Multiscale streamflow forecasts for the Brazilian hydropower system using bayesian model averaging (BMA)

O uso de sistemas eficientes de previsão de afluências nas diversas escalas temporais permite otimizar a operação do conjunto de reservatórios hidrelétricos brasileiros, elevando o grau de segurança no fornecimento de energia elétrica e minimizando os custos operacionais. Entretanto, os modelos atuais de previsão utilizados pelo Operador Nacional do Sistema Elétrico (ONS) tendem a ser limitados no horizonte de previsão e na modelagem da dependência existente entre as diversas escalas de tempo, reduzindo a qualidade das previsões. Neste trabalho é proposta uma nova contribuição para os modelos de previsão de afluências em uso pelo ONS a partir do conceito de ponderação bayesiana de modelos (BMA), que permite integrar previsões mensais e semanais de vazões com objetivo de melhorar o desempenho das previsões semanais. As previsões mensais são obtidas por meio de um modelo periódico auto-regressivo exógeno (PARX), que busca captar a persistência das vazões na parte auto-regressiva e a contribuição do escoamento superficial na parcela exógena por meio do uso de informações climáticas de larga escala. Previsões semanais de afluência com até seis semanas de antecedência são obtidas a partir das informações disponibilizadas pelo ONS nos relatórios do Programa Mensal de Operação (PMO). A metodologia proposta é aplicada em séries de afluências semanais aos 28 principais reservatórios hidroelétricos brasileiros. Os resultados de previsão semanal de afluências obtidos com a ponderação das saídas dos modelos de previsão semanal e mensal indicam uma melhoria significativa em indicadores de desempenho de previsões (NS, MAPE e DM) quando comparados com os resultados de previsão oriundos do modelo semanal isolado. Os ganhos obtidos nos indicadores de desempenho são mais significativos a partir da segunda semana de antecedência. A abordagem proposta é flexível em termos de implementação, permitindo integrar outras escalas de previsão assim como diferentes modelos preditivos (por exemplo, modelos de base física).The use of efficient streamflow forecast systems at different time scales allows the operational optimization of the Brazilian interconnected hydropower reservoirs, raising the security level of electricity supply and minimizing operating costs. However, current forecasting models used by the National Electric System Operator (ONS) tend to be limited over the forecast horizon and in the modeling of the dependence structure across the various time scales, thus reducing the quality of forecasts. This paper proposes a new contribution to the streamflow forecast models by exploring the concept of Bayesian Model Averaging (BMA), which allows integrating weekly and monthly forecasts in order to improve the skill of weekly predictions. The monthly forecasts are obtained from a periodic auto-regressive exogenous model (PARX), which attempts to capture the persistence of flow in the auto-regressive part and the runoff contribution in the exogenous portion through the use of climate information. Weekly streamflow forecasts with up to six weeks lead time are obtained from information made available by ONS in the Monthly Operational Program (PMO) reports. The proposed methodology is tested using weekly inflow series from the 28 major Brazilian hydropower reservoirs. The weekly streamflow forecasts results obtained from the weighting of the outputs from the weekly and monthly models indicate a significant improvement in skill based on common performance indicators (NS, MAPE and DM) when compared with forecasts derived from the isolated weekly model. The gains in performance indicators are more significant for lead times beyond two weeks. The proposed approach is flexible in terms of implementation, allowing the incorporation of the other forecast scales as well as different forecast models (e.g. physical models)

Influences of soil pH on cadmium toxicity to eight plant species

Soil pollution by heavy metals affects soil quality worldwide. Cadmium (Cd) is of special concern because it might transfer from soil to plants, especially under acidic conditions, causing toxicity. This work aimed to evaluate the LC50 (lethal concentration to 50% of studied population), NOEC (no observed effects concentration) and LOEC (lowest observed effects concentration), by measuring the germination and growth of eight plant species (Beta vulgaris, Daucus carota, Lactuca sativa, Phaseolus vulgaris; Avena strigosa, Oryza sativa, Triticum aestivum and Zea mays) in soil under increasing Cd concentrations (0, 10, 40, 80, 160, and 320 mg kg-1) and two levels of acidity. Increasing the soil pH (from 4.1 to 6.4) by liming alleviated Cd toxicity and had a positive impact on seedling growth of all plant species studied. Germination was a less responsive endpoint and only the most sensitive species (L. sativa, B. and D. carota) were affected under the most acidic condition. These results were confirmed by the lower values found for LOEC and LC50 in these species regardless of the soil pH. Sensitive species are thus recommended as indicators of soil contamination in ecotoxicological studies, in which dicotyledonous species (e. g. L. sativa and B. vulgaris) are more suitable for risk assessments in Cd-contaminated soils at low concentrations, whilst monocotyledons (e. g. Z. mays) are more adequate for higher Cd concentrations (≥ 80 mg kg-1). Increasing soil pH by liming was demonstrated to be an efficient method in alleviating Cd toxicity in seedling growth

TESTANDO A HIPÓTESE DE EFICIÊNCIA DE MERCADO POR MEIO DE REDES NEURAIS ARTIFICIAIS: UM ESTUDO DE CASO COM AS DEZ PRINCIPAIS AÇÕES DO IBOVESPA DO PRIMEIRO QUADRIMESTRE DE 2011

Fuel market is facing political, economic, social and environmental problems that are fuzzing the future of fossil energy sources and in face of these facts, countries are looking for hybrid and electric vehicles as part of solution in transportation sector due to the fact of electric vehicles use few or no fossil fuel. The objective in this article was to identify options until 2020 to introduce electric vehicle in the urban traffic of São Paulo city and to develop this study the method of literature review in secondary sources was used to present electric vehicle technologies and to identify parameters that were assessed through morphological analysis technique. In morphological analysis, sets of values were defined by the author for these parameters, possible combinations were structured, clearly impractical deployment options before 2020 were discarded and some viable solutions were analyzed in details. These analyses concluded that there are viable options for actual days in São Paulo city, but important requirements regarding technology, politic, market, infrastructure and innovation in products and services still need to be addressed and it is the main reason of electric vehicle remain unnoticed by consumers as an viable option. The challenges are great and the actors who are willing to solve them will find a promising market to explore.Este artigo tem como objetivo analisar se a ferramenta de Marangoni (2010) a partir de uma rede neural artificial (RNA) tem relação com a hipótese de eficiência de mercado para a tomada de decisão de investimentos no mercado de ações. O presente estudo utilizou as dez ações mais importantes que faziam parte do Ibovespa no primeiro quadrimestre do ano de 2011. O estudo será dividido em três etapas. A primeira consiste em revisar a literatura específica que aborda as questões do ambiente da gestão financeira no que tange aos investimentos em bolsa de valores e seus instrumentos de avaliação. A segunda etapa consiste na aplicação do modelo nos papéis selecionados para finalmente se realizarem as análises e devidas considerações. Conclui-se que a ferramenta de redes neurais artificiais convergiu, em 50% dos papéis em termos de previsão, para a hipótese de eficiência de mercado. O papel sugerido como opção de compra, que maximiza a rentabilidade por parte do investidor pela RNA, foi igual ao papel indicado com base na hipótese de mercado eficiente. O mesmo ocorre com o papel menos rentável. Ao comparar com o que aconteceu, nota-se que a primeira decisão seria acertada e a última é pouco distorcida em relação ao que ocorreu. A pesquisa é predominantemente quantitativa. O estudo se faz importante uma vez que atualmente existem poucos estudos que comprovam o funcionamento das RNAs para previsão de série temporal no mercado acionário

Cadmium stress causes differential effects on growth and the secretion of carbon-degrading enzymes in four mycorrhizal basidiomycetes

We hypothesised that cadmium exposure would hinder growth and secretion of carbon-degrading enzymes by mycorrhizal fungi, and that this would vary according to their tolerance to cadmium stress. The enzymes measured were β-Glucosidase, β-Xylosidase, β-D-cellubiosidase, N-acetyl-β-Glucosaminidase in three strains of ectomycorrhizal fungi Hebeloma subsaponaceum, Scleroderma sp., Hebeloma sp. and a feremycorrhizal fungus Austroboletus occidentalis. Fungi were subjected to cadmium stress for 28 d (in modified Melin-Norkrans liquid medium). The results showed unanticipated differential response of enzyme activities among the fungal species, including potential hormesis effects. Austroboletus occidentalis showed an increase in enzyme activity under cadmium stress

Mycorrhizal symbiosis induces divergent patterns of transport and partitioning of Cd and Zn in Populus trichocarpa

We investigated how arbuscular mycorrhizal symbiosis can alter trace element uptake, distribution and toxicity in plants by examining some of the molecular mechanisms behind Populus trichocarpa tolerance to Cd and Zn, and the effects of AMF in metal homeostasis. Plants were grown under Cd and Zn contamination, with and without Rhizophagus irregularis inoculation. We determined organ metal concentrations, the expression of genes involved in trace element homeostasis, and the function of metallothionein PtMT2b by heterologous expression in yeast. P. trichocarpa was highly tolerant to both elements, with AMF increasing Zn accumulation. AMF altered the partitioning of Cd, but maintained the same patterns for Zn, indicating that despite being geochemically similar and carried mostly by the same transporters, the nutrient metal (Zn) is handled differently from the non-essential metal (Cd). High Zn and Cd down-regulated PtHMA4 (roots), and up-regulated PtZIP1 (leaves), suggesting their involvement in transporting both metals in poplar. PtMT2b was highly up-regulated in mycorrhizal roots and enhanced Cd tolerance in transformed yeast. R. irregularis reduced Cd transfer to poplar shoots, but did not affect Zn partitioning. The gene expression patterns observed offer a glimpse into the mechanisms behind trace element uptake/translocation dynamic in poplars, influenced by AMF symbiosis

Study of association models for determining the growth of the fleet of motor vehicles in the Metropolitan Region of Cariri, Ceará

The quality of life underlying the modern society can be attributed to several factors, among them, the technological and economic development experienced in recent years. Durable consumer goods are part of this modern society, such as automobiles. However, because most automobiles are powered by the combustion of fossil fuels, the emission of greenhouse gases is a worrisome environmental problem. The objective of this article is to analyze Gross Domestic Product (GDP) data, population and SELIC rate (SELIC stands for Special System of Settlement and Custody) in the period from 2001 to 2020 to evaluate the impact on the number of vehicles in the Cariri Metropolitan Region (RMC), using multivariate models. It was verified that the fleet of the RMC experienced an increase of 561.45% in the last 20 years. Three prediction models were tested and the conclusion was reached that for the next 20 years it is not sustainable to maintain the same growth already experienced, in a linear manner. Instead, the ideal is to adopt a model with growth forecast with a logarithmic function, i. e. with a stationary tendency in the long time. In a society where over 50% of vehicles are more than 10 years old, it is essential that public managers, the private initiative, the academic-scientific environment and society adopt sustainable practices and consider future scenarios to make decisions in order to preserve the environment and to ensure everyone\u27s quality of life

Is the relative age effect prevalent in elite Brazilian male futsal? An investigation based on age categories and playing positions

This study aimed to investigate the existence of relative age effect (RAE) in male Brazilian futsal athletes according to age categories and playing position. Data from male futsal athletes from the top five teams in Brazil were collected during May and June 2021. The distribution of birth dates of 387 male futsal athletes was analyzed, based on their age categories (U15, n = 97; U17, n = 88; U20, n = 116; senior, n = 86) and playing positions (defender, n = 76; winger; n = 162; pivot, n = 69; goalkeeper, n = 80). Chi-squared tests were used to analyze the birth dates distribution based on quarter and semesters of the year according to age categories and playing positions. The overall analysis of birth quarter indicated a higher occurrence of births in the first quarter of the year (p<.001; V = 0.188). The age categories analysis indicated a uniform distribution in U15 (p=.09; V = 0.15) and unequal distributions in U17 (p<.001; V = 0.29), U20 (p<.007; V = 0.19) and senior (p<.01; V = 0.21) categories. The playing position analysis indicated a uniform distribution for the pivots (p=.11; V = 0.17) and unequal distribution for goalkeepers (p<.04; V = 0.19), wingers (p<.002; V = 0.19) and defenders (p<.002; V = 0.27). We concluded that RAE was present in Brazilian elite men’s futsal, especially in the U17, U20, and senior categories, and goalkeepers, wingers, and defenders. Our results reinforce the need to consider the effects of relative age in the development of Brazilian elite futsal players

Estudo in vivo da toxicidade e citotoxicidade de biocerâmicos de nanohidroxiapatita e nanotubos de carbornos funcionalizado com óxido de grafeno / In vivo study of the toxicity and cytotoxicity of nano-hydroxyapatite and carbon nanotubes functionalized with graphene oxide

Os biocerâmicos a base de nanohidroxiapatita e nanotubos de carbono funcionalizados com óxido de grafeno tem demonstrado ser um biomaterial com propriedades químicas, física e biológicas atraentes para o processo de regeneração óssea. Assim objetivou-se nesse estudo determinar a toxicidade e citotoxicidade destes biomateriais através do teste de allium cepa. Para tanto, soluções de nanohidroxiapatita (nHAp) e das dispersões de nanotubos de carbono funcionalizado com óxido de grafeno (GNR) em meio aquoso em concentrações variando de 30 a 150 µg/mL, foram colocados em contato com os meristemas de espécie de allium cepa(cebolas) por um período de 72h. As raízes germinadas foram extraídas, medidas e coradas para a determinação da citotoxicidade e genotoxicidade. Os resultados indicaram uma não toxicidade do nHAp em concentrações inferiores a 150 µg/mL (6,59 ± 3,26); quando comparados ao controle negativo (CN =10,77 ± 1,89) e controle positivo (CP = 3,77 ± 0,79). Enquanto que os GNRs não apresentaram toxicidade, citotoxicidade ou genotoxicidade em nenhuma das concentrações investigadas. Entretanto, o nHAp indicou uma citotoxicidade e genotoxicidade na concentração acima de 120 µg/mL.  Portanto, sugere-se as concentrações entre 30 a 120 µg/mL dos GNR e nHAp como seguras, quanto as aspecto aqui investigados, para estudos que envolvam processos de regeneração de tecidos biológicos.

BALNEABILIDADE NO BAIXO SUCURIÚ, MUNICÍPIO DE TRÊS LAGOAS/MS

Para avaliar a balneabilidade das praias que banham os ranchos e os condomínios,&nbsp; localizados ao longo do baixo curso do rio Sucuriú, no município de Três Lagoas/MS, utilizou-se do oxigênio dissolvido - OD como principal indicador de qualidade. Para as análises foram&nbsp; escolhidos 14 estações, monitoradas no inverno de 2009. Para avaliar a balneabilidade utilizou-se&nbsp; as classes de enquadramento do CONAMA, resolução 357/2005. Os resultados mostram que de&nbsp; forma geral, as águas superficiais da bacia do Sucuriú, nesse trecho são de boa qualidade e consecutiva balneabilidade, enquadrando-se na classe I. A facilidade de obtenção das mensurações do OD no campo, seu baixo custo e eficiência demonstram sua viabilidade para tal fim

Mechanical properties of composites as functions of the syringe storage temperature and energy dose

Objective: To investigate the mechanical properties of different classifications of composites indicated for posterior application as functions of the storage condition and of the energy dose. Material and Methods: Specimens (8x2x2 mm) were obtained according to the factors: I) Composites (3M ESPE): Filtek P60, Filtek Z350XT, and Filtek Silorane; II) Syringe storage conditions: room temperature, aged, oven, refrigerator, and freezer; and III) Energy dose: 24 J/cm2 and 48 J/cm2. After photoactivation, the specimens were stored at 37ºC for 24 h. After storage, a three-point bending test was carried out in a universal testing machine at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. Data were analyzed by three-way ANOVA and Tukey's test (α=0.05). Results: Different storage conditions significantly affected the silorane composite for S; conversely, no effects were noted in terms of E. The accelerated aging protocol significantly increased the S of Filtek P60 and Filtek Silorane, whereas storage in the oven significantly decreased the S for all of the composites tested. Filtek P60 was the only composite not affected by the lower storage temperatures tested for S, whereas for the silorane this parameter was impacted at the same conditions. The factor "dose" was not statistically significant. Conclusions: The syringe storage at different temperature conditions proved to influence mostly the flexural strength, a clinically important characteristic considering the posterior indication of the materials tested. The silorane composite should not be stored at lower temperatures