Eficácia de barreiras acústicas

O tráfego rodoviário tem impactes significativos no ambiente, na saúde e na qualidade de vida das populações. Os avultados investimentos aplicados na construção de barreiras acústicas nem sempre se traduzem numa redução eficaz do ruído. Esta comunicação apresenta os resultados da avaliação da eficácia de três barreiras acústicas colocadas em vias de comunicação com volumes de tráfego distintos. Os materiais que as constituem são blocos de betão parcialmente preenchidos com lã de rocha, chapa metálica perfurada com lã de rocha e painéis pré-fabricados de betão com inertes leves. A avaliação da eficácia de cada barreira acústica foi efectuada com recurso a sonómetros colocados à frente, no tardoz e numa zona contígua não influenciada pela mesma. Para complementar a avaliação, estabelecem-se comparações entre os valores medidos e os valores obtidos a partir de modelos simplificados de comportamento.The road traffic has significant impacts in the environment, in population quality of life and health. The large investments applied in construction of acoustics barriers nor always result in an efficient noise reduction. This paper presents the results of the evaluation of the effectiveness of three acoustics barriers placed in highways with distinct traffic. The materials that constitute the barriers are concrete blocks partially filled with rockwool, perforated metallic shell with rockwool and prefabricated concrete panels. The evaluation of the effectiveness of each acoustics barrier was carried out with sound level meters placed in the front, behind and in a contiguous zone not influenced by the barrier. Comparisons between the measured values and the values gotten from simplified behaviour models are established

Spin-orbit mode transfer via a classical analog of quantum teleportation

We translate the quantum teleportation protocol into a sequence of coherent operations involving three degrees of freedom of a classical laser beam. The protocol, which we demonstrate experimentally, transfers the polarisation state of the input beam to the transverse mode of the output beam. The role of quantum entanglement is played by a non-separable mode describing the path and transverse degrees of freedom. Our protocol illustrates the possibility of new optical applications based on this intriguing classical analogue of quantum entanglement.Comment: 5 pages, 7 figure

Colocando as mãos (e o conhecimento) na massa: uso de massa de modelar como atividade lúdica no ensino de Biologia Celular

Anais do 3° Encontro Nacional de Jogos e Atividades Lúdicas no Ensino de Química, Física e Biologia (Jalequim - Level III) - Núcleo de Desenvolvimento de Pesquisas em Ensino de Química/Ciências da UNILA (NuDDEQ)Nos últimos anos tem crescido as discussões de educadores e pesquisadores, sobre a busca por novos métodos e propostas de ensino. Para Santos et al. (2011) o aumento desses métodos e pesquisas visam superar o modelo tradicional de ensino, buscando o diálogo entre professores e educandos e a participação dos mesmos em sala de aul

Astigmatic tomography of orbital angular momentum superpositions

We use astigmatic transformations to characterize two-dimensional superpositions of Orbital Angular Momentum (OAM) states in laser beams. We propose two methods for doing this, both relying only on astigmatic transformations, viewed as rotations on the Poincar\'e sphere, followed by imaging. These methods can be used as a tomographic tool for communication protocols based on optical vortices.Comment: Submitted to Physical Rivew

Photoacoustic Monitoring Of Magnetite-crystal Formation From Iron(iii) Hydroxide Acetate: Comparison With Esr Results

The formation of crystalline magnetite by 1-h heat treatment of iron(III) hydroxide acetate is described. This amorphous-crystalline solid transformation is monitored by electron-spin resonance and photoacoustic spectroscopies. No significant changes were detected for samples heated below 190 °C. Above this temperature both techniques presented results following a definite pattern, namely, the enhancement of ion mobility leading to particle growth and crystallization for a temperature up to 240 °C and the onset of magnetic ordering of magnetite near this temperature.65125150515