5,183 research outputs found

    A Survey of Lentic Waters with Respect to Dissolved and Particulate Lead

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    Some of the strongest temperature inversions in the world occur at Fairbanks, Alaska. Benson (1970) has reported that a temperature gradient of 10 to 30C/1OO m is common in the winter inversions that form at Fairbanks. Air pollution is especially severe during these inversions when it is accompanied by the formation of ice crystals in the air, a condition known as ice fog. This phenomenon occurs when the temperature drops below -20F (-35C) (Benson, 1970), and it intensifies with time if the inversion is not broken. The ice crystals in this fog have been found to adsorb dust and gasses, including the lead halides which are present in the air as a result of the combustion of tetraethyl lead and/or other lead-hydrocarbon compounds used as anti-knock additives in automotive gasoline. Lazrus et al. (1970) have found lead concentrations in precipitation to be highly significantly correlated with the amount of gasoline used in the area sampled. There are two factors that bring the concentration of lead to high levels in ice fogs. Evaporation of the ice crystals tends to concentrate pollutants in the air mass, especially over the core area of the city where precipitation is retarded by the heating effect of the city. Also, during the extreme cold weather accompanying this phenomenon, many people allow their cars to idle when they are parked to increase performance and for reasons of personal comfort. Eventually, much of the pollutants suspended in the ice fog is precipitated and causes unnaturally high levels of lead in the snow. (Winchester et al., 1967). It is suspected that some of this particulate lead collected in the snow may be carried along with the associated surface runoff into 1entic (standing) surface waters during thawing. The objectives of this project were: 1. to measure the amount of dissolved and particulate lead in a number of selected 1entic waters in the Fairbanks area, and 2. to measure the amount of lead that has been incorporated into net plankton organisms located in the selected lentic waters.The work upon which this report is based was supported by funds (Project A-035-ALAS) provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Act of 1964, as amended

    Blindfolding the Jury

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    Nutrient chemistry of a large, deep lake in subarctic Alaska

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    Project Officer Eldor W. Schallock Assessment and Criteria Development Division Corvallis Environmental Research Laboratory Corvallis, Oregon 97330;Corvallis Environmental Research Laboratory Office of Research and Development U. S. Environmental Protection Agency Corvallis, Oregon 97330; R800276The primary objective of this project was to assess the state of the water quality of Harding Lake, and to attempt to predict the effects of future development within its watershed. Since the major effect of degradation of water quality due to human activity is the promotion of nuisance growths of plants, the major emphasis was placed on measurements of plant growth and concentrations of the major nutrients they require. Planktonic algal growth was found to be low, below 95.6 gm/m2/year, and the growth of submerged rooted plants was found to be relatively less important at approximately 1.35 gm/m2/year. Measurements of the growth of attached algae were not conducted, therefore the relative importance of their growth is currently unknown. A model for predicting the effect of future real estate development in the watershed was modified and applied to this lake. This model adequately describes current water quality conditions, and is assumed to have some predictive ability, but several cautions concerning application of this model to Harding Lake are discussed. A secondary objective was to study the thermal regime of a deep subarctic lake. Intensive water temperature measurements were made throughout one year and less intensive measurements were conducted during two additional years. The possibility that this lake may occasionally stratify thermally under the ice and not mix completely in the spring was discovered. The implications of this possibility are discussed for management of subarctic lakes. Hydrologic and energy budgets of this lake are attempted; the annual heat budget is estimated at 1.96 x 104 ± 1.7 x 103 cal/cm2. The results of a study of domestic water supply and waste disposal alternatives in the watershed, and the potential for enteric bacterial contamination of the lake water are presented. Limited work on the zooplankton, fishes, and benthic macroinvertebrates of this lake is also presented

    Timesharing performance as an indicator of pilot mental workload

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    Attentional deficits (workloads) were evaluated in a timesharing task. The results from this and other experiments were incorporated into an expert system designed to provide workload metric selection advice to non-experts in the field interested in operator workload

    The Nature Conservancy's Emiquon Nature Preserve Fish and Aquatic Vegetation Monitoring Annual Report

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    Key Ecological Attributes (KEA’s) for thefish and aquatic vegetation communities are used toevaluate theprogressof the restoration efforts at Thompson and Flag lakes of The Nature Conservancy’s Emiquon Nature Preserve.A total of 19 KEA criteria were monitored monthlybetween 4/21/2015-10/23/2015. Of thosecriteria set by the Emiquon Science Advisory Council, 15were met in 2015. The 2015water transparency values were within the desired range (Secchi depths no less than half the maximum water depth when a site is ≀1.5 m deep). However, when 2015results are compared to 2014, we see that the mean monthly transparencies for April-May were lowerthan the same period in 2014. In contrast,transparencies between June-Octoberwere higherthan the corresponding in 2014. Thus,while KEA criteria are being met, there is still room for improvement.The aquatic vegetation community in 2015 continued to be dominated by native aquatic plant species.Despite the dominance by natives, twoinvasive aquatic plants-Eurasian watermilfoilandcurly-leaf pondweedwere among the species collected in 2015.Eurasian watermilfoil and curly-leaf pondweed, while still not dominant,were found at moresites and at a higherdensity than in 2014.An invasive submersed aquatic vegetation species known as Egeria was collected for the first time in 2014 since restoration but was not observed or collectedin 2015.If this increase in densityof these non-natives is an on-going trend, then consideration may need to be given on how to manage theseinvasive plants.The fish community in 2015continuedto be dominated byan increasing number of native species. Despite this, the KEA goal of collecting ≄25 native fish species was not met.Bluegilldominated our catches in 2015whilecatchesof other desirable native fishes including freshwater drum, grass pickerel, and longnose gar were presentbut lowin numbers. Despite the low numbers of thesenative fishes, these were still the highest catches for these species ever observed at the Emiquon Preserve.Of the 21fish species collectedin 2015,only one non-native speciesconsisting of the common carpwas collected. Total common carp catchwas lower than 2014catches and wasthe lowest catch of this species since restoration.The Nature Conservancyunpublishednot peer reviewe

    Physics Potential of Very Intense Conventional Neutrino Beams

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    The physics potential of high intensity conventional beams is explored. We consider a low energy super beam which could be produced by a proposed new accelerator at CERN, the Super Proton Linac. Water Cherenkov and liquid oil scintillator detectors are studied as possible candidates for a neutrino oscillation experiment which could improve our current knowledge of the atmospheric parameters and measure or severely constrain the parameter connecting the atmospheric and solar realms. It is also shown that a very large water detector could eventually observe leptonic CP violation. The reach of such an experiment to the neutrino mixing parameters would lie in-between the next generation of neutrino experiments (MINOS, OPERA, etc) and a future neutrino factory.Comment: Talk given at the Venice Conference on Neutrino Telescopes, Venice, March, 200

    A ‘healthy baby’: The double imperative of preimplantation genetic diagnosis

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 The Authors.This article reports from a study exploring the social processes, meanings and institutions that frame and produce ‘ethical problems’ and clinical dilemmas for practitioners, scientists and others working in the specialty of preimplantation genetic diagnosis (PGD). A major topic in the data was that, in contrast to IVF, the aim of PGD is to transfer to the woman’s womb only those embryos likely to be unaffected by serious genetic disorders; that is, to produce ‘healthy babies’. Staff described the complex processes through which embryos in each treatment cycle must meet a double imperative: they must be judged viable by embryologists and ‘unaffected’ by geneticists. In this article, we focus on some of the ethical, social and occupational issues for staff ensuing from PGD’s double imperative.The Wellcome Trus

    Brain-specific tropomyosins TMBr-1 and TMBr-3 have distinct patterns of expression during development and in adult brain

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    In this study we report on the developmental and regional expression of two brain-specific isoforms of tropomyosin, TMBr-1 and TMBr-3, that are generated from the rat alpha-tropomyosin gene via the use of alternative promoters and alternative RNA splicing. Western blot analysis using an exon-specific peptide polyclonal antibody revealed that the two isoforms are differentially expressed in development with TMBr-3 appearing in the embryonic brain at 16 days of gestation, followed by the expression of TMBr-1 at 20 days after birth. TMBr-3 was detected in all brain regions examined, whereas TMBr-1 was detected predominantly in brain areas that derived from the prosencephalon. Immunocytochemical studies on mixed primary cultures made from rat embryonic midbrain indicate that expression of the brain-specific epitope is restricted to neurons. The developmental pattern and neuronal localization of these forms of tropomyosin suggest that these isoforms have a specialized role in the development and plasticity of the nervous system
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