Design, simulation and experiment of a cusp electron beam for millimeter wave gyro-devices

The design, simulation and experiment of a thermionic cusp electron gun that is to be used for millimeter wave generation will be presented. A cusp gun uses a non-adiabatic magnetic field reversal to obtain azimuthal motion on an electron beam resulting in an annular shaped, axis-encircling beam. The cusp gun was designed to generate a beam of 1.5A at 40kV with an adjustable velocity ratio of up to 3.0. The beam had a simulated axial velocity spread of 7.4% and alpha spread of 10.1%. The beam had an averaged radius of 0.35mm and beam thickness of 0.05mm which is ideal to drive sub-mm wave gyro-devices under investigation

Studies on the terrestrial and freshwater algae of aldabra atoll

A study was made of the terrestrial and freshwater algae of Aldabra Atoll, Indian Ocean. Field work was carried out between September 1972 and June 1973. Wide ranging excursions were made to various areas of the atoll in order to collect information on the species present together with physico-chemical and descriptive data from representative habitats. Data were collected in a standard manner and stored in a computable form using a modified version of a stream recording system devised in Durham, 1053 samples were collected during the field study, of which 521 were complete with detailed taxonomic and environmental data. The latter are stored on computer file at Durham. The 521 samples constituted an Aldabran data bank and a range of computer programmes facilitated the rapid retrieval of information and the performing of statistical analyses. An example of one such statistical analysis is included in the present study. A taxonomic checklist is given of the 291 species together with descriptions of these species, comparisons with the descriptions given by other authors, the areas of Aldabra from which they were recorded, notes on distribution on Aldabra, habitats, abundance and comparisons with records of other workers. Blue-green algae are the most abundant species present, predominating in both terrestrial and freshwater habitats. In terrestrial habitats they are often present almost to the exclusion of other species, though in freshwater habitats this predominance is less well-marked. It is probable that some species are restricted to certain regions or habitats: the reasons for such restriction are discussed. A study of one physiological process in blue-green algae is presented. The nitrogen-fixing potential of Tolypothrix byssoidea and several Nostoc species was investigated using the acetylene reduction assay technique. The study includes rates measured between 0930 and 1200 h, a 24 h time course study for Nostoc Commune and laboratory studies on the onset of acetylene reduction after rewetting

Multi-mode coupling wave theory for helically corrugated waveguide

Helically corrugated waveguide has been used in various applications such as gyro-backward wave oscillators, gyro-traveling wave amplifier and microwave pulse compressor. A fast prediction of the dispersion characteristic of the operating eigenwave is very important when designing a helically corrugated waveguide. In this paper, multi-mode coupling wave equations were developed based on the perturbation method. This method was then used to analyze a five-fold helically corrugated waveguide used for X-band microwave compression. The calculated result from this analysis was found to be in excellent agreement with the results from numerical simulation using CST Microwave Studio and vector network analyzer measurements

Characterization of the catalytic mechanisms of 'Escherichia coli' fumarate reductase and ubiquinal oxidase cytochrome-bd

Escherichia coli respiratory enzymes fumarate reductase and ubiquinol-oxygen oxido-reductase cytochrome-bd have been investigated with the aim of determining their catalytic mechanisms. A rapid-freeze quench apparatus was developed for discontinuous pre-steady state spectral analysis of fumarate reductase prosthetic group electron transfer. The ram system includes the application of stainless steel HPLC parts for mixing. The novel feature of the apparatus is the cryostat which is safer and more convenient to use than its predecessors. The cryostat was designed for application to electron paramagnetic resonance studies but could easily be modified for use with other spectroscopic techniques. Test reactions determined the resolution of the apparatus in the low millisecond range. Reduction/oxidation events for the iron-sulphur centres FR1 and FR3 of fumarate reductase were not kinetically resolved in the low millisecond range (internal equilibration rapid). From data presented, FR1 and FR3 are thought to be kinetically competent for the predicted maximum turnover of the fumarate reductase benzyl viologen assay (30s-1, Simpkin, 1985). E.p.r. signals for FR2, the low potential iron-sulphur centre, were not observed in the pre-steady state or steady state and the role of this centre in electron transfer remains ambiguous. The data is consistent with a sequential model of electron transfer from menaquinol→FR3→FR1→flavin→fumarate. A dual, high potential/low potential, pathway for fumarate reductase (Cammack et al., 1986a,b) is not consistent with available data. Ligand binding studies for cytochrome-bd demonstrate carbon monoxide and nitric oxide ligation to both haem-d and haem-b595. Photodissociation affects for the carbon monoxide inhibited oxidase (oxygen electrode) and time dependent haem-NO formation (optical and e.p.r.), suggest a bimetallic site with two haems in close proximity. The catalytic mechanism for dioxygen reduction is proposed as a single dioxygen ligation between haem-b595 and haem-d with subsequent reduction by haem-b558 and quinol. A stabilized (bound) semiquinone in close proximity to haem-b558 is also detected

A History of Louisiana\u27s Rural Electric Cooperatives, 1937-1983.

The Rural Electrification Administration was created by Franklin D. Roosevelt in 1936. There were attempts at rural electrification prior to that date, but FDR\u27s program, as part of the New Deal, was the beginning of the modern system. The REA was put into operation by Morris L. Cooke, and expanded by John Carmody and Harry Slattery through 1944. The Fifties ushered in a conservative presidential administration that opposed organizations such as co-ops, and, consequently, funds were cut. But on the local level, co-ops continued to grow. The Sixties brought with it financial cooperation from Washington, and many co-ops around the country found that there was enough money available to begin generating their own power. In Louisiana, the REA came not as a government organization, but as a generous banker--a lender of low interest money. The co-ops began in Louisiana in late 1937 at Teche Electric, and developed to a total of thirteen individual groups through the late Forties. During the War, the thirteen co-ops in the state organized a statewide association, the purpose of which was to lobby and to promote the idea of rural electrification In the early Fifties they founded a newspaper and threatened to generate their own power in the face of excessive fuel costs from the private power companies in the state. In 1962, prices again rose and the state\u27s co-op leaders, through their statewide organization, began a serious move to generate their own power. After a hard-fought struggle, a loan was finally approved in 1964. But it was not until four years later, after extensive compromise with the private utilities, that the money was finally granted for the construction of the first plant. It was also at this time that the group fought battles over right-of-way regulation and Public Service Commission regulation. Between the completion of the first plant in 1972 and today (1983) Cajun Electric has completed three other plants, all coal

Seiberg-Witten-Floer Homology and Gluing Formulae

This paper gives a detailed construction of Seiberg-Witten-Floer homology for a closed oriented 3-manifold with a non-torsion \spinc structure. Gluing formulae for certain 4-dimensional manifolds splitting along an embedded 3-manifold are obtained.Comment: 63 pages, LaTe