Pullback attractors for a singularly nonautonomous plate equation

We consider the family of singularly nonautonomous plate equation with structural damping $$u_{tt} + a(t,x)u_{t} + (- \Delta) u_{t} + (-\Delta)^{2} u + \lambda u = f(u),$$ in a bounded domain $\Omega \subset \R^n$, with Navier boundary conditions. When the nonlinearity $f$ is dissipative we show that this problem is globally well posed in $H^2_0(\Omega) \times L^2(\Omega)$ and has a family of pullback attractors which is upper-semicontinuous under small perturbations of the damping $a$

O cenário de pesquisas sobre Filosofia da Tecnologia no Ensino de Ciências por meio do estado da arte

Nesta pesquisa tivermos como objetivo identificar o estado da arte em trabalhos acerca da Filosofia da Tecnologia no Ensino de Ciências. Utilizarmos para fundamentar as nossas ideias utilizarmos os apontamentos de Herbert Marcuse acerca da Filosofia da Tecnologia, especificamente sobre a sociedade unidimensional que utiliza a ideia de neutralidade da Ciência e da Tecnologia para perpetuar o sistema de dominação capitalista. Assim, elaboramos o estado da arte de publicações da área de Ensino de Ciências a fim de mapear as pesquisas publicados em periódicos-Qualis de A1 a B2 na classificação de 2016 e também no banco de teses e dissertações da Capes, além de eventos científicos. Identificarmos apenas 6 trabalhos ao total que estão   de acordo com os critérios de inclusão de inclusão. Com isso, observamos lacunas imensas de pesquisas que articulem a Filosofia da Tecnologia nos moldes marcuseano com o Ensino de Ciências. Dessa forma, reiteramos que é pertinente para a área de Ensino englobar tais discussões para consolidar a linha de Filosofia da Tecnologia que permite pensar a sociedade de forma mais crítica, buscando promover a emancipação humana

A crítica da Ciência e da Tecnologia em Herbert Marcuse: Implicações para a Educação em Ciências

In this research we aimed to point out Herbert Marcuse's ideas about the problem of neutrality of science and technology for Science Education. Thus, we conducted an analysis of science and technology through Marcuse's point of view, using for this his texts published in books and articles, and when relevant, we will resort to commentators to complement our ideas regarding the author's understanding and his understanding of science and technology. In this sense, science and technology for Marcuse are one-dimensionalized to be used to dominate nature and promote neutrality, omitting aspects of reflection, among them, the criticism of the dominant status and the emancipation of human beings. To overcome this, Marcuse thought of a new science and a new technology in which we would be placed in harmony with nature and not in conflict with it. Thus, Marcuse's ideas are relevant and more than necessary to think of a new society under the aegis of human emancipation to overcome the one-dimensional society based on domination by scientific and technological rationality.En esta investigación pretendemos señalar las ideas de Herbert Marcuse sobre el problema de la neutralidad de la ciencia y la tecnología para la enseñanza de las ciencias. De esta manera, se realizó un análisis de la ciencia y la tecnología a través del punto de vista de Marcuse utilizando para ello sus textos publicados en libros y artículos y cuando sea pertinente recurriremos a comentaristas para complementar nuestras ideas sobre la comprensión del autor y su entendimiento sobre la ciencia y la tecnología. En este sentido, la ciencia y la tecnología para Marcuse están unidimensionalizadas para ser utilizadas para dominar la naturaleza y promover la neutralidad omitiendo aspectos de reflexión, entre ellos, la crítica al estatus dominante y la emancipación del ser humano. Para superar esto, Marcuse pensó en una nueva ciencia y una nueva tecnología en la que nos pusiéramos en armonía con la naturaleza y no en conflicto con ella. Así, las ideas de Marcuse son pertinentes y más que necesarias para pensar en una nueva sociedad bajo la égida de la emancipación humana para superar la sociedad unidimensional basada en la dominación de la racionalidad científica y tecnológica.Nesta pesquisa tivermos como objetivo apontar por meio de discussões das ideias de Hebert Marcuse o problema da neutralidade da ciência e da tecnologia para a Educação em Ciências. A escolha por analisar o trabalho de Hebert Marcuse ocorreu devido a área de Educação em Ciências não ter avançado em relação a pesquisas que utilizem de ideias de teóricos advindos da escola de Frankfurt. Nesse sentido, A ciência e tecnologia para Marcuse são unidimensionalizada para serem utilizadas para dominar a natureza e com isso catalisar a produção dinamizando as forças produtivas. Assim, em nome de uma suposta neutralidade aspectos da reflexão estão ocultos, dentre esses a crítica aos status dominante e a emancipação dos seres humanos. Para superar isso, Marcuse pensou em uma nova ciência e uma nova tecnologia no qual seríamos colocados em harmonia com a natureza e não em conflito com ela. As ideias de Marcuse são relevantes e mais do que necessárias para pensar uma nova sociedade sobre a égide da emancipação humana para a superação da sociedade unidimensional pautada na dominação da racionalidade científica e tecnológica

Articulações entre a Perspectiva CTSA e a Ciência e a Tecnologia em Herbert Marcuse: Contribuições para o Ensino de Ciências

In the present research we had the objectives to make approximations between the CTSA perspective and the ideas about Science and Technology and to make contributions to Science Teaching in the one-dimensional society. This allows us to reflect on the participation of people aware of their real needs as a decisive factor for the transformation of the one-dimensional society into a more just and egalitarian one, in which people will be involved and understand how the processes of decision making occur in order to transcend the very vision of people's participation, as the CTSA perspective preaches, so that, besides participating, they can be protagonists of the political process in order to build a new society in which class struggles no longer exist. Therefore, we point out that the area of Science Teaching advances when it discusses issues that problematize the neutral character that the dominant classes want people to have in relation to Science and Technology and that reflect in the movements of scientific denials in a pandemic that caused disinformation about vaccination. Thus, we understand that the CTSA perspective integrated with Marcuse's ideas allows us to understand complex issues that are increasingly present in a one-dimensional society, as well as the crisis of democracies with the rise of disinformation aiming to control people so that they can defend the current system.El objetivo de esta investigación era acercar la perspectiva de la CTSA a las ideas sobre ciencia y tecnología y hacer aportaciones a la enseñanza de las ciencias en una sociedad unidimensional. Ello nos permite reflexionar sobre la participación de las personas conscientes de sus necesidades reales, factor decisivo para transformar una sociedad unidimensional en otra más justa e igualitaria, en la que las personas se involucren y comprendan cómo se producen los procesos de toma de decisiones, de forma que se trascienda la propia visión de participación de las personas, tal y como propugna la perspectiva CTSA, para que además de participar, sean protagonistas del proceso político, en el sentido de construir una nueva sociedad en la que ya no exista la lucha de clases. Frente a esto, queremos señalar que el campo de la Enseñanza de las Ciencias avanza cuando discute cuestiones que problematizan el carácter neutro que las clases dominantes quieren que las personas tengan en relación a la Ciencia y a la Tecnología y que se reflejan en los movimientos de negacionismo científico en una pandemia que provocó la desinformación sobre la vacunación. Así, entendemos que la perspectiva de la CTSA integrada con las ideas de Marcuse nos permite comprender cuestiones complejas cada vez más presentes en la sociedad unidimensional, así como la crisis de las democracias con el auge de la desinformación dirigida a controlar a las personas para que defiendan el sistema actual.Na presente pesquisa tivermos os objetivos de realizar aproximações entre a perspectiva CTSA com as ideias sobre Ciência e Tecnologia e tecer contribuições para o Ensino de Ciências na sociedade unidimensional. Isso permite refletir sobre a participação das pessoas cientes das suas reais necessidades sendo  um fator decisivo para a transformação da sociedade unidimensional em uma sociedade mais justa e igualitária no qual as pessoas estarão envolvidas e entenderam como ocorre os processos de tomadas de decisões de forma a transcender a própria visão de participação das pessoas como preza a perspectiva CTSA para que elas além de participar sejam protagonista do processo político no sentido de construírem uma nova sociedade em que as lutas de classes não existam mais. Diante disso, apontarmos que a área de Ensino de Ciências avança quando discute questões que problematizam o caráter neutro que as classes dominantes querem que as pessoas tenham em relação a Ciência e a Tecnologia e que refletem nos movimentos de negacionismo científico em uma pandemia que provocou a desinformação sobre a vacinação. Assim, entendermos que a perspectiva CTSA integrado com as ideias de Marcuse permite compreender questões complexas cada vez mais presentes na sociedade unidimensional, bem como, a crise das democracias com a ascensão da desinformação com intuito de controle das pessoas para que elas possam defender o sistema vigente. &nbsp

Measuring random force noise for LISA aboard the LISA Pathfinder mission

The LTP (LISA Testflight Package), to be flown aboard the ESA / NASA LISA Pathfinder mission, aims to demonstrate drag-free control for LISA test masses with acceleration noise below 30 fm/s^2/Hz^1/2 from 1-30 mHz. This paper describes the LTP measurement of random, position independent forces acting on the test masses. In addition to putting an overall upper limit for all source of random force noise, LTP will measure the conversion of several key disturbances into acceleration noise and thus allow a more detailed characterization of the drag-free performance to be expected for LISA.Comment: 7 pages, 3 figures. To be published in Classical and Quantum Gravity with the proceedings of the 2003 Amaldi Meetin

Threshold of motion and orientation of bivalve shells under current flow

Disarticulated shells of three bivalve mollusk species (Anomalocardia brasiliana, Codakia orbicularis, and Divaricella quadrisulcata) were experimentally tested in laboratory flumes to determine the threshold of motion and final orientation of the valves. A total of 150 current flow experiments were conducted on single shells resting on a fixed sand bed. This study demonstrated that shells in the convex-up position are more resistant to flow when the umbo is pointing downstream rather than upstream. Moreover, species with higher frontal areas were more likely to be entrained at lower flow velocities. Results of dimensionless shear stress exhibited values far below the threshold of grains movement for beds of uniform roughness (Shields curve). It was observed that circular shells in convex-up positions were mostly orientated with the umbo pointing downstream. Conversely, elliptical shells in convex-up position tended to align their longer axis parallel to the flow with the posterior side of the valve pointing downstream. These results are not only directly applicable in interpretations of incipient shell motions and in paleocurrent analyses from field and sample data, but also support construction of accurate geological models

Abrasion wear resistance of different artificial teeth opposed to metal and composite antagonists

One of the most important properties of artificial teeth is the abrasion wear resistance, which is determinant in the maintenance of the rehabilitation's occlusal pattern. OBJECTIVES: This in vitro study aims to evaluate the abrasion wear resistance of 7 brands of artificial teeth opposed to two types of antagonists. MATERIAL AND METHODS: Seven groups were prepared with 12 specimens each (BIOLUX & BL, TRILUX & TR, BLUE DENT & BD, BIOCLER & BC, POSTARIS & PO, ORTHOSIT & OR, GNATHOSTAR & GN), opposed to metallic (M & nickel-chromium alloy), and to composite antagonists (C & Solidex indirect composite). A mechanical loading device was used (240 cycles/min, 4 Hz speed, 10 mm antagonist course). Initial and final contours of each specimen were registered with aid of a profile projector (20x magnification). The linear difference between the two profiles was measured and the registered values were subjected to ANOVA and Tukey's test. RESULTS: Regarding the antagonists, only OR (M = 10.45 ± 1.42 µm and C = 2.77 ± 0.69 µm) and BC (M = 6.70 ± 1.37 µm and C = 4.48 ± 0.80 µm) presented statistically significant differences (p < 0.05). Best results were obtained with PO (C = 2.33 ± 0.91 µm and M = 1.78 ± 0.42 µm), followed by BL (C = 3.70 ± 1.32 µm and M = 3.70 ± 0.61 µm), statistically similar for both antagonists (p>0.05). Greater result variance was obtained with OR, which presented the worse results opposed to Ni-Cr (10.45 ± 1.42 µm), and results similar to the best ones against composite (2.77 ± 0.69 µm). CONCLUSIONS: Within the limitations of this study, it may be concluded that the antagonist material is a factor of major importance to be considered in the choice of the artificial teeth to be used in the prosthesis

Porous iron-nitrogen-carbon electrocatalysts for anion exchange membrane fuel cells (AEMFC)

High-performance platinum group metal-free (PGM-free) electrocatalysts were prepared from porous organic polymers (POPs) precursors with highly-porous structures and adjustable surface area. A resin phenol-melamine-based POP and an iron salt were used to synthesize Fe−N−C catalysts with different iron contents (0.2–1.3 wt.%). Electrochemical and spectroscopical characterization allowed us to elucidate the effect of Fe content on the material's structure, surface chemistry, and electrocatalytic activity toward the oxygen reduction reaction (ORR). The increase of iron content led to a specific surface area decrease, preserving the morphological structure, with the formation of highly-active catalytic sites, as indicated by X-ray photoelectron spectroscopy (XPS) analysis. The rotating ring disk electrode experiments, performed at pH=13, confirmed the high ORR activity of both 0.5 Fe (E1/2=0.84 V) and 1.3 Fe (E1/2=0.83 V) catalysts, which were assembled at the cathode of a H2-fed anion exchange membrane fuel cells (AEMFC) equipped with a FAA-3-50 membrane, evidencing promising performance (0.5 Fe, maximum power density, Max PD=69 mA cm−2 and 1.3 Fe, Max PD=87 mA cm−2) with further advancement prospects