Restructuring's Effect on Related and Unrelated Diversification Among Top Food Manufacturing Firms in the 1980s

Corporate restructuring during the 1980s is argued to have focused on improving firm performance by increasing related and decreasing unrelated diversification. The restructuring patterns of top food manufacturing firms do not support this; instead, much of the restructuring appears to have been driven by the pursuit of stronger market positions. TheAgribusiness, Industrial Organization,

Single crystal growth and physical properties of SrFe2_{2}(As1−x_{1-x}Px_{x})2_{2}

We report a crystal growth and physical properties of SrFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$. The single crystals for various $x$s were grown by a self flux method. For $x = 0.35$, $T_c$ reaches the maximum value of 30\,K and the electrical resistivity $\rho$($T$) shows $T$-linear dependence. As $x$ increases, $T_{c}$ decreases and $\rho$($T$) changes to $T^2$-behavior, indicating a standard Fermi liquid. These results suggest that a magnetic quantum critical point exists around $x=0.35$.Comment: 4 pages, 4 figures, accepted to Supplemental issue of the Journal of Physical Society of Japan (JPSJ

Modeling Magnetic Field Structure of a Solar Active Region Corona using Nonlinear Force-Free Fields in Spherical Geometry

We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases where noisy vector data are provided on only the lower boundary (approximating the solar problem). Analytical tests also show that the NLFFF code in the spherical geometry performs better than that in the Cartesian one when the field of view of the bottom boundary is large, say, $20^\circ \times 20^\circ$. Additionally, We apply the NLFFF model to an active region observed by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) both before and after an M8.7 flare. For each observation time, we initialize the models using potential field source surface (PFSS) extrapolations based on either a synoptic chart or a flux-dispersal model, and compare the resulting NLFFF models. The results show that NLFFF extrapolations using the flux-dispersal model as the boundary condition have slightly lower, therefore better, force-free and divergence-free metrics, and contain larger free magnetic energy. By comparing the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the Atmospheric Imaging Assembly (AIA) on board SDO, we find that the NLFFF performs better than the PFSS not only for the core field of the flare productive region, but also for large EUV loops higher than 50 Mm.Comment: 34 pages, 8 figures, accepted for publication in Ap

Cusp-scaling behavior in fractal dimension of chaotic scattering

A topological bifurcation in chaotic scattering is characterized by a sudden change in the topology of the infinite set of unstable periodic orbits embedded in the underlying chaotic invariant set. We uncover a scaling law for the fractal dimension of the chaotic set for such a bifurcation. Our analysis and numerical computations in both two- and three-degrees-of-freedom systems suggest a striking feature associated with these subtle bifurcations: the dimension typically exhibits a sharp, cusplike local minimum at the bifurcation.Comment: 4 pages, 4 figures, Revte

Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission spectroscopy measurements of the superconducting gap in the Fe-based high-temperature superconductors. We show that the superconducting gap is Fermi surface dependent and nodeless with small anisotropy, or more precisely, a function of momentum. We show that while this observation is inconsistent with weak coupling approaches for superconductivity in these materials, it is well supported by strong coupling models and global superconducting gaps. We also suggest that the strong anisotropies measured by other probes sensitive to the residual density of states are not related to the pairing interaction itself, but rather emerge naturally from the smaller lifetime of the superconducting Cooper pairs that is a direct consequence of the momentum dependent interband scattering inherent to these materials.Comment: 7 pages, 5 figure

Superconducting gap symmetry of Ba0.6K0.4Fe2As2 studied by angle-resolved photoemission spectroscopy

We have performed high-resolution angle-resolved photoemission spectroscopy on the optimally-doped Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ compound and determined the accurate momentum dependence of the superconducting (SC) gap in four Fermi-surface sheets including a newly discovered outer electron pocket at the M point. The SC gap on this pocket is nearly isotropic and its magnitude is comparable ($\Delta$ $\sim$ 11 meV) to that of the inner electron and hole pockets ($\sim$12 meV), although it is substantially larger than that of the outer hole pocket ($\sim$6 meV). The Fermi-surface dependence of the SC gap value is basically consistent with $\Delta$($k$) = $\Delta$$_0$cos$k_x$cos$k_y$ formula expected for the extended s-wave symmetry. The observed finite deviation from the simple formula suggests the importance of multi-orbital effects.Comment: 4 pages, 3 figures, 1 tabl

Dual Ginzburg-Landau Theory for Nonperturbative QCD

Nonperturbative QCD is studied with the dual Ginzburg-Landau theory, where color confinement is realized through the dual Higgs mechanism by QCD-monopole condensation. We obtain a general analytic formula for the string tension. A compact formula is derived for the screened inter-quark potential in the presence of light dynamical quarks. The QCD phase transition at finite temperature is studied using the effective potential formalism. The string tension and the QCD-monopole mass are largely reduced near the critical temperature, $T_c$. The surface tension is estimated from the effective potential at $T_c$. We propose also a new scenario of the quark-gluon-plasma creation through the color-electric flux-tube annihilation. Finally, we discuss a close relation between instantons and QCD-monopoles.Comment: Talk presented by H. Suganuma at the Int. Conf. ``CONFINEMENT95'', March 22-24, 1995, Osaka, Japan, 12 pages, uses PHYZZ