Resistance and relief: The wit and woes of early twentieth century folk and country music

This is the publisher's version, also available electronically from http://www.degruyter.com/view/j/humr.2010.23.issue-2/humr.2010.008/humr.2010.008.xml.Folk and country music were rural-based music styles that developed during the pre-rock decades of the early twentieth century. Largely performed by working-class practitioners for working-class audiences, these genres captured the hardships of poor constituencies through markedly different means of humorous expression. Whereas folk employed an often strident satire in resisting perceived oppressors, country looked inwards, using self-deprecating and personalized humor as a shield and relief against outside forces. Narrative tall-tales and regional vernacular were ubiquitous features of folk and country humor, and both crafted struggling characters to serve as illustrative metaphors for broader class concerns. In surveying these music forms in their infancy—as well as their key players—we are connected to the roots of American humor, as well as subsequent developments in rock & roll rebellion

A Penrose polynomial for embedded graphs

We extend the Penrose polynomial, originally defined only for plane graphs, to graphs embedded in arbitrary surfaces. Considering this Penrose polynomial of embedded graphs leads to new identities and relations for the Penrose polynomial which can not be realized within the class of plane graphs. In particular, by exploiting connections with the transition polynomial and the ribbon group action, we find a deletion-contraction-type relation for the Penrose polynomial. We relate the Penrose polynomial of an orientable checkerboard colourable graph to the circuit partition polynomial of its medial graph and use this to find new combinatorial interpretations of the Penrose polynomial. We also show that the Penrose polynomial of a plane graph G can be expressed as a sum of chromatic polynomials of twisted duals of G. This allows us to obtain a new reformulation of the Four Colour Theorem

A note on recognizing an old friend in a new place:list coloring and the zero-temperature Potts model

Here we observe that list coloring in graph theory coincides with the zero-temperature antiferromagnetic Potts model with an external field. We give a list coloring polynomial that equals the partition function in this case. This is analogous to the well-known connection between the chromatic polynomial and the zero-temperature, zero-field, antiferromagnetic Potts model. The subsequent cross fertilization yields immediate results for the Potts model and suggests new research directions in list coloring

Separability and the genus of a partial dual

Partial duality generalizes the fundamental concept of the geometric dual of an embedded graph. A partial dual is obtained by forming the geometric dual with respect to only a subset of edges. While geometric duality preserves the genus of an embedded graph, partial duality does not. Here we are interested in the problem of determining which edge sets of an embedded graph give rise to a partial dual of a given genus. This problem turns out to be intimately connected to the separability of the embedded graph. We determine how separability is related to the genus of a partial dual. We use this to characterize partial duals of graphs embedded in the plane, and in the real projective plane, in terms of a particular type of separation of an embedded graph. These characterizations are then used to determine a local move relating all partially dual graphs in the plane and in the real projective plane

Systematic Improvement of Parton Showers with Effective Theory

We carry out a systematic classification and computation of next-to-leading order kinematic power corrections to the fully differential cross section in the parton shower. To do this we devise a map between ingredients in a parton shower and operators in a traditional effective field theory framework using a chain of soft-collinear effective theories. Our approach overcomes several difficulties including avoiding double counting and distinguishing approximations that are coordinate choices from true power corrections. Branching corrections can be classified as hard-scattering, that occur near the top of the shower, and jet-structure, that can occur at any point inside it. Hard-scattering corrections include matrix elements with additional hard partons, as well as power suppressed contributions to the branching for the leading jet. Jet-structure corrections require simultaneous consideration of potential 1 -> 2 and 1 -> 3 branchings. The interference structure induced by collinear terms with subleading powers remains localized in the shower.Comment: 54 pages, 24 figures, plus a few appendices. v2: included a parameter "eta" to account for energy loss, title improved, journal versio

Connecting fish, flows and habitats on lowland river floodplains

Connectivity between river and floodplain habitats is important to many lowland river fishes enabling them to complete their life cycle, maximise growth potential and minimise early life-history mortality. There is increasing recognition of this need and in regulated systems, increasing sophistication of management processes and infrastructure around environmental water allocations to facilitate this connectivity. Providing connecting flows with limited water resources often means prioritising watering one area over another; so comparative evaluation of fish movement, growth and productivity can be important to demonstrate success. In the Great Darling Anabranch, we used directional-netting, measures of whole stream productivity and fish otolith growth and body condition analysis to investigate benefits of connecting flows in 500km of restored ephemeral river channel alongside the same factors in an alternative flow-path, the Darling River. The Hattah Lakes, a complex of regulated, lowland-river floodplain lakes can be filled using large, purpose built environmental pumps; transferring water and fish recruits from the Murray River to productive floodplain habitats. We investigated the lateral movement of resident fish during filling and draw-down of the lakes, using acoustic tags in a native fish species, Golden perch (Macquaria ambigua) and an invasive fish, Carp (Cyprinus carpio). We generated regular movement-trajectories for tagged fish using interpolation, then tested observations against null models to evaluate individual and group movements against a one-dimensional behavioural hypothesis; “do fish move towards or away from the river in response to draw-down or filling?” Results are assisting natural resource managers develop designs for environmental watering hydrographs for connecting flows in large anabranch channels and floodplain lakes

The Las Vergnas Polynomial for embedded graphs

The Las Vergnas polynomial is an extension of the Tutte polynomial to cellularly embedded graphs. It was introduced by Michel Las Vergnas in 1978 as special case of his Tutte polynomial of a morphism of matroids. While the general Tutte polynomial of a morphism of matroids has a complete set of deletion-contraction relations, its specialisation to cellularly embedded graphs does not. Here we extend the Las Vergnas polynomial to graphs in pseudo-surfaces. We show that in this setting we can define deletion and contraction for embedded graphs consistently with the deletion and contraction of the underlying matroid perspective, thus yielding a version of the Las Vergnas polynomial with complete recursive definition. This also enables us to obtain a deeper understanding of the relationships among the Las Vergnas polynomial, the Bollobas-Riordan polynomial, and the Krushkal polynomial. We also take this opportunity to extend some of Las Vergnas' results on Eulerian circuits from graphs in surfaces of low genus to surfaces of arbitrary genus