Materials chemistry: Design, Synthesis and Functionality

The need to synthesise new materials is driven by the need for materials with specific functionality, which is in turn driven by the intended final application. In this talk we will explore the design of materials based on the application for which they are intended and the ways in which they can be synthesised and characterised. From the materials perspective we will focus on inorganic–organic hybrid materials, metal phosphonates and metal oxides, and discuss how we can make such materials which exhibit properties of luminescence and antimicrobial activity. Characterisation of materials using crystallography, photoluminescence and adsorption spectroscopies, and how the biological activity of materials is determined will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Materials chemistry: design and synthesis of luminescent and biologically active materials

The need to synthesise new materials is driven by the need for materials with specific properties. Those properties are determined by the final application. In this talk we will explore the design of materials which are used in Luminescent and Anti-microbial applications. From the materials perspective we will focus on inorganic–organic hybrid materials, metal phosphonates and metal oxides, and discuss how we can make such materials. We will consider how the choice of metal changes the luminescent response and how materials can be constructed by design at the atomic level. considering antimicrobial materials we will discuss how structure influences the release of active species and can result in materials which are therapeutic but not toxic.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Computational Methods for Nucleosynthesis and Nuclear Energy Generation

This review concentrates on the two principle methods used to evolve nuclear abundances within astrophysical simulations, evolution via rate equations and via equilibria. Because in general the rate equations in nucleosynthetic applications form an extraordinarily stiff system, implicit methods have proven mandatory, leading to the need to solve moderately sized matrix equations. Efforts to improve the performance of such rate equation methods are focused on efficient solution of these matrix equations, by making best use of the sparseness of these matrices. Recent work to produce hybrid schemes which use local equilibria to reduce the computational cost of the rate equations is also discussed. Such schemes offer significant improvements in the speed of reaction networks and are accurate under circumstances where calculations with complete equilibrium fail.Comment: LaTeX2e with graphicx, 40 Pages with 5 embedded figures. To be published in Computational Astrophysics, The Journal of Computational and Applied Mathematics, eds. H. Riffert, K. Werne

Silicon Burning I: Neutronization and the Physics of Quasi-Equilibrium

As the ultimate stage of stellar nucleosynthesis, and the source of the iron peak nuclei, silicon burning is important to our understanding of the evolution of massive stars and supernovae. Our reexamination of silicon burning, using results gleaned from simulation work done with a large nuclear network (299 nuclei and more than 3000 reactions) and from independent calculations of equilibrium abundance distributions, offers new insights into the quasi-equilibrium mechanism and the approach to nuclear statistical equilibrium. We find that the degree to which the matter has been neutronized is of great importance, not only to the final products but also to the rate of energy generation and the membership of the quasi-equilibrium groups. A small increase in the global neutronization results in much larger free neutron fluences, increasing the abundances of more neutron-rich nuclei. As a result, incomplete silicon burning results in neutron richness among the isotopes of the iron peak much larger than the global neutronization would indicate. Finally, we briefly discuss the limitations and pitfalls of models for silicon burning currently employed within hydrodynamic models. In a forthcoming paper we will present a new approximation to the full nuclear network which preserves the most important features of the large nuclear network calculations at a significant improvement in computational speed. Such improved methods are ideally suited for hydrodynamic calculations which involve the production of iron peak nuclei, where the larger network calculation proves unmanageable.Comment: 44 pages of TeX with 25 Postscript figures, uses psfig.sty, To appear in the The Astrophysical Journal, April 1 1996. Complete PostScript version of the paper is also available from http://tycho.as.utexas.edu/~raph/Publications.htm

Usability Evaluation in Virtual Environments: Classification and Comparison of Methods

Virtual environments (VEs) are a relatively new type of human-computer interface in which users perceive and act in a three-dimensional world. The designers of such systems cannot rely solely on design guidelines for traditional two-dimensional interfaces, so usability evaluation is crucial for VEs. We present an overview of VE usability evaluation. First, we discuss some of the issues that differentiate VE usability evaluation from evaluation of traditional user interfaces such as GUIs. We also present a review of VE evaluation methods currently in use, and discuss a simple classification space for VE usability evaluation methods. This classification space provides a structured means for comparing evaluation methods according to three key characteristics: involvement of representative users, context of evaluation, and types of results produced. To illustrate these concepts, we compare two existing evaluation approaches: testbed evaluation [Bowman, Johnson, & Hodges, 1999], and sequential evaluation [Gabbard, Hix, & Swan, 1999]. We conclude by presenting novel ways to effectively link these two approaches to VE usability evaluation

Atypical Thermonuclear Supernovae from Tidally Crushed White Dwarfs

Suggestive evidence has accumulated that intermediate mass black holes (IMBH) exist in some globular clusters. As stars diffuse in the cluster, some will inevitable wander sufficiently close to the hole that they suffer tidal disruption. An attractive feature of the IMBH hypothesis is its potential to disrupt not only solar-type stars but also compact white dwarf stars. Attention is given to the fate of white dwarfs that approach the hole close enough to be disrupted and compressed to such extent that explosive nuclear burning may be triggered. Precise modeling of the dynamics of the encounter coupled with a nuclear network allow for a realistic determination of the explosive energy release, and it is argued that ignition is a natural outcome for white dwarfs of all varieties passing well within the tidal radius. Although event rates are estimated to be significantly less than the rate of normal Type Ia supernovae, such encounters may be frequent enough in globular clusters harboring an IMBH to warrant a search for this new class of supernova.Comment: 13 pages, 4 figures, ApJ, accepte

How to Choose the European Executive: A Counterfactual Analysis (1979-1999)

In this paper, we use data on roll-call votes by MEP’s in the five elected EuropeanParliaments (1979, 1984, 1989, 1994, 1999) to evaluate the likely impact of current proposalsin the Convention on the Future of Europe for the appointment of the European executive. Wefind (a) that the different procedures for appointing the Commission lead to quite differentresults in terms of the composition of the Commission, (b) that election of the President of theCommission by the national parliaments (our preferred mode of appointment) gives the resultthat is most in line with the observed composition of the Commission since 1979, whereas (c)election by the European Parliament creates a ‘built-in’ form of divided government betweenthe Council and the Commissio n that could prove counterproductive for the functioning ofEuropean institutions.European Parliament; European Parliament; European Convention; European Commission; European Council

Is the EU really run by unelected bureaucrats?

Much of the UK’s referendum debate has focused on the extent to which EU decision-making is democratic, with the European Commission a source of particular criticism from leave campaigners on the basis that it is unelected. Simon Hix writes that while there are legitimate problems with the EU’s system of democracy, there is little to justify the idea that the EU is run by unelected bureaucrats, and the procedures in place for appointing the Commission are now far more democratic than they were in the past