2,415 research outputs found

    Explaining the cosmic ray spectrum feature of Auger beyond the ankle with dip model plus the galactic propagation effect

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    The Auger Collaboration has recently published the energy spectrum of cosmic rays above 1 EeV, which exhibits interesting features. These spectrum features provide an opportunity to investigate the propagation of ultra-high-energy cosmic rays (UHECRs). In this study, we have developed a model that incorporates the dip model for UHECRs in the extragalactic propagation, while accounting for the suppression due to diffusion and interactions within the galaxy. Our model demonstrates excellent agreement with the energy spectrum measured by Auger and supports a spectral index of 2 for the diffusion coefficient in the galaxy starting from 5×10185\times10^{18}eV.Comment: 5 pages, 2 figure

    Improved aerodynamic optimization for the design of wind turbine blades

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    A wind turbine rotor converts the kinetic energy of wind to drive a generator which in turn yields electricity. The aerodynamic analysis and the optimization of design parameters for the wind turbine blades are key techniques in the early stage of the development of wind turbine blades. In this study a computational procedure using artificial neural network and numerical optimization techniques was developed for three-dimensional blades design of a wind turbine. The procedure was applied for improving a previously studied wind turbine rotor design. Results showed that the aerodynamic performance of the new blade has remarkable improvement after optimization

    Multiwavelength Bulge-Disk Decomposition for the Galaxy M81 (NGC 3031). I. Morphology

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    A panchromatic investigation of morphology for the early-type spiral galaxy M81 is presented in this paper. We perform bulge-disk decomposition in M81 images at totally 20 wavebands from FUV to NIR obtained with GALEX, Swift, SDSS, WIYN, 2MASS, WISE, and Spitzer. Morphological parameters such as Sersic index, effective radius, position angle, and axis ratio for the bulge and the disk are thus derived at all the wavebands, which enables quantifying the morphological K-correction for M81 and makes it possible to reproduce images for the bulge and the disk in the galaxy at any waveband. The morphology as a function of wavelength appears as a variable-slope trend of the Sersic index and the effective radius, in which the variations are steep at UV--optical and shallow at optical--NIR bands; the position angle and the axis ratio keep invariable at least at optical--NIR bands. It is worth noting that, the Sersic index for the bulge reaches to about 4--5 at optical and NIR bands, but drops to about 1 at UV bands. This difference brings forward a caveat that, a classical bulge is likely misidentified for a pseudo-bulge or no bulge at high redshifts where galaxies are observed through rest-frame UV channels with optical telescopes. The next work of this series is planned to study spatially resolved SEDs for the bulge and the disk, respectively, and thereby explore stellar population properties and star formation/quenching history for the the galaxy composed of the subsystems.Comment: 48 Pages, 38 Figures, 5 Tables; Accepted for Publication in The Astrophysical Journal Supplement Serie

    Tunable multiband directional electromagnetic scattering from spoof Mie resonant structure

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    We demonstrate that directional electromagnetic scattering can be realized from a artificial Mie resonant strcuture which supports electric and magnetic dipole modes simultaneously. The directivity of the far-field radiation pattern can be switched by changing the incident light wavelength as well as tailoring the geometric parameters of the structure. Particularly, the electric quadrupole at higher frequency contribute significantly to the scattered fields, leading to enhancement of the directionality. In addition, we further design a quasiperiodic spoof Mie resonant structure by alternately inserting two materials into the slits. The results show that multi-band directional light scattering are realized by exciting multiple electric and magnetic dipole modes with different frequencies in the quasiperiodic structure. The presented design concept is general from microwave to terahertz region and can be applied for various advanced optical devices, such as antenna, metamaterial and metsurface.Comment: 10pages,6figure

    Exvivo Experiments of Human Ovarian Cancer Ascites-Derived Exosomes Presented by Dendritic Cells Derived from Umbilical Cord Blood for Immunotherapy Treatment

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    Objectives Exosomes, a type of membrane vesicles, released from tumor cells have been shown to be capable of transferring tumor antigens to dendritic cells and activating specific cytotoxic T-lymphocytes. Recent work has demonstrated the presence of high numbers of exosomes in malignant effusions. Umbilical cord blood (UCB) is a rich source of hematopoietic stem cells and from which a significant number of dendritic cells can be produced. We hypothesized that the exosomes released from metastatic ovarian carcinoma were able to present tumor specific antigen to dendritic cells derived from unrelated umbilical cord blood, then could stimulate resting T cells to differentiate and induce effective cytotoxicity. Study Design Exosomes were isolated by ultracentrifugation of malignant ascites from ovarian cancer patients (n = 10). Purified exosomes were further characterized by Western blot analyses and immunoelectronic microscopy. Dendritic cells were collected from unrelated umbilical cord blood and cultured in the presence of GM-CSF, IL-4 and TNF-α. Resting T cells were mixed with dentritic cells previously primed with exosomes and the cytotoxicity were measured by MTT method. T cells were activated by DCs presented with exosomes. Results 1) the exosomes isolated from the ascites were membrane vesicles of about 30-90nm in diameter; 2) the exosomes expressed MHC class I molecules, HSP70, HSP90, Her2/Neu, and Mart1; and 3)umbilical cord blood-derived DCs previously exosome-primed stimulated resting T cells to differentiate and produce effective cytotoxicity. Conclusions These results suggested that tumor-specific antigens present on exosomes can be presented by DCs derived from unrelated umbilical cord blood to induce tumor specific cytotoxicity and this may represent as a novel immunotherapy for ovarian cancer
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