Context storage for M2M scenarios

As the number of environmental sensors grows, it becomes increasingly difficult to manage, store and process all these sources of information. Several context representation schemes try to standardize this information, however none of them have been widely adopted. Instead of proposing yet another context representation scheme, we discuss efficient ways to deal with this diversity of representation schemes. We defined the basic requirements for flexible context storage systems, proposed an implementation and compared our implementation against two other approaches. Our solution provides more value than the remaining solutions without suffering a significant decrease in performance

Refractive changes following surgery for correction of esotropia

Purpose: To evaluate changes in refraction and corneal curvature following surgery for correction of acquired esotropia. Methods: 42 eyes of 21 patients with acquired moderate angle esotropia without any other form of strabismus were prospectively enrolled and submitted to a complete ophthalmological examination followed by recess/resect procedure in a single eye. Data from the fellow eye were selected as control. Ophthalmological assessment was carried out preoperatively, 1 month after surgery and 6 months after surgery, where astigmatism was compared using vector analysis and the polar value concept. Results: The eyes submitted to surgery revealed a significant (p<0.05) decrease in spherical equivalent, from 3.28 ± 1.98 diopters to 3.05 ± 1.95 diopters. Refraction data disclosed a significant increase in the 90° component of net astigmatism, from 0.458 ± 0.594 diopters to 1.002 ± 0.718 diopters, which was also observed in keratometric readings:1.083 ± 0.560 diopters to 1.690 ± 0.591 diopters. Surgically induced astigmatism, assessed using refraction data was 0.63 ± 0.27 diopters at an average axis of 92.30 ± 14.91 degrees, and 0.71 ± 0.27 diopters at an average axis of 94.45 ± 15.69 degrees as obtained by keratometric readings. This is visually demonstrated by the corneal topography difference map. Conclusions: There is a statistically significant and clinically relevant increase in with-the-rule astigmatism in esotropic patients submitted to monocular recess/resect surgery. This change is stable at a 6 month follow-up and is associated with a decrease in mean spherical equivalent.Objetivo: Estudar o comportamento da refração e da curvatura corneana em pacientes com esotropia essencial submetidos à cirurgia monocular para correção do estrabismo. Métodos: Estudo prospectivo em que 42 olhos de 21 pacientes com esotropia essencial de ângulo moderado, sem quaisquer outros estrabismos associados, foram selecionados e submetidos ao exame oftalmológico completo e à cirurgia monocular. O olho contralateral serviu como grupo controle. Foram feitas avaliações de pré-operatório, pós-operatório de 1 mês e pós-operatório de 6 meses. O astigmatismo pré-operatório foi confrontado com os astigmatismos pós-operatórios por análise vetorial e cálculo do valor polar. Resultados: Obtivemos, nos olhos operados, redução significante (p<0,05) na médio do equivalente esférico, de 3,28 ±1,98 dioptrias para 3,05 ± 1,95 dioptrias. Na refração houve um aumento significante da média do componente a 90° do astigmatismo, de 0,458 ± 0,594 dioptrias para 1,002 ± 0,718 dioptrias, também observado na ceratometria: 1,083 ± 0,560 dioptrias para 1,690 ± 0,591 dioptrias. A média do astigmatismo induzido pela cirurgia, na refração, foi de 0,63 ± 0,27 dioptrias a um eixo médio de 92,30 ± 14,91 graus e de 0,71 ± 0,27 dioptrias a um eixo médio de 94,45 ± 15,69 graus na ceratometria, evidenciáveis graficamente pelo mapa diferencial da topografia corneana. Conclusões: Observa-se aumento estatisticamente significante e clinicamente relevante do astigmatismo a-favor-da-regra em pacientes esotrópicos submetidos ao retrocesso/ressecção monocular. Essa mudança é estável ao longo do tempo e é acompanhada de diminuição significante do equivalente esférico.Faculdade de Medicina da Universidade de São Paulo Hospital das Clínicas Departamento de OftalmologiaSanta Casa de São Paulo Departamento de OftalmologiaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de OftalmologiaUNIFESP, EPM, Depto. de OftalmologiaSciEL

Competition between ferroelectric and semiconductor properties in Pb(Zr0.65Ti0.35)O-3 thin films deposited by sol-gel

Asymmetric metal–ferroelectric–metal (MFM) structures were manufactured by sol–gel deposition of a lead zirconate-titanate (PZT with Zr/Ti ratio 65/35) film on Pt-coated Si, with a Au top electrode. The average remnant polarization of 9 µC/cm2 and the coercive field of 39 kV/cm were obtained from the hysteresis loop measurements. A detailed analysis of the polarization–electric field (P–E), capacitance–voltage (C–V), and current–voltage (I–V) measurement results allowed us to estimate the near-electrode space-charge region thickness (roughly half of the film thickness at zero voltage), net doping concentration (around 1018 cm–3), built-in potential (in the 0.4–0.8 V range, depending on the injecting electrode), and dynamic dielectric constant (5.2). The current logarithm–voltage dependence for the field-enhanced Schottky emission obeys a "1/4" law. The spectral distribution of the short circuit current measured under continuous light illumination in the 290–800 nm range exhibits a cutoff wavelength at 370 nm and a maximum sensitivity at about 340 nm. The estimated band-gap energy of the PZT material is 3.35 eV. The MFM structure is discussed in terms of two back-to-back Schottky diodes with a ferroelectric material in between. It is concluded that the semiconductor properties of the films are not negligible and, in certain conditions, are dominating over the ferroelectric one

The 'spinning disk touches stationary disk' problem revisited: an experimental approach

A popular Newtonian mechanics problem, featured in textbooks, physics olympiads and forums alike, concerns two disks with different radii and moment of inertia that rotate differently and that touch each other. Most students struggle to calculate the final angular velocity of the disks, erroneously attempting to use different conservation laws. In this paper we propose a simple experiment that should help physics teachers explain this challenging exercise in an engaging way for the students. By using a smartphone/tablet and video analysis tools, the angular velocity of both disks can easily be tracked as a function of time, clearly showing the three stages of the interaction (before touching, only one disk rotating; touching with slippage; and touching without slippage). Processing and plotting of the data in a spreadsheet immediately shows which quantities are conserved and which are not. Several extensions to the core experiment are also suggested

IMAGINÁRIO, LITERATURA E EDUCAÇÃO POPULAR: NOTAS SOBRE QUESTÕES DE GÊNERO A PARTIR DA OBRA AS FILHAS DE LILITH DE CIDA PEDROSA

Esta pesquisa apresenta discussões que interligam os campos da Educação Popular, Literatura e Gênero à luz da Teoria do Imaginário. Assim, este estudo tem o objetivo geral de compreender as representações da categoria gênero presentes no pensamento literário da escritora pernambucana Cida Pedrosa. Trata-se de uma investigação de natureza bibliográfica, exploratória e descritiva quanto aos seus fins. Os resultados alcançados a partir da análise da obra eleita aludem a premissas de que a literatura, entendida enquanto espaço e prática formativa, potencializa uma compreensão plural e interdisciplinar acerca da categoria gênero. Ainda, que as concepções apresentadas na obra da escritora Cida Pedrosa perfazem a literatura como expressão sensível e possível à resignificação dos modelos e discursos hegemônicos sobre questões de gênero. E, por fim, que o saber não formal, assim como o produzido na literatura de Cida Pedrosa, aliado a teorias não redutoras, é imprescindível à resistência as imposições epistemológicas que marcam a produção hegemônica do conhecimento

The effect of a tangential frictional force on rotating disks: an experimental approach

This paper describes an experiment with two touching rotating disks, whose movement is followed by video analysis. Within the disks’ movements, there are intervals with sliding and intervals without sliding, that is, intervals with frictional forces between the touching surfaces and intervals without it. This system configuration allows for measurement of the changeable magnitudes and directions of frictional forces (much more difficult to set up with translational motion). This activity may be used to combat students misconceptions of “frictional force always opposes the motion” and “between the same two bodies, one gets the same frictional force,” commonly found in the classroom, or just to reinforce the rotational dynamics relationships

Endurance exercise bout does not interfere in strength performance of upper limbs

OBJETIVO: O presente estudo avaliou o efeito do exercício de endurance (corrida) sobre o subseqüente desempenho de força de músculos dos membros superiores e do tronco. METODOLOGIA: A amostra foi composta por 13 universitárias, saudáveis e fisicamente ativas. A primeira fase do experimento consistiu na realização de um teste de corrida, simulando uma sessão de treino, com duração de 45 minutos a 70% da FC MAX. Imediatamente após a corrida, foram aplicados testes de força (dinamometria - preensão palmar, teste de 1-RM e teste de repetições máximas a 70%-1RM no supino). A glicemia foi mensurada no início do experimento e imediatamente antes dos testes de força. RESULTADOS: Não foi observada diferença significativa no desempenho dos testes de força após o treino de corrida (dinamometria, 1-RM e REPMAX - sem a prévia execução do treino de corrida - 29,9 ± 3,8 kgf; 34,4 ± 3,1 kg; 1ºset: 12,5 ± 3,3 reps e 2ºset: 11,7 ± 2,7 reps vs. com a prévia execução do treino de corrida - 29,2 ± 3,1 kgf; 33,9 ± 2,5 kg; 1ºset: 13,2 ± 2,1 reps e 2ºset: 12,2 ± 2,8 reps). Com relação à glicemia, não foi detectada alteração significativa durante o experimento. CONCLUSÃO: A execução do treino de corrida não afetou o subseqüente desempenho de força dos membros superiores e do tronco. Esse dado sugere que a interferência, freqüentemente, observada no exercício concorrente, é dependente do grupo muscular treinado. Possivelmente, o efeito adverso induzido pelo treino concorrente, realizado, exclusivamente, com membros inferiores, é decorrente da fadiga residual instalada nos músculos recrutados na atividade anterior. É importante ressaltar que a atividade de endurance não promoveu alteração na concentração plasmática de glicose. A manutenção da glicemia associada à ausência de interferência sobre o desempenho dos testes de força reforça, mais ainda, a hipótese de que o efeito adverso do treinamento concorrente é, provavelmente, causado por alterações periféricas músculo-específicas.AIM: the present study evaluated the effect of endurance exercise (running) on the subsequent strength performance of muscles of upper limbs and trunk. METHODOLOGY: Thirteen healthy female, university students, physically active were selected to compose the sample. The first phase of the experiment the subjects were submitted to an endurance exercise bout (treadmill), simulating a training session, with duration of 45 minutes at 70% of the HRmax. Immediately after the endurance exercise bout, the subjects performed strength tests (Dynamometry test - handgrip, 1RM test and maximal repetitions test at 70%-1RM in the bench press). Glycemia was measured in the beginning of the experiment and immediately before the strength tests. RESULTS: No significant difference was observed in the strength tests performance after the endurance exercise bout (Dynamometry, 1-RM and REPMAX - with no previous endurance exercise - 29.9 ± 3.8 kgf; 34.4 ± 3.1 kg; 1st set 12.5 ± 3.3 reps and 2nd set 11.7 ± 2.7 reps vs. with previous endurance exercise - 29.2 ± 3.1 kgf; 33.9 ± 2.5 kg; 1st set 13.2 ± 2.1 reps and 2nd set 12.2 ± 2.8 reps). Regarding glycemia, no significant alteration was observed during the experiment. CONCLUSION: the endurance exercise bout did not affect the subsequent strength performance of the upper limbs and trunk. This data suggests that the common interference observed in the concurrent training is dependent on which muscular group has been recruited. Possibly, the adverse effect induced by the concurrent training, exclusively performed with lower extremities, is due to the residual fatigue installed in the muscles recruited in the previous activity. It is important to highlight that endurance exercise did not promote alteration in the glucose plasma concentration. The glycemia maintenance associated with the lack of interference on the performance of the strength tests reinforces even more the hypothesis that the adverse effect of the concurrent training is probably caused by muscle-specific peripheral alterations

Structural and dielectric properties of laser ablated BaTiO3 films deposited over electrophoretically dispersed CoFe2O4 grains

Thin film nanocomposites with mixed connectivity, composed by CoFe2O4 grains deposited by electrophoresis on Si|Pt substrates and subsequently covered by a laser ablation deposited BaTiO3 layer were prepared with different cobalt ferrite concentrations. Their structure presented a combination of BaTiO3, with its tetragonal and the orthorhombic phases coexisting at room temperature, and CoFe2O4 with the cubic spinel structure. The cobalt ferrite nanograins were under in-plane tensile stress, while the BaTiO3 phase was under in-plane compressive stress. The dielectric measurements showed that as the barium titanate grain size decreased, its ferroelectric Curie temperature shifted to lower temperatures relative to the bulk. This grain size dependent TC shift was associated and modeled by a core-shell structure of BaTiO3 grains in the films, with a tetragonal core and cubic shell. Additionally a diffuse tetragonal-orthorhombic phase transition was observed and, in agreement with Raman spectroscopy results, associated to the coexistence of barium titanate orthorhombic and tetragonal phases in the room temperature region. This led to the formation of polar nanoclusters with random polarization orientations, which induced a frustrated phase transition between the tetragonal and orthorhombic phases of barium titanate in the films.This work has been supported by Fundacao para a Ciencia e Tecnologia (FCT) and FEDER, through the projects PTDC/CTM/099415/2008 and PTDC/CTM-NAN/115125/2009 and by QREN-ON2-O Novo Norte, through the project Operacao Norte-070124-FEDER-000070. J. G. Barbosa and I. T. Gomes gratefully acknowledge PhD grants from Fundacao para a Ciencia e Tecnologia (SFRH/BD/41913/2007 and SFRH/BD/36348/2007, respectively)