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21.
It is often argued that the growth of major emerging powers, such as China, India, Russia, and Brazil, will have a transformative effect on the world economy and politics, but the implications of their rise on sustainable development diplomacy have remained understudied. Do these new powers have the potential to exercise leadership and address the stalled performance on the sustainable development agenda? Drawing on theories of leadership in multiparty negotiations and the empirical study of two major emerging powers’ coalitions, BRICS (Brazil, Russia, India, China, South Africa) and BASIC (Brazil, South Africa, India, China), this article assesses their leadership potential in sustainable development diplomacy. It finds that emerging powers are already engaging in policy coordination in the sustainable development realm, have begun to use their influence to create incentives for other actors in the system and have been conducting skillful diplomacy to develop their coalitions and forge consensus in global policy-making. However, exerting actual global leadership would require building a stronger policy agenda. One area with particular potential for emerging powers to exert leadership is the clean energy arena of sustainable development diplomacy.  相似文献   
22.
The phase boundary between MnTiO3 I (ilmenite structure) and MnTiO3 II (lithium niobate structure) has been determined by analysis of quench products from reversal experiments in a cubic anvil apparatus at 1073–1673 K and 43–75 kbar using mixtures of MnTiO3 I and II as starting materials. Tight brackets of the boundary give P(kbar)=121.2−0.045 T(K). Thermodynamic analysis of this boundary gives ΔHo=5300±1000 J·mol−1, ΔSo = 1.98 ±1J·K−1· mol−1. The enthalpy of transformation obtained directly by transposed-temperature-drop calorimetry is 8359 ±2575 J·mol−1. Possible topologies of the phase relations among the ilmenite, lithium niobate, and perovskite polymorphs are constrained using the above data and the observed (reversible with hysteresis) transformation of II to III at 298 K and 20–30 kbar (Ross et al. 1989). The observed II–III transition is likely to lie on a metastable extension of the II–III boundary into the ilmenite field. However the reversed I–II boundary, with its negative dP/ dT does represent stable equilibrium between ilmenite and lithium niobate, as opposed to the lithium niobate being a quench product of perovskite. We suggest a topology in which the perovskite occurs stably at low T and high P with a triple point (I, II, III) at or below 1073 K near 70 kbar. The I–II boundary would have a negative P-T slope while the II–III and I–III boundaries would be positive, implying that entropy decreases in the order lithium niobate, ilmenite, perovskite. The inferred positive slope of the ilmenite-perovskite transition in MnTiO3 is different from the negative slopes in silicates and germanates. These thermochemical parameters are discussed in terms of crystal structure and lattice vibrations.  相似文献   
23.
An integrated data-directed numerical method has been developed to estimate the undiscovered mineral endowment within a given area. The method has been used to estimate the undiscovered uranium endowment in the San Juan Basin, New Mexico, U.S.A. The favorability of uranium concentration was evaluated in each of 2,068 cells defined within the Basin. Favorability was based on the correlated similarity of the geologic characteristics of each cell to the geologic characteristics of five area-related deposit models. Estimates of the undiscovered endowment for each cell were categorized according to deposit type, depth, and cutoff grade. The method can be applied to any mineral or energy commodity provided that the data collected reflect discovered endowment.  相似文献   
24.
In an attempt to characterize localized rates of sediment accretion, 10 sediment cores were collected from the lower reach of the Passaic River, a major tributary of Newark Bay, New Jersey. Sediments were assayed for 210Pb activity at predetermined depths and the rate of sediment accretion (cm yr?1) was estimated from the least squares regression of the log of unsupported activity versus depth. Sediment accretion rates, derived from 210Pb measurements (RPb) were used to predict the depth interval within the core containing sediments deposited around 1954; subsequent 137Cs analyses were focused on this depth interval. Sediment accretion rates derived from 137Cs measurements (RCs) were extrapolated from the depth of the 1954 horizon. Lead-210 derived sediment accretion rates in cores collected from a sediment bench extending along the inside bend on the southern shore of a meander in the river, ranged from 4.1 cm yr?1 to 10.2 cm yr?1 and averaged 6.8 cm yr?1. The RCs estimates for cores from this area ranged from 3.8 cm yr?1 to 8.9 cm yr?1 and averaged 6.6 cm yr?1. The RCs for cores collected in a more hydrologically dynamic reach of the river upstream of the sediment bench, were only 0.41 cm yr?1 and 0.66 cm yr?1. The results of this investigation indicate that this reach of the lower Passaic River is an area of high sediment accumulation, retaining much of the sediment load deposited from upstream and downstream sources. The rates of sediment accretion in the lower Passaic River are among the highest reported anywhere in the Newark Bay estuary.  相似文献   
25.
GIS: A New Profession?   总被引:1,自引:0,他引:1  
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26.
The distribution of macroinvertebrates on Connecticut tidal marshes corresponds well with that reported for other marshes along the Atlantic and Gulf coasts of the United States. The greatest densities and biomass of the ribbed mussel,Geukensia demissa, were found on marshes in the central and western part of the state where both the annual production ofSpartina alterniflora and tidal range are large. *** DIRECT SUPPORT *** A01BY019 00011  相似文献   
27.
Volcán Huaynaputina is a group of four vents located at 16°36'S, 70°51'W in southern Peru that produced one of the largest eruptions of historical times when ~11 km3 of magma was erupted during the period 19 February to 6 March 1600. The main eruptive vents are located at 4200 m within an erosion-modified amphitheater of a significantly older stratovolcano. The eruption proceeded in three stages. Stage I was an ~20-h sustained plinian eruption on 19-20 February that produced an extensive dacite pumice fall deposit (magma volume ~2.6 km3). Throughout medial-distal and distal parts of the dispersal area, a fine-grained plinian ashfall unit overlies the pumice fall deposit. This very widespread ash (magma volume ~6.2 km3) has been recognized in Antarctic ice cores. A short period of quiescence allowed local erosion of the uppermost stage-I deposits and was followed by renewed but intermittent explosive activity between 22 and 26 February (stage II). This activity resulted in intercalated pyroclastic flow and pumice fall deposits (~1 km3). The flow deposits are valley confined, whereas associated co-ignimbrite ash fall is found overlying the plinian ash deposit. Following another period of quiescence, vulcanian-type explosions of stage III commenced on 28 February and produced crudely bedded ash, lapilli, and bombs of dense dacite (~1 km3). Activity ceased on 6 March. Compositions erupted are predominantly high-K dacites with a phenocryst assemblage of plagioclase>hornblende>biotite>Fe-Ti oxides-apatite. Major elements are broadly similar in all three stages, but there are a few important differences. Stage-I pumice has less evolved glass compositions (~73% SiO2), lower crystal contents (17-20%), lower density (1.0-1.3 g/cm3), and phase equilibria suggest higher temperature and volatile contents. Stage-II and stage-III juvenile clasts have more evolved glass (~76% SiO2) compositions, higher crystal contents (25-35%), higher densities (up to 2.2 g/cm3), and lower temperature and volatile contents. All juvenile clasts show mineralogical evidence for thermal disequilibrium. Inflections on a plot of log thickness vs area1/2 for the fall deposits suggest that the pumice fall and the plinian ash fall were dispersed under different conditions and may have been derived from different parts of the eruption column system. The ash appears to have been dispersed mainly from the uppermost parts of the umbrella cloud by upper-level winds, whereas the pumice fall may have been derived from the lower parts of the umbrella cloud and vertical part of the eruption column and transported by a lower-altitude wind field. Thickness half distances and clast half distances for the pumice fall deposit suggests a column neutral buoyancy height of 24-32 km and a total column height of 34-46 km. The estimated mass discharge rate for the ~20-h-long stage-I eruption is 2.4᎒8 kg/s and the volumetric discharge rate is ~3.6᎒5 m3/s. The pumice fall deposit has a dispersal index (Hildreth and Drake 1992) of 4.4, and its index of fragmentation is at least 89%, reflecting the dominant volume of fines produced. Of the 11 km3 total volume of dacite magma erupted in 1600, approximately 85% was evacuated during stage 1. The three main vents range in size from ~70 to ~400 m. Alignment of these vents and a late-stage dyke parallel to the NNW-SSE trend defined by older volcanics suggest that the eruption initiated along a fissure that developed along pre-existing weaknesses. During stage I this fissure evolved into a large flared vent, vent 2, with a diameter of approximately 400 m. This vent was active throughout stage II, at the end of which a dome was emplaced within it. During stage III this dome was eviscerated forming the youngest vent in the group, vent 3. A minor extra-amphitheater vent was produced during the final event of the eruptive sequence. Recharge may have induced magma to rise away from a deep zone of magma generation and storage. Subsequently, vesiculation in the rising magma batch, possibly enhanced by interaction with an ancient hydrothermal system, triggered and fueled the sustained Plinian eruption of stage I. A lower volatile content in the stage-II and stage-III magma led to transitional column behavior and pyroclastic flow generation in stage II. Continued magma uprise led to emplacement of a dome which was subsequently destroyed during stage III. No caldera collapse occurred because no shallow magma chamber developed beneath this volcano.  相似文献   
28.
The intent of this paper is to contribute to a larger discussion of the history of geographical thought and its consequences by gently drawing attention to the Arctic as a place where alternative visions of nature, home and horizon persist; by contrasting many of our unchallenged geographical assumptions with what might be the logical consequence had we started in a different place, under different conditions and with a different perspective. It is never easy to comprehend the perspective of another and it is unwise to presume that one has indeed done so. For this reason, while this paper explores the dichotomy between the geographic perspectives of the Arctic, particularly those of the Inuit who know it best, and those of the Western Europeans who have literally laid claim to the Arctic geography, it does not purport to be anthropological or ethnographical. Rather it is an attempt to sketch the intellectual landscapes implicit in the contrast between Inuit and European approaches to the Arctic.  相似文献   
29.
Comparison of eolian transport during five high-velocity wind events over a 29 day period on a narrow estuarine beach in Delaware Bay, New Jersey, USA, reveals the temporal variability of transport, due to changes in direction of wind approach. Mean wind speed measured 6 m above the dune crest for the five events ranged from 8·5 to 15·9 ms?1. Mean wind direction was oblique to the shoreline (63° from shore-normal) during one event but was within 14° of shore-normal during the other events. Eolian transport is greatest during low tide and rising tide, when the beach source area is widest and when drying of surface sediments occurs. The quantity of sediment caught in a vertical trap for the five events varied from a total of 0·07 to 113·73 kgm?1. Differences in temperature, relative humidity and moisture and salt content of surficial sediments were slight. Mean grain sizes ranged from 0·33 to 0·58 mm, causing slight differences in threshold shear velocity, but shear velocities exceeded the threshold required for transport during all events. Beach width, measured normal to the shoreline, varied from 15·5 to 18·0 m; beach slope differed by 0·5°. The oblique wind during one event created a source width nearly double the width during other days. Beach slope, measured in the direction of the wind, was less than half as steep as the slope measured normal to the shoreline. The amount of sand trapped during the oblique wind was over 20 times greater than any other event, even those with higher shear velocities. The ability of the beach surface to supply grains to the air stream is limited on narrow beaches, but increased source width, due to oblique wind approach, can partially overcome limitations of surface conditions on the beach.  相似文献   
30.
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