The magic of algorithm design and analysis: teaching algorithmic skills using magic card tricks

We describe our experience using magic card tricks to teach algorithmic skills to first-year Computer Science undergraduates. We illustrate our approach with a detailed discussion on a card trick that is typically presented as a test to the psychic abilities of an audience. We use the trick to discuss concepts like problem decomposition, pre- and post-conditions, and invariants. We discuss pedagogical issues and analyse feedback collected from students. The feedback has been very positive and encouraging.(undefined

Deformation mechanisms of Gum metal

Gum metal (Ti-36Nb-2Ta-3Zr-0.3O) is a recently developed multifunctional bcc titanium (p Ti) alloy that exhibits high strength (> 1 GPa), high ductility (>10%) and high yield strain (~2.5%). In addition, this alloy possesses the invar and elinvar properties, and is highly cold workable. The encouraging mechanical properties and workability of Gum metal mean that it is a candidate material in a range of applications, from biomedical implants to aerospace and military applications. The deformation mechanisms of Gum metal have previously been reported to involve ideal shear. The rational for this suggestion is that Gum metal was designed on first principles, such that the value of the shear modulus (C') assumes a very low value. This implies that the ideal shear stress is comparable to the actual strength, such that deformation can proceed via ideal shear. Furthermore, the observation of ‘giant shear steps’ in transmission electron microscopy (TEM), whose orientation does not correspond to any bcc slip or twin systems is considered to be consistent with this hypothesis. However, the existence of a deformation mechanism involving ideal shear is against metallurgical wisdom. Many other titanium alloys of similar composition are also known to exhibit a low C. However, these alloys deform via a stress induced superelastic martensitic transformation. Therefore the aim of this work is to improve our understanding of the micromechanisms of this alloy. The single crystal elastic constants (C¡¡) of Gum metal were acquired with the aid of in- situ synchrotron X-ray diffraction (SXRD) and an Eshelby-Kroner-Kneer self consistent model. The results showed that although C is low in this alloy, the ideal shear strength (>2 GPa) is still above the material’s tensile strength, implying deformation cannot occur via ideal shear. Furthermore, analysis of the SXRD spectra during cyclic loading suggests that Gum metal undergoes a stress-induced superelastic martensitic (a") transformation. The SXRD results were complemented with TEM characterisation, which showed the presence of the a" phase, and the © phase, which exhibited a plate-like morphology. In addition, deformation twins of the type {1 12} were identified. Structures similar to the giant shear steps were observed and their formation is believed to be due to a" variants nucleating from co plates or twin boundaries. The effect of processing route and chemical composition on the deformation mechanisms and mechanical properties of Gum metal were also investigated. A more cost effective processing route involving ingot metallurgy was trialled and the mechanical properties were comparable to the alloys produced via powder metallurgy. Oxygen was found to suppress the amount of transformation strain in Gum metal (by increasing C'); and hence the majority of the observed superelastic strain was due to the low Young’s modulus and high yield strain of the p phase. However, oxygen increased the stress for permanent deformation, thus allowing more stable superelasticity. Prior deformation (extrusion or cold rolling) was found to increase the amount of transformation strain. This was considered to be a result of mechanical working providing nucleation sites, such as the co phase and twins, from which, the a" phase was able to nucleate. The amount of transformation strain could be increased through control of specimen texture. The specimens produced via the ingot metallurgy processing route, involving casting and extrusion were found to exhibit the greatest transformation strain

Structure prediction of alkaline earth oxide nanoclusters in vacuo and on graphene

Can nanoclusters be used in materials design?. Knowing the structure of nanoclusters can give insight into their properties, knowing which nanocluster sizes have only one stable structure can inform experiment and knowing their behaviour on a surface is important as they are expected to be stabilised in such an environment.In this thesis, an evolutionary algorithm has been used in conjunction with interatomic potentials and density functional theory to elucidate the structures of (BaO)n nanoclusters where n= 1 to 18 and 24. Then, data mining was used to find structures of strontium, calcium and magnesium oxides of the same sizes. It was found that for barium oxide clusters, sizes n= 4,6,8,10 and 16 are the best synthesis targets as they have one especially low-energy structure and are also relatively low energy compared to other sizes. Synthesis target sizes for the other three oxides were: sizes n= 9,15,16,18 and 24 for (MgO)n; sizes n= 8,9,12,16,18 and 24 for (CaO)n; and the greatest number of sizes for (SrO)n clusters (n= 8,9,10,12,13,15,16,18 and 24).Cuboid rocksalt cuts were particularly energetically favourable for barium, strontium and calcium oxides, and therefore these cuboids were looked at in greater detail. In particular, the influence of Madelung constants on their stability is investigated, and nanowire, slab and bulk energies are extrapolated from their energies.A set of interatomic potentials was developed to investigate the behaviour of these nanoclusters above a graphene surface, and their interaction with the surface was further looked into

Carbon in the Galaxy: Studies from Earth and Space

Presented here is the text of the invited papers presented during a meeting entitled, Carbon in the Galaxy: Studies from Earth and Space, that was held at NASA Ames Research Center on November 5 and 6, 1987. For completeness, abstracts from all of the poster papers and the text of a paper summarizing what was learned during the course of the meeting are also included. The underlying premise for the meeting was that there is much to be gained by bringing together scientists from very different disciplines, all of whom study carbon in different ways for different reasons. The interchanges took place during the meeting and the contents of the enclosed papers validate that premise

Regulatory Transgression? Drivers, Aims and Effects of Money Laundering and Terrorism Financing Regulation in Pakistan

The harmonization of money laundering and terrorism financing regulation is a key feature of the contemporary global economy. Since 9/11 particularly, the remarkable growth of this field of regulation has been characterized by both scale and intensity. However, this drive towards regulatory convergence is puzzling: the efficacy of the regulation remains unproven while the content of the regulation poses significant challenges to both criminal justice systems and human rights frameworks. The corollary to these observations: who does the regulation benefit? With the understanding that all regulation is an expression of some interest/s, this study analyses the trajectory of this global regulation and its products. My aim is to understand who gains what from regulation and how they influence this regulatory evolution. Focusing on Pakistan, my research will examine how anti money laundering (AML) and counter terrorism financing (CTF) regulation and its increasing demands for information affects established power hierarchies in states, between states and among states. At the international and transnational levels, I’m interested in how a universal financial regulation discourse threatens basic rights and freedoms and how this exercise of power affects civil, political and economic rights in a country, its foreign policy as well as geopolitics. At the national level, I’m curious about how such regulatory power with its distinctive objectives interacts or conflicts with or even amplifies the control of established power centres in a polity. The analysis of power relations in the case of Pakistan will be particularly instructive for several reasons. First, the size of its formal economy is rivalled (if not surpassed) by the informal or black economy and the money laundering industry is all the more powerful for processing illicit funds from crime; corruption; and tradeand taxation-related malpractices. Second, Pakistan’s military establishment has long supported militancy as a foreign policy tool, both materially and financially, and to date orients its foreign policy accordingly. Finally, the military establishment also relies on intrusive surveillance tools to control civil society. The opacity of the discourse regarding international financial governance makes a closer scrutiny of its aims a critical imperative. By exploring the links between regulation, power, knowledge and surveillance, I hope to understand the aims of this power and offer a critique of financial regulation as a technique of power and the politics of making and administering AML/ CTF regulation, both across the globe and within states

Regulatory Transgression? Drivers, Aims and Effects of Money Laundering and Terrorism Financing Regulation in Pakistan

The harmonization of money laundering and terrorism financing regulation is a key feature of the contemporary global economy. Since 9/11 particularly, the remarkable growth of this field of regulation has been characterized by both scale and intensity. However, this drive towards regulatory convergence is puzzling: the efficacy of the regulation remains unproven while the content of the regulation poses significant challenges to both criminal justice systems and human rights frameworks. The corollary to these observations: who does the regulation benefit? With the understanding that all regulation is an expression of some interest/s, this study analyses the trajectory of this global regulation and its products. My aim is to understand who gains what from regulation and how they influence this regulatory evolution. Focusing on Pakistan, my research will examine how anti money laundering (AML) and counter terrorism financing (CTF) regulation and its increasing demands for information affects established power hierarchies in states, between states and among states. At the international and transnational levels, Im interested in how a universal financial regulation discourse threatens basic rights and freedoms and how this exercise of power affects civil, political and economic rights in a country, its foreign policy as well as geopolitics. At the national level, Im curious about how such regulatory power with its distinctive objectives interacts or conflicts with or even amplifies the control of established power centres in a polity. The analysis of power relations in the case of Pakistan will be particularly instructive for several reasons. First, the size of its formal economy is rivalled (if not surpassed) by the informal or black economy and the money laundering industry is all the more powerful for processing illicit funds from crime; corruption; and trade- and taxation-related malpractices. Second, Pakistans military establishment has long supported militancy as a foreign policy tool, both materially and financially, and to date orients its foreign policy accordingly. Finally, the military establishment also relies on intrusive surveillance tools to control civil society. The opacity of the discourse regarding international financial governance makes a closer scrutiny of its aims a critical imperative. By exploring the links between regulation, power, knowledge and surveillance, I hope to understand the aims of this power and offer a critique of financial regulation as a technique of power and the politics of making and administering AML/ CTF regulation, both across the globe and within states

A fundamental analysis of means of producing and storing energy

The goal of this dissertation is to examine some of the most promising non-fossil means for producing electricity and storing energy for transportation, to provide a thorough and (hopefully) unbiased assessment of which hold the most promise, and therefore warrant further research focus. Additionally, recommendations are made for potential means for improving proposed or existing technologies, in particular the technology of a new subcritical reactor design using an electronuclear driver and thermal transmutation of transuranic actinides. The high energy density of liquid hydrocarbon fuels is ideal for transportation applications, but our ability to sustainably produce such fuels (i.e. biofuels) is limited by the low photosynthetic efficiency achieved by plants. While some proposals are made herein to make the most of the potential of biofuels, their limitations ultimately will require the storage of electrical energy (in batteries, hydrogen, or mechanical energy storage) if we are to eliminate our dependence on petroleum for transportation. The outcome of this analysis is that lithium-ion batteries are best suited for such an application. This is based on a significantly better net efficiency with only moderately lower energy density compared to the best means of storing hydrogen, and no additional infrastructure requirements. The analysis also indicates the direction research should take to further improve lithium-ion batteries. Since the sustainability of electric vehicles depends on the means of producing electricity, a focus of this dissertation is assessing the potential to produce electricity with advanced nuclear fission and fusion reactors. While magnetic and inertial confinement fusion are interesting from the standpoint of the plasma and nuclear physics involved, the analysis presented here illustrates that the potential for commercial electricity production with either is slim, with several potential deal breakers. Further, muon catalyzed fusion is shown to offer no practical means of producing net energy. Furthermore, fusion fuels other than Deuterium-Tritium (DT) have triple product requirements roughly two orders of magnitude greater for net energy production. The analysis of a catalyzed deuterium plasma presented herein shows it to be less promising than previous analyses have indicated. The flux of 14.1 MeV neutrons from a DT plasma presents a significant challenge that is likely to limit or prevent commercialization of DT fusion power. The primary alternative approach that may become viable is a so-called helium catalyzed DD cycle. However, there are two significant challenges (the need for active tritium removal and the large onsite tritium inventory) that must be addressed for this option to have significant potential. Greater focus therefore should be placed on advanced fission reactors, in particular thermal thorium reactors and driven subcritical reactors, such as of the general design proposed in this dissertation

Tastes of Sovereignty : An Ethnography of Sámi Food Movements in Arctic Sweden

In this dissertation, I examine the process of building a Sámi food movement in northern Sweden. Using 15 months of ethnographic research that included observation of food events (n=100) and semi-structured interviews with food producers and activists (n=47), I describe how Sámi individuals are incorporating global food activism frameworks into their efforts to maintain Sámi cultural and livelihood practices. Two frameworks have become salient to Sámi efforts: food sovereignty and rural food development. I find that on the one hand food sovereignty provides a discourse that enables Sámi activists to address their concerns with land access and climate change, which threaten their food production. On the other hand, the protection and development of their heritage foods, through programs like Slow Food and other third party certifications, enable them to connect with consumers and to address their concern for the cooptation of Sámi knowledge, which equally threatens their ability to make a living selling Sámi foods and culinary knowledge. I demonstrate that new discourses and spaces become available – nutrition science discourses and national food conferences for example – which Sámi activists accustomize for their own ends. This dissertation is one of the first to address how indigenous sovereignty movements and food movements are together enabling indigenous peoples to work towards sovereignty in new discourses and spaces. It advances our understanding of how food movements can contribute to building indigenous sovereignty and economies, at the same time it introduces us to some of the risks inherent to this approach