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Search Results: 1 - 10 of 297665 matches for " J. Buckley "
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Wetting Alteration of Solid Surfaces by Crude Oils and Their Asphaltenes Modification de la mouillabilité des surfaces solides par les pétroles bruts et leurs asphaltènes
Buckley J. S.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1998026
Abstract: Crude oils contain a variety of components - including asphaltenes - that can adsorb onto mineral surfaces and alter wetting. What distinguishes the asphaltenes from other constituents of an oil is their tendency to aggregate and even separate from the oil in response to changes in oil solvency. Because they change in size, asphaltenes can be viewed as both macromolecules and colloids. Their influence on wettability can change with this shift from molecular to colloidal regimes. As macromolecules, asphaltenes and other crude oil components with polar functionality can adsorb on mineral surfaces. Many different crude oils have been shown to have similar effects on wetting of dry silicate surfaces. When water is present, however, the results of exposing surfaces to different oils can be quite complex, depending on the distribution of water, the compositions of oil and brine, and mineralogy of rock surfaces. Acid and base numbers and the relationship between them provide a measure of the potential for a particular oil to alter wetting through ionic interactions. As colloids, asphaltenes can alter wetting by an additional mechanism. Near the onset of precipitation, wetting alteration occurs by surface precipitation because of the interfacial aggregation of the colloidal asphaltenes, which can precede flocculation in bulk. The influence of asphaltenes on wetting is thus strongly dependent on the environment in which they are found. Mixture refractive index is a useful measure for quantifying the stability of asphaltenes in a crude oil and thus in differentiating between macromolecular and colloidal contributions of asphaltenes to wetting alteration. Les pétroles bruts contiennent de nombreux constituants - dont les asphaltènes - qui peuvent être adsorbés sur les surfaces minérales et modifier leurs caractéristiques de mouillage. Ce qui distingue les asphaltènes des autres constituants de l'huile est leur tendance à s'agréger et même à se séparer du pétrole en réaction à des modifications du pouvoir solvant du pétrole. Du fait qu'ils changent de taille, les asphaltènes peuvent être considérés soit comme des macromolécules, soit comme des collo des. Leur influence sur la mouillabilité peut varier selon que le régime est plut t moléculaire ou plut t collo dal. En tant que macromolécules, les asphaltènes et les autres constituants du pétrole possédant des fonctions polaires peuvent s'adsorber sur les surfaces minérales. Il est établi que de nombreux pétroles différents modifient la mouillabilité de surfaces silicatées sèches de fa on similaire. En présence d'eau,
A Behavioral Economic Study of Tax Rate Selection by the Median Voter: Can the Tax Rate Be Influenced by the Name of the Publicly Provided Private Good?  [PDF]
Neil J. Buckley, David Cameron, Katherine Cuff, Jeremiah Hurley, Stuart Mestelman, Stephanie Thomas
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.83034
Abstract: This paper presents the results of a behavioral economics study to test if the tax rates submitted to finance the public provision of a private good are influenced by changing the name of the private good. A revealed-preference laboratory decision-making experiment is used to test if participants choose significantly different tax rates to support provision of a private good named as a health care investment compared to an identical good named as a neutral monetary investment. Although some previous studies focusing on both framing and context effects find differences associated with health versus non-health environments, these studies have not involved voting over public provision of a private good. In our experimental environment, participants with different income endowments provide their preferred proportional tax rates for financing public provision of a private good in either a neutral or a health context. The implemented tax rate is the median preferred tax rate, and once the budget is determined, each participant receives the same quantity of the publicly provided private good. In each context, the payoff functions are the same. The only difference between the contexts is the name attached to the publicly provided private good, regardless of the name attached to the publicly provided private good, consuming it imposes no externalities. This controls for the positive externality characteristics of many health care goods, but not for preferences evoked by the merit good character of health care which factor into decisions about the public provision of health care. We find that the theoretical predictions of the median voter model are generally supported by the data. However, the conjecture that
Proinflammatory Mediators of Toxic Shock and Their Correlation to Lethality
Teresa Krakauer,Marilyn J. Buckley,Diana Fisher
Mediators of Inflammation , 2010, DOI: 10.1155/2010/517594
Abstract: Bacterial exotoxins and endotoxins both stimulate proinflammatory mediators but the contribution of each individual toxin in the release of mediators causing lethal shock is incompletely understood. This study examines the cytokine response and lethality of mice exposed to varying doses of staphylococcal enterotoxin B (SEB) or lipopolysaccharide (LPS) and their combinations. In vivo, SEB alone induced moderate levels of IL-2 and MCP-1 and all mice survived even with a high dose of SEB (100 g/mouse). LPS (80 g/mouse) caused 48% lethality and induced high levels of IL-6 and MCP-1. SEB induced low levels of TNF , IL-1, IFN , MIP-2, and LPS synergized with SEB in the expression of these cytokines and that of IL-6 and MCP-1. Importantly, the synergistic action of SEB and LPS resulted in lethal shock and hypothermia. ANOVA of cytokine levels by survival status of SEB-plus-LPS groups revealed significantly higher levels of TNF , IL-6, MIP-2, and MCP-1 in nonsurvivors measured at 8 hours. Significantly higher levels of IFN and IL-2 were observed at 21 hours in nonsurvivors of toxic shock compared to those in survivors. Overall, synergistic action of SEB and LPS resulted in higher and prolonged levels of these key cytokines leading to toxic shock. 1. Introduction Bacterial exotoxins and endotoxins are among the most common etiological agents that cause septic shock [1–3]. Although similar cytokines are released from host cells stimulated with these structurally distinct bacterial products, the stimulants act through distinct cell surface receptors on host cells. Staphylococcal enterotoxin B (SEB) and structurally related exotoxins are bacterial superantigens that potently activate antigen-presenting cells by binding directly to major histocompatibility complex (MHC) class II molecules [1, 4, 5]. These exotoxins also interact with specific Vβ regions of the T cell antigen receptors resulting in polyclonal T cell activation [6]. Interactions of superantigens with antigen-presenting cells and T cells lead to massive proinflammatory cytokine and chemokine release, causing clinical symptoms that include fever, hypotension, and shock [1, 2, 4, 7, 8]. In contrast, lipopolysaccharide (LPS) from gram-negative bacteria binds to a different receptor on monocytes/macrophages. An LPS-binding protein in serum first binds to LPS and facilitates its binding to cell surface protein CD14 on monocytes/macrophages and other cells [9, 10]. The subsequent interaction of LPS/CD14 complex with Toll-like receptor 4 on these cells initiates recruitment of intracellular adaptors and
Reliability in One-Repetition Maximum Performance in People with Parkinson's Disease
Thomas A. Buckley,Christopher J. Hass
Parkinson's Disease , 2012, DOI: 10.1155/2012/928736
Abstract: Strength training is an effective modality to improve muscular strength and functional performance in people with Parkinson's disease (PWP). One-repetition maximum (1-RM) is the gold standard assessment of strength; however, PWP suffer from day-to-day variations in symptom severity and performance characteristics, potentially adversely affecting the reliability of 1-RM performance. Herein, we assessed the reliability of 1-RM in PWP. Forty-six participants completed two sessions of 1-RM testing of knee extension, knee flexion, chest press, and biceps curl at least 72 hours apart. Significantly differences between testing sessions were identified for knee extension ( < 0.001), knee flexion ( = 0.042), and biceps curl ( = 0.001); however, high reliability (ICC > 0.90) was also identified between sessions. Interestingly, almost third of subjects failed to perform better on the second testing session. These findings suggest that 1-RM testing can be safely performed in PWP and that disease-related daily variability may influence 1-RM performance. 1. Introduction Parkinson’s disease (PD), a progressive neurological disease which is believed to affect over 1.5 million Americans, results from the degeneration of the dopaminergic neurons in the midbrain and the resulting reduced dopamine availability to the basal ganglia [1, 2]. The cardinal features of PD include rigidity, tremor, bradykinesia, and impaired postural control, and these symptoms are often unpredictable and their severity can fluctuate daily, often termed “day-to-day variability” [3–5]. Further, muscular weakness, identified by Dr. Parkinson as an early symptom of the disease, is also frequently reported by people with Parkinson’s (PWP) [6, 7]. However, inconsistent findings in the literature have obscured the elucidation of the underlying mechanism of the apparent weakness, thus, raising the debate if muscular weakness is intrinsic to the disease or a secondary consequence [8, 9]. Muscular weakness, when present in PWP, presents bilaterally and tends to increase as the velocity of movement increases [9]. While the specific contributory neurophysiological mechanisms remain uncertain, bradykinesia, the inability to energize the appropriate muscles to generate forces at a sufficient rate, is thought to be a major contributing factor [8, 10]. Bradykinesia likely results from basal ganglia pathophysiology leading to impairments in both motor programming and execution [11]. Muscular weakness and bradykinesia impair power production, particularly at lighter loads [8]. These reductions in muscular
Optimizing SIFT for Matching of Short Wave Infrared and Visible Wavelength Images
Aleksandra A. Sima,Simon J. Buckley
Remote Sensing , 2013, DOI: 10.3390/rs5052037
Abstract: The scale invariant feature transform (SIFT) is a widely used interest operator for supporting tasks such as 3D matching, 3D scene reconstruction, panorama stitching, image registration and motion tracking. Although SIFT is reported to be robust to disparate radiometric and geometric conditions in visible light imagery, using the default input parameters does not yield satisfactory results when matching imagery acquired at non-overlapping wavelengths. In this paper, optimization of the SIFT parameters for matching multi-wavelength image sets is documented. In order to integrate hyperspectral panoramic images with reference imagery and 3D data, corresponding points were required between visible light and short wave infrared images, each acquired from a slightly different position and with different resolutions and geometric projections. The default SIFT parameters resulted in too few points being found, requiring the influence of five key parameters on the number of matched points to be explored using statistical techniques. Results are discussed for two geological datasets. Using the SIFT operator with optimized parameters and an additional outlier elimination method, allowed between four and 22 times more homologous points to be found with improved image point distributions, than using the default parameter values recommended in the literature.
Tourism Revenue as a Conservation Tool for Threatened Birds in Protected Areas
Rochelle Steven, J. Guy Castley, Ralf Buckley
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062598
Abstract: Many bird populations worldwide are at risk of extinction, and rely heavily on protected area networks for their continued conservation. Tourism to these areas contributes to conservation by generating revenue for management. Here we quantify the contribution of tourism revenue for bird species in the IUCN Red List, using a simple accounting method. Relevant data are available for 90 (16%) of the 562 critically endangered and endangered species. Contributions of tourism to bird conservation are highest, 10–64%, in South America, Africa, and their neighbouring islands. Critically endangered bird species rely on tourism more heavily than endangered species (p<0.02). Many protected areas could also enhance their management budgets by promoting birdwatching tourism specifically.
Fast supersymmetry phenomenology at the Large Hadron Collider using machine learning techniques
A. Buckley,A. Shilton,M. J. White
Physics , 2011, DOI: 10.1016/j.cpc.2011.12.026
Abstract: A pressing problem for supersymmetry (SUSY) phenomenologists is how to incorporate Large Hadron Collider search results into parameter fits designed to measure or constrain the SUSY parameters. Owing to the computational expense of fully simulating lots of points in a generic SUSY space to aid the calculation of the likelihoods, the limits published by experimental collaborations are frequently interpreted in slices of reduced parameter spaces. For example, both ATLAS and CMS have presented results in the Constrained Minimal Supersymmetric Model (CMSSM) by fixing two of four parameters, and generating a coarse grid in the remaining two. We demonstrate that by generating a grid in the full space of the CMSSM, one can interpolate between the output of an LHC detector simulation using machine learning techniques, thus obtaining a superfast likelihood calculator for LHC-based SUSY parameter fits. We further investigate how much training data is required to obtain usable results, finding that approximately 2000 points are required in the CMSSM to get likelihood predictions to an accuracy of a few per cent. The techniques presented here provide a general approach for adding LHC event rate data to SUSY fitting algorithms, and can easily be used to explore other candidate physics models.
Localised Oscillatory States in Magnetoconvection
Matthew C. Buckley,Paul J. Bushby
Physics , 2013, DOI: 10.1103/PhysRevE.87.023019
Abstract: Localised states are found in many pattern forming systems. The aim of this paper is to investigate the occurrence of oscillatory localised states in two-dimensional Boussinesq magnetoconvection. Initially considering an idealised model, in which the vertical structure of the system has been simplified by a projection onto a small number of Fourier modes, we find that these states are restricted to the low $\zeta$ regime (where $\zeta$ represents the ratio of the magnetic to thermal diffusivities). These states always exhibit bistability with another non-trivial solution branch, in other words they show no evidence of subcritical behaviour. This is due to the weak flux expulsion that is exhibited by these time-dependent solutions. Using the results of this parameter survey, we locate corresponding states in a fully-resolved two-dimensional system, although the mode of oscillation is more complex in this case. This is the first time that a localised oscillatory state, of this kind, has been found in a fully-resolved magnetoconvection simulation.
Observability of Gamma Rays from Dark Matter Neutralino Annihilations in the Milky Way Halo
L. Bergstrom,P. Ullio,J. Buckley
Physics , 1997, DOI: 10.1016/S0927-6505(98)00015-2
Abstract: Recent advances in N-body simulations of cold dark matter halos point to a substantial density enhancement near the center. This means that, e.g., the $\gamma$ ray signals from neutralino dark matter annihilations would be significantly enhanced compared to old estimates based on an isothermal sphere model with large core radius. Another important development concerns new detectors, both space- and ground-based, which will cover the window between 50 and 300 GeV where presently no cosmic $\gamma$-ray data are available. Thirdly, new calculations of the $\gamma$-ray line signal (a sharp spike of $10^{-3}$ relative width) from neutralino annihilations have revealed a hitherto neglected contribution which, for heavy higgsino-like neutralinos, gives an annihilation rate an order of magnitude larger than previously predicted. We make a detailed phenomenological study of the possible detection rates given these three pieces of new information. We show that the proposed upgrade of the Whipple telescope will make it sensitive to a region of parameter space, with substantial improvements possible with the planned new generation of Air Cherenkov Telescope Arrays. We also comment on the potential of the GLAST satellite detector. An evaluation of the continuum $\gamma$-rays produced in neutralino annihilations into the main modes is also done. It is shown that a combination of high-rate models and very peaked halo models are already severely constrained by existing data.
The conjugacy problem in hyperbolic groups for finite lists of group elements
David J. Buckley,Derek F. Holt
Mathematics , 2011,
Abstract: Let G be a word-hyperbolic group with given finite generating set, for which various standard structures and constants have been pre-computed. A (non-practical) algorithm is described that, given as input two lists A and B, each composed of m words in the generators and their inverses, determines whether or not the lists are conjugate in G, and returns a conjugating element should one exist. The algorithm runs in time O(m mu)$, where mu is an upper bound on the lengths of elements in the two lists. Similarly, an algorithm is outlined that computes generators of the centraliser of A, with the same bound on running time.
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