Comparative Analysis of the Major Polypeptides from Liver Gap Junctions and Lens Fiber Junctions

Gap junctions from rat liver and fiber junctions from bovine lens have similar septilaminar profiles when examined by thin-section electron microscopy and differ only slightly with respect to the packing of intramembrane particles in freeze-fracture images. These similarities have often led to lens fiber junctions being referred to as gap junctions. Junctions from both sources were isolated as enriched subcellular fractions and their major polypeptide components compared biochemically and immunochemically. The major liver gap junction polypeptide has an apparent molecular weight of 27,000, while a 25,000-dalton polypeptide is the major component of lens fiber junctions. The two polypeptides are not homologous when compared by partial peptide mapping in SDS. In addition, there is not detectable antigenic similarity between the two polypeptides by immunochemical criteria using antibodies to the 25,000-dalton lens fiber junction polypeptide. Thus, in spite of the ultrastructural similarities, the gap junction and the lens fiber junction are comprised of distinctly different polypeptides, suggesting that the lens fiber junction contains a unique gene product and potentially different physiological properties

Biodiversity and Ecosystem Health of the Aldabra Group, Southern Seychelles: Scientific Report to the Government of Seychelles.

National Geographic's Pristine Seas project, in collaboration with the government of the Seychelles, the Island Conservation Society (ICS), the Seychelles Islands Foundation (SIF), and the Waitt Foundation, conducted an expedition to explore the poorly known marine environment around these islands. The goals were to assess the biodiversity of the nearshore marine environment and to survey the largely unknown deep sea realm. The data collected contribute to the marine spatial planning of the Seychelles, in particular the creation of large marine reserves

Quasi-local contribution to the scalar self-force: Non-geodesic Motion

We extend our previous calculation of the quasi-local contribution to the self-force on a scalar particle to general (not necessarily geodesic) motion in a general spacetime. In addition to the general case and the case of a particle at rest in a stationary spacetime, we consider as examples a particle held at rest in Reissner-Nordstrom and Kerr-Newman space-times. This allows us to most easily analyse the effect of non-geodesic motion on our previous results and also allows for comparison to existing results for Schwarzschild spacetime.Comment: 11 pages, 1 figure, corrected typo in Eq. 2.

Algebraic approach to quantum field theory on non-globally-hyperbolic spacetimes

The mathematical formalism for linear quantum field theory on curved spacetime depends in an essential way on the assumption of global hyperbolicity. Physically, what lie at the foundation of any formalism for quantization in curved spacetime are the canonical commutation relations, imposed on the field operators evaluated at a global Cauchy surface. In the algebraic formulation of linear quantum field theory, the canonical commutation relations are restated in terms of a well-defined symplectic structure on the space of smooth solutions, and the local field algebra is constructed as the Weyl algebra associated to this symplectic vector space. When spacetime is not globally hyperbolic, e.g. when it contains naked singularities or closed timelike curves, a global Cauchy surface does not exist, and there is no obvious way to formulate the canonical commutation relations, hence no obvious way to construct the field algebra. In a paper submitted elsewhere, we report on a generalization of the algebraic framework for quantum field theory to arbitrary topological spaces which do not necessarily have a spacetime metric defined on them at the outset. Taking this generalization as a starting point, in this paper we give a prescription for constructing the field algebra of a (massless or massive) Klein-Gordon field on an arbitrary background spacetime. When spacetime is globally hyperbolic, the theory defined by our construction coincides with the ordinary Klein-Gordon field theory on aComment: 21 pages, UCSBTH-92-4

Support varieties for selfinjective algebras

Support varieties for any finite dimensional algebra over a field were introduced by Snashall-Solberg using graded subalgebras of the Hochschild cohomology. We mainly study these varieties for selfinjective algebras under appropriate finite generation hypotheses. Then many of the standard results from the theory of support varieties for finite groups generalize to this situation. In particular, the complexity of the module equals the dimension of its corresponding variety, all closed homogeneous varieties occur as the variety of some module, the variety of an indecomposable module is connected, periodic modules are lines and for symmetric algebras a generalization of Webb's theorem is true

Gravitational waves about curved backgrounds: a consistency analysis in de Sitter spacetime

Gravitational waves are considered as metric perturbations about a curved background metric, rather than the flat Minkowski metric since several situations of physical interest can be discussed by this generalization. In this case, when the de Donder gauge is imposed, its preservation under infinitesimal spacetime diffeomorphisms is guaranteed if and only if the associated covector is ruled by a second-order hyperbolic operator which is the classical counterpart of the ghost operator in quantum gravity. In such a wave equation, the Ricci term has opposite sign with respect to the wave equation for Maxwell theory in the Lorenz gauge. We are, nevertheless, able to relate the solutions of the two problems, and the algorithm is applied to the case when the curved background geometry is the de Sitter spacetime. Such vector wave equations are studied in two different ways: i) an integral representation, ii) through a solution by factorization of the hyperbolic equation. The latter method is extended to the wave equation of metric perturbations in the de Sitter spacetime. This approach is a step towards a general discussion of gravitational waves in the de Sitter spacetime and might assume relevance in cosmology in order to study the stochastic background emerging from inflation.Comment: 17 pages. Misprints amended in Eqs. 50, 54, 55, 75, 7