26 research outputs found
Modelagem computacional da circulação natural do CO2 supercrítico
Passive safety systems for residual heat removal through natural circulation are indispensable for the future of nuclear energy. In an attempt to optimize such systems, the use of supercritical CO2 is an alternative considered by many researchers due to the high rates of heat transfer and low pressure drop. This work aims to investigate one of the main intrinsic limitations of this system type, the phenomenon of heat transfer deterioration (HTD). The four most common configurations of a rectangular natural circulation loop were analyzed, differed by the orientation of the heater and the cooler. The simulations were performed in steady state, using a three-dimensional model. The turbulence model chosen was RNG k-ε. The code used was ANSYS Fluent v. 18.2. The natural circulation mass flowrate and the average temperature were analyzed as a function of the heating power for the four loop configurations and for three pressures (8.5 MPa, 9.0 MPa and 9.5 MPa). The results were compared with the empirical correlations of SWAPNALEE et al. [1] and YADAV et al. [2] in order to verify the simulation. The HTD regime was observed for all the cases studied. It was observed that the increase in pressure delays the beginning of HTD regime and also induces a significant increase in the natural circulation flowrate after the emergence of HTD for all studied cases. In order to investigate the heat transfer of the system, the Nusselt number was analyzed as a function of the Rayleigh number and it was observed that the correlation described by YADAV et al. [2] presented good agreement with the results obtained from the simulation. Finally, correlations were proposed for the heat transfer and the Reynolds number, individually for each configuration, and a unified correlation was proposed for the friction factor, for all the cases studied.Sistemas passivos de remoção de calor residual por circulação natural são indispensáveis para o futuro da energia nuclear. Na tentativa de otimizar estes sistemas, a utilização do CO2 supercrítico é uma alternativa considerada por muitos pesquisadores devido às altas taxas de troca térmica e baixa perda de carga. Este trabalho visa investigar uma das principais limitações intrínsecas deste tipo de sistema, o fenômeno da deterioração da transferência de calor (HTD). Foram analisadas as quatro configurações mais comuns de um circuito de circulação natural retangular, que diferem-se pela orientação do aquecedor e do resfriador. As simulações foram realizadas em estado estacionário, empregando um modelo tridimensional. O modelo de turbulência escolhido foi o RNG k-ε. O código utilizado foi o ANSYS Fluent v. 18.2. A vazão de circulação natural e a temperatura média foram analisadas em função da potência de aquecimento para as quatro configurações do circuito e para três diferentes pressões de operação (8,5 MPa, 9,0 MPa e 9,5MPa). Os resultados foram comparados com as correlações empíricas de SWAPNALEE et al. [1] e YADAV et al. [2] com intuito de verificar a simulação. O regime de HTD foi observado para todos os casos estudados. Observou-se que o aumento da pressão de operação retarda o surgimento do regime da HTD e também induz um sensível aumento na vazão de circulação natural após o início da HTD, para todos os casos estudados. Com o intuito de investigar a transferência de calor do sistema, o número de Nusselt foi analisado em função do número de Rayleigh e observou-se que a correlação descrita por YADAV et al. [2] apresentou boa concordância com os resultados obtidos da simulação. Por fim, foram propostas correlações para a transferência de calor e para o número de Reynolds, individualmente para cada configuração, e uma correlação para o fator de atrito, para todos os casos estudados
Contracepção hormonal e lesões cervicais pelo Papilomavírus Humano: uma revisão de literatura / Hormonal contraception and cervical injuries by Human Papillomavirus: a literature review
Introdução: A infecção pelo papilomavírus humano (HPV) é a doença sexualmente transmissível (DST) mais comum, afetando 50% da população mundial. Estima-se que entre 75 e 80% da de indivíduos sexualmente ativos adquirirão algum subtipo de HPV ao longo da vida. No Brasil, a taxa de prevalência de HPV varia de 13,7 a 54,3%, de acordo com a população e as regiões estudadas. Assim, este artigo tem como objetivo analisar a associação entre os hormônios contracepção e o aparecimento de lesões induzidas por HPV em o colo uterino. Metodologia: O presente estudo foi elaborado por meio de uma pesquisa bibliográfica, realizada eletronicamente, procurando registros sobre o desenvolvimento de lesões induzidas por HPV em colo uterino e hormônios de contracepção. Objetivando com isso identificar através da literatura a associação entre os hormônios de contracepção e o aparecimento de lesões induzidas por HPV em colo uterino. Para a realização do mesmo foram analisados artigos publicados em revistas científicas, utilizando as bases de dados da BVS (Biblioteca Virtual da Saúde), como: Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde) e Scielo (Scientific Electronic Library Online). Resultados: Após a seleção, restaram nove artigos para a discussão. Podemos observar os artigos escolhidos no quadro, composto pelos autores, título, metodologia, resultados e conclusão que cada um encontrou. Em seguida foi realizada uma discussão acerca destes artigos. Conclusão: Muitos estudos relataram que os mecanismos envolvidos na persistência e incidência de lesões de HPV estão longe de ser esclarecidas, e que novas estudos são necessários para elucidar melhores abordagens em relação ao tipo de contracepção, via de administração e doses hormonal que não estão associadas a lesões induzidas por HPV
A evolução clínica do paciente portador de abscesso pulmonar: Clinical evolution of patients with lung abscess
Atualmente, com a era da antibioticoterapia e demais meios terapêuticos, o abscesso pulmonar decaiu em termos de morbimortalidade, mas ainda permanece como um desafio em termos diagnósticos e manejo clínico. O abscesso pulmonar corresponde a uma cavidade com pus no pulmão, envolvido por tecido inflamado e geralmente oriunda de uma infecção. O artigo objetivou descrever de modo narrativo a evolução clínica do portador de abscesso pulmonar, ressaltando os principais dados para a compreensão deste fenômeno. Um abscesso pulmonar é causado principalmente por bactérias existentes na boca ou garganta, a qual são aspiradas até os pulmões. A sintomatologia é inespecífica, abordando fadiga, inapetência, sudorese noturna, febre, perda ponderal e tosse com expectoração. O quadro clínico geralmente necessita do complemento de exames de imagem, principalmente a radiografia torácica para diagnóstic
Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions
Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil
The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others
Recommended from our members
Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation
Simulação e desenvolvimento dos ecoindicadores do processo de produção de acetato de metila e dimetil éter a partir do metanol
Dentro do cenário socioeconômico atual, orientado para o desenvolvimento sustentável, este trabalho tem como objetivo a análise dos ecoindicadores de consumo de energia e de emissão de CO2 de três processos industriais: a produção de dimetil éter a partir do metanol, a produção de acetato de metila a partir de dimetil éter e a produção de acetato de metila a partir de metanol. Os dois primeiros são reportados na literatura por Diemer e Luyben (2010) e o terceiro é proposto através da integração dos dois primeiros. Para uma representação mais fiel da realidade industrial, plantas de utilidades para geração de vapor e água de refrigeração foram desenvolvidas. O software UNISIM R390 foi utilizado para a simulação dos processos e os resultados foram satisfatórios, em conformidade com os apresentados na literatura. Dentre as plantas analisadas o processo de produção de acetato de metila a partir de dimetil éter apresentou os ecoindicadores mais baixos. A planta integrada apresentou o ecoindicador de consumo de energia igual a 4,0027 GJ por tonelada de produto e o de emissão de CO2 igual a 0,2256 toneladas de CO2 por tonelada de produto. Os resultados dos ecoindicadores contribuem para a análise de ecoeficiência dos processos estudados e na elaboração de melhorias de projetos, a fim de obter maiores ganhos econômicos com menores impactos ambientaisWithin the current socio-economic scenario, driven by sustainable development, this paper aims to analyse energy consumption and CO2 emission eco indicators of three industrial processes: the production of dimethyl ether from methanol, the production of methyl acetate from dimethyl ether and the production of methyl acetate from methanol. The first two processes are reported in the literature by Diemer and Luyben (2010) and the third one is proposed by the integration of the first two processes. In order to have a more realistic industrial representation, utilities systems were developed to generate steam and cooling water. In the simulation, the software used was UNISIM R390 and the results were satisfactory in accordance with the literature. Among the three analysed processes, the production of methyl acetate from dimethyl ether showed the lowest eco indicators. The integrated methyl acetate plant revealed an energy consumption eco indicator of 4.0027 GJ per tonne of product and a CO2 emission eco indicator of 0.2256 tonne of CO2 per tonne of product. The eco indicator results contribute to eco-efficiency analysis of the studied processes and also to the development of projects in order to have better economic results and lower environmental impact
AMAZONIA CAMTRAP: A data set of mammal, bird, and reptile species recorded with camera traps in the Amazon forest
The Amazon forest has the highest biodiversity on Earth. However, information on Amazonian vertebrate diversity is still deficient and scattered across the published, peer-reviewed, and gray literature and in unpublished raw data. Camera traps are an effective non-invasive method of surveying vertebrates, applicable to different scales of time and space. In this study, we organized and standardized camera trap records from different Amazon regions to compile the most extensive data set of inventories of mammal, bird, and reptile species ever assembled for the area. The complete data set comprises 154,123 records of 317 species (185 birds, 119 mammals, and 13 reptiles) gathered from surveys from the Amazonian portion of eight countries (Brazil, Bolivia, Colombia, Ecuador, French Guiana, Peru, Suriname, and Venezuela). The most frequently recorded species per taxa were: mammals: Cuniculus paca (11,907 records); birds: Pauxi tuberosa (3713 records); and reptiles: Tupinambis teguixin (716 records). The information detailed in this data paper opens up opportunities for new ecological studies at different spatial and temporal scales, allowing for a more accurate evaluation of the effects of habitat loss, fragmentation, climate change, and other human-mediated defaunation processes in one of the most important and threatened tropical environments in the world. The data set is not copyright restricted; please cite this data paper when using its data in publications and we also request that researchers and educators inform us of how they are using these data