A PLL-based multirate structure for time-varying power systems harmonic/interharmonic estimation

This paper describes a phase-locked-loop (PLL)-based power systems harmonic estimation algorithm, which uses an analysis filter bank and multirate processing. The filter bank is composed of bandpass filters. The initial center frequency of each filter is purposely chosen to be equal to harmonic frequencies. However, an adaptation strategy makes it possible to track time-varying frequencies as well as interharmonic components. A downsampler device follows the filtering stage, reducing the computational burden, especially because undersampling operations are performed. Finally, the last stage is composed of a PLL estimator which provides estimates for amplitude, phase, and frequency of the input signal. The proposed method improves the accuracy, computational effort, and convergence time of the previous harmonic estimator based on cascade PLL configuration

Controlo da altura de plantas ornamentais: alternativas sustentáveis aos reguladores de crescimento

V Jornadas Ibéricas de Horticultura Ornamental, Faro, 13-15 Outubro, 2011A necessidade de encontrar estratégias sustentáveis eficazes no controlo da altura da planta é actualmente um grande desafio que se coloca à horticultura ornamental protegida. Este estudo teve como objectivo: (1) analisar a informação disponível acerca dos factores que afectam a altura das plantas; (2) compreender os mecanismos fisiológicos envolvidos no processo de alongamento do caule; (3) definir alternativas sustentáveis para produzir plantas compactas, reduzindo ao mínimo a aplicação de ‘reguladores químicos de crescimento’. Concluiu-se que manter uma temperatura nocturna superior à temperatura diurna (DIF negativa ou tratamento DROP) ou a alteração do espectro luminoso (elevado rácio vermelho/vermelholongínquo) apresentam um forte potencial como métodos não químicos no controlo da altura de várias espécies de plantas ornamentais. O aumento do rácio vermelho/vermelho-longínquo, poderá ser efectuado de diferentes modos incluindo a utilização de filmes fotosselectivos e/ou recorrendo a um conjunto de medidas facilmente aplicáveis tais como: (i) evitar densidades de plantação muito elevadas; (ii) utilização de luz suplementar com elevado rácio vermelho/vermelho-longínquo (ex. lâmpadas de assimilação em substituição de lâmpadas incandescentes); (iii) evitar a exposição das plantas à radiação do crepúsculo (devido à diminuição natural do rácio vermelho/vermelho-longínquo). O stress mecânico é também uma medida eficaz para a manutenção de plantas compactas em determinadas espécies. Paralelamente, o recurso ao Melhoramento de plantas no sentido de seleccionar cultivares ananicantes poderá ser bastante promissor. Porém, na maioria dos casos, não será uma medida única que permitirá a obtenção de plantas compactas, mas a combinação de várias estratégiasinfo:eu-repo/semantics/publishedVersio

Insulin therapy modulates mitochondrial dynamics and biogenesis, autophagy and tau protein phosphorylation in the brain of type 1 diabetic rats

AbstractThe main purpose of this study was to examine whether streptozotocin (STZ)-induced type 1 diabetes (T1D) and insulin (INS) treatment affect mitochondrial function, fission/fusion and biogenesis, autophagy and tau protein phosphorylation in cerebral cortex from diabetic rats treated or not with INS. No significant alterations were observed in mitochondrial function as well as pyruvate levels, despite the significant increase in glucose levels observed in INS-treated diabetic rats. A significant increase in DRP1 protein phosphorylated at Ser616 residue was observed in the brain cortex of STZ rats. Also an increase in NRF2 protein levels and in the number of copies of mtDNA were observed in STZ diabetic rats, these alterations being normalized by INS. A slight decrease in LC3-II levels was observed in INS-treated rats when compared to STZ diabetic animals. An increase in tau protein phosphorylation at Ser396 residue was observed in STZ diabetic rats while INS treatment partially reversed that effect. Accordingly, a modest reduction in the activation of GSK3β and a significant increase in the activity of phosphatase 2A were found in INS-treated rats when compared to STZ diabetic animals. No significant alterations were observed in caspases 9 and 3 activity and synaptophysin and PSD95 levels. Altogether our results show that mitochondrial alterations induced by T1D seem to involve compensation mechanisms since no significant changes in mitochondrial function and synaptic integrity were observed in diabetic animals. In addition, INS treatment is able to normalize the alterations induced by T1D supporting the importance of INS signaling in the brain

Motores de propulsão em veículos elétricos: tipos, características e perspetivas de evolução

Os sistemas de propulsão baseados em motores síncronos de ímanes permanentes (MSIP) e motores de indução (MI) têm sido as principais opções para veículos híbridos (VH) e elétricos (VE). As limitações das reservas e os elevados custos das terras-raras (constituinte essencial dos ímanes permanentes (IP)) têm motivado o interesse por motores sem IP ou com menores quantidades de terras-raras. Várias configurações têm vindo a ser desenvolvidas e/ou aperfeiçoadas, com vista a ultrapassar as limitações dos MI, sendo que a otimização do seu projeto também tem sido alvo de atenção. De modo não exaustivo, o objetivo deste artigo é incidir sobre os tipos de motores atualmente aplicados na propulsão elétrica. No final, apresenta-se uma breve referência às principais tecnologias emergentes.info:eu-repo/semantics/publishedVersio

Metabolic dynamics of human Sertoli cells are differentially modulated by physiological and pharmacological concentrations of GLP-1

Obesity incidence has pandemic proportions and is expected to increase even further. Glucagon-like peptide-1 (GLP-1) based therapies are well-established pharmacological resources for obesity treatment. GLP-1 regulates energy and glucose homeostasis, which are also crucial for spermatogenesis. Herein, we studied the GLP-1 effects in human Sertoli cells (hSCs) metabolism and mitochondrial function. hSCs were cultured in absence or exposed to increasing doses of GLP-1 mimicking physiological post-prandial (0.01 nM) levels or equivalent to pharmacological levels (1 and 100 nM) used for obesity treatment. We identified GLP-1 receptor in hSCs. Consumption/production of extracellular metabolites were assessed, as well as protein levels or activities of glycolysis-related enzymes and transporters. Mitochondrial membrane potential and oxidative damage were evaluated. Glucose consumption decreased, while lactate production increased in hSCs exposed to 0.01 and 1 nM GLP-1. Though lactate dehydrogenase (LDH) protein decreased after exposure to 100 nM GLP-1 its activity increased in hSCs exposed to the same concentration of GLP-1. Mitochondrial membrane potential decreased in hSCs exposed to 100 nM of GLP-1, while formation of carbonyl groups was decreased in those cells. Those effects were followed by an increase in p-mammalian target of rapamycin (mTOR) Ser(2448). Overall, the lowest concentrations of GLP-1 increased the efficiency of glucose conversion to lactate, while GLP-1 concentration of 100 nM induces mTOR phosphorylation, decreases mitochondrial membrane potential and oxidative damage. GLP-1 regulates testicular energy homeostasis and pharmacological use of GLP-1 analogues could be valuable to counteract the negative impact of obesity in male reproductive function.info:eu-repo/semantics/publishedVersio

Soil organisms in organic and conventional cropping systems.

Apesar do crescente interesse pela agricultura orgânica, são poucas as informações de pesquisa disponíveis sobre o assunto. Assim, num Argissolo Vermelho-Amarelo distrófico foram comparados os efeitos de sistemas de cultivo orgânico e convencional, para as culturas do tomate (Lycopersicum esculentum) e do milho (Zea mays), sobre a comunidade de organismos do solo e suas atividades. As populações de fungos,bactérias e actinomicetos, determinadas pela contagem de colônias em meio de cultura, foram semelhantes para os dois sistemas de produção. A atividade microbiana, avaliada pela evolução de CO2, manteve-se superior no sistema orgânico, sendo que em determinadas avaliações foi o dobro da evolução verificada no sistema convencional. O número de espécimes de minhoca foi praticamente dez vezes maior no sistema orgânico. Não foi observada diferença na taxa de decomposição de matéria orgânica entre os dois sistemas. De modo geral, o número de indivíduos de microartrópodos foi superior no sistema orgânico do que no sistema convencional, refletindo no maior índice de diversidade de Shannon. As maiores populações de insetos foram as da ordem Collembola, enquanto para os ácaros a maior população foi a da superfamília Oribatuloidea. Indivíduos dos grupos Aranae, Chilopoda, Dyplopoda, Pauropoda, Protura e Symphyla foram ocasionalmente coletados e de forma similar entre os sistemas

Instanton Effects in QCD at High Baryon Density

We study instanton effects in QCD at very high baryon density. In this regime instantons are suppressed by a large power of $(\Lambda_{QCD}/\mu)$, where $\Lambda_{QCD}$ is the QCD scale parameter and $\mu$ is the baryon chemical potential. Instantons are nevertheless important because they contribute to several physical observables that vanish to all orders in perturbative QCD. We study, in particular, the chiral condensate and its contribution $m_{GB}^2\sim m$ to the masses of Goldstone bosons in the CFL phase of QCD with $N_f=3$ flavors. We find that at densities $\rho\sim (5-10) \rho_0$, where $\rho_0$ is the density of nuclear matter, the result is dominated by large instantons and subject to considerable uncertainties. We suggest that these uncertainties can be addressed using lattice calculations of the instanton density and the pseudoscalar diquark mass in QCD with two colors. We study the topological susceptibility and Witten-Veneziano type mass relations in both $N_c=2$ and $N_c=3$ QCD.Comment: 27 pages, 8 figures, minor revision

Energy and Flux Measurements of Ultra-High Energy Cosmic Rays Observed During the First ANITA Flight

The first flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment recorded 16 radio signals that were emitted by cosmic-ray induced air showers. For 14 of these events, this radiation was reflected from the ice. The dominant contribution to the radiation from the deflection of positrons and electrons in the geomagnetic field, which is beamed in the direction of motion of the air shower. This radiation is reflected from the ice and subsequently detected by the ANITA experiment at a flight altitude of 36km. In this paper, we estimate the energy of the 14 individual events and find that the mean energy of the cosmic-ray sample is 2.9 EeV. By simulating the ANITA flight, we calculate its exposure for ultra-high energy cosmic rays. We estimate for the first time the cosmic-ray flux derived only from radio observations. In addition, we find that the Monte Carlo simulation of the ANITA data set is in agreement with the total number of observed events and with the properties of those events.Comment: Added more explanation of the experimental setup and textual improvement