4,665 research outputs found

    Method for fiberizing ceramic materials Patent

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    Process for fiberizing ceramic materials with high fusion temperatures and tensile strengt

    What Constitutes a County Highway Program?

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    Chronology: MSFC Space Station program, 1982 - present. Major events

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    The Marshall Space Flight Center (MSFC) maintains an active program to capture historical information and documentation on the MSFC's roles regarding Space Shuttle and Space Station. Marshall History Report 12, called Chronology: MSFC Space Station Program, 1982-Present, is presented. It contains synopses of major events listed according to the dates of their occurrence. Indices follow the synopses and provide additional data concerning the events listed. The Event Index provides a brief listing of all the events without synopses. The Element Index lists the specific elements of the Space Station Program under consideration in the events. The Location Index lists the locations where the events took place. The indices and synopses may be cross-referenced by using dates

    A Normal-Mode Approach to Jovian Atmospheric Dynamics

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    We propose a nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity equation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is then derived. We show that for a planet with a neutrally stable, fluid interior instead of a solid lower boundary, the baroclinic mode represents motions in the interior, and is not affected by the baroclinic modes. One consequence of this is that a normal-mode model with one baroclinic mode is dynamically equivalent to a one layer model with solid lower topography. We also show that for motions in Jupiter's cloudy lower troposphere, the stratosphere behaves nearly as a rigid lid, so that the normal-mode model is applicable to Jupiter. We test the accuracy of the normal-mode model for Jupiter using two simple problem forced, vertically propagating Rossby waves, using two and three baroclinic modes and baroclinic instability, using two baroclinic modes. We find that the normal-road model provide qualitatively correct results, even with only a very limited number of vertical degrees of freedom

    A Note on Embedding of M-Theory Corrections into Eleven-Dimensional Superspace

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    By analyzing eleven-dimensional superspace fourth-rank superfield strength F-Bianchi identities, we show that M-theory corrections to eleven-dimensional supergravity can not be embedded into the mass dimension zero constraints, such as the (\g^{a b})_{\a\b} X_{a b}{}^c or i (\g^{a_1... a_5})_{\a\b} X_{a_1... a_5}{}^c -terms in the supertorsion constraint T_{\a\b}{}^c. The only possible modification of superspace constraint at dimension zero is found to be the scaling of F_{\a\b c d} like F_{\a\b c d} = (1/2) \big(\g_{c d}\big)_{\a\b} e^\Phi for some real scalar superfield \Phi, which alone is further shown not enough to embed general M-theory corrections. This conclusion is based on the dimension zero F-Bianchi identity under the two assumptions: (i) There are no negative dimensional constraints on the F-superfield strength: F_{\a\b\g\d} = F_{\a\b\g d} =0; (ii) The supertorsion T-Bianchi identities and F-Bianchi identities are not modified by Chern-Simons terms. Our result can serve as a powerful tool for future exploration of M-theory corrections embedded into eleven-dimensional superspace supergravity.Comment: 14 pages, latex, some minor typos corrected, as well as old section 5 deleted, due to the subtlety about Chern-Simons term in F-Bianchi identitie

    Radio and near-infrared observations of the steep spectrum Galactic plane radio source WKB 0314+57.8

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    Radio and near-infared observations towards the steep spectrum Galactic plane radio source WKB 0314+57.8 are presented, in order to clarify the nature of this source. The radio observations include archival and survey data, together with new Giant Metrewave Radio Telescope observations at 617 MHz. The near-infrared observations are in the J and K bands, from the Gemini instrument on the Shane 3-m telescope. The radio observations show that WKB 0314+57.8 is extended, with an very steep spectrum (with flux density proportional to frequency to -2.5 power between 40 MHz and 1.5 GHz). The colour--magnitude diagram constructed from near-infrared observations of the field suggests the presence of a z approx 0.08 galaxy cluster behind the Galactic plane, reddened by about 6 magnitudes of visual extinction. Although the steep spectrum source has no obvious identification, two other radio sources in the field covered by the near-infrared observations have tentative identifications with galaxies. These observations indicate that WKB 0314+57.8 is a relic source in a cluster of galaxies, not a pulsar.Comment: 6 pages, to appear in MNRAS, typos correcte

    Seasonal variability of Indonesian rainfall in ECHAM4 simulations and in the reanalyses: The role of ENSO

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    A study on the skill of the atmospheric general circulation model ECHAM version 4 and two reanalyses in simulating the Indonesian rainfall is presented with comparisons to 30 years of rain gauge data. The reanalyses are those performed by the European Centre for Medium-Range Weather Forecasts and of the National Centers for Environmental Predic- tion jointly with National Center for Atmospheric Research. This study investigates the skill of the reanalyses and ECHAM4 with regard to regional, annual and interannual variability of rainfall and its responses to El Ni˜ no-Southern Oscillation (ENSO) events. The study is conducted at two resolutions, T42 and T106. A new regionalization method called the double correlation method is introduced. With this method, the Maritime Continent is divided into three climate regions, the south mon- soonal, the northwest semi-monsoonal and the Molucca anti-monsoonal region. Except over Molucca, the reanalyses and ECHAM4 simulate these annual rainfall patterns quite well. The three regions are used to study the variability of Indonesian rainfall and to mea- sure the skills of the reanalyses and ECHAM4. The skill of rainfall simulations in Indonesia depends on the region, month and season, and the distribution of land and sea. Higher sim- ulation skills are confined to years with ENSO events. Except for the region of northwest Indonesia, the rainfall from June (Molucca) and July (south Indonesia) to November is in- fluenced by ENSO, and it is more sensitive to El Ni˜ no than La Ni˜ na events. The observations show that the Moluccan region is more sensitive to ENSO, receives a longer ENSO impact and receives the earliest ENSO impact in June. The ENSO impact will diminish in Decem- ber. It is found that the reanalyses and the climate model simulate the seasonal variability better than the monthly one. The seasonal skill is the highest in June/July/August, followed by September/October/November, December/January/February and March/April/May. The correlations usually break down in April (for monthly analysis) or in spring (for seasonal analysis). In general the performance of ECHAM4 is poor, but in ENSO sensitive regions and during ENSO events, it is comparable to the reanalyses. The introduction of a higher resolution land-sea mask improves the model performance. Besides rainfall variability, signatures of the ENSO impact, the spring correlation breakdown and annual cycles are better represented by the higher resolution model

    Spectral energy distributions of quasars selected in the mid-infrared

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    We present preliminary results on fitting of SEDs to 142 z>1 quasars selected in the mid-infrared. Our quasar selection finds objects ranging in extinction from highly obscured, type-2 quasars, through more lightly reddened type-1 quasars and normal type-1s. We find a weak tendency for the objects with the highest far-infrared emission to be obscured quasars, but no bulk systematic offset between the far-infrared properties of dusty and normal quasars as might be expected in the most naive evolutionary schemes. The hosts of the type-2 quasars have stellar masses comparable to those of radio galaxies at similar redshifts. Many of the type-1s, and possibly one of the type-2s require a very hot dust component in addition to the normal torus emission.Comment: 4 pages, 2 figures, to appear in the proceedings of The Spectral Energy Distribution of Galaxies, Preston, September 2011, eds R.J. Tuffs & C.C. Popesc
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