Systematic evolution of the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6} in a wide doping range

Recently we have succeeded in growing a series of high-quality Bi_{2}Sr_{2-x}La_{x}CuO_{6} crystals in a wide range of carrier concentrations. The data of \rho_{ab}(T) and R_H(T) of those crystals show behaviors that are considered to be "canonical" to the cuprates. The optimum zero-resistance T_c has been raised to as high as 38 K, which is almost equal to the optimum T_c of La_{2-x}Sr_{x}CuO_{4}.Comment: 2 pages, 2 figures, to be published in Physics C (Proceedings of the International Conference on Materials and Mechanisms of Superconductivity, High Temperature Superconductors VI (M2S-HTSC-VI), Houston, Feb 20-25, 2000

Transport in Bilayer Graphene: Calculations within a self-consistent Born approximation

The transport properties of a bilayer graphene are studied theoretically within a self-consistent Born approximation. The electronic spectrum is composed of $k$-linear dispersion in the low-energy region and $k$-square dispersion as in an ordinary two-dimensional metal at high energy, leading to a crossover between different behaviors in the conductivity on changing the Fermi energy or disorder strengths. We find that the conductivity approaches $2e^2/\pi^2\hbar$ per spin in the strong-disorder regime, independently of the short- or long-range disorder.Comment: 8 pages, 5 figure

Neumann Heat kernel monotonicity

We prove that the diagonal of the transition probabilities for the d-dimensional Bessel processes on (0, 1], reflected at 1, which we denote by $p_R^N(t, r,r)$, is an increasing function of r for d>2 and that this is false for d=2

Rational S^1-equivariant elliptic cohomology

For each elliptic curve A over the rational numbers we construct a 2-periodic S^1-equivariant cohomology theory E whose cohomology ring is the sheaf cohomology of A; the homology of the sphere of the representation z^n is the cohomology of the divisor A(n) of points with order dividing n. The construction proceeds by using the algebraic models of the author's AMS Memoir ``Rational S^1 equivariant homotopy theory.'' and is natural and explicit in terms of sheaves of functions on A. This is Version 5.2 of a paper of long genesis (this should be the final version). The following additional topics were first added in the Fourth Edition: (a) periodicity and differentials treated (b) dependence on coordinate (c) relationship with Grojnowksi's construction and, most importantly, (d) equivalence between a derived category of O_A-modules and a derived category of EA-modules. The Fifth Edition included (e) the Hasse square and (f) explanation of how to calculate maps of EA-module spectra

Double challenges to Japanese farmers : nuclear accident and transpactfic regional partnership = 日本農民的雙重挑戰 : 核危機及太平洋區域的合作關係

For a while after Japan was struck by a major earthquake and tsunami on 11 March this year, gloomy and depressing atmosphere was dominant in Japanese people. As soon as the disaster occurred, corporations refrained from distributing their commercial messages (CMs) on TV. Japanese people are usually exposed by the enormous amount of CMs, but could not but repeatedly watch CMs produced by AC (Advertising Council Japan), a private non-profit agency, during the few weeks. Most of the agency’s CMs are more public than those of other private companies, such as a CM to enhance women’s awareness of breast cancer screening tests. Many Japanese people watched again and again a CM that three Japanese soccer players sent solidarity messages to people who suffered from the earthquake and tsunami. One of them, Uchida Atsuto, a brilliant soccer player who is affiliated with a German club, tried to cheer up Japanese people by saying, “each person should do what he or she can do. Japan is like a team”. He advised his fellow Japanese people to be united (like an organised soccer team) in order to overcome difficulties. The representation of Japanese people as a whole and coherent unit is not new, but it is much more influential in the media after the earthquake and tsunami. I do not intend to deny this kind of nationalism to recover from the disaster. Rather I am just concerned that this representation can lead us to overlooking the unfair relationship between different groups of Japanese people. The list of people who are disadvantaged includes casual workers, people living in Fukushima, and farmers and fisheries. This paper focuses particularly on Japanese farmers who suffer from the nuclear accident. They are also challenged by Transpacific Strategic Economic Partnership Agreement (TPPA), a regional economic partnership agreement, which aims to facilitate trade liberalisation in the Pacific and Asian region

Stripes and Charge Transport Properties of High-T_c Cuprates

Unusual features in the in-plane charge transport in lightly hole-doped La_{2-x}Sr_{x}CuO_{4} single crystals are described. Notably, both the in-plane resistivity and the Hall coefficient show a metallic behavior at moderate temperatures even in the long-range-ordered antiferromagnetic phase, which obviously violates the Mott-Ioffe-Regel criterion for the metallic transport and can hardly be understood without employing the role of charge stripes. Moreover, the mobility of holes in this "metallic" antiferromagnetic state is found to be virtually the same as that in optimally-doped crystals, which strongly suggests that the stripes govern the charge transport in a surprisingly wide doping range up to optimum doping.Comment: Invited paper at ICTP Workshop on Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides, Trieste, July 2002. (To be published in the Proceedings of the ICTP Workshop as a World Scientific book.) Some statements are revised and references are added in response to the comments from theorist friend

Mixed quantal-semiquantal dynamics with stochastic particles for backreaction

A mixed quantal-semiquantal theory is presented in which the semiquantal squeezed-state wave packet describes the heavy degrees of freedom. We first derive mean-field equations of motion from the time-dependent variational principle. Then, in order to take into account the interparticle correlation, in particular the 'quantum backreaction' beyond the mean-field approximation, we introduce the stochastic particle description for both the quantal and semiquantal parts. A numerical application on a model of O2 scattering from a Pt surface demonstrates that the proposed scheme gives correct asymptotic behavior of the scattering probability, with improvement over the mixed quantum-classical scheme with Bohmian particles, which is comprehended by comparing the Bohmian and the stochastic trajectories.Comment: 4 pages, 2 figure