Airline Schedule Competition: Product-Quality Choice in a Duopoly Model

This paper presents a simple model of airline schedule competition that circumvents the complexities of the spatial approach used in earlier papers. Consumers choose between two duopoly carriers, each of which has evenly spaced flights, by comparing the combinations of fare and expected schedule delay that they offer. In contrast to the spatial approach, the particular departure times of individual flights are thus not relevant. The model generates a number of useful comparative-static predictions, while welfare analysis shows that equilibrium flight frequencies tend to be inefficiently low.airline, airline schedule, airline schedule competition, transportation

Airline Schedule Competition: Product-Quality Choice in a Duopoly Model

This paper presents a simple model of airline schedule competition that circumvents the complexities of the spatial approach used in earlier papers. Consumers choose between two duopoly carriers, each of which has evenly spaced flights, by comparing the combinations of fare and expected schedule delay that they offer. In contrast to the spatial approach, the particular departure times of individual flights are thus not relevant. The model generates a number of useful comparative-static predictions, while welfare analysis shows that equilibrium flight frequencies tend to be inefficiently low.

The One Dimensional Damped Forced Harmonic Oscillator Revisited

In this paper we give a general solution to the problem of the damped harmonic oscillator under the influence of an arbitrary time-dependent external force. We employ simple methods accessible for beginners and useful for undergraduate students and professors in an introductory course of mechanics.Comment: 4 Latex page

Computability of the causal boundary by using isocausality

Recently, a new viewpoint on the classical c-boundary in Mathematical Relativity has been developed, the relations of this boundary with the conformal one and other classical boundaries have been analyzed, and its computation in some classes of spacetimes, as the standard stationary ones, has been carried out. In the present paper, we consider the notion of isocausality given by Garc\'ia-Parrado and Senovilla, and introduce a framework to carry out isocausal comparisons with standard stationary spacetimes. As a consequence, the qualitative behavior of the c-boundary (at the three levels: point set, chronology and topology) of a wide class of spacetimes, is obtained.Comment: 44 pages, 5 Figures, latex. Version with minor changes and the inclusion of Figure

Towards a robust estimate of the merger rate evolution using near-IR photometry

We use a combination of deep, high angular resolution imaging data from the CDFS (HST/ACS GOODS survey) and ground based near-IR $K_s$ images to derive the evolution of the galaxy major merger rate in the redshift range $0.2 \leq z \leq 1.2$. We select galaxies on the sole basis of their J-band rest-frame, absolute magnitude, which is a good tracer of the stellar mass. We find steep evolution with redshift, with the merger rate $\propto (1+z)^{3.43\pm0.49}$ for optically selected pairs, and $\propto (1+z)^{2.18\pm0.18}$ for pairs selected in the near-IR. Our result is unlikely to be affected by luminosity evolution which is relatively modest when using rest-frame J band selection. The apparently more rapid evolution that we find in the visible is likely caused by biases relating to incompleteness and spatial resolution affecting the ground based near IR photometry, underestimating pair counts at higher redshifts in the near-IR. The major merger rate was $\sim$5.6 times higher at $z\sim1.2$ than at the current epoch. Overall 41%$\times$(0.5\gyr/$\tau$) of all galaxies with $M_J\leq-19.5$ have undergone a major merger in the last \sim8 \gyr, where $\tau$ is the merger timescale. Interestingly, we find no effect on the derived major merger rate due to the presence of the large scale structure at $z=0.735$ in the CDFS.Comment: Accepted for Publication in ApJ. 9 Figure