In this paper, we investigate and analyze the cosmological dynamics of the universe, with an effect of modified f(R) gravity emerging at cosmological scale. We choose the Einstein frame as a physical frame. We consider phase portraits of the universe at the late time from modified f(R) gravity model. This result gives our universe an acceleration phase expansion without introducing existence of...

A gravity model, frequently used to explain trade patterns, is used to explain stock market correlations. The main result of the trade literature is that geography matters for goods markets. Physical location and trading costs should be less of an issue in asset markets. However we find that geographical variables still matter when examining equity market linkages. In particular, the number of ...

We study gravity localization in the context of a six-dimensional gravity model coupled with complex scalar fields. With a supergravity-motivated scalar potential, we show that the domain wall junction solutions localize a four-dimensional massless graviton under an assumption on the wall profile. We find that unlike the global supersymmetric model, contributions to the junction tension cancel ...

I review recent work toward constructing, via five-dimensional holographic duals, fourdimensional theories in which spin-2 states (gravitons) are emergent. The basic idea is to extend to gravity model-building the applications of holographic duality to phenomenology construction.

S. Deser* Physics Department, Brandeis University, Waltham Massachusetts 02454, USA and Lauritsen Laboratory, California Institute of Technology, Pasadena California 91125, USA (Received 28 April 2009; published 2 September 2009) Canonical analysis of a recently proposed linearþ quadratic curvature gravity model in D 1⁄4 3 establishes its pure, irreducibly fourth derivative, quadratic curvature...

Picture a small open economy in the North Atlantic Ocean, highly dependent on trade with the EU and NAFTA. How important are these trading blocs to the country’s exports? How important is the country’s location and size, and how do these affect the export sectors? A unique version of the gravity model is applied here using an inverse hyperbolic sine function. Typically, the export volume is sig...

While the gravity model has been one of the most successful applications in empirical trade, various attempts are still made to improve its regression results. One of the recent developments in the econometric technique is to extend the gravity model to a panel data framework and take into consideration the existence of dynamic effects. In this paper, we apply these new techniques to examine th...

China’s trade with Africa has increased significantly in the past two decades. The effects of these growing trade volumes (and financial flows) are quite contested. The purpose of this paper is to study the effects of growing Chinese influence in Africa on the intra-regional trade in the continent. This paper estimates a traditional gravity model using Poisson pseudo-maximum-likelihood estimati...

When data are poor, we resort to theory modeling. This is a two-step process. We have first to identify the appropriate type of model for the system under consideration and then to tailor it to the specifics of the case. To understand settlement formation, which is the concern of this article, this involves choosing not only input parameter values such as site separations but also input functio...

EU enlargement revives the debate around the participation to the EMU. We use a gravity model to see whether informal barriers have changed over a ten-year period covering the creation of the EMU, and whether their impact on European member countries’ agricultural and food trade has been modified. We find that it has led to lower information costs. We observe a diminishing marginal trade impact...