318 research outputs found

    CONCRETE FRACTURE ANALYSIS USING THE CONTINUUM STRONG DISCONTINUITY APPROACH AND THE BOUNDARY ELEMENT METHOD

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    The implicit formulation of the boundary element method is applied to bi-dimensional problems of material failure involving, sequentially, inelastic dissipation with softening in continuous media, bifurcation and transition between weak and strong discontinuities. The bifurcation condition is defined by the singularity of the localization tensor, also known, for historical reasons, as acoustic tensor. The weak discontinuities are related to strain localization bands of finite width, which become increasingly narrow until to collapse in a surface with discontinuous displacement field, called strong discontinuity surface. To associate such steps to the fracture process in concrete specimens, an isotropic damage (continuum) constitutive model is used to represent the material behaviour in all of them, taking into account the adaptations that comefrom the strong discontinuity analysis for the post-bifurcation phases. The crack propagation across the domain is done by an automatic cells generation algorithm and, in this context, the fracture process zone in the crack tip became totally represented by the cells in the continuum damage regime and the cells with weak discontinuities

    Synergism of Cattle and Bison Inoculum on Ruminal Fermentation and Select Bacterial Communities in an Artificial Rumen (Rusitec) Fed a Barley Straw Based Diet

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    This study evaluated the effect of increasing the proportion of bison relative to cattle inoculum on fermentation and microbial populations within an artificial rumen (Rusitec). The experiment was a completely randomized design with a factorial treatment structure (proportion cattle:bison inoculum; 0:100, 33:67, 67:33 and 100:0) replicated in two Rusitec apparatuses (n=8 fermenters). The experiment was 15 d with 8 d of adaptation and 7 d of sampling. Fermenters were fed a diet of 70:30 barley straw:concentrate (DM basis). True digestibility of DM was determined after 48 h of incubation from d 13-15, and daily ammonia (NH3) and volatile fatty acid (VFA) production were measured on d 9-12. Protozoa counts were determined at d 9, 11, 13 and 15 and particle-associated bacteria (PAB) from d 13-15. Select bacterial populations in the PAB were measured using RT-qPCR. Fermenter was considered the experimental unit and day of sampling as a repeated measure. Increasing the proportion of bison inoculum resulted in a quadratic effect (P0.05). Increasing bison inoculum linearly increased (P<0.05) concentrate aNDF disappearance, total and concentrate N disappearance as well as total daily VFA and acetate production. A positive quadratic response (P<0.05) was observed for daily NH3-N, propionate, butyrate, valerate, isovalerate and isobutyrate production, as well as the acetate:propionate ratio. Increasing the proportion of bison inoculum linearly increased (P<0.05) total protozoa numbers. No effects were observed on pH, total gas and methane production, microbial N synthesis, or copies of 16S rRNA associated with total bacteria, Selenomonas ruminantium or Prevotella bryantii. Increasing bison inoculum had a quadratic effect (P<0.05) on Fibrobacter succinogenes, and tended to linearly (P<0.10) increase Ruminococcus flavefaciens and decrease (P<0.05) Ruminococcus albus copy numbers. In conclusion, bison inoculum increased the degradation of feed protein and fibre. A mixture of cattle and bison rumen inoculum acted synergistically, increasing the DM and aNDF disappearance of barley straw

    Influence of different ECM-like hydrogels on neurite outgrowth induced by adipose tissue-derived stem cells

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    Mesenchymal stem cells (MSCs) have been proposed for spinal cord injury (SCI) applications due to their capacity to secrete growth factors and vesicles-secretome-that impacts important phenomena in SCI regeneration. To improve MSC survival into SCI sites, hydrogels have been used as transplantation vehicles. Herein, we hypothesized if different hydrogels could interact differently with adipose tissue-derived MSCs (ASCs). The efficacy of three natural hydrogels, gellan gum (functionalized with a fibronectin peptide), collagen, and a hydrogel rich in laminin epitopes (NVR-gel) in promoting neuritogenesis (alone and cocultured with ASCs), was evaluated in the present study. Their impact on ASC survival, metabolic activity, and gene expression was also evaluated. Our results indicated that all hydrogels supported ASC survival and viability, being this more evident for the functionalized GG hydrogels. Moreover, the presence of different ECM-derived biological cues within the hydrogels appears to differently affect the mRNA levels of growth factors involved in neuronal survival, differentiation, and axonal outgrowth. All the hydrogel-based systems supported axonal growth mediated by ASCs, but this effect was more robust in functionalized GG. The data herein presented highlights the importance of biological cues within hydrogel-based biomaterials as possible modulators of ASC secretome and its effects for SCI applications.This study is funded by Prémios Santa Casa Neurociências—Prize Melo e Castro for Spinal Cord Injury Research. This is also partially funded by EU-FP7-Health-2011-Collaborative Project 278612, Biohybrid—Templates for peripheral nerve regeneration, and Portuguese Foundation for Science and Technology (IF Development Grant to A. J. Salgado; postdoctoral fellowship to N. A. Silva—SFRH/BPD/97701/2013; PhD fellowships of R. C. Assunção-Silva and E. D. Gomes—PDE/BDE/113596/2015 and SFRH/BD/103075/2014, resp.). This article is a result of the project (NORTE-01-0145-FEDER-000013) supported by the Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Cofinanciado pelo ProgramaOperacional Regional do Norte(ON.2 SR&TD Integrated Program—NORTE-07-0124-FEDER-000021), ao abrigo do Quadro de Referência Estratégico Nacional (QREN), através do Fundo Europeude Desenvolvimento Regional (FEDER); Projeto Estratégico—LA 26–2011-2012 and Projeto Estratégico—LA 26–2013-2014 cofinanciado por fundos nacionais, através da Fundação para a Ciência e a Tecnologia (PEst-C/SAU/LA0026/2011; PEst-C/SAU/LA0026/2013), e pelo Fundo Europeu de Desenvolvimento Regional (FEDER), através do COMPETE (FCOMP-01-0124-FEDER-022724; FCOMP-01-0124-FEDER-037298). The authors would like to thank Professor Jeffrey Gimble at the Tulane University Center for Stem Cell Research and Regenerative Medicine and LaCell LLC (New Orleans, Louisiana, USA) for kindly providing the ASCs used in this study.info:eu-repo/semantics/publishedVersio

    Unveiling the Differences of Secretome of Human Bone Marrow Mesenchymal Stem Cells, Adipose Tissue-Derived Stem Cells, and Human Umbilical Cord Perivascular Cells: A Proteomic Analysis

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    The use of human mesenchymal stem cells (hMSCs) has emerged as a possible therapeutic strategy for CNS-related conditions. Research in the last decade strongly suggests that MSC-mediated benefits are closely related with their secretome. Studies published in recent years have shown that the secretome of hMSCs isolated from different tissue sources may present significant variation. With this in mind, the present work performed a comparative proteomic-based analysis through mass spectrometry on the secretome of hMSCs derived from bone marrow (BMSCs), adipose tissue (ASCs), and human umbilical cord perivascular cells (HUCPVCs). The results revealed that BMSCs, ASCs, and HUCPVCs differed in their secretion of neurotrophic, neurogenic, axon guidance, axon growth, and neurodifferentiative proteins, as well as proteins with neuroprotective actions against oxidative stress, apoptosis, and excitotoxicity, which have been shown to be involved in several CNS disorder/injury processes. Although important changes were observed within the secretome of the cell populations that were analyzed, all cell populations shared the capability of secreting important neuroregulatory molecules. The difference in their secretion pattern may indicate that their secretome is specific to a condition of the CNS. Nevertheless, the confirmation that the secretome of MSCs isolated from different tissue sources is rich in neuroregulatory molecules represents an important asset not only for the development of future neuroregenerative strategies but also for their use as a therapeutic option for human clinical trials.Foundation Calouste de Gulbenkian for the funds attributed to A.J.S.; Portuguese Foundation for Science and Technology (FCT) PhD fel- lowships attributed to A.O.P. (SFRH/BD/33900/2009) and S.I.A. (SFRH/BD/81495/2011) and Ciência 2007, IF Development Grant attributed to A.J.S., and projects PTDC/ NEU-NMC/0205/2012, UID/NEU/04539/2013; cofinanced by COMPETE Programa Operacional Factores de Compe- titividade; and by The National Mass Spectrometry Network (RNEM) (REDE/1506/REM/2005); Prémios Santa Casa Neurociências—Prize Melo e Castro for Spinal Cord Injury Research; cofunded by Programa Operacional Regional do Norte (ON.2–O Novo Norte),ao abrigo do Quadro de Referência Estratégico Nacional (QREN), and através do Fundo Europeu de Desenvolvimento Regional (FEDER). The authors also would like to thank Professor J.E.D. (University of Toronto, Canada) and Professor J.M.G. (Tulane University) for kindly providing HUCPVCs and ASCs, respectivelyinfo:eu-repo/semantics/publishedVersio

    Fluência de Leitura, Reconhecimento de Palavras e Compreensão Leitora em Alunos do 4º ao 9º Ano do Ensino Fundamental: Revisão Sistemática

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    O processamento da leitura é resultado da interação de distintos processos cognitivos, como reconhecimento de palavras, compreensão oral e fluência. Há evidências sobre a importância da fluência para predizer a compreensão de leitura, mas ainda não é claro seu papel ao longo do desenvolvimento. Essa revisão sistemática analisou estudos nacionais e internacionais sobre a relação das habilidades de reconhecimento de palavras e fluência de leitura com a compreensão de leitura em alunos do 4º ao 9º ano. A revisão foi conduzida de acordo com a metodologia prisma e utilizou a base de dados PubMed, de 2000 a setembro de 2019. Foram incluídos artigos que respondiam à pergunta norteadora e atendiam à temática estabelecida pelos descritores e palavras-chave. Foram encontrados 992 artigos, dos quais 904 foram excluídos pelo título e resumo e 56 pela leitura do texto completo. Isto possibilitou a análise de 32 artigos. Os resultados sugerem que, diferentemente do reconhecimento de palavras, a habilidade de fluência de leitura tende a manter relação significativa com a compreensão de leitura no decorrer do segundo ciclo do Ensino Fundamental

    Fluência de Leitura, Reconhecimento de Palavras e Compreensão Leitora em Alunos do 4º ao 9º Ano do Ensino Fundamental: Revisão Sistemática

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    Text processing results from the interaction of different cognitive processes, such as word recognition, listening comprehension, and fluency. There is evidence relating to the importance of fluency in predicting reading comprehension, but its role during the course of development is still uncertain. The present systematic review has analyzed national and international research on the relationship between word recognition skills and reading fluency with reading comprehension in students from the 4th to 9th grade. The review was conducted according to the PRISMA methodology and employed the PubMed database from 2000 to September 2019. The chosen papers answered the orienting question and corresponded to the topic established by the descriptors and keywords. We found 992 articles, of which 904 were excluded by reading the titles and abstracts and 56 by reading the full texts. It was possible to analyze 32 papers. The results suggest that, unlike word recognition, the ability to read fluently tends to uphold a significant relationship with reading comprehension during the second cycle of Elementary School.El procesamiento de la lectura es el resultado de la interacción de diferentes procesos cognitivos, como el reconocimiento de palabras, la comprensión oral y la fluidez. Existe evidencia sobre la importancia de la fluidez en la predicción de la comprensión lectora, pero a lo largo del desarrollo su papel no está claro. Esta revisión sistemática analizó estudios nacionales e internacionales sobre la relación entre las habilidades de reconocimiento de palabras y fluidez lectora con la comprensión lectora en estudiantes de 4° a 9° grado. La revisión se realizó de acuerdo con la metodología prisma y utilizó la base de datos  PubMed, desde el 2000 hasta septiembre de 2019. Fueron incluidos artículos que respondieron a la pregunta guía y cumplieron con la temática establecida por los descriptores y palabras clave. Se encontraron 992 artículos, de los cuales 904 fueron excluidos por título y resumen, y 56 por lectura de texto completo. Esto permitió el análisis de 32 artículos. Los resultados sugieren que, a diferencia del reconocimiento de palabras, la habilidad de fluidez lectora tiende a mantener una relación significativa con la comprensión lectora durante el segundo ciclo de la escuela primaria.O processamento da leitura é resultado da interação de distintos processos cognitivos, como reconhecimento de palavras, compreensão oral e fluência. Há evidências sobre a importância da fluência para predizer a compreensão de leitura, mas ainda não é claro seu papel ao longo do desenvolvimento. Essa revisão sistemática analisou estudos nacionais e internacionais sobre a relaçãodas habilidades de reconhecimento de palavrase fluência de leitura com a compreensão de leitura em alunos do 4º ao 9º ano. A revisão foi conduzida deacordo com a metodologia prisma e utilizou a basede dados PubMed, de 2000 a setembro de 2019. Foram incluídos artigos que respondiam à pergunta norteadora e atendiam à temática estabelecida pelos descritores e palavras-chave. Foram encontrados 992 artigos, dos quais 904 foram excluídos pelo título e resumo e 56 pela leitura do texto completo. Isto possibilitou a análise de 32 artigos. Os resultados sugerem que, diferentemente do reconhecimento de palavras, a habilidade de fluência de leitura tende a manter relação significativa com a compreensão de leitura no decorrer do segundo ciclo do Ensino Fundamental

    Identification of novel enzymes to enhance the ruminal digestion of barley straw

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    Crude enzyme extracts typically contain a broad spectrum of enzyme activities, most of which are redundant to those naturally produced by the rumen microbiome. Identification of enzyme activities that are synergistic to those produced by the rumen microbiome could enable formulation of enzyme cocktails that improve fiber digestion in ruminants. Compared to untreated barley straw, Viscozyme® increased gas production, dry matter digestion (P<0.01) and volatile fatty acid production (P<0.001) in ruminal batch cultures. Fractionation of Viscozyme® by Blue Native PAGE and analyses using a microassay and mass-spectrometry revealed a GH74 endoglucanase, GH71 α-1,3-glucanase, GH5 mannanase, GH7 cellobiohydrolase, GH28 pectinase, and esterases from Viscozyme® contributed to enhanced saccharification of barley straw by rumen mix enzymes. Grouping of these identified activities with their carbohydrate active enzymes (CAZy) counterparts enabled selection of similar CAZymes for downstream production and screening. Mining of these specific activities from other biological systems could lead to high value enzyme formulations for ruminants

    Ages and metallicities of stellar clusters using S-PLUS narrow-band integrated photometry: the Small Magellanic Cloud

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    The Magellanic Clouds are the most massive and closest satellite galaxies of the Milky Way, with stars covering ages from a few Myr up to 13 Gyr. This makes them important for validating integrated light methods to study stellar populations and star-formation processes, which can be applied to more distant galaxies. We characterized a set of stellar clusters in the Small Magellanic Cloud (SMC), using the Southern Photometric Local Universe Survey\textit{Southern Photometric Local Universe Survey}. This is the first age (metallicity) determination for 11 (65) clusters of this sample. Through its 7 narrow bands, centered on important spectral features, and 5 broad bands, we can retrieve detailed information about stellar populations. We obtained ages and metallicities for all stellar clusters using the Bayesian spectral energy distribution fitting code BAGPIPES\texttt{BAGPIPES}. With a sample of clusters in the color range −0.20<r−z<+0.35-0.20 < r-z < +0.35, for which our determined parameters are most reliable, we modeled the age-metallicity relation of SMC. At any given age, the metallicities of SMC clusters are lower than those of both the Gaia Sausage-Enceladus disrupted dwarf galaxy and the Milky Way. In comparison with literature values, differences are Δ\Deltalog(age)≈0.31\approx0.31 and Δ\Delta[Fe/H]≈0.41\approx0.41, which is comparable to low-resolution spectroscopy of individual stars. Finally, we confirm a previously known gradient, with younger clusters in the center and older ones preferentially located in the outermost regions. On the other hand, we found no evidence of a significant metallicity gradient.Comment: 12 pages, 11 figure

    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

    Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic

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    Material collected in summer 2004 from the Mid-Atlantic Ridge between Iceland and the Azores with three pelagic trawls was used to estimate relative catchabilities of common fish, cephalopod, decapod, and jellyfish species. Catchability is defined as the ratio of numbers caught between two trawls, standardized for towed distance. Taxon-specific catchability coefficients were estimated for two large pelagic trawls with graded meshes, using a smaller pelagic trawl with a uniform mesh size as the reference trawl. Two of the trawls were equipped with multiple opening–closing codends that allowed sampling of different depth layers. Generalized linear and mixed models suggest that most of the taxa have catchabilities much lower than expected from the area of opening alone, indicating that only a few species are herded by the large mesh at the mouth of larger trawls. Catchability coefficients across taxa show a very large spread, indicating that the sampled volume for the larger trawls with graded meshes was highly taxon-specific. Part of this variability can be explained by body size and taxonomic group, the latter probably reflecting differences in body form and behaviour. The catchability estimates presented here form the basis for combining data for quantitative analyses of community structure
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