Variability - Surface intensity distribution of large-area reference sources.

In this paper we present the impact of variability, a surface source parameter, on the efficiency evaluation of surface contamination monitors. This study was based on two source uniformity correction methodologies and data from real surface source distributions. Surface source intensity distribution has been changed by rearranging the cells (portions of the active area of each LARS) while keeping the same source uniformity value. Instrument efficiencies have been calculated for different sets of uniformities and variabilities. This study led to emphasize the importance of variability, a differential source intensity distribution parameter, over the uniformity, an integral source intensity distribution parameter, and reinforced the importance of the source uniformity correction procedure on the course of surface contamination monitor calibration.

Correction factors for non-uniform large-area reference sources.

Based on uniformity measurements of large-area reference sources used in calibration procedures of surface contamination monitors, an investigation was carried out to obtain a method that estimates the bias originated from surface source intensity distribution deviation from the ideal uniform distribution and corrects it. It relies on correcting the estimated instrument efficiency by applying correction factors driven from the uniformity distribution profiles of the sources used in calibration procedure. Simulations of the monitor calibration procedure are run for 2 distinct surface source distributions: the real and the ideally uniform distributions. Correction factors are driven from counting rate estimates obtained from each source representation. In order to evaluate adequacy of this proposition it was validated against a method proposed by the NPL in the Good Practices Guide No.14.

Synthesis and atomic scale characterization of Er2O3 nanoparticles: enhancement of magnetic properties and changes in the local structure.

In the investigation reported in this paper a modified thermal decomposition method was developed to produce very small Er2O3 nanoparticles (NPs). Particles structure, shape and size were characterized by x-ray diffraction and transmission electron microscopy which showed that the synthesis by thermal decomposition under O2 atmosphere produced very small and monodisperse NPs, allowing the investigation of finite-size and surface effects. Results of magnetization measurements showed that the smallest particles present the highest values of susceptibility that decrease as particle size increases. Specific heat measurements indicate that the sample with the smallest NPs (diameter ∼5 nm) has a Néel temperature of 0.54 K. The local structure of particles was investigated by measurements of hyperfine interactions with perturbed angular correlation spectroscopy using 111Cd as probe nuclei replacing the cationic sites. Results showed that the relative population of sites 8b increases in both the core and surface layer of particles.

Infestation of Brazilian Peridomiciliary Areas by Culicoides (Diptera: Ceratopogonidae) in Humid and Semihumid Climates.

This study investigates Culicoides infestation in peridomestic environments in two villages in Maranhão, one with hot and humid climate and the other with semihumid climate. We evaluated the composition, richness, abundance, and seasonality of species. We captured insects using CDC light traps installed in animal shelters once a month, from 6 pm to 6 am, for 24 mo (May 2012 to April 2014). In this study, 17 species were found. Of these, 10 occurred simultaneously in two areas; six were found only in hot and humid area, while one occurred only in the semihumid area. Species richness was higher in the hot and humid climate (16 species) than in the semihumid (11 species). The rank of abundance was uneven across areas: C. foxi, C. insignis, C. filariferus, C. ignacioi, and C. flavivenula were dominant in the hot and humid area, and C. ignacioi, C. foxi, C. filariferus, C. insignis, and C. boliviensis in the semihumid. Midges were more abundant in the rainy season in both areas. This result reveals a diversified fauna of midges, with variable abundance of rank according to the area, prevailing in the rainy season and in the Amazon area. It also highlights the need for health monitoring in order to contain the infestation by these insects in peridomestic environments, taking into account that some species can be effective vectors of arboviruses in the Amazon and northeastern Maranhão.

Evaluation of the voltage quantities measured with different noninvasive meters for quality control at a calibration laboratory.

In this work the peak kilovoltage (kVp), practical peak voltage (PPV) and air kerma rate were measured with the noninvasive meters Radcal Accu-kV® Diagnostic Sensor™ model 40×12-W, and PTW Diavolt. The results were compared in order to ensure the quality control, compare the meters and establish the new quantity PPV, at the Calibration Laboratory of IPEN. These tests were performed using the standard diagnostic radiology quality beam RQR5, and the results are in good agreement.

Molecular epidemiology of KPC-2- producing Klebsiella pneumoniae isolates in Brazil: the predominance of sequence type 437.

The aim of this study was to investigate the genetic relatedness of 57 KPC-2-producing Klebsiella pneumoniae isolates from 5 states in Brazil, during 2006-2009. Pulse-field gel electrophoresis analysis identified 10 pulsotypes. The pulsotype designated as Kp-RJ (Klebsiella pneumoniae-Rio de Janeiro) was the dominant clone found in the states of Rio de Janeiro and Espírito Santo. Multilocus sequence typing of Kp-RJ assigned it to ST 437. Sequence types ST11, ST16, ST25, ST70, ST101, ST105, ST423, ST442, and ST443 were also identified. These results indicate the dissemination of a successful KPC-producing clone (ST437) in Brazil, which is a single locus variant of ST258.

Development of an object test to dental image verification.

An object test was developed to verify the dental images best quality in relation to the exposition time. It consists of high purity perforated aluminum plates, with different thickness and dimensions of 3x4 cm. The plates were covered by acrylic, making its total thickness of 3.0 mm. It was irradiated together with the film from 0.1 to 0.5 s. The irradiation of 0.2 s showed the best image, reducing the regular time exposition by 0.3 s.

Myasthenia gravis in children: analysis of 18 patients

Myasthenia gravis (MG) in childhood is rare comprising 10 to 20 percent of all myasthenic patients. We studied 18 patients with MG whose first symptoms started from 1 to 12 years of age, followed at the Department of Neurology of the UNIFESP-EPM, from January 1983 to August 1997. There were 10 girls and 8 boys (1.2:1). Eleven patients (61 percent) presented moderate or severe generalized disease and 4 (22 percent) had at least one myasthenic crisis. EMG with supramaximal repetitive nerve stimulation was diagnostic in 8 (47 percent) out of 17 patients, and chest CT was normal in 14 patients. Seropositivity to acetylcholine receptor antibodies was found in 81.6 percent (9 out of 11 tested) and the levels had no relation to clinical severity. Nine out of 16 patients (56 percent) worsened with pyridostigmine alone and were treated with prednisone. Four out of those nine continued worsening despite steroids and were subjected to thymectomy (all showed thymic lymphoid follicular hyperplasia). Three patients (75 percent) improved markedly after thymectomy and one (25 percent) worsened, eventually getting better with intravenous immunoglobulin and oral azathioprine. MG treatment, using all resources available, has to be individualized for each child

Comportamento de monitores portáteis em feixes de radiaçäo X de baixas energias / Behavioral of portable monitors in low energy X-rays fields

No Laboratório de Calibração de instrumentos do IPEN os monitores portáteis são calibrados com radiação gama de (60)Co e (137)Cs; no entanto, sabe-se que muitos destes instrumentos são utilizados para medidas em campos de radiação X até mesmo na faixa em que apresentam dependência energética acentuada. Este trabalho consiste no estudo da resposta de monitores portáteis expostos a feixes de radiação X de baixas energias.