Higher-Derivative Gravity with Non-minimally Coupled Maxwell Field

We construct higher-derivative gravities with a non-minimally coupled Maxwell field. The Lagrangian consists of polynomial invariants built from the Riemann tensor and the Maxwell field strength in such a way that the equations of motion are second order for both the metric and the Maxwell potential. We also generalize the construction to involve a generic non-minimally coupled $p$-form field strength. We then focus on one low-lying example in four dimensions and construct the exact magnetically-charged black holes. We also construct exact electrically-charged $z=2$ Lifshitz black holes. We obtain approximate dyonic black holes for the small coupling constant or small charges. We find that the thermodynamics based on the Wald formalism disagrees with that derived from the Euclidean action procedure, suggesting this may be a general situation in higher-derivative gravities with non-minimally coupled form fields. As an application in the AdS/CFT correspondence, we study the entropy/viscosity ratio for the AdS or Lifshitz planar black holes, and find that the exact ratio can be obtained without having to know the details of the solutions, even for this higher-derivative theory.Comment: Latex, 23 page

On the Role of Absorptive Capacity: FDI Matters to Growth

The paper studies the e®ects of foreign direct investment (FDI) on economic growth when su±cient provisions of infrastructure is a pre-requisite. In the overlap-ping generations structure setting, we show that technology spillovers via FDI take place only when the host country has the su±cient level of infrastructure. Infras-tructure has a subsequent positive feedback on further investment which leads the country grow faster. If infrastructure falls short of the critical level, however, then FDI has little e®ect on growth as the country is trapped in a low-growth equilibrium. We also present the simulations and empirical results based on panel data for 42 developing countries between 1970 and 2000. They provide support to the model that FDI and infrastructure are complements in a®ecting per capita GDP growth.

Horndeski Gravity and the Violation of Reverse Isoperimetric Inequality

We consider Einstein-Horndeski-Maxwell gravity, together with a cosmological constant and multiple Horndeski axions. We construct charged AdS planar black holes in general dimensions where the Horndeski anxions span over the planar directions. We analyse the thermodynamics and obtain the black hole volumes. We show that the reverse isoperimetric inequality can be violated, implying that these black holes can store information more efficiently than the Schwarzschild black hole.Comment: Latex, 25 pages, 1 figure, references adde

Second-harmonic generation in graded metallic films

We study the effective second-harmonic generation (SHG) susceptibility in graded metallic films by invoking the local field effects exactly, and further numerically demonstrate that the graded metallic films can serve as a novel optical material for producing a broad structure in both the linear and SHG response and an enhancement in the SHG signal.Comment: 10 pages, 2 EPS figures. Minor revision

Asymmetric Information and Global Sourcing

This paper aims to study the choice of offshoring modes made by multinationals in the presence of asymmetric information. We focus on two types of asymmetric information, namely hidden characteristics and hidden action. The former creates adverse selection problem, and the later leads to moral hazard problem, both of which incur non-trivial costs to multinationals. We show that different offshoring modes, including greenfield foreign direct investment, joint venture, and outsourcing, can serve as a means to overcome or mitigate the problem of information asymmetry. We study the conditions under which one particular type of offshore modes dominates the others. The model generates implications consistent with the patterns of the prevalence of various offshoring models over time, and across industries and countries.Asymmetric Information, Global Sourcing, Foreign Direct Investment, Joint Venture, Outsourcing

Equity market volatility and expected risk premium

This paper revisits the time-series relation between the conditional risk premium and variance of the equity market portfolio. The main innovation is that we construct a measure of the ex ante equity market risk premium using corporate bond yield spread data. This measure is forward-looking and does not rely critically on either realized equity returns or instrumental variables. We find strong support for a positive risk-return tradeoff, and this result is not sensitive to a number of robustness checks, including alternative proxies of the conditional stock variance and controls for hedging demands.Stock exchanges ; Securities