugal com dados do MSG-1, o desenvolvimento de um conjunto de actividades de exploração da Detecção Remota no contexto do 1º Ciclo do Ensino Básico e a validação dos resultados de previsão do modelo de mesoescala MM5 com imagens de satélite. A análise destas imagens desempenha um papel crucial, por exemplo nos estudos sobre tempo e clima. É por essa razão que tanto os Estados Unidos como outros países têm vindo a desenvolver um esforço contínuo para que possam ser lançados novos satélites que permitam uma constante aquisição de conhecimentos sobre os fenómenos meteorológicos. Deste modo, a implementação de sistemas de recepção que possibilitem transformar as medidas disponibilizadas por instrumentos a bordo de satélites em informação constitui um empreendimento de extrema utilidade para as mais diversas áreas do saber (como as Geociências ou a Meteorologia), revestindo-se de inúmeras aplicações de interesse para a Sociedade, nomeadamente nos sectores agrícola, energético, dos transportes e da conservação do meio ambiente.
- Effect of time and rate of cattle-slurry application on nitrate concentration of drainage water in a double-cropping forage systemPublication . Trindade, H.; Pereira, J.; Coutinho, J.; Moreira N, N.In the NW region of Portugal a very intensive dairy farming system has been developed based on two silage crops per year (maize plus a winter crop), which has important risks of nitrate leaching losses during the winter season. These soils receive N inputs as high as 600-730 kg N ha -1 yr -1 resulting from two applications of dairy-cattle slurry just before sowing each crop, and 220-300 kg N ha -1 yr -1 from mineral fertilizers (Trindade et al., 1997). The objectives of our study were to evaluate the effect of cattle-slurry rate and time of application on nitrate-N concentration of drainage water during the winter crop (Lolium multiflorum Lam.) growth period.
- Nitrogen mineralization in soils receiving different rates of cattle-slurry and cropped with forage maizePublication . Pereira, J.; Trindade, H.; Coutinho, J.; Moreira, N.The quantification and the time-course of organic nitrogen release from slurry applied at sowing of maize grown for silage is of major importance to increase the efficient use of slurry-N and to reduce environmental impacts. The objective of this work was to quantify the net N mineralization measured in the 0-30 cm soil layer during the forage maize growth period, when cattle slurry was applied at sowing to supply 340 (T1), 190 (T2) and 0 (T3) kg total N ha -1 . The experiment was carried out during 1999 in the NW region of Portugal. Net mineralization rates were significantly different and reached high values, being a relevant source of N for the plants. During the forage maize crop net mineralization represented 401, 281 and 174 Kg N ha -1 respectively on treatments T1, T2 and T3, values that correspond to average net N mineralization rates of 1.3, 0.9 and 0.6 mg N kg -1 soil day -1 . The forage maize dry matter yields on these treatments reached 22, 19 and 13 t ha -1 , respectively for T1, T2 and T3.
- Shrinkage characteristics and porosity of pears during drying.Publication . Guiné, Raquel; Ramos, António; Figueiredo, MargaridaThe high moisture content of pears (about 80 %) results in a high degree of shrinkage when drying takes place which strongly affects the fruit structure and quality. The aim of the present work was to study the shrinkage characteristics of pears during air drying, by evaluating their dimensions and volume along the drying process and by predicting particle and bulk densities as well as porosity as a function of material moisture content. The latter properties were estimated using a mathematical model available from literature whose parameters were either directly measured or determined by fitting some of the equations of the proposed model to the experimental data. The results predicted were subsequently validated by independent measurements.
- From periodic to chaotic oscillations in composite laminated platesPublication . Ribeiro, P.; P. Duarte, RuiThe geometrically non-linear, linear elastic, oscillations of composite laminated plates are studied in the time domain by direct numeric integration of the equations of motion. A p-version finite element, where first-order shear deformation is followed and that was recently proposed for moderately thick plates, is employed to define the mathematical model. By applying transverse harmonic forces, the variation of the oscillations with the angle of the fibres is investigated. With this kind of excitation, only periodic motions with a period equal to the one of the excitation are found. However, introducing in-plane forces, m-periodic or quasi-periodic oscillations, as well as chaotic oscillations are computed. The existence of chaos is confirmed by calculating the largest Lyapunov exponent.
- Chemical and microbiological characterization of Portuguese varieties of pears.Publication . Barroca, Maria João; Guiné, Raquel; Pinto, António; Gonçalves, Fernando; Ferreira, DulcineiaThe sun-dried pears of the local variety known as S. Bartolomeu, found in the centre of Portugal, are relatively small fruits, characterized by an intense reddish brown colour, that loose their pronounced astringency with drying. However, and since their production has been declining over the past decades, there has been an increasing interest in drying also for other varieties of pears, also with small dimensions, as an alternative to produce the dried pears. The aim of this work is the evaluation of the nutritional properties of fresh and dried pears of the local varieties known as Amêndoa, Amorim, Carapinheira Branca and S. Bartolomeu, all original from of the centre of Portugal. The results enable us to conclude that the fresh pear pulp of all varieties has a low content of protein and a high level of total sugars, as is generally true for fruit. However, their values of dietary fiber ranged between 12 and 15% (dry mass) constituting these pears a potential source of dietary fiber. In addition, it is also possible to conclude that, apparently, the solar stove-drying process has no effect on the nutritional characteristics of the pears, except on total sugars and acidity. The range of water activity values and microbial charge of the different pears also allow inferring that the dried fruits obtained from the four varieties studied are potentially safe from a microbiological point of view. The resemblance in the characteristics of the fruits, together with the similarity of behaviour towards drying, suggests that the fruits of the varieties Carapinheira Branca, Amêndoa and Amorim can be viewed as a good alternative to those of the variety S. Bartolomeu for the production of dried pears.
- Moisture diffusivity in pears: Experimental determination and derivation of a mathematical prediction model.Publication . Guiné, RaquelIn the present work the dependence of moisture diffusivity on pear composition (in particular, water and sugar concentrations) was examined from the drying rate data measured experimentally. A model for predicting diffusivity that accounts for the effects of three variables (temperature, moisture content and sugar concentration) was then developed, and compared with the model presented by Zogzas and Maroulis (Drying Technology 1996;14:1543), which accounts only for the influence of temperature and moisture concentration. It was observed that the value for the activation energy predicted by the model that includes the influence of the sugar concentration is higher, showing that the amount of sugar present influences the diffusion of moisture through the pear. From the results obtained it was possible to conclude that at constant temperature the diffusivity is increased for higher water contents and lower sugar concentrations. Furthermore, it was possible to observe that higher temperatures have a much more pronounced influence on the diffusivity, compared with lower temperatures.