This paper presents a data-driven method for the reconstruction and visualisation of curvilinear slices from three-dimensional (3D) magnetic resonance (MR) scans of the head. Visualisation of curvilinear slices, rather than standard planar slices, produces symmetrical views of the cortex and allows small abnormalities to be detected by comparing the two hemispheres of the brain. In our method, the surface defined by the upper half of the brain is used as a reference shape for curvilinear reconstructions. The brain is first segmented from the 3D scan using a 3D region growing method associated to an unsupervised threshold selection technique. The upper half of the segmented brain is then extracted and fitted by a deformable surface model. This surface is finally interactively moved by the operator in the 3D scan, to visualise the desired curvilinear slice, which is projected on the screen as a two-dimensional image. We show an application of this visualisation technique to the localisation of cerebral epileptogenic lesions. The procedure has proven efficient and handy in clinical use. 相似文献
We report accurate measurements of the current-phase relationship in the flow of superfluid 3He through a single orifice. While ideal sinusoidal 2π-periodic Josephson behavior prevails close to Tc, increasingly strong π-periodic admixture is usually observed at lower temperatures. 相似文献
In the structure of triiodomesitylene (1,3,5‐triiodo‐2,4,6‐trimethylbenzene), C9H9I3, at 293 K, the benzene ring is found to be significantly distorted from ideal D6h symmetry; the average endocyclic angles facing the I atoms and the methyl groups are 123.8 (3) and 116.2 (3)°, respectively. The angle between the normal to the molecular plane and the normal to the (100) plane is 5.1°. No disorder was detected at 293 K. The thermal motion was investigated by a rigid‐body motion tensor analysis. Intra‐ and intermolecular contacts are described and topological differences compared with the isomorphous compounds trichloromesitylene and tribromomesitylene are discussed. 相似文献
We describe the synthesis and characterization of three‐arm star block copolymers based on polystyrene, poly(ethylene oxide), poly(ϵ‐caprolactone), poly(methyl methacrylate), poly(tert‐butyl methacrylate) and poly(L‐lactide) blocks. The copolymers were obtained by a route consisting of two successive initiation steps on functional macroinitiator. Some results on micellization and crystallization are given. They indicate an increase in the miscibility of different incompatible blocks. 相似文献
Piezoelectric devices with integrated actuation and sensing capabilities are often used for the development of electromechanical systems. The present paper addresses experimentally the nonlinear dynamics of a fully integrated circular piezoelectric thin structure, with piezoelectric patches used for actuation and other for sensing. A phase-locked loop control system is used to measure the resonant periodic response of the system under harmonic forcing, in both its stable and unstable parts. The single-mode response around a symmetric resonance as well as the coupled response around an asymmetric resonance, involving two companion modes in 1:1 internal resonance, is accurately measured. For the latter, a particular location of the patches and additional signal processing is proposed to spatially discriminate the response of each companion mode. In addition to a hardening behavior associated with geometric nonlinearities of the plate, a softening behavior predominant at low actuation amplitudes is observed, resulting from the material piezoelectric nonlinearities.