19,772 research outputs found
New class of rotating perfect fluid black holes in three dimensional gravity
We obtain a new class of rotating black holes for Einstein theory with
perfect fluid source in (2+1) dimensions. We conclude that these black hole
solutions only depend on variable angular velocity . Some examples of
these black holes are given explicitly. In particular, the unknown static black
hole in this special background is obtained. In addition, the general
properties including the horizon structure, energy conditions and equation of
state, mass and angular momentum are explained in detail.Comment: 12 pages, no figures; a few references added and typos corrected;
published versio
Renewable Resources, Capital Accumulation, and Economic Growth
This paper proposes a dynamic economic model with physical capital and renewable resources. Different from most of the neoclassical growth models with renewable resources which are based on microeconomic foundation and neglect physical capital accumulation, this study proposes a growth model with dynamics of renewable resources and physical capital accumulation. The model is a synthesis of the neoclassical growth theory and the traditional dynamic models of renewable resources with an alternative approach to household behavior. The model describes a dynamic interdependence among physical accumulation, resource change, and division of labor under perfect competition.Because of its refined economic structure, our study enables some interactions among economic variables which are not found in the existing literature on economic growth with renewable resources. We simulate the model to demonstrate the existence of equilibrium points and motion of the dynamic system. Our comparative dynamic analysis shows, for instance, that a rise in the propensity to consume the renewable resource increases the interest rate and reduces the national and production sector’s capital stocks, wage rate and level of the consumption good. Moreover,it initially reduces and then increases the capital stocks of the resource sector and the consumption and price of the renewable resource. The stock of the renewable resource is initially increased and then reduced. Finally, labor is redistributed from the production to the resource sector.renewable resource, harvesting, capital accumulation, economic growth
Anisotropy in Inflation with Non-minimal Coupling
We study a new anisotropic inflation model, with an inflaton field
nonminimally coupled with the gravity and a vector field. We find that the
anisotropic attractor solution exists not only in the weak curvature coupling
limit, but more interestingly in the strong curvature coupling limit as well.
We show that in the strong curvature coupling limit, the contribution from the
anisotropy is greatly suppressed.Comment: V2, 12 pages, 3 figures, numerical analysis adde
On Sums of Powers of Almost Equal Primes
We investigate the Waring-Goldbach problem of representing a positive integer
as the sum of th powers of almost equal prime numbers. Define
when , and put . In addition, put
, and
. Suppose that satisfies the necessary congruence conditions, and
put . We show that whenever and , and
is sufficiently large, then is represented as the sum of th powers
of prime numbers with . This conclusion
is based on a new estimate of Weyl-type specific to exponential sums having
variables constrained to short intervals.Comment: 38 pages; in version 2 we have corrected a significant oversight in
section 4 of the original version, leading to a slight adjustment of the
admissible exponents for larger
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