The aim of this paper is to study the aerodynamics of discus throw. A comparison of numerical and experimental performance of discus throw with and without rotation was carried out using the analysis of lift and drag coefficients. Initial velocity corresponding to variation angle of around 35.5° was simulated. Boundary condition, on the top and bottom boundary edges of computational domain, was imposed in order to eliminate external influences on the discus; a wind resistance was calculated for the velocity values of 25 and 27 m/s. The results indicate that the flight distance (D) was strongly affected by the drag coefficient, the initial velocity, the release angle and the direction of wind velocity. It was observed that these variables change as a function of discus rotation. In this study, results indicate a good agreement of D between experimental values and numerical results.

This work presents a proposal to introduce the study of vectors in High School, in order to oer a broader and clearer possibility for some mathematical demonstrations, applications and their use in other elds, such as Physics, for example. Make some demonstrations of trigonometry, of analytical and at geometries more playful and understandable, is the objective of this approach, besides, of course, oer conditions to work with vectors already in High School, oering pre requisites for future studies in the areas of Exact Sciences.

In this paper, we present a formalism designed to model tidal interaction with a viscoelastic body made of Maxwell material. Our approach remains regular for any spin rate and orientation, and for any orbital configuration including high eccentricities and close encounters. The method is to integrate simultaneously the rotation and the position of the planet as well as its deformation. We provide the equations of motion both in the body frame and in the inertial frame. With this study, we generalize preexisting models to the spatial case and to arbitrary multipole orders using a formalism taken from quantum theory. We also provide the vectorial expression of the secular tidal torque expanded in Fourier series. Applying this model to close-in exoplanets, we observe that if the relaxation time is longer than the revolution period, the phase space of the system is characterized by the presence of several spin-orbit resonances, even in the circular case. As the system evolves, the planet spin can visit different spin-orbit configurations. The obliquity is decreasing along most of these resonances, but we observe a case where the planet tilt is instead growing. These conclusions derived from the secular torque are successfully tested with numerical integrations of the instantaneous equations of motion on HD 80606 b. Our formalism is also well adapted to close-in super-Earths in multiplanet systems which are known to have non-zero mutual inclinations.

We investigate the secular dynamics of three-body circumbinary systems under the effect of tides. We use the octupolar non-restricted approximation for the orbital interactions, general relativity corrections, the quadrupolar approximation for the spins, and the viscous linear model for tides. We derive the averaged equations of motion in a simplified vectorial formalism, which is suitable to model the long-term evolution of a wide variety of circumbinary systems in very eccentric and inclined orbits. In particular, this vectorial approach can be used to derive constraints for tidal migration, capture in Cassini states, and stellar spin–orbit misalignment. We show that circumbinary planets with initial arbitrary orbital inclination can become coplanar through a secular resonance between the precession of the orbit and the precession of the spin of one of the stars. We also show that circumbinary systems for which the pericenter of the inner orbit is initially in libration present chaotic motion for the spins and for the eccentricity of the outer orbit. Because our model is valid for the non-restricted problem, it can also be applied to any three-body hierarchical system such as star–planet–satellite systems and triple stellar systems.

A materialidade, enquanto critério fundamental do julgamento profissional, orienta as decisões do auditor em todas as fases de uma auditoria. Contudo, apesar de ser reconhecida a sua importância, a ausência de evidências sobre a sua aplicação prática tem dificultado a compreensão dos fatores que a influenciam. Com a atual possibilidade de aceder a este tipo de evidências no contexto empresarial do Reino Unido, este estudo visa identificar possíveis padrões de atuação dos auditores, procurando inferir se o sexo e a rotação de auditor ou de empresa de auditoria influenciam significativamente o julgamento acerca da materialidade. Para tal, foi utilizada uma amostra final de 92 empresas integrantes do FTSE 100, ao longo de um período de 8 anos. A análise desenvolvida baseou-se em técnicas estatísticas convencionais, complementada por uma análise econométrica de forma a testar os referidos fatores. Os resultados demonstram que a decisão acerca do nível de materialidade global não advém de uma simples “rule of thumb”. Com efeito, verifica-se que são utilizados diversos benchmarks para a sua definição, que se baseiam em um ou mais racionais que justificam a escolha. Também a materialidade de execução tem por base um ou mais racionais, nomeadamente, a avaliação do risco e das características do sistema de controlo interno, o histórico de distorções, a volatilidade, o início do mandato e a consistência. Não foram encontradas evidências de que tanto o sexo como a rotação de auditor ou de empresa de auditoria influenciem significativamente a materialidade global. No entanto, foi possível inferir que quando existe rotação da empresa de auditoria, se verifica uma diminuição do nível de materialidade de execução. Por fim, observou-se uma maior sensibilidade dos homens a variações na Rendibilidade Operacional do Ativo, refletida em ajustamentos mais acentuados ao nível da materialidade global.

Small angle neutron scattering techniques were used to quantify the size and shape of the chain conformation in electrospun fibres of atactic polystyrene prepared from solutions in methyl ethyl ketone. Aligned arrays of fibres were collected onto a rotating collector with tangential velocity varying between 0 ms-1 and ∼15 ms-1. The measured radii of gyration of the polystyrene chains were found to be slightly higher than that expected for samples prepared from solutions in the concentrated regime. The ratio of the radius of gyration parallel and perpendicular to the chain axis was found to be ∼1.05 in contrast to the substantial macroscopic shape transformation intrinsic to electrospinning. When the tangential velocity of the rotating collector was greater than the flight velocity of the fibres (ca. 4 ms -1), a further extension of the polymer chains was observed with a ratio of the radii of gyration increasing to 1.20 at the highest collector speeds. It is proposed that the heterogeneous processes involved, particularly solvent evaporation and the formation of a polymer skin during electrospinning play a significant role in determining the level of molecular anisotropy in the fibres. © 2011 The Royal Society of Chemistry.

Objectives: The purpose of this study was to compare shoulder external rotation range of motion (ROM) during the hand-behind-neck (HBN) test and a standard shoulder external rotation test and to describe the 3-dimensional scapular motion during the HBN test. Methods: An electromagnetic tracking device was used to assess the dominant shoulder of 14 healthy participants while performing active full ROM in a standard shoulder external rotation test in an elevated position (EREP) and in the HBN test. The humeral and scapular 3-dimensional positions at the end of EREP and HBN were compared using a paired-sample t test. A correlation analysis was performed between humeral and scapular angles to assess the contribution of scapular motion to the full shoulder ROM during the HBN test. Results: No significant differences were found between the HBN test and the EREP at the end-range of the glenohumeral external rotation (HBN: 15.6° ± 6.3° vs EREP: 23.4° ± 4.7°; P = .08) and on scapular internal-external rotation (HBN test: 21.2° ± 6.3° vs EREP: 15.6° ± 1.8°; P = .23). Significant differences were found in scapular upward rotation (HBN: 21.2° ± 6.3° vs EREP: 15.6° ± 1.8°; P b .01) and scapular spinal tilt (HBN: − 0.4° ± 2.3° vs EREP: 8.1° ± 2.1°; P b .01). There was a positive correlation between the humeral angles and scapular internal and posterior spinal tilt angles with the HBN test. Conclusions: The results of the present study showed that, in young asymptomatic participants with no known shoulder pathology, the end-range of shoulder rotation was similar in the HBN test and in a standard shoulder rotation test. During the HBN test, the scapula assumed a more internal and anterior spinal tilted position at the end-range of active shoulder external rotation. These results suggest that the HBN test may be used to assess the end-range of glenohumeral external rotation.

Este estudo investiga a problemática das saídas voluntárias dos militares dos Quadros Permanentes (QP) da Força Aérea Portuguesa, desenvolvendo um modelo preditivo para identificar militares com maior probabilidade de pedir abate. Utilizando uma abordagem quantitativa, recorreu-se a métodos de machine learning, nomeadamente Regressão Logística, Naive Bayes, Análise Discriminante Linear, Análise Discriminante Quadrática e Árvores de Decisão. A base de dados foi composta por 2176 militares, divididos entre aqueles que solicitaram abate e os que permaneceram em serviço. A análise identificou variáveis sociodemográficas e estruturais significativas, como a idade, a especialidade, o número de louvores e a nota da ficha de avaliação. O modelo de Regressão Logística (RL) apresentou a melhor performance, permitindo calcular um índice de probabilidade de saída, com utilidade prática para a gestão de recursos humanos. Apesar de limitações, como a baixa sensibilidade e o uso de um conjunto limitado de variáveis, o estudo oferece contributos importantes para a retenção de talento na Força Aérea e sugere a inclusão de mais variáveis e abordagens avançadas em investigações futuras.

Proteins in the arrestin family exhibit a conserved structural fold that nevertheless allows for significant differences in their selectivity for G-protein coupled receptors (GPCRs) and their phosphorylation states. To reveal the mechanism of activation that prepares arrestin for selective interaction with GPCRs, and to understand the basis for these differences, we used unbiased molecular dynamics simulations to compare the structural and dynamic properties of wild type Arr1 (Arr1-WT), Arr3 (Arr3-WT), and a constitutively active Arr1 mutant, Arr1-R175E, characterized by a perturbation of the phosphate recognition region called "polar core". We find that in our simulations the mutant evolves toward a conformation that resembles the known preactivated structures of an Arr1 splice-variant, and the structurally similar phosphopeptide-bound Arr2-WT, while this does not happen for Arr1-WT. Hence, we propose an activation allosteric mechanism connecting the perturbation of the polar core to a global conformational change, including the relative reorientation of N- and C-domains, and the emergence of electrostatic properties of putative binding surfaces. The underlying local structural changes are interpreted as markers of the evolution of an arrestin structure toward an active-like conformation. Similar activation related changes occur in Arr3-WT in the absence of any perturbation of the polar core, suggesting that this system could spontaneously visit preactivated states in solution. This hypothesis is proposed to explain the lower selectivity of Arr3 toward nonphosphorylated receptors. Moreover, by elucidating the allosteric mechanism underlying activation, we identify functionally critical regions on arrestin structure that can be targeted with drugs or chemical tools for functional modulation.

Este relatório surge no âmbito da Prática de Ensino Supervisionada (PES) inserida no curso de Mestrado em Ensino do 1.o CEB e de Matemática e Ciências Naturais no 2.o CEB, da Escola Superior de Educação de Viana do Castelo. Encontra-se dividido em três partes: a primeira evidenciando os contextos educativos, onde foram realizadas as intervenções didáticas, descrevendo acontecimentos importantes ao longo deste percurso; na segunda parte, apresenta-se o estudo realizado numa turma do 2.o CEB na área disciplinar de Matemática; e na terceira parte, é realizada uma reflexão global sobre as experiências vividas durante esta prática. O estudo realizou-se no âmbito da Matemática tendo como foco principal o ensino-aprendizagem das isometrias no plano. Ao longo desta investigação procurou-se compreender o desempenho dos alunos em tarefas no âmbito das isometrias com recurso a materiais manipuláveis e, para orientar este estudo, formularam-se duas questões orientadoras: (1) Como se carateriza o desempenho dos alunos na resolução de tarefas no âmbito das isometrias com materiais manipuláveis, identificando os seus principais conhecimentos e dificuldades? (2) Como se carateriza a reação dos alunos à utilização de materiais manipuláveis no estudo das isometrias? De modo a responder as estas questões, optou-se por utilizar uma metodologia de investigação qualitativa e interpretativa, seguindo um design de estudo de caso, onde se acompanharam dois grupos-caso compostos por três elementos cada. A recolha de dados foi realizada através de observações, questionários, entrevista, registo áudio e fotográfico e documentos escritos, em particular a produções realizadas pelos alunos nas tarefas propostas. A análise destes dados permitiu concluir que os alunos apresentaram um desempenho positivo em relação à resolução de tarefas propostas sobre isometrias utilizando materiais manipuláveis. De salientar que as maiores dificuldades sentidas no âmbito das isometrias incidem na rotação e na simetria de rotação. Por outro lado, a maior preferência aponta para a reflexão axial. Em relação aos materiais manipuláveis houve uma reação bastante positiva à sua utilização, sendo que a maioria dos alunos deu preferência ao Mira, mostrando maiores dificuldades na utilização do transferidor de 360°.