7,126 research outputs found
Bifurcations in valveless pumping techniques from a coupled fluid-structure-electrophysiology model in heart development
We explore an embryonic heart model that couples electrophysiology and
muscle-force generation to flow induced using a fluid-structure
interaction framework based on the immersed boundary method. The propagation of
action potentials are coupled to muscular contraction and hence the overall
pumping dynamics. In comparison to previous models, the electro-dynamical model
does not use prescribed motion to initiate the pumping motion, but rather the
pumping dynamics are fully coupled to an underlying electrophysiology model,
governed by the FitzHugh-Nagumo equations. Perturbing the diffusion parameter
in the FitzHugh-Nagumo model leads to a bifurcation in dynamics of action
potential propagation. This bifurcation is able to capture a spectrum of
different pumping regimes, with dynamic suction pumping and peristaltic-like
pumping at the extremes. We find that more bulk flow is produced within the
realm of peristaltic-like pumping.Comment: 11 pages, 13 figures. arXiv admin note: text overlap with
arXiv:1610.0342
Locally Equivalent Correspondences
Given a pair of number fields with isomorphic rings of adeles, we construct
bijections between objects associated to the pair. For instance we construct an
isomorphism of Brauer groups that commutes with restriction. We additionally
construct bijections between central simple algebras, maximal orders, various
Galois cohomology sets, and commensurability classes of arithmetic lattices in
simple, inner algebraic groups. We show that under certain conditions, lattices
corresponding to one another under our bijections have the same covolume and
pro-congruence completion. We also make effective a finiteness result of Prasad
and Rapinchuk.Comment: Final Version. To appear in Ann. Inst. Fourie
Convergence in Income Inequality: Further Evidence from the Club Clustering Methodology across States in the U.S.
This paper contributes to the sparse literature on inequality convergence by empirically testing convergence across states in the U.S. This sample period encompasses a series of different periods that the existing literature discusses -- the Great Depression (1929–1944), the Great Compression (1945–1979), the Great Divergence (1980-present), the Great Moderation (1982–2007), and the Great Recession (2007–2009). This paper implements the relatively new method of panel convergence testing, recommended by Phillips and Sul (2007). This method examines the club convergence hypothesis, which argues that certain countries, states, sectors, or regions belong to a club that moves from disequilibrium positions to their club-specific steady-state positions. We find strong support for convergence through the late 1970s and early 1980s, and then evidence of divergence. The divergence, however, moves the dispersion of inequality measures across states only a fraction of the way back to their levels in the early part of the twentieth century
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