A Study of Non-Neutral Networks with Usage-based Prices

Hahn and Wallsten wrote that network neutrality "usually means that broadband service providers charge consumers only once for Internet access, do not favor one content provider over another, and do not charge content providers for sending information over broadband lines to end users." In this paper we study the implications of non-neutral behaviors under a simple model of linear demand-response to usage-based prices. We take into account advertising revenues and consider both cooperative and non-cooperative scenarios. In particular, we model the impact of side-payments between service and content providers. We also consider the effect of service discrimination by access providers, as well as an extension of our model to non-monopolistic content providers

Phase diagram of the one-dimensional Holstein model of spinless fermions

The one-dimensional Holstein model of spinless fermions interacting with dispersionless phonons is studied using a new variant of the density matrix renormalisation group. By examining various low-energy excitations of finite chains, the metal-insulator phase boundary is determined precisely and agrees with the predictions of strong coupling theory in the anti-adiabatic regime and is consistent with renormalisation group arguments in the adiabatic regime. The Luttinger liquid parameters, determined by finite-size scaling, are consistent with a Kosterlitz-Thouless transition.Comment: Minor changes. 4 pages, 4 figures. To appear in Physical Review Letters 80 (1998) 560

Density Matrix Renormalization Group Applied to the Ground State of the XY-Spin-Peierls System

We use the density matrix renormalization group (DMRG) to map out the ground state of a XY-spin chain coupled to dispersionless phonons of frequency $\omega$. We confirm the existence of a critical spin-phonon coupling $_c\propto \omega ^{0.7}$ for the onset of the spin gap bearing the signature of a Kosterlitz-Thouless transition. We also observe a classical-quantum crossover when the spin-Peierls gap $\Delta$ is of order $$. In the classical regime, $\Delta >\omega$, the mean-field parameters are strongly renormalized by non-adiabatic corrections. This is the first application of the DMRG to phonons.Comment: 10 pages, 5 figures. To be published in PR

Ground-state properties of the One-dimensional Kondo Lattice at partial Band-filling

We compute the magnetic structure factor, the singlet correlation function and the momentum distribution of the one-dimensional Kondo lattice model at the density $\rho =0.7$. The density matrix-renormalization group method is used. We show that in the weak-coupling regime, the ground state is paramagnetic. We argue that a Luttinger liquid description of the model in this region is consistent with our calculations . In the strong-coupling regime, the ground state becomes ferromagnetic. The conduction electrons show a spinless-fermion like behavior.Comment: 8 pages, Latex, 5 figures included, to be published in PRB (Rapid Communications

Quantum Chaos Versus Classical Chaos: Why is Quantum Chaos Weaker?

We discuss the questions: How to compare quantitatively classical chaos with quantum chaos? Which one is stronger? What are the underlying physical reasons

The CO2 Content of Consumption Across US Regions: A Multi-Regional Input-Output (MRIO) Approach

We improve on existing estimates of the carbon dioxide (CO2) content of consumption across regions of the United States. Using a multi-regional input-output (MRIO) framework, we estimate the direct and indirect CO2 emissions attributable to domestically and internationally imported goods. We include estimates of bilateral trade between US states as well as between individual states and international countries and regions. This report presents two major findings. First, attributing emissions to states on a consumption versus a production basis leads to very different state-level emissions responsibilities; for example, when attributed on a consumption basis, California's per capita emissions are over 25 percent higher than when attributed on a production basis. Second, when attributing emissions on a consumption basis, heterogeneity of emissions across trading partners significantly affects emissions intensity. These findings have important implications for evaluating the potential distributional impacts of national climate policies, as well as for understanding differing incentives to implement state- or regional-level policies