TY - CHAP A1 - Borowski, Andreas A1 - Glowinski, Ingrid A1 - Frister, Jonas A1 - Höttecke, Dietmar A1 - Buth, Katrin A1 - Koenen, Jenna A1 - Masanek, Nicole A1 - Reichwein, Wilko A1 - Scholten, Nina A1 - Sprenger, Sandra A1 - Stender, Peter A1 - Wöhlke, Carina A1 - Komorek, Michael A1 - Freckmann, Janine A1 - Hofmann, Josefine A1 - Niesel, Verena A1 - Richter, Chris A1 - Mehlmann, Nelli A1 - Bikner-Ahsbahs, Angelika A1 - Unverricht, Katja A1 - Schanze, Sascha A1 - Bittorf, Robert Marten A1 - Meier, Monique A1 - Grospietsch, Finja A1 - Mayer, Jürgen A1 - Gimbel, Katharina A1 - Ziepprecht, Kathrin A1 - Hofmann, Judith A1 - Kramer, Charlotte A1 - Müller, Britta-Kornelia A1 - Rohde, Andreas A1 - Zühlsdorf, Felix A1 - Winkler, Iris A1 - Laging, Ralf A1 - Peter, Carina A1 - Schween, Michael A1 - Härle, Gerhard A1 - Busse, Beatrix A1 - Mahner, Sebastian A1 - Köstler, Verena A1 - Kufner, Sabrina A1 - Mägdefrau, Jutta A1 - Müller, Christian A1 - Beck, Christina A1 - Kriehuber, Eva A1 - Boch, Florian A1 - Engl, Anna-Teresa A1 - Helzel, Andreas A1 - Pickert, Tina A1 - Reiter, Christian A1 - Blasini, Bettina A1 - Nerdel, Claudia A1 - Lewalter, Doris A1 - Schiffhauer, Silke A1 - Richter-Gebert, Jürgen A1 - Bannert, Maria A1 - Maahs, Mirjam A1 - Reißner, Maria A1 - Ungar, Patrizia A1 - von Wachter, Jana-Kristin A1 - Hellmann, Katharina A1 - Zaki, Katja A1 - Pohlenz, Philipp ED - Glowinski, Ingrid ED - Borowski, Andreas ED - Gillen, Julia ED - Schanze, Sascha ED - von Meien, Joachim T1 - Kohärenz in der universitären Lehrerbildung T1 - Coherence in teacher education at university BT - Vernetzung von Fachwissenschaft, Fachdidaktik und Bildungswissenschaften BT - linking studies in content knowledge, pedagogical content knowledge and pedagogical knowledge in teacher education N2 - One area that is supported by the project “Qualitätsoffensive Lehrerbildung” (funded by BMBF) is the improvement of collaboration and coordination between studies in the discipline, studies in pedagogical content knowledge, and studies in pedagogical knowledge during teacher education at university. Aiming a better coordination among these three parts of teacher education at university, many of the supported projects have designed and realized university-specific approaches. This conference proceedings volume comprises contributions by 15 of these projects. Seven of those were introduced and discussed in workshops on the occasion of two cross-regional project-conferences in Hannover and Potsdam. Overall, the contributions give a theoretically funded as well as a practice-oriented overview of current approaches and concepts to achieve a better connection between study units concerning studies in content knowledge, pedagogical content knowledge and pedagogical knowledge in teacher education. The volume presents university projects, which take effect on different levels (at the level of curriculum and content, at a collegiate level, at the level of structural conditions of universities). The different approaches are described in a way that they can provide a basis for transfer to other subjects or further universities. The contributions are aimed at teacher educators as well as other actors working in the field of teaching- and quality development at universities. All of them can take transferable ideas and impulses from the described concepts and formats. N2 - Eine verbesserte Zusammenarbeit und Abstimmung von Fachwissenschaft, Fachdidaktik, Bildungswissenschaften und schulpraktischen Lernorten ist einer der Förderbereiche der „Qualitätsoffensive Lehrerbildung“. Zahlreiche der geförderten Projekte haben für dieses Handlungsfeld im Bereich Vernetzung von Fachwissenschaft, Fachdidaktik und Bildungswissenschaften hochschulspezifische Maßnahmen konzipiert und umgesetzt. Der vorliegende Tagungsband beinhaltet Beiträge von 15 entsprechenden Projekten, von denen sieben anlässlich von zwei standortübergreifenden Projekt-Tagungen in Hannover und Potsdam vorgestellt und in Workshops diskutiert wurden. Insgesamt geben die Beiträge einen theoretisch fundierten und gleichzeitig praxisorientierten Überblick über aktuelle Ansätze und Konzepte zur besseren Vernetzung fachwissenschaftlicher, fachdidaktischer und bildungswissenschaftlicher Studienanteile im Lehramtsstudium. Dargestellt werden Projektarbeiten der Hochschulen, die auf verschiedenen Ebenen wirksam werden (curricular-inhaltliche Ebene, kollegiale Ebene, hochschul-strukturelle Ebene). Die Maßnahmen sind so beschrieben, dass sie als Grundlage für einen Transfer auf andere Fächer bzw. andere Standorte genutzt werden können. Die Beiträge richten sich an alle Lehrenden im Bereich der Lehramtsbildung sowie sonstige Akteure im Bereich der Lehr- und Qualitätsentwicklung an den Universitäten. Sie alle können den beschriebenen Konzepten und Umsetzungsformaten transferierbare Ideen und Impulse entnehmen. KW - Professionswissen KW - universitäre Lehrerbildung KW - Vernetzung Fachwissenschaft KW - Fachdidaktik KW - Bildungswissenschaft KW - Lehramtsstudium KW - teacher education KW - professional knowledge KW - content knowledge KW - pedagogical content knowledge Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-414267 SN - 978-3-86956-438-8 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Richter, Philipp A1 - Fox, Andrew J. A1 - Wakker, Bart P. A1 - Howk, J. Christopher A1 - Lehner, Nicolas A1 - Barger, Kathleen A. A1 - Lockman, Felix J. T1 - New constraints on the nature and origin of the leading arm of the magellanic stream JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We present a new precision measurement of gas-phase abundances of S, O, N, Si, Fe, P, Al, Ca as well as molecular hydrogen (H-2) in the Leading Arm (region II, LA II) of the Magellanic Stream (MS) toward the Seyfert galaxy NGC 3783. The results are based on high-quality archival ultraviolet/optical/radio data from various different instruments (HST/STIS, FUSE, AAT, GBT, GB140 ft, ATCA). Our study updates previous results from lower-resolution data and provides for the first time a self-consistent component model of the complex multiphase absorber, delivering important constraints on the nature and origin of LA II. We derive a uniform, moderate a abundance in the two main absorber groups at +245 and +190 km s(-1) of alpha/H = 0.30 +/- 0.05 solar, a low nitrogen abundance of N/H = 0.05 +/- 0.01 solar, and a high dust content with substantial dust depletion values for Si, Fe, Al, and Ca. These a, N, and dust abundances in LA II are similar to those observed in the Small Magellanic Cloud (SMC). From the analysis of the H2 absorption, we determine a high thermal pressure of P/k approximate to 1680 K cm(-3) in LA II, in line with the idea that LA II is located in the inner Milky Way halo at a z-height of < 20 kpc, where it hydrodynamically interacts with the ambient hot coronal gas. Our study supports a scenario in which LA II stems from the breakup of a metal- and dust-enriched progenitor cloud that was recently (200-500 Myr ago) stripped from the SMC. KW - Galaxy: evolution KW - Galaxy: halo KW - ISM: abundances KW - Magellanic Clouds KW - quasars: absorption lines Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aadd0f SN - 0004-637X SN - 1538-4357 VL - 865 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Fox, Andrew J. A1 - Richter, Philipp A1 - Ashley, Trisha A1 - Heckman, Timothy M. A1 - Lehner, Nicolas A1 - Werk, Jessica K. A1 - Bordoloi, Rongmon A1 - Peeples, Molly S. T1 - The Mass Inflow and Outflow Rates of the Milky Way JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We present new calculations of the mass inflow and outflow rates around the Milky Way (MW), derived from a catalog of ultraviolet metal-line high-velocity clouds (HVCs). These calculations are conducted by transforming the HVC velocities into the Galactic standard of rest (GSR) reference frame, identifying inflowing (vGSR.<.0 km s(-1)) and outflowing (vGSR > 0 km s(-1)) populations, and using observational constraints on the distance, metallicity, dust content, covering fractions, and total silicon column density of each population. After removing HVCs associated with the Magellanic Stream and the Fermi Bubbles, we find inflow and outflow rates in cool (T similar to 10(4) K) ionized gas of dM(in)/dt greater than or similar to.(0.53 +/- 0.23)(d/12 kpc)(Z/0.2Z(circle dot))-1M(circle dot) yr(-1) and dM(out)/dt greater than or similar to (0.16 +/- 0.07)(d/12 kpc)(Z/0.5Z(circle dot))M--1(circle dot) yr(-1). The apparent excess of inflowing over outflowing gas suggests that the MW is currently in an inflow-dominated phase, but the presence of substantial mass flux in both directions supports a Galactic fountain model, in which gas is constantly recycled between the disk and the halo. We also find that the metal flux in both directions (in and out) is indistinguishable. By comparing the outflow rate to the Galactic star formation rate, we present the first estimate of the mass loading factor (eta(HVC)) of the disk-wide MW wind, finding eta(HVC) greater than or similar to (0.10 +/- 0.06)(d/12 kpc)(Z/0.5Z(circle dot))(-1). Including the contributions from low- and intermediatevelocity clouds and from hot gas would increase these inflow and outflow estimates. Y1 - 2019 U6 - https://doi.org/10.3847/1538-4357/ab40ad SN - 0004-637X SN - 1538-4357 VL - 884 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Zhang, Heshou A1 - Yan, Huirong A1 - Richter, Philipp T1 - The influence of atomic alignment on absorption and emission spectroscopy JF - Monthly notices of the Royal Astronomical Society N2 - Spectroscopic observations play essential roles in astrophysics. They are crucial for determining physical parameters in our Universe, providing information about the chemistry of various astronomical environments. The proper execution of the spectroscopic analysis requires accounting for all the physical effects that are compatible to the signal-to-noise ratio. We find in this paper the influence on spectroscopy from the atomic/ground state alignment owing to anisotropic radiation and modulated by interstellar magnetic field, has significant impact on the study of interstellar gas. In different observational scenarios, we comprehensively demonstrate how atomic alignment influences the spectral analysis and provide the expressions for correcting the effect. The variations are even more pronounced for multiplets and line ratios. We show the variation of the deduced physical parameters caused by the atomic alignment effect, including alpha-to-iron ratio ([X/Fe]) and ionization fraction. Synthetic observations are performed to illustrate the visibility of such effect with current facilities. A study of Photodissociation regions in rho Ophiuchi cloud is presented to demonstrate how to account for atomic alignment in practice. Our work has shown that due to its potential impact, atomic alignment has to be included in an accurate spectroscopic analysis of the interstellar gas with current observational capability. KW - magnetic fields KW - submillimetre: ISM KW - ultraviolet: ISM KW - ISM: abundances KW - ISM: lines and bands KW - techniques: spectroscopic Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty1594 SN - 0035-8711 SN - 1365-2966 VL - 479 IS - 3 SP - 3923 EP - 3935 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Guber, Christoph Rudolf A1 - Richter, Philipp A1 - Wendt, Martin T1 - Multiple origins for the DLA at zabs = 0.313 toward PKS 1127–145 indicated by a complex dust depletion pattern of Ca, Ti, and Mn JF - Astronomy and astrophysics : an international weekly journal N2 - Aims: We aim to investigate the dust depletion properties of optically thick gas in and around galaxies and its origin we study in detail the dust depletion patterns of Ti, Mn, and Ca in the multi-component damped Lyman alpha (DLA) absorber at z(abs) = 0.313 toward the quasar PKS 1127-145. Methods: We performed a detailed spectral analysis of the absorption profiles of Ca II, Mn II, TIII, and Na I associated with the DLA toward PKS 1127-145, based on optical high-resolution data obtained with the UVES instrument at the Very Large Telescope. We obtained column densities and Doppler-parameters for the ions listed above and determine their gas-phase abundances, from which we conclude on their dust depletion properties. We compared the Ca and Ti depletion properties of this DLA with that of other DLAs. Results: One of the six analyzed absorption components (component 3) shows a striking underabundance of Ti and Mn in the gas-phase, indicating the effect of dust depletion for these elements and a locally enhanced dust-to-gas ratio. In this DLA and in other similar absorbers, the Mn II abundance follows that of Ti II very closely, implying that both ions are equally sensitive to the dust depletion effects. Conclusions: Our analysis indicates that the DLA toward PKS 1127 145 has multiple origins. With its narrow line width and its strong dust depletion, component 3 points toward the presence of a neutral gas disk from a faint LSB galaxy in front of PKS 1127 145, while the other, more diffuse and dust-poor, absorption components possibly are related to tidal gas features from the interaction between the various, optically confirmed galaxy-group members. In general, the Mn/Ca II ratio in sub-DLAs and DLAs possibly serves as an important indicator to discriminate between dust-rich and dust-poor in neutral gas in and around galaxies. KW - quasars: absorption lines KW - galaxies: abundances KW - intergalactic medium KW - quasars: individual: PKS1127-145 KW - dust, extinction KW - ISM: kinematics and dynamics Y1 - 2018 U6 - https://doi.org/10.1051/0004-6361/201730984 SN - 1432-0746 VL - 609 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Fox, Andrew J. A1 - Barger, Kathleen A. A1 - Wakker, Bart P. A1 - Richter, Philipp A1 - Antwi-Danso, Jacqueline A1 - Casetti-Dinescu, Dana I. A1 - Howk, J. Christopher A1 - Lehner, Nicolas A1 - Crowther, Paul A. A1 - Lockman, Felix J. T1 - Chemical Abundances in the Leading Arm of the Magellanic Stream JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - The Leading Arm (LA) of the Magellanic Stream is a vast debris field of H I clouds connecting the Milky Way and the Magellanic Clouds. It represents an example of active gas accretion onto the Galaxy. Previously, only one chemical abundance measurement had been made in the LA. Here we present chemical abundance measurements using Hubble Space Telescope/Cosmic Origins Spectrograph and Green Bank Telescope spectra of four AGN sightlines passing through the LA and three nearby sightlines that may trace outer fragments of the LA. We find low oxygen abundances, ranging from 4.0+(2.0)(2.0)% 12.6(4.1)(6.0)% solar, in the confirmed LA directions, with the lowest values found in the region known as LA III, farthest from the LMC. These abundances are substantially lower than the single previous measurement, S/H = 35 +/- 7% solar, but are in agreement with those reported in the SMC filament of the trailing Stream, supporting a common origin in the SMC (not the LMC) for the majority of the LA and trailing Stream. This provides important constraints for models of the formation of the Magellanic System. Finally, two of the three nearby sightlines show high-velocity clouds with H I columns, kinematics, and oxygen abundances consistent with LA membership. This suggests that the LA is larger than traditionally thought, extending at least 20 degrees further to the Galactic northwest. KW - Galaxy: evolution KW - Galaxy: halo KW - ISM: abundances KW - Magellanic Clouds KW - quasars: absorption lines Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aaa9bb SN - 0004-637X SN - 1538-4357 VL - 854 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Rauch, Thomas A1 - Quinet, P. A1 - Hoyer, D. A1 - Werner, K. A1 - Richter, Philipp A1 - Kruk, J. W. A1 - Demleitner, M. T1 - VII. New Kr IV - VII oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289 JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. New Kr IV-VII oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods. We calculated Kr IV-VII oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. Results. We reanalyzed the effective temperature and surface gravity and determined T-eff = 70 000 +/- 2000 K and log (g/cm s(-2)) = 7.5 +/- 0.1. We newly identified ten Kr V lines and one Kr vi line in the spectrum of RE 0503-289. We measured a Kr abundance of 3.3 +/- 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km s(-1) < upsilon(rad) < +18 km s(-1). Conclusions. Reliable measurements and calculations of atomic data are a prerequisite for state-of-the-art NLTE stellar-atmosphere modeling. Observed Kr V-VII line profiles in the UV spectrum of the white dwarf RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. KW - atomic data KW - line: identification KW - stars: abundances KW - stars: individual: RE 0503-289 KW - virtual observatory tools KW - stars: individual: RE 0457-281 Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201628131 SN - 1432-0746 VL - 590 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Richter, Philipp A1 - de Boer, Klaas S. A1 - Werner, Klaus A1 - Rauch, Thomas T1 - High-velocity gas toward the LMC resides in the Milky Way halo JF - Astronomy and astrophysics : an international weekly journal N2 - Aims. To explore the origin of high-velocity gas in the direction of the Large Magellanic Cloud, (LMC) we analyze absorption lines in the ultraviolet spectrum of a Galactic halo star that is located in front of the LMC at d = 9.2(-7.2)(+4.1) kpc distance. Methods. We study the velocity-component structure of low and intermediate metal ions (CII, SiII, SiIII) in the spectrum of RXJ0439.8-6809, as obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST), and measure equivalent widths and column densities for these ions. We supplement our COS data with a Far-Ultraviolet Spectroscopic Explorer (FUSE) spectrum of the nearby LMC star Sk-69 59 and with Hi 21 cm data from the Leiden-Argentina-Bonn (LAB) survey. Results. Metal absorption toward RXJ0439.8-6809 is unambiguously detected in three different velocity components near v(LSR) = 0, + 60, and + 150 km s(-1). The presence of absorption proves that all three gas components are situated in front of the star, thus located in the disk and inner halo of the Milky Way. For the high-velocity cloud (HVC) at v(LSR) = + 150 km s(-1), we derive an oxygen abundance of [O/H] = -0.63 (similar to 0.2 solar) from the neighboring Sk-69 59 sight line, in accordance with previous abundance measurements for this HVC. From the observed kinematics we infer that the HVC hardly participates in the Galactic rotation. Conclusions. Our study shows that the HVC toward the LMC represents a Milky Way halo cloud that traces low column density gas with relatively low metallicity. We rule out scenarios in which the HVC represents material close to the LMC that stems from a LMC outflow. KW - Galaxy: halo KW - Galaxy: evolution KW - ISM: abundances KW - ISM: structure Y1 - 2015 U6 - https://doi.org/10.1051/0004-6361/201527451 SN - 1432-0746 VL - 584 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Bouma, Sietske Jeltje Deirdre A1 - Richter, Philipp A1 - Wendt, Martin T1 - The relation between Ly alpha absorbers and local galaxy filaments JF - Astronomy and astrophysics : an international weekly journal N2 - Context. The intergalactic medium (IGM) is believed to contain the majority of baryons in the universe and to trace the same dark matter structure as galaxies, forming filaments and sheets. Ly alpha absorbers, which sample the neutral component of the IGM, have been extensively studied at low and high redshift, but the exact relation between Ly alpha absorption, galaxies, and the large-scale structure is observationally not well constrained.Aims. In this study, we aim at characterising the relation between Ly alpha absorbers and nearby over-dense cosmological structures (galaxy filaments) at recession velocities Delta v <= 6700 km s(-1) by using archival observational data from various instruments.Methods. We analyse 587 intervening Ly alpha absorbers in the spectra of 302 extragalactic background sources obtained with the Cosmic Origins Spectrograph (COS) installed on the Hubble Space Telescope (HST). We combine the absorption line information with galaxy data of five local galaxy filaments from the V8k catalogue.Results. Along the 91 sightlines that pass close to a filament, we identify 215 (227) Ly alpha absorption systems (components). Among these, 74 Ly alpha systems are aligned in position and velocity with the galaxy filaments, indicating that these absorbers and the galaxies trace the same large-scale structure. The filament-aligned Ly alpha absorbers have a similar to 90% higher rate of incidence (d?/dz=189 for log N(HI) >= 13.2) and a slightly shallower column density distribution function slope (-beta=-1.47) relative to the general Ly alpha population at z=0, reflecting the filaments' matter over-density. The strongest Ly alpha absorbers are preferentially found near galaxies or close to the axis of a filament, although there is substantial scatter in this relation. Our sample of absorbers clusters more strongly around filament axes than a randomly distributed sample would do (as confirmed by a Kolmogorov-Smirnov test), but the clustering signal is less pronounced than for the galaxies in the filaments. KW - galaxies: halos KW - intergalactic medium KW - quasars: absorption lines KW - large-scale structure of Universe KW - techniques: spectroscopic KW - ultraviolet: general Y1 - 2021 U6 - https://doi.org/10.1051/0004-6361/202039786 SN - 0004-6361 SN - 1432-0746 VL - 647 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Richter, Philipp T1 - Hot gas in galaxy halos traced by coronal broad Lyα absorbers JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We explore the possibility to systematically study the extended, hot gaseous halos of low-redshift galaxies with coronal broad Lya absorbers (CBLAs). These are weak, thermally broadenend H I absorption lines arising from the tiny fraction of neutral hydrogen that resides in the collisionally ionized, million-degree halo gas in these galaxies. Using a semi-analytic approach, we model the spatial density and temperature distribution of hot coronal gas to predict strength, spectral shape, and cross section of CBLAs as a function of galaxy-halo mass and line-of-sight impact parameter. For virial halo masses in the range log M M = 10.6 12.6, the characteristic logarithmic CBLA H I column densities and Doppler parameters are log N(H I) = 12.4- 13.4 and b(H I).=.70-200 km s-1, indicating that CBLAs represent weak, shallow spectral features that are difficult to detect. Yet, the expected number density of CBLAs per unit redshift in the above given mass range is d. dz(CBLA). 3, implying that CBLAs have a substantial absorption cross section. We compare the model predictions with a combined set of UV absorption-line spectra from the Hubble Space Telescope (HST)/Cosmic Origins Spectrograph and HST/Space Telescope Imaging Spectrograph that trace the halos of four low-redshift galaxies. We demonstrate that CBLAs might already have been detected in these spectra, but the complex multi-component structure and the limited signal-to-noise ratio complicate the interpretation of these CBLA candidate systems. Our study suggests that CBLAs represent a very interesting absorber class that potentially will allow us to further explore the hot coronae of galaxies with UV spectral data. Y1 - 2020 U6 - https://doi.org/10.3847/1538-4357/ab7937 SN - 0004-637X SN - 1538-4357 VL - 892 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER -