4,558 research outputs found

    Induction Machine Broken Bar and Stator Short-Circuit Fault Diagnostics Based on Three Phase Stator Current Envelopes

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    A new method for the fault diagnosis of a broken rotor bar and interturn short circuits in induction machines (IMs) is presented. The method is based on the analysis of the three-phase stator current envelopes of IMs using reconstructed phase space transforms. The signatures of each type of fault are created from the three-phase current envelope of each fault. The resulting fault signatures for the new so-called ldquounseen signalsrdquo are classified using Gaussian mixture models and a Bayesian maximum likelihood classifier. The presented method yields a high degree of accuracy in fault identification as evidenced by the given experimental results, which validate this method

    A time of flight method to measure the speed of sound using a stereo sound card

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    We present an inexpensive apparatus for measuring the speed of sound, with a time of flight method, using a computer with a stereo sound board. Students measure the speed of sound by timing the delay between the arrivals of a pulse to two microphones placed at different distances from the source. It can serve as a very effective demonstration, providing a quick measurement of the speed of sound in air; we have used it with great success in Open Days in our Department. It can also be used for a full fledged laboratory determination of the speed of sound in air.Comment: Accepted for publication in The Physics Teache

    Genetic analysis of members of the species Oropouche virus and identification of a novel M segment sequence

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    Oropouche virus (OROV) is a public health threat in South America, and in particular Northern Brazil, causing frequent outbreaks of febrile illness. Using a combination of deep sequencing and Sanger sequencing approaches we have determined complete genome sequences of eight clinical isolates that were obtained from patient sera during an Oropouche fever outbreak in Amapa state, northern Brazil in 2009. We also report complete genome sequences of two OROV reassortants isolated from two marmosets in Minas Gerais state, southeast Brazil in 2012 that contain a novel M genome segment. Interestingly, all ten isolates posses a 947 nucleotide long S segment that lacks 11 residues in the S segment 3' UTR compared to the recently redetermined Brazilian prototype OROV strain BeAn19991. OROV maybe circulating more widely in Brazil and in the non-human primate population than previously appreciated and the identification of yet another reassortant highlights the importance of bunyavirus surveillance in South America

    Keeping the eIF2 alpha kinase Gcn2 in check

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    The protein kinase Gcn2 is present in virtually all eukaryotes and is of increasing interest due to its involvement in a large array of crucial biological processes. Some of these are universally conserved from yeast to humans, such as coping with nutrient starvation and oxidative stress. in mammals, Gcn2 is important for e.g. long-term memory formation, feeding behaviour and immune system regulation. Gcn2 has been also implicated in diseases such as cancer and Alzheimer's disease. Studies on Gcn2 have been conducted most extensively in Saccharomyces cerevisiae, where the mechanism of its activation by amino acid starvation has been revealed in most detail. Uncharged tRNAs stimulate Gcn2 which subsequently phosphorylates its substrate, eIF2 alpha, leading to reduced global protein synthesis and simultaneously to increased translation of specific mRNAs, e.g. those coding for Gcn4 in yeast and ATF4 in mammals. Both proteins are transcription factors that regulate the expression of a myriad of genes, thereby enabling the cell to initiate a survival response to the initial activating cue. Given that Gcn2 participates in many diverse processes, Gcn2 itself must be tightly controlled. Indeed, Gcn2 is regulated by a vast network of proteins and RNAs, the list of which is still growing. Deciphering molecular mechanisms underlying Gcn2 regulation by effectors and inhibitors is fundamental for understanding how the cell keeps Gcn2 in check ensuring normal organismal function, and how Gcn2-associated diseases may develop or may be treated. This review provides a critical evaluation of the current knowledge on mechanisms controlling Gcn2 activation or activity. (C) 2014 Published by Elsevier B.V.Massey University Research FundAuckland Medical Research FoundationMaurice & Phyllis Paykel TrustNutricia Research FoundationFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Massey UniversityInstitute of Natural and Mathematical SciencesUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilMassey Univ, Inst Nat & Math Sci, Auckland 0745, Albany, New ZealandUniversidade Federal de São Paulo, Escola Paulista Med, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilAuckland Medical Research Foundation: 4109024Auckland Medical Research Foundation: 4113010Nutricia Research Foundation: 2010-35FAPESP: 2009/52047-5CNPq: 478903/2012-0CNPq: 309860/2011-3CNPq: 153660/2010-4CAPES: 1915-13-4Web of Scienc

    Metarhizium anisopliae blastospores are highly virulent to adult Aedes aegypti, an important arbovirus vector

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    BackgroundThe use of entomopathogenic fungi (EPF) for the control of adult mosquitoes is a promising alternative to synthetic insecticides. Previous studies have only evaluated conidiospores against adult mosquitoes. However, blastospores, which are highly virulent against mosquito larvae and pupae, could also be effective against adults.MethodsMetarhizium anisopliae (ESALQ 818 and LEF 2000) blastospores and conidia were first tested against adult Aedes aegypti by spraying insects with spore suspensions. Blastospores were then tested using an indirect contact bioassay, exposing mosquitoes to fungus-impregnated cloths. Virulence when using blastospores suspended in 20% sunflower oil was also investigated.ResultsFemale mosquitoes sprayed with blastospores or conidia at a concentration of 108 propagules ml−1 were highly susceptible to both types of spores, resulting in 100% mortality within 7 days. However, significant differences in virulence of the isolates and propagules became apparent at 107 spores ml−1, with ESALQ 818 blastospores being more virulent than LEF 2000 blastospores. ESALQ 818 blastospores were highly virulent when mosquitoes were exposed to black cotton cloths impregnated with blastospores shortly after preparing the suspensions, but virulence declined rapidly 12 h post-application. The addition of vegetable oil to blastospores helped maintain virulence for up to 48 h.ConclusionThe results showed that blastospores were more virulent to adult female Ae. aegypti than conidia when sprayed onto the insects or applied to black cloths. Vegetable oil helped maintain blastospore virulence. The results show that blastospores have potential for use in integrated vector management, although new formulations and drying techniques need to be investigated

    Evaluation of PM2.5 Surface Concentration Simulated by Version 1 of the Nasa's MERRA Aerosol Reanalysis Over Israel and Taiwan

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    Version 1 of the NASA MERRA Aerosol Reanalysis (MERRAero) assimilates bias-corrected 18 aerosol optical depth (AOD) data from MODIS-Terra and MODIS-Aqua, and simulates particulate 19 matter (PM) concentration data to reproduce a consistent database of AOD and PM concentration around 20 the world from 2002 to the end of 2015. The purpose of this paper is to evaluate MERRAeros simulation 21 of fine PM concentration against surface measurements in two regions of the world with relatively high 22 levels of PM concentration but with profoundly different PM composition, those of Israel and Taiwan. 23 Being surrounded by major deserts, Israels PM load is characterized by a significant contribution of 24 mineral dust, and secondary contributions of sea salt particles, given its proximity to the Mediterranean 25 Sea, and sulfate particles originating from Israels own urban activities and transported from Europe. 26 Taiwans PM load is composed primarily of anthropogenic particles (sulfate, nitrate and carbonaceous 27 particles) locally produced or transported from China, with an additional contribution of springtime 28 transport of mineral dust originating from Chinese and Mongolian deserts. The evaluation in Israel 29 produced favorable results with MERRAero slightly overestimating measurements by 6 on average 30 and reproducing an excellent year-to-year and seasonal fluctuation. The evaluation in Taiwan was less 31 favorable with MERRAero underestimating measurements by 42 on average. Two likely reasons 32 explain this discrepancy: emissions of anthropogenic PM and their precursors are largely uncertain in 33 China, and MERRAero doesnt include nitrate particles in its simulation, a pollutant of predominately 34 anthropogenic sources. MERRAero nevertheless simulates well the concentration of fine PM during the 35 summer, when Taiwan is least affected by the advection of pollution from China

    Taxonomic bias in amphibian research : Are researchers responding to conservation need?

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    Amphibians are very diverse, widely distributed, and the most endangered class of vertebrates. As with other taxa, effective conservation of amphibians needs to be supported by detailed scientific knowledge. However, species rich and broadly distributed taxa are typically characterized by high variability in research effort. Our objective was therefore to understand which factors (ecological and cultural) have led some amphibian species to be more researched than others. We used two proxies of research effort: i) the total number of articles on Web of Science (WoS) that mention the scientific name (or synonyms) of each species, and; ii) the number of conservation science articles on WoS that mention the scientific name (or synonyms) of each species. These measures were used as dependent variables in zero hurdle regression models with the aim of identifying the most important factors driving species-level knowledge production. Well researched species (generally, and for conservation) tend to have a longer history of scientific research, come from countries with high scientific capacity, have large body size, and to be present in man-made habitats. Endangered species tend to be less researched, generally and for conservation, possibly because they are often more difficult to study: many endangered amphibians are restricted to small, fragmented and remote habitats in countries with low scientific capacity. We conclude with a discussion of how taxonomic biases in research effort on amphibians can be addressed given the limited funds available for conservation research.Peer reviewe

    Indirect detection of superoxide in RAW 264.7 macrophage cells using microchip electrophoresis coupled to laser-induced fluorescence

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s00216-015-8865-1Superoxide is a naturally produced reactive oxygen species (ROS) in the human body and is involved in many pathological and physiological signaling processes. However, if superoxide formation is left unregulated, overproduction can lead to oxidative damage to important biomolecules, such as DNA, lipids, and proteins. Superoxide can also lead to the formation of peroxynitrite, an extremely hazardous substance, through its reaction with endogenously produced nitric oxide. Despite its importance, quantitative information regarding superoxide production is difficult to obtain due to its high reactivity and low concentrations in vivo. MitoHE, a fluorescent probe that specifically reacts with superoxide, was used in conjunction with microchip electrophoresis (ME) and laser-induced fluorescence detection to investigate changes in superoxide production by RAW 264.7 macrophage cells following stimulation with phorbol 12-myristate 13-acetate (PMA). Stimulation was performed in the presence and absence of the superoxide dismutase (SOD) inhibitors, diethyldithiocarbamate (DDC) and 2-metoxyestradiol (2-ME). The addition of these inhibitors resulted in an increase in the amount of superoxide specific product (2-OH-MitoE+) from 0.08 ± 0.01 fmol (0.17 ± 0.03 mM) in native cells to 1.26 ± 0.06 fmol (2.5 ± 0.1 mM) after PMA treatment. This corresponds to an approximately 15-fold increase in intracellular concentration per cell. Furthermore, the addition of 3-morpholino-sydnonimine (SIN-1) to the cells during incubation resulted in 0.061 ± 0.006 fmol (0.12 ± 0.01 mM) of 2-OH-MitoE+ per cell on average. These results demonstrate that indirect superoxide detection coupled with the use of SOD inhibitors and a separation method is a viable method to discriminate the 2-OH-MitoE+ signal from possible interferences
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