U-duality covariant membranes

We outline a formulation of membrane dynamics in D=8 which is fully covariant under the U-duality group SL(2,Z) x SL(3,Z), and encodes all interactions to fields in the eight-dimensional supergravity, which is constructed through Kaluza-Klein reduction on T^3. Among the membrane degrees of freedom is an SL(2,R) doublet of world-volume 2-form potentials, whose quantised electric fluxes determine the membrane charges, and are conjectured to provide an interpretation of the variables occurring in the minimal representation of E_{6(6)} which appears in the context of automorphic membranes. We solve the relevant equations for the action for a restricted class of supergravity backgrounds. Some comments are made on supersymmetry and lower dimensions.Comment: LaTeX, 21 pages. v2: Minor changes in text, correction of a sign. v3: some changes in text, a sign convention changed; version to appear in JHE

The Twisted String Vertex Algorithm Applied to the Z2Z_2-Twisted Scalar String Four Vertex

Recently an algorithm was found by means of which one can calculate terms at arbitrary oscillator level in the four-Ramond vertex obtained by sewing. Here we show that this algorithm is applicable also to the case of ${\bf Z}_2$-twisted scalars and derive the full propagator for scalars on the Riemann sphere with two branch cuts. The relation to similar results previously derived in the literature by other means is discussed briefly.Comment: 18 pages (LaTeX), G\"oteborg ITP 94-

Higher-Dimensional Loop Algebras, Non-Abelian Extensions and p-Branes

We postulate a new type of operator algebra with a non-abelian extension. This algebra generalizes the Kac--Moody algebra in string theory and the Mickelsson--Faddeev algebra in three dimensions to higher-dimensional extended objects ($p$-branes). We then construct new BRST operators, covariant derivatives and curvature tensors in the higher-dimensional generalization of loop space.Comment: (published version, extended introduction), 35 pp.(LaTeX), Goteborg ITP-93-3

FIELD EMITTER ARRAYS APPLIED TO VACUUM FLUORESCENT DISPLAY

In this paper we describe recent progress in the development of a thin vacuum-fluorescent display utilizing a matrix-addressable array of groups of Spindt-type field-emission cathodes1,2. The array consists of a matrix having 100 lines/inch in one direction and 300 lines/inch in the other. Each picture element (pixel) in the matrix is made up of an array of emitter tips sharing a common, individually addressable base electrode (one of the 100 lines) and three separately addressable control or gate electrodes in the orthogonal direction (one for each of the basic colors : red, green, blue). Each color element has about 100 emitter tips. The current emitted from the array is averaged over the 100 tips, and good uniformity of emission from color element to color element and pixel to pixel can be obtained, because of the averaging effect