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51.
Christopher T. Boyko Mark R. Gaterell Austin R.G. Barber Julie Brown John R. Bryson David Butler Silvio Caputo Maria Caserio Richard Coles Rachel Cooper Gemma Davies Raziyeh Farmani James Hale A. Chantal Hales C. Nicholas Hewitt Dexter V.L. Hunt Lubo Jankovic Ian Jefferson Joanne M. Leach D. Rachel Lombardi Christopher D.F. Rogers 《Global Environmental Change》2012,22(1):245-254
Scenarios are a useful tool to help think about and visualise the future and, as such, are utilised by many policymakers and practitioners. Future scenarios have not been used to explore the urban context in much depth, yet have the potential to provide valuable insights into the robustness of decisions being made today in the name of sustainability. As part of a major research project entitled Urban Futures, a toolkit has been developed in the UK to facilitate the use of scenarios in any urban context and at any scale relevant to that context. The toolkit comprises two key components, namely, (i) a series of indicators comprising both generic and topic area-specific indicators (e.g., air quality, biodiversity, density, water) that measure sustainability performance and (ii) a list of characteristics (i.e., 1–2-sentence statements about a feature, issue or small set of issues) that describe four future scenarios. In combination, these two components enable us to measure the performance of any given sustainability indicator, and establish the relative sensitivity or vulnerability of that indicator to the different future scenarios. An important aspect of the methodology underpinning the toolkit is that it is flexible enough to incorporate new scenarios, characteristics and indicators, thereby allowing the long-term performance of our urban environments to be considered in the broadest possible sense. 相似文献
52.
Michael Hosack J. Kevin Black Philip Deines-Jones Brian R. Dennis Joanne E. Hill Keith Jahoda Albert Y. Shih Christian E. Urba A. Gordon Emslie 《Experimental Astronomy》2011,32(2):101-125
We describe the design of a balloon-borne Imaging X-ray Polarimeter for Solar flares (IXPS). This novel instrument, a Time Projection Chamber (TPC) for photoelectric polarimetry, will be capable of measuring polarization at the few percent level in the 20?C50 keV energy range during an M- or X-class flare, and will provide imaging information at the ??10 arcsec level. The primary objective of such observations is to determine the directivity of nonthermal high-energy electrons producing solar hard X-rays, and hence to learn about the particle acceleration and energy release processes in solar flares. Secondary objectives include the separation of the thermal and nonthermal components of the flare X-ray emissions and the separation of photospheric albedo fluxes from direct emissions. 相似文献
53.
Bulk geochemistry of ~ 1.8 Ma lacustrine claystone at Olduvai Gorge, Tanzania, is controlled principally by the geochemistry of ultrafine (< 0.1 μm), authigenic clay minerals. Authigenic clays have an average structural formula of (Si3.83Al0.17)(Al0.43Fe0.49Mg0.84)(Na0.99K0.22Ca0.16)O10(OH)2; octahedral composition varies, with Mg/(Al + Fe) ranging from 0.7 to 2.3. These clay minerals have a complex history of interaction with saline, alkaline water, followed by secondary diagenetic reactions that leached Mg in freshwater paleoenvironments. Lateral variations in whole-rock and clay geochemistry show westward enrichment in Mg, from Mgoct = 0.6–1.6. This is consistent with persistence of saline, alkaline Paleolake Olduvai to the west, and the presence of groundwater wetlands and other freshwater paleoenvironments to the east. Stone artifact mass density also varies systematically across the basal Bed II deposits, ranging from 100.0 to 104.3 g of artifacts per cubic meter of excavated sediment. Significant correlation is found between clay geochemistry and the density of artifacts excavated from associated archeological trenches (r2 = 0.59, p < 0.01). This relationship supports models of hominin land use in which artifact use and discard is concentrated near freshwater paleoenvironments such as wetlands associated with surface and groundwater discharge. Independent paleoenvironmental proxies such as clay geochemistry allow quantitative hypothesis testing to improve our understanding of early hominin behavior and paleoecology. 相似文献
54.
Several new precise times of minima, based on CCD observations, have been secured for the relatively seldom studied eclipsing
binary V865 Cyg (P=0d.365 days). Its O–C diagram was analysed and new light elements are given. We showed that there is probably no parabolic period increase in V865 Cyg.
Instead, a single abrupt period increase can be distinguished in the O–C diagram. 相似文献
55.
L. Maignien D. Depreiter A. Foubert J. Reveillaud L. De Mol P. Boeckx D. Blamart J.-P. Henriet N. Boon 《International Journal of Earth Sciences》2011,100(6):1413-1422
The Gulf of Cadiz is an area of mud volcanism and gas venting through the seafloor. In addition, several cold-water coral
carbonate mounds have been discovered at the Pen Duick escarpment amidst the El Arraiche mud volcano field on the Moroccan
margin. One of these mounds -named Alpha mound- has been studied to examine the impact of the presence of methane on pore-water
geochemistry, potential sulphate reduction (SR) rate and dissolved inorganic carbon (DIC) budget of the mound in comparison
with off-mound and off-escarpment locations. Pore-water profiles of sulphate, sulphide, methane, and DIC from the on-mound
location showed the presence of a sulphate to methane transition zone at 350 cm below the sea floor. This was well correlated
with an increase in SR activity. 13C-depleted DIC at the transition zone (−21.9‰ vs. Vienna Pee Dee Belemnite) indicated that microbial methane oxidation significantly
contribute to the DIC budget of the mound. The Alpha mound thus represents a new carbonate mound type where the presence and
anaerobic oxidation of methane has an important imprint on both geochemistry and DIC isotopic signature and budget of this
carbonate mound. 相似文献
56.
We investigated the occurrence of behaviors that maximize predator avoidance and seaward transport in estuarine decapod zoeae
by collecting larvae from discrete depths in a partially mixed estuary, Willapa Bay, Washington, USA, and relating their abundance
and vertical distribution to a suite of environmental variables. Abundances of first zoeae of Neotrypaea californiensis and Pinnotheridae were associated with tidal phase, diel phase, and water height. Both taxa were most abundant during ebb
tides, and abundances increased with water height, suggesting behaviors that enhanced seaward transport. Additionally, N. californiensis were both shallower and more abundant at night, indicative of behaviors to avoid visual predators. Our results suggest that
both tidal transport and predator avoidance are important and sometimes interactive selective forces shaping larval decapod
behavior. 相似文献
57.
Roger Urgeles Angelo Camerlenghi Daniel Garcia‐Castellanos Ben De Mol Miquel Garcés Jaume Vergés Ian Haslam Martin Hardman 《Basin Research》2011,23(2):123-145
We present new 3D seismic and well data from the Ebro Margin, NW Mediterranean Sea, to shed new light on the processes that formed the Messinian Erosion Surfaces (MES) of the Valencia Trough (Mediterranean Sea). We combine these data with backstripping techniques to provide a minimum estimate of the Messinian sea level fall in the EBRO Margin, as well as coupled isostasy and river incision and transport modeling to offer new constraints on the evolution of the adjacent subaerial Ebro Basin. Four major seismic units are identified on the Cenozoic Ebro Margin, based on the seismic data, including two major prograding megasequences that are separated by a major unconfirmity: the MES. The 3D seismic data provide an unprecedented view of the MES and display characteristic features of subaerial incision, including a drainage network with tributaries of at least five different orders, terraces and meandering rivers. The Messinian landscape presents a characteristic stepped‐like profile that allows the margin to be subdivided in three different regions roughly parallel to the coastline. No major tectonic control exists on the boundaries between these regions. The boundary between the two most distal regions marks the location of a relatively stable base level, and this is used in backstripping analysis to estimate the magnitude of sea level drop associated with the Messinian Salinity Crisis on the Ebro Margin. The MES on the Ebro Margin is dominated by a major fluvial system, that we identify here as the Messinian Ebro River. The 3D seismic data, onshore geology and modeling results indicate that the Ebro River drained the Ebro Basin well in advance of the Messinian. 相似文献
58.
A subaltern critical geopolitics of the war on terror: Postcolonial security in Tanzania 总被引:1,自引:0,他引:1
Joanne Sharp 《Geoforum》2011,42(3):297-305
Currently, hegemonic geographical imaginations are dominated by the affective geopolitics of the War on Terror, and related security practice is universalised into what has been called “globalized fear” (Pain, 2009). Critical approaches to geopolitics have been attentive to the Westerncentric nature of this imaginary, however, studies of non-Western perceptions of current geopolitics and the nature of fear will help to further displace dominant geopolitical imaginations. Africa, for example, is a continent that is often captured in Western geopolitics - as a site of failed states, the coming anarchy, passive recipient of aid, and so on - but geopolitical representations originating in Africa rarely make much of an impact on political theory.This paper aims to add to critical work on the so-called War on Terror from a perspective emerging from the margins of the dominant geopolitical imagination. It considers the geopolitical imagination of the War on Terror from a non-Western source, newspapers in Tanzania. 相似文献
59.
Niels Hovius Albert Galy Robert G. Hilton Robert Sparkes Joanne Smith Kao Shuh-Ji Chen Hongey Lin In-Tian A. Joshua West 《Applied Geochemistry》2011
Rapidly eroding, coastal mountain belts, where steep rivers and submarine channels connect upland sources to nearby marine sinks are hotspots of organic carbon transfer from life biomass, soil and exhumed bedrock into geological storage. Using observations from the Southern Alps of New Zealand, and Taiwan, we have mapped this organic pathway to geological carbon sequestration, and can evaluate the magnitude and efficiency of transfers between sources and sinks. We demonstrate that POC is harvested by landsliding, but importantly also by common and widespread surface runoff on steep hillslopes. Although terrestrially sourced POC is found in many sedimentary environments associated with mountain belts and frontier basins, it appears to be most abundantly trapped and preserved in marine turbidites. The loss of all forms of POC in onward transport through short, steep routing systems to this repository is limited. This is in marked contrast to larger routing systems, in which only the most resilient forms of POC survive into long-term deposition. 相似文献
60.
Scales and structure of frontal adjustment and freshwater export in a region of freshwater influence
Sea surface temperature satellite imagery and a regional hydrodynamic model are used to investigate the variability and structure
of the Liverpool Bay thermohaline front. A statistically based water mass classification technique is used to locate the front
in both data sets. The front moves between 5 and 35 km in response to spring–neap changes in tidal mixing, an adjustment that
is much greater than at other shelf-sea fronts. Superimposed on top of this fortnightly cycle are semi-diurnal movements of
5–10 km driven by flood and ebb tidal currents. Seasonal variability in the freshwater discharge and the density difference
between buoyant inflow and more saline Irish Sea water give rise to two different dynamical regimes. During winter, when cold
inflow reduces the buoyancy of the plume, a bottom-advected front develops. Over the summer, when warm river water provides
additional buoyancy, a surface-advected plume detaches from the bottom and propagates much larger distances across the bay.
Decoupled from near-bed processes, the position of the surface front is more variable. Fortnightly stratification and re-mixing
over large areas of Liverpool Bay is a potentially important mechanism by which freshwater, and its nutrient and pollutant
loads, are exported from the coastal plume system. Based on length scales estimated from model and satellite data, the erosion
of post-neap stratification is estimated to be responsible for exporting approximately 19% of the fresh estuarine discharge
annually entering the system. Although the baroclinic residual circulation makes a more significant contribution to freshwater
fluxes, the episodic nature of the spring–neap cycle may have important implications for biogeochemical cycles within the
bay. 相似文献