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191.
Geraint Harker Saleem Zaroubi Gianni Bernardi Michiel A. Brentjens A. G. de Bruyn Benedetta Ciardi Vibor Jeli Leon V. E. Koopmans Panagiotis Labropoulos Garrelt Mellema ré Offringa V. N. Pandey Joop Schaye Rajat M. Thomas Sarod Yatawatta 《Monthly notices of the Royal Astronomical Society》2009,397(2):1138-1152
192.
T. Appourchaux P. Liewer M. Watt D. Alexander V. Andretta F. Auchère P. D’Arrigo J. Ayon T. Corbard S. Fineschi W. Finsterle L. Floyd G. Garbe L. Gizon D. Hassler L. Harra A. Kosovichev J. Leibacher M. Leipold N. Murphy M. Maksimovic V. Martinez-Pillet B. S. A. Matthews R. Mewaldt D. Moses J. Newmark S. Régnier W. Schmutz D. Socker D. Spadaro M. Stuttard C. Trosseille R. Ulrich M. Velli A. Vourlidas C. R. Wimmer-Schweingruber T. Zurbuchen 《Experimental Astronomy》2009,23(3):1079-1117
The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place
a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging
orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude
regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While
Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does
not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between
the magnetism and dynamics of the Sun’s polar regions and the solar cycle.
相似文献
T. AppourchauxEmail: |
193.
G. Amelino-Camelia K. Aplin M. Arndt J. D. Barrow R. J. Bingham C. Borde P. Bouyer M. Caldwell A. M. Cruise T. Damour P. D’Arrigo H. Dittus W. Ertmer B. Foulon P. Gill G. D. Hammond J. Hough C. Jentsch U. Johann P. Jetzer H. Klein A. Lambrecht B. Lamine C. Lämmerzahl N. Lockerbie F. Loeffler J. T. Mendonca J. Mester W.-T. Ni C. Pegrum A. Peters E. Rasel S. Reynaud D. Shaul T. J. Sumner S. Theil C. Torrie P. Touboul C. Trenkel S. Vitale W. Vodel C. Wang H. Ward A. Woodgate 《Experimental Astronomy》2009,23(2):549-572
The GAUGE (GrAnd Unification and Gravity Explorer) mission proposes to use a drag-free spacecraft platform onto which a number
of experiments are attached. They are designed to address a number of key issues at the interface between gravity and unification
with the other forces of nature. The equivalence principle is to be probed with both a high-precision test using classical
macroscopic test bodies, and, to lower precision, using microscopic test bodies via cold-atom interferometry. These two equivalence
principle tests will explore string-dilaton theories and the effect of space–time fluctuations respectively. The macroscopic
test bodies will also be used for intermediate-range inverse-square law and an axion-like spin-coupling search. The microscopic
test bodies offer the prospect of extending the range of tests to also include short-range inverse-square law and spin-coupling
measurements as well as looking for evidence of quantum decoherence due to space–time fluctuations at the Planck scale. 相似文献
194.
Susan L. Cutter Lindsey Barnes Melissa Berry Christopher Burton Elijah Evans Eric Tate Jennifer Webb 《Global Environmental Change》2008,18(4):598
There is considerable research interest on the meaning and measurement of resilience from a variety of research perspectives including those from the hazards/disasters and global change communities. The identification of standards and metrics for measuring disaster resilience is one of the challenges faced by local, state, and federal agencies, especially in the United States. This paper provides a new framework, the disaster resilience of place (DROP) model, designed to improve comparative assessments of disaster resilience at the local or community level. A candidate set of variables for implementing the model are also presented as a first step towards its implementation. 相似文献
195.
Keyan Fang Xiaohua Gou Fahu Chen Jinbao Li Rosanne D’Arrigo Edward Cook Tao Yang Nicole Davi 《Climate Dynamics》2010,35(4):577-585
We present a Palmer Drought Severity Index reconstruction (r = 0.61, P < 0.01) from 1440 to 2007 for the southeastern Tibetan Plateau, based on tree rings of the forest fir (Abies forrestii). Persistent decadal dry intervals were found in the 1440s–1460s, 1560s–1580s, 1700s, 1770s, 1810s, 1860s and 1980s, and
the extreme wet epochs were the 1480s–1490s, 1510s–1520s, 1590s, 1610s–1630s, 1720s–1730s, 1800s, 1830s, 1870s, 1930s, 1950s
and after the 1990s. Comparisons of our record with those identified in other moisture related reconstructions for nearby
regions showed that our reconstructed droughts were relatively consistent with those found in other regions of Indochina,
suggesting similar drought regimes. Spectral peaks of 2.3–5.5 years may be indicative of ENSO activity, as also suggested
by negative correlations with SSTs in the eastern equatorial and southeastern Pacific Ocean. Significant multidecadal spectral
peaks of 29.2–40.9 and 56.8–60.2 years were identified. As indicated by the spatial correlation patterns, the decadal-scale
variability may be linked to SST variations in the northern Pacific and Atlantic Oceans. 相似文献
196.
In this study, the geochemistry and origin of natural gas and formation waters in Devonian age organic-rich shales and reservoir sandstones across the northern Appalachian Basin margin (western New York, eastern Ohio, northwestern Pennsylvania, and eastern Kentucky) were investigated. Additional samples were collected from Mississippian Berea Sandstone, Silurian Medina Sandstone and Ordovician Trenton/Black River Group oil and gas wells for comparison. Dissolved gases in shallow groundwaters in Devonian organic-rich shales along Lake Erie contain detectable CH4 (0.01–50.55 mol%) with low δ13C–CH4 values (−74.68 to −57.86‰) and no higher chain hydrocarbons, characteristics typical of microbial gas. Nevertheless, these groundwaters have only moderate alkalinity (1.14–8.72 meq/kg) and relatively low δ13C values of dissolved inorganic C (DIC) (−24.8 to −0.6‰), suggesting that microbial methanogenesis is limited. The majority of natural gases in Devonian organic-rich shales and sandstones at depth (>168 m) in the northern Appalachian Basin have a low CH4 to ethane and propane ratios (3–35 mol%; C1/C2 + C3) and high δ13C and δD values of CH4 (−53.35 to −40.24‰, and −315.0 to −174.6‰, respectively), which increase in depth, reservoir age and thermal maturity; the molecular and isotopic signature of these gases show that CH4 was generated via thermogenic processes. Despite this, the geochemistry of co-produced brines shows evidence for microbial activity. High δ13C values of DIC (>+10‰), slightly elevated alkalinity (up to 12.01 meq/kg) and low SO4 values (<1 mmole/L) in select Devonian organic-rich shale and sandstone formation water samples suggest the presence of methanogenesis, while low δ13C–DIC values (<−22‰) and relatively high SO4 concentrations (up to 12.31 mmole/L) in many brine samples point to SO4 reduction, which likely limits microbial CH4 generation in the Appalachian Basin. Together the formation water and gas results suggest that the vast majority of CH4 in the Devonian organic-rich shales and sandstones across the northern Appalachian Basin margin is thermogenic in origin. Small accumulations of microbial CH4 are present at shallow depths along Lake Erie and in western NY. 相似文献
197.
Wheat as food, wheat as industrial substance; comparative geographies of transformation and mobility 总被引:1,自引:0,他引:1
Wheat is the world’s second largest crop, supplies 19% of human calories, and is the largest volume crop traded internationally. Its uniquely malleable physical properties make it a valued industrial substance, albeit often an invisible one, as well as a food. This combination of transformation, invisibility and mobility demands new ways of thinking about wheat geographies. In this paper we document and analyse several ‘moments’ in the life of Australian wheat; at the supermarket, in the lives of coeliac sufferers, in laboratories, industrial factories and on the farm. We illustrate diverse patterns of interaction with wheat. The major plane of differentiation is between wheat as food and wheat as industrial substance. The explicit connection of food to the human body tends to fix the identity of wheat, whether as healthy staple of the nation, or harmful poison to coeliacs who must negotiate its presence using the regulatory regime of food labelling. This is no small task given the ubiquity of wheat; our survey of 10,235 supermarket items found it in 29.5% of labelled food items. In contrast, when wheat is physically and chemically disassembled to become an industrial substance, its presence and identity become mutable, hidden and often invisible. 相似文献
198.
Yves Goddéris Jennifer Z. Williams Dave Pollard 《Geochimica et cosmochimica acta》2010,74(22):6357-6374
Anthropogenic and natural climate change affect processes in the atmosphere, biosphere, hydrosphere, and pedosphere. The impact of climate on soil evolution has not been well-explored, largely due to slow rates and the complexity of coupled processes that must be observed and simulated. The rates of mineral weathering in loess deposited 23 kyr ago and experiencing soil formation for 13 kyr are explored here using the WITCH model for weathering and the GENESIS model for climate simulation. The WITCH model, which uses rigorous kinetic parameters and laws with provision for the effect on rates of deviation from equilibrium, can successfully simulate the depletion profiles in the soil for dolomite and albite if soil CO2 is assumed to rise over the last 10 kyr up to about 30-40× the present atmospheric pressure, and if the solubility product of the Ca-smectite is assumed equal to that of an Fe(III)-rich Ca-montmorillonite. Such simulations document that dissolution behavior for silicates and carbonates are strongly coupled through pH, and for Ca-smectite and feldspars through dissolved silica. Such coupling is not incorporated in simple geometric and analytical models describing mineral dissolution, and therefore probably contributes to the long-standing observation of discrepancies among laboratory and field mineral dissolution rates. 相似文献
199.
Jennifer Lynn Bartlett Chan Park Srikrishna Kanneganti Philip A. Ianna 《New Astronomy》2010,15(6):547-553
Despite the continuing importance of ground-based parallax measurements, few active programs remain. Because new members of the solar neighborhood tend towards later spectral types, infrared parallax programs are particularly desirable. Therefore, the astrometric quality of the new infrared camera, FanCam, developed by the Virginia Astronomical Instrumentation Laboratory (VAIL) for the 31-in. (0.8 m) Tinsley reflector at Fan Mountain Observatory was assessed using 68 J-band exposures of an open cluster, NGC 2420, over a range of hour angles during 2005. Positions of 16 astrometric evaluation stars were measured and the repeatability of those positions was evaluated using the mean error in a single observation of unit weight. Overall, a precision of 1.3 ± 0.7 μm in x (RA) and 1.3 ± 0.8 μm in y (Dec) was attained, which corresponds to 0.04″ ± 0.02″ in each axis. Although greater precision is expected from CCDs in the visual and near-infrared, this instrument can achieve precision similar to that of the ESO NTT infrared parallax program. Therefore, measuring parallaxes in the infrared would be feasible using this equipment. If initiated, such a program could provide essential distances for brown dwarfs and very low mass stars that would contribute significantly to the solar neighborhood census. 相似文献
200.
This study deals with a detailed geochemical characterization of three crude oils from the Upper Indus Basin, Punjab, Pakistan.
The samples were obtained from three productive oil fields of the Datta Formation (Jurassic), Lochhart (Palaeocene) and the
Dhak Pass zone (Palaeocene). The GC parameters for and the bulk properties of Datta Formation oils are essentially coincident
with those of the oils from the Dhak Pass Formation in the Upper Indus Basin, Pakistan and the oils likely originate from
a marine source rock. In contrast, the Lockhart Formation oils show different behaviors and seem to be originated from dirty
carbonate rocks although all three crude oils are mature, being of non-biodegraded and somewhat mixed organic matter origin.
Low Pr/Ph values and high C35 homohopane index for the Lockhart Formation oils suggest a source of anoxic environment with low Eh while oils from the Datta
Formation and Dhak Pass Formation showed different trends, i.e., lower values of C35 homohopane index indicating different depositional environment than oil from the Lockhart Formation. All three crude oils
from the Upper Indus Basin are mature for the hopane ratios, i.e., Ts/Ts+Tm, C3222S/(S+R) and C30 αβ/(αβ+βα) and sterane ratios, i.e., C2922S/(S+R) and C29ββ/(ββ+αα) but oils from the Lockhart Formation seem to be less mature than those from the Palaeocene and Datta Formation
according to plots like API° vs. homohopane Index, Pr/Ph vs. sterane. The relative composition of 5α(H), 14β(H), 17β(H)-24-ethylecholestanes
and the C2920S/20S+20R index, indicate that all three crude oils are equally mature, which makes it unlikely with respect to the above
said plots. This difference is may be due to the migratory chromatography which alters the concentrations of sterane and hoapnes
and hence gives different results. These oils do not exhibit UCM and have complete n-alkane profiles indicating non-biodegradation. 相似文献