Contact Line Dynamics during the Evaporation of Extended Colloidal Thin Films: Influence of Liquid Polarity and Particle Size.

Exercising control over the evaporation of colloidal suspensions is pivotal to modulate the coating characteristics for specific uses, wherein the interactions among the liquid, the particles, and the substrate control the process. In the present study, the contact line dynamics of a receding colloidal liquid film consisting of particles of distinctly different sizes (nominal diameters 0.055 and 1 µm and surface unmodified) during evaporation is analyzed. The role of the liquid polarity is also investigated by replacing the polar liquid (water) with a relatively nonpolar liquid (isopropyl alcohol) in the colloidal suspension. The characteristics of the evaporating receding meniscus, namely, the film thickness and the curvature are experimentally evaluated using an image-analyzing interferometry technique. The experimental results are assessed in conjunction with the augmented Young-Laplace equation, highlighting the roles of the relevant components of the disjoining pressure and the polarity of the liquid involved in the colloidal suspension.

The loosening of American culture over 200 years is associated with a creativity-order trade-off.

For many years, scientists have studied culture by comparing societies, regions or social groups within a single point in time. However, culture is always changing, and this change affects the evolution of cognitive processes and behavioural practices across and within societies. Studies have now documented historical changes in sexism1, individualism2,3, language use4 and music preferences5 within the United States and around the world6. Here we build on these efforts by examining changes in cultural tightness-looseness (the strength of cultural norms and tolerance for deviance) over time, using the United States as a case study. We first develop a new linguistic measure to measure historical changes in tightness-looseness. Analyses show that America grew progressively less tight (i.e., looser) from 1800 to 2000. We next examine how changes in tightness-looseness relate to four indicators of societal order: debt (adjusted for inflation), adolescent pregnancies and crime, and high school attendance, as well as four indicators of creative output: registered patents, trademarks, feature films produced, and baby-naming conformity. We find that cultural tightness correlates negatively with each measure of creativity, and correlates positively with three out of four measures of societal order (fewer adolescent pregnancies, less debt and higher levels of school attendance). These findings imply that the historical loosening of American culture was associated with a trade-off between higher creativity but lower order.

Publisher Correction: The loosening of American culture over 200 years is associated with a creativity-order trade-off.

In the version of this article initially published, errors appeared in three sentences. In the abstract, the sentence beginning "We next examine" should have read "adolescent pregnancies, crime, and high school attendance"; in the main text, the sentence beginning "More recently, the 1964 Civil Rights Act" should have read "directly challenged the authority of the government" and the sentence beginning "Notably, cultural tightness" should have read "cultural tightness positively correlated with crime". The errors have been corrected in the HTML and PDF versions of the article.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The Inevitability of Ethnocentrism Revisited: Ethnocentrism Diminishes As Mobility Increases.

Nearly all major conflicts across the globe, both current and historical, are characterized by individuals defining themselves and others by group membership. This existence of group-biased behavior (in-group favoring and out-group hostile) has been well established empirically, and has been shown to be an inevitable outcome in many evolutionary studies. Thus it is puzzling that statistics show violence and out-group conflict declining dramatically over the past few centuries of human civilization. Using evolutionary game-theoretic models, we solve this puzzle by showing for the first time that out-group hostility is dramatically reduced by mobility. Technological and societal advances over the past centuries have greatly increased the degree to which humans change physical locations, and our results show that in highly mobile societies, one's choice of action is more likely to depend on what individual one is interacting with, rather than the group to which the individual belongs. Our empirical analysis of archival data verifies that contexts with high residential mobility indeed have less out-group hostility than those with low mobility. This work suggests that, in fact, group-biased behavior that discriminates against out-groups is not inevitable after all.