Implementing a definitive notation for interactive graphics

This paper describes the application of a definitive (definition-based) programming paradigm to graphics software. The potential merits of using definitive principles for interactive graphics were considered from a theoretical perspective in [Be87]; this paper is complementary, in that it describes the insights gained through practical experience in implementing a prototype system. The main characteristics of the prototype implementation are illustrated by simple examples. Analysis of the abstract machine model underlying this implementation suggests a general purpose programming paradigm based on definitive principles that can be applied to more ambitious applications

Embodied carbon and construction cost differences between Hong Kong and Melbourne buildings

Limiting the amount of embodied carbon in buildings can help minimize the damaging impacts of global warming through lower upstream emission of CO2. This study empirically investigates the embodied carbon footprint of new-build and refurbished buildings in both Hong Kong and Melbourne to determine the embodied carbon profile and its relationship to both embodied energy and construction cost. The Hong Kong findings suggest that mean embodied carbon for refurbished buildings is 33-39% lower than new-build projects, and the cost for refurbished buildings is 22-50% lower than new-build projects (per square metre of floor area). The Melbourne findings, however, suggest that mean embodied carbon for refurbished buildings is 4% lower than new-build projects, and the cost for refurbished buildings is 24% higher than new-build projects (per square metre of floor area). Embodied carbon ranges from 645-1,059 kgCO2e/m2 for new-build and 294-655 kgCO2e/m2 for refurbished projects in Hong Kong, and 1,138-1,705 kgCO2e/m2 for new-build and 900-1,681 kgCO2e/m2 for refurbished projects in Melbourne. The reasons behind these locational discrepancies are explored and critiqued. Overall, a very strong linear relationship between embodied energy and construction cost in both cities was found and can be used to predict the former, given the latter

Returns to Skill and Teacher Wage Premiums: What Can We Learn By Comparing the Teacher and Private Sector Labor Markets?

Estimates the wage differences between public school teachers and other professions over time by gender, advanced degree, major, college quality, and technical and academic skills. Explores the incentives needed to attract and retain effective teachers

Introduction to Graphene Electronics -- A New Era of Digital Transistors and Devices

The speed of silicon-based transistors has reached an impasse in the recent decade, primarily due to scaling techniques and the short-channel effect. Conversely, graphene (a revolutionary new material possessing an atomic thickness) has been shown to exhibit a promising value for electrical conductivity. Graphene would thus appear to alleviate some of the drawbacks associated with silicon-based transistors. It is for this reason why such a material is considered one of the most prominent candidates to replace silicon within nano-scale transistors. The major crux here, is that graphene is intrinsically gapless, and yet, transistors require a band-gap pertaining to a well-defined ON/OFF logical state. Therefore, exactly as to how one would create this band-gap in graphene allotropes is an intensive area of growing research. Existing methods include nano-ribbons, bilayer and multi-layer structures, carbon nanotubes, as well as the usage of the graphene substrates. Graphene transistors can generally be classified according to two working principles. The first is that a single graphene layer, nanoribbon or carbon nanotube can act as a transistor channel, with current being transported along the horizontal axis. The second mechanism is regarded as tunneling, whether this be band-to-band on a single graphene layer, or vertically between adjacent graphene layers. The high-frequency graphene amplifier is another talking point in recent research, since it does not require a clear ON/OFF state, as with logical electronics. This paper reviews both the physical properties and manufacturing methodologies of graphene, as well as graphene-based electronic devices, transistors, and high-frequency amplifiers from past to present studies. Finally, we provide possible perspectives with regards to future developments.Comment: This is an updated version of our review article, due to be published in Contemporary Physics (Sept 2013). Included are updated references, along with a few minor corrections. (45 pages, 19 figures

A note on the third family of N=2 supersymmetric KdV hierarchies

We propose a hamiltonian formulation of the $N=2$ supersymmetric KP type hierarchy recently studied by Krivonos and Sorin. We obtain a quadratic hamiltonian structure which allows for several reductions of the KP type hierarchy. In particular, the third family of $N=2$ KdV hierarchies is recovered. We also give an easy construction of Wronskian solutions of the KP and KdV type equations

Collapse of Vacuum Bubbles in a Vacuum

Motivated by the discovery of a plenitude of metastable vacua in a string landscape and the possibility of rapid tunneling between these vacua, we revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications to inflationary physics.Comment: 8 pages including 6 figures, LaTex; references adde

A unified 'bang-bang' principle with respect to R-invariant performance benchmarks

published_or_final_versio