The Transference Numbers and the Degree of Solvation of the Ions of Lithium Chloride in Certain Alcohols

The low migration velocities of some of the ions of the elements of low atomic weight, as well as the many other phenomena that are not explained by simple electrolytic dissociation, have led to the belief that the ion does not lead an independent existence in the solution, but is solvated, or combined chemically with one or more molecules of the solvent

Internal U, Th and Rb concentrations of alkali-feldspar grains:Implications for luminescence dating

This study assesses whether internal U, Th and Rb concentrations of single grains of alkali-feldspar can impact upon luminescence dating. Internal alpha dose-rates determined for two sedimentary samples calculated from mean U and Th concentrations accounted for ∼10% of the total dose-rates, while internal beta dose-rates from mean Rb concentrations accounted for ∼2%. Depth profiles of measurements penetrating into each grain show that internal U and Th concentrations varied between grains, where some grains had effective internal alpha dose-rates up to 1.8 Gy/ka (32% of the total dose-rate). K concentrations inferred from Rb (KRb) for individual grains suggest that internal U and Th concentrations are related to the feldspar composition. Grains with KRb > 6% had low U and Th, and grains with KRb < 6% had higher U and Th concentrations. Internal alpha and beta dose-rates of the perthitic and Na-rich grains contaminating the density-separated K-feldspar fractions had a significant impact upon the single-grain De distributions, which was estimated to be equivalent to overdispersion values of ∼10 – 15%. The scatter in the De distributions arising from internal alpha and beta dose-rates for both samples could be reduced by selecting only the brightest 20% of grains for luminescence dating

Can Light Echoes Account for the Slow Decay of Type IIn Supernovae?

The spectra of type IIn supernovae indicate the presence of apre-existing slow, dense circumstellar wind (CSW). If the CSW extends sufficiently far from the progenitor star, then dust formation should occur in the wind. The light from the supernova explosion will scatter off this dust and produce a light echo. Continuum emission seen after the peak will have contributions from both this echo as well as from the shock of the ejecta colliding with the CSW, with a fundamental question of which source dominates the continuum. We calculate the brightness of the light echo as a function of time for a range of dust shell geometries, and use our calculations to fit to the light curves of SN 1988Z and SN 1997ab, the two slowest declining IIn supernovae on record. We find that the light curves of both objects can be reproduced by the echo model. However, their rate of decay from peak, color at peak and their observed peak absolute magnitudes when considered together are inconsistent with the echo model. Furthermore, when the observed values of M$_{B}$ are corrected for the effects of dust scattering, the values obtained imply that these supernovae have unrealistically high luminosities. We conclude that light echoes cannot properly account for the slow decline seen in some IIn's, and that the shock interaction is likely to dominate the continuum emission.Comment: 15 pages, 9 figure

Refined conformal spectra in the dimer model

Working with Lieb's transfer matrix for the dimer model, we point out that the full set of dimer configurations may be partitioned into disjoint subsets (sectors) closed under the action of the transfer matrix. These sectors are labelled by an integer or half-integer quantum number we call the variation index. In the continuum scaling limit, each sector gives rise to a representation of the Virasoro algebra. We determine the corresponding conformal partition functions and their finitizations, and observe an intriguing link to the Ramond and Neveu-Schwarz sectors of the critical dense polymer model as described by a conformal field theory with central charge c=-2.Comment: 44 page

Wind on the boundary for the Abelian sandpile model

We continue our investigation of the two-dimensional Abelian sandpile model in terms of a logarithmic conformal field theory with central charge c=-2, by introducing two new boundary conditions. These have two unusual features: they carry an intrinsic orientation, and, more strangely, they cannot be imposed uniformly on a whole boundary (like the edge of a cylinder). They lead to seven new boundary condition changing fields, some of them being in highest weight representations (weights -1/8, 0 and 3/8), some others belonging to indecomposable representations with rank 2 Jordan cells (lowest weights 0 and 1). Their fusion algebra appears to be in full agreement with the fusion rules conjectured by Gaberdiel and Kausch.Comment: 26 pages, 4 figure

On the structure of the scalar mesons f0(975)f_0(975) and a0(980)a_0(980)

We investigate the structure of the scalar mesons $f_0(975)$ and $a_0(980)$ within realistic meson-exchange models of the $\pi\pi$ and $\pi\eta$ interactions. Starting from a modified version of the J\"ulich model for $\pi\pi$ scattering we perform an analysis of the pole structure of the resulting scattering amplitude and find, in contrast to existing models, a somewhat large mass for the $f_0(975)$ ($m_{f_0}=1015$ MeV, $\Gamma_{f_0}=30$ MeV). It is shown that our model provides a description of $J/\psi\rightarrow\phi\pi\pi/\phi KK$ data comparable in quality with those of alternative models. Furthermore, the formalism developed for the $\pi\pi$ system is consistently extended to the $\pi\eta$ interaction leading to a description of the $a_0(980)$ as a dynamically generated threshold effect (which is therefore neither a conventional $q\overline{q}$ state nor a $K\overline{K}$ bound state). Exploring the corresponding pole position the $a_0(980)$ is found to be rather broad ($m_{a_0}=991$ MeV, $\Gamma_{a_0}=202$ MeV). The experimentally observed smaller width results from the influence of the nearby $K\overline{K}$ threshold on this pole.Comment: 25 pages, 15 Postscript figure