We investigate the relationship between controversial roll call votes and support for Democratic incumbents in the 2010 midterm elections. Consistent with previous analyses, we find that supporters of health care reform paid a significant price at the polls. We go beyond these analyses by identifying a mechanism for this apparent effect: constituents perceived incumbents who supported health care reform as more ideologically distant (in this case, more liberal), which in turn was associated with lower support for those incumbents. Our analyses show that this perceived ideological difference mediates most of the apparent impact of support for health care reform on both individual-level vote choice and aggregate-level vote share. We conclude by simulating counterfactuals that suggest health care reform may have cost Democrats their House majority.

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Health and physiology are critically dependent on the ability of soft, permeable, and aqueous materials (e.g. cartilage, cells, and extracellular matrix) to provide lubrication over a wide range of speeds and contact stresses. Living cells and tissues present tremendous handling and experimental challenges for fundamental biotribology studies. Synthetic high water content hydrogels, designed to share similar mechanical and transport properties of biomaterials, can provide fundamental insights into the basic dissipative mechanisms associated with aqueous lubrication. Recent studies investigating the response of self-mated (Gemini) hydrogels to a wide range of sliding speeds under constant load conditions revealed transitions in friction behavior that may be associated with polymer relaxation time and contact time for a surface mesh during sliding (mesh size divided by the sliding speed). Here, the extent to which contact pressure and contact area affect hydrogel friction behavior was explored by changing the applied load over two orders of magnitude (0.1-20 mN) and the sliding speed over four orders of magnitude (10 m/s-100 mm/s). Oscillating pin-on-disk microtribological experiments were performed in ultrapure water for Gemini polyacrylamide hydrogels (average mesh size ~7 nm). Friction coefficient decreased across all ranges of sliding speed with increasing applied load, consistent with predictions of contact area scaling non-linearly with applied load and pressureindependent surface shear stresses. The contact area for Gemini hydrogel interfaces under these conditions has been shown to follow Hertzian contact mechanics theory, and supports the scaling of friction coefficient in the speed-independent regime that follows ~ Fn −1/3 .

In recent decades, the literature has coalesced around either symmetry or responsiveness as measures of partisan bias in single‐member district systems. I argue neither accurately captures the traditional idea of an “efficient” gerrymander, where one party claims more seats without more votes. I suggest a better measure of efficiency and then use this new measure to reconsider a classic study of partisan gerrymandering. Contrary to the original study findings, I show that the effects of party control on bias are small and decay rapidly, suggesting that redistricting is at best a blunt tool for promoting partisan interests.