360 research outputs found

    High-dispersion spectroscopic observations of Venus during 1968 and 1969 II. The carbon-dioxide band at 8689A

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    Thirty well-exposed photographic plates showing the spectrum of the carbon dioxide band at 8689A in the atmosphere of Venus were obtained during 1968 and 1969. All spectra were obtained at a dispersion of 2 A/mm for Venus phase angles varying from 10 deg. to 126 deg. Rotational temperatures ranging from 236 K to 274 K were found. The average value of the rotational temperature is 246 + or - 1 K (one standard deviation); for 1967 observations, the rotational temperatures ranged from 222 to 248 K, with an average value of 238 + or - 4 K. The variation of the equivalent width of the 8689A band, with Venus phase angle, was very similar for the two sets of observations (53 plates). The temporal variations, of approximately 30 percent, were comparable with the phase variations over this limited range of phase angle

    Non-Uniqueness of Quantized Yang-Mills Theories

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    We consider quantized Yang-Mills theories in the framework of causal perturbation theory which goes back to Epstein and Glaser. In this approach gauge invariance is expressed by a simple commutator relation for the S-matrix. The most general coupling which is gauge invariant in first order contains a two-parametric ambiguity in the ghost sector - a divergence- and a coboundary-coupling may be added. We prove (not completely) that the higher orders with these two additional couplings are gauge invariant, too. Moreover we show that the ambiguities of the n-point distributions restricted to the physical subspace are only a sum of divergences (in the sense of vector analysis). It turns out that the theory without divergence- and coboundary-coupling is the most simple one in a quite technical sense. The proofs for the n-point distributions containing coboundary-couplings are given up to third or fourth order only, whereas the statements about the divergence-coupling are proven in all orders.Comment: 22 pages. The paper is written in TEX. The necessary macros are include

    Interaction particles from the surface of the curved pipeline

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    The interaction of the agglomerated fine dust particles from the surface of the rotary pyleprovoda, given deposit formation evaluation. The interaction of large particles to the surface of the rotary pyleprovoda. The analysis of hydrodynamic phenomena in the means of protection against wear

    Massive gravity as a quantum gauge theory

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    We present a new point of view on the quantization of the massive gravitational field, namely we use exclusively the quantum framework of the second quantization. The Hilbert space of the many-gravitons system is a Fock space F+(Hgraviton){\cal F}^{+}({\sf H}_{\rm graviton}) where the one-particle Hilbert space Hgraviton{\sf H}_{graviton} carries the direct sum of two unitary irreducible representations of the Poincar\'e group corresponding to two particles of mass m>0m > 0 and spins 2 and 0, respectively. This Hilbert space is canonically isomorphic to a space of the type Ker(Q)/Im(Q)Ker(Q)/Im(Q) where QQ is a gauge charge defined in an extension of the Hilbert space Hgraviton{\cal H}_{\rm graviton} generated by the gravitational field hμνh_{\mu\nu} and some ghosts fields uμ,u~μu_{\mu}, \tilde{u}_{\mu} (which are vector Fermi fields) and vμv_{\mu} (which are vector field Bose fields.) Then we study the self interaction of massive gravity in the causal framework. We obtain a solution which goes smoothly to the zero-mass solution of linear quantum gravity up to a term depending on the bosonic ghost field. This solution depends on two real constants as it should be; these constants are related to the gravitational constant and the cosmological constant. In the second order of the perturbation theory we do not need a Higgs field, in sharp contrast to Yang-Mills theory.Comment: 35 pages, no figur

    Methodology for Assessing Measurement Error for Casting Surface Inspection

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    Forschungsmethoden

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    Das heutige Wissen über den Aufbau von Materie und die Entwicklung des Universums kurz nach dem Urknall beruht auf Erkenntnissen, die mit Hilfe von Teilchenbeschleunigern und -detektoren gewonnen wurden. Das vorliegende Unterrichtsmaterial bietet Ihnen und Ihren Schülern einen Einblick in die Forschungsmethoden der experimentellen Teilchenphysik. In den KAPITELN 1 und 2 werden zunächst einige Hintergrundinformationen für Lehrkräfte gegeben. Dazu gehören Anknüpfungspunkte an den Lehrplan, benötigte Vorkenntnisse der Schüler, Lernziele sowie methodische und fachliche Hinweise. KAPITEL 3 befasst sich mit den Zielen der aktuellen experimentellen Teilchenphysik-Forschung, wie sie am LHC des CERN in Genf betrieben wird. In zwei getrennten Abschnitten werden Teilchenbeschleuniger und Teilchendetektoren eingeführt. Jeder Abschnitt endet mit Fragen zur Selbstkontrolle. Daran schließt sich jeweils ein Kapitel mit Aufgaben an

    Structure of mixed ombrophyllous forests with Araucaria angustifolia (Araucariaceae) under external stress in Southern Brazil.

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    This study is part of the Floristic and Forest Inventory of Santa Catarina, conceived to evaluate forest resources, species composition and structure of forest remnants, providing information to update forest conservation and land use policy in Southern Brazilian State of Santa Catarina (95 000km²). In accordance to the Brazilian National Forest Inventory (IFN-BR), the inventory applies systematic sampling, with 440 clusters containing four crosswise 1 000m² plots (20x50m) each, located on a 10x10km grid overlaid to land use map based on classification of SPOT-4 images from 2005. Within the sample units, all woody individuals of the main stratum (DBH?10cm) are measured and collected (fertile and sterile), if not undoubtedly identified in field. Regeneration stratum (height>1.50m; DBH<10cm) is registered in 100m² in each sample unit. Floristic sampling includes collection of all fertile trees, shrubs and herbs within the sample unit and in its surroundings. This study performs analysis based on 92 clusters measured in 2008 within an area of 32 320km² of mixed ombrophyllous forests with Araucaria angustifolia located at the state’s high plateau (500m to 1 560m above sea level at 26º00’-28º30’ S and 49º13’-51º23’ W). Mean density (DBH?10cm) is 578 individuals/ha (ranging from 85/ha to 1 310/ha), mean species richness in measured remnants is 35 (8 to 62), Shannon and Wiener diversity index (H’) varies between 1.05 and 3.48. Despite high total species diversity (364 Magnoliophyta, five Coniferophyta and one tree fern) and relatively high mean basal area (25.75m²/ha, varying from 3.87 to 68.85m²/ ha), the overwhelming majority of forest fragments are considered highly impacted and impoverished, mostly by logging, burning and extensive cattle farming, turning necessary more efficient protection measures. Basal area was considered an appropriate indicator for stand quality and conservation status

    Sugars dominate the seagrass rhizosphere

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    Seagrasses are among the most efficient sinks of carbon dioxide on Earth. While carbon sequestration in terrestrial plants is linked to the microorganisms living in their soils, the interactions of seagrasses with their rhizospheres are poorly understood. Here, we show that the seagrass, Posidonia oceanica excretes sugars, mainly sucrose, into its rhizosphere. These sugars accumulate to mu M concentrations-nearly 80 times higher than previously observed in marine environments. This finding is unexpected as sugars are readily consumed by microorganisms. Our experiments indicated that under low oxygen conditions, phenolic compounds from P. oceanica inhibited microbial consumption of sucrose. Analyses of the rhizosphere community revealed that many microbes had the genes for degrading sucrose but these were only expressed by a few taxa that also expressed genes for degrading phenolics. Given that we observed high sucrose concentrations underneath three other species of marine plants, we predict that the presence of plant-produced phenolics under low oxygen conditions allows the accumulation of labile molecules across aquatic rhizospheres. Seagrass meadows are important carbon sinks. Here, the authors show that organic carbon in the form of simple sugars can accumulate at high concentrations in seagrass rhizospheres because plant phenolic compounds inhibit their consumption by microorganisms
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