1,930 research outputs found

    Remediation of Contaminated Soils by Solvent Flushing

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    Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, and increases the release rates of the contaminants. A simulation model is developed to predict contaminant elution curves during solvent flushing for the case of one‐dimensional, steady flow through a contaminated medium. Column experiments are conducted with a Eustis fine sand that is initially equilibrated with an aqueous naphthalene solution, and then eluted with different methanol‐water mixtures to remove the naphthalene. The model simulations, based on parameter values estimated from literature data, agree well with the measured elution profiles. Solvent flushing experiments, where the soil was initially equilibrated with a solution of naphthalene and anthracene, show that compounds with different retardation factors are separated at low cosolvent contents, while coelution of the compounds occurs at higher contents. In general, the smaller the retardation factor in water and the higher the cosolvent fraction, the faster the contaminant is recovered. The presence of nonequilibrium conditions, soil heterogeneity, and type of cosolvent will influence the time required to recover the contaminant.\u

    The Role of Email Communications in Determining Response Rates and Mode of Participation in a Mixed-mode Design

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    This article is concerned with the extent to which the propensity to participate in a web-face-to-face sequential mixed-mode survey is influenced by the ability to communicate with sample members by email in addition to mail. Researchers may be able to collect email addresses for sample members and to use them subsequently to send survey invitations and reminders. However, there is little evidence regarding the value of doing so. This makes it difficult to decide what efforts should be made to collect such information and how to subsequently use it efficiently. Using evidence from a randomized experiment within a large mixed-mode national survey, we find that using a respondent-supplied email address to send additional survey invites and reminders does not affect survey response rate but is associated with an increased proportion of responses by web rather than face to face and, hence, lower survey costs

    Discovering and Recovering the Nineteenth-Century Journals of Martha E. McMillan in an American Women Writer’s Course: A Collaborative Digital Recovery Project

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    The following essay tells a story about an undergraduate American Women Writer\u27s course, the University archives, a nineteenth-century journal, and a Digital Recovery project. The essay explains that the story of undergraduates and their work to discover and to recover a primary text within the context of a single course could not have happened without collaboration. Because our story is a story of collaboration, I cannot tell it alone. I am Michelle Wood, an Associate Professor of English who teaches American Literature. During spring semester 2015, I collaborated with Lynn Brock, the Dean of Library Sciences, to create an archival recovery project for a course entitled American Women Writers. Together we will tell our story

    Discovering and Recovering the Nineteenth-Century Journals of Martha E. McMillan in an American Women Writer’s Course: A Collaborative Digital Recovery Project

    Get PDF
    The following essay tells a story about an undergraduate American Women Writer\u27s course, the University archives, a nineteenth-century journal, and a Digital Recovery project. The essay explains that the story of undergraduates and their work to discover and to recover a primary text within the context of a single course could not have happened without collaboration. Because our story is a story of collaboration, I cannot tell it alone. I am Michelle Wood, an Associate Professor of English who teaches American Literature. During spring semester 2015, I collaborated with Lynn Brock, the Dean of Library Sciences, to create an archival recovery project for a course entitled American Women Writers. Together we will tell our story

    Differential effects of dietary supplements on metabolomic profile of smokers versus non-smokers.

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    BackgroundCigarette smoking is well-known to associate with accelerated skin aging as well as cardiovascular disease and lung cancer, in large part due to oxidative stress. Because metabolites are downstream of genetic variation, as well as transcriptional changes and post-translational modifications of proteins, they are the most proximal reporters of disease states or reversal of disease states.MethodsIn this study, we explore the potential effects of commonly available oral supplements (containing antioxidants, vitamins and omega-3 fatty acids) on the metabolomes of smokers (n = 11) compared to non-smokers (n = 17). At baseline and after 12 weeks of supplementation, metabolomic analysis was performed on serum by liquid and gas chromatography with mass spectroscopy (LC-MS and GC-MS). Furthermore, clinical parameters of skin aging, including cutometry as assessed by three dermatologist raters blinded to subjects' age and smoking status, were measured.ResultsLong-chain fatty acids, including palmitate and oleate, decreased in smokers by 0.76-fold (P = 0.0045) and 0.72-fold (P = 0.0112), respectively. These changes were not observed in non-smokers. Furthermore, age and smoking status showed increased glow (P = 0.004) and a decrease in fine wrinkling (P = 0.038). Cutometry showed an increase in skin elasticity in smokers (P = 0.049) but not in non-smokers. Complexion analysis software (VISIA) revealed decreases in the number of ultraviolet spots (P = 0.031), and cutometry showed increased elasticity (P = 0.05) in smokers but not non-smokers.ConclusionsAdditional future work may shed light on the specific mechanisms by which long-chain fatty acids can lead to increased glow, improved elasticity measures and decreased fine wrinkling in smokers' skin. Our study provides a novel, medicine-focused application of available metabolomic technology to identify changes in sera of human subjects with oxidative stress, and suggests that oral supplementation (in particular, commonly available antioxidants, vitamins and omega-3 fatty acids) affects these individuals in a way that is unique (compared to non-smokers) on a broad level

    Infrared Nonlinear Optics

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    Contains report on one research project.U. S. Air Force - Office of Scientific Research (Grant AFOSR-76-2894

    Infrared Nonlinear Optics

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    Contains research objectives and summary of research on one research project.U. S. Air Force - Office of Scientific Research (Grant AFOSR-76-2894

    An evaluation and comparison of conservation guidelines for an at-risk migratory songbird

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    For at-risk wildlife species, it is important to consider conservation within the process of adaptive management. Golden-winged Warblers (Vermivora chrysoptera) are Neotropical migratory songbirds that are experiencing long-term population declines due in part to the loss of early-successional nesting habitat. Recently-developed Golden-winged Warbler habitat management guidelines are being implemented by USDA: Natural Resource Conservation Service (2014) and its partners through the Working Lands For Wildlife (WLFW) program. During 2012–2014, we studied the nesting ecology of Golden-winged Warblers in managed habitats of the eastern US that conformed to WLFW conservation practices. We evaluated five NRCS “management scenarios” with respect to nesting success and attainment of recommended nest site vegetation conditions outlined in the Golden-winged Warbler breeding habitat guidelines. Using estimates of territory density, pairing rate, nest survival, and clutch size, we also estimated fledglingproductivity (number of fledglings/ha) for each management scenario. In general, Golden-winged Warbler nest survival declined as each breeding season advanced, but nest survival was similar across management scenarios. Within each management scenario, vegetation variables had little influence on nest survival. Still, percent Rubus cover and density of \u3e2 m tall shrubs were relevant in some management scenarios. All five management scenarios rarely attained recommended levels of nest site vegetation conditions for Golden-winged, yet nest survival was high. Fledgling productivity estimates for each management scenario ranged from 2.1 to 8.6 fledglings/10 hectares. Our results indicate that targeted habitat management for Golden-winged Warblers using a variety of management techniques on private lands has the capability to yield high nest survival and fledgling productivity, and thus have the potential to contribute to the species recovery

    Parity nonconservation in heavy atoms: The radiative correction enhanced by the strong electric field of the nucleus

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    Parity nonconservation due to the nuclear weak charge is considered. We demonstrate that the radiative corrections to this effect due to the vacuum fluctuations of the characteristic size larger than the nuclear radius r0r_0 and smaller than the electron Compton wave-length ΝC\lambda_C are enhanced because of the strong electric field of the nucleus. The parameter that allows one to classify the corrections is the large logarithm ln⁥(ΝC/r0)\ln(\lambda_C/r_0). The vacuum polarization contribution is enhanced by the second power of the logarithm. Although the self-energy and the vertex corrections do not vanish, they contain only the first power of the logarithm. The value of the radiative correction is 0.4% for Cs and 0.9% for Tl, Pb, and Bi. We discuss also how the correction affects the interpretation of the experimental data on parity nonconservation in atoms.Comment: 4 pages, 3 figures, RevTe

    Precise calculation of parity nonconservation in cesium and test of the standard model

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    We have calculated the 6s-7s parity nonconserving (PNC) E1 transition amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in the calculation of the correlations and have included all significant contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times 10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations used for the interpretation of Cs PNC experiments. The resulting nuclear weak charge Q_{W} for Cs deviates by about 2 standard deviations from the value predicted by the standard model.Comment: 24 pages, 8 figure
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