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71.
Sandra Owens Philippe De Wals Grace Egeland Christopher Furgal Yang Mao Gerald Y. Minuk Paul A. Peters Manon Simard éric Dewailly 《Climatic change》2012,115(1):259-281
The contributions of several IPY health projects are highlighted in the context of population health indicators for Inuit Nunangat. Food and housing are two critical social determinants of health contributing to health issues on many levels. The nutritional deficit associated with food insecurity and the transition away from traditional and towards market foods represents a dual risk with profound consequences. Knowledge of the physiological benefits associated with traditional food consumption is increasing, including for mental health and chronic disease. Ensuring the safety of traditional foods in terms of zoonotic diseases is thus highly valuable and efforts to institute adequate monitoring and address knowledge gaps are underway. Acute respiratory disease among the young remains a significant public health issue with potential long term effects. The human papilloma virus is manifesting itself among women across northern Canada with high risk types that are more similar to profiles observed in Europe than in North America with possible implications for immunization programs. Despite a high prevalence of Hepatitis B virus infections among residents of Inuit Nunangat, the outcomes appear to be relatively benign. Communication of new knowledge on the manifestation of this virus among northern populations is provided to health care providers in the North through modern technology. 相似文献
72.
The interaction of fine mineral particles with stranded oil in an aqueous medium reduces the adhesion of the oil to solid surfaces, such as sediments or bedrock. The net result is the formation of stable, micron-sized, oil droplets that disperse into the water column. In turn, the increase in surface area makes the oil more available for biodegradation. This interaction, referred to as oil–mineral aggregate (OMA) formation, can explain how oiled shorelines are cleaned naturally in the absence of wave action in very sheltered coastal environments. OMA formation also plays an important role in the efficacy of shoreline treatment techniques, such as physical mixing and sediment relocation that move oiled sediments into the zone of wave action to promote the interaction between oil and mineral fines. Successful application of these shoreline treatment options has been demonstrated at two spill events (the Tampa Bay response in Florida and the Sea Empress operation in Wales) and at a controlled oil spill experiment in the field (the 1997 Svalbard ITOSS program). Sediment relocation harnesses the hydraulic action of waves so that the processes of fine-particle interaction and physical abrasion usually occur in tandem on open coasts. There has been no evidence of significant detrimental side-effects of residual oil in pelagic or benthic environments associated with the use of these treatment options to enhance rates of dispersion and oil biodegradation. 相似文献
73.
74.
High-field torque-meter measurements of diamagnetic susceptibility anisotropy of a suite of samples of Carrara marble, axially shortened by amounts up to 50% at (1.5–3.0) · 108 Pa confining pressure and at 20–500°C (mainly 400°C), have been compared with optical measurements of preferred crystallographic orientation. A revised value for the susceptibility anisotropy of calcite has been obtained from studies of single crystals, and it has been shown to be almost independent of the state of intracrystalline plastic strain. From the measured anisotropy of calcite, quantitative comparison of optical and magnetic fabric measurements is possible. It is found that these measurements agree and the implications of the observed progressive development of fabric intensity with strain are discussed. 相似文献
75.
J. C. Owens 《Journal of Geodesy》1968,42(3):277-291
The development of lasers, new electro-optic light modulation methods, and improved electronic techniques have made possible
significant improvements in the range and accuracy of optical distance measurements, thus providing not only improved geodetic
tools but also useful techniques for the study of other geophysical, meteorological, and astronomical problems. One of the
main limitations, at present, to the accuracy of geodetic measurements is the uncertainty in the average propagation velocity
of the radiation due to inhomogeneity of the atmosphere. Accuracies of a few parts in ten million or even better now appear
feasible, however, through the use of the dispersion method, in which simultaneous measurements of optical path length at
two widely separated wavelengths are used to determine the average refractive index over the path and hence the true geodetic
distance. The design of a new instrument based on this method, which utilizes wavelengths of6328 ? and3681 ? and3 GHz polarization modulation of the light, is summarized. Preliminary measurements over a5.3 km path with this instrument have demonstrated a sensitivity of3×10
−9
in detecting changes in optical path length for either wavelength using1-second averaging, and a standard deviation of3×10
−7
in corrected length. The principal remaining sources of error are summarized, as is progress in other laboratories using
the dispersion method or other approaches to the problem of refractivity correction. 相似文献
76.
Aaron J. Martin Irene Kadel-Harder Brent E. Owens Kouki Kitajima Scott D. Samson Sanjeet K. Verma 《International Geology Review》2020,62(5):523-548
ABSTRACTThe Goochland Terrane is an enigmatic crustal block in the Appalachian Piedmont Province of central Virginia, USA. Sparse exposures of terminal Mesoproterozoic and late Neoproterozoic igneous rocks in the central Goochland Terrane offer the opportunity to investigate both the continental affinity of the terrane during the Proterozoic Eon and the timing and mechanisms of crustal growth. We apply multiple geochemical tools to these rocks: tectonic discrimination using whole-rock major and trace element abundances; whole-rock Sm-Nd isotopes; O, U-Pb, and Lu-Hf isotope analyses of spots in zircon; and measurement of O isotopes in multi-grain quartz separates. Eruption of the Sabot Amphibolite protolith is difficult to date, but we tentatively assign an age of 552 ± 11 Ma. Goochland Terrane continental crust first separated from the mantle prior to ca. 1050–1010 Ma intrusion of the Montpelier Anorthosite and the State Farm Gneiss protolith. The granitic magma that became the State Farm Gneiss protolith could have been derived entirely from partial melting of this initial Goochland Terrane crust. In contrast, the magmas that became the Montpelier Anorthosite, Neoproterozoic granitoid, and the Sabot Amphibolite were mixtures of mantle melt and preexisting Goochland Terrane crust. This production of juvenile continental crust occurred during continental extension and, eventually, rifting. The timing and compositions of terminal Mesoproterozoic magmatism in the Goochland Terrane closely match those in the nearby Blue Ridge Province. Although the compositions of the Neoproterozoic magmas in the two regions are similar, intrusion and possibly eruption occurred about 10 M.y. later in the Goochland Terrane. 相似文献
77.
78.
A small experimental oil spill was conducted on the northern tip of Baffin Island Nunavut, Canada (72 degrees 31' N, 79 degrees 50' W) in August 1981, and the natural weathering of the oil has been followed by periodic visits. This paper reports on the chemical composition of oil collected in August 2001. The vast majority of the initial oil has gone, but small patches remain. Some samples remain essentially unaltered despite their 20 years of exposure to the elements, while others show that biodegradation and photooxidation can play important roles in removing the majority of the components of the oil. Using 17alpha(H)21beta(H)hopane as a conserved marker within the oil, we show that the most biodegraded sample has lost more than 87% of the hydrocarbons initially present, while another has lost a substantial proportion of its initial chrysene and alkylated congeners. Potential explanations for the different weathering patterns seen in samples collected from this small site are briefly discussed. 相似文献
79.
Characteristics of surface particles on four fans dominated by different depositional processes are investigated in the sedimentary ranges of the Aoraki–Mount Cook area, Southern Alps, New Zealand. Statistical testing shows that on three of the fans all indices of particle size and roundness differ significantly according to the depositional process: snow avalanches produce the largest and most angular particles, streamflows the smallest and most rounded, with debris flows in between. On the fourth fan affected by all of these depositional processes, particle size and roundness indicate that snow avalanches are presently dominant with streamflow playing a secondary role. The results also show that all indices of particle size are strongly correlated with each other and suggest that the principal (a-) or intermediate (b-) axis length may provide a satisfactory substitute for more complex indices of size. Indices of particle shape generally do not differ significantly between the fans, reflecting both the strong control exerted on particle shape by source area lithology and structure and the geologic similarity of the four basins. Changes in particle size and roundness occur with down-fan distance on the snow avalanche, debris flow, and hybrid fans but not on the streamflow fan. 相似文献
80.
Morphometric variables associated with 41 debris‐?ow and 18 ?uvial fans and their basins in the Southern Alps of New Zealand are examined. The results show statistically signi?cant differences in the area, maximum elevation, relief and ruggedness (Melton's R) of the basin and the area, gradient, and apex and toe elevations of the fan between debris‐?ow and ?uvial sites. Concavity of the fan longitudinal pro?le also differs between the two fan types, although this could not be tested statistically. Most of these morphometric differences re?ect differences in processes and environmental controls on them. Discriminant analysis indicates that basin area and fan gradient best differentiate the two fan types by process. Moderately strong correlations exist, on both debris‐?ow and ?uvial fans, between basin area or Melton's R and fan area. Correlations between basin area or Melton's R and fan gradient are generally weaker. The results of this study also indicate that on debris‐?ow‐prone fans the fan gradient and basin Melton's R have lower thresholds which overlap little with upper thresholds associated with basins where only stream?ow reaches the fan. These thresholds may therefore have value in preliminary morphometric assessments of debris‐?ow hazard on fans in the Southern Alps. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献