On the existence of effective potentials in time-dependent density functional theory

We investigate the existence and properties of effective potentials in time-dependent density functional theory. We outline conditions for a general solution of the corresponding Sturm-Liouville boundary value problems. We define the set of potentials and v-representable densities, give a proof of existence of the effective potentials under certain restrictions, and show the set of v-representable densities to be independent of the interaction.Comment: 13 page

Supercontinuum generation in media with sign-alternated dispersion

When an ultrafast optical pulse with high intensity is propagating through transparent material a supercontinuum can be coherently generated by self-phase modulation, which is essential to many photonic applications in fibers and integrated waveguides. However, the presence of dispersion causes stagnation of spectral broadening past a certain propagation length, requiring an increased input peak power for further broadening. We present a concept to drive supercontinuum generation with significantly lower input power by counteracting spectral stagnation via alternating the sign of group velocity dispersion along the propagation. We demonstrate the effect experimentally in dispersion alternating fiber in excellent agreement with modeling, revealing almost an order of magnitude reduced peak power compared to uniform dispersion. Calculations reveal a similar power reduction also with integrated optical waveguides, simultaneously with a significant increase of flat bandwidth, which is important for on-chip broadband photonics.Comment: Main text and supplementary informatio

The viscosity of dacitic liquids measured at conditions relevant to explosive arc volcanism: determing the influence of temperature, silicate composition, and dissolved volatile content

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (February 7, 2007)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2006.Dissertations, Academic -- University of Missouri--Columbia -- Geological sciences.Viscosity can control various magmatic processes and varies by orders of magnitude as a function of temperature, composition and dissolved volatiles. There is no predictive model for the viscosity of dacitic liquids, which are involved in explosive volcanism. This study investigated the effects of variable composition and water content on dacitic liquids. Ten dacitic glasses were synthesized with varying degrees of polymerization. Hydrous glasses were made with water contents varying up to 5 wt.%. The viscosity was measured using parallel plate and concentric cylinder viscometry. TVF equations, of the form log [eta] = A + B/(T-C), allow prediction of hydrous liquid viscosities at magmatic temperatures. At 1100K, liquids containing 1 and 5 wt.% dissolved water are about 5 and 7 orders of magnitude less viscous than anhydrous liquids, respectively. The results demonstrate that varying polymerization state of the liquids has a smaller effect on viscosity than water content and temperature

Tuning the scattering length with an optically induced Feshbach resonance

We demonstrate optical tuning of the scattering length in a Bose-Einstein condensate as predicted by Fedichev {\em et al.} [Phys. Rev. Lett. {\bf 77}, 2913 (1996)]. In our experiment atoms in a $^{87}$Rb condensate are exposed to laser light which is tuned close to the transition frequency to an excited molecular state. By controlling the power and detuning of the laser beam we can change the atomic scattering length over a wide range. In view of laser-driven atomic losses we use Bragg spectroscopy as a fast method to measure the scattering length of the atoms.Comment: submitted to PRL, 5 pages, 5 figure

When evaluating a president’s economic performance, voters look across their entire record – not just the recent short term.

How do voters decide? Do they take everything into account that happened over the government’s time in office? Or do they rely only on the recent past? Timothy Hellwig and Dani M. Marinova report that voters, counter to conventional understandings, are not so short-sighted. Their analysis of vote intentions in the run up to the 2012 presidential election reveals that voters are no more accurate in assessing economic performance over the short term compared to the long term. Voters, it turns out, are more misinformed than short-sighted

Discrete-time approximations of the Holmström-Milgrom Brownian-motion model of intertemporal incentive provision

This paper studies the relation between multi-period discrete-time and continuous-time principal-agent models. We explicitly derive the continuous-time model as a limit of discrete-time models with ever shorter periods and show that the optimal incentive scheme in the continuous model, which is linear in accounts, can be approximated by a sequence of optimal incentive schemes in the discrete models. For a variant of the discrete-time model in which the principal observes only total profits at the end of the last period and where the agent can destroy profits unnoticed we show, that if the length of each period is sufficiently small, then an incentive scheme that is linear in total profits is approximately optimal

Fallacies, Irrelevant Facts, and Myths in the Discussion of Capital Regulation: Why Bank Equity is Not Expensive

We examine the pervasive view that “equity is expensive,” which leads to claims that high capital requirements are costly and would affect credit markets adversely. We find that arguments made to support this view are either fallacious, irrelevant, or very weak. For example, the return on equity contains a risk premium that must go down if banks have more equity. It is thus incorrect to assume that the required return on equity remains fixed as capital requirements increase. It is also incorrect to translate higher taxes paid by banks to a social cost. Policies that subsidize debt and indirectly penalize equity through taxes and implicit guarantees are distortive. Any desirable public subsidies to banks’ activities should be given directly and not in ways that encourage leverage. Finally, suggestions that high leverage serves a necessary disciplining role are based on inadequate theory lacking empirical support. We conclude that bank equity is not socially expensive, and that high leverage is not necessary for banks to perform all their socially valuable functions, including lending, taking deposits and issuing money-like securities. To the contrary, better capitalized banks suffer fewer distortions in lending decisions and would perform better. The fact that banks choose high leverage does not imply that this is socially optimal, and, viewed from an ex ante perspective, high leverage may not even be privately optimal for banks. Setting equity requirements significantly higher than the levels currently proposed would entail large social benefits and minimal, if any, social costs. Approaches based on equity dominate alternatives, including contingent capital. To achieve better capitalization quickly and efficiently and prevent disruption to lending, regulators must actively control equity payouts and issuance. If remaining challenges are addressed, capital regulation can be a powerful tool for enhancing the role of banks in the economy.capital regulation, financial institutions, capital structure, too big to fail, systemic risk, bank equity, contingent capital, Basel.

DEVELOPMENT OF VIRTUAL EVENT MARKETING

In the last few years the Pichia pastoris expression system has been gaining more and more interest for the expression of recombinant proteins. Many groups have employed fermentation technology in their investigations because the system is fairly easy to scale up and suitable for the production in the milligram to gram range. A large number of heterologous proteins from different sources has been expressed, but the fermentation process technology has been investigated to a lesser extent. A large number of fermentations are carried out in standard bioreactors that may be insufficiently equipped to meet the demands of high-cell-density fermentations of methylotrophic yeasts. In particular, the lack of on-line methanol analysis leads to fermentation protocols that may impair the optimal expression of the desired products. We have used a commercially available methanol sensor to investigate in detail the effects of supplementary glycerol feeding while maintaining a constant methanol concentration during the induction of a Mut+ strain of Pichia pastoris. Specific glycerol feed rates in the range of 38-4.2 mg × g(exp -1) × h(exp -1) (mg glycerol per gram fresh weight per hour) were investigated. Expression of the recombinant scFv antibody fragment was only observed at specific feed rates below 6 mg × g(exp -1) × h(exp -1). At low specific feed rates, growth was even lower than with methanol as the sole carbon source and the harvest expression level of the scFv was only half of that found in the control fermentation. These results show that glycerol inhibits expression driven by the AOX1 promoter even at extremely limited availability and demonstrate the benefits of on-line methanol control in Pichia fermentation research

An Economic Approach to Article 82

This report argues in favour of an economics-based approach to Article 82, in a way similar to the reform of Article 81 and merger control. In particular, we support an effects-based rather than a form-based approach to competition policy. Such an approach focuses on the presence of anti-competitive effects that harm consumers, and is based on the examination of each specific case, based on sound economics and grounded on facts