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61.
The scale and severity of property crashes following the global financial crisis has made vacancy a more visible and politically significant feature of cities. Although research has focused on urban experiments in vacant spaces, there has been less emphasis on how the contested property relations around vacancy remake urban governance. In this paper, we argue that debates about vacancy have been a central concern in post-crisis urban governance. In the first part of the paper we draw two conceptual approaches into a dialogue and apply them to an analysis of vacant space: that of Nicholas Blomley on property and Elizabeth Povinelli on “alternative social projects”. In the second part of the paper, we critically analyse how three groups discursively construct the need to “activate” and “re-use” vacant spaces in Dublin: grassroots groups, urban policy-makers, and financial actors. We argue that governing vacancy will be a key feature of post-crisis urbanisation.  相似文献   
62.
 Equilibrium C–O–H fluid speciation calculations predict that graphite will precipitate from initially graphite saturated fluid inclusions during cooling and exhumation of metamorphic rocks. In the case that no mass is gained or lost by the inclusions, the original X O ratio [O/(O+H)] of the fluid phase must be maintained. Given this closed system constraint, the down-temperature progress of graphite precipitation can easily be monitored as a function of the varible X O, and produces some effects that are of significance to fluid inclusion studies: 1. Variation of the H2O : CO2 : CH4 relationship in the graphite-saturated COH fluid, namely increase of X H2 O and decrease of the carbonic fraction; 2. Decrease of fluid density due to precipitation of graphite, which is denser than the residual fluid; 3. Alteration of the CO2 : CH4 ratio of the fluid, depending on the initial O : H ratio of the fluid: for X O>1/3, fluids increase their CO2 : CH4 ratio with decreasing temperature, and vice-versa. This implies that the CO2 : CH4 ratio measured at room T will not represent the trapping value, which is in any case closer to unity. As a consequence of density reduction, isochores extrapolated from densities observed at room temperature do not pass through the pressure-temperature conditions at which the inclusion was trapped, with pressure underestimates of up to 2 kbar. Actual P-T trapping conditions are located along the equilibrium “bulk isochore” (curve of constant-X O, constant-volume) of the fluid. Alteration of the CO2 : CH4 ratio is a mechanism by which a CO2-rich or CH4-rich carbonic phase can be formed from aqueous fluids that are slightly off the neutral X O=1/3 value. Subsequent segregation of this phase from the aqueous counterpart may account for the formation of pure CO2 and CH4 fluids in the upper crust. Received: 15 March 1995 / Accepted: 1 June 1995  相似文献   
63.
18O/16O and14C analysis of deep-sea cores from the Gulf of Mexico revealed a 2.4% isotopic anomaly between 12,000 and 11,000 years ago. This value, together with estimates of the oxygen isotopic composition of ice meltwater and rates of mixing within the Gulf of Mexico indicates that the average yearly discharge of the Mississippi River was between 100,000 and 230,000 m3/s (as compared to 57,000 m3/s for the peak flood of February 17, 1937), with probable yearly peak floods twice as large. Corresponding sea-level rise was between 1 and 2 m per century.  相似文献   
64.
Trapping of long water waves that are induced by submarine earthquakes and that attack circular islands is studied by applying a theoretical model (Tinti andVannini, 1994) that is based on the linear shallow water approximation. The solution is computed as the superposition of the eigenmodes of the water basin. The tsunami trapping is seen in terms of the capability of the source to excite the trapped eigenmodes of the basin. The bottom depth dependence around the island is shown to be quite important in determining the trapping capability of the island: a depth profile that is downwardly concave as the distance from the island coasts increases is substantially more efficient in amplifying the incoming waves and in trapping their energy than a profile exhibiting an upward concavity.  相似文献   
65.
66.
In the Grt-Bt-Sil restitic xenoliths of El Joyazo (Cerro de Hoyazo), hercynitic spinel is a minor phase commonly associated with biotite. The possible reaction relationships among biotite and spinel are studied in reaction textures developed around biotites at their contact with patches of fibrolitic sillimanite and rhyolitic melt. In these textures, resorbed biotite crystals about 1 mm long are rimmed by a layer of glass <200 μm thick containing spinel and ilmenite; the same glass also fills embayments in biotite. Spinel forms euhedral crystals <100 μm in size, and ilmenite occurs as smaller anhedral crystals or needles, often intergrown with spinel. The homogeneous felt-like melt-sillimanite aggregate (“mix”) is richest in glass close to the reaction rim around biotite. Plagioclase and garnet are located >5 mm away from the reaction texture. Biotite is chemically zoned. Cores (Bt 1 ) have XMg=0.35 ± 0.02 and Ti=0.58 ± 0.01 atoms; whereas the outer rims (Bt 2 ) have XMg=0.45 ± 0.01 and Ti up to 0.68 atoms. The hercynite-rich spinel (Spl) has low ZnO content (<0.80 wt%) and XMg=0.26 ± 0.04. The chemical compositions of the mix aggregate represent linear combinations between sillimanite and a silica-rich melt. This melt (melt 1 ) is different from that of the layer around biotite (melt 2 ), which is also richer in Ca and alkalis. Garnet rims (Grt) have low Ca and Mn, and XMg=0.14. Plagioclase is characterized by large homogeneous cores (Pl 1 , An31 ± 2) and more calcic rims (Pl 2 , An49 ± 6). Matrix analysis in the 9-component (Al-Ca-Fe-K-Mg-Mn-Na-Si-Ti), 9-phase (Bt1-Bt2-Grt-Spl-Ilm-melt2-mix-Pl1-Pl2) system provides the mass balance (in mole units):
This relationship is in excellent agreement with the observed textures and hence is considered a good model for the incongruent melting of biotite in the xenoliths. The mass-balance indicates that melt production is dominated by the availability of K from biotite, and that garnet and plagioclase must be involved as reactants, so that the reaction volume is larger than the melt production site. The melting of biotite, constrained at T=900–950°C and P ≥ 5 kbar, is not a terminal reaction, as its variance in the reduced 8-component multisystem is ≥3. Received: 1 June 1999 / Accepted: 8 February 2000  相似文献   
67.
Metapelitic hornfelses in the contact aureole of the Vedrette di Ries pluton exhibit the terminal decomposition of Zn-poor Fe-staurolite in a muscovite-quartz-free domain. The reaction takes place only within coarsegrained sillimanite that has replaced andalusite porphyroblasts during prograde metamorphism. The product is a gahnite-poor hercynitic spinel, which occurs as very small grains closely associated in space with resorbed staurolite. Microstructural observations indicate that bereynite growth postdates the pseudomorphs of sillimanite after andalusite. The textural evidence for a genetic relationship between hercynite and staurolite is confirmed by the identical Fe/Mg/Zn ratios of the two minerals, which causes the collinearity of hercynite, staurolite and Al2SiO5 in FeO–MgO–ZnO–Al2O3–SiO2–H2O composition space (FMZASH), and indicates hercynite formed by the reaction: Fe-staurolite = 3.85hercynite + 5.1sillimanite + 2.55quartz + 2H2O Staurolite inclusions within andalusite did not break down to form hercynite, indicating a kinetic control, as well as little overstepping of the equilibrium conditions, of the reaction forming hercynite. Assuming overstepping did not occur, modelling of the reaction with existing thermodynamic data in the simplified FASH system suggests that the terminal breakdown of staurolite to form hercynite occurred at 2.5–3.75kbar and 585–655°C.  相似文献   
68.
A high-resolution spectrometer (0.0014 nm at 313 nm) has been developed at the University of L’Aquila (Italy) for atmospheric spectroscopic studies. The layout, optics and software for the instrument control are described. Measurements of the mercury low-pressure lamp lines from 200 to 600 nm show the high performances of the spectrometer. Laboratory measurements of OH and NO2 spectrums demonstrate that the system could be used for cross-section measurements and to detect these species in the atmosphere. The first atmospheric application of the system was the observation of direct solar and sky spectrums that shows a filling-in of the sky lines due to rotational Raman scattering. The measurements have been done with clear and cloudy sky and in both there was a strong dependence of the filling-in from the solar zenith angle whereas no dependence from the wavelengths was evident at low solar zenith angles (less than 85°).  相似文献   
69.
A model is constructed of the material in front of the star Cygnus OB2 no. 12 in which dense cores are embedded in diffuse clumps of gas. The model reproduces the measured abundances of C2 and CO, and predicts a column density of 91010 cm2 for HCO+.  相似文献   
70.
After an earthquake, non‐negligible residual displacements may affect the serviceability of a base isolated structure, if the isolation system does not possess a good restoring capability. The permanent offset does not affect the performance unless the design is problematic for utilities, also considering possible concerns related to the maintenance of the devices. Starting from experimental and analytical results of previous studies, the restoring capability of Double Concave Friction Pendulum bearings is investigated in this paper. A simplified design suggestion for the estimation of maximum expected residual displacements for currently used friction pendulum systems is then validated. The study is based on controlled‐displacement and seismic input experiments, both performed under unidirectional motion. Several shaking table tests have been carried out on a three‐dimensional isolated specimen structure. The same sequence of seismic inputs was applied considering three different conditions of sliding surfaces corresponding to low, medium and high friction. The accumulation of residual displacements is also investigated by means of nonlinear dynamic analysis. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
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