Disorder and interference: localization phenomena

The specific problem we address in these lectures is the problem of transport and localization in disordered systems, when interference is present, as characteristic for waves, with a focus on realizations with ultracold atoms.Comment: Notes of a lecture delivered at the Les Houches School of Physics on "Ultracold gases and quantum information" 2009 in Singapore. v3: corrected mistakes, improved script for numerics, Chapter 9 in "Les Houches 2009 - Session XCI: Ultracold Gases and Quantum Information" edited by C. Miniatura et al. (Oxford University Press, 2011

Global financial crisis, liquidity pressure in stock markets and efficiency of central bank interventions

In this article, we investigate the hypothesis of efficiency of central bank intervention policies within the current global financial crisis. We firstly discuss the major existing interventions of central banks around the world to improve liquidity, restore investor confidence and avoid a global credit crunch. We then evaluate the short-term efficiency of these policies in the context of the UK, the US and the French financial markets using different modelling techniques. On the one hand, the impulse response functions in a Structural Vector Autoregressive (SVAR) model are used to apprehend stock market reactions to central bank policies. On the other hand, since these reactions are likely to be of an asymmetric and nonlinear nature, a two-regime Smooth Transition Regression-Generalized Autoregressive Conditional Heteroscedasticity (STR-GARCH) model is estimated to explore the complexity and nonlinear responses of stock markets to exogenous shifts in monetary policy shocks. As expected, our findings show strong repercussions from interest rate changes on stock markets, indicating that investors keep a close eye on central bank intervention policies to make their trading decisions. The stock markets lead monetary markets, however, when central banks are slow to adjust their benchmark interest rates

The Dust Trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006

We report on observations of the dust trail of comet 67P/Churyumov-Gerasimenko (CG) in visible light with the Wide Field Imager at the ESO/MPG 2.2m telescope at 4.7 AU before aphelion, and at 24 micron with the MIPS instrument on board the Spitzer Space Telescope at 5.7 AU both before and after aphelion. The comet did not appear to be active during our observations. Our images probe large dust grains emitted from the comet that have a radiation pressure parameter beta<0.01. We compare our observations with simulated images generated with a dynamical model of the cometary dust and constrain the emission speeds, size distribution, production rate and geometric albedo of the dust. We achieve the best fit to our data with a differential size distribution exponent of -4.1, and emission speeds for a beta=0.01 particle of 25 m/s at perihelion and 2 m/s at 3 AU. The dust production rate in our model is on the order of 1000 kg/s at perihelion and 1 kg/s at 3 AU, and we require a dust geometric albedo between 0.022 and 0.044. The production rates of large (>10 micron) particles required to reproduce the brightness of the trail are sufficient to also account for the coma brightness observed while the comet was inside 3 AU, and we infer that the cross-section in the coma of CG may be dominated by grains of the order of 60-600 micron.Comment: 79 pages, 13 figures, 6 tables. Accepted for publication in Icaru

Energy prices, production

This paper investigates economic incentives influencing the adoption of energy saving technology by industry, namely, CHP in UK and Dutch manufacturing sectors. The empirical analysis is based on a cross sectional time series econometric model, and examines how industrial output and historical increases in the price of electricity relative to gas prices, spark the diffusion of CHP. Production and price elasticities are estimated across heterogeneous industrial groups. Using data for 13 manufacturing sectors the model shows that fuel cost savings and industry output impact significantly on CHP uptake. Model outcomes are found to differ depending on the period of estimation and the estimation period is key in determining the impact of gas price and purchased power prices on adoption of CHP

Multiple scattering of light in cold atomic clouds with a magnetic field

Starting from a microscopic theory for atomic scatterers, we describe the scattering of light by a single atom and study the coherent propagation of light in a cold atomic cloud in the presence of a magnetic field B in the mesoscopic regime. Non-pertubative expressions in B are given for the magneto-optical effects and optical anisotropy. We then consider the multiple scattering regime and address the fate of the coherent backscattering (CBS) effect. We show that, for atoms with nonzero spin in their ground state, the CBS interference contrast can be increased compared to its value when B=0, a result at variance with classical samples. We validate our theoretical results by a quantitative comparison with experimental data.Comment: 16 pages, 7 figure

Variety and regional economic growth in the Netherlands

In economic theory, one can distinguish between variety as a source of regional knowledge spillovers, called Jacobs externalities, and variety as a portfolio protecting a region from external shocks. We argue that Jacobs externalities are best measured by related variety (within sectors), while the portfolio argument is better captured by unrelated variety (between sectors). We introduce a methodology based on entropy measures to compute related variety and unrelated variety. Using data at the COROP level for the period 1996-2002, we find that Jacobs externalities enhance employment growth, while unrelated variety dampens unemployment growth. Productivity growth, by contrast, can be explained by traditional determinants including investments and R&D expenditures. Implications for regional policy in The Netherlands follow.evolutionary economic geography, new economic geography, economic variety