19,391 research outputs found
A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet
The group velocity of light in material around the AGN jet is acquiescently
one (c as a unit), but this is only a hypothesis. Here, we re-derive apparent
superluminal and Doppler formulas for the general case (it is assumed that the
group velocity of light in the uniform and isotropic medium around a jet (a
beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010)
thought that there may be dense clouds around AGN jet base), and show that the
group velocity of light close to one could seriously affect apparent
superluminal phenomena and Doppler effect in the AGN jet (when the viewing
angle and Lorentz factor take some appropriate values).Comment: 4 pages, 2 figures, new version accepted for publication in Journal
of Astrophysics and Astronom
On the connectedness of planar self-affine sets
In this paper, we consider the connectedness of planar self-affine set
arising from an integral expanding matrix with
characteristic polynomial and a digit set
. The necessary and sufficient conditions only
depending on are given for the to be connected.
Moreover, we also consider the case that is non-consecutively
collinear.Comment: 18 pages; 18 figure
Microscopic Realization of 2-Dimensional Bosonic Topological Insulators
It is well known that a Bosonic Mott insulator can be realized by condensing
vortices of a bo- son condensate. Usually, a vortex becomes an anti-vortex (and
vice-versa) under time reversal symmetry, and the condensation of vortices
results in a trivial Mott insulator. However, if each vortex or anti-vortex
interacts with a spin trapped at its core, the time reversal transformation of
the composite vortex operator will contain an extra minus sign. It turns out
that such a composite vortex condensed state is a bosonic topological insulator
(BTI) with gapless boundary excitations protected by
symmetry. We point out that in BTI, an external flux monodromy defect
carries a Kramers doublet. We propose lattice model Hamiltonians to realize the
BTI phase, which might be implemented in cold atom systems or spin-1 solid
state systems.Comment: 5 pages + supplementary materia
An asymmetrical synchrotron model for knots in the 3C 273 jet
To interpret the emission of knots in the 3C 273 jet from radio to X-rays, we
propose a synchrotron model in which, owing to the shock compression effect,
the injection spectra from a shock into the upstream and downstream emission
regions are asymmetric. Our model could well explain the spectral energy
distributions of knots in the 3C 273 jet, and predictions regarding the knots
spectra could be tested by future observations.Comment: 9 pages, 1 figure, 1 table, new version accepted for publication in
Ap
A Ricardian Model with Endogenous Comparative Advantage and Endogenous Trade Policy Regimes
This paper develops a general equilibrium model with transaction costs and endogenous and exogenous comparative advantages. In the model, the governments are allowed to choose between tariff war, tariff negotiation, and laissez faire regimes. The model shows that the level of division of labor and the volume of trade increase as transaction conditions improve. In the process of moving to a high level of division of labour, a country may receive more gains from trade even if its terms of trade deteriorate. This is because an expansion of the network size of division of labour can generate productivity gains that outweigh the adverse effect of the terms of trade deterioration. When a high level of division of labor occurs in general equilibrium, if both countries play a Nash tariff game, a tariff war may break out, which can dissipate all the gains from trade. Facing this risk, all governments would prefer trade negotiations to a trade war. A Nash tariff negotiation would result in zero tariff rates. If a medium level of division of labor occurs in general equilibrium, then unilateral tariff protection and unilateral laissez faire policies would coexist. The result provides a plausible story about the evolution of trade policy regimes, and highlights the importance of trade negotiations in achieving trade liberalization.inframarginal analysis of trade theory, Ricardo model, dual structure, underdevelopment
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