Exploring effects of climate change on Northern Plains American Indian health     

John T. Doyle  Margaret Hiza Redsteer  Margaret J. Eggers 《Climatic change》2013,120(3):643-655

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   

New phase-coherent measurements of pulsar braking indices     

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   

Testing variograms for positive-definiteness     

Margaret Armstrong  Phil Diamond 《Mathematical Geology》1984,16(4):407-421

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   

Magnetic cleansing of weathered/tarry oiled feathers--the role of pre-conditioners     

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   

Understanding ancient, modern and future biotic responses to environmental change     

Margaret L. Fraiser  Guest Editor 《Global and Planetary Change》2009,65(3-4):105-106

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Depositional ice nucleation on NX illite and mixtures of NX illite with organic acids     

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 S_ice = 1.07 ± 0.01 at ?47 °C, with S_ice slightly increasing at lower temperatures. In contrast, pure M5 is a poorer ice nucleus with S_ice = 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   

Comparison of garnet-biotite, calcite-graphite, and calcite-dolomite thermometry in the Grenville Orogen; Ontario, Canada     

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   

Development of a distributed hydrological model to facilitate watershed management     

Sisi Li  Margaret Gitau  Bernard A. Engel  Yun Du  Carlington Wallace 《水文科学杂志》2017,62(11):1755-1771

To facilitate precise and cost-effective watershed management, a simple yet spatially and temporally distributed hydrological model (DHM-WM) was developed. The DHM-WM is based on the Mishra-Singh version of the curve number method, with several modifications: The spatial distribution of soil moisture was considered in moisture updating; the travel time of surface runoff was calculated on a grid cell basis for routing; a simple tile flow module was included as an option. The DHM-WM was tested on a tile-drained agricultural watershed in Indiana, USA. The model with the tile flow module performed well in the study area, providing a balanced water budget and reasonable flow partitioning. The daily coefficient of determination and Nash-Sutcliffe coefficient were 0.58 and 0.56, for the calibration period, and 0.63 and 0.62 for the validation period. The DHM-WM also provides detailed information about the source areas of flow components, the travel time and pathways of surface runoff.