SIMULATION OF THE GROWTH RESPONSE OF DRYLAND AND IRRIGATED CORN*

This paper studies the complex relationship between plant growth and the variables affecting that growth. The author has developed several growth models, with soil moisture being a primary explanatory variable in the models. The relationship of plant growth to moisture is demonstrated by the sensitivity of a corn plant to moisture at different periods in its growth. Ce papier fail une études des relations complexes entre la croissance des plantes et les variables qui influent cette croissance. ?auteur a construit plusieurs modèles de croissance en se servant de ?humidité du sol comme variable primaire explicalif La connexité entre la croissance des plantes el ?humidilé est démonstée en utilisant une plante de blé d;inde ei en montrant comment sensible à?humidité est cette plante à differentes étapes de sa maturation.     

ESTIMATING THE DEMAND FOR WATER IN COMMERCIAL AGRICULTURE*

The foundation of the demand for water in agriculture is the water response functions of the various crops grown. As the productivity of water is largely determined by the lime at which a crop is irrigated, both intra-seasonal and seasonal demand schedules for water exist for the firm and so for the region. The efficient interregional allocation and pricing of water between users may be assessed using spatial equilibrium models. While a profit maximising objective may be valid for the firm, as the level of an analysis moves to the regional or the inter-regional complex, increasing attention must be paid to non-economic goals which must be incorporated within societies' objective. La demande ?eau dans ?agriculture se base sur les fonctions du besoin ?eau des récolies différents. Tandis que la productivité de ?eau est déterminé en grande parlie selon la saison pendant laquelle une récolle est irriguée, des programmes de demande intra-saisonnier et saisonnier pour ?eau existe pour ?exploitation, ainsi que pour la région. ?allocation efficace au niveau inter-régional et ?établissement ?un prix pour ?eau parmi les utilisateurs peuvent être évalués en se servant de modèles ?equilibre spatial. Tandis qu'un but de maximisation de profit peut être valide pour ?exploitation. au moment ou une analyse comprend le systems régional ou inter-regional, il faut aussi considérer les buts non-économiques qui doivent etre incorporés dans les objectifs sociaux.     

How Central Is Too Central? Organizing Interorganizational Collaboration Networks for Breakthrough Innovation

Firms increasingly look to collaboration with alliance partners in their quest for breakthrough innovation. But how does the position of a firm in its alliance network weighted by the centrality of its partners—a concept which we term “partner‐weighted alliance centrality”—and the heterogeneities in the types of partners that it cooperates with—in terms of its private‐public collaboration—influence this quest? Using longitudinal data from the U.S. pharmaceutical industry, we build alliance networks in the period 1985–2001 to investigate these questions. We show that, for breakthrough innovation, collaborating with more partners that are more central in alliance networks the better, but only to a point. Beyond that point, we find that the likelihood of achieving breakthrough innovation drops. Furthermore, and looking at the kinds of knowledge provided by the partners in each firm's alliances, we report that firms with a greater share of private partners, relative to public partners, suffer less from the diminishing benefits of collaboration with central partners when developing breakthrough innovation. Taken together, we make novel contributions about how to organize for breakthrough innovation, and provide actionable managerial advice in terms of selecting collaborative partners in alliance networks.