The Bochum Survey of the Southern Galactic Disk: II. Follow‐up measurements and multi‐filter photometry for 1323 square degrees monitored in 2010 – 2015     

M. Hackstein  Ch. Fein  M. Haas  M. Ramolla  F. Pozo Nuez  A. Barr Domínguez  L. Kaderhandt  K. Thomsch  N. Niedworok  Ch. Westhues  R. Chini 《Astronomische Nachrichten》2015,336(6):590-603

This paper is the second in a series describing the southern Galactic Disk Survey (GDS) performed at the Univer‐sitätssternwarte Bochum near Cerro Armazones in Chile. Haas et al. (2012, Paper I) presented the survey design and the characteristics of the observations and data. They identified ∼2200 variable stars in an area of 50 square degrees with more than 50 observations in 2011. Here we present the first complete version of the GDS covering all 268 fields with 1323 square degrees along the Galactic disk including revised data from Paper I. The individual fields were observed up to 272 times and comprise a maximum time span between September 2010 and May 2015. We detect a total of 64 151 variable sources, which are presented in a catalog including some of their properties and their light curves. A comparison with the International Variable Star Index (VSX) and All Sky Automated Survey (ASAS) indicates that 56794 of these sources are previously unknown variables. Furthermore, we present U, B, V, r ′, i ′, z ′ photometry for all sources within the GDS, resulting in a new multi‐color catalog of nearly 16×10⁶ sources detected in at least one filter. Both the GDS and the near‐infrared VISTA Variables in the Via Lactea survey (VVV) complement each other in the overlap area of about 300 square degrees enabling future comparison studies. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

A new method and a new instrument for the determination of the chronometer correction by means of radio time signals     

Th. de Haas 《Journal of Geodesy》1956,30(1):20-28

Summary On the initiative of ProfessorR. Roelofs of the Delft Technological University and the financial support of the ‘Delft's Hogeschoolfonds’, a study was undertaken by the author concerning the reception and the use of radio time signals for the precise determination of the chronometer correction. As a result of this study an entirely new method featuring visual presentation and electronic enlargement of second ticks as transmitted by radio station WWV, was developed. Owing to the international importance of the problem, further development and actual construction of the necessary electronic equipment were carried out under the auspices of the Netherlands National Geodetic Committee, resulting in the Time Signal Oscillograph (TSO), which has now been in experimental use at the Geodetic Institute of the Delft Technological University since August 1953. The accuracy achieved by the new method is of the order of 1/1000 second, while errors and uncertainties due to atmospheric and/or man-made interference with the reception of the radio time signals have been practically eliminated. Operation of the instrument can be carried out by technically non-skilled persons, and direct reading of the chronometer correction in milleseconds is obtained. No identification is given of any particular second tick; however, this can be readily obtained by means of the standard tone modulation periods of the WWV radio station.  相似文献   

Stable isotope indicators of movement and residency for brown shrimp (<Emphasis Type="Italic">Farfantepenaeus aztecus</Emphasis>) in coastal Louisiana marshscapes     

Brian Fry  Donald M. Baltz  Mark C. Benfield  John W. Fleeger  Arian Gace  Heather L. Haas  Zoraida J. Quiñones-Rivera 《Estuaries and Coasts》2003,26(1):82-97

Brown shrimp (Farfantepenaeus aztecus) are an important commercial aquatic species experiencing loss of inshore marsh nursery habitat in coastal Louisiana. To study inshore brown shrimp movements and identify aspects of essential habitat important for sustaining brown shrimp populations, we collected juvenile brown shrimp in April and May 2000, the time of annual maximum brown shrimp abundance, in a small 1-km² marsh area on the central Louisiana coast. Drop sampling showed average shrimp densities of 1.6–2.4 m⁻² in shallow marsh ponds and seining indicated lower densities of 0.5–0.9 m⁻² in nearby shallow channel and open bay sites. Smaller shrimp (< 50 mm) fed disproportionately on benthic diatoms and small harpacticoid copepods, while large shrimp fed more frequently on larger-bodied amphipods and tanaids. We developed novel chemical approaches to estimate patterns of shrimp residency and movement using carbon and nitrogen stable isotopic determinations. Resident shrimp had isotopic values similar to average foods and showed consistent isotopic spacings between fast and slow turnover tissues. Residency was highest (47–55%) in ponds and shallow channel habitats and much less in open bays and deep channels (4–27%). There was sparse evidence for dietary specialization among individull shrimp. The results support the view that small 10–20 mm postlarval and juvenile brown shrimp arriving in estuaries from offshore waters continue movement through sub-optimal habitats (deep channels and open bays), but exhibit much less movement once an optimal habitat (marsh ponds or shallow channel margins) is reached. This study also indicated that combining estimates of shrimp densities, residency, growth rate, and mortality allows evaluation of the importance of different habitat types for shrimp production. Shallow ponds that in many ways resemble fertile aquaculture ponds appear to be hot spots for brown shrimp production, and coastal preservation and restoration efforts should focus on these areas as important for sustaining shrimp fisheries.  相似文献   

Uncertainties in Facies Proportion Estimation I. Theoretical Framework: The Dirichlet Distribution     

André Haas  Philippe Formery 《Mathematical Geology》2002,34(6):679-702

To simulate geological models comprising several litho-types—or facies—we need first to estimate their proportions, which are often poorly known. The corresponding uncertainties can be modelled using a Bayesian approach for inverting the multinomial distribution. The result obtained is known as the Dirichlet distribution. It can be simulated by decomposition into independent conditional distributions. Application of the model is extended to the case of nonstationary proportions and, with some approximation, to the case of correlated spatial data. The mathematical developments presented in the appendices provide a more precise and general definition of the distribution, several decomposition formulae into independent variables, the determination of remarkable stability properties, and the resulting consequences for the conditional and marginal distributions.  相似文献   

Designing Monitoring Programs to Effectively Evaluate the Performance of Natural Attenuation     

Todd H. Wiedemeier  Patrick E. Haas 《Ground Water Monitoring & Remediation》2002,22(3):124-135

Natural attenuation processes affect the fate and transport of organic compounds in many hydrologic systems. Over the last several years, regulatory agencies and environmental professionals have come to recognize the importance of these natural processes in effecting contaminant attenuation. When they are shown to be protective of human health and the environment, and when a well-designed monitoring program is in place to document the efficiency of these processes, they can be a valuable component of site remediation strategies.  相似文献   

Variations in organic geochemistry and lithology of a carbonate sequence deposited in a backplatform basin (Triassic, Hungary)     

Magdolna Hetnyi  Alice Brukner-Wein  Csand Sajg  Jnos Haas  Mria Hmor-Vid  Zsuzsanna Sznt  Mria Tth 《Organic Geochemistry》2002,33(12)

The variations in the organic matter quantity and quality were studied with respect to the mineral composition of the carbonate sequences accumulated on a gentle slope (Zl-1 well) and at the toe of the slope (Rzt-1 well) located between a Late Triassic carbonate platform and a backplatform basin. Parallel variations observed in mineral composition and organic geochemical features of the successions appeared to be controlled by the change in climate and by sea-level fluctuations. The repetitive sea-level changes resulted in a variation in the carbonate-rich basin facies and in the mineralogically heterogenous slope and toe-of-slope ones. According to Rock Eval pyrolysis, organic petrography and carbon isotope ratios, the immature organic matter is of predominantly marine origin and composed of mainly liptinites in both of the studied boreholes. The results of the GC and GC/MS analyses of the saturated hydrocarbon fractions of bitumens together with the composition of kerogen pyrolysates reveal a predominant algal input with a minor variable bacterial and subordinate terrestrial contribution for the Rzt-1 borehole. In the Zl-1 borehole a significantly higher proportion of the bacterial biomass contributed to the organic precursors. The δ¹³C values and the composition of the kerogen pyrolysates together with the results of the maceral analysis and GC data suggest a relatively higher, but moderate, higher plant derived contribution in the slope facies and at the top of the toe-of-slope facies. The elementary composition of kerogens and Rock Eval data display type II-S kerogen in the basin and the slope facies, and type I-II-S one in the toe-of-slope facies. Variations in the hydrogen content of the organic matter mainly reflect variations in the preservation conditions and in primary productivity. The presence of the 2,6,10,15,19-pentamethyleicosane and the extremely low pristane/phytane ratios indicate a relatively high methanogenic bacterial activity and strongly anoxic depositional conditions in the Rzt-1 well, especially in two most organic-rich toe-of-slope facies.  相似文献   

RAPTOR‐UAV: Real‐time particle tracking in rivers using an unmanned aerial vehicle          下载免费PDF全文

Philipp Thumser  Christian Haas  Jeffrey A. Tuhtan  Juan Francisco Fuentes‐Pérez  Gert Toming 《地球表面变化过程与地形》2017,42(14):2439-2446

River system measurement and mapping using UAVs is both lean and agile, with the added advantage of increased safety for the surveying crew. A common parameter of fluvial geomorphological studies is the flow velocity, which is a major driver of sediment behavior. Advances in fluid mechanics now include metrics describing the presence and interaction of coherent structures within a flow field and along its boundaries. These metrics have proven to be useful in studying the complex turbulent flows but require time‐resolved flow field data, which is normally unavailable in geomorphological studies. Contactless UAV‐based velocity measurement provides a new source of velocity field data for measurements of extreme hydrological events at a safe distance, and could allow for measurements of inaccessible areas. Recent works have successfully applied large‐scale particle image velocimetry (LSPIV) using UAVs in rivers, focusing predominantly on surficial flow estimation by tracking intensity differences between georeferenced images. The objective of this work is to introduce a methodology for UAV based real‐time particle tracking in rivers (RAPTOR) in a case study along a short test reach of the Brigach River in the German Black Forest. This methodology allows for large‐scale particle tracking velocimetry (LSPTV) using a combination of floating, infrared light‐emitting particles and a programmable embedded color vision sensor in order to simultaneously detect and track the positions of objects. The main advantage of this approach is its ability to rapidly collect and process the position data, which can be done in real time. The disadvantages are that the method requires the use of specialized light‐emitting particles, which in some cases cannot be retrieved from the investigation area, and that the method returns velocity data in unscaled units of px/s. This work introduces the RAPTOR system with its hardware, data processing workflow, and provides an example of unscaled velocity field estimation using the proposed method. First experiences with the method show that the tracking rate of 50 Hz allows for position estimation with sub‐pixel accuracy, even considering UAV self‐motion. A comparison of the unscaled tracks after Savitzky–Golay filtering shows that although the time‐averaged velocities remain virtually the same, the filter reduces the standard deviation by more than 40% and the maxima by 20%. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

FIB‐TEM analysis of cometary material in 10 Stardust foil craters     

Brendan A. Haas  Christine Floss  Rhonda M. Stroud  Ryan C. Ogliore 《Meteoritics & planetary science》2020,55(6):1349-1370

Aluminum foils from the Stardust cometary dust collector contain impact craters formed during the spacecraft's encounter with comet 81P/Wild 2 and retain residues that are among the few unambiguously cometary samples available for laboratory study. Our study investigates four micron‐scale (1.8–5.2 μm) and six submicron (220–380 nm) diameter craters to better characterize the fine (<1 μm) component of comet Wild 2. We perform initial crater identification with scanning electron microscopy, prepare the samples for further analysis with a focused ion beam, and analyze the cross sections of the impact craters with transmission electron microscopy (TEM). All of the craters are dominated by combinations of silicate and iron sulfide residues. Two micron‐scale craters had subregions that are consistent with spinel and taenite impactors, indicating that the micron‐scale craters have a refractory component. Four submicron craters contained amorphous residue layers composed of silicate and sulfide impactors. The lack of refractory materials in the submicron craters suggests that refractory material abundances may differentiate Wild 2 dust on the scale of several hundred nanometers from larger particles on the scale of a micron. The submicron craters are enriched in moderately volatile elements (S, Zn) when normalized to Si and CI chondrite abundances, suggesting that, if these craters are representative of the Wild 2 fine component, the Wild 2 fines were not formed by high‐temperature condensation. This distinguishes the comet's fine component from the large terminal particles in Stardust aerogel tracks which mostly formed in high‐temperature events.  相似文献   

Spitzer observations of M83 and the hot star, H ii region connection     

Robert H. Rubin  Janet P. Simpson  Sean W. J. Colgan  Reginald J. Dufour  Katherine L. Ray  Edwin F. Erickson  Michael R. Haas  Adalbert W. A. Pauldrach  Robert I. Citron 《Monthly notices of the Royal Astronomical Society》2007,377(4):1407-1418

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Concerning the Meteor Observed on January 30, 1868, which Fell thru the Atmosphere as a Shower of Stones at Pultusk in the Kingdom of Poland     

J. G. Galle  Walter H. Haas 《Meteoritics & planetary science》1944,3(10):124-128

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