A folk theorem in infinitely repeated prisoner's dilemma with small observation cost

We consider an infinitely repeated prisoner's dilemma under costly observation. If a player observes his opponent, then he pays an observation cost and knows the action chosen by his opponent. If a player does not observe his opponent, he cannot obtain any information about his opponent's action. Furthermore, no player can statistically identify the observational decision of his opponent. We prove an efficiency without any signals. Next, we consider a kind of delayed observations. Players decide their actions and observation decisions in the same period, but they choose observation decisions after they choose their actions. We introduce an interim public randomization instead of public randomization just before observation decision. We present a folk theorem with an interim public randomization device for a sufficiently small observation cost when players are sufficiently patient

A folk theorem in infinitely repeated prisoner's dilemma with small observation cost

We consider an infinitely repeated prisoner's dilemma under costly observation. If a player observes his opponent, then he pays an observation cost and knows the action chosen by his opponent. If a player does not observe his opponent, he cannot obtain any information about his opponent's action. Furthermore, no player can statistically identify the observational decision of his opponent. We prove an efficiency without any signals. Next, we consider a kind of delayed observations. Players decide their actions and observation decisions in the same period, but they choose observation decisions after they choose their actions. We introduce an interim public randomization instead of public randomization just before observation decision. We present a folk theorem with an interim public randomization device for a sufficiently small observation cost when players are sufficiently patient

A folk theorem in infinitely repeated prisoner's dilemma with small observation cost

We consider an infinitely repeated prisoner's dilemma under costly observation. If a player observes his opponent, then he pays an observation cost and knows the action chosen by his opponent. If a player does not observe his opponent, he cannot obtain any information about his opponent's action. Furthermore, no player can statistically identify the observational decision of his opponent. We prove an efficiency without any signals. Next, we consider a kind of delayed observations. Players decide their actions and observation decisions in the same period, but they choose observation decisions after they choose their actions. We introduce an interim public randomization instead of public randomization just before observation decision. We present a folk theorem with an interim public randomization device for a sufficiently small observation cost when players are sufficiently patient

Corporate Social Responsibility and Strategic Relationships

We analyze a delegation game relevant to the conduct of corporate social responsibility (CSR) in which the firm's owner offers the manager a contract consisting of firm profit and social welfare. We derive three results that distinctly differ from existing findings. First, CSR decisions are strategic complements for firms. Second, with simultaneous CSR decisions, the equilibrium price is equal to marginal cost, despite the fact that firms compete in a Cournot duopoly. Finally, with sequential CSR decisions, unlike the follower firm, the leader firm never exhibits CSR. However, the follower firm can enjoy a profit equal to that derived by the leader in a Cournot-Stackelberg game

Corporate Social Responsibility and Strategic Relationships

We analyze a delegation game relevant to the conduct of corporate social responsibility (CSR) in which the firm's owner offers the manager a contract consisting of firm profit and social welfare. We derive three results that distinctly differ from existing findings. First, CSR decisions are strategic complements for firms. Second, with simultaneous CSR decisions, the equilibrium price is equal to marginal cost, despite the fact that firms compete in a Cournot duopoly. Finally, with sequential CSR decisions, unlike the follower firm, the leader firm never exhibits CSR. However, the follower firm can enjoy a profit equal to that derived by the leader in a Cournot-Stackelberg game

Road Junction Configurations and the Severity of Traffic Accidents in Japan

In many countries, 40–60% of the traffic accidents occur at junctions, making the reduction of junction accidents paramount to achieving UN Sustainable Development Goals. In Japan, the road safety guidelines specify the proximity between junctions and non-perpendicular angles at junctions as the two main risk factors behind junction accidents, yet their impact remains understudied. Using binomial logistic regression models, this study investigates the impact of junction intervals and junction angles on the severity of traffic accidents. The study found that, in general, (1) shorter intervals between adjacent junctions helps reduce the risk of serious accidents, which is the opposite of the current road safety guidelines in Japan, and (2) results from the junction angle analysis were mixed but there was no evidence that the roads should meet at a right angle to reduce traffic accidents. Some types of accidents also returned a non-linear curve, e.g., vehicle-to-vehicle collisions at four-armed junctions involving a driver aged 65 years and over have the highest risk of fatal/serious accidents when adjacent junctions were 32 m apart, and the risk reduces at a shorter or longer interval. These results suggest that the current road safety guidelines require updating to improve road safety around junctions

A Case of Hepatocellular Carcinoma with Bone Metastasis Responding to Radiotherapy after Successful Hepatectomy of Primary Lesion

Radical hepatectomy was carried out on a patient with hepatocellular carcinima (HCC) located in segment VIII of the liver. The patient was a 56-year-old man who showed positive for hepatitis C antibody and negative for hepatitis B surface antigen. Six months after hepatectomy, a lumbar plane X-ray and computed tomography examination revealed bone metastases in the lumbar vertebrae. The patient was subsequently treated by radiation to the lumbar vertebrae in response to lumbago. The metastatic lesion has been well controlled by radiotherapy on an oputpatient basis with no recurrence for 5 years and 3 months.　　 The prognosis of patients with HCC with distant metastases is poor. It is believed that the long survival of this patient can be attributed to successful radiotherapy of the bone metastasis after hepatectomy and the lack of recurrence in the liver

KRT13 and UPK1B for differential diagnosis between metastatic lung carcinoma from oral squamous cell carcinoma and lung squamous cell carcinoma

Abstract Oral squamous cell carcinomas unusually show distant metastasis to the lung after primary treatment, which can be difficult to differentiate from primary squamous cell carcinoma of the lung. While the location and number of tumor nodules is helpful in diagnosing cases, differential diagnosis may be difficult even with histopathological examination. Therefore, we attempted to identify molecules that can facilitate accurate differential diagnosis. First, we performed a comprehensive gene expression analysis using microarray data for OSCC-LM and LSCC, and searched for genes showing significantly different expression levels. We then identified KRT13, UPK1B, and nuclear receptor subfamily 0, group B, member 1 (NR0B1) as genes that were significantly upregulated in LSCC and quantified the expression levels of these genes by real-time quantitative RT-PCR. The expression of KRT13 and UPK1B proteins were then examined by immunohistochemical staining. While OSCC-LM showed no KRT13 and UPK1B expression, some tumor cells of LSCC showed KRT13 and UPK1B expression in 10 of 12 cases (83.3%). All LSCC cases were positive for at least one of these markers. Thus, KRT13 and UPK1B might contribute in differentiating OSCC-LM from LSCC