Francis Bacon and the practice of painting

This article addresses the question about why painting continues to be relevant in our contemporary cultural climate. A key reason can be located in the means by which the material of paint can be utilized, manipulated, and perceived through entire sensory and bodily mechanisms. As the practice of Francis Bacon (1909–1992) demonstrates, it is within the elusive behaviour and handling of pigment that the full transformative potential of painting can be released. In fact it can activate a whole field of sensory responses on the part of painter and viewer. The painter can manipulate the material to achieve a variety of effects but needs also to acknowledge how the material can potentially assume an independent life of its own, an almost unruly character. The strength and enduring quality of painting which links modern to postmodern practice, lies in its potential to utilise the painter's tacit skills as well as releasing the inherent and ‘unruly’ qualities of the pigment. The potential of painting practice lies within the orbit of the individual painter who can recognize implicitly how to let the paint ‘work’ according to the needs of the image being constructed

Analysing BitTorrent's seeding strategies

BitTorrent is a typical peer-to-peer (P2P) file distribution application that has gained tremendous popularity in recent years. A considerable amount of research exists regarding BitTorrent’s choking algorithm, which has proved to be effective in preventing freeriders. However, the effect of the seeding strategy on the resistance to freeriders in BitTorrent has been largely overlooked. In addition to this, a category of selfish leechers (termed exploiters), who leave the overlay immediately after completion, has never been taken into account in the previous research. In this paper two popular seeding strategies, the Original Seeding Strategy (OSS) and the Time- based Seeding Strategy (TSS), are chosen and we study via mathematical models and simulation their effects on freeriders and exploiters in BitTorrent networks. The mathematical model is verified and we discover that both freeriders and exploiters impact on system performance, despite the seeding strategy that is employed. However, a selfish-leechers threshold is identified; once the threshold is exceeded, we find that TSS outperforms OSS – that is, TSS reduces the negative impact of selfish lechers more effectively than OSS. Based on these results we discuss the choice of seeding strategy and speculate as to how more effective BitTorrent-based file distribu- tion applications can be built

Developing performance-portable molecular dynamics kernels in Open CL

This paper investigates the development of a molecular dynamics code that is highly portable between architectures. Using OpenCL, we develop an implementation of Sandia’s miniMD benchmark that achieves good levels of performance across a wide range of hardware: CPUs, discrete GPUs and integrated GPUs. We demonstrate that the performance bottlenecks of miniMD’s short-range force calculation kernel are the same across these architectures, and detail a number of platform- agnostic optimisations that improve its performance by at least 2x on all hardware considered. Our complete code is shown to be 1.7x faster than the original miniMD, and at most 2x slower than implementations individually hand-tuned for a specific architecture

Low income dynamics in 1990s Britain

This paper analyses low income dynamics in Britain using the first four waves of the British Household Panel Survey. There is much low income turnover: although there is a small group of people who are persistently poor, more striking is the relatively large number of low income escapers and entrants from one year to the next. Simulations using estimated low income exit and re-entry rates demonstrate the importance of repeated low income spells for explaining a person’s experience of low income over a given period. We also document the characteristics of low income stayers, escapers and entrants.

How generational are generational trends in in vehicle ownership and use?

There are longstanding debates about the differences between generations. This includes claims that Millennials have fundamentally different preferences for driving and vehicle ownership when compared to prior generations. Using data on the United Kingdom I do indeed find large observed differences in driving habits and vehicle ownership between Millennials and prior generations. However, once certain confounding factors are controlled for these differences largely disappear. These results confirm findings from related work that looked at the United States, indicating that generational trends in driving habits are likely a fairly general phenomenon

The economic costs of NIMBYism: evidence from renewable energy projects

Large infrastructure projects can have important social benefits, but also prompt strong local opposition. This is often attributed to NIMBY (Not In My Backyard) attitudes. I study the economic costs of NIMBYism and local planning restrictions by looking at renewable energy projects. Using hedonic methods I find that wind projects can impose significant external local costs, while solar projects do not. I then show that planning officials are particularly sensitive to local costs in their area. The resulting misallocation of investment may have increased wind power deployment costs by 10-29%. I conclude by examining compensation payments as a policy solution

Connectivity-guaranteed and obstacle-adaptive deployment schemes for mobile sensor networks

Mobile sensors can relocate and self-deploy into a network. While focusing on the problems of coverage, existing deployment schemes largely over-simplify the conditions for network connectivity: they either assume that the communication range is large enough for sensors in geometric neighborhoods to obtain location information through local communication, or they assume a dense network that remains connected. In addition, an obstacle-free field or full knowledge of the field layout is often assumed. We present new schemes that are not governed by these assumptions, and thus adapt to a wider range of application scenarios. The schemes are designed to maximize sensing coverage and also guarantee connectivity for a network with arbitrary sensor communication/sensing ranges or node densities, at the cost of a small moving distance. The schemes do not need any knowledge of the field layout, which can be irregular and have obstacles/holes of arbitrary shape. Our first scheme is an enhanced form of the traditional virtual-force-based method, which we term the Connectivity-Preserved Virtual Force (CPVF) scheme. We show that the localized communication, which is the very reason for its simplicity, results in poor coverage in certain cases. We then describe a Floor-based scheme which overcomes the difficulties of CPVF and, as a result, significantly outperforms it and other state-of-the-art approaches. Throughout the paper our conclusions are corroborated by the results from extensive simulations

Profiling large-scale lazy functional programs

The LOLITA natural language processing system is an example of one of the ever increasing number of large-scale systems written entirely in a functional programming language. The system consists of over 50,000 lines of Haskell code and is able to perform a number of tasks such as semantic and pragmatic analysis of text, context scanning and query analysis. Such a system is more useful if the results are calculated in real-time, therefore the efficiency of such a system is paramount. For the past three years we have used profiling tools supplied with the Haskell compilers GHC and HBC to analyse and reason about our programming solutions and have achieved good results; however, our experience has shown that the profiling life-cycle is often too long to make a detailed analysis of a large system possible, and the profiling results are often misleading. A profiling system is developed which allows three types of functionality not previously found in a profiler for lazy functional programs. Firstly, the profiler is able to produce results based on an accurate method of cost inheritance. We have found that this reduces the possibility of the programmer obtaining misleading profiling results. Secondly, the programmer is able to explore the results after the execution of the program. This is done by selecting and deselecting parts of the program using a post-processor. This greatly reduces the analysis time as no further compilation, execution or profiling of the program is needed. Finally, the new profiling system allows the user to examine aspects of the run-time call structure of the program. This is useful in the analysis of the run-time behaviour of the program. Previous attempts at extending the results produced by a profiler in such a way have failed due to the exceptionally high overheads. Exploration of the overheads produced by the new profiling scheme show that typical overheads in profiling the LOLITA system are: a 10% increase in compilation time; a 7% increase in executable size and a 70% run-time overhead. These overheads mean a considerable saving in time in the detailed analysis of profiling a large, lazy functional program