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X-ray Microdensitometry Applied to Determination of Wood Density Variation of Eucalyptus grandis W. Hill trees

Ugulino de Oliveira, Bruna Roque; Latorraca, João Vicente de Figueiredo; Filho, Mario Tomazello; de Moura Palermo, Gilmara Pires; Carvalho, Alexandre Monteiro de; Pastro, Milena Scaramussa
Fonte: IPEF-INST PESQUISAS ESTUDOS FLORESTAIS; PIRACICABA Publicador: IPEF-INST PESQUISAS ESTUDOS FLORESTAIS; PIRACICABA
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.04%
This study aimed to analyze the variation of wood density in the radial and longitudinal trunk of Eucalyptus grandis trees. Six 23 years old trees were selected and cross sections were cut in three longitudinal positions (DBH, 3.70, 6.10 m) of the log. The results showed that the apparent density of wood (i) increases in the radial direction, characterizing the juvenile wood and mature wood, (ii) no significant variation in base-top log direction was observed. Based on the radial profiles of density, the mature wood of Eucalyptus grandis can be applied in the manufacture of products with higher aggregated value (PMVAs).

Análise da variação longitudinal do esqueleto axial em Serpentes (Squamata) empregando ferramentas de morfometria geométrica; Analysis of the longitudinal variation in the axial skeleton of Serpentes (Squamata) using geometric morphometrics techniques

Machado, Fabio de Andrade
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/11/2010 PT
Relevância na Pesquisa
46.12%
As cobras são um grupo de vertebrados extremamente bem sucedido. Apesar da aparente simplicidade, elas conseguiram ocupar uma grande diversidade de habitats. O esqueleto axial das serpentes apresenta relação com vários aspectos da vida que puderam ter tido influência direta em seu sucesso evolutivo. Além disso, a forma dos elementos vertebrais possui valor taxonômico, fato que desperta particular interesse, visto que a maior parte do registro fóssil deste grupo é constituído por elementos vertebrais desarticulados. A morfometria geométrica utiliza informações sobre a posição de pontos em duas ou três dimensões, localizados sobre estruturas anatômicas para análise estatística da variação da forma. Esse conjunto de técnicas tem se mostrado eficaz em avaliar variações da forma que não seriam diagnosticadas por métodos tradicionais. O presente trabalho buscou avaliar as vértebras do esqueleto pré-cloacal de Serpentes no contexto da morfometria geométrica, considerando as influências ecológicas e filogenéticas sob estas estruturas, e investigando ainda a utilidade taxonômica da forma vertebral. Os resultados apresentados aqui sugerem a existência de uma padronização do esqueleto axial de serpentes que é conservada ao longo da história evolutiva desse grupo. Análises ecomorfológicas demonstram que a forma vertebral é fortemente influenciada por hábitos de vida como fossorialidade e constrição. A despeito da ausência de sinal filogenético...

Modelos não-lineares para dados longitudinais provenientes de experimentos em blocos casualizados abordagem bayesiana; Nonlinear models for longitudinal data from experiments in randomized block design a bayesian framework

Rocha, Everton Batista da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/01/2011 PT
Relevância na Pesquisa
36.12%
Dados consistindo de medidas repetidas tomadas em um mesmo indivíduo são muito comuns na agricultura e biologia. A modelagem de dados desta natureza usualmente envolve a caracterização da relação entre medidas repetidas e covariáveis. Em muitas aplicações, a relação proposta entre as medidas repetidas tem um comportamento não-linear nos parâmetros desconhecidos de interesse. Por exemplo, em estudo de crescimento de arvores, geralmente o comportamento da variável resposta e melhor descrito por um modelo não-linear nos parâmetros porque estes modelos caracterizam melhor a realidade dos fenômenos biológicos em estudo e porque e possvel uma interpretação biológica dos parâmetros. A presença de medidas repetidas em um indivíduo requer um cuidado particular na caracterização da variac~ao entre medidas dentro de uma mesma unidade experimental e entre unidades. Dados observados na mesma unidade experimental são correlacionados, e é provável que essa correlação decaia ao longo do tempo e que haja variações entre as medidas. Neste trabalho considera-se duas estruturas de covariâncias: erros aleatórios e independentes com media zero e variância 2, esta formulação não incorpora uma possível dependência entre as observações tomadas no mesmo indivíduo...

Longitudinal distribution and seasonality of macroalgae in a subtropical stream impacted by organic pollution

Peres, Cleto Kaveski; Branco, Ciro Cesar Zanini; Krupek, Rogério Antonio; Rocha, José Celso
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: 199-207
ENG
Relevância na Pesquisa
36.09%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); OBJETIVO: O presente estudo foi desenvolvido com o objetivo de avaliar a distribuição longitudinal e temporal e o efeito da poluição orgânica em comunidades de macroalgas em um riacho subtropical; MÉTODOS: A presença e a cobertura percentual das macroalgas foram investigadas durante um período sazonal em quatro pontos de amostragem ao longo do perfil longitudinal do rio Cascavel, Estado do Paraná, região subtropical do Brasil. Os pontos de amostragem foram aleatoriamente escolhidos, porém as suas localizações em relação às fontes de poluição orgânica urbanas foram consideradas. em adição, diversas variáveis ambientais comumente relacionadas à poluição orgânica em ecossistemas aquáticos foram mensuradas; RESULTADOS: Durante as amostragens foram encontrados 11 táxons macroalgais. Chlorophyta foi a divisão predominante (4 espécies ou 36,3% da riqueza total), seguida por Cyanophyta e Rhodophyta (3 ou 27,3%) e Heterokontophyta (1 ou 9,1% do total). A Análise de variância (ANOVA) revelou que não existiram diferenças significativas nos valores de diversidade de espécies, cobertura percentual e índice de diversidade entre as estações do ano ou entre os pontos de amostragem. Além disso...

Longitudinal distribution and seasonality of macroalgae in a subtropical stream impacted by organic pollution

Peres, Cleto Kaveski; Branco, Ciro Cesar Zanini; Krupek, Rogério Antonio; Rocha, José Celso
Fonte: Associação Brasileira de Limnologia Publicador: Associação Brasileira de Limnologia
Tipo: Artigo de Revista Científica Formato: 199-207
ENG
Relevância na Pesquisa
36.09%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); AIM: This study was carried out to assess longitudinal and temporal distribution and the effects of organic pollution on macroalgal communities in a subtropical stream; METHODS: The occurrence and percent cover of stream macroalgae were investigated during seasonal period in four sampling sites along the course of the Cascavel Stream, in Paraná State, subtropical area of Brazil. Sampling sites were randomly chosen; however, their location in relation to urban organic pollution sources was taken into consideration. Besides, several stream variables usually related to organic pollution in aquatic ecosystems were measured; RESULTS: Eleven macroalgal taxa were found during the samplings. Chlorophyta was the prevailing division (4 species or 36.3% of the total richness), followed by Cyanophyta and Rhodophyta (3 or 27.3%) and Heterokontophyta (1 or 9.1%). Analysis of variance (ANOVA) showed no significant differences in species diversity, percent cover and diversity index among seasons or the sampling sites. In addition, species diversity was not correlated with any environmental variable in particular. On the other hand, the relative composition of the stream macroalgal communities showed wide spatial and temporal variation. Thus...

Longitudinal flight control with a variable span morphing wing

Sanches, Tiago Nunes
Fonte: Universidade da Beira Interior Publicador: Universidade da Beira Interior
Tipo: Dissertação de Mestrado
Publicado em /10/2012 EN
Relevância na Pesquisa
36.11%
The present study focuses on the design of a longitudinal flight controller for an unmanned aircraft equipped with dissymmetric variable-span system (VSMW or Variable-Span Morphing Wing). Its primary role consists in the longitudinal flight stabilization of the aeroplane while in levelled cruise flight, although, it was designed to offer longitudinal flight stabilization for other flight phases as well, such as e.g. take-off and landing. The stabilization algorithm relies on the most up-to-date developments in the state-of-the-art LQR and Batz-Kleinman controller techniques to stabilize the aircraft on its intended longitudinal attitude upon any small atmospheric disturbances inflicted. It was designed for the experimental UAV prototype Olharapo equipped with the VSMW, so it can automatically adjust the VSMW overall wingspan in accordance with the flight speed and stabilize the aircraft in the desired attitude, although, its modular concept allows it to be used for different configurations of the aircraft or even for a different aircraft. The development, simulation and testing of the algorithm were done using the MATLAB® software and the aircraft’s stability and control derivatives previously obtained using the XFLR5® software. Minor adaptations of the flight dynamics equations were performed to allow the compatibilization with the VSMW. The required implementation of imposed flight qualities was also performed to ensure proper scaling the controller weight matrix for optimal values. Finally...

Caloric variability of Corbicula fluminea (Mollusca, Bivalvia) in Rosana Reservoir, Brazil

Bagatini,Yara Moretto; Benedito-Cecilio,Evanilde; Higuti,Janet
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
46.04%
The purpose of the present study was to investigate temporal and longitudinal variation of caloric density of Corbicula fluminea in Rosana Reservoir. Significant differences concerning the caloric density of C. fluminea were observed throughout the year at the three reservoir sites. The caloric density variation during the year was probably related to reproductive activity, which demanded higher allocation of energy in certain period. The food source used by this species might be an important factor in the caloric value temporal and spatial variation of C. fluminea in Rosana Reservoir.

Association between common variation at the FTO locus and changes in body mass index from infancy to late childhood: the complex nature of genetic association through growth and development

Sovio, U.; Mook-Kanamori, D.; Warrington, N.; Lawrence, R.; Briollais, L.; Palmer, C.; Cecil, J.; Sandling, J.; Syvanen, A.C.; Kaakinen, M.; Beilin, L.; Millwood, I.; Bennett, A.; Laitneen, J.; Pouta, A.; Molitor, J.; Smith, G.; Ben-Shlomo, Y.; Jaddoe, V.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
36.04%
An age-dependent association between variation at the FTO locus and BMI in children has been suggested. We meta-analyzed associations between the FTO locus (rs9939609) and BMI in samples, aged from early infancy to 13 years, from 8 cohorts of European ancestry. We found a positive association between additional minor (A) alleles and BMI from 5.5 years onwards, but an inverse association below age 2.5 years. Modelling median BMI curves for each genotype using the LMS method, we found that carriers of minor alleles showed lower BMI in infancy, earlier adiposity rebound (AR), and higher BMI later in childhood. Differences by allele were consistent with two independent processes: earlier AR equivalent to accelerating developmental age by 2.37% (95% CI 1.87, 2.87, p = 10−20) per A allele and a positive age by genotype interaction such that BMI increased faster with age (p = 10−23). We also fitted a linear mixed effects model to relate genotype to the BMI curve inflection points adiposity peak (AP) in infancy and AR. Carriage of two minor alleles at rs9939609 was associated with lower BMI at AP (−0.40% (95% CI: −0.74, −0.06), p = 0.02), higher BMI at AR (0.93% (95% CI: 0.22, 1.64), p = 0.01), and earlier AR (−4.72% (−5.81, −3.63)...

Analysis of longitudinal nef sequence variation throughout HIV-2 infection

Remédios, M.; Paixão, E.; Feliciano, H.; Silva-Graça, A.; Pádua, E.
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge, IP
Tipo: Conferência ou Objeto de Conferência
Publicado em 11/03/2010 ENG
Relevância na Pesquisa
46.07%
Abstract publicado em: International Journal of Infectious Diseases. 2010;14(Supl 1).; Background: Human Immunodeficiency Virus type 1 (HIV-1) and type 2 (HIV-2) may case a severe immunodeficiency in humans (AIDS). However HIV-2 is more frequently associated with lower levels of transmission and disease progression, compared with HIV-1 infections. The role of nef gene in vivo during the development of AIDS has been clearly demonstrated in simian immunodeficiency virus infected Rhesus macaques model, but the determinants which play a role in the pathogenesis of HIV are relatively poorly understood. However, even less is known about the role of nef in HIV-2 infections. Methods: In this study, it was analyzed the variation of 48 nef gene sequences, obtained from samples taken between 1994 and 2009, corresponding to 17 HIV-2-infected individuals with different clinical stages of infection. The sequences obtained by Nested PCR were classified by phylogenetic analysis and the functional protein motifs, described as important in CD4 and MHC-I downregulation and in viral infectivity were also analyzed. Results: In all individuals were identified nef sequences from group A of HIV-2, which encoded possible functional and complete protein. There was a greater conservation of residues in the Nef sequences of individuals in the symptomatic stage (63%)...

Longitudinal variation and effects of habitat on biodiversity of Australasian temperate reef fishes

Smith, H.L.; Anderson, M.J.; Gillanders, B.M.; Connell, S.D.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.09%
Aim Latitudinal gradients in marine biodiversity of fishes are well documented but comparatively little is known about longitudinal patterns. The objective of this study was to describe the distributional patterns in biodiversity and assemblage structure of temperate reef-associated fishes in two habitats (kelp forests and open reefs) in each of four regions at comparable latitudes spanning a large longitudinal range (> 5000 km; 117.91° E–174.81° E). Location New Zealand, New South Wales, South Australia and Western Australia. Methods Total abundance, species richness, evenness, average taxonomic distinctness and variation in taxonomic distinctness were calculated from underwater visual counts of individual fish species and were analysed using ANOVA. Compositional change in fish communities was analysed using PERMANOVA and non-metric multi-dimensional scaling at the species level and at the family level. Results Patterns in univariate diversity measures did not show a clear longitudinal gradient and depended on the particular variable being considered. There was, however, a clear longitudinal gradient of turnover in species composition but this disappeared in family-level analyses. The effects of habitat were also relatively stronger in family-level analyses. Main conclusions We propose that ecological communities in similar habitats may be assembled according to a general ‘village hypothesis’...

Longitudinal flight control with a variable span morphing wing

Sanches, Tiago Nunes
Fonte: Universidade da Beira Interior Publicador: Universidade da Beira Interior
Tipo: Dissertação de Mestrado
Publicado em /10/2012 ENG
Relevância na Pesquisa
36.11%
The present study focuses on the design of a longitudinal flight controller for an unmanned aircraft equipped with dissymmetric variable-span system (VSMW or Variable-Span Morphing Wing). Its primary role consists in the longitudinal flight stabilization of the aeroplane while in levelled cruise flight, although, it was designed to offer longitudinal flight stabilization for other flight phases as well, such as e.g. take-off and landing. The stabilization algorithm relies on the most up-to-date developments in the state-of-the-art LQR and Batz-Kleinman controller techniques to stabilize the aircraft on its intended longitudinal attitude upon any small atmospheric disturbances inflicted. It was designed for the experimental UAV prototype Olharapo equipped with the VSMW, so it can automatically adjust the VSMW overall wingspan in accordance with the flight speed and stabilize the aircraft in the desired attitude, although, its modular concept allows it to be used for different configurations of the aircraft or even for a different aircraft. The development, simulation and testing of the algorithm were done using the MATLAB® software and the aircraft’s stability and control derivatives previously obtained using the XFLR5® software. Minor adaptations of the flight dynamics equations were performed to allow the compatibilization with the VSMW. The required implementation of imposed flight qualities was also performed to ensure proper scaling the controller weight matrix for optimal values. Finally...

Análise longitudinal do impacto dos investimentos de tecnologia da informação na eficiência bancária à luz da metodologia DEA

Steffanello, Marinês
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.08%
Os benefícios que a Tecnologia da Informação (TI) tem trazido à sociedade e às organizações vem aumentado ao longo do tempo. A TI tem se desenvolvido com uma rapidez muito grande, prometendo ganhos de eficiência e aumentos na produtividade das empresas. Nos últimos anos, inúmeras organizações têm investido altas quantias em TI, independentemente do setor em que atuam. Dentro deste contexto, observa-se que o setor bancário tem se destacado, pois os recursos destinados para investimentos em TI crescem em ritmo acelerado. Entretanto, a falta de boas medidas quantitativas para mensurar o impacto destes investimentos na produtividade dificulta sua comprovação. Desta forma, fazem-se necessários estudos que apliquem métodos de análise temporal dos investimentos em TI, já que este tipo de investimento não apresenta resultado imediato. Buscando sanar esta lacuna, este trabalho utilizou a metodologia Análise Envoltória de Dados (DEA), que visa analisar eficiência de instituições homogêneas de forma relativa. A partir desta técnica, buscou-se analisar o efeito das variações dos investimentos em TI de um ano para outro nas variações da eficiência relativa dessas instituições em até quatro períodos seguintes ao investimento...

Statistical image analysis of longitudinal RAVENS images

Lee, Seonjoo; Zipunnikov, Vadim; Reich, Daniel S.; Pham, Dzung L.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 20/10/2015 EN
Relevância na Pesquisa
36.03%
Regional analysis of volumes examined in normalized space (RAVENS) are transformation images used in the study of brain morphometry. In this paper, RAVENS images are analyzed using a longitudinal variant of voxel-based morphometry (VBM) and longitudinal functional principal component analysis (LFPCA) for high-dimensional images. We demonstrate that the latter overcomes the limitations of standard longitudinal VBM analyses, which does not separate registration errors from other longitudinal changes and baseline patterns. This is especially important in contexts where longitudinal changes are only a small fraction of the overall observed variability, which is typical in normal aging and many chronic diseases. Our simulation study shows that LFPCA effectively separates registration error from baseline and longitudinal signals of interest by decomposing RAVENS images measured at multiple visits into three components: a subject-specific imaging random intercept that quantifies the cross-sectional variability, a subject-specific imaging slope that quantifies the irreversible changes over multiple visits, and a subject-visit specific imaging deviation. We describe strategies to identify baseline/longitudinal variation and registration errors combined with covariates of interest. Our analysis suggests that specific regional brain atrophy and ventricular enlargement are associated with multiple sclerosis (MS) disease progression.

Benthic insects of the El Tala River (Catamarca, Argentina): longitudinal variation of their structure and the use of insects to assess water quality

Colla,MF; César,II; Salas,LB
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2013 EN
Relevância na Pesquisa
66.12%
The aim of this work was to determine the structure of the benthic entomofauna and its variation along the El Tala River (Catamarca, Argentina). Five sampling stations were established, considering the location of nearby housing with respect to the watercourse. The following variables were determined in situ: altitude, latitude and longitude, bedstream width, river depth, river-current speed, water and air temperatures. Benthic insects were collected with a square parcel sampler of 0.09-m2 area and 300-µm net opening and identified to the family level. Faunal density, richness, and diversity exhibited a longitudinal variation. From sampling Stations 1 (reference site) to 3, the number of orders and families decreased, whereas in sampling Station 4 those values increased and continued to do so through to Station 5 (downstream station). Station 5 showed the highest family richness (17) and the highest value for the Shannon-Wiener index (2.74) and the lowest value in Simpson's Dominance index (D = 0.22). These values could be explained because of the self-cleansing capabilities of the river downstream. The water quality of El Tala River is Class I (very clean and non-impacted), according to the results obtained from the application of the biotic Biological-Monitoring–Working-Party and Average-Store-per-Taxon indices.

Stress-gradient coupling in glacier flow: I. Longitudinal averaging of the influence of ice thickness and surface slope

Kamb, Barclay; Echelmeyer, Keith A.
Fonte: International Glaciological Society Publicador: International Glaciological Society
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em //1986
Relevância na Pesquisa
36.09%
For a glacier flowing over a bed of longitudinally varying slope, the influence of longitudinal stress gradients on the flow is analyzed by means of a longitudinal flow-coupling equation derived from the "vertically" (cross-sectionally) integrated longitudinal stress equilibrium equation, by an extension of an approach originally developed by Budd (1968), Linearization of the flow-coupling equation, by treating the flow velocity u ("vertically" averaged), ice thickness h, and surface slope ɑ in terms of small deviations Δu, Δh, and Aɑ from overall average (datum) values u)0, h_0, and ɑ_0 results in a differential equation that can be solved by Green's function methods, giving Δu(x) as a function of Δh(x) and Δɑ(x), x being the longitudinal coordinate. The result has the form of a longitudinal averaging integral of the influence of local h(x) and ɑ(x) on the flow u(x): Δu(x)= u0/2ℓ ∫^L_0 Δln(ɑ^nƒ^nh^(n+l)exp(-│x' -x│/ℓ)dx' where the integration is over the length L of the glacier. The Δ operator specified deviations from the datum state, and the term on which it operates, which is a function of the integration variable x', represents the influence of local h(x' ), ɑ(x'), and channel-shape factor ƒ(x')...

Variação radial e longitudinal da densidade aparente e estimativa de massa de Toona ciliata; Longitudinal and radial variation of apparent density and mass estimation of Toona ciliata

Silva, Tatiane Antunes da
Fonte: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais Publicador: Universidade Federal de Lavras; Programa de Pós-Graduação em Ciência e Tecnologia da Madeira; UFLA; brasil; Departamento de Ciências Florestais
Tipo: Dissertação
Publicado em 22/12/2015 POR
Relevância na Pesquisa
36.19%
Australian Cedar (Toona ciliata), belongs to the Meliaceae family and has been cultivated in many Brazilian sites. When compared to natural forest species it has fast growth and has been used as an option to substitute native woods, such as mahogany (Swietenia macrophylla) and cedar (Cedrella odorata). The main purpose of this work was to evaluate the variation in apparent density and propose a model for stem mass estimation this study used trees with 52 months old, from plantation areas, in Campo Belo county, Minas Gerais state, Brazil. Two distinct progenies were chosen and had wood discs removed in the following positions from the tree base: 0.15 m, 0.70 m, 1.30 m and 30%, 50%, 70% and 85% of the total height. Wood samples from the disks were collected in order to conduct X-ray densitometry. The X-ray densitometry allowed us to know density variation from pit to bark and from base to top of trees. The density increases from pit to bark. From base to top of the tree, the density decreases up to DBH position and, after that, increases until the top of the tree. The estimated value for mean apparent density was 0.422 g/cm³. Based on the longitudinal variation of apparent density it was possible to propose a model for mass estimation. The model...

Longitudinal variation of basic density of wood of tropical pine species; VARIAÇÃO LONGITUDINAL DA DENSIDADE BÁSICA DA MADEIRA DE ESPÉCIES DE PINUS TROPICAIS

Trianoski, Rosilani; UFPR, Curitiba, PR, Brasil; Matos, Jorge Luis Monteiro; UFPR, Curitiba, PR, Brasil; Iwakiri, Setsuo; UFPR, Curitiba, PR, Brasil; Prata, José Guilherme; UFPR, Curitiba, PR, Brasil
Fonte: FUPEF DO PARANÁ Publicador: FUPEF DO PARANÁ
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 13/09/2013 POR
Relevância na Pesquisa
46.24%
The wood properties knowledge has fundamental importance since it is associated to many processing and using ways. In this context, this paper aims to evaluate longitudinal variation of basic density of wood of tropical pines species. It evaluated seven species of tropical pines: Pinus caribaea var. bahamensis, Pinus caribaea var. caribaea, Pinus caribaea var. hondurensis, Pinus chiapensis, Pinus maximinoi, Pinus oocarpa, Pinus tecunumanii, beyond Pinus taeda (reference), collected in experimental plantations at 17 and 18 years of age, located in the regions of Itararé (SP) and Ventania (PR). Five trees were selected by species, which were sectioned at positions 0%, 25%, 50%, 75% and 100% of the commercial height for samples. Basic density was determined according to the standard 461 of Comisión Panamericana de Normas Técnicas, besides the percentage of latewood, quantified by Windendro software, based on analysis of scanned images of disks of different positions. The results revealed that all species presented low basic density (0.389 to 0.489 g/cm3) with coefficients of variation between 5.09% to 9.77%, and can be considered promising for commercial scale cultivation, in this way increasing the wood supply for different segments of timber industry.; O conhecimento das propriedades da madeira é de fundamental importância...

Longitudinal variation and effect of spacing on basic density wood of Mimosa scabrella and Ateleia glazioveana; VARIAÇÃO LONGITUDINAL E EFEITO DO ESPAÇAMENTO NA MASSA ESPECÍFICA BÁSICA DA MADEIRA DE Mimosa scabrella E Ateleia glazioveana

Eloy, Elder; Universidade Federal do Paraná; Caron, Braulio Otomar; Universidade Federal de Santa Maria; Trevisan, Rômulo; Universidade Federal de Santa Maria; Schmidt, Denise; Universidade Federal de Santa Maria; Zanon, Magda Lea Bolzan; Universidade F
Fonte: FUPEF DO PARANÁ Publicador: FUPEF DO PARANÁ
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 10/05/2013 POR
Relevância na Pesquisa
36.18%
AbstractThis study aimed to evaluate the variation in length and effect of spacing of the basic density of Mimosa scabrella Benth e Ateleia glazioveana Baill, trees with 36 months of age. We analyzed an experiment set up in randomized complete block design with three replications. The treatments were defined by the spacing (2.0x1.0 m, 2.0x1.5 m, 3.0x1.0 m, 3.0x1.5 m). 72 trees were evaluated, and these measures and scaled by the method of Smalian. Then, the disks were removed from the trunk positions: 0.10 m (base), 1.30 m (DAP - diameter at breast height), 25%, 50% and 75% of the total height of the tree, determining the basic density. The basic density in trees of Mimosa scabrella showed a decrease to the region of the DAP, followed by addition, without a tendency to stabilize with time. The Ateleia glazioveana showed a decreasing trend towards bottom-up tree. The spacing influenced the variation of basic density in trees of Mimosa scabrella e Ateleia glazioveana not been verified a systematic positive or negative trend in relation to the living space provided. Keywords: Axial variation; technological characteristic of wood; wood quality; planting space.;  Este trabalho teve como objetivo avaliar a variação longitudinal e o efeito do espaçamento de plantio na massa específica básica das árvores de Mimosa scabrella Benth e Ateleia glazioveana Baill...

Longitudinal variation in the composition of the benthic macroinvertebrate fauna of a typical North coast Jamaican river

Hyslop,Eric. J.; Hunte-Brown,Meshagae
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Benthic macroinvertebrate fauna plays a major role in river ecosystems, especially those of tropical islands. Since there is no information on the distribution of benthic invertebrates along a Jamaican river, we report here on the composition of the benthic fauna of the Buff Bay river, on the Northern coast of Jamaica. A total of 14 samples were collected from five sites, using kick nets and a Surber sampler, between May 1997 and October 1998. We also examined the applicability of the rhithron/potamon model, and some of the premises of the River Continuum Concept (RCC) in relation to the distribution of invertebrate taxa. The results showed a total of 38 taxa of identified invertebrates. A group of dominant taxa, composed mainly of immature stages of insects, occurred at all sites. Two notable characteristics of the river were the absence of a true potamonic fauna and the low representation of the shredder functional feeding group in the community We conclude that, while there was minor variation in the composition of the benthic macroinvertebrate fauna among the sites, this was a response to local conditions within the river system. The characteristics of the community did not conform to either of the models.

Variation throughout the tree stem in the physical-mechanical properties of the wood of Abies alba Mill. from the spanish Pyrenees

González-Rodrigo,Beatriz; Esteban,Luis G.; de Palacios,Paloma; García-Fernández,Francisco; Guindeo,Antonio
Fonte: Instituto de Ecología A.C. Publicador: Instituto de Ecología A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
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This study analyses the variation of main physical-mechanical properties of wood along the longitudinal and radial directions of the tree for Abies alba Mill. growing in the Spanish Pyrenees. Small clear specimens were used to study the properties of volumetric shrinkage (VS), density (ρ), hardness (H), bending strength (MOR), modulus of elasticity (MOE), maximum compressive strength parallel to the grain (MCS) and impact strength (K). Several models of properties variation in the longitudinal and radial directions were analyzed. Main trends of variation of properties throughout the tree stem were identified although none of them could be fitted to predictive statistical models. Along the longitudinal direction, the properties studied followed a downward trend from the base to the crown, which was not significant in all cases, indicating that no differences in quality existed. Throughout the radial direction the trend is upward for the first 40-50 growth rings, after which it slopes downwards, more gently at first until rings 70-75 and then more steeply. This behaviour is related to variation in wood structure from the pith to the bark, depending on whether the wood is juvenile, sapwood or heartwood, and to wood maturity and microfibril angle. Authors encourage carrying further studies on other populations of A. alba in the Spanish Pyrenees to check if the trends found in this study apply to other provenances.