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Elemental speciation in biomolecules by LC-ICP-MS with magnetic sector and collision cell instruments

Description: A methodology that can monitor and identify inorganic elements in biological and environmental systems was developed. Size exclusion chromatography (SEC) separates biomolecules, which are then nebulized by a microconcentric nebulizer. The resulting aerosol is desolved and introduced into either a high resolution ICP-MS device or a quadrupole device with a collision cell. Because of the high sensitivity and spectral resolution and high sample introduction efficiency, many unusual or difficult elements, such as Cr, Se, Cd and U, can be observed at ambient levels bound to proteins in human serum. These measurements are made in only a few minutes without preliminary isolation and preconcentration steps. Serum samples can be titrated with spikes of various elements to determine which proteins bind a given metal and oxidation state. Experiments concerning the effects of breaking disulfide linkages and denaturation on metal binding in proteins were also investigated. Elemental distribution in liver extract was also obtained.
Date: November 8, 1999
Creator: Wang, Jin
Partner: UNT Libraries Government Documents Department


Description: The most frequent complaint of operators in modern computer-based control rooms is that there just are not enough video display units (VDUs). In this paper we examine the basis for this concern and try to understand the technical and historical reasons for this complaint, and its implications for the design of complex human-machine systems, including the number of VDUs in the control room. The overall aim of our work is to develop human factors guidance for the review of computer-based and modernized control rooms in nuclear power plants. As part of these efforts we have conducted literature reviews and studies using both simulators and actual systems in a broad range of industries, including process control, aerospace, medical, and others. Our findings reflect the general complaint of operators across all these industries: there just are not enough VDUs in the control room. We conclude that there are three primary reasons for this complaint. First, as part of a workload management strategy, operators frequently avoid interface management tasks and do not access all the information available, preferring instead to use a fixed set of familiar displays that provide much (but not all) of the information needed. Performance thereby becomes data limited and operators complain that they do not have a sufficient number of VDUs to set up in the early phases of a high-workload period so they can get all the information they need. Second, display designs are typically not designed with operator tasks in mind. The most common method of representing information is by functions and systems. Since tasks typically cut across many systems, operators need many displays. Thus, to make task performance easier operators need additional VDUs. Finally, there is a differing ''concept of operations'' between designers and operators. Modern computer-based control rooms are designed with vast amounts of data, ...
Date: October 8, 2001
Partner: UNT Libraries Government Documents Department

Mathematical models and specific absorbed fractions of photon energy in the nonpregnant adult female and at the end of each trimester of pregnancy

Description: Mathematical phantoms representing the adult female at three, six, and nine months of gestation are described. They are modifications of the 15-year-old male/adult female phantom (15-AF phantom) of Cristy and Eckerman (1987). The model of uterine contents includes the fetus, fetal skeleton, and placenta. The model is suitable for dose calculations for the fetus as a whole; individual organs within the fetus (other than the skeleton) are not modeled. A new model for the nonpregnant adult female is also described, comprising (1) the 15-AF phantom; (2) an adjustment to specific absorbed fractions for organ self-dose from photons to better match Reference Woman masses; and (3) computation of specific absorbed fractions with Reference Woman masses from ICRP Publication 23 for both penetrating and nonpenetrating radiations. Specific absorbed fractions for photons emitted from various source regions are tabulated for the new non;pregnant adult female model and the three pregnancy models.
Date: May 8, 1995
Creator: Stabin, M.G.; Watson, E.E.; Cristy, M.; Ryman, J.C.; Eckerman, K.F.; Davis, J.L. et al.
Partner: UNT Libraries Government Documents Department

Human disease from radon exposures: the impact of energy conservation in buildings

Description: The level of radon and its daughters inside conventional buildings is often higher than the ambient background level. Interest in conserving energy is motivating home-owners and builders to reduce the rate of infiltration of fresh air into homes, and hence to increase the concentration of indoor air contaminants, including radon. It is unlikely, but possible, that the present radiation levels from radon daughters account for much of the lung cancer rate in non-smokers. In any event, it is likely that some increased lung cancer risk would result from increased radon exposures; hence, it is desirable not to allow radon concentrations to rise significantly. There are several ways to circumvent the increased risk without compromising energy conservation considerations.
Date: August 8, 1978
Creator: Budnitz, R.J.; Berk, J.V.; Hollowell, C.D.; Nazaroff, W.W.; Nero, A.V. & Rosenfeld, A.H.
Partner: UNT Libraries Government Documents Department

Workshop on short-term health effects of reactor accidents: Chernobyl

Description: The high-dose early-effects research that has been continued has been done in the context of infrequent accidents with large radiation sources and the use of bone marrow transfusions for treating malignancies, especially leukemia. It thus seemed appropriate to bring together those who have done research on and have had experience with massive whole-body radiation. The objectives were to review what is known about the acute effects of whole-body irradiation, to review the current knowledge of therapy, and particularly of the diagnostic and immunologic problems encountered in bone marrow therapy, and to compare this knowledge with observations made to date on the Chernobyl accident radiation casualties. Dr. Robert Gale, who had helped to care for these casualties, was present at the Workshop. It was hoped that such a review would help those making continuing clinical and pathological observations on the Chernobyl casualties, and that these observations would provide a basis for recommendations for additional research that might result in improved ability to manage successfully this type of severe injury.
Date: August 8, 1986
Partner: UNT Libraries Government Documents Department

High-purity germanium detection system for the in vivo measurement of americium and plutonium

Description: A high-purity germanium (HPGe) array, photon-counting system has been developed for the Rocky Flats Plant Body-Counter Medical Facility. The newly improved system provides exceptional resolutions of low-energy X-ray and gamma-ray spectra associated with the in vivo deposition of plutonium and americium. Described are the operational parameters of the system and some qualitative results illustrating detector performance for the photon emissions produced from the decay of plutonium and americium between energy ranges from 10 to 100 kiloelectron volts. Since large amounts of data are easily generated with the system, data storage, analysis, and computer software developments continue to be an essential ingredient for processing spectral data obtained from the detectors. Absence of quantitative data is intentional. The primary concern of the study was to evaluate the effects of the various physical and electronic operational parameters before adding those related entirely to a human subject.
Date: September 8, 1976
Creator: Tyree, W. H.; Falk, R. B.; Wood, C. B. & Liskey, R. W.
Partner: UNT Libraries Government Documents Department