Home About us Contact
|
Home About us Contact | ||
|
|
||
Structural Components (structural + component)
Kinds of Structural Components Selected AbstractsThree-Dimensional Serial Section Computer Reconstruction of the Arrangement of the Structural Components of the Parabronchus of the Ostrich, Struthio Camelus LungTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 11 2009John N. Maina ,Cubed' three-dimensional computer reconstruction (from serial sections) of the exchange tissue (parenchyma) of the lung of the ostrich, Struthio camelus showing the profuse anastomoses of the air capillaries (shown in cyan) and the blood capillaries (shown in red). While the two terminal respiratory units interdigitate very copiously as they interface intimately, thereby optimizing the respiratory surface area, regarding their size and shape, they are not mirror images as has previously been reported nor do they spatially form a counter-current arrangement, as they have been commonly modelled. See Maina et al., "Three-Dimensional Serial Section Computer Reconstruction of the Arrangement of the Structural Components of the Parabronchus of the Ostrich, Struthio Camelus Lung," on page 1685, in this issue. [source] Characterization of New PPAR, Agonists: Analysis of Telmisartan's Structural ComponentsCHEMMEDCHEM, Issue 3 2009Matthias Goebel Abstract Telmisartan was originally designed as an AT1 antagonist but was later also characterized as a selective PPAR, modulator. This study focused on the identification of the essential structural motifs of telmisartan for PPAR, activation activity, elucidating the individual SAR of each different component (shown). In addition to a proven efficacy in lowering blood pressure, the AT1 receptor blocker telmisartan has recently been shown to exert pleiotropic effects as a partial agonist of the nuclear peroxisome proliferator-activated receptor gamma (PPAR,). Based on these findings and an excellent side-effect profile, telmisartan may serve as a lead structure for the development of new PPAR, ligands. Therefore, we analyzed the structural components of telmisartan to identify those necessary for PPAR, activation. Synthesized compounds were tested in a differentiation assay using 3T3-L1 preadipocytes and a luciferase assay with COS-7 cells transiently transfected with pGal4-hPPAR,DEF, pGal5-TK-pGL3 and pRL-CMV. The data obtained in this structure,activity relationship (SAR) study provide the basis for the development of new PPAR, ligands, which could lead to active compounds with a distinct, beneficial pharmacological profile compared with the existing full agonists. The basic 1-(biphenyl-4-ylmethyl)-1H -benzimidazole scaffold of telmisartan was identified as an essential moiety with either a carboxylic acid or tetrazole group at the C-2 position of the biphenyl. For maximum potency and activity, the alkyl chain in position 2 requires a minimum length of at least two C atoms (ethyl group), while the methyl group at position 4 of the benzimidazole core seems to contribute to partial activity. An additional benzimidazole at position 6 appears to be a further determinant of potency. Similar conclusions can be drawn for the methyl group in position 1. [source] Innendämmung bei erhaltenswerten Fassaden , ein baukonstruktives ProjektbeispielBAUPHYSIK, Issue 4 2009Leiter des Instituts für Angewandte Bautechnik Hans-Jürgen Holle Prof. Dr.-Ing. habil. Gebäudebestand; Energieeinsparung; reconstruction; energy performance Abstract Die Sanierung eines gründerzeitlichen Wohngebäudes in Hamburg aus dem Jahre 1907 mit erhaltenswerter Fassade wurde im Rahmen des Forschungsvorhabens "Energetische Sanierung" (EnSan) des Bundesministeriums für Wirtschaft und Technologie gefördert und wissenschaftlich begleitet. Zwei baugleiche Gebäudehälften wurden mit unterschiedlichen energetischen Sanierungskonzepten und -standards ("EnSan-Standard" und "Hamburger Standard") geplant und realisiert. Es wurden Konstruktionen einschließlich der dafür erforderlichen Einbauabläufe entwickelt. Die energetischen Zielgrößen sind erreicht worden. Der Endenergieverbrauch für Beheizung wurde um 80 % auf 32 kWh/m2a gesenkt. Der Primärenergieverbrauch beträgt gemittelt für beide Gebäudehälften ca. 95 kWh/m2a. Internal insulation of façades that are worth preserving. Example of a structural design project. The refurbishment of a residential buildings in Hamburg built in 1907 during the Wilhelminian era with a façade that was deemed worthy of preservation was funded as part of the research project "Energy-efficient refurbishment" (EnSan) by the German Federal Ministry of Economic Affairs and Technology, which also provided scientific backup. Two identical building parts were refurbished based on different energy-efficiency concepts and standards ("EnSan standard" and "Hamburg standard"). Structural components and associated installation procedures were developed. The energy target values were achieved. The heating energy end use was reduced by 80 % to 32 kWh/m2a. The average primary energy consumption for both building parts is approx. 95 kWh/m2a. [source] Assessment of Protection Systems for Buried Steel Pipelines Endangered by RockfallCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2005Bernhard Pichler First, a gravel-based protection system (GBPS) is investigated, that is, a pipeline buried in sandy gravel is considered. To assess the load-carrying behavior of this structure when subjected to rockfall, a finite element (FE) model has been developed. The development and the validation of this structural model are strictly separated, that is, they are based on two physically and statistically independent sets of experiments. Subsequently, scenarios of rockfall onto a gravel-buried steel pipe are analyzed considering different boundary conditions and structural dimensions. Following the conclusions drawn from these numerical analyses, an enhanced protection system (EPS) is proposed. It consists of gravel as an energy-absorbing and impact-damping system and a buried steel plate resting on walls made of concrete representing a load-carrying structural component. The potential and the limitations of both protection systems are discussed in detail. [source] Axonemal localization of Chlamydomonas PACRG, a homologue of the human Parkin -coregulated gene productCYTOSKELETON, Issue 11 2007Kazuho Ikeda Abstract A homologue of mammalian PACRG was identified in Sarkosyl-extracted Chlamydomonas axonemes as a protein that may interact with Rib72 (a component of the protofilament ribbon within the outer doublet microtubules). PACRG is a protein whose expression is co-regulated with the Parkin gene implicated in Parkinson's disease. Although subsequent analyses did not confirm a Rib72-PACRG interaction, both proteins display similar localization in the axoneme. Immuno-localization of PACRG required pretreatment of the axoneme with Sarkosyl, suggesting that the antigen is buried in the wall of the microtubule. Indirect immunofluorescence localized PACRG to the entire length of the axoneme and the basal body, and immuno-electron microscopy showed that the PACRG antigen is densely distributed along the outer doublets in frayed axonemes. In thin-section images, the PACRG signals were frequently found between the A- and B-tubules of adjacent outer doublets. From these and other results, we propose that PACRG is a structural component of the doublet and triplet microtubules possibly involved in inter-tubule linkage. Cell Motil. Cytoskeleton, 2007. © 2007 Wiley-Liss, Inc. [source] A design-variable-based inelastic hysteretic model for beam,column connectionsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2008Gun Jin Yun Abstract This paper presents a design-variable-based inelastic hysteretic model for beam,column connections. It has been well known that the load-carrying capacity of connections heavily depends on the types and design variables even in the same connection type. Although many hysteretic connection models have been proposed, most of them are dependent on the specific connection type with presumed failure mechanisms. The proposed model can be responsive to variations both in design choices and in loading conditions. The proposed model consists of two modules: physical-principle-based module and neural network (NN)-based module in which information flow from design space to response space is formulated in one complete model. Moreover, owing to robust learning capability of a new NN-based module, the model can also learn complex dynamic evolutions in response space under earthquake loading conditions, such as yielding, post-buckling and tearing, etc. Performance of the proposed model has been demonstrated with synthetic and experimental data of two connection types: extended-end-plate and top- and seat-angle with double-web-angle connection. Furthermore, the design-variable-based model can be customized to any structural component beyond the application to beam,column connections. Copyright © 2007 John Wiley & Sons, Ltd. [source] Chitin induces upregulation of B7-H1 on macrophages and inhibits T-cell proliferationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2010Claudia J. Wagner Abstract Chitin is a highly abundant glycopolymer, which serves as structural component in fungi, arthropods and crustaceans but is not synthesized by vertebrates. However, vertebrates express chitinases and chitinase-like proteins, some of which are induced by infection with helminths suggesting that chitinous structures may be targets of the immune system. The chitin-induced modulations of the innate and adaptive immune responses are not well understood. Here, we demonstrate that intranasal administration of OVA and chitin resulted in diminished T-cell expansion and Th2 polarization as compared with OVA administration alone. Chitin did not promote nor attenuate Th2 polarization in vitro. Chitin-exposed macrophages inhibited proliferation of CD4+ T cells in a cell,cell contact-dependent manner. Chitin induced upregulation of the inhibitory ligand B7-H1 (PD-L1) on macrophages independently of MyD88, TRIF, TLR2, TLR3, TLR4 and Stat6. Inhibition of T-cell proliferation was largely dependent on B7-H1, as the effect was not observed in cocultures with cells from B7-H1-deficient mice. [source] Evolution and phylogenetic relationships of chitin synthases from yeasts and fungiFEMS YEAST RESEARCH, Issue 4 2002José Ruiz-Herrera Abstract Chitin, the structural component that provides rigidity to the cell wall of fungi is the product of chitin synthases (Chs). These enzymes are not restricted to fungi, but are amply distributed in four of the five eukaryotic ,crown kingdoms'. Dendrograms obtained by multiple alignment of Chs revealed that fungal enzymes can be classified into two divisions that branch into at least five classes, independent of fungal divergence. In contrast, oomycetes and animals each possess a single family of Chs. These results suggest that Chs originated as a branch of ,-glycosyl-transferases, once the kingdom Plantae split from the evolutionary line of eukaryotes. The existence of a single class of Chs in animals and Stramenopiles, against the multiple families in fungi, reveals that Chs diversification occurred after fungi departed from these kingdoms, but before separation of fungal groups. Accordingly, each fungal taxon contains members with enzymes belonging to different divisions and classes. Multiple alignment revealed the conservation of specific motifs characteristic of class, division and kingdom, but the strict conservation of only three motifs QXXEY, EDRXL and QXRRW, and seven isolated amino acids in the core region of all Chs. Determination of different structural features in this region of Chs brought to light a noticeable conservation of secondary structure in the proteins. [source] Endochitinase activity in the apoplastic fluid of Phellinus weirii -infected Douglas-fir and its association with over wintering and antifreeze activityFOREST PATHOLOGY, Issue 5 2003A. Zamani Summary Extracellular proteins were extracted from Phellinus weirii infected Douglas-fir (Pseudotsuga menziesii var. menziesii) roots and needles to examine endochitinase activity. Chitinases have been associated with the plant's defence response against fungal attack because they hydrolyse chitin, a structural component of fungal cell walls. Protein separation using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by Western immunoblot analysis using a polyclonal antibody specific to an endochitinase-like protein (ECP) resulted in the detection of up to three polypeptides between 27 and 30 kDa in size. Two-dimensional gel electrophoresis (2-D PAGE) followed by Western immunoblot analysis revealed that the apoplastic fluid contained multiple ECP isoforms with isoelectric points (pIs) ranging from 5.3 to 5.8 and molecular masses of 27,30 kDa. Chitinase activity in needle and root tissues was measured spectrophotometrically using a colorimetric assay. A gel overlay technique using glycol chitin as a substrate for endochitinase was applied to confirm that the ECP antibody detected an enzymatically active protein. The apoplastic fluid collected from P. weirii -infected winter Douglas-fir needles showed anti-freeze activity and seasonal analysis of needle tissue showed some evidence of ECP accumulation in winter months. ECP was distributed systemically throughout the tree. Increased levels of endochitinase activity in the region of P. weirii infection supports a physiological role for ECP in the plant defence response. Résumé Les protéines extra-cellulaires ont été extraites des racines et aiguilles de douglas (Pseudotsuga menziesii var menziesii) infectés par Phellinus weirii (Murr.) Gilbn., pour étudier l'activité endochitinase. Les chitinases ont été associées aux réactions de défense des plantes contre les attaques fongiques parce-qu'elles hydrolysent la chitine, un composant de la paroi des cellules fongiques. La séparation des protéines, réalisée par électrophorèse en gel de polyacrylamide avec sodium dodecyl sulfate (SDS-PAGE), suivie par une analyse par Western immunoblot en utilisant un anticorps polyclonal spécifique d'une protéine de type endochitinase (ECP), a permis la détection de 3 polypeptides de taille comprise entre 27 et 30 kDa. Une électrophorèse sur gel en 2-dimensions (2-D PAGE) suivie par une analyse par Western immunoblot a révélé que le fluide apoplastique contient de multiples isoformes d'ECP avec des pI dans une gamme de 5.3 à 5.8 et des masses moléculaires de 27 à 30 kDa. L'activité chitinase dans les aiguilles et tissus racinaires a été mesurée par spectrophotométrie par une méthode colorimétrique. Une technique d'overlay utilisant de la chitine glycol comme substrat de l'endochitinase a été appliquée pour confirmer que l'anticorps ECP avait détecté une protéine active du point de vue enzymatique. Le fluide apoplastique d'aiguilles récoltées en hiver sur des douglas infectés par P. weirii a montré une activité antigel et l'analyse saisonnière des tissus foliaires a montré une certaine accumulation d'ECP pendant l'hiver. L'ECP est répartie de façon systémique dans l'ensemble de l'arbre. Les niveaux accrus d'activité endochitinase dans la zone infectée par P. weirii suggère un rôle physiologique de l'ECP dans les réactions de défense de la plante. Zusammenfassung Aus Wurzeln und Nadeln von mit Phellinus weirii infizierten Douglasien (Pseudotsuga menziesii var. menziesii) wurden extrazelluläre Proteine extrahiert, um die Endochitinase-Aktivität zu bestimmen. Chitinasen werden mit der pflanzlichen Abwehrreaktion auf Pilzinfektionen in Verbindung gebracht, da sie Chitin, eine Strukturkomponente der pilzlichen Zellwand, hydrolysieren. Die Proteine wurden mit Natrium-Dodecyl-Sulfat-Polyacrylamid-Gelelektrophorese (SDS-PAGE) getrennt, gefolgt von einer Western Immunoblot-Analyse mit einem gegen ein Endochitinase-ähnliches Protein (ECP) spezifischen polyklonalen Antikörper. Hiermit liessen sich bis zu drei Polypeptide zwischen 27-30 kDa nachweisen. Eine zweidimensionale Gelelektrophorese (2-D PAGE) mit anschliessender Western Immunoblot-Analyse ergab, dass die Apoplastenflüssigkeit multiple ECP-Isoformen enthielt (mit pIs von 5,3 bis 5,8 und Molekularmassen von 27 bis 30 kDa). Die Chitinase-Aktivität wurde auch im Nadel- und Wurzelgewebe spektrophotometrisch mit einer Farbreaktion gemessen. Um sicher zu stellen, dass der ECP-Antikörper ein enzymatisch aktives Protein nachwies, wurde eine Gel-Overlay-Methode verwendet, mit Glycolchitin als Substrat für die Endochitinase. Die Apoplastenflüssigkeit der Nadeln von mit P. weirii infizierten Douglasien zeigte in Winterzustand eine Antifrost-Aktivität, ihre Analyse während des gesamten Jahres ergab aber keine Hinweise auf eine ECP-Anreicherung während der Wintermonate. ECP war systemisch im gesamten Baum enthalten. Die erhöhte Endochitinase-Aktivität in Bereichen mit P. weirii -Infektion lässt auf eine physiologische Rolle von ECP in der Pflanzenabwehr schliessen. [source] Dynamic Hydrogels: Switching of 3D Microenvironments Using Two-Component Naturally Derived Extracellular MatricesADVANCED MATERIALS, Issue 6 2010Brian M. Gillette This article describes fabrication of a two-component extracellular matrix (ECM) in which one component acts as a stable structural element and another component gels or dissolves reversibly (a modulatory component). Using a composite collagen-alginate ECM, reversible crosslinking of the alginate (the modulatory component) via application of calcium or citrate modulates cell mobility in a 3D collagen matrix (the structural component). [source] Nonlinear transient dynamic analysis by explicit finite element with iterative consistent mass matrixINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3 2009Shen Rong Wu Abstract Various mass matrices in the explicit finite element analyses of nonlinear transient dynamic problems are investigated. The matrices are obtained as a linear combination of lumped and consistent mass matrices. An iterative procedure to calculate the inverse of the consistent and the mixed mass matrices in the framework of explicit finite element method is presented. The convergence of the iterative procedure is proved. The inverse of the consistent and mixed mass matrices is approximated by the iteration and is used to compare the results from the lumped mass matrix. For the impact of a structural component and a vehicle, some difference in the results by using coarse mesh is observed. For the component using fine mesh, no significant difference is found. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fatigue life prediction using 2-scale temporal asymptotic homogenizationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2004Caglar Oskay Abstract In this manuscript, fatigue of structures is modelled as a multiscale phenomenon in time domain. Multiple temporal scales are introduced due to the fact that the load period is orders of magnitude smaller than the useful life span of a structural component. The problem of fatigue life prediction is studied within the framework of mathematical homogenization with two temporal co-ordinates. By this approach the original initial boundary value problem is decomposed into coupled micro-chronological (fast time-scale) and macro-chronological (slow time-scale) problems. The life prediction methodology has been implemented in ABAQUS and validated against direct cycle-by-cycle simulations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Different structural components of conventional papillary thyroid carcinoma display mostly identical BRAF statusINTERNATIONAL JOURNAL OF CANCER, Issue 1 2007Alexander Abrosimov Abstract Activating BRAFT1799A mutation is closely associated with a papillary thyroid carcinoma (PTC) histotype. The transversion is frequently detected in the conventional type, Warthin-like and tall cell variants, but is rare in the follicular variant of PTC. Conventional PTC is often presented with tumors of mixed architecture, which besides the papillary structures also contain areas with follicular and solid morphology in which the details of BRAF mutational status are unknown. We set out to differentially investigate the presence of mutated BRAF in the individual structural components microdissected from 44 formalin-fixed, paraffin-embedded PTC tissues from 40 patients. The mutation was detected in at least 1 structural component in 23 tumors (52%). Different structural components of the same tumor had identical BRAF status in 41/44 tumors (93%). In 3 tumors the BRAFT1799A mutation was found only in the papillary, but not in the follicular component. Mutational patterns identical to those in the primary tumors were found in 11/12 lymph node metastases (92%, including both BRAFT1799A -positive and -negative cases). The high concordance of the BRAF mutational status in structurally distinct areas suggests a rather homogeneous distribution of neoplastic epithelial cells in a conventional PTC tumor in most cases. These results imply the reliability of preoperative molecular diagnosis of PTC regardless of the type of tumor component at the site of biopsy sampling and suggest that the majority of patients with BRAF mutation-positive PTC may benefit from the targeted pharmacotherapy. © 2006 Wiley-Liss, Inc. [source] Wool peptide derivatives for hand careINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2008C. Barba Hands experience much greater wear and tear during normal daily routines compared with most other parts of the body, and thereby demand specific needs from cosmetics targeted at hand care. Keratin proteins are the major structural component of the outer layers of the skin. In this work a novel keratin fraction from wool, which has high cystine content present in the S-sulphonated form, has been developed to target hand care applications. In vivo long-term studies were performed to evaluate the water-holding capacity and elasticity of hand skin following topical application of keratins. Moreover, protection of healthy skin against detergent-induced dermatitis was evaluated after topical application of the keratin-active formulation. Significant results in the measured biophysical parameters were found, which indicated an improvement in the skin's water-holding capacity, hydration, and elasticity for volunteers with dry skin as a result of the keratin peptide treatment. Results also indicated that the keratin peptide treatment can prevent some of the damaging effects associated with surfactant exposure. [source] Crimp morphology in relaxed and stretched rat Achilles tendonJOURNAL OF ANATOMY, Issue 1 2007Marco Franchi Abstract Fibrous extracellular matrix of tendon is considered to be an inextensible anatomical structure consisting of type I collagen fibrils arranged in parallel bundles. Under polarized light microscopy the collagen fibre bundles appear crimped with alternating dark and light transverse bands. This study describes the ultrastructure of the collagen fibrils in crimps of both relaxed and in vivo stretched rat Achilles tendon. Under polarized light microscopy crimps of relaxed Achilles tendons appear as isosceles or scalene triangles of different size. Tendon crimps observed via SEM and TEM show the single collagen fibrils that suddenly change their direction containing knots. The fibrils appear partially squeezed in the knots, bent on the same plane like bayonets, or twisted and bent. Moreover some of them lose their D-period, revealing their microfibrillar component. These particular aspects of collagen fibrils inside each tendon crimp have been termed ,fibrillar crimps' and may fulfil the same functional role. When tendon is physiologically stretched in vivo the tendon crimps decrease in number (46.7%) (P < 0.01) and appear more flattened with an increase in the crimp top angle (165° in stretched tendons vs. 148° in relaxed tendons, P < 0.005). Under SEM and TEM, the ,fibrillar crimps' are still present, never losing their structural identity in straightened collagen fibril bundles of stretched tendons even where tendon crimps are not detectable. These data suggest that the ,fibrillar crimp' may be the true structural component of the tendon crimp acting as a shock absorber during physiological stretching of Achilles tendon. [source] Role of the Latent Transforming Growth Factor ,,Binding Protein 1 in Fibrillin-Containing Microfibrils in Bone Cells In Vitro and In VivoJOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2000Sarah L. Dallas Abstract Latent transforming growth factor ,,binding proteins (LTBPs) are extracellular matrix (ECM) proteins that bind latent transforming growth factor , (TGF-,) and influence its availability in bone and other connective tissues. LTBPs have homology with fibrillins and may have related functions as microfibrillar proteins. However, at present little is known about their structural arrangement in the ECM. By using antibodies against purified LTBP1, against a short peptide in LTBP1, and against epitope-tagged LTBP1 constructs, we have shown colocalization of LTBP1 and fibrillin 1 in microfibrillar structures in the ECM of cultured primary osteoblasts. Immunoelectron microscopy confirmed localization of LTBP1 to 10- to 12-nm microfibrils and suggested an ordered aggregation of LTBP1 into these structures. Early colocalization of LTBP1 with fibronectin suggested a role for fibronectin in the initial assembly of LTBP1 into the matrix; however, in more differentiated osteoblast cultures, LTBP1 and fibronectin 1 were found in distinct fibrillar networks. Overexpression of LTBP1 deletion constructs in osteoblast-like cells showed that N-terminal amino acids 67,467 were sufficient for incorporation into fibrillin-containing microfibrils and suggested that LTBP1 can be produced by cells distant from the site of fibril formation. In embryonic long bones in vivo, LTBP1 and fibrillin 1 colocalized at the surface of newly forming osteoid and bone. However, LTBP1-positive fibrils, which did not contain fibrillin 1, were present in cartilage matrix. These studies show that in addition to regulating TGF,1, LTBP1 may function as a structural component of connective tissue microfibrils. LTBP1 may therefore be a candidate gene for Marfan-related connective tissue disorders in which linkage to fibrillins has been excluded. [source] Surface topology and structural integrity of the Theromyzon tessulatum (Annelida: Hirudinea: Glossiphoniidae) cocoonJOURNAL OF MORPHOLOGY, Issue 7 2008Jon'elle Coleman Abstract Cocoons secreted by the aquatic leech Theromyzon tessulatum comprise a tubular, membranous ovoid, sealed at each end by a glue-like substance, called an operculum. Scanning electron microscopy showed surface features of the T. tessulatum cocoon that included a circuitous bulge, cups that conformed to the shape of embryos, relief folds that radiated from opercula, and asymmetric distributions of protuberances on the upper aspect of the cocoon surface. The structural integrity of the T. tessulatum cocoon was assessed after exposure to a variety of denaturing conditions (e.g., extreme heat, detergents, acids). Although both the fibrous cocoon membrane and opercula were strikingly resilient, the membrane/operculum boundary appeared to be the weakest structural component of the cocoon, consistent with its functional role as an escape hatch for juvenile leeches. The operculum itself was more sensitive to denaturation than the cocoon membrane, and thus was probably the source of a major protein component isolated from the T. tessulatum cocoon (i.e., Tcp; Theromyzon cocoon protein). J. Morphol., 2008. © 2008 Wiley-Liss, Inc. [source] Strong stabilization of a structural acoustic model, which incorporates shear and thermal effects in the structural componentMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 12 2010Marié Grobbelaar-Van Dalsen Abstract In this paper we consider the question of stabilization of a linear three-dimensional structural acoustic model, which incorporates displacement, rotational inertia, shear and thermal effects in the flat flexible structural component of the model. We show strong stabilization of the coupled model without incorporating viscous or boundary damping in the equations for the gas dynamics and without imposing geometric conditions. It turns out that damping is needed in the interior of the plate. Our main tool is an abstract resolvent criterion due to Y. Tomilov. Copyright © 2009 John Wiley & Sons, Ltd. [source] A scalar analysis of landscape connectivityOIKOS, Issue 2 2003Article first published online: 4 JUL 200 Landscape connectivity is critical to the maintenance of spatially-structured populations and consists of both a structural component, which describes the shape, size and location of landscape features; and a biological component, which consists of both the response of individuals to landscape features, and the patterns of gene flow that result from those individual responses. Traditional studies of landscape connectivity have attempted to discern individual behavioral responses to landscape features, but this methodology is intractable for many species. This paper is an attempt to relate the components of landscape connectivity through the explicit treatment of their spatial and temporal scales. Traditional measures of structural and biological components of connectivity are reviewed and more recently developed methods for the analysis of scale for each are introduced. I then present a framework for the comparison of scalar phenomena based on Watt's unit pattern, describe the potential outcomes of the comparison and discuss the implications of each. Several testable hypotheses emerge from the analysis that may serve as a useful framework for the investigation of landscape connectivity in the future. [source] Robust optimization of an airplane component taking into account the uncertainty of the design parametersQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 3 2009Gunther Steenackers Abstract A slat track, structural component of an aircraft wing that transfers the aerodynamical loads, excited by operational forces can result in excessive displacement levels if not properly designed. The design parameter values are not always precisely known but can contain a level of uncertainty to some extent due to, for example dimensional variation. During the different optimization approaches, the slat track geometry is optimized in order to limit the maximum vertical displacement, taking into account the variability of the design parameters. Application and comparison of different optimal, robust and generalized optimization approaches is presented and applied on the slat track finite element model, making use of mean and variance response functions to model the uncertainty on the finite element displacement values. Next to validating different objective function statements, a comparison is also made on the level of accuracy and practicability concerning the different response function models, based on regression techniques and Monte Carlo simulations, optimization and transmissibilities and regressive techniques and vibration reduction over a frequency range. Copyright © 2008 John Wiley & Sons, Ltd. [source] Molecular anatomy of a speckleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2006Lisa L. Hall Abstract Direct localization of specific genes, RNAs, and proteins has allowed the dissection of individual nuclear speckles in relation to the molecular biology of gene expression. Nuclear speckles (aka SC35 domains) are essentially ubiquitous structures enriched for most pre-mRNA metabolic factors, yet their relationship to gene expression has been poorly understood. Analyses of specific genes and their spliced or mature mRNA strongly support that SC35 domains are hubs of activity, not stores of inert factors detached from gene expression. We propose that SC35 domains are hubs that spatially link expression of specific pre-mRNAs to rapid recycling of copious RNA metabolic complexes, thereby facilitating expression of many highly active genes. In addition to increasing the efficiency of each step, sequential steps in gene expression are structurally integrated at each SC35 domain, consistent with other evidence that the biochemical machineries for transcription, splicing, and mRNA export are coupled. Transcription and splicing are subcompartmentalized at the periphery, with largely spliced mRNA entering the domain prior to export. In addition, new findings presented here begin to illuminate the structural underpinnings of a speckle by defining specific perturbations of phosphorylation that promote disassembly or assembly of an SC35 domain in relation to other components. Results thus far are consistent with the SC35 spliceosome assembly factor as an integral structural component. Conditions that disperse SC35 also disperse poly(A) RNA, whereas the splicing factor ASF/SF2 can be dispersed under conditions in which SC35 or SRm300 remain as intact components of a core domain. Anat Rec Part A, 288A:664,675, 2006. © 2006 Wiley-Liss, Inc. [source] Structure and composition of the postsynaptic density during developmentTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 20 2010Matthew T. Swulius Abstract In this study, we used electron tomography as well as immunogold labeling to analyze the morphology and distribution of proteins within postsynaptic densities (PSDs) isolated from rats before birth (embryonic day 19) and at postnatal days 2, 21, and 60. Our data provide direct evidence of distinct morphological and compositional differences in PSDs throughout development. Not all PSD components are present at the early stages of development, with a near lack of the scaffolding molecule PSD-95 at E19 and P2. The presence of NR1 and NR2b suggests that PSD-95 is not directly required for clustering of N-methyl-D-aspartic acid (NMDA) receptors in PSDs early in development. ,-Actinin is abundant by E19, suggesting that it is a core structural component of the PSD. Both , and , isoforms of Ca2+/calmodulin-dependent protein kinase II (CaMKII) are present early on but then rise in labeling density by approximately fourfold by P21. Among all the molecules studied, only calmodulin (CaM) was found in higher abundance early in PSD development and then fell in amount over time. Spatial analysis of the immunogold label shows a nonrandom distribution for all the proteins studied, lending support to the idea that the PSD is systematically assembled in an organized fashion. Morphological data from electron tomography shows that the PSD undergoes major structural changes throughout development. J. Comp. Neurol. 518:4243,4260, 2010. © 2010 Wiley-Liss, Inc. [source] Applying forest restoration principles to coral reef rehabilitationAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2003N. Epstein Abstract 1.Forest restoration through silviculture (gardening) programs revives productivity, biodiversity, and stability. As in silviculture approaches, the coral ,gardening' strategy is based on a two-step protocol. 2.The first step deals with the establishment of in situ and/or ex situ coral nurseries in which corals are farmed (originating from two types of source material: asexual [ramets, nubbins], and sexual [planula larvae, spat] recruits). 3.The second is the reef rehabilitation step, where maricultured colonies are transplanted into degraded sites. 4.We compare here the rationale of forest restoration to coral reef ecosystem restoration by evaluating major key criteria. As in silviculture programs, a sustainable mariculture operation that focuses on the prime structural component of the reef (,gardening' with corals) may promote the persistence of threatened coral populations, as well as that of other reef taxa, thus maintaining genetic diversity. In chronically degrading reef sites this may facilitate a halt in biodiversity depletion. 5.Within the current theoretical framework of ecosystem restoration, the recovery of biodiversity indices is considered a core element since a rich species diversity provides higher ecosystem resilience to disturbances. 6.The gardening measure may also be implemented worldwide, eliminating the need to extract existing colonies for transplantation operations. At degraded reef sites, the coral gardening strategy can assist in managing human and non-human stakeholders' requirements as is done in forest management. Copyright © 2003 John Wiley & Sons, Ltd. [source] The alpha-3 polypeptide chain of laminin 5: insight into wound healing responses from the study of genodermatosesCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 4 2005K. J. Hamill Summary Laminin 5 (kalinin/epiligrin/nicein) is an essential structural component of the dermal,epidermal junction, composed of three polypeptide subunits: laminin ,3, ,3 and ,2. Studies of the inherited skin fragility disorder junctional epidermolysis bullosa (JEB) have suggested that the major role of this heterotrimeric protein is to act as an adhesive ligand essential for binding the epidermis to the underlying dermis and thus maintaining the integrity of the skin. Protein interaction studies have shown that the C terminus of the ,3 subunit binds to a range of integrin complexes depending on the motility status of keratinocytes. This allows laminin 5 to interact with either hemidesmosomes or the actin cytoskeleton. Recently we have reported that the absence of the N-terminal region of laminin ,3a in laryngo-onchyo-cutaneous syndrome causes excessive granulation tissue production at wound sites. As granulation tissue production is also a problem in JEB, this implicates laminin 5 in control of this wound healing response. [source] Influence of Semi-Rigid Connections and Local Joint Damage on Progressive Collapse of Steel FrameworksCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2010Yuxin Liu This article extends the threat-independent method for progressive-failure analysis of rigid frames to analysis accounting for semi-rigid connections. The influence of joint damage caused by disengagement of member(s) is also considered in the analysis, and the degree of damage is modeled by a health index. A compound element model is employed to include the contributions of nonlinear behavior of beam-to-column connections, connection and member-end damage, member inelasticity, member shear deformation, and geometrical nonlinearity to structural response. Four beam collapse modes are illustrated for the progressive collapse analysis associated with debris loading generated when disengaged structural components fall onto lower parts of the structure. The impact effect is taken into account for the quasi-static nonlinear analysis by utilizing an impact amplification factor according to GSA and DoD guidelines. Any progressive collapse occurring thereafter involves a series of collapse events associated with topological changes of the frame. The analysis procedure is illustrated for the progressive collapse behavior of two planar steel frames. The results demonstrate that the proposed method is potentially an effective tool for the progressive collapse analysis of semi-rigid steel frames under abnormal loading events. [source] Calyculin-A, an inhibitor for protein phosphatases, induces cortical contraction in unfertilized sea urchin eggsCYTOSKELETON, Issue 4 2001Yukako Asano Abstract When an unfertilized sea urchin egg was exposed to calyculin-A (CL-A), an inhibitor of protein phosphatases, for a short period and then lysed, the cortex contracted to exclude cytoplasm and became a cup-shaped mass. We call the contracted cortex "actin cup" since actin filaments were major structural components. Electron microscopic observation revealed that the cup consisted of inner electron-dense layer, middle microfilamentous layer, and outermost granular region. Microfilaments were heavily accumulated in the inner electron-dense layer. The middle layer also contained numerous microfilaments, which were determined to be actin filaments by myosin S1 decoration, and they were aligned so that their barbed ends directed toward the outermost region. Myosin II, Arp2, Arp3, and spectrin were concentrated in the actin cup. Immuno-electron microscopy revealed that myosin II was localized to the electron-dense layer. We further found that the cortical tension of the egg increased just after application of CL-A and reached maximum within 10 min. Cytochalasin B or butanedione monoxime blocked the contraction, which suggested that both actin filaments and myosin ATPase activity were required for the contraction. Myosin regulatory light chain (MRLC) in the actin cup was shown to be phosphorylated at the activation sites Ser-19 and Thr-18, by immunoblotting with anti-phosphoepitope antibodies. The phosphorylation of MRLC was also confirmed by a 32P in vivo labeling experiment. The CL-A-induced cortical contraction may be a good model system for studying the mechanism of cytokinesis. Cell Motil. Cytoskeleton 48:245,261, 2001. © 2001 Wiley-Liss, Inc. [source] Exploring the Frontier of Livelihoods ResearchDEVELOPMENT AND CHANGE, Issue 1 2005Leo De Haan This article discusses the value of livelihoods studies and examines the obstacles which have prevented it from making a greater contribution to understanding the lives of poor people over the past decade. After examining the roots of the livelihoods approach, two major challenges are explored: the conceptualization of the problem of access, and how to achieve a better understanding of the mutual link between livelihood opportunities and decision-making. The article concludes that access to livelihood opportunities is governed by social relations, institutions and organizations, and that power is an important (and sometimes overlooked) explanatory variable. In discussing the issue of access to livelihood opportunities, the authors note the occurrence of both strategic and unintentional behaviour and the importance of structural factors; they discuss concepts of styles and pathways, which try to cater for structural components and regularities; and they propose livelihood trajectories as an appropriate methodology for examining these issues. In this way, the article also sets the agenda for future livelihoods research. [source] Multi-scale system reliability analysis of lifeline networks under earthquake hazardsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2010Junho Song Abstract Recent earthquake events evidenced that damage of structural components in a lifeline network may cause prolonged disruption of lifeline services, which eventually results in significant socio-economic losses in the affected area. Despite recent advances in network reliability analysis, the complexity of the problem and various uncertainties still make it a challenging task to evaluate the post-hazard performance and connectivity of lifeline networks efficiently and accurately. In order to overcome such challenges and take advantage of merits of multi-scale analysis, this paper develops a multi-scale system reliability analysis method by integrating a network decomposition approach with the matrix-based system reliability (MSR) method. In addition to facilitating system reliability analysis of large-size networks, the multi-scale approach enables optimizing the level of computational effort on subsystems; identifying the relative importance of components and subsystems at multiple scales; and providing a collaborative risk management framework. The MSR method is uniformly applied for system reliability analyses at both the lower-scale (for link failure) and the higher-scale (for system connectivity) to obtain the probability of general system events, various conditional probabilities, component importance measures, statistical correlation between subsystem failures and parameter sensitivities. The proposed multi-scale analysis method is demonstrated by its application to a gas distribution network in Shelby County of Tennessee. A parametric study is performed to determine the number of segments during the lower-scale MSR analysis of each pipeline based on the strength of the spatial correlation of seismic intensity. It is shown that the spatial correlation should be considered at both scales for accurate reliability evaluation. The proposed multi-scale analysis approach provides an effective framework of risk assessment and decision support for lifeline networks under earthquake hazards. Copyright © 2009 John Wiley & Sons, Ltd. [source] Earthquake-resistant structural design through energy demand and capacityEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2007Adang Surahman Abstract An energy-based earthquake-resistant structural design method is proposed. The proposed method uses specific input energy spectra, modal or time-history analyses, and energy distribution among structural members. For a given member strength and stiffness, a relationship between the energy attributable to damage absorbed by a member and its cumulative ductility demand can be determined. Member strength, stiffness and energy capacity are design parameters which are simultaneously used in the design. The method can avoid soft-storey design. The damage is measured based on a cumulative basis considering earthquake magnitude, frequency, and duration. Tests have been carried out to determine energy absorbing capacities of various structural components. More efforts are needed to make the energy-based earthquake-resistant structural design practical, but ssimple formulations for this method are possible. Copyright © 2007 John Wiley & Sons, Ltd. [source] Major components of a sea urchin block to polyspermy are structurally and functionally conservedEVOLUTION AND DEVELOPMENT, Issue 3 2004Julian L. Wong Summary One sperm fusing with one egg is requisite for successful fertilization; additional sperm fusions are lethal to the embryo. Because sperm usually outnumber eggs, evolution has selected for mechanisms that prevent this polyspermy by immediately modifying the egg extracellular matrix. We focus here on the contribution of cortical granule contents in the sea urchin block to polyspermy to begin to understand how well this process is conserved. We identified each of the major constituents of the fertilization envelope in two species of seaurchins, Strongylocentrotus purpuratus and Lytechinus variegatus, that diverged 30 to 50 million years ago. Our results show that the five major structural components of the fertilization envelope, derived from the egg cortical granules, are semiconserved. Most of these orthologs share sequence identity and encode multiple low-density lipoprotein receptor type A repeats or CUB domains but at least two contain radically different carboxy-terminal repeats. Using a new association assay, we also show that these major structural components are functionally conserved during fertilization envelope construction. Thus, it seems that this population of female reproductive proteins has retained functional motifs while gaining significant sequence diversity,two opposing paths that may reflect cooperativity among the proteins that compose the fertilization envelope. [source] | ||||||||||||||||||||||||||||||||||||||||||||||