253 research outputs found
Cartilage and bone regeneration: how close are we to bedside?
The treatment/regeneration of bone and cartilage diseases or defects, whether induced by rheumatism, joint dysplasia, trauma, or surgery presents great challenges that have not been fully solved by the current therapies. In the last few years, tissue engineering and regenerative medicine have been proposing advanced tools and technologies for bone and cartilage tissue regeneration, and some of which have successfully reached the market. Beyond the source of cells, the creation of superior structures for replacing defective bone and cartilage requires strong research in biomechanical signaling and synthesis of advanced biomaterials to mimic human tissues at the most varied levels. Natural and synthetic polymers, bioresorbable inorganic materials, and composites have been investigated for its potential as scaffolding materials with enhanced mechanical and biological properties. Porous scaffolds, hydrogels, and fibers are the most commonly biomimetic structures used for bone and cartilage tissue engineering. Herein, the concepts and current treatment strategies for bone and cartilage repair, as well as biomimetic strategies for bone and cartilage tissue engineering are overviewed. A global review of the ongoing clinical trials and of the scaffolds commercially available for the repair of osteochondral tissue is also presented.(undefined
Fault systems of Upper Triassic outcrops in Coimbra region
Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)A partir da análise estrutural dos sistemas de falhas em afloramentos do Triásico Superior
localizados na região de Coimbra, na Bacia Lusitânica, foi possível definir famílias e sub-famílias de
falhas. Este trabalho permitiu reconhecer que os acidentes tectónicos extensionais que afectaram os
depósitos do Triásico nesta região, durante toda a evolução do contexto tectónico do Mesozóico foram
sistematicamente reactivados nos regimes compressivos do final do Mesozóico e Cenozóico.From the structural analysis of the fault system in the Upper Triassic outcrops, located in the
Coimbra region of the Lusitanian Basin, it was possible to define fault families and subfamilies. This
recognizing that the extensional tectonic strutures that affected the Triassic deposits from this region,
were systematically reactivated during the Late Mesozoic and Cenozoic compressive regimes
Sistemas de recompensa: Uma analise empírica de antecedentes e consequências
O objectivo principal deste estudo consistiu em
analisar os antecedentes e consequências da configuração
do sistema de recompensas. O trabalho avaliou a
influência da cultura dominante de uma organização
nas características do sistema de recompensas, bem
como os efeitos deste no desempenho dos sujeitos. A
questão de partida era: qual o contributo da configuração
do sistema de recompensas de uma organização
para a explicação do nível do desempenho dos seus
trabalhadores? Este problema de investigação pode por
sua vez subdividir-se nas seguintes questões: que dimensões
da cultura organizacional influenciam a configuração
do sistema de remuneração? Quais os efeitos
do sistema de recompensas de uma organização no desempenho
dos seus trabalhadores? Os resultados sugerem
que as características do sistema de recompensas
de uma organização sofrem influências da cultura organizacional
dominante, no que se refere nomeadamente
ao nível da orientação competitiva ou orientação
humanista. A cultura dominante e o nível de remuneração
influem de forma significativa na percepção
de equidade, ou seja, organizações com cultura orientada
para a competição geram percepções de iniquidade
enquanto que organizações de matiz cooperativo
promovem percepções de equidade. Por último, as características
do sistema de recompensas influenciam
múltiplas dimensões do desempenho organizacional.ABSTRACT: This study analyzed some antecedents and consequences
of an organization’s reward system. The study
evaluated the influence of the dominant culture on the
characteristics of the reward system, as well as the
effects of this system on organizational behavior. The
departing question was: what is the contribution of the
reward system to the explanation of behavior in organizations?
This research problem was subdivided in
the following questions: what dimensions of the culture
organizational do influence the compensation system?
What are the effects of the reward system? Results
suggest that the characteristics of rewards are influenced
by the dominant cultural type, operationalized
as competitive and humanist orientations. Culture
and reward systems influence the perception of fairness,
in the sense that organizations with competitive
cultures tend to generate more perceptions of inequity,
while cooperative organizations promote perceptions
of equity.info:eu-repo/semantics/publishedVersio
Hierarchical HRP-crosslinked silk fibroin/ZnSr-doped TCP nancocomposites towards osteochondral tissue regeneration: Biomechanical performance and in vivo assessment
[Excerpt] Introduction. Recent investigations highlight promising regenerative strategies for osteochondral (OC) tissue treatment, such as hierarchical nanocomposite scaffolds containing ionic dopants.1,2 They allow cell infiltration and ECM formation throughout the engineered cartilage and subchondral tissues. The biomechanical behavior, antibacterial properties, and in vivo performance of hierarchical nanostructures combining enzymatically crosslinked silk fibroin (SF) and ZnSr-doped β-tricalcium phosphate (ZnSrTCP) for OC tissue regeneration is herein assessed. [...]Thanks to the Portuguese Foundation for Science and Technology for M-era-Net/0001/2014
project, and for the distinctions (IF/01285/2015) and (CEECIND/03673/2017)
Water and otolith chemistry: implications for discerning estuarine nursery habitat use of a juvenile flatfish
Variations in otolith elemental composition are widely used to reconstruct fish movements. However, reconstructing habitat use and environmental histories of fishes within estuaries is still a major challenge due to the dynamic nature of these coastal environments. In this study, we performed a laboratory experiment to investigate the effects of variations in salinity (three levels; 5, 18, 30) and temperature (two levels; 16,
21 C) on the otolith elemental composition (Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) of juvenile Senegalese sole Solea senegalensis. Temperature and salinity treatments mirrored the natural conditions of the estuarine habitats occupied by juvenile Senegalese sole, thereby providing information on the applicability of otolith microchemistry to reconstruct habitat use patterns within estuarine nurseries, where individual fish move across
complex salinity and temperature gradients. While Sr:Ca and Ba:Ca in otoliths were both positively related to salinity, no temperature effect was observed. Partition coefficients, proxies for element incorporation rates increased with increasing salinity for Sr (DSr) and Ba (DBa). In contrast, salinity and temperature had little influence on otolith Mn:Ca and Mg:Ca, supporting physiological control on the incorporation of these elements. Our results are a stepping stone for the interpretation of otolith chemical profiles for fish collected in their natural habitats and contribute to better understanding the processes involved in otolith element incorporation.info:eu-repo/semantics/publishedVersio
Ferroelectric nanofibers with an embedded optically nonlinear benzothiazole derivative
We report measurements of the molecular first hyperpolarizability, thermal stability, photophysical, piezoelectric and ferroelectric properties of a benzothiazole derivative bearing an arylthiophene π-conjugated bridge both in solution and when embedded into a poly (L-lactic acid) (PLLA) matrix in the form of electrospun fibers with an average diameter of roughly 500 nm. The embedded nanocrystalline phenylthienyl-benzothiazole derivative, with crystal sizes of about 1.4 nm resulted in a good piezoelectric response from these functionalized electrospun fibers, indicative of a polar crystalline structure.Fundação para a Ciência e a Tecnologia (FCT
Transcriptional activity of transposable elements in maize
<p>Abstract</p> <p>Background</p> <p>Mobile genetic elements represent a high proportion of the Eukaryote genomes. In maize, 85% of genome is composed by transposable elements of several families. First step in transposable element life cycle is the synthesis of an RNA, but few is known about the regulation of transcription for most of the maize transposable element families. Maize is the plant from which more ESTs have been sequenced (more than two million) and the third species in total only after human and mice. This allowed us to analyze the transcriptional activity of the maize transposable elements based on EST databases.</p> <p>Results</p> <p>We have investigated the transcriptional activity of 56 families of transposable elements in different maize organs based on the systematic search of more than two million expressed sequence tags. At least 1.5% maize ESTs show sequence similarity with transposable elements. According to these data, the patterns of expression of each transposable element family is variable, even within the same class of elements. In general, transcriptional activity of the <it>gypsy</it>-like retrotransposons is higher compared to other classes. Transcriptional activity of several transposable elements is specially high in shoot apical meristem and sperm cells. Sequence comparisons between genomic and transcribed sequences suggest that only a few copies are transcriptionally active.</p> <p>Conclusions</p> <p>The use of powerful high-throughput sequencing methodologies allowed us to elucidate the extent and character of repetitive element transcription in maize cells. The finding that some families of transposable elements have a considerable transcriptional activity in some tissues suggests that, either transposition is more frequent than previously expected, or cells can control transposition at a post-transcriptional level.</p
Design, Construction and Installation of the ATLAS Hadronic Barrel Scintillator-Tile Calorimeter
The scintillator tile hadronic calorimeter is a sampling calorimeter using steel as the absorber structure and scintillator as the active medium. The scintillator is located in "pockets" in the steel structure and the wavelength-shifting fibers are contained in channels running radially within the absorber to photomultiplier tubes which are located in the outer support girders of the calorimeter structure. In addition, to its role as a detector for high energy particles, the tile calorimeter provides the direct support of the liquid argon electromagnetic calorimeter in the barrel region, and the liquid argon electromagnetic and hadronic calorimeters in the endcap region. Through these, it indirectly supports the inner tracking system and beam pipe. The steel absorber, and in particular the support girders, provide the flux return for the solenoidal field from the central solenoid. Finally, the end surfaces of the barrel calorimeter are used to mount services, power supplies and readout crates for the inner tracking systems and the liquid argon barrel electromagnetic calorimeter
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