Translocal assemblages: Space, power and social movements   总被引：3，自引：0，他引：3  

Colin McFarlane   《Geoforum》2009,40(4):561-567

In this paper, I deploy an analytic of ‘translocal assemblage’ as a means for conceptualising space and power in social movements. I offer a relational topology that is open to how actors within movements construct different spatial imaginaries and practices in their work. In using the prefix ‘translocal’, I am signifying three orientations. First, translocal assemblages are composites of place-based social movements which exchange ideas, knowledge, practices, materials and resources across sites. Second, assemblage is an attempt to emphasise that translocal social movements are more than just the connections between sites. Sites in translocal assemblages have more depth than the notion of ‘node’ or ‘point’ suggests – as connoted by network – in terms of their histories, the labour required to produce them, and their inevitable capacity to exceed the connections between other groups or places in the movement. Third, they are not simply a spatial category, output, or resultant formation, but signify doing, performance and events. I examine the potential of assemblage to offer an alternative account to that of the ‘network’, the predominant and often de facto concept used in discussions of the spatiality of social movements. I draw on examples from one particular translocal assemblage based in and beyond Mumbai which campaigns on housing within informal settlements: Slum/Shack Dwellers International.  相似文献   

Preferential magma extraction from K- and metal-enriched source regions in the crust     

Andrew G. Tomkins  Roberto F. Weinberg  Chris R. M. McFarlane 《Mineralium Deposita》2009,44(2):171-181

We compare melting of potassic alteration zones in metamorphosed gold deposits with that of unaltered rocks of the same protolith to examine their relative contributions to crust-derived magmas and to investigate the implications for ore genesis. Potassic hydrothermal alteration, at the crustal levels where orogenic gold deposits form, stabilizes a higher proportion of muscovite and biotite than is possible in unaltered rocks at high metamorphic grades. Because these micas contain water, they control the melt fraction generated through dehydration melting in that a greater proportion of micas permits more extensive melting. Orogenic gold deposits, in which mineralization is typically encapsulated by potassic alteration, form at deep-enough crustal levels to survive repeated tectonic activity, which can lead to their being metamorphosed. In the vicinity of this metamorphosed gold mineralization, the greatest proportion of felsic melt is generated in the more metal- and sulfur-rich rocks because of the associated potassic alteration. Ore minerals dissolve and are physically incorporated into the resulting felsic melt, which thereby becomes metal- and sulfur-enriched. Since melt fraction is the dominant control on strain partitioning and melt mobilization, increased melting in K-altered mineralized rocks implies that these sites will be the first to experience melt escape and will continue to be the focus of melt escape during ongoing metamorphism. This strain partitioning promotes shear zone development, and once shearing is localized to K-altered mineralized domains, it may attract external magma, allowing extension and linking with nearby active shear zones. In this way, mineralized zones may connect to a regional network of magma transfer, allowing metal enrichment of migrating magmas. Terrains that underwent widespread K alteration associated with mid-crustal gold enrichment are likely, when metamorphosed, to produce significant volumes of reduced, relatively metal- and sulfur-enriched felsic magma. The ages and relative tectonic preservation potential of different K alteration-associated ore types implies that Au, Ag, As, Sb, Bi, Te, and W may be recycled within the crust through this mechanism, whereas Cu and Mo are unlikely to be recycled and require mantle sourcing to form new intrusion-related ores. Silicate melt derived from preexisting zones of gold enrichment in the lower crust may contribute significantly to the metal budget of intrusion-related gold systems, and possibly some gold-rich porphyry deposits.  相似文献   

Titan's diverse landscapes as evidenced by Cassini RADAR's third and fourth looks at Titan     

J.I. Lunine  C. Elachi  S.D. Wall  M.D. Allison  R. Boehmer  P. Encrenaz  G. Franceschetti  G. Hamilton  W.T.K. Johnson  R.L. Kirk  R. Lorenz  D.O. Muhleman  S.J. Ostro  P. Paillou  F. Posa  L.E. Roth  S. Shaffer  B. Stiles  S. Vetrella  C.A. Wood  H. Zebker  E. Karkoschka  E. McFarlane  B. Kazeminejad 《Icarus》2008,195(1):415-433

Cassini's third and fourth radar flybys, T7 and T8, covered diverse terrains in the high southern and equatorial latitudes, respectively. The T7 synthetic aperture radar (SAR) swath is somewhat more straightforward to understand in terms of a progressive poleward descent from a high, dissected, and partly hilly terrain down to a low flat plain with embayments and deposits suggestive of the past or even current presence of hydrocarbon liquids. The T8 swath is dominated by dunes likely made of organic solids, but also contain somewhat enigmatic, probably tectonic, features that may be partly buried or degraded by erosion or relaxation in a thin crust. The dark areas in T7 show no dune morphology, unlike the dark areas in T8, but are radiometrically warm like the dunes. The Huygens landing site lies on the edge of the T8 swath; correlation of the radar and Huygens DISR images allows accurate determination of its coordinates, and indicates that to the north of the landing site sit two large longitudinal dunes. Indeed, had the Huygens probe trajectory been just 10 km north of where it actually was, images of large sand dunes would have been returned in place of the fluvially dissected terrain actually seen—illustrating the strong diversity of Titan's landscapes even at local scales.  相似文献   

Awareness of tsunami natural warning signs and intended evacuation behaviors in Java,Indonesia     

Hall  Sarah  Pettersson  Jessica  Meservy  William  Harris  Ron  Agustinawati  Diannitta  Olson  Jennie  McFarlane  Allayna 《Natural Hazards》2017,89(1):473-496

Natural Hazards - The south coast of Java has a long history of deadly seismogenic tsunamis. The most recent tsunami events in 1994 and 2006 killed hundreds due to lack of awareness and...  相似文献   

Variability of precipitation intensity: sensitivity to treatment of moist convection in an RCM and a GCM     

Virginie Lorant  Norman A. McFarlane  John F. Scinocca 《Climate Dynamics》2006,26(2-3):183-200

The present study investigates the sensitivity of the frequency distribution of precipitation rates to the closure employed in the penetrative mass flux cumulus parameterization of Zhang and McFarlane in the Canadian regional climate model (CRCM) and in the Canadian Centre for Climate Modelling and Analysis third generation global atmospheric general circulation model (AGCM3). The effects of an alternative prognostic closure for mass flux cumulus parameterization in place of the original diagnostic closure are investigated. A set of experiments is performed in which changes in the frequency distribution of precipitation rates and cloud base mass-flux are examined as a function of the parameters that define each closure scheme. The relationship between the frequency distribution of precipitation and cloud base mass flux is examined and a self-consistent relation is found when the depth of convection is taken into account. Experiments performed with the prognostic closure favor relatively strong cloud base mass-flux and deep penetrative convection with relatively more intense convective precipitation. The mean of the frequency distribution of convective precipitation is larger and the heavier events become more intense. Also, experiments performed with the prognostic closure favor less frequent convective activity. However these changes in the distribution of convective component of precipitation are generally offset by opposite changes in the distribution of the resolved large-scale component of precipitation, resulting in relatively smaller changes in total precipitation. The altered partition of precipitation between convective and large-scale components is found to alter the energy balance and the thermodynamic equilibrium structure of the troposphere. The robustness found in the CRCM results regarding the sensitivity of the frequency distribution of precipitation to changes in the closure of the deep convection parameterization is investigated by performing a similar analysis of AGCM3 simulations. A remarkable similarity of AGCM3 and CRCM results is found suggesting that the closure sensitivity identified in this study is robust.  相似文献   

Spatial and temporal expression of vegetation and atmospheric variability from stable carbon and nitrogen isotope analysis of bat guano in the southern United States     

Christopher M. Wurster  Donald A. McFarlane 《Geochimica et cosmochimica acta》2007,71(13):3302-3310

Stable isotopes of faeces contain information related to the animals feeding ecology. The use of stable isotope values from subfossil faeces as a palaeoenvironmental indicator depends on how faithfully the animal records their local environment. Here we present insectivorous bat guano δ¹³C and δ¹⁵N values from a precipitation gradient across the southern United States and northern Mexico to compare with local vegetation and climate. We find δ¹³C values to be an excellent predictor of expected C₄/CAM vegetation, indicating that the bats are non-selective in their diet. Moreover, we find bat guano δ¹³C values to be strongly correlated with summer precipitation amount and winter precipitation ratio. We also find evidence for a significant relationship with mean annual temperature. In general, we do not find δ¹⁵N values to be related to any parameters along the climatic gradient we examined. Additionally, we measured δ¹³C and δ¹⁵N values of bulk guano deposited annually from 1968 to 1987 in a varved guano deposit at Eagle Creek Cave, Arizona. Neither δ¹³C nor δ¹⁵N values were significantly related to various local meteorological variables; however, we found δ¹³C values of guano to be significantly related to drought and to the North American Monsoon indicating bat guano δ¹³C values preserve an interpretable record of large-scale atmospheric variability.  相似文献   

Mobilization of aluminium in the wathering profiles of the African surface in Malawi     

M. J. McFarlane  D. J. Bowden 《地球表面变化过程与地形》1992,17(8):789-805

Leaching of aluminium from the weathering profile of the African surface in Malawi was deduced from the chemistry of a vadose profile. Its loss occurs where congruent kaolinite dissolution results in saprolite collapse, leaving a weakly lateritized, sandy residual mantle. This leaching is a contemporary process, as shown by the precipitation of aluminosilicate evaporites in the dambos (seasonally waterlogged bottomlands). This paper presents the results of determinations, by ICP-OES and AAS-graphite furnace, of aluminium levels in groundwaters, examining the effects of a variety of pretreatments. Filtration (0.45 μm) substantially reduces the levels of total aluminium, showing it to be in particulate form. Subsequent acidification causes precipitation of < 0.45 μm forms of aluminium, further reducing the apparent levels to below ICP-OES detection limit. This is consistent with mobilization in organically bound forms which are destabilized at low pH, and accords with earlier work which showed that indigenous micro-organisms can cause dissolution of kaolinite. Organically bound mobilization provides an explanation for aluminium leaching at near-neutral pH in conjunction with the presence of silica in solution. The identification of this mechanism of kaolinite dissolution and aluminium evacuation from vadose profiles provides a realistic process for the levelling of extensive planation surfaces; the contingent collapse of the kaolinized saprolite would lower the interfluves, progressively narrowing the vadose zone until the landsurface approaches the planar form of the stable, regional water-table.  相似文献   

Parameterization of the surface-layer exchange coefficients for atmospheric models   总被引：2，自引：0，他引：2  

K. Abdella  N. A. McFarlane 《Boundary-Layer Meteorology》1996,80(3):223-248

A new surface-flux parameterization is presented and its impact on climate simulations with the Canadian Centre for Climate Modelling and Analysis (CCCMA) general circulation model (GCM) is discussed. The parameterization is based on the Monin-Obukhov similarity theory using well established flux-profile relationships for the unstable conditions. However, recently proposed new relationships are used in stable conditions. The new formulation allows different roughness lengths for heat and momentum, and gives transfer coefficients that are in agreement with Monin-Obukhov similarity theory. It also includes a parameterization for the free-convective boundary layer, which often occurs over warm surfaces within light winds. In circumstances where the surface layer is not neutrally stratified the proposed flux parameterization yields surface transfer coefficients that are different from those resulting from the standard surface flux formulation used in the GCM. The most marked effects of implementing the new formulation in the GCM are found over land and adjacent oceanic regions in winter where significant differences are found in the surface heat and moisture fluxes and surface temperatures.  相似文献   

Monitoring land surface and cover in urban and peri-urban environments using digital aerial photography     

Peter Caccetta  Simon Collings  Andrew Devereux  Kassell Hingee  Don McFarlane  Anthony Traylen 《International Journal of Digital Earth》2016,9(5):457-475

This paper describes the development of a system for decimetre-scale monitoring of land-surface and land-cover in urban and peri-urban environments. We describe our methodology that comprises the application of highly automated processing and analysis methods to digital aerial photography. The approach described in this paper addresses a monitoring need by providing the ability to generate change information at a spatial resolution suitable for urban, peri-urban and coastal areas, where an increasing percentage of the worlds’ population dwells. These areas are dynamic, with many environmental issues associated with planning, service provision, resource management and allocation, as well as monitoring regulatory compliance. We present a system based on standardised data and methods, which is able to track and communicate changes in features of interest in a way that has not been previously possible. We describe the methodology and then demonstrate its feasibility by applying it to geographic areas of planning and policy relevant size (the order of tens of thousands of square kilometres). We demonstrate the approach by applying it to the problem of urban forest assessment.  相似文献   

Longevity overfishing   总被引：2，自引：1，他引：2  

R.J. Beamish  G.A. McFarlane  A. Benson 《Progress in Oceanography》2006,68(2-4):289

Overfishing is generally considered to be a reduction in biomass below some critical level such that the remaining fish are not able to replenish the population. We propose that the removal of large numbers of older age groups by fishing is also a form of overfishing, which we identify as longevity overfishing. Longevity overfishing is a potentially important consideration for the commercial fisheries off Canada’s Pacific coast that are dominated by species that have maximum ages of 30 years or longer. Sablefish is one of the key long-lived species that is managed for biomass and not longevity. An age structured model showed that if younger fish do not have the same productivity per unit biomass as older fish, the population depleted of older fishes would not recover after a shift of carrying capacity from a prolonged period of poor productivity to a more productive ocean ecosystem. Current management of long-lived species implicitly assumes that young fish will have the same productivity as older fishes, an assumption that is not supported by a sparse literature, and is thus not precautionary. We propose that the evolved age structure is an indication that long-lived species must be managed for longevity as well as biomass, which requires a management time frame that is decades and not annual.  相似文献