O ofuscamento da infância no brilho das telas: relações entre teoria crítica, educação e sociedade

Pós-graduação em Educação Escolar - FCLAR

Sistema autônomo de iluminação utilizando energia solar

This work presents a self-sustainable lighting system using ultracapacitor as a storage device, replacing the conventional battery, using solar energy as the only energy supplier. A detailed study of solar panels, switched mode converters and ultracapacitors was made, in order to design a circuit capable of capturing solar energy and transfer it efficiently to a bank of ultracapacitors. Later, at nighttime, this energy is used for lighting in LED luminaires which have high luminous efficiency and high reliability index. This work presents the design of the solar panel, ultracapacitors bank, the development of the voltage converter circuit and charger working at the maximum power point of the solar panel. All subsystems were simulated and it was shown that the use of ultracapacitors is feasible to feed a LED lamp with enough brightness for a person to walk at night, for two night shifts, using a capacitive bank with twenty-four ultracapacitors. Replacing the battery by an ultracapacitor allows a faster recharge, with low maintenance costs, since ultracapacitors have a lifetime bigger than batteries; beyond reducing the environmental impact, as they don't use potentially toxic chemical compounds

Comparison of Video Laryngoscopy Technologies

Indirect laryngoscopy allows practitioners to “see around the corner” of a patient’s airway during intubation. Inadequate airway management is a major contributor to patient injury, morbidity and mortality. The purpose of the present study was to evaluate the video quality of commercially available video laryngoscopy systems. A team of four investigators at the University of Nebraska at Omaha and the Peter Kiewit Institute performed intubation simulations using a number of video laryngoscopy systems. Testing was done with a Laerdal Difficult Airway Manikin (Laerdal Medical Corp., Wappingers Falls, NY) in a setting that simulated difficult airways, adverse lighting conditions and various system configurations (e.g., maximizing screen contrast, minimizing screen brightness, maximizing screen color hue, etc.).

Sistema autônomo de iluminação utilizando energia solar

This work presents a self-sustainable lighting system using ultracapacitor as a storage device, replacing the conventional battery, using solar energy as the only energy supplier. A detailed study of solar panels, switched mode converters and ultracapacitors was made, in order to design a circuit capable of capturing solar energy and transfer it efficiently to a bank of ultracapacitors. Later, at nighttime, this energy is used for lighting in LED luminaires which have high luminous efficiency and high reliability index. This work presents the design of the solar panel, ultracapacitors bank, the development of the voltage converter circuit and charger working at the maximum power point of the solar panel. All subsystems were simulated and it was shown that the use of ultracapacitors is feasible to feed a LED lamp with enough brightness for a person to walk at night, for two night shifts, using a capacitive bank with twenty-four ultracapacitors. Replacing the battery by an ultracapacitor allows a faster recharge, with low maintenance costs, since ultracapacitors have a lifetime bigger than batteries; beyond reducing the environmental impact, as they don't use potentially toxic chemical compounds

Opto-electrical properties of single layer flexible electroluminescence device with ruthenium complex

In this work, a ruthenium hexafluorophosphate complex, [Ru(bpy)(3)](PF6)(2) in poly(methylmethacrylate) (PMMA) was employed to build a single layer light electrochemical cell on indium tin oxide polyester flexible substrate. The electroluminescence spectrum features a relatively broad band peaked near 625 run, with CIE (x,y) color coordinates of (0.61,0.39). The driving voltage is only 3 V, and for the maximum electrical current of 10 mA the brightness reaches 1 cd/m(2). Regarding the useful application of the device, its opto-electrical behavior under mechanical strain was studied considering the central curvature. In these situations, both electrical characterization in DC mode and luminance were analyzed. (C) 2007 Elsevier B.V. All rights reserved.

Polymer Light Emitting Diode Using PFT-Poly(9,9 `-n-dihexil-2,7-fluorenodiilvinylene-alt-2,5thiophene)

The development of new electroluminescence polymers for specific colour tuning in Polymer Light Emitting Devices (PLEDs) is currently one of the most important fields for organic electronics. This work reports a synthesis of a new electroluminescent polymer and the concomitant test as PLED emissive layer. The polymer, synthesised from fluorene, is poly(9,9`-n-dihexil-2,7-fluorenodiilvinylene-alt-2,5thiophene) or PFT The luminescence shows large bands with maxima around 480 nm in absorption and 560 nm in emission. The device was made in a three layer structure, with PEDOT:PSS as hole transport layer, PFT as emissive layer and butyl-PBD as electron transport layer. The electroluminescence spectrum shows a strong band peaked at 540 nm. For an applied voltage of 12 Volt, the brightness at normal angle of viewing is near 10 cd/m(2) and the luminous efficiency is of 0.01 lm/W. A discussion about carrier transport and the electroluminescence properties is made.

Constraining H-0 in general dark energy models from Sunyaev-Zeldovich/X-ray technique and complementary probes

In accelerating dark energy models, the estimates of the Hubble constant, Ho, from Sunyaev-Zerdovich effect (SZE) and X-ray surface brightness of galaxy clusters may depend on the matter content (Omega(M)), the curvature (Omega(K)) and the equation of state parameter GO. In this article, by using a sample of 25 angular diameter distances of galaxy clusters described by the elliptical beta model obtained through the SZE/X-ray technique, we constrain Ho in the framework of a general ACDM model (arbitrary curvature) and a flat XCDM model with a constant equation of state parameter omega = p(x)/rho(x). In order to avoid the use of priors in the cosmological parameters, we apply a joint analysis involving the baryon acoustic oscillations (BA()) and the (MB Shift Parameter signature. By taking into account the statistical and systematic errors of the SZE/X-ray technique we obtain for nonflat ACDM model H-0 = 74(-4.0)(+5.0) km s(-1) Mpc(-1) (1 sigma) whereas for a fiat universe with constant equation of state parameter we find H-0 = 72(-4.0)(+5.5) km s(-1) Mpc(-1)(1 sigma). By assuming that galaxy clusters are described by a spherical beta model these results change to H-0 = 6(-7.0)(+8.0) and H-0 = 59(-6.0)(+9.0) km s(-1) Mpc(-1)(1 sigma), respectively. The results from elliptical description are in good agreement with independent studies from the Hubble Space Telescope key project and recent estimates based on the Wilkinson Microwave Anisotropy Probe, thereby suggesting that the combination of these three independent phenomena provides an interesting method to constrain the Bubble constant. As an extra bonus, the adoption of the elliptical description is revealed to be a quite realistic assumption. Finally, by comparing these results with a recent determination for a, flat ACDM model using only the SZE/X-ray technique and BAO, we see that the geometry has a very weak influence on H-0 estimates for this combination of data.

Using the Hard, Randy, and Rittler Test to Evaluate Color Vision in Capuchins (Cebus libidinosus)

The identification of color vision types in primates is fundamental to understanding the evolution and biological function of color perception. The Hard, Randy, and Rittler (HRR) pseudoisochromatic test categorizes human color vision types successfully. Here we provide an experimental setup to employ HRR in a nonhuman primate, the capuchin (Cebus libidinosus), a platyrrhine with polymorphic color vision. The HRR test consists of plates with a matrix composed of gray circles that vary in size and brightness. Differently colored circles form a geometric shape (X, O, or Delta) that is discriminated visually from the gray background pattern. The ability to identify these shapes determines the type of dyschromatopsy (deficiency in color vision). We tested six capuchins in their own cages under natural sunlight. The subjects chose between two HRR plates in each trial: one with the gray pattern only and the other with a colored shape, presented on the left or right side at random. We presented the test 40 times and calculated the 95 % confidence limits for chance performance based on the binomial test. We also genotyped all subjects for exons 3 and 5 of the X-linked opsin genes. The HRR test diagnosed two subjects as protan dichromats (missing or defective L-cone), three as deutan dichromats (missing or defective M-cone), and one female as trichromat. Genetic analysis supported the behavioral data for all subjects. These findings show that the HRR test can be applied to diagnose color vision in nonhuman primates.

A NEW METHOD TO QUANTIFY X-RAY SUBSTRUCTURES IN CLUSTERS OF GALAXIES

We present a new method to quantify substructures in clusters of galaxies, based on the analysis of the intensity of structures. This analysis is done in a residual image that is the result of the subtraction of a surface brightness model, obtained by fitting a two-dimensional analytical model (beta-model or Sersic profile) with elliptical symmetry, from the X-ray image. Our method is applied to 34 clusters observed by the Chandra Space Telescope that are in the redshift range z is an element of [0.02, 0.2] and have a signal-to-noise ratio (S/N) greater than 100. We present the calibration of the method and the relations between the substructure level with physical quantities, such as the mass, X-ray luminosity, temperature, and cluster redshift. We use our method to separate the clusters in two sub-samples of high-and low-substructure levels. We conclude, using Monte Carlo simulations, that the method recuperates very well the true amount of substructure for small angular core radii clusters (with respect to the whole image size) and good S/N observations. We find no evidence of correlation between the substructure level and physical properties of the clusters such as gas temperature, X-ray luminosity, and redshift; however, analysis suggest a trend between the substructure level and cluster mass. The scaling relations for the two sub-samples (high-and low-substructure level clusters) are different (they present an offset, i. e., given a fixed mass or temperature, low-substructure clusters tend to be more X-ray luminous), which is an important result for cosmological tests using the mass-luminosity relation to obtain the cluster mass function, since they rely on the assumption that clusters do not present different scaling relations according to their dynamical state.

Alessi 95 and the short-period Cepheid SU Cassiopeiae

The parameters for the newly discovered open cluster Alessi 95 are established on the basis of available photometric and spectroscopic data, in conjunction with new observations. Colour excesses for spectroscopically observed B- and A-type stars near SU Cas follow a reddening relation described by E(U-B)/E(B-V) = 0.83 + 0.02E(B-V), implying a value of R=AV/E(B-V) ? 2.8 for the associated dust. Alessi 95 has a mean reddening of E(B-V)(B0) = 0.35 +/- 0.02 s.e., an intrinsic distance modulus of V0-MV= 8.16 +/- 0.04 s.e. (+/- 0.21 s.d.), d= 429 +/- 8 pc, and an estimated age of 108.2 yr from zero-age main sequence (ZAMS) fitting of available UBV, CCD BV, NOMAD, and Two Micron All Sky Survey JHKs observations of cluster stars. SU Cas is a likely cluster member, with an inferred space reddening of E(B-V) = 0.33 +/- 0.02 and a luminosity of < MV >=-3.15 +/- 0.07 s.e., consistent with overtone pulsation (PFM= 2.75 d), as also implied by the Cepheids light-curve parameters, rate of period increase and Hipparcos parallaxes for cluster stars. There is excellent agreement of the distance estimates for SU Cas inferred from cluster ZAMS fitting, its pulsation parallax derived from the infrared surface brightness technique and Hipparcos parallaxes, which all agree to within a few per cent.

The 6dF Galaxy Survey: stellar population trends across and through the Fundamental Plane

We present results from an analysis of stellar population parameters for 7132 galaxies in the 6dF Galaxy Survey Fundamental Plane (FP) sample. We bin the galaxies along the axes, v1, v2 and v3, of the tri-variate Gaussian to which we have fitted the galaxy distribution in effective radius, surface brightness and central velocity dispersion (FP space), and compute median values of stellar age, [Fe/H], [Z/H] and [a/Fe]. We determine the directions of the vectors in FP space along which each of the binned stellar population parameters vary most strongly. In contrast to previous work, we find stellar population trends not just with velocity dispersion and FP residual, but with radius and surface brightness as well. The most remarkable finding is that the stellar population parameters vary through the plane (v1 direction) and across the plane (v3 direction), but show no variation at all along the plane (v2 direction). The v2 direction in FP space roughly corresponds to luminosity density. We interpret a galaxys position along this vector as being closely tied to its merger history, such that early-type galaxies with lower luminosity density are more likely to have undergone major mergers. This conclusion is reinforced by an examination of the simulations of Kobayashi, which show clear trends of merger history with v2.

New constraints on H-0 and Omega(m) from SZE/X-ray data and baryon acoustic oscillations

The Hubble constant, H-0, sets the scale of the size and age of the Universe and its determination from independent methods is still worthwhile to be investigated. In this article, by using the Sunyaev-Zeldovich effect and X-ray surface brightness data from 38 galaxy clusters observed by Bonamente et al. (Astrophys J 647:25, 2006), we obtain a new estimate of H-0 in the context of a flat Lambda CDM model. There is a degeneracy on the mass density parameter (Omega(m)) which is broken by applying a joint analysis involving the baryon acoustic oscillations (BAO) as given by Sloan Digital Sky Survey. This happens because the BAO signature does not depend on H-0. Our basic finding is that a joint analysis involving these tests yield H-0 = 76.5(-3.33)(+3.35) km/s/mpc and Omega(m) = 0.27(-0.02)(+0.03). Since the hypothesis of spherical geometry assumed by Bonamente et al. is questionable, we have also compared the above results to a recent work where a sample of galaxy clusters described by an elliptical profile was used in analysis.

Assessment of using digital manipulation tools for diagnosing mandibular radiolucent lesions

Objective: The purpose of this study was to analyse the use of digital tools for image enhancement of mandibular radiolucent lesions and the effects of this manipulation on the percentage of correct radiographic diagnoses. Methods: 24 panoramic radiographs exhibiting radiolucent lesions were selected, digitized and evaluated by non-experts (undergraduate and newly graduated practitioners) and by professional experts in oral diagnosis. The percentages of correct and incorrect diagnoses, according to the use of brightness/contrast, sharpness, inversion, highlight and zoom tools, were compared. All dental professionals made their evaluations without (T-1) and with (T-2) a list of radiographic diagnostic parameters. Results: Digital tools were used with low frequency mainly in T-2. The most preferred tool was sharpness (45.2%). In the expert group, the percentage of correct diagnoses did not change when any of the digital tools were used. For the non-expert group, there was an increase in the frequency of correct diagnoses when brightness/contrast was used in T-2 (p = 0.008) and when brightness/contrast and sharpness were not used in T-1 (p = 0.027). The use or non-use of brightness/contrast, zoom and sharpness showed moderate agreement in the group of experts [kappa agreement coefficient (kappa) = 0.514, 0.425 and 0.335, respectively]. For the non-expert group there was slight agreement for all the tools used (kappa <= 0.237). Conclusions: Consulting the list of radiographic parameters before image manipulation reduced the frequency of tool use in both groups of examiners. Consulting the radiographic parameters with the use of some digital tools was important for improving correct diagnosis only in the group of non-expert examiners. Dentomaxillofacial Radiology (2012) 41, 203-210. doi: 10.1259/dmfr/78567773

Probing the cosmic distance-duality relation with the Sunyaev-Zel'dovich effect, X-ray observations and supernovae Ia

Context. The angular diameter distances toward galaxy clusters can be determined with measurements of Sunyaev-Zel'dovich effect and X-ray surface brightness combined with the validity of the distance-duality relation, D-L(z)(1 + z)(2)/D-A(z) = 1, where D-L(z) and D-A(z) are, respectively, the luminosity and angular diameter distances. This combination enables us to probe galaxy cluster physics or even to test the validity of the distance-duality relation itself. Aims. We explore these possibilities based on two different, but complementary approaches. Firstly, in order to constrain the possible galaxy cluster morphologies, the validity of the distance-duality relation (DD relation) is assumed in the Lambda CDM framework (WMAP7). Secondly, by adopting a cosmological-model-independent test, we directly confront the angular diameters from galaxy clusters with two supernovae Ia (SNe Ia) subsamples (carefully chosen to coincide with the cluster positions). The influence of the different SNe Ia light-curve fitters in the previous analysis are also discussed. Methods. We assumed that eta is a function of the redshift parametrized by two different relations: eta(z) = 1 +eta(0)z, and eta(z) = 1 + eta(0)z/(1 + z), where eta(0) is a constant parameter quantifying the possible departure from the strict validity of the DD relation. In order to determine the probability density function (PDF) of eta(0), we considered the angular diameter distances from galaxy clusters recently studied by two different groups by assuming elliptical and spherical isothermal beta models and spherical non-isothermal beta model. The strict validity of the DD relation will occur only if the maximum value of eta(0) PDF is centered on eta(0) = 0. Results. For both approaches we find that the elliptical beta model agrees with the distance-duality relation, whereas the non-isothermal spherical description is, in the best scenario, only marginally compatible. We find that the two-light curve fitters (SALT2 and MLCS2K2) present a statistically significant conflict, and a joint analysis involving the different approaches suggests that clusters are endowed with an elliptical geometry as previously assumed. Conclusions. The statistical analysis presented here provides new evidence that the true geometry of clusters is elliptical. In principle, it is remarkable that a local property such as the geometry of galaxy clusters might be constrained by a global argument like the one provided by the cosmological distance-duality relation.

Quantification of cellular action fibers alignment from confocal microscopic images.

The cellular rheology has recently undergone a rapid development with particular attention to the cytoskeleton mechanical properties and its main components - actin filaments, intermediate filaments, microtubules and crosslinked proteins. However it is not clear what are the cellular structural changes that directly affect the cell mechanical properties. Thus, in this work, we aimed to quantify the structural rearrangement of these fibers that may emerge in changes in the cell mechanics. We created an image analysis platform to study smooth muscle cells from different arteries: aorta, mammary, renal, carotid and coronary and processed respectively 31, 29, 31, 30 and 35 cell image obtained by confocal microscopy. The platform was developed in Matlab (MathWorks) and it uses the Sobel operator to determine the actin fiber image orientation of the cell, labeled with phalloidin. The Sobel operator is used as a filter capable of calculating the pixel brightness gradient, point to point, in the image. The operator uses vertical and horizontal convolution kernels to calculate the magnitude and the angle of the pixel intensity gradient. The image analysis followed the sequence: (1) opens a given cells image set to be processed; (2) sets a fix threshold to eliminate noise, based on Otsu's method; (3) detect the fiber edges in the image using the Sobel operator; and (4) quantify the actin fiber orientation. Our first result is the probability distribution II(Δθ) to find a given fiber angle deviation (Δθ) from the main cell fiber orientation θ0. The II(Δθ) follows an exponential decay II(Δθ) = Aexp(-αΔθ) regarding to its θ0. We defined and determined a misalignment index α of the fibers of each artery kind: coronary αCo = (1.72 ‘+ or =’ 0.36)rad POT -1; renal αRe = (1.43 + or - 0.64)rad POT -1; aorta αAo = (1.42 + or - 0.43)rad POT -1; mammary αMa = (1.12 + or - 0.50)rad POT -1; and carotid αCa = (1.01 + or - 0.39)rad POT -1. The α of coronary and carotid are statistically different (p < 0.05) among all analyzed cells. We discussed our results correlating the misalignment index data with the experimental cell mechanical properties obtained by using Optical Magnetic Twisting Cytometry with the same group of cells.