94 research outputs found

    The Beast to the East: Norway\u27s Russia-Policy After Crimea - Status Quo or a Shift in Policy?

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    This research examines Norway’s Russia-policy following the Russian annexation of the Crimean Peninsula and the aggression in East Ukraine. The research identifies attributes of Norway’s Russia-policy before and after Crimea and applies realist and liberal international relations theory to the discussion on whether Norway’s policy doctrine has changed. The main conclusion is that there has been a shift in Norway’s Russia-policy in the aftermath of Crimea from a liberal approach to realist foreign policy doctrine, but that Norway retain some emphasis on preserving normalized bilateral relations and cooperation

    Automatic Detection of Atrial Fibrillation Using Electrocardiomatrix and Convolutional Neural Network

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    Long-term electrocardiogram (ECG) monitoring is a standard clinical routine in cryptogenic stroke survivors to assess the presence of atrial fibrillation (AF). However, manual evaluation of such recordings is time consuming, in particular when brief episodes are of interest. The electrocardiomatrix (ECM) technique allows compact, two-dimensional representation of the ECG and facilitates its review. In this study, we present a convolutional neural network (CNN) approach for automatic detection of AF based on ECM images. ECG segments of only 10 beats were converted into ECM images. A CNN was implemented to classify the ECMs between non-AF and AF. The CNN was trained using the MIT-BIH-NSR and the MIT-BIH-LTAF, and tested on the MIT-BIH-AF. A total of 120088 non-AF and 108088 AF ECM images were classified with accuracy of 86.95%. This study suggests that a CNN allows automatic detection of AF episodes of only 10 beats when the ECG data is represented as an ECM image

    Feature selection for high-dimensional neural network potentials with the adaptive group lasso

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    Neural network potentials are a powerful tool for atomistic simulations, allowing to accurately reproduce ab initio potential energy surfaces with computational performance approaching classical force fields. A central component of such potentials is the transformation of atomic positions into a set of atomic features in a most efficient and informative way. In this work, a feature selection method is introduced for high dimensional neural network potentials, based on the adaptive group lasso (AGL) approach. It is shown that the use of an embedded method, taking into account the interplay between features and their action in the estimator, is necessary to optimize the number of features. The method's efficiency is tested on three different monoatomic systems, including Lennard–Jones as a simple test case, Aluminium as a system characterized by predominantly radial interactions, and Boron as representative of a system with strongly directional components in the interactions. The AGL is compared with unsupervised filter methods and found to perform consistently better in reducing the number of features needed to reproduce the reference simulation data at a similar level of accuracy as the starting feature set. In particular, our results show the importance of taking into account model predictions in feature selection for interatomic potentials

    The Lyman Alpha Reference Sample: III. Properties of the Neutral ISM from GBT and VLA Observations

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    We present new H I imaging and spectroscopy of the 14 UV-selected star-forming galaxies in the Lyman Alpha Reference Sample (LARS), aimed for a detailed study of the processes governing the production, propagation, and escape of Lyα\alpha photons. New H I spectroscopy, obtained with the 100m Green Bank Telescope (GBT), robustly detects the H I spectral line in 11 of the 14 observed LARS galaxies (although the profiles of two of the galaxies are likely confused by other sources within the GBT beam); the three highest redshift galaxies are not detected at our current sensitivity limits. The GBT profiles are used to derive fundamental H I line properties of the LARS galaxies. We also present new pilot H I spectral line imaging of 5 of the LARS galaxies obtained with the Karl G. Jansky Very Large Array (VLA). This imaging localizes the H I gas and provides a measurement of the total H I mass in each galaxy. In one system, LARS 03 (UGC 8335 or Arp 238), VLA observations reveal an enormous tidal structure that extends over 160 kpc from the main interacting systems and that contains >>109^9 M_{\odot} of H I. We compare various H I properties with global Lyα\alpha quantities derived from HST measurements. The measurements of the Lyα\alpha escape fraction are coupled with the new direct measurements of H I mass and significantly disturbed H I velocities. Our robustly detected sample reveals that both total H I mass and linewidth are tentatively correlated with key Lyα\alpha tracers. Further, on global scales, these data support a complex coupling between Lyα\alpha propagation and the H I properties of the surrounding medium.Comment: Preprint form, 16 figures, accepted in Ap

    Machine learning interatomic potentials for aluminium: application to solidification phenomena

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    In studying solidification process by simulations on the atomic scale, the modeling of crystal nucleation or amorphization requires the construction of interatomic interactions that are able to reproduce the properties of both the solid and the liquid states. Taking into account rare nucleation events or structural relaxation under deep undercooling conditions requires much larger length scales and longer time scales than those achievable by ab initio molecular dynamics (AIMD). This problem is addressed by means of classical molecular dynamics simulations using a well established high dimensional neural network potential trained on a set of configurations generated by AIMD relevant for solidification phenomena. Our dataset contains various crystalline structures and liquid states at different pressures, including their time fluctuations in a wide range of temperatures. Applied to elemental aluminium, the resulting potential is shown to be efficient to reproduce the basic structural, dynamics and thermodynamic quantities in the liquid and undercooled states. Early stages of crystallization are further investigated on a much larger scale with one million atoms, allowing us to unravel features of the homogeneous nucleation mechanisms in the fcc phase at ambient pressure as well as in the bcc phase at high pressure with unprecedented accuracy close to the ab initio one. In both cases, a single step nucleation process is observed

    Formate overflow drives toxic folate trapping in MTHFD1 inhibited cancer cells

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    Cancer cells fuel their increased need for nucleotide supply by upregulating one-carbon (1C) metabolism, including the enzymes methylenetetrahydrofolate dehydrogenase-cyclohydrolase 1 and 2 (MTHFD1 and MTHFD2). TH9619 is a potent inhibitor of dehydrogenase and cyclohydrolase activities in both MTHFD1 and MTHFD2, and selectively kills cancer cells. Here, we reveal that, in cells, TH9619 targets nuclear MTHFD2 but does not inhibit mitochondrial MTHFD2. Hence, overflow of formate from mitochondria continues in the presence of TH9619. TH9619 inhibits the activity of MTHFD1 occurring downstream of mitochondrial formate release, leading to the accumulation of 10-formyl-tetrahydrofolate, which we term a 'folate trap'. This results in thymidylate depletion and death of MTHFD2-expressing cancer cells. This previously uncharacterized folate trapping mechanism is exacerbated by physiological hypoxanthine levels that block the de novo purine synthesis pathway, and additionally prevent 10-formyl-tetrahydrofolate consumption for purine synthesis. The folate trapping mechanism described here for TH9619 differs from other MTHFD1/2 inhibitors and antifolates. Thus, our findings uncover an approach to attack cancer and reveal a regulatory mechanism in 1C metabolism.In this study, Green, Marttila, Kiweler et al. characterize one-carbon metabolism rewiring in response to a dual MTHFD1 and MTHFD2 inhibitor. This work provides insight into one-carbon fluxes, and reveals a previously uncharacterized vulnerability in cancer cells created by folate trapping

    Nevrological manifestations in patiens with West Nile fever

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    Гарячка Західного Нілу (ГЗН) є найпоширенішим зооантропонозним трансмісивним «комариним» захворюванням у групі природно осередкових інфекцій. Вірус ГЗН належить до роду Flavivirus родини Flaviviridae, поширений на усіх континентах за винятком Антарктиди. В Європі основним видом комарів, які передають вірус ГЗН людям, є Culex pipiens. Інфікування описане також при вертикальній передачі від матері до дитини та парентеральним шляхом. За філогенетичними властивостями вірусу розрізняють кілька генетичних груп – генотипів, деякі з яких містять підгрупи, що обумовлює нерівномірний територіальний розподіл та тяжкість клінічної маніфестації ГЗН

    Recurrent attacks of acute hepatic porphyria: major role of the chronic inflammatory response in the liver

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    Acute intermittent porphyria (AIP) is an inherited disorder of heme metabolism characterized by life-threatening acute neurovisceral attacks due to the induction of hepatic -aminolevulinic acid synthase 1 (ALAS1) associated with hydroxymethylbilane synthase (HMBS) deficiency. Hemin represses ALAS1 and restores metabolic equilibrium. The main issue in the medical care of AIP patients is the occurrence of debilitating recurrent attacks. Chronically ill patients require repeated hemin infusions and develop secondary hemochromatosis and have a poorer quality of life. To decipher the mechanisms underlying recurrence in AIP patients, we studied the metabolic pathways altered by chronic hemin administration. A follow-up study was conducted between 1974 and 2015 and included 602 French AIP patients, of whom 46 had recurrent AIP. Moreover, we studied the hepatic transcriptome, serum proteome, liver macrophage polarization and oxidative and inflammatory profiles of Hmbs-/- mice chronically treated by hemin and extended the investigations to 5 human explanted livers. The introduction of hemin into the pharmacopeia has coincided with a 4.4-fold increase in the prevalence of chronic patients. We show that repeated hemin infusions trigger a high level heme oxygenase 1 (HO1) response, induce a pro-oxidative iron accumulation and a complex pattern of liver inflammation with macrophage infiltration. Conclusion: chronically heme-treated AIP patients may present with symptoms of an inflammatory disease responsible for an adaptive HO1 induction that could deplete the free heme pool inducing ALAS1. Hemin remains the most effective treatment but should be restricted to patients with severe forms of AIP to prevent chronic damage

    Erratum to: Methods for evaluating medical tests and biomarkers

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    [This corrects the article DOI: 10.1186/s41512-016-0001-y.]
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