1,379 research outputs found

    Remarks on (1−q)(1-q) expansion and factorization approximation in the Tsallis nonextensive statistical mechanics

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    The validity of (1-q) expansion and factorization approximations are analysed in the framework of Tsallis statistics. We employ exact expressions for classical independent systems (harmonic oscillators) by considering the unnormalized and normalized constrainsts. We show that these approxiamtions can not be accurate in the analysis of systems with many degrees of freedom.Comment: Latex, 6 pages, 2 figure

    Computational and Mathematical Modelling of the EGF Receptor System

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    This chapter gives an overview of computational and mathematical modelling of the EGF receptor system. It begins with a survey of motivations for producing such models, then describes the main approaches that are taken to carrying out such modelling, viz. differential equations and individual-based modelling. Finally, a number of projects that applying modelling and simulation techniques to various aspects of the EGF receptor system are described

    Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

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    We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

    In vivo performance of hierarchical HRP-crosslinked silk fibroin/ÎČ-TCP scaffolds for osteochondral tissue regeneration

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    Background: Osteochondral defects (OCD) can affect the articular cartilage and subchondral bone tissues, which requires superior therapies for the simultaneous and full restoration of such structurally and biologically different tissues. Methods: Tissue engineered OC grafts were prepared using a horseradish peroxidase (HRP) approach to crosslink silk fibroin (HRP-SF) as the articular cartilage-like layer and an underlying HRP-SF/ZnSrTCP subchondral bone-like layer (HRP-SF/dTCP), through salt-leaching/freeze-drying methodologies. In vivo OC regeneration was assessed by implantating the hierarchical scaffolds in rabbit critical size OC defects, during 8 weeks. A comparative analysis was performed using hierarchical OC grafts made of pure ÎÂČ-TCP (HRP-SF/TCP). Results: The hierarchical scaffolds showed good integration into the host tissue and no signs of acute inflammatory reaction, after 8 weeks of implantation. The histological analyses revealed positive collagen type II and glycosaminoglycansĂą formation in the articular cartilage-like layer. New bone ingrowthĂą s and blood vessels infiltration were detected in the subchondral bone-like layers. Conclusions: The proposed hierarchical scaffolds presented an adequate in vivo response with cartilage tissue regeneration and calcified tissue formation specially promoted by the ionic incorporation into the subchondral bone layer, confirming the hierarchical structures as suitable for OCD regeneration.Portuguese Foundation for Science and Technology for the Hierarchitech project (M-era-Net/0001/2014), for the fellowships (SFRH/BD/99555/2014) and (SFRH/BPD/101952/2014), and for the distinctions attributed to JMO (IF/01285/2015) and SP (CEECIND/03673/2017). Also, financial support from FCT/MCTES (Fundação para a CiĂȘncia e a Tecnologia/ MinistĂ©rio Da CiĂȘncia, Tecnologia, e Ensino Superior) and fundo social europeu atravĂ©s do programa operacional do capital humano (FSE/POCH), PD/59/2013, PD/BD/113806/201
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