1,319 research outputs found

    Ambivalence and innovative moments in grief psychotherapy: the cases of Emily and Rose

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    Several studies have suggested that the process of narrative change in psychotherapy occurs through the emergence and expansion of moments of novelty, known as innovative moments (IMs), that allow changes in the problematic self-narrative responsible for the client’s suffering. However, as these IMs challenge typical (and problematic) ways of acting, feeling, and thinking, they may also generate discrepancy or uncertainty. Clients may reduce uncertainty by returning to the problematic self-narrative immediately after the emergence of an IM, thus ensuring the homeostasis of the previous meaning system. This cyclical movement is a form of ambivalence, which can maintain problematic stability across therapy and lead to therapeutic failure. In this study, we identified return to the problem markers (RPMs), which are empirical indicators of the ambivalence process, for all IMs in two cases of constructivist grief psychotherapy. Both cases evidenced a high percentage of IMs with RPMs, and the evolution of IMs and RPMs along treatment was significantly correlated. We suggest that stability of the ambivalence process in grief psychotherapy may represent a form of self-protection from the anxiety or guilt of releasing pain as a disconnection from the deceased

    Dynamic behaviour of single droplets impinging upon liquid films with variable thickness: Jet a-1 and hvo mixtures

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    Fortunately, the human being has already started to be environmentally concerned and the search for new alternatives to reduce pollution increased. Transports are responsible for a significant portion and it is extremely necessary to bet on alternatives to oil. The introduction of biofuels in aero-engines could be an example. In order to modify and optimize piston engines and gas turbines to operate efficiently with alternative fuels, this work used Jet Fuel and Biofuel mixtures. The focus of these studies was to visualize the dynamic behavior of single droplets impinging upon liquid films with variable thickness. The existence of splash as well as its characteristics were reported and the differences and similarities between the outcomes according to the impact conditions and the fluid properties were catalogued. To achieve that an experimental facility was designed and built. Four fluids were tested: water (as reference), 100% Jet A-1, 75%/25% and 50%/50% mixtures of Jet A-1 and HVO (Hydro-processed Vegetable Oil), respectively, since civil aviation only accept mixtures with at least 50% Jet Fuel in volume. The fluid properties were measured to ensure accuracy. The liquid film depths considered were 10%, 50% and 100% of the droplet diameter. A high-speed digital camera was used to image acquisition and the droplet was released by a syringe pump connected to the needle at a specific pumping rate. The impact surface was a perspex container filled with fluid. Five needles with different inner diameters and three impact heights were employed to provide a variety of Weber and Reynolds numbers.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    The splash deposition transition limits of a biofuel droplet wall impact with a and without crossflow

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    Over the last years, there have been many investigations into new ways to obtain clean and efficient energy production. In this spirit, this study aims to successfully adapt low emission aero-engines combustors to burn biofuels. Biofuels are the immediate alternative to fossil-fuel powered aero-engines, given that by regulation is possible to apply today, a biofuel into the aeronautical industry. There are some regulations to have into account, being the biggest one the fact that the new blend must be constituted of at least 50% of conventional jet fuel (JF). In this work were selected four blends to study: 100% JF; 75% JF and 25% NEXBTL (biofuel); 50% JF and 50% NEXBTL and H2O. A smooth, dry aluminium plate was used as the impact surface and the objective was to observe the splash-deposition limits and characterize the dynamic behaviour of the droplets with and without crossflow. Different velocities of the crossflow were chosen and the impact angle of the droplet was also analysed. The splash-deposition threshold was also compared with those proposed by other authors.Fundação para a Ciência e a Tecnologia (FCT)info:eu-repo/semantics/publishedVersio

    Experimental Study of a Single Droplet Impinging Upon a Heated Dry Surface Using Jet Fuel and Biofuel Mixtures

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    The aeronautical sector is dependent on fossil fuels which contribute to a considerable amount of pollutant emissions to the atmosphere. In an attempt to reduce these pollutant emissions in a short period of time and without several changes to the aircraft and their engines, this study focuses on the physical phenomena that happen inside the combustion chamber of an internal combustion engine during fuel injection. However, instead of considering only a conventional jet fuel, an alternative fuel is also investigated. The mixture is composed of at least 50% in volume of conventional jet fuel, as demanded by the current legislation, and a biofuel to decrease the consumption of petroleum-based fuels and to reduce pollutant emissions. The main goal of this study is to experimentally observe droplet impact on a heated dry stainless-steel surface for different fuel mixtures, impact energies (Weber number between 174 and 955, and Reynolds number between 1099 and 12365), and wall temperatures (Tw = 20 − 300 ºC) to identify the different heat regimes and the physical differences between the distinct sets of impact conditions. To achieve that purpose an experimental setup was designed and built including the acquisition of high-speed images, a droplet dispensing system, a heating device to accurately control the temperature of the target surface and the illumination of the impact site. To enhance the knowledge about the impacts, three different perspectives of the phenomena were captured. The typical front perspective, a second perspective where the camera has a ≈ 20◦ angle to the impact surface to capture more details of the impact, and finally, at a lower frame rate, an isometric perspective to measure the evaporation time. From these data, the impact regimes were identified and the influence of surface temperature, fluid properties, and impact energy was analyzed.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Activation of adenosine A2A receptors induces TrkB translocation and increases BDNF-mediated phospho-TrkB localization in lipid rafts : implications for neuromodulation

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    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)]

    Ambivalence in grief therapy: the interplay between change and self-stability

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    This article explores the role of ambivalence in grief therapy within a narrative framework. From this perspective, change starts with the occurrence of innovative moments, which can be nullified by reaffirmation of the problematic self-narrative as a sign of ambivalence. This study analyzed ambivalence in six complicated grief cases using the “Return to the Problem Coding System.” Markers of ambivalence emerged in all cases, with a decreasing profile in cases with greater symptomatic improvement, suggesting an association between clinical change and ambivalence evolution in therapy. Addressing ambivalence may bring to light important aspects of client’s selfreconstruction after a major loss.Portuguese Foundation for Science and Technology, through the Grant PTDC/PSI-PCL/121525/2010 (Ambivalence and Unsuccessful Psychotherapy,2012–2015) and the PhD Grant SFRH/BD/48607/200

    Insights on bubble encapsulation after drop impact on thin liquid films

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    The accurate understanding of the phenomenology of drop impact onto dry/ wetted and cold/heated surfaces is increasingly relevant to implement biofuels in civil aviation. The outcome of drop impact depends on the pre-impact conditions and a seldom researched event is the encapsulation of a bubble when this impact occurs on thin liquid films. Therefore, the goal of the experimental work reported is to investigate the mechanism of this bubble encapsulation. Results show that the mechanism leading to a bubble formation has two stages. In the first stage, after the drop impacts a steady liquid film, a prompt splash occurs followed by a crown splash. The uprising sheet propagates in an almost normal direction relative to the liquid film, but its radius at the base continues to expand, eventually leading to the inward collapse of the crown-bounding rim encapsulating air inside the dome. In the second stage, three different phenomenologies of bubble encapsulation can occur. At the top of the closed crown, one jet (phenomenology 1) or two jets are formed (phenomenologies 2 and 3). For phenomenology 2, the upward jet eventually collapses due to gravitational influence, while the downward jet continues to grow until it reaches the liquid film, attaching to it, stretching and detaching from the top at the hemispheric thin sheet, forming a bubble. In phenomenology 3, the upward jet is high enough to allow its breakup and ejection of one large droplet before the collapse of the upward jet. Many secondary droplets fall on the bubble and one of them will eventually break the dome, leading to more secondary atomization. Additionally, the first perturbation imposed on the liquid film by the droplet impact is studied and an empirical correlation is proposed for its propagation velocity. Finally, bubble geometry is investigated.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Analysis And Visualization Of The Perturbations Imposed On The Liquid Film By Crown Sheet Collapse Or Closure

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    Bubble encapsulation is a phenomenon that results from droplet impact on a liquid film for very specific impact conditions. After splashing, the crown liquid sheet starts to bend inwards, and eventually, the jets at the top of the crown merge and form a perfect empty bubble. This bubble bursts due to the impingement of a secondary droplet that falls in the spherical dome or by reaching its critical thickness. However, bubble encapsulation is seldom reported in the literature. Due to that, this work focuses on understanding better its dynamics and formation mechanisms. By using a bottom perspective of the phenomenon, important information about its dynamics is disclosed. From the bottom shadowgraphs, the capillary waves and the perturbations imposed on the steady liquid film are clearly observed. From previous works, it was confirmed that its occurrence is systematic, so, one of the goals of this study is to realize how the impact conditions influence the phenomenon and if we can establish a criterion for its occurrence. Despite the scarce information about the phenomenon, there are some works about it that are focused on the cavity underneath the bubble. In this study, we observed the cavity and conclude that the cavity shape does not influence the bubble encapsulation phenomenon. Finally, the crown closure time was measured for a specific set of impact conditions and it was analyzed depending on the dimensionless thickness of the liquid film.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Insights on Bubbling Formation after Drop Impact on Thin Liquid Films

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    Over the years, the phenomena obtained when a drop impinges upon a dry, wetted or heated surface have been thoroughly studied. In previous works, the existence of splash was investigated by the authors with the goal of evaluating the possible implementation of biofuels in the civil aviation and it was found an episode of a phenomenon, seldom reported in the literature under specific pre-impingement conditions. The mechanism that leads to a bubble formation has two stages. After the drop impacts a steady liquid film, prompt splash occurs followed by crown splash. In the first stages of crown splash, the uprising sheet propagates almost normal to the liquid film, but its radius at the base continues to expand, eventually leading to the inward collapse of the crown bounding rim. Thus, the top of the crown closes in a bubble-like shape with the formation of two jets, one upwards and other downwards. The upward jet eventually disappears due to gravitational influence, while the downward jet continues to grow until it reaches the liquid film, attaching to it, stretching and detaching from the top at the hemispheric thin-sheet, forming a perfect bubble. Many secondary droplets fall on the bubble and one of them will eventually break the dome, leading to more secondary atomization. The few works reported in the literature referring to this phenomenon as “bubbling” or “floating bubble,” scarcely explore the hydrodynamic mechanism associated with this bubble formation and occurrence, mainly focusing on droplets impacting upon deep pools. However, in a previous study, the authors observed this event for a liquid film dimensionless thickness of 0:5 in a fluid mixture of Jet A-1 and biofuel NEXBTL. In this study, the impact conditions in the experiments performed allow to recreate the floating bubble with 100% of occurrence. After that, the authors present an extensive characterization of the bubbling phenomenon to understand better the mechanisms which lead to its formation, as well as its practical significance. A high-speed digital camera acquires several images of the floating bubble formation from different points of view (side and bottom). Namely, capturing the phenomenon from below, high-quality images allow retrieving essential data to describe the hydrodynamic mechanism accurately. The most relevant features include the bubble height and diameter, and the propagation velocity of the first perturbation imposed on the liquid film.info:eu-repo/semantics/publishedVersio

    Development of bio-hybrid piezoresistive nanocomposites using silk-elastin protein copolymers

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    Recombinant silk-elastin-like protein (SELP)/carbon nanotubes (CNTs) nanocomposite films with different amounts of CNTs (1, 3 and 6wt%) were prepared by solvent casting. The produced films were stabilized by exposure to methanol that induces an increase of the -structure content. The CNTs were homogeneously distributed into the SELP matrix and did not induce significant alterations into its chemical structure. The incorporation of CNTs also increased the thermal stability of the films. Further, the incorporation of 1wt% of CNTs greatly improved the mechanical properties of the SELP matrix leading to a 6-fold increase in strain-to-failure and to increase the ultimate tensile strength with minor differences in modulus of elasticity. The nanocomposites exhibited a good linearity between deformation and electrical resistance variation with electrical conductivity increasing with the nanofiller content up to 0.8Sm1. Finally, the produced nanocomposites were non-cytotoxic indicating their suitability for biomedical applications.This work was supported by national funds through FCT I.P. (Fundação para a Ciência e Tecnologia, Portugal) and by the European Regional Development Fund (ERDF) through COMPETE2020 Programa Operacional Competitividade e Internacionalização (POCI, Portugal) in the framework of the Strategic Programs UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) and UID/FIS/04650/2013. This work was also supported by the strategic programme UID/BIA/04050/2019 funded by national funds through FCT I.P. The present work was also supported by FCT I.P. within the ERA-NET IB-2 project FunBioPlas (ERA-IB-2-6/0004/2014), EuroNanoMed 2016 call and project LungChek ENMed/0049/2016. DMC, SR and CR also thank FCT I.P. for the grants SFRH/BPD/121526/2016, SFRH/BD/111478/2015, and SFRH/BPD/90870/2012, respectively. This article is a result of the project EcoAgriFood [NORTE-01-0145-FEDER-000009], supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Finally, the authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs.info:eu-repo/semantics/publishedVersio
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