Steady and Stable: Numerical Investigations of Nonlinear Partial Differential Equations

Excerpt: Mathematics is a language which can describe patterns in everyday life as well as abstract concepts existing only in our minds. Patterns exist in data, functions, and sets constructed around a common theme, but the most tangible patterns are visual. Visual demonstrations can help undergraduate students connect to abstract concepts in advanced mathematical courses. The study of partial differential equations, in particular, benefits from numerical analysis and simulation

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Grouted repairs to steel offshore structures A summary report of a programme of tests carried out by Wimpey Laboratories for the Department of Energy

18.00SIGLEAvailable from British Library Lending Division - LD:6244.38(OTH--84-202) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Fabrication of high numerical aperture fluoroaluminate fibres

A family of fluoroaluminate glasses has been identified as the ideal host for doping with Nd3+ for use in the development of lasers and amplifiers in the second telecom window. For optimum performance, a fibre with high numerical aperture (NA), fibre length of 5cm and loss of 10dB/m is required. The high NA implies a core diameter of 3µm is needed and thus the core-to-clad interface represents greater than 50% of the core area. Crystallisation in the interface introduces large scattering losses. The critical step in the fabrication process is preform fabrication. We will present results comparing the different techniques employed and thermal and mechanical fabrication process modelling consistent with our experimental observations and detail the advantages and limiting parameters for the different processes. Rod-in-tube is the simplest technique of preform fabrication and works exceptionally well for oxide glasses. Fluorides are highly prone to surface crystallisation. We have looked at the fibre losses as functions of polishing material, polishing time, and etching. It is a good first step to test the optical properties and performance in a fibre. Rotational casting is usually employed in fluoride glasses. The high Tg(450°C) and large expansion coefficient ( >150x10-7/°K. We will compare the results of rotational casting with built-in-casting and the influence of processing time, thermal history and mould material (thermal conductivity). Extrusion as a procedure for preform fabrication is specially suitable for fluoraluminates. Extrusion allows one to operate at temperatures nearer Tg than Tx. Preforms can be prepared with small cores and thus avoid the thermal cycling involved in sleeving to get the singlemode fibre. To date our losses for fibres with 5-8µm cores vary from 100dB/m using rod-in-tube to 20dB/m using extrusion

A 1317nm neodymium doped fluoride glass waveguide laser

Laser emission at 1317nm has been observed for the first time in a neodymium doped fluoroaluminate glass waveguide fabricated by a combination of hot dip spin coating and direct UV writing

Difluorinated analogues of shikimic acid

Investigations into the quinate to shikimate transformation have been carried out, the results of which have been exploited in the synthesis of a novel difluoromethylene homologue of shikimic acid from (-)-quinic acid. Martin's sulfurane {Ph2S[OC(CF3)(2)Ph](2)} was the reagent of choice for the key dehydration step of this synthesis. The results of investigations into the synthesis of the important natural product analogue, 6,6-difluoroshikimic acid are also reported. (C) 2003 Elsevier Science Ltd. All rights reserved