GRASS UTILIZATION IN GROWING FINISHING BÍSARO PIGS (85-107 KG). PERFORMANCE AND CARCASS COMPOSITION

The use of different quantities of vegetables, forages or fresh grass as fodder for growing-finishing pigs is an important factor of the northern Portugal traditional system. The increasing development of swine production in outdoor systems, extensive and organic production, turns to upcoming natural diets, in which grass performs a significant part. With regard to this, some investigation has been made concerning the use of fibre-rich feed ingredients in pig nutrition. Metabolic effects of its ingestion are analysed concerning different sights (economical, social, environmental and physiological ones). The aim of this work was to study the effects of grass utilization in the diets on performances of finishing Bísaro pigs. A total of 22 pigs (16 castrated males and 6 females) was housed outdoor and fed ad libitum (37 – 85 kg live weight) with a growing diet and then transferred to an indoor system (with free access to an outdoor area) for 49 days, according to 3 different treatments: 100% concentrate (C), 75% concentrate + ad libitum grass (CE75), 50% concentrate + ad libitum grass (CE50). The grass was supplied and its intake registered on a daily basis. Every 14 days, the pigs were weighted and their back fat (P2 in vivo) measured. After slaughter (average weight of 107 kg LW), yield and ½ left carcass characteristics were controlled. During the outdoor growing phase, the ADG was 513 g/day. During the indoor finishing phase, the increase grass intake was proportional to the reduction of concentrate in the diet. The ADG (g) and the fat deposition (P2 cm) were significantly different (P<0,05) in the 3 treatments (ADG: C=641, CE75=467, CE50=356 and: C=11,4, CE75=+9,5, CE50=+6,2). The empty body weight (kg) was also proportional to the intake of concentrate (C=116,2; CE75=107,7; CE50=102,2). Comparatively to the weight of the body parts, pigs that had higher intake of grass and lower of concentrate showed a higher % of shoulder (P<0,05; C=20,4, CE75=21,7, CE50=22,2) and the pH45min of CE carcasses was significantly higher (P<0,05). As a conclusion, concentrate substitution for grass showed a slower growing rate, thinner carcasses and a high technological quality. Neverthelles variability (CV %) of the productive parameters at the end of this study were higher in the treatments that included grass: live weight (C= 10,5%; C75=10,7%; C50=14,3%), finishing ADG (C=24%; C75=37%, C50=42%), and final fat (C=37%; C75=32%, C50=52%). These values suggest that the utilization of fibrous feeds in growing-finishing swine may be one of the possible explanations of the more heterogeneous products and carcasses found in the traditional or extensive systems, common users of fibrous feeds in the carcass finishing phase

Curves and surfaces making a constant angle with a parallel transported direction in Riemannian spaces

In the last two decades, much effort has been dedicated to studying curves and surfaces according to their angle with a given direction. How- ever, most findings were obtained using a case-by-case approach, and it is often unclear what is a consequence of specificities of the ambient manifold and what could be generic. In this work, we propose a theo- retical framework to unify parts of these findings. We study curves and surfaces by prescribing the angle they make with a parallel transported vector field. We show that the characterization of Euclidean helices in terms of their curvature and torsion is also valid in any Riemannian manifold. Among other properties, we prove that surfaces making a con- stant angle with a parallel transported direction are extrinsically flat ruled surfaces. We also investigate the relation between their geodesics and the so-called slant helices. We prove that surfaces of constant angle are the rectifying surface of a slant helix, i.e., the ruled surface with rulings given by the Darboux field of the directrix. We characterize recti- fying surfaces of constant angle or, equivalently, when their geodesics are slant helices. As a corollary, we show that if every geodesic of a surface of constant angle is a slant helix, the ambient manifold is flat. Finally, we characterize surfaces in the product of a Riemannian surface with the real line making a constant angle with the vertical real direction

Apresentação gráfica do conceito de função e sua implicação nas atitudes e na aprendizagem dos alunos

Actualmente abrem-se novas perspectivas de apresentação de diversos conteúdos que, aliadas à rapidez e precisão de execução dos computadores, permitem uma abordagem gráfica, anteriormente difícil de conseguir, especialmente em alguns tópicos curriculares da disciplina de matemática, envolvendo alguma abstracção e raciocínio lógico por parte dos alunos. A esta abordagem gráfica, o computador permite acrescentar funcionalidades de interacção e interactividade. Deste modo, recorrendo ao computador como auxiliar educativo, os alunos podem simular e experimentar novas situações como lhes aprouver e verificar os respectivos resultados. No caso concreto que apresentamos, utilizámos a capacidade gráfica e de simulação dos computadores para facilitar a aprendizagem do conceito de função, reforçando a correspondência entre linguagem algébrica e gráfica

Ensino-aprendizagem com recurso à tecnologia informática : mudanças observadas nos alunos

Citação bibliográfica: Machado, José; SILVA, Bento & Almeida, Leandro (2007). Ensino-aprendizagem com recurso à tecnologia informática: mudanças observadas nos alunos. In A. Barca, M. Peralbo, A. Porto, B. Duarte da Silva & Almeida, L.(Eds.). Actas do IX Congresso Internacional Galego-Português de Psicopedagoxía. Corunha: Universidade da Corunha, pp. 652-663. (ISSN 1138-1663)É cada vez mais comum utilizar-se a modalidade educativa designada por e-learning, entendida como o recurso às novas tecnologias multimédia e à internet para melhorar a qualidade da aprendizagem, a qual abrange um vasto conjunto de aplicações e processos como a aprendizagem mediada por computador, a aprendizagem baseada na Web, salas de aula e comunidades virtuais online. Apesar destes avanços tecnológicos e pedagógicos, continuam a existir disciplinas com níveis de insucesso elevados. A matemática é ilustrativa, continuando a ser considerada uma disciplina de difícil aprendizagem por grande parte dos alunos. Com o presente estudo, foi nosso objectivo recorrer à mediação por computador para avaliar o impacto na aprendizagem de funções quando os conteúdos matemáticos são apresentados utilizando a parte gráfica, em complemento da convencional abordagem algébrica. Os resultados finais sugerem que os alunos do 12º ano que participaram nesta experiência demonstram uma melhor compreensão dos conceitos matemáticos envolvidos e passaram a estabelecer, com mais facilidade, as relações entre as escritas algébrica e gráfica. Para além disso, nesta comunicação descrevemos algumas outras mudanças ocorridas nos alunos com a implementação desta experiência educativa, nomeadamente em termos de frequências, locais, modos de utilização e atitudes dos alunos em relação à utilização dos computadores

Software educativo como facilitador da aprendizagem : estudo tomando a função exponencial e a derivada

Citação bibliográfica: Machado, José, SILVA, Bento & Almeida, Leandro (2007). Software educativo como facilitador da aprendizagem: estudo tomando a função exponencial e a derivada. In Paulo Dias, Cândido Varela de Freitas et. al. (orgs.). Actas da V Conferência Internacional de Tecnologias de Informação e Comunicação na Educação, Challenges 2007. Braga: Centro de Competência da Universidade do Minho, Braga, p.326-336. (ISBN 978-972-8746-52-0)A digitalização da informação permite com relativa facilidade a sua apresentação recorrendo ao texto, ao som, à imagem e à combinação de todos estes elementos. Decorrente dela o aspecto visual e gráfico, tal corno noutras áreas, pode e deve ser explorado no processo de ensino-aprendizagem. Visou-se neste estudo aferir qual o impacto que o software educativo escolhido teve no processo de ensino-aprendizagem do conceito de função exponencial e derivada. Estes conceitos foram leccionados, recorrendo às potencialidades gráficas do computador, a alunos do décimo segundo ano, que frequentaram as aulas da disciplina de Matemática. Esse impacto seria traduzido numa melhor compreensão dos conceitos matemáticos e da relação entre a escrita algébrica e a gráfica, pelos alunos envolvidos na experiência educativa. Na investigação sobre a diferenciação de rendimento dos alunos, tivemos ainda em consideração a variável sexo, dada a possível relevância desta variável. Por outro lado pretendemos aferir quais as frequências e modos de utilização que os alunos faziam dos computadores e se o facto de terem contactado com urna metodologia de ensino que envolvia o recurso a computadores teria repercussões nesses valores e usos. O estudo permitiu constatar que os alunos envolvidos na experiência educativa, tiveram um aproveitamento diferenciado do dos seus colegas, a quem os mesmos conceitos foram leccionados de forma convencional, sem recurso a computadores.Digital information enables its presentation in a relatively simple way by means of a text, a sound, an image and the combination of all these elements. Due to its visual and graphic aspect, it can and should be explored in the teaching-learning process, just as in other areas. It was sought in this study to check which impact the chosen educational software had in the process of teaching-learning applied to the concept of exponential function and derived function. These concepts were taught, to students attending the subject of Mathematics, 12th form, and were supported by the graphic potentialities of computers. For the students involved in the educational experience that impact would be translated in a better understanding of the mathematical concepts and of the relationship between the algebraic writing and the graphic visualisation. The investigation about the differentiation of the students' success had also into consideration the variable gender, because of the possible relevance of this variable. On the other hand we intended to check how often and what for do students use the computers and if by having experienced this teaching methodology supported by the use of computers, there were sorne repercussions in those values and uses. This study allowed us to verify, that the students involved in the educational experience had a differentiated success of other students to whom, the same concepts were taught in a conventional way, without computers

Spreading gossip in social networks

We study a simple model of information propagation in social networks, where two quantities are introduced: the spread factor, which measures the average maximal fraction of neighbors of a given node that interchange information among each other, and the spreading time needed for the information to reach such fraction of nodes. When the information refers to a particular node at which both quantities are measured, the model can be taken as a model for gossip propagation. In this context, we apply the model to real empirical networks of social acquaintances and compare the underlying spreading dynamics with different types of scale-free and small-world networks. We find that the number of friendship connections strongly influences the probability of being gossiped. Finally, we discuss how the spread factor is able to be applied to other situations.Comment: 10 pages, 16 figures, Revtex; Virt.J. of Biol. Phys., Oct.1 200