277 research outputs found

    Electrohydrodynamically patterned colloidal crystals

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    A method for assembling patterned crystalline arrays of colloidal particles using ultraviolet illumination of an optically-sensitive semiconducting anode while using the anode to apply an electronic field to the colloidal particles. The ultraviolet illumination increases current density, and consequently, the flow of the colloidal particles. As a result, colloidal particles can be caused to migrate from non-illuminated areas of the anode to illuminated areas of the anode. Selective illumination of the anode can also be used to permanently affix colloidal crystals to illuminated areas of the anode while not affixing them to non-illuminated areas of the anode

    Error resilient layered stereoscopic video streaming

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    In this paper, error resilient stereoscopic video streaming problem is addressed. Two different Forward Error Correction (FEC) codes namely Systematic LT and RS codes are utilized to protect the stereoscopic video data against transmission errors. Initially, the stereoscopic video is categorized in 3 layers with different priorities. Then, a packetization scheme is used to increase the efficiency of error protection. A comparative analysis of RS and LT codes are provided via simulations to observe the optimum packetization and UEP strategies

    Rate-distortion optimized layered stereoscopic video streaming with raptor codes

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    A near optimal streaming system for stereoscopic video is proposed. Initially, the stereoscopic video is separated into three layers and the approximate analytical model of the Rate-Distortion (RD) curve of each layer is calculated from sufficient number of rate and distortion samples. The analytical modeling includes the interdependency of the defined layers. Then, the analytical models are used to derive the optimal source encoding rates for a given channel bandwidth. The distortion in the quality of the stereoscopic video that is caused by losing a NAL unit from the defined layers is estimated to minimize the average distortion of a single NAL unit loss. The minimization is performed over protection rates allocated to each layer. Raptor codes are utilized as the error protection scheme due to their novelty and suitability in video transmission. The layers are protected unequally using Raptor codes according to the parity ratios allocated to the layers. Comparison of the defined scheme with two other protection allocation schemes is provided via simulations to observe the quality of stereoscopic video. ©2007 IEEE

    Personalized copy number and segmental duplication maps using next-generation sequencing

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    Despite their importance in gene innovation and phenotypic variation, duplicated regions have remained largely intractable owing to difficulties in accurately resolving their structure, copy number and sequence content. We present an algorithm (mrFAST) to comprehensively map next-generation sequence reads, which allows for the prediction of absolute copy-number variation of duplicated segments and genes. We examine three human genomes and experimentally validate genome-wide copy number differences. We estimate that, on average, 73-87 genes vary in copy number between any two individuals and find that these genic differences overwhelmingly correspond to segmental duplications (odds ratio = 135; P < 2.2 x 10(-16)). Our method can distinguish between different copies of highly identical genes, providing a more accurate assessment of gene content and insight into functional constraint without the limitations of array-based technology

    High energy spin excitations in YBa_2 Cu_3 O_{6.5}

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    Inelastic neutron scattering has been used to obtain a comprehensive description of the absolute dynamical spin susceptibility χâ€Čâ€Č(q,ω)\chi'' (q,\omega) of the underdoped superconducting cuprate YBa_2 Cu_3 O_{6.5} (Tc=52KT_c = 52 K) over a wide range of energies and temperatures (2meV≀ℏω≀120meV2 meV \leq \hbar \omega \leq 120 meV and 5K≀T≀200K5K \leq T \leq 200K). Spin excitations of two different symmetries (even and odd under exchange of two adjacent CuO_2 layers) are observed which, surprisingly, are characterized by different temperature dependences. The excitations show dispersive behavior at high energies.Comment: 15 pages, 5 figure

    Fe-substituted mullite powders for the in situ synthesis of carbon nanotubes by catalytic chemical vapor deposition

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    Powders of iron-substituted mullite were prepared by combustion and further calcination in air at different temperatures. A detailed study involving notably Mošssbauer spectroscopy showed that the Fe3+ ions are distributed between the mullite phase and a corundum phase that progressively dissolves into mullite upon the increase in calcination temperature. Carbon nanotube-Fe-mullite nanocomposites were prepared for the first time by a direct method involving a reduction of these powders in H2-CH4 and without any mechanical mixing step. The carbon nanotubes formed by the catalytic decomposition of CH4 on the smallest metal particles are mostly double-walled and multiwalled, although some carbon nanofibers are also observed

    Effect of Nonmagnetic Impurities on the Magnetic Resonance Peak in YBa2Cu3O7

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    The magnetic excitation spectrum of a YBa_2 Cu_3 O_7 crystal containing 0.5% of nonmagnetic (Zn) impurities has been determined by inelastic neutron scattering. Whereas in the pure system a sharp resonance peak at E ~ 40 meV is observed exclusively below the superconducting transition temperature T_c, the magnetic response in the Zn-substituted system is broadened significantly and vanishes at a temperature much higher than T_c. The energy-integrated spectral weight observed near q = (pi,pi) increases with Zn substitution, and only about half of the spectral weight is removed at T_c

    İzmir‐Ankara suture as a Triassic to Cretaceous plate boundary – data from central Anatolia

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    The Ä°zmir‐Ankara suture represents part of the boundary between Laurasia and Gondwana along which a wide Tethyan ocean was subducted. In northwest Turkey, it is associated with distinct oceanic subduction‐accretion complexes of Late Triassic, Jurassic and Late Cretaceous ages. The Late Triassic and Jurassic accretion complexes consist predominantly of basalt with lesser amounts of shale, limestone, chert, Permian (274 Ma zircon U‐Pb age) metagabbro and serpentinite, which have undergone greenschist facies metamorphism. Ar‐Ar muscovite ages from the phyllites range from 210 Ma down to 145 Ma with a broad southward younging. The Late Cretaceous subduction‐accretion complex, the ophiolitic mĂ©lange, consists of basalt, radiolarian chert, shale and minor amounts of recrystallized limestone, serpentinite and greywacke, showing various degrees of blueschist facies metamorphism and penetrative deformation. Ar‐Ar phengite ages from two blueschist metabasites are ca. 80 Ma (Campanian). The ophiolitic mĂ©lange includes large Jurassic peridotite‐gabbro bodies with plagiogranites with ca. 180 Ma U‐Pb zircon ages. Geochronological and geological data show that Permian to Cretaceous oceanic lithosphere was subducted north under the Pontides from the Late Triassic to the Late Cretaceous. This period was characterized generally by subduction‐accretion, except in the Early Cretaceous, when subduction‐erosion took place. In the Sakarya segment all the subduction accretion complexes, as well as the adjacent continental sequences, are unconformably overlain by Lower Eocene red beds. This, along with the stratigraphy of the Sakarya Zone indicate that the hard collision between the Sakarya Zone and the Anatolide‐Tauride Block took place in Paleocene

    Spin Susceptibility in Underdoped YBa2Cu3O6+x\bf YBa_2Cu_3O_{6+x}

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    We report a comprehensive polarized and unpolarized neutron scattering study of the evolution of the dynamical spin susceptibility with temperature and doping in three underdoped single crystals of the \YBCO{6+x} high temperature superconductor: \YBCO{6.5} (Tc = 52 K), \YBCO{6.7} (Tc = 67 K), and \YBCO{6.85} (T_c = 87 K). Theoretical implications of these data are discussed, and a critique of recent attempts to relate the spin excitations to the thermodynamics of high temperature superconductors is given.Comment: minor revisions, to appear in PR
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