569 research outputs found
A New Method for Measuring Tail Exponents of Firm Size Distributions
We propose a new method for estimating the power-law exponents of firm size variables. Our focus is on how to empirically identify a range in which a firm size variable follows a power-law distribution. As is well known, a firm size variable follows a power-law distribution only beyond some threshold. On the other hand, in almost all empirical exercises, the right end part of a distribution deviates from a power-law due to finite size effect. We modify the method proposed by Malevergne et al. (2011) so that we can identify both of the lower and the upper thresholds and then estimate the power-law exponent using observations only in the range defined by the two thresholds. We apply this new method to various firm size variables, including annual sales, the number of workers, and tangible fixed assets for firms in more than thirty countries.Econophysics, power-law distributions, power-law exponents, firm size variables, finite size effect
Weak-Coupling Approach to Hole-Doped S=1 Haldane Systems
As a weak-coupling analogue of hole-doped Haldane systems, we study two
models for coupled chains via Hund coupling; coupled Hubbard chains, and a
Hubbard chain coupled with an Heisenberg chain. The fixed point
properties of these models are investigated by using bosonization and
renormalization group methods. The effect of randomness on these fixed points
is also studied. It is found that the presence of the disorder parameter
inherent in the Haldane state in the former model suppresses the Anderson
localization for weak randomness, and stabilizes the Tomonaga-Luttinger liquid
state with the spin gap.Comment: 4 pages, RevTex, 1 postscript figure (uuencoded and compressed), to
appear in Phys. Rev.
Theory of Fulde-Ferrell-Larkin-Ovchinnikov state of superconductors with and without inversion symmetry: Hubbard model approach
We study Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of superconductors
with and without inversion symmetry based on the Hubbard model on the square
lattice near half-filling, using the random phase approximation. We show that
center of mass momentum tends to be parallel to - or y-axis in the
presence of inversion symmetry, while vector is likely to be perpendicular
to the magnetic field in the absence of inversion symmetry. We also clarify
that -wave pairing is favored and the hetero spin triplet -wave state
is present in the FFLO state unlike state in the superconductors only with the
Rashba type spin-orbit coupling (RSOC) originating from the broken inversion
symmetry. The triplet -wave state is enhanced by magnetic field and the
RSOC. This stems from the reduction of the spin susceptibilities by the
magnetic field and the RSOC.Comment: 9 pages, 15 figures, 1 tabl
Production in Two-Photon Processes at TRISTAN
We have carried out an inclusive measurement of production
in two-photon processes at TRISTAN. The mean was 58 GeV and the
integrated luminosity was 199 pb. High-statistics samples were
obtained under such conditions as no-, anti-electron, and remnant-jet tags. The
remnant-jet tag, in particular, allowed us, for the first time, to measure the
cross sections separately for the resolved-photon and direct processes.Comment: 20 pages, Latex format, 4 figures and KEK-mark included. Table 1
revised. To be published in Phys. Lett.
Measurement of inclusive electron cross section in collisions at TRISTAN
We have studied open charm production in collisions with the
TOPAZ detector at the TRISTAN collider. In this study, charm
quarks were identified by electrons (and positrons) from semi-leptonic decays
of charmed hadrons. The data corresponded to an integrated luminosity of 95.3
pb at a center-of-mass energy of 58 GeV. The results are presented as
the cross sections of inclusive electron production in
collisions with an anti-tag condition, as well as the subprocess cross
sections, which correspond to resolved-photon processes. The latter were
measured by using a sub-sample with remnant jets. A comparison with various
theoretical predictions based on direct and resolved-photon processes showed
that our data prefer that with relatively large gluon contents in a photon at
small , with the next-to-leading order correction, and with a
charm-quark mass of 1.3 GeV.Comment: 26 pages, Latex format (article), 5 figures included, to be published
in Phys. Lett.
Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at =58GeV with electron tagging
We have measured, with electron tagging, the forward-backward asymmetries of
charm- and bottom-quark pair productions at =58.01GeV, based on
23,783 hadronic events selected from a data sample of 197pb taken with
the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are
and , which are consistent with the standard model
predictions.Comment: 19 pages, Latex format (article), 5 figures included. to be published
in Phys. Lett.
Chiral Anomaly and Spin Gap in One-Dimensional Interacting Fermions
Semiclassical approach has been developed for the one-dimensional interacting
fermion systems. Starting from the incommensurate spin density wave (SDW) mean
field state for the repulsive Hubbard model in 1D, the non-Abelian bosonized
Lagrangian describing the spin-charge separation is obtained. The Berry phase
term is derived from the chiral anomaly, and we obtain the massless
Tomonaga-Luttinger liquid in the single chain case while the spin gap opens in
the double-chain system. This approach offers a new method to identify the
strong-coupling fixed point, and its relation to the Abelian bosonization
formalism is discussed on the spin gap state. The generalization to higher
dimensions is also discussed.Comment: Revised and enlarged version. 16 pages in REVTE
A Measurement of the Cross Section in Two-Photon Processes
We have measured the inclusive production cross section in a
two-photon collision at the TRISTAN collider. The mean of
the collider was 57.16 GeV and the integrated luminosity was 150 . The
differential cross section () was obtained in the
range between 1.6 and 6.6 GeV and compared with theoretical predictions, such
as those involving direct and resolved photon processes.Comment: 8 pages, Latex format (article), figures corrected, published in
Phys. Rev. D 50 (1994) 187
Measurement of the cross-section and forward-backward charge asymmetry for the b and c-quark in e+e- annihilation with inclusive muons at sqrt(s) = 58 GeV
We have studied inclusive muon events using all the data collected by the
TOPAZ detector at sqrt(s)=58 GeV with an integrated luminosity of 273pb-1. From
1328 inclusive muon events, we measured the ratio R_qq of the cross section for
qq-bar production to the total hadronic cross section and forward-backward
asymmetry A^q_FB for b and c quarks. The obtained results are R_bb =
0.13+-0.02(stat)+-0.01(syst), R_cc = 0.36+-0.05(stat)+-0.05(syst), A^b_FB =
-0.20+-0.16(stat)+-0.01(syst) and A^c_FB = -0.17+-0.14(stat)+-0.02(syst), in
fair agreement with a prediction of the standard model.Comment: To be published in EPJ C. 24 pages, 12 figure
Intravenous immunoglobulin contributes to the control of antimelanoma differentiation-associated protein 5 antibody-associated dermatomyositis with palmar violaceous macules/papules
Autoantibodies to melanoma differentiation-associated protein 5 (MDA5) are associated with a subset of patients with dermatomyositis (DM) who have rapidly progressive interstitial lung disease (RP-ILD) with poor prognosis. Intensive immunosuppressive therapy is initiated before irreversible lung damage can occur; however, there are few lines of evidence for the treatment of RP-ILD. Here, we report three cases of anti-MDA5 antibody-associated DM with RP-ILD in which the patients were treated with combined-modality therapy, including high-dose prednisolone, tacrolimus, intravenous cyclophosphamide and intravenous immunoglobulin (IVIG). In all three cases, serum ferritin levels, which are known to represent the disease activity of RP-ILD, were decreased after IVIG administration. IVIG might contribute to the control of the disease activity of anti-MDA5 antibody-positive DM. Moreover, palmar violaceous macules/papules around the interphalangeal joints, which was observed in all three cases in the incipient stage, might be a useful sign in suggesting a diagnosis of anti-MDA5 antibody-associated DM
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