970 resultados para Multidimensional scaling


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A global database containing 3365 occurrences, 821 species and 251 genera of the Capitanian (Late Guadalupian, Permian) brachiopod faunas from 24 stations has been analyzed by cluster analysis using the Jaccard and Otsuka coefficients and the probabilistic index of similarity, nonmetric multidimensional scaling and minimum spanning tree. Two supergroups, three groups and six subgroups are revealed and interpreted as representing, respectively, two biotic realms (the Palaeoequatorial and Gondwanan Realms), two regions and six provinces. An additional realm (the Boreal Realm), based on the fauna from Spitsbergen, also appears recognizable although it also shows considerable similarities with southwestern North America and the northern margin of Gondwana as revealed by the statistical analysis. The Palaeoequatorial Realm can be further subdivided into the North America Region and the Asian Tethyan Region. The six biotic provinces are the Cathaysian Province in the Palaeotethys and Mesotethys, the Greenland-Svalbard Province in the Arctic region, the Austrazean Province in eastern Australia and New Zealand, the Grandian Province in western North America and the two transitional zones (the Himalayan Province in the southern temperate zone and the Sino–Mongolian–Japanese Province in the northern temperate zone). Polynomial regression analysis and rarefaction analysis indicate that the generic diversities of brachiopod faunas during the Capitanian peaked in the Palaeoequatorial Cathaysian Province and the two transitional zones (Himalayan Province and Sino–Mongolian–Japanese Province), but fell dramatically in the polar regions. The generic diversity of the Palaeoequatorial Grandian Province is apparently lower than in the two transitional zones of temperate palaeolatitudes, suggesting that the generic diversity of Capitanian brachiopod faunas does not exhibit a strict negative correlation with palaeolatitudes. This in turn would suggest that biogeographical determinants (such as geographical barriers, inhabitable area and ocean currents) other than latitude-related temperature control may also have played an important role in the dispersal of some brachiopods and the characterization of some local provinces and high diversities. The Capitanian global brachiopod palaeobiogeography is generally comparable with those in the Wuchiapingian and Changhsingian, but with some notable differences. These include: (1) that the Grandian Province of the Capitanian in western North America vanished after the end-Guadalupian regression, (2) that the western Tethyan Province of the Lopingian could not be distinguished in the Capitanian, and (3) that the Austrazean Province was larger in area than either in the Wuchiapingian or in the Changhsingian.

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Allozyme and Random Amplified Polymorphic DNA (RAPD) variation was surveyed in the freshwater crayfish Cherax destructor Clark, an ecologically and commercially important species that is widespread throughout the freshwater systems of central Australia. At the intra-population level, allozymes revealed a similar level of variation to that found in other freshwater crayfish; RAPDs showed less diversity than allozymes, which was unexpected. At the inter-population level, both techniques revealed significant population structure, both within and between drainages. RAPD results were consistent with phylogeographic patterns previously identified using mtDNA. Although allozyme data showed little geographic pattern in relation to genetic variation based on multidimensional-scaling (MDS) plots on matrices of genetic distance, results of AMOVA and Mantel tests indicated significant population structuring. Each of the mtDNA lineages proposed in a previous study also showed significant genetic structure at similar levels as revealed by RAPDs but different levels by allozymes. These results reject hypotheses previously put forward on genetic homogenisation within the species due to wide-scale translocation. The implications of the findings for conservation and aquaculture of C. destructor are also discussed.

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Lichen floristics and distribution were examined in cool temperate rainforests of Victoria, Australia. Forty sites were sampled, ten from each of the Otways, Yarra Ranges, Baw Baw, and Errinundra regions. A total of 165 lichen species were recorded, representing 38 fam- ilies. Seventeen species are new for Victoria. Non-metric Multidimensional Scaling showed three lichen groups that corresponded with the rainforest types in which they occurred. A sub-group of lichen species were considered widespread and represented the core of Victoria's rainforest lichen flora.

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Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [SD (fingerlings ha−1)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development (DL) and shoreline area ratio (RLA), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation (P < 0.05) between RLA and total fish yield (Y). A multiple regression equation, Y = −693 + 4810 RLA + 0.484 SD, was generated to estimate fish harvest in relation to SD.

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The River Murray, Australia, is a highly regulated river from which almost 80% of mean annual flow is removed for human use, primarily irrigated agriculture. Consequent changes to the pattern and volume of river flow are reflected in floodplain hydrology and, therefore, the wetting/drying patterns of floodplain wetlands. To explore the significance of these changes, macroinvertebrate samples were compared between permanent and temporary wetlands following experimental flooding in a forested floodplain of the River Murray. Weekly samples from two permanent wetlands and four associated temporary sites were used to track changes in macroinvertebrate assemblage composition. Non-metric multidimensional scaling was used to ordinate the macroinvertebrate data, indicating consistent differences between the biota of permanent and temporary wetlands and between the initial and later assemblages in the temporary sites. There were marked changes over time, but little sign that the permanent and temporary assemblages were becoming more alike over the 25-week observation period. The apparent heterogeneity of these systems is of particular importance in developing river management plans which are likely to change flooding patterns. Such plans need to maintain a mosaic of wetland habitats if floodplain biodiversity is to be supported.

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The effects of increased trophic complexity, through the addition of predatory notonectids (Anisops deanei), on temporary pond microcosms used for aquatic toxicity testing were studied. Replicate microcosms were established using sediment from a dried temporary pond, and treated with one of four concentrations of the organochlorine pesticide endosulfan (0, 1, 10 or 50 μg/L), in the presence or absence of six A. deanei. The tanks were sampled regularly for nine weeks following the addition of the predators and the entire contents of each tank counted after 12 weeks. Analysis using non-metric multidimensional scaling (MDS) and non-parametric MANOVA showed that both Anisops and endosulfan at concentrations >10 μg/L significantly altered community structure. However, an interaction between the effects of Anisops and the effects of endosulfan was not detected. The addition of Anisops did not increase the variability of response and thus did not reduce the sensitivity of the test method.

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Introduction: While the importance and magnitude of the burden of low back pain upon the individual is well recognized, a systematic understanding of the impact of the condition on individuals is currently hampered by the lack of an organized understanding of what aspects of a person’s life are affected and the lack of comprehensive measures for these effects. The aim of the present study was to develop a conceptual and measurement model of the overall burden of low back pain from the individual’s perspective using a validity-driven approach.
Methods: To define the breadth of low back pain burden we conducted three concept-mapping workshops to generate an item pool. Two face-to-face workshops (Australia) were conducted with people with low back pain and clinicians and policy-makers, respectively. A third workshop (USA) was held with international multidisciplinary experts. Multidimensional scaling, cluster analysis, participant input and thematic analyses organized participants’ ideas into clusters of ideas that then informed the conceptual model.
Results: One hundred and ninety-nine statements were generated. Considerable overlap was observed between groups, and four major clusters were observed - Psychosocial, Physical, Treatment and Employment - each with between two and six subclusters. Content analysis revealed that elements of the Psychosocial cluster were sufficiently distinct to be split into Psychological and Social, and a further cluster of elements termed Positive Effects also emerged. Finally, a hypothesized structure was proposed with six domains and 16 subdomains. New domains not previously considered in the back pain field emerged for psychometric verification: loss of independence, worry about the future, and negative or discriminatory actions by others.
Conclusions: Using a grounded approach, an explicit a priori and testable model of the overall burden of low back pain has been proposed that captures the full breadth of the burden experienced by patients and observed by experts.

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The study aimed to examine the factor structure of the Obsessive Beliefs Questionnaire (OBQ), the most widely used measure of dysfunctional beliefs in obsessive—compulsive disorder (OCD). Multiple exploratory methods (exploratory factor analysis, cluster analysis by variable, multidimensional scaling) were used to examine the questionnaire. Confirmatory factor analyses were also performed in two large nonclinical samples from Australia (N = 1,234) and Israel ( N = 617). Our analyses suggested a four-factor solution with 38 items, where threat and responsibility formed separate dimensions (the “OBQ-TRIP”). This version had superior fit statistics across the two divergent confirmatory samples, when compared with four alternative models suggested by previous authors. Of the OBQ dimensions, the threat scale correlated most strongly with OCD symptom measures, even when controlling for depression. A short, 20-item version of the scale is offered for further study. Implications and limitations are discussed.

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Objective
To develop a conceptual framework for the design of an in-home monitoring system (IMS) based on the requirements of older adults with vision impairment (VI), informal caregivers and eye-care rehabilitation professionals.

Materials and Methods
Concept mapping, a mixed-methods statistical research tool, was used in the construction of the framework. Overall, 40 participants brainstormed or sorted and rated 83 statements concerning an IMS for older adults with VI. Multidimensional scaling and hierarchical cluster analysis were employed to construct the framework. A questionnaire yielded further insights into the views of a wider sample of older adults with VI (n=78) and caregivers (n=25) regarding IMS.

Results
Concept mapping revealed a nine-cluster model of IMS-related aspects including affordability, awareness of system capabilities, simplicity of installation, operation and maintenance, system integrity and reliability, fall detection and safe movement, user customization, user preferences regarding information delivery, and safety alerts for patients and caregivers. From the questionnaire, independence, safety and fall detection were the most commonly reported reasons for older adults and caregivers to accept an IMS. Concerns included cost, privacy, security of the information obtained through monitoring, system accuracy, and ease of use.

Discussion
Older adults with VI, caregivers and professionals are receptive to in-home monitoring, mainly for fall detection and safety monitoring, but have concerns that must be addressed when developing an IMS.

Conclusion
Our study provides a novel conceptual framework for the design of an IMS that will be maximally acceptable and beneficial to our ageing and vision-impaired population.

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Objective: To comprehensively identify components of the physical limitation concept in knee osteoarthritis (OA) and to rate the clinical importance of these using perspectives of both patients and health professionals.Design: Concept mapping, a structured group process, was used to identify and organize data in focus groups (patients) and via a global web-based survey (professionals). Ideas were elicited through a nominal group technique and then organized using multidimensional scaling, cluster analysis, participant validation, rating of clinical importance, and thematic analyses to generate a conceptual model of physical limitations in knee OA. Results: Fifteen Danish patients and 200 international professionals contributed to generating the conceptual model. Five clusters emerged: ‘Limitations/physical deficits’; ‘Everyday hurdles’; ‘You’re not the person you used to be’; ‘Need to adjust way of living’; and ‘External limitations,’ each with sub-clusters. Patients generally found their limitations more important than the professionals did. Conclusion: Patients and professionals agreed largely on the physical limitation concept in knee OA. Some limitations of high importance to patients were lower rated by the professionals, highlighting the importance of including patients when conceptualizing patient outcomes. These data offer new knowledge to guide selection of clinically relevant outcomes and development of outcome measures in knee OA.

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Tendo como motivação o desenvolvimento de uma representação gráfica de redes com grande número de vértices, útil para aplicações de filtro colaborativo, este trabalho propõe a utilização de superfícies de coesão sobre uma base temática multidimensionalmente escalonada. Para isso, utiliza uma combinação de escalonamento multidimensional clássico e análise de procrustes, em algoritmo iterativo que encaminha soluções parciais, depois combinadas numa solução global. Aplicado a um exemplo de transações de empréstimo de livros pela Biblioteca Karl A. Boedecker, o algoritmo proposto produz saídas interpretáveis e coerentes tematicamente, e apresenta um stress menor que a solução por escalonamento clássico.

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As florestas secundárias e plantações de espécies exóticas estão se expandindo nas paisagens tropicais. No entanto, nossa compreensão sobre o valor destas florestas para a conservação da biodiversidade de invertebrados ainda é incipiente. Neste trabalho, usamos a fauna de formigas de serapilheira para avaliar a diversidade desses insetos entre três florestas de Eucalyptus, sendo uma comercial (quatro anos de idade) e duas abandonadas em diferentes idades de regeneração (16 e 31 anos) e uma área de Mata Atlântica secundária. A riqueza total foi mais alta na floresta secundária e nos plantios de Eucalyptus abandonados há mais tempo. A densidade de espécies na floresta secundária foi significativamente maior quando comparado as plantações de Eucalyptus, mas não difere entre eucaliptais; análise de ordenação revelou diferenças na composição de espécies entre as plantações de Eucalyptus com subbosque ausente e com subbosque desenvolvido ou em desenvolvimento. Ainda, foi constatada uma sobreposição acentuada entre amostras de serapilheira das florestas de eucaliptos abandonadas há mais tempo e a floresta secundária. em geral, plantações de eucalipto foram caracterizadas pela presença de espécies generalistas e de ampla distribuição. Nossos resultados indicam que embora o subbosque de plantações de eucaliptos com maior idade de regeneração suporte um conjunto relativamente alto de espécies generalistas de formigas, é improvável que eucaliptais conservem a maioria das espécies de florestas primárias, especialmente predadores especializados, Dacetini e espécies nômades.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The inherent complexity of natural communities is a challenge to our understanding about how the habitat influences the abundance, local distribution and species diversity. The habitat can influence community structure in multiple ways and elucidate these relationships has provoked a lot of debate in ecology. The habitat heterogeneity hypothesis states that an increase in habitat heterogeneity (number of habitats) leads to an increase in species diversity in the landscape due to an expansion in niche dimensions. This study aims to identify whether this hypothesis is valid for the spiders that inhabit a locality in the Caatinga of northeastern Brazil. Cursorial and arboreal spiders were sampled in 30 plots within an area of Caatinga together with measures of environmental complexity, habitat heterogeneity and environmental parameters related to multiple aspects of vegetation architecture and species composition of woody plants. Stepwise multiple regressions were used to define which local environmental parameters best explain the variation in arboreal and cursorial spiders richness. Then a NMDS (Nonmetric multidimensional scaling) was used to reduce the number of predictive variables to those who are the most important and best represent the variation in spiders richness associated with the environment they were sampled. The results show a clear segregation between the guilds of arboreal and cursorial spiders, both related to what kind of environmental variables best explain its variation as well as in relation to what part of the vegetation they occupy

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Teaching is an activity inherent to the human condition. Historically, from the institutionalization of education, the key role to pursue that activity has been attributed to the teacher, who is required to adapt to the demands of each historical conjuncture. Currently, according to the new paradigmatic requirements, the teacher must possess various skills in order to handle the complex and challenging act of teaching. Assuming the existence of a gap between what the State and the scientific discourse recommend the teacher act upon in the classroom, a decision was made to identify the configuration and structure of social representation in the act of teaching, put forth by elementary school teachers in the public schools of Natal, RN, Brazil. Therefore, the research relied on the theoretical model developed by Domingos Sobrinho (1998, 2000, 2003), which articulates the praxeology of Pierre Bourdieu with the theory of social representations of Serge Moscovici (1978). It was intended to demonstrate how teachers habitus, in its due historical context, directs the construction of social representations in the act of teaching which guides the actions of the teacher, particularly in the classroom context. At the methodological level, the following methods and techniques were used: bibliographic and documentary review in order to identify the scientific discourse on the subject matter and the official parameters of educational regulation and the act of teaching; the Procedure of Multiple Classifications PMC in order to capture the configuration and structure of the representational content in focus, the direct observation of the classroom to identify in actual terms the social representation as "guide to action" as the theory preaches. From the standpoint of the analysis, quantitative data were analysed through Multidimensional Scaling MDS, covering in this study the Multidimensional Scale Analysis MSA and Smallest Space Analysis SSA; and non-parametric statiscal techniques. Additional data of qualitative value had to undergo categorical content analysis. It was then concluded that the teachers investigated guided themselves by social representation, the product of collectively constructed and shared assumptions about the act of teaching, forming a synthesis of different sources of information and knowledge acquirement, involving elements of common sense, religious habitus, pedagogic models considered outdated, the agencies responsible for teacher training and the hegemonic discourse about education today