3,005.83
1.28
2,613

Publication History View all

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Our aim is to propose a new approach to breast pattern classification that will aid in the development of an automated mammographic density analysis procedure. Breast patterns broadly classify the mammographic density and density distribution of each mammogram in order to provide a framework for assessing the risk of breast cancer according to density. However, basic weaknesses of classifying mammogram films are the inter and intra-subject variability in interpretation and coding of the patterns by different radiologists as well as the fact that the intensities of the mammogram do not indicate the actual volume of the breast regions. Our endeavour is the development of objective descriptors of breast density based on the digital mammogram. Unlike previous efforts to classify breast patterns based on image texture, we propose the use of density measures based on a normalised representation of the breast (h int representation or SMF) and demonstrate that they can provide a more intuitive quantitative description of mammogram patterns.
    International Workshop on Digital Mammography, Lecture Notes in Computer Science, Springer Verlag Berlin Heidelberg, 2002. 01/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Silver is credited with being a unique catalyst for direct epoxidation of ethene. Copper(II) oxide is known for its combustion catalytic properties in such reactions. In this paper it is reported for the first time that copper oxides under certain conditions can catalyze direct epoxidation of ethene. Reduced copper oxide, ethene, and molecular oxygen are the minimum necessary and sufficient conditions for olefin epoxidation. There is an induction period for the onset of epoxidation. On continual use of this mixed oxide, the selectivity diminishes progressively to about 1%. Reduction of the used mixed oxide restores selectivity, at least in part. A two-stage pulsed reaction (alternating pulses of hydrogen and oxygen in flowing ethene) maintains the selectivity, suggesting that the active species in epoxidation reaction is close to the Cu(I) state. It is also possible to maintain this active species for the sustained reaction by adjusting the oxygen partial pressure to be close to 0.07.
    Journal of Catalysis. 01/2014; 309:309–313.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Understanding and controlling the behaviour of dislocations is crucial for a wide range of applications, from nano-electronics and solar cells to structural engineering alloys. Quantitative X-ray diffraction measurements of the strain fields due to individual dislocations, particularly in the bulk, however, have thus far remained elusive. Here we report the first characterization of a single dislocation in a freestanding GaAs/In0.2Ga0.8As/GaAs membrane by synchrotron X-ray micro-beam Laue diffraction. Our experimental X-ray data agrees closely with textbook anisotropic elasticity solutions for dislocations, providing one of few experimental validations of this fundamental theory. On the basis of the experimental uncertainty in our measurements, we predict the X-ray beam size required for three-dimensional measurements of lattice strains and rotations due to individual dislocations in the material bulk. These findings have important implications for the in situ study of dislocation structure formation, self-organization and evolution in the bulk.
    Nature Communications 11/2013; 4:2774.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The contour method is one of the most prevalent destructive techniques for residual stress measurement. Up to now, the method has involved the use of the finite-element (FE) method to determine the residual stresses from the experimental measurements. This paper presents analytical solutions, obtained for a semi-infinite strip and a finite rectangle, which can be used to calculate the residual stresses directly from the measured data; thereby, eliminating the need for an FE approach. The technique is then used to determine the residual stresses in a variable-polarity plasma-arc welded plate and the results show good agreement with independent neutron diffraction measurements.
    Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences 11/2013; 469(2159):20130367.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanomaterial-mediated delivery represents a promising technique for reproductive biology with a potential to improve the safety and efficacy of existing methodologies, including experimental gene therapy and sperm-mediated gene transfer. Mesoporous silica nanoparticles (MSNPs) have been characterised as a powerful and safe delivery tool, rendering them an excellent candidate for use in reproductive research. However, their effects upon mammalian gametes with highly specialised structure and functionality remain untested. Here, we show for the first time, that spherical MSNPs with hexagonal pore symmetry, functionalised with polyethileneimine and aminopropyltriethoxysilane, and optionally loaded with two common types of cargo (nucleic acid/protein), form strong associations with boar sperm following incubation in vitro and do not exert negative effect upon the main parameters of sperm function, including motility, viability, acrosomal status and DNA fragmentation index. Our findings provide a rationale for the use of MSNPs for the transfer of investigative, diagnostic and/or therapeutic compounds into mammalian sperm.
    Nanomedicine: nanotechnology, biology, and medicine 11/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Human enamel is a typical hierarchical mineralized tissue with a two-level composite structure. To date, few studies have focused on how the mechanical behaviour of this tissue is affected by both the rod orientation at micro-scale and the preferred orientation of mineral crystallites at the nano-scale. In this study, Wide Angle X-ray Scattering (WAXS) was used to determine the internal lattice strain response of human enamel samples (with differing rod directions) as a function of in situ uniaxial compressive loading. Quantitative stress distribution evaluation in the birefringent mounting epoxy was performed in parallel using photoelastic techniques. The resulting experimental data was analysed using an advanced multi-scale Eshelby inclusion model that takes into account the two-level hierarchical structure of human enamel, and reflects the differing rod directions and orientation distributions of HAp crystals. The achieved satisfactory agreement between the model and the experimental data, in terms of the values of multi-directional strain components under the action of differently orientated loads, suggests that the multi-scale approach captures reasonably successfully the structure-property relationship between the hierarchical architecture of human enamel and its response to the applied forces. This novel and systematic approach can be used to improve the interpretation of the mechanical properties of enamel, as well as of the textured hierarchical biomaterials in general.
    Acta biomaterialia 10/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Human enamel is a hierarchical mineralized tissue with a two-level composite structure. Few studies have focused on the structure-mechanical property relationship and its link to the multi-scale architecture of human enamel, whereby the response to mechanical loading is affected not only by the rod distribution at micro-scale, but also strongly influenced by the mineral crystallite shape, and spatial arrangement and orientation. In this study, two complementary synchrotron X-ray diffraction techniques, Wide and Small Angle X-ray Scattering (WAXS/SAXS) were used to obtain multi-scale quantitative information about the structure and deformation response of human enamel to in situ uniaxial compressive loading. The apparent modulus was determined linking the external load and the internal strain in hydroxyapatite (HAp) crystallites. An improved multi-scale Eshelby model is proposed taking into account the two-level hierarchical structure of enamel. This framework has been used to analyse the experimental data for the elastic lattice strain evolution within the HAp crystals. The achieved agreement between the model prediction and experiment along the loading direction validates the model and suggests that the new multi-scale approach reasonably captures the structure-property relationship for the human enamel. The ability of the model to predict multi-directional strain components is also evaluated by comparison with the measurements. The results are useful for understanding the intricate relationship between the hierarchical structure and the mechanical properties of enamel, and for making predictions of the effect of structural alterations that may occur due to the disease or treatment on the performance of dental tissues and their artificial replacements.
    Journal of Structural Biology 10/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rationale: Sarcomere length (SL) is a key indicator of cardiac mechanical function, but current imaging technologies are limited in their ability to unambiguously measure and characterize SL at the cell level in intact, living tissue. Objective: We develop a method for measuring SL and regional cell orientation, using remote focusing microscopy, an emerging imaging modality that can capture light from arbitrary oblique planes within a sample. Methods and Results: We present a protocol that unambiguously and quickly determines cell orientation from user-selected areas in a field of view, by imaging two oblique planes that share a common major axis with the cell. We demonstrate the effectiveness of this technique in establishing single cell SL in Langendorff perfused hearts, loaded with the membrane dye di-4-ANEPPS. Conclusions: Remote focusing microscopy can measure cell orientation in complex two photon data sets without capturing full z-stacks. The technique allows rapid assessment of SL in healthy and diseased heart experimental preparations.
    Circulation Research 07/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The contribution of flexoelectric polarization to the dielectric susceptibility in helicoidal liquid crystals is formulated for the static equilibrium case, and further in the case of a time-varying field. A dispersion of the dielectric permittivity due to the frequency response of flexoelectric switching is described. The special case of a negative dielectric-anisotropy nematic material is considered and experimentally shown to agree with the analytical theory. It is further demonstrated how relaxation of the flexoelectric contribution to the dielectric tensor in this special case can be exploited to switch between states in cholesteric liquid crystal structures by altering the applied time-dependent field amplitude, if Δɛ<0 and (e_{1}-e_{3})^{2}/(K_{1}+K_{3})>-Δɛɛ_{0}. Consequentially, a versatile mechanism for driving between states in liquid crystal systems has been demonstrated and its implications for technology are suggested, and include dual-mode, bistable, and transflective displays.
    Physical Review E 07/2013; 88(1-1):012506.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The recovery of structure from motion in real time over extended areas demands methods that mitigate the effects of computational complexity and arithmetical inconsistency. In this paper, we develop SCISM, an algorithm based on relative frame bundle adjustment, which splits the recovered map of 3D landmarks and keyframes poses so that the camera can continue to grow and explore a local map in real time while, at the same time, a bulk map is optimized in the background. By temporarily excluding certain measurements, it ensures that both maps are consistent, and by using the relative frame representation, new results from the bulk process can update the local process without disturbance. The paper first shows how to apply this representation to the parallel tracking and mapping (PTAM) method, a real-time bundle adjuster, and compares results obtained using global and relative frames. It then explains the relative representation's use in SCISM and describes an implementation using PTAM. The paper provides evidence of the algorithm's real-time operation in outdoor scenes, and includes comparison with a more conventional submapping approach.
    IEEE Transactions on Software Engineering 06/2013; 35(6):1451-1463.
Information provided on this web page is aggregated encyclopedic and bibliographical information relating to the named institution. Information provided is not approved by the institution itself. The institution’s logo (and/or other graphical identification, such as a coat of arms) is used only to identify the institution in a nominal way. Under certain jurisdictions it may be property of the institution.
View all

Top publications last week

 
Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
154 Downloads
 
Magnetic Nanoparticles: From Fabrication to Clinical Applications edited by N. T. K. Thanh, 07/2012: chapter Magnetic Microbubbles: pages 499-522; CRC Press.
113 Downloads