Luxury and Wealth Accumulation.

This paper develops a model of luxury goods by incorporating weakly non-separable, recursive preferences. In a two-good framework, a quasi-luxury is de ned as a good whose marginal rate of substitution is increasing in wealth. Under certain conditions, it is identical to a luxury good. Consumers wait for quasi-luxuries more (less) patiently than for quasi-necessities when they expect to be happier (unhappier) in the future. The preference for quasi-luxuries promotes optimal wealth accumulation and hence growth. In a two-country economy, the less patient country with stronger quasi-luxury preferences can be wealthier than the more patient country.WEALTH ; WEALTH DISTRIBUTION ; PREFERENCES

Tariffs, Time Preference, and the Current Account under Weakly Nonseparable Preferences.

Incorporating weakly nonseparable preferences into the familiar time-preference model, we emphasize a role of steady-state welfare changes in determining the effect of permanent tariffs on the current account.TARIFFS ; SOCIAL WELFARE ; PREFERENCES

Weakly Nonseparable Preference and the Current Account: Yes, There is a Harberger-Laursen-Metzler Effect.

We examine the current account effect of a terms-of-trade deterioration for a small country model, incorporating weakly nonseparable preference a la Shi (1994) under endogenous time preference.INTERNATIONAL ECONOMY ; CURRENT ACCOUNT

Josephson Vortex States in Intermediate Fields

Motivated by recent resistance data in high $T_c$ superconductors in fields {\it parallel} to the CuO layers, we address two issues on the Josephson-vortex phase diagram, the appearances of structural transitions on the observed first order transition (FOT) curve in intermediate fields and of a lower critical point of the FOT line. It is found that some rotated pinned solids are more stable than the ordinary rhombic pinned solids with vacant interlayer spacings and that, due to the vertical portion in higher fields of the FOT line, the FOT tends to be destroyed by creating a lower critical point.Comment: 12 pages, 3 figures. To appear in J.Phys.Soc.Jpn. 71, No.2 (February, 2002

Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer

We investigated the relationship between tunnel magnetoresistance (TMR) ratio and the crystallization of CoFeB layers through annealing in magnetic tunnel junctions (MTJs) with MgO barriers that had CoFe/Ru/CoFeB synthetic ferrimagnet pinned layers with varying Ru spacer thickness (tRu). The TMR ratio increased with increasing annealing temperature (Ta) and tRu, reaching 361% at Ta = 425C, whereas the TMR ratio of the MTJs with pinned layers without Ru spacers decreased at Ta over 325C. Ruthenium spacers play an important role in forming an (001)-oriented bcc CoFeB pinned layer, resulting in a high TMR ratio through annealing at high temperatures.Comment: 10 pages, 5 figures, submitted to Applied Physics Letter

Time-reversal Characteristics of Quantum Normal Diffusion

This paper concerns with the time-reversal characteristics of intrinsic normal diffusion in quantum systems. Time-reversible properties are quantified by the time-reversal test; the system evolved in the forward direction for a certain period is time-reversed for the same period after applying a small perturbation at the reversal time, and the separation between the time-reversed perturbed and unperturbed states is measured as a function of perturbation strength, which characterizes sensitivity of the time reversed system to the perturbation and is called the time-reversal characteristic. Time-reversal characteristics are investigated for various quantum systems, namely, classically chaotic quantum systems and disordered systems including various stochastic diffusion systems. When the system is normally diffusive, there exists a fundamental quantum unit of perturbation, and all the models exhibit a universal scaling behavior in the time-reversal dynamics as well as in the time-reversal characteristics, which leads us to a basic understanding on the nature of quantum irreversibility.Comment: 21pages, 25figure