The Puzzling Collapse of Electronic Sliding Friction on a Superconductor Surface

In a recent paper [Phys. Rev. Lett. 80 (1998) 1690], Krim and coworkers have observed that the friction force, acting on a thin physisorbed layer of N_2 sliding on a lead film, abruptly decreases by a factor of ~2 when the lead film is cooled below its superconductivity transition temperature. We discuss the possible mechanisms for the abruptness of the sliding friction drop, and also discuss the relevance of these results to the problem of electronic friction.Comment: 5 pages, no figure

Photoheliograph requirements for a spectrograph, November 1967 - June 1968

Preliminary design requirements and constraints for ATM photoheliograp

Debt, Cash Flow and Inflation Incentives: A Swedish Example

The fiscal gains from, and hence the political incentives to, an increase in inflation rate of ten percentage points may be substantial: with Swedish data from 1994, these gains would have been an annual real flow of 3-4 percent of GDP, or a capitalized value of nearly 100 percent of GDP. They would mainly have arisen from the nominalistic features of the tax and transfer systems rather than from the traditional sources: seignorage and real depreciation of the public debt. The welfare costs of such an inflation increase would have been even larger, however, and would thus have reduced net welfare. Possible institutional reforms, aimed at making the political costs of inflation more equal to the social costs, are presented and discussed

Transient localization in the kicked Rydberg atom

We investigate the long-time limit of quantum localization of the kicked Rydberg atom. The kicked Rydberg atom is shown to possess in addition to the quantum localization time $\tau_L$ a second cross-over time $t_D$ where quantum dynamics diverges from classical dynamics towards increased instability. The quantum localization is shown to vanish as either the strength of the kicks at fixed principal quantum number or the quantum number at fixed kick strength increases. The survival probability as a function of frequency in the transient localization regime $\tau_L<t<t_D$ is characterized by highly irregular, fractal-like fluctuations