Upper Irtysh River flow since AD 1500 as reconstructed by tree rings,reveals the hydroclimatic signal of inner Asia   总被引：1，自引：0，他引：1  

Feng Chen  Yujiang Yuan  Nicole Davi  Tongwen Zhang 《Climatic change》2016,139(3-4):651-665

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How well can a convection-permitting climate model reproduce decadal statistics of precipitation,temperature and cloud characteristics?     

Erwan Brisson  Kwinten Van Weverberg  Matthias Demuzere  Annemarie Devis  Sajjad Saeed  Martin Stengel  Nicole P. M. van Lipzig 《Climate Dynamics》2016,47(9-10):3043-3061

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The Holocene tufa at Daours (Somme Valley,northern France): Malacological succession and palaeohydrological implications     

Nicole Limondin‐Lozouet  Richard C. Preece  Pierre Antoine 《Boreas: An International Journal of Quaternary Research》2013,42(3):650-663

One of the thickest and most extensive tufa deposits in northern France occurs at Daours, about 8 km upstream of Amiens at the confluence of the River Somme and its tributary the Hallue. It covers an area of about 80 ha and reaches 10 m above the level of the present valley, probably owing to the construction of a tufa barrage, which caused periodic damming of the valley. The molluscan succession from a 4‐m section through the Daours tufa provides an unusually detailed record of environmental change during the Holocene. The faunal record, supported by four radiocarbon dates, indicates that the tufa sequence at this location does not extend back to the early Holocene but began c. 7340 cal. a BP and ceased to form shortly after c. 4938 cal. a BP, consistent with the notion of a NW European ‘late Holocene tufa decline’. The molluscan record is divisible into six zones that define three aquatic phases separated by three terrestrial episodes, when the tufa surface dried out sufficiently to allow colonization by dry‐ground species, including some shade‐demanding elements. These events are also reflected by differences in the lithology of the tufa. The earliest aquatic phase at the base of the sequence represents the most stable and permanent water‐body. The two subsequent aquatic phases appear to represent smaller, more ephemeral, water‐bodies surrounded by marsh. The land snail assemblages show ecological changes within each terrestrial episode, as well as faunal differences between them. These events, which reflect changes in the local hydrology, were short‐lived, each lasting for only a few hundred years. The tufa at Daours has also yielded flint artefacts and pottery, but it seems unlikely that the dynamic environmental record of the site results from anthropogenic activity.  相似文献   

“We Don’t Take the Pledge”: Environmentality and environmental skepticism at the epicenter of US wind energy development     

Wendy Jepson  Christian Brannstrom  Nicole Persons 《Geoforum》2012,43(4):851-863

This study analyzes pro-wind, “anti-environmental” discourses prevalent among key stakeholders in Nolan County, Texas, the epicenter of US wind power. We draw upon interviews conducted within a Q-method study to examine environmental views held by key actors in wind-farm development. We frame our analysis within the theoretical field that engages the formation of environmental subjects, defined as the process through which individuals and communities align their environmental practices with state ends. We argue that this is a process that can be incomplete or in tension with other subject positions, which together may lead to unexpected environmental views. We introduce “environmental skepticism,” defined as a rejection of ecological science steeped in deep anthropocentrism and possessive individualism, as a dominant counter-narrative informing certain environmental subjectivities. The remainder of the paper describes Texas wind stakeholders’ views or subject positions on energy and the environment and reveals how environmental skepticism is not overturned even as renewable energy supports the local economy. We analyze wind stakeholders’ environmental subjectivity in terms of emergent subject positions as “reflexive environmental skepticism,” a view that accepts the economic products, processes, and policy innovations advocated by ecological modernization without accepting the core claim that innovations are required to adapt to environmental change.  相似文献   

The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines     

Hugues Lantuit  Pier Paul Overduin  Nicole Couture  Sebastian Wetterich  Felix Aré  David Atkinson  Jerry Brown  Georgy Cherkashov  Dmitry Drozdov  Donald Lawrence Forbes  Allison Graves-Gaylord  Mikhail Grigoriev  Hans-Wolfgang Hubberten  James Jordan  Torre Jorgenson  Rune Strand ?deg?rd  Stanislav Ogorodov  Wayne H. Pollard  Volker Rachold  Sergey Sedenko  Steve Solomon  Frits Steenhuisen  Irina Streletskaya  Alexander Vasiliev 《Estuaries and Coasts》2012,35(2):383-400

Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447?km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5?m? year^?1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales.  相似文献   

Total Earth Pressure Cells for Measuring Loads in a Municipal Solid Waste Landfill     

Jason Timmons  Young Min Cho  Timothy Townsend  Nicole Berge  Debra Reinhart 《Geotechnical and Geological Engineering》2012,30(1):95-105

Commercially available hydraulic total overburden pressure cells were installed in the sand drainage layer of a municipal solid waste landfill and monitored for a period of 3,110 days. Both overburden pressure and temperature were measured in the landfill as it was filled with compacted waste. Topographic surveys of the landfill were periodically conducted to measure the height of waste above the pressure cells and to determine the landfill volume for indirect unit weight estimation. The average ratio of measured to theoretically-predicted overburden pressure was 0.6, indicating that on average the pressure cells underestimated the load. The overburden pressure measured near the toe of the landfill was greater than that predicted by the unit weight of landfilled material, while most of the overburden pressure measurements further inside the landfill were less than predicted. Several possible causes for this phenomenon are discussed, including the uneven distribution of forces resulting from the heterogeneous nature of the waste and cover soil. The earth pressure cells were capable of detecting the placement of individual waste lifts.  相似文献   

Multi-spacecraft investigation of space turbulence: Lessons from Cluster and input to the Cross-Scale mission     

Fouad Sahraoui  Melvyn L. Goldstein  Alain Roux  Patrick Canu  Nicole Cornilleau-Wehrlin  Thierry Dudok De Wit  Khurom Kiyani 《Planetary and Space Science》2011,59(7):585-591

Investigating space plasma turbulence from single-point measurements is known to be characterized by unavoidable ambiguities in disentangling temporal and spatial variations. Solving this problem has been one of the major goals of the Cluster mission. For that purpose multipoint measurements techniques, such as the k-filtering, have been developed. Such techniques combine several time series recorded simultaneously at different points in space to estimate the corresponding energy density in the wavenumber space. Here we apply the technique to both simulated and Cluster magnetometer data in the solar wind (SW) and investigate the errors and limitations that arise due to the separation of the spacecraft and the quality of the tetrahedral configuration. Specifically, we provide an estimation of the minimum and maximum scales that can be accurately measured given a specific distance between the satellites and show the importance of the geometry of the tetrahedron and the relationship of that geometry to spatial aliasing. We also present recent results on characterizing small scale SW turbulence and provide scientific arguments supporting the need of new magnetometers having better sensitivity than the existing ones. Throughout the paper we emphasize technical challenges and their solutions that can be considered for a better preparation of the Cross-Scale mission.  相似文献   

Deformation,metamorphism, and mobilization of Ni–Cu–PGE sulfide ores at Garson Mine,Sudbury     

Joshua Mukwakwami  Bruno Lafrance  C. Michael Lesher  Douglas K. Tinkham  Nicole M. Rayner  Doreen E. Ames 《Mineralium Deposita》2014,49(2):175-198

The Garson Ni–Cu–platinum group element deposit is a deformed, overturned, low Ni tenor contact-type deposit along the contact between the Sudbury Igneous Complex (SIC) and stratigraphically underlying rocks of the Huronian Supergroup in the South Range of the 1.85-Ga Sudbury structure. The ore bodies are coincident with steeply south-dipping, north-over-south D₁ shear zones, which imbricated the SIC, its ore zones, and underlying Huronian rocks during mid-amphibolite facies metamorphism. The shear zones were reactivated as south-over-north, reverse shear zones during D₂ at mid-greenschist facies metamorphism. Syn-D₂ metamorphic titanite yields an age of 1,849?±?6 Ma, suggesting that D₁ and D₂ occurred immediately after crystallization of the SIC during the Penokean Orogeny. The ore bodies plunge steeply to the south parallel to colinear L₁ and L₂ mineral lineations, indicating that the geometry of the ore bodies are strongly controlled by D₁ and D₂. Sulfide mineralization consists of breccia ores, with minor disseminated sulfides hosted in norite, and syn-D₂ quartz–calcite–sulfide veins. Mobilization by ductile plastic flow was the dominant mechanism of sulfide/metal mobilization during D₁ and D₂, with additional minor hydrothermal mobilization of Cu, Fe, and Ni by hydrothermal fluids during D₂. Metamorphic pentlandite overgrows a S₁ ferrotschermakite foliation in D₁ deformed ore zones. Pentlandite was exsolved from recrystallized polygonal pyrrhotite grains after cessation of D₁, which resulted in randomly distributed large pentlandite grains and randomly oriented pentlandite loops along the grain boundaries of polygonal pyrrhotite within the breccia ore. It also overgrows a S₂ chlorite foliation in D₂ shear zones. Pyrrhotite recrystallized and was flattened during D₂ deformation of breccia ore along narrow shear zones. Exsolution of pentlandite loops along the grain boundaries of these flattened grains produced a pyrrhotite–pentlandite layering that is not observed in D₁ deformed ore zones. The overprinting of the two foliations by pentlandite and exsolution of pentlandite along the grain boundaries of flattened pyrrhotite grains suggest that the Garson ores reverted to a metamorphic monosulfide solid solution at temperatures ranging between 550 and 600 °C during D₁ and continued to deform as a monosulfide solid solution during D₂.  相似文献   

An infrared imaging survey of the faint Chandra sources near the Galactic Centre     

R. M. Bandyopadhyay  J. C. A. Miller-Jones  K. M. Blundell  F. E. Bauer  Ph. Podsiadlowski  A. J. Gosling  Q. D. Wang  E. Pfahl  S. Rappaport 《Monthly notices of the Royal Astronomical Society》2005,364(4):1195-1202

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Stellar-mass black hole binaries as ultraluminous X-ray sources     

S. A. Rappaport  Ph. Podsiadlowski  E. Pfahl † 《Monthly notices of the Royal Astronomical Society》2005,356(2):401-414

Ultraluminous X-ray sources (ULXs) with   L _x > 10³⁹ erg s⁻¹  have been discovered in great numbers in external galaxies with ROSAT , Chandra and XMM-Newton . The central question regarding this important class of sources is whether they represent an extension in the luminosity function of binary X-ray sources containing neutron stars and stellar-mass black holes (BHs), or a new class of objects, e.g. systems containing intermediate-mass BHs  (100–1000 M_⊙)  . We have carried out a theoretical study to test whether a large fraction of the ULXs, especially those in galaxies with recent star formation activity, can be explained with binary systems containing stellar-mass BHs. To this end, we have applied a unique set of binary evolution models for BH X-ray binaries, coupled to a binary population synthesis code, to model the ULXs observed in external galaxies. We find that for donor stars with initial masses  ≳10 M_⊙  the mass transfer driven by the normal nuclear evolution of the donor star is sufficient to potentially power most ULXs. This is the case during core hydrogen burning and, to an even more pronounced degree, while the donor star ascends the giant branch, although the latter phases last only ∼5 per cent of the main-sequence phase. We show that with only a modest violation of the Eddington limit, e.g. a factor of ∼10, both the numbers and properties of the majority of the ULXs can be reproduced. One of our conclusions is that if stellar-mass BH binaries account for a significant fraction of ULXs in star-forming galaxies, then the rate of formation of such systems is  ∼3 × 10⁻⁷ yr⁻¹  normalized to a core-collapse supernova rate of 0.01 yr⁻¹.  相似文献