5 research outputs found

    Heat transport in Weyl semimetals in the hydrodynamic regime

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    We study heat transport in a Weyl semimetal with broken time-reversal symmetry in the hydrodynamic regime. At the neutrality point, the longitudinal heat conductivity is governed by the momentum relaxation (elastic) time, while longitudinal electric conductivity is controlled by the inelastic scattering time. In the hydrodynamic regime this leads to a large longitudinal Lorenz ratio. As the chemical potential is tuned away from the neutrality point, the longitudinal Lorenz ratio decreases because of suppression of the heat conductivity by the Seebeck effect. The Seebeck effect (thermopower) and the open circuit heat conductivity are intertwined with the electric conductivity. The magnitude of Seebeck tensor is parametrically enhanced, compared to the non-interacting model, in a wide parameter range. While the longitudinal component of Seebeck response decreases with increasing electric anomalous Hall conductivity σxy\sigma_{xy}, the transverse component depends on σxy\sigma_{xy} in a non-monotonous way. Via its effect on the Seebeck response, large σxy\sigma_{xy} enhances the longitudinal Lorenz ratio at a finite chemical potential. At the neutrality point, the transverse heat conductivity is determined by the Wiedemann-Franz law. Increasing the distance from the neutrality point, the transverse heat conductivity is enhanced by the transverse Seebeck effect and follows its non-monotonous dependence on σxy\sigma_{xy}

    Anomalous Hall effect in disordered Weyl semimetals

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    We study the anomalous Hall effect in a disordered Weyl semimetal. While the intrinsic contribution is expressed solely in terms of Berry curvature, the extrinsic contribution is given by a combination of the skew scattering and side jump terms. For the model of small size impurities, we are able to express the skew scattering contribution in terms of scattering phase shifts. We identify the regime in which the skew scattering contribution dominates the side-jump contribution: the impurities are either strong or resonant, and at dilute concentration. In this regime, the Hall resistivity ρxy\rho_{xy} is expressed in terms of two scattering phases, analogous to the s-wave scattering phase in a non-topological metal. We compute the dependence of ρxy\rho_{xy} on the chemical potential, and show that ρxy\rho_{xy} scales with temperature as T2T^2 in low temperatures and as T3/2T^{3/2} in the high temperature limit

    Movie 3 - Infiltration assay

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    Infiltration to stroma assays of MDA231 with and without vimentin expression<br

    Movie 2 - Local-density and velocity correlations

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    Velocity and local density evolution over time for MDA231 cells, with and without vimentin expression. MDA231 cells expressing vimentin (but not vimentin knockdown cells) show positive correlation between the velocity and the local density.<br

    The role of Vimentin in Regulating Cell Invasive Migration in Dense Cultures of Breast Carcinoma Cells

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    Cell migration and mechanics are tightly regulated by the integrated activities of the various cytoskeletal networks. In cancer cells, cytoskeletal modulations have been implicated in the loss of tissue integrity and acquisition of an invasive phenotype. In epithelial cancers, for example, increased expression of the cytoskeletal filament protein vimentin correlates with metastatic potential. Nonetheless, the exact mechanism whereby vimentin affects cell motility remains poorly understood. In this study, we measured the effects of vimentin expression on the mechano-elastic and migratory properties of the highly invasive breast carcinoma cell line MDA231. We demonstrate here that vimentin stiffens cells and enhances cell migration in dense cultures, but exerts little or no effect on the migration of sparsely plated cells. These results suggest that cell–cell interactions play a key role in regulating cell migration, and coordinating cell movement in dense cultures. Our findings pave the way toward understanding the relationship between cell migration and mechanics in a biologically relevant context
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