Power operations and coactions in highly commutative homology theories

Power operations in the homology of infinite loop spaces, and H∞ or E∞ ring spectra have a long history in Algebraic Topology. In the case of ordinary mod p homology for a prime p, Dyer-Lashof operations interact with Steenrod operations via the Nishida relations, but for many purposes this leads to complicated calculations once iterated applications of these functions are required. On the other hand, the homology coaction turns out to provide tractable formulae better suited to exploiting multiplicative structure. We show how to derive suitable formulae for the interaction between power operations and homology coactions in a wide class of examples; our approach makes crucial use of modern frameworks for spectra with well behaved smash products. In the case of mod <i>p</i> homology, our formulae extend those of Bisson & Joyal to odd primes. We also show how to exploit our results in sample calculations, and produce some apparently new formulae for the Dyer-Lashof action on the dual Steenrod algebra

Common Medieval Pigments

This paper discusses the pigments used in medieval manuscripts. Specific types of pigments that are examined are earths, minerals, manufactured, and organics. It also focuses on both destructive and non-destructive methods for identifying medieval pigments

Approximate solutions for the single soliton in a Skyrmion-type model with a dilaton scalar field

We consider the analytical properties of the single-soliton solution in a Skyrmion-type Lagrangian that incorporates the scaling properties of quantum chromodynamics (QCD) through the coupling of the chiral field to a scalar field interpreted as a bound state of gluons. The model was proposed in previous works to describe the Goldstone pions in a dense medium, being also useful for studying the properties of nuclear matter and the in-medium properties of mesons and nucleons. Guided by an asymptotic analysis of the Euler-Lagrange equations, we propose approximate analytical representations for the single soliton solution in terms of rational approximants exponentially localized. Following the Pad\'e method, we construct a sequence of approximants from the exact power series solutions near the origin. We find that the convergence of the approximate representations to the numerical solutions is considerably improved by taking the expansion coefficients as free parameters and then minimizing the mass of the Skyrmion using our ans\"atze for the fields. We also perform an analysis of convergence by computation of physical quantities showing that the proposed analytical representations are very useful useful for phenomenological calculations.Comment: 13 pages, 3 eps figures, version to be published in Phys.Rev.

Galois theory and torsion points on curves

In this paper, we survey some Galois-theoretic techniques for studying torsion points on curves. In particular, we give new proofs of some results of A. Tamagawa and the present authors for studying torsion points on curves with "ordinary good" or "ordinary semistable" reduction at a given prime. We also give new proofs of: (1) The Manin-Mumford conjecture: There are only finitely many torsion points lying on a curve of genus at least 2 embedded in its Jacobian by an Albanese map; and (2) The Coleman-Kaskel-Ribet conjecture: If p is a prime number which is at least 23, then the only torsion points lying on the curve X_0(p), embedded in its Jacobian by a cuspidal embedding, are the cusps (together with the hyperelliptic branch points when X_0(p) is hyperelliptic and p is not 37). In an effort to make the exposition as useful as possible, we provide references for all of the facts about modular curves which are needed for our discussion.Comment: 18 page

A split finite element algorithm for the compressible Navier-Stokes equations

An accurate and efficient numerical solution algorithm is established for solution of the high Reynolds number limit of the Navier-Stokes equations governing the multidimensional flow of a compressible essentially inviscid fluid. Finite element interpolation theory is used within a dissipative formulation established using Galerkin criteria within the Method of Weighted Residuals. An implicit iterative solution algorithm is developed, employing tensor product bases within a fractional steps integration procedure, that significantly enhances solution economy concurrent with sharply reduced computer hardware demands. The algorithm is evaluated for resolution of steep field gradients and coarse grid accuracy using both linear and quadratic tensor product interpolation bases. Numerical solutions for linear and nonlinear, one, two and three dimensional examples confirm and extend the linearized theoretical analyses, and results are compared to competitive finite difference derived algorithms