Ser estudante no ensino superior: as respostas institucionais à diversidade de públicos

Textos selecionados a partir de comunicações apresentadas no 2º Seminário “Ser Estudante no Ensino Superior: As respostas institucionais à diversidade de públicos”, realizado pelo ObservatoriUM - Observatório dos Percursos Académicos dos Estudantes da UMinho (Campus de Gualtar, 9 de setembro de 2016).info:eu-repo/semantics/publishedVersio

Boolean Chaos

We observe deterministic chaos in a simple network of electronic logic gates that are not regulated by a clocking signal. The resulting power spectrum is ultra-wide-band, extending from dc to beyond 2 GHz. The observed behavior is reproduced qualitatively using an autonomously updating Boolean model with signal propagation times that depend on the recent history of the gates and filtering of pulses of short duration, whose presence is confirmed experimentally. Electronic Boolean chaos may find application as an ultra-wide-band source of radio wavesComment: 10 pages and 4 figur

Towards an electroless deposition of gold on metallic substrates using ionic liquids as electrolytes

Recent research has suggested a number of applications for gold in fuel cells and related hydrogen fuel processing, which include light weight corrosion resistance bipolar plates and the incorporation of gold as catalyst to provide improvements in electrode conductivity, among others. This paper reports on the electroless deposition of gold on copper substrates from a HAuCl4.3H2O solution in 1-butyl-1- methylpyrrolidinium dicyanamide (BMP-DCA), in laboratory atmospheric conditions. The electrochemical behaviour of the plating solution was studied by potential sweep techniques. Results suggest that gold ions are reduced and deposited on copper without the aid of external polarization, probably by displacement deposition involving copper dissolution, since no other oxidation reaction was identified. Preliminary studies using SEM/EDX showed that compact gold thin films, deposited on copper substrates at 333 K, present a granular nanostructured morphology

Social dominance modulates eavesdropping in zebrafish

Group living animals may eavesdrop on signalling interactions between conspecifics and integrate it with their own past social experience in order to optimize the use of relevant information from others. However, little is known about this interplay between public (eavesdropped) and private social information. To investigate it, we first manipulated the dominance status of bystander zebrafish. Next, we either allowed or prevented bystanders from observing a fight. Finally, we assessed their behaviour towards the winners and losers of the interaction, using a custom-made video-tracking system and directional analysis. We found that only dominant bystanders who had seen the fight revealed a significant increase in directional focus (a measure of attention) towards the losers of the fights. Furthermore, our results indicate that information about the fighters' acquired status was collected from the signalling interaction itself and not from post-interaction status cues, which implies the existence of individual recognition in zebrafish. Thus, we show for the first time that zebrafish, a highly social model organism, eavesdrop on conspecific agonistic interactions and that this process is modulated by the eavesdroppers' dominance status. We suggest that this type of integration of public and private information may be ubiquitous in social learning processes.FCT PhD fellowship: (SFRH/BD/33280/2007), Champalimaud Neuroscience Programme

Chlorella vulgaris as Soil Amendment: influence of encapsulation and enrichment with Rhizobacteria

Several trials with five plant growth-promoting rhizobacteria (PGPR) and the chlorophyte Chlorella vulgaris were carried out in order to look for the consortia that could show the best interactions, giving rise to improved growth of mixed cultures. Pseudomonas putida, Serratia proteomaculans and Stenotrophomonas maltophilia were the chosen bacteria for the consortia with Chlorella, while the proportions of microalgae/bacteria tested were 2:1, 3:1 and 3:1, respectively. Three replicates of 20 treatments were performed and studied, after sowing 20 seeds per replicate, for each of the consortia. Plantlets were left to grow for a two-week period. Maltodextrin (MD) and arabic gum (GA) or gelatine (G) were used as coats for the freeze-dried biomass microbeads. Longest roots were obtained with the consortium Chlorella: Serratia but encapsulates of Chlorella:Stenotrophomonas gave rise to meadow clover plantlets with the highest root and shoot system dried biomass, especially with coating proportions of 1:1 MD:G and MD:GA. Results obtained with this last consortium suggested some interactions with the plant metabolism, as well as some synergistic effects between Chlorella and bacteria.info:eu-repo/semantics/publishedVersio

Model-based estimation of reaction rates in stirred tank bioreactors

In this paper an adaptive model-based algorithm is proposed for the on-line estimation of reaction rates in stirred tank bioreactors. The main design condition imposes that the observation errors reflecting the mismatch between the estimated parameters and the 'true' values follow second-order dynamics of convergence. The gain matrices are shown to be functions of the state and of user-defined damping coefficients and natural periods of oscillation for second-order trajectories. The application of the algorithm is illustrated with a simple case-study involving the estimation of the specific reaction rate for a single substrate, single product scheme.Junta Nacional de Investigação Científica e Tecnológica (JNICT)

Stability, dynamics of convergence and tuning of observer-based kinetics estimators

This work discusses issues concerning stability, tuning and dynamics of convergence of observer-based kinetics estimators. The analysis focuses on both continuous and discrete time formulations of the estimation algorithms. Concerning the former, it is shown that, with proper tuning, stability can be guaranteed, while simultaneously imposing a desired quasi-time invariant second order time response for the convergence of estimates to true values. Concerning the latter, an algorithm is presented, based on a forward Euler discretisation, whose error system is shown to be linear time-invariant. Furthermore, stability conditions were derived, which define the stable domain for the discretisation period as function of the tuning parameters. The theory is illustrated with a case-study of Baker’s yeast fermentation. Results clearly confirm the theoretical developments. In particular, results concerning the stability domain for the Euler-based discrete formulation of the estimator are shown to have relevant practical implications

A new linear parametrization for peak friction coefficient estimation in real time

The correct estimation of the friction coefficient in automotive applications is of paramount importance in the design of effective vehicle safety systems. In this article a new parametrization for estimating the peak friction coefficient, in the tire-road interface, is presented. The proposed parametrization is based on a feedforward neural network (FFNN), trained by the Extreme Learning Machine (ELM) method. Unlike traditional learning techniques for FFNN, typically based on backpropagation and inappropriate for real time implementation, the ELM provides a learning process based on random assignment in the weights between input and the hidden layer. With this approach, the network training becomes much faster, and the unknown parameters can be identified through simple and robust regression methods, such as the Recursive Least Squares. Simulation results, obtained with the CarSim program, demonstrate a good performance of the proposed parametrization; compared with previous methods described in the literature, the proposed method reduces the estimation errors using a model with a lower number of parameters

On the ordeal of quinolone preparation via cyclisation of aryl-enamines; synthesis and structure of ethyl 6-methyl-7-iodo-4-(3-iodo-4-methylphenoxy)-quinoline-3-carboxylate

Recent studies directed to the design of compounds targeting the bc(1) protein complex of Plasmodium falciparum, the parasite responsible for most lethal cases of malaria, identified quinolones (4-oxo-quinolines) with low nanomolar inhibitory activity against both the enzyme and infected erythrocytes. The 4-oxo-quinoline 3-ester chemotype emerged as a possible source of potent bc(1) inhibitors, prompting us to expand the library of available analogs for SAR studies and subsequent lead optimization. We now report the synthesis and structural characterization of unexpected ethyl 6-methyl-7-iodo-4-(3-iodo-4-methylphenoxy)quinoline-3-carboxylate, a 4-aryloxy-quinoline 3-ester formed during attempted preparation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate (4-oxo-quinoline 3-ester). We propose that the 4-aryloxy-quinoline 3-ester derives from 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate (4-hydroxy-quinoline 3-ester), the enol form of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate. Formation of the 4-aryloxy-quinoline 3-ester confirms the impact of quinolone/hydroxyquinoline tautomerism, both on the efficiency of synthetic routes to quinolones and on pharmacologic profiles. Tautomers exhibit different cLogP values and interact differently with the enzyme active site. A structural investigation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate and 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, using matrix isolation coupled to FTIR spectroscopy and theoretical calculations, revealed that the lowest energy conformers of 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, lower in energy than their most stable 4-oxo-quinoline tautomer by about 27 kJ mol(-1), are solely present in the matrix, while the most stable 4-oxo-quinoline tautomer is solely present in the crystalline phase.Fundacao para a Ciencia e Tecnologia (FCT - Portugal) [UID/Multi/04326/2013]; QREN-COMPETE-UE; CCMAR; FCT [SFRH/BD/81821/2011, RECI/BBB-BQB/0230/2012, UI0313/QUI/2013, UID/FIS/04564/2016]; FEDER/COMPETE-UE; [PTDC/QEQ-QFI/3284/2014 - POCI-01-0145-FEDER-016617]info:eu-repo/semantics/publishedVersio