947 resultados para Frankel, Theodore: The geometry of physics : an introduction
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Includes bibliography
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Predation is a primary driver of tadpole assemblages, and the activity rate is a good predictor of the tadpoles' tolerance for predation risk. The conflicting demands between activity and exposure to predation can generate suboptimal behaviours. Because morphological components, such as body colouration, may affect the activity of tadpoles, we predict that environmental features that enhance or match the tadpole colouration should affect their survival or activity rate in the presence of a predator. We tested this prediction experimentally by assessing the mortality rate of tadpoles of Rhinella schneideri and Eupemphix nattereri and the active time on two artificial background types: one bright-coloured and one black-coloured. We found no difference in tadpole mortality due to the background type. However, R. schneideri tadpoles were more active than E. nattereri tadpoles, and the activity of R. schneideri was reduced less in the presence of the predator than that of E. nattereri. Although the background colouration did not affect the tadpole mortality rate, it was a stimulus that elicited behavioural responses in the tadpoles, leading them to adjust their activity rate to the type of background colour. © 2013 Dipartimento di Biologia, Università degli Studi di Firenze, Italia.
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Los documentos del Seminario fueron publicados por UNESCO en 1961 con el título: La urbanización en América Latina/Urbanization in Latin America
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Includes bibliography
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A atualização dos currículos escolares e, em especial, a inserção de assuntos de física moderna e contemporânea já foram defendidos com justificativas satisfatórias, tanto por professores em atividade escolar como por pesquisadores da área de ensino de física. Entre os assuntos que deveriam ser discutidos encontramos a Física das Partículas Elementares. O ensino deste tópico é justificado pelo fato dele permitir a discussão: a) de uma nova visão de mundo; b) de uma visão mais adequada da ciência; c) da reinterpretação da Física Clássica; d) da dinâmica da Ciência e seu desenvolvimento; e) da contribuição dos diversos cientistas; f) do papel da experimentação; g) do investimento financeiro e cooperativo de diversos países e pesquisadores. No entanto, para que a inserção de assuntos de física moderna e contemporânea ocorra de maneira eficiente é necessária a atualização dos professores que já estão em docência escolar, bem como uma formação adequada daqueles que estão em processo de formação inicial. Neste sentido, desde 2010 a Sociedade Brasileira de Física realiza anualmente a Escola de Física do CERN, na qual participam professores brasileiros de física de escolas públicas do Ensino Médio. Nesta escola são desenvolvidas aulas sobre física de partículas, sessões experimentais e visitas aos laboratórios do CERN. Perante isso, investigamos como os professores participantes da Escola de Física do CERN abordam a física de partículas em suas aulas após participarem dela.
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This paper presents an extension of the Enestrom-Kakeya theorem concerning the roots of a polynomial that arises from the analysis of the stability of Brown (K, L) methods. The generalization relates to relaxing one of the inequalities on the coefficients of the polynomial. Two results concerning the zeros of polynomials will be proved, one of them providing a partial answer to a conjecture by Meneguette (1994)[6]. (C) 2011 Elsevier Inc. All rights reserved.
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To evaluate whether a history of falls is directly related to the quadriceps muscular function and body sway, 26 elderly women were divided on the basis of the presence or absence of a history of falls. Evaluation of muscular power and anteroposterior and mediolateral displacements of center of pressure during consecutive stand and sit 5 times were performed. Fallers exhibited higher mediolateral displacement than nonfallers. No differences were observed for quadriceps power and for sit-to-stand time between groups (P<.05). The fall history was not related to the quadriceps muscular function or to the anteroposterior displacement during sit to stand.
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BACKGROUND: Mechanical pain sensitivity is assessed in every patient with pain, either by palpation or by quantitative pressure algometry. Despite widespread use, no studies have formally addressed the usefulness of this practice for the identification of the source of pain. We tested the hypothesis that assessing mechanical pain sensitivity distinguishes damaged from healthy cervical zygapophysial (facet) joints. METHODS: Thirty-three patients with chronic unilateral neck pain were studied. Pressure pain thresholds (PPTs) were assessed bilaterally at all cervical zygapophysial joints. The diagnosis of zygapophysial joint pain was made by selective nerve blocks. Primary analysis was the comparison of the PPT between symptomatic and contralateral asymptomatic joints. The secondary end points were as follows: differences in PPT between affected and asymptomatic joints of the same side of patients with zygapophysial joint pain; differences in PPT at the painful side between patients with and without zygapophysial joint pain; and sensitivity and specificity of PPT for 2 different cutoffs (difference in PPT between affected and contralateral side by 1 and 30 kPa, meaning that the test was considered positive if the difference in PPT between painful and contralateral side was negative by at least 1 and 30 kPa, respectively). The PPT of patients was also compared with the PPT of 12 pain-free subjects. RESULTS: Zygapophysial joint pain was present in 14 patients. In these cases, the difference in mean PPT between affected and contralateral side (primary analysis) was −6.2 kPa (95% confidence interval: −19.5 to 7.2, P = 0.34). In addition, the secondary analyses yielded no statistically significant differences. For the cutoff of 1 kPa, sensitivity and specificity of PPT were 67% and 16%, respectively, resulting in a positive likelihood ratio of 0.79 and a diagnostic confidence of 38%. When the cutoff of 30 kPa was considered, the sensitivity decreased to only 13%, whereas the specificity increased to 95%, resulting in a positive likelihood ratio of 2.53 and a diagnostic confidence of 67%. The PPT was significantly lower in patients than in pain-free subjects (P < 0.001). CONCLUSIONS: Assessing mechanical pain sensitivity is not diagnostic for cervical zygapophysial joint pain. The finding should stimulate further research into a diagnostic tool that is widely used in the clinical examination of patients with pain.
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This article brings to light a debate on tragic fiction in eighteenth-century France, and more specifically, on whether or not tragedy has the power to transform individuals intellectually and emotionally. Through analysis of abbé Dubos’s Reflexions critiques sur la poésie et sur la peinture and Jean-Jacques Rousseau’s Lettre à d’Alembert sur les spectacles, I contend that Dubos’s overwhelmingly positive conception of fiction—and especially his contention that we learn through the emotions when we engage with tragic fiction—can serve as an admirable pedagogical model for today’s fiction-focused foreign language classrooms.
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Using an epistemological and feminist lens, this thesis analyzes the political and social forces that actively construct both knowledge and ignorance around female sexual pleasure. It draws from interviews and a focus group, all conducted at Bucknell Unviersity to explore the journeys that women take to gain knowledge about sexual pleasure, and how the sources and cultural mores that women in the twenty-first century rely on or go up against in order to gain such knowledge are often limited, unauthorized or phallocentric. This aids in the construction and perpetuation of ignorance. This thesis looks at how women feel shame or enact self-censorship, regardless of their assertion of knowledge concerning their sexual appetites, which results in consequential ambivalence. For this reason, it concludes that more informed and educational conversations between peers, parents and partners need to take place. These conversations will help to ignite change and to raise awareness about the knowledge and ignorance surrounding female sexual pleasure, which would allow for more pleasurable experiences to take place generally and with a brief over view on Bucknell's campus specifically.
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A general theory of violence may only be possible in the sense of a meta-theoretical framework, As such it should comprise a parsimonious set of general mechanisms that operate across various manifestations of violence. In order to identify such mechanisms, a general theory of violence needs to equally consider all manifestations of violence, in all societies, and at all times. Departing from this assumption this paper argues that three theoretical approaches may be combined in a non-contradictory way to understand violence as goal-directed instrumental behaviour: a theory of the judgment and decision-making processes operating in the situations that give rise to violence; a theory of the evolutionary processes that have resulted in universal cognitive and emotional mechanisms associated with violence; and a theory of the way in which social institutions structure violence by selectively enhancing its effectiveness for some purposes (i.e legitimate use of force) and controlling other types of violence (i.e crime). To illustrate the potential use of such a perspective the paper then examines some general mechanisms that may explain many different types of violence. In particular, it examines how the mechanisms of moralistic aggression (Trivers) and moral disengagement (Bandura) may account for many different types of violence.