We consider n-body problems given by potentials of the form α r + β r with a, b, α, β constants, 0 ≤ a < b. To analyze the dynamics of the problem, we first prove some properties related to central configurations, including a generalization of Moulton’s theorem. Then we obtain several qualitative properties for collision and near-collision orbits in the Manev-type case a = 1. At the end we poin...

A large class of Type II fluid solutions to Einstein field equations in Ndimensional spherical spacetimes is found, wich includes most of the known solutions. A family of the generalized collapsing Vaidya solutions with homothetic self-similarity, parametrized by a constant λ, is studied, and found that when λ > λc(N), the collapse always forms black holes, and when λ < λc(N), it always forms n...

The traditional economic approach to index number theory is based on a ratio concept. The Konüs true cost of living index is a ratio of cost functions evaluated at the same utility level but with the prices of the current period in the cost function that appears in the numerator and the prices of the base period in the denominator cost function. The Allen quantity index is also a ratio of cost ...

Wide field interferometry has become a subject of increasing interest in the recent years. New methods have been suggested in order to avoid the drawbacks of the standard wide field method (homothetic mapping) which is not applicable when the aperture is highly diluted; for this reason imaging with non-homothetic arrays is being extensively studied1,2. The field of view of a pupil plane interfe...

In the incomplete markets model with numeraire asset and a single consumption good we show that, even with homothetic preferences, on compact sets of prices Continuity, Walras’ identity and Homogeneity characterize the properties of market excess demand. This result is proved by an extension of Mantel (1976) to the case of incomplete markets. Journal of Economic Literature Class. No. : D 52, C ...

Differences between the concepts of returns to size and returns to scale are systematically reexamined in this paper. Specifically, the relationship between returns to scale and size are examined through the use of the envelope theorem. A major conclusion of the paper is that the level of abstraction in applying a cost function derived from a homothetic technology within a relevant range of the...