5,127 research outputs found
Goldstone radio spectrum protection
Potential electromagnetic interference to the Goldstone tracking receivers due to neighboring military installations is discussed. Coordination of the military and NASA Goldstone activities in the Mojave Desert area is seen to be an effective method to protect the Goldstone radio spectrum while maintaining compatible operations for the military and Goldstone
Routh's sphere
In this paper we show that the integral map of Rouths sphere has monodromy when the sphere becomes gyroscopically unstable This uses the nonHamiltonian monodromy of Rouths sphere has center of mass not at its geometrical center and moment of inertia tensor with two equal principal moments of inertia Moreover it rolls on a horizontal plane under the inuence of a constant vertical gravitational forc
Lie Groups and mechanics: an introduction
The aim of this paper is to present aspects of the use of Lie groups in
mechanics. We start with the motion of the rigid body for which the main
concepts are extracted. In a second part, we extend the theory for an arbitrary
Lie group and in a third section we apply these methods for the diffeomorphism
group of the circle with two particular examples: the Burger equation and the
Camassa-Holm equation
A Cantor set of tori with monodromy near a focus-focus singularity
We write down an asymptotic expression for action coordinates in an
integrable Hamiltonian system with a focus-focus equilibrium. From the
singularity in the actions we deduce that the Arnol'd determinant grows
infinitely large near the pinched torus. Moreover, we prove that it is possible
to globally parametrise the Liouville tori by their frequencies. If one
perturbs this integrable system, then the KAM tori form a Whitney smooth
family: they can be smoothly interpolated by a torus bundle that is
diffeomorphic to the bundle of Liouville tori of the unperturbed integrable
system. As is well-known, this bundle of Liouville tori is not trivial. Our
result implies that the KAM tori have monodromy. In semi-classical quantum
mechanics, quantisation rules select sequences of KAM tori that correspond to
quantum levels. Hence a global labeling of quantum levels by two quantum
numbers is not possible.Comment: 11 pages, 2 figure
PHYSIOLOGY AND ENDOCRINOLOGY SYMPOSIUM: The current status of heat shock in early embryonic survival and reproductive effi ciency
The Physiology and Endocrinology Symposium titled “The Current Status of Heat Shock in Early Embryonic Survival and Reproductive Efficiency” was held at the Joint Annual Meeting in Phoenix, AZ, July 15 to 19, 2012. In recent years, data has accumulated indicating a role for heat shock proteins (HSP) in early embryonic development and reproductive efficiency. An understanding of how these proteins influence reproductive efficiency both in vivo and in vitro could have major ramifications for production agriculture. In cattle, performance differences have been identified in Bos indicus breeds and genetic polymorphisms in HSP70 have been associated with reproductive performance (Rosenkrans et al., 2010). In Holstein cows, differences in expression of genes in the HSP40 family have been associated with improved early embryonic development in vitro, indicating that these proteins may have a greater role in reproductive efficiency than thought, even in animals not adapted to a tropical environment and not placed in a heat stress situation (Zhang et al., 2011). The speakers at this Physiology and Endocrinology Symposium were identified to address these topics based on their research
Singular reduction for proper actions
The goal of this paper is to give a simplied proof of the singular reduction theorem for a proper Hamiltonian action of a Lie group G on a connected smooth symplectic manifold P which has a coadjoint equivariant mo mentum mapping Our proof does not use the assumption that the coadjoint orbit is locally closed any local normal form or the shifting trick These were essential ingredients of the existing proo
Zeeman's monotonicity conjecture
In this paper we prove a conjecture of Zeeman about the monotonicity of the rotation number of a family of dieomorphisms φ of the first quadrant Q of R
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