Asymmetric price effects of competition

This paper examines how the distribution of prices changes with the number of competitors in the market. Using gasoline price data from the Netherlands we find that as competition increases, the distribution of prices spreads out: the low prices go down while the high prices go up, on average. As a result, competition has an asymmetric effect on prices. These findings, which are consistent with a theoretical model where consumers differ in the information they have about prices, imply that consumers' gains from competition depend on their shopping behavior. In our data, all consumers, irrespective of the number of prices they observe, benefit from an increase in the number of gas stations. The magnitude of the welfare gain, however, is greater for those consumers that are aware of more prices. We conclude that an increase in the number of gas stations has a positive but unequal effect on the welfare of consumers in the Netherlands.Asymmetric; Price; Effects; Competition;

Mean Field Theory for Sigmoid Belief Networks

We develop a mean field theory for sigmoid belief networks based on ideas from statistical mechanics. Our mean field theory provides a tractable approximation to the true probability distribution in these networks; it also yields a lower bound on the likelihood of evidence. We demonstrate the utility of this framework on a benchmark problem in statistical pattern recognition---the classification of handwritten digits.Comment: See http://www.jair.org/ for any accompanying file

Nonlinear Couplings of R-modes: Energy Transfer and Saturation Amplitudes at Realistic Timescales

Non-linear interactions among the inertial modes of a rotating fluid can be described by a network of coupled oscillators. We use such a description for an incompressible fluid to study the development of the r-mode instability of rotating neutron stars. A previous hydrodynamical simulation of the r-mode reported the catastrophic decay of large amplitude r-modes. We explain the dynamics and timescale of this decay analytically by means of a single three mode coupling. We argue that at realistic driving and damping rates such large amplitudes will never actually be reached. By numerically integrating a network of nearly 5000 coupled modes, we find that the linear growth of the r-mode ceases before it reaches an amplitude of around 10^(-4). The lowest parametric instability thresholds for the r-mode are calculated and it is found that the r-mode becomes unstable to modes with 13<n<15 if modes up to n=30 are included. Using the network of coupled oscillators, integration times of 10^6 rotational periods are attainable for realistic values of driving and damping rates. Complicated dynamics of the modal amplitudes are observed. The initial development is governed by the three mode coupling with the lowest parametric instability. Subsequently a large number of modes are excited, which greatly decreases the linear growth rate of the r-mode.Comment: 3 figures 4 pages Submitted to PR

Calculation of gravitational wave forms from black hole collisions and disk collapse: Applying perturbation theory to numerical spacetimes

Many simulations of gravitational collapse to black holes become inaccurate before the total emitted gravitational radiation can be determined. The main difficulty is that a significant component of the radiation is still in the near-zone, strong field region at the time the simulation breaks down. We show how to calculate the emitted waveform by matching the numerical simulation to a perturbation solution when the final state of the system approaches a Schwarzschild black hole. We apply the technique to two scenarios: the head-on collision of two black holes, and the collapse of a disk to a black hole. This is the first reasonably accurate calculation of the radiation generated from colliding black holes that form from matter collapse.Comment: 8 pages (RevTex 3.0 with 7 uuencoded figures

Rogue—A Deeper Meaning: Organizational Communication and the Nonverbal Signifiers in Labels

Within the beer and wine industry, labels provide an ever-prevalent marketing ploy to reel in customers. A semiotic analysis of Rogue Breweries’ five main beer labels provided a glimpse into the company’s communication strategies. Focusing on both verbal and nonverbal messages, the study illuminated several themes occurring within this marketing tool and identified concrete messages conveyed by the labels. The paper upon which this poster was based was written for the Senior Seminar course in Communication Arts