Search results for "GRAVITY MODEL"

Calculation and inversion of two-dimensional gravity in the vicinity of Lake Tuz, Turkey

2000

Abstract An example of gravity inversion and interpretation is presented which demonstrates how a priori information can be used to derive reliable, though complex models. In this case, the geometry of the studied model profile has been constructed on the basis of seismic and geological data. The densities used in the forward calculations were obtained from laboratory measurements of drill cores, from density-velocity relationships, and from Nettleton’s method of fitting gravity and topography. In the seismic section 21 ‘formations’ are distinguished leading to a very complex gravity model. What is called ‘formations’ here, are two-dimensional bodies which are distinguished from each other …

Trade Costs, Trade Balances, and Current Accounts: an application of Gravity to Multilateral Trade

2005

In this paper we test the well-known hypothesis of Obstfeld and Rogoff (NBER Macroeconomics Annual 7777:339–390, 2000) that trade costs are the key to explaining the so-called Feldstein–Horioka puzzle. Our approach has a number of novel features. First, we focus on the interrelationship between trade costs, the trade account and the Feldstein–Horioka puzzle. Second, we use the gravity model to estimate the effect of trade costs on bilateral trade and, third, we show how bilateral trade can be used to draw inferences about desired trade balances and desired intertemporal trade. Our econometric results provide strong support for the Obstfeld and Rogoff hypothesis and we are also able to recon…

Canonical equivalence of a generic 2-D dilaton gravity model and a free field

1997

We show that a canonical transformation converts, up to a boundary term, a generic 2-D dilaton gravity model into a free field theory with a Minkowskian target space.

Institutional Quality and International Competitiveness

2008

The two-loop five-particle amplitude in $\mathcal{N}=8$ supergravity

2019

We compute for the first time the two-loop five-particle amplitude in $\mathcal{N}=8$ supergravity. Starting from the known integrand, we perform an integration-by-parts reduction and express the answer in terms of uniform weight master integrals. The latter are known to evaluate to non-planar pentagon functions, described by a 31-letter symbol alphabet. We express the final result for the amplitude in terms of uniform weight four symbols, multiplied by a small set of rational factors. The amplitude satisfies the expected factorization properties when one external graviton becomes soft, and when two external gravitons become collinear. We verify that the soft divergences of the amplitude ex…

Free Fields for Chiral 2D Dilaton Gravity

1998

We give an explicit canonical transformation which transforms a generic chiral 2D dilaton gravity model into a free field theory.

Determinants of Italy's agri-food trade flows with the Mediterranean non-Eu partner countries

2013

The objective of this paper is to evaluate the determinants of Italy’s agri-food exports in the markets of Mediterranean non-EU partner countries and, particularly, the impact of Agreement Association signed in the Euro-Mediterranean partnership. The Mediterranean Sea situated at the crossroad of three continents, the European, the Asian and the African one, has ever been of great strategic interest for several geo-economical powers and in particular of the European Union as one of its foreign policy main protagonists. Italy as a centred Mediterranean country which is sharing agri-food production with some Mediterranean partners could profit from the EU’s relationships with the partners of …

The determinants of FDI: a new network-based approach

2022

This article investigates the determinants of FDI at sub-national level. It recognizes that MNEsModified Letter Turned Comma foreign activities are organized in networks of strongly interconnected, but geographically dispersed affiliates. This implies a different approach to the analysis of the determinants of FDI, which should focus on contextual factors able to stimulate economic relations at distance. Methodologically, we use a gravity-type model and different regression techniques with a new dataset on networks of FDI involving German and Italian regions. We find evidence that technologically proximate regions sharing the same industry profile are more likely to experience positive and …

Political risk and export promotion: evidence from Germany

2008

Political risk represents an important hidden transaction cost that reduces international trade. This paper investigates the claim that German public export credit guarantees (Hermes guarantees) mitigate this friction to trade flows and hence promote exports. We employ an empirical trade gravity model, where we explicitly control for political risk in the importing country in order to evaluate the effect of export guarantees. The idea behind export promotion through public export credit agencies (ECAs) is that the private market is unable to provide adequate insurance for all risks associated with exports. As a consequence, firms' export activities are limited in the absence of insurance pr…

Explaining German outward FDI in the EU: a reassessment using Bayesian model averaging and GLM estimators

2021

The last decades have seen an increasing interest in FDI and the process of production fragmentation. This has been particularly important for Germany as the core of the European Union (EU) production hub. This paper attempts to provide a deeper under standing of the drivers of German outward FDI in the EU for the period 1996–2012 by tackling the two main challenges faced in the modelization of FDI, namely the variable selection problem and the choice of the estimation method. For that purpose, we first extend previous BMA analysis developed by Camarero et al. (Econ Model 83:326–345, 2019) by including country-pair-fixed effects to select the appropriate set of variables. Second, we compare…