On localization effects in underdoped cuprates

We comment on transport experiments in underdoped LaSrCuO in the non-superconducting phase. The temperature dependence of the resistance strongly resembles what is expected from standard localization theory. However this theory fails, when comparing with experiments in more detail.Comment: 8 pages, to be published in J. of Superconductivit

Density functional theory for a model quantum dot: Beyond the local-density approximation

We study both static and transport properties of model quantum dots, employing density functional theory as well as (numerically) exact methods. For the lattice model under consideration the accuracy of the local-density approximation generally is poor. For weak interaction, however, accurate results are achieved within the optimized effective potential method, while for intermediate interaction strengths a method combining the exact diagonalization of small clusters with density functional theory is very successful. Results obtained from the latter approach yield very good agreement with density matrix renormalization group studies, where the full Hamiltonian consisting of the dot and the attached leads has to be diagonalized. Furthermore we address the question whether static density functional theory is able to predict the exact linear conductance through the dot correctly - with, in general, negative answer.Comment: 8 page

Non-linear conductivity and quantum interference in disordered metals

We report on a novel non-linear electric field effect in the conductivity of disordered conductors. We find that an electric field gives rise to dephasing in the particle-hole channel, which depresses the interference effects due to disorder and interaction and leads to a non-linear conductivity. This non-linear effect introduces a field dependent temperature scale $T_E$ and provides a microscopic mechanism for electric field scaling at the metal-insulator transition. We also study the magnetic field dependence of the non-linear conductivity and suggest possible ways to experimentally verify our predictions. These effects offer a new probe to test the role of quantum interference at the metal-insulator transition in disordered conductors.Comment: 5 pages, 3 figure

Ageing and pensions in the Euro Area Survey and projection results

Population ageing will impose a significant burden on European fiscal balances, in particular through pay-as-you-go pension systems. This study presents an independent estimate of this burden for the euro area, and quantifies the impact of two reform scenarios. Based on widely used, but optimistic assumptions, the present value of future pension deficits through 2050 is estimated at 51percent of GDP, adding to the current average explicit debt stock of around 67 percent of GDP. In this calculation, the deficits currently incurred by many pension systems as revenues fall short of expenditures, are not included. Viable parametric reforms represent no durable solution to alleviate the burden sufficiently, as they can balance pension systems at best temporarily. A comprehensive reform, including reforms of current systems, and a move towards partial funding, is found to ensure permanent financial viability of the public pension system.Pensions&Retirement Systems,Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Economic Stabilization

Endogenous Growth, Public Capital, and the Convergence of Regional Manufacturing Industries

Several explanations can be offered for the unbalanced growth of U.S. regional manufacturing industries in the decades after World War II. The convergence hypothesis suggests that the success of the South in catching up to the Northeast and Midwest should be understood by analogy with the economic success of Japan and the rest of the G-7 in closing the gap relative to the U.S. as a whole. Endogenous growth theory, on the other hand, assigns a central role to capital formation, broadly defined. A variant of endogenous growth theory focuses on investments in public infrastructure as a key determinant of regional growth. Finally, traditional location theory stresses the evolution of regional supply and demand and the role of economies of scale and agglomeration. This paper compares these alternative explanations of U.S. regional growth by testing their predictions about the productive efficiency of regional manufacturing industries. We find little evidence that technological convergence explains the regional evolution of U.S. manufacturing industry, or that endogenous growth was an important factor. We also find little evidence that public capital externalities played a significant role in explaining the relative success of industries in the South and West. The main engine of differential regional manufacturing growth over the period 1970-86 seems to be inter-regional flows of capital and labor. The growth of multifactor productivity is essentially uniform across regions, although there is some variation in the initial levels of efficiency.

Income Originating in the State and Local Sector

In this paper we develop an accounting framework for the state and local sector which is consistent with the accounting framework for the private sector of the economy. We show that the public sector capital stock generates an imputed return which takes the form of a reduction in local taxes and that failure to recognize this income distorts the measurement of the output of this sector, confuses the debate over federal tax reform, and hides the distinction between general subsidies for capital formation. Our implementation of those accounts for the 1959- 1985 period indicates that current national income accounting procedures misstate the amount of income originating in the state and local sector; in recent years this misstatement has been on the order of $100 billion. We also show that the state and local sector is one of the more capital intensive sectors of the economy.

(WP 2017-02) The Great Recession and Public Education

We examine the impact of the Great Recession on K-12 education finance and employment and generate five key results. First, nearly 300,000 school employees lost their jobs. Second, schools that were heavily dependent financially on state governments were particularly vulnerable to the recession. Third local revenues from the property tax actually increased during the recession, primarily because millage rates rose in response to declining property values. Fourth, inequality in school spending rose sharply during the Great Recession. Fifth, the federal government’s efforts to shield education from some of the worst effects of the recession achieved their major goal

Mesoscopic Mechanical Resonators as Quantum Non-Inertial Reference Frames

An atom attached to a micrometer-scale wire that is vibrating at a frequency of 100 MHz and with displacement amplitude 1 nm experiences an acceleration magnitude 10^9 ms^-2, approaching the surface gravity of a neutron star. As one application of such extreme non-inertial forces in a mesoscopic setting, we consider a model two-path atom interferometer with one path consisting of the 100 MHz vibrating wire atom guide. The vibrating wire guide serves as a non-inertial reference frame and induces an in principle measurable phase shift in the wave function of an atom traversing the wire frame. We furthermore consider the effect on the two-path atom wave interference when the vibrating wire is modeled as a quantum object, hence functioning as a quantum non-inertial reference frame. We outline a possible realization of the vibrating wire, atom interferometer using a superfluid helium quantum interference setup.Comment: Published versio