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KLAUS DODDS 《Geographical review》2011,101(1):88-105
Generic action‐thriller films, especially The Bourne Ultimatum, the last in a series of three films, provide a useful resource for examining the gendered nature of geopolitics, the specification of place, and the role of geosurveillance in post‐9/11 national security. Using the dialogue of the film as key source material, I show how the private world of Jason Bourne, an assassin, is interwoven with the public sphere of international security, including covert operations: The personal is geopolitical. I conclude with some reflections on how we might use film as a critical pedagogical resource. 相似文献
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KROON NORRIS KLAUS IAN T. ALEXANDER LEON PAUL BARDOT CHARLES E. BARKER JEAN-PIERRE BELLIER CHARLES D. BLOME LEON J. CLARKE JOCHEN ERBACHER KRISTINA L. FAUL MARY ANNE HOLMES BRIAN T. HUBER MIRIAM E. KATZ KENNETH G. MACLEOD SANDRA MARCA FRANCISA C. MARTINEZ-RUIZ ISAO MITA MUTSUMI NAKAI JAMES G. OGG DOROTHY K. PAK THOMAS K. PLETSCH JEAN M. SELF-TRIAL NICHOLAS J. SHACKLETON JAN SMIT WILLIAM USSLERIII DAVID K. WATKINS JOEN WIDMARK & PAUL A. WILSON 《Geology Today》1998,14(6):222-226
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This review begins with a discussion of the techniques needed for observations of scattered light from cometary dust. After
an introduction into the basic concepts of the scattering process, observations of the phase curves of brightness, colour
and polarization are covered. Images of colour and polarization are presented and the observed relation of colour and polarization
in jets and shells is discussed. The interpretation of the measurements is based on the power law size distributions of dust
grains observed from space. The power index must lie between 2 and 4 to provide the mass budget and visibility of the dust
coma in accordance with the basic facts of cometary physics. Application of mechanical (radiation pressure) theory to cometary
images allows us to derive related power law distributions for comets not explored by spacecraft. Grain scattering models
are presented and compared with observations. A prediction is made of the spatial distribution of Stokes parameters U and
V in the presence of aligned particles. Up to now such patterns have not been observed. Future work should include the exploration
of comets at small and possibly very small phase angles and a detailed comparison of polarization and colour images of comets
with thermal images and with models based on mechanical theory.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Abstract— We evaluate the consequences of explosive activity having taken place during volcanic eruptions on the differentiated asteroid 4 Vesta, which is the likely parent body of the howardite-eucrite-diogenite (HED) meteorites. For a wide range of magma volatile contents, we calculate the eruption speeds and subsequent trajectories of the pyroclastic magma droplets produced. By considering the size distribution and eruption speeds of the droplets, and the mass fluxes at which they are ejected, we show that, under all realistic circumstances, the droplets will have formed lava fountains that were extremely optically dense. As a result, virtually all of the droplets will have reached the surface having suffered a negligible amount of radiative cooling and will have coalesced into lava ponds feeding lava flows. Typically, <1% of the pyroclasts will have undergone enough cooling to allow them to accumulate into a recognizable fall deposit consisting of unwelded or partly welded volcanic glass beads. This result is consistent with the apparent absence of identifiable pyroclastic material in the HED (and other types of) differentiated meteorites. 相似文献
5.
Ocean circulation and climate change 总被引：1，自引：0，他引：1
KLAUS HASSELMANN 《Tellus. Series B, Chemical and physical meteorology》1991,43(4):82-103
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KLAUS H. MICHELS 《Sedimentology》1995,42(1):31-38
The composition of sediment samples and/or the influence of current activity on the sediment can be easily determined using the dissection of settling velocity distributions. A new dissection method for the analysis of settling velocity distributions has been developed. The initial settling velocity distribution is decomposed by means of settling velocity distributions of the main biogenic constituents, three planktic and three benthic foraminifera species. A divergence from the natural size distribution of a foraminifera species can be attributed to current influence. Thus, negative or positive skewness of current-affected foraminifera populations indicate erosional or depositional sediment influence. The dissection of Holocene samples from the northern North Atlantic demonstrates the advantages of this method in the interpretation of sand-size material. 相似文献
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ALEXANDER N. KROT MICHAEL I. PETAEV EDWARD R. D. SCOTT BYEON-GAK CHOI MICHAEL E. ZOLENSKY KLAUS KEIL 《Meteoritics & planetary science》1998,33(5):1065-1085
Abstract— The oxidized CV3 chondrites can be divided into two major subgroups or lithologies, Bali-like (CV3oxB) and Allende-like (CV3oxA), in which chondrules, calcium-aluminum-rich inclusions (CAIs) and matrices show characteristic alteration features (Weisberg et al, 1997; Krot et al, 1997d; Kimura and Ikeda, 1997). The CV3oxB lithology is present in Bali, Kaba, parts of the Mokoia breccia and, possibly, in Grosnaja and Allan Hills (ALH) 85006. It is characterized by the presence of the secondary low-Ca phyllosilicates (saponite and sodium phlogopite), magnetite, Ni-rich sulfides, fayalite (Fa>90), Ca-Fe-rich pyroxenes (Fs10–50Wo45–50) and andradite. Phyllosilicates replace primary Ca-rich minerals in chondrules and CAIs, which suggests mobilization of Ca during aqueous alteration. Magnetite nodules are replaced to various degrees by fayalite, Ca-Fe-rich pyroxenes and minor andradite. Fayalite veins crosscut fine-grained rims around chondrules and extend into the matrix. Thermodynamic analysis of the observed reactions indicates that they could have occurred at relatively low temperatures (<300 °C) in the presence of aqueous solutions. Oxygen isotopic compositions of the coexisting magnetite and fayalite plot close to the terrestrial fractionation line with large Δ18Ofayalite-magnetite fractionation (～20%). We infer that phyllosilicates, magnetite, fayalite, Ca-Fe-rich pyroxenes and andradite formed at relatively low temperatures (<300 °C) by fluid-rock interaction in an asteroidal environment. Secondary fayalite and phyllosilicates are virtually absent in chondrules and CAIs in the CV3oxA lithology, which is present in Allende and its dark inclusions, Axtell, ALHA81258, ALH 84028, Lewis Cliff (LEW) 86006, and parts of the Mokoia and Vigarano breccias. Instead secondary nepheline, sodalite, and fayalitic olivine are common. Fayalitic olivine in chondrules replaces low-Ca pyroxenes and rims and veins forsterite grains; it also forms coarse lath-shaped grains in matrix. Secondary Ca-Fe-rich pyroxenes are abundant. We infer that the CV3oxA lithology experienced alteration at higher temperatures than the CV3oxB lithology. The presence of the reduced and CV3oxA lithologies in the Vigarano breccia and CV3oxA and CV3oXB lithologies in the Mokoia breccia indicates that all CV3 chondrites came from one heterogeneously altered asteroid. The metamorphosed clasts in Mokoia (Krot and Hutcheon, 1997) may be rare samples of the hotter interior of the CV asteroid. We conclude that the alteration features observed in the oxidized CV3 chondrites resulted from the fluid-rock interaction in an asteroid during progressive metamorphism of a heterogeneous mixture of ices and anhydrous materials mineralogically similar to the reduced CV3 chondrites. 相似文献
9.
ALEXANDER N. KROT MICHAEL I. PETAEV MICHAEL E. ZOLENSKY KLAUS KEIL EDWARD R. D. SCOTT KEIKO NAKAMURA 《Meteoritics & planetary science》1998,33(4):623-645
Abstract— We have characterized Ca-Fe-rich silicates (salite-hedenbergite pyroxenes (Fs10–50Wo45–50), andradite (Ca3Fe2Si3O12), kirschsteinite (CaFeSiO4), and wollastonite (Ca3Si3O9)) in the type I chondrules and matrices in the Bali-like and Allende-like oxidized CV3 chondrites and Allende dark inclusions. In type I chondrules in the Bali-like CV3 chondrites, metal is oxidized to magnetite; magnetite-sulfide nodules are replaced by Ca-Fe-rich pyroxenes with minor andradite and pure fayalite. We infer that Ca-Fe-rich pyroxenes, andradite, fayalite, magnetite, and phyllosilicates (which occur in mesostases) formed at relatively low temperatures (<300 °C) in the presence of aqueous solutions. Thermodynamic analysis of phase relations in the Si-Fe-Ca-O-H system and large O isotopic fractionation of the coexisting magnetite and fayalite (～20%) (Krot et al., 1998) are consistent with this interpretation. In type I chondrules in the Allende-like CV3 chondrites and dark inclusions, magnetite-sulfide nodules are replaced by Ca-Fe-rich pyroxenes and ferrous olivine; low-Ca pyroxene and forsterite phenocrysts are rimmed and veined by ferrous olivine. It appear that the Ca-Fe-rich pyroxenes predate formation of ferrous olivine; the latter postdates formation of talc and biopyriboles (Brearley, 1997). The Allende dark inclusions are crosscut by Ca-Fe-pyroxene-andradite veins and surrounded by Ca-rich rims that consist of Ca-Fe-rich pyroxenes, andradite, wollastonite, and kirschsteinite. Calcium-rich veins and rims formed after aggregation and lithification of the dark inclusions. The rimmed dark inclusions show zoned depletion in Ca, which is due to a lower abundance of Ca-Fe-rich pyroxenes close to the rim. Calcium was probably leached from the inclusions and redeposited along their edges. We infer that the Allende-like chondrites and dark inclusions experienced similar aqueous alteration to the Bali-like chondrites and were metamorphosed subsequently, which resulted in loss of aqueous solutions and dehydration of phyllosilicates. We conclude that Ca-Fe-rich silicates in the oxidized CV3 chondrites and Allende dark inclusions are secondary and resulted from aqueous fluid-rock interactions during progressive metamorphism of a heterogeneous mixture of hydrous (ices?) and anhydrous materials; the latter were possibly mineralogically similar to the reduced CV3 chondrites. 相似文献
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