Photo‐feature: World of Geology     

Tony Waltham 《Geology Today》2019,35(3):95-101

World of Geology is a book that was born from the back pages of Geology Today: a celebration of the richness of the diversity of geological sites worldwide, and a fitting tribute to the impact of a magazine that is marking its thirty‐fifth year in 2019. This photo‐feature revisits some of the spectacular images that have faetured on its back pages over the years  相似文献   

St Francis: the world's worst dam site          下载免费PDF全文

Tony Waltham 《Geology Today》2018,34(3):100-108

Lying just north of Los Angeles, the total collapse of the St Francis Dam in 1928 has been described as America's worst civil engineering disaster of the twentieth century. Although poorly remembered among today's residents of Los Angeles, the event is better known to engineering geologists. The dam's failure was largely due to the geology of its site, which was inappropriate to the point of disastrous, in more ways than one.  相似文献   

Investigating the Tsunamigenic Potential of Earthquakes from Analysis of the Informational and Multifractal Properties of Seismograms     

Luciano Telesca  Ashutosh Chamoli  Michele Lovallo  Tony Alfredo Stabile 《Pure and Applied Geophysics》2015,172(7):1933-1943

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Photometric analysis of the nucleus of Comet 81P/Wild 2 from Stardust images     

Jian-Yang Li  Michael F. A’Hearn  Tony L. Farnham  Lucy A. McFadden 《Icarus》2009,204(1):209-226

The disk-resolved flyby images of the nucleus of Comet 81P/Wild 2 collected by Stardust are used to perform a detailed study of the photometric properties of this cometary nucleus. A disk-integrated phase function from phase angle 11° to about 100° is measured and modeled. A phase slope of 0.0513 ± 0.0002 mag/deg is found, with a V-band absolute magnitude of 16.29 ± 0.02. Hapke’s photometric model yields a single-scattering albedo of 0.034, an asymmetry factor of phase function −0.53, a geometric albedo 0.059, and a V-band absolute magnitude of 16.03 ± 0.07. Disk-resolved photometric modeling from both the Hapke model and the Minnaert model results in 11% model RMS, indicating small photometric variations. The roughness parameter is modeled to be 27 ± 5° from limb-darkening profile. The modeled single-scattering albedo and asymmetry factor of the phase function are 0.038 ± 0.004 and −0.52 ± 0.04, respectively, consistent with those from disk-integrated phase function. The bulk photometric properties of the nucleus of Wild 2 are comparable with those of other cometary nuclei. The photometric variations on the surface of the nucleus of Wild 2 are at a level of or smaller than 15%, much smaller than those on the nucleus of Comet 19P/Borrelly and comparable or smaller than those on the nucleus of Comet 9P/Tempel 1. The similar photometric parameters of the nuclei of Wild 2, Tempel 1, and the non-source areas of fan jets on Borrelly may reflect the typical photometric properties of the weakly active surfaces on cometary nuclei.  相似文献   

Coma morphology of Jupiter-family comets     

Tony L. Farnham 《Planetary and Space Science》2009,57(10):1192-1217

We present a general review of cometary coma morphology, with specific reference to how it used in studies of Jupiter-family comets. We introduce the most common features that are seen in gas and dust observations, and summarize of how they are used to infer the properties of the nucleus and coma. We also expand the discussion to cover other topics relating to morphology, including the general shape of the coma (characterized by radial gradient profiles) and spatial maps of the color, albedo and polarization of the dust. We address the pros and cons of the different approaches used in the interpretation and analysis of the features. Finally, we review the results obtained for specific comets and compare the Jupiter-family comets to those from other classes.  相似文献   

Quasi-evaporating black holes and cold dark matter     

Julien Larena  Tony Rothman 《Astrophysics and Space Science》2010,327(1):71-76

Vilkovisky has claimed to have solved the black hole backreaction problem and finds that black holes lose only ten percent of their mass to Hawking radiation before evaporation ceases. We examine the implications of this scenario for cold dark matter, assuming that primordial black holes are created during the reheating period after inflation. The mass spectrum is expected to be dominated by 10-gram black holes. Nucleosynthesis constraints and the requirement that the earth presently exist do not come close to ruling out such black holes as dark matter candidates. They also evade the demand that the photon density produced by evaporating primordial black holes does not exceed the present cosmic radiation background by a factor of about one thousand.  相似文献   

Water demand management in Yemen and Jordan: addressing power and interests     

Zeitoun M  Allan T  Al Aulaqi N  Jabarin A  Laamrani H 《The Geographical journal》2012,178(1):54-66

This paper investigates the extent to which entrenched interests of stakeholder groups both maintain water use practice, and may be confronted. The focus is on the agricultural sectors of Yemen and Jordan, where water resource policymakers face resistance in their attempts to reduce water use to environmentally sustainable levels through implementation of water demand management (WDM) activities. Some farmers in both countries that have invested in irrigated production of high-value crops (such as qat and bananas) benefit from a political economy that encourages increased rather than reduced water consumption. The resultant over-exploitation of water resources affects groups in unequal measures. Stakeholder analysis demonstrates that the more ‘powerful’ groups (chiefly the large landowners and the political elites, as well as the ministries of irrigation over which they exert influence) are generally opposed to reform in water use, while the proponents of WDM (e.g. water resource managers, environmental ministries and NGOs, and the international donor community) are found to have minimal influence over water use policy and decisionmaking. Efforts and ideas attempted by this latter group to challenge the status quo are classified here as either (a) influencing or (b) challenging the power asymmetry, and the merits and limits of both approaches are discussed. The interpretation of evidence suggests current practice is likely to endure, but may be more effectively challenged if a long-term approach is taken with an awareness of opportunities generated by windows of opportunity and the participation of ‘overlap groups’.  相似文献   

Hydrogeological Decision Analysis: 4. The Concept of Data Worth and Its Use in the Development of Site Investigation Strategies   总被引：4，自引：0，他引：4  

R. Allan Freeze  Bruce James  Joel Massmann  Tony Sperling  Leslie Smith 《Ground water》1992,30(4):574-588

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A laboratory model of dust devil vortices     

John B. Mullen  Tony Maxworthy 《Dynamics of Atmospheres and Oceans》1977,1(3):181-214

The results of a laboratory investigation of the dust devil vortex are presented. Vortex velocity and temperature profiles were measured for various initial conditiions of boundary heat input and outer flow swirl. Three different categories of core structure were observed depending on the amount of axial flow force and circulation strength produced in the experiment and dust devil models are constructed based on the measured mean behavior of each core category.  相似文献   

The geography of (manufacturing) wages in New Zealand     

Tony Hoare 《New Zealand geographer》1986,42(2):78-81

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