Sovereign Debt as Intertemporal Barter

Borrowing and lending between sovereign parties is modeled as intertemporal barter that smoothes the consumption of a risk-averse party subject to endowment shocks. The surplus anticipated in the relationship offers sufficient incentive for cooperation by all parties, including any other competitive agents who are potential lenders to the sovereign. The sole punishments consist of renegotiation-proof changes in the path of future payments. We show that intertemporal trade can be sustained in the absence of any exogenous enforcement of lending relationships whatsoever. That is, borrowing and lending are possible under anarchy, and are supported by punishments that consist of cheating any cheater. Long-term implicit relationships may be fulfilled as the continual renegotiation of simple incomplete short-term loans. The analysis suggests that the crucial role of the explicit loan contract is the identification of the relationship and the parties involved.

Orbital thermal analysis of lattice structured spacecraft using color video display techniques

A color video display technique is demonstrated as a tool for rapid determination of thermal problems during the preliminary design of complex space systems. A thermal analysis is presented for the lattice-structured Earth Observation Satellite (EOS) spacecraft at 32 points in a baseline non Sun-synchronous (60 deg inclination) orbit. Large temperature variations (on the order of 150 K) were observed on the majority of the members. A gradual decrease in temperature was observed as the spacecraft traversed the Earth's shadow, followed by a sudden rise in temperature (100 K) as the spacecraft exited the shadow. Heating rate and temperature histories of selected members and color graphic displays of temperatures on the spacecraft are presented

Interference of a thermal Tonks gas on a ring

A nonzero temperature generalization of the Fermi-Bose mapping theorem is used to study the exact quantum statistical dynamics of a one-dimensional gas of impenetrable bosons on a ring. We investigate the interference produced when an initially trapped gas localized on one side of the ring is released, split via an optical-dipole grating, and recombined on the other side of the ring. Nonzero temperature is shown not to be a limitation to obtaining high visibility fringes.Comment: 4 pages, 3 figure

Does measurement technique explain the mismatch between European head size and WHO charts?

Objective To test whether different measuring techniques produce systematic differences in head size that could explain the large head circumferences found in Northern European children compared with the WHO standard. Design: Cross-sectional observational study. Setting: Scotland, UK. Patients: Study 1: 68 healthy children aged 0.4–18 months from mother and baby groups and a medical students teaching session. Study 2: 81 children aged 0.4 to 25 months from hospital wards and neonatal follow-up clinics. Interventions: Study 1: heads measured with plastic tape using both the WHO tight and UK loose technique. Study 2: heads measured using WHO research technique and a metal measuring tape and compared with routinely acquired measurements. Main outcome measures: Mean difference in head z-scores using WHO standard between the two methods. Results: The tight technique resulted in a mean (95% CI) z-score difference of 0.41 (0.27 to 0.54, p<0.001) in study 1 and 0.44 (0.36 to 0.53, p<0.001) in study 2. However, the mean WHO measurements in the healthy infants still produced a mean z-score that was two-third of a centile space (0.54 SD (0.28 to 0.79) p<0.001) above the 50th centile. Conclusion: The WHO measurement techniques produced significantly lower measures of head size, but average healthy Scottish children still had larger heads than the WHO standard using this method

Alternative instruments for smoothing the consumption of primary commodity exporters

Countries that depend on a single primary export for their foreign earnings are likely to experience sharp fluctuations in export earnings and their underlying wealth, because of the instability of all primary commodity markets. As part of structural adjustment, several countries have liberalized their trade regimes, so domestic producers are no longer insulated from international price fluctuations. This paper concentrates on the management of country-level consumption risk, and considers actions which the government might undertake to reduce the cost of that risk. The paper reviews the costs of export price instability, with some reference to the empirical magnitudes. It considers the role of conventional instruments, including loans, price stabilization measures, and futures contracts. Particular attention is paid to the potential use of futures rollovers for longer-term price protection, and the effect of production response on that protection. The paper also discusses"commodity bonds"and dynamic consumption smoothing paths and offers conclusions.Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Access to Markets,Markets and Market Access

Candidate constructional volcanic edifices on Mercury

[Introduction] Studies using MESSENGER data suggest that Mercury’s crust is predominantly a product of effusive volcanism that occurred in the first billion years following the planet’s formation. Despite this planet-wide effusive volcanism, no constructional volcanic edifices, characterized by a topographic rise, have hitherto been robustly identified on Mercury, whereas constructional volcanoes are common on other planetary bodies in the solar system with volcanic histories. Here, we describe two candidate constructional volcanic edifices we have found on Mercury and discuss how these edifices may have formed

A model for the interaction of high-energy particles in straight and bent crystals implemented in Geant4

A model for the simulation of orientational effects in straight and bent periodic atomic structures is presented. The continuum potential approximation has been adopted.The model allows the manipulation of particle trajectories by means of straight and bent crystals and the scaling of the cross sections of hadronic and electromagnetic processes for channeled particles. Based on such a model, an extension of the Geant4 toolkit has been developed. The code has been validated against data from channeling experiments carried out at CERN