MinK residues line a potassium channel pore.

MinK has neither the P region nor signature sequence that characterizes pore-forming subunits of all known K+ channels. A specific minK region has now been identified that affects external blockade by 2 common probes of K+ channel pores. When mutated to cysteine, residues in this region render minK susceptible to covalent blockade by methanethiosulfonate ethylsulfonate and alter reversible inhibition by tetraethylammonium. The 2 blockers are found to share overlapping binding site determinants and to interact. Since inhibition by external tetraethylammonium is sensitive to voltage and to the internal concentration of permeant ions, we argue that tetraethylammonium blocks by occluding the external end of a water-filled transmembrane pore. These findings support the view that minK is directly involved in forming a K+-selective ion conduction pathway

Anisotropic finite-size scaling analysis of a three-dimensional driven-diffusive system

We study the standard three-dimensional driven diffusive system on a simple cubic lattice where particle jumps along a given lattice direction are biased by an infinitely strong field, while those along other directions follow the usual Kawasaki dynamics. Our goal is to determine which of the several existing theories for critical behavior is valid. We analyze finite-size scaling properties using a range of system shapes and sizes far exceeding previous studies. Four different analytic predictions are tested against the numerical data. Binder and Wang's prediction does not fit the data well. Among the two slightly different versions of Leung, the one including the effects of a dangerous irrelevant variable appears to be better. Recently proposed isotropic finite-size scaling is inconsistent with our data from cubic systems, where systematic deviations are found, especially in scaling at the critical temperature.Comment: 12 pages, 14 PS figures, RevTeX; extensively revise

Privatization, Efficiency Gap, and Subsidization with Excess Taxation Burden

It is well recognized that the impact of subsidization/taxation policies hinges on the market structure to which they apply. We show that different degree of efficiency gain sharply changes the comparisons of optimal subsidy, total outputs and social welfare between mixed and private duopoly. What is more, for an imposition of an optimal subsidy, welfare may increase, decrease, or remain unchanged with privatization, which depends on the level of the cost efficiency gap and the taxation burden. However, it may be possible to raise welfare through privatization as long as the efficiency gain prevails or no excess taxation burden exists. Government sets higher subsidy to stimulate firms' production if the value of cost-differential is assured.Privatization, Mixed Duopoly, Cost Efficiency Gap, Subsidization, Excess Taxation Burden

Trade liberalization and environmental tax in differentiated oligopoly with consumption externalities

This paper investigates the environment tax and trade liberalization with different market structures (pure oligopoly or mixed oligopoly) juxtaposing the substitutability of the goods (homogenous goods and differentiated goods), wherein environmental damage is associated with consumption. It shows that the environmental tax in mixed oligopoly is higher than in pure oligopoly irrespective of the properties of goods. In addition, it demonstrates that when the domestic market increases its openings, the tariff reduction does not always bring positive effects on the environment in mixed oligopoly but, in pure oligopoly with homogeneous goods, the tariff reduction is bad for the environment.