On the ownership of land     

E. M. Yates 《GeoJournal》1992,26(3):265-275

In the first section concepts relating to the ownership of land, as voiced by various thinkers from Plato and Aristotle to Locke, Proudhon and Marx, are discussed. In the second section it is shown, that despite the high moral tone of the theorists, in practice land was acquired by theft, the theft perhaps followed by some retrospective attempts to achieve legality. Land was also expropriated on a large scale to be used as a counter in the struggle between the power groupa within the state. In the third section the present day relevance of estate ownership is briefly examined, with reference to political power and to environmental conservation. It is suggested that ideally there should be a return to a leasehold system, in Proudhon's terms possession rather than ownership, land leased from the community and forfeited if environmental damage is inflicted. There should be limit to the upward size of estates in order to limit the political advantages that accrue to families holding large areas of land. For these reforms to be effective and enormous enlargement of democratic processes is required, accompanied by a reduction in power of the central authorities, and by an increase in the financial and intellectual investment in education.  相似文献   

A critical discussion of numerical models for multiaquifer systems     

Ismael Herrera  Jean Pierre Hennart  Robert Yates 《Advances in water resources》1980,3(4):159-163

Leaky aquifers constitute complicated hydrological structures, whose inclusion in numerical models of hydrological systems is difficult, because of their three-dimensional nature. Methods for treating such systems can be classified as fully three-dimensional and quasi-three-dimensional. The latter have clear numerical advantages when applicable. In this paper a critical discussion of existing quasi-three-dimensional models is presented.  相似文献   

The simultaneous detection of 22- and 321-GHz H₂O maser emission towards the symbiotic Mira R Aquarii     

R. J. Ivison  J. A. Yates  & P. J. Hall 《Monthly notices of the Royal Astronomical Society》1998,295(4):813-818

We report high spatial and spectral resolution measurements of masers towards R Aqr and H1−36, both of which are examples of the sub-class of symbiotic stars that contain a long-period Mira-type variable. Our observations have resulted in the first detection of 321-GHz H₂O maser action towards a symbiotic Mira — R Aqr. Comparison with simultaneous 22-GHz H₂O maser data suggests that the masers do not have the same properties as those in the circumstellar envelopes of field Miras. R Aqr's 22-/321-GHz peak flux density and luminosity ratios are low, as is the line width ratio. Continuum and spectral-line maps indicate that the 22-GHz maser and free–free emission are aligned. Three mechanisms can reproduce the data with varying degrees of success. All three lead naturally to normal levels of maser emission in SiO and 321-GHz H₂O and anomalously weak OH and 22-GHz H₂O masers. In the most convincing model, UV radiation and a fast wind from the companion remove the Mira's envelope of dusty, molecular gas, leaving a relatively small cavity of dense, neutral material within a large, ionized nebula. Excitation temperatures suggest that 321-GHz masers are normally excited close to the Mira whilst 22-GHz masers are more remote; in R Aqr, therefore, the 22-GHz masers do not form under optimum conditions. Instead, we see weak and narrow lines that form closer to the Mira, consistent with our high-resolution maps.  相似文献   

Marine science and technology in the Federal Republic of Germany: A policy for non-living resource utilization     

Christine Tiler  John Yates   《Marine Policy》1988,12(4)

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Resolved OH megamaser emission in the nuclear region of the ultraluminous infrared galaxy Markarian 273     

J. A. Yates  A. M. S. Richards  M. M. Wright  J. L. Collett  M. D. Gray  D. Field  R. J. Cohen 《Monthly notices of the Royal Astronomical Society》2000,317(1):28-36

We present high angular resolution MERLIN observations of the 18-cm OH maser and continuum emission associated with the active core of the ultraluminous infrared galaxy Markarian 273. The continuum emission comes from three distinct regions in the central arcsecond of the galaxy. The brightest region of emission has a double-peaked structure which is spatially coincident with similar structures observed at 6 cm and 2.2 μm. The peak of the OH maser emission is spatially coincident with the peak in the continuum. For the first time the maser emission is spatially resolved, allowing us to measure the gas motion within the central 100 pc of the galaxy. Maser emission is found in both the 1665- and 1667-MHz lines, with no systematic offset found in the spatial locations of the two lines. The brighter component of the maser emission shows ordered motion and is aligned along the axis of the double-peaked structure in the brightest continuum region. The gas motion enables us to estimate the central mass density to be 850±50 M_⊙ pc⁻³, which corresponds to a total mass of ≈1.5×10⁸ M_⊙.  相似文献   

Polarization models of young stellar objects – II. Linear and circular polarimetry of R Coronae Australis     

Stuart Clark  Alan McCall  Antonio Chrysostomou  Tim Gledhill  Jeremy Yates  James Hough 《Monthly notices of the Royal Astronomical Society》2000,319(2):337-349

Near-infrared linear imaging polarimetry of the young stellar objects R CrA and T CrA in the J , H and K n bands, and circular imaging polarimetry in the H band, is presented. The data are modelled with the Clark and McCall scattering model. The R CrA and T CrA system is shown to be a particularly complex scattering environment. In the case of R CrA there is evidence that the wavelength dependence of polarization changes across the nebula. MRN dust grain models do not explain this behaviour. Depolarization by line emission is considered as an alternative explanation. The dust grain properties could also be changing across the nebula.
Although surrounded by reflection nebulosity, there is a region of particularly low polarization surrounding R CrA that is best modelled by the canonical bipolar outflow being truncated by an evacuated spherical cavity surrounding the star. The symmetry axis of the nebula appears inclined by 50° to the plane of the sky.
The H -band circular polarimetry of R CrA clearly shows a quadrupolar structure of positive and negative degrees of circular polarization that reach peak magnitudes of ∼5 per cent within our limited map. It is shown that spherical MRN grains are incapable of producing this circular polarization given the observed linear polarization of the R CrA system. Instead, scattering from aligned non-spherical grains is proposed as the operating mechanism.
T CrA is a more archetypical bipolar reflection nebula, and this object is modelled as a canonical parabolic reflection nebula that lies in the plane of the sky. The wavelength independence of linear polarization in the T CrA reflection nebula suggests that the scattering particles are Rayleigh sized. This is modelled with the MRN interstellar grain size distribution.  相似文献   

Assessing the role of alkaline soils on the carbon cycle at a playa site     

Emma L. Yates  Angela M. Detweiler  Laura T. Iraci  Brad M. Bebout  Christopher P. McKay  Kathleen Schiro  Edwin J. Sheffner  Cheryl A. Kelley  Jovan M. Tadić  Max Loewenstein 《Environmental Earth Sciences》2013,70(3):1047-1056

Alkaline soils occupy approximately 5 % of the Earth’s land surface (7 million km), and this may increase due to the global trend towards increasing desertification, yet the extent to which these soils modulate carbon dynamics on regional and global scales is inadequately studied and poorly understood. Railroad Valley (RRV) playa (Nevada, USA) is a semi-arid playa with highly alkaline soils (pH > 10) and no vegetation. The extreme, alkaline environment and absence of vascular vegetation make RRV an ideal site to investigate the role of physiochemical processes of soil-atmosphere CO₂ exchange. Both field and laboratory investigations were conducted. This work shows how the atmospheric CO₂ mixing ratio decreases at nighttime at RRV playa to a value well below the average global background CO₂ concentration. Laboratory investigations using soil samples collected at RRV playa confirmed that CO₂ uptake by RRV playa soils occurs when temperatures are decreased. Both field and laboratory studies suggest that the alkaline RRV soil acts as a CO₂ reservoir during colder periods, such as at nighttime. These results highlight the importance of investigating carbon dynamics in previously understudied environments. Given how little information is available on the CO₂ flux in desert and semi-arid alkaline ecosystems lacking vegetation, our findings draw attention to these environments as becoming increasingly important for carbon fluxes on regional and global scales.  相似文献   

MERLIN polarimetry of the OH masers in OH17.7–2.0     

I. Bains  T. M. Gledhill  J. A. Yates  A. M. S. Richards 《Monthly notices of the Royal Astronomical Society》2003,338(2):287-302

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Sub-au imaging of water vapour clouds around four asymptotic giant branch stars     

I. Bains  R. J. Cohen  A. Louridas  A. M. S. Richards  D. Rosa-González  J. A. Yates 《Monthly notices of the Royal Astronomical Society》2003,342(1):8-32

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OH maser mapping of the evolved star HD 179821: evidence for interacting outflows     

T.M. Gledhill  J.A. Yates  A.M.S. Richards 《Monthly notices of the Royal Astronomical Society》2001,328(1):301-310

The evolved star HD 179821 continues to be the subject of much debate as to whether it is a nearby     post-asymptotic giant branch (post-AGB) star or a distant     high initial mass     post-red supergiant. We have mapped the OH maser emission around HD 179821 in the 1612- and 1667-MHz lines with the MERLIN interferometer array at a resolution of 0.4 arcsec and 0.35 km s⁻¹. The OH emission lies in a thick shell with inner and outer radii of 1.3 and         and expansion velocity of 30 km s⁻¹. Although we find some evidence for acceleration and for deviations from spherical symmetry, the bulk of the maser emission is consistent with a constant-velocity spherical shell. The extent of the shell agrees with H₂O and OH dissociation models and supports a distance estimate of 6 kpc. However, the shell is incomplete and appears to have been disrupted by more recent collimated outflow activity within the last 1500 yr. We suggest that this activity is also responsible for the active envelope chemistry (in particular the presence of HCO⁺) and for the apparent offset of the star from the centre of the shell. The luminous yellow hypergiant star IRC +10420 also shows signs of recent outflows, and HD 179821 may be at a similar, perhaps slightly earlier, phase of evolution. We suggest that the SiO thermal emission arises from the same detached envelope as the OH maser emission as in IRC +10420. If so then this would strengthen the connection between these two stars and probably rule out a post-AGB status for HD 179821.  相似文献