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.

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

Disinhibition of neurite growth to repair the injured adult CNS: Focusing on Nogo

Abstract.: Investigations into mechanisms that restrict the recovery of functions after an injury to the brain or the spinal cord have led to the discovery of specific neurite growth inhibitory factors in the adult central nervous system (CNS) of mammals. Blocking their growth-suppressive function resulted in disinhibition of axonal growth, i.e. growth of cultured neurons on inhibitory CNS tissue in vitro and regeneration of injured axons in vivo. The enhanced regenerative and compensatory fibre growth was often accompanied by a substantial improvement in the functional recovery after CNS injury. The first clinical studies to assess the therapeutic potential of compounds that neutralize growth inhibitors or interfere with their downstream signalling are currently in progress. This review discusses recent advances in the understanding of how the ‘founder molecule' Nogo-A and other glialderived growth inhibitors restrict the regeneration and repair of disrupted neuronal circuits, thus limiting the functional recovery after CNS injurie

Spin dependent electron transport through a magnetic resonant tunneling diode

Electron transport properties in nanostructures can be modeled, for example, by using the semiclassical Wigner formalism or the quantum mechanical Green's functions formalism. We compare the performance and the results of these methods in the case of magnetic resonant-tunneling diodes. We have implemented the two methods within the self-consistent spin-density-functional theory. Our numerical implementation of the Wigner formalism is based on the finite-difference scheme whereas for the Green's function formalism the finite-element method is used. As a specific application, we consider the device studied by Slobodskyy et all. [Phys. Rev. Lett. 90, 246601 (2003)] and analyze their experimental results. The Wigner and Green's functions formalisms give similar electron densities and potentials but, surprisingly, the former method requires much more computer resources in order to obtain numerically accurate results for currents. Both of the formalisms can successfully be used to model magnetic resonant tunneling diode structures.Comment: 13 pages and 12 figure

Electronic Aharonov-Bohm Effect Induced by Quantum Vibrations

Mechanical displacements of a nanoelectromechanical system (NEMS) shift the electron trajectories and hence perturb phase coherent charge transport through the device. We show theoretically that in the presence of a magnetic feld such quantum-coherent displacements may give rise to an Aharonov-Bohm-type of effect. In particular, we demonstrate that quantum vibrations of a suspended carbon nanotube result in a positive nanotube magnetoresistance, which decreases slowly with the increase of temperature. This effect may enable one to detect quantum displacement fluctuations of a nanomechanical device.Comment: 4 pages, 3 figure

Spin polarizations and spin Hall currents in a two-dimensional electron gas with magnetic impurities

We consider a two-dimensional electron gas in the presence of Rashba spin-orbit coupling, and study the effects of magnetic s-wave impurities and long-range non-magnetic disorder on the spin-charge dynamics of the system. We focus on voltage induced spin polarizations and their relation to spin Hall currents. Our results are obtained using the quasiclassical Green function technique, and hold in the full range of the disorder parameter $\alpha p_F\tau$.Comment: 5 pages, 2 figures. References added, minor stylistic modification

Electron transport through quantum wires and point contacts

We have studied quantum wires using the Green's function technique and the density-functional theory, calculating the electronic structure and the conductance. All the numerics are implemented using the finite-element method with a high-order polynomial basis. For short wires, i.e. quantum point contacts, the zero-bias conductance shows, as a function of the gate voltage and at a finite temperature, a plateau at around 0.7G_0. (G_0 = 2e^2/h is the quantum conductance). The behavior, which is caused in our mean-field model by spontaneous spin polarization in the constriction, is reminiscent of the so-called 0.7-anomaly observed in experiments. In our model the temperature and the wire length affect the conductance-gate voltage curves in the same way as in the measured data.Comment: 8 page

Magneto-spin Hall conductivity of a two-dimensional electron gas

It is shown that the interplay of long-range disorder and in-plane magnetic field gives rise to an out-of-plane spin polarization and a finite spin Hall conductivity of the two-dimensional electron gas in the presence of Rashba spin-orbit coupling. A key aspect is provided by the electric-field induced in-plane spin polarization. Our results are obtained first in the \textit{clean} limit where the spin-orbit splitting is much larger than the disorder broadening of the energy levels via the diagrammatic evaluation of the Kubo-formula. Then the results are shown to hold in the full range of the disorder parameter $\alpha p_F \tau$ by means of the quasiclassical Green function technique.Comment: 5 pages, 1 figur