An optimal internet location strategy for markets with different tax rates

The traditional view that a high sales tax rate reduces trade by driving a wedge between the purchase and sale price may not apply to internet commerce for two reasons. The first reason is that the sales tax paid by buyers purchasing via the internet is determined by the tax rate in the region of the buyer. The second reason is that a high sales tax may lower the before-tax price if sellers absorb part of the tax. Taken together, this implies that internet distributors may profitably target customers in regions with low tax rates by locating their selling addresses in high tax regions. Consequently the optimal marketing strategy for a global internet distributor may include siting selling locations in regions with high tax rates in order to target customers in regions with low tax rates. An empirical analysis of the European car market suggests that this is more than a remote theoretical possibility by demonstrating that the before-tax prices recommended by manufacturers for new cars are lower in high tax countries

Recent experimental data and the size of the quark in the Constituent Quark Model

We use the Constituent Quark Model (CQM) to describe CDF data on double parton cross section and HERA data on the $J / \Psi$ ratio cross section of elastic and inelastic diffractive productions. Our estimate shows that the radius of the constituent quark turns out to be rather small, $R^2_{quark} \approx 0.1 Gev^{-2}$, in accordance with the assumption on which CQM is based.Comment: 21 pages, 19 figure

Why charges go to the surface: a generalized Thomson problem

We study a generalization of a Thomson problem of n particles confined to a sphere and interacting by a 1/r^g potential. It is found that for g \le 1 the electrostatic repulsion expels all the charges to the surface of the sphere. However for g>1 and n>n_c(g) occupation of the bulk becomes energetically favorable. It is curious to note that the Coulomb law lies exactly on the interface between these two regimes

Simplified half-life methods for the analysis of kinetic data

The analysis of reaction rate data has as its goal the determination of the order rate constant which characterize the data. Chemical reactions with one reactant and present simplified methods for accomplishing this goal are considered. The approaches presented involve the use of half lives or other fractional lives. These methods are particularly useful for the more elementary discussions of kinetics found in general and physical chemistry courses

Dynamics of Black Hole Pairs II: Spherical Orbits and the Homoclinic Limit of Zoom-Whirliness

Spinning black hole pairs exhibit a range of complicated dynamical behaviors. An interest in eccentric and zoom-whirl orbits has ironically inspired the focus of this paper: the constant radius orbits. When black hole spins are misaligned, the constant radius orbits are not circles but rather lie on the surface of a sphere and have acquired the name "spherical orbits". The spherical orbits are significant as they energetically frame the distribution of all orbits. In addition, each unstable spherical orbit is asymptotically approached by an orbit that whirls an infinite number of times, known as a homoclinic orbit. A homoclinic trajectory is an infinite whirl limit of the zoom-whirl spectrum and has a further significance as the separatrix between inspiral and plunge for eccentric orbits. We work in the context of two spinning black holes of comparable mass as described in the 3PN Hamiltonian with spin-orbit coupling included. As such, the results could provide a testing ground of the accuracy of the PN expansion. Further, the spherical orbits could provide useful initial data for numerical relativity. Finally, we comment that the spinning black hole pairs should give way to chaos around the homoclinic orbit when spin-spin coupling is incorporated.Comment: 16 pages, several figure

Coulomb Glasses: A Comparison Between Mean Field and Monte Carlo Results

Recently a local mean field theory for both eqilibrium and transport properties of the Coulomb glass was proposed [A. Amir et al., Phys. Rev. B 77, 165207 (2008); 80, 245214 (2009)]. We compare the predictions of this theory to the results of dynamic Monte Carlo simulations. In a thermal equilibrium state we compare the density of states and the occupation probabilities. We also study the transition rates between different states and find that the mean field rates underestimate a certain class of important transitions. We propose modified rates to be used in the mean field approach which take into account correlations at the minimal level in the sense that transitions are only to take place from an occupied to an empty site. We show that this modification accounts for most of the difference between the mean field and Monte Carlo rates. The linear response conductance is shown to exhibit the Efros-Shklovskii behaviour in both the mean field and Monte Carlo approaches, but the mean field method strongly underestimates the current at low temperatures. When using the modified rates better agreement is achieved