The Theory of Assortative Matching Based on Costly Signals

We study two-sided markets with a finite numbers of agents on each side, and with two-sided incomplete information. Agents are matched assortatively on the basis of costly signals. A main goal is to identify conditions under which the potential increase in expected output due to assortative matching (relative to random matching) is completely offset by the costs of signalling. We also study how the signalling activity and welfare on each side of the market change when we vary the number of agents and the distribution of their attributes, thereby displaying effects that are particular to small markets. Finally, we look at the continuous version of our two-sided market model and establish the connections to the finite version. Technically, the paper is based on the very elegant theory about stochastic ordering of (normalized) spacings and other linear combinations of order statistics from distributions with monotone failure rates, pioneered by R. Barlow and F. Proschan (1966, 1975) in the framework of reliability theory

Intermediation in Innovation

The paper offers a new theoretical framework to examine the role of intermediaries between creators and potential users of new inventions. Using a model of university-industry technology transfer, we demonstrate that technology transfer offices can provide an opportunity to economize on a critical component of efficient innovation investments: the expertise to locate new, external inventions and to overcome the problem of sorting ‘profitable’ from ‘unprofitable’ ones. The findings may help explain the surge in university patenting and licensing since the Bayh-Dole Act of 1980. Furthermore, the study identifies several limitations to the potential efficiency of intermediation in innovation. ZUSAMMENFASSUNG - In diesem Papier stellen wir ein neues theoretisches Modell zur Analyse der Rolle von Intermediären zwischen Erfindern und potentiellen Nutzern von Erfindungen vor. Für den Transfer von Erfindungen aus Universitäten in den Industriebereich zeigen wir, daß Technologietransfer-Stellen den Marktteilnehmern die Möglichkeit bieten, sich die Kosten für den Aufbau der Expertise, neue externe Erfindungen zu lokalisieren und evaluieren, zu teilen. Die Ergebnisse unserer Studie können dazu beitragen, die signifikante Zunahme der Universitätspatente und - lizensen seit dem Bayh-Dole-Act von 1980 in den USA zu erklären. Darüber hinaus diskutieren wir Wohlfahrtswirkungen der Aktivität von Innovations-Intermediären.Intermediation, Market Microstructure, Matching Uncertainty, Innovation, Patent Licensing

EISCAT observations during MAC/SINE and MAC/Epsilon

The EISCAT incoherent scatter radar facility in Tromsoe, Norway was operated during the MAC/SINE campaign for 78 hours in the period 10 June to 17 July 1987, and during the MAC/Epsilon campaign for 90 hours in the period 15 October to 5 November 1987. The VHF (224 MHz) radar operations during MAC/SINE yielded most interesting observations of strong coherent echoes from the mesopause region. Characteristic data of these polar mesospheric summer echoes are presented. The UHF (933 MHz) radar operations during MAC/Epsilon were done with 18 deg off zenith beam and allows the deduction of meridonal and horizontal wind components as well as radial velocity spectra in addition to the usual electron density profiles in the D and lower E regions. Some results from the VHF and UHF radars indicating the presence of gravity waves are examined

Spatial Competition in Credit Markets

Using Hotelling's two-stage model of spatial competition, we develop a lending model where the equilibrium outcome may be characterized by maximal differentiation - in contrast to Hotelling's model where firms have an incentive to reduce differentiation, as long as a pure-strategy price equilibrium exists. The difference is due to the specificities of banks' activities: banks perform independent tests to assess the credit-worthiness of their loan applicants, and thereby create a nongeographic customer heterogeneity. If banks are sufficiently pessimistic about the credit-worthiness of firms, they try to minimize the risk of default by moving away from the market centerBanking competition, Hotelling, information acquisition, credit-worthiness tests

Entry Deterrence in Durable-Goods Monopoly

Some industries support Schumpeter's notion of creative destruction through innovative entrants. Others exhibit a single, persistent technological leadership. This paper explores a durable-goods monopolist threatened by entry via a new generation of the durable good. It is shown that the durability of the good either acts as an entry barrier itself or creates an opportunity for the incumbent firm to deter entry by limit pricing. As a consequence, the industry tends to remain monopolized, with successive generations of the durable good being introduced by the incumbent monopolist. We show that entry deterrence by limit pricing can lead to underinvestment in innovation.

The Theory of Assortative Matching Based on Costly Signals

We study two-sided markets with a finite numbers of agents on each side, and with two-sided incomplete information. Agents are matched assortatively on the basis of costly signals. A main goal is to identify conditions under which the potential increase in expected output due to assortative matching (relative to random matching) is completely offset by the costs of signalling. We also study how the signalling activity and welfare on each side of the market change when we vary the number of agents and the distribution of their attributes, thereby displaying effects that are particular to small markets. Finally, we look at the continuous version of our two-sided market model and establish the connections to the finite version. Technically, the paper is based on the very elegant theory about stochastic ordering of (normalized) spacings and other linear combinations of order statistics from distributions with monotone failure rates, pioneered by R. Barlow and F. Proschan (1966, 1975) in the framework of reliability theory.

Probing chiral interactions up to next-to-next-to-next-to-leading order in medium-mass nuclei

We study ground-state energies and charge radii of closed-shell medium-mass nuclei based on novel chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions, with a focus on exploring the connections between finite nuclei and nuclear matter. To this end, we perform in-medium similarity renormalization group (IM-SRG) calculations based on chiral interactions at next-to-leading order (NLO), N$^2$LO, and N$^3$LO, where the 3N interactions at N$^2$LO and N$^3$LO are fit to the empirical saturation point of nuclear matter and to the triton binding energy. Our results for energies and radii at N$^2$LO and N$^3$LO overlap within uncertainties, and the cutoff variation of the interactions is within the EFT uncertainty band. We find underbound ground-state energies, as expected from the comparison to the empirical saturation point. The radii are systematically too large, but the agreement with experiment is better. We further explore variations of the 3N couplings to test their sensitivity in nuclei. While nuclear matter at saturation density is quite sensitive to the 3N couplings, we find a considerably weaker dependence in medium-mass nuclei. In addition, we explore a consistent momentum-space SRG evolution of these NN and 3N interactions, exhibiting improved many-body convergence. For the SRG-evolved interactions, the sensitivity to the 3N couplings is found to be stronger in medium-mass nuclei.Comment: 10 pages, 11 figures, published versio

Interpretation of runaway electron synchrotron and bremsstrahlung images

The crescent spot shape observed in DIII-D runaway electron synchrotron radiation images is shown to result from the high degree of anisotropy in the emitted radiation, the finite spectral range of the camera and the distribution of runaways. The finite spectral camera range is found to be particularly important, as the radiation from the high-field side can be stronger by a factor $10^6$ than the radiation from the low-field side in DIII-D. By combining a kinetic model of the runaway dynamics with a synthetic synchrotron diagnostic we see that physical processes not described by the kinetic model (such as radial transport) are likely to be limiting the energy of the runaways. We show that a population of runaways with lower dominant energies and larger pitch-angles than those predicted by the kinetic model provide a better match to the synchrotron measurements. Using a new synthetic bremsstrahlung diagnostic we also simulate the view of the Gamma Ray Imager (GRI) diagnostic used at DIII-D to resolve the spatial distribution of runaway-generated bremsstrahlung.Comment: 21 pages, 11 figure

The Origin of Chiral Anomaly and the Noncommutative Geometry

We describe the scalar and spinor fields on noncommutative sphere starting from canonical realizations of the enveloping algebra ${\cal A}={\cal U}{u(2))}$. The gauge extension of a free spinor model, the Schwinger model on a noncommutative sphere, is defined and the model is quantized. The noncommutative version of the model contains only a finite number of dynamical modes and is non-perturbatively UV-regular. An exact expresion for the chiral anomaly is found. In the commutative limit the standard formula is recovered.Comment: 30 page