Anomaly/Transport in an Ideal Weyl gas

We study some of the transport processes which are specific to an ideal gas of relativistic Weyl fermions and relate the corresponding transport coefficients to various anomaly coefficients of the system. We propose that these transport processes can be thought of as arising from the continuous injection of chiral states and their subsequent adiabatic flow driven by vorticity. This in turn leads to an elegant expression relating the anomaly induced transport coefficients to the anomaly polynomial of the Ideal Weyl gas.Comment: 35 pages, JHEP forma

The Logic of Fashion Cycles

Many cultural traits exhibit volatile dynamics, commonly dubbed fashions or fads. Here we show that realistic fashion-like dynamics emerge spontaneously if individuals can copy others' preferences for cultural traits as well as traits themselves. We demonstrate this dynamics in simple mathematical models of the diffusion, and subsequent abandonment, of a single cultural trait which individuals may or may not prefer. We then simulate the coevolution between many cultural traits and the associated preferences, reproducing power-law frequency distributions of cultural traits (most traits are adopted by few individuals for a short time, and very few by many for a long time), as well as correlations between the rate of increase and the rate of decrease of traits (traits that increase rapidly in popularity are also abandoned quickly and vice versa). We also establish that alternative theories, that fashions result from individuals signaling their social status, or from individuals randomly copying each other, do not satisfactorily reproduce these empirical observations

Rapid cultural adaptation can facilitate the evolution of large-scale cooperation

Over the past several decades, we have argued that cultural evolution can facilitate the evolution of large-scale cooperation because it often leads to more rapid adaptation than genetic evolution, and, when multiple stable equilibria exist, rapid adaptation leads to variation among groups. Recently, Lehmann, Feldman, and colleagues have published several papers questioning this argument. They analyze models showing that cultural evolution can actually reduce the range of conditions under which cooperation can evolve and interpret these models as indicating that we were wrong to conclude that culture facilitated the evolution of human cooperation. In the main, their models assume that rates of cultural adaption are not strong enough compared to migration to maintain persistent variation among groups when payoffs create multiple stable equilibria. We show that Lehmann et al. reach different conclusions because they have made different assumptions. We argue that the assumptions that underlie our models are more consistent with the empirical data on large-scale cultural variation in humans than those of Lehmann et al., and thus, our models provide a more plausible account of the cultural evolution of human cooperation in large groups

The Role of Handwashing in Prevention of Endemic Intensive Care Unit Infections

AbstractHandwashing is believed to be the most important means of preventing nosocomial infections. Previous studies of healthcare workers (HCWs) have shown that handwashing practices are poor. No one has shown that handwashing practices can be easily improved and that this prevents endemic (non-epidemic) nosocomial infection. Handwashing and infection rates were studied in two intensive care units (ICUs) of a community teaching hospital. Handwashing rates were monitored secretly throughout the study. After six months of observation, we started interventions to increase handwashing. Handwashing increased gradually, but overall rates before (22.0%) and after (29.9%) interventions were not significantly different (p = .071). Handwashing never occurred before intravenous care, whereas it occurred 67.5% for all other indications (p<.0001). When questioned, nurses felt they were washing appropriately nearly 90% of the time. Infection rates seemed unrelated to handwashing throughout the study, and no clusters of infection were detected. We conclude that handwashing rates, when measured against arbitrary but reasonable standards, are suboptimal, difficult to change and not closely related to evidence of cross-infection. Further, nurses wash hands selectively, depending on the indication for handwashing, and generally believe they are washing much more frequently than an objective observer believes they are

Classic Maya Bloodletting and the Cultural Evolution of Religious Rituals: Quantifying Patterns of Variation in Hieroglyphic Texts

Religious rituals that are painful or highly stressful are hypothesized to be costly signs of commitment essential for the evolution of complex society. Yet few studies have investigated how such extreme ritual practices were culturally transmitted in past societies. Here, we report the first study to analyze temporal and spatial variation in bloodletting rituals recorded in Classic Maya (ca. 250–900 CE) hieroglyphic texts. We also identify the sociopolitical contexts most closely associated with these ancient recorded rituals. Sampling an extensive record of 2,480 hieroglyphic texts, this study identifies every recorded instance of the logographic sign for the word ch’ahb’ that is associated with ritual bloodletting. We show that documented rituals exhibit low frequency whose occurrence cannot be predicted by spatial location. Conversely, network ties better capture the distribution of bloodletting rituals across the southern Maya region. Our results indicate that bloodletting rituals by Maya nobles were not uniformly recorded, but were typically documented in association with antagonistic statements and may have signaled royal commitments among connected polities

Quality versus mere popularity: a conceptual map for understanding human behavior

Cultural transmission, Evolution, Pattern formation, Popularity, Social learning,

Simulating geographical variation in material culture : were Early Modern Humans in Europe ethnically structured ?

International audienc