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Search Results: 1 - 10 of 8408 matches for " Scott Farrow "
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Cybersecurity: Integrating Information into the Microeconomics of the Consumer and the Firm  [PDF]
Scott Farrow
Journal of Information Security (JIS) , 2016, DOI: 10.4236/jis.2016.75023
Abstract: The connectivity of information has changed many things but not the way economists model consumers, firms and government. Information is here newly modeled as a fundamental element of microeconomic choices and utility, cost and tax functions. The results are more clearly defined metrics for losses due to cyber breaches or productivity gains from cyber investments. The integration of information into standard microeconomics also allows use of econometric and other tools to analyze the empirics of the consumer and the firm. In particular, the results identify ways in which losses in the Gordon and Loeb [1] model can be specified in more detail.
Cybersecurity Investment Guidance: Extensions of the Gordon and Loeb Model  [PDF]
Scott Farrow, Jules Szanton
Journal of Information Security (JIS) , 2016, DOI: 10.4236/jis.2016.72002
Abstract: Extensions of the Gordon-Loeb [1] and the Gordon-Loeb-Lucyshyn-Zhou [2] models are presented based on mathematical equivalency with a generalized homeland security model. The extensions include limitations on changes in the probability of attack, simultaneous effects on probability and loss, diversion of attack, and shared non-information defenses. Legal cases are then investigated to assess approximate magnitudes of external effects and the extent they are internalized by the legal system.
Concurrent profiling of indole-3-acetic acid, abscisic acid, and cytokinins and structurally related purines by high-performance-liquid-chromatography tandem electrospray mass spectrometry
Farrow Scott C,Emery RJ Neil
Plant Methods , 2012, DOI: 10.1186/1746-4811-8-42
Abstract: Background Cytokinins (CKs) are a group of plant growth regulators that are involved in several plant developmental processes. Despite the breadth of knowledge surrounding CKs and their diverse functions, much remains to be discovered about the full potential of CKs, including their relationship with the purine salvage pathway, and other phytohormones. The most widely used approach to query unknown facets of CK biology utilized functional genomics coupled with CK metabolite assays and screening of CK associated phenotypes. There are numerous different types of assays for determining CK quantity, however, none of these methods screen for the compendium of metabolites that are necessary for elucidating all roles, including purine salvage pathway enzymes in CK metabolism, and CK cross-talk with other phytohormones. Furthermore, all published analytical methods have drawbacks ranging from the required use of radiolabelled compounds, or hazardous derivatization reagents, poor sensitivity, lack of resolution between CK isomers and lengthy run times. Results In this paper, a method is described for the concurrent extraction, purification and analysis of several CKs (freebases, ribosides, glucosides, nucleotides), purines (adenosine monophosphate, inosine, adenosine, and adenine), indole-3-acetic acid, and abscisic acid from hundred-milligram (mg) quantities of Arabidopsis thaliana leaf tissue. This method utilizes conventional Bieleski solvents extraction, solid phase purification, and is unique because of its diverse range of detectable analytes, and implementation of a conventional HPLC system with a fused core column that enables good sensitivity without the requirement of a UHPLC system. Using this method we were able to resolve CKs about twice as fast as our previous method. Similarly, analysis of adenosine, indole-3-acetic acid, and abscisic acid, was comparatively rapid. A further enhancement of the method was the utilization of a QTRAP 5500 mass analyzer, which improved upon several aspects of our previous analytical method carried out on a Quattro mass analyzer. Notable improvements included much superior sensitivity, and number of analytes detectable within a single run. Limits of detection ranged from 2 pM for (9G)Z to almost 750 pM for indole-3-acetic acid. Conclusions This method is well suited for functional genomics platforms tailored to understanding CK metabolism, CK interrelationships with purine recycling and associated hormonal cross-talk.
Vibration-enhanced energy transfer in living molecules
Vlatko Vedral,Tristan Farrow
Physics , 2010,
Abstract: The conversion of an absorbed photon from the exciton energy into the reaction centre in the photosynthetic complex has a near unit efficiency. It is becoming clear that any classical model, where the exciton hopping is modeled by a classical stochastic diffusion equation, cannot explain such a high degree of efficiency. A number of different quantum models have been proposed, ranging from a purely unitary model with long range exciton interactions to a noise-aided stochastic resonance models. Here we propose a very simple spin-boson model that captures all the features of the efficient part of energy transfer. We show how this model describes a scenario where a donor-acceptor system can be brought into resonance by a narrow band of vibrational modes so that the excitation transfer between the two can be made arbitrarily high. This is then extended to a seven exciton system such as the widely-studied FMO photosynthetic complex to show that a high efficiency is also achievable therein. Our model encodes a number of readily testable predictions and we discuss its generalisations to include the localisation in the reaction centre.
Scale-estimation of quantum coherent energy transport in multiple-minima systems
Tristan Farrow,Vlatko Vedral
Physics , 2014,
Abstract: A generic and intuitive model for coherent energy transport in multiple minima systems coupled to a quantum mechanical bath is shown. Using a simple spin-boson system, we illustrate how a generic donor-acceptor system can be brought into resonance using a narrow band of vibrational modes, such that the transfer efficiency of an electron-hole pair (exciton) is made arbitrarily high. Coherent transport phenomena in nature are of renewed interest since the discovery that a photon captured by the light-harvesting complex (LHC) in photosynthetic organisms can be conveyed to a chemical reaction centre with near-perfect efficiency. Classical explanations of the transfer use stochastic diffusion to model the hopping motion of a photo-excited exciton. This accounts inadequately for the speed and efficiency of the energy transfer measured in a series of recent landmark experiments. Taking a quantum mechanical perspective can help capture the salient features of the efficient part of that transfer. To show the versatility of the model, we extend it to a multiple minima system comprising seven-sites, reminiscent of the widely studied Fenna-Matthews-Olson (FMO) light-harvesting complex. We show that an idealised transport model for multiple minima coupled to a narrow-band phonon can transport energy with arbitrarily high efficiency.
Bayes linear kinematics in a dynamic Bayesian survival model
Kevin J. Wilson,Malcolm Farrow
Statistics , 2014,
Abstract: Bayes linear kinematics and Bayes linear Bayes graphical models provide an extension of Bayes linear methods so that full conditional updates may be combined with Bayes linear belief adjustment. In this paper we investigate the application of this approach to a more complicated problem: namely survival analysis with time-dependent covariate effects. We use a piecewise-constant hazard function with a prior in which covariate effects are correlated over time. The need for computationally intensive methods is avoided and the relatively simple structure facilitates prior specification and posterior interpretation. Our approach eliminates the problem of non-commutativity which was observed in earlier work by Gamerman. We apply the technique to data on survival times for leukemia patients.
Adapting online learning resources for all: planning for professionalism in accessibility
Patrick McAndrew,Robert Farrow,Martyn Cooper
Research in Learning Technology , 2012, DOI: 10.3402/rlt.v20i0.18699
Abstract: Online resources for education offer opportunities for those with disabilities but also raise challenges on how to best adjust resources to accommodate accessibility. Automated reconfiguration could in principle remove the need for expensive and time-consuming discussions about adaptation. On the other hand, human-based systems provide much needed direct support and can help understand options and individual circumstances. A study was carried out within an EU-funded accessibility project at The Open University (OU) in parallel with studies at three other European universities. The study combined focus groups, user-testing, management consultation and student survey data to help understand ways forward for accessibility. The results reinforce a holistic view of accessibility, based on three factors: positioning the university as a positive provider to disabled students; developing processes, systems and services to give personal help; and planning online materials which include alternatives. The development of a model that helps organisations incorporate professionalism in accessibility is described, though challenges remain. For example, a recurrent difficulty in providing adequate self-description of accessibility needs implies that a completely automated solution may not be attainable. A more beneficial focus, therefore, may be to develop systems that support the information flow required by the human “in the loop.”
“Otherwise it would be nothing but cruises”: exploring the subjective benefits of working beyond 65
Frances Reynolds,Alexandra Farrow,Alison Blank
International Journal of Ageing and Later Life , 2012,
Abstract: The age at which statutory and private pensions are being paid is increasing in many countries and hence more people will need to work into their late 60s and beyond. At present, relatively little is known about the meanings of work for people who actively choose to work into their later life. This qualitative study examined the subjective benefits of continuing in a paid job or self-employment beyond the age of 65 in the United Kingdom. Thirty-one participants were interviewed, aged 6591 years (median age 71), with 11 females and 20 males. Fourteen were working full-time and seventeen part-time. Interview transcripts were subject to thematic analysis. Although financial reward was acknowledged (more so by the female participants and the males who had young second families), there was more elaboration of the role of work in maintaining health and enabling continuing personal development. Work was framed as increasing personal control over later life, lifestyle choices and active participation in wider society, an antithesis to ‘‘cruising’’.
Relationship between the atomic pair distribution function and small angle scattering: implications for modeling of nanoparticles
Christopher L. Farrow,Simon J. L. Billinge
Physics , 2008, DOI: 10.1107/S0108767309009714
Abstract: Here we show explicitly the relationship between the functions used in the atomic pair distribution function (PDF) method and those commonly used in small angle scattering (SAS) analyses. The origin of the sloping baseline, $-4\pi r\rho_0$, in PDFs of bulk materials is identified as originating from the SAS intensity that is neglected in PDF measurements. The non-linear baseline in nanoparticles has the same origin, and contains information about the shape and size of the nanoparticles.
Atomistic Molecular Dynamics Simulations of Shock Compressed Quartz
Matthew R. Farrow,Matthew I. J. Probert
Physics , 2011, DOI: 10.1063/1.3615526
Abstract: Atomistic non-equilibrium molecular dynamics (NEMD) simulations of shock wave compression of quartz have been performed using the so-called BKS semi-empirical potential of van Beest, Kramer and van Santen to construct the Hugoniot of quartz. Our scheme mimics the real world experimental set up by using a flyer-plate impactor to initiate the shock wave and is the first shock wave simulation that uses a geom- etry optimised system of a polar slab in a 3-dimensional system employing periodic boundary conditions. Our scheme also includes the relaxation of the surface dipole in the polar quartz slab which is an essential pre-requisite to a stable simulation. The original BKS potential is unsuited to shock wave calculations and so we propose a simple modification. With this modification, we find that our calculated Hugoniot is in good agreement with experimental shock wave data up to 25 GPa, but significantly diverges beyond this point. We conclude that our modified BKS potential is suitable for quartz under representative pressure conditions of the Earth core, but unsuitable for high-pressure shock wave simulations. We also find that the BKS potential incorrectly prefers the {\beta}-quartz phase over the {\alpha}-quartz phase at zero-temperature, and that there is a {\beta} \rightarrow {\alpha} phase-transition at 6 GPa.
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