R. P. Millane

University of Canterbury, Christchurch, Canterbury Region, New Zealand

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Publications (147)578.28 Total impact

  • Rick P. Millane, Victor L. Lo
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    ABSTRACT: A general class of iterative projection algorithms is described and proposed as a tool for phasing in protein crystallography in order to improve the radius of convergence over that of conventional density‐modification algorithms. Their relationship to conventional density modification is described. The common iterative projection algorithms, their convergence properties and their application to protein crystallography are described. These algorithms offer the possibility of protein structure determination starting with only information on the molecular envelope and low‐order non‐crystallographic symmetry.
    Acta Crystallographica Section A Foundations of Crystallography 01/2013; 69(5). · 2.24 Impact Factor
  • Victor Lo, Rick P. Millane
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    ABSTRACT: A brief description of various iterative projection algorithms and the relationships between them is given, along with some possible reasons for their ability to solve non-convex problems. An empirical model of their behaviour when applied to non-convex problems is also described.
    Proc SPIE 10/2012;
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    ABSTRACT: The problem of estimating wind velocities from limited flight data recordings is considered, with application to sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the sailplane airspeed and heading. The method is tested by simulation and by application to sailplane flight data.
    Proc SPIE 10/2012;
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    ABSTRACT: Two improved compressed sensing (CS)-based image reconstruction methods for MRI are proposed: prior estimate-based compressed sensing (PECS) and sensitivity encoding-based compressed sensing (SENSECS). PECS allows prior knowledge of the underlying image to be intrinsically incorporated in the image recovery process, extending the use of data sorting as first proposed by Adluru and DiBella (Int J Biomed Imaging 2008: 341648). It does so by rearranging the elements in the underlying image based on the magnitude information gathered from a prior image estimate, so that the underlying image can be recovered in a new form that exhibits a higher level of sparsity. SENSECS is an application of PECS in parallel imaging. In SENSECS, image reconstruction is carried out in two stages: SENSE and PECS, with the SENSE reconstruction being used as a image prior estimate in the following PECS reconstruction. SENSECS bypasses the conflict of sampling pattern design in directly applying CS recovery in multicoil data sets and exploits the complementary characteristics of SENSE-type and CS-type reconstructions, hence achieving better image reconstructions than using SENSE or CS alone. The characteristics of PECS and SENSECS are investigated using experimental data.
    Magnetic Resonance in Medicine 10/2010; 65(1):83-95. · 3.27 Impact Factor
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    Philip J. Bones, Michael A. Fiddy, Rick P. Millane
    Proc SPIE 08/2010;
  • Ni Zhang, Rick P. Millane, Alan J. Hunter
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    ABSTRACT: The problem of estimating the wind velocity from measurement of limited flight data from a sailplane flight in atmospheric mountain waves is considered. A Sailplane are often equipped with a flight recorder that records position, and sometimes other information, at regular intervals during the flight. These data contain information on the state of the atmosphere during the flight. A maximum likelihood method is developed for estimating wind fields using such sailplane flight data. The methods are evaluated by application to simulated flight data.
    Proc SPIE 08/2010;
  • V. L. Lo, R. P. Millane
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    ABSTRACT: Symmetry provides a source of redundancy which can be exploited in image reconstruction. In particular, internal symmetries in molecules can help to compensate for the loss of Fourier phase information in macromolecular x-ray crystallography. Symmetry projections are incorporated into iterative projection algorithms for reconstruction of macromolecular electron densities from x-ray diffraction amplitudes from crystals. The effects of interpolation are studied and the algorithms are applied to reconstruction of an icosahedral virus.
    Proc SPIE 08/2010;
  • Joe Chen, Veit Elser, R. P. Millane
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    ABSTRACT: The problem of optimizing antenna locations in a radio telescope with a large number of antennas is addressed. An algorithm is developed that first optimizes the probability density function of the antenna positions and this distribution is subsequently sampled. This approach avoids the large number of variables with many antennas. The density function is optimized subject to terrain constraints and the distribution of visibility samples. The optimization is solved by mapping the problem to a phase retrieval problem which is solved using an iterative projection algorithm.
    01/2010;
  • Journal of Atmospheric and Oceanic Technology 01/2010; 27(1). · 1.69 Impact Factor
  • N. Zhang, R. P. Millane, A. J. Hunter
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    ABSTRACT: Maximum likelihood (ML) and maximum a posteriori (MAP) estimators are described for the estimation of wind velocity using position, and airspeed measurements from flight data recordings. The estimators are demonstrated using simulated flight data and experimental flight data from a high-altitude sailplane flight.
    01/2010;
  • Source
    B. Wu, R. Watts, R. P. Millane, P. J. Bones
    International Society for Magnetic Resonance in Medicine, Stockholm, Sweden; 01/2010
  • Source
    International Society for Magnetic Resonance in Medicine, Stockholm, Sweden; 01/2010
  • Victor L. Lo, Rick P. Millane
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    ABSTRACT: The electron density of an icosahedral virus with 5-fold non-crystallographic symmetry is reconstructed ab initio from crystal x-ray diffraction amplitudes using the difference map projection algorithm.
    Signal Recovery and Synthesis; 10/2009
  • R P Millane, W H Hsiao
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    ABSTRACT: Phase dominance is a phenomenon that has been widely observed in imaging, visual perception, and other technical areas. Here we show for general images that phase dominance, in terms of exchanging the spectral amplitude and phase of two images, is simply explained by the expected mean square error.
    Optics Letters 10/2009; 34(17):2607-9. · 3.39 Impact Factor
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    ABSTRACT: An algorithm is described for determining macromolecular envelopes from crystal diffraction amplitudes measured from a solvent contrast variation series. The method uses solvent contrast variation data that have been preprocessed to represent the structure-factor amplitudes of the envelope. The amplitudes are phased using an iterative projection algorithm that incorporates connectivity and compactness constraints on the envelope. The algorithm is tested by simulation on two protein envelopes and shown to be effective even in the absence of the very low resolution data, which are difficult to access experimentally.
    Acta crystallographica. Section A, Foundations of crystallography 08/2009; 65(Pt 4):312-8. · 49.93 Impact Factor
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    ABSTRACT: An automated image analysis system for determining myosin filament azimuthal rotations, or orientations, in electron micrographs of muscle cross sections is described. The micrographs of thin sections intersect the myosin filaments which lie on a triangular lattice. The myosin filament profiles are variable and noisy, and the images exhibit a variable contrast and background. Filament positions are determined by filtering with a point spread function that incorporates the local symmetry of the lattice. Filament orientations are determined by correlation with a template that incorporates the salient filament characteristics, and the orientations are classified using a Gaussian mixture model. The precision of the technique is assessed by application to a variety of micrographs and comparison with manual classification of the orientations. The system provides a convenient, robust, and rapid means of analysing micrographs containing many filaments to study the distribution of filament orientations.
    IEEE Transactions on Image Processing 05/2009; 18(4):831-9. · 3.20 Impact Factor
  • David H Wojtas, R P Millane
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    ABSTRACT: A number of aspects of the two-point correlation behavior of the nearest-neighbor, triangular Ising antiferromagnet are studied using a combination of numerical evaluation of exact expressions and Monte Carlo simulation. Existing asymptotic results for on-axis correlations at finite temperatures are evaluated and shown to be of limited accuracy. The sublattice structure of the off-axis correlation function is clarified, and rotational invariance is studied as a function of temperature. Separations and temperatures for which the correlation function is significant are identified, and a simple functional expression is developed that allows accurate calculation of the correlation function in this region.
    Physical Review E 05/2009; 79(4 Pt 1):041123. · 2.31 Impact Factor
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    ABSTRACT: A new 3D parallel magnetic resonance imaging (MRI) method named Generalized Unaliasing Incorporating Support constraint and sensitivity Encoding (GUISE) is presented. GUISE allows direct image recovery from arbitrary Cartesian k-space trajectories. However, periodic k-space sampling patterns are considered for reconstruction efficiency. Image recovery methods such as 2D SENSE (SENSitivity Encoding) and 2D CAIPIRINHA (Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration) are special instances of GUISE where specific restrictions are placed on the k-space sampling patterns used. It is shown that the sampling pattern has large impacts on the image reconstruction error due to noise. An efficient sampling pattern design method that incorporates prior knowledge of object support and coil sensitivity profile is proposed. It requires no experimental trials and could be used in clinical imaging. Comparison of the proposed sampling pattern design method with 2D SENSE and 2D CAIPIRINHA are made based on both simulation and experiment results. It is seen that this new adaptive sampling pattern design method results in a lower noise level in reconstructions due to better exploitation of the coil sensitivity variation and object support constraint. In addition, elimination of the non-object region from reconstruction potentially allows an acceleration factor higher than the number of receiver coils used.
    Magnetic Resonance Imaging 04/2009; 27(7):942-53. · 2.06 Impact Factor
  • Biophysical Journal 01/2009; 96(3). · 3.67 Impact Factor
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    ABSTRACT: An automated image analysis system for determination of myosin filament orientations in electron micrographs of muscle cross-sections is described. Analysis of the distribution of the orientations is important in studies of muscle structure, particularly for interpretation of x-ray diffraction data. Filament positions are determined using h-dome extraction and image filtering, based on grayscale reconstruction. Erroneous locations are eliminated based on lattice regularity. Filament orientations are determined by correlation with a template that incorporates the salient filament characteristics and classified using a Gaussian mixture model. Application to a number of micrographs and comparison with manual classifications of orientations shows that the system is effective in many cases.
    IEEE Transactions on Image Processing 01/2009; 18:831-839. · 3.20 Impact Factor

Publication Stats

989 Citations
578.28 Total Impact Points

Institutions

  • 1982–2013
    • University of Canterbury
      • Department of Electrical and Computer Engineering
      Christchurch, Canterbury Region, New Zealand
  • 2010
    • Duke University Medical Center
      • Brain Imaging and Analysis Center
      Durham, NC, United States
  • 2008
    • Cornell University
      • Department of Physics
      Ithaca, NY, United States
  • 2005
    • Canterbury Christ Church University
      Cantorbery, England, United Kingdom
    • Girne American University Canterbury
      Cantorbery, England, United Kingdom
  • 1983–2004
    • Purdue University
      • • School of Electrical and Computer Engineering
      • • Whistler Center for Carbohydrate Research
      • • Department of Biological Sciences
      West Lafayette, IN, United States