The discovery of two distant, massive clusters of galaxies in the ROSAT All-Sky Survey     

A. C. Edge  H. Ebeling  †  M. Bremer  H. Röttgering  M. P. van Haarlem  R. Rengelink  N. J. D. Courtney 《Monthly notices of the Royal Astronomical Society》2003,339(4):913-924

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The 2dF QSO Redshift Survey – X. Lensing of background QSOs by galaxy groups     

A. D. Myers  P. J. Outram  T. Shanks  B. J. Boyle  S. M. Croom  N. S. Loaring  L. Miller  R. J. Smith 《Monthly notices of the Royal Astronomical Society》2003,342(2):467-482

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Characters of the Pco2 and CO2 Flux in the East China Sea in Autumn     

纪雷  崔鹤  辛淑平  王军  张龙军  陆贤昆 《中国海洋湖沼学报》2003,21(2):180-186

Pco2 of air and seawater samples from the East China Sea(ECS) were measured in situ in autumn, 1994,Ocean currents,terrestrial fluviation,biological activities,etc.,Pco2 char-acters in air and seawater were investigated,CO2 flux and its character in the East China Sea are discussed on the basis of the Pco2 profiles of air and seawater,It was clear that the nearshore was the source of CO2;and tht the oulter sea area was the sink of CO2; and that the shelf area of the EXS is a net sink for atmospheric CO2 in autumn.  相似文献   

STUDY ON THE INTERACTION BETWEEN NDVI PROFILE AND THE GROWING STATUS OF CROPS   总被引：5，自引：1，他引：4  

JIANGDong WANGNai-bin YANGXIao-huan WANGJi-hua 《中国地理科学(英文版)》2003,13(1):62-65

Daily and ten-day Normalized Difference Vegetation Index(NDVI) of crops were retrieved from meteorological statellite NOAA AVHRR images ,The temporal variations of the NDVI were analyzed during the whole growing season,and thus the principle of the interaction between NDIV profile and the growing status of crops was discussed,As a case in point,the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed.By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination,scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield.These relation could be described with linear,cubic polynomial ,and exponential regression,and the cubic polynomial regression was the best way,In general ,NDVI reflects growing status of green vegetation ,so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.  相似文献   

Orbital periods of 22 subdwarf B stars     

L. Morales-Rueda  P. F. L. Maxted  T. R. Marsh  R. C. North  U. Heber 《Monthly notices of the Royal Astronomical Society》2003,338(3):752-764

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Large-scale structure in the NIR-selected MUNICS survey     

C.S. Botzler  J. Snigula  R. Bender  N. Drory  G. Feulner  G.J. Hill  U. Hopp  C. Maraston  C. Mendes de Oliveira 《Astrophysics and Space Science》2003,284(2):393-396

The Munich Near-IR Cluster Survey (MUNICS) is a wide-area, medium-deep, photometric survey selected in the K' band. The project's main scientific aims are the identification of galaxy clusters up to redshifts of unity and the selection of a large sample of field early-type galaxies up to z < 1.5 for evolutionary studies. We created a Large Scale Structure catalog, using a new structure finding technique specialized for photometric datasets, that we developed on the basis of a friends-of-friends algorithm. We tested the plausibility of the resulting galaxy group and cluster catalog with the help of Color-Magnitude Diagrams (CMD), as well as a likelihood- and Voronoi-approach. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

DISASTER ANALYSIS AND COUNTERMEASURES OF LAND SUBSIDENCE CAUSED BY COAL CUTTING IN CHINA     

YANGYong-liang SHITong-guang JLANGLU-guang LIYue 《中国地理科学(英文版)》2003,13(2):130-133

In recent years, many coal-producing countries have paid great attention to the land subsidence causedby coal cutting. In China, because of the dense population in coalfield areas, the land subsidence hazard is more seri-ous. After a brief analysis on the mechanism of land subsidence, this paper gives a comprehensive and systematical ac-count on all kinds of hazards caused by the land subsidence in China. The study shows that land subsidence has endan-gered land, buildings, traffic and communication lines, dykes and dams. It also causes damage to ecological and socialenvironment. In order to lessen the hazard of land subsidence, preventive measures should be taken to reduce the col-lapse amount, such as extraction with stowing, banded mining system, succession and coordination mining system, orhigh-pressure mudflow between rock strata. Measures of reinforcing or moving certain buildings should also be taken toreduce the destructive degree. In order to harness the subsidence land and bring them under control for fanning, mea-sures should be taken such as filling with spoil or fine breeze, excavating the deeper and covering the shallower land.  相似文献   

Laboratory studies of the interaction of carbon monoxide with water ice     

M.P. Collings  J.W. Dever  H.J. Fraser  M.R.S. McCoustra 《Astrophysics and Space Science》2003,285(3-4):633-659

The interaction of carbon monoxide (CO) with vapour-deposited water(H₂O) ices has been studied using temperature programmed desorption (TPD) and Fourier transform reflection-absorption infrared spectroscopy (FT-RAIRS) over a range of astrophysically relevant temperatures. Such measurements have shown that CO desorption from amorphous H₂Oices is a much more complex process than current astrochemical models suggest. Re-visiting previously reported laboratory experiments (Collings et al., 2003), a rate model has been constructed to explain, in a phenomenological manner, the desorption of CO over astronomically relevant time scales. The model presented here can be widely applied to a range of astronomical environments where depletion of CO from the gas phase is relevant. The model accounts for the two competing processes of CO desorption and migration, and also enables the entrapment of some of the CO in the ice matrix and its subsequent release as the water ice crystallises and then desorbs. The astronomical implications of this model are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Resonant and Secular Families of the Kuiper Belt     

Chiang  E. I.  Lovering  J. R.  Millis  R. L.  Buie  M. W.  Wasserman  L. H.  Meech  K. J. 《Earth, Moon, and Planets》2003,92(1-4):49-62

We review ongoing efforts to identify occupants of mean-motion resonances(MMRs) and collisional families in the Edgeworth–Kuiper belt. Directintegrations of trajectories of Kuiper belt objects (KBOs) reveal the 1:1(Trojan), 5:4, 4:3, 3:2 (Plutino), 5:3, 7:4, 9:5, 2:1 (Twotino), and 5:2 MMRsto be inhabited. Apart from the Trojan, resonant KBOs typically have largeorbital eccentricities and inclinations. The observed pattern of resonanceoccupation is consistent with resonant capture and adiabatic excitation bya migratory Neptune; however, the dynamically cold initial conditions priorto resonance sweeping that are typically assumed by migration simulationsare probably inadequate. Given the dynamically hot residents of the 5:2 MMRand the substantial inclinations observed in all exterior MMRs, a fraction ofthe primordial belt was likely dynamically pre-heated prior to resonancesweeping. A pre-heated population may have arisen as Neptune gravitationallyscattered objects into trans-Neptunian space. The spatial distribution of Twotinosoffers a unique diagnostic of Neptune's migration history. The Neptunian Trojanpopulation may rival the Jovian Trojan population, and the former's existence isargued to rule out violent orbital histories for Neptune. Finally, lowest-order seculartheory is applied to several hundred non-resonant KBOs with well-measured orbitsto update proposals of collisional families. No convincing family is detected.  相似文献   

In-Orbit Vignetting Calibrations of XMM-Newton Telescopes     

D. H. Lumb  A. Finoguenov  R. Saxton  B. Aschenbach  P. Gondoin  M. Kirsch  I. M. Stewart 《Experimental Astronomy》2003,15(2):89-111

We describe measurements of the mirror vignetting in the XMM-Newton Observatory made in-orbit, using observations of SNR G21.5-09 and SNR 3C58 with the EPIC imaging cameras. The instrument features that complicate these measurements are briefly described. We show the spatial and energy dependences of measured vignetting, outlining assumptions made in deriving the eventual agreement between simulation and measurement. Alternate methods to confirm these are described, including an assessment of source elongation with off-axis angle, the surface brightness distribution of the diffuse X-ray background, and the consistency of Coma cluster emission at different position angles. A synthesis of these measurements leads to a change in the XMM calibration data base, for the optical axis of two of the three telescopes, by in excess of 1 arcmin. This has a small but measureable effect on the assumed spectral responses of the cameras for on-axis targets. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献