1,521 research outputs found
Impact of macroeconomic indicators on bankruptcy prediction models: case of the Portuguese construction sector
The importance of macroeconomic indicators on the performance of bankruptcy prediction models has been a contentious issue, due in part to a lack of empirical evidence. Most indicators are primarily centered around a company's internal environment, overlooking the impact of the economic cycle on the status of the company. This research brings awareness about the combination of microeconomic and macroeconomic factors. To do this, a new model based on logistic regression was combined with principal component analysis to determine the indicators that best explained the variations in the dataset studied. The sample used comprised data from 1,832 Portuguese construction companies from 2009 to 2019. The empirical results demonstrated an average accuracy rate of 90% up until three years before the bankruptcy. The microeconomic indicators with statistical significance fell within the category of liquidity ratios, solvency and financial autonomy ratios. Regarding the macroeconomic indicators, the gross domestic product and birth rate of enterprises proved to increase the accuracy of bankruptcy prediction more than using only microeconomic factors. A practical implication of the results obtained is that construction companies, as well as investors, government agencies and banks, can use the suggested model as a decision-support system. Furthermore, consistent use can lead to an effective method of preventing bankruptcy by spotting early warning indicators
Activation of adenosine A2A receptors induces TrkB translocation and increases BDNF-mediated phospho-TrkB localization in lipid rafts : implications for neuromodulation
Copyright © 2010 the authorsBrain-derived neurotrophic factor (BDNF) signaling is critical for neuronal development and transmission. Recruitment of TrkB receptors to lipid rafts has been hown to be necessary for the activation of specific signaling pathways and modulation of neurotransmitter release by BDNF. Since TrkB receptors are known to be modulated by adenosine A2A receptor activation, we hypothesized that activation of A2A receptors could influence TrkB receptor localization among different membrane microdomains. We found that adenosine A2A receptor agonists increased the levels of TrkB receptors in the lipid raft fraction of cortical membranes and potentiated BDNF-induced augmentation of phosphorylated TrkB levels in lipid rafts. Blockade of the clathrin-mediated endocytosis with monodansylcadaverine(100µM) did not modify the effects of theA2A receptor agonists but significantly impairedBDNFeffects on TrkB recruitment to lipid rafts.
The effect of A2A receptor activation in TrkB localization was mimicked by 5 µM forskolin, an adenylyl cyclase activator. Also, it was blocked by the PKA inhibitors Rp-cAMPs and PKI-(14 –22), and by the Src-family kinase inhibitor PP2. Moreover, removal of endogenous adenosine or disruption of lipid rafts reduced BDNF stimulatory effects on glutamate release from cortical synaptosomes.
Lipid raft integrity was also required for the effects of BDNF on hippocampal long-term potentiation at CA1 synapses. Our data
demonstrate, for the first time, a BDNF-independent recruitment of TrkB receptors to lipid rafts induced by activation of adenosine A2A receptors, with functional consequences for TrkB phosphorylation and BDNF-induced modulation of neurotransmitter
release and hippocampal plasticity.Supported by Fundacão para a Ciência e a Tecnologia (SFRH/BD/21374/2005 for N.A.L., SFRH/BD/21359/2005 for V.C.S., and SFRH/BPD/11528/2002 for D.B.P.) and by the European Union [European Cooperation in Science and Technology (COST) COST B30 concerted action, Neural Regeneration and Plasticity (NEREPLAS)]
Comparative studies of ultrasound and membrane emulsification for the production of stable Perfluorocarbon-in-water nanoemulsions
Low-molecular weight perfluorocarbons (PFCs) are usually chemically and biologically inert, clear, colorless liquids, presenting a high affinity for many gases, namely for O2, NO and CO2, which turn them particularly suitable in various biomedical applications involving gas capture, transport and release. In fact, PFC-in-Water emulsions were one of the two major classes of systems proposed as blood substitutes and for O2/NO therapeutics. However there are still some important issues concerning this type of systems which have limited their efficiency, approval and commercial success, namely those related to emulsion stability, hydrodynamic size distribution and reduced shelf-lives. Stability issues can easily lead to PFC diffusion in water, to aggregation and to the consequent hydrodynamic size increase and emulsion degradation [1].
Nanoemulsions (typically within a range of hydrodynamic sizes of 10-100 nm) exhibit various advantages over typical microemulsions [2]. Hence, our aim is to produce monodisperse PFC nanoemulsions presenting larger surface-to-volume ratios, enhanced stabilities and more efficient gas capture/delivery properties. A first approach to achieve these goals is to prepare and to study a mixed surfactant system based on Tween 80 and on a perfluorinated surfactant (perfluorooctyl phosphocholine) at different relative compositions.
PFC-in-Water nanoemulsions were produced by using the traditional ultrasound emulsification method (500W). The effects of co-surfactants relative compositions on CMC values, on the kinetics of emulsion formation and on the corresponding stabilities of prepared nanoemulsions were evaluated. Hydrodynamic sizes and Zeta-potentials were also assessed, being able to obtain stable nanoemulsions with hydrodynamic sizes between 150 and 200 nm. In a comparative study, PFC-in-Water nanoemulsions were also produced by membrane emulsification. This low energy-intensive technique has received increasing interest as it allows more flexible operating conditions. Regenerated cellulose membranes such as Nadir UC500 and Millipore Ultracel RC100, polyethersulphone membranes such as Nadir UP150 and Millipore PBHK04310, and a promising polycarbonate Whatman Track-ethched 30 nm Nuclepore membrane, were employed to produce nanoemulsions, and using the same mixed surfactant system and relative compositions. The energy inputs of these two methods were compared and discussed along with their efficiencies in terms of producing nanoemulsions presenting improved stabilities, smaller hydrodynamic sizes and narrower hydrodynamic size distributions.
References
[1] M.P. Krafft, A. Chittofrati, J.G. Riess, Curr Opin in Colloid Interface Sci., 8 (2003) 251–258
[2] E. Piacentini, E. Drioli, L. Giorno, J. of Membr. Sci., 468 (2014) 410–42
Thienylpyrrole azo dyes: synthesis, solvatochromic and electrochemical properties
The synthesis and the evaluation of solvatochromic and electrochemical properties of new donor-acceptor-substituted thienylpyrrole azo dyes 3 are described. These derivatives exhibit dramatic changes in both their electronic and redox properties in comparison with thienylpyrroles 1. In agreement with the solvatochromic and electrochemical studies of push-pull derivatives 3 the new compounds prepared, may find application in the manufacture of new materials with notable non-linear optical properties.Fundação para a Ciència e Tecnologia - POCTI/QUI/37816/2001
Donor-acceptor substituted thienylpyrrole azo dyes: synthesis, solvatochromic and electrochemical properties
The synthesis of thienyl- substituted pyrrole azo dyes and their UV-visible, solvatochromic and electrochemical properties are described. In agreement with the solvatochromic data and also with the electrochemical study the new donor-acceptor systems synthesized could have applications in NLO.Fundação para a Ciência e Tecnologia (FCT
Synthesis of formyl-thienylpyrroles : versatile building blocks for NLO materials
Several formyl-substituted 1-alkyl(aryl)-2-(2´-thienyl)pyrroles 3-7 were synthesized by functionalization of the pyrrole or thiophene ring of thienylpyrroles 2 using different methods: Vilsmeier formylation or metalation followed by reaction with DMF.Fundação para a Ciência e Tecnologi
Effects of concurrent strenght and endurance training sequence order on physical fitness performance in adolescent students
The aim of the study was to examine the effect of the sequence order of concurrent training on physical
performance in students. 31 subjects were recruited from a Portuguese public high school and were randomly
divided in strength training followed by endurance exercise group (GSE, n=12) and endurance followed by
strength training group (GAS, n=11). The training program was performed during physical education classes, 2
times per week during 10 weeks. Anthropometrics and physical variables were assessed before (M1), after 5
weeks of training (M2) and after the training period (M3). Training‐induced significant differences in both
groups after the training program [1kg and 3kg medicine ball throw gains (GES: 4.6 to 6.3%, and 3.9 to 6.0%,
GSE: 5.0 to 9.3% and 3.0 to 8.4%), VO2max (GES: 2.3 to 3.7%, GSE: 2.8 to 8.0%), push-ups (GES: 11.7 to
12.5%; GSE: 13.3 to 23.5%), standing long jump (GES: 5.1 to 4.3%, GSE: 2.9 to 5.3%), counter movement
jump (GES: 5.1 to 4.3%, GES: 3.1 to 8.1%) and sprint running 20m (GES: -1.5 to -1.2%, GSE: -1.0 to -1.7%).
Independently of the sequence order, concurrent training appear to change body composition and increase
physical fitness in students during physical education classes.info:eu-repo/semantics/publishedVersio
The path from the choroid plexus to the subventricular zone: go with the flow!
In adult mammals, under physiological conditions, neurogenesis, the process of generating new functional neurons from precursor cells, occurs mainly in two brain areas: the subgranular zone in the dentate gyrus of the hippocampus, and the subventricular zone (SVZ) lining the walls of the brain lateral ventricles. Taking into account the location of the SVZ and the cytoarchitecture of this periventricular neural progenitor cell niche, namely the fact that the slow dividing primary progenitor cells (type B cells) of the SVZ extend an apical primary cilium toward the brain ventricular space which is filled with cerebrospinal fluid (CSF), it becomes likely that the composition of the CSF can modulate both self-renewal, proliferation and differentiation of SVZ neural stem cells. The major site of CSF synthesis is the choroid plexus (CP); quite surprisingly, however, it is still largely unknown the contribution of molecules specifically secreted by the adult CP as modulators of the SVZ adult neurogenesis. This is even more relevant in light of recent evidence showing the ability of the CP to adapt its transcriptome and secretome to various physiologic and pathologic stimuli. By giving particular emphasizes to growth factors and axonal guidance molecules we will illustrate how CP-born molecules might play an important role in the SVZ niche cell population dynamics.Ana M. Falcão and Ashley Novais are recipients of Ph.D.Fellowships from the Fundação para a Ciência e Tecnologia (FCT,Portugal).Fernanda Marques is a recipiente of post docToral fellowship from the Fundação para a Ciência e Tecnologia
(FCT,Portugal).This work is supported by a grant from FCT (PTDC/SAU-OSM/104475/2008
Evaluation of healthy and sensory indexes of sweetened beverages using an electronic tongue
Overconsumption of sugar-sweetened beverages may increase the risk of health problems and so, the evaluation of their glycemic load and fructose-intolerance level is essential since it may allow establishing possible relations between physiologic effects of sugar-rich beverages and health. In this work, an electronic tongue was used to accurately classify beverages according to glycemic load (low, medium or high load) as well to their adequacy for people suffering from fructose malabsorption syndrome (tolerable or not): 100% of correct classifications (leave-one-out cross-validation) using linear discriminant models based on potentiomentric signals selected by a meta-heuristic simulated annealing algorithm. These results may be partially explained by the electronic tongue’s capability to mimic the human sweetness perception and total acid flavor of beverages, which can be related with glycemic load and fructose-intolerance index. Finally, the E-tongue was also applied to quantify, accurately, healthy and sensory indexes using multiple linear regression models (leave-one-out cross-validation: Radj > 0.99) in the following dynamic ranges: 4.7 < glycemic load ≤ 30; 0.4 < fructose intolerance index ≤ 1.5; 32 < sweetness perception < 155; 1.3 < total acid flavor, g L−1 < 8.3; and, 5.8 < well-balanced flavor ≤ 74. So, the proposed electronic tongue could be used as a practical, fast, low-cost and green tool for beverage’s healthy and sensory evaluation.This work was partially co-financed by FCT and FEDER under Program COMPETE (Project PEst-C/EQB/LA0020/2013); by the Strategic Project PEst-OE/EQB/LA0023/2013 and by the project ref. RECI/BBB-EBI/0179/2012 (project number FCOMP-01-0124-FEDER-027462) funded by Fundacao para a Ciencia e a Tecnologia
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