140 research outputs found

    A longitudinal and comparative analysis of competitive balance in five European football leagues

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    Purpose This paper aims to provide empirical evidence on competitive balance in the 'big five' European football leagues; namely the English Premier League, French Ligue 1, German Bundesliga, Italian Serie A and Spanish La Liga. Design/Methodology/Approach Our paper utilises recognised measures of competitive balance to measure levels of concentration (within-season competitive balance) and dominance (between-season competitive balance) in the selected leagues over 22 seasons between 1995/96 and 2016/17. Findings Ligue 1 emerged as the most balanced league in terms of both concentration and dominance measures. Our analysis also points to a statistically significant decline in competitive balance in all leagues apart from Serie A (Italy). Originality/Value The findings of this study are concerning for league organisers. Competition intensity is a key component of a sport league and a league that is dominated by one or a select few clubs is less attractive within the marketplace. This paper presents challenges at league governance level for the five leagues examined

    Adhesive bonding of stainless steel :Sstrength and durability.

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    Adhesive bonding as an alternative method of joining materials together has many advantages over the more conventional joining methods such as fusion and spot welding, bolting and riveting. For example, adhesives can be used to bond dissimilar materials, adhesive joints have a high stiffness to weight ratio and the stress distribution within the joint is much improved. Stainless steels are commonly used in applications that would clearly benefit from adhesive bonding; architectural cladding, because of the large bond areas involved, and in the railway industry, due to improved acoustic insulation and greater fatigue resistance. The work presented in this thesis is concerned with adhesive bonding of stainless steels intended for structural applications. As a starting point to the investigation, a review of the literature was conducted, covering the intrinsic mechanisms of adhesion, the significance of the chemical and physical nature of the adherend surface, the types of structural adhesives, the methods of testing adhesive joints and surface characterisation techniques. The first experimental stage, involved a screening programme to evaluate a number of candidate adhesive systems and adherend surface pre-treatments. Standard single overlap shear and floating roller peel tests conducted in ambient conditions were employed in the discrimination and the degree of compatibility between adhesive and adherend, as measured by the proportion of cohesive failure on the post-fracture face, was also considered. In the second stage of the experimental work, lap shear tests were used to evaluate the affects of surface contamination on joint strength. In addition, lap shear and peel tests were considered to assess the significance of the adhesive bondline and primer thickness. In order to assess the environmental durability of adhesive joints, lap shear and peel tests were conducted after ageing in ambient and high humidity environments. To compliment the data, Boeing wedge crack extension tests were also carried out on adhesive bonded joints incorporating adherends with different surface conditions, to investigate the contribution to joint strength in ambient and adverse environments afforded by surface pre-treatment. The next stage of the experimental work was designed to evaluate the significance of the adherend type and its thickness on initial lap shear strength. Several different commercial grades and gauges of stainless steel were used in the tests, which were conducted at room temperature. The final stage of the experimental work was concentrated on the room temperature creep and dynamic fatigue performance of adhesive joints. Throughout the course of study a number of different surface analytical techniques were employed to physically and chemically characterise the surfaces of pre-bonded adherends and to identify the locus of failure on post-fracture faces. The single overlap shear and floating roller peel tests were able to differentiate between the candidate adhesives; epoxy systems, particularly the toughened variants, were considered the most suitable structural adhesives for bonding stainless steels in load bearing applications. However, these tests and subsequent tests using lap shear and peel, failed to discriminate conclusively between the different surface pre-treatments (except untreated or crudely prepared surfaces) and ageing environments. The Boeing wedge crack extension tests were found to be sensitive to the condition of the adherend surface and the environment in which the joint is located; roughening the surface of the adherend either chemically or physically was found to enhance joint durability in ambient, high humidity and sub-zero environments. The use of surface primers and coupling agents may protect the un-bonded surface and benefit joint durability, but excessively thick primer layers may reduce joint strength. The stiffness of the adherend material was found to significantly influence lap shear strength. Stiffer adherends, either thicker or inherently stronger, give higher joint strengths because they resist joint rotation and the peel stresses at the extremes of the overlap are minimised. Lap joints with low stiffness adherends will fail by peel-dominated, adherend-controlled failure and lap joints with high stiffness adherends will fail by shear-dominated, adhesive-controlled failure. Two elastic models were proposed for determining the elastic rotation and the line peel force as a function of the shear stress. The room temperature creep results showed an endurance limit of ~40% mean static failure load (design load = 250 N.mm'1). The dynamic fatigue results were favourable compared to those of spot welded and weldbonded joints and an endurance limit of ~ 40% mean static failure load (design load = 250 N.mm'1) was observed. Finally, leaving the hard fillets of cured adhesive squeeze-out, intact at the extremes of the overlap, will reinforce the joint and minimise the rotation-induced peel stresses that will lead to premature failure when the adherend plastically deforms under static or dynamic loading

    Bucking the trend: the diversity of Anthropocene ‘winners’ among British moths

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    An appreciation of how some species are becoming more common despite unprecedented anthropogenic pressures could offer key insights for mitigating the global biodiversity crisis.  Research to date has largely focused on declining species, while species that are becoming more common have received relatively little attention. Macro-moths in Great Britain are well-studied and species-rich, making them an ideal group for addressing this knowledge gap. Here, we examine changes in 51 successful species between 1968 and 2016 using 4.5 million occurrence records and a systematic monitoring dataset. We employ 3D graphical analysis to visualise long-term multidimensional trends in prevalence (abundance and range) and use vector autoregression models to test whether past values of local abundance are useful for predicting changes in the extent of occurrence. The responses of Anthropocene winners are heterogeneous, suggesting multiple drivers are responsible. Changes in range and local abundance frequently occur intermittently through time, demonstrating the value of long-term, continuous monitoring. There is significant diversity among the winners themselves, which include widespread generalists, habitat specialists, and recent colonists. We offer brief discussion of possible causal factors and the wider ecosystem implications of these trends

    Single Atom Dynamics in Chemical Reactions

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    Many heterogeneous chemical reactions involve gases catalyzed over solid surfaces at elevated temperatures and play a critical role in the production of energy, healthcare, pollution control, industrial products, and food. These catalytic reactions take place at the atomic level, with active structures forming under reaction conditions. A fundamental understanding of catalysis at the single atom resolution is therefore a major advance in a rational framework upon which future catalytic processes can be built. Visualization and analysis of gas-catalyst chemical reactions at the atomic level under controlled reaction conditions are key to understanding the catalyst structural evolution and atomic scale reaction mechanisms crucial to the performance and the development of improved catalysts and chemical processes. Increasingly, dynamic single atoms and atom clusters are believed to lead to enhanced catalyst performance, but despite considerable efforts, reaction mechanisms at the single atom level under reaction conditions of gas and temperature are not well understood. The development of the atomic lattice resolution environmental transmission electron microscope (ETEM) by the authors is widely used to visualize gas–solid catalyst reactions at this atomic level. It has recently been advanced to the environmental scanning TEM (ESTEM) with single atom resolution and full analytical capabilities. The ESTEM employs high-angle annular dark-field imaging where intensity is approximately proportional to the square of the atomic number (Z). In this Account, we highlight the ESTEM development also introduced by the authors for real time in situ studies to reliably discern metal atoms on lighter supports in gas and high temperature environments, evolving oxide/metal interfaces, and atomic level reaction mechanisms in heterogeneous catalysts more generally and informatively, with utilizing the wider body of literature. The highlights include platinum/carbon systems of interest in fuel cells to meet energy demands and reduce environmental pollution, in reduction/oxidation (redox) mechanisms of copper and nickel nanoparticles extensively employed in catalysis, electronics, and sensors, and in the activation of supported cobalt catalysts in Fischer–Tropsch (FT) synthesis to produce fuels. By following the dynamic reduction process at operating temperature, we investigate Pt atom migrations from irregular nanoparticles in a carbon supported platinum catalyst and the resulting faceting. We outline the factors that govern the mechanism involved, with the discovery of single atom interactions which indicate that a primary role of the nanoparticles is to act as reservoirs of low coordination atoms and clusters. This has important implications in supported nanoparticle catalysis and nanoparticle science. In copper and nickel systems, we track the oxidation front at the atomic level as it proceeds across a nanoparticle, by directly monitoring Z-contrast changes with time and temperature. Regeneration of deactivated catalysts is key to prolong catalyst life. We discuss and review analyses of dynamic redox cycles for the redispersion of nickel nanoparticles with single atom resolution. In the FT process, pretreatment of practical cobalt/silica catalysts reveals higher low-coordination Co0 active sites for CO adsorption. Collectively, the ESTEM findings generate structural insights into catalyst dynamics important in the development of efficient catalysts and processes

    Sunset haematology: improving the end-of-life journey for patients and caregivers, in patients with haematologic malignancies

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    BACKGROUND AND AIM Haematologic Malignancies (HM) are diverse diseases with differing illness trajectories and therapeutic pathways. Unfortunately HM patients may rapidly and unexpectedly clinically deteriorate, resulting in suboptimal engagement of palliative and end-of-life (EOL) care.  Compared to patients with solid tumours, HM patients have many different factors affecting their end-of-life (EOL) journey. Uniquely, a subset of HM patients with bone marrow failure (BMF) can be supported for significant, but highly variable, periods of time with red blood cell transfusions (RBCT), platelet transfusions (PT) and prophylactic antibiotics.  Availability of chronic RBCTs and PTs make HM patients with BMF similar to elderly and poor prognosis patients with end stage kidney disease (ESKD). Multidisciplinary Palliative Supportive Care programs have been shown to be effective for these EKSD patients and may serve as supportive care models for EOL journey in HM patients. This project is  a pilot study aiming to provide a template for management of EOL for patients with HM with BMF, and their care-givers. METHODS Three components are being developed: 1) Survey of patient opinions around treatment decision-making. 2) Analyses of the impact of patient, disease and treatment factors on the probability of survival from start of PT, to inform patients. 3) Collaborative involvement between Haematology and Palliative Care staff involved in the local ESKD program, to develop a template for earlier EOL pathway planning in HM patients. CONCLUSION Progress of work to date will be presented including preliminary findings and next steps

    Thermorheological Properties Near the Glass Transition of Oligomeric Poly(methyl methacrylate) Blended with Acrylic Polyhedral Oligomeric Silsesquioxane Nanocages

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    Submitted to Rheologica ActaTwo distinct oligomeric species of similar mass and chemical functionality (Mw ≈ 2,000 g/mol), one a linear methyl methacrylate oligomer (radius of gyration Rg ≈ 1.1 nm) and the other a hybrid organic-inorganic polyhedral silsesquioxane nanocage (methacryl-POSS, r ≈ 1.0 nm), were subjected to thermal and rheological tests to compare the behaviors of these geometrically dissimilar molecules over the entire composition range. The glass transition temperatures of the blends varied monotonically between the glass transition temperatures of the pure oligomer (Tg = â47.3°C) and the pure POSS (Tg = â61.0°C). Blends containing high POSS contents (with volume fraction φ_POSS ⥠0.90) exhibited enhanced enthalpy relaxation in DSC measurements, and the degree of enthalpy relaxation was used to calculate the kinetic fragility indices m of the oligomeric MMA (m = 59) and the POSS (m = 74). The temperature dependences of the viscosities were fitted by the free volume-based WLF-VFT framework and a dynamic scaling relation. The calculated values of the fragility from the WLF-VFT fits were similar for the POSS (m = 82) and for the oligomer (m = 76), and the dynamic scaling exponent was similar for the oligomeric MMA and the POSS. Within the range of known fragilities for glass-forming liquids, the temperature dependence of the viscosity was found to be similarly fragile for the two species. The difference in shape of the nanocages and oligomer chains is unimportant in controlling the glass-forming properties of the blends at low volume fractions ( φPOSS < 0.20); however, at higher volume fractions, adjacent POSS cages begin to crowd each other, leading to an increase in the fractional free volume at the glass transition temperature and the observed enhanced enthalpy relaxation in DSC.AFOSR (DURINT Program

    The organophosphate pesticide chlorpyrifos affects form deprivation myopia

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    PURPOSE. The effects of the anticholinesterase organophosphate pesticide chlorpyrifos (CPF) on the refractive development of the eye were examined. Form deprivation was used to induce eye growth to address the previously reported relationship between organophosphate pesticide use and the incidence of myopia. METHODS. Chickens, a well-established animal model for experimental myopia and organophosphate neurotoxicity, were dosed with chlorpyrifos (3 mg/kg per day, orally, from day 2 to day 9 after hatching) or corn oil vehicle (VEH) with or without monocular form deprivation (MFD) over the same period. The set of dependent measures included the refractive state of each eye measured using retinoscopy, axial dimensions determined with A-scan ultrasound, and intraocular pressure. RESULTS. Dosing with CPF yielded an inhibition of 35% butyrylcholinesterase in plasma and 45% acetylcholinesterase in brain. MFD resulted in a significant degree of myopia in form-deprived eyes resulting from significant lengthening of the vitreal chamber of the eye. CPF significantly reduced the effect of MFD, resulting in less myopic eyes (mean refraction: VEH-MFD = -16.2 ± 2.3 diopters; CPF-MFD = - 11.1 ± 1.8 diopters) with significantly shorter vitreal chambers. Nonoccluded eyes were, on average, slightly hyperopic. Treatment with CPF for 1 week in the absence of MFD led to no significant change in ocular dimensions or refraction relative to controls. CONCLUSIONS. The use of form deprivation as a challenge suggests that CPF treatment interferes with the visual regulation of eye growth

    Effects of fluoride on in vitro hydroxyapatite demineralisation analysed by 19F MAS-NMR

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    IntroductionFluoride plays a major role in inhibiting enamel dissolution and promoting fluorapatite formation. Porous hydroxyapatite (HAP) discs can be used as an enamel analogue in artificial demineralisation/remineralisation studies.MethodThe aim of the study was to monitor the fluoride-mineral phases formed on HAP surfaces as a function of fluoride concentration ([F−]) under demineralising conditions, using 19F magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, and compare the results with a previous study using an enamel substrate. Porous HAP blocks were immersed in demineralisation solutions (0.1 M acetic acid, pH 4.0) with increasing [F−] (0–1450 ppm).ResultsAt below 50 ppm [F−], 19F MAS-NMR showed fluoride-substituted apatite formation; above 50 ppm [F−], calcium fluoride (CaF2) was formed in increasing proportions. These results mirrored those of previous similar studies with an enamel substrate. Further increases in fluoride caused no further measurable reduction in demineralisation but increased the proportion of CaF2 formed. The total calcium concentration [Ca] and total phosphorus [P] concentrations in the solution were measured by inductively coupled plasma atomic emission spectroscopy. At high fluoride concentrations, the solution total [P] increased, and the molar Ca:P ratios decreased to values consistent with the formation of CaF2. However, Ca:P ratios found at low [F−] were higher than those in the previous enamel study and consistent with the formation of a partially fluoridated apatite.ConclusionsUnder demineralising conditions, CaF2 formed on HAP at [F−] of 50 ppm and above, whereas fluoridated apatite formed at [F−] below 50 ppm. The results were consistent with those obtained when an enamel substrate was used

    Effect of Pretreatment Method on the Nanostructure and Performance of Supported Co Catalysts in Fischer−Tropsch Synthesis

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    ABSTRACT: Understanding precursor transformation to active catalysts is crucial to heterogeneous Fischer−Tropsch (FT) catalysis directed toward production of hydrocarbons for transportation fuels. Despite considerable literature on FT catalysis, the effect of pretreatment of supported cobalt catalysts on cobalt dispersion, dynamic atomic structure, and the activity of the catalysts is not well understood. Here we present systematic studies into the formation of active catalyst phases in supported Co catalyst precursors in FT catalysis using in situ environmental (scanning) transmission electron microscopy (E(S)TEM) with single-atom resolution under controlled reaction environments for in situ visualization, imaging, and analysis of reacting atomic species in real time, EXAFS, XAS, DRIFTS analyses, and catalytic activity measurements. We have synthesized and analyzed dried reduced (D) and dried calcined reduced (DC) Co real catalysts on reducible and nonreducible supports, such as SiO2, Al2O3, TiO2, and ZrO2. Comparisons of dynamic in situ atomic structural observations of reacting single atoms, atomic clusters, and nanoparticles of Co and DRIFTS, XAS, EXAFS, and catalytic activity data of the D and DC samples reveal in most cases better dispersion in the D samples, leading to a larger number of low-coordination Co0 sites and a higher number of active sites for CO adsorption. The experimental findings on the degree of reduction of D and 27 DC catalysts on reducible and nonreducible supports and correlations between hexagonal (hcp) Co sites and the activity of the catalysts generate structural insights into the catalyst dynamics, important to the development of efficient FT catalysts

    Security that matters: critical infrastructure and objects of protection

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    Critical infrastructure protection is prominently concerned with objects that appear indispensable for the functioning of social and political life. However, the analysis of material objects in discussions of critical infrastructure protection has remained largely within the remit of managerial responses, which see matter as simply passive, a blank slate. In security studies, critical approaches have focused on social and cultural values, forms of life, technologies of risk or structures of neoliberal globalization. This article engages with the role of "things" or of materiality for theories of securitization. Drawing on the materialist feminism of Karen Barad, it shows how critical infrastructure in Europe neither is an empty receptacle of discourse nor has "essential" characteristics; rather, it emerges out of material-discursive practices. Understanding the securitization of critical infrastructure protection as a process of materialization allows for a reconceptualization of how security matters and its effects
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