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41.
Abstract— Four meteorites from South Australia are described and classified. Streaky Bay (L4b) and Mangalo (L6e) were received by the South Australian Museum in December, 1989. Ethiudna (L4a) and Crockers Well (LL7) were previously thought to be paired and were previously described only as chondrites. 相似文献
42.
43.
Annemarie Christophersen Nicola Litchfield Kelvin Berryman Richard Thomas Roberto Basili Laura Wallace William Ries Gavin P. Hayes Kathleen M. Haller Toshikazu Yoshioka Richard D. Koehler Dan Clark Monica Wolfson-Schwehr Margaret S. Boettcher Pilar Villamor Nick Horspool Teraphan Ornthammarath Ramon Zuñiga Robert M. Langridge Mark W. Stirling Tatiana Goded Carlos Costa Robert Yeats 《Natural Hazards》2015,79(1):111-135
44.
American Indians have unique vulnerabilities to the impacts of climate change because of the links among ecosystems, cultural practices, and public health, but also as a result of limited resources available to address infrastructure needs. On the Crow Reservation in south-central Montana, a Northern Plains American Indian Reservation, there are community concerns about the consequences of climate change impacts for community health and local ecosystems. Observations made by Tribal Elders about decreasing annual snowfall and milder winter temperatures over the 20th century initiated an investigation of local climate and hydrologic data by the Tribal College. The resulting analysis of meteorological data confirmed the decline in annual snowfall and an increase in frost free days. In addition, the data show a shift in precipitation from winter to early spring. The number of days exceeding 90 ?F (32 ?C) has doubled in the past century. Streamflow data show a long-term trend of declining discharge. Elders noted that the changes are affecting fish distribution within local streams and plant species which provide subsistence foods. Concerns about warmer summer temperatures also include heat exposure during outdoor ceremonies that involve days of fasting without food or water. Additional community concerns about the effects of climate change include increasing flood frequency and fire severity, as well as declining water quality. The authors call for local research to understand and document current effects and project future impacts as a basis for planning adaptive strategies. 相似文献
45.
Margaret A. Livingstone Victoria M. Kaspi Fotis P. Gavriil Richard N. Manchester E. V. G. Gotthelf Lucien Kuiper 《Astrophysics and Space Science》2007,308(1-4):317-323
Pulsar braking indices offer insight into the physics that underlies pulsar spin-down. Only five braking indices have been
measured via phase-coherent timing; all measured values are less than 3, the value expected from magnetic dipole radiation.
Here we present new measurements for three of the five pulsar braking indices, obtained with phase-coherent timing for PSRs J1846-0258
(n=2.65±0.01), B1509-58 (n=2.839±0.001) and B0540-69 (n=2.140±0.009). We discuss the implications of these results and possible physical explanations for them.
相似文献
46.
A method based on Bochner's theorem is described for demonstrating the positive-definiteness of variogram models and for generating classes of valid variogram functions.Work performed while on leave at the Centre de Géostatistique et de Morphologie Mathématique. 相似文献
47.
Dao HV Ngeh LN Bigger SW Orbell JD Healy M Jessop R Dann P 《Marine pollution bulletin》2006,52(12):1591-1594
Iron powder has previously been demonstrated to be effective in the removal, via magnetic harvesting, of a wide variety of oil contaminants from feathers and plumage. This study investigates the efficacy of magnetic cleansing for the removal from feathers of tarry contamination that has been allowed to weather. Clusters of feathers from Mallard duck (Anas platyrhnchos) and Little Penguin (Eudyptula minor) were completely immersed in a tarry contaminant and allowed to weather from one to fourteen days. The contaminant was removed using a magnetic cleansing protocol and the removal efficacy assessed gravimetrically. For one, seven and fourteen days of weathering, a final removal (after fourteen treatments) of more than 99% and 97% was achieved for duck feathers and penguin feathers, respectively. Repeating the experiments (for a seven-day weathering period) for both duck and penguin feathers, with the judicious application of a pre-conditioner (olive oil), further improved removal efficacy. A convenient method to screen for improved pre-conditioning agents is suggested. 相似文献
48.
49.
Katherine?M.?PrimmEmail author Gregory?P.?Schill Daniel?P.?Veghte Miriam?Arak?Freedman Margaret?A.?Tolbert 《Journal of Atmospheric Chemistry》2017,74(1):55-69
Mineral dust particles are known to be efficient ice nuclei in the atmosphere. Previous work has probed heterogeneous ice nucleation on various laboratory dust samples including Arizona Test Dust, kaolinite, montmorillonite, and illite as atmospheric dust surrogates. However, it has recently been suggested that NX illite may be a better representation of atmospheric dust. Hiranuma et al. (2015) performed a laboratory comparison for immersion ice nucleation on NX illite, but here we focus on depositional ice nucleation because of its importance in low temperature cirrus cloud formation. A Raman microscope setup was used to examine the ice-nucleating efficiency of NX illite. Organic coatings on the NX illite particles were also investigated using a mixture of 5 dicarboxylic acids (M5). The ratio of NX illite to M5 was varied from 1:10 to 100:1. It was found that NX illite efficiently nucleates ice with Sice = 1.07 ± 0.01 at ?47 °C, with Sice slightly increasing at lower temperatures. In contrast, pure M5 is a poorer ice nucleus with Sice = 1.30 ± 0.02 at ?40 °C, relatively independent of temperature. Further, it was found that M5 coatings on the order of several monolayers thick hindered the ice nucleating ability of NX illite. Optical images suggest that at colder temperatures (< ?50 °C) 1:1 NX illite:M5 particles and pure M5 particles nucleate ice depositionally, while at warmer temperatures (> ?50 °C) subsaturated immersion ice nucleation dominates. These experiments suggest that mineral dust particles may become less active towards ice nucleation as they age in the atmosphere. 相似文献
50.
Mark A. Rathmell Margaret M. Streepey Eric J. Essene Ben A. van der Pluijm 《Contributions to Mineralogy and Petrology》1999,134(2-3):217-231
The Elzevir Terrane of the Grenville Orogen in southern Ontario contains metapelites and abundant graphitic marbles that
were regionally metamorphosed from the upper greenschist to upper amphibolite facies. Comparative thermometry was undertaken
with widely used calibrations for the systems garnet-biotite, calcite-dolomite, and calcite-graphite. Temperatures that are
obtained from matrix biotites paired with prograde garnet near-rim analyses are usually consistent with those determined using
calcite-graphite thermometry. However, calcite-graphite thermometry occasionally yields low temperatures due to lack of equilibration
of anomalously light graphite. Application of calcite-graphite and garnet-biotite systems may yield temperatures up to 70 °C
higher than calcite-dolomite in amphibolite facies rocks. Calcite-dolomite temperatures most closely approach those from calcite-graphite
and garnet-biotite when the samples contain a single generation of dolomite and calcite grains contain no visible dolomite
exsolution lamellae. However, some of these samples yield temperatures considerably lower than temperatures calculated from
calcite-graphite and garnet-biotite thermometry, indicating that the calcite-dolomite thermometer may have been partially
reset during retrogression. Estimated peak metamorphic temperatures of regional metamorphism between Madoc (upper greenschist
facies) and Bancroft (upper amphibolite facies) range from 500 to 650 °C. These results place the chlorite-staurolite isograd
at 540 °C, the kyanite-sillimanite isograd at 590 °C, and the sillimanite-K-feldspar isograd at 650 °C. Although each thermometer
may have an absolute uncertainty of as much as ±50 °C, the 50 to 60 °C temperature differences between the isograds are probably
accurate to 10 to 20 °C. An incomplete picture of the thermal gradients can result from the application of only one thermometer
in a given area. Simultaneous application of several systems allows one to recognize and overcome the inherent limitations
of each thermometer.
Received: 26 March 1997 / Accepted: 15 April 1998 相似文献