32 resultados para Multidimensional Scaling
Resumo:
ABSTRACT The analysis of changes in species composition and vegetation structure in chronosequences improves knowledge on the regeneration patterns following land abandonment in the Amazon. Here, the objective was to perform floristic-structural analysis in mature forests (with/without timber exploitation) and secondary successions (initial, intermediate and advanced vegetation regrowth) in the Tapajós region. The regrowth age and plot locations were determined using Landsat-5/Thematic Mapper images (1984-2012). For floristic analysis, we determined the sample sufficiency and the Shannon-Weaver (H'), Pielou evenness (J), Value of Importance (VI) and Fisher's alpha (α) indices. We applied the Non-metric Multidimensional Scaling (NMDS) for similarity ordination. For structural analysis, the diameter at the breast height (DBH), total tree height (Ht), basal area (BA) and the aboveground biomass (AGB) were obtained. We inspected the differences in floristic-structural attributes using Tukey and Kolmogorov-Smirnov tests. The results showed an increase in the H', J and α indices from initial regrowth to mature forests of the order of 47%, 33% and 91%, respectively. The advanced regrowth had more species in common with the intermediate stage than with the mature forest. Statistically significant differences between initial and intermediate stages (p<0.05) were observed for DBH, BA and Ht. The recovery of carbon stocks showed an AGB variation from 14.97 t ha-1 (initial regrowth) to 321.47 t ha-1 (mature forests). In addition to AGB, Ht was also important to discriminate the typologies.
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The taxonomic composition, observed and estimated species richness, and patterns of community structure of arboreal spider assemblages in eleven sites surrounding the "Banhado Grande" wet plain in the state of Rio Grande do Sul, Brazil, are presented. These sites represent three different vegetational types: hillside (four sites), riparian (five sites) and flooded forests (two sites). The spiders were captured by beating on foliage and "aerial litter". A sample was defined as the result of beating on twenty bushes, tree branches or "aerial litter" clusters, which roughly corresponds to one-hour search effort per sample. Fifty five samples (five per site) were obtained, resulting in an observed richness of 212 species present as adult or identifiable juveniles. The total richness for all samples was estimated to be between 250 (Bootstrap) to 354 species (Jackknife 2). Confidence intervals of both sample and individual-based rarefaction curves for each vegetation type clearly indicated that flooded forest is the poorest vegetation type with respect to spider species richness, with hillside and riparian forests having a similar number of species. The percentage complementarity between the eleven sites indicated that all sites contain a distinct set of species, irrespective of their vegetation types. Nevertheless, the spider assemblages in riparian and hillside forests are more similar with respect to each other than when compared to flooded forest. Both cluster and nonmetric multidimensional scaling analyses showed no strong correspondence between the spider arboreal fauna and the three vegetation types. Moreover, a Mantel test revealed no significant association between species composition and geographic distance among sites.
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Human activities in tropical forests are the main causes of forest fragmentation. According to historical factor in deforestation processes, forest remnants exhibit different sizes and shapes. The aim of the present study was to evaluate the dung beetle assemblage on fragments of different degree of sizes. Sampling was performed during rainy and dry season of 2010 in six fragments of Atlantic forest, using pitfall traps baited with excrement and carrion. Also, we used two larger fragments as control. We used General Linear Models to determine whether the fragments presented distinguished dung beetle abundance and richness. Analysis of Similarities and Non-Metric Multidimensional Scaling were used to determine whether the dung beetle assemblage was grouped according to species composition. A total of 3352 individuals were collected and 19 species were identified in the six fragments sampled. Dung beetle abundance exhibited a shift according to fragment size; however, richness did not change among fragments evaluated. Also, fragments sampled and the two controls exhibited distinct species composition. The distinction on abundance of dung beetles among fragments may be related to different amount of resource available in each one. It is likely that the dung beetle richness did not distinguish among the different fragments due to the even distribution of the mammal communities in these patches, and consequent equal dung diversity. We conclude that larger fragments encompass higher abundance of dung beetle and distinct species. However, for a clearer understanding of effects of fragmentation on dung beetles in Atlantic forest, studies evaluating narrower variations of larger fragments should be conducted.
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Farm planning requires an assessment of the soil class. Research suggest that the Diagnosis and Recommendation Integrated System (DRIS) has the capacity to evaluate the nutritional status of coffee plantations, regardless of environmental conditions. Additionally, the use of DRIS could reduce the costs for farm planning. This study evaluated the relationship between the soil class and nutritional status of coffee plants (Coffea canephora Pierre) using the Critical Level (CL) and DRIS methods, based on two multivariate statistical methods (discriminant and multidimensional scaling analyses). During three consecutive years, yield and foliar concentration of nutrients (N, P, K, Ca, Mg, S, B, Zn, Mn, Fe and Cu) were obtained from coffee plantations cultivated in Espírito Santo state. Discriminant analysis showed that the soil class was an important factor determining the nutritional status of the coffee plants. The grouping separation by the CL method was not as effective as the DRIS one. The bidimensional analysis of Euclidean distances did not show the same relationship between plant nutritional status and soil class. Multidimensional scaling analysis by the CL method indicated that 93.3 % of the crops grouped into one cluster, whereas the DRIS method split the fields more evenly into three clusters. The DRIS method thus proved to be more consistent than the CL method for grouping coffee plantations by soil class.
Resumo:
The objective of this work was to evaluate an inventory method efficiency for ants. We used subsamples collected in 24 transects of 100 m, distributed in 6 plots of 600 ha each in primary forest, as part of a long-term project. Ten litter subsamples were extracted per transect using Winkler extractors. Ants were identified to genus level, and Crematogaster, Gnamptogenys and Pachycondyla genera to species/morphospecies level. To evaluate the consequences of reduced sampling on the retention of ecological information, we estimated the lowest number of subsamples needed to detect the effects of environmental variables. Multidimensional scaling (MDS) was used to generate dissimilarity matrices, and Mantel correlations between each reduced-sampling effort and maximum effort were used as an index of how much information was maintained and could still be used in multivariate analyses. Lower p-values was observed on the effect of soil pH in the community of genera, and on the effect of the litter volume for the community of Crematogaster. The trend was still detectable in the analysis based on reduced-sampling. The number of subsamples can be reduced, and the cost-efficiency of the protocol can be improved with little loss of information.
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The present study examined the floristic composition of three fragments of Araucaria Forest (AF) in the Planalto Catarinense region of southern Brazil as well as the floristic contextualization of these areas in relation to other remnant AF sites. Three AF fragments at different altitudes were analyzed in the municipalities of Campos Novos, Lages, and Painel. Fifty 200 m² plots were examined in each fragment and all of the trees with CBH (circumference at breast height) > 15.7 cm were identified. In order to floristically contextualize the study fragments, comparisons were made with other remnant AF sites by way of dendrograms and NMDS (Non-metric multidimensional scaling). Environmental and spatial variables were plotted on the diagram produced by the NMDS to evaluate their influence on the floristic patterns encountered. The forest fragments studied demonstrated high floristic heterogeneity, indicating that AFs cannot be considered homogeneous formations and they could be classified into 3 phytogeographical categories: i) high altitude areas influenced by cloud cover/fog, including the Painel region; ii) areas of lesser altitude and greater mean annual temperatures situated in the Paraná River basin, and iii) areas situated in the Paraná and Upper-Uruguay river basins and the smaller basins draining directly into the southern Atlantic, near Campos Novos and Lages. The environmental variables most highly correlated with species substitutions among the sites were altitude, mean annual temperature, and the mean temperature of the most humid trimester.
Resumo:
A 3-bp insertion/deletion polymorphism in intron 6 of GSTM3 (rs1799735, GSTM3*A/*B) affects the activity of the phase 2 xenobiotic metabolizing enzyme GSTM3 and has been associated with increased cancer risk. The GSTM3*B allele is rare or absent in Southeast Asians, occurs in 5-20% of Europeans but was detected in 80% of Bantu from South Africa. The wide genetic diversity among Africans led us to investigate whether the high frequency of GSTM3*B prevailed in other sub-Saharan African populations. In 168 healthy individuals from Angola, Mozambique and the São Tomé e Príncipe islands, the GSTM3*B allele was three times more frequent (0.74-0.78) than the GSTM3*A allele (0.22-0.26), with no significant differences in allele frequency across the three groups. We combined these data with previously published results to carry out a multidimensional scaling analysis, which provided a visualization of the worldwide population affinities based on the GSTM3 *A/*B polymorphism.
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No trabalho são desenvolvidos indicadores de integração regional com o principal objetivo de apresentar uma analise multidimensional do Mercosul no período de 1991 a 2006. A pesquisa parte da premissa que o Mercosul não é um caso sui generis de integração regional, e sim um exemplo de organização de integração regional assim como, por exemplo, a União Européia ou a Comunidade Andina de Nações. Assim, embora os indicadores sejam desenvolvidos para serem aplicados no Mercosul, eles poderiam potencialmente ser aplicados para outros casos de processos de integração regional.
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A abordagem de gestão de processos de negócio ganhou grande popularidade e ampla disseminação nas últimas décadas. Uma análise dessa abordagem mostra que ela persegue dois objetivos de difícil conciliação: por um lado, visa à formalização dos processos em modelos - a fim de estruturar efetivamente o trabalho - e, por outro lado, visa dar flexibilidade à organização - mantendo a sua capacidade de responder a situações novas e imprevistas. O presente artigo examina a relação entre formalização e flexibilidade na modelagem de processos de negócio, por meio de uma pesquisa empírica em uma companhia de manutenção de aeronaves na Alemanha, adotando um enfoque qualitativo em diálogo com a Teoria Ator-Rede. A análise deste caso oferece duas contribuições principais: (a) evidencia e ilustra a complexidade sociotécnica envolvida na modelagem de processos de negócio e (b) apresenta os contornos de uma compreensão multidimensional sobre a relação entre formalização e flexibilidade na gestão de processos de negócio.
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This paper examines the nature of the construct of consumers' trust toward the electronic channel of their financial institution. Through a study of a total of 372 individual users of Internet banking in Spain, we have managed to develop a third-order measuring instrument that integrates a total of seven dimensions. The exploratory and confirmatory factor analyses were used to test the validation and reliability of the proposed scale. Findings provide useful information to professionals who seek to identify how customer's trust is formed in the online channel and in the financial sector.
Resumo:
Na abordagem das capacitações de Sen (1981, 1985, 2000, 2001), a pobreza significa privação em diferentes aspectos da vida. O objetivo deste estudo é mensurar a pobreza multidimensional nos municípios da Região Nordeste por meio da teoria dos conjuntos fuzzy e dados do Censo Demográfico (IBGE, 2010). São utilizados 19 indicadores (funcionamentos) distribuídos em quatro dimensões: educação, saúde, condições habitacionais e renda. Os resultados indicam pobreza, com destaque nas dimensões da renda e da educação, principalmente nos estados de Maranhão, Alagoas, Piauí e Paraíba. Políticas de redução da pobreza precisam considerar quais são as privações sofridas pelas pessoas e as particularidades do local onde vivem.
Resumo:
The impact of shift and night work on health shows a high inter- and intra-individual variability, both in terms of kind of troubles and temporal occurrence, related to various intervening factors dealing with individual characteristics, lifestyles, work demands, company organisation, family relations and social conditions. The way we define "health" and "well-being" can significantly influence appraisals, outcomes and interventions. As the goal is the optimisation of shiftworkers' health, it is necessary to go beyond the health protection and to act for health promotion. In this perspective, not only people related to medical sciences, but many other actors (ergonomists, psychologists, sociologists, educators, legislators), as well as shiftworkers themselves. Many models have been proposed aimed at describing the intervening variables mediating and/or moderating the effects; they try to define the interactions and the pathways connecting risk factors and outcomes through several human dimensions, which refer to physiology, psychology, pathology, sociology, ergonomics, economics, politics, and ethics. So, different criteria can be used to evaluate shiftworkers' health and well-being, starting from biological rhythms and ending in severe health disorders, passing through psychological strain, job dissatisfaction, family perturbation and social dis-adaptation, both in the short- and long-term. Consequently, it appears rather arbitrary to focus the problem of shiftworkers' health and tolerance only on specific aspects (e.g. individual characteristics), but a systemic approach appears more appropriate, able to match as many variables as possible, and aimed at defining which factors are the most relevant for those specific work and social conditions. This can support a more effective and profitable (for individuals, companies, and society) adoption of preventive and compensative measures, that must refer more to "countervalues" rather than to "counterweights".
Resumo:
O estudo objetivou desenvolver e validar instrumento capaz de medir não-adesão ao tratamento com medicamentos em suas múltiplas dimensões. O Questionário de Adesão a Medicamentos com três perguntas foi aplicado a 46 pessoas com hipertensão arterial em Blumenau, SC, 2006. Compararam-se as medidas de não-adesão obtidas com outros quatro métodos: testes de Haynes, Morisky, contagem de comprimidos e desfecho clínico. As medidas de não-adesão variaram de acordo com o método. A medida composta obtida a partir do questionário desenvolvido resultou em não-adesão de 47,8% (IC 95%: 32,9;63,1), enquanto o padrão-ouro foi 69,6% (IC 95%: 54,3;82,3). As medidas de acurácia para detectar não-adesão mostraram sensibilidade de 62,5% e especificidade de 85,7%, área sob a curva ROC de 74,1% e valor preditivo positivo de 90,9%. Os resultados sugerem bom desempenho do Questionário de Adesão a Medicamentos.
Resumo:
O artigo apresenta o processo de elaboração do questionário utilizado no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Iniciamos pelo relato sobre a "Seleção de Temas" abordados no questionário, cujo conteúdo teria que abranger o conhecimento disponível acerca da complexa rede de causalidade dos desfechos de interesse, assim como possibilitar a comparabilidade com estudos semelhantes. Contextualizamos a "tradução e a adaptação de instrumentos de medida", necessárias no caso de escalas de avaliação de vizinhanças, do instrumento para diagnóstico de transtornos depressivos e de ansiedade, e do questionário de frequência alimentar. A seguir, comentamos os critérios que nortearam a "ordem dos blocos temáticos" e finalmente a importância prática dos "pré-testes e estudos-piloto". As relações entre o conjunto de informações reunidas no ELSA poderão constituir contribuição original sobre os fatores que causam ou agravam os desfechos de interesse no contexto brasileiro, assim como sobre seus fatores de proteção.
Resumo:
Two methods were evaluated for scaling a set of semivariograms into a unified function for kriging estimation of field-measured properties. Scaling is performed using sample variances and sills of individual semivariograms as scale factors. Theoretical developments show that kriging weights are independent of the scaling factor which appears simply as a constant multiplying both sides of the kriging equations. The scaling techniques were applied to four sets of semivariograms representing spatial scales of 30 x 30 m to 600 x 900 km. Experimental semivariograms in each set successfully coalesced into a single curve by variances and sills of individual semivariograms. To evaluate the scaling techniques, kriged estimates derived from scaled semivariogram models were compared with those derived from unscaled models. Differences in kriged estimates of the order of 5% were found for the cases in which the scaling technique was not successful in coalescing the individual semivariograms, which also means that the spatial variability of these properties is different. The proposed scaling techniques enhance interpretation of semivariograms when a variety of measurements are made at the same location. They also reduce computational times for kriging estimations because kriging weights only need to be calculated for one variable. Weights remain unchanged for all other variables in the data set whose semivariograms are scaled.