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RESUMO Objetivo: Descrever e analisar a prevalência de baixa acuidade visual e suas causas em estudantes do ensino público de Belo Horizonte/MG. Métodos: Estudo transversal de 1452 escolares de 5 a 19 anos, do ensino público de Belo Horizonte/MG, triados e atendidos entre 2011 e 2014. Resultados: Da amostra total, 150 pacientes (10,33%) apresentaram baixa acuidade visual à triagem, recebendo encaminhamento para atendimento oftalmológico. Quarenta (26,66%) foram encaminhados e compareceram à consulta, onde 29 (72,5%) apresentaram indicação de correção visual. O astigmatismo miópico simples e composto foram os diagnósticos mais relacionados à prescrição de óculos. Conclusão: O estudo mostrou que a prevalência de baixa acuidade visual na população estudada foi compatível com demais programas semelhantes. Em contrapartida, a taxa de abstenção foi maior do que o esperado, evidenciando a importância da criação de medidas preventivas e informativas quanto à importância do cuidado com a saúde ocular.

This study was undertaken to determine the effect of zircon content and firing temperature on the hardness and indentation modulus of zircon–glass composites obtained by sintering. A standard non-devitrified borosilicate glass (SRM 717a) powder and an industrial micrometric zircon powder were used to prepare mixtures with a zircon volume/solids volume between 0 and 0.63, by the wet method. The values of these mechanical properties were determined by nanoindentation and related to the most important microstructural characteristics of the composites, such as porosity, zircon volume fraction, glass volume fraction, and average zircon grain size. Composite mechanical performance was interpreted and determined by statistically analysing the results of a large number of indentations using two maximum loads. An empirical model was developed that describes the effect of these microstructural characteristics on composite hardness and modulus of indentation. Composites of high hardness (11.3 ± 2.5 GPa) and low porosity (ε = 0.07) were obtained at 1100 °C from a mixture with a zircon volume/solids volume of 0.43. [ABSTRACT FROM AUTHOR]

Many materials of a glass-ceramic nature are obtained by glass particle sinter-crystallisation, whose process kinetics have been studied very little. The present study analyses the physico-chemical transformations that develop during the firing of a complex commercial satin glaze (containing more than five phases), with high frit content, particularly focusing on sinter-crystallisation kinetics. Glaze sintering and phase evolution were studied by hot stage microscopy (HSM) and X-ray diffraction (XRD). The glaze melting and crystallisation ranges and the kinetic parameters of the crystallisation process were determined by differential thermal analysis (DTA). Glaze sinter-crystallisation behaviour and the development of the crystal mass fractions, residual glass compositions, and effective viscosity, η eff , during heating are discussed, based on Rietveld analysis of the XRD data. A new kinetic model was developed that describes the non-isothermal sinter-crystallisation of materials exhibiting three-stage sintering. A two-step kinetic model is involved: sintering with concurrent surface crystallisation (corresponding to sintering stages I and II) and sintering with simultaneous partial melting of crystalline phases (sintering stage III). The experimental data obtained by hot stage microscopy (HSM) at different heating rates were compared with those estimated by the model. The results obtained by the two methods exhibited very good agreement. The crystallisation kinetic parameters (activation energy, E cr , and Avrami index, n, obtained by DTA, were consistent with the viscous flow activation energy, Q 2 , corresponding to the first sintering step (sintering stages I and II). The model was used to calculate the values of the effective sintering viscosity, η s , of the glaze melt. These values were compared with the experimental effective viscosity, η eff , data obtained by hot stage microscopy (HSM). Both sets of results exhibited good agreement. Effective sintering viscosity, η s , which is readily measurable, helps better understand the role played by the different glaze constituents and by the firing conditions in sintering, enabling more rational design of these materials. [ABSTRACT FROM AUTHOR]

Libertarianism deals with what the law should be. In this article, we focus on what the appropriate law to punish criminals should be in a libertarian society; that is, one that respects the Non-Aggression Principle and property rights. We examine various theories of punishment and explain why some are incompatible with libertarianism. We contribute to the latest libertarian theory of punishment suggesting the necessity to take time preference into consideration. We conclude stating a limit and a limitation to libertarian punishment theories.

A structural model was developed to describe the shear-thinning behaviour of dense, stabilised suspensions of plate-like particles. The model is based on the following main assumptions: the particles are distributed in more or less compact layers, oriented parallel to the flow; the particles are assumed to behave as hard disks, disk thickness being the sum of crystal thickness plus twice the Debye length; when the shear stress increases, the orientation of the plate-like particles in the flow direction also increases, thus increasing layer compactness. In order to test the proposed model, a kaolin was selected and characterised. The kaolin was used to prepare more than 40 aqueous suspensions, modifying the solids volume fraction between ϕ = 0.20 and ϕ = 0.475 and the dispersant (sodium silicate) content between X s = 0.075 and X s = 0.225 mg dispersant/m 2 solid. The flow curves of all suspensions were determined in the quasi-steady state. The results confirmed the validity of the model to satisfactorily describe the combined effect of ϕ and X S on the flow curves in the shear-thinning range. [ABSTRACT FROM AUTHOR]

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This paper describes a methodology for the analysis of nitrogen by scanning electron microscope with an energy dispersive X-ray spectrometer (SEM-EDS). The methodology was developed to have a rapid and accurate alternative method to the elemental analysis by combustion and thermoconductivity detection that does not imply the decomposition of the sample. Two methods by SEM-EDS were established: a quantitative method trying to construct a calibration curve with reference materials and another using the standardless method provided with the instrument software, and the results were compared with those obtained by elemental analysis using two instruments that work at different temperature. An important matrix effect was found when trying to construct a calibration curve for SEM-EDS for any kind of material, being corrected when using the standardless method because this method corrects the matrix effect. The quantification of nitrogen by SEM-EDS is a good alternative to elemental analysis by combustion and thermoconductivity detection in those cases where the sample has a very high decomposition temperature. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Diabetic neuropathy is one of the most frequent complications in diabetes but there are no treatments beyond glucose control, due in part to the lack of an appropriate animal model to assess an effective therapy. This study was undertaken to characterize the degenerative and regenerative responses of peripheral nerves after induced sciatic nerve damage in transgenic rat insulin I promoter / human interferon beta (RIP/IFNbeta) mice made diabetic with a low dose of streptozotocin (STZ) as an animal model of diabetic complications. In vivo, histological and immunohistological studies of cutaneous and sciatic nerves were performed after left sciatic crush. Functional tests, cutaneous innervation, and sciatic nerve evaluation showed pronounced neurological reduction in all groups 2 weeks after crush. All animals showed a gradual recovery but this was markedly slower in diabetic animals in comparison with normoglycemic animals. The delay in regeneration in diabetic RIP/IFNbeta mice resulted in an increase in active Schwann cells and regenerating neurites 8 weeks after surgery. These findings indicate that diabetic-RIP/IFNbeta animals mimic human diabetic neuropathy. Moreover, when these animals are submitted to nerve crush they have substantial deficits in nerve regrowth, similar to that observed in diabetic patients. When wildtype animals were treated with the same dose of STZ, no differences were observed with respect to nontreated animals, indicating that low doses of STZ and the transgene are not implicated in development of the degenerative and regenerative events observed in our study. All these findings indicate that RIP/IFNbeta transgenic mice are a good model for diabetic neuropathy. [ABSTRACT FROM AUTHOR]

The technique, indications, and complications of diagnostic thoracoscopy are described. Two hundred and eight explorations have been performed in our service in the last seven years. From 137 pleural malignancies we have obtained an unequivocal positive biopsy in 129 (94%) with a minimum number of complications and no mortality. From our experience we conclude that thoracoscopy, when porperly performed, is diagnostic in most pleural conditions. [ABSTRACT FROM PUBLISHER]

Since 1970 we have stabilized the ribs to correct paradoxical movement of the chest wall in chest injuries, using an original technique, in order to avoid as far as possible the need for long-term chest wall stabilization by intermittent positive pressure respiration (IPPR). The technical details of surgical stabilization are described, and the different types of stainless steel struts are shown. Type I was originally used either as an intramedullary nail or as an external brace. Types II and III were designed for external fixation of the strut to the rib. Treatment of 29 patients with severe flail chest, classified into four groups is shown: group I was treated by IPPR, group II by IPPR plus surgical stabilization, group III by surgical stabilization only, and group IV by surgical stabilization after exploratory thoracotomy. The clinical results are discussed. We conclude that surgical stabilization of the paradoxial movement of the chest wall can avoid the use of the respirator or at least reduce the interval of IPPR to a short period during the initial recovery from trauma. Using type III struts, we have obtained stabilization of the flail chest in all cases even in patients with severe anterior paradoxical movement. The patients' tolerance of surgical stainless steel struts was good. [ABSTRACT FROM AUTHOR]

Up to December 1973, we had performed 100 mediastinoscopies for lung carcinoma. Fifty-two were positive and 48 negative. In 80 cases there was clinical or radiological suspicion of mediastinal invasion. With radiological evidence of mediastinal node involvement exploration was positive in 32 out of 35 cases, when chest radiography findings were equivocal in 19 out of 45, and when radiology of the mediastinum was normal in only one of 20 cases. Mediastinoscopy was more frequently positive when the carcinoma was oat-cell or anaplastic. Of 48 patients with negative biopsies, 41 were explored. In 26 the carcinoma extended beyond the lung. In 1973 we circularized 83 thoracic surgeons concerning (1) the use of mediastinoscopy for patients with lung carcinoma assessed for surgery, (2) the significance of mediastinal node involvement, (3) the results of radiotherapy alone in patients rejected for surgery, and (4) the survival rate in patients with positive mediastinal nodes treated with surgery alone or together with radiotherapy. The replies to the questionnaire are summarized. The authors emphasize the usefulness of mediastinoscopy but state that care must be taken when deciding to withhold operation for a possible cure. [ABSTRACT FROM PUBLISHER]

, , 631-636. Nine patients with Margagni's hernia of the diaphragm are reported, seven of whom have been operated on. Four patients had gastrointestinal symptoms, two respiratory symptoms, and one retrosternal pain; the other two were asymptomatic. In the first case the diagnosis was made at the time of thoracotomy, in the other eight it was suggested by radiological studies. The standard midline epigastric incision was used for repair in four cases and thoracotomy in two; the last patient was operated on through a preperitoneal subxiphoid route. This route has the advantage of not requiring a wide incision of peritoneum. [ABSTRACT FROM PUBLISHER]