Internet services, such as review sites, FAQ sites, online auction sites, online flea markets, and social networking services, are essential to our daily lives. Each Internet service aims to promote information exchange among people who share common interests, activities, or goods. Internet service providers aim to have users of their services actively communicate through their services. Without active interaction, the service falls into disuse. In this study, we consider that an Internet service has a network externality as its main feature, (...) and we model user behavior in the Internet service with network externality as a dynamic game. In particular, we model the diffusion process of users of an ISNE as an infinite-horizon extensive-form game of complete information in which: each user can choose whether or not to use the ISNE in her/his turn and the network effect of the ISNE depends on the history of each player’s actions. We then apply Markov perfect equilibrium to analyze how to increase the number of active users. We derive the necessary and sufficient condition under which the state in which every player is an active user is the unique Markov perfect equilibrium outcome. Moreover, we propose an incentive mechanism that enables the number of active users to increase steadily. (shrink)

During brain development, neural precursor cells (NPCs) in different brain regions produce different types of neurons, and each of these regions plays a different role in the adult brain. Therefore, precise regionalization is essential in the early stages of brain development, and irregular regionalization has been proposed as the cause of neurodevelopmental disorders. The mechanisms underlying brain regionalization have been well studied in terms of morphogen‐induced expression of critical transcription factors for regionalization. NPC potential in different brain regions is defined (...) by chromatin structures that regulate the plasticity of gene expression. Herein, we present recent findings on the importance of chromatin structure in brain regionalization, particularly with respect to its regulation by Polycomb‐group proteins and chromatin accessibility. (shrink)