635 research outputs found

    Ordenação de sequências finitas por reversões usando conjugações em grupos de permutações

    Get PDF
    Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2012.O problema da distância entre duas sequências finitas por reversões é estudado neste trabalho em uma abordagem formal e algébrica com base em um grupo de permutações onde a operação do grupo e a de conjugação são utilizadas para simular reversões. A abordagem é geral por operar com sequências genéricas que podem representar estruturas utilizadas na especificação de uma grande variedade de problemas relevantes em computação e em matemática, entre as quais se incluem os genomas. Uma estrutura de grupo foi estabelecida sobre um conjunto de famílias de sequências para possibilitar aplicar uma reversão em uma destas famílias mediante uma operação de conjugação, onde a família e uma certa permutação, atuando como um conjugador, participam como fatores ou termos. Além disso, a mesma reversão pode ser simulada pela operação do grupo utilizando, como fatores ou termos, um conjugador especial da família e a mesma permutação que, acima, atuou como conjugador. O trabalho propõe um método diferente de computar que conduz a uma maneira di- ferente de pensar no problema da distância de reversão o que, eventualmente, poderá contribuir na descoberta de respostas a questões nesta área. Os programas computacionais que utilizam reversões podem ser adaptados ao método. ______________________________________________________________________________ ABSTRACTThe problem of sorting finite sequences by reversals is studied in this work using a formal and algebraic approach based on a group of permutations where the operation of the group and the conjugation are used to implement reversals. The approach is general in the sense that it treats generic sequences which can represent structures, used in the specification of a wide variety of relevant problems in computer science and mathematics, among them are included the genomes. A permutation group structure was established on a set of families of sequences in order to apply a reversal on one of this family through the operation of conjugation, where the family and one certain permutation, acting as a conjugator, participate as factors or terms. Moreover, the same reversal may be applied by means the group operation using, as factors or terms, a special conjugator of the family and the same permutation, above mentioned, that served as conjugator. The work proposes a different method of computing resulting in a different way of thinking about the reversal distance problem which may possibly contribute to find answers in this area. Computer programs that use reversals can be adapted for the method

    Atualização na abordagem do tabagismo em pacientes com doenças respiratórias

    Get PDF
    O tabagismo é o maior responsável pelas doenças respiratórias (DR). Os efeitos nocivos do tabaco sobre o aparelho respiratório se iniciam ainda intraútero e influenciam as respostas imunológicas ao longo da infância e vida adulta. Os tabagistas com DR possuem peculiaridades que podem dificultar a cessação tabágica, tais como maior grau de dependência e de abstinência de nicotina; níveis mais elevados de monóxido de carbono exalado; motivação e autoeficácia baixas; maior preocupação com ganho ponderal; e elevada prevalência de ansiedade e depressão. Além disso, requerem tratamento mais intensivo e prolongado. É necessário esclarecer sempre o paciente sobre o fato de que parar de fumar será a única medida que irá reduzir a progressão das DR e melhorar sua qualidade de vida, independentemente do tempo e da gravidade da doença. Os médicos devem sempre oferecer o tratamento de cessação tabágica. O tratamento ambulatorial ou hospitalar deve ser multidisciplinar, baseado em intervenções comportamentais e farmacoterapia, sendo eficaz e custo-efetivo, dobrando as chances de sucesso.Smoking is the leading cause of respiratory disease (RD). The harmful effects of smoking on the respiratory system begin in utero and influence immune responses throughout childhood and adult life. In comparison with “healthy” smokers, smokers with RD have peculiarities that can impede smoking cessation, such as a higher level of nicotine dependence; nicotine withdrawal; higher levels of exhaled carbon monoxide; low motivation and low self-efficacy; greater concern about weight gain; and a high prevalence of anxiety and depression. In addition, they require more intensive, prolonged treatment. It is always necessary to educate such individuals about the fact that quitting smoking is the only measure that will reduce the progression of RD and improve their quality of life, regardless of the duration and severity of the disease. Physicians should always offer smoking cessation treatment. Outpatient or inpatient smoking cessation treatment should be multidisciplinary, based on behavioral interventions and pharmacotherapy. It will thus be more effective and cost-effective, doubling the chances of success

    Erratum to: The study of cardiovascular risk in adolescents – ERICA: rationale, design and sample characteristics of a national survey examining cardiovascular risk factor profile in Brazilian adolescents

    Get PDF
    1585

    Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

    Get PDF
    Unidad de excelencia María de Maeztu CEX2019-000940-MAim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

    Geography and ecology shape the phylogenetic composition of Amazonian tree communities

    Get PDF
    Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2^{2} = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2^{2} = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

    Pervasive gaps in Amazonian ecological research

    Get PDF
    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

    Get PDF

    As particularidades clínicas da otite média: Clinical features of otitis media

    Get PDF
    A otite média é um processo inflamatório de evolução abrupta, acompanhado pelo quadro clínico típico de inflamação na orelha média, sendo sua incidência prevalente em crianças, culminando em leves repercussões clínicas, mas que deve ser adequadamente diagnosticada e tratada. Este evento clínico pode ser agudo, subagudo ou crônico com aparições típicas, evolução e manejo clínico diferenciados. O seguinte artigo é uma revisão narrativa de literatura que visa analisar a respeito das principais particularidades clínicas da Otite Média. Diante das informações coletadas, pode se elucidar que a otite média é o fator causal para implicações negativas e antibioticoterapia em crianças, logo é essencial medidas para diagnose precoce para evitar repercussões na saúde destes

    Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

    Get PDF
    Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

    Geography and ecology shape the phylogenetic composition of Amazonian tree communities

    Get PDF
    AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions
    corecore