S-Duality Constraints On Effective Potentials For Gaugino Condensation

We clarify the role of approximate S-duality in effective supergravity theories that are the low energy limits of string theories, and show how this partial symmetry may be used to constrain effective lagrangians for gaugino condensation.Comment: 22 page

Reduced order system identification for UAVs

Reduced order models representing the dynamic behaviour of symmetric aircraft are well known and can be easily derived from the standard equations of motion. In flight testing, accurate measurements of the dependent variables which describe the linearised reduced order models for a particular flight condition are vital for successful system identification. However, not all the desired measurements such as the rate of change in vertical velocity (W. ) can be accurately measured in practice. In order to determine such variables two possible solutions exist: reconstruction or differentiation. This paper addresses the effect of both methods on the reliability of the parameter estimates. The methods are used in the estimation of the aerodynamic derivatives for the Aerosonde UAV from a recreated flight test scenario in Simulink. Subsequently, the methods are then applied and compared using real data obtained from flight tests of the Cranfield University Jetstream 31 (G-NFLA) research aircraft

The Y^2 Stellar Evolutionary Tracks

We present a database of the latest stellar models of the $Y^2$ (Yonsei-Yale) collaboration. This database contains the stellar evolutionary tracks from the pre-main-sequence birthline to the helium core flash that were used to construct the $Y^2$ isochrones. We also provide a simple interpolation routine that generates stellar tracks for given sets of parameters (metallicity, mass, and $\alpha$-enhancement).Comment: 7 pages, TeX, 1 eps figure. ApJS, 2003, vol.144 (Feb), in pres

Airline Alliances, Carve-Outs and Collusion

In this paper, we ask how antitrust immunity subject to a carve-out affects collusion incentives in international airline alliances. We show that the gains from economies of density due to higher interline traffic under the alliance strengthen the incentive to collude on the interhub segment, while the accompanying revenue gain heightens the incentive to defect from collusive behavior. These two effects exactly cancel in the case of linear demands and linear economies of density. Under this approximation, the incentives for interhub collusion are no different before and after the emergence of an airline alliance subject to a carve-out.collusion, carve-out

Laser phase noise effects on the dynamics of optomechanical resonators

We investigate theoretically the influence of laser phase noise on the cooling and heating of a generic cavity optomechanical system. We derive the back-action damping and heating rates and the mechanical frequency shift of the radiation pressure-driven oscillating mirror, and derive the minimum phonon occupation number for small laser linewidths. We find that in practice laser phase noise does not pose serious limitations to ground state cooling. We then consider the effects of laser phase noise in a parametric cavity driving scheme that minimizes the back-action heating of one of the quadratures of the mechanical oscillator motion. Laser linewidths narrow compared to the decay rate of the cavity field will not pose any problems in an experimental setting, but broader linewidths limit the practicality of this back-action evasion method.Comment: 9 pages, 7 figure