Using GIS and perceived distance to understand the unequal geographies of healthcare in lower-income urban neighbourhoods   总被引：2，自引：0，他引：2  

Hawthorne TL  Kwan MP 《The Geographical journal》2012,178(1):18-30

Geographers play important roles in public health research, particularly in understanding healthcare accessibility, utilisation, and individual healthcare experiences. Most accessibility studies have benefited from the increased sophistication of geographic information systems (GIS). Some studies have been enhanced with semi-structured in-depth interviews to understand individual experiences of people as they access healthcare. However, few accessibility studies have explicitly utilised individual in-depth interview data in the construction of new GIS accessibility measures. Using mixed methods including GIS analysis and individual data from semi-structured in-depth interviews, we offer satisfaction-adjusted distance as a new way of conceptualising accessibility in GIS. Based on fieldwork in a predominantly lower-income community in Columbus, Ohio (USA), we find many residents felt neighbourhood healthcare facilities offered low-quality care, which suggested an added perceived distance as they attempt to access high-quality healthcare facilities. The satisfaction-adjusted distance measure accounts for the perceived distance some residents feel as they search for high-quality healthcare in lower-income urban neighbourhoods. In moving beyond conventional GIS and re-conceptualising accessibility in this way, we offer a more realistic portrayal of the issues lower-income urban residents face as they attempt to access high-quality healthcare facilities. The work has theoretical implications for conceptualising healthcare accessibility, advances the mixed-methodologies literature, and argues for a more equitable distribution of high-quality healthcare in urban neighbourhoods.  相似文献   

XPS spectra of uranyl minerals and synthetic uranyl compounds. I: The U 4f spectrum     

M. Schindler  F.C. Hawthorne  P.C. Burns 《Geochimica et cosmochimica acta》2009,73(9):2471-7290

The occurrence and binding energies of the U⁶⁺, U⁵⁺ and U⁴⁺ bands in the U 4f_7/2 peak of 19 uranyl minerals of different composition and structure were measured by XPS. The results suggest that these minerals can be divided into the following four groups: (1) Uranyl-hydroxy-hydrate compounds with no or monovalent interstitial cations; (2) Uranyl-hydroxy-hydrate minerals with divalent interstitial cations; (3) Uranyl-oxysalt minerals with (TO_n) groups (T = Si, P, and C) in which all equatorial O-atoms of the uranyl-polyhedra are shared with (TO_n) groups; (4) Uranyl-oxysalt minerals with (TO_n) groups (T = S and Se), in which some equatorial O-atoms are shared only between uranyl polyhedra. The average binding energies of the U⁶⁺and U⁴⁺ bands shift to lower values with (1) incorporation of divalent cations and (2) increase in the Lewis basicity of the anion group bonded to U. The first observation is a consequence of an increase in the bond-valence transfer from the interstitial species (cations, H₂O) groups to the O-atoms of the uranyl-groups, which results in an electron transfer from O to U⁶⁺. The second trend correlates with an increase in the covalency of the UO bonds with increase in Lewis basicity of the anion group, which results in a shift of the electron density from O to U. The presence of U⁴⁺ on the surface of uranyl minerals can be detected by the shape of the U 4f_7/2 peak, and the occurrence of the U 5f peak and satellite peaks belonging to the U 4f_5/2 peak. The presence of U⁴⁺ in some of the uranyl minerals and synthetics examined may be related to the conditions during their formation. A charge-balance mechanism is proposed for the incorporation of lower-valence U in the structure of uranyl minerals. Exposure of a Na-substituted metaschoepite crystal in air and to Ultra-High Vacuum results in dehydration of its surface structure associated with a shift of the U⁶⁺ bands to higher binding energies. The latter observation indicates a shift in electron density from U to O, which must be related to structural changes inside the upper surface layers of Na-substituted metaschoepite.  相似文献   

Infrared characterization of (OH, F)-pargasites     

J.- L. Robert  G. Della Ventura  F. C. Hawthorne 《Physics and Chemistry of Minerals》1996,23(4-5):307-307

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A structural phase-transition in K(Mg1−xCux)F3 perovskite     

Peter C. Burns  Frank C. Hawthorne  Anne M. Hofmeister  Stephanie L. Moret 《Physics and Chemistry of Minerals》1996,23(3):141-150

A complete solid-solution series between cubic (Pm 3 m) KMgF₃ and tetragonal (I4/mcm) KCuF₃ was synthesized at 730–735 °C in an inert atmosphere. X-ray powder-diffraction at room temperature shows that the transition between the cubic and tetragonal perovskite structures in the series K (Mg_1?xCu_x) F₃ occurs at x ～ 0.6. Rietveld structure-refinements were done for selected compositions. In the cubic phase, all parameters are linear with composition up to the transition point. At the transition point, there is a strong discontinuity in the cell volume; this is strongly anisotropic with expansion along the a axes and contraction along the c axis due to a pronounced axial elongation of the (Mg, Cu) F₆ octahedron that increases with increasing Cu content. The phase transition is first-order, with a discontinuity of ≈2% in the symmetry-breaking strain at x_C. It is proposed that the phase transition in K (Mg, Cu) F₃ is due to the onset of the cooperative Jahn-Teller effect. Compositional relationships for lattice vibrations in this solid solution were established using thin-film infrared spectroscopy. A phase transition occurring above 60 mole % KCuF₃ is indicated by the appearance of one of the two modes expected for the tetragonal phase; the weaker mode is not resolved below 80 mole % KCuF₃. Modes common to both structures vary smoothly and continuously across the binary; however, frequencies do not depend linearly on composition, nor is mode-softening discernable. Two-mode behaviour is observed only for the bending motion of the cubic phase, because this peak alone has non-overlapping end-member components.  相似文献   

Intrusion features of some hypabyssal south African kimberlites     

J. B. Dawson  J. B. Hawthorne 《Bulletin of Volcanology》1970,34(3):740-757

Kimberlite in certain dykes and in the deepest parts of some diatremes show textural and other features which contrast with those in the breccia diatremes. Some hypabyssal kimberlite intrusions show relatively high-temperature contact phenomena including baking of country-rock sediments and sedimentary xenoliths, and contrasting with the brecciated texture of most diatreme-facies kimberlites, in the hypabyssal kimberlites are numerous examples of preferred orientation of inequidimensional minerals (? trachytic flow texture), and rapid mineralogical gradients from the contact towards the dyke centres that may be attributable to flowage differentiation. In the Benfontein sill (Kimberley area) there is well-developed horizontal banding due to gravitational settling, and pseudo-sedimentary structures are also present. The accumulated evidence indicates that kimberlite existed as a relatively hot fluid up to depths of 2–3 km below the land-surface at the time of intrusion; above this level, gas release caused diatreme formation, brecciation and adiabatic cooling. These views are contrary to those of geologists who postulate eruption of kimberlite as a cold breccia directly from the mantle or deep within the crust, but accords with the views of many Russian geologsts who accept the existence of kimberlite magma, the extrusive equivalent of which is the ultrabasic lava meimechite.  相似文献   

未熟—低熟油研究现状与存在的问题   总被引：6，自引：0，他引：6  

李素梅庞雄奇  金之钧黎茂稳 《地质论评》2003,49(3):298-304

目前存在多种未熟-低熟油成烃机理的说法，但现有未熟-低熟油生烃模式能否用于指导勘探仍然有待于进一步检验。富类脂可溶有机质生烃被认为是未熟-低熟油生烃模式之一，但依据舀烷(特别是甲藻舀烷)的分布特征，东营凹陷牛庄洼陷南斜坡沙四段富藻类未熟-低熟页岩与八面河油田的原油几乎没有可比性，充分说明低演化阶段的藻类类脂物并非该区原油的主要成烃母质。未熟-低熟油田总与邻近的有利生油凹陷相伴以及某些未熟-低熟油的混合成熟度性质，暗示未熟-低熟油区的成熟油贡献，该结论已为中国两个典型未熟-低熟油田即东营凹陷八面河油田与苏北盆地金湖凹陷的最近研究结果所证实。现有资源量计算方法不太适用于未熟-低熟油，这可能导致了部分油田未熟-低熟资源量计算结果偏高。生物标志物标样定量技术是识别原油未熟-低熟性及油源追踪的有效途径，在油气勘探过程中还应加强地化与地质的有机结合。  相似文献   

Stable isotopes in a stalagmite from NW Sweden document environmental changes over the past 4000 years   总被引：1，自引：0，他引：1  

HANNA S. SUNDQVIST  KARIN HOLMGREN  ERS MOBERG  CHRISTOPH SPÖTL  AUGUSTO MANGINI 《Boreas: An International Journal of Quaternary Research》2010,39(1):77-86

Sundqvist, H. S., Holmgren, K., Moberg, A., Spötl, C. & Mangini, A. 2009: Stable isotopes in a stalagmite from NW Sweden document environmental changes over the past 4000 years. Boreas, 10.1111/j.1502‐3885.2009.00099.x. ISSN 0300‐9483. This study of a 4000‐year‐old stalagmite from Korallgrottan in northwestern Sweden highlights the potentials and challenges when using stable isotopes in stalagmites as climate proxies, as well as the fact that the relationship between climate and proxy may change through time. Both the oxygen and the carbon isotopes display an overall trend of enrichment together with decreasing growth rates over the time period covered by the stalagmite, which is considered a generally cooling period according to current palaeoclimate understanding. The stable isotope records show enriched isotopic values during the, for Scandinavia, comparatively cold period AD 1300–1700 and depleted values during the warmer period AD 800–1000. The indication of a negative relationship between measured δ¹⁸O and surface temperature concurs with earlier reported stalagmite records from regions with a seasonal snow cover and is further supported by the fact that the stalagmite δ¹⁸O record shows general similarities with both regional and hemispheric temperature reconstructions available for the past 500 and 2000 years, respectively. Compared with a stable isotope record of lacustrine carbonates from northern Sweden, however, shifting correlations over time between the two records indicate that a local hydrological change may have taken place at Korallgrottan, or at the lake, compared with around 1000 years ago. The earlier part of the stalagmite δ¹⁸O might thus be influenced, to some extent, by another process than the later part, which means that a negative relationship between δ¹⁸O and surface temperature might not hold for the entire 4000‐year‐old record.  相似文献   

Spectral reflectance properties of minerals exposed to simulated Mars surface conditions     

E.A. Cloutis  M.A. Craig  W.R. Jamroz  F.C. Hawthorne 《Icarus》2008,195(1):140-168

A number of mineral species were exposed to martian surface conditions of atmospheric pressure and composition, temperature, and UV light regime, and their evolution was monitored using reflectance spectroscopy. The stabilities for different groups varied widely. Phyllosilicate spectra all showed measurable losses of interlayer H₂O, with some structural groups showing more rapid H₂O loss than others. Loss of OH from the phyllosilicates is not always accompanied by a change in metal-OH overtone absorption bands. OH-bearing sulfates, such as jarosite and alunite, show no measurable change in spectral properties, suggesting that they should be spectrally detectable on Mars on the basis of diagnostic absorption bands in the 0.4-2.5 μm region. Fe³⁺- and H₂O-bearing sulfates all showed changes in the appearance and/or reduction in depths of hydroxo-bridged Fe³⁺ absorption bands, particularly at 0.43 μm. The spectral changes were often accompanied by visible color changes, suggesting that subsurface sulfates exposed to the martian surface environment may undergo measurable changes in reflectance spectra and color over short periods of time (days to weeks). Organic-bearing geological materials showed no measurable change in CH related absorption bands, while carbonates and hydroxides also showed no systematic changes in spectral properties. The addition of ultraviolet irradiation did not seem to affect mineral stability or rate of spectral change, with one exception (hexahydrite). In some cases, spectral changes could be related to the formation of specific new phases. The data also suggest that hydrated minerals detected on Mars to date retain their diagnostic spectral properties that allow their unique identification.  相似文献   

VIII Triassic     

R.J. Allen  R. Bryan  W.H. Bryan  H.G.S. Cribb  A.K. Denmead  W.L. Hawthorne 《Australian Journal of Earth Sciences》2013,60(1-2):251-286

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X Cretaceous     

R.J. Allen  R.W. Day  A.K. Denmead  W.L. Hawthorne  T.G.H. Jenkins  N.J. de Jersey 《Australian Journal of Earth Sciences》2013,60(1-2):309-340

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