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71.
Jérôme Harlay Caroline De Bodt Anja Engel Sandra Jansen Quentin d’Hoop Judith Piontek Nicolas Van Oostende Steve Groom Koen Sabbe Lei Chou 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1251-1265
The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEPmicro) and colorimetric (TEPcolor) methods, showed abundant (6.1×106–4.4×107 L?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEPmicro and similar vertical profiles of TEPcolor. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms. 相似文献
72.
Harold C. Connolly Caroline Smith Gretchen Benedix Luigi Folco Kevin Righter Jutta Zipfel Akira Yamaguchi Hasnaa Chennaoui Aoudjehane 《Meteoritics & planetary science》2007,42(9):1647-1694
Abstract— In this edition of The Meteoritical Bulletin, 1394 recognized meteorites are reported, 27 from specific locations within Africa, 133 from Northwest Africa, 1227 from Antarctica (from ANSMET, PNRA, and PRIC expeditions), and 7 from Asia. The Meteoritical Bulletin announces the approval of four new names series by the Nomenclature Committee of the Meteoritical Society, two from Africa and one from Asia, including Al Haggounia, from Al Haggounia, Morocco, which is projected to be on the order of 3 metric tons of material related to enstatite chondrites and aubrites. Approved are two falls from Africa, Bassikounou (Mauritania) and Gashua (Nigeria). Approved from areas other than Antarctica are one lunar, two Martian, 32 other achondrites, three mesosiderites, two pallasites, one CM, two CK, one CR2, two CV3, one CR2, and four R chondrites. The Nomenclature Committee of the Meteoritical Society announces 48 newly approved relict meteorites from two new name series, Österplana and Gullhögen (both from Sweden). 相似文献
73.
Equilibration Scales in Silicic to Intermediate Magmas Implications for Experimental Studies 总被引:5,自引:0,他引:5
Pichavant Michel; Costa Fidel; Burgisser Alain; Scaillet Bruno; Martel Caroline; Poussineau Stephane 《Journal of Petrology》2007,48(10):1955-1972
Experimental phase equilibrium studies are increasingly beingused for the determination of intensive variables (P, T, fH2O,fO2 ) in silicic to intermediate magmas. In contrast, silicicigneous bodies are now perceived as open, periodically recharged,systems involving only limited chemical equilibration. Thus,the use of laboratory-determined crystal–liquid equilibriumdata needs clarification. Here we review the field, petrologicaland geochemical evidence concerning states and scales of chemicalequilibrium in silicic magma bodies. It is concluded that totalchemical equilibrium is generally not the rule. However, a subsystemin local equilibrium (the reactive magma) can be identified.Equilibration scales in silicic magmas are rate-limited eitherby diffusive flux in crystals (DICL regime) or by diffusiveflux in the melt (MD regime). The recognition that equilibriumin magmas is limited to a reactive subsystem requires phaseequilibrium studies to be chemically scaled. Experiments, eitherof total or partial equilibrium type, should aim at a closereproduction of equilibrium states specific to natural systems.The laboratory reconstruction of the natural equilibrium statesguarantees a precise determination of the pre-eruptive parametersand a reliable application of the experimental data to activevolcanic systems. KEY WORDS: silicic magmas; chemical equilibrium; timescales; experimental studies 相似文献
74.
Caroline von Bernuth 《Geoforum》2007,38(3):545-557
In recent literature, projects are mostly seen as an efficient form of organization which is particularly suited for mastering tasks of high complexity and creativity and adapting to changing economic and institutional conditions. This paper challenges the assumption that inter-firm projects are persistent organizational arrangements of production in the advertising industry and presents a novel argument about the potential threats to forms of project organization in crisis situations. By exploring the cases of Frankfurt/Main and Leipzig (East Germany), we show that the organization of production is substantially affected by periods of economic crisis or political transformation. We demonstrate that inter-firm projects might be replaced by more durable organizational configurations or might not be viewed as viable options in situations of severe rupture. This applies particularly to the cooperative arrangements in the creative process and leads to an organizational paradox. Although creativity is often a pivotal force to gain competitive advantage, the advertising agencies respond to the challenges of crises by reducing cooperation with external partners to a minimum and sometimes fully rely on in-house personnel. This threatens the potential of the respective firms to develop innovative and creative ideas which would enable the firms to acquire new customers and market segments. Instead of trying to overcome crises by focusing on their creative capabilities, many advertising agencies develop a cost-cutting strategy and rely on more durable network-forms of organization instead of inter-firm projects. 相似文献
75.
This paper presents new evidence from the Dhamar highlands, Yemen, of paleohydrologic response to fluctuations in Holocene climate. Stratigraphic, geochemical, and chronological analyses of highland peat and lacustrine deposits contribute to knowledge of the timing of early Holocene moisture changes on the Arabian Peninsula, providing a backdrop to understanding early cultural development in the Arabian highlands. The location of the Dhamar highlands, characterized by intermontane valleys surrounded by the highest mountains on the Arabian Peninsula and adjacent to the Indian Ocean is ideal for examining the influence of the Indian Ocean Monsoon (IOM) on the moisture history of this region. Fluctuations in the lacustrine and paleosol records of the Dhamar highlands reflect both local changes in paleohydrology and regional influences on the Holocene paleoclimatic conditions in southwest Arabia. In addition, a peat deposit with a radiocarbon age of 10,253 – 10,560 cal yr BP documents some of the earliest Holocene high moisture conditions on the Arabian Peninsula. 相似文献
76.
77.
Tree-ring reconstructed dry season rainfall in Guatemala 总被引:1,自引:0,他引:1
Anchukaitis Kevin J. Taylor Matthew J. Leland Caroline Pons Diego Martin-Fernandez Javier Castellanos Edwin 《Climate Dynamics》2015,45(5-6):1537-1546
Climate Dynamics - Drought in Guatemala has negative consequences for agriculture and potable water supplies, particularly in regions of the country with highly seasonal rainfall. General... 相似文献
78.
Exploring high-end scenarios for local sea level rise to develop flood protection strategies for a low-lying delta—the Netherlands as an example 总被引:4,自引:1,他引:3
Caroline A. Katsman A. Sterl J. J. Beersma H. W. van den Brink J. A. Church W. Hazeleger R. E. Kopp D. Kroon J. Kwadijk R. Lammersen J. Lowe M. Oppenheimer H. -P. Plag J. Ridley H. von Storch D. G. Vaughan P. Vellinga L. L. A. Vermeersen R. S. W. van de Wal R. Weisse 《Climatic change》2011,109(3-4):617-645
Sea level rise, especially combined with possible changes in storm surges and increased river discharge resulting from climate change, poses a major threat in low-lying river deltas. In this study we focus on a specific example of such a delta: the Netherlands. To evaluate whether the country’s flood protection strategy is capable of coping with future climate conditions, an assessment of low-probability/high-impact scenarios is conducted, focusing mainly on sea level rise. We develop a plausible high-end scenario of 0.55 to 1.15 m global mean sea level rise, and 0.40 to 1.05 m rise on the coast of the Netherlands by 2100 (excluding land subsidence), and more than three times these local values by 2200. Together with projections for changes in storm surge height and peak river discharge, these scenarios depict a complex, enhanced flood risk for the Dutch delta. 相似文献
79.
Pierre Ocvirk Ariane Lançon Christophe Pichon Philippe Prugniel Damien Le Borgne Brigitte Rocca-Volmerange Michel Fioc Caroline Soubiran Eric Thiébaut 《Astrophysics and Space Science》2003,284(2):933-936
We present inversion techniques which aim at recovering the composite nature and the kinematics of a stellar population from
its high resolution absorption line spectrum. The originality of the combined inversion is its potential to recover both the
stellar content and the kinematics simultaneously. These techniques use new synthetic high resolution spectra produced by
PéGASE and minimization algorithms. We apply them to mock data representing the bulge and disk population of the inner region
of spiral galaxies.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
80.
Core-top samples from different ocean basins have been analyzed to refine our current understanding of the sensitivity of benthic foraminiferal calcite magnesium/calcium (Mg/Ca) to bottom water temperatures (BWT). Benthic foraminifera collected from Hawaii, Little Bahama Bank, Sea of Okhotsk, Gulf of California, NE Atlantic, Ceara Rise, Sierra Leone Rise, the Ontong Java Plateau, and the Southern Ocean covering a temperature range of 0.8 to 18°C were used to revise the Cibicidoides Mg/Ca-temperature calibration. The Mg/Ca-BWT relationship of three common Cibicidoides species is described by an exponential equation: Mg/Ca = 0.867 ± 0.049 exp (0.109 ± 0.007 × BWT) (stated errors are 95% CI). The temperature sensitivity is very similar to a previously published calibration. However, the revised calibration has a significantly different preexponential constant, resulting in different predicted absolute temperatures. We attribute this difference in the preexponential constant to an analytical issue of accuracy. Some genera, notably Uvigerina, show apparently lower temperature sensitivity than others, suggesting that the use of constant offsets to account for vital effects in Mg/Ca may not be appropriate. Downcore Mg/Ca reproducibility, as determined on replicate foraminiferal samples, is typically better than 0.1 mmol mol−1 (2 S.E.). Thus, considering the errors associated with the Cibicidoides calibration and the downcore reproducibility, BWT may be estimated to within ±1°C. Application of the revised core-top Mg/Ca-BWT data to Cenozoic foraminiferal Mg/Ca suggests that seawater Mg/Ca was not more than 35% lower than today in the ice-free ocean at 50 Ma. 相似文献