Thermodynamic and transport properties of superconducting Mg10B2

Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB2 superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, Hc2, with magnetization data giving dHc2/dT = 0.44 T/K at the transition temperature of Tc = 40.2 K. Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1 T. The value of dHc/dT at Tc is estimated to be about 12 mT/K, a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter kappa approximately 26. Estimates of the critical supercurrent density, Jc, using hysteresis loops and the Bean model, give critical current densities on the order of 10(5) A/cm2. Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb3Sn.     

EFFECT OF DIETARY LIPID ON UV LIGHT CARCINOGENESIS IN THE HAIRLESS MOUSE

Abstract— Isocaloric feeding of diets varying in lipid content to albino hairless mice has shown that their susceptibility to skin tumorigenesis induced by simulated solar UV light was not affected by the level of polyunsaturated fat, 5% or 20%. However a qualitative effect of dietary lipid was demonstrated. Mice fed 20% saturated fat were almost completely protected from UV tumorigenesis when compared with mice fed 20% polyunsaturated fat. Multiple latent tumours were detected in the saturated fat-fed mice by subsequent dietary replenishment, suggesting that a requirement for dietary unsaturated fat exists for the promotion stage of UV-induced skin carcinogenesis.     

Enumeration of connected invariant graphs

Let h be a finite group acting on unlabeled graphs which does not change connectivity. Examples include edge reversal in directed graphs and permutations of colors in edge and/or vertex colored graphs. The generating functions of h-invariant (directed) graphs and h-invariant (weakly) connected (directed) graphs are discussed. This leads to a recursive formula for calculating the number of connected graphs when the total number of graphs is known. This is then applied to self-dual signed graphs, self-converse digraphs, and color cyclic graphs. Asymptotic expansions are also obtained. As expected, almost all of the above h-invariant graphs are connected and the asymptotic number of disconnected graphs has a simple interpretation.     

Hook length products and Cayley operators of classical invariant theory

We show how hook length products of frames associated with integral partitions are involved in the evaluation of the Cayley operators of classical invariant theory. In this setting, hook length products play a more fundamental role than they do in the representation theory of the symmetric group. We give an elementary combinatorial argument which derives the result of Frame, Robinson and Thrall [2] concerning the dimensions of the irreducible representations of the symmetric group from these same general results of invariant theory.     

Remarks on an asymptotic method in combinatorics

The numerical problems involved in estimating the coefficients of a generating function w(z) which satisfies a functional equation F(z, w) = 0 are discussed. Particular attention is paid to algebraic functions.     

Fabrication and characterization of single-mode electro-optic polymer optical fiber

We report on what we believe is the first demonstration of single-mode polymer optical fiber with embedded electrodes. We show that the electrodes can be used to pole the dye-doped core and to electro-optically phase modulate the light in the waveguide.