The 2dF Galaxy Redshift Survey: galaxy clustering per spectral type     

Darren S. Madgwick  Ed Hawkins  Ofer Lahav  Steve Maddox  Peder Norberg  John A. Peacock  Ivan K. Baldry  Carlton M. Baugh  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Carole Jackson  Ian Lewis  Stuart Lumsden  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2003,344(3):847-856

  相似文献   

A maximum-likelihood approach to removing radio sources from observations of the Sunyaev–Zel'dovich effect, with application to Abell 611     

William F. Grainger  Rhiju Das†  Keith Grainge  Michael E. Jones  Rüdiger Kneissl  G. G. Pooley  Richard D. E. Saunders 《Monthly notices of the Royal Astronomical Society》2002,337(4):1207-1214

  相似文献   

The 2dF Galaxy Redshift Survey: the population of nearby radio galaxies at the 1-mJy level     

Manuela Magliocchetti  Steve J. Maddox  Carole A. Jackson  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto de Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Ofer Lahav  Ian Lewis  Stuart Lumsden  John A. Peacock  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,333(1):100-120

  相似文献   

The 2dF Galaxy Redshift Survey: the clustering of galaxy groups     

Nelson D. Padilla  Carlton M. Baugh  Vincent R. Eke  Peder Norberg  Shaun Cole  Carlos S. Frenk  Darren J. Croton  Ivan K. Baldry  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Karl Glazebrook  Carole Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve Maddox  Darren Madgwick  John A. Peacock  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,352(1):211-225

  相似文献   

Discussion of "A Challenge to the Consulting Environment," by Mark D. Varljen, Ground Water Monitoring and Remediation, v. 14, no. 3, pages 105–6, Summer 1994.     

Will Focht 《Ground Water Monitoring & Remediation》1995,15(1):150-150

  相似文献   

San Quintín volcanic field, Baja California, Mexico: 'within-plate' magmatism following ridge subduction     

M. Storey  G. Rogers  A.D. Saunders  D.J. Terrell 《地学学报》1989,1(2):195-202

The Holocene San Quintín volcanic province in northern Baja California comprises spinel-lherzolite-bearing alkali basalts. Trace element (La/Nb = 0.57–0.73; K/Rb = 402–479; La_N/Yb_N= 8.4, 9.9) and isotopic ratios (⁸⁷Sr/⁸⁶r = 0.70323–0.70352; ¹⁴³Nd/¹⁴⁴Nd = 0.512924–0.512996; ²⁰⁶Pb/²⁰⁴Pb = 19.108, 19.250; ²⁰⁷Pb/²⁰⁴Pb = 15.567, 15.589; ²⁰⁸Pb/²⁰⁴Pb = 38.82, 38.85) show that the lavas are compositionally indistinguishable from some ocean island, plume-associated basalts such as Hawaii and the Azores, and testify to an asthenospheric source for the magmas. The occurrence in Baja of such lavas may be related to the nature of the cessation of plate subduction beneath the peninsula; at present, San Quintín (and volcanic provinces to the north) are underlain by a 'no-slab window', whereas immediately to the south, remanent oceanic lithosphere may be preserved as a relict slab. This may act as a bamer to the upward passage of diapirs or magmas from the asthenosphere.  相似文献   

Matching authority and VGI road networks using an extended node-based matching algorithm     

Ehsan Abdolmajidi  Ali Mansourian  Julian Will  Lars Harrie 《地球空间信息科学学报》2013,16(2-3):65-80

The amount of volunteered geographic information (VGI) has increased over the past decade, and several studies have been conducted to evaluate the quality of VGI data. In this study, we evaluate the completeness of the road network in the VGI data set OpenStreetMap (OSM). The evaluation is based on an accurate and efficient network-matching algorithm. The study begins with a comparison of the two main strategies for network matching: segment-based and node-based matching. The comparison shows that the result quality is comparable for the two strategies, but the node-based result is considerably more computationally efficient. Therefore, we improve the accuracy of node-based algorithm by handling topological relationships and detecting patterns of complicated network components. Finally, we conduct a case study on the extended node-based algorithm in which we match OSM to the Swedish National Road Database (NVDB) in Scania, Sweden. The case study reveals that OSM has a completeness of 87% in the urban areas and 69% in the rural areas of Scania. The accuracy of the matching process is approximately 95%. The conclusion is that the extended node-based algorithm is sufficiently accurate and efficient for conducting surveys of the quality of OSM and other VGI road data sets in large geographic regions.  相似文献   

Testing Stokes-Helmert geoid model computation on a synthetic gravity field: experiences and shortcomings     

Petr Vaníček  Robert Kingdon  Michael Kuhn  Artu Ellmann  Will E. Featherstone  Marcelo C. Santos  Zdeněk Martinec  Christian Hirt  David Avalos-Naranjo 《Studia Geophysica et Geodaetica》2013,57(3):369-400

We report on testing the UNB (University of New Brunswick) software suite for accurate regional geoid model determination by use of Stokes-Helmert’s method against an Australian Synthetic Field (ASF) as “ground truth”. This testing has taken several years and has led to discoveries of several significant errors (larger than 5mm in the resulting geoid models) both in the UNB software as well as the ASF. It was our hope that, after correcting the errors in UNB software, we would be able to come up with some definite numbers as far as the achievable accuracy for a geoid model computed by the UNB software. Unfortunately, it turned out that the ASF contained errors, some of as yet unknown origin, that will have to be removed before that ultimate goal can be reached. Regardless, the testing has taught us some valuable lessons, which we describe in this paper. As matters stand now, it seems that given errorless gravity data on 1′ by 1′ grid, a digital elevation model of a reasonable accuracy and no topographical density variations, the Stokes-Helmert approach as realised in the UNB software suite is capable of delivering an accuracy of the geoid model of no constant bias, standard deviation of about 25 mm and a maximum range of about 200 mm. We note that the UNB software suite does not use any corrective measures, such as biases and tilts or surface fitting, so the resulting errors reflect only the errors in modelling the geoid.  相似文献   

Palaeoecological tools for improving the management of coastal ecosystems: a case study from Lake King (Gippsland Lakes) Australia   总被引：2，自引：0，他引：2  

Krystyna M. Saunders  Dominic A. Hodgson  Jennifer Harrison  Andrew McMinn 《Journal of Paleolimnology》2008,40(1):33-47

Since European settlement began over 200 years ago, many southeast Australian coastal lakes and lagoons have experienced substantial human impacts, including nutrient enrichment. Present day management and conservation efforts are often hampered by a lack of data on pre-impact conditions. We used a palaeoecological approach at Lake King, Gippsland Lakes, southeast Australia in order to determine its pre-impact condition and to establish the nature and direction of subsequent environmental changes, including responses to the construction of a permanent entrance to the sea in 1889. A 120 cm sediment core was analysed for diatoms, chlorophyll a, total carbon, nitrogen and sulphur, and dated using ²¹⁰Pb. Past phosphate and salinity concentrations were reconstructed using diatom-phosphate and diatom-salinity transfer functions developed from a calibration set based on 53 sites from 14 southeast Australian coastal lakes and lagoons. Results show changes in the diatom assemblage that record a shift from a brackish-water to marine diatom flora since construction of the permanent entrance. Phosphate concentrations increased at the same time and experienced major peaks in the 1940s and 1950s to >100 μg/l. Chlorophyll a concentrations were generally below 24 μg/l/gTOC in the core, but there has been a clear increase since the 1980s, peaking at 120 μg/l/gTOC, likely associated with a recorded increase in the frequency of nuisance algal blooms. These results indicate that the Lake King environment is now very different to that present during early European settlement. We conclude that by identifying the nature and direction of environmental change, palaeoecological studies can contribute towards developing realistic and well-informed management, conservation and restoration strategies in Australian coastal ecosystems.  相似文献   

Water distribution in Martian permafrost regions from joint analysis of HEND (Mars Odyssey) and MOLA (Mars Global Surveyor) data     

N. E. Demidov  W. V. Boynton  D. A. Gilichinsky  M. T. Zuber  A. S. Kozyrev  M. L. Litvak  I. G. Mitrofanov  A. B. Sanin  R. S. Saunders  D. E. Smith  V. I. Tretyakov  D. Hamara 《Astronomy Letters》2008,34(10):713-723

We jointly analyze data from the High-Energy Neutron Detector (HEND) onboard the NASA Mars Odyssey spacecraft and data from the Mars Orbiter Laser Altimeter (MOLA) onboard the Mars Global Surveyor spacecraft. The former instrument measures the content of hydrogen (in the form of H₂O or OH) in the subsurface layer of soil and the latter instrument measures the surface albedo with respect to the flux of solar energy. We have checked the presence of a correlation between these two data sets in various Martian latitude bands. A significant correlation has been found between these data at latitudes poleward of 40° in the northern hemisphere and at latitudes 40°–60° in the southern hemisphere. This correlation is interpreted as evidence for the presence of stable water ice in these regions under a dry layer of soil whose thickness is determined by the condition for equilibrium between the condensation of water from the atmosphere and its sublimation when heated by solar radiation. For these regions, we have derived an empirical relation between the flux of absorbed solar radiation and the thickness of the top dry layer. It allows the burial depth of the water ice table to be predicted with a sub-kilometer resolution based on near-infrared albedo measurements. We have found no correlation in the southern hemisphere at latitudes >60°, although neutron data also suggest that water ice is present in this region under a layer of dry soil. We conclude that the thickness of the dry layer in this region does not correspond to the equilibrium condition between the water ice table and the atmosphere.  相似文献