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 effects of foreign direct investment (FDI) on economic growth when sufficient provisions of infrastructure is a pre-requisite. In the overlapping generations setting, we show that technology spillovers via FDI take place only when the host country has the sufficient level of infrastructure. Infrastructure has a subsequent positive feedback on further investment which leads the country to grow faster. If infrastructure falls short of the critical level, however, then FDI has little effect 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 support the model that FDI and infrastructure are complementary in affecting per capita GDP growth.http://deepblue.lib.umich.edu/bitstream/2027.42/57225/1/wp845 .pd

Improving Routing Efficiency through Intermediate Target Based Geographic Routing

The greedy strategy of geographical routing may cause the local minimum problem when there is a hole in the routing area. It depends on other strategies such as perimeter routing to find a detour path, which can be long and result in inefficiency of the routing protocol. In this paper, we propose a new approach called Intermediate Target based Geographic Routing (ITGR) to solve the long detour path problem. The basic idea is to use previous experience to determine the destination areas that are shaded by the holes. The novelty of the approach is that a single forwarding path can be used to determine a shaded area that may cover many destination nodes. We design an efficient method for the source to find out whether a destination node belongs to a shaded area. The source then selects an intermediate node as the tentative target and greedily forwards packets to it, which in turn forwards the packet to the final destination by greedy routing. ITGR can combine multiple shaded areas to improve the efficiency of representation and routing. We perform simulations and demonstrate that ITGR significantly reduces the routing path length, compared with existing geographic routing protocols

On the Role of Absorptive Capacity: FDI Matters to Growth

The paper studies the effects of foreign direct investment (FDI) on economic growth when sufficient provisions of infrastructure is a pre-requisite. In the overlapping generations setting, we show that technology spillovers via FDI take place only when the host country has the sufficient level of infrastructure. Infrastructure has a subsequent positive feedback on further investment which leads the country to grow faster. If infrastructure falls short of the critical level, however, then FDI has little effect on growth as the country is trapped in a lowgrowth equilibrium. We also present the simulations and empirical results based on panel data for 42 developing countries between 1970 and 2000. They support the model that FDI and infrastructure are complementary in affecting per capita GDP growth.foreign direct investment; economic growth, technology diffusion, infrastructure

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