624 research outputs found

    Neurocontroller Alternatives for Fuzzy Ball-and-Beam Systems with Nonuniform Nonlinear Friction

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    The ball-and-beam problem is a benchmark for testing control algorithms. Zadeh proposed (1994) a twist to the problem, which, he suggested, would require a fuzzy logic controller. This experiment uses a beam, partially covered with a sticky substance, increasing the difficulty of predicting the ball\u27s motion. We complicated this problem even more by not using any information concerning the ball\u27s velocity. Although it is common to use the first differences of the ball\u27s consecutive positions as a measure of velocity and explicit input to the controller, we preferred to exploit recurrent neural networks, inputting only consecutive positions instead. We have used truncated backpropagation through time with the node-decoupled extended Kalman filter (NDEKF) algorithm to update the weights in the networks. Our best neurocontroller uses a form of approximate dynamic programming called an adaptive critic design. A hierarchy of such designs exists. Our system uses dual heuristic programming (DHP), an upper-level design. To our best knowledge, our results are the first use of DHP to control a physical system. It is also the first system we know of to respond to Zadeh\u27s challenge. We do not claim this neural network control algorithm is the best approach to this problem, nor do we claim it is better than a fuzzy controller. It is instead a contribution to the scientific dialogue about the boundary between the two overlapping disciplines

    Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories

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    A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed

    Measuring and theorizing regional governance

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    This symposium Regional Authority and the Postfunctionalist Theory of Governance engages two recent books on regional governance. The first sets out a measure of regional authority for 81 countries in North America, Europe, Latin America, Asia and the Pacific between 1950 and 2010. The second theorizes how regional governance is shaped by functional and communal pressures. These pressures are detected in many historical episodes of jurisdictional reform. These books seek to pin them down empirically. Community and efficiency appear to have tangible and contrasting effects that explain how jurisdictions are designed, why regional governance has become differentiated and how multilevel governance has deepened over the past several decades. The symposium consists of contributions by Kent Eaton, Jean-Paul Faguet and Imke Harbers followed by a response from the authors: Liesbet Hooghe, Gary Marks, Arjan H. Schakel, Sara Niedzwiecki, Sandra Chapman Osterkatz and Sarah Shair-Rosenfield, Measuring Regional Authority: A Postfunctionalist Theory of Governance, Vol. I. Oxford: Oxford University Press, 2016; and Liesbet Hooghe and Gary Marks, with Arjan H. Schakel, Sara Niedzwiecki, Sandra Chapman Osterkatz and Sarah Shair-Rosenfield, Community, Scale, and Regional Governance: A Postfunctionalist Theory of Governance, Vol. II. Oxford: Oxford University Press, 2016

    'To live and die [for] Dixie': Irish civilians and the Confederate States of America

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    Around 20,000 Irishmen served in the Confederate army in the Civil War. As a result, they left behind, in various Southern towns and cities, large numbers of friends, family, and community leaders. As with native-born Confederates, Irish civilian support was crucial to Irish participation in the Confederate military effort. Also, Irish civilians served in various supporting roles: in factories and hospitals, on railroads and diplomatic missions, and as boosters for the cause. They also, however, suffered in bombardments, sieges, and the blockade. Usually poorer than their native neighbours, they could not afford to become 'refugees' and move away from the centres of conflict. This essay, based on research from manuscript collections, contemporary newspapers, British Consular records, and Federal military records, will examine the role of Irish civilians in the Confederacy, and assess the role this activity had on their integration into Southern communities. It will also look at Irish civilians in the defeat of the Confederacy, particularly when they came under Union occupation. Initial research shows that Irish civilians were not as upset as other whites in the South about Union victory. They welcomed a return to normalcy, and often 'collaborated' with Union authorities. Also, Irish desertion rates in the Confederate army were particularly high, and I will attempt to gauge whether Irish civilians played a role in this. All of the research in this paper will thus be put in the context of the Drew Gilpin Faust/Gary Gallagher debate on the influence of the Confederate homefront on military performance. By studying the Irish civilian experience one can assess how strong the Confederate national experiment was. Was it a nation without a nationalism

    Proteomic profiling of neuronal mitochondria reveals modulators of synaptic architecture

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    Abstract Background Neurons are highly polarized cells consisting of three distinct functional domains: the cell body (and associated dendrites), the axon and the synapse. Previously, it was believed that the clinical phenotypes of neurodegenerative diseases were caused by the loss of entire neurons, however it has recently become apparent that these neuronal sub-compartments can degenerate independently, with synapses being particularly vulnerable to a broad range of stimuli. Whilst the properties governing the differential degenerative mechanisms remain unknown, mitochondria consistently appear in the literature, suggesting these somewhat promiscuous organelles may play a role in affecting synaptic stability. Synaptic and non-synaptic mitochondrial subpools are known to have different enzymatic properties (first demonstrated by Lai et al., 1977). However, the molecular basis underpinning these alterations, and their effects on morphology, has not been well documented. Methods The current study has employed electron microscopy, label-free proteomics and in silico analyses to characterize the morphological and biochemical properties of discrete sub-populations of mitochondria. The physiological relevance of these findings was confirmed in-vivo using a molecular genetic approach at the Drosophila neuromuscular junction. Results Here, we demonstrate that mitochondria at the synaptic terminal are indeed morphologically different to non-synaptic mitochondria, in both rodents and human patients. Furthermore, generation of proteomic profiles reveals distinct molecular fingerprints – highlighting that the properties of complex I may represent an important specialisation of synaptic mitochondria. Evidence also suggests that at least 30% of the mitochondrial enzymatic activity differences previously reported can be accounted for by protein abundance. Finally, we demonstrate that the molecular differences between discrete mitochondrial sub-populations are capable of selectively influencing synaptic morphology in-vivo. We offer several novel mitochondrial candidates that have the propensity to significantly alter the synaptic architecture in-vivo. Conclusions Our study demonstrates discrete proteomic profiles exist dependent upon mitochondrial subcellular localization and selective alteration of intrinsic mitochondrial proteins alters synaptic morphology in-vivo

    Dysregulation of ubiquitin homeostasis and β-catenin signaling promote spinal muscular atrophy

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    Acknowledgements The authors are grateful to Nils Lindstrom and members of the Gillingwater laboratory for advice and assistance with this study and helpful comments on the manuscript; Neil Cashman for the NSC-34 cell line; and Ji-Long Liu for the DrosophilasmnA and smnB lines. This work was supported by grants from the SMA Trust (to T.H. Gillingwater, P.J. Young, and R. Morse), BDF Newlife (to T.H. Gillingwater and S.H. Parson), the Anatomical Society (to T.H. Gillingwater and S.H. Parson), the Muscular Dystrophy Campaign (to T.H. Gillingwater), the Jennifer Trust for Spinal Muscular Atrophy (to H.R. Fuller), the Muscular Dystrophy Association (to G.E. Morris), the Vandervell Foundation (to P.J. Young), the Medical Research Council (GO82208 to I.M. Robinson), Roslin Institute Strategic Grant funding from the BBSRC (to T.M. Wishart), the BBSRC (to C.G. Becker), the Deutsche Forschungsgemeinschaft and EU FP7/2007-2013 (grant no. 2012-305121, NeurOmics, to B. Wirth), the Center for Molecular Medicine Cologne (to B. Wirth and M. Hammerschmidt), and SMA Europe (to M.M. Reissland). We would also like to acknowledge financial support to the Gillingwater lab generated through donations to the SMASHSMA campaign.Peer reviewedPublisher PD

    Variability in the Dynamics of Mortality and Immobility Responses of Freshwater Arthropods Exposed to Chlorpyrifos

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    The species sensitivity distribution (SSD) concept is an important probabilistic tool for environmental risk assessment (ERA) and accounts for differences in species sensitivity to different chemicals. The SSD model assumes that the sensitivity of the species included is randomly distributed. If this assumption is violated, indicator values, such as the 50% hazardous concentration, can potentially change dramatically. Fundamental research, however, has discovered and described specific mechanisms and factors influencing toxicity and sensitivity for several model species and chemical combinations. Further knowledge on how these mechanisms and factors relate to toxicologic standard end points would be beneficial for ERA. For instance, little is known about how the processes of toxicity relate to the dynamics of standard toxicity end points and how these may vary across species. In this article, we discuss the relevance of immobilization and mortality as end points for effects of the organophosphate insecticide chlorpyrifos on 14 freshwater arthropods in the context of ERA. For this, we compared the differences in response dynamics during 96 h of exposure with the two end points across species using dose response models and SSDs. The investigated freshwater arthropods vary less in their immobility than in their mortality response. However, differences in observed immobility and mortality were surprisingly large for some species even after 96 h of exposure. As expected immobility was consistently the more sensitive end point and less variable across the tested species and may therefore be considered as the relevant end point for population of SSDs and ERA, although an immobile animal may still potentially recover. This is even more relevant because an immobile animal is unlikely to survive for long periods under field conditions. This and other such considerations relevant to the decision-making process for a particular end point are discussed
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