6d Dirac fermion on a rectangle; scrutinizing boundary conditions, mode functions and spectrum

We classify possible boundary conditions of a 6d Dirac fermion $\Psi$ on a rectangle under the requirement that the 4d Lorentz structure is maintained, and derive the profiles and spectrum of the zero modes and nonzero KK modes under the two specific boundary conditions, (i) 4d-chirality positive components being zero at the boundaries and (ii) 2d-chirality positive components being zero at the boundaries. In the case of (i), twofold degenerated chiral zero modes appear which are localized towards specific directions of the rectangle pointed by an angle parameter $\theta$. This leads to an implication for a new direction of pursuing the origin of three generations in the matter fields of the standard model, even though triple-degenerated zero modes are not realized in the six dimensions. The emergence of the angle parameter $\theta$ originates from a rotational symmetry in the degenerated chiral zero modes on the rectangle extra dimensions since they do not feel the boundaries. In the case of (ii), this rotational symmetry is promoted to the two-dimensional conformal symmetry though no chiral massless zero mode appears. We also discuss the correspondence between our model on a rectangle and orbifold models in some details.Comment: 26 pages, 2 tables (v1); 39 pages, 3 tables, accepted to Nuclear Physics B (v2

Organizational Capabilities of Product Development: International Competitiveness of Japanese Automakers (Japanese)

This paper reports the results of an international comparison of productivity in automotive product development in Japan, the U.S. and Europe. This comparative survey was commenced by Harvard University in 1985. The first survey analyzed data from the 1980s, and detailed results showing the superiority of Japanese manufacturers were published by Fujimoto and Clark (1993). Subsequently data for the 1990s was collected twice, in 1995 and 2000. This paper analyzes the data from the entire 20 year period and reports on key points. The conclusions show that Japan's superior development productivity noted in the 1980s - measured by person-hours and development lead-time - continued until 2000. European and U.S. automakers had difficulty imitating Japanese firms' integrated organizational abilities. One fundamental problem is that the typical project member in Europe and the U.S. is highly specialized, with a narrow range of responsibilities. Since this problem arises from labor market systems, individual firms can do little to change it. This high degree of specialization means larger numbers of people involved in each project, making coordination complicated. Since project managers in Europe and the U.S. are also highly specialized, it is difficult for them to take responsibility for both product development and marketing (product concept) in the way that Japan's heavyweight project managers do.

火災時におけるプレストレストコンクリート部材の爆裂挙動と火災後の耐荷性に関する研究

学位記番号：理工博甲5

Core-Shell Droplet Generation Device Using a Flexural Bolt-Clamped Langevin-Type Ultrasonic Transducer

Droplets with a core-shell structure formed from two immiscible liquids are used in various industrial field owing to their useful physical and chemical characteristics. Efficient generation of uniform core-shell droplets plays an important role in terms of productivity. In this study, monodisperse core-shell droplets were efficiently generated using a flexural bolt-clamped Langevin-type transducer and two micropore plates. Water and silicone oil were used as core and shell phases, respectively, to form core-shell droplets in air. When the applied pressure of the core phase, the applied pressure of the shell phase, and the vibration velocity in the micropore were 200 kPa, 150 kPa, and 8.2 mm/s, respectively, the average diameter and coefficient of variation of the droplets were 207.7 mu m and 1.6%, respectively. A production rate of 29,000 core-shell droplets per second was achieved. This result shows that the developed device is effective for generating monodisperse core-shell droplets