14,366 research outputs found

    High density circuit technology

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    Acquisition of polyimide materials for inter-metal dielectrics was obtained from three vendors, with considerable evaluation conducted on the Dupont PI2550 material. Experimental results indicate this material can be patterned using contact printing to line width far below 0.1 mils. Optimum line width is acquired using plasma etch equipment. Metal lift-off experiments on thermal evaporated films were optimized for application to sputtered deposited films. Alternate metal-lift-off experiments are proposed for future investigation. Dry processing equipment studies and future trends in VLSI fabrication techniques are on-going

    High density circuit technology

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    Polyimide dielectric materials were acquired for comparative and evaluative studies in double layer metal processes. Preliminary experiments were performed. Also, the literature indicates that sputtered aluminum films may be successfully patterned using the left-off technique provided the substrate temperature remains low and the argon pressure in the chamber is relatively high at the time of sputtering. Vendors associated with dry processing equipment are identified. A literature search relative to future trends in VLSI fabrication techniques is described

    New reconstructive methods in scientific illustration with reference to systematic herpetology.

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    The present work and papers published earlier by the author, together with a detailed introductory chapter, describe the work of scientific illustration at a specialized level and how the development of drawing techniques can contribute to an understanding of the morphology and systematics of snakes. This work has its roots in the background of the writer as a scientific illustrator. The early phase reflects the disciplines and influence of science, leading to involvement, first with fishes, then reptiles. A later phase arose from contact with the scientific staff of institutions, such as the natural History Museum London leading to an appreciation of, and participation in taxonomy. Illustration+visual recording of data, augmented by field experience, comprised the principal component in the research. Practical considerations directed the study towards snakes from Algeria. This work has resulted in seven published papers, most in collaboration with established scientists mainly on the herpetology of North Africa. A synopsis of each paper is provided. In some cases the writer's collaborators are from disciplines such as molecular sequencing and computer analysis. Traditional taxonomic characters are reviewed and new features are suggested to provide alternative approaches and applications. The species under investigation are viewed in the light of current practice in taxonomy and newly published evidence has been considered. Some related aspects are touched on: genetics, for example is not normally a matter for illustration but is of direct concern, as it is a parallel discipline in the investigation of interrelationships of taxa and thus cannot be disregarded. The illustrative techniques demonstrated here are inseparable from the recording of morphological data. Such recording requires prior perception of what is to be recorded and it is that interpretation which contributes. In processing of material, the experience of graphic recording of observations resulted in the acquisition of a degree of understanding, which was very useful in resolving taxonomic problems, and added an extra dimension. The contribution that graphic art has made to some problems in taxonomy is discussed. Specimens in a variety of conditions of preservation require a variety of approaches and techniques of illustration. It has been found that artistic input changed from being a purely descriptive record to a means by which, in conjunction with the more standard techniques, novel conclusions could be derived, thus demonstrating an original contribution to taxonomic problems

    A model for the fast ionic diffusion in alumina-doped LiI

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    Lithium Iodide shows enhanced ionic conductivity when doped with a powder of the insulator, alumina. We extend Landauer's effective medium model to see if the observations are consistent with a high conductivity layer forming on each non-conducting particle. The predictions are consistent with experiment provided one assumes the layer a few hundred Angstroms thick. At the outside, away from the particle, the enhancement of conductivity should fall off slowly, as in Debye-Huckel screening, whereas it is possible a new phase forms close to the insulator surface

    Post heat treatment effects on double layer metal structures for VLSI applications

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    The realization of high yield double layer metal systems using wet chemistry processes and the ability to extend yields beyond that attainable with wet chemistry by means of post sintering processes at temperatures below 500 C for potential applications in very large scale integration structures were studied. Yields in excess of 98% and average total contact resistance of less than 150 ohms and 200 ohms were realized for a series of 560 vias of 0.5 X 0.5 mils and 0.2 X 0.2 mils in size, respectively

    Digital Scotland, the relevance of library research and the Glasgow Digital Library Project

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    The Glasgow Digital Library (GDL) Project has a significance over and above its primary aim of creating a joint digital library for the citizens of Glasgow. It is also both an important building block in the development of a planned and co-ordinated 'virtual Scotland' and a rich environment for research into issues relevant to that enterprise. Its creation comes at a time of political, social, economic and cultural change in Scotland, and may be seen, at least in part, as a response to a developing Scottish focus in these areas, a key element of which is a new socially inclusive and digitally driven educational vision and strategy based on the Scottish traditions of meritocratic education, sharing and common enterprise, and a fiercely independent approach. The initiative is based at the Centre for Digital Library Research at Strathclyde University alongside a range of other projects of relevance both to the development of a coherent virtual landscape in Scotland and to the GDL itself, a supportive environment which allows it to draw upon the research results and staff expertise of other relevant projects for use in its own development and enables its relationship to virtual Scotland to be both explored and developed more readily. Although its primary aim is the creation of content (based initially on electronic resources created by the institutions, on public domain information, and on joint purchases and digitisation initiatives) the project will also investigate relationships between regional and national collaborative collection management programmes with SCONE (Scottish Collections Network Extension project) and relationships between regional and national distributed union catalogues with CAIRNS (Co-operative Academic Information Retrieval Network for Scotland) and COSMIC (Confederation of Scottish Mini-Clumps). It will also have to tackle issues associated with the management of co-operation

    Casimir effect in rugby-ball type flux compactifications

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    As a continuation of the work in \cite{mns}, we discuss the Casimir effect for a massless bulk scalar field in a 4D toy model of a 6D warped flux compactification model,to stabilize the volume modulus. The one-loop effective potential for the volume modulus has a form similar to the Coleman-Weinberg potential. The stability of the volume modulus against quantum corrections is related to an appropriate heat kernel coefficient. However, to make any physical predictions after volume stabilization, knowledge of the derivative of the zeta function, ζ(0)\zeta'(0) (in a conformally related spacetime) is also required. By adding up the exact mass spectrum using zeta function regularization, we present a revised analysis of the effective potential. Finally, we discuss some physical implications, especially concerning the degree of the hierarchy between the fundamental energy scales on the branes. For a larger degree of warping our new results are very similar to the previous ones \cite{mns} and imply a larger hierarchy. In the non-warped (rugby-ball) limit the ratio tends to converge to the same value, independently of the bulk dilaton coupling.Comment: 13 pages, 6 figures, accepted for publication in PR
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