A articulação matrizes e transformações lineares em algebra linear

Apresentamos nesse artigo o estudo das relações institucionais esperadas e existentes para o ensino e aprendizagem da noção de matrizes, suas operações e propriedades no Ensino Médio e de matrizes e transformações lineares no Ensino Superior. Observamos que o objetivo de nossa pesquisa é identificar os conhecimentos prévios necessários para trabalhar a articulação entre as noções de matrizes e transformações lineares nos cursos de licenciatura em matemática. Para desenvolver as análises propostas na metodologia da nossa pesquisa construímos uma grade de análse utilizando as ferramentas teóricas de análise apresentadas na teoria antropológica do didático de Chevallard (1992) e Bosch e Chevallard (1999) e nas abordagens teóricas em termos de quadros e mudanças de quadros de Douady (1984, 1992) e níveis de conhecimento esperados dos estudantes de Robert(1997). Os resultados encontrados mostram que é preciso considerar os conhecimentos prévios dos estudantes que iniciam o Ensino Superior para desenvolver o conteúdo escolhido de forma eficaz

Predicting climate effects on aquatic true bugs in a tropical biodiversity hotspot

Climate change is a matter of worldwide concern with severe predicted impacts on biodiversity. Here, we analysed the potential impacts of current and future climates on aquatic true bugs (Heteroptera) in relation to their distribution patterns and ecological preferences (based on a database generated from existing literature references and field collections). We considered the traits as ‘species thermal range’ and ‘emergence period’ to evaluate the future climate change impacts on the distributions of aquatic true bugs in the riverine regions of a tropical biodiversity hotspot, the Western Ghats of India. We used Species Distribution Models (SDMs) to evaluate the potential impacts of climate change on the distributions of aquatic true bugs. We modelled the distributions of twenty-six species of aquatic true bugs using different modelling tools through a carefully examined set of occurrence records to generate potential present distributions and to project these distributions into future scenarios of climate change. We observed increasing/decreasing range sizes of the species in the current and future scenarios. We found losses and increases of species' ranges in some regions, but not much variation in species richness. Similarly, no significant effect was observed in the distribution ranges for species with different duration of emergence period and thermal range in current and future climatic scenarios. Losses and gains in species richness would be concentrated in the mountainous area of the Western Ghats, whereas loss of species and the bigger difference between current and future richness will occur in the adjacent lowlands and towards central regions, including the network of protected areas of the Western Ghats. These areas are critical to buffer regional species loss in the future. Implications for insect conservation: Given the importance of aquatic true bugs as bioindicators and biological control agents, monitoring their range shifts should be routinely addressed in the conservation contexts of the Western Ghats

Thresholds of freshwater biodiversity in response to riparian vegetation loss in the Neotropical region

Protecting riparian vegetation around streams is vital in reducing the detrimental effects of environmental change on freshwater ecosystems and in maintaining aquatic biodiversity. Thus, identifying ecological thresholds is useful for defining regulatory limits and for guiding the management of riparian zones towards the conservation of freshwater biota. Using nationwide data on fish and invertebrates occurring in small Brazilian streams, we estimated thresholds of native vegetation loss in which there are abrupt changes in the occurrence and abundance of freshwater bioindicators and tested whether there are congruent responses among different biomes, biological groups and riparian buffer sizes. Mean thresholds of native vegetation cover loss varied widely among biomes, buffer sizes and biological groups: ranging from 0.5% to 77.4% for fish, from 2.9% to 37.0% for aquatic invertebrates and from 3.8% to 43.2% for a subset of aquatic invertebrates. Confidence intervals for thresholds were wide, but the minimum values of these intervals were lower for the smaller riparian buffers (50 and 100 m) than larger ones (200 and 500 m), indicating that land use should be kept away from the streams. Also, thresholds occurred at a lower percentage of riparian vegetation loss in the smaller buffers, and were critically lower for invertebrates: reducing only 6.5% of native vegetation cover within a 50-m riparian buffer is enough to cross thresholds for invertebrates. Synthesis and applications. The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50-m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law

Fatal outcome of chikungunya virus infection in Brazil

Federal University of Ceará. Fortaleza, CE, Brazil / Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.University of Oxford. Department of Zoology. oxford, United Kingdom.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.University of Oxford. Department of Zoology. oxford, United Kingdom / Gorgas Memorial Institute of Health Studies. Department of Research in Virology and Biotechnology. Panama City, Panama.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil / Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Central Public Health Laboratory of Ceará State. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.State Health Secretariat of Ceará. Death Verification Service Dr Rocha Furtado. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Ceará. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Centro Universitário Christus. Faculdade de Medicina. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil.Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brazil.Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brazil / Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Ministry of Health. Brasilia, DF, Brazil.Faculdade de Medicina São Leopoldo Mandic. Campinas, SP, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.University of Oxford. Department of Zoology. Oxford, United Kingdom.University of São Paulo. Virology Research Center. Ribeirão Preto, SP, Brazil.University of Oxford. Department of Zoology. Oxford, United Kingdom / Imperial College London. Department of Infectious Disease Epidemiology. London, United Kingdom.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Ceará. Fortaleza, CE, Brazil.Federal University of Ceará. Fortaleza, CE, Brazil / Oswaldo Cruz Foundation - Branch Ceará. Fortaleza, CE, Brazil.BACKGROUND: Chikungunya virus (CHIKV) emerged in the Americas in 2013 and has caused approximately 2.1 million cases and >600 deaths. A retrospective investigation was undertaken to describe clinical, epidemiological, and viral genomic features associated with deaths caused by CHIKV in Ceará state, northeast Brazil. METHODS: Sera, cerebrospinal fluid (CSF), and tissue samples from 100 fatal cases with suspected arbovirus infection were tested for CHIKV, dengue virus (DENV), and Zika virus (ZIKV). Clinical, epidemiological, and death reports were obtained for patients with confirmed CHIKV infection. Logistic regression analysis was undertaken to identify independent factors associated with risk of death during CHIKV infection. Phylogenetic analysis was conducted using whole genomes from a subset of cases. RESULTS: Sixty-eight fatal cases had CHIKV infection confirmed by reverse-transcription quantitative polymerase chain reaction (52.9%), viral antigen (41.1%), and/or specific immunoglobulin M (63.2%). Co-detection of CHIKV with DENV was found in 22% of fatal cases, ZIKV in 2.9%, and DENV and ZIKV in 1.5%. A total of 39 CHIKV deaths presented with neurological signs and symptoms, and CHIKV-RNA was found in the CSF of 92.3% of these patients. Fatal outcomes were associated with irreversible multiple organ dysfunction syndrome. Patients with diabetes appear to die at a higher frequency during the subacute phase. Genetic analysis showed circulation of 2 CHIKV East-Central-South African (ECSA) lineages in Ceará and revealed no unique virus genomic mutation associated with fatal outcome. CONCLUSIONS: The investigation of the largest cross-sectional cohort of CHIKV deaths to date reveals that CHIKV-ECSA strains can cause death in individuals from both risk and nonrisk groups, including young adults. © The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America

Thresholds of freshwater biodiversity in response to riparian vegetation loss in the Neotropical region

Protecting riparian vegetation around streams is vital in reducing the detrimental effects of environmental change on freshwater ecosystems and in maintaining aquatic biodiversity. Thus, identifying ecological thresholds is useful for defining regulatory limits and for guiding the management of riparian zones towards the conservation of freshwater biota. Using nationwide data on fish and invertebrates occurring in small Brazilian streams, we estimated thresholds of native vegetation loss in which there are abrupt changes in the occurrence and abundance of freshwater bioindicators and tested whether there are congruent responses among different biomes, biological groups and riparian buffer sizes. Mean thresholds of native vegetation cover loss varied widely among biomes, buffer sizes and biological groups: ranging from 0.5% to 77.4% for fish, from 2.9% to 37.0% for aquatic invertebrates and from 3.8% to 43.2% for a subset of aquatic invertebrates. Confidence intervals for thresholds were wide, but the minimum values of these intervals were lower for the smaller riparian buffers (50 and 100 m) than larger ones (200 and 500 m), indicating that land use should be kept away from the streams. Also, thresholds occurred at a lower percentage of riparian vegetation loss in the smaller buffers, and were critically lower for invertebrates: reducing only 6.5% of native vegetation cover within a 50-m riparian buffer is enough to cross thresholds for invertebrates. Synthesis and applications. The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50-m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law. © 2020 British Ecological Societ