Horizontal Product Differentiation in Auctions and Multilateral Negotiations

We experimentally compare first-price auctions and multilateral negotiations after introducing horizontal product differentiation into a standard procurement setting. The two institutions yield the buyer the same surplus, a difference from prior findings with homogeneous products that results from differentiation’s influence on the sellers’ pricing behavior. In particular, we find that introducing product differentiation intensifies price competition among the sellers in some treatments, and has no effect in others, which contrasts with the conventional wisdom that product differentiation softens competition.

A Simple Method for Computing Singular or Nearly Singular Integrals on Closed Surfaces

We present a simple, accurate method for computing singular or nearly singular integrals on a smooth, closed surface, such as layer potentials for harmonic functions evaluated at points on or near the surface. The integral is computed with a regularized kernel and corrections are added for regularization and discretization, which are found from analysis near the singular point. The surface integrals are computed from a new quadrature rule using surface points which project onto grid points in coordinate planes. The method does not require coordinate charts on the surface or special treatment of the singularity other than the corrections. The accuracy is about $O(h^3)$, where $h$ is the spacing in the background grid, uniformly with respect to the point of evaluation, on or near the surface. Improved accuracy is obtained for points on the surface. The treecode of Duan and Krasny for Ewald summation is used to perform sums. Numerical examples are presented with a variety of surfaces.Comment: to appear in Commun. Comput. Phy

A Comparison of Auctions and Multilateral Negotiations

We compare first-price auctions to an exchange process that we term \u27multilateral negotiations.\u27 In multilateral negotiations, a buyer solicits price offers for a homogeneous product from sellers with privately known costs, and then plays the sellers off one another to obtain additional price concessions. Using the experimental method, we find that with four sellers, transaction prices are statistically indistinguishable in the two institutions, but with two sellers, prices are higher in multilateral negotiations than in first-price auctions. The institutions are equally efficient with two sellers, but multilateral negotiations are slightly more efficient with four sellers

Horizontal Product Differentiation in Auctions and Multilateral Negotiations

We experimentally compare first-price auctions and multilateral negotiations after introducing horizontal product differentiation into a standard procurement setting. Both institutions yield identical surplus for the buyer, a difference from prior findings with homogeneous products that results from differentiation\u27s influence on sellers\u27 pricing behaviour. The data are consistent with this finding being driven by concessions from low-cost sellers in response to differentiation reducing their likelihood of being the buyer\u27s surplus-maximizing trading partner. Further analysis shows that introducing product differentiation increases the intensity of price competition among sellers, which contrasts with the conventional wisdom that product differentiation softens competition

Is Mycoplasma bovis in Sand Bedding Infectious to Dairy Calves?

Mycoplasmas are unusual bacteria that can infect all ages of cattle, and can cause arthritis, pneumonia, and death. Infected dairy cows may also contract mastitis, metritis, or virtually cease milk production. The most common mycoplasma affecting cattle is M. bovis; there are several other Mycoplasma spp. as well. Because standard microbial culture methods do not isolate Mycoplasma spp., special laboratory methods are needed for diagnosis. Mycoplasma spreads by inhalation and respiratory secretions and also at milking time via contaminated inflations in milking units. Mycoplasma spp. have also been detected in straw, sand, recycled manure, and other bedding, often associated with cows with mycoplasma mastitis lying on that bedding. Therefore, producers often ask about mycoplasma-positive recycled bedding’s risk to baby calves. We have found mycoplasma in straw, recycled manure, and some other environments, including hospital pens where cows sometimes calve. However, we have found it much more likely to be found in sand than other bedding types, all on farms with cows already mycoplasma-positive. Therefore, we investigated whether mycoplasma-positive sand bedding infected mycoplasma-free dairy calves

Surface flashover of oil-immersed dielectric materials in uniform and non-uniform fields

The applied electrical fields required to initiate surface flashover of different types of dielectric material immersed in insulating oil have been investigated, by applying impulses of increasing peak voltage until surface flashover occurred. The behavior of the materials in repeatedly over-volted gaps was also analyzed in terms of breakdown mode (some bulk sample breakdown behaviour was witnessed in this regime), time to breakdown, and breakdown voltage. Cylindrical samples of polypropylene, low-density polyethylene, ultra-high molecular weight polyethylene, and Rexolite, were held between two electrodes immersed in insulating oil, and subjected to average applied electrical fields up to 870 kV/cm. Tests were performed in both uniform- and non-uniform-fields, and with different sample topologies. In applied field measurements, polypropylene required the highest levels of average applied field to initiate flashover in all electrode configurations tested, settling at similar to 600 kV/cm in uniform fields, and similar to 325 kV/cm in non-uniform fields. In over-volted point-plane gaps, ultra-high molecular weight polyethylene exhibited the longest pre-breakdown delay times. The results will provide comparative data for system designers for the appropriate choice of dielectric materials to act as insulators for high-voltage, pulsed-power machines