Tényelleni (counter-factual) gondolkodás egyetemi tanulási kontextusban

Mikor egy negatív élményt élünk át életünk során, gyakran gondolkozunk el azon, mennyire másképp alakulhattak volna a dolgok, ha akár csak a végeredményt megelőző egyetlen előzmény más lett volna. Az ilyen jellegű gondolatokat nevezzük tényelleni (counter-factual) gondolatoknak: ezek olyan mentális alternatívát nyújtanak számunkra a valósággal szemben, amely jellegénél és idődimenziójánál fogva kitágítja kognitív és érzelmi tapasztalatainkat a valós határokon túl

Utilização de georadar na caracterização da evolução do dano estrutural de uma parede: ensaio à escala real

Ao longo do tempo o património edificado deteriora-se devido a causas naturais ou antrópicas. A acção sísmica é um factor que pode provocar danos estruturais nas paredes das construções tradicionais, por vezes até imperceptíveis à vista desarmada. A Geofísica aplicada proporciona técnicas de elevada resolução que permitem detectar alvos de pequenas dimensões, como por exemplo fendas na estrutura interna de paredes. O georadar, técnica não invasiva, utiliza impulsos electromagnéticos de frequências variando de dezenas de MHz a GHz que permitem uma elevada resolução dos meios a investigar. A utilização destas técnicas na caracterização interna de paredes exige a utilização de gamas de frequências elevadas (> 1GHz) de forma que pequenas fissuras sejam detectadas. A evolução do dano de uma estrutura tradicional de alvenaria sujeita a diferentes solicitações, como as acções sísmicas, pode ser monitorizada por medidas de georadar. Por outro lado, poderá ainda ser viável a utilização de medidas de georadar na avaliação da eficácia de soluções de reparação de fissuras por injecção de caldas. Na região de Aveiro as paredes estruturais eram tradicionalmente realizadas em adobe. Para avaliar a viabilidade da aplicação do georadar na caracterização interna destas estruturas, no Departamento de Engenharia Civil da Universidade de Aveiro foi construída uma parede em adobe, com blocos de adobe recuperados das construções existentes, e segundo as técnicas e métodos tradicionais. Esta parede foi inicialmente sujeita a uma solicitação cíclica de amplitude crescente que lhe produziu danos estruturais significativos. Estes danos foram posteriormente reparados com recurso à injecção de uma calda à base de cal hidráulica. Após reparação dos danos, a parede foi reforçada com uma malha polimérica embebida no reboco e esta foi sujeita a um ensaio cíclico de amplitude crescente até ao seu colapso. Foram recolhidos dados de georadar (1.6 GHz) sobre a parede, antes e durante o ensaio da parede reforçada, que permitiram caracterizar os danos iniciais, a eficiência da injecção da calda na colmatação das fissuras e a evolução dos danos estruturais provocados ao longo do ensaio. Os resultados são discutidos e permitem justificar plenamente a utilização do georadar na caracterização interna de estruturas de paredes. Demonstra-se que o georadar é uma ferramenta não intrusiva de elevada resolução a utilizar na avaliação do dano em construções existentes

Abnormal grain growth in pressure assisted sintering of BaLa4Ti4O15

The application of compressive stresses during sintering is known to be an efficient way to eliminate porosity at lower temperatures by the direct positive effect on the sintering driving force. Therefore, it is the basis of some special sintering techniques, such as: Hot pressing (HP), Hot isostatic pressing (HIP), Hot forging (HF) and, together with the electric field, in the Electric field assisted sintering (EFAS). Despite the fact that the role of applied stress on the densification is well established, its effect on the movement of grain boundaries (GBs) for grain growth in 2D/3D ceramics has not been sufficiently addressed in sintering models. We have been investigating this topic in functional titanate materials, namely in BaLa4Ti4O15 (BLT), a key material in microwave applications due to its high permittivity, high quality factor Q (low dielectric losses) and low temperature coefficient of resonant frequency. The microstructure developed during sintering, in special the anisotropic grain growth, was found to alter the electrical properties of ceramic samples and films [1]. We have reported for the first time that the GB mobility was shown to be dependent on the external stresses created or applied during sintering and that stress assisted sintered samples present enhanced anisotropic grain growth [2,3]. In this work, pressure assisted sintering was applied to BLT and particular attention was given to the microstructure with statistical analysis of the grain size distributions to clarify the role of stresses on the grain growth phenomena. HIP with 65 MPa, HP with 60 MPa and conventional sintering, without any external pressure (CS), for comparison, were used to design microstructures with different grain size distributions, keeping the same thermal history for all the samples. Based on cross section and top view Scanning Electron Microscopy (SEM) micrographs, the grain size was evaluated by measuring the area of the elongated grains. Samples were thinned down to 20 µm using precision ion polishing system for High Resolution Transmission Electron Microscopy (HRTEM) studies. Via the stereological analysis of the grain size distribution, which was separated into two populations, i.e., normal (NGs) and abnormal grains (AGs), we verified that the main effect of external pressure lies on triggering AG growth, increasing both the number and size of AGs and leading to a more anisotropic grain growth (more elongated and oriented grains), whereas not a significant change was found for the grain growth of the NGs population. Complementarily, the HRTEM analysis showed that the structure of grains and GBs is quite different in stress assisted samples, presenting a larger density of crystal imperfections and thicker GB disorder regions than in CS samples

AN AXON'S JOURNEY TO FIND ITS PATH: IN VIVO CHARACTERIZATION OF THE MODULATORS AND EFFECTORS OF THE RAC GTPASE SIGNALING PATHWAY INVOLVED IN AXON GUIDANCE

The molecular mechanisms leading to axonal guidance are vital for the proper wiring of the nervous system. Many psychiatric disorders may arise from the improper development of the brain. If an axon does not form, or is extended to a place where it is not supposed to be, proper synapses will not form and communication between neurons and neighbor cells will be affected. An axon is extended after the migration of the growth cone. Filopodia and lamellipodia are extended from the growth cone in order to sense the environment for guidance cues. Once signaled, the growth cone migrates to its final target and the axon is developed. A class of proteins called the Rac GTPases is essential for the process of axon pathfinding. In the model nematode Caenorhabditis elegans, MIG-2/RhoG and CED-10/Rac1 are the two redundant Rac GTPases involved in growth cone migration. The main role of Rac GTPases in axon guidance is due to its control over the actin cytoskeleton. The actin-binding UNC-115/abLIM acts downstream of CED-10/Rac1 in axon pathfinding. In Chapters II and III, I describe how Rac signaling activates UNC-115/abLIM. I propose that the scaffolding protein RACK-1 recruits UNC-115/abLIM to the plasma membrane and brings other molecules, such as PKC, for its modulation. Rac GTPases switch between an inactive, GDP-bound form, to an active, GTP-bound form. Activation can be aided by guanine-nucleotide exchange factors (GEFs), and inactivation is enhanced by GTPase activating proteins (GAPs). UNC-73/Trio is a GEF that acts with both MIG-2/RhoG and CED-10/Rac1 in axon guidance. Nevertheless, mutations that disrupt the Rac GEF activity of UNC-73/Trio do not affect axon pathfinding to the same levels as the abolishment of Rac activity seen in the double mutant of mig-2 and ced-10. Along with other evidence, this suggested that there were other molecules involved in the control of Rac GTPases in this process. I performed a candidate-based genetic screen in the C. elegans genome in order to find other DH-containing GEFs that could potentially interact with MIG-2/RhoG and CED-10/Rac1. In Chapter IV, I show that the Rac GEF TIAM-1 acts upstream of MIG-2/RhoG and CED-10/Rac1 as a linker between these GTPases and CDC-42, another member of the Rho subfamily of small GTPases. Moreover, previous studies have implicated Rac GTPases, but not UNC-73/Trio, in the UNC-6/Netrin attractive signaling system. I show that TIAM-1 is the GEF recruited for this system. In Chapter V I show that other GEFs are also involved in this process. The Rac GEF PIX-1/βPIX, and two CDC-42 GEFs, UIG-1/Clg and EXC-5/FGD1, are also involved in the control of Rac GTPases during axon development. In summary, my work has shown how Rac GTPases control the activity of the actin-binding protein UNC-115/abLIM, and how Rac GTPases themselves are controlled during the process of axon guidance

Perceptions of expertise : a determinant factor on the acceptance of user-designed products

the traditional paradigm of innovation in which consumers are merely buyers, firms are increasingly drawing on their user communities to conceptualize new products. Innovation scholars acknowledge this process as beneficial for both firms and observing consumers (consumers not involved in the conceptualization process). However, some caveats were made regarding the expertise of users when conceiving products that are either complex, luxurious or when knowledge about technical details such as materials or components is needed. This research aims to investigate whether observing consumers perceive users (vis-à-vis professional designers) to possess enough expertise to design products ideated around technical and functional details. Additionally, two moderators of this effect are studied: observing consumers’ uncertainty avoidance beliefs and perceptions of similarity these have towards the creators of new products. We conducted an experimental study using two design modes: products designed by users or by firms’ professionals. The data have been collected in MTurk measuring participants’ perceptions of expertise and purchase intentions. The results show that consumers prefer professionals’ input for these products due to higher perceptions of expertise (that also lead to higher quality perceptions). Additionally, we find that this preference is exacerbated for high uncertainty-avoiding consumers and that expertise perceptions mediate purchase intentions differently depending on the perceptions of similarity that observing consumers have towards the creators of a product. This study adds to the innovation literature by showing that consumers’ involvement in NPD is not universally beneficial and that uncertainty avoidance beliefs and perceptions of similarity are two critical boundary conditions

Managing Royal Buildings in Medieval and Early Modern Portugal

UIDB/00417/2020 UIDP/00417/2020publishersversionpublishe

Electromagnetic prospection in time domain applied to Olhos da Fervença, Cantanhede (Central Portugal)

Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)A exsurgência cársica do sistema Jurássico Olhos da Fervença localiza-se no concelho de Cantanhede, distrito de Coimbra e ocorre no leito da Ribeira da Corujeira, sob uma forma borbulhante, como se fervesse. A formação jurássica está subjacente a uma cobertura de areias de duna, que impede a sua observação directa, recorrendo-se neste estudo à utilização de prospecção electromagnética no domínio do tempo, com o equipamento TEM-FAST 48. Realizaram-se 24 sondagens electromagnéticas cuja interpretação permitiu identificar estruturas de fracturação associadas à ocorrência da exsurgência.The karstic exsurgence of the Jurassic system Olhos da Fervença is located in Cantanhede region, Coimbra district (centre of Portugal) and occurs sparkling in the Ribeira da Corujeira stream. The Jurassic formation is under dune sands and is not possible to observe it directly. This study with electromagnetic prospection in the time domain uses TEM-FAST 48 equipment. The results of the interpretation of the 24 electromagnetic soundings allow the identification of fracture structures associated to the exsurgence