Not Very Far, But Not Close Either

In “Not Very Far, But Not Close Either”, formal lyrics, free verse poems, and translations from the first century Latin of Martial and Horace explore ideas of distance: the physical distance between bodies, the psychological distance between (and within) human minds, the temporal distance between past, present, and future. A speaker considers his relationship to the image in a foggy bathroom mirror, another to the bird living behind his house, another to the ghosts of his dead parents, whom he asks to watch over a beloved and recently departed child. In exploring these distances—between self and semblance, man and bird, living and dead—the speakers of these poems attempt to locate themselves the only way we can ever locate anything: in relation to something—or someone—else. In this spirit, the manuscript incorporates not only translations and original poems, but poems adapted from and taken after the work of poets who have explored similar themes, questions, and concerns.

Phase transitions in gene networks evolved under different selection rules

Mathematical models of gene regulation are a powerful tool for understanding the complex features of genetic control. While various modeling efforts have been successful at explaining gene expression dynamics, much less is known about how evolution shapes the structure of these networks. An important feature of gene regulatory networks is their stability in response to environmental perturbations. Regulatory systems are thought to have evolved to exist near the transition between stability and instability, in order to have the required stability to environmental fluctuations while also being able to achieve a wide variety of functions (corresponding to different dynamical patterns). We study a simplified model of gene network evolution in which links are added via different selection rules. These growth models are inspired by recent work on `explosive' percolation which shows that when network links are added through competitive rather than random processes, the connectivity phase transition can be significantly delayed, and when it is reached, it appears to be first order (discontinuous, e.g., going from no failure at all to large expected failure) instead of second order (continuous, e.g., going from no failure at all to very small expected failure). We find that by modifying the traditional framework for networks grown via competitive link addition to capture how gene networks evolve to avoid damage propagation, we also see significant delays in the transition that depend on the selection rules, but the transitions always appear continuous rather than `explosive'.