786 research outputs found

    Mean value coordinates–based caricature and expression synthesis

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    We present a novel method for caricature synthesis based on mean value coordinates (MVC). Our method can be applied to any single frontal face image to learn a specified caricature face pair for frontal and 3D caricature synthesis. This technique only requires one or a small number of exemplar pairs and a natural frontal face image training set, while the system can transfer the style of the exemplar pair across individuals. Further exaggeration can be fulfilled in a controllable way. Our method is further applied to facial expression transfer, interpolation, and exaggeration, which are applications of expression editing. Additionally, we have extended our approach to 3D caricature synthesis based on the 3D version of MVC. With experiments we demonstrate that the transferred expressions are credible and the resulting caricatures can be characterized and recognized

    Contrasting Pressure Effects in Sr2VFeAsO3 and Sr2ScFePO3

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    We report the resistivity measurements under pressure of two Fe-based superconductors with a thick perovskite oxide layer, Sr2VFeAsO3 and Sr2ScFePO3. The superconducting transition temperature Tc of Sr2VFeAsO3 markedly increases with increasing pressure. Its onset value, which was Tc{onset}=36.4 K at ambient pressure, increases to Tc{onset}=46.0 K at ~4 GPa, ensuring the potential of the "21113" system as a high-Tc material. However, the superconductivity of Sr2ScFePO3 is strongly suppressed under pressure. The Tc{onset} of ~16 K decreases to ~5 K at ~4 GPa, and the zero-resistance state is almost lost. We discuss the factor that induces this contrasting pressure effect.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jpn. No.12 (2009

    The Unusual Superconducting State at 49 K in Electron-Doped CaFe2As2 at Ambient

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    We report the detection of unusual superconductivity up to 49 K in single crystalline CaFe2As2 via electron-doping by partial replacement of Ca by rare-earth. The superconducting transition observed suggests the possible existence of two phases: one starting at ~ 49 K, which has a low critical field ~ 4 Oe, and the other at ~ 21 K, with a much higher critical field > 5 T. Our observations are in strong contrast to previous reports of doping or pressurizing layered compounds AeFe2As2 (or Ae122), where Ae = Ca, Sr or Ba. In Ae122, hole-doping has been previously observed to generate superconductivity with a transition temperature (Tc) only up to 38 K and pressurization has been reported to produce superconductivity with a Tc up to 30 K. The unusual 49 K phase detected will be discussed.Comment: 11 pages, 8 figure

    Structural study on hole-doped superconductors Pr1-xSrxFeAsO

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    The structural details in Pr1-xSrxFeAsO (1111) superconducting system are analyzed using data obtained from synchrotron X-ray diffraction and the structural parameters are carefully studied as the system is moving from non-superconducting to hole-doped superconducting with the Sr concentration. Superconductivity emerges when the Sr doping amount reaches 0.221. The linear increase of the lattice constants proves that Sr is successfully introduced into the system and its concentration can accurately be determined by the electron density analyses. The evolution of structural parameters with Sr concentration in Pr1-xSrxFeAsO and their comparison to other similar structural parameters of the related Fe-based superconductors suggest that the interlayer space between the conducting As-Fe-As layer and the insulating Pr-O-Pr layer is important for improving Tc in the hole-doped (1111) superconductors, which seems to be different from electron-doped systems.Comment: 17 pages, 7 figures, 1 tabl

    Evaluation of hydrogeologic properties of the Barbados accretionary prism: a synthesis of Leg 156 results

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    In situ and laboratory studies of permeability, conducted by Ocean Drilling Program scientists from Leg 156, provide constraints on parameters controlling the hydrogeologic system in the Barbados accretionary prism. Results from these studies indicate that core-scale and formation-scale permeability values differ by at least several orders of magnitude and are dependent on pore-fluid pressure and effective stress conditions. Direct measurement from packer experiments and indirect evidence from consolidation tests suggest that pore-fluid pressures are commonly above hydrostatic values and approach lithostatic values within the décollement zone. Permeability and fluid pressure conditions in the Barbados accretionary prism reflect the complexity of the hydrogeologic system of such an active tectonic environment

    Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition

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    Ca(Fe1−x_{1-x}Rhx_x)2_2As2_2 undergoes successive phase transitions with increasing Rh doping in the TT == 0 limit. The antiferromagnetic-metal phase with orthorhombic structure at 0.00 ≤\le xx ≤\le 0.020 is driven to a superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020 ≤\le xx ≤\le 0.024; a non-superconducting collapsed-tetragonal (cT) phase takes over at xx ≥\geq 0.024. The breakdown of Fermi-liquid transport is observed in the ucT phase above TcT_{\rm c}. In the adjacent cT phase, Fermi-liquid transport is restored along with a disappearance of superconductivity. This interplay of superconductivity and Fermi-liquid transport suggests the essential role of magnetic fluctuations in the emergence of superconductivity in doped CaFe2_2As2_2.Comment: 11 pages, 4 figure

    Radio-Continuum study of the Nearby Sculptor Group Galaxies. Part 1: NGC 300 at lambda = 20 cm

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    A series of new radio-continuum (lambda=20 cm) mosaic images focused on the NGC 300 galactic system were produced using archived observational data from the VLA and/or ATCA. These new images are both very sensitive (rms=60 microJy) and feature high angular resolution (<10"). The most prominent new feature is the galaxy's extended radio-continuum emission, which does not match its optical appearance. Using these newly created images a number of previously unidentified discrete sources have been discovered. Furthermore, we demonstrate that a joint deconvolution approach to imaging this complete data-set is inferior when compared to an immerge approach.Comment: 13 pages, 12 figures, accepted to APSS, new version to correct the missing reference

    Determination of the Upper Critical Field of a Single Crystal LiFeAs: The Magnetic Torque Study up to 35 Tesla

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    We report on the upper critical field B_c2 of a superconducting LiFeAs single crystal with T_c~16 K, determined from magnetic torque measurements in dc-magnetic fields up to 35 T and at temperatures down to 0.3 K. B_c2 at 0.3 K is obtained to be 26.4 T and 15.5 T for the applied field B_a||ab and B_a||c, respectively. The anisotropy parameter Γ\Gamma=Bc2ab/Bc2cB_c2^ab / B_c2^c is ~ 3 at T_c and decreases to 1.7 as T→0T \rightarrow 0, showing rather isotropic superconductivity. While B_c2 is orbitally-limited for B_a||c, the spin-paramagnetic effect is evident in the temperature dependence of B_c2 for B_a||abComment: 4 pages, 4 figures, revised version to be published in J. Phys. Soc. Jpn. as a letter articl

    Pressure versus concentration tuning of the superconductivity in Ba(Fe(1-x)Cox)2As2

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    In the iron arsenide compound BaFe2As2, superconductivity can be induced either by a variation of its chemical composition, e.g., by replacing Fe with Co, or by a reduction of the unit-cell volume through the application of hydrostatic pressure p. In contrast to chemical substitutions, pressure is expected to introduce no additional disorder into the lattice. We compare the two routes to superconductivity by measuring the p dependence of the superconducting transition temperature Tc of Ba(Fe(1-x)Cox)2As2 single crystals with different Co content x. We find that Tc(p) of underdoped and overdoped samples increases and decreases, respectively, tracking quantitatively the Tc(x) dependence. To clarify to which extent the superconductivity relies on distinct structural features we analyze the crystal structure as a function of x and compare the results with that of BaFe2As2 under pressure.Comment: 14 pages, 4 figures, to be published in JPSJ Vol. 79 No. 12. The copyright is held by The Physical Society of Japa
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