Proteinase-activated receptor 2 (PAR2)-activating peptides: Identification of a receptor distinct from PAR2 that regulates intestinal transport

The effects of PAR2-activating PAR2-activating peptides, SLIGRL (SL)-NH2, and trans-cinnamoyl-LIGRLO (tc)-NH2 were compared with the action of trypsin, thrombin, and the PAR1 selective-activating peptide: Ala-parafluoroPhe-Arg-cyclohexylAla-Citrulline-Tyr (Cit)-NH2 for stimulating intestinal ion transport. These agonists were added to the serosa of stripped rat jejunum segments mounted in Ussing chambers, and short circuit current (Isc) was used to monitor active ion transport. The relative potencies of these agonists also were evaluated in two bioassays specific for the activation of rat PAR2: a cloned rat PAR2 cell calcium-signaling assay (PAR2-KNRK cells) and an aorta ring relaxation (AR) assay. In the Isc assay, all agonists, except thrombin, induced an Isc increase. The SL-NH2-induced Isc changes were blocked by indomethacin but not by tetrodotoxin. The relative potencies of the agonists in the Isc assay (trypsin≫SL-NH2>tc-NH2>Cit-NH2) were strikingly different from their relative potencies in the cloned PAR2-KNRK cell calcium assay (trypsin≫>tc-NH2 ≅ SL-NH2≫>Cit-NH2) and in the AR assay (trypsin≫>tc-NH2 ≅ SL-NH2). Furthermore, all agonists were maximally active in the PAR2-KNRK cell and AR assays at concentrations that were one (PAR2 -activating peptides) or two (trypsin) orders of magnitude lower than those required to activate intestinal transport. Based on the distinct potency profile for these agonists and the considerable differences in the concentration ranges required to induce an Isc effect in the intestinal assay compared with the PAR2-KNRK and AR assays, we conclude that a proteinase-activated receptor, pharmacologically distinct from PAR2 and PAR1, is present in rat jejunum and regulates intestinal transport via a prostanoid-mediated mechanism.

On the role of the K-proton transfer pathway in cytochrome c oxidase

Cytochrome c oxidase is a membrane-bound enzyme that catalyzes the four-electron reduction of oxygen to water. This highly exergonic reaction drives proton pumping across the membrane. One of the key questions associated with the function of cytochrome c oxidase is how the transfer of electrons and protons is coupled and how proton transfer is controlled by the enzyme. In this study we focus on the function of one of the proton transfer pathways of the R. sphaeroides enzyme, the so-called K-proton transfer pathway (containing a highly conserved Lys(I-362) residue), leading from the protein surface to the catalytic site. We have investigated the kinetics of the reaction of the reduced enzyme with oxygen in mutants of the enzyme in which a residue [Ser(I-299)] near the entry point of the pathway was modified with the use of site-directed mutagenesis. The results show that during the initial steps of oxygen reduction, electron transfer to the catalytic site (to form the “peroxy” state, Pr) requires charge compensation through the proton pathway, but no proton uptake from the bulk solution. The charge compensation is proposed to involve a movement of the K(I-362) side chain toward the binuclear center. Thus, in contrast to what has been assumed previously, the results indicate that the K-pathway is used during oxygen reduction and that K(I-362) is charged at pH ≈ 7.5. The movement of the Lys is proposed to regulate proton transfer by “shutting off” the protonic connectivity through the K-pathway after initiation of the O2 reduction chemistry. This “shutoff” prevents a short-circuit of the proton-pumping machinery of the enzyme during the subsequent reaction steps.

Atenuação de vibrações em pás de helicópteros utilizando circuito piezelétrico semi-passivo

O uso de materiais inteligentes em problemas de controle de vibração tem sido investigado em diversas pesquisas ao longo dos últimos anos. Apesar de que diferentes materiais inteligentes estão disponíveis, o piezelétrico tem recebido grande atenção devido à facilidade de uso como sensores, atuadores, ou ambos simultaneamente. As principais técnicas de controle usando materiais piezoelétricos são os ativos e passivos. Circuitos piezelétricos passivos são ajustados para uma frequência específica e, portanto, a largura de banda efetiva é pequena. Embora os sistemas ativos possam apresentar um bom desempenho no controle de vibração, a quantidade de energia externa e hardware adicionado são questões importantes. As técnicas SSD (Synchronized Switch Damping) foram desenvolvidas como uma alternativa aos controladores passivos e controladores ativos de vibração. Elas podem ser técnicas semi-ativas ou semi-passivas que introduzem um tratamento não linear na tensão elétrica proveniente do material piezelétrico e induz um aumento na conversão de energia mecânica para energia elétrica e, consequentemente, um aumento no efeito de amortecimento. Neste trabalho, o controle piezoelétrico semi-passivo de uma pá piezelétrica engastada é apresentado e comparado com outros controladores. O modelo não linear electromecânico de uma pá com piezocerâmicas incorporados é determinado com base no método variacional-assintótico (VAM). O sistema rotativo acoplado não linear é resolvido no domínio do tempo, utilizando um método de integração alfa-generalizado afim de garantir a estabilidade numérica. As simulações são realizadas para uma vasta gama de velocidades de rotação. Em primeiro lugar, um conjunto de resistências (variando desde a condição de curto-circuito para a condição de circuito aberto) é considerada. O efeito da resistência ótima (que resulta em máximo amortecimento) sobre o comportamento do sistema é investigado para o aumento da velocidade de rotação. Mais tarde, a técnica SSDS é utilizada para amortecer as oscilações da pá com o aumento da velocidade de rotação. Os resultados mostram que a técnica SSDS pode ser um método útil para o controle de vibrações de vigas rotativas não lineares, tais como pás de helicóptero.

Uma abordagem paramétrica do impacto da geração distribuída sobre as correntes de curto-circuito e na proteção de redes de distribuição.

Esta dissertação tem por propósito analisar os impactos da geração distribuída sobre as correntes de curto-circuito e sobre a proteção das redes de média tensão das concessionárias de distribuição de energia elétrica usando uma abordagem paramétrica. A principal motivação deste trabalho são os recentes incentivos regulatórios que estão fomentando a geração distribuída no Brasil. Contudo, as redes de distribuição convencionais foram projetadas para serem passivas e a introdução da geração poderá causar problemas de ordem técnica que ainda precisam ser resolvidos. Tais problemas foram pesquisados e aqueles relacionados com os impactos sobre as correntes de curto-circuito foram enfatizados. As normas técnicas das concessionárias também foram investigadas porque seus requisitos, como a ligação dos transformadores de acoplamento, influem nas correntes de curto-circuito. Para se calcular as correntes de curto-circuito, desenvolveu-se uma planilha eletrônica cujos resultados foram validados com programas comerciais de análise de redes elétricas. Esta ferramenta foi utilizada para demonstrar, através de exemplos, o impacto causado pela geração distribuída sobre as correntes de curto-circuito e, posteriormente, para realizar as análises paramétricas nas quais a influência de cada variável foi avaliada. A aplicação do método paramétrico permitiu o estudo de possíveis limites para a potência de um gerador distribuído em função dos impactos admissíveis, de seu ponto de conexão, de seus parâmetros elétricos e dos parâmetros elétricos da rede.

Uncertainty during organizational change: Types, consequences, and management strategies

This research tested a model that classifies change uncertainty into three interrelated types: strategic, structural, and job-related. We predicted that control would mediate the effects of job-related uncertainty upon psychological strain, and that management communication and participation in decision-making (PDM) would reduce uncertainty and increase feelings of control. The model was tested in a public sector organization and the results supported it. Control was found to mediate the effects of job-related uncertainty upon psychological strain. Management communication was negatively related to strategic uncertainty, whereas PDM was negatively related to structural and job-related uncertainty, suggesting different mechanisms to deal with the types of uncertainty during change. Finally, PDM was positively associated with feelings of control and negatively associated with psychological strain. These results suggest that PDM can short-circuit the damaging effects of uncertainty by allowing employees to have a say in change related organizational affairs, thereby instilling a sense of control over their circumstances.

Protease-activated receptor-2 peptides activate neurokinin-1 receptors in the mouse isolated trachea

Protective roles for protease-activated receptor-2 (PAR2) in the airways including activation of epithelial chloride (Cl-) secretion are based on the use of presumably PAR(2)-selective peptide agonists. To determine whether PAR(2) peptide-activated Cl- secretion from mouse tracheal epithelium is dependent on PAR(2), changes in ion conductance across the epithelium [short-circuit current (I-SC)] to PAR(2) peptides were measured in Ussing chambers under voltage clamp. In addition, epithelium and endothelium-dependent relaxations to these peptides were measured in two established PAR(2) bioassays, isolated ring segments of mouse trachea and rat thoracic aorta, respectively. Apical application of the PAR(2) peptide SLIGRL caused increases in I-SC, which were inhibited by three structurally different neurokinin receptor-1 (NK1R) antagonists and inhibitors of Cl- channels but not by capsaicin, the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP(8-37), or the nonselective cyclooxygenase inhibitor indomethacin. Only high concentrations of trypsin caused an increase in I-SC but did not affect the responses to SLIGRL. Relaxations to SLIGRL in the trachea and aorta were unaffected by the NK1R antagonist nolpitantium (SR 140333) but were abolished by trypsin desensitization. The rank order of potency for a range of peptides in the trachea I-SC assay was 2-furoyl-LIGRL > SLCGRL > SLIGRL > SLIGRT > LSIGRL compared with 2-furoyl-LIGRL > SLIGRL > SLIGRT > SLCGRL (LSIGRL inactive) in the aorta relaxation assay. In the mouse trachea, PAR(2) peptides activate both epithelial NK1R coupled to Cl- secretion and PAR(2) coupled to prostaglandin E-2-mediated smooth muscle relaxation. Such a potential lack of specificity of these commonly used peptides needs to be considered when roles for PAR(2) in airway function in health and disease are determined.

Studies of the shellside performance of shell-and-tube heat exchangers

Accurate prediction of shellside pressure drop in a baffled shell-and-tube heat exchanger is very difficult because of the complicated shellside geometry. Ideally, all the shellside fluid should be alternately deflected across the tube bundle as it traverses from inlet to outlet. In practice, up to 60% of the shellside fluid may bypass the tube bundle or leak through the baffles. This short-circuiting of the main flow reduces the efficiency of the exchanger. Of the various shellside methods, it is shown that only the multi-stream methods, which attempt to obtain the shellside flow distribution, predict the pressure drop with any degree of accuracy, the various predictions ranging from -30% to +70%, generally overpredicting. It is shown that the inaccuracies are mainly due to the manner in which baffle leakage is modelled. The present multi-stream methods do not allow for interactions of the various flowstreams, and yet it is shown that three main effects are identified, a) there is a strong interaction between the main cross flow and the baffle leakage streams, enhancing the crossflow pressure drop, b) there is a further short-circuit not considered previously i.e. leakage in the window, and c) the crossflow does not penetrate as far, on average, as previously supposed. Models are developed for each of these three effects, along with a new windowflow pressure drop model, and it is shown that the effect of baffle leakage in the window is the most significant. These models developed to allow for various interactions, lead to an improved multi-stream method, named the "STREAM-INTERACTION" method. The overall method is shown to be consistently more accurate than previous methods, with virtually all the available shellside data being predicted to within ±30% and over 60% being within ±20%. The method is, thus, strongly recommended for use as a design method.

Adrenoceptor influences on fluid and electrolyte transport in the rat intestine

An investigation of rat jejunal and distal colonic electrolyte transport in-vitro was undertaken using an Ussing chamber prepartion. Selective α2-adrenoceptor stimualtion in the jejunum was found to depress theo-phylline elevated anion secretion, as evidenced by decreases in short- circuit current (SCC). or α1 -Adrenoceptor stimulation, after α2 -adrenoceptor antagonism in the jejunum, evoked transient increases in basal anion secretion, as reflected by transient increases in basal SCC. The use of the neurotoxin tetrodotoxin indicated that this was a direct epithelial secretory effect. 5-hydroxytryptamine (5-HT) on the jejunum elicited transient increases in basal anion secretion, as demonstrated by transient increases in basal SCC. The use of tetrodotoxin, reserpine and α1 -adrenoceptor antagonists, indicated that a major component of this epithelial secretory effect by 5-HT, was associated with activation of intramural nervous pathways of the sympathetic nervous system, ultimately stimulating α1-adrenoceptors. This might represent an important secretory mechanism by 5-HT in the jejunum. β2-Adrenoceptor stimulation in the distal colon was found to decrease basal SCC, as evidenced by the metoprolol resistant effect of the selective β2- adrenoceptor agonist salbutamol, and lack of effect of the selective β1-adrenoceptor agonist prenalterol. An investigation of rat distal colonic fluid and electrolyte transport in-vivo was undertaken using an colonic loop technique. Although a basal colonic absorption of Na+ and Cl-, and a secretion of K+ were observed, these processes were not under tonic α-adrenergic regulation, as evidenced by the lack of effect of selective α-adrenoceptor antagonism. The secretory effects of prostaglandin-E2 were inhibited by α-adrenoceptor activation, whereas such stimulation did not evoke pro-absorptive responses upon basal transport, unlike noradrenaline.

Practical photovoltaic simulator with a cross tackling control strategy based on the first-hand duty cycle processing

This paper proposes a methodological scheme for the photovoltaic (PV) simulator design. With the advantages of a digital controller system, linear interpolation is proposed for precise fitting with higher computational efficiency. A novel control strategy that directly tackles two different duty cycles is proposed and implemented to achieve a full-range operation including short circuit (SC) and open circuit (OC) conditions. Systematic design procedures for both hardware and algorithm are explained, and a prototype is built. Experimental results confirm an accurate steady state performance under different load conditions, including SC and OC. This low power apparatus can be adopted for PV education and research with a limited budget.

Efficiency improvement of non-uniformly-aged PV arrays

The utilization of solar energy by photovoltaic (PV) systems have received much research and development (R&D) attention across the globe. In the past decades, a large number of PV array have been installed. Since the installed PV arrays often operate in harsh environments, non-uniform aging can occur and impact adversely on the performance of PV systems, especially in the middle and late periods of their service life. Due to the high cost of replacing aged PV modules by new modules, it is appealing to improve energy efficiency of aged PV systems. For this purpose, this paper presents a PV module reconfiguration strategy to achieve the maximum power generation from non-uniformly aged PV arrays without significant investment. The proposed reconfiguration strategy is based on the cell-unit structure of PV modules, the operating voltage limit of gird-connected converter, and the resulted bucket-effect of the maximum short circuit current. The objectives are to analyze all the potential reorganization options of the PV modules, find the maximum power point and express it in a proposition. This proposition is further developed into a novel implementable algorithm to calculate the maximum power generation and the corresponding reconfiguration of the PV modules. The immediate benefits from this reconfiguration are the increased total power output and maximum power point voltage information for global maximum power point tracking (MPPT). A PV array simulation model is used to illustrate the proposed method under three different cases. Furthermore, an experimental rig is built to verify the effectiveness of the proposed method. The proposed method will open an effective approach for condition-based maintenance of emerging aging PV arrays.

Central-tapped node linked modular fault-tolerance topology for SRM applications

Electric vehicles (EVs) and hybrid electric vehicles (HEVs) can reduce greenhouse gas emissions while switched reluctance motor (SRM) is one of the promising motor for such applications. This paper presents a novel SRM fault-diagnosis and fault-tolerance operation solution. Based on the traditional asymmetric half-bridge topology for the SRM driving, the central tapped winding of the SRM in modular half-bridge configuration are introduced to provide fault-diagnosis and fault-tolerance functions, which are set idle in normal conditions. The fault diagnosis can be achieved by detecting the characteristic of the excitation and demagnetization currents. An SRM fault-tolerance operation strategy is also realized by the proposed topology, which compensates for the missing phase torque under the open-circuit fault, and reduces the unbalanced phase current under the short-circuit fault due to the uncontrolled faulty phase. Furthermore, the current sensor placement strategy is also discussed to give two placement methods for low cost or modular structure. Simulation results in MATLAB/Simulink and experiments on a 750-W SRM validate the effectiveness of the proposed strategy, which may have significant implications and improve the reliability of EVs/HEVs.

Automatons, Robots, and Capitalism in a Very Wrong Twenty-First Century: A Review Essay on Neill Blomkamp’s Chappie

Contrary to prevailing opinions, Neill Blomkamp’s recent feature film Chappie is not a movie about robots or artificial intelligence. It is not Robocop. It is not Short Circuit. It is also not District 9 or Elysium. Chappie is a movie about humanity’s dialectically creative and destructive potential. It is a movie about how it is that humans come to behave how they do through their social and material circumstances, as well as the barbaric results when the two are mixed under the thoroughly undemocratic conditions of neoliberal capitalism.

Avaliação da soldagem GMAW mecanizada e automatizada para união de dutos utilizando fontes convencional e com controle de curto- circuito

Welding is one of the most employed process for joining steel pipes. Although, manual welding is still the most used one, mechanized version and even automatized one have increased its demand. Thus, this work deals with girth welding of API 5L X65 pipes with 8” of nominal diameter and 8.0 mm thickness, beveled with V-30º narrow gap. Torch is moved by a bug carrier (mechanized welding) and further the parameters are controlled as a function of angular position (automatized welding). Welding parameters are presented for filling the joint with two-passes (root and filling/capping passes). Parameters for the root pass were extracted from previous author´s work with weldments carried out in plates, but validated in this work for pipe welding. GMAW processes were assessed with short-circuit metal transfer in both conventional and derivative modes using different technologies (RMD, STT and CMT). After the parameter determination, mechanical testing was performed for welding qualification (uniaxial tension, face and root bending, nick break, Charpy V-notch impact, microhardness and macrograph). The initially obtained results for RMD and CMT were acceptable for all testing and, in a second moment, also for the STT. However, weld beads carried out by using the conventional process failed and revealed the existence of lack of fusion, which required further parametrization. Thus, a Parameter-Variation System for Girth Welding (SVP) was designed and built to allow varying the welding parameters as a function of angular position by using an inclinometer. The parameters were set for each of the three angular positions (flat, vertical downhill and overhead). By using such equipment and approach, the conventional process with parameter variation allowed reducing the welding time for joint accomplishment of the order of 38% for the root pass and 30% for the filling/capping pass.

TILTED COLUMNAR THIN FILM COATINGS WITH ANISOTROPIC LIGHT SCATTERING PROPERTIES FOR SOLAR ENERGY APPLICATIONS

The main goal of this thesis is to show the versatility of glancing angle deposition (GLAD) thin films in applications. This research is first focused on studying the effect of select deposition variables in GLAD thin films and secondly, to demonstrate the flexibility of GLAD films to be incorporated in two different applications: (1) as a reflective coating in low-level concentration photovoltaic systems, and (2) as an anode structure in dye-sensitized solar cells (DSSC). A particular type of microstructure composed of tilted micro-columns of titanium is fabricated by GLAD. The microstructures form elongated and fan-like tilted micro-columns that demonstrate anisotropic scattering. The thin films texture changes from fiber texture to tilted fiber texture by increasing the vapor incidence angle. At very large deposition angles, biaxial texture forms. The morphology of the thin films deposited under extreme shadowing condition and at high temperature (below recrystallization zone) shows a porous and inclined micro-columnar morphology, resulting from the dominance of shadowing over adatom surface diffusion. The anisotropic scattering behavior of the tilted Ti thin film coatings is quantified by bidirectional reflectance distribution function (BRDF) measurements and is found to be consistent with reflectance from the microstructure acting as an array of inclined micro-mirrors that redirect the incident light in a non-specular reflection. A silver-coating of the surface of the tilted-Ti micro-columns is performed to enhance the total reflectance of the Ti-thin films while keeping the anisotropic scattering behavior. By using such coating is as a booster reflector in a laboratory-scale low-level concentration photovoltaic system, the short-circuit current of the reference silicon solar cell by 25%. Finally, based on the scattering properties of the tilted microcolumnar microstructure, its scattering effect is studied as a part of titanium dioxide microstructure for the anode in DSSCs. GLAD-fabricated TiO2 microstructures for the anode in a DSSC, consisting of vertical micro-columns, and combined vertical topped with tilted micro-columns are compared. The solar cell with the two-part microstructure shows the highest monochromatic incident photon to current efficiency with 20% improvement compared to the vertical microstructure, and the efficiency of the cell increases from 1.5% to 2% due to employing the scattering layer.

Modélisation des machines par circuits couplés pour l’observation des courants de barres au rotor

Ce travail présente une modélisation rapide d’ordre élévé capable de modéliser une configuration rotorique en cage complète ou en grille, de reproduire les courants de barre et tenir compte des harmoniques d’espace. Le modèle utilise une approche combinée d’éléments finis avec les circuits-couplés. En effet, le calcul des inductances est réalisé avec les éléments finis, ce qui confère une précision avancée au modèle. Cette méthode offre un gain important en temps de calcul sur les éléments finis pour des simulations transitoires. Deux outils de simulation sont développés, un dans le domaine du temps pour des résolutions dynamiques et un autre dans le domaine des phaseurs dont une application sur des tests de réponse en fréquence à l’arrêt (SSFR) est également présentée. La méthode de construction du modèle est décrite en détail de même que la procédure de modélisation de la cage du rotor. Le modèle est validé par l’étude de machines synchrones: une machine de laboratoire de 5.4 KVA et un grand alternateur de 109 MVA dont les mesures expérimentales sont comparées aux résultats de simulation du modèle pour des essais tels que des tests à vide, des courts-circuits triphasés, biphasés et un test en charge.