Stochastically Stable Equilibria in Coordination Games with Multiple Populations

We investigate the equilibrium selection problem in n-person binary coordination games by means of adaptive play with mistakes (Young 1993). The size and the depth of a particular type of basins of attraction are found to be the main factors in determining the selection outcome. The main result shows that if a strategy has the larger basin of attraction, and if it is deep enough, then the strategy constitutes a stochastically stable equilibrium. The existence of games with multiple stochastically stable equilibria is an immediate consequence of the result. We explicitly address the qualitative difference between selection results in multi-dimensional stochastic evolution models and those in single dimensional models, and shed some light on the source of the difference.Equilibrium selection, stochastic stability, unanimity game, coordination game

Multiplicity and Sensitivity of Stochastically Stable Equilibria in Coordination Games

We investigate the equilibrium selection problem in n-person binary coordination games by means of the adaptive play with mistakes (Young 1993). We show that whenever the difference between the deviation losses of respective equilibria is not overwhelming, the stochastic stability exhibits a notable dependence on payoff parameters associated with strategy profiles where the numbers of players for the respective strategies are nearly equal. This feature necessitates the existence of games that possess multiple stochastically stable equilibria.Equilibrium selection, stochastic stability, unanimity game, coordination game

Multiple Stochastically Stable Equilibria in Coordination Games

In an (n,m)-coordination game, each of the n players has two alternative strategies. A strategy generates positive payoff only if there are at least m-1 others who choose the same, where m>n/2. The payoff is nondecreasing in the number of such others so that there are exactly two strict equilibria. Applying the adaptive play with mistakes (Young 1993) to (n,m)-coordination games, we point out potential complications inherent in many-person games. Focusing on games that admit simple analysis, we show that there is a nonempty open set of (n,m)-coordination games that possess multiple stochastically stable equilibria, which may be Pareto ranked, if and only if m>(n+3)/2, which in turn is equivalent to the condition that there is a strategy profile against which every player has alternative best responses.Equilibrium selection, stochastic stability, unanimity game, coordination game, collective decision making

Group Formation and Heterogeneity in Collective Action Games

We present a simple model of voluntary groups in a collective action problem where individuals differ in their willingness to cooperate. The heterogeneity of individuals' preferences generally yields multiple equilibrium groups with different levels of cooperation. Voluntary participation in a binding contract to cooperate does not necessarily lead to the full cooperation. Applications to voluntary provision of public goods and cartel formation in oligopolistic markets are discussed.group formation, collective action, heterogeneous preferences, voluntary participation

Fission-Fusion Correlation in Mechanical Property Changes of Several Pure FCC Metals

Mechanical property changes were observed for pure Ni, Cu and Au irradiated with fission and fusion neutrons. Before comparing the results of fission neutron with fusion neutron irradiation, the importance of irradiation temperature history is discussed. The irradiation below a designed temperature at the start-up of the reactor brings very different results from that obtained from strictly temperature controlled irradiation experiments, and this depends on the relative situation between the irradiation temperature and the temperature range of nucleation stage. Although there was no overlapping for neutron fluence in the fission and fusion neutron irradiation experiments, fluence for equivalent amount of the yield strength change for fusion neutron irradiation could be predicted from the plots of yield strength against 1/4 power of the neutron fluence for fission neutron irradiated specimens , and vice versa

Development of Large Capacity And High Efficiency Rotary Compressor

The authors had studied some elemental technologies to realize the large capacity and high efficiency in rotary compressor in order to achieve energy and material resource savings as well as in weight reduction of heat pump systems. Those elemental technologies are the cylinder dimension optimization, the new discharge structure, the divided vane structure, and the compatibility between sliding loss reduction and securing reliability in journal bearings. The new discharge structure is a structure in which two discharge ports are installed per cylinder. The discharge ports are designed with different in cross-sectional area and the responsiveness of each discharge valve is also optimized. By applying the new discharge structure, discharge losses drastically reduced during compression process. The divided vanes structure which splits the vane in the axial direction to reduce force due to the pressure difference per each vane enables to avoid the increasing risk at local contact surface pressure on vane. The journal bearing designs are optimized by using structural analysis. Enhanced shaft stiffness and appropriate journal bearing design contribute to sliding friction reduction and high reliability assurance. By adopting those technologies, we succeeded in developing a new compressor that can increase to the maximum refrigeration capacity 20 HP [60kW]. Compared to our conventional large model, the new model has 1.7 times larger maximum capacity, and about 6 % higher COP ratio in most operation condition range. Moreover, by the more compact and lighter weight of 38.2 kg, the new one has contributed to resource saving and weight reduction of the heat pump unit system. We commercialized this developed compressor for our latest air-cooled module heat pump unit “Universal Smart X Edge Series” which expanded up to 70HP in rated cooling capacity and achieved “IPLV 6.0” at 60 HP heat pump unit systems

A case of fulminant amebic colitis that could be saved

An 80-year-old man was admitted to a neighboring hospital with severe diarrhea and bloody stools. He did not have a remarkable medical history, was not homosexual, and had not traveled outside the country for several years. Colonoscopy was performed on the day of admission and revealed multiple ulcerations with edematous mucosa throughout the colorectum. Histopathological findings of biopsy specimen could not identify the reason for the inflamed colon. On postadmission day 6, the patient developed severe abdominal pain and underwent an emergent surgery for pan-peritonitis due to bowel perforation. The laparotomy revealed glossy fecal pan-peritonitis with perforation of the sigmoid colon; necrosis was observed through the entire length of the colon. The colonic tissue was extremely fragile and exhibited a blotting paper-like appearance. Total colectomy, sigmoid mucous fistula, ileostomy, and intraperitoneal drainage were performed. On postadmission day 12, histopathological findings of resected specimen raised the suspicion of amebic dysentery, and we accordingly treated him with metronidazole (2,250 mg/day) administered orally. Abdominal CT images taken on days 12 and 20 postadmission showed multiple liver abscesses, which improved following metronidazole administration. Metronidazole was discontinued 14 days after initiation as the patient’s general condition improved. His condition remained stable thereafter, and he was transferred two months after admission

Correlation study of observation data of polycyclic aromatic hydrocarbons and chemical transport model calculation data of other pollutants at Wajima

金沢大学大学院自然科学研究科場所：金沢大学自然科学研究科図書館棟1階，講演会場：図書館棟1階　大会議室，ポスター会場：図書館棟1階12会議室,主催・共催：文部科学省２１世紀COE「環日本海域の環境計測と長期・短期変動予測」， 大気環境学会， 金沢大学工学

Correlation study of observation data of polycyclic aromatic hydrocarbons and chemical transport model calculation data of other pollutants at Wajima

金沢大学大学院自然科学研究科場所：東京大学弥生講堂，共催：文部科学省２１世紀COE「環日本海域の環境計測と長期・短期変動予測」，大気環境学

Age-Dependent Association Between Modifiable Risk Factors and Incident Cardiovascular Disease

BACKGROUND: There have been limited data examining the age-dependent relationship of wide-range risk factors with the incidence of each subtype of cardiovascular disease (CVD) event. We assessed age-related associations between modifiable risk factors and the incidence of CVD. METHODS AND RESULTS: We analyzed 3 027 839 participants without a CVD history enrolled in the JMDC Claims Database (mean age, 44.8±11.0 years; 57.6% men). Each participant was categorized as aged 20 to 49 years (n=2 008 559), 50 to 59 years (n=712 273), and 60 to 75 years (n=307 007). Using Cox proportional hazards models and the relative risk reduction, we identified associations between risk factors and incident CVD, consisting of myocardial infarction, angina pectoris, stroke, and heart failure (HF). We assessed whether the association of risk factors for developing CVD would be modified by age cat-egory. Over a mean follow-up of 1133 days, 6315 myocardial infarction, 56 447 angina pectoris, 28 079 stroke, and 56 369 HF events were recorded. The incidence of myocardial infarction, angina pectoris, stroke, and HF increased with age category. Hazard ratios of obesity, hypertension, and diabetes in the multivariable Cox regression analyses for myocardial infarction, angina pectoris, stroke, and HF decreased with age category. The relative risk reduction of obesity, hypertension, and diabetes for CVD events decreased with age category. For example, the relative risk reduction of hypertension for HF decreased from 59.2% in participants aged 20 to 49 years to 38.1% in those aged 60 to 75 years. CONCLUSIONS: The contribution of modifiable risk factor to the development of CVD is greater in younger compared with older individuals. Preventive efforts for risk factor modification may be more effective in younger people.</p