Evolution from a molecular Rydberg gas to an ultracold plasma in a seeded supersonic expansion of NO

We report the spontaneous formation of a plasma from a gas of cold Rydberg molecules. Double-resonant laser excitation promotes nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, to single Rydberg states extending as deep as 80 cm$^{-1}$ below the lowest ionization threshold. The density of excited molecules in the illuminated volume is as high as 1 x 10$^{13}$ cm$^{-3}$. This population evolves to produce prompt free electrons and a durable cold plasma of electrons and intact NO$^{+}$ ions.Comment: 4 pages (two column) 3 figures; smaller figure files, corrected typo

The changing patterns of group politics in Britain

Two interpretations of ways in which group politics in Britain have presented challenges to democracy are reviewed: neo-corporatism or pluralistic stagnation and the rise of single issue interest groups. The disappearance of the first paradigm created a political space for the second to emerge. A three-phase model of group activity is developed: a phase centred around production interests, followed by the development of broadly based 'other regarding' groups, succeeded by fragmented, inner directed groups focusing on particular interests. Explanations of the decay of corporatism are reviewed. Single issue group activity has increased as party membership has declined and is facilitated by changes in traditional media and the development of the internet. Such groups can overload the policy-making process and frustrate depoliticisation. Debates about the constitution and governance have largely ignored these issues and there is need for a debate

Effect of phosphorus and cadmium levels on glyphosate sorption

Non-Peer Reviewe

Digital Synthetic Aperture Acoustic Imaging for NDE

Real time synthetic aperture or synthetic focus techniques for acoustic imaging have been investigated and a prototype digital imaging system has been developed. It operates by exciting, with an impulse, one element from a transducer array, digitizing the return echoes, and storing them in a Random Access Memory. When this process has been repeated for all the array elements, the focus information is loaded from a mini computer. The system then generates a series of swept-focus lines, which are arranged perpendicular to the array face. Our processor handles typical input data at rates sufficient to generate real time images. As only one transducer at a time is excited it has been necessary to develop a high efficiency broadband transducer array with quarter wavelength matching layers. The array we have developed has an 11 dB return loss, a 2.7-4.3 MHz frequency range with a pulse response approximately 5 half cycles long. The digital processor operates at a 10- 16 MHz sample rate with 8 bit quantization. Theoretical and experimental images will be presented for a system with a 96 line display employing 8 and 32 active transducer elements, which has a resolution of \u3c 1 mm. We will also discuss methods of reducing the sidelobe responses in these systems. We have carried out experiments and theory, and we can considerably reduce the sidelobe level with input gain compression from the current experimental value of -12 dB to beyond -20 dB in our prototype 8 transducer system. In addition, we are investigating inverse filtering techniques for shortening the effective pulse length to 1 rf cycle to further improve the image quality and range resolution

Postfledging Survival, Movements, and Dispersal of Ring Ouzels (Turdus torquatus)

We thank Invercauld Estate for cooperation with access to Glen Clunie. S. Redpath, J. Wilson, and S. Roos provided valuable comments on the manuscript. This study was funded by the Royal Society for the Protection of Birds, Scottish Natural Heritage, and the Cairngorms National Park Authority. J.L.L. was supported by the Natural Environment Research Council.Peer reviewedPublisher PD