Theories of species coexistence have played a central role in ecology and evolutionary studies of the origin and maintenance of biodiversity in highly diverse communities. The concept of niche and associated theories predict that competition for available ecological space leads to a ceiling in species richness that influences further diversification patterns. By contrast, the neutral theory sup...

The effectiveness of humanitarian programs normally is evaluated according to a limited number of pre-defined objectives. These objectives typically represent only selected positive expected impacts of program interventions and as such, are inadequate benchmarks for understanding the overall effectiveness of aid. This is because programs also have unexpected impacts (both positive and negative)...

This paper identifies two distinct types of payoff kinks that can be exhibited by preference functions over monetary lotteries—“locally separable” vs. “locally nonseparable”—and illustrates their relationship to the payoff and probability derivatives of such functions. Expected utility and Fréchet differentiable preference functions are found to be incapable of exhibiting locally nonseparable p...

Technology has the potential to impact cognition in many ways. Here we contrast two forms of technology usage: (1) media multitasking (i.e., the simultaneous consumption of multiple streams of media, such a texting while watching TV) and (2) playing action video games (a particular subtype of video games). Previous work has outlined an association between high levels of media multitasking and s...

The effect of quenched impurities on systems which undergo first-order phase transitions is studied within the framework of the q-state Potts model. For large q a mapping to the random field Ising model is introduced which provides a simple physical explanation of the absence of any latent heat in 2D, and suggests that in higher dimensions such systems should exhibit a tricritical point with a ...