Evidence for plasmid-associated crystal toxin production in Bacillus thuringiensis subsp. israelensis

Three crystalliferous (Cry+) strains of Bacillus thuringiensis subsp. israelensis (serotype 14) that produce parasporal protein crystals toxic to dipteran larvae and several acrystalliferous (Cry-) mutants, either induced or spontaneously derived from a single Cry+ parent, were examined for the presence of covalently closed circular (CCC) DNA in attempts to correlate toxin production with the presence of a specific plasmid. The plasmid profiles of both Cry+ and Cry- variants were analyzed by both a cleared lysate- and a modified Eckhardt lysate-electrophoresis technique. All of the Cry- mutants derived from the Cry+ parental strain had lost a 4.0- to 4.4-megadalton (Mdal) plasmid. Bioassay data confirmed loss of toxin production by the Cry- variants. All three Cry+ strains, including the parent of the Cry- strains, contained CCC plasmids DNAs of the following approximate molecular weights: 4.0 to 4.4, 5.2 to 6.0, and 11.4 to 13.0 Mdal. One Cry+ strain contained an additional CCC plasmid of 6.7 to 7.2 Mdal. The plasmid patterns for several Cry- derivatives differed in other respects from the pattern for their parent strain. The various Cry+ and Cry- strains could be distinguished either by phenotypical differences in antibiotic sensitivity, crystal production, and toxicity, or by differences in their plasmid profiles.     

Long-term continental U.S. timing system via television networks

Hundreds of atomic frequency standards and precision crystal oscillators exist in remote locations throughout the continental U.S. that are synchronized through fairly complex and costly means. Today, however, an inexpensive synchronization system is available in the form of live television broadcasts by commercial networks. In precision and accuracy, the television method is comparable to the portable atomic clock and/or Loran-C, with average day-to-day differential delays less than 1?s. Based on the results of the tests presented here, the use of nearly any solid-state television receiver and a low-cost horizontal sync pulse generator can provide 10-?s synchronizations at all times. The operation of a TV line-10 timing system, including the circuitry of auxiliary equipment, is also included. This article gives about 1? years of substantiating data for the three major commercial networks (ABC, CBS, and NBC). There is also provision for synchronization with the NBS and/or USNO Coordinated Universal Time (UTC) scales through regularly published reports.     

Isolation of a spotted fever group rickettsia from the Pacific Coast tick, Ixodes pacificus, in Oregon

A rickettsia of the spotted fever group was isolated on three occasions from Ixodes pacificus in western Oregon. These isolations, and additional evidence furnished by complement fixation tests on guinea pigs inoculated with other Oregon ticks of this species, indicate that the association of this rickettsia with the Pacific Coast tick may be widespread. This is the first isolation of a spotted fever group rickettsia from I. pacificus. Because the Oregon isolates are mildly virulent for guinea pigs they resemble the Western U and Rickettsia montana strains of rickettsiae. However, preliminary evidence from cross-immunofluorescence tests of mouse antisera suggests the Tillamook and Grants Pass strains are antigenically different from all known spotted fever group agents.     

LINEARIZATION OF EMPIRICAL RHEOLOGICAL DATA FOR USE IN COMPOSITION CONTROL OF MULTICOMPONENT FOODSTUFFS

Abstract An empirical measure of viscosity, which is often far from being a linear function of composition, was used together with refractive index to build up a function which bears a linear relationship to the composition of tomato paste-water-sucrose mixtures. The new function can be used directly for rapid composition control by linear vector-vector transformation.     

Reactively hot-pressed yttrium iron garnets

Reactive hot-pressing of co-precipitated oxalates of Yttrium and Iron, under 6000–8000 psi, to a maximum temperature of 1100°C, produced high density specimens. Only the stooichiometric mixture (Fe/Y=1.66) produced some garnet phase. Off-stoichiometric specimens were mainly composed of orthoferrites. On annealing in air or oxygen at 1400°C, the orthoferrite phase was converted to the garnet phase (with excess Fe₂O₃ or Y₂O₃ in the lattice) with an accompanying increase in magnetic moment.     

Application of iterative suboptimal strategies for improving adaptation transients in adaptive systems

Some solutions which involve iterative optimization techniques are given to improve adaptation transients in adaptive systems. Two suboptimal controllers are developed and applied to an equivalent discrete-time system valid for describing the behaviour of a recent adaptive control scheme when one of the (time-varying) parameters entering the adaptation algorithm varies within a closed domain admissible from a convergence point of view. The resulting suboptimal control strategies are translated into corrections of this parameter in order to recompute the adaptation algorithm over a finite horizon. Some numerical simulations illustrate the usefulness of the proposed scheme.