39 research outputs found
Numerical analysis of a Neumann boundary control problem with a stochastic parabolic equation
This paper analyzes the discretization of a Neumann boundary control problem
with a stochastic parabolic equation, where an additive noise occurs in the
Neumann boundary condition. The convergence is established for general
filtrations, and the convergence rate is derived for the natural filtration of the Q-Wiener
process
Extremely large magnetoresistance in topologically trivial semimetal -WP
Extremely large magnetoresistance (XMR) was recently discovered in many
non-magnetic materials, while its underlying mechanism remains poorly
understood due to the complex electronic structure of these materials. Here, we
report an investigation of the -phase WP, a topologically trivial
semimetal with monoclinic crystal structure (C2/m), which contrasts to the
recently discovered robust type-II Weyl semimetal phase in -WP. We
found that -WP exhibits almost all the characteristics of XMR
materials: the near-quadratic field dependence of MR, a field-induced up-turn
in resistivity following by a plateau at low temperature, which can be
understood by the compensation effect, and high mobility of carriers confirmed
by our Hall effect measurements. It was also found that the normalized MRs
under different magnetic fields has the same temperature dependence in
-WP, the Kohler scaling law can describe the MR data in a wide
temperature range, and there is no obvious change in the anisotropic parameter
value with temperature. The resistance polar diagram has a peanut
shape when field is rotated in plane, which can be understood by
the anisotropy of Fermi surface. These results indicate that both
field-induced-gap and temperature-induced Lifshitz transition are not the
origin of up-turn in resistivity in the -WP semimetal. Our findings
establish -WP as a new reference material for exploring the XMR
phenomena.Comment: 18 pages, 12 figure
Nonrigid Registration of Brain Tumor Resection MR Images Based on Joint Saliency Map and Keypoint Clustering
This paper proposes a novel global-to-local nonrigid brain MR image registration to compensate for the brain shift and the unmatchable outliers caused by the tumor resection. The mutual information between the corresponding salient structures, which are enhanced by the joint saliency map (JSM), is maximized to achieve a global rigid registration of the two images. Being detected and clustered at the paired contiguous matching areas in the globally registered images, the paired pools of DoG keypoints in combination with the JSM provide a useful cluster-to-cluster correspondence to guide the local control-point correspondence detection and the outlier keypoint rejection. Lastly, a quasi-inverse consistent deformation is smoothly approximated to locally register brain images through the mapping the clustered control points by compact support radial basis functions. The 2D implementation of the method can model the brain shift in brain tumor resection MR images, though the theory holds for the 3D case