Origin of superconducting carriers in "non-doped" T'- (La,RE)2CuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y) prepared by molecular beam epitaxy

We have performed a systematic investigation of the variations of the lattice constants with substituent rare-earth element concentration x in the nominally undoped superconductors T'-(La3+)2-x(RE3+)xCuO4 (RE = Sm, Eu, Gd, Tb, Lu, and Y), which we have recently discovered using MBE. The results show both the in-plane and out-of-plane lattice constants (a0 and c0) linearly decrease with x, whose extrapolation to x = 2 agrees well with the reported a0 and c0 values for each T'-RE2CuO4. This behavior is what one would expect simply from the ionic size difference between La3+ and RE3+. The absence of the Cu-O bond stretching due to electron-doping, which is commonly observed in electron-doped T' and infinite-layer superconductors, implies that electron doping via oxygen deficiencies is, at least, not a main source of charge carriers.Comment: proceedings of ISS 200

Ce doping in T-La2CuO4 films: Broken electron-hole symmetry for high-Tc superconductivity

We attempted Ce doping in La2CuO4 with the K2NiF4 (T) structure by molecular beam epitaxy. At low growth temperature and with an appropriate substrate choice, we found that Ce can be incorporated into the K2NiF4 lattice up to x ~ 0.06, which had not yet been realized in bulk synthesis. The doping of Ce makes T-La2-xCexCuO4 more insulating, which is in sharp contrast to Ce doping in La2CuO4 with the Nd2CuO4 structure, which makes the compounds superconducting. The observed smooth increase in resistivity from hole-doped side (T-La2-xSrxCuO4) to electron-doped side (T-La2-xCexCuO4) indicates that electron-hole symmetry is broken in the T-phase materials.Comment: proceedings of ISS 200

String operations on rational Gorenstein spaces

F\'{e}lix and Thomas developed string topology of Chas and Sullivan on simply-connected Gorenstein spaces. In this paper, we prove that the degree shifted homology of the free loop space of a simply-connected ${\mathbb Q}$-Gorenstein space with rational coefficient is a non-unital and non-counital Frobenius algebra by solving the up to constant problem. We also investigate triviality or non-triviality of the loop product and coproduct of particular Gorenstein spaces.Comment: 27page

Construction of Negatively Curved Cubic Carbon Crystals via Standard Realizations

We constructed physically stable sp2 negatively curved cubic carbon structures which reticulate a Schwarz P-like surface. The method for constructing such crystal structures is based on the notion of the standard realization of abstract crystal lattices. In this paper, we expound on the mathematical method to construct such crystal structures

AN EMPIRICAL STUDY OF COMMON PROPERTY RESOURCE: THE CASE OF SKIPJACK FISHERY IN THE WESTERN-CENTRAL PACIFIC OCEAN

A dynamic Cournot game model is used to predict the strategic behavior of harvesters engaged in a non-cooperative fishery on a common property resource. The model predicts that an increase in the current number of harvesters in a common property fishery will reduce both the equilibrium harvest level and the current resource rent for the individual harvester. Also, an increase in the future number of harvesters increases both two equilibrium levels. These predictions are tested using data from the Japanese skipjack fishery in the Western-central Pacific Ocean. The empirical results on the effect of changes in the current and future numbers of harvesters on the individual harvest rates and resource rent are consistent with theory.Resource /Energy Economics and Policy,

Atkinson and Stiglitz Theorem with Endogenous Human Capital Accumulation

Recently, several papers have re-examined the so called production efficiency theorem and the Atkinson and Stiglitz theorem on commodity taxes in the optimal taxation literature. Naito (1998) showed that indirect redistribution through production distortion or consumption distortion can Pareto-improve welfare and that the two theorems do not necessarily hold when different factors are imperfect substitutes and factor prices are endogenous. On the other hand, Saez (2001) argued that in the long run where human capital accumulation is endogenous, the two theorems are still valid. This paper points out that the result of Saez (2003) depends on the assumption on the dimension of the type of human capital. This paper shows that if different people have different comparative advantage in accumulating different types of human capital, the Atkinson and Stiglitz theorem does not hold.

Optimal Nonlinear Income and Inheritance Taxation in an Infinite Horizon Model with Quasi-linear Preference

This paper analyzes optimal nonlinear income and inheritance taxation by incorporating two types of models that were developed independently in the public finance literature: an infinite horizon representative agent model such as Judd (1995), Chamley (1986) and Lucas (1992), and asymmetric information model analyzed by Mirrlees (1971) and Stiglitz (1982). In this paper, by using an infinite horizon model with heterogenous agents and quasi-linear preference under an asymmetric information environment we characterize optimal income and inheritance taxation. This paper shows that, contrary to the general perception that inheritance taxation should be progressive to some extent, the expected tax liability of those who have a higher level of assets is lower than the expected tax liability of those who have a lower level of assets. Thus, the optimal inheritance tax is regressive.