The Integrated Power Switch

Utilizing a signal from transistor transistor logic (TTL) circuits, the integrated power switch (IPS) can control 40 kW. Protection against overload conditions enables the use of transistors which have ideal switching characteristics. Each half-section of the IPS is electrically isolated from the signal input using optical couplers. Discrete component assemblies, printed-circuit boards, thick-film or medium-scale integrated substrates each have been utilized. The forced-air-cooled heat sink was designed for maximum cooling. Two types of IPS's were initially constructed: 500 V/60 A, and 100 V/200 A, with additional availability of 500 V/100 A devices in small quantity. Its capability to work from continuous operation to 10 kHz makes the IPS universally applicable to most power-conversion applications with-in its current and voltage limitation.     

Human T cell leukemia virus type I expression in salivary glands of infected patients

Human T cell leukemia virus type I (HTLV-I) sequences were sought in labial salivary glands of patients with HTLV-I-associated myelopathy or tropical spastic paraparesis and of seropositive neurologically healthy carriers. HTLV-I proviral DNA was found by polymerase chain reaction amplification in DNA extracted from lip biopsies of every patient. Viral RNA was found by in situ hybridization in the acini epithelium, as well as in lymphocytic infiltrates. This observation suggests that HTLV-I expression in labial salivary glands could participate in the inflammatory lesions observed in these patients. Some seronegative patients with Sj?gren's syndrome or dryness syndrome were also positive for viral transactivator tax DNA (41% in Martinique and 16% in non-HTLV-I-endemic region). Despite histologic signs of lymphocytic infiltration, no viral expression was found in the labial salivary glands of these patients.     

Lower bounds for the bilinear complexity of associative algebras

Let R(A) denote the bilinear complexity (also called rank) of a finite dimensional associative algebra A.?We prove that if the decomposition of into simple algebras contains only noncommutative factors, that is, the division algebra is noncommutative or . In particular, -matrix multiplication requires at least essential bilinear multiplications. We also derive lower bounds of the form essential bilinear multiplications. We also derive lower bounds of the form for the algebra of upper triangular -matrices and the algebra of truncated bivariate polynomials in the indeterminates X,Y over some field k.?A class of algebras that has received wide attention in this context con-sists of those algebras A for which the Alder—Strassen Bound is sharp, i.e., R(A) = 2dim A—t is the number of maximal twosided ideals in A. These algebras are called algebras of minimal rank. We determine all semisimple algebras of minimal rank over arbitrary fields and all algebras of minimal rank over algebraically closed fields. Received: January 12, 2000.     

π-RED*—A graph reducer for a full-fledged γ-calculus

This paper describes an applicative order graph reducer which under interactive control performs high-level program transformations that are governed by the reduction semantics of a full-fledged untyped γ-calculus. To do so with competitive speed, high-level functional programs are by a pre-processor reversibly converted into graph representations of γ-terms. Its subterms are closed by the abstraction of relatively free variables only to the extent absolutely necessary to avoid the complexity of full β-reductions at run-time. Processing these γ-terms is based on high-level interpretation which exploits the simplicity and efficiency of naive graph pointer substitutions when reducing function calls. Partially or completely reduced graphs are by a post-processor re-converted into high-level programs. Full β-reductions are only employed by the pre- and post-processor to maintain correct binding levels when abstracting free variables from γ-terms and when undoing these abstractions or reducing partial applications left over as closures, respectively.