Bargaining and sustainability: the Argentine debt swap of 2005

When Argentine sovereign default in December 2001 led to a collapse of the peso, the burden of dollar debt became demonstrably unsustainable. But it was not clear what restructuring was feasible, nor when. Eventually, in 2005 after a delay of more than three years, a supermajority of creditors accepted a swap implying a recovery rate of around 37 cents in the dollar. In this paper a bargaining approach is used to explain both the settlement and the delay. We conclude that the agreed swap broadly corresponds to a bargaining outcome where the Argentine government had “first mover” advantage: and that substantial delay occurred as negotiators seeking a sustainable settlement waited for economic recovery. Factors not explicit in the formal framework are also considered -- heterogeneity of creditors, for example, and the role of third parties in promoting “good faith” bargaining

Searching for nova shells around cataclysmic variables

We present the results of a search for nova shells around 101 cataclysmic variables (CVs), using Halpha images taken with the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope Photometric Halpha Survey of the Northern Galactic Plane (IPHAS). Both telescopes are located on La Palma. We concentrated our WHT search on nova-like variables, whilst our IPHAS search covered all CVs in the IPHAS footprint. We found one shell out of the 24 nova-like variables we examined. The newly discovered shell is around V1315 Aql and has a radius of approx.2.5 arcmin, indicative of a nova eruption approximately 120 years ago. This result is consistent with the idea that the high mass-transfer rate exhibited by nova-like variables is due to enhanced irradiation of the secondary by the hot white dwarf following a recent nova eruption. The implications of our observations for the lifetime of the nova-like variable phase are discussed. We also examined 4 asynchronous polars, but found no new shells around any of them, so we are unable to confirm that a recent nova eruption is the cause of the asynchronicity in the white dwarf spin. We find tentative evidence of a faint shell around the dwarf nova V1363 Cyg. In addition, we find evidence for a light echo around the nova V2275 Cyg, which erupted in 2001, indicative of an earlier nova eruption approx.300 years ago, making V2275 Cyg a possible recurrent nova.Comment: 14 pages, 50 figures, 3 Table

Constructing packings in Grassmannian manifolds via alternating projection

This paper describes a numerical method for finding good packings in Grassmannian manifolds equipped with various metrics. This investigation also encompasses packing in projective spaces. In each case, producing a good packing is equivalent to constructing a matrix that has certain structural and spectral properties. By alternately enforcing the structural condition and then the spectral condition, it is often possible to reach a matrix that satisfies both. One may then extract a packing from this matrix. This approach is both powerful and versatile. In cases where experiments have been performed, the alternating projection method yields packings that compete with the best packings recorded. It also extends to problems that have not been studied numerically. For example, it can be used to produce packings of subspaces in real and complex Grassmannian spaces equipped with the Fubini--Study distance; these packings are valuable in wireless communications. One can prove that some of the novel configurations constructed by the algorithm have packing diameters that are nearly optimal.Comment: 41 pages, 7 tables, 4 figure

Treatment of Acute Sciatica

In patients with acute sciatica, bed rest and advice to stay active have similar outcomes on their functional status and perceived improvement. (Strength of Recommendation [SOR]: A) Spinal manipulation increases improvement compared with placebo; also, specific spinal pulling and turning manipulation techniques are more effective than traction. (SOR: A) Nonsteroidal anti-inflammatory drugs (NSAIDs) are similar to placebo in overall improvement. (SOR: A) Epidural steroid injections are unlikely to be beneficial. (SOR: A

Electron locking in semiconductor superlattices

We describe a novel state of electrons and phonons arising in semiconductor superlattices (SSL) due to strong electron-phonon interactions. These states are characterized by a localization of phonons and a self-trapping or locking of electrons in one or several quantum wells due to an additional, deformational potential arising around these locking wells in SSL. The effect is enhanced in a longitudinal magnetic field. Using the tight-binding and adiabatic approximations the whole energy spectrum of the self-trapped states is found and accurate, analytic expressions are included for strong electron-phonon coupling. Finally, we discuss possible experiments which may detect these predicted self-trapped states.Comment: 8 pages, 2 figures. Please note that the published article has the title 'Electron locking in layered structures by a longitudinal magnetic field

Sovereign debt default: the impact of creditor composition

The main motivation of this paper is to study the impact of the composition of creditors on the probability of default and the risk premium on sovereign bonds, when there is debtor moral hazard. In the absence of any legal enforcement, relational contracts work only when there are creditors who have a repeated relationship with the borrower. We show that ownership structures with a larger fraction of long term lenders are associated with a lower default probability and lower risk premia. Moreover, competitive markets structures lead to loss in efficiency as well when there is moral hazard, in contrast to the case with perfect enforceability and information