46,705 research outputs found

    Energetic solar proton versus terrestrially trapped proton fluxes for the active years 1977 - 1983

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    Ratios of solar to trapped proton fluences were computed for circular-orbit, geocentric space missions to be flown during the active phase of the next solar cycle (1977-1983). The ratios are presented as functions of orbit altitude and inclination, mission duration, proton energy threshold, and the chance the mission planner is willing to take that the actually encountered solar proton fluence will exceed the design fluence provided by the statistical solar proton model. It is shown that the ratio is most sensitively dependent on orbit altitude and inclination, with trapped protons dominant for low inclination, low and mid altitude orbits and for high inclination, mid altitude orbits. Conversely, solar protons are dominant for high inclination, low altitude orbits, and for low and high inclination, high altitude orbits

    Design of recursive digital filters having specified phase and magnitude characteristics

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    A method for a computer-aided design of a class of optimum filters, having specifications in the frequency domain of both magnitude and phase, is described. The method, an extension to the work of Steiglitz, uses the Fletcher-Powell algorithm to minimize a weighted squared magnitude and phase criterion. Results using the algorithm for the design of filters having specified phase as well as specified magnitude and phase compromise are presented

    Hopf algebras and characters of classical groups

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    Schur functions provide an integral basis of the ring of symmetric functions. It is shown that this ring has a natural Hopf algebra structure by identifying the appropriate product, coproduct, unit, counit and antipode, and their properties. Characters of covariant tensor irreducible representations of the classical groups GL(n), O(n) and Sp(n) are then expressed in terms of Schur functions, and the Hopf algebra is exploited in the determination of group-subgroup branching rules and the decomposition of tensor products. The analysis is carried out in terms of n-independent universal characters. The corresponding rings, CharGL, CharO and CharSp, of universal characters each have their own natural Hopf algebra structure. The appropriate product, coproduct, unit, counit and antipode are identified in each case.Comment: 9 pages. Uses jpconf.cls and jpconf11.clo. Presented by RCK at SSPCM'07, Myczkowce, Poland, Sept 200

    Thermomicrobium carboxidum sp. nov., and Thermorudis peleae gen. nov., sp. nov., carbon monoxide-oxidizing bacteria isolated from geothermally heated biofilms

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    Two thermophilic, Gram-stain-positive, rod-shaped, non-spore-forming bacteria (strains KI3T and KI4T) were isolated from geothermally heated biofilms growing on a tumulus in the Kilauea Iki pit crater on the flank of Kilauea Volcano (Hawai\u27i, USA). Strain KI3T grew over an examined temperature range of 50-70 °C (no growth at 80 °C) and a pH range of 6.0-9.0, with optimum growth at 70 °C and pH 7.0. Strain KI4T grew at temperatures of 55-70 °C and a pH range of 5.8-8.0, with optimum growth at 65 °C and pH 6.7-7.1. The DNA G+C contents of strains KI3T and KI4T were 66.0 and 60.7 mol%, respectively. The major fatty acid for both strains was 12-methyl C18: 0. Polar lipids in strain KI3T were dominated by glycolipids and phosphatidylinositol, while phosphatidylinositol and phosphoglycolipids dominated in strain KI4T. Strain KI3T oxidized carbon monoxide [6.7±0.8 nmol CO h-1 (mg protein)-1], but strain KI4T did not. 16S rRNA gene sequence analyses determined that the strains belong to the class Thermomicrobia, and that strains KI3T and KI4T are related most closely to Thermomicrobium roseum DSM 5159T (96.5 and 91.1 % similarity, respectively). 16S rRNA gene sequence similarity between strain KI3T and strain KI4T was 91.4 %. Phenotypic features and phylogenetic analyses supported the affiliation of strain KI3T to the genus Thermomicrobium, while results of chemotaxonomic, physiological and biochemical assays differentiated strains KI3T and KI4T from Thermomicrobium roseum. Strain KI3T (= DSM 27067T = ATCC BAA-2535T) is thus considered to be the type strain of a novel species, for which the name Thermomicrobium carboxidumsp. nov. is proposed. Additionally, the characterization and phylogenetic position of strain KI4T showed that it represents a novel species of a new genus, for which the name Thermorudis peleae gen. nov., sp. nov. is proposed. The type strain of Thermorudis peleae is KI4T (= DSM 27169T = ATCC BAA-2536T). © 2014 IUMS

    Description of Thermogemmatispora carboxidivorans sp. nov., a carbon-monoxideoxidizing member of the class Ktedonobacteria isolated from a geothermally heated biofilm, and analysis of carbon monoxide oxidation by members of the class Ktedonobacteria

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    A thermophilic, aerobic, Gram-stain-positive bacterium (strain PM5T), which formed mycelia of irregularly branched filaments and produced multiple exospores per cell, was isolated from a geothermally heated biofilm. Strain PM5T grew at 40-65 °C and pH 4.1-8.0, with optimal growth at 55 °C and pH 6.0. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain PM5T belonged to the class Ktedonobacteria, and was related most closely to Thermogemmatispora onikobensis ONI-1T (97.7 % similarity) and Thermogemmatispora foliorum ONI-5T (96.1 %). Morphological features and fatty acid profiles (major fatty acids: iso-C17: 0, iso-C19: 0 and 12,17-dimethyl C18: 0) supported the affiliation of strain PM5T to the genus Thermogemmatispora. Strain PM5T oxidized carbon monoxide [CO; 10±1 nmol h-1 (mg protein)-1], but did not grow with CO as a sole carbon and energy source. Results from analyses of related strains indicated that the capacity for CO uptake occurred commonly among the members of the class Ktedonobacteria; 13 of 14 strains tested consumed CO or harboured coxL genes that potentially enabled CO oxidation. The results of DNA-DNA hybridization and physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain PM5T from the two recognized species of the genus Thermogemmatispora. Strain PM5T differed from Thermogemmatispora onikobensis ONI-1T in its production of orange pigment, lower temperature optimum, hydrolysis of casein and starch, inability to grow with mannitol, xylose or rhamnose as sole carbon sources, and utilization of organic acids and amino acids. Strain PM5T is therefore considered to represent a novel species, for which the name Thermogemmatispora carboxidivorans sp. nov. is proposed. The type strain is PM5T (= DSM 45816T = ATCC BAA-2534T). © 2014 IUMS

    Recurrence Formulas for Fully Exponentially Correlated Four-Body Wavefunctions

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    Formulas are presented for the recursive generation of four-body integrals in which the integrand consists of arbitrary integer powers (>= -1) of all the interparticle distances r_ij, multiplied by an exponential containing an arbitrary linear combination of all the r_ij. These integrals are generalizations of those encountered using Hylleraas basis functions, and include all that are needed to make energy computations on the Li atom and other four-body systems with a fully exponentially correlated Slater-type basis of arbitrary quantum numbers. The only quantities needed to start the recursion are the basic four-body integral first evaluated by Fromm and Hill, plus some easily evaluated three-body "boundary" integrals. The computational labor in constructing integral sets for practical computations is less than when the integrals are generated using explicit formulas obtained by differentiating the basic integral with respect to its parameters. Computations are facilitated by using a symbolic algebra program (MAPLE) to compute array index pointers and present syntactically correct FORTRAN source code as output; in this way it is possible to obtain error-free high-speed evaluations with minimal effort. The work can be checked by verifying sum rules the integrals must satisfy.Comment: 10 pages, no figures, accepted by Phys. Rev. A (January 2009
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