The Pagoda Sequence: a Ramble through Linear Complexity, Number Walls, D0L Sequences, Finite State Automata, and Aperiodic Tilings

We review the concept of the number wall as an alternative to the traditional linear complexity profile (LCP), and sketch the relationship to other topics such as linear feedback shift-register (LFSR) and context-free Lindenmayer (D0L) sequences. A remarkable ternary analogue of the Thue-Morse sequence is introduced having deficiency 2 modulo 3, and this property verified via the re-interpretation of the number wall as an aperiodic plane tiling

The Origin and Shaping of Planetary Nebulae: Putting the Binary Hypothesis to the Test

Planetary nebulae (PNe) are circumstellar gas ejected during an intense mass-losing phase in the the lives of asymptotic giant branch stars. PNe have a stunning variety of shapes, most of which are not spherically symmetric. The debate over what makes and shapes the circumstellar gas of these evolved, intermediate mass stars has raged for two decades. Today the community is reaching a consensus that single stars cannot trivially manufacture PNe and impart to them non spherical shapes and that a binary companion, possibly even a sub-stellar one, might be needed in a majority of cases. This theoretical conjecture has however not been tested observationally. In this review we discuss the problem both from the theoretical and observational standpoints, explaining the obstacles that stand in the way of a clean observational test and ways to ameliorate the situation. We also discuss indirect tests of this hypothesis and its implications for stellar and galactic astrophysics.Comment: 28 pages of text. 4 tables 9 figures. Accepted by PASP Review

Ricardo Diaz - Latino/a Mass Incarceration in relation to the “War on Drugs”

Michelle Alexander, in The New Jim Crow, argues that the American legal system is a racial caste system maintained by unequal drug laws, what she terms, “The New Jim Crow” laws. This essay explores the limits of her thesis in relation to Latino/a population in the United States. Specific attention is paid to the Latino/a population in Wisconsin where racial disparities in the penal system are the greatest in America. Analysis of government data suggests that Alexander’s research reproduces the tendency of the American legal system to define race in binary terms: black and white. In effect this leaves Latino/a Americans without accurate representation within the American legal system.https://epublications.marquette.edu/mcnair_2013/1001/thumbnail.jp