The measures employed are standard in gravity models, which have enjoyed great empirical success in the trade literature.5 Moreover, the gravity model allows tests of whether Cuba and competing [End Page 2] Caribbean destinations adjust their tourism base to hedge potential gains or losses in the wake of free Cuba-U.S. tourism trade.
In order to construct exact solutions parametrized by generic off-diagonal metrics or for investigating nonholonomic frame structures in gravity models with nontrivial torsion, it is more convenient to work with more general classes of linear connections which are N-adapted but contain nontrivial torsion coefficients because of nontrivial nonholonomy coefficients W αß γ Open image in new window.
In contrast, several epidemiological observations, such as spatially structured diffusion patterns [ 18, 19] and hierarchical spread driven by population size and distance, in gravity models [ 20], have not been evident from phylogenetic methods [ 16, 21, 22].
The general form of the gravity model for locating retail trade, which links expenditure and accessibility, is shown in Box 8. there is a common tendency to simplify distance in gravity models to pure distance, not reflecting time or cost differences in operating the road network.
The difference of the fault displacement and depth of the basement obtained in the gravity model is in the order of 10% compared to seismic and well data.
Both models are static and require some information in order to be adjusted: in the gravity model, parameters are fitted using real mobility data, provided by an independent source; the radiation model, in its original formulation, is parameter-free, but it requires accurate knowledge of the spatial population distribution.
Practices proves this method overcome the shortcomings existing in the gravity model and the breaking-point model which are commonly used to determine the scope of hinterland.
To this end, researchers from MIT, Northeastern University and Italy's University of Padua have identified an underlying flaw in the gravity model: The distance between two cities is far less important than the population size in the area surrounding them.
This paper presents new evidence regarding the role of national scientific capacity in driving patterns of R&D offshoring using a larger and more comprehensive dataset than has hitherto been used and applying it in a gravity model framework.
