4,517 research outputs found

    Big data and humanitarian supply networks: Can Big Data give voice to the voiceless?

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright © 2013 IEEE.Billions of US dollars are spent each year in emergency aid to save lives and alleviate the suffering of those affected by disaster. This aid flows through a humanitarian system that consists of governments, different United Nations agencies, the Red Cross movement and myriad non-governmental organizations (NGOs). As scarcer resources, financial crisis and economic inter-dependencies continue to constrain humanitarian relief there is an increasing focus from donors and governments to assess the impact of humanitarian supply networks. Using commercial (`for-profit') supply networks as a benchmark; this paper exposes the counter-intuitive competition dynamic of humanitarian supply networks, which results in an open-loop system unable to calibrate supply with actual need and impact. In that light, the phenomenon of Big Data in the humanitarian field is discussed and an agenda for the `datafication' of the supply network set out as a means of closing the loop between supply, need and impact

    A Penrose polynomial for embedded graphs

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    We extend the Penrose polynomial, originally defined only for plane graphs, to graphs embedded in arbitrary surfaces. Considering this Penrose polynomial of embedded graphs leads to new identities and relations for the Penrose polynomial which can not be realized within the class of plane graphs. In particular, by exploiting connections with the transition polynomial and the ribbon group action, we find a deletion-contraction-type relation for the Penrose polynomial. We relate the Penrose polynomial of an orientable checkerboard colourable graph to the circuit partition polynomial of its medial graph and use this to find new combinatorial interpretations of the Penrose polynomial. We also show that the Penrose polynomial of a plane graph G can be expressed as a sum of chromatic polynomials of twisted duals of G. This allows us to obtain a new reformulation of the Four Colour Theorem

    The impact of Self-Generated Images in online pornography

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    This investigation seeks to evaluate the impact on individuals, and society, of Self-Generated Images (SGI’s) in online pornography. It presents an inquiry into the extent, and modes, of SGI use among a large sample of adult internet users. This form the initial platform for a theoretical analysis of the rapidly emerging topic, alongside an empirical investigation into how SGI’s are used, and criminally abused. A mixed research method strategy was consequently adopted, employing a quantitative anonymous online survey (Stage 1), qualitative face-to-face interviews with serving Metropolitan Police Service officers in the SOECA unit (Stage 2), and qualitative Skype interviews with active SGI users (Stage 3). The thesis is divided into three main sections. Firstly, in chapters one-to-four, the context for this study into SGI’s is explained, including the specific UK statute laws regarding licit and illicit pornographic images. Commonly used pornographic terminologies are defined. Furthermore, existent research on the topic of SGI’s/online pornography is scrutinized, and several theoretical issues are given a discourse in relation to SGI’s. An analysis of the free speech/online pornography debate is included, together with an examination of the criminal abuse of SGI’s. The second part, chapter five, provides a rationale for the adoption of a mixed research methods strategy in pursuing the aims of this study. Many methodological issues regarding the three stages of the primary fieldwork are addressed; these include: ontology, epistemology, research paradigms and axiology, ethical underpinnings, practical considerations, and the strengths and limitations of methods chosen. In the third section, chapters six-to-eight, the study’s key findings include a taxonomy of the six main types of SGI. Passive SGI viewing is very pervasive, particularly among the key demographic groups of younger adults, Lesbian Gay Bisexual Transgender (LGBT) and males, and may be becoming the norm. Free PornTube websites are predominately used; but also, increasingly, social network sites (SNS’s) and messaging/image sharing apps. Most adults use SGI’s safely for sexual stimulation; however, some use them for educational and humorous purposes. For a minority of active creators of SGI’s, disastrous personal consequences can result because of subsequent criminal abuse, including cyber-bullying/trolling, sextortion, etc. Gay and bisexual men have highly accelerated rates of SGI use on hooking-up sites, often leading to hazardous risk taking. Children face grave dangers from making and sharing sexualised SGI’s as online child sexual abuse (CSA), grooming and sextortion, etc. may transpire. In the UK’s schools, Personal, Social and Health Education (PSHE), and Sex and Relationships Education (SRE), are in a parlous state regarding the issues and dangers of SGI’s. Finally, this inquiry provides some original insights into the areas of applying and generating theories, using mixed research methods, and the empirical findings uncovered

    Clyde superficial deposits and bedrock models released to the ASK Network 2013 : a guide for users

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    This report draft provides an overview of the Clyde superficial deposits models to be released in 2013 and detail on the Central Glasgow Superficial Deposits Model currently released to the ASK network. The geological models are an interpretation of digital datasets held by the British Geological Survey. A summary of the construction and limitations of the models and a brief description of the modelled units is given. The report will be updated and revised as more models become available for release to the ASK network. More details on the models can be found in the previous reports Merritt et al. (2009), Monaghan (2012a) and Monaghan et al. (2012)

    Controlling Artificial Viscosity in SPH simulations of accretion disks

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    We test the operation of two methods for selective application of Artificial Viscosity (AV) in SPH simulations of Keplerian Accretion Disks, using a ring spreading test to quantify effective viscosity, and a correlation coefficient technique to measure the formation of unwanted prograde alignments of particles. Neither the Balsara Switch nor Time Dependent Viscosity work effectively, as they leave AV active in areas of smooth shearing flow, and do not eliminate the accumulation of alignments of particles in the prograde direction. The effect of both switches is periodic, the periodicity dependent on radius and unaffected by the density of particles. We demonstrate that a very simple algorithm activates AV only when truly convergent flow is detected and reduces the unwanted formation of prograde alignments. The new switch works by testing whether all the neighbours of a particle are in Keplerian orbit around the same point, rather than calculating the divergence of the velocity field, which is very strongly affected by Poisson noise in the positions of the SPH particles.Comment: 8 pages, 5 figure

    Star Formation Around Super-Massive Black Holes

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    The presence of young massive stars orbiting on eccentric rings within a few tenths of a parsec of the supermassive black hole in the Galactic centre is challenging for theories of star formation. The high tidal shear from the black hole should tear apart the molecular clouds that form stars elsewhere in the Galaxy, while transporting the stars to the Galactic centre also appears unlikely during their stellar lifetimes. We present numerical simulations of the infall of a giant molecular cloud that interacts with the black hole. The transfer of energy during closest approach allows part of the cloud to become bound to the black hole, forming an eccentric disc that quickly fragments to form stars. Compressional heating due to the black hole raises the temperature of the gas to 100-1000K, ensuring that the fragmentation produces relatively high stellar masses. These stars retain the eccentricity of the disc and, for a sufficiently massive initial cloud, produce an extremely top-heavy distribution of stellar masses. This potentially repetitive process can therefore explain the presence of multiple eccentric rings of young stars in the presence of a supermassive black hole.Comment: 20 pages includingh 7 figures. "This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science, 321, (22 August 2008), doi:10.1126/science.1160653". Reprints and animations can be found at http://star-www.st-and.ac.uk/~iab1

    Comparison of C═C bond hydrogenation in C-4 unsaturated nitriles over Pt/alumina

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    The hydrogenation of allyl cyanide (but-1-ene-4-nitrile, AC), trans- and cis-crotononitrile (E- and Z-but-2-ene nitrile, TCN and CCN), and methacrylonitrile (2-cyano-1-propene, MCN) were studied, both singly and competitively, over a Pt/alumina catalyst in the liquid phase. Each unsaturated nitrile only underwent C═C bond hydrogenation: no evidence was found for the formation of the saturated or unsaturated amine. The nonconjugated allyl cyanide was found to be the most reactive unsaturated nitrile. Activation energies for the hydrogenation of the C═C bond in AC and MCN were determined giving values of 64 ± 7 kJ mol–1 for AC and 37 ± 4 kJ mol–1 for MCN. The reaction was zero order for both nitriles. Competitive hydrogenations revealed that not only does allyl cyanide react preferentially over the other isomers but also it inhibits the hydrogenation of the other isomers. When all four nitriles were simultaneously hydrogenated, inhibition effects were easily seen suggesting that in terms of strength of bonding to the surface an order of AC > CCN > TCN ∼ MN can be generated