Theory and practice of microlensing light curves around fold singularities     

M. Dominik 《Monthly notices of the Royal Astronomical Society》2004,353(1):69-86

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Can microlensing fold caustics reveal a second stellar limb-darkening coefficient?     

M. Dominik 《Monthly notices of the Royal Astronomical Society》2004,352(4):1315-1318

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Disintegration of dust aggregates in interstellar shocks and the lifetime of dust grains in the ISM     

C. Dominik  A. P. Jones  A. G. G. M. Tielens 《Astrophysics and Space Science》1995,233(1-2):155-159

We have studied to influence of grain porosity on the dust destruction mechanism in interstellar shocks. Our results show, that fluffy aggregates of dust grains can be broken up easily in shocks.  相似文献   

Bioleaching potential of bacterial communities in historic mine waste areas     

Nida Amin  Dominik Schneider  Michael Hoppert 《Environmental Earth Sciences》2018,77(14):542

Microbial activity has the potential to alter all cultural heritage in mining and metallurgy, due to metal mobilization by leaching. This communication shows the consequences of the bioleaching ability of two natural enrichments on copper slag samples from a historic ore smelting site in Sangerhausen (Mansfeld, Südharz, Saxony-Anhalt, Germany). Enrichment cultures gained from mine drainage were dominated by either the iron and sulfur-oxidizing Acidithiobacillus ferrivorans, or by the iron-oxidizing Leptospirillum. During 35 days of bioleaching in media containing copper slag pulp, inoculated with these enrichments, the change in pH and solubilized metal concentrations of the systems were monitored. Both bacterial strains were completely different from each other in their pattern of pH variation and rates of metal solubilization. The maximum removal of Cu (1725 mg/l) and Zn (715 mg/l) from copper slag substrate was achieved with enrichment culture of A. ferrivorans SCUT-1. However, maximum Mn (207 mg/l), Pb (86 mg/l), and Ni (75 mg/l) removal was observed with enrichment culture of Leptospirillum strain YQP-1. Implications for metal mobilization along with alteration of artifacts from not only historic mining areas but also aspects of decontamination and remediation are discussed.  相似文献   

The Influence of Selected Meteorological Parameters on the Concentration of Surface Ozone in the Central Region of Poland     

Izabela Pawlak  Janusz Jarosławski 《大气与海洋》2015,53(1):126-139

Abstract?This paper presents the results of measurements of the concentration of surface ozone and concurrent standard meteorological parameters: total solar radiation, temperature, relative humidity, pressure, wind speed, and vertical and horizontal components of the wind. The data were collected from 2005 to 2010 at stations located in central Poland (Mazowieckie voivodeship): Warszawa (urban), Legionowo (suburban), Granica and Belsk (rural). Furthermore, Granica is situated in the forested area of Kampinoski National Park. Continuously measured surface ozone concentrations demonstrated the well-known diurnal cycle of surface ozone concentration with a maximum in the afternoon and a minimum in the early morning hours. The averaged diurnal variations over six years reveal that the highest concentrations appear at rural stations (Belsk: 55?µg?m^?3 and Granica: 50?µg?m^?3) and the lowest at the urban station (Warszawa: 41?µg?m^?3). The threshold for high levels of surface ozone (120?µg?m^?3 per 8?h) was exceeded most often at Granica and Belsk. The occurrence of the ozone “weekend effect,” especially at urban stations, has been identified. The difference between weekend and weekday surface ozone concentrations at urban and rural stations was as high as 6.5?µg?m^?3 and approximately 2?µg?m^?3, respectively. Using appropriate statistical tools, it has been shown that meteorological conditions have a significant influence on ozone concentration. High correlation coefficients were found between ozone concentration and solar radiation, temperature, relative humidity, and wind speed. The forward stepwise regression model explains up to 75% of the variations in daily surface ozone concentration in terms of meteorological variability in summer and up to 70% in winter. At the same time, a multilayer perceptron neural network model was used to reconstruct the concentration of surface ozone. High correlation coefficients (up to 0.89) indicate that, on the basis of standard meteorological parameters and NO₂ concentration, we can determine ozone concentration with high accuracy.  相似文献   

Adaptive contouring – an efficient way to calculate microlensing light curves of extended sources     

M. Dominik † 《Monthly notices of the Royal Astronomical Society》2007,377(4):1679-1688

The availability of a robust and efficient routine for calculating light curves of a finite source magnified due to bending of its light by the gravitational field of an intervening binary lens is essential for determining the characteristics of planets in such microlensing events, as well as for modelling stellar lens binaries and resolving the brightness profile of the source star. However, the presence of extended caustics, and the fact that the images of the source star cannot be determined analytically while their number depends on the source position (relative to the lens system), makes such a task difficult in general. Combining the advantages of several earlier approaches, an adaptive contouring algorithm is presented, which only relies on a small number of simple rules and operations on the adaptive search grid. By using the parametric representation of critical curves and caustics found by Erdl & Schneider, seed solutions to the adaptive grid are found, which ensures that no images or holes are missed.  相似文献   

Why can't we do better than Topmodel?     

Wouter Buytaert  Dominik Reusser  Stefan Krause  J.‐P. Renaud 《水文研究》2008,22(20):4175-4179

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The influence of climate,hydrology and permafrost on Holocene peat accumulation at 3500 m on the eastern Qinghai–Tibetan Plateau     

David J. Large  Baruch Spiro  Marion Ferrat  Michaela Shopland  Malin Kylander  Kerry Gallagher  Xiangdong Li  Chengde Shen  Goran Possnert  Gan Zhang  W. George Darling  Dominik Weiss 《Quaternary Science Reviews》2009,28(27-28):3303-3314

Peatland of the eastern Qinghai–Tibetan Plateau lies at the convergence of the East Asian and Indian monsoon systems in eastern Asia. To understand the evolution of this peatland and its potential to provide new insights into the Holocene evolution of the East Asian monsoon a 6 m peat core was collected from the undisturbed central part of a peat deposit near Hongyuan. The age-depth profile was determined using 16 ¹⁴C-AMS age dates, the peat analysed for a range of environmental variables including carbon, nitrogen and hydrogen concentration, bulk density, δ¹³C and the associated spring water analysed for hydrogen and oxygen isotopes. The age-depth profile of the recovered peat sequence covers the period from 9.6 to 0.3 kyr BP and is linear indicating that the conditions governing productivity and decay varied little over the Holocene. Using changes in carbon density, organic carbon content and its δ¹³C, cold dry periods of permafrost characterised by low density and impeded surface drainage were identified. The low δ¹⁸O and δD values of the spring water emanating around the peat deposit, down to ?13.8 and ?102‰ (VSMOW), respectively, with an inverse relationship between electrical conductivity and isotopic composition indicate precipitation under colder and drier conditions relative to the present day. In view of the current annual mean air temperature of 1 °C this suggests conditions in the past have been conducive to permafrost. Inferred periods of permafrost correspond to independently recognised cold periods in other Holocene records from across China at 8.6, 8.2–7.8, 5.6–4.2, 3.1 and 1.8–1.5 kyr BP. The transition to a cold dry climate appears to be more rapid than the subsequent recovery and cold dry periods at Hongyuan are of longer duration than equivalent cold dry periods over central and eastern China. Light–dark banding peat on a scale of 15–30 years from 9.6 to 5.5 kyr BP may indicate a strong influence of decadal oscillations possibly the Pacific Decadal Oscillation and a potential link between near simultaneous climatic changes in the northwest Pacific, ENSO, movement of the Intertropical Convergence Zone and the East Asian Monsoon.  相似文献   

Ferric/ferrous iron ratios in sodic amphiboles: Mössbauer analysis, stoichiometry-based model calculations and the high-resolution microanalytical flank method     

Michael Enders  Dominik Speer  Walter V. Maresch  Catherine A. McCammon 《Contributions to Mineralogy and Petrology》2000,140(2):135-147

Although the electron microprobe has become the standard microanalytical tool in modern geosciences, conventional electron microprobe analysis does not allow determination of the valence states of elements such as Fe. The correct classification of minerals and interpretation of reaction microfabrics and grain zonation require high-quality information on ferric/ferrous ratios on a scale of micrometers. The flank method developed by Höfer et?al. (1994, Eur J Mineral 6:407–418) has revived new interest in electron-induced X-ray-spectroscopy to resolve oxidation states in minerals with high spatial resolution. We have recharacterized well-documented sodic amphiboles of the glaucophane–ferroglaucophane–riebeckite–magnesioriebeckite series by electron probe microanalysis and combined the microanalytical data with ferric/ferrous ratios from Mössbauer spectroscopy, Li data from bulk ICP-AES analysis and H₂O data from bulk Karl–Fischer titration. The combination of microanalysis and high-quality analysis on the bulk materials results in a data set that allows comparison of model-based stoichiometric calculations and the calibration of the high-resolution flank method. The calibration obtained allows ferric/ferrous ratios to be determined within an error of ±5%. We have found it necessary to apply an empirical correction for absorption phenomena. The advantages of the method must be weighed against the complex calibration procedures necessary and thus the flank method will probably not find use as a routine method. However, in cases where high-resolution data in terms of valence state are needed, the flank method will provide useful data on ferric/ferrous ratios down to minimum FeO_total content of 6–8 wt%.  相似文献   

The power spectrum of SUSY-CDM on subgalactic scales     

Anne M. Green  Stefan Hofmann  Dominik J. Schwarz 《Monthly notices of the Royal Astronomical Society》2004,353(3):L23-L27

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