The first fossil cyphophthalmid harvestman from Baltic amber

The first fossil cyphophthalmid harvestman (Opiliones: Cyphophthalmi) from Palaeogene (Eocene) Baltic amber is described. This is only the third fossil example of this basal harvestman lineage; the others being from the probably slightly younger Bitterfeld amber and the much older, early Cretaceous, Myanmar (Burmese) amber. Although incomplete and lacking most of the appendages, the new Baltic amber fossil can be identified as a female. The somatic characters preserved, especially spiracle morphology and the coxo-genital region, allow it to be assigned with some confidence to the extant genus Siro Latreille, 1796 (Sironidae). This fossil is formally described here as Siro balticus sp. nov. It resembles modern North American Siro species more than modern European ones, and can be distinguished principally on its relatively large size and the outline form of the body

An analysis of the use of graphics for information retrieval

Several research groups have addressed the problem of retrieving vector graphics. This work has, however, focused either on domain-dependent areas or was based on very simple graphics languages. Here we take a fresh look at the issue of graphics retrieval in general and in particular at the tasks which retrieval systems must support. The paper presents a series of case studies which explored the needs of professionals in the hope that these needs can help direct future graphics IR research. Suggested modelling techniques for some of the graphic collections are also presented

Upper limits on K-band polarization in three high-redshift radio galaxies: LBDS 53W091, 3C 441 and MRC 0156-252

We present the results of K-band imaging polarimetry of three radio galaxies, including the very red and apparently old z=1.55 galaxy 53W091. We find weak evidence for polarization in components of 3C 441 and in the south-east companion of 53W091, but no evidence of significant polarization in 53W091 itself. We also find strong evidence that MRC 0156-252 is unpolarised. We present upper limits for the K-band polarization of all three sources. For 53W091, the lack of significant K-band polarization provides further confidence that its red R-K colour can be attributed to a mature stellar population, consistent with the detailed analyses of its ultraviolet spectral-energy distribution which indicate a minimum age of 2-3.5 Gyr.Comment: 7 pages, 3 postscript figures. In press at MNRA

Anomalous fluctuations in phases with a broken continuous symmetry

It is shown that the Goldstone modes associated with a broken continuous symmetry lead to anomalously large fluctuations of the zero field order parameter at any temperature below T_c. In dimensions 2<d<4, the variance of the extensive spontaneous magnetization scales as L^4 with the system size L, independent of the order parameter dynamics. The anomalous scaling is a consequence of the 1/q^{4-d} divergence of the longitudinal susceptibility. For ground states in two dimensions with Goldstone modes vanishing linearly with momentum, the dynamical susceptibility contains a singular contribution (q^2-\omega^2/c^2)^{-1/2}. The dynamic structure factor thus exhibits a critical continuum above the undamped spin wave pole, which may be detected by neutron scattering in the N\'eel-phase of 2D quantum antiferromagnets.Comment: final version, minor change

Mechanical and biological aspects of impaction bone grafting in revision hip surgery and the use of a new synthetic bone graft

AIMS: This thesis aims to examine the biological and mechanical factors which influence the strength of impacted morsellised bone graft. The use of synthetic materials as bone graft enhancers was also analysed (Controlled Release Glass - Corglaes®, Giltech Ltd, Ayr, Scotland and Tricalcium Phosphate Hydroxyapatite - TCP/HA, Stryker Howmedica Osteonics, Berkshire, UK). METHODS: Phase I - the mechanical strength of different fresh frozen human bone graft preparations were analysed in the laboratory, looking specifically at the effect of particle size, washing the graft and using synthetic additives. Phase II - mixtures of bone graft and bone graft/Corglaes®, which had been identified as being mechanically stronger than standard bone graft, were analysed for their biological response in an in-vivo ovine defect model, compared to controls. Bone densitometry and histological analysis was performed. Phase III - a mixture of bone graft and Corglaes® was compared to the current 'gold standard' of allograft bone alone, in a simulated revision in-vivo ovine femoral hip replacement model. Outcome measures of subsidence, micromotion on cyclical loading and histomorphometry were performed. RESULTS: Phase 1 - Fresh frozen human bone-graft behaves in a similar fashion to theoretical predictions based on Engineering principles. These principles follow Soil Mechanics theory and are commonly used by engineers when designing stable foundations for roads or buildings. In general, when the spread of different particle sizes is uniform over a given range, the material is stronger (more resistant to shear) than if the particles are all the same size. This allowed determination of which bone mills produce the strongest graft. These results were dependent on the degree of fluid release on graft milling, with more fluid release when the average particle size is reduced. Shear strength was improved for all mills after washing the morsellised graft or by the addition of synthetic additives (Corglaes® and TCP/HA). Phase 2 - The defect model allowed analysis of remodelling of the impacted pellets, highlighting rapid dissolution of the Corglaes®, without a significant inflammatory response. The model may be closer to a fracture model when the histological results of phase III are considered. Phase 3 - No statistically significant difference in subsidence over the implantation period (12 weeks) or micromotion of the retrieved implant / femur composites could be elicited between the two groups. Histological analysis revealed the distal impacted graft to be in an isolated environment, both from biological ingress and solution exchange. Bone graft and Corglaes® that was remodelled or resorbed after time in the Phase II defect experiments, was little changed with time in the distal femur. The proximal femur histologically behaved in a similar fashion to the defect experiments. This suggests that a defect model alone is not ideal to analyse materials for impaction grafting. CONCLUSIONS: • Graft strength is variable depending on the bone mill that produces it - washing bone graft improves the strength from all bone mills tested. • Tight compaction with smaller particles does not inhibit neovascularisation. • Novel biomaterials by themselves were inferior mechanically and biologically. • 50/50 mixes of allograft and Corglaes® are stronger mechanically and do not appear to have an adverse effect on biological incorporation. • In this sheep hemiarthroplasty model, subsidence, micromotion and histomorphometry results better replicate the equivalent reported human results than previous models, especially unloaded defect models in lower vertebrates

Cosmology with redshift surveys of radio sources

We use the K-z relation for radio galaxies to illustrate why it has proved difficult to obtain definitive cosmological results from studies based entirely on catalogues of the brightest radio sources, e.g. 3C. To improve on this situation we have been undertaking redshift surveys of complete samples drawn from the fainter 6C and 7C radio catalogues. We describe these surveys, and illustrate the new studies they are allowing. We also discuss our `filtered' 6C redshift surveys: these have led to the discovery of a radio galaxy at z=4.4, and are sensitive to similar objects at higher redshift provided the space density of these objects is not declining too rapidly with z. There is currently no direct evidence for a sharp decline in the space density of radio galaxies for z > 4, a result only barely consistent with the observed decline of flat-spectrum radio quasars.Comment: 8 pages Latex, To appear in the "Cosmology with the New Radio Surveys" Conference - Tenerife 13-15 January 199

Model system studies with a phase separated membrane bioreactor

The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestial simulation

Forces from highly focused laser beams: modeling, measurement and application to refractive index measurements

The optical forces in optical tweezers can be robustly modeled over a broad range of parameters using generalsed Lorenz-Mie theory. We describe the procedure, and show how the combination of experimental measurement of properties of the trap coupled with computational modeling, can allow unknown parameters of the particle - in this case, the refractive index - to be determined.Comment: 5 pages, 4 figures, presented at 17th AIP Congress, Brisbane, 200