Adult Mortality and Natural Resource Use in Rural South Africa: Evidence From the Agincourt Health and Demographic Surveillance Site     

Hunter LM  Twine W  Johnson A 《社会与自然资源》2011,24(3):256-275

There is little empirical evidence on the association between household experience with HIV/AIDS and shifts in the use of natural resources in developing countries, where residents of rural regions remain highly dependent on often-declining local supplies of natural resources. This study examines household strategies with regard to fuelwood and water among impoverished rural South African households having experienced a recent adult mortality and those without such mortality experience. Quantitative survey data reveal higher levels of natural resource dependence among mortality-affected households, as well as differences in collection strategies. Qualitative interview data provide insight into subtle and complex adjustments at the household level, revealing that impacts vary by the role of the deceased within the household economy. Resource management and public health implications are explored.  相似文献   

Thermal infrared spectra of experimentally shocked andesine anorthosite     

Jeffrey R. Johnson 《Icarus》2012,221(1):359-364

Andesine-rich (An_36–46) anorthosite rocks experimentally shocked to high pressures (16–57 GPa) exhibit changes in spectral features with increasing pressure in laboratory thermal infrared emission spectra (250–1400 cm^?1). These results are similar to previous studies of shocked bytownite- and albite-rich rocks, albeit with differences in absorption band centers characteristic of mineralogy and composition. Typical spectral absorptions result from Si–O antisymmetric stretch motions of the silica tetrahedral (1000–1250 cm^?1) and weaker absorptions due to Si–O–Si octahedral bending vibrations (350–700 cm^?1). Many of these features persist to higher pressures in the andesine spectra compared to similar features in measurements of shocked bytownite. This is consistent with previous thermal infrared absorption studies of shocked feldspars and likely is related to differences in density, hardness, and Al content. A transparency feature at ～832 cm^?1 observed in powdered andesine spectra also degrades with increasing pressure, intermediate between the ～828 cm^?1 and ～855 cm^?1 transparency features in spectra of powders of shocked bytownite and albitite, respectively. These data can be incorporated into thermal infrared spectral analyses of cratered planetary surfaces (or laboratory spectra of shocked samples) to help constrain the occurrence and degree of shock in plagioclase feldspars.  相似文献   

Charting thermal emission variability at Pele,Janus Patera and Kanehekili Fluctus with the Galileo NIMS Io Thermal Emission Database (NITED)     

Ashley Gerard Davies  Glenn J. Veeder  Dennis L. Matson  Torrence V. Johnson 《Icarus》2012,221(1):466-470

Using the NIMS Io Thermal Emission Database (NITED), a collection of over 1000 measurements of radiant flux from Io’s volcanoes (Davies, A.G. et al. [2012]. Geophys. Res. Lett. 39, L01201. doi:10.1029/2011GL049999), we have examined the variability of thermal emission from three of Io’s volcanoes: Pele, Janus Patera and Kanehekili Fluctus. At Pele, the 5-μm thermal emission as derived from 28 night time observations is remarkably steady at 37 ± 10 GW μm^?1, re-affirming previous analyses that suggested that Pele an active, rapidly overturning silicate lava lake. Janus Patera also exhibits relatively steady 5-μm thermal emission (≈20 ± 3 GW μm^?1) in the four observations where Janus is resolved from nearby Kanehekili Fluctus. Janus Patera might contain a Pele-like lava lake with an effusion rate (Q_F) of ≈40–70 m³ s^?1. It should be a prime target for a future mission to Io in order to obtain data to determine lava eruption temperature. Kanehekili Fluctus has a thermal emission spectrum that is indicative of the emplacement of lava flows with insulated crusts. Effusion rate at Kanehekili Fluctus dropped by an order of magnitude from ≈95 m³ s^?1 in mid-1997 to ≈4 m³ s^?1 in late 2001.  相似文献   

Thermally driven escape from Pluto’s atmosphere: A combined fluid/kinetic model     

O.J. Tucker  J.T. Erwin  J.I. Deighan  A.N. Volkov  R.E. Johnson 《Icarus》2012,217(1):408-415

A combined fluid/kinetic model is developed to calculate thermally driven escape of N₂ from Pluto’s atmosphere for two solar heating conditions: no heating above 1450 km and solar minimum heating conditions. In the combined model, one-dimensional fluid equations are applied for the dense part of the atmosphere, while the exobase region is described by a kinetic model and calculated by the direct simulation Monte Carlo method. Fluid and kinetic parts of the model are iteratively solved in order to maintain constant total mass and energy fluxes through the simulation region. Although the atmosphere was found to be highly extended, with an exobase altitude at ～6000 km at solar minimum, the outflow remained subsonic and the escape rate was within a factor of two of the Jeans rate for the exobase temperatures determined. This picture is drastically different from recent predictions obtained solely using a fluid model which, in itself, requires assumptions about atmospheric density, flow velocity and energy flux carried away by escaping molecules at infinity. Gas temperature, density, velocity and heat flux versus radial distance are consistent between the hydrodynamic and kinetic model up to the exobase, only when the energy flux across the lower boundary and escape rate used to solve the hydrodynamic equations is obtained from the kinetic model. This limits the applicability of fluid models to atmospheric escape problems. Finally, the recent discovery of CO at high altitudes, the effect of Charon and the conditions at the New Horizon encounter are briefly considered.  相似文献   

Crustal architecture of the Capricorn Orogen,Western Australia and associated metallogeny     

S. P. Johnson  A. M. Thorne  I. M. Tyler  R. J. Korsch  B. L. N. Kennett  H. N. Cutten 《Australian Journal of Earth Sciences》2013,60(6-7):681-705

A 581 km vibroseis-source, deep seismic reflection survey was acquired through the Capricorn Orogen of Western Australia and, for the first time, provides an unprecedented view of the deep crustal architecture of the West Australian Craton. The survey has imaged three principal suture zones, as well as several other lithospheric-scale faults. The suture zones separate four seismically distinct tectonic blocks, which include the Pilbara Craton, the Bandee Seismic Province (a previously unrecognised tectonic block), the Glenburgh Terrane of the Gascoyne Province and the Narryer Terrane of the Yilgarn Craton. In the upper crust, the survey imaged numerous Proterozoic granite batholiths as well as the architecture of the Mesoproterozoic Edmund and Collier basins. These features were formed during the punctuated reworking of the craton by the reactivation of the major crustal structures. The location and setting of gold, base metal and rare earth element deposits across the orogen are closely linked to the major lithospheric-scale structures, highlighting their importance to fluid flow within mineral systems by the transport of fluid and energy direct from the mantle into the upper crust.  相似文献   

Facies model of a fine‐grained,tide‐dominated delta: Lower Dir Abu Lifa Member (Eocene), Western Desert,Egypt     

Berit Legler  Howard D. Johnson  Gary J. Hampson  Benoit Y.G. Massart  Chris A‐L. Jackson  Matthew D. Jackson  Ahmed El‐Barkooky  Rodmar Ravnas 《Sedimentology》2013,60(5):1313-1356

Existing facies models of tide‐dominated deltas largely omit fine‐grained, mud‐rich successions. Sedimentary facies and sequence stratigraphic analysis of the exceptionally well‐preserved Late Eocene Dir Abu Lifa Member (Western Desert, Egypt) aims to bridge this gap. The succession was deposited in a structurally controlled, shallow, macrotidal embayment and deposition was supplemented by fluvial processes but lacked wave influence. The succession contains two stacked, progradational parasequence sets bounded by regionally extensive flooding surfaces. Within this succession two main genetic elements are identified: non‐channelized tidal bars and tidal channels. Non‐channelized tidal bars comprise coarsening‐upward sandbodies, including large, downcurrent‐dipping accretion surfaces, sometimes capped by palaeosols indicating emergence. Tidal channels are preserved as single‐storey and multilateral bodies filled by: (i) laterally migrating, elongate tidal bars (inclined heterolithic strata, 5 to 25 m thick); (ii) forward‐facing lobate bars (sigmoidal heterolithic strata, up to 10 m thick); (iii) side bars displaying oblique to vertical accretion (4 to 7 m thick); or (iv) vertically‐accreting mud (1 to 4 m thick). Palaeocurrent data show that channels were swept by bidirectional tidal currents and typically were mutually evasive. Along‐strike variability defines a similar large‐scale architecture in both parasequence sets: a deeply scoured channel belt characterized by widespread inclined heterolithic strata is eroded from the parasequence‐set top, and flanked by stacked, non‐channelized tidal bars and smaller channelized bodies. The tide‐dominated delta is characterized by: (i) the regressive stratigraphic context; (ii) net‐progradational stratigraphic architecture within the succession; (iii) the absence of upward deepening trends and tidal ravinement surfaces; and (iv) architectural relations that demonstrate contemporaneous tidal distributary channel infill and tidal bar accretion at the delta front. The detailed facies analysis of this fine‐grained, tide‐dominated deltaic succession expands the range of depositional models available for the evaluation of ancient tidal successions, which are currently biased towards transgressive, valley‐confined estuarine and coarser grained deltaic depositional systems.  相似文献   

Volcanoes and rocks of St Andrew Strait,Papua New Guinea     

R. W. Johnson  I. E. Smith 《Australian Journal of Earth Sciences》2013,60(3):333-351

When Tuluman volcano, in St Andrew Strait, northern Bismarck Sea, erupted between 1953 and 1957, it produced acid rocks similar in major element chemistry to those of three other islands in the Strait — Lou, Pam Lin, and Pam Mandian. These acid rocks — termed the TLP’ series — are thought to represent magmas, or to be derivatives of a parental magma, produced by melting of crust (about 25 km thick beneath St Andrew Strait). TLP rocks have agpaitic indices ranging between 0.86 and 0.96. Acid lava also makes up 3 of the 4 Fedarb Islands at the northern end of St Andrew Strait, but its composition appears to be unrelated to that of the TLP series, and its origin is uncertain.

Q‐normative basalts (quartz tholeiites) make up the fourth island of the Fedarb group, and ol‐ and hy‐normative basalts crop out on Baluan Island at the southern end of the Strait. These basalt types do not appear to be directly related to one another, although both may have been derived from parents that originated in the upper mantle. Andesitic rocks have not been found on any of the islands in St Andrew Strait.

Tuluman and the volcanoes of Lou Island form an arc which may be part of a developing (or completed) ring fracture whose centre coincides with the line between Baluan Island, the Pam Islands, and the Fedarb Islands. The ring fracture may be the result of sagging of crust above a zone of crustal melting that produced the TLP magmas. It is possible that collapse could take place along this ring fracture, producing a caldera.  相似文献   

Resolution of foraminiferal biotopes in Broken Bay,N.S.W.     

A. D. Albani  K. R. Johnson 《Australian Journal of Earth Sciences》2013,60(4):435-446

A recent benthonic foraminiferal population consisting of 144 species from an interacting marine‐estuarine environment has been analysed by Q‐mode cluster analysis to reveal biotopes. Simplification of the total populations, both in terms of abundance and occurrence, discloses that the more significant subpopulation is composed of the widely‐occurring species. Subpopulations based on rarely occurring but locally abundant species do not define meaningful biotopes.  相似文献   

Light element geochemistry of the Chelyabinsk meteorite     

C. T. Pillinger  R. C. Greenwood  D. Johnson  J. M. Gibson  A. G. Tindle  A. B. Verchovsky  A. I. Buikin  I. A. Franchi  M. M. Grady 《Geochemistry International》2013,51(7):540-548

The spectacular arrival of a huge meteorite in central Siberia on February 15th 2013 was the largest event of its kind for more than a hundred years. Oxygen isotope analysis reveals the object involved was an ordinary chondrite of type LL. Petrological examination of the material analysed shows two main lithologies, metamorphic grade 5, were present both having veins of shock produced glass. All three types of material were investigated for carbon, nitrogen and noble gas content and isotopic compositions. The relatively low abundance of carbon and nitrogen indicate that Chelyabinsk is uncontaminated by comparison with other samples in meteorite collections so that indigenous components may be recognized. All the samples studied contained minimal amounts of cosmogenic and primordial noble gases, evidence that the pre-atmospheric size of the object was large, greater than two metres in diameter and that the explosion and break-up was accompanied by catastrophic degassing. The implications for other major meteorite falls and the Tunguska event are discussed.  相似文献   

A GIS and statistical approach to identify variables that control water quality in hydrothermally altered and mineralized watersheds, Silverton, Colorado, USA     

Douglas B. Yager  Raymond H. Johnson  Barnaby W. Rockwell  Jonathan Saul Caine  Kathleen S. Smith 《Environmental Earth Sciences》2013,70(3):1057-1082

Hydrothermally altered bedrock in the Silverton mining area, southwest Colorado, USA, contains sulfide minerals that weather to produce acidic and metal-rich leachate that is toxic to aquatic life. This study utilized a geographic information system (GIS) and statistical approach to identify watershed-scale geologic variables in the Silverton area that influence water quality. GIS analysis of mineral maps produced using remote sensing datasets including Landsat Thematic Mapper, advanced spaceborne thermal emission and reflection radiometer, and a hybrid airborne visible infrared imaging spectrometer and field-based product enabled areas of alteration to be quantified. Correlations between water quality signatures determined at watershed outlets, and alteration types intersecting both total watershed areas and GIS-buffered areas along streams were tested using linear regression analysis. Despite remote sensing datasets having varying watershed area coverage due to vegetation cover and differing mineral mapping capabilities, each dataset was useful for delineating acid-generating bedrock. Areas of quartz–sericite–pyrite mapped by AVIRIS have the highest correlations with acidic surface water and elevated iron and aluminum concentrations. Alkalinity was only correlated with area of acid neutralizing, propylitically altered bedrock containing calcite and chlorite mapped by AVIRIS. Total watershed area of acid-generating bedrock is more significantly correlated with acidic and metal-rich surface water when compared with acid-generating bedrock intersected by GIS-buffered areas along streams. This methodology could be useful in assessing the possible effects that alteration type area has in either generating or neutralizing acidity in unmined watersheds and in areas where new mining is planned.  相似文献