Late Quaternary vegetation changes around Lake Rutundu,Mount Kenya,East Africa: evidence from grass cuticles,pollen and stable carbon isotopes     

Dr M. J. Wooller  D. L. Swain  K. J. Ficken  A. D. Q. Agnew  F. A. Street-Perrott  G. Eglinton 《第四纪科学杂志》2003,18(1):3-15

Woody, subalpine shrubs and grasses currently surround Lake Rutundu, Mount Kenya. Multiple proxies, including carbon isotopes, pollen and grass cuticles, from a 755‐cm‐long core were used to reconstruct the vegetation over the past 38 300 calendar years. Stable carbon‐isotope ratios of total organic carbon and terrestrial biomarkers from the lake sediments imply that the proportion of terrestrial plants using the C₄ photosynthetic pathway was greater during the Late Pleistocene than in the Holocene. Pollen data show that grasses were a major constituent of the vegetation throughout the Late Pleistocene and Holocene. The proportion of grass pollen relative to the pollen from other plants was greatest at the last glacial maximum (LGM). Grass cuticles confirm evidence that C₄ grass taxa were present at the LGM and that the majority followed the cold‐tolerant NADP‐MEC₄ subpathway. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Book Review     

A. D. Q. Agnew 《Journal of Arid Environments》2002,50(4):688

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U.S. Congress welcomes advice     

Allen F. Agnew 《Environmental Geology》1992,19(2):69-69

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DISCUSSION OF "Strip Mining and Water Pollution," by Moid U. Ahmad, Readers' Forum Section, September-October 1973 Issue, pp. 37-41     

Allen F. Agnew 《Ground water》1974,12(2):110-110

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Stacking for the frequencies and Qs of ₀S₀ and ₁S₀     

Mark A. Riedesel  Duncan Agnew  Jon Berger  Freeman Gilbert 《Geophysical Journal International》1980,62(2):457-471

Summary. Using nine IDA records for the Indonesian earthquake of 1977 August 19, we have formed an optimal linear combination of the records and have measured the frequency and Q of ₀ S ₀ and ₁ S ₀. The frequency was measured using the moment ratio method. The attenuation was measured by the minimum width method and by the time-lapse method. The frequency and attenuation were measured simultaneously by varying them to obtain a best fit to the data. A 2000-hr stack, the sum of nine individual records, for ₀ S ₀ gave a frequency of 0.814664 mHz±4 ppm. The values for the Q of ₀ S ₀ for the three different methods of measurement were 5600,5833 and 5700, respectively. The error in the estimates of Q ^-1 is about 5 per cent for the minimum power method. For ₁ S ₀ a 300-hr stack yielded a frequency of 1.63151 mHz±30 ppm. The values of Q for this mode were 1960, 1800 and 1850, respectively, with an error in Q ^-1 of about 12 per cent for the minimum power method.  相似文献   

Assessment of stone crab (Lithodidae) density on the South Georgia slope using baited video cameras   总被引：2，自引：0，他引：2  

Collins  M. A.; Yau  C.; Guilfoyle  F.; Bagley  P.; Everson  I.; Priede  I. G.; Agnew  D. 《ICES Journal of Marine Science》2002,59(2):370-379

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Mahafir: A water harvesting system in the Eastern Jordan (Badia) Eesert     

Clive T. Agnew  Ewan Anderson  W. Lancaster  F. Lancaster 《GeoJournal》1995,37(1):69-80

There are many different water harvesting systems in the Middle East and the operation of one type, the mahafir, was investigated in the Badia Region of Jordan. Mahafir are crescent and rectangular shaped excavations dug into the playa surface, now filled with sediment. Their previous volumes were estimated through topographical survey of the surrounding earth mounds. The average depth of the mahafir was found to be 3.2 m; storing a total water volume of 111,619 m³ at Maharouta and 55,005 m³ at Anka. The mahafir only occupy 4% of the playa surface and their source of water is primarily direct rainfall onto the playa surface augmented by runoff from adjacent slopes. Taking annual rainfalls as an input from 1963 to 1992 and even assuming rainfall harvesting is only 10% effective it appears that the full water storage potential of the mahafir could be met in most years.  相似文献   

NATIONAL WATER RESOURCES RESEARCH CENTER AND NATIONAL WATER RESOURCES INFORMATION CLEARINGHOUSE – A CONSIDERED VIEW     

Allen F. Agnew 《Ground water》1984,22(6):678-678

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Self-consistent equilibrium ocean tides   总被引：4，自引：0，他引：4  

Duncan Carr Agnew  W. E. Farrell 《Geophysical Journal International》1978,55(1):171-181

Summary. We compute the static response of the world ocean to an external zonal gravitational potential. The computation includes the effects of the self-attraction of the ocean, and the yielding of the Earth caused both by the external potential and the change in ocean load. We compare the computed tide with measurements of the fortnightly and monthly ocean tides. The short-wavelength departures from equilibrium found by Wunsch are still present. An average of observations at Pacific islands shows that the fortnightly tide departs significantly from equilibrium but the monthly may not. We have also calculated the effects of our computed tide on measurements of tidal gravity and tidal fluctuations in the length of day. Existing tidal gravity data are too imprecise to enable us to determine whether or not the spatial average of the ocean tides departs from equilibrium. The length of day data suggest that the monthly tide is farther from equilibrium than the fortnightly. We have not been able to resolve the apparent discrepancy between the length of day and ocean tide data.  相似文献   

INSTRUMENTALISM,REALISM, AND RESEARCH ON THE DIFFUSION OF INNOVATION     

John A. Agnew 《The Professional geographer》1979,31(4):364-370

Research on the diffusion of innovation has been dominated for many years by an approach to scientific reasoning developed most thoroughly and influentially by Hägerstrand. Recently there has been a shift away from this approach. However, this shift has not been previously noted in the literature. After presenting the characteristics of the two perspectives in terms of the instrumentalist and realist conceptions of science, this article provides some evidence for the shift and identifies several key issues for future research.  相似文献