101 research outputs found

    Accuracy Investigations on a Polar Position-Fixing System

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    This paper affords an insight into some investigations about geodetic devices carried out by the Federal Institute of Hydrology in Germany. The methods developed and the results of the field tests are presented. The qualities determined and the accuracy of the device correspond in almost all cases with the statements of the manufacturer

    Digitales GelÀndemodell des Niederrheins

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    Nano- and micro-structures in lunar zircon from Apollo 15 and 16 impactites: implications for age interpretations

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    Meteorite impact processes are ubiquitous on the surfaces of rocky and icy bodies in the Solar System, including the Moon. One of the most common accessory minerals, zircon, when shocked, produces specific micro-structures that may become indicative of the age and shock conditions of these impact processes. To better understand the shock mechanisms in zircon from Apollo 15 and 16 impact breccias, we applied transmission electron microscopy (TEM) and studied nano-structures in eight lunar zircons displaying four different morphologies from breccias 15455, 67915, and 67955. Our observations revealed a range of shock-related features in zircon: (1) planar and non-planar fractures, (2) “columnar” zircon rims around baddeleyite cores, (3) granular textured zircon, in most cases with sub-”m-size inclusions of monoclinic ZrO2 (baddeleyite) and cubic ZrO2 (zirconia), (4) silica-rich glass and metal inclusions of FeS and FeNi present at triple junctions in granular zircon and in baddeleyite, (5) inclusions of rutile in shocked baddeleyite, (6) amorphous domains, (7) recrystallized domains. In many grain aggregates, shock-related micro-structures overprint each other, indicating either different stages of a single impact process or multiple impact events. During shock, some zircons were transformed to diaplectic glass (6), and others (7) were completely decomposed into SiO2 and Zr-oxide, evident from the observed round shapes of cubic zirconia and silica-rich glass filling triple junctions of zircon granules. Despite the highly variable effect on textures and Zr phases, shock-related features show no correlation with relatively homogeneous U–Pb or 207Pb/206Pb ages of zircons. Either the shock events occurred very soon after the solidification or recrystallization of the different Zr phases, or the shock events were too brief to result in noticeable Pb loss during shock metamorphism

    Short total synthesis of ajoene, (E ,Z )‐4,5,9‐Trithiadodeca‐1,6,11‐triene 9‐oxide, in batch and (E ,Z )‐4,5,9‐Trithiadodeca‐1,7,11‐triene in continuous flow

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    A short total synthesis of ajoene, (E,Z )‐4,5,9‐trithiadodeca‐1,6,11‐triene 9‐oxide, has been achieved over six steps. In addition, a continuous flow synthesis under mild reaction conditions to (E,Z )‐4,5,9‐trithiadodeca‐1,7,11‐triene is described starting from simple and easily accessible starting materials. Over four steps including propargylation, radical addition of thioacetate, deprotection, and disulfide formation/ allylation, the target product can be obtained at a rate of 0.26 g h−1 in an overall yield of 12 %

    Spitzer IRS 16 micron Observations of the GOODS Fields

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    We present Spitzer 16 micron imaging of the Great Observatories Origins Deep Survey (GOODS) fields. We survey 150 square arcminutes in each of the two GOODS fields (North and South), to an average 3 sigma depth of 40 and 65 micro-Jy respectively. We detect about 1300 sources in both fields combined. We validate the photometry using the 3-24 micron spectral energy distribution of stars in the fields compared to Spitzer spectroscopic templates. Comparison with ISOCAM and AKARI observations in the same fields show reasonable agreement, though the uncertainties are large. We provide a catalog of photometry, with sources cross correlated with available Spitzer, Chandra, and HST data. Galaxy number counts show good agreement with previous results from ISOCAM and AKARI, with improved uncertainties. We examine the 16 to 24 micron flux ratio and find that for most sources it lies within the expected locus for starbursts and infrared luminous galaxies. A color cut of S_{16}/S_{24}>1.4 selects mostly sources which lie at 1.1<z<1.6, where the 24 micron passband contains both the redshifted 9.7 micron silicate absorption and the minimum between PAH emission peaks. We measure the integrated galaxy light of 16 micron sources, and find a lower limit on the galaxy contribution to the extragalactic background light at this wavelength to be 2.2\pm 0.2$ nW m^{-2} sr^{-1}.Comment: Accepted for Publication in the AJ. 53 preprint pages, including 15 figures and 8 tables. Table 1-4 are truncated in the ms.tex but are included in full in the tar file (and will be available in the online version of the AJ

    Regionale Standards: Ausgabe 2013

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    "Die 'Regionalen Standards' gehen zurĂŒck auf die Initiative eines gemeinsamen Arbeitskreises, bestehend aus Vertretern des Statistischen Bundesamtes, der Arbeitsgemeinschaft Sozialwissenschaftlicher Institute e.V. (ASI) und des ADM Arbeitskreis Deutscher Markt- und Sozialforschungsinstitute e.V. Sie stellen ein Angebot fĂŒr die Forschung in der Bundesrepublik Deutschland dar. Die 'Regionalen Standards' beschreiben Gebietsabgrenzungen und Instrumente zur Typisierung von Regionen, wie sie in der Bundesrepublik Deutschland von der amtlichen Statistik und/oder der Markt- und Sozialforschung in gewisser RegelmĂ€ĂŸigkeit eingesetzt werden. ZusĂ€tzlich werden DatensĂ€tze aus unterschiedlichen Quellen vorgestellt, die fĂŒr die Regionalisierung von Bevölkerungsumfragen genutzt werden können und fĂŒr die Forschung (teils jedoch mit EinschrĂ€nkungen) zur VerfĂŒgung stehen. ErgĂ€nzt werden die 'Regionalen Standards' durch eine jĂ€hrlich aktualisierte Tabellenanalyse aus dem Mikrozensus, zu beziehen ĂŒber die Internetseiten www.destatis.de, www.gesis.org und www.adm-ev.de." (Autorenreferat
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