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Author |
Yamamoto, H.; Almeras, T. |
Title |
A mathematical verification of the reinforced-matrix hypothesis using the Mori-Tanaka theory |
Type |
Journal Article |
Year |
2007 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Journal of Wood Science |
Abbreviated Journal |
J. Wood Sci. |
Volume |
53 |
Issue |
6 |
Pages |
505-509 |
Keywords |
Engineering |
Abstract |
This article presents a theoretical verification of the reinforced-matrix hypothesis derived from tensor equations, σ W = σ f + σ m and ε W = ε f = ε m (Wood Sci Technol 32:171–182, 1998; Wood Sci Technol 33:311–325, 1999; J Biomech Eng 124:432–440, 2002), using classical Mori-Tanaka theory on the micromechanics of fiber-reinforced materials (Acta Metall 21:571–574, 1973; Micromechanics — dislcation and inclusions (in Japanese), pp 141–147, 1976). The Mori-Tanaka theory was applied to a small fragment of the cell wall undergoing changes in its physical state, such as those arising from sorption of moisture, maturation of wall components, or action of an external force, to obtain 〈σ A〉D = ϕ·〈σ F〉I + (1−ϕ)·〈σ M〉D−I. When the constitutive equation of each constituent material was applied to the equation 〈σ A〉D = ϕ·〈σ F〉I + (1−ϕ)·〈σ M〉D−I, the equations σ W = σ f + σ m and ε W = ε f = ε m were derived to lend support to the concept that two main phases, the reinforcing cellulose microfibril and the lignin-hemicellulose matrix, coexist in the same domain. The constitutive equations for the cell wall fragment were obtained without recourse to additional parameters such as Eshelby’s tensor S and Hill’s averaged concentration tensors AF and AM. In our previous articles, the coexistence of two main phases and σ W = σ f + σ m and ε W = ε f =ε m had been taken as our starting point to formulate the behavior of wood fiber with multilayered cell walls. The present article provides a rational explanation for both concepts. |
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Springer Japan |
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1435-0211 |
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EcoFoG @ eric.marcon @ |
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215 |
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Almeras, T.; Yoshida, M.; Okuyama, T. |
Title |
The generation of longitudinal maturation stress in wood is not dependent on diurnal changes in diameter of trunk |
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Journal Article |
Year |
2006 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Journal of Wood Science |
Abbreviated Journal |
J. Wood Sci. |
Volume |
52 |
Issue |
5 |
Pages |
452-455 |
Keywords |
maturation stress; growth stress; cell-wall maturation; continuous lighting; diurnal strains |
Abstract |
A hypothetical mechanism for the generation of maturation stress in wood was tested experimentally. The hypothesis was that the maturation stress could partly originate in a physical mechanism related to daily changes in water pressure and associated diurnal strains. The matrix of lignin and hemicellulose, deposited in the cell wall during the night, would be put in compression by the effect of water tension during the next day. The cellulose framework, crystallizing during the day, would be put in tension by the decrease in tension at night and subsequent cell-wall swelling. This was tested on young saplings of sugi and beech. Half of the saplings were submitted to continuous lighting, which canceled diurnal strains. Saplings were tilted 40 degrees, and their uprighting movement was measured. The uprighting movement is directly due to the production of reaction wood and the concomitant development of large longitudinal maturation stress. It occurred in the continuously lighted plants at least as much as in control plants. We conclude that the generation of longitudinal maturation stress in tension or compression wood is not directly related to variations in water pressure and diurnal strains. |
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Nagoya Univ, Grad Sch Bioagr Sci, Lab Biomat Phys, Chikusa Ku, Nagoya, Aichi 4648601, Japan, Email: t_almeras@hotmail.com |
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SPRINGER TOKYO |
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1435-0211 |
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ISI:000241010600012 |
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EcoFoG @ eric.marcon @ |
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222 |
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Zhang, T.; Bai, S.-L.; Bardet, S.; Almeras, T.; Thibaut, B.; Beauchene, J. |
Title |
Radial variations of vibrational properties of three tropical woods |
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Journal Article |
Year |
2011 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Journal of Wood Science |
Abbreviated Journal |
J. Wood Sci. |
Volume |
57 |
Issue |
5 |
Pages |
377-386 |
Keywords |
Damping coefficient; Dynamic modulus; Extractives; Microfibril angle; Tropical woods |
Abstract |
The radial trends of vibrational properties, represented by the specific dynamic modulus (E′/ρ) and damping coefficient (tan δ), were investigated for three tropical rainforest hardwood species (Simarouba amara, Carapa procera, and Symphonia globulifera) using free-free flexural vibration tests. The microfibril angle (MFA) was estimated using X-ray diffraction. Consistent patterns of radial variations were observed for all studied properties. E′/ρ was found to decrease from pith to bark, which was strongly related to the increasing pith-bark trend of MFA. The variation of tan δ along the radius could be partly explained by MFA and partly by the gradient of extractives due to heartwood formation. The coupling effect of MFA and extractives could be separated through analysis of the log(tan δ) versus log(E′/ρ) diagram. For the species studied, the extractive content putatively associated with heartwood formation generally tends to decrease the wood damping coefficient. However, this weakening effect of extractives was not observed for the inner part of the heartwood, suggesting that the mechanical action of extractives was reduced during their chemical ageing. © 2011 The Japan Wood Research Society. |
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CIRAD, UMR Ecofog, BP 701, 97387 Kourou Cedex, Guyane Française, France |
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14350211 (Issn) |
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Export Date: 26 October 2011; Source: Scopus; Coden: Jwscf; doi: 10.1007/s10086-011-1189-7; Language of Original Document: English; Correspondence Address: Bai, S.-L.; Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China; email: slbai@pku.edu.cn |
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EcoFoG @ webmaster @ |
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363 |
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Gibson, J.C.; Larabee, F.J.; Touchard, A.; Orivel, J.; Suarez, A.V. |
Title |
Mandible strike kinematics of the trap-jaw ant genus Anochetus Mayr (Hymenoptera: Formicidae) |
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Journal Article |
Year |
2018 |
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Journal of Zoology |
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Volume |
306 |
Issue |
2 |
Pages |
119-128 |
Keywords |
catapult mechanism; comparative biomechanics; Formicidae; functional morphology; kinematics; mandible strike; power amplification |
Abstract |
High-speed power-amplification mechanisms are common throughout the animal kingdom. In ants, power-amplified trap-jaw mandibles have evolved independently at least four times, including once in the subfamily Ponerinae which contains the sister genera Odontomachus and Anochetus. In Odontomachus, mandible strikes have been relatively well described and can occur in <0.15 ms and reach speeds of over 60 m s−1. In contrast, the kinematics of mandible strikes have not been examined in Anochetus, whose species are smaller and morphologically distinct from Odontomachus. In this study, we describe the mandible strike kinematics of four species of Anochetus representative of the morphological, phylogenetic, and size diversity present within the genus. We also compare their strikes to two representative species of Odontomachus. We found that two species, Anochetus targionii and Anochetus paripungens, have mandible strikes that overall closely resemble those found in Odontomachus, reaching a mean maximum rotational velocity and acceleration of around 3.7 × 104 rad s−1 and 8.5 × 108 rad s−2, respectively. This performance is consistent with predictions based on body size scaling relationships described for Odontomachus. In contrast, Anochetus horridus and Anochetus emarginatus have slower strikes relative to the other species of Anochetus and Odontomachus, reaching mean maximum rotational velocity and acceleration of around 1.3 × 104 rad s−1 and 2 × 108 rad s−2, respectively. This variation in strike performance among species of Anochetus likely reflects differences in evolutionary history, physiology, and natural history among species. © 2018 The Zoological Society of London |
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Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States |
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Export Date: 15 October 2018 |
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EcoFoG @ webmaster @ |
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826 |
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Perz, S.G.; Qiu, Y.; Xia, Y.; Southworth, J.; Sun, J.; Marsik, M.; Rocha, K.; Passos, V.; Rojas, D.; Alarcón, G.; Barnes, G.; Baraloto, C. |
Title |
Trans-boundary infrastructure and land cover change: Highway paving and community-level deforestation in a tri-national frontier in the Amazon |
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Journal Article |
Year |
2013 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Land Use Policy |
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34 |
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27-41 |
Keywords |
Amazon; Brazil, Peru; Globalization; Infrastructure; Land |
Abstract |
Economic globalization manifests in landscapes through regional integration initiatives involving trans-boundary infrastructure. While the relationships of roads, accessibility and land cover are well-understood, they have rarely been considered across borders in national frontier regions. We therefore pursue an analysis of infrastructure connectivity and land cover change in the tri-national frontier of the southwestern Amazon where Bolivia, Brazil and Peru meet, and where the Inter-Oceanic Highway has recently been paved. We integrate satellite, survey, climate and other data for a sample of rural communities that differ in terms of highway paving across the tri-national frontier. We employ a suite of explanatory variables tied to road paving and other factors that vary both across and within the three sides of the frontier in order to model their importance for deforestation. A multivariate analysis of non-forest land cover during 2005-2010 confirms the importance of paving status and travel times, as well as land tenure and other factors. These findings indicate that integration affects land cover, but does not eliminate the effects of other factors that vary across the frontier, which bears implications for the study of globalization, trans-boundary infrastructure, environmental governance and land cover change. © 2013 Elsevier Ltd. |
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Department of Biology, University of Florida, Gainesville, FL 32611, United States |
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Export Date: 14 March 2013; Source: Scopus |
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EcoFoG @ webmaster @ |
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475 |
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Talaga, S.; Petitclerc, F.; Carrias, J.-F.; Dezerald, O.; Leroy, C.; Céréghino, R.; Dejean, A. |
Title |
Environmental drivers of community diversity in a neotropical urban landscape: a multi-scale analysis |
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Journal Article |
Year |
2017 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Landscape Ecology |
Abbreviated Journal |
Landscape Ecology |
Volume |
32 |
Issue |
9 |
Pages |
1805-1818 |
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Aquatic metacommunity; Landscape ecology; Mosquitoes; Neotropics; Scale dependency; Tank bromeliads; Urban ecology |
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Context: Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem. Objectives: To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape. Methods: Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses. Results: We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator. Conclusions: The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning. © 2017, Springer Science+Business Media B.V. |
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IRD; UMR AMAP (botAnique et Modélisation de l’Architecture des Plantes et des végétations), Boulevard de la Lironde, TA A‐51/PS2, Montpellier Cedex 5, France |
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Export Date: 18 December 2017 |
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EcoFoG @ webmaster @ |
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777 |
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Leba, L.-J.; Musset, L.; Pelleau, S.; Estevez, Y.; Birer, C.; Briolant, S.; Witkowski, B.; Ménard, D.; Delves, M.J.; Legrand, E.; Duplais, C.; Popovici, J. |
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Use of Plasmodium falciparum culture-adapted field isolates for in vitro exflagellation-blocking assay |
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Journal Article |
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2015 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Malaria Journal |
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Malaria Journal |
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14 |
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234 |
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Background: A major requirement for malaria elimination is the development of transmission-blocking interventions. In vitro transmission-blocking bioassays currently mostly rely on the use of very few Plasmodium falciparum reference laboratory strains isolated decades ago. To fill a piece of the gap between laboratory experimental models and natural systems, the purpose of this work was to determine if culture-adapted field isolates of P. falciparum are suitable for in vitro transmission-blocking bioassays targeting functional maturity of male gametocytes: exflagellation. Methods: Plasmodium falciparum isolates were adapted to in vitro culture before being used for in vitro gametocyte production. Maturation was assessed by microscopic observation of gametocyte morphology over time of culture and the functional viability of male gametocytes was assessed by microscopic counting of exflagellating gametocytes. Suitability for in vitro exflagellation-blocking bioassays was determined using dihydroartemisinin and methylene blue. Results: In vitro gametocyte production was achieved using two isolates from French Guiana and two isolates from Cambodia. Functional maturity of male gametocytes was assessed by exflagellation observations and all four isolates could be used in exflagellation-blocking bioassays with adequate response to methylene blue and dihydroartemisinin. Conclusion: This work shows that in vitro culture-adapted P. falciparum field isolates of different genetic background, from South America and Southeast Asia, can successfully be used for bioassays targeting the male gametocyte to gamete transition, exflagellation. © 2015 Leba et al. |
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Department of Life Sciences, Imperial College, London, United Kingdom |
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Export Date: 16 July 2015 |
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EcoFoG @ webmaster @ |
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612 |
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Petit, M.; Denis, T.; Rux, O.; Richard-Hansen, C.; Berzins, R. |
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Estimating jaguar (Panthera onca) density in a preserved coastal area of French Guiana |
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Journal Article |
Year |
2018 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Mammalia |
Abbreviated Journal |
Mammalia |
Volume |
82 |
Issue |
2 |
Pages |
188-192 |
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camera trapping; density; French Guiana; home range; Panthera onca; spatially explicit capture recapture |
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Knowledge of the jaguar population is needed in French Guiana that faces an increase of human-jaguar conflicts. We carried out a camera trap survey to assess jaguar local density and home range size in a preserved coastal area of French Guiana. We ran spatially explicit capture recapture (SECR) models. In our model, the scale parameter σ, that is linked to the home range size, was larger for males (σ=3.87±0.59 SE km) than for females (σ=2.33±0.30 SE km). The assessed jaguar density was 3.22±0.87 SE ind. 100 km â '2, which should be considered as an optimal density in a French Guiana coastal area. |
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Office National de la Chasse et de la Faune Sauvage, Campus Agronomique, BP316, Kourou Cedex, French Guiana |
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Export Date: 7 May 2018 |
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EcoFoG @ webmaster @ |
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803 |
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Mathieu, A.; Letort, V.; Cournède, P.H.; Zhang, B.G.; Heuret, P.; De Reffye, P. |
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Oscillations in functional structural plant growth models |
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Journal Article |
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2012 |
Publication ![sorted by Publication field, ascending order (up)](img/sort_asc.gif) |
Mathematical Modelling of Natural Phenomena |
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7 |
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6 |
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47-66 |
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Cecropia trees; Cucumber plant; Dynamic system of plant growth; Functional-structural plant models; GreenLab |
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The dynamic model of plant growth GreenLab describes plant architecture and functional growth at the level of individual organs. Structural development is controlled by formal grammars and empirical equations compute the amount of biomass produced by the plant, and its partitioning among the growing organs, such as leaves, stems and fruits. The number of organs initiated at each time step depends on the trophic state of the plant, which is evaluated by the ratio of biomass available in plant to the demand of all the organs. The control of the plant organogenesis by this variable induces oscillations in the simulated plant behaviour. The mathematical framework of the GreenLab model allows to compute the conditions for the generation of oscillations and the value of the period according to the set of parameters. Two case-studies are presented, corresponding to emergence of oscillations associated to fructification and branching. Similar alternating patterns are commonly reported by botanists. In this article, two examples were selected: alternate patterns of fruits in cucumber plants and alternate appearances of branches in Cecropia trees. The model was calibrated from experimental data collected on these plants. It shows that a simple feedback hypothesis of trophic control on plant structure allows the emergence of cyclic patterns corresponding to the observed ones. © EDP Sciences, 2012. |
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CIRAD, UMR AMAP, Montpellier, France |
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Export Date: 27 December 2012; Source: Scopus |
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EcoFoG @ webmaster @ |
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452 |
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Campillo, F.; Rakotozafy, R.; Rossi, V. |
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Parallel and interacting Markov chain Monte Carlo algorithm |
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2009 |
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Mathematics and Computers in Simulation |
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Math. Comput. Simul. |
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79 |
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12 |
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3424-3433 |
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Markov chain Monte Carlo method; Interacting chains; Hidden Markov model |
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In many situations it is important to be able to propose N independent realizations of a given distribution law. We propose a strategy for making N parallel Monte Carlo Markov chains (MCMC) interact in order to get an approximation of an independent N-sample of a given target law. In this method each individual chain proposes candidates for all other chains. We prove that the set of interacting chains is itself a MCMC method for the product of N target measures. Compared to independent parallel chains this method is more time consuming. but we show through examples that it possesses many advantages. This approach is applied to a biomass evolution model. (C) 2009 IMACS. Published by Elsevier B.V. All rights reserved. |
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[Rossi, Vivien] CIRAD, Res Unit, Montpellier, France, Email: Fabien.Campillo@inria.fr |
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ELSEVIER SCIENCE BV |
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0378-4754 |
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ISI:000269289100006 |
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EcoFoG @ eric.marcon @ |
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197 |
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