Marshallian Externalities And The Emergence And Spatial Stability Of Technological Enclaves *

Technological dualism often is found to be associated with the geographical clustering of firms that use the same techniques. To shed further light on these localization phenomena, we analyze the long-run dynamic behavior of a system in which firms' choices among alternative production methods (each of which requires a technique-specific input) are influenced by both firm-specific random shocks and Marshallian ‘industrial neighborhood’ effects. The latter are local factor market externalities that tend to lower the relative marginal costs d those inputs that are used most extensively in the immediate locale. The model developed here focuses on labor market externalities affecting the supply conditions for workers with technology-specific skills, and their effect on the choices made by producers at various sites whose choice of technique is subject to periodic revisions. A special structure familiar in the applied theory of Markov random fields, the stochastic Ising model. provides a reduced-form representation of this dynamic spatial system. The general properties of models of this type and their application in economics are considered. Discrete time numerical simulations of the behavior of an ensemble of firms (located at the nodes of a finite lattice formed on a two-dimensional (orus) shows that positive neighborhood externalities effects do not necessarily result in the uniquitous diffusion of one of the two available technologies. Instead. this system exhibits a spatially localized form of ‘technological dualism," in which at least two technological enclaves emerge and undergo path-dependent evolution. The temporal durations of these spatial patterns in technology adoption are affected by parameters of the Ising model that can be given a straightforward economic interpretation     

人与自然发展的协调性:社会实践活动发展的新定位

人与自然对立的社会实践行为,导致了全球的生态危机,进而威胁到了人类的生存与发展。因此,人类必须抛弃传统的观念,转变价值观、发展观、消费观和科技观,树立科学的实践观,按生态平衡规律办事,在保护生态环境中去发展生产力,实现人与自然的协调发展。     

Research Networks And Organisational Mobility In An Emerging Technological Field: The Case Of Plant Biotechnology

This paper builds on social network theory to understand technological development. Based on the empirical evidence of 367 research organisations in plant biotechnology over a nineteen-year period, we demonstrate how a structural analysis of the research network within the technological community is used to identify four collaboration-based strategic groups of research organisations. The emergence of these groups can be linked to technological breakthroughs in the field. Analyses of the four clusters point to the influence of research collaborations on stratification within an evolving technological domain. Finally, as archival data sources are used to detect incidences of collaborative research and to trace the evolution of R&D networks in an emerging field, we conclude with a discussion of the potential contribution of bibliometric data to understand the development of new technologies in their early, pre-commercial phases.