Existence of an infinite particle limit of stochastic ranking process

We study a stochastic particle system which models the time evolution of the ranking of books by online bookstores (e.g., Amazon). In this system, particles are lined in a queue. Each particle jumps at random jump times to the top of the queue, and otherwise stays in the queue, being pushed toward the tail every time another particle jumps to the top. In an infinite particle limit, the random motion of each particle between its jumps converges to a deterministic trajectory. (This trajectory is actually observed in the ranking data on web sites.) We prove that the (random) empirical distribution of this particle system converges to a deterministic space-time dependent distribution. A core of the proof is the law of large numbers for {\it dependent} random variables

Stochastic ranking process with time dependent intensities

We consider the stochastic ranking process with the jump times of the particles determined by Poisson random measures. We prove that the joint empirical distribution of scaled position and intensity measure converges almost surely in the infinite particle limit. We give an explicit formula for the limit distribution and show that the limit distribution function is a unique global classical solution to an initial value problem for a system of a first order non-linear partial differential equations with time dependent coefficients

Restoration of isotropy on fractals

We report a new type of restoration of macroscopic isotropy (homogenization) in fractals with microscopic anisotropy. The phenomenon is observed in various physical setups, including diffusions, random walks, resistor networks, and Gaussian field theories. The mechanism is unique in that it is absent in spaces with translational invariance, while universal in that it is observed in a wide class of fractals.Comment: 11 pages, REVTEX, 3 postscript figures. (Compressed and encoded figures archived by "figure" command). To appear in Physical Review Letter

The Challenges Confronting the Banking System Reform in China: An Analysis in Light of Japan's Experience of Financial Liberalization

China's banking system reform has made notable progress since 2002. After restoring their balance sheets, Chinese banks have aggressively increased lending and contributed to supporting the country' s economy given the global financial crisis. Thus far, the regulated deposit and lending interest rates, undeveloped capital markets, and restrictions in cross-border capital transactions have given banks an advantage in gaining profits. However, along with the full-blown reform of the economic system toward a market-oriented economy, the conditions protecting banks' profits will change in the future. The experiences of Japanese banks under the financial liberalization that occurred during the 1970s and 1980s indicate how important it is for commercial banks to change their business models in accordance with the fundamental changes in the economy. These experiences may be useful for considering the subsequent reform process of the financial system in China.Banking System Reform, Financial Liberalization, State-owned Commercial Banks, Rent for Banks

Long-term oxygen therapy in Japan: history, present status, and current problems

Historically, the progress of long term-oxygen therapy (LTOT) in Japan has been characterized by collaboration among academicgroups, policy makers, and industrial companies. The public health insurance program has covered the cost of LTOT since 1985.Thomas Petty’s group in Denver enthusiastically carried out the public implementation of LTOT and conveyed the concept of pulmonaryrehabilitation for the processing with LTOT. Although the target diseases of LTOT in Japan tended to be chronic obstructivepulmonary disease or sequelae of primary lung tuberculosis, it was soon applied for cardiac diseases as well as other pulmonarydiseases. Together with increasing medical costs for geriatric patients, the political conversion from hospital based care ofa traditional style to home care system has been performed, with two background reasons: the improvement of quality of life ofpatients and the reduction of the medical expense. Presently, LTOT plays a pivotal role in the successful implementation of homerespiratory care for elderly patients. In addition, this promotes comprehensive pulmonary rehabilitation, a team approach, andclose liaisons between primary care and hospitals. Currently, the total number of patients using LTOT exceeds 150,000. In Japan,LTOT resulted in an advancement in the medical care as well as in administrative decision to introduce it as a nationwide systemafter analyzing the results of opinion polls of patients with respiratory failure. However, the recent great earthquake in East Japanrevealed that many unresolved problems remain for these patients, and these issues are of great concern.Historically, the progress of long term-oxygen therapy (LTOT) in Japan has been characterized by collaboration among academicgroups, policy makers, and industrial companies. The public health insurance program has covered the cost of LTOT since 1985.Thomas Petty’s group in Denver enthusiastically carried out the public implementation of LTOT and conveyed the concept of pulmonaryrehabilitation for the processing with LTOT. Although the target diseases of LTOT in Japan tended to be chronic obstructivepulmonary disease or sequelae of primary lung tuberculosis, it was soon applied for cardiac diseases as well as other pulmonarydiseases. Together with increasing medical costs for geriatric patients, the political conversion from hospital based care ofa traditional style to home care system has been performed, with two background reasons: the improvement of quality of life ofpatients and the reduction of the medical expense. Presently, LTOT plays a pivotal role in the successful implementation of homerespiratory care for elderly patients. In addition, this promotes comprehensive pulmonary rehabilitation, a team approach, andclose liaisons between primary care and hospitals. Currently, the total number of patients using LTOT exceeds 150,000. In Japan,LTOT resulted in an advancement in the medical care as well as in administrative decision to introduce it as a nationwide systemafter analyzing the results of opinion polls of patients with respiratory failure. However, the recent great earthquake in East Japanrevealed that many unresolved problems remain for these patients, and these issues are of great concern

審査論文 隠された脅威 : 大航海時代の魔女シコラックス

エリザベス朝とジェイムズ朝の日誌や旅行記を読み解きながら、『テンペスト』における他者の表象を、キャリバンの母シコラックスを中心に考察する。『テンペスト』では、大航海時代、イングランド植民地計画に関わる航海記に刺激を受けて、南北アメリカの他者インディアンの脅威を征服する男性性が描かれている。『テンペスト』はパストラル・ドラマの枠組みを持ち、その中で男性性は古典的な魔術の世界と平行しながら、新世界発見と成功のテーマを展開している。この劇では、こういった新世界を築く男性性に対して、ギリシャ・ローマ神話に繋がる北アフリカの古典的な他者、邪悪な子を孕むシコラックスが対置されている。その隠された存在は、不在であるがためにパストラル・ドラマの枠組みを逸脱してしまう。舞台上で、母体である女性性が男性性への脅威となって立ち現れ、その脅威に対する不安がこの劇全体を支配していることがわかる