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561.
Pauline Miller Jon Mills Stuart Edwards Paul Bryan Stuart Marsh Peter Hobbs 《Marine Geodesy》2013,36(1-2):109-123
At the dynamic coastal fringe, numerous processes interact with local morphology. In soft-cliff environments, this can often lead to the occurrence of coastal geohazards. These can pose a major threat to property and cultural heritage, and an effective monitoring strategy is therefore essential. While contemporary monitoring techniques have been applied, these are often unsuitable in isolation. This paper presents an integrated approach, with the development of weighted surface matching software enabling reliable dataset fusion and multi-temporal change detection, even where significant surface differences exist. Evaluation of this approach is presented and discussed. 相似文献
562.
Michael W. Busch Steven J. Ostro Lance A.M. Benner Jon D. Giorgini Daniel J. Scheeres Michael C. Nolan Patrick A. Taylor Walter Brisken 《Icarus》2011,212(2):649-660
We observed the near-Earth ASTEROID 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 ± 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid’s equator that is broken by a concavity about 150 m in diameter. Otherwise the asteroid’s surface is notably smooth on decameter scales. EV5’s radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure. 相似文献
563.
Climate change,migration and adaptation in Funafuti,Tuvalu 总被引:1,自引:0,他引:1
This paper shows the extent to which people in Funafuti – the main island of Tuvalu – are intending to migrate in response to climate change. It presents evidence collected from Funafuti to challenge the widely held assumption that climate change is, will, or should result in large-scale migration from Tuvalu. It shows that for most people climate change is not a reason for concern, let alone a reason to migrate, and that would-be migrants do not cite climate change as a reason to leave. People in Funafuti wish to remain living in Funafuti for reasons of lifestyle, culture and identity. Concerns about the impacts of climate change are not currently a significant driver of migration from Funafuti, and do not appear to be a significant influence on those who intend to migrate in the future. 相似文献
564.
The prize of peace (is eternal vigilance): a cautionary editorial essay on climate geopolitics 总被引:1,自引:1,他引:0
Jon Barnett 《Climatic change》2009,96(1-2):1-6
565.
Dirk Frei Axel Liebscher Gerhard Franz Bernd Wunder Stephan Klemme Jon Blundy 《Contributions to Mineralogy and Petrology》2009,157(4):473-490
We determined experimentally the Nernst distribution coefficient between orthopyroxene and anhydrous silicate melt for trace elements i in the system Na2O–CaO–MgO–Al2O3–SiO2 (NCMAS) along the dry model lherzolite solidus from 1.1 GPa/1,230°C up to 3.2 GPa/1,535°C in a piston cylinder apparatus.
Major and trace element composition of melt and orthopyroxene were determined with a combination of electron microprobe and
ion probe analyses. We provide partitioning data for trace elements Li, Be, B, K, Sc, Ti, V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb,
Cs, Ba, La, Ce, Sm, Nd, Yb, Lu, Hf, Ta, Pb, U, and Th. The melts were chosen to be boninitic at 1.1 and 2.0 GPa, picritic
at 2.3 GPa and komatiitic at 2.7 and 3.2 GPa. Orthopyroxene is Tschermakitic with 8 mol% Mg-Tschermaks MgAl[AlSiO6] at 1.1 GPa while at higher pressure it has 18–20 mol%. The rare earth elements show a continuous, significant increase in
compatibility with decreasing ionic radius from D
Laopx−melt ∼ 0.0008 to D
Luopx−melt ∼ 0.15. For the high-field-strength elements compatibility increases from D
Thopx−melt ∼ 0.001 through D
Nbopx−melt ∼ 0.0015, D
Uopx−melt ∼ 0.002, D
Taopx−melt ∼ 0.005, D
Zropx−melt ∼ 0.02 and D
Hfopx−melt ∼ 0.04 to D
Tiopx−melt ∼ 0.14. From mathematical and graphical fits we determined best-fit values for D
0M1, D
0M2, r
0M1, r
0M2, E
0M1, and E
0M2 for the two different M sites in orthopyroxene according to the lattice strain model and calculated the intracrystalline
distribution between M1 and M2. Our data indicate extreme intracrystalline fractionation for most elements in orthopyroxene;
for the divalent cations D
i
M2−M1 varies by three orders of magnitude between D
CoM2−M1 = 0.00098–0.00919 and D
BaM2−M1 = 2.3–28. Trivalent cations Al and Cr almost exclusively substitute on M1 while the other trivalent cations substitute on
M2; D
LaM2−M1 reaches extreme values between 6.5 × 107 and 1.4 × 1016. Tetravalent cations Ti, Hf, and Zr almost exclusively substitute on M1 while U and Th exclusively substitute on M2. Our
new comprehensive data set can be used for polybaric-polythermal melting models along the Earth’s mantle solidus.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
566.
As fundamental as emotions may be in our experiences with wildlife, very little research addresses this topic. The following paper provides insight into the emotional responses of conservation volunteers participating on conservation holidays through four ethnographic case-studies. Six common emotional responses were identified: anguish, disappointment, frustration, exhilaration, awe and compassion. These emotional highs and lows shaped the volunteer experience, as the realities of wildlife conservation in South Africa upset the culturally constructed, emotionally appealing vision of African wilderness that the volunteers expected. While the positive emotions associated with idealised expectations of African wildlife provide an ideal basis upon which to commercialise nature conservation, they generate a series of tensions in practice. The paper makes an important empirical contribution to current debates surrounding the economic exploitation of affect, showing how emotions underpin the commercialisation of conservation, both through the configuration of the volunteers’ wildlife experiences and the scope of conservation that is practised. 相似文献
567.
Marina Brozovic Steven J. Ostro Jon D. Giorgini Randy Rose Alice A. Hine Daniel J. Scheeres 《Icarus》2009,201(1):153-166
Near-Earth Asteroid 4660 Nereus has been identified as a potential spacecraft target since its 1982 discovery because of the low delta-V required for a spacecraft rendezvous. However, surprisingly little is known about its physical characteristics. Here we report Arecibo (S-band, 2380-MHz, 13-cm) and Goldstone (X-band, 8560-MHz, 3.5-cm) radar observations of Nereus during its 2002 close approach. Analysis of an extensive dataset of delay-Doppler images and continuous wave (CW) spectra yields a model that resembles an ellipsoid with principal axis dimensions X=510±20 m, Y=330±20 m and . The pole direction is approximately located at ecliptic pole longitude and latitude of λ=+25°, β=+80° with the uncertainty radius of 10°. Our modeling yields a refined rotation period of 15.16±0.04 h. Nereus has a circular polarization (SC/OC) ratio of 0.74±0.08, which implies substantial near-surface centimeter-to-decimeter scale roughness. Dynamical analysis of our model suggests that YORP alteration of the rotation period may become evident within a few years. Nereus has two stable synchronous orbits where natural material may remain in orbit, while most asteroids observed to date do not have such stable synchronous orbits. We also find that spacecraft orbits about Nereus are feasible. 相似文献
568.
Matthew R. Sasso Robert J. Macke Joseph S. Boesenberg Daniel T. Britt Mark L. Rivers Denton S. Ebel Jon M. Friedrich 《Meteoritics & planetary science》2009,44(11):1743-1753
Abstract— We document the size distributions and locations of voids present within five highly porous equilibrated ordinary chondrites using high‐resolution synchrotron X‐ray microtomography (μCT) and helium pycnometry. We found total porosities ranging from ~10 to 20% within these chondrites, and with μCT we show that up to 64% of the void space is located within intergranular voids within the rock. Given the low (S1‐S2) shock stages of the samples and the large voids between mineral grains, we conclude that these samples experienced unusually low amounts of compaction and shock loading throughout their entire post accretionary history. With Fe metal and FeS metal abundances and grain size distributions, we show that these chondrites formed naturally with greater than average porosities prior to parent body metamorphism. These materials were not “fluffed” on their parent body by impact‐related regolith gardening or events caused by seismic vibrations. Samples of all three chemical types of ordinary chondrites (LL, L, H) are represented in this study and we conclude that incomplete compaction is common within the asteroid belt. 相似文献
569.
570.