Measurement of the angular correlation function of radio galaxies from the NRAO VLA Sky Survey     

Chris Blake  Jasper Wall 《Monthly notices of the Royal Astronomical Society》2002,329(2):37-41

We quantify the angular distribution of radio sources in the NRAO VLA Sky Survey (NVSS) by measuring the two-point angular correlation function w ( θ ). By careful consideration of the resolution of radio galaxies into multiple components, we are able to determine both the galaxy angular clustering and the size distribution of giant radio galaxies. The slope of the correlation function for radio galaxies agrees with that for other classes of galaxy,     , with a 3D correlation length     (under certain assumptions). Calibration problems in the survey prevent clustering analysis below     . About 7 per cent of radio galaxies are resolved by NVSS into multiple components, with a power-law size distribution. Our work calls into question previous analyses and interpretations of w ( θ ) from radio surveys.  相似文献   

LEGRI instrument health. A historical review     

Julia Suso  Pere Blay  Almudena Robert  Victor Reglero  Chris J. Eyles 《Astrophysics and Space Science》2001,276(1):299-309

LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously receivedfor nearly two years by LEGRI SOC in Valencia, and subsequently checked on adaily basis and then stored for long term monitoring analysis.LEGRI HouseKeeping data include three critical operating parameters:temperature, power and polarisation voltages. Six temperature sensors arespread over the different LEGRI units: Detector Unit, Data Processing Unit,High Voltage Unit and Star Sensor. Voltages are measured at eight differentpoints. Detector Unit temperature and polarisation voltage are thecritical parameters for LEGRI operation. Solid state detectors aresensitive to changes not only in polarisation but also in temperature.Around one and a half million of measurements for each of the HK fourteen parameters have been recorded and analysed. The data show a very remarkablestability, within the expected margins, and the averages are very close to theoptimal design values. Special attention has been paid to the detectorpolarisation voltages analysis with a mean value of 286 ± 2 V when the detectors are operating. Thermal control over all the LEGRI units shows a remarkable stability in their temperatures.On the detector plane a mean value of T _det = 13 ± 2 ^°C has been found.We can therefore conclude that LEGRI as a system has been operating withinits optimal design conditions. We also want to point out the excellentperformance of the MINISAT-01 thermal control system.  相似文献   

The 2dF Galaxy Redshift Survey: the environmental dependence of galaxy star formation rates near clusters     

Ian Lewis  Michael Balogh  Roberto De Propris  Warrick Couch  Richard Bower  Alison Offer  Joss Bland-Hawthorn  Ivan K. Baldry  Carlton Baugh  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Chris Collins  Nicholas Cross  Gavin Dalton  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Edward Hawkins  Carole Jackson  Ofer Lahav  Stuart Lumsden  Steve Maddox  Darren Madgwick  Peder Norberg  John A. Peacock  Will Percival  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,334(3):673-683

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Glacial Lake Victoria,a high‐level Antarctic Lake inferred from lacustrine deposits in Victoria Valley     

Brenda L. Hall  George H. Denton  Bret Overturf  Chris H. Hendy 《第四纪科学杂志》2002,17(7):697-706

We present evidence of a large lake (Glacial Lake Victoria) that existed in Victoria Valley in the dry valleys region of Antarctica between at least 20 000 and 8600 ¹⁴C yr BP. At its highstands, Glacial Lake Victoria covered 100 km² and was ca. 200 m deep. The chronology for lake‐level changes comes from 87 AMS radiocarbon dates of lacustrine algae preserved in deltas and glaciolacustrine deposits that extend up to 185 m above present‐day lakes on the valley floor. The existence of Glacial Lake Victoria, as well as other large lakes in the dry valleys, indicates a climate regime significantly different from that of today at the last glacial maximum and in the early Holocene. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Galaxy groups in the Two-degree Field Galaxy Redshift Survey: the luminous content of the groups     

V. R. Eke  Carlos S. Frenk  Carlton M. Baugh  Shaun Cole  Peder Norberg  John A. Peacock  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 A. Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve J. Maddox  Darren Madgwick  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,355(3):769-784

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A visibility-based assessment of tsunami evacuation signs in Seaside,Oregon     

Chris Lonergan  Nick Hedley  John J. Clague 《Natural Hazards》2015,76(1):41-61

Tsunami risk mitigation programs often include iconic evacuation signage to direct locals and visitors to safety during a tsunami event. This paper examines sign placement in Seaside, Oregon, from a visibility perspective. It leverages existing visibility analysis methodologies characterize the visibility of the community’s evacuation signage and reveals patterns in the viewable landscape. Additionally, we develop a topologically 3D approach to visibility analysis using raw LiDAR datasets. This applied work situates a discussion on existing patterns of visibility, how to improve existing signage placement, 2D and 3D representation of landscape, and the importance of visibility analysis. This work aims to stimulate discussion and development of hazard research that incorporates a visibility perspective.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114001601   总被引：3，自引：2，他引：1  

Tim E.Johnson  Chris Clark  Richard J.M.Taylor  M.Santosh  Alan S.Collins 《地学前缘(英文版)》2015,6(3):373-387

Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure-temperature-time[P-T-t) evolution of the Nagercoil Block at the southernmost tip of peninsular India.An inferred peak metamorphic assemblage of garnet,K-feldspar.sillimanite,plagioclase,magnetite,ilmenite,spinel and melt is consistent with peak metamorphic pressures of 6-8 kbar and temperatures in excess of 900℃.Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 C.SHRIMP U-Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages.New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation,and the minimum age of the metamorphic peak,to around560 Ma.The data suggest two stages of monazite growth.The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite.Relatively REE-depleted rims,which have a pronounced negative europium anomaly,grew during melt crystallisation along the retrograde path at around 535 Ma.Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer,supporting a long-lived high-grade metamorphic history.The metamorphic conditions,timing and duration of the implied clockwise P-T-t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent.  相似文献   

Editorial     

Chris Gibson 《The Australian geographer》2015,46(3):297-298

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The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques   总被引：1，自引：1，他引：0  

Philip L. Woodworth  Médéric Gravelle  Marta Marcos  Guy Wöppelmann  Chris W. Hughes 《Journal of Geodesy》2015,89(8):811-827

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Unravelling the complexities in high-grade rocks using multiple techniques: the Achankovil Zone of southern India     

Richard J. M. Taylor  Chris Clark  Tim E. Johnson  M. Santosh  Alan S. Collins 《Contributions to Mineralogy and Petrology》2015,169(5):1-19

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