879 research outputs found

    Textural and geochemical characteristics of hematitic chert deposits in SW Norway: Implications for formation settings and processes

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    Postponed access: the file will be accessible after 2019-11-17Jasper, a specific type of hematitic chert, is often interpreted as an ancient analogue to modern seafloor hydrothermal deposits. Modern low-temperature seafloor hydrothermal Fe-deposits are mainly produced by Fe(II)- oxidising chemolithoautotrophs, which produce characteristic filamentous microstructures. Hematitic cherts from the SW Norwegian ophiolithic terrain exposed on the islands Stord and Bømlo have not been examined within the scope of this potential formation process. In this study, 10 hematitic chert samples were investigated to clarify the processes leading to their formation and if they all formed analogously to modern seafloor hydrothermal Fe-deposits. Additionally it was examined how the presence of hematitic cherts within the ophiolitic terrain can help to improve the understanding of the areas’ geological history. Geochemical, textural, and mineralogical analyses were conducted by applying inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry, optical microscopy, scanning electron microscopy, and Raman spectroscopy. Pronounced geochemical and textural differences were found, and four subtypes of hematitic chert were defined. Bedded hematitic radiolarian cherts (Lower/Middle Ordovician, Langevåg on Bømlo and Sagvåg on Stord) consist of SiO2 (~77 – 87 wt%), Al2O3 (~6 – 10 wt%), and Fe2O3 (~3- 6 wt%), and they have relatively high trace and rare earth element (REE) concentrations ( ΣREE ~30 – 66 ppm). Radiolarian shell remnants and distinct layering are present. A sampled hematitic radiolarian chert band (late Cambrian, Geitung by Bømlo) closely resembles the bedded cherts, but exhibits a much lower Al2O3 content, and significantly lower trace element contents and REE sum (2.8 ppm). Jasper (late Cambrian) differs vastly, no layering is present and Fe2O3 and SiO2 (~3- 23wt% and ~75 – 92 wt%, respectively) dominate, while Al2O3 is negligibly low. Trace element and REE concentrations are very low ( ΣREE ~1.1 - 3.0ppm). Two types of jasper can be distinguished. Abiogenic jasper (Geitung by Bømlo) is characterised by the absence of filaments, but contains hematite crystals occurring in concentrated clusters of polygonal patches, indicating a gel precursor undergoing syneresis. Microbially induced jasper (Finnås on Bømlo) contains a high abundance of hematite crystals comprising filamentous structures interpreted to be of microbial origin. This study demonstrates that the hematitic cherts on Stord and Bømlo have different formation processes. The hematitic radiolarian cherts are interpreted to have formed mainly from radiolarian ooze and terrigenous/volcaniclastic input. They clearly cannot be seen as analogues to modern Fe-deposits in seafloor hydrothermal systems. The abiogenic and microbially induced jaspers very likely originate from low-temperature hydrothermal fluids, emanating from the seafloor. The abiogenic jasper formation can be explained by diffusely venting fluids forming Fe-Si-oxyhydroxide gels, in which abiogenic precipitation took place. Temperatures were potentially too high for Fe(II)-oxidising chemolithoautotrophs to thrive, explaining the absence of filamentous structures. The microbially induced jasper is interpreted as having formed by diffuse venting leading to mound formation in which redox conditions and temperatures were favourable for Fe(II)-oxidisers, causing filament formation. This can potentially serve as an ancient analogue to modern hydrothermal Fe-deposits found in the Jan Mayen Vent Fields and several other vent fields. The bedded hematitic radiolarian cherts formed during the Lower/Middle Ordovician within a widening back-arc basin with suboxic seafloor conditions. Landmasses nearby provided terrigenous volcaniclastic input. The jaspers, both abiogenic and microbially induced, formed in the deep sea during the early stages of an immature island arc in the late Cambrian. The late Cambrian radiolarian chert band formed coevally, but during a quiescent phase and was potentially unaffected by hydrothermal fluids.Master's Thesis in Earth ScienceGEOV39

    Nanofluid enhancement of mineral oil and thermal properties instrument design.

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    There are two purposes of this research, to design and build a heat transfer cell that could accurately calculate heat transport coefficients of various fluids and to determine if the increased heat transfer capabilities of nanofluids can be applied to cooling transformers by using the heat transfer cell to measure the enhancement. The design and construction of a heat transfer cell that could accurately calculate heat transport coefficients of various fluids was successful. A heat transfer cell was built and tested on several fluids to confirm the accuracy of the design and the experiments. Three fluids were successfully tested overall for their thermal conductivity values, and one fluid was tested for its convection coefficients in the heat transfer cells. Values for the thermal conductivity and the convection coefficients were obtained during this experiment that agreed with commonly accepted values for the testing fluids. The average value for the thermal conductivities for mineral oil of the first design in the ¼” diameter cell is 0.15 w/m2c, and agrees well with the commonly accepted values of mineral oils. The value commonly accepted value of thermal conductivity for mineral oil is 0.14 w/m2c at 25°C, the first heat transfer cell yielded a thermal conductivity value of approximately 0.16 w/m2c at roughly 25C. The heat transfer cell was also used to calculated convection coefficients of mineral oil, and values were obtained within the limits for natural convection according to Incropera, contributing more to the validity of the results from this heat transfer cell. A second heat transfer cell was designed to determine the thermal conductivities of more thermally sensitive fluids, offering a wider range of materials that can be tested. The second design places the thermocouples directly at their assumed position of the wire and the wall temperatures for calculation purposes, yielding more accurate results and can therefore more accurately calculate the thermal conductivities of various fluids. The second design calculated a thermal conductivity of water to be 0.59 w/m2c, while the commonly accepted value is 0.58 w/m2c, which is well within a tolerable range of error to accept this value as accurate at the experimental conditions. This heat transfer cell also calculated the thermal conductivity value for AMSOIL synthetic motor oil to be 0.12 w/m2c and 0.10 w/m2c for mineral oil, both of these values are within the expected ranges of thermal conductivity for oils. The second goal of applying the heat transfer enhancement properties of a nanofluid to a transformer cooling application proved to be futile for Copper Oxide(40nm) and Carbon coated Copper nanoparticles(25nm) in mineral oil. All of the attempted nanofluids fell out of suspension within a timeframe of a day, and in a transformer cell where natural convection is the only means of flow available that contributes to keeping the nanoparticles suspended, there is not enough flow to keep the nanoparticles from falling out of suspension. That is why unless the transformer industry moves towards another coolant besides mineral oil, heat transfer enhancement using Copper Oxide (40nm) or Carbon Coated nanoparticles (25nm) in a mineral oil nanofluid is not a viable option

    EDGC 6540

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    This course provides an overview of the application of counseling theory to counseling practice of counseling in human services agencies and other community settings. Emphasis is given to the role, function, and professional identity of community counselors, and to principles and practices of community outreach, intervention, education, consultation, and client advocacy

    ASEAN, 1985-2000: A US ROLE TO INFLUENCE SHAPE

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    Picturing Anna Williams Shavers

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    Anna Williams Shavers began her career at the University of Nebraska College of Law in 1989. That year, former Dean, soon-to-become Chancellor Harvey Perlman wrote a tribute to retiring Professor Lawrence Berger in which he said that the prior decades at the College had been the “Larry Berger era.”1 I remember being startled by the remark at the time, even though I had always considered (and still consider) Larry to be my father figure on the faculty. But prior eras at the College, if there were such things, would have been named for Deans (the Pound era) or world events (closure of the World War II era)—not faculty members. But now I understand Dean Perlman’s comment because I have lived through another era that could be named for a faculty member. Anna Shavers was the College’s first African- American professor, and she shepherded the College, as Professor, Associate Dean, and Acting Dean, into a new era of awareness and inclusion. She has had the single greatest effect on the culture of the Law College of anyone during my four decades here. It may well be that the “Larry Berger era” was followed immediately by the “Anna Shavers era.” But before I get to that, some history. Before coming to Nebraska, Anna had lived several varieties of life as a Black female and, in each life, she overcame any disadvantage and thrived

    The Effects of Stress and Burden on Caregivers of Individuals with a Chronic Illness

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    Informal caregivers have played a significant social and economic role in the care and treatment of individuals diagnosed with chronic illness. However, caregiving can have harmful effects on a caregiver\u27s physical, psychological, and emotional well-being. Using caregiver stress theory as the theoretical framework, the purpose of this archival research was to determine the predictive relationship of stress in relation to caregiver quality of life for 309 selected cases. Correlational and hierarchical multiple linear regression analyses were used to examine the relationship between the independent variables and the dependent variable. The independent variables examined were environment and context, stressors related to the demands of caregiving, self-appraisal of ability to cope, and caregivers\u27 knowledge and use of community and family resources. The dependent variable was the caregiver\u27s quality of life. Findings showed that independent variables of environment and context (gender, age, marital status, education, employment status, income level) accounted for 14% of the variance in caregiver quality of life. The remaining independent variables (caregiver stressors, self-appraisal of ability to cope, and knowledge and use of resources) accounted for an additional 4% of the variance. The set of independent variables in this study collectively accounted for 18% of the variability in caregiver quality of life. Caregiver knowledge and use of resources had the strongest predictive relationship with caregiver quality of life. Researchers and practitioners may use the findings to assist in identifying antecedents to caregiver stress and the strongest predictors of caregiver stress, as well as in developing appropriate and efficient interventions and social support resources to meet caregivers\u27 specific needs, reduce their stress, and promote and enhance their quality of life

    EDGC 6540

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    This course provides an overview of the application of counseling theory to counseling practice of counseling in human services agencies and other community settings. Emphasis is given to the role, function, and professional identity of community counselors, and to principles and practices of community outreach, intervention, education, consultation, and client advocacy

    EDGC 6420

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    This course provides an examination of major theories of human development, including those from physical, psychological, cognitive, social, and moral perspectives. Development is viewed across the human life span in each of these areas. The course is designed to encourage an integrated concept of these theoretical perspectives, which serves as a developmental framework for the counseling process

    EDGC 6810

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    Japan\u27s Self-Defense Forces: What Dangers to Northeast Asia?

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    Dr. Thomas Wilborn examines Japan\u27s defense policy and the capabilities of its Self-Defense Forces (SDF) to determine if the fears of a remilitarized Japan have any basis in fact. He concludes that Japanese defense policy places rigid restraints on the SDF, and that currently there is no support for anything but a thoroughly defensive military posture. Moreover, the SDF lack the force projection ability to attack any of Japan\u27s neighbors, and could not develop the ability in less than a decade--even if there were a political decision to do so. Finally, the preponderance of evidence suggests that future generations of leaders are no more likely to pursue a military role in the region than the generation which has governed since the end of American occupation, in 1952.https://press.armywarcollege.edu/monographs/1898/thumbnail.jp
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