2,040 research outputs found

    Single-Document and Multi-Document Summarization Techniques for Email Threads Using Sentence Compression First Author Affiliation / Address line 1

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    We present two approaches to email thread summarization: Collective Message Summarization (CMS) applies a multi-document summarization approach, while Individual Message Summarization (IMS) treats the problem as a sequence of single-document summarization tasks. Both approaches are implemented in our general framework driven by sentence compression. Instead of a purely extractive approach, we employ linguistic and statistical methods to generate multiple compressions, and then select from those candidates to produce a final summary. We demonstrate our techniques on the Enron collection—a very challenging corpus because of the highly technical language. Results suggest that CMS represents a better approach and additional findings pave the way for future explorations.

    Spiralling dynamics near heteroclinic networks

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    There are few explicit examples in the literature of vector fields exhibiting complex dynamics that may be proved analytically. We construct explicitly a {two parameter family of vector fields} on the three-dimensional sphere \EU^3, whose flow has a spiralling attractor containing the following: two hyperbolic equilibria, heteroclinic trajectories connecting them {transversely} and a non-trivial hyperbolic, invariant and transitive set. The spiralling set unfolds a heteroclinic network between two symmetric saddle-foci and contains a sequence of topological horseshoes semiconjugate to full shifts over an alphabet with more and more symbols, {coexisting with Newhouse phenonema}. The vector field is the restriction to \EU^3 of a polynomial vector field in \RR^4. In this article, we also identify global bifurcations that induce chaotic dynamics of different types.Comment: change in one figur

    Magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO: first-principles calculations

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    The electronic structure and magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO have been investigated using first-principles methods. We show that the magnetic coupling between Gd or Nd ions in the nearest neighbor sites is ferromagnetic. The stability of the ferromagnetic coupling between Gd ions can be enhanced by appropriate electron doping into ZnO:Gd system and the room-temperature ferromagnetism can be achieved. However, for ZnO:Nd system, the ferromagnetism between Nd ions can be enhanced by appropriate holes doping into the sample. The room-temperature ferromagnetism can also be achieved in the \emph{n}-conducting ZnO:Nd sample. Our calculated results are in good agreement with the conclusions of the recent experiments. The effect of native defects (VZn_{\rm{Zn}}, VO_{\rm{O}}) on the ferromagnetism is also discussed.Comment: 5 pages, 5 figure

    Superconductivity in iron telluride thin films under tensile stress

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    By realizing in thin films a tensile stress state, superconductivity of 13 K was introduced into FeTe, an non-superconducting parent compound of the iron pnictides and chalcogenides, with transition temperature higher than that of its superconducting isostructural counterpart FeSe. For these tensile stressed films, the superconductivity is accompanied by the softening of the first-order magnetic and structural phase transition; and also, the in-plane extension and out-of-plane contraction are universal in all FeTe films independent of sign of lattice mismatch, either positive or negative. Moreover, the correlations were found exist between the transition temperatures and the tetrahedra bond angles in these thin films.Comment: 4 pages, 4 figures, accepted by Physical Review Letter

    Kinesin-II is required for axonal transport of choline acetyltransferase in Drosophila

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    KLP64D and KLP68D are members of the kinesin-II family of proteins in Drosophila. Immunostaining for KLP68D and ribonucleic acid in situ hybridization for KLP64D demonstrated their preferential expression in cholinergic neurons. KLP68D was also found to accumulate in cholinergic neurons in axonal obstructions caused by the loss of kinesin light chain. Mutations in the KLP64D gene cause uncoordinated sluggish movement and death, and reduce transport of choline acetyltransferase from cell bodies to the synapse. The inviability of KLP64D mutations can be rescued by expression of mammalian KIF3A. Together, these data suggest that kinesin-II is required for the axonal transport of a soluble enzyme, choline acetyltransferase. in a specific subset of neurons in Drosophila. Furthermore, the data lead to the conclusion that the cargo transport requirements of different classes of neurons may lead to upregulation of specific pathways of axonal transport

    Spin Hall effect in the kagome lattice with Rashba spin-orbit interaction

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    We study the spin Hall effect in the kagom\'{e} lattice with Rashba spin-orbit coupling. The conserved spin Hall conductance σxys\sigma_{xy}^{s} (see text) and its two components, i.e., the conventional term σxys0\sigma_{xy}^{s0} and the spin-torque-dipole term σxysτ\sigma_{xy}^{s\tau}, are numerically calculated, which show a series of plateaus as a function of the electron Fermi energy ϵF\epsilon_{F}. A consistent two-band analysis, as well as a Berry-phase interpretation, is also given. We show that these plateaus are a consequence of the various Fermi-surface topologies when tuning ϵF\epsilon_{F}. In particular, we predict that compared to the case with the Fermi surface encircling the Γ\mathbf{\Gamma} point in the Brillouin zone, the amplitude of the spin Hall conductance with the Fermi surface encircling the K\mathbf{K} points is twice enhanced, which makes it highly meaningful in the future to systematically carry out studies of the K\mathbf{K}-valley spintronics.Comment: 7 pages, 3 figures. Phys. Rev. B (in press
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