The paper moves a step forward in the direction of establishing a connection between the structure and evolution of knowledge
bases and the structure and evolution of organizational forms in innovative activities in a science-intensive industry. The
paper has an explicit focus on the dynamics of the network of collaborative agreements in R&D in the pharma/biotech industry
after the “molecular biology revolution”. Using a comprehensive dataset, built by the authors integrating several sources
in the industry, the dynamics of the network over time is extensively analyzed. With regards to network structure, it is found
that, while the size of the network increases over time due to net flows of entry, its topological properties remain relatively
unchanged. The evolution of the network has occurred without relevant deformations in the core-periphery profile. With regards
to age-dependent propensity to collaborate, the paper finds that the extent of inter-generational collaboration is much more
significant than intra-generational collaboration. In addition, the propensity of firms of a given generation to enter into
collaboration with firms of a different generation increases with the distance between the two, while the total number of
intra-generational collaborations decreases over time and, moreover, tends to decrease for most recent generations. In the
paper a unitary and coherent explanation of the evidence is developed, coming to reveal the existence of a striking isomorphism
between structural properties of the dynamics of knowledge and of the evolution of network structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Methods to perform regression on compositional covariates have recently been proposed using isometric log-ratios (ilr) representation of compositional parts. This approach consists of first applying standard regression on ilr coordinates and second, transforming the estimated ilr coefficients into their contrast log-ratio counterparts. This gives easy-to-interpret parameters indicating the relative effect of each compositional part. In this work we present an extension of this framework, where compositional covariate effects are allowed to be smooth in the ilr domain. This is achieved by fitting a smooth function over the multidimensional ilr space, using Bayesian P-splines. Smoothness is achieved by assuming random walk priors on spline coefficients in a hierarchical Bayesian framework. The proposed methodology is applied to spatial data from an ecological survey on a gypsum outcrop located in the Emilia Romagna Region, Italy. 相似文献
A generalization of the Granger and the Johansen Representation Theorems valid for any (possibly fractional) order of integration is presented. This Representation Theorem is based on inversion results that characterize the order of the pole and the coefficients of the Laurent series representation of the inverse of a matrix function around a singular point. Explicit expressions of the matrix coefficients of the (polynomial) cointegrating relations, of the Common Trends and of the Triangular representations are provided, either starting from the Moving Average or the Auto Regressive form. This contribution unifies different approaches in the literature and extends them to an arbitrary order of integration. The role of deterministic terms is discussed in detail. 相似文献
The aim of this article is to discuss some of the leading features of Erving Goffman's action theory as an alternative to the ‘orthodox’ paradigms of sociology, viewed as a structuralist and functionalist science that defines social constructs by their shared rules and values, and as a drifting of action, in the sense of intention, toward an individualistic version. The author examines Goffman's shift of the focus of attention from the boundaries of a social sense of action to the social dialectic of ‘defining a situation’ (W. Thomas) as conducted by the social actors in a renewal of Simmel's ‘empowering covenants’ (wechselwirkung) in the multiple casual social connections that make up the ‘social buzz’ in a society. The author moreover discusses Goffman's action as a kind of playacting regulating cognitive and expressive face-to-face ‘traffic’ between the social actors. This relational dynamic creates an interactive play based on encounters – in which one's opening to another is fraught with risks of deception – regulated by trust as a central resource for social interactions. Trust, in its interpersonal and systemic variants, constitutes a universal social datum and an elementary precondition for social exchanges and the cooperation between individuals. Trust, thus, functions as comparer between reciprocal expectations and a regulator of freedom tending to the stability of the social system. 相似文献
This article proposes a systematic procedure for computing probabilities of operator action failure in the cognitive reliability and error analysis method (CREAM). The starting point for the quantification is a previously introduced fuzzy version of the CREAM paradigm that is here further extended to account for: (1) the ambiguity in the qualification of the conditions under which the action is performed (common performance conditions, CPCs) and (2) the fact that the effects of such conditions on human performance reliability may not all be equal. 相似文献
Human migration involves the movement of people from one place to another. An example of undirected migration is Italian student mobility where students move from the South to the Center-North. This kind of mobility has become of general interest, and this work explores student mobility from Sicily towards universities outside the island. The data used in this paper regards six cohorts of students, from 2008/09 to 2013/14. In particular, our goal is to study the 3-step migration path: the area of origin (Sicilian provinces), the regional university for the bachelor’s degree, and the regional university for the master’s. Our analysis is conducted by building a multipartite network with four sets of nodes: students; Sicilian provinces; bachelor region of studies; and the master region of studies. By projecting the students’ set onto the others, we obtain a tripartite network where the number of students represents the link weight. Results show that the big Sicilian cities—Palermo, Catania, and Messina—have different preferential paths compared to small Sicilian cities. Furthermore, the results reveal preferential paths of 3-step mobility that only, in part, reflect a south-north orientation in the transition from the region of study for the bachelor degree to that for the master’s.
The present study integrates the technology acceptance and convergence streams of research to develop and test a model of
individual adoption of convergent mobile technologies. Adopting structural equation modelling, we hypothesize that relative
advantage, effort expectancy, social influence and facilitating conditions affect directly individual attitude and, indirectly
the intention to use convergent mobile technologies. The model explains a highly significant 53.2% of the variance for individual
attitude, while individual attitude accounts for 33.9% of the variance in behavioral intention.
Authors are listed alphabetically. 相似文献