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  • 1
    Publication Date: 2015-04-03
    Description: In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells Cell Death and Disease 6, e1711 (April 2015). doi:10.1038/cddis.2015.71 Authors: C Leikam, A L Hufnagel, C Otto, D J Murphy, B Mühling, S Kneitz, I Nanda, M Schmid, T U Wagner, S Haferkamp, E-B Bröcker, M Schartl & S Meierjohann
    Electronic ISSN: 2041-4889
    Topics: Biology , Medicine
    Published by Springer Nature
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  • 2
    Publication Date: 2019
    Description: Abstract Direct measurement of mean vertical velocities in the mesosphere‐lower thermosphere (60–110 km) is not possible due to their small values. Here we derive vertical velocities using the divergence of the mean meridional wind over the Antarctic summer pole using MF radar wind measurements made at Davis Station (69°S, 78°E) between 1994 and 2018. Estimates of vertical velocity are restricted to a 21‐day period centered just after solstice when the equatorward wind reaches its maximum value of about 15 m s−1 at heights near 90 km. The Medium Frequency (MF) radar winds are calibrated against colocated meteor wind radar observations. Neutral densities required for the vertical wind calculations are obtained from zonally averaged temperature measurements obtained by the MLS instrument aboard the AURA satellite. The estimated vertical velocities have peak values varying between 2 and 6 cm s−1 with significant interannual variability. While the peak values do not show significant long‐term change, there is a long‐term decrease in the mean height of maximum winds of about 0.6 km per decade that is statistically significant. The interannual variability is linked to the date of transition in the stratospheric zonal circulation from winter eastward to summer westward flow. Meridional and vertical velocities are smaller and peak at lower altitudes during early transitions (20–30 days prior to solstice) than is the case for late transitions that occur at solstice or later.
    Print ISSN: 2169-897X
    Electronic ISSN: 2169-8996
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
    Publication Date: 2012-03-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, David J -- England -- Nature. 2012 Mar 28;483(7391):541. doi: 10.1038/483541a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22460887" target="_blank"〉PubMed〈/a〉
    Keywords: Environmental Policy/*legislation & jurisprudence ; Fossil Fuels/*economics/*supply & distribution
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-08-12
    Description: The decay times of VHF radar echoes from underdense meteor trails are reduced in the lower portions of the meteor region. This is a result of plasma neutralization initiated by the attachment of positive trail ions to neutral atmospheric molecules. Decreased echo decay times cause meteor radars to produce erroneously high estimates of the ambipolar diffusion coefficient at heights below 90 km, which affects temperature estimation techniques. Comparisons between co-located radars and satellite observations show that meteor radar estimates of diffusion coefficients are not consistent with estimates from the Aura MLS satellite instrument and that co-located radars operating at different frequencies estimate different values of the ambipolar diffusion coefficient for simultaneous detections of the same meteors. Loss of free electrons from meteor trails due to attachment to aerosols and chemical processes were numerically simulated and compared with observations to determine the specific mechanism responsible for low altitude meteor trail plasma neutralization. It is shown that three-body attachment of positive metal ions significantly reduces meteor radar echo decay times at low altitudes compared to the case of diffusion only, that atmospheric ozone plays little part in the evolution of low-altitude underdense meteor trails, and that the effect of three-body attachment begins to exceed diffusion in echo decay times at a constant density surface.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
    Publication Date: 2014-10-21
    Description: Radiosonde observations made from Davis station, Antarctica (68.6°S, 78.0°4 E) between 2001 and 2012 are used to compile a climatology of lower stratosphere inertial gravity wave characteristics. Wavelet analysis extracts single wave packets from the wind and temperature perturbations. Wavelet parameters, combined with linear gravity wave theory, allow for the derivation of a wide range of wave characteristics. Observational filtering associated with this analysis preferentially selects inertial gravity waves with vertical wavelengths less then 2-3 km. The vertical propagation statistics show strong temporal and height variations. The waves propagate close to the horizontal and are strongly advected by the background wind in the wintertime. Notably, around half of the waves observed in the stratosphere above Davis between early May and mid-October propagate downward. This feature is distributed over the observed stratospheric height range. Based on the similarity between the upward and downward propagating waves and on the vertical structure of the non-linear balance residual in the polar winter stratosphere, it is concluded that a source due to imbalanced flow that is distributed across the winter lower-stratosphere best explains the observations. Calculations of kinetic and potential energies and momentum fluxes highlight the potential for variations in results due to different analysis techniques.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2016-04-13
    Description: Author(s): T. Blum, P. A. Boyle, N. H. Christ, J. Frison, N. Garron, R. J. Hudspith, T. Izubuchi, T. Janowski, C. Jung, A. Jüttner, C. Kelly, R. D. Kenway, C. Lehner, M. Marinkovic, R. D. Mawhinney, G. McGlynn, D. J. Murphy, S. Ohta ((太田滋生)), A. Portelli, C. T. Sachrajda, and A. Soni (RBC and UKQCD Collaborations) We present results for several light hadronic quantities ( f π , f K , B K , m u d , m s , t 0 1 / 2 , w 0 ) obtained from simulations of 2 + 1 flavor domain wall lattice QCD with large physical volumes and nearly physical pion masses at two lattice spacings. We perform a short, O ( 3 ) % , extrapolation in pion mass to the … [Phys. Rev. D 93, 074505] Published Tue Apr 12, 2016
    Keywords: Lattice Methods
    Print ISSN: 0556-2821
    Electronic ISSN: 1089-4918
    Topics: Physics
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  • 7
    Publication Date: 2012-04-28
    Description: Wind observations obtained between 1995 and 2011 using the MF radar at Davis have been used to demonstrate the modifying role the quasi-biennial oscillation (QBO) plays on some aspects of interhemispheric coupling identified by previous authors. The response of the meridional wind in the southern summer polar MLT to changes in winter stratospheric planetary wave activity is shown to change sign according to the phase of the QBO. The time delay associated with the coupling is also shown to vary with QBO phase, with an eastward QBO providing a more rapid response. Coupling to the MLT meridional winds is strongest in January. Parts of the mechanism currently proposed have been tested using UKMO assimilated observations. The signatures of some aspects of this mechanism are present in the data. However, some differences to the mechanism are also apparent, in particular the effectiveness of the mechanism near the equator. An explanation for the QBO modulation of the MLT wind response to interhemispheric coupling is proposed on the basis of these differences.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
    Publication Date: 2011-07-13
    Description: Gravity wave activity in the upper stratosphere and lower mesosphere (USLM) is investigated using temperature data retrieved from a Rayleigh lidar at Davis, Antarctica (69°S, 78°E) during the 2007 and 2008 winters. The temporal and height variabilities of waves with ground-based periods greater than 2 h and vertical wavelengths between 4 km and 20 km are analyzed. Stratospheric gravity wave potential energy per unit mass shows a weaker correlation with stratospheric winds at Davis than that reported in the Arctic. Gravity waves dissipate above 40 km during winter, while there is no dissipation in the autumn mesosphere. A separate analysis of gravity waves with ground-based periods of 2–6 h revealed lower dissipation in the winter mesosphere. The seasonal cycle of gravity wave activity is evident throughout the USLM, with peak activity observed during winter. The gravity wave potential energy and vertical wavenumber power spectral density at Davis are similar to that recorded at other high-latitude sites.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Publication Date: 2013-08-13
    Description: Motivation: One of the major challenges for contemporary bioinformatics is the analysis and accurate annotation of genomic datasets to enable extraction of useful information about the functional role of DNA sequences. This article describes a novel genome-wide statistical approach to the detection of specific DNA sequence motifs based on similarities between the promoters of similarly expressed genes. This new tool, cisExpress , is especially designed for use with large datasets, such as those generated by publicly accessible whole genome and transcriptome projects. cisExpress uses a task farming algorithm to exploit all available computational cores within a shared memory node. We demonstrate the robust nature and validity of the proposed method. It is applicable for use with a wide range of genomic databases for any species of interest. Availability: cisExpress is available at www.cisexpress.org . Contact: tatiana.tatarinova@usc.edu Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
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  • 10
    Publication Date: 2017-10-15
    Description: A scanning radiometer deployed at Davis Station, Antarctica (68 ° S, 78 ° E) has been recording infrared (1.10-1.65 μm) images of a small region (24 km × 24 km) of the zenith night sky once per minute each austral winter night since February 1999. These images have been processed to extract information on the passage of gravity waves (GWs) (horizontal wavelength, λ h 〉 15 km) and ripples ( λ h ≤ 15 km) over the observing station. Phase speeds, periods, horizontal wavelengths, and predominant propagation directions have been deduced. Observed speeds were found to be highly correlated with horizontal wavelengths as has been reported in previous studies. Reverse ray-tracing of the detected GWs only enabled us to identify four distinct groups. On average only 15% of waves detected can be traced back to the troposphere, and a large proportion ( ~ 45%) were not successfully reverse traced substantially below the airglow layer. Two smaller groups were found to reach a termination condition for reverse ray-tracing at altitudes near 50 km and 75 km. Of those that reached the termination altitude in the troposphere (10 km), most of the end points fell within a radius of 300 km of the station, with a very pronounced concentration of wave initiation to the north west at approximately of the observing point. The predominant direction of propagation was southward, and they were observed throughout the year. Recent reports suggest the interaction of planetary waves with the background wind field as a potential source for these waves.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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