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  • 1
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    High‐Resolution Optical Observations of Neutral Heating Associated With the Electrodynamics of an Auroral Arc (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract We present results that indicate the existence of two distinct neutral heating processes associated with a discrete auroral arc over Svalbard. Within the order of seconds, the thermospheric temperature profile displays a significant response to the arc on spatial scales smaller than 10 km. It is suggested that both heating signatures are associated with the electrodynamic system responsible for the formation of the arc. Pedersen currents produce a temperature increase of approximately 100 K, observed at altitudes between 80 and 160 kilometres, directly adjacent to the arc structure and on its poleward edge only. In contrast, field‐aligned currents produce a variable temperature increase, of approximately 50 K, which is observed within the arc itself and constrained to a narrow altitude range between 90 and 110 km. By utilizing a range of observations and new analysis methods we are able to measure the atmospheric neutral temperature profile, over auroral altitudes, at unprecedented temporal and spatial scales. The High Throughput Imaging Echelle Spectrograph records high‐resolution emission spectra of the aurora, which are then fitted with synthetic N2 spectra, generated with modeled N2 volume emission rate profiles and a library of trial temperature profiles. The N2 volume emission rate profiles are retrieved from the Southampton ionospheric model using precipitating particle energies and fluxes obtained from Auroral Structure and Kinetics and the EISCAT Svalbard Radar. The application of this technique allows us to produce a time series of neutral temperature profiles and measure the localized heating of the neutral atmosphere resulting from the electrodynamics of the arc.
    Print ISSN: 2169-9380
    Electronic ISSN: 2169-9402
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    Kinematic detection of a planet carving a gap in a protoplanetary disk (2019)
    Springer Nature
    Details
    Publication Date: 2019
    Electronic ISSN: 2397-3366
    Topics: Physics
    Published by Springer Nature
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  • 3
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    Can non-ideal magnetohydrodynamics solve the magnetic braking catastrophe? (2016)
    Oxford University Press
    Details
    Publication Date: 2016-01-29
    Description: We investigate whether or not the low ionization fractions in molecular cloud cores can solve the ‘magnetic braking catastrophe’, where magnetic fields prevent the formation of circumstellar discs around young stars. We perform three-dimensional smoothed particle non-ideal magnetohydrodynamics (MHD) simulations of the gravitational collapse of one solar mass molecular cloud cores, incorporating the effects of ambipolar diffusion, Ohmic resistivity and the Hall effect alongside a self-consistent calculation of the ionization chemistry assuming 0.1 μm grains. When including only ambipolar diffusion or Ohmic resistivity, discs do not form in the presence of strong magnetic fields, similar to the cases using ideal MHD. With the Hall effect included, disc formation depends on the direction of the magnetic field with respect to the rotation vector of the gas cloud. When the vectors are aligned, strong magnetic braking occurs and no disc is formed. When the vectors are anti-aligned, a disc with radius of 13 au can form even in strong magnetic when all three non-ideal terms are present, and a disc of 38 au can form when only the Hall effect is present; in both cases, a counter-rotating envelope forms around the first hydrostatic core. For weaker, anti-aligned fields, the Hall effect produces massive discs comparable to those produced in the absence of magnetic fields, suggesting that planet formation via gravitational instability may depend on the sign of the magnetic field in the precursor molecular cloud core.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 4
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    Post-periapsis pancakes: sustenance for self-gravity in tidal disruption events (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-03
    Description: A tidal disruption event, which occurs when a star is destroyed by the gravitational field of a supermassive black hole, produces a stream of debris, the evolution of which ultimately determines the observational properties of the event. Here, we show that a post-periapsis caustic – a location where the locus of gas parcels comprising the stream would collapse into a two-dimensional surface if they evolved solely in the gravitational field of the hole – occurs when the pericentre distance of the star is of the order of the tidal radius of the hole. It is demonstrated that this ‘pancake’ induces significant density perturbations in the debris stream, and, for stiffer equations of state (adiabatic index 5/3), these fluctuations are sufficient to gravitationally destabilize the stream, resulting in its fragmentation into bound clumps. The results of our findings are discussed in the context of the observational properties of tidal disruption events.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 5
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    Domain-Wall Spin Dynamics in Kagome Antiferromagnets (2011)
    American Physical Society (APS)
    Details
    Publication Date: 2011-12-17
    Description: Author(s): E. Lhotel, V. Simonet, J. Ortloff, B. Canals, C. Paulsen, E. Suard, T. Hansen, D. J. Price, P. T. Wood, A. K. Powell, and R. Ballou [Phys. Rev. Lett. 107, 257205] Published Fri Dec 16, 2011
    Keywords: Condensed Matter: Electronic Properties, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society (APS)
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  • 6
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    Rapamycin-induced inhibition of the 70-kilodalton S6 protein kinase (1992)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1992-08-14
    Description: The immunosuppressant rapamycin inhibited proliferation of the H4IIEC hepatoma cell line. Rapamycin, but not its structural analog FK506, also inhibited the basal and insulin-stimulated activity of the p70 ribosomal protein S6 kinase. By contrast, insulin stimulation of the p85 Rsk S6 kinase and mitogen-activated protein (MAP) kinase activity were unaffected by drug. Rapamycin treatment of COS cells transfected with recombinant p70 S6 kinase completely inhibited the appearance of the hyperphosphorylated form of p70 S6 kinase concomitant with the inhibition of enzyme activity toward 40S subunits. Thus, rapamycin inhibits a signal transduction element that is necessary for the activation of p70 S6 kinase and mitogenesis but unnecessary for activation of p85 Rsk S6 kinase or MAP kinase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Price, D J -- Grove, J R -- Calvo, V -- Avruch, J -- Bierer, B E -- P01 CA39542/CA/NCI NIH HHS/ -- R01 DK17776/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1992 Aug 14;257(5072):973-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Diabetes Unit, Massachusetts General Hospital, Boston.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1380182" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium-Calmodulin-Dependent Protein Kinases ; Cell Line ; Chromatography, Ion Exchange ; Cyclosporine/pharmacology ; Immunosuppressive Agents/*pharmacology ; Insulin/pharmacology ; Kinetics ; Liver Neoplasms, Experimental ; Polyenes/*pharmacology ; *Protein Kinase Inhibitors ; Protein Kinases/genetics/isolation & purification/*metabolism ; Recombinant Proteins/antagonists & inhibitors/isolation & purification ; Ribosomal Protein S6 Kinases ; Ribosomes/enzymology ; Sirolimus ; Tacrolimus/pharmacology ; Tetradecanoylphorbol Acetate/pharmacology ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Producing ultrastrong magnetic fields in neutron star mergers (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-04-01
    Description: We report an extremely rapid mechanism for magnetic field amplification during the merger of a binary neutron star system. This has implications for the production of the short class of gamma-ray bursts, which recent observations suggest may originate in such mergers. In detailed magnetohydrodynamic simulations of the merger process, the fields are amplified by Kelvin-Helmholtz instabilities beyond magnetar field strength and may therefore represent the strongest magnetic fields in the universe. The amplification occurs in the shear layer that forms between the neutron stars and on a time scale of only 1 millisecond, that is, long before the remnant can collapse into a black hole.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Price, D J -- Rosswog, S -- New York, N.Y. -- Science. 2006 May 5;312(5774):719-22. Epub 2006 Mar 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16574823" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 8
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    Recombinant fragment of protein kinase inhibitor blocks cyclic AMP-dependent gene transcription (1987)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1987-10-23
    Description: Transcriptional regulation by cyclic adenosine monophosphate (cAMP) in mammalian cells could be mediated by a phosphoprotein substrate of the cAMP-dependent protein kinase or, as in prokaryotes, by a cAMP-binding protein. Two synthetic genes that code for an active fragment of the protein inhibitor of this kinase and a mutant inactive fragment were constructed and used to distinguish these alternatives. Transient expression of the active peptide product specifically inhibited the cAMP-stimulated expression of a cotransfected reporter gene by more than 90 percent, whereas the expression of the inactive peptide did not alter cAMP-stimulated gene expression. The results indicate that an active kinase catalytic subunit is a necessary intermediate in the cAMP stimulation of gene transcription.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grove, J R -- Price, D J -- Goodman, H M -- Avruch, J -- New York, N.Y. -- Science. 1987 Oct 23;238(4826):530-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02114.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2821622" target="_blank"〉PubMed〈/a〉
    Keywords: Acetyltransferases/genetics ; Carrier Proteins/*pharmacology ; Chloramphenicol O-Acetyltransferase ; Cyanogen Bromide ; Cyclic AMP/*pharmacology ; DNA, Recombinant ; Escherichia coli/genetics ; *Intracellular Signaling Peptides and Proteins ; Nucleic Acid Hybridization ; Peptide Fragments/*pharmacology ; Phosphorylation ; Plasmids ; Protein Kinase Inhibitors ; Protein Kinases/metabolism ; RNA, Messenger/genetics ; Recombinant Proteins/*pharmacology ; Transcription, Genetic/*drug effects ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of General Anesthetics and Pressure on Mammalian Excitatory Receptors Expressed in Xenopus Oocytes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 625 (1991), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1991.tb33834.x
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  • 10
    Electronic Resource
    Electronic Resource
    Natural hybrids between Atlantic salmon, Salmo salar L., and trout, Salmo trutta L., in juvenile salmonid populations in south-west England (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 39 (1991), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Electrophoretic analysis of juvenile salmonids from south-west England revealed the presence of natural hybrids between Atlantic salmon, Salmo salar L., and brown trout, Salmo rrurra L., within three of five rivers. Amongst 409 juvenile ‘salmon’, 1.2% were hybrids, and of 150 juvenile ‘trout’ sampled, 2.0% were natural hybrids. In one river, similar hybridization levels in ‘salmon’ parr samples were found in two successive years. Levels of hybridization are high when compared with most similar studies, especially others within the United Kingdom. Possible factors influencing this are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1991.tb05095.x
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