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  • 2015-2019  (112)
  • 2010-2014  (177)
  • 1990-1994  (45)
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  • 1
    ISSN: 1432-1017
    Keywords: Monte Carlo ; Crystal water ; Structure refinement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The space in the unit cell of a metmyoglobin crystal not occupied by myoglobin atoms was filled with water using Monte Carlo calculations. Independent calculations with different amounts of water have been performed. Structure factors were calculated using the water coordinates thus obtained and the known coordinates of the myoglobin atoms. A comparison with experimental structure factors showed that both the low and the high resolution regime could be well reproduced with 814 Monte Carlo water molecules per unit cell with a B-value of 50 Å2. The Monte Carlo water molecules yield a smaller standard R-value (0.166) than using a homogeneous electron density for the simulation of the crystal water (R = 0.212). A reciprocal space refinement of the water and the protein coordinates has been performed. Monte Carlo calculations can be used to obtain information for crystallographically invisible parts of the unit cell and yield better coordinates for the visible part in the refinement.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Digital Particle-Image-Velocimetry was applied to investigate particle trajectories in a gas flow past a sphere. The particle displacement was determined by autocorrelation analysis of image sections. To enhance the signal/noise ratio a synthetic image with idealized particle pictures was generated from the real image. The autocorrelation function (ACF) was calculated using the Fast Hartley Transformation (FHT). The desired secondary maximum of this function was detected by an algorithm with subpixel resolution. A data validation step testing the plausibility of the velocity vectors completes the image analysis. Particle trajectories are traced with help of the particles' velocity vectors. The particle deposition on a sphere can be deduced from the course of these trajectories.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Annales geophysicae 12 (1994), S. 1197-1206 
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In a series of ozone-sonde soundings at the Hohenpeißenberg observatory, starting in 1967, the most striking features are increases of \sim2.2% per year in all tropospheric heights up to 8 km during the past 24 years. These facts have recently been published and discussed by several authors. In this paper, we present some evidence for the increase of tropospheric ozone concentrations during the past 50 years 1940–1990 in the territory of the northern edge of the Bavarian Alps, including the Hohenpeißenberg data. In December 1940 and August 1942, probably the first exact wet-chemical vertical soundings of ozone up to 9 km height were made by an aircraft in the region mentioned. These results were published in the earlier literature. We have converted the results of the flights on 4 days in December 1940 and on 6 days in August 1942 to modern units and have compared them with the Hohenpeißenberg ozone-sonde data of the December and August months. We also compared the data at the ground with the August results of Paris-Montsouris 1886-1898. Our results show an increase of ozone concentration at all tropospheric heights in Upper Bavaria during the past 50 years, compared with the Montsouris data in August during the past 105 years. In the recently published papers, the increases since 1967 were approximated linearly.Our results, extended to the past, show non-linear trends, with steeper increases since 1975-1979. Possible reasons for these findings are discussed. Quite recently (in case of the December months since 1986/87, the August months since 1990), the ozone mixing ratios at and above Hohenpeißenberg seem to have decreased.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019-03-04
    Description: The boron isotope (δ11B) composition of marine calcifiers is considered to be one of the most reliable pH proxies, enabling us to reconstruct past ocean pH and infer on the associated changes in carbon budget involved (e.g. Gut- jahr et al. 2017). The application of the commonly used δ 11 B archives such as foraminifera or corals is however mostly limited to the Cenozoic due to insufficient preservation or incomplete geological records. Brachiopods have a promising potential for extending our knowledge on seawater pH evolution throughout the entire Phanerozoic considering their high abundance in the fossil record and its origin dating back to the early Cambrian. Moreover, their shell is composed of low-magnesium calcite, rendering brachiopods more resistant to post-depositional di-magenetic alteration of its primary chemical signal (e.g. Brand et al. 2012). Additionally, even today they present an extant and widespread taxa, allowing for an assessment of the controls on boron isotope incorporation into brachiopod calcite and possible distortions of the signal due to vital effects or other processes. We present a detailed exploration of boron isotope systematics in three different brachiopod species (Magellania venosa, Terebratella dorsata, Pajaudina atlantica) cultured under controlled laboratory settings for over a year. Our experimental setup includes a control (pH = 8.15) and two pH treatments (pH = 7.6 and 7.35), and we provide both bulk MC-ICP-MS as well as high spatial resolution SIMS data of the shell material. Our results indicate that boron incorporation is primarily driven by vital effects related to their ability to regulate calcifying fluid pH in response to ambient changes, which we further validate by in vivo microelectrode measurements (e.g. Stumpp et al. 2012). Despite internal buffering, the local pH at calcification sites systematically decreases with seawater pH, and hence is impacted by ocean acidification. This not only suggests that brachiopod shells serve as useful and conservative recorders of past ocean pH trends, but also provides new insights into mechanisms that may have enabled brachiopod survival throughout several major environmental crises in the past. Our findings have implications for past climate studies, as well as research on calcification processes and physio- logical adaptations to environmental change (e.g. the actual global ocean acidification). Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli, E., 2012. The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic catastrophe, Chem. Geol. 323, 121-144. Gutjahr M., Ridgewell A., Sexton P.F., Anagnostou E., Pearson P.N., Pälike H., Norris R.D., Thomas E., and Foster G.L., 2017. Very large release of mostly volcanic carbon during the Palaeocene-Eocene Thermal Maximum, Nature 548, 573-577. Stumpp M., Hu M.Y., Melzner F., Gutowska M., Dorey N., Himmerkus N., Holtmann W.C., Dupont S.T., Thorndyke M.C., and Bleich M. Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification, PNAS 44: 18192-18197.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 337 (1990), S. 355-356 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate an extension of the Standard Model with a second Higgs doublet, showing a two stage phase transition. Wash-out of a baryon asymmetry after the phase transition can be easily avoided in this class of models.B+L transitions are more strongly suppressed in the intermediate phase than in the high temperature symmetric phase, however. Therefore, it becomes more difficult if not impossible to generate a sufficient baryon asymmetry during the phase transition.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the clear observation and assignment of the symmetric stretching and bending van der Waals modes in two three-bodyC 2v complexes, phenol- and aniline-(Ar)2, using resonant two-photon ionization.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-6079
    Keywords: 36.40. + d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A tandem time-of-flight mass spectrometer is used to measure photofragmentation mass spectra and optical absorption spectra of mass selected argon cluster ions in then=3 to 108 atoms per cluster range.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrafast electromagnetic radiation induced by a femtosecond laser beam from a semiconductor provides determination of the impurity doping concentration, carrier mobility, sign, and strength of the depletion field near the semiconductor surface.
    Type of Medium: Electronic Resource
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