4,361 research outputs found

    State estimation of medium voltage distribution networks using smart meter measurements

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    Distributed generation and low carbon loads are already leading to some restrictions in the operation of distribution networks and higher penetrations of e.g. PV generation, heat pumps and electric vehicles will exacerbate such problems. In order to manage the distribution network effectively in this new situation, increased real-time monitoring and control will become necessary. In the future, distribution network operators will have smart meter measurements available to them to facilitate safe and cost-effective operation of distribution networks. This paper investigates the application of smart meter measurements to extend the observability of distribution networks. An integrated load and state estimation algorithm was developed and tested using residential smart metering measurements and an 11 kV residential distribution network. Simulation results show that smart meter measurements, both real-time and pseudo measurements derived from them, can be used together with state estimation to extend the observability of a distribution network. The integrated load and state estimation algorithm was shown to produce accurate voltage magnitudes and angles at each busbar of the network. As a result, the algorithm can be used to enhance distribution network monitoring and contro

    k-means based load estimation of domestic smart meter measurements

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    A load estimation algorithm based on kk-means cluster analysis was developed. The algorithm applies cluster centres – of previously clustered load profiles – and distance functions to estimate missing and future measurements. Canberra, Manhattan, Euclidean, and Pearson correlation distances were investigated. Several case studies were implemented using daily and segmented load profiles of aggregated smart meters. Segmented profiles cover a time window that is less than or equal to 24 h. Simulation results show that Canberra distance outperforms the other distance functions. Results also show that the segmented cluster centres produce more accurate load estimates than daily cluster centres. Higher accuracy estimates were obtained with cluster centres in the range of 16–24 h. The developed load estimation algorithm can be integrated with state estimation or other network operational tools to enable better monitoring and control of distribution networks

    Electrophysiological Assessment of Primary Cortical Neurons Genetically Engineered using Iron Oxide Nanoparticles

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    The development of safe technologies to genetically modify neurons is of great interest in regenerative neurology, for both translational and basic science applications. Such approaches have conventionally been heavily reliant on viral transduction methods, which have safety and production limitations. Magnetofection (magnet-assisted gene transfer using iron oxide nanoparticles as vectors) has emerged as a highly promising non-viral alternative for safe and reproducible genetic modification of neurons. Despite the high potential of this technology, there is an important gap in our knowledge of the safety of this approach, namely, whether it alters neuronal function in adverse ways, such as by altering neuronal excitability and signaling. We have investigated the effects of magnetofection in primary cortical neurons by examining neuronal excitability using the whole cell patch clamp technique. We found no evidence that magnetofection alters the voltage-dependent sodium and potassium ionic currents that underpin excitability. Our study provides important new data supporting magnetofection as a safe technology for bioengineering of neuronal cell populations

    Public perception of mental health in Iraq

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    <p>Abstract</p> <p>Background</p> <p>People who suffer from mental illness, the professionals who treat them, and indeed the actual concept of mental illness are all stigmatised in public perception and often receive very negative publicity. This paper looks at Iraq, which has a population of 30 million who are mainly Moslem. Mental health services and professionals have historically been sparse in Iraq with 1 psychiatrist per 300,000 before 2003 falling to 1 per million until recently and 1 primary care centre (40 Healthcare Workers including 4 General Practitioners) to 35,000 population, compared with 1 GP per 1700 population in the UK.</p> <p>Methods</p> <p>We aimed to assess public attitudes and perceptions to mental illness. Participants were asked to complete a questionnaire (additional file <supplr sid="S1">1</supplr>), which was designed specifically for Iraqi contexts and was made available in 2 languages. The survey was carried out in 500 participants' homes across 2 districts of Baghdad.</p> <suppl id="S1"> <title> <p>Additional file 1</p> </title> <text> <p><b>Public Perception of Mental Illness Questionnaire</b>.</p> </text> <file name="1752-4458-4-26-S1.DOC"> <p>Click here for file</p> </file> </suppl> <p>Results</p> <p>The response rate of the survey was 86.4%. The paper shows respondents views on the aetiology of mental illness, perceptions of people with mental illness and attitudes towards care and treatment of people with mental illness.</p> <p>Conclusions</p> <p>This survey of public attitudes towards mental illness in Iraq has shown that community opinion about the aetiology of mental illness is broadly compatible with scientific evidence, but understanding of the nature of mental illness, its implications for social participation and management remains negative in general.</p

    Three classes of ligands each bind to distinct sites on the orphan G protein-coupled receptor GPR84

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    Medium chain fatty acids can activate the pro-inflammatory receptor GPR84 but so also can molecules related to 3,3′-diindolylmethane. 3,3′-Diindolylmethane and decanoic acid acted as strong positive allosteric modulators of the function of each other and analysis showed the affinity of 3,3′-diindolylmethane to be at least 100 fold higher. Methyl decanoate was not an agonist at GPR84. This implies a key role in binding for the carboxylic acid of the fatty acid. Via homology modelling we predicted and confirmed an integral role of arginine172, located in the 2nd extracellular loop, in the action of decanoic acid but not of 3,3′-diindolylmethane. Exemplars from a patented series of GPR84 antagonists were able to block agonist actions of both decanoic acid and 3,3′-diindolylmethane at GPR84. However, although a radiolabelled form of a related antagonist, [3H]G9543, was able to bind with high affinity to GPR84, this was not competed for by increasing concentrations of either decanoic acid or 3,3′-diindolylmethane and was not affected adversely by mutation of arginine172. These studies identify three separable ligand binding sites within GPR84 and suggest that if medium chain fatty acids are true endogenous regulators then co-binding with a positive allosteric modulator would greatly enhance their function in physiological settings

    The \u3cem\u3ePhaeodactylum\u3c/em\u3e genome reveals the evolutionary history of diatom genomes

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    Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one-fifth of the primary productivity on Earth1,2. The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology3,4,5. Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (∼40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans

    Decays of =1\ell=1 Baryons --- Quark Model versus Large-NcN_c

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    We study nonleptonic decays of the orbitally excited, \su6 \rep{70}-plet baryons in order to test the hypothesis that the successes of the nonrelativistic quark model have a natural explanation in the large-NcN_c limit of QCD. By working in a Hartree approximation, we isolate a specific set of operators that contribute to the observed s- and d-wave decays in leading order in 1/Nc1/N_c. We fit our results to the current experimental decay data, and make predictions for a number of allowed but unobserved modes. Our tentative conclusion is that there is more to the nonrelativistic quark model of baryons than large-NcN_c.Comment: LaTeX 49pp. (38 pp. landscape), PicTex, PrePicTex, PostPicTex required for 3 figures, Harvard Preprint HUTP-94/A008. (Two additional operators are included, but conclusions are unchanged.

    A disciplinary commons for database teaching

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    This paper discusses the experience of taking part in a disciplinary commons devoted to the teaching of database systems. It will discuss the structure of a disciplinary commons and our experience of the database version
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