The E6E_6 state sum invariant of lens spaces

In this paper, we calculate the values of the $E_6$ state sum invariants for the lens spaces $L(p,q)$. In particular, we show that the values of the invariants are determined by $p \mod 12$ and $q \mod (p,12)$. As a corollary, we show that the $E_6$ state sum is a homotopy invariant for the oriented lens spaces.Comment: 6 pages, 0 figure

Membrane Quantum Mechanics

We consider the multiple M2-branes wrapped on a compact Riemann surface and study the arising quantum mechanics by taking the limit where the size of the Riemann surface goes to zero. The IR quantum mechanical models resulting from the BLG-model and the ABJM-model compactified on a torus are N = 16 and N = 12 superconformal gauged quantum mechanics. After integrating out the auxiliary gauge fields we find OSp(16|2) and SU(1,1|6) quantum mechanics from the reduced systems. The curved Riemann surface is taken as a holomorphic curve in a Calabi-Yau space to preserve supersymmetry and we present a prescription of the topological twisting. We find the N = 8 superconformal gauged quantum mechanics that may describe the motion of two wrapped M2-branes in a K3 surface.Comment: 54 pages, v2: errors corrected and notations improve

Holding Company and Bank: An Historical Comparative Perspective on Corporate Governance in Japan, subsequently published in "Seoul Journal of Economics", 2004, vol.17-3. )

In this paper I describe the outline of the historical evolution of corporate governance in Japan, and intend to derive some insights on its future. While two alternative systems, the holding company-based system and the bank-based system were available in the 1920s, the former started to proliferate. However, the experiences during the Second World War made the corporate system choose the other fork in the road, the bank-based system. The changes in employment system and production management were complementary with the changes in corporate governance and finance. The Japanese corporate system, which was faced with a bifurcation in the 1920s and the 1930s, is now facing another bifurcation.

"Ownership Changes and Economic Efficiency: Plant-Level Evidence from the Japanese Cotton Spinning Industry, 1900-1911"

This paper investigates how ownership changes affect the plant performance, focusing on the cotton spinning industry in early twentieth century Japan, where many plants experienced ownership changes. Through analyses of detailed plant-level data, it is revealed that, after ownership changes, plants tended to focus on low grade and low price products and, at the same time, total factor productivity, machine productivity and profitability of the plants significantly increased. These results indicate that the plants were managed and utilized more efficiently under the new ownership.

"Supplier Networks and Aircraft Production in Wartime Japan"

The Japanese aircraft industry, which operated on a very small scale before World War II, became Japan's largest manufacturing industry by the end of the war. In this paper, we explore the causes of the growth of the aircraft industry during this time by focusing on the No. 5 Works of Mitsubishi Heavy Industries Co. We find that during the war, the supply of basic inputs increased substantially: the labor force, equipment and "machinery parts" were in sufficient supply, and none of them were binding constraints on production. A binding constraint existed in the supply of "special parts." Put differently, aircraft production expanded as the supply of special parts increased. This increase in the supply of special parts and even faster growth in the supply of machinery parts came about through the expansion of supplier networks in terms of both the number of suppliers and the geographical area in which they were located. These findings imply that outsourcing played a key role in the rise of aircraft production in wartime Japan.

"Industrial Development, Firm Dynamics and Patterns of Productivity Growth: The Case of the Cotton Spinning Industry in Prewar Japan, 1894-1924"

This paper explores the relationship between patterns of productivity growth and the development stage of an industry, using firm-level data on the cotton spinning industry in Japan in the late nineteenth century. It is found that patterns of productivity growth depend on the development stage of the industry. In the earlier stage of industrial development, productivity growth of each firm, namely the within effect, was the sole major source of aggregate productivity growth. On the other hand, once the industry had matured, resource reallocation across firms became a major source of aggregate productivity growth, along with the within effect. This relationship between patterns of productivity growth and the development stage of an industry is considered to reflect the stage-dependent patterns of innovation and competition.

"The Role of the Merchant Coalition in Pre-modern Japanese Economic Development: An Historical Institutional Analysis"

This paper examines the economic role of the merchant coalition (kabu nakama) in Japan during the the eighteenth and the first half of the nineteenth century in Japan. During this period public sector enforcement of contracts was imperfect. Kabu nakama substituted for the public sector, using a multilateral punishment strategy. When the government (Bakufu) prohibited kabu nakama in 1841, the growth rate of the real money supply contracted, efficiency of price arbitrage declined, and the inflation rate increased.