393 research outputs found

    Dos raios X à bomba atômica (1895-1945): os 50 anos que mudaram o mundo.

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    Wilhelm Conrad Röntgen e a descoberta dos raios X; Philipp Lenard: uma figura singular de cientista e de nacional-socialista; Antoine Henri Becquerel e a descoberta da radioatividade; A descoberta do elétron; Maria Sklodowska Curie e a descoberta da radioatividade natural; James Chadwick e a descoberta do nêutron; Frédéric Joliot e Irène Curie: a descoberta da radioatividade artificial; Da radioatividade artificial à fissão nuclear; A física durante o nazifascismo; Werner Heisenberg: um gênio da física teórica, mas também uma personalidade controvertida; A fundação da física na Universidade de São Paulo (USP); Leo Szilàrd: uma figura singular de cientista; A "corrida" para a bomba atômica; Conceitos básicos de física atômica e nuclear; Urânio: um protagonista involuntário na história da física nuclear; Cronologia dos acontecimentos que levaram à bomba atômica; A bomba atômica soviética; A bomba atômica japonesa; Breves biografias dos maiores cientistas da física nuclear do século 20; Instituições e siglas citadas

    Combined use of coenzyme Q10 and citicoline: A new possibility for patients with glaucoma

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    Glaucoma is the leading cause of irreversible blindness worldwide. Several risk factors have been involved in the pathogenesis of the disease. By now, the main treatable risk factor is elevated intraocular pressure. Nevertheless, some patients, whose intraocular pressure is considered in the target level, still experience a progression of the disease. Glaucoma is a form of multifactorial ocular neurodegeneration with complex etiology, pathogenesis, and pathology. New evidence strongly suggests brain involvement in all aspects of this disease. This hypothesis and the need to prevent glaucomatous progression led to a growing interest in the pharmacological research of new neuroprotective, non-IOP-lowering, agents. The aim of this paper is to report evidence of the usefulness of Coenzyme Q10 and Citicoline, eventually combined, in the prevention of glaucomatous neurodegeneration

    Tomografia por impedância elétrica e seus possíveis usos na agropecuária.

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    Construction of an Immigrant Integration Composite Indicator through the Partial Least Squares Structural Equation Model K-Means

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    Integration is a multidimensional process, which can take place in different ways and at different times in relation to each of the single economic, social, cultural, and political dimensions. Hence, examining every single dimension is important as well as building composite indexes simultaneously inclusive of all dimensions in order to obtain a complete description of a complex phenomenon and to convey a coherent set of information. In this paper, we aim at building an immigrant integration composite indicator (IICI), able to measure the different aspects related to integration such as employment, education, social inclusion, active citizenship, and on the basis of which to simultaneously classify territorial areas such as European regions. For this application, the data collected in 274 European regions from the European Social Survey (ESS), Round 8, on immigration have been used

    Lindane and Endosulfan Sulfate Isomers in Crassostrea virginica (Gmelin, 1791) Oyster Populations in Lagoon Systems from Central Gulf of Mexico

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    The aim of this study was to determine Lindane and Endosulfan Sulfate isomers in Crassostrea virginica oyster populations (Gmelin, 1791) in the Mandinga and Alvarado lagoon systems located in the central Gulf of Mexico. Samples were taken from the main oyster banks of each lagoon system, during the three representative seasons of the region, wet, dry and north winds. By means of free diving, 30 commercial size oysters (7 ± 3 cm) were collected in four oyster banks or stations of the Mandinga lagoon system, totaling 360 organisms, while in the Alvarado lagoon system there were a total of 90 oysters during the annual cycle. Concentration of lindane and endosulfan sulfate isotopes in C. virginica was performed with a gas chromatograph (Thermo Electron Model Trace GC Ultra 115V, Thermo Fisher Scientific Inc©, Monterrey, Nuevo León, México) with an Electron capture detector. Results showed that in the Alvarado Lagoon system mean concentrations of C. virginica oysters for lindane pesticide were 4.11 ± 3.83 ng⋅g-1, whereas for the Mandinga lagoon system, were 8.69 ± 5.15 ng⋅g-1. Endosulfan sulfate showed the highest average concentration in the Mandinga lagoon system with 24.68 ± 1.20 ng ⋅g-1. In addition, the endosulfan sulfate presents differences in its spatial distribution; high concentration levels in the Mandinga lagoon system whereas the lindane heterogeneity at all sampling points in both lagoons. Values of concentrations and relationships between compounds suggest recent contributions that could correspond to the excessive fluctuations of water discharged into the lagoon caused by the atypical rains of the year of sampling. It was concluded that endosulfan sulfate and lindane show concentration in all the points of sampling in both lagoons

    Subclinical signs of retinal involvement in hereditary angioedema

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    To explore retinal abnormalities using spectral domain optical coherence tomography (SD‐OCT) and OCT‐angiography (OCT‐A) in a highly selective cohort of patients with type I hereditary angioedema (HAE). This prospective case‐control study included 40 type I HAE patients and 40 age‐/sex‐matched healthy subjects (HC). All participants underwent SD‐OCT‐scanning of retinal posterior pole (PP), peripapillary retinal nerve fiber layer (pRNFL), and optic nerve head (ONH). Superficial/deep capillary density was analyzed by OCT‐A. A total of 80 eyes from 40 HAE and 40 eyes from HC were evaluated. The pRNFL was thicker in HAE than in HC in nasal superior (p < 0.0001) and temporal quadrants (p = 0.0005 left, p = 0.003 right). The ONH thickness in HAE patients was greater than in HC in the nasal (p = 0.008 left, p = 0.01 right), temporal (p = 0.0005 left, p = 0.003 right), temporal inferior (p = 0.007 left, p = 0.0008 right), and global (p = 0.005 left, p = 0.007 right) scans. Compared to HC, HAE showed a lower capillary density in both superficial (p = 0.001 left, p = 0.006 right) and deep (p = 0.008 left, p = 0.004 right) whole images, and superficial (p = 0.03 left) and deep parafoveal (p = 0.007 left, p = 0.005 right) areas. Our findings documented subclinical retinal abnormalities in type I HAE, supporting a potential role of the retinal assessment by SD‐ OCT/OCT‐A as a useful tool in the comprehensive care of HAE patients

    Efficacy of radiofrequency ablation in autonomous functioning thyroid nodules. A systematic review and meta-analysis

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    Whether thermal ablation is effective to treat toxic thyroid nodules (TTN) is still unknown. Aim of this review was to achieve more robust evidence on the efficacy of radiofrequency ablation (RFA) in treating TTN in terms of TSH normalization, thyroid scintiscan, and volume reduction rate (VRR). A comprehensive literature search of PubMed/Medline and Scopus was performed in November 2018 to retrieve published studies. Original papers reporting TTN treated by RFA and later followed-up were eligible. Excluded were: articles not within this field, articles with unclear data, overlapping series, case/series reports. Discordances were solved in a final collegial meeting. Information was collected concerning population features, treatment procedure, follow-up, cases with TSH normalization, cases with scintiscan normalization, VRR of nodules. Pooled prevalence of patients with TSH or scintiscan normalization, and pooled VRR over time were calculated. For statistical analysis, the random-effects model was used. Eight articles published between 2008 and 2018 were included. The overall number of AFTN treated by RFA was 205. Five studies used a single session of treatment. The time of follow-up ranged from six to 24 months. The pooled rate of patients with TSH normalization was 57%. The pooled rate of patients with scintigraphically proven optimal response was 60%. The pooled VRR at 1 year was 79%. Baseline nodules volume was associated with the rate of TSH normalization. In conclusion, a moderate efficacy of RFA in treating TTN was found, and this can represent a solid starting point in this field

    Differential X-ray attenuation in MA-XRF analysis for a non-invasive determination of gilding thickness

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    When investigating gilded artifacts or works of art, the determination of the gilding thickness plays a significant role in establishing restoration protocols or conservation strategies. Unfortunately, this is done by cross-sectioning the object, a destructive approach not always feasible. A non-destructive alternative, based on the differential attenuation of fluorescence radiation from the sample, has been developed in the past years, but due to the intrinsic random nature of X-rays, the study of single or few spots of an objects surface may yield biased information. Furthermore, considering the effects of both porosity and sample inhomogeneities is a practice commonly overlooked, which may introduce systematic errors. In order to overcome these matters, here we propose the extrapolation of the differential-attenuation method from single-spot X-ray fluorescence (XRF) measurements to macro-XRF (MA-XRF) scanning. In this work, an innovative algorithm was developed for evaluating the large amount of data coming from MA-XRF datasets and evaluate the thickness of a given overlapping layer over an area. This approach was adopted to study a gilded copper-based buckle from the sixteenth to seventeenth century found in Rome. The gilded object under investigation was also studied by other analytical techniques including scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Previous results obtained from SEM-EDS were used to confront the data obtained with the proposed methodology and validate it. MA-XRF elemental distribution maps were fundamental in identifying and choosing sampling areas to calculate the thickness of the gilding layer, avoiding lead islands present in the sample that could negatively influence the results. Albeit the large relative standard deviation, the mean thickness values fell within those found in literature and those obtained from previous studies with SEM-EDS. Surface fissure has been found to deeply affect the results obtained, an aspect that is often disregarded
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