In non-minimally coupled effective gravity theories one can have non-topological solitonic solutions. A typical solution is a spherical region with Geff = 0 outside and having the canonical Newtonian value inside. Such a spherical domain (gravity-ball) is characterized by an effective index of refraction which causes bending of light incident on it. The gravity ball thus acts as a spherical len...

We provide a method to determine the motion of a classical massive particle in a background geometry of 2-dimensional gravity theories, for which the Birkhoff theorem holds. In particular, we get the particle trajectory in a continuous class of 2-dimensional dilaton gravity theories that includes the Callan-Giddings-HarveyStrominger (CGHS) model, the Jackiw-Teitelboim (JT) model, and the d-dime...

background: spine of an adult is made up of five areas that include 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, sacrum and finally coccyx. selecting appropriate assumptions for modeling and biological analysis of the spine components has a significant impact on the accuracy of results in biomechanical simulation for different modes. methods: in the present study, biomechani...

this article has considered the volume and direction of iran’s trade using the gravity model. the major issue in this analysis is to explore why iran over or under-traded with the 76 countries relative to the predicted trade flows of the model. the study attempts to explore the reasons from the respect of both the model itself and iran’s trade structure. this is done by analysing the performanc...

in gravity interpretation, inversion algorithms have been used widely over the years, but as the potential follows the gauss theorem, there are many equivalent source distributions that can produce the same known field. so to obtain a unique solution, suitable constraints should be introduced to the algorithm. during the last decades many authors have used several approaches to introduce a prio...

â â â â â â â â â â â  the recent global crisis, as a big crash ( baldwin and simon , 2009), has reduced foreign demand growth affecting total countries’ exports. given the importance of foreign trade to nations and the reality that recent crisis has affected international trade we study the effects of the global financial crisis on trade relations between countries by using ma and cheng (200...

We obtain nonperturbative results in the framework of continuous Liouville theory. In particular, we express the specific heat Z of pure gravity in terms of an expansion of integrals on moduli spaces of punctured Riemann spheres. The integrands are written in terms of the Liouville action. We show that Z satisfies the Painlevé I. Partly supported by the European Community Research Programme Gau...

In this article, we review model selection predictions for modified gravity scenarios as an explanation for the observed acceleration of the expansion history of the Universe. We present analytical procedures for calculating expected Bayesian evidence values in two cases: (i) that modified gravity is a simple parametrized extension of general relativity (GR; two nested models), such that a Baye...

A new model, dubbed the MRQSphere, provides a multiresolution representation of the gravity field designed for its estimation. The multiresolution representation uses an approximation via Gaussians of the solution of the Laplace’s equation in the exterior of a sphere. Also, instead of the spherical harmonics, variations in the angular variables are modeled by a set of functions constructed usin...