Capacity for Half-Duplex Line Networks with Two Sources

The focus is on noise-free half-duplex line networks with two sources where the first node and either the second node or the second-last node in the cascade act as sources. In both cases, we establish the capacity region of rates at which both sources can transmit independent information to a common sink. The achievability scheme presented for the first case is constructive while the achievability scheme for the second case is based on a random coding argument.Comment: Proceedings of the IEEE International Symposium on Information Theory, Austin, TX, USA, June 12 - 18, 201

Developments and Development Directions of Electronic Trade Platforms in US and European Agri-Food Markets: Impact on Sector Organization

Electronic trade platforms support trading transactions between enterprises. They have entered the business landscape including the agri-food sector only a few years ago. However, there already have been dramatic changes in the agri-food sectorÂ’s platform infrastructures. This paper analyzes developments in electronic trade platform infrastructures in the agri-food sector of the US and Europe between 2000 and 2002 and identifies development strategies of successful platforms. Of 85 platforms in existence in the year 2000, only 25 remained active in 2002. But there are still market entries of new platforms and existing platforms form various types of partnerships. The analysis could identify a range of strategic development lines of successful platforms. Initiating cooperation with other platforms on the use of specific features and the development and use of standards, gaining support by major market participants, the improvement of trading functionalities and the expansion of value-added services are the primary lines of development and evolvement of platforms. Platform evolvement tendencies and the present occurrence of the trade platform infrastructure allow for projecting the emergence of an agri-food sector with embedded, interconnected e-commerce infrastructure or mega-hub leading towards a more networked agri-food industry.Electronic commerce, Electronic trade platforms, Agri-food markets, Agribusiness, Marketing,

Spherically symmetric equilibria for self-gravitating kinetic or fluid models in the non-relativistic and relativistic case - A simple proof for finite extension

We consider a self-gravitating collisionless gas as described by the Vlasov-Poisson or Einstein-Vlasov system or a self-gravitating fluid ball as described by the Euler-Poisson or Einstein-Euler system. We give a simple proof for the finite extension of spherically symmetric equilibria, which covers all these models simultaneously. In the Vlasov case the equilibria are characterized by a local growth condition on the microscopic equation of state, i.e., on the dependence of the particle distribution on the particle energy, at the cut-off energy E_0, and in the Euler case by the corresponding growth condition on the equation of state p=P(\rho) at \rho=0. These purely local conditions are slight generalizations to known such conditions.Comment: 20 page