Molecular Dynamics Simulations of Field Emission From a Prolate Spheroidal Tip

High resolution molecular dynamics simulations with full Coulomb interactions of electrons are used to investigate field emission from a prolate spheroidal tip. The space charge limited current is several times lower than the current calculated with the Fowler-Nordheim formula. The image-charge is taken into account with a spherical approximation, which is good around the top of the tip, i.e. region where the current is generated.Comment: 6 pages, 8 figure

The Dynamics of Currency Crashes and Fundamental Reversions

This dissertation is composed of three chapters. In Chapter 1 I look at the role of real exchange rates in the asset pricing of currencies. I construct portfolios based on signals about the real exchange rate and analyze the returns of these portfolios as they relate to traditional asset pricing factors and especially how they correlate with carry trade portfolios. Deviations from long term averages of real exchange rates are found to be predictors of crash risk. I also show that there is significant information in real exchange rate signals that does not seem to be priced. In addition to demonstrating this in outright currency markets I provide evidence suggesting that this is also the case in options markets. A relationship between real exchange rates and the VIX volatility over long periods is also demonstrated. The distribution of returns depends on state variables. For currencies an important variable is the deviations of real exchange rates from their long run means and for stocks the market-to-book ratio serves a similar purpose. Chapter 2 introduces a variant of a mixture of normals that allows for dependence of this kind. The model is estimated using Markov chain Monte Carlo. The results clearly indicate conditionality on the state variables and how high prices of assets predict negative skewness (large losses) for as well as negative returns. The Icelandic financial collapse, which occurred in the fall of 2008, is without precedent. Never before in modern history has an entire financial system of a developed country collapsed so dramatically. Chapter 3 describes the country's path towards financial liberalization and the economic background that lead to an initially flourishing banking sector. In doing so the paper elaborates on the economic oversights that were made during the financial build-up of the country and how such mistakes contributed to the crash. The focus is thus on identifying the main factors that contributed to the financial collapse and on drawing conclusions about how these missteps could have been avoided. Also summarized are the mistakes that followed in the attempted rescue phase after the disaster had struck. The paper discusses these issues from a general perspective in order to provide an overview of the pitfalls that any fast growing market may be exposed to. The paper concludes that the economic collapse was primarily home-brewed and a consequence of an unbound, risk-seeking banking sector and ineffective (or non-existent) actions of the Icelandic authorities

Controlled Coulomb effects in core-shell quantum rings

We analyse theoretically the possibilities of contactless control of in-gap states formed by a pair of electrons confined in a triangular quantum ring. The in-gap states are corner-localized states associated with two electrons occupying the same corner area, and thus shifted to much higher energies than other corner states, but still they are below the energies of corner-side-localized states. We show how the energies, degeneracy and splittings between consecutive levels change with the orientation of an external electric field relatively to the polygonal cross section. We also show how absorption changes in the presence of external electric and magnetic fields.Comment: 4 pages, 2 figure