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Search Results: 1 - 10 of 197147 matches for " Elquio E. Oliveira "
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MICROEMULS O: UM PROMISSOR CARREADOR PARA MOLéCULAS INSOLúVEIS
Bolivar P. G. L. Damasceno,José A. Silva,Elquio E. Oliveira,Walte?á L. L. Silveira
Revista de Ciências Farmacêuticas Básica e Aplicada , 2011,
Abstract: Microemuls o (ME) é um sistema que foi descoberto por Hoar e Schulman no ano de 1943 e que é termodinamicamente estável e isotropicamente translúcido de dois líquidos imiscíveis (óleo/água), estabilizados por um filme interfacial de tensoativos. O estudo de sistemas microemulsionados se baseia nas suas três teorias de forma o: (1) teoria da solubiliza o, (2) teoria da tens o interfacial e (3) teoria termodinamica. A estrutura formada é influenciada pelas propriedades físico-químicas dos componentes utilizados e da raz o entre os componentes. O objetivo desta revis o foi avaliar o estado da arte de sistemas microemulsionados enfatizando uma abordagem teórica. Além disso, os recentes avan os sobre a aplicabilidade clínca e utiliza o como carreador de moléculas insolúveis foram discutidas. Palavras-chave: Aplica es Clínicas. Diagrama de Fases. Microemuls o. ABSTRACT Microemulsion: a promising carrier system for insoluble compounds Microemulsions (ME) are thermodynamically stable and isotropic systems of two immiscible liquids (oil/water), stabilized by an interfacial film of surfactants, discovered by Hoar and Schulman in 1943. The study of ME formation is based on three areas of theory: (1) solubilization, (2) interfacial tension and (3) thermodynamics. ME structures are influenced by the physicochemical properties and proportions of their ingredients. The goal of this review is to assess the state of the art of microemulsified systems, from a theoretical viewpoint. Also, recent progress on their clinical application and use as carriers for insoluble compounds is discussed. Keywords: Microemulsion. Pharmaceutical Application. Phase Diagram.
Lagrange as a Historian of Mechanics  [PDF]
Agamenon R. E. Oliveira
Advances in Historical Studies (AHS) , 2013, DOI: 10.4236/ahs.2013.23016
Abstract: In the first and second parts of his masterpiece, Analytical Mechanics, dedicated to static and dynamics respectively, Lagrange (1736-1813) describes in detail the development of both branches of mechanics from a historical point of view. In this paper this important contribution of Lagrange (Lagrange, 1989) to the history of mechanics is presented and discussed in tribute to the bicentennial year of his death.
History of Two Fundamental Principles of Physics: Least Action and Conservation of Energy  [PDF]
Agamenon R. E. Oliveira
Advances in Historical Studies (AHS) , 2014, DOI: 10.4236/ahs.2014.32008
Abstract: One of the aims most sought after by physics along the years has been to find a principle, the simplest possible, into which all natural phenomena would fit, and which would also allow the calculation of all past occurrences and principally future occurrences. Evidently, this is far from being reached and quite probably does not even exist. Nevertheless, an approximation to this ideal is always possible and the history of physics shows that some results in this direction have been achieved. Thus, the history of the principles of least action and conservation of energy presented in this paper explains the search for this ideal.
Charles-Augustin Coulomb—The Founder of Physiology and Ergonomics  [PDF]
Agamenon R. E. Oliveira
Advances in Historical Studies (AHS) , 2016, DOI: 10.4236/ahs.2016.55017
Abstract: The memoir Sur la force des Hommes was published by Coulomb in 1778. It is an attempt to understand human work mechanically and is the first publication on physiology and ergonomics. The question introduced by Coulomb appears from a pragmatic point of view. He proposed to measure the quantity of action (mechanical work) that a man can expend in a day of work by different ways of applying force. To do this, Coulomb studied the old problem of human mechanical capacity, also studied by Theophilus Desagulliers (1683-1744) and Daniel Bernoulli (1700-1782). In this paper we examine and discuss Coulomb’s above-mentioned publication showing his pioneering approach (Coulomb, 2002).
D’Alembert: Between Newtonian Science and the Cartesian Inheritance  [PDF]
Agamenon R. E. Oliveira
Advances in Historical Studies (AHS) , 2017, DOI: 10.4236/ahs.2017.64010
Abstract: This paper is a tribute to the tercentenary of d’Alembert’s birth. It studies the way how d’Alembert (1717-1783), with his Cartesian education, assimilated and developed Newtonian science. His Cartesianism involved the conception of the intelligibility and rationality of the principles of knowledge. His discovery of Newtonian science determined the direction of his work, with the laws of dynamics and gravitational attraction, as well as the mathematical-physics approach to mechanical problems. However, d’Alembert’s work is not just a mere development of Newtonian physics, but a real conceptual reorganization of mechanics, using differential and integral calculus formulated by Newton (1642-1727) and Leibniz (1646-1716).
Russian Science Prior to the Russian Revolution  [PDF]
Agamenon R. E. Oliveira
Advances in Historical Studies (AHS) , 2018, DOI: 10.4236/ahs.2018.73008
Abstract: This paper is an attempt to present and discuss the scientific context prior to the outbreak of the Russian Revolution in 1917. Some general aspects of the scientific milieus of the eighteenth and nineteenth centuries are described, including the period of Peter the Great, the foundation of the Academy of Science, and the influence of great figures of science, both Russian and foreign. In the eighteenth century, Euler (1707-1783) and Lomonosov (1711-1765) were chosen as symbolic and representative figures, while in the nineteenth century, Lobachevski (1792-1856), Chebyshev (1821-1894), Mendeleev (1834-1907), and Pavlov (1849-1936) were looked.
Le Développement Durable: à la croisée de l'économie, de la société et de l'environnement
Rui Oliveira e Silva
Silva Lusitana , 2010,
Abstract:
Nonexistence of extremizers for certain convex curves
Diogo Oliveira e Silva
Mathematics , 2012,
Abstract: We establish the nonexistence of extremizers for a local Fourier restriction inequality on a certain class of planar convex curves whose curvature satisfies a natural assumption. We accomplish this by studying the local behavior of the triple convolution of the arclength measure on the curve with itself, and show in particular that every extremizing sequence concentrates at a point on the curve.
Extremizers for Fourier restriction inequalities: convex arcs
Diogo Oliveira e Silva
Mathematics , 2012,
Abstract: We establish the existence of extremizers for a Fourier restriction inequality on planar convex arcs without points with colinear tangents whose curvature satisfies a natural assumption. More generally, we prove that any extremizing sequence of nonnegative functions has a subsequence which converges to an extremizer.
On Learning by Exchanging Advice
L. Nunes,E. Oliveira
Computer Science , 2002,
Abstract: One of the main questions concerning learning in Multi-Agent Systems is: (How) can agents benefit from mutual interaction during the learning process?. This paper describes the study of an interactive advice-exchange mechanism as a possible way to improve agents' learning performance. The advice-exchange technique, discussed here, uses supervised learning (backpropagation), where reinforcement is not directly coming from the environment but is based on advice given by peers with better performance score (higher confidence), to enhance the performance of a heterogeneous group of Learning Agents (LAs). The LAs are facing similar problems, in an environment where only reinforcement information is available. Each LA applies a different, well known, learning technique: Random Walk (hill-climbing), Simulated Annealing, Evolutionary Algorithms and Q-Learning. The problem used for evaluation is a simplified traffic-control simulation. Initial results indicate that advice-exchange can improve learning speed, although bad advice and/or blind reliance can disturb the learning performance.
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