Homotopy Actions, Cyclic Maps and their Duals

An action of A on X is a map F: AxX to X such that F|_X = id: X to X. The restriction F|_A: A to X of an action is called a cyclic map. Special cases of these notions include group actions and the Gottlieb groups of a space, each of which has been studied extensively. We prove some general results about actions and their Eckmann-Hilton duals. For instance, we classify the actions on an H-space that are compatible with the H-structure. As a corollary, we prove that if any two actions F and F' of A on X have cyclic maps f and f' with Omega(f) = Omega(f'), then Omega(F) and Omega(F') give the same action of Omega(A) on Omega(X). We introduce a new notion of the category of a map g and prove that g is cocyclic if and only if the category is less than or equal to 1. From this we conclude that if g is cocyclic, then the Berstein-Ganea category of g is <= 1. We also briefly discuss the relationship between a map being cyclic and its cocategory being <= 1.Comment: 16 pages, LaTeX 2

International Equity Flows and Returns: A Quantitative Equilibrium Approach

This paper considers the role of foreign investors in developed-country equity markets. It presents a quantitative model of trading that is built around two new assumptions: (i) both the foreign and domestic investor populations contain investors of different sophistication, and (ii) investor sophistication matters for performance in both public equity and private investment opportunities. The model delivers a unified explanation for three stylized facts about US investors' international equity trades: (i) trading by US investors occurs in bursts of simultaneous buying and selling, (ii) Americans build and unwind foreign equity positions gradually and (iii) US investors increase their market share in a country when stock prices there have recently been rising. The results suggest that heterogeneity within the foreign investor population is much more important than heterogeneity of investors across countries.Asymmetric information, heterogenous investors, asset pricing, international equity flows, international equity returns

International equity flows and returns: a quantitative equilibrium approach

This paper considers the role of foreign investors in developed-country equity markets. It presents a quantitative model of trading that is built around two new assumptions: (i) both the foreign and domestic investor populations contain investors of different sophistication, and (ii) investor sophistication matters for performance in both public equity and private investment opportunities. The model delivers a unified explanation for three stylized facts about US investors’ international equity trades: (i ) trading by US investors occurs in bursts of simultaneous buying and selling, (ii ) Americans build and unwind foreign equity positions gradually and (iii ) US investors increase their market share in a country when stock prices there have recently been rising. The results suggest that heterogeneity within the foreign investor population is much more important than heterogeneity of investors across countries.Asymmetric information, heterogenous investors, asset pricing, international equity flows, international equity returns

An emerging market for corporate control? The Mannesmann takeover and German corporate governance

Corporate governance in Germany is often described as a bank-oriented, block-holder or stakeholder model where markets for corporate control have not played a significant role. This case study of the hostile takeover of Mannesmann AG by Vodafone in 2000 demonstrates how systemic changes during the 1990s have eroded past institutional barriers to takeovers. These changes include the strategic reorientation of German banks from the house bank to investment banking, the growing consensus and productivity orientation of employee co-determination and corporate law reform. A significant segment of German corporations are now subjected to a market for corporate control. The implications for the German model are examined in light of both claims by agency theory for the efficiency of takeover markets, as well as the institutional complementarities within Germany's specific variety of capitalism. While the efficiency effects are questionable, the growing pressures for German corporations to achieve the higher stock market valuations of their Anglo-American competitors threaten the distributional compromises underlying the German model. --

PRODUCTION, PRICE AND RISK FACTORS IN CHANNEL CATFISH FARMING

The effects of several production/management, price and risk factors upon channel catfish profitability are analyzed with a multiperiod mixed-integer linear programming model. Factors analyzed include pond size and optimal stocking rates, alternate levels and trends in catfish prices, pond production losses and level of family consumption withdrawals. Model results indicate that channel catfish offer the potential to significantly increase farm rates of return while providing an avenue of intensive farm growth, without expanding the land base of the farm. However, the long range financial success of the firm was very sensitive to several of the management and risk factors examined.Production Economics, Risk and Uncertainty,

Supersymmetric solutions to Euclidean Romans supergravity

We study Euclidean Romans supergravity in six dimensions with a non-trivial Abelian R-symmetry gauge field. We show that supersymmetric solutions are in one-to-one correspondence with solutions to a set of differential constraints on an SU(2) structure. As an application of our results we (i) show that this structure reduces at a conformal boundary to the five-dimensional rigid supersymmetric geometry previously studied by the authors, (ii) find a general expression for the holographic dual of the VEV of a BPS Wilson loop, matching an exact field theory computation, (iii) construct holographic duals to squashed Sasaki-Einstein backgrounds, again matching to a field theory computation, and (iv) find new analytic solutions.Comment: 31 pages; v2: published version (with reference added