Laser spectroscopy of hyperfine structure in highly-charged ions: a test of QED at high fields

An overview is presented of laser spectroscopy experiments with cold, trapped, highly-charged ions, which will be performed at the HITRAP facility at GSI in Darmstadt (Germany). These high-resolution measurements of ground state hyperfine splittings will be three orders of magnitude more precise than previous measurements. Moreover, from a comparison of measurements of the hyperfine splittings in hydrogen- and lithium-like ions of the same isotope, QED effects at high electromagnetic fields can be determined within a few percent. Several candidate ions suited for these laser spectroscopy studies are presented.Comment: 5 pages, 1 figure, 1 table. accepted for Canadian Journal of Physics (2006

Recent developments in planet migration theory

Planetary migration is the process by which a forming planet undergoes a drift of its semi-major axis caused by the tidal interaction with its parent protoplanetary disc. One of the key quantities to assess the migration of embedded planets is the tidal torque between the disc and planet, which has two components: the Lindblad torque and the corotation torque. We review the latest results on both torque components for planets on circular orbits, with a special emphasis on the various processes that give rise to additional, large components of the corotation torque, and those contributing to the saturation of this torque. These additional components of the corotation torque could help address the shortcomings that have recently been exposed by models of planet population syntheses. We also review recent results concerning the migration of giant planets that carve gaps in the disc (type II migration) and the migration of sub-giant planets that open partial gaps in massive discs (type III migration).Comment: 52 pages, 18 figures. Review article to be published in "Tidal effects in Astronomy and Astrophysics", Lecture Notes in Physic

Neck mobility measurement by means of the 'Flock of Birds' electromagnetic tracking system

OBJECTIVE: To establish the accuracy and reliability of a six-degrees-of-freedom electromagnetic tracking device, the "Flock of Birds", for measuring neck rotations and to identify the main sources of error. DESIGN: Ten human subjects made the same types of maximal neck rotation, both actively and passively: axial rotation in neutral position, from a flexed position and from an extended position, flexion/extension and lateral flexion. The same movements were mimicked in a 'dummy head' set-up. METHODS: One Flock of Birds receiver was mounted on the thorax, one on the head. By means of a third receiver, mounted on a stylus, bony landmarks on head and thorax were palpated. These served to define two anatomically based local coordinate systems, to which the rotations were referred. RESULTS: Measurements were accurate with a maximal measurement error of 2.5 degrees. No significant difference between active and passive rotation was seen. The intra-subject variation was low within the same session, SD between 2 degrees and 4 degrees. Between sessions the variability was considerable, SD between 5 degrees and 16 degrees. CONCLUSION: The Flock of Birds method is reliable and sufficiently precise. The variability in measured range of motion between sessions is a point of concern in interpreting follow-up studies in patients. RELEVANCE: A reduced range of neck motion is a major complaint in pathologies of the cervical spine or the shoulder. A method is described in which neck rotations are related to well-defined bony landmarks. In combined rotations, e.g. flexion combined with axial rotation, the measured range of motion can sometimes fluctuate strongly (up to 30 degrees ) between measurements, without apparent pathology

The EC and world protectionism Dimensions of the political economy

SIGLEAvailable from British Library Document Supply Centre- DSC:3597.9512(CEPR-DP--897) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Regionalism versus multilateralism

Available from British Library Document Supply Centre-DSC:3597.9512(CEPR-DP--1525) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo