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Architectural Parameters (architectural + parameter)
Selected AbstractsSimulation of the three-dimensional distribution of the red:far-red ratio within crop canopiesNEW PHYTOLOGIST, Issue 1 2007Michaël Chelle Summary ,,It is widely recognized that the red:far-red ratio (,) acts as a signal that triggers plant morphogenesis. New insights into photomorphogenesis have been gained through experiments in controlled environments. Extrapolation of such results to field conditions requires characterization of the , signal perceived by plant organs within canopies. This paper presents a modeling approach to characterize this signal. ,,A wheat (Triticum aestivum) architectural model was coupled with a three-dimensional light model estimating the irradiances of virtual sensors. Architectural parameters and , values were measured on two contrasting spring wheat canopies under outdoor conditions. Light simulations were compared with measurements, and an analysis of sensitivity to measurement conditions was carried out. ,,The model results agreed well with measurements and previously published data. The sensitivity analysis showed that , strongly depends on canopy development as well as on sky conditions, sensor orientation, and sensor field of view. ,,This paper shows that modeling enables investigation of , distribution in a canopy over space and time. It also shows that the characterization of light quality strongly depends on measurement conditions, and that any discrepancies in results are likely attributable to different experimental set-ups. The usefulness of this modeling approach for crop photomorphogenesis studies is discussed. [source] Architectural properties of the first dorsal interosseous muscleJOURNAL OF ANATOMY, Issue 4 2010Benjamin W. Infantolino Abstract Muscle architecture is considered to reflect the function of muscle in vivo, and is important for example to clinicians in designing tendon-transfer and tendon-lengthening surgeries. The purpose of this study was to quantify the architectural properties of the FDI muscle. It is hypothesized that there will be consistency, that is low variability, in the architectural parameters used to describe the first dorsal interosseous muscle because of its clear functional role in index finger motion. The important architectural parameters identified were those required to characterize a muscle adequately by modeling. Specifically the mass, cross-sectional area, and length of the tendon and muscle were measured in cadavers along with the muscle fiber optimum length and pennation angle, and the moment arm of the first dorsal interosseous at the metacarpophalangeal joint. These parameters provide a characterization of the architecture of the first dorsal interosseous, and were used to indicate the inherent variability between samples. The results demonstrated a large amount of variability for all architectural parameters measured; leading to a rejection of the hypothesis. Ratios designed to describe the functioning of the muscles in vivo, for example the ratio of tendon to fiber optimum lengths, also demonstrated a large variability. The results suggest that function cannot be deduced from form for the first dorsal interosseous, and that subject-specific architectural parameters may be necessary for the formulation of accurate musculoskeletal models or making clinical decisions. [source] Long-Term Protective Effects of Zoledronic Acid on Cancellous and Cortical Bone in the Ovariectomized Rat,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2008Jürg A Gasser PhD Abstract Current bisphosphonate therapies effectively prevent bone loss in postmenopausal women. We studied the effect of a single intravenous dose of ZOL in ovariectomized rats. Protection from bone loss was dose dependent, lasting for up to 32 weeks, supporting the rationale for an annual intravenous dosing regimen of ZOL for treatment of postmenopausal osteoporosis. Introduction: Once-yearly dosing with zoledronic acid (ZOL) 5 mg can increase BMD and reduce fracture rate in postmenopausal women with low BMD. The primary objective of this study was to determine the duration of bone protective effects of a single dose of ZOL in ovariectomized rats, an animal model of postmenopausal osteopenia. Secondary objectives were to determine the effects on bone turnover and mechanical properties. Materials and Methods: Female Wistar rats (10 per group) received single intravenous doses of ZOL 0.8, 4, 20, 100, or 500 ,g/kg, alendronate 200 ,g/kg, or isotonic saline 4 days before bilateral ovariectomy. Sham-operated controls were pretreated with saline. Mass and density of cancellous and cortical bone (pQCT) were measured at 4-wk intervals for 32 wk. Bone architecture (,CT), bone formation dynamics (fluorochrome label-based histomorphometry), and biomechanical strength in compression testing were also assessed at 32 wk. Results: Ovariectomy-associated BMD loss was significantly attenuated for 32 wk by ZOL ,4 ,g/kg for total BMD, ZOL ,20 ,g/kg for cortical BMD, and ZOL ,4 ,g/kg for cancellous BMD (p < 0.01 versus ovariectomized controls). Alendronate 200 ,g/kg was of equivalent potency to ZOL 20 ,g/kg. Ovariectomy-associated decreases in trabecular architectural parameters were dose-dependently attenuated by ZOL. Alendronate 200 ,g/kg was equivalent to ZOL 20 ,g/kg. The bone resorption marker TRACP5b indicated transient suppression of elevated osteoclast activity by ZOL relative to OVX-rats even at the lowest dose of 0.8 ,g/kg, whereas at 100,500 ,g/kg, the effect was significant relative to the OVX control for the entire duration of the study of 32 wk. Bone formation parameters were not significantly affected by ZOL 20 ,g/kg but were significantly reduced by ZOL 100,500 ,g/kg. Alendronate 200 ,g/kg was equivalent to ZOL 100 ,g/kg. ZOL produced dose-related improvements in bone strength parameters after ovariectomy. Alendronate 200 ,g/kg was of similar potency to ZOL 20 ,g/kg. Conclusions: The duration and magnitude of the bone-protecting effect of a single intravenous dose of ZOL in ovariectomized rats is dose dependent and lasts for up to 32 wk. Compared with alendronate, ZOL shows 10-fold higher potency in preventing bone loss. These data support the use of an annual intravenous ZOL dosing regimen for the treatment of osteoporosis. [source] What youngsters say about adults: seedling roots reflect clonal traits of adult plantsJOURNAL OF ECOLOGY, Issue 3 2007MARIE, MILAUEROVÁ Summary 1Grime's theory on plant strategies predicts that the set of traits present in established plants is not correlated with that found in the regenerative stage of the life cycle. We tested this prediction and further investigated whether clonal growth traits, which are found in adult plants but also affect regeneration, are correlated with seedling traits. 2We characterized seedling root systems by their total length, number of root tips and several architectural parameters (length of exterior and interior root links and two topological indices). These below-ground traits were supplemented by the ratio of leaf area to root length, representing relative investment into photosynthesizing surface. We compared seedling traits with clonal growth traits, adult plant heights, and species positions on gradients of nitrogen and water availability. 3Plant species with limited horizontal spread by clonal growth exhibited a larger relative investment in photosynthetic area and also developed larger root systems as seedlings. 4Seedlings of species with taller shoots and those which occur naturally at nutrient-rich sites developed both larger roots and more dichotomously branched root systems (with higher total length and more branches). 5Taking phylogenetic inertia into account showed that this explained large parts of the variation in seedling traits. Relationships between clonal spread and seedling traits were strengthened by phylogenetic correction. 6Our study shows that some of the traits of clonal growth affect both the established and the regenerative stages of the life cycle, suggesting that an evolutionary trade-off exists between the ability to spread clonally and performance at the seedling stage. Species not able to escape from less favourable conditions by extensive clonal spread seem to be more able to exploit the location in which they germinate. [source] State of the art and future directions of scaffold-based bone engineering from a biomaterials perspectiveJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 4 2007Dietmar Werner Hutmacher Abstract Scaffold-based bone tissue engineering aims to repair/regenerate bone defects. Such a treatment concept involves seeding autologous osteogenic cells throughout a biodegradable scaffold to create a scaffold,cell hybrid that may be called a tissue-engineered construct (TEC). A variety of materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past two decades. This review aims to discuss the advances in bone engineering from a scaffold material point of view. In the first part the reader is introduced to the basic principles of bone engineering. The important properties of the biomaterials and the scaffold design in the making of tissue engineered bone constructs are discussed in detail, with special emphasis placed on the new material developments, namely composites made of synthetic polymers and calcium phosphates. Advantages and limitations of these materials are analysed along with various architectural parameters of scaffolds important for bone tissue engineering, e.g. porosity, pore size, interconnectivity and pore-wall microstructures. Copyright © 2007 John Wiley & Sons, Ltd. [source] Documentation and three-dimensional modelling of human soleus muscle architectureCLINICAL ANATOMY, Issue 4 2003Anne M. Agur Abstract The purpose of this study was to visualize and document the architecture of the human soleus muscle throughout its entire volume. The architecture was visualized by creating a three-dimensional (3D) manipulatable computer model of an entire cadaveric soleus, in situ, using B-spline solid to display muscle fiber bundles that had been serially dissected, pinned, and digitized. A database of fiber bundle length and angle of pennation throughout the marginal, posterior, and anterior soleus was compiled. The computer model allowed documentation of the architectural parameters in 3D space, with the angle of pennation being measured relative to the tangent plane of the point of attachment of a fiber bundle. Before this study, the only architectural parameters that have been recorded have been 2D. Three-dimensional reconstruction is an exciting innovation because it makes feasible the creation of an architectural database and allows visualization of each fiber bundle in situ from any perspective. It was concluded that the architecture is non-uniform throughout the volume of soleus. Detailed architectural studies may lead to the development of muscle models that can more accurately predict interaction between muscle parts, force generation, and the effect of pathologic states on muscle function. Clin. Anat. 16:285,293, 2003. © 2003 Wiley-Liss, Inc. [source] | |||||||||||||