Typability in partial groupoids

Adapting a claim of M. Kracht, we establish a characterization of the typable partial applicative algebras.Comment: 5 page

Different Perspectives on the Global Development of Transport

The future of the transport sector is clearly fraught with uncertainties, as the system is influenced by many factors that can develop in various ways. The aim of this paper is to get insight into the future development of the transportation sector seen from a world-wide perspective. This is done by applying a scenario approach and by designing four possible development paths for transport. These future developments are presented here by sketching four global contrast images based on outcomes of earlier research. The outcomes for the transport sector, expressed in transported volumes for both passenger transport and freight transport, are first described qualitatively, based on expected developments of several indicators. Next, based on those descriptions, quantitative numbers of transported volumes are calculated with the year 2020 as the time horizon. It appears that all scenarios foresee a world-wide growth in transport volumes (for both passengers and freight). The achievement of sustainable mobility based on the outcomes presented in this paper may seem difficult and will be confronted with several hurdles. But policy changes and (unexpected) technology developments offer possibilities to realise this objective. Thus policy makers are faced with formidable policy challenges to achieve the Kyoto objectives in the next 20 years. 1

Development and management of green spaces in European cities: a comparative analysis

“Energy, Environment and Sustainable Development ” of the 5th Framework Programme of the European Union. This paper aims to compare the present state and availability of urban green spaces in various European cities. The results of a factor analysis applied on the information gathered in extensive survey questionnaires show that the availability of “urban green ” is high in metropoles and big cities, whereas availability of “natural green”, such as forests and agricultural areas, is high i

Influence of Atmospheric Turbulence on Optical Communications using Orbital Angular Momentum for Encoding

We describe an experimental implementation of a free-space 11-dimensional communication system using orbital angular momentum (OAM) modes. This system has a maximum measured OAM channel capacity of 2.12 bits/photon. The effects of Kolmogorov thin-phase turbulence on the OAM channel capacity are quantified. We find that increasing the turbulence leads to a degradation of the channel capacity. We are able to mitigate the effects of turbulence by increasing the spacing between detected OAM modes. This study has implications for high-dimensional quantum key distribution (QKD) systems. We describe the sort of QKD system that could be built using our current technology.Comment: 6 pages, 5 figure

Announcement of the Summer School of Biology for 1929 July 6-August 16

Official Publication of Cornell University V.20 1928/2