1,609 research outputs found

    Hydrous Titanium Oxide as a Concentrator for Trace Nuclides in Seawater

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    904-90

    The Power of Ranking: The Ease of Doing Business Indicator and Global Regulatory Behavior

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    The proliferation of Global Performance Indicators (GPIs), especially those that rate and rank states against one another, shapes decisions of states, investors, bureaucrats, and voters. This power has not been lost on the World Bank, which has marshaled the Ease of Doing Business (EDB) index to amass surprising influence over global regulatory policies – a domain over which it has no explicit mandate and for which there is ideological contestation. This paper demonstrates how the World Bank’s EDB ranking system affects policy through bureaucratic, transnational, and domestic-political channels. We use observational and experimental data to show that states respond to being publicly ranked and make reforms strategically to improve their ranking. A survey experiment of professional investors demonstrates that the EDB ranking shapes investor perceptions of investment opportunities. Qualitative evidence from India’s interagency EDB effort show how these mechanisms shape domestic politics and policy in the world’s second-largest largest emerging economy

    Combining interpolation and 3D level set method (I+3DLSM) for medical image segmentation

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    A combined interpolation - 3D Level Set Method (I+3DLSM) based segmentation process is presented. The performance in terms of accuracy of the 3-dimensional (3D) level set method (LSM) in the segmentation of throat regions from highly anisotropic magnetic resonance imaging (MRI) volumes, with and without an interpolation step is evaluated. Qualitative and quantitative results from real MRI data suggest that performing interpolation, to reconstruct isotropic MRI volumes, prior to 3D LSM improves the accuracy of the segmentation results, compared to interpolation post 3D LSM and no interpolation at all

    Dense Motion Estimation for Smoke

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    Motion estimation for highly dynamic phenomena such as smoke is an open challenge for Computer Vision. Traditional dense motion estimation algorithms have difficulties with non-rigid and large motions, both of which are frequently observed in smoke motion. We propose an algorithm for dense motion estimation of smoke. Our algorithm is robust, fast, and has better performance over different types of smoke compared to other dense motion estimation algorithms, including state of the art and neural network approaches. The key to our contribution is to use skeletal flow, without explicit point matching, to provide a sparse flow. This sparse flow is upgraded to a dense flow. In this paper we describe our algorithm in greater detail, and provide experimental evidence to support our claims.Comment: ACCV201

    Validation of a magnetic resonance imaging-based auto-contouring software tool for gross tumour delineation in head and neck cancer radiotheraphy planning

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    To perform statistical validation of a newly developed magnetic resonance imaging (MRI) auto-contouring software tool for gross tumour volume (GTV) delineation in head and neck tumours to assist in radiotherapy planning. Axial MRI baseline scans were obtained for 10 oropharyngeal and laryngeal cancer patients. GTV was present on 102 axial slices and auto-contoured using the modified fuzzy c-means clustering integrated with level set method (FCLSM). Peer reviewed (C-gold) manual contours were used as the reference standard to validate auto-contoured GTVs (C-auto) and mean manual contours (C-manual) from 2 expert clinicians (C1 and C2). Multiple geometrical metrics, including Dice Similarity Coefficient (DSC) were used for quantitative validation. A DSC ≥0.7 was deemed acceptable. Inter-and intra-variabilities amongst the manual contours were also validated. The 2-dimension (2D) contours were then reconstructed in 3D for GTV volume calculation, comparison and 3D visualisation. The mean DSC between C-gold and C-auto was 0.79. The mean DSC bet ween C-gold and C-manual was 0.79 and that between C1 and C2 was 0.80. The average time for GTV auto-contouring per patient was 8 minutes (range 6-13mins; mean 45seconds per axial slice) compared to 15 minutes (range 6-23mins; mean 88 seconds per axial slice) for C1. The average volume concordance between C-gold and C-auto volumes was 86. 51% compared to 74.16% between C-gold and C-manual. The average volume concordance between C1 and C2 volumes was 86.82%. This newly-designed MRI-based auto-contouring software tool shows initial acceptable results in GTV delineation of oropharyngeal and laryngeal tumours using FCLSM. This auto-contouring software tool may help reduce inter-and intra- variability and can assist clinical oncologists with time-consuming, complex radiotherapy planning

    Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells

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    A microscopic theory for the generation and propagation of coherent LA phonons in pseudomorphically strained wurzite (0001) InGaN/GaN multi-quantum well (MQW) p-i-n diodes is presented. The generation of coherent LA phonons is driven by photoexcitation of electron-hole pairs by an ultrafast Gaussian pump laser and is treated theoretically using the density matrix formalism. We use realistic wurzite bandstructures taking valence-band mixing and strain-induced piezo- electric fields into account. In addition, the many-body Coulomb ineraction is treated in the screened time-dependent Hartree-Fock approximation. We find that under typical experimental conditions, our microscopic theory can be simplified and mapped onto a loaded string problem which can be easily solved.Comment: 20 pages, 17 figure

    The effect of size ratio on the sphere structure factor in colloidal sphere-plate mixtures

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    The following article appeared in Journal of Chemical Physics 137.20 (2012): 204909 and may be found at http://scitation.aip.org/content/aip/journal/jcp/137/20/10.1063/1.4767722Binary mixtures of colloidal particles of sufficiently different sizes or shapes tend to demix at high concentration. Already at low concentration, excluded volume interactions between the two species give rise to structuring effects. Here, a new theoretical description is proposed of the structure of colloidal sphere-plate mixtures, based on a density expansion of the work needed to insert a pair of spheres and a single sphere in a sea of them, in the presence or not of plates. The theory is first validated using computer simulations. The predictions are then compared to experimental observations using silica spheres and gibbsite platelets. Small-angle neutron scattering was used to determine the change of the structure factor of spheres on addition of platelets, under solvent contrast conditions where the platelets were invisible. Theory and experiment agreed very well for a platelet/sphere diameter ratio Dd 2.2 and reasonably well for Dd 5. The sphere structure factor increases at low scattering vector Q in the presence of platelets; a weak reduction of the sphere structure factor was predicted at larger Q, and for the system with Dd 2.2 was indeed observed experimentally. At fixed particle volume fraction, an increase in diameter ratio leads to a large change in structure factor. Systems with a larger diameter ratio also phase separate at lower concentrationsG. Cinacchi was supported by the EU through a Marie Curie Research Fellowship PIEF-GA-2008-220557 and now by the Ministry of Research of Spain through the RamĂłn y Cajal contract (Contract. No. RYC-2010-07475). N. Doshi was jointly supported by Imerys and EPSRC DTA. Experiments at ILL were supported by beamtime allocations 9-12- 216 and 9-10-1044. Materials were kindly donated by AZ Electronics (Klebosol) and Lubrizol (Solsperse 41000
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