Mechanism Design with Renegotiation and Costly Messages

The paper studies a general model of hold-up in a setting encompassing the models of Segal (1999) and Che and Hausch (1999) among others. It is shown that if renegotiation is modelled as an infinite-horizon non-cooperative bargaining game then, with a simple initial contract, an efficient equilibrium will generally exist. The contract gives authority to one party to set the terms of trade and gives the other party a non-expiring option to trade at these terms. The difference from standard results arises because the existing contract ensures that the renegotiation game has multiple equilibria; the multiplicity of continuation equilibria can be used to enforce efficient investment

Kinetic studies of the dissolution of copper in ferric chloride solutions

M.S.Walter H. Burrow

Comment on "Dynamic Wetting by liquids of different viscosity", by T.D. Blake and Y.D. Shikhmurzaev

We comment on a recent theory of dynamic wetting, that is based directly upon a model for interface formation, introduced by Shikhmurzaev. We argue that the treatment of surface tension and its relaxation, inherent in the original model, is physically flawed.Comment: comment submitted to Journal of Colloid and Interface Scienc

A Hermit in Suburbia

Solo exhibition. This exhibition included paintings, animations and drawings and was part of a long-term enquiry into the ways in the largely Western and urban-based population perceive and encounter the natural world. This show focused on the ornamental hermit, a curious invention of the English Landscape Garden tradition. These were not real hermits, but were employed to live within large estates to provide human subjects for their picturesque grounds, for the amusement of the owner and guests alike. The hermits in this exhibition have been redeployed to the contemporary British suburbs asking the viewer to think anew about our relationship with nature in these ‘hybridised spaces’ whilst considering ideas about the wilderness, retreat and solitude

Quantifying density fluctuations in water at a hydrophobic surface: evidence for critical drying

Employing smart Monte Carlo sampling techniques within the grand canonical ensemble, we investigate the properties of water at a model hydrophobic substrate. By reducing the strength of substrate-water attraction we find that fluctuations in the local number density, quantified by a rigorous definition of the local compressibility $\chi(z)$, increase rapidly for distances $z$ within $1$ or $2$ molecular diameters from the substrate as the degree of hydrophobicity, measured by the macroscopic contact angle $\theta$, increases. Our simulations provide evidence for a continuous (critical) drying transition as the substrate-water interaction becomes very weak: $\cos(\theta)\to -1$. We speculate that the existence of such a transition might account for earlier simulation observations of strongly enhanced density fluctuations

Reputational Externality and Self-Regulation

Professional associations and other producer groups often complain that their reputation is damaged by other groups providing a similar but lower-quality service and that the latter should be regulated. We examine the conditions under which a common regulatory regime can induce Pareto-improvements by creating a common reputation for quality among heterogeneous producers, when the regulator cannot commit to a given quality. A common reputation can be created only if the groups are not too different and if marginal cost is declining. High cost groups and small groups benefit most from forming a common regime

The Local Compressibility of Liquids near Non-Adsorbing Substrates: A Useful Measure of Solvophobicity and Hydrophobicity?

We investigate the suitability of the local compressibility chi(z) as a measure of the solvophobicity or hydrophobicity of a substrate. Defining the local compressibility as the derivative of the local one-body density w.r.t. the chemical potential at fixed temperature, we use density functional theory (DFT) to calculate chi(z) for a model fluid, close to bulk liquid-gas coexistence, at various planar substrates. These range from a `neutral' substrate with a contact angle of approximately 90 degrees, which favours neither the liquid nor the gas phase, to a very solvophobic, purely repulsive substrate which exhibits complete drying (i.e. contact angle 180 degrees). We find that the maximum in the local compressibility, which occurs within one-two molecular diameters of the substrate, and the integrated quantity chi_ex (the surface excess compressibility, defined below) both increase rapidly as the contact angle increases and the substrate becomes more solvophobic. The local compressibility provides a more pronounced indicator of solvophobicity than the density depletion in the vicinity of the surface which increases only weakly with increasing contact angle. When the fluid is confined in a parallel slit with two identical solvophobic walls, or with competing solvophobic and solvophilic walls, chi(z) close to the solvophobic wall is altered little from that at the single substrate. We connect our results with simulation studies of water near to hydrophobic surfaces exploring the relationship between chi(z) and fluctuations in the local density and between chi_ex and the mean-square fluctuation in the number of adsorbed molecules.Comment: 23 pages, 9 figures, submitted to Journal of Physics: Condensed Matter as a Special Issue Articl

On some properties of the water-vapor spectrum and their relations to atmospheric radiation

In the present paper we investigate the physical consequences of the fact that the water vapor spectrum in the far infrared consists of a large number of narrow lines. It will be shown that the average width of these lines is much smaller than the intervals which could be resolved with the spectrographs used hitherto. For thick layer of vapor complete absorption is nevertheless reached in most parts of the spectrum. It can be shown that under such circumstances the total absorption is approximately proportional to the air pressure in the absorbing layers and is inversely proportional to the square root of the absolute temperature. There is an additional variation with temperature of a more complex type which cannot yet be quantitatively evaluated from the available measurements, but it is probably not very large