Spinor fields without Lorentz frames in curved spacetime using complexified quaternions

Using complexified quaternions, a formalism without Lorentz frames, and therefore also without vierbeins, for dealing with tensor and spinor fields in curved spacetime is presented. A local U(1) gauge symmetry, which, it is speculated, might be related to electromagnetism, emerges naturally.Comment: 14 pages; v2: minor corrections; v3: note added concerning unified treatment of local Lorentz transformations and local U(1) gauge transformations; v4: published in J. Math. Phys. 50 083507 (2009

The String Coupling Accelerates the Expansion of the Universe

Generic cosmological models in non-critical string theory have a time-dependent dilaton background at a late epoch. The cosmological deceleration parameter Q_0 is given by the square of the string coupling, g_s^2, up to a negative sign. Hence the expansion of the Universe must accelerate eventually, and the observed value of Q_0 coresponds to g_s^2 ~ 0.6. In this scenario, the string coupling is asymptotically free at large times, but its present rate of change is imperceptibly small.Comment: 7 page

Multiparty Politics in America (First Edition)

In the wake of Ross Perot, Ralph Nader, and other third party and independent candidates that ran in the 1996 election, this collection of original essays by leading political scientists and third party officials is must reading for individuals interested in American politics. Multiparty Politics in America examines the roles that third parties have played in U.S. elections past and present and their prospects for the future. It presents unique and detailed coverage of the Reform, Green, and Libertarian parties\u27 goals and campaign strategies; discusses the kinds of reforms that would help them become more viable; and advances the debate over whether the U.S. should have a two-party or multiparty system.https://ideaexchange.uakron.edu/multiparty_politics1/1000/thumbnail.jp

The X-ray Iron Emission from Tycho's Supernova Remnant

We present the results of broadband fits to the X-ray spectrum of Tycho's supernova remnant obtained by the Solid-State Imaging Spectrometers on the ASCA Observatory. We use single-temperature, single-ionization-age, nonequilibrium ionization models to characterize the ejecta and the blast-shocked interstellar medium. Based on the Fe K emission at 6.5 keV, previous spectral studies have suggested that the Fe ejecta in this Type Ia remnant are stratified interior to the other ejecta. The ASCA data provide important constraints from the Fe L emission near 1 keV as well as the Fe K emission. We find that the simplest models, with emission from the ejecta and blast wave each at a single temperature and ionization age, severely underestimate the Fe K flux. We show that there is little Fe emission associated with the Si and S ejecta shell. The blast-shocked interstellar medium has abundances roughly 0.3 times the solar value, while the ejecta, with the exception of Fe, have relative abundances that are typical of Type Ia supernovae. The addition of another component of Fe emission, which we associate with ejecta, at a temperature at least two times higher and an ionization age $\sim$ 100 times lower than the Si ejecta, does provide a good fit to the spectrum. This model is consistent with X-ray imaging results. Although fluorescent emission from dust in the remnant may contribute to the Fe K flux, we conclude that it is unlikely to dominate.Comment: 23 pages, LaTex; 4 postscript figures, 2 postscript tables. To appear in ApJ, vol 49

Open problems in artificial life

This article lists fourteen open problems in artificial life, each of which is a grand challenge requiring a major advance on a fundamental issue for its solution. Each problem is briefly explained, and, where deemed helpful, some promising paths to its solution are indicated

Hemiparasitic plant impacts animal and plant communities across four trophic levels

1.Understanding the impact of species on community structure is a fundamental question in ecology. There is a growing body of evidence that suggests that both sub-dominant species and parasites can have a disproportionately large impact. 2.Here we report the impacts of an organism that is both subdominant and parasitic, the hemiparasite Rhinanthus minor. Whilst the impact of parasitic angiosperms on their hosts and, to a lesser degree, co-existing plant species, have been well characterized, much less is known about their impacts on higher trophic levels. 3.We experimentally manipulated field densities of the hemiparasite Rhinanthus minor in a species rich grassland, comparing the plant and invertebrate communities in plots where it was removed, at natural densities or at enhanced densities. 4.Plots with natural and enhanced densities of R. minor had lower plant biomass than plots without the hemiparasite, but enhanced densities almost doubled the abundance of invertebrates within the plots across all trophic levels, with effects evident in herbivores, predators and detritivores. 5.The hemiparasite R. minor, despite being a sub-dominant and transient component within plant communities that it inhabits, has profound effects on four different trophic levels. These effects persist beyond the life of the hemiparasite, emphasizing its role as a keystone species in grassland communitie

A new mechanism for exchange processes observed in the compounds [M(η-C_5H_5)_2(exo-η-RCH = CH_2)H], M = Nb and Ta

Dynamic n.m.r. studies of the exchange processes in the complexes [M(η-C_5H_5)(exo-η-RCH=CH_2)H], M = Nb, Ta, lead to the proposal of a new mechanism involving intermediates with agostic bonding

Geology of the Lower Paleozoic Rocks in the Boundary Mountain Anticlinorium

Guidebook for field trips in the Rangeley Lakes - Dead River Basin region, western Maine: 62nd annual meeting October 2, 3, and 4, 1970: Trip A-

The Statistical Mechanical Theory of Transport Processes. III. The Coefficients of Shear and Bulk Viscosity of Liquids

A molecular theory of the coefficients of shear and bulk viscosity of monatomic liquids is developed on the basis of the general theory of transport processes presented in the first article of this series. With the use of the Lennard-Jones potential and a reasonable analytic approximation to the experimental radial distribution function, calculations of the coefficients of shear and bulk viscosity of liquid argon at 89°K have been carried out. The theory leads explicitly to ratios of the coefficients to the friction constant of the theory of Brownian motion. With a preliminary estimate of the friction constant, a value of the shear viscosity of liquid argon in moderately good agreement with experiment is obtained

The Journal of the Friends' Historical Society volume 1, no. 1

1. Foreword 2. Notes and Queries 3. The Handwriting of George Fox (illustrated) By Isaac Sharp, B.A. 4. Grangerised Books By The Editors 5. Our Recording Clerks: I. Ellis HookesBy Norman Penney 6. The Case of William Gibson (illustrated) By The Editor 7. Two Quotations in the London Y.M. Epistle, 1903 By The Editors 8. The Quaker Family of Owen I By Joseph J. Green 9. Letters of Wm. Dewsbury and John Whitehead By The Editors 10. Friends' Reference Library, Devonshire House 11. Book Notes By Norman Penney 12. List of Member