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Resting state brain networks (RSNs) are spatially distributed large-scale networks, evidenced by resting state functional magnetic resonance imaging (fMRI) studies. Importantly, RSNs are implicated in several relevant brain functions and present abnormal functional patterns in many neuropsychiatric disorders, for which stress exposure is an established risk factor. Yet, so far, little is known about the effect of stress in the architecture of RSNs, both in resting state conditions or during shift to task performance. Herein we assessed the architecture of the RSNs using functional magnetic resonance imaging (fMRI) in a cohort of participants exposed to prolonged stress (participants that had just finished their long period of preparation for the medical residence selection exam), and respective gender- and age-matched controls (medical...
External corrosion is one of the most common causes of oilwell casing failure. Hostile environments can be due to acidizing treatments. Although it is common to add corrosion inhibitors and oxygen scavengers in acidic solutions to control external casing corrosion, their real efficiency is unknown yet. Therefore, it is important to establish how aggressive to steel are the different hostile environments to help decide which acidic systems can be used. A comparative evaluation of the corrosion of steel immersed in hardened cement slurries submitted to commonly acidizing agents is suggested. The performance of Special Class Portland Cement Slurries reinforced with polished SAE 1045 steel was evaluated by electrochemical measurements as a function of time. Open circuit potential, polarization curves and electrochemical impedance spectrosc...
The standards for the environmental quality required by the European Community are very demanding in what concerns traffic noise. The interaction tire/road is undoubtedly one of the main sources of traffic noise. Nevertheless, standards do not account for the increase in the noise level caused by rain falling onto road surfaces. Therefore, the aim of this work is to study the effects of water on pass-by noise since the weather is rainy about 25 per cent of the year in Portugal. Thus, it addresses two currently used pavement surfaces, porous asphalt and dense asphalt, constructed in a motorway. A version of the Statistical Pass-By Method was used to assess noise levels with dry and wet surfaces, using a selected set of heavy and light vehicles. The results include analysis of the statistical pass-by index, pressure noise levels and nois...
The low regeneration potential of the central nervous system (CNS) represents a challenge for the development of new therapeutic strategies. Mesenchymal stem cells (MSCs) have been proposed as a possible therapeutic tool for CNS disorders. In addition to their differentiation potential, it is well accepted nowadays that their beneficial actions can also be mediated by their secretome. Indeed, it was already demonstrated, both in vitro and in vivo, that MSCs are able to secrete a broad range of neuroregulatory factors that promote an increase in neurogenesis, inhibition of apoptosis and glial scar formation, immunomodulation, angiogenesis, neuronal and glial cell survival, as well as relevant neuroprotective actions on different pathophysiological contexts. Considering their protective action in lesioned sites, MSCs' secretome might als...
The authors focused on the teaching practice experiences of 224 student teachers. Participants’ viewpoint was assessed using the Inventory of Experiences and Perceptions of the Teaching Practice (Caires & Almeida, 2001) at the beginning and the end of the practice year. The authors examined changes in their perceptions and the effect of personal and contextual variables on the students’ experiences. Special attention was given to students’ socioemotional adjustment and its predictors. Results show growing levels of adaptation and satisfaction, and the influence of gender, graduate course background, 4th-year grade, and school setting on their experiences. School resources and acceptance, supervisor’s guidance and support, and the feeling of vocational fulfillment were identified as determinant factors of students’ socioemotional adjust...
This paper presents a theoretical analysis of perfect gas flow over a convex corner of a rigid-body contour. It is assumed that the flow is subsonic before the corner. It accelerates around the corner to become supersonic, and then undergoes an additional acceleration in the expansion Prandtl–Meyer fan that forms in the supersonic part of the flow behind the corner. The entire process is described by a self-similar solution of the K´arm´an–Guderley equation. The latter shows that the boundary layer approaching the apex of the corner is exposed to a singular pressure gradient, dp/dx ∼ (−x)−3/5, where x denotes the coordinate measured along the body surface from the corner apex. Under these conditions, the solution for the boundary layer also develops a singularity. In particular, the longitudinal velocity near the body surface behaves a...
Reactivation of telomerase has been implicated in human tumorigenesis, but the underlying mechanisms remain poorly understood. Here we report the presence of recurrent somatic mutations in the TERT promoter in cancers of the central nervous system (43%), bladder (59%), thyroid (follicular cell-derived, 10%) and skin (melanoma, 29%). In thyroid cancers, the presence of TERT promoter mutations (when occurring together with BRAF mutations) is significantly associated with higher TERT mRNA expression, and in glioblastoma we find a trend for increased telomerase expression in cases harbouring TERT promoter mutations. Both in thyroid cancers and glioblastoma, TERT promoter mutations are significantly associated with older age of the patients. Our results show that TERT promoter mutations are relatively frequent in specific types of human can...
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