Exposure computational models with voxel phantoms coupled to EGSnrc Monte Carlo code

In computational dosimetry of ionizing radiation, the energy deposited in radiosensitive organs and tissues is evaluated when an anthropomorphic simulator (phantom) is irradiated using Exposure Computational Models (ECMs). An ECM is a virtual scene with a phantom positioned mathematically relative to a radioactive source. The initial state includes information like the type of primary particle, its energy, starting point coordinates, and direction. Subsequently, robust Monte Carlo (MC) codes are used to simulate the particle's mean free path, interaction with the medium's atoms, and energy deposition. These are common steps for simulations involving photons and/or primary electrons. The GDN (Research Group on Numerical Dosimetry and the Research Group on Computational Dosimetry and Embedded Systems) has published ECMs with voxel phantoms irradiated by photons using the MC code EGSnrc. This work has led to specific computational tools development for various numerical dosimetry stages, including input file preparation, ECM execution, and result analysis. Since 2004, the GDN developed in-house applications like FANTOMAS, CALDose_X, DIP, and MonteCarlo. Certain previously used phantoms are reintroduced to provide historical context in the ECMs' production timeline, emphasizing additive modifications inherent in systematic theme studies. The dosimetric evaluations used the binary version of the MASH (Male Adult mesh) phantom, converted to the SID (Dosimetric Information System) text file type. This format has been used by the group since 2021 to couple a voxel phantom to the EGSnrc user code. The ECM included an environmental dosimetry problem simulation. Most of these tools are accessible on the GDN page (http://dosimetrianumerica.org)

COMPLEXIDADE RACIAL: mitos e realidades em duas freguesias de Salvador em 1775

A partir da análise minuciosa dos dados do Censo de 1775 sobre duas freguesias de Salvador (São Pedro e Penha), são colocados em questão cinco mitos dominantes sobre a escravidão no imaginário nacional: (1) o domínio total do trabalho escravo na sociedade; (2) uma sociedade formada apenas por senhores e escravos; (3) uma sociedade constituída, por um lado, por um segmento de dominantes e exploradores e, por outro, por dominados e explorados; (4) uma sociedade urbana segregada; (5) uma sociedade patriarcal, em que as mulheres eram submissas e economicamente subordinadas. Os resultados do censo, portanto, levantam novas questões para o entendimento da complexidade do nosso passado, o que ajuda a entender a manutenção das extremas desigualdades atuais, além de evidenciar a existência de diferenciações espaciais na cidade. PALAVRAS-CHAVE: escravos, libertos, agregados, freguesias, Salvador.RACIAL COMPLEXITY: myth and reality in two Salvador freguesias in 1775 Pedro de Almeida Vasconcelos The meticulous analysis of data from the Census of 1775 on two freguesias of Salvador (São Pedro and Penha), bring doubt to five dominant myths on slavery in the national imaginary: (1) the exclusivity of slave work in the society; (2) a society just formed by slave owners and slaves; (3) a society where, on one side, live a segment of dominant exploiters and, on the other, dominated explored people; (4) a segregated urban society; (5) a patriarchal society, in which women were submissive and economically subordinates. The results of the census, therefore, bring new subjects to understanding the complexity of our past, what helps to understand the maintenance of the extreme current inequalities, besides showing the existence of space differentiations in the city. KEYWORDS: slaves, freed men, agregados, freguesias, Salvador.COMPLEXITÉ RACIALE: mythes et réalités dans deux paroisses de Salvador en 1775 Pedro de Almeida Vasconcelos A partir de l’analyse minutieuse des données du recensement de 1775 concernant deux paroisses de Salvador (São Pedro et Penha) sont remis en question cinq mythes dominants à propos de l’esclavage dans l’imaginaire national: (1) l’exclusivité du travail esclave dans la société; (2) une société formée uniquement de seigneurs et d’esclaves; (3) une société constituée d’une part par un segment de dominants et d’exploiteurs et d’autre part de dominés et d’exploités; (4) une société urbaine ségréguée; (5) une société patriarcale où les femmes étaient soumises et subordonnées économiquement. Les résultats de ce recensement soulèvent donc de nouvelles questions pour la compréhension de la complexité de notre passé, ceci permet de comprendre le maintien d’extrêmes inégalités actuelles et de mettre aussi en évidence l’existence de différenciations spatiales dans la ville. MOTS-CLÉS: esclaves, personnes libres, domestiques, paroisses, Salvador. Publicação Online do Caderno CRH: http://www.cadernocrh.ufba.b

Development and validation of the MMCD score to predict kidney replacement therapy in COVID-19 patients

Abstract Background Acute kidney injury (AKI) is frequently associated with COVID-19, and the need for kidney replacement therapy (KRT) is considered an indicator of disease severity. This study aimed to develop a prognostic score for predicting the need for KRT in hospitalised COVID-19 patients, and to assess the incidence of AKI and KRT requirement. Methods This study is part of a multicentre cohort, the Brazilian COVID-19 Registry. A total of 5212 adult COVID-19 patients were included between March/2020 and September/2020. Variable selection was performed using generalised additive models (GAM), and least absolute shrinkage and selection operator (LASSO) regression was used for score derivation. Accuracy was assessed using the area under the receiver operating characteristic curve (AUC-ROC). Results The median age of the model-derivation cohort was 59 (IQR 47–70) years, 54.5% were men, 34.3% required ICU admission, 20.9% evolved with AKI, 9.3% required KRT, and 15.1% died during hospitalisation. The temporal validation cohort had similar age, sex, ICU admission, AKI, required KRT distribution and in-hospital mortality. The geographic validation cohort had similar age and sex; however, this cohort had higher rates of ICU admission, AKI, need for KRT and in-hospital mortality. Four predictors of the need for KRT were identified using GAM: need for mechanical ventilation, male sex, higher creatinine at hospital presentation and diabetes. The MMCD score had excellent discrimination in derivation (AUROC 0.929, 95% CI 0.918–0.939) and validation (temporal AUROC 0.927, 95% CI 0.911–0.941; geographic AUROC 0.819, 95% CI 0.792–0.845) cohorts and good overall performance (Brier score: 0.057, 0.056 and 0.122, respectively). The score is implemented in a freely available online risk calculator ( https://www.mmcdscore.com/ ). Conclusions The use of the MMCD score to predict the need for KRT may assist healthcare workers in identifying hospitalised COVID-19 patients who may require more intensive monitoring, and can be useful for resource allocation