RF circulator structures via offset lithography

Further developments are reported of the conductive lithographic film (CLF) process in which components of radio-frequency circulators are fabricated economically via offset lithography. The performance of centre conductor elements printed from silver-loaded inks on polymer substrates is compared with that of conventional solid copper structures

Printed analogue filter structures

The authors report progress in conductive lithographic film (CLF) technology, which uses the offset lithographic printing process to form electrically conductive patterns on flexible substrates. Networks of planar passive components and interconnects fabricated simultaneously via the CLF process form notch filter networks at 85 kHz

An investigation of cellular radiosensitivity associated with immunodeficiency.

DNA Double Strand Breaks (DSBs) are induced by ionising radiation, but also arise during normal physiological processes such as V(D)J recombination during lymphocyte development. The induction of DSBs leads to the activation of proteins involved in DNA repair, but also initiates p53 dependent pathways that can result in cell cycle arrest and/or apoptosis. Defects in this damage response network may therefore result in immunodeficiency and cellular radiosensitivity. Skin biopsies obtained from undefined immunodeficient patients were used to generate primary fibroblast lines, and a group of these demonstrated cellular radiosensitivity using fibroblast survival assays. Whilst radiation-induced lymphocyte apoptosis was found to be an unreliable measure of intrinsic radiosensitivity, the examination of fibroblast division early after irradiation determined that radiosensitive fibroblasts undergo distinct cell fates after irradiation. Further characterisation revealed that all the identified radiosensitive lines were able to initiate p53-dependent gene transcription after irradiation. Analysis suggested that one undefined line (F96) might harbour a defect in DSB repair. Sequence examination of F96 candidate genes confirmed the presence of 2 novel mutations in the Artemis DNA repair gene that were expressed from separate alleles. Cloning of the Artemis gene also allowed the discovery of a new alternative exon and many novel splice variants. Concurrently, the F96 line was found to induce abnormally high levels of p53 activation after irradiation, which was associated with a more widespread induction of p53 target genes. This indicated that after DNA damage, defects in DSB repair might combine with other genetic factors that impair cellular survival to confer a radiosensitive immunodeficient phenotype

Stability of Circular Orbits in General Relativity: A Phase Space Analysis

Phase space method provides a novel way for deducing qualitative features of nonlinear differential equations without actually solving them. The method is applied here for analyzing stability of circular orbits of test particles in various physically interesting environments. The approach is shown to work in a revealing way in Schwarzschild spacetime. All relevant conclusions about circular orbits in the Schwarzschild-de Sitter spacetime are shown to be remarkably encoded in a single parameter. The analysis in the rotating Kerr black hole readily exposes information as to how stability depends on the ratio of source rotation to particle angular momentum. As a wider application, it is exemplified how the analysis reveals useful information when applied to motion in a refractive medium, for instance, that of optical black holes.Comment: 20 pages. Accepted for publication in Int. J. theor. Phy

Reconstruction of Random Colourings

Reconstruction problems have been studied in a number of contexts including biology, information theory and and statistical physics. We consider the reconstruction problem for random $k$-colourings on the $\Delta$-ary tree for large $k$. Bhatnagar et. al. showed non-reconstruction when $\Delta \leq \frac12 k\log k - o(k\log k)$ and reconstruction when $\Delta \geq k\log k + o(k\log k)$. We tighten this result and show non-reconstruction when $\Delta \leq k[\log k + \log \log k + 1 - \ln 2 -o(1)]$ and reconstruction when $\Delta \geq k[\log k + \log \log k + 1+o(1)]$.Comment: Added references, updated notatio

Multilayer clustering: Biomarker driven segmentation of Alzheimer's disease patient population

Identification of biomarkers for the Alzheimer's disease is a challenge and a very difficult task both for medical research and data analysis. In this work we present results obtained by application of a novel clustering tool. The goal is to identify subpopulations of the Alzheimer's disease (AD) patients that are homogeneous in respect of available clinical and biological descriptors. The result presents a segmentation of the Alzheimer's disease patient population and it may be expected that within each subpopulation separately it will be easier to identify connections between clinical and biological descriptors. Through the evaluation of the obtained clusters with AD subpopulations it has been noticed that for two of them relevant biological measurements (whole brain volume and intracerebral volume) change in opposite directions. If this observation is actually true it would mean that the diagnosed severe dementia problems are results of different physiological processes. The observation may have substantial consequences for medical research and clinical trial design. The used clustering methodology may be interesting also for other medical and biological domains

A geological model of the chalk of East Kent

This report describes the geological modelling of the Chalk in the North Downs of East Kent, within the catchment of River Great Stour and eastwards to the coast, including the Isle of Thanet. This work was funded by the Environment Agency to support investigations of the local hydrogeology and thereby to enhance catchment management. The whole area is underlain by the Upper Cretaceous Chalk Group, with the Palaeogene succession of the Thanet Sand Formation, the Lambeth Group and the Thames Group overlying it in the northern and central eastern parts. The project included a desk study revision of the Chalk of the North Downs, using the new Chalk lithostratigraphy. The revisions to the geology are shown on the 1:50 000 scale geological map which accompanies this report. Together with evidence from boreholes and from seismic surveys, the new outcrop patterns have been incorporated into a geological model, using both computer software (EarthVision) and manual methods. The introduction describes the background to the project. The second chapter describes the sources for the data used in the model: published and unpublished geological maps, borehole records (both lithological and geophysical), seismic surveys, biostratigraphic records, digital topographic information, and the published literature. Each Chalk formation present in the area is then briefly described in the third chapter, noting its relationship to the older lithostratigraphic divisions, and to biostratigraphic zones. The local Chalk succession extends from the base of the Chalk Group to the Newhaven Chalk Formation, here represented by the Margate Chalk Member. Evidence for the thickness of each formation is reviewed. The early Palaeogene formations (the Thanet Sand, Upnor, Harwich and London Clay formations) are also briefly described (Chapter 4) and the local superficial deposits mentioned, with references to detailed descriptions (Chapter 5). Apart from minor adjustments to the outcrop of the basal Palaeogene surface, no revision of these formations was done for this study

Image resonance in the many-body density of states at a metal surface

The electronic properties of a semi-infinite metal surface without a bulk gap are studied by a formalism that is able to account for the continuous spectrum of the system. The density of states at the surface is calculated within the GW approximation of many-body perturbation theory. We demonstrate the presence of an unoccupied surface resonance peaked at the position of the first image state. The resonance encompasses the whole Rydberg series of image states and cannot be resolved into individual peaks. Its origin is the shift in spectral weight when many-body correlation effects are taken into account