569 research outputs found

    Norwegian Aerospace Activities: an Overview

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    Excerpts from a Governmental Investigation concerning Norwegian participation in the European Space Organization (ESA) is presented. The implications and advantages of such a move and a suggestion for the reorganization of Norwegian Aerospace activity is given

    Kartlegging av forurensningstilstanden i Meråker gruvefelt

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    Avrenning fra kisgruvene i Meråkerfeltet påvirker fortsatt vannkvaliteten i vassdragene i nedbørfeltet selv 100 år etter at gruvedriften opphørte. Største forurensningskilde i området er Lillefjell gruve som bidrar med ca. 80 % av kobbertilførslene til Stjørdalselva som er ca. 3 tonn på årsbasis. Gilsåa og Dalåa er mest belastet med tungmetaller, men vassdragsreguleringen som er foretatt, kan ha bidratt til en forverret vannkvalitet i Torsbjørka nedenfor inntaket til kraftverket. Undersøkelser av bunnfaunaen viser klare påvirkninger i Dalåa, mens det var en naturlig bunnfauna i nedre del av Torsbjørka og i Stjørdalselva. Burforsøk med ørret viste en høy dødelighet i Gilsåa/Dalåa. Det ble også påvist at ørreten i Torsbjørka var metallbelastet

    Radiative corrections to hard spectator scattering in BππB\to \pi\pi decays

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    We present the calculation of the next-to-leading corrections to the tree amplitudes which appear in the description of non-leptonic B-decays in the factorization approach. These corrections, together with radiative corrections to the jet functions, represent the full next-to-leading contributions to the dominant hard spectator scattering term generated by operators O1,2O_{1,2} in the decay amplitudes. Using obtained analytical results we estimate BππB\to\pi\pi branchings fractions in the physical (or BBNS) factorization scheme. We have also found that the imaginary part generated in the hard spectator scattering term is rather large compared to the imaginary part of the vertex contribution.Comment: text is improved and typos are corrected, accepted for publication in JHE

    Signal-background separation and energy reconstruction of gamma rays using pattern spectra and convolutional neural networks for the Small-Sized Telescopes of the Cherenkov Telescope Array

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    Imaging Atmospheric Cherenkov Telescopes (IACTs) detect very high-energy gamma rays from ground level by capturing the Cherenkov light of the induced particle showers. Convolutional neural networks (CNNs) can be trained on IACT camera images of such events to differentiate the signal from the background and to reconstruct the energy of the initial gamma ray. Pattern spectra provide a 2-dimensional histogram of the sizes and shapes of features comprising an image and they can be used as an input for a CNN to significantly reduce the computational power required to train it. In this work, we generate pattern spectra from simulated gamma-ray and proton images to train a CNN for signal-background separation and energy reconstruction for the Small-Sized Telescopes (SSTs) of the Cherenkov Telescope Array (CTA). A comparison of our results with a CNN directly trained on CTA images shows that the pattern spectra-based analysis is about a factor of three less computationally expensive but not able to compete with the performance of the CTA images-based analysis. Thus, we conclude that the CTA images must be comprised of additional information not represented by the pattern spectra.Comment: 10 pages, 9 figures, submitted to Nuclear Instruments and Methods in Physics Research - section

    Sink i ferskvann - kjemi, tilførsler og biologiske effekter

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    Det er laget en kunnskapsstatus for betydningen av sink i ferskvann med særlig vekt på tilførsler fra gruveavrenning. I tillegg ble det utført en undersøkelse av biologiske effekter i et vassdrag. Sveselva, med sink-belastning, men få andre metaller. Alle levende organismer har behov for sink, men det er begrensede kunnskaper om mekanismene bak giftigheten til metallet. Effekt-grenser for akvatiske organismer varier fra 10 til over 1000 µg/l. Blant de mest følsomme organismene er enkelte alger, planktoniske krepsdyr og utviklingsstadier hos fisk. I Sveselva var det tilsynelatende effekter på vegetasjon (begroing) allerede ved 20-30 µg/l, men det er usikkert om dette var det reelle belastningsnivået. Både vegetasjon og bunndyr var klart påvirket på stasjoner med konsentrasjoner i området 250-670 µg/l. Kadmium og sink akkumulerte i gjellene til utplassert dammusling på alle stasjoner nedenfor tilførslene og førte til noe forhøyede konsentrasjoner av metallotionein. Dammusling med høye metall-nivåer i gjellene filtrerte mindre alger og hadde høyere respirasjon enn dammusling med lavere metall-nivåer i gjellene. Resultatene viser at det er viktig å benytte flere mål for biologiske effekter i overvåking av effektene av metall-forurensning og å integrere kjemisk og biologisk overvåking

    NatF Contributes to an Evolutionary Shift in Protein N-Terminal Acetylation and Is Important for Normal Chromosome Segregation

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    N-terminal acetylation (N-Ac) is a highly abundant eukaryotic protein modification. Proteomics revealed a significant increase in the occurrence of N-Ac from lower to higher eukaryotes, but evidence explaining the underlying molecular mechanism(s) is currently lacking. We first analysed protein N-termini and their acetylation degrees, suggesting that evolution of substrates is not a major cause for the evolutionary shift in N-Ac. Further, we investigated the presence of putative N-terminal acetyltransferases (NATs) in higher eukaryotes. The purified recombinant human and Drosophila homologues of a novel NAT candidate was subjected to in vitro peptide library acetylation assays. This provided evidence for its NAT activity targeting Met-Lys- and other Met-starting protein N-termini, and the enzyme was termed Naa60p and its activity NatF. Its in vivo activity was investigated by ectopically expressing human Naa60p in yeast followed by N-terminal COFRADIC analyses. hNaa60p acetylated distinct Met-starting yeast protein N-termini and increased general acetylation levels, thereby altering yeast in vivo acetylation patterns towards those of higher eukaryotes. Further, its activity in human cells was verified by overexpression and knockdown of hNAA60 followed by N-terminal COFRADIC. NatF's cellular impact was demonstrated in Drosophila cells where NAA60 knockdown induced chromosomal segregation defects. In summary, our study revealed a novel major protein modifier contributing to the evolution of N-Ac, redundancy among NATs, and an essential regulator of normal chromosome segregation. With the characterization of NatF, the co-translational N-Ac machinery appears complete since all the major substrate groups in eukaryotes are accounted for

    Protein N-terminal acetylation: NAT 2007–2008 Symposia

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    Protein N-terminal acetylation is a very common modification, but has during the past decades received relatively little attention. In order to put this neglected field back on the scientific map, we have in May 2007 and September 2008 arranged two international NAT symposia in Bergen, Norway. This supplement contains selected proceedings from these symposia reflecting the current status of the field, including an overview of protein N-terminal acetylation in yeast and humans, a novel nomenclature system for the N-terminal acetyltransferases (NATs) and methods for studying protein N-terminal acetylation in vitro and in vivo

    Entanglement study of the 1D Ising model with Added Dzyaloshinsky-Moriya interaction

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    We have studied occurrence of quantum phase transition in the one-dimensional spin-1/2 Ising model with added Dzyaloshinsky-Moriya (DM) interaction from bi- partite and multi-partite entanglement point of view. Using exact numerical solutions, we are able to study such systems up to 24 qubits. The minimum of the entanglement ratio R \equiv \tau 2/\tau 1 < 1, as a novel estimator of QPT, has been used to detect QPT and our calculations have shown that its minimum took place at the critical point. We have also shown both the global-entanglement (GE) and multipartite entanglement (ME) are maximal at the critical point for the Ising chain with added DM interaction. Using matrix product state approach, we have calculated the tangle and concurrence of the model and it is able to capture and confirm our numerical experiment result. Lack of inversion symmetry in the presence of DM interaction stimulated us to study entanglement of three qubits in symmetric and antisymmetric way which brings some surprising results.Comment: 18 pages, 9 figures, submitte

    Entanglement in the One-dimensional Kondo Necklace Model

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    We discuss the thermal and magnetic entanglement in the one-dimensional Kondo necklace model. Firstly, we show how the entanglement naturally present at zero temperature is distributed among pairs of spins according to the strength of the two couplings of the chain, namely, the Kondo exchange interaction and the hopping energy. The effect of the temperature and the presence of an external magnetic field is then investigated, being discussed the adjustment of these variables in order to control the entanglement available in the system. In particular, it is indicated the existence of a critical magnetic field above which the entanglement undergoes a sharp variation, leading the ground state to a completely unentangled phase.Comment: 8 pages, 13 EPS figures. v2: four references adde

    Introducing the composite time trade-off: a test of feasibility and face validity

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    __Abstract__ __Introduction__ This study was designed to test the feasibility and face validity of the composite time trade-off (composite TTO), a new approach to TTO allowing for a more consistent elicitation of negative health state values. __Methods__ The new instrument combines a conventional TTO to elicit values for states regarded better than dead and a lead-time TTO for states worse than dead. __Results__ A total of 121 participants completed the composite TTO for ten EQ-5D-5L health states. Mean values ranged from −0.104 for health state 53555 to 0.946 for 21111. The instructions were clear to 98 % of the respondents, and 95 % found the task easy to understand, indicating feasibility. Further, the average number of steps taken in the iteration procedure to achieve the point of indifference in the TTO and the average duration of each task were indicative of a deliberate cognitive process. __Conclusion__ Face validity was confirmed by the high mean values for the mild health states (>0.90) and low mean values for the severe states (<0.42). In conclusion, this study demonstrates the feasibility and face validity of the composite TTO in a face-to-face standardized computer-assisted interview setting
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