A Ciência nos Telejornais Brasileiros (O papel educativo e a compreensão pública das matérias de CT&I)

Este trabalho investiga a cobertura de Ciência, Tecnologia e Inovação (CT&I) nos telejornais brasileiros de canal aberto, no horário nobre (das 19h15 às 22h), para verificar a função educativa da mídia na abordagem de assuntos de CT&I. O corpus desta pesquisa compõe-se de um recorte dos seguintes telejornais: Jornal da Band, Jornal Nacional, Jornal da Record, Jornal da Cultura e SBT Brasil. A proposta foi avaliar, comparativamente, as matérias jornalísticas que tratam especificamente de CT&I, em relação ao formato, à linguagem e aos conteúdos de cada um dos programas estudados. Este trabalho empregou a metodologia de Análise de Discurso de linha Francesa (AD). Esta pesquisa, de natureza qualitativa, também englobou um Estudo de Recepção sobre as reportagens selecionadas. O procedimento utilizado para isso foi o de Grupos Focais. Dessa forma, buscou-se analisar o processo de Comunicação que envolve as matérias telejornalísticas de CT&I das mensagens à recepção. Este estudo verificou que CT&I é um assunto presente nos telejornais brasileiros mesmo quando ocorrem fatos imprevisíveis (de outras editorias) que influenciam significativamente a cobertura dos noticiários televisivos. Constatou também que não há, entre os telejornais selecionados, um padrão de aprofundamento e contextualização dos assuntos CT&I, mas que a abordagem varia até dentro de uma única edição. As emissoras, mesmo reconhecendo a importância de CT&I, ainda oscilam entre uma abordagem contextualizada e a simples descrição do fato principal. A linguagem empregada pelos telejornais para o tratamento de assuntos de Ciência, Tecnologia e Inovação é, predominantemente, clara e simples. No entanto, foi possível verificar algumas nuances, com o uso de termos específicos da linguagem científica sem que a matéria oferecesse qualquer explicação sobre tais conceitos. A experiência dos Grupos Focais revelou que os telespectadores não são passivos em relação aos conteúdos científicos dos programas telejornalísticos. De modo geral, o público se interessa por CT&I e sabe avaliar qualitativamente as matérias. Analisar como as matérias sobre CT&I produzem sentidos e qual a contribuição que estas podem dar à Compreensão Pública da Ciência possibilitou reflexões relevantes sobre as limitações e os potenciais da televisão e das mensagens veiculadas, assim como o interesse e a visão crítica a respeito dos assuntos de CT&I.(AU)

A Ciência nos Telejornais Brasileiros (O papel educativo e a compreensão pública das matérias de CT&I)

Este trabalho investiga a cobertura de Ciência, Tecnologia e Inovação (CT&I) nos telejornais brasileiros de canal aberto, no horário nobre (das 19h15 às 22h), para verificar a função educativa da mídia na abordagem de assuntos de CT&I. O corpus desta pesquisa compõe-se de um recorte dos seguintes telejornais: Jornal da Band, Jornal Nacional, Jornal da Record, Jornal da Cultura e SBT Brasil. A proposta foi avaliar, comparativamente, as matérias jornalísticas que tratam especificamente de CT&I, em relação ao formato, à linguagem e aos conteúdos de cada um dos programas estudados. Este trabalho empregou a metodologia de Análise de Discurso de linha Francesa (AD). Esta pesquisa, de natureza qualitativa, também englobou um Estudo de Recepção sobre as reportagens selecionadas. O procedimento utilizado para isso foi o de Grupos Focais. Dessa forma, buscou-se analisar o processo de Comunicação que envolve as matérias telejornalísticas de CT&I das mensagens à recepção. Este estudo verificou que CT&I é um assunto presente nos telejornais brasileiros mesmo quando ocorrem fatos imprevisíveis (de outras editorias) que influenciam significativamente a cobertura dos noticiários televisivos. Constatou também que não há, entre os telejornais selecionados, um padrão de aprofundamento e contextualização dos assuntos CT&I, mas que a abordagem varia até dentro de uma única edição. As emissoras, mesmo reconhecendo a importância de CT&I, ainda oscilam entre uma abordagem contextualizada e a simples descrição do fato principal. A linguagem empregada pelos telejornais para o tratamento de assuntos de Ciência, Tecnologia e Inovação é, predominantemente, clara e simples. No entanto, foi possível verificar algumas nuances, com o uso de termos específicos da linguagem científica sem que a matéria oferecesse qualquer explicação sobre tais conceitos. A experiência dos Grupos Focais revelou que os telespectadores não são passivos em relação aos conteúdos científicos dos programas telejornalísticos. De modo geral, o público se interessa por CT&I e sabe avaliar qualitativamente as matérias. Analisar como as matérias sobre CT&I produzem sentidos e qual a contribuição que estas podem dar à Compreensão Pública da Ciência possibilitou reflexões relevantes sobre as limitações e os potenciais da televisão e das mensagens veiculadas, assim como o interesse e a visão crítica a respeito dos assuntos de CT&I.(AU)

Insulin promotes rapid delivery of N-methyl-d- aspartate receptors to the cell surface by exocytosis

Insulin potentiates N-methyl-d-aspartate receptors (NMDARs) in neurons and Xenopus oocytes expressing recombinant NMDARs. The present study shows that insulin induced (i) an increase in channel number times open probability (nPo) in outside-out patches excised from Xenopus oocytes, with no change in mean open time, unitary conductance, or reversal potential, indicating an increase in n and/or Po; (ii) an increase in charge transfer during block of NMDA-elicited currents by the open channel blocker MK-801, indicating increased number of functional NMDARs in the cell membrane with no change in Po; and (iii) increased NR1 surface expression, as indicated by Western blot analysis of surface proteins. Botulinum neurotoxin A greatly reduced insulin potentiation, indicating that insertion of new receptors occurs via SNARE-dependent exocytosis. Thus, insulin potentiation occurs via delivery of new channels to the plasma membrane. NMDARs assembled from mutant subunits lacking all known sites of tyrosine and serine/threonine phosphorylation in their carboxyl-terminal tails exhibited robust insulin potentiation, suggesting that insulin potentiation does not require direct phosphorylation of NMDAR subunits. Because insulin and insulin receptors are localized to glutamatergic synapses in the hippocampus, insulin-regulated trafficking of NMDARs may play a role in synaptic transmission and plasticity, including long-term potentiation.

Pentameric subunit stoichiometry of a neuronal glutamate receptor.

Ionotropic glutamate receptors, neurotransmitter-activated ion channels that mediate excitatory synaptic transmission in the central nervous system, are oligomeric membrane proteins of unknown subunit stoichiometry. To determine the subunit stoichiometry we have used a functional assay based on the blockade of two alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate/kainate receptor subunit 1 (GluR1) mutant subunits selectively engineered to exhibit differential sensitivity to the open channel blockers phencyclidine and dizolcipine (MK-801). Coinjection into amphibian oocytes of weakly sensitive with highly sensitive subunit complementary RNAs produces functional heteromeric channels with mixed blocker sensitivities. Increasing the fraction of the highly sensitive subunit augmented the proportion of drug-sensitive receptors. Analysis of the data using a model based on random aggregation of receptor subunits allowed us to determine a pentameric stoichiometry for GluR1. This finding supports the view that a pentameric subunit organization underlies the structure of the neuronal ionotropic glutamate receptor gene family.

Zn2+ interaction with Alzheimer amyloid beta protein calcium channels.

The Alzheimer disease 40-residue amyloid beta protein (AbetaP[1-40]) forms cation-selective channels across acidic phospholipid bilayer membranes with spontaneous transitions over a wide range of conductances ranging from 40 to 4000 pS. Zn2+ has been reported to bind to AbetaP[1-40] with high affinity, and it has been implicated in the formation of amyloid plaques. We now report the functional consequences of such Zn2+ binding for the AbetaP[1-40] channel. Provided the AbetaP[1-40] channel is expressed in the low conductance (<400 pS) mode, Zn2+ blocks the open channel in a dose- dependent manner. For AbetaP[1-40] channels in the giant conductance mode (>400 pS), Zn2+ doses in the millimolar range were required to exert substantial blockade. The Zn2+ chelator o-phenanthroline reverses the blockade. We also found that Zn2+ modulates AbetaP[1-40] channel gating and conductance only from one side of the channel. These data are consistent with predictions of our recent molecular modeling studies on AbetaP[1-40] channels indicating asymmetric Zn(2+)-AbetaP[1-40] interactions at the entrance to the pore.

Cocaine: mechanism of inhibition of a muscle acetylcholine receptor studied by a laser-pulse photolysis technique.

Effects of cocaine on the muscle nicotinic acetylcholine receptor were investigated by using a chemical kinetic technique with a microsecond time resolution. This membrane-bound receptor regulates signal transmission between nerve and muscle cells, initiates muscle contraction, and is inhibited by cocaine, an abused drug. The inhibition mechanism is not well understood because of the lack of chemical kinetic techniques with the appropriate (microsecond) time resolution. Such a technique, utilizing laser-pulse photolysis, was recently developed; by using it the following results were obtained. (i) The apparent cocaine dissociation constant of the closed-channel receptor form is approximately 50 microM. High carbamoylcholine concentration and, therefore, increased concentrations of the open-channel receptor form, decrease receptor affinity for cocaine approximately 6-fold. (ii) The rate of the receptor reaction with cocaine is at least approximately 30-fold slower than the channel-opening rate, resulting in a cocaine-induced decrease in the concentration of open receptor channels without a concomitant decrease in the channel-opening or -closing rates. (iii) The channel-closing rate increases approximately 1.5-fold as the cocaine concentration is increased from 20 to 60 microM but then remains constant as the concentration is increased further. The results are consistent with a mechanism in which cocaine first binds rapidly to a regulatory site of the receptor, which can still form transmembrane channels. Subsequently, a slow step (t1/2 approximately 70 ms) leads to a receptor form that cannot form transmembrane channels, and acetylcholine receptor-mediated signal transmission is, therefore, blocked. Implications for the search for therapeutic agents that alleviate cocaine poisoning are mentioned.

Lidocaine effects on acetylcholine-elicited currents from mouse superior cervical ganglion neurons

Lidocaine is a commonly used local anaesthetic that, besides blocking voltage-dependent Na+ channels, has multiple inhibitory effects on muscle-type nicotinic acetylcholine (ACh) receptors (nAChRs). In the present study, we have investigated the effects of lidocaine on ACh-elicited currents (IAChs) from cultured mouse superior cervical ganglion (SCG) neurons, which mainly express heteromeric α3β4 nAChRs. Neurons were voltage-clamped by using the perforated-patch method and IAChs were elicited by fast application of ACh (100-300 μM), either alone or in presence of lidocaine at different concentrations. IAChs were reversibly blocked by lidocaine in a concentration-dependent way (IC50 = 41 μM; nH close to 1) and the inhibition was, at least partially, voltage-dependent, indicating an open-channel blockade. Besides, lidocaine blocked resting (closed) nAChRs, as evidenced by the increased inhibition caused by a 12 s lidocaine application just before its co-application with the agonist, and also enhanced IAChs desensitisation, at concentrations close to the IC50. These results indicate that lidocaine has diverse inhibitory actions on neuronal heteromeric nAChRs resembling those previously reported for Torpedo (muscle-type) nAChRs ( Alberola-Die et al., 2011). The similarity of lidocaine actions on different subtypes of heteromeric nAChRs differs with the specific effects of other compounds, restricted to particular subtypes of nAChRs.

Muscle-Type Nicotinic Receptor Blockade by Diethylamine, the Hydrophilic Moiety of Lidocaine

Lidocaine bears in its structure both an aromatic ring and a terminal amine, which can be protonated at physiological pH, linked by an amide group. Since lidocaine causes multiple inhibitory actions on nicotinic acetylcholine receptors (nAChRs), this work was aimed to determine the inhibitory effects of diethylamine (DEA), a small molecule resembling the hydrophilic moiety of lidocaine, on Torpedo marmorata nAChRs microtransplanted to Xenopus oocytes. Similarly to lidocaine, DEA reversibly blocked acetylcholine-elicited currents (IACh) in a dose-dependent manner (IC50 close to 70 μM), but unlike lidocaine, DEA did not affect IACh desensitization. IACh inhibition by DEA was more pronounced at negative potentials, suggesting an open-channel blockade of nAChRs, although roughly 30% inhibition persisted at positive potentials, indicating additional binding sites outside the pore. DEA block of nAChRs in the resting state (closed channel) was confirmed by the enhanced IACh inhibition when pre-applying DEA before its co-application with ACh, as compared with solely DEA and ACh co-application. Virtual docking assays provide a plausible explanation to the experimental observations in terms of the involvement of different sets of drug binding sites. So, at the nAChR transmembrane (TM) domain, DEA and lidocaine shared binding sites within the channel pore, giving support to their open-channel blockade; besides, lidocaine, but not DEA, interacted with residues at cavities among the M1, M2, M3, and M4 segments of each subunit and also at intersubunit crevices. At the extracellular (EC) domain, DEA and lidocaine binding sites were broadly distributed, which aids to explain the closed channel blockade observed. Interestingly, some DEA clusters were located at the α-γ interphase of the EC domain, in a cavity near the orthosteric binding site pocket; by contrast, lidocaine contacted with all α-subunit loops conforming the ACh binding site, both in α-γ and α-δ and interphases, likely because of its larger size. Together, these results indicate that DEA mimics some, but not all, inhibitory actions of lidocaine on nAChRs and that even this small polar molecule acts by different mechanisms on this receptor. The presented results contribute to a better understanding of the structural determinants of nAChR modulation.

SimuMap: a computational system for spatial modelling

The paper presents a computational system based upon formal principles to run spatial models for environmental processes. The simulator is named SimuMap because it is typically used to simulate spatial processes over a mapped representation of terrain. A model is formally represented in SimuMap as a set of coupled sub-models. The paper considers the situation where spatial processes operate at different time levels, but are still integrated. An example of such a situation commonly occurs in watershed hydrology where overland flow and stream channel flow have very different flow rates but are highly related as they are subject to the same terrain runoff processes. SimuMap is able to run a network of sub-models that express different time-space derivatives for water flow processes. Sub-models may be coded generically with a map algebra programming language that uses a surface data model. To address the problem of differing time levels in simulation, the paper: (i) reviews general approaches for numerical solvers, (ii) considers the constraints that need to be enforced to use more adaptive time steps in discrete time specified simulations, and (iii) scaling transfer rates in equations that use different time bases for time-space derivatives. A multistep scheme is proposed for SimuMap. This is presented along with a description of its visual programming interface, its modelling formalisms and future plans. (C) 2003 Elsevier Ltd. All rights reserved.

A Ciência nos Telejornais Brasileiros (O papel educativo e a compreensão pública das matérias de CT&I)

Este trabalho investiga a cobertura de Ciência, Tecnologia e Inovação (CT&I) nos telejornais brasileiros de canal aberto, no horário nobre (das 19h15 às 22h), para verificar a função educativa da mídia na abordagem de assuntos de CT&I. O corpus desta pesquisa compõe-se de um recorte dos seguintes telejornais: Jornal da Band, Jornal Nacional, Jornal da Record, Jornal da Cultura e SBT Brasil. A proposta foi avaliar, comparativamente, as matérias jornalísticas que tratam especificamente de CT&I, em relação ao formato, à linguagem e aos conteúdos de cada um dos programas estudados. Este trabalho empregou a metodologia de Análise de Discurso de linha Francesa (AD). Esta pesquisa, de natureza qualitativa, também englobou um Estudo de Recepção sobre as reportagens selecionadas. O procedimento utilizado para isso foi o de Grupos Focais. Dessa forma, buscou-se analisar o processo de Comunicação que envolve as matérias telejornalísticas de CT&I das mensagens à recepção. Este estudo verificou que CT&I é um assunto presente nos telejornais brasileiros mesmo quando ocorrem fatos imprevisíveis (de outras editorias) que influenciam significativamente a cobertura dos noticiários televisivos. Constatou também que não há, entre os telejornais selecionados, um padrão de aprofundamento e contextualização dos assuntos CT&I, mas que a abordagem varia até dentro de uma única edição. As emissoras, mesmo reconhecendo a importância de CT&I, ainda oscilam entre uma abordagem contextualizada e a simples descrição do fato principal. A linguagem empregada pelos telejornais para o tratamento de assuntos de Ciência, Tecnologia e Inovação é, predominantemente, clara e simples. No entanto, foi possível verificar algumas nuances, com o uso de termos específicos da linguagem científica sem que a matéria oferecesse qualquer explicação sobre tais conceitos. A experiência dos Grupos Focais revelou que os telespectadores não são passivos em relação aos conteúdos científicos dos programas telejornalísticos. De modo geral, o público se interessa por CT&I e sabe avaliar qualitativamente as matérias. Analisar como as matérias sobre CT&I produzem sentidos e qual a contribuição que estas podem dar à Compreensão Pública da Ciência possibilitou reflexões relevantes sobre as limitações e os potenciais da televisão e das mensagens veiculadas, assim como o interesse e a visão crítica a respeito dos assuntos de CT&I.(AU)

Convection induced by instabilities in the presence of a transverse seepage

The transition of laterally heated flows in a vertical layer and in the presence of a streamwise pressure gradient is examined numerically for the case of different values Prandtl number. The stability analysis of the basic flow for the pure hydrodynamic case ( Pr = 0 ) was reported in [1]. We find that in the absence of transverse pumping the previously known critical parameters are recovered [2], while as the strength of the Poiseuille flow component is increased the convective motion is delayed considerably. Following the linear stability analysis for the vertical channel flow our attention is focused on a study of the finite am- plitude secondary travelling-wave (TW) solutions that develop from the perturbations of the transverse roll type imposed on the basic flow and temperature profiles. The linear stability of the secondary TWs against three-dimensional perturbations is also examined and it is shown that the bifurcating tertiary flows are phase-locked to the secondary TWs.

Medição do transporte sólido por arrastamento através de sensores acústicos

A quantificação do material sólido transportado (transporte sólido) ao longo de um curso de água é extremamente importante nas mais variadas áreas da engenharia fluvial. O transporte sólido em rios de montanha dá-se maioritariamente por arrastamento no fundo, através de deslizamento, rolamento e saltação dos sedimentos. Ao longo dos tempos foram desenvolvidas várias fórmulas para estimar o transporte sólido por arrastamento, contudo, devido à complexidade dos processos de transporte de sedimentos, bem como a variabilidade espacial e temporal, a previsão de taxas de transporte não foi conseguida exclusivamente através de investigação teórica. Para obter um melhor conhecimento sobre os processos de transporte sólido por arrastamento em rios de montanha, torna-se necessário monitorizá-los com maior precisão possível. Com os avanços na electrónica, novos métodos tecnológicos foram desenvolvidos para resolver a problemática da quantificação do transporte sólido, em detrimento dos atuais métodos tradicionais, que se baseiam na recolha de amostras em campo, para posterior correlação. O objetivo principal da presente dissertação foi o desenvolvimento de um equipamento capaz de estimar/monitorizar continuamente o transporte sólido por arrastamento em rios de montanha, que utilizasse tecnologia de baixo custo. Este equipamento dispõe de um sensor piezolelétrico que realizará medições à vibração causada pelo embate dos sedimentos sobre uma chapa metálica. A energia do sinal resultante dos impactos reverterá em peso. A metodologia usada para a obtenção das medições foi a realização de ensaios laboratoriais, tendo sido dado especial destaque à influência da variação do caudal, bem como da forma dos sedimentos, na intensidade do sinal adquirido.

Integration of virus-like particle macromolecular bioreceptors in electrochemical biosensors

Rapid, sensitive and selective detection of chemical hazards and biological pathogens has shown growing importance in the fields of homeland security, public safety and personal health. In the past two decades, efforts have been focusing on performing point-of-care chemical and biological detections using miniaturized biosensors. These sensors convert target molecule binding events into measurable electrical signals for quantifying target molecule concentration. However, the low receptor density and the use of complex surface chemistry in receptors immobilization on transducers are common bottlenecks in the current biosensor development, adding to the cost, complexity and time. This dissertation presents the development of selective macromolecular Tobacco mosaic virus-like particle (TMV VLP) biosensing receptor, and the microsystem integration of VLPs in microfabricated electrochemical biosensors for rapid and performance-enhanced chemical and biological sensing. Two constructs of VLPs carrying different receptor peptides targeting at 2,4,6-trinitrotoluene (TNT) explosive or anti-FLAG antibody are successfully bioengineered. The VLP-based TNT electrochemical sensor utilizes unique diffusion modulation method enabled by biological binding between target TNT and receptor VLP. The method avoids the influence from any interfering species and environmental background signals, making it extremely suitable for directly quantifying the TNT level in a sample. It is also a rapid method that does not need any sensor surface functionalization process. For antibody sensing, the VLPs carrying both antibody binding peptides and cysteine residues are assembled onto the gold electrodes of an impedance microsensor. With two-phase immunoassays, the VLP-based impedance sensor is able to quantify antibody concentrations down to 9.1 ng/mL. A capillary microfluidics and impedance sensor integrated microsystem is developed to further accelerate the process of VLP assembly on sensors and improve the sensitivity. Open channel capillary micropumps and stop-valves facilitate localized and evaporation-assisted VLP assembly on sensor electrodes within 6 minutes. The VLP-functionalized impedance sensor is capable of label-free sensing of antibodies with the detection limit of 8.8 ng/mL within 5 minutes after sensor functionalization, demonstrating great potential of VLP-based sensors for rapid and on-demand chemical and biological sensing.

Subfilter-scale Stress Modelling for Large Eddy Simulations

A subfilter-scale (SFS) stress model is developed for large-eddy simulations (LES) and is tested on various benchmark problems in both wall-resolved and wall-modelled LES. The basic ingredients of the proposed model are the model length-scale, and the model parameter. The model length-scale is defined as a fraction of the integral scale of the flow, decoupled from the grid. The portion of the resolved scales (LES resolution) appears as a user-defined model parameter, an advantage that the user decides the LES resolution. The model parameter is determined based on a measure of LES resolution, the SFS activity. The user decides a value for the SFS activity (based on the affordable computational budget and expected accuracy), and the model parameter is calculated dynamically. Depending on how the SFS activity is enforced, two SFS models are proposed. In one approach the user assigns the global (volume averaged) contribution of SFS to the transport (global model), while in the second model (local model), SFS activity is decided locally (locally averaged). The models are tested on isotropic turbulence, channel flow, backward-facing step and separating boundary layer. In wall-resolved LES, both global and local models perform quite accurately. Due to their near-wall behaviour, they result in accurate prediction of the flow on coarse grids. The backward-facing step also highlights the advantage of decoupling the model length-scale from the mesh. Despite the sharply refined grid near the step, the proposed SFS models yield a smooth, while physically consistent filter-width distribution, which minimizes errors when grid discontinuity is present. Finally the model application is extended to wall-modelled LES and is tested on channel flow and separating boundary layer. Given the coarse resolution used in wall-modelled LES, near the wall most of the eddies become SFS and SFS activity is required to be locally increased. The results are in very good agreement with the data for the channel. Errors in the prediction of separation and reattachment are observed in the separated flow, that are somewhat improved with some modifications to the wall-layer model.

Modelling and PI Control of an Irrigation Canal

The main goal of this paper is to expose and validate a methodology to design efficient automatic controllers for irrigation canals, based on the Saint-Venant model. This model-based methodology enables to design controllers at the design stage (when the canal is not already built). The methodology is applied on an experimental canal located in Portugal. First the full nonlinear PDE model is calibrated, using a single steady-state experiment. The model is then linearized around a functioning point, in order to design linear PI controllers. Two classical control strategies are tested (local upstream control and distant downstream control) and compared on the canal. The experimental results show the effectiveness of the model.