VoroTop: Voronoi Cell Topology Visualization and Analysis Toolkit

This paper introduces a new open-source software program called VoroTop, which uses Voronoi topology to analyze local structure in atomic systems. Strengths of this approach include its abilities to analyze high-temperature systems and to characterize complex structure such as grain boundaries. This approach enables the automated analysis of systems and mechanisms previously not possible.Comment: 17 pages, 10 figure

Convective adjustment in baroclinic atmospheres

Local convection in planetary atmospheres is generally considered to result from the action of gravity on small regions of anomalous density. That in rotating baroclinic fluids the total potential energy for small scale convection contains a centrifugal as well as a gravitational contribution is shown. Convective adjustment in such an atmosphere results in the establishment of near adiabatic lapse rates of temperature along suitably defined surfaces of constant angular momentum, rather than in the vertical. This leads in general to sub-adiabatic vertical lapse rates. That such an adjustment actually occurs in the earth's atmosphere is shown by example and the magnitude of the effect for several other planetary atmospheres is estimated

The effect of the integration interval on the measurement accuracy of RMS values and powers in systems with nonsinusoidal waveforms

In this paper the possibility of errors in the measurement of average values (in particular rms values or active powers) in power systems under nonsinusoidal conditions are discussed. The errors considered are either due to the fact that the measurement time interval is not an exact multiple of the fundamental period of the voltage and current signals, or due to the presence of interharmonics or subharmonics. The errors are calculated and the results are illustrated by means of simple examples

A Sovereign Debt Model with Trade Credit and Reserves

This paper analyzes sovereign debt in an economy in which the availability of short-term trade credit reduces international trade transaction costs. The model highlights the distinction between gross and net international reserve positions. Borrowed reserves provide net wealth and liquidity services during a negotiation, as long as they are not fully attachable by creditors. Moreover, reserves strengthen the bargaining position of a country by shielding it from a cut-off from short-term trade credits thereby diminishing its degree of impatience to conclude a negotiation. We show that competitive banks do lend for the accumulation of borrowed reserves, which provide partial insurance.

Nonperturbative Matching Between Equal-Time and Lightcone Quantization

We investigate the nonperturbative relation between lightcone (LC) and standard equal-time (ET) quantization in the context of $\lambda \phi^4$ theory in $d=2$. We discuss the perturbative matching between bare parameters and the failure of its naive nonperturbative extension. We argue that they are nevertheless the same theory nonperturbatively, and that furthermore the nonperturbative map between bare parameters can be extracted from ET perturbation theory via Borel resummation of the mass gap. We test this map by using it to compare physical quantities computed using numerical Hamiltonian truncation methods in ET and LC.Comment: 22+8 pages, 10 figure

On fiber diameters of continuous maps

We present a surprisingly short proof that for any continuous map $f : \mathbb{R}^n \rightarrow \mathbb{R}^m$, if $n>m$, then there exists no bound on the diameter of fibers of $f$. Moreover, we show that when $m=1$, the union of small fibers of $f$ is bounded; when $m>1$, the union of small fibers need not be bounded. Applications to data analysis are considered.Comment: 6 pages, 2 figure