Collaborative research and development (R&D) for climate technology transfer and uptake in developing countries: towards a needs driven approach     

David Ockwell  Ambuj Sagar  Heleen de Coninck 《Climatic change》2015,131(3):401-415

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Projected changes in diverse ecosystems from climate warming and biophysical drivers in northwest Alaska     

Mark Torre Jorgenson  Bruce G. Marcot  David K. Swanson  Janet C. Jorgenson  Anthony R. DeGange 《Climatic change》2015,130(2):131-144

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Nocturnal isoprene declines in a semi-urban environment     

David Doughty  Jose D. Fuentes  Ricardo Sakai  Xiao-Ming Hu  Kevin Sanchez 《Journal of Atmospheric Chemistry》2015,72(3-4):215-234

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Vulnerability assessment for loss of access to drinking water due to extreme weather events   总被引：1，自引：0，他引：1  

Jeanne Luh  Elizabeth C. Christenson  Aizhan Toregozhina  David A. Holcomb  Tucker Witsil  Laura R. Hamrick  Edema Ojomo  Jamie Bartram 《Climatic change》2015,133(4):665-679

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The energy balance over land and oceans: an assessment based on direct observations and CMIP5 climate models   总被引：2，自引：0，他引：2  

Martin Wild  Doris Folini  Maria Z. Hakuba  Christoph Schär  Sonia I. Seneviratne  Seiji Kato  David Rutan  Christof Ammann  Eric F. Wood  Gert König-Langlo 《Climate Dynamics》2015,44(11-12):3393-3429

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Displaced non-Keplerian orbits using impulsive thrust     

Colin R. McInnes 《Celestial Mechanics and Dynamical Astronomy》2011,110(3):199-215

This paper investigates new families of displaced, highly non-Keplerian orbits in the two-body problem and artificial equilibria in the circular restricted three-body problem. The families of orbits presented extend prior work by using periodic impulses to generate displaced orbits rather than continuous thrust. The new displaced orbits comprise a sequence of individual Keplerian arcs whose intersection is continuous in position, with discontinuities in velocity removed using impulses. For frequent impulses the new families of orbits approximate continuous thrust non-Keplerian orbits found in previous studies. To generate approximations to artificial equilibria in the circular restricted three-body problem, periodic impulses are used to generate a sequence of connected three-body arcs which begin and terminate at a fixed position in the rotating frame of reference. Again, these families of orbits reduce to the families of artificial equilibria found using continuous thrust.  相似文献   

MIL 03443, a dunite from asteroid 4 Vesta: Evidence for its classification and cumulate origin     

Andrew W. BECK  David W. MITTLEFEHLDT  Harry Y. McSWEEN Jr  Douglas RUMBLE III  Cin‐Ty A. LEE  Robert J. BODNAR 《Meteoritics & planetary science》2011,46(8):1133-1151

Abstract– The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than with mesosiderites. Similarities in olivine and pyroxene FeO/MnO ratios, mineral compositions, and unusual mineral inclusions between MIL 03443 and the diogenites support their formation on a common parent body. This hypothesis is bolstered by oxygen isotopic and bulk geochemical data. Beyond evidence for its reclassification, we present observations and interpretations that MIL 03443 is probably a crustal cumulate rock like the diogenites, rather than a sample of the Vestan mantle.  相似文献   

Cosmic‐ray exposure history of the Norton County enstatite achondrite     

G. F. HERZOG  David FINK  Jeffrey KLEIN  Donald D. BOGARD  L. E. NYQUIST  C.‐Y. SHIH  D. H. GARRISON  Young REESE  J. MASARIK  R. C. REEDY  G. RUGEL  T. FAESTERMANN  G. KORSCHINEK 《Meteoritics & planetary science》2011,46(2):284-310

Abstract– We report measurements of cosmogenic nuclides in up to 11 bulk samples from various depths in Norton County. The activities of ³⁶Cl, ⁴¹Ca, ²⁶Al, and ¹⁰Be were measured by accelerator mass spectrometry; the concentrations of the stable isotopes of He, Ne, Ar, and Sm were measured by electron and thermal ionization mass spectrometry, respectively. Production rates for the nuclides were modeled using the LAHET and the Monte Carlo N‐Particle codes. Assuming a one‐stage irradiation of a meteoroid with a pre‐atmospheric radius of approximately 50 cm, the model satisfactorily reproduces the depth profiles of ¹⁰Be, ²⁶Al, and ⁵³Mn (<6%) but overestimates the ⁴¹Ca concentrations by about 20%. ³He, ²¹Ne, and ²⁶Al data give a one‐stage cosmic‐ray exposure (CRE) age of 115 Ma. Argon‐36 released at intermediate temperatures, ³⁶Ar_n, is attributed to production by thermal neutrons. From the values of ³⁶Ar_n, an assumed average Cl concentration of 4 ppm, and a CRE age of 115 Ma, we estimate thermal neutron fluences of 1–4 × 10¹⁶ neutrons cm^?2. We infer comparable values from ε¹⁴⁹Sm and ε¹⁵⁰Sm. Values calculated from ⁴¹Ca and a CRE age of 115 Ma, 0.2–1.4 × 10¹⁶ neutrons cm^?2, are lower by a factor of approximately 2.5, indicating that nearly half of the ¹⁴⁹Sm captures occurred earlier. One possible irradiation history places the center of proto‐Norton County at a depth of 88 cm in a large body for 140 Ma prior to its liberation as a meteoroid with a radius of 50 cm and further CRE for 100 Ma.  相似文献   

The chemical composition of solar-type stars in comparison with that of the Sun     

Bengt Gustafsson  Jorge Meléndez  Martin Asplund  David Yong 《Astrophysics and Space Science》2010,328(1-2):185-191

The question whether the solar chemical composition is typical for solar-type stars is analysed by comparing the Sun with different stellar samples, including a sample of stars with very similar parameters, solar twins. Although typical in terms of overall metallicity for stars of solar age and galactic orbit, the solar atmosphere is found to have abundances, as compared with solar twins, that indicate that its gas has once been affected by dust formation and dust separation. It is concluded that this may be related to the formation of the solar planetary system and its special properties.  相似文献   

Thermal contraction crack polygons on Mars: A synthesis from HiRISE, Phoenix, and terrestrial analog studies     

Joseph S. Levy  David R. Marchant 《Icarus》2010,206(1):229-216

Thermal contraction crack polygons are complex landforms that have begun to be deciphered on Earth and Mars by the combined investigative efforts of geomorphology, environmental monitoring, physical models, paleoclimate reconstruction, and geochemistry. Thermal contraction crack polygons are excellent indicators of the current or past presence of ground ice, ranging in ice content from weakly cemented soils to debris-covered massive ice. Relative to larger topographic features, polygons may form rapidly, and reflect climate conditions at the time of formation—preserving climate information as relict landforms in the geological record. Polygon morphology and internal textural characteristics can be used to distinguish surfaces modified by the seasonal presence of a wet active layer or dry active layer, and to delimit subsurface ice conditions. Analysis of martian polygon morphology and distribution indicates that geologically-recent thermal contraction crack polygons on Mars form predominantly in an ice-rich latitude-dependent mantle, more likely composed of massive ice deposited by precipitation than by cyclical vapor diffusion into regolith. Regional and local heterogeneities in polygon morphology can be used to distinguish variations in ice content, deposition and modification history, and to assess microclimate variation on timescales of ka to Ma. Analyses of martian polygon morphology, guided by investigations of terrestrial analog thermal contraction crack polygons, strongly suggest the importance of excess ice in the formation and development of many martian thermal contraction crack polygons—implying the presence of an ice-rich substrate that was fractured during and subsequent to obliquity-driven depositional periods and continually modified by ongoing vapor equilibration processes.  相似文献