Quinnvangsgaard6071

In this work, we develop an index signature characterising the third order topological phases in 3D systems. This index is an alternating sum of monomial signatures of Higgs triplet values at 3D corners. We extend our method to N-dimensional systems with open boundaries, and demonstrate that the topological invariant can be efficiently generalised to any space dimension including the second order topological insulators. Known results on lower dimensional systems are recovered and an interpretation in the Higgs space parameters is given. © 2020 IOP Publishing Ltd.Collective cell migration is crucial in many biological processes such as wound healing, tissue morphogenesis, and tumor progression. The leading front of a collective migrating epithelial cell layer often destabilizes into multicellular finger-like protrusions, each of which is guided by a leader cell at the fingertip. Here, we develop a subcellular-element-based model of this fingering instability, which incorporates leader cells and other related properties of a monolayer of epithelial cells. Our model recovers multiple aspects of the dynamics, especially the traction force patterns and velocity fields, observed in experiments on MDCK cells. Our model predicts the necessity of the leader cell and its minimal functions for the formation and maintenance of a stable finger pattern. Meanwhile, our model allows for an analysis of the role of supra-cellular actin cable on the leading front, predicting that while this observed structure helps maintain the shape of the finger, it is not required in order to form a finger. In addition, we also study the driving instability in the context of continuum active fluid model, which justifies some of our assumptions in the computational approach. In particular, we show that in our model no finger protrusions would emerge in a phenotypically homogenous active fluid and hence the role of the leader cell and its followers are often critical. © 2020 IOP Publishing Ltd.The suppression of streak artifacts in computed tomography with a limited-angle configuration is challenging. Conventional analytical algorithms, such as filtered backprojection (FBP), are not successful due to incomplete projection data. Moreover, model-based iterative total variation (TV) algorithms effectively reduce small streaks but do not work well at eliminating large streaks. In contrast, FBP mapping networks and deep-learning-based postprocessing networks are outstanding at removing large streak artifacts; however, these methods perform processing in separate domains, and the advantages of multiple deep learning algorithms operating in different domains have not been simultaneously explored. In this paper, we present a hybrid domain convolutional neural network (hdNet) for the reduction of streak artifacts in limited-angle computed tomography. The network consists of three components the first component is a convolutional neural network operating in the sinogram domain, the second is a domain transformation operation, and the last is a convolutional neural network operating in the CT image domain. After training the network, we can obtain artifact-suppressed CT images directly from the sinogram domain. Verification results based on numerical, experimental and clinical data confirm that the proposed method can significantly reduce serious artifacts. © 2020 Institute of Physics and Engineering in Medicine.3D-printed titanium alloy orthopedic implants combine the dual advantages of 3D printing and titanium alloys implants, which not only have complex structures that cannot be manufactured by traditional techniques, but also inherit the excellent physical and chemical properties of titanium and its alloys, so they are widely used in the field of orthopedics in recent years. The inherent porous structure of 3D-printed implants and the original modification processes of titanium alloys provide the conditions for the functionalization of implants. To meet the needs of orthopedic surgeons and patients, functionalized implants with the ability of long-term stability promotion, anti-infection or anti-tumor have been developed, in which various methods of functionalization deserve to be summarized, compared and analyzed. Therefore, in this review, we will collect the existing knowledge on functionalization of 3D-printed titanium alloy orthopedic implants and give our own opinion. © 2020 IOP Publishing Ltd.We present first principles calculations of the electrostatic properties of Ba$_2$NaOsO$_6$ (BNOO), a 5$d^1$ Mott insulator with strong spin orbit coupling (SOC) in its low temperature quantum phases. In light of recent NMR experiments showing that BNOO develops a local octahedral distortion that is accompanied by the emergence of an electric field gradient (EFG) and precedes the formation of long range magnetic order [Lu \etal, Nature Comm. \bf 8, 14407 (2017), Liu \etal, Phys. Rev. B \bf 97, 224103 (2018), Liu \etal, Physica B \bf 536, 863 (2018)], we calculated BNOO's EFG tensor for several different model distortions. The local orthorhombic distortion that we identified as mostly strongly agreeing with experiment corresponds to a Q2 distortion mode of the Na-O octahedra, in agreement with conclusions given in [Liu \etal, Phys. Rev. B \bf 97, 224103 (2018)]. Furthermore, we found that the EFG is insensitive to the type of underlying magnetic order. By combining NMR results with first principles modeling, we have thus forged a more complete understanding of BNOO's structural and magnetic properties, which could not be achieved based upon experiment or theory alone. © 2020 IOP Publishing Ltd.Thermal transport in graphene is strongly influenced by strain. We investigate the influence of biaxial tensile strain on the thermal conductivity of zigzag and armchair graphene (AG and ZG) using Non-Equilibrium Molecular Dynamics simulations (NEMD). Selleckchem Bezafibrate We observe that the thermal conductivity is significantly reduced under strain with a maximum reduction obtained at equi-biaxial strain. It is interesting to note that the high lateral to longitudinal strain ratios reduces the negative impact of strain on the thermal conductivity of AG and ZG. The in-plane acoustic modes are found to be the major heat carriers in unstrained graphene but are severely softened due to strain, and hence, their contribution to the conductivity drops down significantly. Strain alleviates the out-of-plane fluctuations in graphene and the group velocity of the out-of-plane acoustic mode (ZA) increases due to the linearisation of its dispersion relation. These factors result in the dominance of ZA mode in the thermal transport of strained graphene.