141,713 research outputs found
Fingers of God
Very long wavelength universal gravitational waves cannot now produce in
clusters of galaxies velocity dispersions greater than that which these systems
would possess if they were expanding with the Universe, if the Universe is not
younger than yr and Hubble's constant is not less than 50 km/sec/
Mpc. A diagram shows that actual velocity dispersions are significantly greater
than this limit.Comment: Published long before the advent of large-scale redshift surveys, as
"A Critique of Rees's Theory of Primordial Gravitational Radiation", this
paper includes the first presentation of what has come to be known as the
fingers-of-god effect. The effect is mentioned several hundred times in
arXive papers, rarely with a wrong attribution, usually with none at al
Inflating and Deflating Hot Jupiters: Coupled Tidal and Thermal Evolution of Known Transiting Planets
We examine the radius evolution of close-in giant planets with a planet
evolution model that couples the orbital-tidal and thermal evolution. For 45
transiting systems, we compute a large grid of cooling/contraction paths
forward in time, starting from a large phase space of initial semi-major axes
and eccentricities. Given observational constraints at the current time for a
given planet (semi-major axis, eccentricity, and system age) we find possible
evolutionary paths that match these constraints, and compare the calculated
radii to observations. We find that tidal evolution has two effects. First,
planets start their evolution at larger semi-major axis, allowing them to
contract more efficiently at earlier times. Second, tidal heating can
significantly inflate the radius when the orbit is being circularized, but this
effect on the radius is short-lived thereafter. Often circularization of the
orbit is proceeded by a long period while the semi-major axis slowly decreases.
Some systems with previously unexplained large radii that we can reproduce with
our coupled model are HAT-P-7, HAT-P-9, WASP-10, and XO-4. This increases the
number of planets for which we can match the radius from 24 (of 45) to as many
as 35 for our standard case, but for some of these systems we are required to
be viewing them at a special time around the era of current radius inflation.
This is a concern for the viability of tidal inflation as a general mechanism
to explain most inflated radii. Also, large initial eccentricities would have
to be common. We also investigate the evolution of models that have a floor on
the eccentricity, as may be due to a perturber. In this scenario we match the
extremely large radius of WASP-12b. (Abridged)Comment: 18 pages, 14 figures, 2 tables, Accepted for publication in Ap
Comment on "Classical and Quantum Interaction of the Dipole"
In this paper I have presented Comment on Anandan's paper (J. Anandan, Phys.
Rev. Lett. 85, 1354 (2000)) [hep-th/9910018].Comment: 1 page, revtex; small changes, mainly typos, according to the
published version in Phys. Rev. Let
USDA-ARS Hydrology Laboratory MISWG Hydrology Workshop
Current research being conducted in remote sensing techniques for measuring hydrologic parameters and variables deals with runoff curve numbers (CN), evapotranspiration (ET), and soil moisture. The CN and ET research utilizes visible and infrared measurements. Soil moisture investigations focus on the microwave region of the electromagnetic spectrum
A legislative bargaining approach to earmarked public expenditures
This paper develops a model of legislative spending in which revenues can be spent through earmarks or a general fund. Legislative choice is modeled as a Baron and Ferejohn style legislative bargaining game. The novel approach is to model the bargaining process as a two-stage game reflecting the reality that earmarked expenditures precede general fund appropriations. This drives the result that all revenue is spent by way of earmarking leaving no revenue in the general fund.Earmarking, legislative bargaining, public goods.
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