7,851 research outputs found

    Older people, regeneration and health and well-being. Case study of Salford Partnership Board for Older People

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    This study sat within a national project aimed at demonstrating that expert knowledge housed within universities can make a positive impact in urban communities around four themes: Community Cohesion, Crime, Enterprise and Health & Wellbeing. It involved the Universities of Salford, Northumbria, Central Lancashire, Manchester Metropolitan University and Bradford. The project aimed to address key urban regeneration challenges in the North of England through inter-disciplinary collaboration between partner universities and practitioner organisations. It also sought to build a long term strategic alliance between core university partners. Within each of the four project areas there were a number of smaller projects each focusing on the relationship between the theme and urban regeneration. This study sought to establish how partnership boards for older people address the health and well being needs of people over 50 years of age including how health and wellbeing are defined; strategies older people adopt to change service providers' actions; learning by service providers about the involvement of older people on Boards; and how this influences practice. The main activity within this study was to interview Salford Partnership Board members. The findings informed further development of the Board

    Time-Space Lower Bounds for Simulating Proof Systems with Quantum and Randomized Verifiers

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    A line of work initiated by Fortnow in 1997 has proven model-independent time-space lower bounds for the SAT\mathsf{SAT} problem and related problems within the polynomial-time hierarchy. For example, for the SAT\mathsf{SAT} problem, the state-of-the-art is that the problem cannot be solved by random-access machines in ncn^c time and no(1)n^{o(1)} space simultaneously for c<2cos(π7)1.801c < 2\cos(\frac{\pi}{7}) \approx 1.801. We extend this lower bound approach to the quantum and randomized domains. Combining Grover's algorithm with components from SAT\mathsf{SAT} time-space lower bounds, we show that there are problems verifiable in O(n)O(n) time with quantum Merlin-Arthur protocols that cannot be solved in ncn^c time and no(1)n^{o(1)} space simultaneously for c<3+322.366c < \frac{3+\sqrt{3}}{2} \approx 2.366, a super-quadratic time lower bound. This result and the prior work on SAT\mathsf{SAT} can both be viewed as consequences of a more general formula for time lower bounds against small-space algorithms, whose asymptotics we study in full. We also show lower bounds against randomized algorithms: there are problems verifiable in O(n)O(n) time with (classical) Merlin-Arthur protocols that cannot be solved in ncn^c randomized time and no(1)n^{o(1)} space simultaneously for c<1.465c < 1.465, improving a result of Diehl. For quantum Merlin-Arthur protocols, the lower bound in this setting can be improved to c<1.5c < 1.5.Comment: 38 pages, 5 figures. To appear in ITCS 202

    Epitaxial grain growth during surface modification of friction stir welded aerospace alloys by a pulsed laser system

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    The liquid film re-growth behaviour resulting from pulsed laser surface melting (LSM) has been investigated for typical 2xxx, and 7xxx aerospace alloys, both on parent plate and friction stir welded (FSW) joints. In Zr free alloys, as a result of the high growth rate and steep thermal gradient, the melted layer re-grew with a stable front, epitaxially, from the parent subsurface grains. This caused a thin coarse grained solidified layer to form over the parent material, thermomechanically affected zone (TMAZ) and heat affected zone (HAZ), and fine columnar grains to develop over the FSW nugget zone of the same order in width as the nugget grain size. In the case of the Zr containing alloys, a very fine columnar grain structure was found over the entire surface, independent of the subsurface grain structure. This has been shown to occur by growth selection from a band of nanoscale Al grains epitaxially nucleated on Al3Zr dispersoids, at the melt solid interface, that had not fully dissolved in the melt

    Concrete Box Beam Risk Assessment and Mitigation: Volume 2—Evaluation and Structural Behavior

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    Adjacent box beam bridges have a history of poor long-term performance including premature deterioration and failures. Leaking joints between box beams allow chloride-laden water to migrate through the superstructure and initiate corrosion. The nature of this deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. The objective of this research is to develop recommendations for inspection, load-rating, and design of adjacent box beam bridges. The research is presented in two volumes. Volume 1 focuses on the evolution of box beam design in Indiana to understand the lack of performance and durability. The Indiana Department of Transportation (INDOT) standards and bridge design manuals were reviewed to track the historical development of box beam bridges in the State. Two timelines were produced tracking important updates to box beam design. Adjacent box beam bridges within INDOT’s bridge database were also analyzed. Superstructure ratings were compared with bridge age as well as bridge characteristics to highlight possible causes for deterioration. Analyzing the INDOT inventory, data shows that the condition of adjacent box beam bridges may be affected by location, type of wearing surface, and the use of deck membranes. Six bridges were then inspected to identify common deficiencies and specific problems. Exterior beams and beams within the wheel load path tend to have higher levels of deterioration. Furthermore, leaking joints between beams leads to corrosion of reinforcement, ultimately resulting in spalling, fracture of prestressing strands, and loss of structural capacity. Volume 2 focuses on evaluating the capacity of deteriorated adjacent box beams, the development of improved load rating procedures, and new box beam design. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. Deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedures are provided along with design recommendations for the next generation of box beam bridges

    Concrete Box Beam Risk Assessment and Mitigation: Volume 1—Evolution and Performance

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    Adjacent box beam bridges have a history of poor long-term performance including premature deterioration and failures. Leaking joints between box beams allow chloride-laden water to migrate through the superstructure and initiate corrosion. The nature of this deterioration leads to uncertainty of the extent and effect of deterioration on structural behavior. Due to limitations in previous research and understanding of the strength of deteriorated box beam bridges, conservative assumptions are made for the assessment and load rating of these bridges. Furthermore, the design of new box beam bridges, which can offer an efficient and economical solution, is often discouraged due to poor past performance. The objective of this research is to develop recommendations for inspection, load-rating, and design of adjacent box beam bridges. The research is presented in two volumes. Volume 1 focuses on the evolution of box beam design in Indiana to understand the lack of performance and durability. The Indiana Department of Transportation (INDOT) standards and bridge design manuals were reviewed to track the historical development of box beam bridges in the State. Two timelines were produced tracking important updates to box beam design. Adjacent box beam bridges within INDOT’s bridge database were also analyzed. Superstructure ratings were compared with bridge age as well as bridge characteristics to highlight possible causes for deterioration. Analyzing the INDOT inventory, data shows that the condition of adjacent box beam bridges may be affected by location, type of wearing surface, and the use of deck membranes. Six bridges were then inspected to identify common deficiencies and specific problems. Exterior beams and beams within the wheel load path tend to have higher levels of deterioration. Furthermore, leaking joints between beams leads to corrosion of reinforcement, ultimately resulting in spalling, fracture of prestressing strands, and loss of structural capacity. Volume 2 focuses on evaluating the capacity of deteriorated adjacent box beams, the development of improved load rating procedures, and new box beam design. Through a series of bridge inspections, deteriorated box beams were identified and acquired for experimental testing. The extent of corrosion was determined through visual inspection, non-destructive evaluation, and destructive evaluation. Non-destructive tests (NDT) included the use of connectionless electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and half-cell potentials. Deteriorated capacity was determined through structural testing, and an analysis procedure was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed to restore load transfer of adjacent beams in cases where shear key failures are suspected. Based on the understanding of deterioration developed through study of deteriorated adjacent box beam bridges, improved inspection and load rating procedures are provided along with design recommendations for the next generation of box beam bridges

    Fifty Years of Science at the Kluane Lake Research Station

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    Circuit Depth Reductions

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    The best known size lower bounds against unrestricted circuits have remained around 3n3n for several decades. Moreover, the only known technique for proving lower bounds in this model, gate elimination, is inherently limited to proving lower bounds of less than 5n5n. In this work, we propose a non-gate-elimination approach for obtaining circuit lower bounds, via certain depth-three lower bounds. We prove that every (unbounded-depth) circuit of size ss can be expressed as an OR of 2s/3.92^{s/3.9} 1616-CNFs. For DeMorgan formulas, the best known size lower bounds have been stuck at around n3o(1)n^{3-o(1)} for decades. Under a plausible hypothesis about probabilistic polynomials, we show that n4εn^{4-\varepsilon}-size DeMorgan formulas have 2n1Ω(ε)2^{n^{1-\Omega(\varepsilon)}}-size depth-3 circuits which are approximate sums of n1Ω(ε)n^{1-\Omega(\varepsilon)}-degree polynomials over F2{\mathbb F}_2. While these structural results do not immediately lead to new lower bounds, they do suggest new avenues of attack on these longstanding lower bound problems. Our results complement the classical depth-33 reduction results of Valiant, which show that logarithmic-depth circuits of linear size can be computed by an OR of 2εn2^{\varepsilon n} nδn^{\delta}-CNFs, and slightly stronger results for series-parallel circuits. It is known that no purely graph-theoretic reduction could yield interesting depth-3 circuits from circuits of super-logarithmic depth. We overcome this limitation (for small-size circuits) by taking into account both the graph-theoretic and functional properties of circuits and formulas. We show that improvements of the following pseudorandom constructions imply new circuit lower bounds: dispersers for varieties, correlation with constant degree polynomials, matrix rigidity, and hardness for depth-33 circuits with constant bottom fan-in
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