5 research outputs found
Heat transport in Weyl semimetals in the hydrodynamic regime
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 , the transverse component depends on
in a non-monotonous way. Via its effect on the Seebeck response, large
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
Anomalous Hall effect in disordered Weyl semimetals
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 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 on
the chemical potential, and show that scales with temperature as
in low temperatures and as in the high temperature limit
Movie 3 - Infiltration assay
Infiltration to stroma assays of MDA231 with and without vimentin expression<br
Movie 2 - Local-density and velocity correlations
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
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