8,567 research outputs found

    The quiescent progenitors of four Type II-P/L supernovae

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    We present Large Binocular Telescope difference imaging data for the final years of four Type II-P/L supernovae progenitors. For all four, we find no significant evidence for stochastic or steady variability in the U, B, V, or R-bands. Our limits constrain variability to no more than roughly 5-10% of the expected R-band luminosities of the progenitors. These limits are comparable to the observed variability of red supergiants in the Magellanic Clouds. Based on these four events, the probability of a Type II-P/L progenitor having an extended outburst after Oxygen ignition is <37% at 90% confidence. Our observations cannot exclude short outbursts in which the progenitor returns to within ~10% of its quiescent flux on the time scale of months with no dust formation.Comment: 9 pages, 8 figures, 1 table. Accepted to MNRA

    Gas phase polymerization of ethylene with a silica-supported metallocene catalyst: influence of temperature on deactivation

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    Ethylene was polymerized at 5 bar in a stirred powder bed reactor with silica supported rac-Me2Si[Ind]2ZrCl2/methylaluminoxane (MAO) at temperatures between 40°C and 80°C using NaCl as support bed and triethylaluminium (TEA) as a scavenger for impurities. For this fixed recipe and a given charge of catalyst. the average catalyst activity is reproducible within 10% for low temperatures. The polymerization rate and the rate of deactivation increase with increasing temperature. The deactivation could be modeled using a first order dependence with respect to the polymerization rate

    Canada's Strategy of Dispossession: Aboriginal Land and Rights Cessions in Comprehensive Land Claims

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    This paper offers a sociological interpretation of the Canadian Comprehensive Land Claims (CLC) process, arguing that CLC is a strategy used by the state to dispossess Aboriginal peoples. CLC does this through leveraging the cession of Aboriginal rights and the relinquishing of indigenous lands. Drawing upon the ongoing Innu Nation Tshash Petapen (?New Dawn?) agreement, I examine four related aspects of the process and the agreement which operate to dispossess the Innu: (1) the undemocratic social and political contexts in which agreement is elicited, (2) the depletion of Aboriginal rights of the indigenous party, (3) the depletion of indigenous lands, and (4) the creation of wealth and debt. Finally, I will interpret these processes as building on social changes inflicted on the Innu. These are characterized by imposed law and the state of exception

    The interaction of cartoonist's gender and formal features of cartoons

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    The present study investigates gender differences in the use of formal features of cartoons, like the amount of text, the number of panels, or the application of color. For the analysis, 300 cartoons (150 each by female and male cartoonists) were selected randomly from the works of 1519 cartoonists. Twenty-one formal features were analyzed. On average, female cartoonists use more text, include text more frequently, and also draw more panels. These differences were expected, because Differential Psychology has shown for a long time in a variety of cultures that, on average, women tend to perform better in tasks testing verbal intelligence whereas men perform significantly better in tasks that require spatial intelligence. We also found a difference in the type of joke: Women more frequently draw cartoons with incongruity-resolution humor, whereas men prefer to draw cartoons with nonsense humor. The results are discussed in relation to gender differences in humor processing and gender differences in genera

    Total and dissociative photoionization cross sections of N2 from threshold to 107 eV

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    The absolute cross sections for the production of N(+) and N2(+) were measured from the dissociative ionization threshold of 115 A. In addition, the absolute photoabsorption and photoionization cross sections were tabulated between 114 and 796 A. The ionization efficiencies were also given at several discrete wave lengths between 660 and 790 A. The production of N(+) fragment ions are discussed in terms of the doubly excited N2(+) states with binding energies in the range of 24 to 44 eV

    Total photoionization cross sections of atomic oxygen from threshold to 44.3A

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    The relative cross section of atomic oxygen for the production of singly charged ions has been remeasured in more detail and extended to cover the wavelength range 44.3 to 910.5 A by the use of synchrotron radiation. In addition, the contribution of multiple ionization to the cross sections has been measured allowing total photoionization cross sections to be obtained below 250 A. The results have been made absolute by normalization to previously measured data. The use of synchrotron radiation has enabled measurements of the continuum cross section to be made between the numerous autoionizing resonances that occur near the ionization thresholds. This in turn has allowed a more critical comparison of the various theoretical estimates of the cross section to be made. The series of autoionizing resonances leading to the 4-P state of the oxygen ion have been observed for the first time in an ionization type experiment and their positions compared with both theory and previous photographic recordings

    Deterministic creation, pinning, and manipulation of quantized vortices in a Bose-Einstein condensate

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    We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles for the superfluid atomic gas; by controlling the positions of the beams within the plane of the BEC, superfluid flow is deterministically established around each beam such that two vortices of opposite circulation are generated by the motion of the beams, with each vortex pinned to the \emph{in situ} position of a laser beam. We study the vortex creation process, and show that the vortices can be moved about within the BEC by translating the positions of the laser beams. This technique can serve as a building block in future experimental techniques to create, on-demand, deterministic arrangements of few or many vortices within a BEC for precise studies of vortex dynamics and vortex interactions.Comment: 9 pages, 7 figure
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