1,046 research outputs found

    Elastic Differential Cross Sctions for Electron Collisions with Polyatomic Molecules

    Get PDF
    Experimental data for electron-polyatomic molecule collisions are reviewed in connection with fusion and processing plasmas, as well as with the associated environmental issues. The electron scattering experiments for differential cross section (DCS) measurements for various processes, such as elastic scattering, have been performed across a broad range of energies (1-100 eV), mainly, at Sophia University since 1978, and some done under the collaborations with the Australian National University, Flinders University, and the Chungnam National University. As a benchmark cross section, elastic DCS are essential for the absolute scale conversion of inelastic DCS, as well as for testing computational methods. The need for cross-section data for a wide variety of molecular 2 species is also discussed, because there is an urgent need to develop an international program to provide the scientific and technological communities with authoritative cross sections for electron-molecule interactions. Note that the detailed comparison with other data available is not given here. Ruther, other available data can be found in the references we cite. This course of action was adopted to keep this report to a sensible length, so that only our numerical data is provided here

    Cross Sections for Electron-induced Resonant Vibrational Excitations in Polyatomic Molecules

    Get PDF
    We continue our review of experimental data for electron-polyatomic molecule collisions in connection with fusion and processing plasmas, as well as with the associated environmental issues. In this case we focus on vibrational excitation processes, in particular what vibrational modes can be identified in electron energy loss experiments and which of these modes are resonantly enhanced due to the temporary capture of the incident electron by the species in question. In this latter respect we report indicative excitation function data, all of which were originally measured at Sophia University and for which the differential cross section, for excitation of the relevant mode, are studied as a function of the incident electron energy at a fixed scattered electron angle. Unlike our previous compilation (NIFS?DATA?101) for elastic scattering, which was conducted over a broad range of energies (1?100 eV), vibrational excitation cross sections usually only become significant when the resonance enhancement process occurs. As a consequence, this survey encompasses incident electron energies between 1?30 eV. Consistent with our first report, no detailed comparison is made here with any other data that might be available in the literature. This course of action was once again adopted in order to keep this report to a sensible length

    Elementary vortex pinning potential in a chiral p-wave superconductor

    Full text link
    The elementary vortex pinning potential is studied in a chiral p-wave superconductor with a pairing d=z(k_x + i k_y) on the basis of the quasiclassical theory of superconductivity. An analytical investigation and numerical results are presented to show that the vortex pinning potential is dependent on whether the vorticity and chirality are parallel or antiparallel. Mutual cancellation of the vorticity and chirality around a vortex is physically crucial to the effect of the pinning center inside the vortex core.Comment: 4 pages, 4 figures include

    Zonotopes and four-dimensional superconformal field theories

    Get PDF
    The a-maximization technique proposed by Intriligator and Wecht allows us to determine the exact R-charges and scaling dimensions of the chiral operators of four-dimensional superconformal field theories. The problem of existence and uniqueness of the solution, however, has not been addressed in general setting. In this paper, it is shown that the a-function has always a unique critical point which is also a global maximum for a large class of quiver gauge theories specified by toric diagrams. Our proof is based on the observation that the a-function is given by the volume of a three dimensional polytope called "zonotope", and the uniqueness essentially follows from Brunn-Minkowski inequality for the volume of convex bodies. We also show a universal upper bound for the exact R-charges, and the monotonicity of a-function in the sense that a-function decreases whenever the toric diagram shrinks. The relationship between a-maximization and volume-minimization is also discussed.Comment: 29 pages, 15 figures, reference added, typos corrected, version published in JHE

    Field dependence of the vortex structure in chiral p-wave superconductors

    Full text link
    To investigate the different vortex structure between two chiral pairing p_x +(-) i p_y, we calculate the pair potential, the internal field, the local density of states, and free energy in the vortex lattice state based on the quasiclassical Eilenberger theory, and analyze the magnetic field dependence. The induced opposite chiral component of the pair potential plays an important role in the vortex structure. It also produces H^{1/2}-behavior of the zero-energy density of states at higher field. These results are helpful when we understand the vortex states in Sr2RuO4.Comment: 11 pages, 10 figures, to be published in Phys. Rev.

    Transmission-electron-microscopy study of charge-stripe order in La(1.725)Sr(0.275)NiO(4)

    Full text link
    We characterize the local structure and correlations of charge stripes in La(1.725)Sr(0.275)NiO(4) using transmission-electron microscopy. We present direct evidence that the stripe modulation is indeed one-dimensional within each NiO(2) plane. Furthermore, we show that individual stripes tend to be either site-centered or bond-centered, with a bias towards the former. The spacing between stripes often fluctuates about the mean, contributing to a certain degree of frustration of the approximate body-centered stacking along the c-axis. These results confirm ideas inferred from previous neutron-diffraction measurements on doped nickelates, and demonstrate that charge-stripe order is quite different from the conventional concept of charge-density-wave order.Comment: 5 pages, 6 figures, submitted to PR

    Localization on quantum graphs with random vertex couplings

    Full text link
    We consider Schr\"odinger operators on a class of periodic quantum graphs with randomly distributed Kirchhoff coupling constants at all vertices. Using the technique of self-adjoint extensions we obtain conditions for localization on quantum graphs in terms of finite volume criteria for some energy-dependent discrete Hamiltonians. These conditions hold in the strong disorder limit and at the spectral edges

    Detecting new microRNAs in human osteoarthritic chondrocytes identifies miR-3085 as a human, chondrocyte-selective, microRNA

    Get PDF
    Objective: To use deep sequencing to identify novel microRNAs in human osteoarthritic cartilage which have a functional role in chondrocyte phenotype or function. Design: A small RNA library was prepared from human osteoarthritic primary chondrocytes using in-house adaptors and analysed by Illumina sequencing. Novel candidate microRNAs were validated by northern blot and qRT-PCR. Expression was measured in cartilage models. Targets of novel candidates were identified by microarray and computational analysis, validated using 3’-UTR-luciferase reporter plasmids. Protein levels were assessed by western blot and functional analysis by cell adhesion. Results: We identified 990 known microRNAs and 1621 potential novel microRNAs in human osteoarthritic chondrocytes, 60 of the latter were expressed in all samples assayed. MicroRNA-140-3p was the most highly expressed microRNA in osteoarthritic cartilage. Sixteen novel candidate microRNAs were analysed further, of which 6 remained after northern blot analysis. Three novel microRNAs were regulated across models of chondrogenesis, chondrocyte differentiation or cartilage injury. One sequence (novel #11), annotated in rodents as microRNA-3085-3p, was preferentially expressed in cartilage, dependent on chondrocyte differentiation and, in man, is located in an intron of the cartilage-expressed gene CRTAC-1. This microRNA was shown to target the ITGA5 gene directly (which encodes integrin alpha5) and inhibited adhesion to fibronectin (dependent on alpha5beta1 integrin). Conclusion: Deep sequencing has uncovered many potential microRNA candidates expressed in human cartilage. At least three of these show potential functional interest in cartilage homeostasis and osteoarthritis. Particularly, novel #11 (microRNA-3085-3p) which has been identified for the first time in man

    Superconducting Wigner Vortex Molecule near a Magnetic Disk

    Full text link
    Within the non-linear Ginzburg-Landau (GL) theory, we investigate the vortex structure in a superconducting thin film with a ferromagnetic disk on top of it. Antivortices are stabilized in shells around a central core of vortices (or a giant-vortex) with size-magnetization controlled ``magic numbers''. An equilibrium vortex phase diagram is constructed. The transition between the different vortex phases occurs through the creation of a vortex-antivortex pair under the magnetic disk edge.Comment: 4 pages, 4 figures. Submitted to Phys. Rev. Let

    Superconducting zero temperature phase transition in two dimensions and in the magnetic field

    Full text link
    We derive the Ginzburg-Landau-Wilson theory for the superconducting phase transition in two dimensions and in the magnetic field. Without disorder the theory describes a fluctuation induced first-order quantum phase transition into the Abrikosov lattice. We propose a phenomenological criterion for determining the transition field and discuss the qualitative effects of disorder. Comparison with recent experiments on MoGe films is discussed.Comment: 7 pages, 2 figure
    • …
    corecore