Origin of Spin Ice Behavior in Ising Pyrochlore Magnets with Long Range Dipole Interactions: an Insight from Mean-Field Theory

Recent experiments suggest that the Ising pyrochlore magnets ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$ display qualitative properties of the ferromagnetic nearest neighbor spin ice model proposed by Harris {\it et al.}, Phys. Rev. Lett. {\bf 79}, 2554 (1997). The manifestation of spin ice behavior in these systems {\it despite} the energetic constraints introduced by the strength and the long range nature of dipole-dipole interactions, remains difficult to understand. We report here results from a mean field analysis that shed some light on the origin of spin ice behavior in (111) Ising pyrochlores. Specifically, we find that there exist a large frustrating effect of the dipolar interactions beyond the nearest neighbor, and that the degeneracy established by effective ferromagnetic nearest neighbor interactions is only very weakly lifted by the long range interactions. Such behavior only appears beyond a cut-off distance corresponding to $O(10^2)$ nearest neighbor. Our mean field analysis shows that truncation of dipolar interactions leads to spurious ordering phenomena that change with the truncation cut-off distance.Comment: 7 Color POSTSCRIPT figures included. To appear in Canadian Journal of Physics for the Proceedings of the {\it Highly Frustrated Magnetism 2000 Conference}, Waterloo, Ontario, Canada, June 11-15, 2000 Contact: [email protected]

Multinationals are Multicultural Units: Some Indications from a Cross-Cultural Study

This paper makes a case for the value of looking at culture and multinationals from a management and organizational perspective because it is one which could direct greater attention towards culture as a significant factor in future investigation on multinational corporations. We attempt to illustrate that multinationals are fundamentally multicultural units in more ways than one. This paper is based on selected materials from a qualitative study of culture and learning in organizations and management. The study investigated four selected Dutch firms in Thailand using evidences collected through observations and open-ended interviews. All evidences were analysed under grounded theory procedure. Parts of the evidences and theorization from the study are presented in this paper, which begins with two cultural riddles from one of the cases as a backdrop for subsequent discussions. Following the riddles is an abridge version of the key finding of the study-a grounded theory of cross-cultural intelligence. Then the two riddles are revisited, this time to illustrate how the proposed theory could illuminate an understanding of their covert meanings vis-à-vis culture and learning in multinationals. Last, we reinstate how our study and its theoretical and empirical findings can elucidate the central thesis that multinationals are essentially multicultural units.case study, culture, corporate culture, cultural intelligence, multinationals, Netherlands, Thailand

Portrait of an Odd-Eyed Cat: Cultural Crossing as a Trademark for a Dutch-Thai Strategic Alliance

This chapter attempts a step forward in seeking a richer understanding of the dynamics of strategic alliances, specifically when viewed from a cross-cultural perspective. We report selected materials from a study designed to build a theory of culture and learning in organizations based on observations of and open-ended interviews with Dutch and Thai employees working for four selected Dutch firms in Thailand. Here we present one of those cases, a Dutch-Thai joint venture that thrived by weaving together the many intricate cultural webs to achieve a unique pattern of partnership which, metaphorically speaking, became its indispensible trademark. The case illustrates how the three levels of culture – national, organizational, and professional cultures – could all interlace in a real world setting and serve as an instrumental force of success amidst tension in one particular cross-border strategic alliance. First, we adopt a thick descriptive style of case narration to present the case of a Dutch- Thai joint venture, Chuchawal-De Weger Internationaal (CDW), painting a portrait of its origin, evolution and characteristics. Next, we turn to elaborate on the particular issue of cultural crossing, its exact theorized properties, dimensions and implications. Finally, we relate the case of CDW to the proposed theory and conclude with a reflection on how this case and our interpretation of it illuminate the complex role culture can play in the dynamics of strategic alliances.cross-cultural management, culture, qualitative case study, strategic alliance, thick-description

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On Convex Quadratic Approximation

In this paper we prove the counterintuitive result that the quadratic least squares approximation of a multivariate convex function in a finite set of points is not necessarily convex, even though it is convex for a univariate convex function. This result has many consequences both for the field of statistics and optimization. We show that convexity can be enforced in the multivariate case by using semidefinite programming techniques.Convex function;least squares;quadratic interpolation;semidefinite program- ming