Narrative Strategies in Benedikte Naubert's Neue Volksmarchen der Deutschen

No abstract available

The slopes determined by n points in the plane

Let $m_{12}$, $m_{13}$, ..., $m_{n-1,n}$ be the slopes of the $\binom{n}{2}$ lines connecting $n$ points in general position in the plane. The ideal $I_n$ of all algebraic relations among the $m_{ij}$ defines a configuration space called the {\em slope variety of the complete graph}. We prove that $I_n$ is reduced and Cohen-Macaulay, give an explicit Gr\"obner basis for it, and compute its Hilbert series combinatorially. We proceed chiefly by studying the associated Stanley-Reisner simplicial complex, which has an intricate recursive structure. In addition, we are able to answer many questions about the geometry of the slope variety by translating them into purely combinatorial problems concerning enumeration of trees.Comment: 36 pages; final published versio

Geometry of graph varieties

A picture P of a graph G = (V,E) consists of a point P(v) for each vertex v in V and a line P(e) for each edge e in E, all lying in the projective plane over a field k and subject to containment conditions corresponding to incidence in G. A graph variety is an algebraic set whose points parametrize pictures of G. We consider three kinds of graph varieties: the picture space X(G) of all pictures, the picture variety V(G), an irreducible component of X(G) of dimension 2|V|, defined as the closure of the set of pictures on which all the P(v) are distinct, and the slope variety S(G), obtained by forgetting all data except the slopes of the lines P(e). We use combinatorial techniques (in particular, the theory of combinatorial rigidity) to obtain the following geometric and algebraic information on these varieties: (1) a description and combinatorial interpretation of equations defining each variety set-theoretically; (2) a description of the irreducible components of X(G); and (3) a proof that V(G) and S(G) are Cohen-Macaulay when G satisfies a sparsity condition, rigidity independence. In addition, our techniques yield a new proof of the equality of two matroids studied in rigidity theory.Comment: 19 pages. To be published in Transactions of the AM

Kinematic Evidence for Superbubbles in I Zw 18: Constraints on the Star Formation History and Chemical Evolution

We have combined measurements of the kinematics, morphology, and oxygen abundance of the ionized gas in \IZw18, one of the most metal-poor galaxies known, to examine the star formation history and chemical mixing processes.Comment: 31 pages including 6 figures. Accepted for publication in the Astrophysical Journa

The Possible Detection of Dark Energy on Earth Using Atom Interferometry

This paper describes the concept and the beginning of an experimental investigation of whether it is possible to directly detect dark energy density on earth using atom interferometry. The concept is to null out the gravitational force using a double interferometer. This research provides a non-astronomical path for research on dark energy. The application of this method to other hypothetical weak forces and fields is also discussed. In the the final section I discuss the advantages of carrying out a dark energy density search in a satellite in earth orbit where more precise nulling of gravitational forces can be achieved

African and Pac!fic Literature: A Comparative Study

The new nations of Africa and the islands of the South Pacific have much in common, despite their ethnic and cultural diversity and the vast distance that separates them. The literature which has developed over the past thirty years in Africa and over the past ten in the Pacific mirrors their shared experiences and outlook. The authors from both regions have acted as spokespersons for their people, voicing concerns about their future as individuals as well as members of a politically viable ethnic community