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Complex Structure (complex + structure)
Selected AbstractsChemInform Abstract: Synthesis and Structural Characterization of A3In2Ge4 and A5In3Ge6 (A: Ca, Sr, Eu, Yb) , New Intermetallic Compounds with Complex Structures, Exhibiting Ge,Ge and In,In Bonding.CHEMINFORM, Issue 35 2010Tae-Soo You Abstract The title compounds are prepared from mixtures of the elements using excess In as a flux (alumina crucible, 1223 K, 10,12 h) and characterized by powder and single crystal XRD, and TB-LMTO electronic structure calculations. [source] Phonons and Raman spectra of lithiated titanate Li0.5TiO2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004R. Baddour-Hadjean Abstract Raman spectra of the electrochemically lithiated TiO2 anatase evidence that Li intercalation induces complex spectral features in the high wavenumber range. These modes can be assigned to the stretching vibrations of Li-O valence bonds. Two theoretical approaches are used to describe the vibrations of Li atoms within the TiO2 lattice. First, the quantum-mechanical calculations of molecular clusters imitating the Li...TiO2 system, which showed formation of covalent Li-O bonds and allowed an estimation of their force constants. Second, the lattice dynamics simulation which enabled to predict the whole spectrum of Li-phonons and their interaction with TiO2 lattice vibrations. Complex structure of the observed Raman spectra is explained by multiplicity of the Li positions. This results in multiple Raman bands originated from the Li atom vibrations covering a wide frequency range from 450 up to 950 cm,1. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Layer-by-Layer Interference Lithography of Three-dimensional Microstructures in SU-8,ADVANCED ENGINEERING MATERIALS, Issue 5 2009Andrés F. Lasagni We report on rapid fabrication of two-, two and a half-, and 3D planar periodic structures using layer-by-layer deposition and interference patterning of SU-8 photoresist. Complex structures with non-periodic vertical symmetry were fabricated controlling the cure depth by addition of a UV absorber. The fabrication method reported here can be applied for the high-volume manufacturing of solid structures for microelectromechanical systems and microfluidic devices. [source] Investigation of the Influence of Overvoltage, Auxiliary Glow Current and Relaxation Time on the Electrical Breakdown Time Delay Distributions in NeonCONTRIBUTIONS TO PLASMA PHYSICS, Issue 2 2005. A. Maluckov Abstract Results of the statistical analysis of the electrical breakdown time delay for neon-filled tube at 13.3 mbar are presented in this paper. Experimental distributions of the breakdown time delay were established on the basis of 200 successive and independent measurements, for different overvoltages, relaxation times and auxiliary glows. Obtained experimental distributions deviate from usual exponential distribution. Breakdown time delay distributions are numerically generated, usingMonte-Carlo method, as the compositions of the two independent random variables with an exponential and a Gaussian distribution. Theoretical breakdown time delay distribution is obtained from the convolution of the exponential and Gaussian distribution. Performed analysis shows that the crucial parameter that determines the complex structure of time delay is the overvoltage and if it is of the order of few percentage, then distribution of time delay must be treated as an convolution of two random variables. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Post-karyokinesis centrosome movement leaves a trail of unanswered questionsCYTOSKELETON, Issue 3 2002Young Y. Ou Abstract The centrosome is a complex structure composed of a large number of proteins (pericentriolar material, PCM) usually organized around a pair of centrioles (or a centriole duplex). This structure is capable of nucleating and organizing microtubules, duplication, and motility. In general, episodes of dramatic centrosome movement correlate with periods of cellular reorganization and nowhere is cellular reorganization more apparent, or more important, than in the periods before and after cell division. It is now clear that centrosome movement occurs not only prior to cell division but also at its completion, in concert with cytokinesis. The focus of this review is the newly emerging picture of centrosome activity during the post-karyokinesis period and the role that this activity might play in the transition of cells from mitosis to interphase. Cell Motil. Cytoskeleton 51:123,132, 2002. © 2002 Wiley-Liss, Inc. [source] Immediate early gene (ZENK, Arc) expression in the auditory forebrain of female canaries varies in response to male song qualityDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2005Stefan Leitner Abstract In male songbirds, the song control pathway in the forebrain is responsible for song production and learning, and in females it is associated with the perception and discrimination of male song. However, experiments using the expression of immediate early genes (IEGs) reveal the activation of brain regions outside the song control system, in particular the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM). In this study on female canaries, we investigate the role of these two regions in relation to playback of male songs of different quality. Male canaries produce elaborate songs and some contain syllables with a more complex structure (sexy syllables) that induce females to perform copulation solicitation displays (CSD) as an invitation to mate. Females were first exposed to playback of a range of songs of different quality, before they were finally tested with playback of songs containing either sexy or nonsexy syllables. We then sectioned the brains and used in situ hybridization to reveal brain regions that express the IEGs ZENK or Arc. In CMM, expression of ZENK mRNA was significantly higher in females that last heard sexy syllables compared to those that last heard nonsexy syllables, but this was not the case for NCM. Expression of Arc mRNA revealed no differences in either CMM or NCM in both experimental groups. These results provide evidence that in female canaries CMM is involved in female perception and discrimination of male song quality through a mechanism of memory reconsolidation. The results also have further implications for the evolution of complex songs by sexual selection and female choice. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source] Female canaries that respond and discriminate more between male songs of different quality have a larger song control nucleus (HVC) in the brainDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2002Stefan Leitner Abstract In male songbirds the song control pathway in the forebrain is responsible for song production and learning. In most species, females do not sing and have smaller nuclei in the song control pathway. Although the function of the pathway in females is assumed to be associated with the perception of male song, there is little direct evidence to support this view. In this study on female canaries, we investigate the role of two key nuclei in the song control pathway (HVC and lMAN) in relation to playback of male song. Male canaries produce elaborate songs that function to attract and stimulate females. The songs are constructed from smaller units called syllables, and special syllables with a more complex structure (sexy syllables) are known to induce females to perform copulation solicitation displays (CSD) as an invitation to mate. By using computer-edited experimental songs, we first show that females discriminate between songs by producing significantly more CSD to those containing sexy syllables. We then sectioned the brains and used in situ hybridization to reveal song nuclei containing androgen receptors. We report positive correlations between the size of HVC and both total CSD response and the amount of discrimination between sexy and nonsexy songs. We found no such relationships between these measures and the size of lMAN. These results provide some evidence to support the view that, in female canaries HVC is involved in female perception and discrimination of male song. The results also have implications for the evolution of complex male songs by sexual selection and female choice. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 294,301, 2002 [source] Structural seismic response analysis based on multiscale approach of computing fault,structure systemEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2009T. Ichimura Abstract Structural safety for earthquake waves emitted from a nearby fault is a major concern. For a large complex structure, it might be desired to estimate its seismic response by analyzing a fault,structure system: a full three-dimensional model in which a source fault and a target structure are modeled so that fault processes, wave propagation and amplification processes, and resulting dynamic responses of the structure can be computed numerically. To analyze this fault,structure system, this paper proposes an efficient approach based on multiscale analysis, i.e. waves emitted from the source fault are computed in the entire system in the geological length-scale; then they are refined in a small part of the system that includes the structure, and the seismic response of the structure is accurately computed in the engineering length-scale. Using a long highway tunnel as an example, this paper examines the validity of the proposed approach. The usefulness and applicability of the proposed approach to estimate the structural seismic responses are discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Molecular mechanisms activating muscle protein degradation in chronic kidney disease and other catabolic conditionsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2005J. Du Abstract Muscle atrophy is a prominent feature of chronic kidney disease (CKD) and is frequent in other catabolic conditions. Results from animal models of these conditions as well as patients indicate that atrophy is mainly owing to accelerated muscle proteolysis in the ubiquitin-proteasome (Ub-P'some) proteolytic system. The Ub-P'some system, however, rapidly degrades actin or myosin but cannot breakdown actomyosin or myofibrils. Consequently, another protease must initially cleave the complex structure of muscle. We identified caspase-3 as an initial and potentially rate-limiting proteolytic step that cleaves actomyosin/myofibrils to produce substrates degraded by the Ub-P'some system. In rodent models of CKD and other catabolic conditions, we find that caspase-3 is activated and cleaves actomyosin to actin, myosin and their fragments. This initial proteolytic step in muscle leaves a characteristic footprint, a 14-kDa actin band, providing a potential diagnostic tool to detect muscle catabolism. We also found that stimulation of caspase-3 activity depends on inhibition of IRS-1-associated phosphatidylinositol 3-kinase (PI3K) activity; inhibiting PI3K in muscle cells also leads to expression of a critical E3-ubiquitin-conjugating enzyme involved in muscle protein breakdown: atrogin-1/MAFbx. Thus, protein breakdown by caspase-3 and the ubiquitin-proteasome system in muscle are stimulated by the same signal: a low PI3K activity. These responses could yield therapeutic strategies to block muscle atrophy. [source] Genetic mapping of Foxb1-cell lineage shows migration from caudal diencephalon to telencephalon and lateral hypothalamusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2008Tianyu Zhao Abstract The hypothalamus is a brain region with vital functions, and alterations in its development can cause human disease. However, we still do not have a complete description of how this complex structure is put together during embryonic and early postnatal stages. Radially oriented, outside-in migration of cells is prevalent in the developing hypothalamus. In spite of this, cell contingents from outside the hypothalamus as well as tangential hypothalamic migrations also have an important role. Here we study migrations in the hypothalamic primordium by genetically labeling the Foxb1 diencephalic lineage. Foxb1 is a transcription factor gene expressed in the neuroepithelium of the developing neural tube with a rostral expression boundary between caudal and rostral diencephalon, and therefore appropriate for marking migrations from caudal levels into the hypothalamus. We have found a large, longitudinally oriented migration stream apparently originating in the thalamic region and following an axonal bundle to end in the anterior portion of the lateral hypothalamic area. Additionally, we have mapped a specific expansion of the neuroepithelium into the rostral diencephalon. The expanded neuroepithelium generates abundant neurons for the medial hypothalamus at the tuberal level. Finally, we have uncovered novel diencephalon-to-telencephalon migrations into septum, piriform cortex and amygdala. [source] How political parties frame European integrationEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2010MARC HELBLING This article analyses how political parties frame European integration, and gauges the consistency of their argumentation. Over the course of investigation, one can see how actors' positions are justified, and how the European Union is perceived (i.e., what forces give rise to Euroscepticism and Europeanism). It is argued here that the parties' framing of issues depends on the interests they traditionally defend at the national level, their general positions on European integration, and whether or not they belong to the established political actors in their respective countries. The coding approach enables the relation of frames to actors and positions, moving beyond the techniques employed by existing studies that analyse the media presentation of European integration. Sophisticated frame categorisations are provided to capture the complex structure of argumentation, going beyond a simple dichotomy of economic and cultural frames. Relying on a large and original media dataset covering the period 2004,2006, six Western European countries are investigated. [source] Oxidation resistant aluminized MCrAlY coating prepared by Spark Plasma Sintering (SPS),ADVANCED ENGINEERING MATERIALS, Issue 5 2007D. Oquab NiCoCrAlYTa single and multi layered coatings on an AM3® nickel base superalloy have been fabricated by Spark Plasma Sintering (SPS). MCrAlY powder and Al foil were sintered on the superalloy in a single run SPS experiment The results reported in this paper open the way to faster development of new high temperature coatings with complex structure and composition. [source] Modularity of the rodent mandible: Integrating bones, muscles, and teethEVOLUTION AND DEVELOPMENT, Issue 6 2008Miriam Leah Zelditch Summary Several models explain how a complex integrated system like the rodent mandible can arise from multiple developmental modules. The models propose various integrating mechanisms, including epigenetic effects of muscles on bones. We test five for their ability to predict correlations found in the individual (symmetric) and fluctuating asymmetric (FA) components of shape variation. We also use exploratory methods to discern patterns unanticipated by any model. Two models fit observed correlation matrices from both components: (1) parts originating in same mesenchymal condensation are integrated, (2) parts developmentally dependent on the same muscle form an integrated complex as do those dependent on teeth. Another fits the correlations observed in FA: each muscle insertion site is an integrated unit. However, no model fits well, and none predicts the complex structure found in the exploratory analyses, best described as a reticulated network. Furthermore, no model predicts the correlation between proximal parts of the condyloid and coronoid, which can exceed the correlations between proximal and distal parts of the same process. Additionally, no model predicts the correlation between molar alveolus and ramus and/or angular process, one of the highest correlations found in the FA component. That correlation contradicts the basic premise of all five developmental models, yet it should be anticipated from the epigenetic effects of mastication, possibly the primary morphogenetic process integrating the jaw coupling forces generated by muscle contraction with those experienced at teeth. [source] Attack and defence in the gastric epithelium , a delicate balanceEXPERIMENTAL PHYSIOLOGY, Issue 4 2007Rod Dimaline The gastric epithelium is a complex structure formed into tubular branched gastric glands. The glands contain a wide variety of cell types concerned with the secretion of hydrochloric acid, proteases, mucus and a range of signalling molecules. All cell types originate from stem cells in the neck region of the gland, before migrating and differentiating to assume their characteristic positions and functions. Endocrine and local paracrine mediators are of crucial importance for maintaining structural and functional integrity of the epithelium, in the face of a hostile luminal environment. The first such mediator to be recognized, the hormone gastrin, was identified over a century ago and is now established as the major physiological stimulant of gastric acid secretion. Recent studies, including those using mice that overexpress or lack the gastrin gene, suggest a number of previously unrecognized roles for this hormone in the regulation of cellular proliferation, migration and differentiation. This review focuses on the identification of hitherto unsuspected gastrin-regulated genes and discusses the paracrine cascades that contribute to the maintenance of gastric epithelial architecture and secretory function. Helicobacter infection is also considered in cases where it shares targets and signalling mechanisms with gastrin. [source] Hierarchical ZnS-In2S3 -CuS Nanospheres with Nanoporous Structure: Facile Synthesis, Growth Mechanism, and Excellent Photocatalytic ActivityADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Yingxuan Li Abstract Without using any templates or surfactants, hierarchical ZnS-In2S3 -CuS nanospheres with nanoporous structure are successfully synthesized via a simple and convenient process. The nanospheres are aggregations of densely packed nanoparticles and nanorods. Different to the oriented attachment (OA) mechanism reported in the literature, the formation of these nanorods is believed to follow a lateral OA mechanism (nanoparticles attach along the direction perpendicular to the crystallographic axes with lateral planes as the juncture) based on the experimental data. This process could be a general phenomenon and would provide a new insight into the OA mechanism. A detailed time-resolved TEM kinetic study of the formation of the complex structure is shown. The dipole mechanism and electric field-induced growth are found to be responsible for the final architecture. Photocatalytic activities for water splitting are investigated under visible-light irradiation (, > 400 nm) and an especially high photocatalytic activity (apparent yield of 22.6% at 420 nm) is achieved by unloaded ZnIn0.25Cu0.02S1.395 prepared at 180 °C for 18 h because of their high crystallinity, large pore volume, and the presence of nanorods with special microstructures. [source] Full-scale study on combustion characteristics of an upholstered chair under different boundary conditions,Part 1: Ignition at the seat centerFIRE AND MATERIALS, Issue 6 2009Q. Y. Xie Abstract The objective of this work is to investigate the effects of boundary conditions on the combustion characteristic of combustible items in a room. A series of full-scale experiments were carried out in the ISO 9705 fire test room with an upholstered chair at four typical locations, i.e. at the middle of side wall, at the center of the room with the seat toward the door, at the center of the room with the seat toward inside of the room, at the room corner, respectively. Ignition was achieved through a BS No.7 wooden crib at the geometric center of the seat surface for each test. Besides the heat release rate (HRR), four thermocouple trees were placed around the chair to monitor detailed temperature distributions during the combustion process of an upholstered chair. The results indicated that the boundary conditions had some effects on the combustion behavior of a chair in a room. It was shown that there were clearly two main peak HRRs for the cases of a chair being clung to the side wall or at the corner. However, there was only one main peak HRR when the chair was placed at the center of the room, either outwards or inwards. In addition, the results of the two cases of chairs being at the center indicate that the maximum HRR (about 829,kW) for the chair seat toward the door was relatively larger than the maximum HRR (about 641,kW) for the chair seat toward inside of the room. It was suggested that the special complex structure of a chair was also a considerable factor for the effect of boundary conditions on the combustion behavior of a chair in an enclosure. Furthermore, the measured temperature distributions around the chair also illustrated the effects of boundary condition on the combustion behavior of a chair in a room. It was suggested that although HRR was one of the most important fire parameters, HRR mainly represented the comprehensive fire behavior of a combustible item. In order to develop more suitable room fire dynamic models, more detailed information such as the surrounding temperature distributions measured by the thermocouple trees are useful. Copyright © 2009 John Wiley & Sons, Ltd. [source] Metapopulation ecology in the sea: from Levins' model to marine ecology and fisheries scienceFISH AND FISHERIES, Issue 2 2004Jacob P Kritzer Abstract Marine and fisheries scientists are increasingly using metapopulation concepts to better understand and model their focal systems. Consequently, they are considering what defines a metapopulation. One perspective on this question emphasizes the importance of extinction probability in local populations. This view probably stems from the focus on extinction in Levins' original metapopulation model, but places unnecessary emphasis on extinction,recolonization dynamics. Metapopulation models with more complex structure than Levins' patch-occupancy model and its variants allow a broader range of population phenomena to be examined, such as changes in population size, age structure and genetic structure. Analyses along these lines are critical in fisheries science, where presence,absence resolution is far too coarse to understand stock dynamics in a meaningful way. These more detailed investigations can, but need not, aim to assess extinction risk or deal with extinction-prone local populations. Therefore, we emphasize the coupling of spatial scales as the defining feature of metapopulations. It is the degree of demographic connectivity that characterizes metapopulations, with the dynamics of local populations strongly dependent upon local demographic processes, but also influenced by a nontrivial element of external replenishment. Therefore, estimating rates of interpopulation exchange must be a research priority. We contrast metapopulations with other spatially structured populations that differ in the degree of local closure of their component populations. We conclude with consideration of the implications of metapopulation structure for spatially explicit management, particularly the design of marine protected area networks. [source] Flux vacua statistics for two-parameter Calabi-Yau'sFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 3 2005A. Misra Abstract We study the number of flux vacua for type IIB string theory on an orientifold of the Calabi-Yau expressed as a hypersurface in WCP4[1,1,2,2,6] by evaluating a suitable integral over the complex-structure moduli space as per the conjecture of Douglas and Ashok. We show that away from the singular conifold locus, one gets a power law, and that the (neighborhood) of the conifold locus indeed acts as an attractor in the (complex structure) moduli space. In the process, we evaluate the periods near the conifold locus. We also study (non)supersymmetric solutions near the conifold locus, and show that supersymmetric solutions near the conifold locus do not support fluxes. [source] Inflorescence characteristics, seed composition, and allometric relationships predicting seed yields in the biomass crop Cynara cardunculusGCB BIOENERGY, Issue 3 2010S. V. ARCHONTOULIS Abstract Cynara (Cynara cardunculus) is a perennial C3 herb that has its potential as bioenergy crop. This paper aims (a) to derive empirical relationships to predict cynara seed yield per head and per unit area, avoiding laborious extraction of seeds from the complex structure of its inflorescences; (b) to determine the head-weight distribution per unit area, the seed composition and the oil profile of cynara seeds; and (c) to estimate the range of cynara biomass, seed and oil yield in representative parts of Greece. We analyzed 16 field experiments, varying in crop age and environmental conditions in Greece. Seed yield per head (SYhead) can be accurately predicted as a linear function of dry head weight (Hw): SYhead=0.429·Hw,2.9 (r2=0.96; n=617). Based on this relationship, we developed a simple two-parameter equation to predict seed yield per unit area (SY): SY=HN·(0.429·,,2.9), where , is the mean head weight (g head,1) and HN is the total number of heads per unit area, respectively. The models were tested against current and published data (n=180 for head-level; n=35 for unit area-level models), and proved to be valid under diverse management and environmental conditions. Attainable cynara seed yields ranged from 190 to 480 g m,2 yr,1, on dry soils and on aquic soils (shallow ground water level). This variation in seed yield was sufficiently explained by the analyses of head-weight distribution per unit area (small, medium and large heads) and variability of seed/head weight ratio at head level. Seed oil concentration (average: 23%) and crude protein concentration (average: 18.7%) were rather invariant across different seed sizes (range: 26,56 mg seed,1) and growing environments. [source] Crystal structure of the Pyrococcus horikoshii DNA primase-UTP complex: implications for the mechanism of primer synthesisGENES TO CELLS, Issue 12 2003Nobutoshi Ito Background:,, In chromosomal DNA replication, DNA primase initiates the synthesis of a dinucleotide on a single-stranded template DNA, and elongates it to form a primer RNA for the replicative DNA polymerase. Although the apo-structure of an archaeal primase has been reported, the mechanism of primer synthesis by the eukaryotic-type primase still remains to be elucidated. Results:,, In this study, we present the crystal structure of the eukaryotic-type DNA primase from the hyperthermophilic archaeon (Pyrococcus horikoshii) with the uridine 5,-triphosphate (UTP). In the present primase-UTP complex, the primase binds the triphosphate moiety of the UTP at the active site, which includes Asp95, Asp97, and Asp280, the essential residues for the nucleotidyl transfer reaction. Conclusion:,, The nucleotide binding geometry in this complex explains the previous biochemical analyses of the eukaryotic primase. Based on the complex structure, we constructed a model between the DNA primase and a primer/template DNA for the primer synthesis. This model facilitates the comprehension of the reported features of DNA primase. [source] Optimization of structural dynamic behaviour based on effective modal parametersINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007S. Besset Abstract Optimization of complex structures often leads to high calculation costs. Indeed, the structure has to be frequently reanalysed in order to update the optimization criteria. We propose an optimization method based on effective modal parameters. These parameters are close to the modal matrices used for the modal analysis of a structure. Thus, once the structure has been analysed, it becomes very easy to calculate optimization criteria. First, we will explain the modal analysis that we will use in this paper. A modal model will be used to analyse the hollow parts of the structure. The modal analysis of the whole structure will be performed using substructuring and ,double modal synthesis' proposed by Jezequel. Secondly, we will explain how to obtain effective modal parameters and their use for optimization. Finally, we will show the efficiency of these parameters through the optimization of a complex structure, using two types of optimization methods. Copyright © 2006 John Wiley & Sons, Ltd. [source] 6-O glucose linoleate supports in vitro human hair growth and lipid synthesisINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2007P. Vingler Synopsis The hair follicle is a very active organ with a complex structure, which produces a hair fibre at a rate of 0.3 mm a day. Accordingly, the hair follicle is highly demanding in energy source, as the hair bulb matrix cells are endowed with one of the highest rates of proliferation in the human body. Moreover, recent data have shown the involvement of lipids in hair follicle function. As in vitro -grown hair follicle keeps producing a hair fibre that closely resembles the natural hair fibre, we decided to use this model to investigate the role of a new of glucose linoleate derivative (6-O-linoleyl- d -glucose: 6-O-GL) as a lipid precursor and energy provider. Our results demonstrated that 6-O-GL was (i) quite stable and surprisingly resistant to oxidative degradation, and (ii) readily taken up and metabolized by the hair follicle into various lipids, namely neutral lipids, ceramides and polar lipids. Moreover, it supported hair follicle growth and survival in a glucose- and linoleic-acid free medium. 6-O-GL thus appeared to be a bi-functional nutrient, ensuring both proper fibre quality and production by the hair follicle. Résumé Le follicule pileux est un organe très actif et d'une structure très complexe, qui produit la tige pilaire au rythme de 0.3 mm par jour. En conséquence, le follicule pileux est très demandeur en ressources énergétiques, les cellules de la matrice bulbaire ayant un des taux de prolifération les plus élevé de l'organisme. De plus des études récentes ont mis en évidence le rôle de lipides dans le fonctionnement du follicule pileux. Puisque le follicule pileux in vitro continue à produire une fibre de qualité identique à celle d'une fibre naturelle, nous avons décidé d'utiliser ce modèle pour étudier le rôle d'un nouveau linoléate de glucose (6-O-linoleyl- d -glucose: 6-O-GL) en tant que précurseur lipidique et source d'énergie. Nos résultats démontrent que le 6-O-GL est très stable et étonnamment résistant à l'auto oxydation, qu'il est capté et métabolisé par le follicule pileux en divers lipides, neutres, polaires et céramides. De plus, le 6-O-GL soutient la croissance et la survie du follicule dans un milieu dépourvu de glucose et d'acide linoléique. Le 6-O-GL apparaît donc comme un agent bi-fonctionnel, permettant au follicule pileux de maintenir in vitro la production de la tige pilaire. [source] Derivation of the mammalian skull vaultJOURNAL OF ANATOMY, Issue 1-2 2001GILLIAN M. MORRISS-KAY abstract This review describes the evolutionary history of the mammalian skull vault as a basis for understanding its complex structure. Current information on the developmental tissue origins of the skull vault bones (mesoderm and neural crest) is assessed for mammals and other tetrapods. This information is discussed in the context of evolutionary changes in the proportions of the skull vault bones at the sarcopterygiantetrapod transition. The dual tissue origin of the skull vault is considered in relation to the molecular mechanisms underlying osteogenic cell proliferation and differentiation in the sutural growth centres and in the proportionate contributions of different sutures to skull growth. [source] Method to describe curing in large epoxy samplesADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009Krzysztof Kasza Abstract Curing kinetics models used in numerical simulations describe the exothermic chemical reaction of thermosetting materials. The mathematical formula known as Kamal's model is discussed in the following paper. Traditionally, the coefficients of Kamal's equations are estimated based on differential scanning calorimetry (DSC) measurements and results from an experimental verification of such created curing kinetics model are presented. Furthermore, an inverse analysis is proposed for additional adjustment of the model. The new coefficients thus found provide better accuracy in the computer simulations. The methodology of development of the curing kinetics model is proposed as an alternative solution to the standard DSC measurements. Particularly, it could be useful for materials with a complex structure, such as composites. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:267,275, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20162 [source] How quickly do forecasters incorporate news?JOURNAL OF APPLIED ECONOMETRICS, Issue 6 2006Evidence from cross-country surveys Using forecasts from Consensus Economics Inc., we provide evidence on the efficiency of real GDP growth forecasts by testing whether forecast revisions are uncorrelated. As the forecast data used are multi-dimensional,18 countries, 24 monthly forecasts for the current and the following year and 16 target years,the panel estimation takes into account the complex structure of the variance,covariance matrix due to propagation of shocks across countries and economic linkages among them. Efficiency is rejected for all 18 countries: forecast revisions show a high degree of serial correlation. We then develop a framework for characterizing the nature of the inefficiency in forecasts. For a smaller set of countries, the G-7, we estimate a VAR model on forecast revisions. The degree of inefficiency, as manifested in the serial correlation of forecast revisions, tends to be smaller in forecasts of the USA than in forecasts for European countries. Our framework also shows that one of the sources of the inefficiency in a country's forecasts is resistance to utilizing foreign news. Thus the quality of forecasts for many of these countries can be significantly improved if forecasters pay more attention to news originating from outside their respective countries. This is particularly the case for Canadian and French forecasts, which would gain by paying greater attention than they do to news from the USA and Germany, respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source] Bone microstructure at the distal tibia provides a strength advantage to males in late puberty: An HR-pQCT studyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2010Melonie Burrows Abstract Bone is a complex structure with many levels of organization. Advanced imaging tools such as high-resolution (HR) peripheral quantitative computed tomography (pQCT) provide the opportunity to investigate how components of bone microstructure differ between the sexes and across developmental periods. The aim of this study was to quantify the age- and sex-related differences in bone microstructure and bone strength in adolescent males and females. We used HR-pQCT (XtremeCT, Scanco Medical, Geneva, Switzerland) to assess total bone area (ToA), total bone density (ToD), trabecular bone density (TrD), cortical bone density (CoD), cortical thickness (Cort.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular spacing standard deviation (Tb.Sp SD), and bone strength index (BSI, mg2/mm4) at the distal tibia in 133 females and 146 males (15 to 20 years of age). We used a general linear model to determine differences by age- and sex-group and age,×,sex interactions (p,<,0.05). Across age categories, ToD, CoD, Cort.Th, and BSI were significantly lower at 15 and 16 years compared with 17 to 18 and 19 to 20 years in males and females. There were no differences in ToA, TrD, and BV/TV across age for either sex. Between sexes, males had significantly greater ToA, TrD, Cort.Th, BV/TV, Tb.N, and BSI compared with females; CoD and Tb.Sp SD were significantly greater for females in every age category. Males' larger and denser bones confer a bone-strength advantage from a young age compared with females. These structural differences could represent bones that are less able to withstand loads in compression in females. © 2010 American Society for Bone and Mineral Research [source] Protein tyrosine phosphatase SHP-1 specifically recognizes C-terminal residues of its substrates via helix ,0JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2001Jian Yang Abstract The catalytic domain of protein tyrosine phosphatase SHP-1 possesses distinct substrate specificity. It recognizes the P-3 to P-5 residues of its substrates via the ,5-loop-,6 region. To study the substrate specificity further, we determined the structure of the catalytic domain of SHP-1 (C455S) complexed with a less-favorable-substrate peptide originated from SIRP,. The complex has disordered N-terminal peptide structure and reduced interactions between the N-terminal peptide and the ,5-loop-,6 region. This could be the basis for the lower affinity of peptide pY427 for the catalytic domain of SHP-1. In addition, by comparing the SHP-1/less-favorable peptide complex structure with the SHP-1/substrate complex structures, we identified a novel substrate-recognition site in the catalytic domain of SHP-1. This site was formed by helix ,0 and the ,5-loop-,6 motif of SHP-1, and specifically bound residues at the P,+,4 and further C-terminal positions of peptide substrates. © 2001 Wiley-Liss, Inc. [source] CAD,ICAD complex structure derived from saturation transfer experiment and simulated annealing without using pairwise NOE informationJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2004Tomoki Matsuda Abstract Saturation transfer experiments were performed for the 2H- and 15N-labeled mouse CAD domain of the caspase-activated deoxyribonuclease and the CAD domain of its inhibitor to reveal the protein,protein complexed conformation. Based on the physical model for the spin diffusion, a novel method was developed to reconstruct the complexed structure using the simulated annealing calculation. The complementarity in the molecular surface shape and the electrostatic potential distribution provide a good measure for the assessment of the putative complexed conformation, despite much less experimental information than the conventional distance geometry calculation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Work values: Development of a new three-dimensional structure based on confirmatory smallest space analysisJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 7 2010Sean T. Lyons We tested the psychological structure of the work values ratings of 119,167 Canadian workers using confirmatory smallest space analysis (SSA). Contrary to our hypotheses, the SSA did not support a two-dimensional radex structure, but suggested a three-dimensional cylindrex structure composed of three facets: (a) A modality facet comprised of four types of work values (cognitive, instrumental, social, and prestige) forming angular sectors of a circle; (b) a growth-orientation facet with growth-related work aspects located closest to the center of the circle and context-related work aspects located in the peripheral ring; and (c) a level of focus facet that divided the overall cylindrical structure into three separate vertical levels (individual, job/organizational, and societal). The findings extend the theory of work values by providing a richer typology of work values and a more complete picture of the complex structure of their inter-relations. Copyright © 2009 John Wiley & Sons, Ltd. [source] New synthetic esters with a complex structure considered as tribological fluidsLUBRICATION SCIENCE, Issue 4 2009Liviu E. MirciArticle first published online: 28 APR 200 Abstract The paper presents results concerning synthesis and characterisation as lubricant fluids of some esters of different monocarboxylic acids with variable chain length, along with aliphatic-aromatic complex alcohols and/or with superior alcohols (exclusive of aliphatic). The monocarboxylic acids taken into account were n -butyric, n -octanoic and oleic, respectively, while the alcohols considered were isodecyl and isotridecyl as purely aliphatic, and 2-phenoxy-ethanol, 2-[(o -sec-butyl)phenoxy]ethanol and 2-[(p -nonyl)phenoxy]ethanol, as part of the complex aliphatic-aromatic alcohols group. Under these circumstances, it became possible to study the influence of the structure on the main physico-chemical properties of these synthetic oils as well as on their tribological representative features. The results recorded certified the validity of the proposed research programme. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||