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Sample records for non-threshold lnt dose-based

  1. Regulatory implications of a linear non-threshold (LNT) dose-based risks.

    PubMed

    Aleta, C R

    2009-01-01

    Current radiation protection regulatory limits are based on the linear non-threshold (LNT) theory using health data from atomic bombing survivors. Studies in recent years sparked debate on the validity of the theory, especially at low doses. The present LNT overestimates radiation risks since the dosimetry included only acute gammas and neutrons; the role of other bomb-caused factors, e.g. fallout, induced radioactivity, thermal radiation (UVR), electromagnetic pulse (EMP), and blast, were excluded. Studies are proposed to improve the dose-response relationship.

  2. Observations on the Chernobyl Disaster and LNT

    PubMed Central

    Jaworowski, Zbigniew

    2010-01-01

    The Chernobyl accident was probably the worst possible catastrophe of a nuclear power station. It was the only such catastrophe since the advent of nuclear power 55 years ago. It resulted in a total meltdown of the reactor core, a vast emission of radionuclides, and early deaths of only 31 persons. Its enormous political, economic, social and psychological impact was mainly due to deeply rooted fear of radiation induced by the linear non-threshold hypothesis (LNT) assumption. It was a historic event that provided invaluable lessons for nuclear industry and risk philosophy. One of them is demonstration that counted per electricity units produced, early Chernobyl fatalities amounted to 0.86 death/GWe-year), and they were 47 times lower than from hydroelectric stations (∼40 deaths/GWe-year). The accident demonstrated that using the LNT assumption as a basis for protection measures and radiation dose limitations was counterproductive, and lead to sufferings and pauperization of millions of inhabitants of contaminated areas. The projections of thousands of late cancer deaths based on LNT, are in conflict with observations that in comparison with general population of Russia, a 15% to 30% deficit of solid cancer mortality was found among the Russian emergency workers, and a 5% deficit solid cancer incidence among the population of most contaminated areas. PMID:20585443

  3. Observations on the Chernobyl Disaster and LNT.

    PubMed

    Jaworowski, Zbigniew

    2010-01-28

    The Chernobyl accident was probably the worst possible catastrophe of a nuclear power station. It was the only such catastrophe since the advent of nuclear power 55 years ago. It resulted in a total meltdown of the reactor core, a vast emission of radionuclides, and early deaths of only 31 persons. Its enormous political, economic, social and psychological impact was mainly due to deeply rooted fear of radiation induced by the linear non-threshold hypothesis (LNT) assumption. It was a historic event that provided invaluable lessons for nuclear industry and risk philosophy. One of them is demonstration that counted per electricity units produced, early Chernobyl fatalities amounted to 0.86 death/GWe-year), and they were 47 times lower than from hydroelectric stations ( approximately 40 deaths/GWe-year). The accident demonstrated that using the LNT assumption as a basis for protection measures and radiation dose limitations was counterproductive, and lead to sufferings and pauperization of millions of inhabitants of contaminated areas. The projections of thousands of late cancer deaths based on LNT, are in conflict with observations that in comparison with general population of Russia, a 15% to 30% deficit of solid cancer mortality was found among the Russian emergency workers, and a 5% deficit solid cancer incidence among the population of most contaminated areas.

  4. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 2. How a mistake led BEIR I to adopt LNT.

    PubMed

    Calabrese, Edward J

    2017-04-01

    This paper reveals that nearly 25 years after the National Academy of Sciences (NAS), Biological Effects of Ionizing Radiation (BEIR) I Committee (1972) used Russell's dose-rate data to support the adoption of the linear-no-threshold (LNT) dose response model for genetic and cancer risk assessment, Russell acknowledged a significant under-reporting of the mutation rate of the historical control group. This error, which was unknown to BEIR I, had profound implications, leading it to incorrectly adopt the LNT model, which was a decision that profoundly changed the course of risk assessment for radiation and chemicals to the present.

  5. LNT IS THE BEST WE CAN DO - TO-DAY

    EPA Science Inventory

    Abstract

    The form of the dose-response curve for radiation-induced cancers, particularly at low doses, is the subject of an ongoing and spirited debate. The present review describes the current data base and basis for establishing a low dose, linear no threshold (LNT) mode...

  6. LNT IS THE BEST WE CAN DO - TO-DAY

    EPA Science Inventory

    Abstract

    The form of the dose-response curve for radiation-induced cancers, particularly at low doses, is the subject of an ongoing and spirited debate. The present review describes the current data base and basis for establishing a low dose, linear no threshold (LNT) mode...

  7. Ammonia Production and Utilization in a Hybrid LNT+SCR System

    SciTech Connect

    Prikhodko, Vitaly Y; Parks, II, James E

    2009-01-01

    A hybrid LNT+SCR system is used to control NOx from a light-duty diesel engine with in-cylinder regeneration controls. A diesel oxidation catalyst and diesel particulate filter are upstream of the LNT and SCR catalysts. Ultraviolet (UV) adsorption spectroscopy performed directly in the exhaust path downstream of the LNT and SCR catalysts is used to characterize NH3 production and utilization in the system. Extractive exhaust samples are analyzed with FTIR and magnetic sector mass spectrometry (H2) as well. Furthermore, standard gas analyzers are used to complete the characterization of exhaust chemistry. NH3 formation increases strongly with extended regeneration (or over regeneration ) of the LNT, but the amount of NOx reduction occurring over the SCR catalyst is limited by the amount of NH3 produced as well as the amount of NOx available downstream of the LNT. Control of lean-rich cycling parameters enables control of the ratio of NOx reduction between the LNT and SCR catalysts. During lean-rich cycling, fuel penalties are similar for either LNT dominant or LNT with supplemental SCR NOx reduction. However, stored NH3 after multiple lean-rich cycles can enable continued NOx reduction by the SCR after lean-rich cycling stops; thus, requirements for active regeneration of the LNT+SCR system can be modified during transient operation.

  8. Do non-targeted effects increase or decrease low dose risk in relation to the linear-non-threshold (LNT) model?

    PubMed

    Little, M P

    2010-05-01

    In this paper we review the evidence for departure from linearity for malignant and non-malignant disease and in the light of this assess likely mechanisms, and in particular the potential role for non-targeted effects. Excess cancer risks observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups exposed at low or moderate doses are generally statistically compatible. For most cancer sites the dose-response in these groups is compatible with linearity over the range observed. The available data on biological mechanisms do not provide general support for the idea of a low dose threshold or hormesis. This large body of evidence does not suggest, indeed is not statistically compatible with, any very large threshold in dose for cancer, or with possible hormetic effects, and there is little evidence of the sorts of non-linearity in response implied by non-DNA-targeted effects. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors and in other groups. In particular, elevated risks of cardiovascular disease, respiratory disease and digestive disease are observed in the A-bomb data. In contrast with cancer, there is much less consistency in the patterns of risk between the various exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other (non-A-bomb) groups. Cardiovascular risks have been seen in many exposed populations, particularly in medically exposed groups, but in contrast with cancer there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. In the absence of a convincing mechanistic explanation of epidemiological evidence that is, at present, less than persuasive, a cause-and-effect interpretation of the reported statistical associations for cardiovascular disease is unreliable but cannot be excluded. Inflammatory processes are the most likely mechanism by which radiation could modify the atherosclerotic disease process. If there is to be modification by low doses of ionizing radiation of cardiovascular disease through this mechanism, a role for non-DNA-targeted effects cannot be excluded.

  9. Do non-targeted effects increase or decrease low dose risk in relation to the linear-non-threshold (LNT) model?☆

    PubMed Central

    Little, M.P.

    2011-01-01

    In this paper we review the evidence for departure from linearity for malignant and non-malignant disease and in the light of this assess likely mechanisms, and in particular the potential role for non-targeted effects. Excess cancer risks observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups exposed at low or moderate doses are generally statistically compatible. For most cancer sites the dose–response in these groups is compatible with linearity over the range observed. The available data on biological mechanisms do not provide general support for the idea of a low dose threshold or hormesis. This large body of evidence does not suggest, indeed is not statistically compatible with, any very large threshold in dose for cancer, or with possible hormetic effects, and there is little evidence of the sorts of non-linearity in response implied by non-DNA-targeted effects. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors and in other groups. In particular, elevated risks of cardiovascular disease, respiratory disease and digestive disease are observed in the A-bomb data. In contrast with cancer, there is much less consistency in the patterns of risk between the various exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other (non-A-bomb) groups. Cardiovascular risks have been seen in many exposed populations, particularly in medically exposed groups, but in contrast with cancer there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. In the absence of a convincing mechanistic explanation of epidemiological evidence that is, at present, less than persuasive, a cause-and-effect interpretation of the reported statistical associations for cardiovascular disease is unreliable but cannot be excluded. Inflammatory processes are the most likely mechanism by which radiation could modify the atherosclerotic disease process. If there is to be modification by low doses of ionizing radiation of cardiovascular disease through this mechanism, a role for non-DNA-targeted effects cannot be excluded. PMID:20105434

  10. The LNT Debate in Radiation Protection: Science vs. Policy

    PubMed Central

    Mossman, Kenneth L.

    2012-01-01

    There is considerable interest in revisiting LNT theory as the basis for the system of radiation protection in the US and worldwide. Arguing the scientific merits of policy options is not likely to be fruitful because the science is not robust enough to support one theory to the exclusion of others. Current science cannot determine the existence of a dose threshold, a key piece to resolving the matter scientifically. The nature of the scientific evidence is such that risk assessment at small effective doses (defined as <100 mSv) is highly uncertain, and several policy alternatives, including threshold and non-linear dose-response functions, are scientifically defensible. This paper argues for an alternative approach by looking at the LNT debate as a policy question and analyzes the problem from a social and economic perspective. In other words, risk assessment and a strictly scientific perspective are insufficiently broad enough to resolve the issue completely. A wider perspective encompassing social and economic impacts in a risk management context is necessary, but moving the debate to the policy and risk management arena necessarily marginalizes the role of scientists. PMID:22740781

  11. Radiation, ecology and the invalid LNT model: the evolutionary imperative.

    PubMed

    Parsons, Peter A

    2006-09-27

    Metabolic and energetic efficiency, and hence fitness of organisms to survive, should be maximal in their habitats. This tenet of evolutionary biology invalidates the linear-no threshold (LNT) model for the risk consequences of environmental agents. Hormesis in response to selection for maximum metabolic and energetic efficiency, or minimum metabolic imbalance, to adapt to a stressed world dominated by oxidative stress should therefore be universal. Radiation hormetic zones extending substantially beyond common background levels, can be explained by metabolic interactions among multiple abiotic stresses. Demographic and experimental data are mainly in accord with this expectation. Therefore, non-linearity becomes the primary model for assessing risks from low-dose ionizing radiation. This is the evolutionary imperative upon which risk assessment for radiation should be based.

  12. Radiation, Ecology and the Invalid LNT Model: The Evolutionary Imperative

    PubMed Central

    Parsons, Peter A.

    2006-01-01

    Metabolic and energetic efficiency, and hence fitness of organisms to survive, should be maximal in their habitats. This tenet of evolutionary biology invalidates the linear-nothreshold (LNT) model for the risk consequences of environmental agents. Hormesis in response to selection for maximum metabolic and energetic efficiency, or minimum metabolic imbalance, to adapt to a stressed world dominated by oxidative stress should therefore be universal. Radiation hormetic zones extending substantially beyond common background levels, can be explained by metabolic interactions among multiple abiotic stresses. Demographic and experimental data are mainly in accord with this expectation. Therefore, non-linearity becomes the primary model for assessing risks from low-dose ionizing radiation. This is the evolutionary imperative upon which risk assessment for radiation should be based. PMID:18648598

  13. Origin of the linearity no threshold (LNT) dose-response concept.

    PubMed

    Calabrese, Edward J

    2013-09-01

    This paper identifies the origin of the linearity at low-dose concept [i.e., linear no threshold (LNT)] for ionizing radiation-induced mutation. After the discovery of X-ray-induced mutations, Olson and Lewis (Nature 121(3052):673-674, 1928) proposed that cosmic/terrestrial radiation-induced mutations provide the principal mechanism for the induction of heritable traits, providing the driving force for evolution. For this concept to be general, a LNT dose relationship was assumed, with genetic damage proportional to the energy absorbed. Subsequent studies suggested a linear dose response for ionizing radiation-induced mutations (Hanson and Heys in Am Nat 63(686):201-213, 1929; Oliver in Science 71:44-46, 1930), supporting the evolutionary hypothesis. Based on an evaluation of spontaneous and ionizing radiation-induced mutation with Drosophila, Muller argued that background radiation had a negligible impact on spontaneous mutation, discrediting the ionizing radiation-based evolutionary hypothesis. Nonetheless, an expanded set of mutation dose-response observations provided a basis for collaboration between theoretical physicists (Max Delbruck and Gunter Zimmer) and the radiation geneticist Nicolai Timoféeff-Ressovsky. They developed interrelated physical science-based genetics perspectives including a biophysical model of the gene, a radiation-induced gene mutation target theory and the single-hit hypothesis of radiation-induced mutation, which, when integrated, provided the theoretical mechanism and mathematical basis for the LNT model. The LNT concept became accepted by radiation geneticists and recommended by national/international advisory committees for risk assessment of ionizing radiation-induced mutational damage/cancer from the mid-1950s to the present. The LNT concept was later generalized to chemical carcinogen risk assessment and used by public health and regulatory agencies worldwide.

  14. Structural Basis for the Inhibition of the Chromatin Repressor BAHD1 by the Bacterial Nucleomodulin LntA

    PubMed Central

    Lebreton, Alice; Job, Viviana; Ragon, Marie; Le Monnier, Alban; Dessen, Andréa; Cossart, Pascale; Bierne, Hélène

    2014-01-01

    ABSTRACT The nucleus has emerged as a key target for nucleomodulins, a family of effectors produced by bacterial pathogens to control host transcription or other nuclear processes. The virulence factor LntA from Listeria monocytogenes stimulates interferon responses during infection by inhibiting BAHD1, a nuclear protein involved in gene silencing by promoting heterochromatin formation. So far, whether the interaction between LntA and BAHD1 is direct and sufficient for inhibiting BAHD1 activity is unknown. Here, we functionally characterized the molecular interface between the two proteins in vitro and in transfected or infected human cells. Based on the known tridimensional structure of LntA, we identified a dilysine motif (K180/K181) in the elbow region of LntA and a central proline-rich region in BAHD1 as crucial for the direct LntA-BAHD1 interaction. To better understand the role played by the dilysine motif in the functionality of LntA, we solved the crystal structure of a K180D/K181D mutant to a 2.2-Å resolution. This mutant highlights a drastic redistribution of surface charges in the vicinity of a groove, which likely plays a role in nucleomodulin target recognition. Mutation of the strategic dilysine motif also abolished the recruitment of LntA to BAHD1-associated nuclear foci and impaired the LntA-mediated stimulation of interferon responses upon infection. Last, the strict conservation of residues K180 and K181 in LntA sequences from 188 L. monocytogenes strains of different serotypes and origins further supports their functional importance. Together, these results provide structural and functional details about the mechanism of inhibition of an epigenetic factor by a bacterial nucleomodulin. PMID:24449750

  15. Perspective on the use of LNT for radiation protection and risk assessment by the U.S. Environmental Protection Agency.

    PubMed

    Puskin, Jerome S

    2009-08-21

    The U.S. Environmental Protection Agency (EPA) bases its risk assessments, regulatory limits, and nonregulatory guidelines for population exposures to low level ionizing radiation on the linear no-threshold (LNT) hypothesis, which assumes that the risk of cancer due to a low dose exposure is proportional to dose, with no threshold. The use of LNT for radiation protection purposes has been repeatedly endorsed by authoritative scientific advisory bodies, including the National Academy of Sciences' BEIR Committees, whose recommendations form a primary basis of EPA's risk assessment methodology. Although recent radiobiological findings indicate novel damage and repair processes at low doses, LNT is supported by data from both epidemiology and radiobiology. Given the current state of the science, the consensus positions of key scientific and governmental bodies, as well as the conservatism and calculational convenience of the LNT assumption, it is unlikely that EPA will modify this approach in the near future.

  16. Health Effects of High Radon Environments in Central Europe: Another Test for the LNT Hypothesis?

    PubMed Central

    Becker, Klaus

    2003-01-01

    Morbus Bechterew, radon treatments are beneficial, with the positive effect lasting until at least 6 months after the normally 3-week treatment by inhalation or bathes. Studies on the mechanism of these effects are progressing. In other cases of extensive use of radon treatment for a wide spectrum of various diseases, for example, in the former Soviet Union, the positive results are not so well established. However, according to a century of radon treatment experience (after millenniums of unknown radon therapy), in particular in Germany and Austria, the positive medical effects for some diseases far exceed any potential detrimental health effects. The total amount of available data in this field is too large to be covered in a brief review. Therefore, less known — in particular recent — work from Central Europe has been analyzed in an attempt to summarize new developments and trends. This includes cost/benefit aspects of radon reduction programs. As a test case for the LNT (linear non-threshold) hypothesis and possible biopositive effects of low radiation exposures, the data support a nonlinear human response to low and medium-level radon exposures. PMID:19330110

  17. The linear nonthreshold (LNT) model as used in radiation protection: an NCRP update.

    PubMed

    Boice, John D

    2017-10-01

    The linear nonthreshold (LNT) model has been used in radiation protection for over 40 years and has been hotly debated. It relies heavily on human epidemiology, with support from radiobiology. The scientific underpinnings include NCRP Report No. 136 ('Evaluation of the Linear-Nonthreshold Dose-Response Model for Ionizing Radiation'), UNSCEAR 2000, ICRP Publication 99 (2004) and the National Academies BEIR VII Report (2006). NCRP Scientific Committee 1-25 is reviewing recent epidemiologic studies focusing on dose-response models, including threshold, and the relevance to radiation protection. Recent studies after the BEIR VII Report are being critically reviewed and include atomic-bomb survivors, Mayak workers, atomic veterans, populations on the Techa River, U.S. radiological technologists, the U.S. Million Person Study, international workers (INWORKS), Chernobyl cleanup workers, children given computerized tomography scans, and tuberculosis-fluoroscopy patients. Methodologic limitations, dose uncertainties and statistical approaches (and modeling assumptions) are being systematically evaluated. The review of studies continues and will be published as an NCRP commentary in 2017. Most studies reviewed to date are consistent with a straight-line dose response but there are a few exceptions. In the past, the scientific consensus process has worked in providing practical and prudent guidance. So pragmatic judgment is anticipated. The evaluations are ongoing and the extensive NCRP review process has just begun, so no decisions or recommendations are in stone. The march of science requires a constant assessment of emerging evidence to provide an optimum, though not necessarily perfect, approach to radiation protection. Alternatives to the LNT model may be forthcoming, e.g. an approach that couples the best epidemiology with biologically-based models of carcinogenesis, focusing on chronic (not acute) exposure circumstances. Currently for the practical purposes of

  18. Development of Optimal Catalyst Designs and Operating Strategies for Lean NOx Reduction in Coupled LNT-SCR Systems

    SciTech Connect

    Harold, Michael; Crocker, Mark; Balakotaiah, Vemuri; Luss, Dan; Choi, Jae-Soon; Dearth, Mark; McCabe, Bob; Theis, Joe

    2013-09-30

    Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO{sub 2}) commonly referred to as NO{sub x}, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NO{sub x} is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NO{sub x} in the presence of excess O{sub 2}. Catalytic abatement measures that are effective for gasoline-fueled engines such as the precious metal containing three-way catalytic converter (TWC) cannot be used to treat O2-laden exhaust containing NO{sub x}. Two catalytic technologies that have emerged as effective for NO{sub x} abatement are NO{sub x} storage and reduction (NSR) and selective catalytic reduction (SCR). NSR is similar to TWC but requires much larger quantities of expensive precious metals and sophisticated periodic switching operation, while SCR requires an on-board source of ammonia which serves as the chemical reductant of the NO{sub x}. The fact that NSR produces ammonia as a byproduct while SCR requires ammonia to work has led to interest in combining the two together to avoid the need for the cumbersome ammonia generation system. In this project a comprehensive study was carried out of the fundamental aspects and application feasibility of combined NSR/SCR. The project team, which included university, industry, and national lab researchers, investigated the kinetics and mechanistic features of the underlying chemistry in the lean NOx trap (LNT) wherein NSR was carried out, with particular focus on identifying the operating conditions such as temperature and catalytic properties which lead to the production of ammonia in the LNT. The performance features of SCR on both model and commercial catalysts focused on the synergy between the LNT and SCR converters in terms of utilizing the upstream-generated ammonia and alternative reductants such as propylene, representing the

  19. The Use of Lexical Neighborhood Test (LNT) in the Assessment of Speech Recognition Performance of Cochlear Implantees with Normal and Malformed Cochlea.

    PubMed

    Kant, Anjali R; Banik, Arun A

    2017-09-01

    The present study aims to use the model-based test Lexical Neighborhood Test (LNT), to assess speech recognition performance in early and late implanted hearing impaired children with normal and malformed cochlea. The LNT was administered to 46 children with congenital (prelingual) bilateral severe-profound sensorineural hearing loss, using Nucleus 24 cochlear implant. The children were grouped into Group 1-(early implantees with normal cochlea-EI); n = 15, 31/2-61/2 years of age; mean age at implantation-3½ years. Group 2-(late implantees with normal cochlea-LI); n = 15, 6-12 years of age; mean age at implantation-5 years. Group 3-(early implantees with malformed cochlea-EIMC); n = 9; 4.9-10.6 years of age; mean age at implantation-3.10 years. Group 4-(late implantees with malformed cochlea-LIMC); n = 7; 7-12.6 years of age; mean age at implantation-6.3 years. The following were the malformations: dysplastic cochlea, common cavity, Mondini's, incomplete partition-1 and 2 (IP-1 and 2), enlarged IAC. The children were instructed to repeat the words on hearing them. Means of the word and phoneme scores were computed. The LNT can also be used to assess speech recognition performance of hearing impaired children with malformed cochlea. When both easy and hard lists of LNT are considered, although, late implantees (with or without normal cochlea), have achieved higher word scores than early implantees, the differences are not statistically significant. Using LNT for assessing speech recognition enables a quantitative as well as descriptive report of phonological processes used by the children.

  20. Standards for environmental, non-threshold, carcinogens: a comparison of the approaches used for radiation and for chemicals.

    PubMed

    Duggan, M J; Lambert, B E

    1998-07-01

    Environmental standards for ionising radiation and for chemical carcinogens have been developed independently of each other. Radiation standards have been derived by deciding upon what is an acceptable risk, and then finding the corresponding dose from the exposure/risk relationship-quantitative risk assessment (QRA). The extent and the quality of the exposure/risk data for radiation, and the authority of the recommendations of the International Commission on Radiological Protection (ICRP), have resulted in universally accepted guidance and standards. This is not the case for chemical, non-threshold carcinogens. Their carcinogenicity ranges from doubtful to well-established, the exposure/response data are generally of poor quality, and there is no authoritative international body analogous to the ICRP. For some of these carcinogens, some organisations have used QRA to derive environmental standards. Others consider the data inadequate for such an approach and have used more pragmatic methods. The problems associated with the various approaches used and the prospects of an integrated approach for both radiation and chemical carcinogens are discussed.

  1. The Genetics Panel of the NAS BEAR I Committee (1956): epistolary evidence suggests self-interest may have prompted an exaggeration of radiation risks that led to the adoption of the LNT cancer risk assessment model.

    PubMed

    Calabrese, Edward J

    2014-09-01

    This paper extends a series of historical papers which demonstrated that the linear-no-threshold (LNT) model for cancer risk assessment was founded on ideological-based scientific deceptions by key radiation genetics leaders. Based on an assessment of recently uncovered personal correspondence, it is shown that some members of the United States (US) National Academy of Sciences (NAS) Biological Effects of Atomic Radiation I (BEAR I) Genetics Panel were motivated by self-interest to exaggerate risks to promote their science and personal/professional agenda. Such activities have profound implications for public policy and may have had a significant impact on the adoption of the LNT model for cancer risk assessment.

  2. Consideration of non-linear, non-threshold and threshold approaches for assessing the carcinogenicity of oral exposure to hexavalent chromium.

    PubMed

    Haney, J

    2015-12-01

    A non-linear approach, consistent with available mode of action (MOA) data, is most scientifically defensible for assessing the carcinogenicity of oral exposure to hexavalent chromium (CrVI). Accordingly, the current paper builds upon previous studies (Haney, 2015a, 2015b) to first develop a non-linear, non-threshold approach as well as a non-linear threshold approach for assessing the oral carcinogenicity of CrVI, and then utilizes available MOA analyses and information for selection of the most scientifically-supported approach. More specifically, a non-linear, non-threshold dose-response function was developed that adequately describes the non-linearity predicted for potential human excess risk versus oral dose due to the sub-linear relationship between oral dose and internal dose (added mg Cr/kg target tissue) across environmentally-relevant doses of regulatory interest. Additionally, benchmark dose modeling was used to derive a reference dose (RfD of 0.003 mg/kg-day) with cytotoxicity-induced regenerative hyperplasia as a key precursor event to carcinogenesis in the mouse small intestine. This RfD value shows remarkable agreement with that published previously (0.006 mg/kg-day) based on a more scientifically-sophisticated, physiologically-based pharmacokinetic modeling approach (Thompson et al., 2013b). The RfD approach is the most scientifically-defensible approach based on the weight-of-evidence of available MOA information and analyses conducted for the most scientifically-supported MOA.

  3. Cancer risk assessment foundation unraveling: new historical evidence reveals that the US National Academy of Sciences (US NAS), Biological Effects of Atomic Radiation (BEAR) Committee Genetics Panel falsified the research record to promote acceptance of the LNT.

    PubMed

    Calabrese, Edward J

    2015-04-01

    The NAS Genetics Panel (1956) recommended a switch from a threshold to a linear dose response for radiation risk assessment. To support this recommendation, geneticists on the panel provided individual estimates of the number of children in subsequent generations (one to ten) that would be adversely affected due to transgenerational reproductive cell mutations. It was hoped that there would be close agreement among the individual risk estimates. However, extremely large ranges of variability and uncertainty characterized the wildly divergent expert estimates. The panel members believed that sharing these estimates with the scientific community and general public would strongly undercut their linearity recommendation, as it would have only highlighted their own substantial uncertainties. Essentially, their technical report in the journal Science omitted and misrepresented key adverse reproductive findings in an effort to ensure support for their linearity recommendation. These omissions and misrepresentations not only belie the notion of an impartial and independent appraisal by the NAS Panel, but also amount to falsification and fabrication of the research record at the highest possible level, leading ultimately to the adoption of LNT by governments worldwide. Based on previously unexamined correspondence among panel members and Genetics Panel meeting transcripts, this paper provides the first documentation of these historical developments.

  4. A novel dose-based positioning method for CT image-guided proton therapy

    PubMed Central

    Cheung, Joey P.; Park, Peter C.; Court, Laurence E.; Ronald Zhu, X.; Kudchadker, Rajat J.; Frank, Steven J.; Dong, Lei

    2013-01-01

    Purpose: Proton dose distributions can potentially be altered by anatomical changes in the beam path despite perfect target alignment using traditional image guidance methods. In this simulation study, the authors explored the use of dosimetric factors instead of only anatomy to set up patients for proton therapy using in-room volumetric computed tomographic (CT) images. Methods: To simulate patient anatomy in a free-breathing treatment condition, weekly time-averaged four-dimensional CT data near the end of treatment for 15 lung cancer patients were used in this study for a dose-based isocenter shift method to correct dosimetric deviations without replanning. The isocenter shift was obtained using the traditional anatomy-based image guidance method as the starting position. Subsequent isocenter shifts were established based on dosimetric criteria using a fast dose approximation method. For each isocenter shift, doses were calculated every 2 mm up to ±8 mm in each direction. The optimal dose alignment was obtained by imposing a target coverage constraint that at least 99% of the target would receive at least 95% of the prescribed dose and by minimizing the mean dose to the ipsilateral lung. Results: The authors found that 7 of 15 plans did not meet the target coverage constraint when using only the anatomy-based alignment. After the authors applied dose-based alignment, all met the target coverage constraint. For all but one case in which the target dose was met using both anatomy-based and dose-based alignment, the latter method was able to improve normal tissue sparing. Conclusions: The authors demonstrated that a dose-based adjustment to the isocenter can improve target coverage and/or reduce dose to nearby normal tissue. PMID:23635262

  5. Daptomycin Dosing Based on Ideal Body Weight versus Actual Body Weight: Comparison of Clinical Outcomes

    PubMed Central

    Rose, Warren E.; Fox, Barry C.; Andes, David R.; Buhr, Kevin A.; Fish, Jeffrey T.

    2014-01-01

    Daptomycin use at our institution changed to ideal body weight dosing based on a published analysis of pharmacokinetic-pharmacodynamic efficacy target attainment, bacterial ecology, and a desire to reduce drug toxicity. The current study compared outcomes between actual body weight and ideal body weight dosing of daptomycin before and after this intervention. In the evaluable group, 69 patients received doses based on actual body weight and 48 patients received doses based on ideal body weight. Patients were treated for documented Enterococcus species, Staphylococcus aureus, or coagulase-negative Staphylococcus infections, including bloodstream, intraabdominal, skin and soft tissue, urinary, and bone. There was no statistically significant difference in clinical success between the groups (88.9% for actual body weight compared to 89.1% for ideal body weight, P = 0.97). After we adjusted for gender, age, body mass index, concomitant 3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitors, infection type, and organism type, clinical success rates remained similar between groups (adjusted odds ratio of 0.68 in favor of actual body weight, 95% confidence interval [CI] of 0.13 to 3.55). Microbiological outcomes, length of stay, mortality, and adverse effects were also similar between groups. Further studies are warranted to confirm that ideal body weight dosing provides similar outcomes to actual body weight dosing for all patients and types of infections and organisms. PMID:24145531

  6. Postmarketing review of intravenous acetaminophen dosing based on Food and Drug Administration prescribing guidelines.

    PubMed

    dela Cruz Ubaldo, Catherine; Hall, Natalie Semaan; Le, Brenden

    2014-12-01

    To evaluate the appropriateness of intravenous acetaminophen dosing-prescribed dose, frequency, duration, and indication-based on United States Food and Drug Administration (FDA)-approved prescribing guidelines and to evaluate the adverse effect profile of intravenous acetaminophen. Retrospective chart review. United States Navy medical center. Three hundred patients who received intravenous acetaminophen from August 1, 2011, to August 1, 2012. The indications, dose, frequency, and duration of intravenous acetaminophen were recorded for each patient. Adverse effects of intravenous acetaminophen were analyzed by thoroughly reviewing any adverse effects documented, including nausea, vomiting, headache, or any symptom specifically attributed to the drug. Baseline liver function tests, including aspartate aminotransferase and alanine aminotransferase levels, and elevations 3 times the upper limit of normal during intravenous acetaminophen therapy were recorded. The average patient weight was 78±21 kg, with 12 patients (4%) weighing less than 50 kg and 288 (96%) patients weighing 50 kg or greater. Two hundred forty-one patients (80%) were appropriately dosed, whereas 59 (20%) patients were not appropriately dosed based on the FDA-approved dosing. No patients exceeded the FDA-approved maximum daily dosing recommendations for intravenous acetaminophen (4 g). Sixty-five patients (22%) received intravenous acetaminophen for longer than 24 hours. Intravenous acetaminophen was well tolerated, without any reported adverse effects, including the commonly reported adverse effects of nausea, vomiting, headache, and insomnia. Ten patients (3%) had a documented history of liver disease and did not experience any adverse effects or increases in liver function tests after the administration of intravenous acetaminophen. Intravenous acetaminophen appeared to be a safe and effective analgesic and antipyretic agent. Dosing for patients weighing less than 50 kg needs to be appropriately

  7. Evaluation of heparin dosing based on adjusted body weight in obese patients.

    PubMed

    Fan, Jingyang; John, Billee; Tesdal, Emily

    2016-10-01

    Results of a study to determine whether heparin dosing based on adjusted body weight (BWAdj) instead of actual body weight (ABW) can lead to faster achievement of therapeutic activated partial thromboplastin time (aPTT) values in obese patients are presented. A single-center retrospective cohort study was conducted to assess aPTT outcomes before and after implementation of a revised heparin protocol specifying BWAdj-based dosing for obese patients. The primary outcome was the percentage of first aPTT values within the target range after heparin initiation. Secondary outcomes included the median time to the first on-target aPTT and the rate of clinically significant bleeding. After protocol implementation, there was no significant difference between obese and nonobese patients in the primary outcome (17% and 21%, respectively, had first aPTT values in the target range) or in the median time to achieve the first on-target aPTT value. Among obese patients, on-target aPTT values were achieved significantly faster with BWAdj-versus ABW-based dosing (14 hours versus 24 hours, p = 0.002). Prior to implementation of BWAdj-based heparin dosing, obese patients had a higher rate of clinically significant bleeding than nonobese patients (11% versus 1%, p = 0.01); postimplementation bleeding rates did not differ significantly. The percentages of first aPTT values in the targeted range did not differ significantly in obese and nonobese patients before and after protocol implementation. The use of BWAdj for dose calculation in obese patients was associated with faster achievement of an aPTT value in the target range. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

  8. Drug dosing based on weight and body surface area: mathematical assumptions and limitations in obese adults.

    PubMed

    Pai, Manjunath P

    2012-09-01

    The average weight of adults in the United States has increased by 25 pounds (11 kg) over the past 50 years, with a marginal change in height. Drugs are generally dosed according to one of three approaches: fixed dosing, weight-based dosing, or body surface area-based dosing. Dosing based on body weight or body surface area assumes that drug pharmacokinetic parameters increase in proportion with increasing body size. In contrast, dosing drugs on a fixed basis assumes that drug pharmacokinetic parameters do not increase with body size. Unfortunately, early stages of clinical drug development tend to include adults within a narrow range of body size. This study population does not reflect the current U.S. population distribution and does not permit evaluation of the correct relationship between body size and drug clearance. As a consequence, a weight-based or body surface area-based dosing regimen defined during drug development may not be applicable to U.S. patient populations. These dosing strategies are more likely to result in drug overexposure (weight-based approach) or underexposure (body surface area-based approach) among obese patients. Alternate weight descriptors such as ideal body weight, adjusted body weight, fat-free weight, and lean body weight are used to prevent drug overexposure with weight-based dosing, but their benefits and limitations must be understood. Reappraisal of the drug dosing paradigm is needed in this era of rising obesity; however, until drug-specific reviews can be performed, clinical studies must include patients at the extremes of the weight continuum to ensure applicable dose extrapolation for body size. © 2012 Pharmacotherapy Publications, Inc. All rights reserved.

  9. A dose-based modeling approach for accumulation and toxicity of arsenic in tilapia Oreochromis mossambicus.

    PubMed

    Tsai, Jeng-Wei; Liao, Chung-Min

    2006-02-01

    comparable to the observed data when the tilapia were exposed to 4 microg/mL(-1). Our results show that a dose-based toxicokinetic and toxicodynamic modeling approach successfully links metal exposure to bioavailability, bioaccumulation, and toxicity, under variable exposure scenarios.

  10. Intra-VTA anandamide infusion produces dose-based biphasic effects on male rat sexual behavior expression.

    PubMed

    Canseco-Alba, Ana; Rodríguez-Manzo, Gabriela

    Sexual behavior is a natural reward and the mesolimbic (MSL) system is involved in the processing of its motivational component and reinforcing properties. Endocannabinoids control rewarding behaviors through the modulation of MSL system's activity. The endocannabinoid anandamide (AEA), systemically administered, produces dose-based, biphasic effects on male rat copulation, facilitating its expression at low doses in both, sexually experienced and sexually exhausted male rats. We hypothesized that AEA's sexual facilitative effects might be exerted at the MSL circuit. Therefore, in this work different AEA doses were bilaterally infused into the VTA of sexually experienced or sexually exhausted animals and their copulatory behavior recorded. Results showed that the lowest AEA dose tested lacked an effect, intermediate doses facilitated specific sexual parameters, and the highest dose inhibited copulation of sexually experienced males. In sexually exhausted animals low AEA doses reversed the sexual inhibition that characterizes sexual satiety, but this effect was lost at higher doses. Together, these data show that the VTA is a target for AEA's biphasic sexual effects suggesting a role of the MLS system in the actions of endocannabinoids on male rat sexual behavior. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. A bounding estimate of neutron dose based on measured photon dose around single pass reactors at the Hanford site.

    PubMed

    Taulbee, Timothy D; Glover, Samuel E; Macievic, Gregory V; Hunacek, Mickey; Smith, Cheryl; DeBord, Gary W; Morris, Donald; Fix, Jack

    2010-07-01

    Neutron and photon radiation survey records have been used to evaluate and develop a neutron to photon (NP) ratio to reconstruct neutron doses to workers around Hanford's single pass reactors that operated from 1945 to 1972. A total of 5,773 paired neutron and photon measurements extracted from 57 boxes of survey records were used in the development of the NP ratio. The development of the NP ratio enables the use of the recorded dose from an individual's photon dosimeter badge to be used to estimate the unmonitored neutron dose. The Pearson rank correlation between the neutron and photon measurements was 0.71. The NP ratio best fit a lognormal distribution with a geometric mean (GM) of 0.8, a geometric standard deviation (GSD) of 2.95, and the upper 95 th % of this distribution was 4.75. An estimate of the neutron dose based on this NP ratio is considered bounding due to evidence that up to 70% of the total photon exposure received by workers around the single pass reactors occurs during shutdown maintenance and refueling activities when there is no significant neutron exposure. Thus when this NP ratio is applied to the total measured photon dose from an individual film badge dosimeter, the resulting neutron dose is considered bounded.

  12. SU-E-J-181: Effect of Prostate Motion On Combined Brachytherapy and External Beam Dose Based On Daily Motion of the Prostate

    SciTech Connect

    Narayana, V; McLaughlin, P; Ealbaj, J

    2015-06-15

    Purpose: In this study, the adequacy of target expansions on the combined external beam and implant dose was examined based on the measured daily motion of the prostate. Methods: Thirty patients received an I–125 prostate implant prescribed to dose of 90Gy. This was followed by external beam to deliver a dose of 90Gyeq (external beam equivalent) to the prostate over 25 to 30 fractions. An ideal IMRT plan was developed by optimizing the external beam dose based on the delivered implant dose. The implant dose was converted to an equivalent external beam dose using the linear quadratic model. Patients were set up on the treatment table by daily orthogonal imaging and aligning the marker seeds in the prostate. Orthogonal images were obtained at the end of treatment to assess prostate intrafraction motion. Based on the observed motion of the markers between the initial and final images, 5 individual plans showing the actual dose delivered to the patient were calculated. A final true dose distribution was established based on summing the implant dose and the 5 external beam plans. Dose to the prostate, seminal vesicles, lymphnodes and normal tissues, rectal wall, urethra and lower sphincter were calculated and compared to ideal. On 18 patients who were sexually active, dose to the corpus cavernosum and internal pudendal artery was also calculated. Results: The average prostate motion in 3 orthogonal directions was less than 1 mm with a standard deviation of less than +2 mm. Dose and volume parameters showed that there was no decrease in dose to the targets and a marginal decrease in dose to in normal tissues. Conclusion: Dose delivered by seed implant moves with the prostate, decreasing the impact of intrafractions dose movement on actual dose delivered. Combined brachytherapy and external beam dose delivered to the prostate was not sensitive to prostate motion.

  13. Dosimetric advantages of generalised equivalent uniform dose-based optimisation on dose-volume objectives in intensity-modulated radiotherapy planning for bilateral breast cancer.

    PubMed

    Lee, T-F; Ting, H-M; Chao, P-J; Wang, H-Y; Shieh, C-S; Horng, M-F; Wu, J-M; Yeh, S-A; Cho, M-Y; Huang, E-Y; Huang, Y-J; Chen, H-C; Fang, F-M

    2012-11-01

    We compared and evaluated the differences between two models for treating bilateral breast cancer (BBC): (i) dose-volume-based intensity-modulated radiation treatment (DV plan), and (ii) dose-volume-based intensity-modulated radiotherapy with generalised equivalent uniform dose-based optimisation (DV-gEUD plan). The quality and performance of the DV plan and DV-gEUD plan using the Pinnacle(3) system (Philips, Fitchburg, WI) were evaluated and compared in 10 patients with stage T2-T4 BBC. The plans were delivered on a Varian 21EX linear accelerator (Varian Medical Systems, Milpitas, CA) equipped with a Millennium 120 leaf multileaf collimator (Varian Medical Systems). The parameters analysed included the conformity index, homogeneity index, tumour control probability of the planning target volume (PTV), the volumes V(20 Gy) and V(30 Gy) of the organs at risk (OAR, including the heart and lungs), mean dose and the normal tissue complication probability. Both plans met the requirements for the coverage of PTV with similar conformity and homogeneity indices. However, the DV-gEUD plan had the advantage of dose sparing for OAR: the mean doses of the heart and lungs, lung V(20) (Gy), and heart V(30) (Gy) in the DV-gEUD plan were lower than those in the DV plan (p<0.05). A better result can be obtained by starting with a DV-generated plan and then improving it by adding gEUD-based improvements to reduce the number of iterations and to improve the optimum dose distribution. Advances to knowledge The DV-gEUD plan provided superior dosimetric results for treating BBC in terms of PTV coverage and OAR sparing than the DV plan, without sacrificing the homogeneity of dose distribution in the PTV.

  14. Anomalous dielectric nonlinearity and dielectric relaxation in xBST-(1- x) (LMT-LNT) ceramics

    NASA Astrophysics Data System (ADS)

    Liu, Cheng; Liu, Peng

    2011-11-01

    xwt%Ba0.6Sr0.4TiO3-(1- x)wt%[0.4La (Mg0.5Ti0.5)O3-0.6(La0.5Na0.5)TiO3] ( x=0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 0.95) ceramics were prepared via a traditional solid-state reaction route. Interesting anomalous dielectric nonlinearity (ADN)—permittivity increased with dc bias electric field ( E-field), and low-temperature dielectric relaxation (LTDR) behaviors—were observed within a x range of 0.30˜0.70 for the first time. Based on our experimental facts, it was suggested that the LTDR was originated from a charge-associated process between electron-oxygen vacancy pairs during a thermal stimulation, while the ADN was related with a metastable state of polarized nano-regions (PNRs).

  15. THE HIGH BACKGROUND RADIATION AREA IN RAMSAR IRAN: GEOLOGY, NORM, BIOLOGY, LNT, AND POSSIBLE REGULATORY FUN

    SciTech Connect

    Karam, P. A.

    2002-02-25

    The city of Ramsar Iran hosts some of the highest natural radiation levels on earth, and over 2000 people are exposed to radiation doses ranging from 1 to 26 rem per year. Curiously, inhabitants of this region seem to have no greater incidence of cancer than those in neighboring areas of normal background radiation levels, and preliminary studies suggest their blood cells experience fewer induced chromosomal abnormalities when exposed to 150 rem ''challenge'' doses of radiation than do the blood cells of their neighbors. This paper will briefly describe the unique geology that gives Ramsar its extraordinarily high background radiation levels. It will then summarize the studies performed to date and will conclude by suggesting ways to incorporate these findings (if they are borne out by further testing) into future radiation protection standards.

  16. Efficacy and safety of weight-based insulin glargine dose titration regimen compared with glucose level- and current dose-based regimens in hospitalized patients with type 2 diabetes: a randomized, controlled study.

    PubMed

    Li, Xiaowei; Du, Tao; Li, Wangen; Zhang, Tong; Liu, Haiyan; Xiong, Yifeng

    2014-09-01

    Insulin glargine is widely used as basal insulin. However, published dose titration regimens for insulin glargine are complex. This study aimed to compare the efficacy and safety profile of a user-friendly, weight-based insulin glargine dose titration regimen with 2 published regimens. A total of 160 hospitalized patients with hyperglycemia in 3 medical centers were screened. Our inclusion criteria included age 18 to 80 years and being conscious. Exclusion criteria included pregnancy or breast-feeding and hepatic or renal dysfunction. A total of 149 patients were randomly assigned to receive weight-based, glucose level-based, or dose-based insulin glargine dose titration regimen between January 2011 and February 2013. The initial dose of insulin glargine was 0.2 U/kg. In the weight-based regimen (n = 49), the dose was titrated by increments of 0.1 U/kg daily. In the glucose level-based regimen (n = 51), the dose was titrated by 2, 4, 6, or 8 U daily when fasting blood glucose (FBG) was, respectively, between 7.0 and 7.9, 8.0 and 8.9, 9.0 and 9.9, or ≥10 mmol/L. In the current dose-based regimen (n = 49), titration was by daily increments of 20% of the current dose. The target FBG in all groups was ≤7.0 mmol/L. The incidence of hypoglycemia was recorded. One-way ANOVA and χ(2) test were used to compare data between the 3 groups. All but 1 patient who required additional oral antidiabetic medication completed the study. The mean (SD) time to achieve target FBG was 3.2 (1.2) days with the weight-based regimen and 3.7 (1.5) days with the glucose level-based regimen (P = 0.266). These times were both shorter than that achieved with the current dose-based regimen (4.8 [2.8] days; P = 0.0001 and P = 0.005, respectively). The daily doses of insulin glargine at the study end point were 0.43 (0.13) U/kg with the weight-based regimen, 0.50 (0.20) U/kg with the glucose level-based regimen, and 0.47 (0.23) U/kg with the current dose-based regimen (P = 0.184). The incidence

  17. Scientific foundation of regulating ionizing radiation: application of metrics for evaluation of regulatory science information.

    PubMed

    Moghissi, A Alan; Gerraa, Vikrham Kumar; McBride, Dennis K; Swetnam, Michael

    2014-11-01

    This paper starts by describing the historical evolution of assessment of biologic effects of ionizing radiation leading to the linear non-threshold (LNT) system currently used to regulate exposure to ionizing radiation. The paper describes briefly the concept of Best Available Science (BAS) and Metrics for Evaluation of Scientific Claims (MESC) derived for BAS. It identifies three phases of regulatory science consisting of the initial phase, when the regulators had to develop regulations without having the needed scientific information; the exploratory phase, when relevant tools were developed; and the standard operating phase, when the tools were applied to regulations. Subsequently, an attempt is made to apply the BAS/MESC system to various stages of LNT. This paper then compares the exposure limits imposed by regulatory agencies and also compares them with naturally occurring radiation at several cities. Controversies about LNT are addressed, including judgments of the U.S. National Academies and their French counterpart. The paper concludes that, based on the BAS/MESC system, there is no disagreement between the two academies on the scientific foundation of LNT; instead, the disagreement is based on their judgment or speculation.

  18. Logic and ethics in radiation protection.

    PubMed

    Lindell, B

    2001-12-01

    The International Commission on Radiological Protection (ICRP) continues to accept the assumption of a linear non-threshold dose-response relationship (LNT) as the most likely one. In that case, basic logic as well as widely accepted ethics require that the full collective dose be used for detriment assessments and in procedures for optimisation of radiation protection. This means that even the smallest doses must be taken into account in the assessment of the global collective dose if they contribute significantly together. However, in calculating collective doses over time, some reasonable restriction of the integration period has to be employed, mainly because of the uncertainties involved in the assessment of future detriment. There are also uncertainties in the LNT assumption, but the precautionary principle would not permit that this is taken as an excuse for neglecting small doses.

  19. Systems Cancer Biology and the Controlling Mechanisms for the J-Shaped Cancer Dose Response: Towards Relaxing the LNT Hypothesis.

    PubMed

    Lou, In Chio; Zhao, Yuchao; Wu, Yingjie; Ricci, Paolo F

    2012-01-01

    The hormesis phenomena or J-shaped dose response have been accepted as a common phenomenon regardless of the involved biological model, endpoint measured and chemical class/physical stressor. This paper first introduced a mathematical dose response model based on systems biology approach. It links molecular-level cell cycle checkpoint control information to clonal growth cancer model to predict the possible shapes of the dose response curves of Ionizing Radiation (IR) induced tumor transformation frequency. J-shaped dose response curves have been captured with consideration of cell cycle checkpoint control mechanisms. The simulation results indicate the shape of the dose response curve relates to the behavior of the saddle-node points of the model in the bifurcation diagram. A simplified version of the model in previous work of the authors was used mathematically to analyze behaviors relating to the saddle-node points for the J-shaped dose response curve. It indicates that low-linear energy transfer (LET) is more likely to have a J-shaped dose response curve. This result emphasizes the significance of systems biology approach, which encourages collaboration of multidiscipline of biologists, toxicologists and mathematicians, to illustrate complex cancer-related events, and confirm the biphasic dose-response at low doses.

  20. LNTgate: How scientific misconduct by the U.S. NAS led to governments adopting LNT for cancer risk assessment.

    PubMed

    Calabrese, Edward J

    2016-07-01

    This paper provides a detailed rebuttal to the letter of Beyea (2016) which offered a series of alternative interpretations to those offered in my article in Environmental Research (Calabrese, 2015a) concerning the role of the U.S. National Academy of Sciences (NAS) Biological Effects of Atomic Radiation (BEAR) I Committee Genetics Panel in the adoption of the linear dose response model for cancer risk assessment. Significant newly uncovered evidence is presented which supports and extends the findings of Calabrese (2015a), reaffirming the conclusion that the Genetics Panel should be evaluated for scientific misconduct for deliberate misrepresentation of the research record in order to enhance an ideological agenda. This critique documents numerous factual errors along with extensive and deliberate filtering of information in the Beyea letter (2016) that leads to consistently incorrect conclusions and an invalid general perspective.

  1. Radiation Hormesis: Historical Perspective and Implications for Low-Dose Cancer Risk Assessment

    PubMed Central

    Vaiserman, Alexander M.

    2010-01-01

    Current guidelines for limiting exposure of humans to ionizing radiation are based on the linear-no-threshold (LNT) hypothesis for radiation carcinogenesis under which cancer risk increases linearly as the radiation dose increases. With the LNT model even a very small dose could cause cancer and the model is used in establishing guidelines for limiting radiation exposure of humans. A slope change at low doses and dose rates is implemented using an empirical dose and dose rate effectiveness factor (DDREF). This imposes usually unacknowledged nonlinearity but not a threshold in the dose-response curve for cancer induction. In contrast, with the hormetic model, low doses of radiation reduce the cancer incidence while it is elevated after high doses. Based on a review of epidemiological and other data for exposure to low radiation doses and dose rates, it was found that the LNT model fails badly. Cancer risk after ordinarily encountered radiation exposure (medical X-rays, natural background radiation, etc.) is much lower than projections based on the LNT model and is often less than the risk for spontaneous cancer (a hormetic response). Understanding the mechanistic basis for hormetic responses will provide new insights about both risks and benefits from low-dose radiation exposure. PMID:20585444

  2. Comparison of radon doses based on different radon monitoring approaches.

    PubMed

    Vaupotič, Janja; Smrekar, Nataša; Žunić, Zora S

    2017-04-01

    In 43 places (23 schools, 3 kindergartens, 16 offices and one dwelling), indoor radon has been monitored as an intercomparison experiment, using α-scintillation cells (SC - Jožef Stefan Institute, Slovenia), various kinds of solid state nuclear track detectors (KfK - Karlsruhe Institute of Technology, Germany; UFO - National Institute of Radiological Sciences, Chiba, Japan; RET - University College Dublin, Ireland) and active electronic devices (EQF, Sarad, Germany). At the same place, the radon levels and, consequently, the effective doses obtained with different radon devices differed substantially (by a factor of 2 or more), and no regularity was observed as regards which detector would show a higher or lower dose.

  3. Simulation of computed tomography dose based on voxel phantom

    NASA Astrophysics Data System (ADS)

    Liu, Chunyu; Lv, Xiangbo; Li, Zhaojun

    2017-01-01

    Computed Tomography (CT) is one of the preferred and the most valuable imaging tool used in diagnostic radiology, which provides a high-quality cross-sectional image of the body. It still causes higher doses of radiation to patients comparing to the other radiological procedures. The Monte-Carlo method is appropriate for estimation of the radiation dose during the CT examinations. The simulation of the Computed Tomography Dose Index (CTDI) phantom was developed in this paper. Under a similar conditions used in physical measurements, dose profiles were calculated and compared against the measured values that were reported. The results demonstrate a good agreement between the calculated and the measured doses. From different CT exam simulations using the voxel phantom, the highest absorbed dose was recorded for the lung, the brain, the bone surface. A comparison between the different scan type shows that the effective dose for a chest scan is the highest one, whereas the effective dose values during abdomen and pelvis scan are very close, respectively. The lowest effective dose resulted from the head scan. Although, the dose in CT is related to various parameters, such as the tube current, exposure time, beam energy, slice thickness and patient size, this study demonstrates that the MC simulation is a useful tool to accurately estimate the dose delivered to any specific organs for patients undergoing the CT exams and can be also a valuable technique for the design and the optimization of the CT x-ray source.

  4. Dosimetry in Mammography: Average Glandular Dose Based on Homogeneous Phantom

    NASA Astrophysics Data System (ADS)

    Benevides, Luis A.; Hintenlang, David E.

    2011-05-01

    The objective of this study was to demonstrate that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 and 46 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

  5. Dosimetry in Mammography: Average Glandular Dose Based on Homogeneous Phantom

    SciTech Connect

    Benevides, Luis A.; Hintenlang, David E.

    2011-05-05

    The objective of this study was to demonstrate that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 and 46 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

  6. Cancer risk assessment: Optimizing human health through linear dose-response models.

    PubMed

    Calabrese, Edward J; Shamoun, Dima Yazji; Hanekamp, Jaap C

    2015-07-01

    This paper proposes that generic cancer risk assessments be based on the integration of the Linear Non-Threshold (LNT) and hormetic dose-responses since optimal hormetic beneficial responses are estimated to occur at the dose associated with a 10(-4) risk level based on the use of a LNT model as applied to animal cancer studies. The adoption of the 10(-4) risk estimate provides a theoretical and practical integration of two competing risk assessment models whose predictions cannot be validated in human population studies or with standard chronic animal bioassay data. This model-integration reveals both substantial protection of the population from cancer effects (i.e. functional utility of the LNT model) while offering the possibility of significant reductions in cancer incidence should the hormetic dose-response model predictions be correct. The dose yielding the 10(-4) cancer risk therefore yields the optimized toxicologically based "regulatory sweet spot". Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. A Mathematical Model for Estimating Biological Damage Caused by Radiation

    NASA Astrophysics Data System (ADS)

    Manabe, Yuichiro; Ichikawa, Kento; Bando, Masako

    2012-10-01

    We propose a mathematical model for estimating biological damage caused by low-dose irradiation. We understand that the linear non threshold (LNT) hypothesis is realized only in the case of no recovery effects. In order to treat the realistic living objects, our model takes into account various types of recovery as well as proliferation mechanism, which may change the resultant damage, especially for the case of lower dose rate irradiation. It turns out that the lower the radiation dose rate, the safer the irradiated system of living object (which is called symbolically ``tissue'' hereafter) can have chances to survive, which can reproduce the so-called dose and dose-rate effectiveness factor (DDREF).

  8. Setting standards for radiation protection: A time for change

    SciTech Connect

    Patterson, H.W.; Hickman, D.P.

    1996-01-01

    In 1950, the International Commission on Radiation Protection (ICRP) recommended that ``certain radiation effects are irreversible and cumulative.`` Furthermore, the ICRP ``strongly recommended that every effort be made to reduce exposures to all types of ionizing radiations to the lowest possible level.`` Then in 1954, the ICRP published its assumption that human response to ionizing radiation was linear with dose, together with the recommendation that exposures be kept as low as practicable. These concepts are still the foundation of radiation protection policy today, even though, as Evans has stated, ``The linear non-threshold (LNT) model was adopted specifically on a basis of mathematical simplicity, not from radio-biological data.... Groups responsible for setting standards for radiation protection should be abreast of new developments and new data as they are published; however, this does not seem to be the case. For example, there have been many reports in scientific, peer-reviewed, and other publications during the last three decades that have shown the LNT model and the policy of As Low As Reasonably Achievable (ALARA) to be invalid. However, none of these reports has been refuted or even discussed by standard-setting groups. We believe this mandates a change in the standard-setting process.

  9. Modeling Dose-response at Low Dose: A Systems Biology Approach for Ionization Radiation.

    PubMed

    Zhao, Yuchao; Ricci, Paolo F

    2010-03-18

    For ionization radiation (IR) induced cancer, a linear non-threshold (LNT) model at very low doses is the default used by a number of national and international organizations and in regulatory law. This default denies any positive benefit from any level of exposure. However, experimental observations and theoretical biology have found that both linear and J-shaped IR dose-response curves can exist at those very low doses. We develop low dose J-shaped dose-response, based on systems biology, and thus justify its use regarding exposure to IR. This approach incorporates detailed, molecular and cellular descriptions of biological/toxicological mechanisms to develop a dose-response model through a set of nonlinear, differential equations describing the signaling pathways and biochemical mechanisms of cell cycle checkpoint, apoptosis, and tumor incidence due to IR. This approach yields a J-shaped dose response curve while showing where LNT behaviors are likely to occur. The results confirm the hypothesis of the J-shaped dose response curve: the main reason is that, at low-doses of IR, cells stimulate protective systems through a longer cell arrest time per unit of IR dose. We suggest that the policy implications of this approach are an increasingly correct way to deal with precautionary measures in public health.

  10. Regulatory-Science: Biphasic Cancer Models or the LNT—Not Just a Matter of Biology!

    PubMed Central

    Ricci, Paolo F.; Sammis, Ian R.

    2012-01-01

    There is no doubt that prudence and risk aversion must guide public decisions when the associated adverse outcomes are either serious or irreversible. With any carcinogen, the levels of risk and needed protection before and after an event occurs, are determined by dose-response models. Regulatory law should not crowd out the actual beneficial effects from low dose exposures—when demonstrable—that are inevitably lost when it adopts the linear non-threshold (LNT) as its causal model. Because regulating exposures requires planning and developing protective measures for future acute and chronic exposures, public management decisions should be based on minimizing costs and harmful exposures. We address the direct and indirect effects of causation when the danger consists of exposure to very low levels of carcinogens and toxicants. The societal consequences of a policy can be deleterious when that policy is based on a risk assumed by the LNT, in cases where low exposures are actually beneficial. Our work develops the science and the law of causal risk modeling: both are interwoven. We suggest how their relevant characteristics differ, but do not attempt to keep them separated; as we demonstrate, this union, however unsatisfactory, cannot be severed. PMID:22740778

  11. Review of Chinese Environmental Risk Assessment Regulations and Case Studies

    PubMed Central

    Meng, Xiaojie; Zhang, Yan; Zhao, Yuchao; Lou, In Chio; Gao, Jixi

    2012-01-01

    Environmental risk assessment is an essential step in the development of solutions for pollution problems and new environmental regulations. An assessment system for environmental risks has been developed in China in recent decades. However, many of the Chinese technical guidelines, standards, and regulations were directly adapted from those of developed countries, and were not based on the Chinese environmental and socioeconomic context. Although existing environmental regulations for pollutants are usually obtained by extrapolations from high-dose toxicological data to low-dose scenarios using linear-non-threshold (LNT) models, toxicologists have argued that J-shaped or inverse J-shaped curves may dominate the dose–response relationships for environmental pollutants at low doses because low exposures stimulate biological protective mechanisms that are ineffective at higher doses. The costs of regulations based on LNT and J-shaped models could therefore be dramatically different. Since economic factors strongly affect the decision-making process, particularly for developing countries, it is time to strengthen basic research to provide more scientific support for Chinese environmental regulations. In this paper, we summarize current Chinese environmental policies and standards and the application of environmental risk assessment in China, and recommend a more scientific approach to the development of Chinese regulations. PMID:22740787

  12. Strategy of the scientific committee on occupational exposure limits (SCOEL) in the derivation of occupational exposure limits for carcinogens and mutagens.

    PubMed

    Bolt, Hermann M; Huici-Montagud, Alicia

    2008-01-01

    Setting standards, such as occupational exposure limits (OELs) for carcinogenic substances must consider modes of action. At the European Union level, the scientific committee on occupational exposure limits (SCOEL) has discussed a number of chemical carcinogens and has issued recommendations. For some carcinogens, health-based OELs were recommended, while quantitative assessments of carcinogenic risks were performed for others. For purposes of setting limits this led to the consideration of the following groups of carcinogens. (A) Non-threshold genotoxic carcinogens; for low-dose assessment of risk, the linear non-threshold (LNT) model appears appropriate. For these chemicals, regulations (risk management) may be based on the ALARA principle ("as low as reasonably achievable"), technical feasibility, and other socio-political considerations. (B) Genotoxic carcinogens, for which the existence of a threshold cannot be sufficiently supported at present. In these cases, the LNT model may be used as a default assumption, based on the scientific uncertainty. (C) Genotoxic carcinogens with a practical threshold, as supported by studies on mechanisms and/or toxicokinetics; health-based exposure limits may be based on an established NOAEL (no observed adverse effect level). (D) Non-genotoxic carcinogens and non-DNA-reactive carcinogens; for these compounds a true ("perfect") threshold is associated with a clearly founded NOAEL. The mechanisms shown by tumour promoters, spindle poisons, topoisomerase II poisons and hormones are typical examples of this category. Health-based OELs are derived for carcinogens of groups C and D, while a risk assessment is carried out for carcinogens of groups A and B. Substantial progress is currently being made in the incorporation of new types of mechanistic data into these regulatory procedures.

  13. Magazines as wilderness information sources: assessing users' general wilderness knowledge and specific leave no trace knowledge

    Treesearch

    John J. Confer; Andrew J. Mowen; Alan K. Graefe; James D. Absher

    2000-01-01

    The Leave No Trace (LNT) educational program has the potential to provide wilderness users with useful minimum impact information. For LNT to be effective, managers need to understand who is most/least aware of minimum impact practices and how to expose users to LNT messages. This study examined LNT knowledge among various user groups at an Eastern wilderness area and...

  14. SU-E-T-04: 3D Dose Based Patient Compensator QA Procedure for Proton Radiotherapy

    SciTech Connect

    Zou, W; Reyhan, M; Zhang, M; Davis, R; Jabbour, S; Khan, A; Yue, N

    2015-06-15

    Purpose: In proton double-scattering radiotherapy, compensators are the essential patient specific devices to contour the distal dose distribution to the tumor target. Traditional compensator QA is limited to checking the drilled surface profiles against the plan. In our work, a compensator QA process was established that assess the entire compensator including its internal structure for patient 3D dose verification. Methods: The fabricated patient compensators were CT scanned. Through mathematical image processing and geometric transformations, the CT images of the proton compensator were combined with the patient simulation CT images into a new series of CT images, in which the imaged compensator is placed at the planned location along the corresponding beam line. The new CT images were input into the Eclipse treatment planning system. The original plan was calculated to the combined CT image series without the plan compensator. The newly computed patient 3D dose from the combined patientcompensator images was verified against the original plan dose. Test plans include the compensators with defects intentionally created inside the fabricated compensators. Results: The calculated 3D dose with the combined compensator and patient CT images reflects the impact of the fabricated compensator to the patient. For the test cases in which no defects were created, the dose distributions were in agreement between our method and the corresponding original plans. For the compensator with the defects, the purposely changed material and a purposely created internal defect were successfully detected while not possible with just the traditional compensator profiles detection methods. Conclusion: We present here a 3D dose verification process to qualify the fabricated proton double-scattering compensator. Such compensator detection process assesses the patient 3D impact of the fabricated compensator surface profile as well as the compensator internal material and structure changes. This research receives funding support from CURA Medical Technologies.

  15. Immunotoxicity of perfluorinated alkylates: calculation of benchmark doses based on serum concentrations in children.

    PubMed

    Grandjean, Philippe; Budtz-Jørgensen, Esben

    2013-04-19

    Immune suppression may be a critical effect associated with exposure to perfluorinated compounds (PFCs), as indicated by recent data on vaccine antibody responses in children. Therefore, this information may be crucial when deciding on exposure limits. Results obtained from follow-up of a Faroese birth cohort were used. Serum-PFC concentrations were measured at age 5 years, and serum antibody concentrations against tetanus and diphtheria toxoids were obtained at age 7 years. Benchmark dose results were calculated in terms of serum concentrations for 431 children with complete data using linear and logarithmic curves, and sensitivity analyses were included to explore the impact of the low-dose curve shape. Under different linear assumptions regarding dose-dependence of the effects, benchmark dose levels were about 1.3 ng/mL serum for perfluorooctane sulfonic acid and 0.3 ng/mL serum for perfluorooctanoic acid at a benchmark response of 5%. These results are below average serum concentrations reported in recent population studies. Even lower results were obtained using logarithmic dose-response curves. Assumption of no effect below the lowest observed dose resulted in higher benchmark dose results, as did a benchmark response of 10%. The benchmark dose results obtained are in accordance with recent data on toxicity in experimental models. When the results are converted to approximate exposure limits for drinking water, current limits appear to be several hundred fold too high. Current drinking water limits therefore need to be reconsidered.

  16. Estimation of the effects of normal tissue sparing using equivalent uniform dose-based optimization

    PubMed Central

    Senthilkumar, K.; Maria Das, K. J.; Balasubramanian, K.; Deka, A. C.; Patil, B. R.

    2016-01-01

    In this study, we intend to estimate the effects of normal tissue sparing between intensity modulated radiotherapy (IMRT) treatment plans generated with and without a dose volume (DV)-based physical cost function using equivalent uniform dose (EUD). Twenty prostate cancer patients were retrospectively selected for this study. For each patient, two IMRT plans were generated (i) EUD-based optimization with a DV-based physical cost function to control inhomogeneity (EUDWith DV) and (ii) EUD-based optimization without a DV-based physical cost function to allow inhomogeneity (EUDWithout DV). The generated plans were prescribed a dose of 72 Gy in 36 fractions to planning target volume (PTV). Mean dose, D30%, and D5% were evaluated for all organ at risk (OAR). Normal tissue complication probability was also calculated for all OARs using BioSuite software. The average volume of PTV for all patients was 103.02 ± 27 cm3. The PTV mean dose for EUDWith DV plans was 73.67 ± 1.7 Gy, whereas for EUDWithout DV plans was 80.42 ± 2.7 Gy. It was found that PTV volume receiving dose more than 115% of prescription dose was negligible in EUDWith DV plans, whereas it was 28% in EUDWithout DV plans. In almost all dosimetric parameters evaluated, dose to OARs in EUDWith DV plans was higher than in EUDWithout DV plans. Allowing inhomogeneous dose (EUDWithout DV) inside the target would achieve better normal tissue sparing compared to homogenous dose distribution (EUDWith DV). Hence, this inhomogeneous dose could be intentionally dumped on the high-risk volume to achieve high local control. Therefore, it was concluded that EUD optimized plans offer added advantage of less OAR dose as well as selectively boosting dose to gross tumor volume. PMID:27217624

  17. Development of predictive models for estimating warfarin maintenance dose based on genetic and clinical factors.

    PubMed

    Yang, Lu; Linder, Mark W

    2013-01-01

    In this chapter, we use calculation of estimated warfarin maintenance dosage as an example to illustrate how to develop a multiple linear regression model to quantify the relationship between several independent variables (e.g., patients' genotype information) and a dependent variable (e.g., measureable clinical outcome).

  18. Proposal of human spinal cord reirradiation dose based on collection of data from 40 patients

    SciTech Connect

    Nieder, Carsten . E-mail: cnied@hotmail.com; Grosu, Anca L.; Andratschke, Nicolaus H.; Molls, Michael

    2005-03-01

    Purpose: Driven by numerous reports on recovery of occult radiation injury, reirradiation of the spinal cord today is considered a realistic option. In rodents, long-term recovery was observed to start at approximately 8 weeks. However, prospective clinical studies are lacking. Therefore, a combined analysis of all published clinical data might provide a valuable basis for future trials. Methods and materials: We collected data from 40 individual patients published in eight different reports after a comprehensive MEDLINE search. These represent all patients with data available for dose per fraction and total dose of each of both treatment courses. We recalculated the biologically effective dose (BED) according to the linear-quadratic model using an {alpha}/{beta} value of 2 Gy for the cervical and thoracic cord and 4 Gy for the lumbar cord. In this model, a dose of 50 Gy given in single daily fractions of 2 Gy is equivalent to a BED of 100 Gy{sub 2} or 75 Gy{sub 4}. For treatment with two daily fractions, a correction term was introduced to take incomplete repair of sublethal damage into account. Results: The cumulative doses ranged from 108 to 205 Gy{sub 2} (median dose, 135 Gy{sub 2}). The median interval between both series was 20 months. Three patients were treated to the lumbar segments only. The median follow-up was 17 months for patients without myelopathy. Eleven patients developed myelopathy after 4-25 months (median, 11 months). Myelopathy was seen only in patients who had received one course to a dose of {>=}102 Gy{sub 2} (n = 9) or were retreated after 2 months (n = 2). In the absence of these two risk factors, no myelopathy developed in 19 patients treated with {<=}135.5 Gy{sub 2} or 7 patients treated with 136-150 Gy{sub 2}. A risk score based on the cumulative BED, the greatest BED for all treatment series in a particular individual, and interval was developed. Low-risk patients remained free of myelopathy and 33% of intermediate-risk patients and 90% of high-risk patients developed myelopathy. Conclusion: On the basis of these literature data (and with due caution), the risk of myelopathy appears small after {<=}135.5 Gy{sub 2} when the interval is not shorter than 6 months and the dose of each course is {<=}98 Gy{sub 2}. We would recommend limiting the dose to this level, whenever technically feasible. However, it appears prudent to propose the collection of prospective data from a greater number of patients receiving doses in the range of 136-150 Gy{sub 2} to assess the safety of higher retreatment doses for those patients in whom limited doses might compromise tumor control.

  19. The estrogenic effects of benzylparaben at low doses based on uterotrophic assay in immature SD rats.

    PubMed

    Hu, Ying; Zhang, Zhaobin; Sun, Libei; Zhu, Desheng; Liu, Qingchun; Jiao, Jian; Li, Jun; Qi, Mingwen

    2013-03-01

    Benzylparaben (BzP), a type of parabens being used as a preservative agent in cosmetics, food, and pharmaceutical products, may be ingested by humans. In this study, we performed an immature uterotrophic assay using Sprague Dawley (SD) rats by intragastric administration to determine the estrogenic effects of BzP and found significant increases in uterine weight with doses of 0.16 mg/kg body weight and higher (P<0.05). The in vivo estrogenicity of BzP was supported by in vitro results from the human estrogen receptor α (hERα)-coactivator recruiting assay and in silico molecular docking analysis performed in this study. The in vitro estrogenic activity of BzP can be observed at concentrations of 1.0×10(-8) M and higher. Molecular docking analysis showed that BzP fits well into the agonist pocket of hERα. The lowest observed effect dose (LOED) (0.16 mg/kg/day) of BzP is much lower than the documented LOEDs of other parabens. Actual risk may exist for people who consume a diet high in BzP or use BzP-laden cosmetics. In addition, we tested the sensitivity of Wistar rats to 17β-estradiol by immature uterotrophic assay, and no obvious uterotrophic response was observed in the rats given doses up to 100 μg/kg body weight.

  20. [Estimation of personal dose based on the dependent calibration of personal dosimeters in interventional radiology].

    PubMed

    Mori, Hiroshige; Koshida, Kichiro; Ichikawa, Katsuhiro

    2007-08-20

    The purpose of present study is, in interventional radiology (IVR), to elucidate the differences between each personal dosimeter, and the dependences and calibrations of area or personal dose by measurement with electronic dosimeters in particular. We compare space dose rate distributions measured by an ionization survey meter with the value measured by personal dosimeter: an optically stimulated luminescence, two fluoroglass, and two electronic dosimeters. Furthermore, with electronic dosimeters, we first measured dose rate, energy, and directional dependences. Secondly, we calibrated the dose rate measured by electronic dosimeters with the results, and estimated these methods with coefficient of determination and Akaike's Information Criterion (AIC). The results, especially in electronic dosimeters, revealed that the dose rate measured fell by energy and directional dependences. In terms of methods of calibration, the method is sufficient for energy dependence, but not for directional dependence, because of the lack of stable calibration. This improvement poses a question for the future. The study suggested that these dependences of the personal dosimeter must be considered when area or personal dose is estimated in IVR.

  1. Blood alcohol levels in rats: non-uniform yields from intraperitoneal doses based on body weight.

    PubMed Central

    Bloom, F.; Lad, P.; Pittman, Q.; Rogers, J.

    1982-01-01

    1 Sprague-Dawley rats (n = 72) weighing from 125 to 450 g were injected intraperitoneally (i.p.) with 16% (w/v) ethanol to provide 1, 2 or 3 g/kg doses. 2 Resulting blood alcohol levels (BALs) demonstrated a general inadequacy of dose/body weight (g/kg) formulations of ethanol to provide uniform BALs in animals of different weights. 3 BAL differences between heavier and lighter rats were not well accounted for by developmental changes in liver weight or alcohol dehydrogenase activity. 4 From the data, a table was derived of more appropriate ethanol injection volumes to produce 0-300 mg% BALs (20 mg% increments) in rats from 100-500 g (10 g increments). PMID:7074285

  2. Implications for human and environmental health of low doses of ionising radiation.

    PubMed

    Mothersill, Carmel; Seymour, Colin

    2014-07-01

    The last 20 years have seen a major paradigm shift in radiation biology. Several discoveries challenge the DNA centric view which holds that DNA damage is the critical effect of radiation irrespective of dose. This theory leads to the assumption that dose and effect are simply linked - the more energy deposition, the more DNA damage and the greater the biological effect. This is embodied in radiation protection (RP) regulations as the linear-non-threshold (LNT) model. However the science underlying the LNT model is being challenged particularly in relation to the environment because it is now clear that at low doses of concern in RP, cells, tissues and organisms respond to radiation by inducing responses which are not readily predictable by dose. These include adaptive responses, bystander effects, genomic instability and low dose hypersensitivity, and are commonly described as stress responses, while recognizing that "stress" can be good as well as bad. The phenomena contribute to observed radiation responses and appear to be influenced by genetic, epigenetic and environmental factors, meaning that dose and response are not simply related. The question is whether our discovery of these phenomena means that we need to re-evaluate RP approaches. The so-called "non-targeted" mechanisms mean that low dose radiobiology is very complex and supra linear or sub-linear (even hormetic) responses are possible but their occurrence is unpredictable for any given system level. Issues which may need consideration are synergistic or antagonistic effects of other pollutants. RP, at present, only looks at radiation dose but the new (NTE) radiobiology means that chemical or physical agents, which interfere with tissue responses to low doses of radiation, could critically modulate the predicted risk. Similarly, the "health" of the organism could determine the effect of a given low dose by enabling or disabling a critical response. These issues will be discussed.

  3. NOx Storage-Reduction Characteristics of Ba-Based Lean NOx Trap Catalysts Subjected to Simulated Road Aging

    SciTech Connect

    Ji, Yaying; Fisk, Courtney; Easterling, Vencon; Graham, Uschi; Poole, Adam; Crocker, Mark; Choi, Jae-Soon; Partridge Jr, William P; Wilson, Karen

    2010-01-01

    Although Lean NO{sub x} Trap (LNT) catalyst technology has made significant strides in recent years, the issue of LNT durability remains problematic. Following on from our previous research concerning the effect of ceria addition on LNT preformance, in this study we focus on the role of ceria in ameliorating the deterioration of Ba-based LNT catalysts during aging. Indeed, we have observed that spectacular improvements in LNT durability can be achieved through the incorporation of CeO{sub 2}-ZrO{sub 2} into the LNT formulation, and, to a lesser extent, La-stabilized ceria.

  4. Inhibitory effect of sulfated lentinan and lentinan against tobacco mosaic virus (TMV) in tobacco seedlings.

    PubMed

    Wang, Jie; Wang, Hong-Yan; Xia, Xiao-Ming; Li, Peng-peng; Wang, Kai-Yun

    2013-10-01

    The antiviral activities of sulfated lentinan (sLNT) and lentinan (LNT) against tobacco mosaic virus (TMV) in tobacco seedlings and the underlying mechanism were investigated. Compared with LNT, sLNT showed significantly higher inhibitory effects on viral infection and TMV multiplication in a dose-dependent way, which might be due to its binding with TMV coat protein. In addition, both sLNT and LNT induced the transient production of H2O2 and expression of some defense-related genes (stilbene synthase, glucanase, acidic chitinase class IV, phenylalanine ammonia-lyase and 5-epi-aristolochene synthase) both locally and systemically. These results suggested that sLNT and LNT could control TMV incidence and the action mechanism might be associated with the affinity towards TMV coat protein and activation of some defense genes. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. American Society for Pain Management Nursing Position Statement: Prescribing and Administering Opioid Doses Based Solely on Pain Intensity.

    PubMed

    Pasero, Chris; Quinlan-Colwell, Ann; Rae, Diana; Broglio, Kathleen; Drew, Debra

    2016-06-01

    The foundation of safe and effective pain management is an individualized, comprehensive pain assessment, which includes, but is not limited to, determining the intensity of pain if the patient is able to report it. An unforeseen consequence of the widespread use of pain intensity rating scales is the practice of prescribing specific doses of opioid analgesics based solely on specific pain intensity. Many factors in addition to pain intensity influence opioid requirements, and there is no research showing that a specific opioid dose will relieve pain of a specific intensity in all patients. The American Society for Pain Management Nursing (ASPMN) holds the position that the practice of prescribing doses of opioid analgesics based solely on a patient's pain intensity should be prohibited because it disregards the relevance of other essential elements of assessment and may contribute to untoward patient outcomes. Copyright © 2016 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.

  6. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method.

    PubMed

    Larson, David B

    2014-10-01

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach.

  7. A mobile bioassay laboratory for the assessment of internal doses based on in vivo and in vitro measurements.

    PubMed

    Dantas, B M; Lucena, E A; Dantas, A L A; Santos, M S; Julião, L Q C; Melo, D R; Sousa, W O; Fernandes, P C; Mesquita, S A

    2010-10-01

    Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.

  8. Non-linear adaptive phenomena which decrease the risk of infection after pre-exposure to radiofrequency radiation.

    PubMed

    Mortazavi, S M J; Motamedifar, M; Namdari, G; Taheri, M; Mortazavi, A R; Shokrpour, N

    2014-05-01

    Substantial evidence indicates that adaptive response induced by low doses of ionizing radiation can result in resistance to the damage caused by a subsequently high-dose radiation or cause cross-resistance to other non-radiation stressors. Adaptive response contradicts the linear-non-threshold (LNT) dose-response model for ionizing radiation. We have previously reported that exposure of laboratory animals to radiofrequency radiation can induce a survival adaptive response. Furthermore, we have indicated that pre-exposure of mice to radiofrequency radiation emitted by a GSM mobile phone increased their resistance to a subsequent Escherichia coli infection. In this study, the survival rates in animals receiving both adapting (radiofrequency) and challenge dose (bacteria) and the animals receiving only the challenge dose (bacteria) were 56% and 20%, respectively. In this light, our findings contribute to the assumption that radiofrequency-induced adaptive response can be used as an efficient method for decreasing the risk of infection in immunosuppressed irradiated individuals. The implication of this phenomenon in human's long term stay in the space is also discussed.

  9. Clinical Outcomes of Biological Effective Dose-Based Fractionated Stereotactic Radiation Therapy for Metastatic Brain Tumors From Non-Small Cell Lung Cancer

    SciTech Connect

    Matsuyama, Tomohiko; Kogo, Kasei; Oya, Natsuo

    2013-03-15

    Purpose: To evaluate the efficacy and toxicity of fractionated stereotactic radiation therapy (FSRT) based on biological effective dose (BED), a novel approach to deliver a fixed BED irrespective of dose fractionation, for brain metastases from non-small cell lung cancer (NSCLC). Methods and Materials: Between March 2005 and March 2009 we treated 299 patients with 1 to 5 lesions from NSCLC (573 total brain metastases) with FSRT using Novalis. The dose fractionation schedules were individually determined to deliver a peripheral BED10 (α/β ratio = 10) of approximately 80 Gy{sub 10}. The median number of fractions was 3 (range, 2-10), the median peripheral BED10 was 83.2 Gy (range, 19.1-89.6 Gy). Patients were followed up with magnetic resonance imaging (MRI) studies performed at 1- to 2-month intervals. The local tumor control rate and overall local progression-free and intracranial relapse-free survival were calculated by the Kaplan-Meier method. Results: Local control rates for all 573 lesions at 6 and 12 months were 96.3% and 94.5%, respectively. By multivariate analysis the tumor diameter was the only factor predictive of the local control rate (P=.001). The median overall survival, local progression-free survival, and intracranial relapse-free survival were 17.1, 14.9, and 4.4 months, respectively. The overall survival, local progression-free survival, and intracranial relapse-free survival rates at 6 and 12 months were 78.5% and 63.3%, 74.3% and 57.8%, and 41.0% and 21.8%, respectively. Six patients (2%) manifested progressive radiation injury to the brain even during therapy with corticosteroids; they underwent hyperbaric oxygen therapy, and follow-up MRI showed improvement. Conclusions: This study showed that BED-based FSRT for brain metastases from NSCLC is a promising strategy that may yield excellent outcomes with acceptable toxicity. Criteria must be established to determine the optimal dose fractionation for individual patients.

  10. SU-D-201-02: Prediction of Delivered Dose Based On a Joint Histogram of CT and FDG PET Images

    SciTech Connect

    Park, M; Choi, Y; Cho, A; Hwang, S; Cha, J; Lee, N; Yun, M

    2015-06-15

    Purpose: To investigate whether pre-treatment images can be used in predicting microsphere distribution in tumors. When intra-arterial radioembolization using Y90 microspheres was performed, the microspheres were often delivered non-uniformly within the tumor, which could lead to an inefficient therapy. Therefore, it is important to estimate the distribution of microspheres. Methods: Early arterial phase CT and FDG PET images were acquired for patients with primary liver cancer prior to radioembolization (RE) using Y90 microspheres. Tumor volume was delineated on CT images and fused with FDG PET images. From each voxel (3.9×3.9×3.3 mm3) in the tumor, the Hounsfield unit (HU) from the CT and SUV values from the FDG PET were harvested. We binned both HU and SUV into 11 bins and then calculated a normalized joint-histogram in an 11×11 array.Patients also underwent a post-treatment Y90 PET imaging. Radiation dose for the tumor was estimated using convolution of the Y90 distribution with a dose-point kernel. We also calculated a fraction of the tumor volume that received a radiation dose great than 100Gy. Results: Averaged over 40 patients, 55% of tumor volume received a dose greater than 100Gy (range : 1.1 – 100%). The width of the joint histogram was narrower for patients with a high dose. For patients with a low dose, the width was wider and a larger fraction of tumor volume had low HU. Conclusion: We have shown the pattern of joint histogram of the HU and SUV depends on delivered dose. The patterns can predict the efficacy of uniform intra-arterial delivery of Y90 microspheres.

  11. Dose-response relationship between dietary magnesium intake and cardiovascular mortality: A systematic review and dose-based meta-regression analysis of prospective studies.

    PubMed

    Fang, Xin; Liang, Chun; Li, Mei; Montgomery, Scott; Fall, Katja; Aaseth, Jan; Cao, Yang

    2016-12-01

    Although epidemiology studies have reported the relationship, including a dose-response relationship, between dietary magnesium intake and risk of cardiovascular disease (CVD), the risk for CVD mortality is inconclusive and the evidence for a dose-response relationship has not been summarized. We conducted a systematic review and meta-analysis of prospective studies to summarize the evidence regarding the association of dietary magnesium intake with risk of CVD mortality and describe their dose-response relationship. We identified relevant studies by searching major scientific literature databases and grey literature resources from their inception to August 2015, and reviewed references lists of retrieved articles. We included population-based studies that reported mortality risks, i.e. relative risks (RRs), odds ratios (ORs) or hazard ratios (HRs) of CVD mortality or cause-specific CVD death. Linear dose-response relationships were assessed using random-effects meta-regression. Potential nonlinear associations were evaluated using restricted cubic splines. Out of 3002 articles, 9 articles from 8 independent studies met the eligibility criteria. These studies comprised 449,748 individuals and 10,313 CVD deaths. Compared with the lowest dietary magnesium consumption group in the population, the risk of CVD mortality was reduced by 16% in women and 8% in men. No significant linear dose-response relationship was found between increment in dietary magnesium intake and CVD mortality across all the studies. After adjusting for age and BMI, the risk of CVD mortality was reduced by 24-25% per 100mg/d increment in dietary magnesium intake in women of all the participants and in all the US participants. Although the combined data confirm the role of dietary magnesium intake in reducing CVD mortality, the dose-response relationship was only found among women and in US population. Copyright © 2016 Elsevier GmbH. All rights reserved.

  12. Genomic rearrangements and signatures of breeding in the allo-octoploid strawberry as revealed through an allele dose based SSR linkage map

    PubMed Central

    2014-01-01

    Background Breeders in the allo-octoploid strawberry currently make little use of molecular marker tools. As a first step of a QTL discovery project on fruit quality traits and resistance to soil-borne pathogens such as Phytophthora cactorum and Verticillium we built a genome-wide SSR linkage map for the cross Holiday x Korona. We used the previously published MADCE method to obtain full haplotype information for both of the parental cultivars, facilitating in-depth studies on their genomic organisation. Results The linkage map incorporates 508 segregating loci and represents each of the 28 chromosome pairs of octoploid strawberry, spanning an estimated length of 2050 cM. The sub-genomes are denoted according to their sequence divergence from F. vesca as revealed by marker performance. The map revealed high overall synteny between the sub-genomes, but also revealed two large inversions on LG2C and LG2D, of which the latter was confirmed using a separate mapping population. We discovered interesting breeding features within the parental cultivars by in-depth analysis of our haplotype data. The linkage map-derived homozygosity level of Holiday was similar to the pedigree-derived inbreeding level (33% and 29%, respectively). For Korona we found that the observed homozygosity level was over three times higher than expected from the pedigree (13% versus 3.6%). This could indicate selection pressure on genes that have favourable effects in homozygous states. The level of kinship between Holiday and Korona derived from our linkage map was 2.5 times higher than the pedigree-derived value. This large difference could be evidence of selection pressure enacted by strawberry breeders towards specific haplotypes. Conclusion The obtained SSR linkage map provides a good base for QTL discovery. It also provides the first biologically relevant basis for the discernment and notation of sub-genomes. For the first time, we revealed genomic rearrangements that were verified in a separate mapping population. We believe that haplotype information will become increasingly important in identifying marker-trait relationships and regions that are under selection pressure within breeding material. Our attempt at providing a biological basis for the discernment of sub-genomes warrants follow-up studies to streamline the naming of the sub-genomes among different octoploid strawberry maps. PMID:24581289

  13. A tissue dose-based comparative exposure assessment of manganese using physiologically based pharmacokinetic modeling-The importance of homeostatic control for an essential metal.

    PubMed

    Gentry, P Robinan; Van Landingham, Cynthia; Fuller, William G; Sulsky, Sandra I; Greene, Tracy B; Clewell, Harvey J; Andersen, Melvin E; Roels, Harry A; Taylor, Michael D; Keene, Athena M

    2017-02-22

    A physiologically-based pharmacokinetic (PBPK) model (Schroeter et al., 2011) was applied to simulate target tissue manganese (Mn) concentrations following occupational and environmental exposures. These estimates of target tissue Mn concentrations were compared to determine margins of safety (MOS) and to evaluate the biological relevance of applying safety factors to derive acceptable Mn air concentrations. Mn blood concentrations measured in occupational studies permitted verification of the human PBPK models, increasing confidence in the resulting estimates. Mn exposure was determined based on measured ambient air Mn concentrations and dietary data in Canada and the United States (US). Incorporating dietary and inhalation exposures into the models indicated that increases in target tissue concentrations above endogenous levels only begin to occur when humans are exposed to levels of Mn in ambient air (i.e. >10μg/m(3)) that are far higher than those currently measured in Canada or the US. A MOS greater than three orders of magnitude was observed, indicating that current Mn air concentrations are far below concentrations that would be required to produce the target tissue Mn concentrations associated with subclinical neurological effects. This application of PBPK modeling for an essential element clearly demonstrates that the conventional application of default factors to "convert" an occupational exposure to an equivalent continuous environmental exposure, followed by the application of safety factors, is not appropriate in the case of Mn. PBPK modeling demonstrates that the relationship between ambient Mn exposures and dose-to-target tissue is not linear due to normal tissue background levels and homeostatic controls.

  14. Predictive Dose-Based Estimation of Systemic Exposure Multiples in Mouse and Monkey Relative to Human for Antisense Oligonucleotides With 2′-O-(2-Methoxyethyl) Modifications

    PubMed Central

    Yu, Rosie Z; Grundy, John S; Henry, Scott P; Kim, Tae-Won; Norris, Daniel A; Burkey, Jennifer; Wang, Yanfeng; Vick, Andrew; Geary, Richard S

    2015-01-01

    Evaluation of species differences and systemic exposure multiples (or ratios) in toxicological animal species versus human is an ongoing exercise during the course of drug development. The systemic exposure ratios are best estimated by directly comparing area under the plasma concentration-time curves (AUCs), and sometimes by comparing the dose administered, with the dose being adjusted either by body surface area (BSA) or body weight (BW). In this study, the association between AUC ratio and the administered dose ratio from animals to human were studied using a retrospective data-driven approach. The dataset included nine antisense oligonucleotides (ASOs) with 2′-O-(2-methoxyethyl) modifications, evaluated in two animal species (mouse and monkey) following single and repeated parenteral administrations. We found that plasma AUCs were similar between ASOs within the same species, and are predictable to human exposure using a single animal species, either mouse or monkey. Between monkey and human, the plasma exposure ratio can be predicted directly based on BW-adjusted dose ratios, whereas between mouse and human, the exposure ratio would be nearly fivefold lower in mouse compared to human based on BW-adjusted dose values. Thus, multiplying a factor of 5 for the mouse BW-adjusted dose would likely provide a reasonable AUC exposure estimate in human at steady-state. PMID:25602582

  15. A novel self-assembly Lentinan-tetraphenylethylene​ composite with strong blue​ fluorescence in water and its properties.

    PubMed

    Li, Mengxia; Chen, Pan; Xu, Min; Xu, Xiaojuan

    2017-10-15

    We report a unique self-assembly of lentinan, a triple helical β-(1→3)-glucan (t-LNT), in water. By molecular dynamics simulation, it was found that t-LNT aggregated preferentially along the chain direction to form long chains, accompanied by side-direction linkage to form branches. Transmission electron microscopy images demonstrated that t-LNT formed dendrite-like fibers, which further formed fishnet-like porous/mesoporous aggregates with increasing concentration. The meshes in the fishnet were ascribed to the intersection of branches. The major driving force for aggregation was expected to be hydrogen bonding between hydroxyl groups in t-LNT chains. Based on this self-assembly behavior, a novel composite was prepared from t-LNT and tetraphenylethylene (TPE) by entrapping TPE aggregates into the meshes of t-LNT fishnets. The as-prepared t-LNT/TPE composite largely enhanced the blue fluorescence of TPE in water, exhibiting stable optical property and good biocompatibility, and t-LNT is expected to show great potential as a carrier of hydrophobic molecules for biomedical application. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Confined organization of Au nanocrystals in glycolipid nanotube hollow cylinders.

    PubMed

    Yang, Bo; Kamiya, Shoko; Yoshida, Kaname; Shimizu, Toshimi

    2004-03-07

    Mild fabrication of anisotropic metal-lipid nanotube (LNT) nanocomposites, in which Au nanoparticles of 3-10 nm wide are organized in a glycolipid nanotube hollow cylinder, has been achieved by filling the internal channel of the LNT with HAuCl(4) aqueous solution by capillary force and subsequent photochemical reduction of [AuCl(4)](-).

  17. Measuring the educational impact of Promoting Environmental Awareness in Kids (PEAK): The development and implementation of a new scale

    Treesearch

    Jennifer Miller; Lindsey Brown; Eddie Hill; Amy Shellman; Ron Ramsing; Edwin. Gómez

    2012-01-01

    The Leave No Trace Center for Outdoor Ethics (LNT) is a nonprofit educational organization that teaches skills and values for recreating responsibly in the out-of-doors. LNT developed Promoting Environmental Awareness in Kids (PEAK), based on seven ethical principles. The PEAK program provides a pack that contains several interactive activities specifically designed to...

  18. GLUT1: A novel tool reflecting proliferative activity of lung neuroendocrine tumors?

    PubMed

    Benzerdjeb, Nazim; Berna, Pascal; Sevestre, Henri

    2017-01-01

    Lung neuroendocrine tumors (LNT) represents approximately 20% of all lung cancers. The classification of LNT relies upon morphology. Recently, in the World Health Organization (WHO) classification, Ki-67 rate has been proposed for classification. It is, however, known that Ki-67 count has a poor interlaboratory reproducibly. For that reason, our team has looked for a new biomarker. GLUT1 protein a facilitative glucose transporter protein which has ubiquitous expression in mammalian. GLUT1 is overexpressed in many human cancers. But, no study has evaluated the GLUT1 staining as an aid diagnosis in LNT. Our team have assessed the GLUT1 immunohistochemical staining in 36 LNT and to assess its diagnostic value. GLUT1 staining was higher in neuroendocrine carcinoma than in carcinoid tumor. A positive predictive value in a priori and posteriori testing for diagnosis of LNT is demonstrated. GLUT1 staining could aid in the diagnosis and should be validated in a large prospective cohort.

  19. Randomised phase III study of S-1 alone versus S-1 plus lentinan for unresectable or recurrent gastric cancer (JFMC36-0701).

    PubMed

    Yoshino, Shigefumi; Nishikawa, Kazuhiro; Morita, Satoshi; Takahashi, Tsuyoshi; Sakata, Koichiro; Nagao, Jiro; Nemoto, Hiroshi; Murakami, Nozomu; Matsuda, Takeru; Hasegawa, Hiroyasu; Shimizu, Ryoichi; Yoshikawa, Takaki; Osanai, Hiroyuki; Imano, Motohiro; Naitoh, Hiroshi; Tanaka, Akiyoshi; Tajiri, Takashi; Gochi, Akira; Suzuki, Michinari; Sakamoto, Junichi; Saji, Shigetoyo; Oka, Masaaki

    2016-09-01

    Lentinan (LNT) is a purified β-1, 3-glucan that augments immune responses. The present study was conducted to assess the efficacy of LNT in combination with S-1 as a first-line treatment for unresectable or recurrent gastric cancer. Eligible patients were randomly assigned to receive S-1 alone or S-1 plus LNT. The primary end-point was overall survival (OS). Secondary end-points were time-to-treatment failure (TTF), overall response rate (ORR), safety, quality of life (QOL), and biomarker. The percentages of LNT-binding monocytes in peripheral blood prior to treatment were analysed for the biomarker assessment. One hundred and fifty-four and 155 patients were randomly assigned to receive S-1 alone or S-1 plus LNT, respectively. The median OS was 13.8 and 9.9 months (P = 0.208), the median TTF was 4.3 and 2.6 months (P < 0.001), the ORR was 22.3% and 18.7% for the S-1 and S-1 plus LNT groups, respectively. The incidences of haematologic and non-haematologic adverse events were similar, and no significant changes in QOL scores were observed during the treatment in both groups. In a subpopulation of patients with LNT-binding monocytes ≥2%, patients who received more than two cycles of chemotherapy showed a longer survival time in the S-1 plus LNT group. OS did not improve and TTF was significantly worse in the S-1 plus LNT group as compared with the S-1-only group. This study showed no efficacy of LNT when combined with S-1 treatment in patients with unresectable or recurrent gastric cancer. UMIN 000000574. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  20. Lymph Node Transplantation Decreases Swelling and Restores Immune Responses in a Transgenic Model of Lymphedema

    PubMed Central

    Hespe, Geoffrey E.; García Nores, Gabriela D.; Kataru, Raghu P.; Martínez-Corral, Inés; Ortega, Sagrario; Mehrara, Babak J.

    2016-01-01

    Introduction Secondary lymphedema is a common complication of cancer treatment and recent studies have demonstrated that lymph node transplantation (LNT) can decrease swelling, as well as the incidence of infections. However, although these results are exciting, the mechanisms by which LNT improves these pathologic findings of lymphedema remain unknown. Using a transgenic mouse model of lymphedema, this study sought to analyze the effect of LNT on lymphatic regeneration and T cell-mediated immune responses. Methods We used a mouse model in which the expression of the human diphtheria toxin receptor is driven by the FLT4 promoter to enable the local ablation of the lymphatic system through subdermal hindlimb diphtheria toxin injections. Popliteal lymph node dissection was subsequently performed after a two-week recovery period, followed by either orthotopic LNT or sham surgery after an additional two weeks. Hindlimb swelling, lymphatic vessel regeneration, immune cell trafficking, and T cell-mediated immune responses were analyzed 10 weeks later. Results LNT resulted in a marked decrease in hindlimb swelling, fibroadipose tissue deposition, and decreased accumulation of perilymphatic inflammatory cells, as compared to controls. In addition, LNT induced a marked lymphangiogenic response in both capillary and collecting lymphatic vessels. Interestingly, the resultant regenerated lymphatics were abnormal in appearance on lymphangiography, but LNT also led to a notable increase in dendritic cell trafficking from the periphery to the inguinal lymph nodes and improved adaptive immune responses. Conclusions LNT decreases pathological changes of lymphedema and was shown to potently induce lymphangiogenesis. Lymphatic vessels induced by LNT were abnormal in appearance, but were functional and able to transport antigen-presenting cells. Animals treated with LNT have an increased ability to mount T cell-mediated immune responses when sensitized to antigens in the affected

  1. Global and local cancer risks after the Fukushima Nuclear Power Plant accident as seen from Chernobyl: a modeling study for radiocaesium ((134)Cs &(137)Cs).

    PubMed

    Evangeliou, Nikolaos; Balkanski, Yves; Cozic, Anne; Møller, Anders Pape

    2014-03-01

    The accident at the Fukushima Daiichi Nuclear Power Plant (NPP) in Japan resulted in the release of a large number of fission products that were transported worldwide. We study the effects of two of the most dangerous radionuclides emitted, (137)Cs (half-life: 30.2years) and (134)Cs (half-life: 2.06years), which were transported across the world constituting the global fallout (together with iodine isotopes and noble gasses) after nuclear releases. The main purpose is to provide preliminary cancer risk estimates after the Fukushima NPP accident, in terms of excess lifetime incident and death risks, prior to epidemiology, and compare them with those occurred after the Chernobyl accident. Moreover, cancer risks are presented for the local population in the form of high-resolution risk maps for 3 population classes and for both sexes. The atmospheric transport model LMDZORINCA was used to simulate the global dispersion of radiocaesium after the accident. Air and ground activity concentrations have been incorporated with monitoring data as input to the LNT-model (Linear Non-Threshold) frequently used in risk assessments of all solid cancers. Cancer risks were estimated to be small for the global population in regions outside Japan. Women are more sensitive to radiation than men, although the largest risks were recorded for infants; the risk is not depended on the sex at the age-at-exposure. Radiation risks from Fukushima were more enhanced near the plant, while the evacuation measures were crucial for its reduction. According to our estimations, 730-1700 excess cancer incidents are expected of which around 65% may be fatal, which are very close to what has been already published (see references therein). Finally, we applied the same calculations using the DDREF (Dose and Dose Rate Effectiveness Factor), which is recommended by the ICRP, UNSCEAR and EPA as an alternative reduction factor instead of using a threshold value (which is still unknown). Excess lifetime cancer

  2. A comparison approach to explain risks related to X-ray imaging for scoliosis, 2012 SOSORT award winner

    PubMed Central

    2013-01-01

    Background X-ray imaging is frequently used as diagnostic approach for scoliosis in children and adolescents. X-ray procedures are considered as justified only when expected benefits exceed related risks. While benefits are well known to physicians, radiological risk awareness can be vague, impeding an optimal communication with patients’ parents and possibly leading to discomfort and anxiety. Objective of the study is the suggestion of a risk comparison approach for better communicating the radiological risks related to X-ray investigation of scoliosis. Methods Starting point of the analysis is the Linear Non-Threshold (LNT) assumption for radiation stochastic effect, which states that for effective doses (E, Sievert – Sv) below 100 mSv, the probability of future stochastic damage is linearly related to E: absorbing two E’s in separate moments results in the addition of the risks related to each E. This allows to add E from different sources to calculate a cumulative risk of health detriment. Medline (Pubmed) was systematically searched in order to determine the average E delivered during X-ray investigation of scoliosis. Subsequently, the major natural sources of radiation were considered. The average yearly E due to natural sources was compared with E due to the imaging of the vertebral column. Results E’s due to X-ray scoliosis examinations show a large variability: under 7 years of age, 0.03-0.54 mSv; 7–12 years, 0.11-0.80 mSv; 13–18 years, 0.17-1.09 mSv. Overall, 65% of the world population is expected to be exposed to an annual E between 1 and 3 mSv. More in detail, worldwide the total annual average E due to natural sources is 2.4 mSv (range 1–10), of which half originates from Radon exposure. Other sources are cosmic rays and ingestion and inhalation of radionuclides. For example, one flight between Europe and America accounts for 0.030-0.045 mSv because of exposure to cosmic rays. Conclusions X-rays are carcinogenic and exposures to them

  3. Electric moulding of dispersed lipid nanotubes into a nanofluidic device

    PubMed Central

    Frusawa, Hiroshi; Manabe, Tatsuhiko; Kagiyama, Eri; Hirano, Ken; Kameta, Naohiro; Masuda, Mitsutoshi; Shimizu, Toshimi

    2013-01-01

    Hydrophilic nanotubes formed by lipid molecules have potential applications as platforms for chemical or biological events occurring in an attolitre volume inside a hollow cylinder. Here, we have integrated the lipid nanotubes (LNTs) by applying an AC electric field via plug-in electrode needles placed above a substrate. The off-chip assembly method has the on-demand adjustability of an electrode configuration, enabling the dispersed LNT to be electrically moulded into a separate film of parallel LNT arrays in one-step. The fluorescence resonance energy transfer technique as well as the digital microscopy visualised the overall filling of gold nanoparticles up to the inner capacity of an LNT film by capillary action, thereby showing the potential of this flexible film for use as a high-throughput nanofluidic device where not only is the endo-signalling and product in each LNT multiplied but also the encapsulated objects are efficiently transported and reacted. PMID:23835525

  4. Lipid Nanotube Tailored Fabrication of Uniquely Shaped Polydopamine Nanofibers as Photothermal Converters.

    PubMed

    Ding, Wuxiao; Chechetka, Svetlana A; Masuda, Mitsutoshi; Shimizu, Toshimi; Aoyagi, Masaru; Minamikawa, Hiroyuki; Miyako, Eijiro

    2016-03-18

    Helically coiled and linear polydopamine (PDA) nanofibers were selectively fabricated with two different types of lipid nanotubes (LNTs) that acted as templates. The obtained coiled PDA-LNT hybrid showed morphological advantages such as higher light absorbance and photothermal conversion effect compared to a linear counterpart. Laser irradiation of the coiled PDA-LNT hybrid induced a morphological change and subsequent release of the encapsulated guest molecule. In cellular experiments, the coiled PDA-LNT efficiently eliminated HeLa cells because of its strong affinity with the tumor cells. This work illustrates the first approach to construct characteristic morphologies of PDA nanofibers using LNTs as simple templates, and the coiled PDA-LNT hybrid exhibits attractive photothermal features derived from its unique coiled shape. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Evaluation of Cervicography Screening for Cervical Cancer in a High Risk Population

    DTIC Science & Technology

    2000-02-16

    cervicography in cervical screening. lnt J Gynecol Cancer 1993~ 3:395-398. 16. Urdaneta H. Detecci6n de patologia cervical no diagnosticada por citologia...factors related to pregnancy history, menopausal status, smoking history, and oral contraceptive use to assess whether any of these factors affected the...cervical screening. lnt J Gynecol Cancer 1993; 3:395-398. 24 Urdaneta H. Detecci6n de patologia cen,-ical no diagnosticada por citologia vaginal

  6. Lentinan diminishes apoptotic bodies in the ileal crypts associated with S-1 administration.

    PubMed

    Suga, Yasuyo; Takehana, Kenji

    2017-09-01

    S-1 is an oral agent containing tegafur (a prodrug of 5-fluorouracil) that is used to treat various cancers, but adverse effects are frequent. Two pilot clinical studies have suggested that lentinan (LNT; β-1,3-glucan) may reduce the incidence of adverse effects caused by S-1 therapy. In this study, we established a murine model for assessment of gastrointestinal toxicity associated with S-1 and studied the effect of LNT. S-1 was administered orally to BALB/c mice at the effective dose (8.3mg/kg, as tegafur equivalent) once daily (5days per week) for 3weeks. Stool consistency and intestinal specimens were examined. We investigated the effect of combined intravenous administration of LNT at 0.1mg, which is an effective dose in murine tumor models. We also investigated the effect of a single administration of S-1. During long-term administration of S-1, some mice had loose stools and an increase in apoptotic bodies was observed in the ileal crypts. An increase in apoptotic bodies was also noted after a single administration of S-1 (15mg/kg). Prior or concomitant administration of LNT inhibited the increase in apoptotic bodies in both settings. Administration of LNT also increased the accumulation of CD11b(+)TIM-4(+) cells in the ileum, while depletion of these cells by liposomal clodronate diminished the inhibitory effect of LNT on S-1 toxicity. Combined administration of LNT with S-1 led to a decrease in apoptotic bodies in the ileal crypts, possibly because LNT promoted phagocytosis of damaged cells by CD11b(+)TIM-4(+) cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Communicating Leave No Trace ethics and practices: Efficacy of two-day trainer courses

    USGS Publications Warehouse

    Daniels, M.L.; Marion, J.L.

    2005-01-01

    Heavy recreational visitation within protected natural areas has resulted in many ecological impacts. Many of these impacts may be avoided or minimized through adoption of low-impact hiking and camping practices. Although ?No Trace? messages have been promoted in public lands since the 1970s, few studies have documented the reception and effectiveness of these messages. The U.S. Leave No Trace Center for Outdoor Ethics develops and promotes two-day Trainer courses that teach Leave No Trace (LNT) skills and ethics to outdoor professionals, groups, and interested individuals. This study examined the change in knowledge, ethics, and behavior of LNT Trainer course participants. The respondents were a convenience sample of participants in Trainer courses offered from April through August 2003. Trainer course instructors administered pre-course and post-course questionnaires to their participants, and we contacted participants individually with a followup questionnaire 4 months after completion of their course. Scores for each of the sections increased immediately following the course, and decreased slightly over the 4 months following the course. Overall, more than half of the knowledge and behavior items, and half of the ethics items, showed significant improvement from pre-course measures to the follow-up. Age, reported LNT experience, and backpacking experience affected the participants? pre-course knowledge and behavior scores. Younger, less experienced respondents also showed a greater improvement in behavior following the course. Trainer course participants also shared their LNT skills and ethics with others both formally and informally. In summary, the LNT Trainer course was successful in increasing participants? knowledge, ethics, and behavior, which they then shared with others. Since many low impact skills taught in the LNT curriculum are supported by scientific research, LNT educational programs have the potential to effectively minimize the environmental

  8. Night temperature and source–sink effects on overall growth, cell number and cell size in bell pepper ovaries

    PubMed Central

    Darnell, Rebecca L.; Cruz-Huerta, Nicacio; Williamson, Jeffrey G.

    2012-01-01

    Background and Aims Ovary swelling, and resultant fruit malformation, in bell pepper flowers is favoured by low night temperature or a high source–sink ratio. However, the interaction between night temperature and source–sink ratio on ovary swelling and the contribution of cell size and cell number to ovary swelling are unknown. The present research examined the interactive effects of night temperature and source–sink ratio on ovary size, cell number and cell size at anthesis in bell pepper flowers. Methods Bell pepper plants were grown in growth chambers at night temperatures of either 20 °C (HNT) or 12 °C (LNT). Within each temperature treatment, plants bore either 0 (non-fruiting) or two developing fruits per plant. Ovary fresh weight, cell size and cell number were measured. Key Results Ovary fresh weights in non-fruiting plants grown at LNT were the largest, while fresh weights were smallest in plants grown at HNT with fruits. In general, mesocarp cell size in ovaries was largest in non-fruiting plants grown at either LNT or HNT and smallest in fruiting plants at HNT. Mesocarp cell number was greater in non-fruiting plants under LNT than in the rest of the night temperature/fruiting treatments. These responses were more marked in ovaries sampled after 18 d of treatment compared with those sampled after 40 d of treatment. Conclusions Ovary fresh weight of flowers at anthesis increased 65 % in non-fruiting plants grown under LNT compared with fruiting plants grown under HNT. This increase was due primarily to increases in mesocarp cell number and size. These results indicate that the combined effects of LNT and high source–sink ratio on ovary swelling are additive. Furthermore, the combined effects of LNT and low source–sink ratio or HNT and high source–sink ratio can partially overcome the detrimental effects of LNT and high source–sink ratio. PMID:22933415

  9. Night temperature and source-sink effects on overall growth, cell number and cell size in bell pepper ovaries.

    PubMed

    Darnell, Rebecca L; Cruz-Huerta, Nicacio; Williamson, Jeffrey G

    2012-10-01

    Ovary swelling, and resultant fruit malformation, in bell pepper flowers is favoured by low night temperature or a high source-sink ratio. However, the interaction between night temperature and source-sink ratio on ovary swelling and the contribution of cell size and cell number to ovary swelling are unknown. The present research examined the interactive effects of night temperature and source-sink ratio on ovary size, cell number and cell size at anthesis in bell pepper flowers. Bell pepper plants were grown in growth chambers at night temperatures of either 20 °C (HNT) or 12 °C (LNT). Within each temperature treatment, plants bore either 0 (non-fruiting) or two developing fruits per plant. Ovary fresh weight, cell size and cell number were measured. Ovary fresh weights in non-fruiting plants grown at LNT were the largest, while fresh weights were smallest in plants grown at HNT with fruits. In general, mesocarp cell size in ovaries was largest in non-fruiting plants grown at either LNT or HNT and smallest in fruiting plants at HNT. Mesocarp cell number was greater in non-fruiting plants under LNT than in the rest of the night temperature/fruiting treatments. These responses were more marked in ovaries sampled after 18 d of treatment compared with those sampled after 40 d of treatment. Ovary fresh weight of flowers at anthesis increased 65 % in non-fruiting plants grown under LNT compared with fruiting plants grown under HNT. This increase was due primarily to increases in mesocarp cell number and size. These results indicate that the combined effects of LNT and high source-sink ratio on ovary swelling are additive. Furthermore, the combined effects of LNT and low source-sink ratio or HNT and high source-sink ratio can partially overcome the detrimental effects of LNT and high source-sink ratio.

  10. Sulfated lentinan induced mitochondrial dysfunction leads to programmed cell death of tobacco BY-2 cells.

    PubMed

    Wang, Jie; Wang, Yaofeng; Shen, Lili; Qian, Yumei; Yang, Jinguang; Wang, Fenglong

    2017-04-01

    Sulphated lentinan (sLTN) is known to act as a resistance inducer by causing programmed cell death (PCD) in tobacco suspension cells. However, the underlying mechanism of this effect is largely unknown. Using tobacco BY-2 cell model, morphological and biochemical studies revealed that mitochondrial reactive oxygen species (ROS) production and mitochondrial dysfunction contribute to sLNT induced PCD. Cell viability, and HO/PI fluorescence imaging and TUNEL assays confirmed a typical cell death process caused by sLNT. Acetylsalicylic acid (an ROS scavenger), diphenylene iodonium (an inhibitor of NADPH oxidases) and protonophore carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (a protonophore and an uncoupler of mitochondrial oxidative phosphorylation) inhibited sLNT-induced H2O2 generation and cell death, suggesting that ROS generation linked, at least partly, to a mitochondrial dysfunction and caspase-like activation. This conclusion was further confirmed by double-stained cells with the mitochondria-specific marker MitoTracker RedCMXRos and the ROS probe H2DCFDA. Moreover, the sLNT-induced PCD of BY-2 cells required cellular metabolism as up-regulation of the AOX family gene transcripts and induction of the SA biosynthesis, the TCA cycle, and miETC related genes were observed. It is concluded that mitochondria play an essential role in the signaling pathway of sLNT-induced ROS generation, which possibly provided new insight into the sLNT-mediated antiviral response, including PCD.

  11. Construction of selenium nanoparticles/β-glucan composites for enhancement of the antitumor activity.

    PubMed

    Jia, Xuewei; Liu, Qingye; Zou, Siwei; Xu, Xiaojuan; Zhang, Lina

    2015-03-06

    We report on a green procedure for the stabilization of selenium nanoparticles (SeNPs) by a naturally occurring β-glucan with triple helical conformation known as Lentinan (t-LNT) in water after denaturing into single chains (s-LNT) at 140 °C. The results demonstrated that the s-LNT can interact with SeNPs through Se-O-H interaction. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectra, UV/vis, X-ray diffraction (XRD) and dynamic light scattering (DLS) showed that s-LNT coated SeNPs to form a stable nano-composite Se/s-LNT, leading to good dispersion of SeNPs. Especially, the as-prepared Se/s-LNT composite in the solution could remain homogeneous and translucent for 30 days without any precipitates. Different size distribution of SeNPs was prepared by simply controlling the concentrations of selenite sodium and the corresponding reducing agent ascorbic acid. The size effect of SeNPs on anti-tumor activity was revealed that the SeNPs with more evenly particle size distribution show the higher anticancer activity.

  12. Prediction of drug terminal half-life and terminal volume of distribution after intravenous dosing based on drug clearance, steady-state volume of distribution, and physiological parameters of the body.

    PubMed

    Berezhkovskiy, Leonid M

    2013-02-01

    The steady state, V(ss), terminal volume of distribution, V(β), and the terminal half-life, t(1/2), are commonly obtained from the drug plasma concentration-time profile, C(p)(t), following intravenous dosing. Unlike V(ss) that can be calculated based on the physicochemical properties of drugs considering the equilibrium partitioning between plasma and organ tissues, t(1/2) and V(β) cannot be calculated that way because they depend on the rates of drug transfer between blood and tissues. Considering the physiological pharmacokinetic model pertinent to the terminal phase of drug elimination, a novel equation that calculates t(1/2) (and consequently V(β)) was derived. It turns out that V(ss), the total body clearance, Cl, equilibrium blood-plasma concentration ratio, r; and the physiological parameters of the body such as cardiac output, and blood and tissue volumes are sufficient for determination of terminal kinetics. Calculation of t(1/2) by the obtained equation appears to be in good agreement with the experimentally observed vales of this parameter in pharmacokinetic studies in rat, monkey, dog, and human. The equation for the determination of the pre-exponent of the terminal phase of C(p)(t) is also found. The obtained equation allows to predict t(1/2) in human assuming that V(ss) and Cl were either obtained by allometric scaling or, respectively, calculated in silico or based on in vitro drug stability measurements. For compounds that have high clearance, the derived equation may be applied to calculate r just using the routine data on Cl, V(ss), and t(1/2), rather than doing the in vitro assay to measure this parameter.

  13. [Tremendous Human, Social, and Economic Losses Caused by Obstinate Application of the Failed Linear No-threshold Model].

    PubMed

    Sutou, Shizuyo

    2015-01-01

    The linear no-threshold model (LNT) was recommended in 1956, with abandonment of the traditional threshold dose-response for genetic risk assessment. Adoption of LNT by the International Commission on Radiological Protection (ICRP) became the standard for radiation regulation worldwide. The ICRP recommends a dose limit of 1 mSv/year for the public, which is too low and which terrorizes innocent people. Indeed, LNT arose mainly from the lifespan survivor study (LSS) of atomic bomb survivors. The LSS, which asserts linear dose-response and no threshold, is challenged mainly on three points. 1) Radiation doses were underestimated by half because of disregard for major residual radiation, resulting in cancer risk overestimation. 2) The dose and dose-rate effectiveness factor (DDREF) of 2 is used, but the actual DDREF is estimated as 16, resulting in cancer risk overestimation by several times. 3) Adaptive response (hormesis) is observed in leukemia and solid cancer cases, consistently contradicting the linearity of LNT. Drastic reduction of cancer risk moves the dose-response curve close to the control line, allowing the setting of a threshold. Living organisms have been evolving for 3.8 billion years under radiation exposure, naturally acquiring various defense mechanisms such as DNA repair mechanisms, apoptosis, and immune response. The failure of LNT lies in the neglect of carcinogenesis and these biological mechanisms. Obstinate application of LNT continues to cause tremendous human, social, and economic losses. The 60-year-old LNT must be rejected to establish a new scientific knowledge-based system.

  14. Linear-no-threshold is a radiation-protection standard rather than a mechanistic effect model.

    PubMed

    Breckow, Joachim

    2006-03-01

    The linear-no-threshold (LNT) controversy covers much more than the mere discussion whether or not "the LNT hypothesis is valid". It is shown that one cannot expect to find only one or even the only one dose-effect relationship. Each element within the biological reaction chain that is affected by ionizing radiation contributes in a specific way to the final biological endpoint of interest. The resulting dose-response relationship represents the superposition of all these effects. Till now there is neither a closed and clear picture of the entirety of radiation action for doses below some 10 mSv, nor does clear epidemiological evidence exist for an increase of risk for stochastic effects, in this dose range. On the other hand, radiation protection demands for quantitative risk estimates as well as for practicable dose concepts. In this respect, the LNT concept is preferred against any alternative concept. However, the LNT concept does not necessarily mean that the mechanism of cancer induction is intrinsically linear. It could hold even if the underlying multi-step mechanisms act in a non-linear way. In this case it would express a certain "attenuation" of non-linearities. Favouring LNT against threshold-, hyper-, or sub-linear models for radiation-protection purposes on the one hand, but preferring one of these models (e.g. for a specific effect) because of biological considerations for scientific purposes on the other hand, does not mean a contradiction.

  15. Structural and mechanical properties of lanthanide doped La1/3Nb0.8Ta0.2O3 thin films prepared by sol-gel method

    NASA Astrophysics Data System (ADS)

    Brunckova, Helena; Medvecky, Lubomir; Kovalcikova, Alexandra; Fides, Martin; Mudra, Erika; Durisin, Juraj; Skvarla, Jiri; Kanuchova, Maria

    2017-04-01

    Transparent Eu and Nd doped lanthanum niobate tantalate La1/3Nb0.8Ta0.2O3 (LNT) thin films (˜150 nm) were prepared by sol-gel/spin-coating process on Pt/SiO2/Si substrates and annealing at 1100 °C. The x-ray diffraction analysis of films confirmed formation of the perovskite La1/3NbO3 and La1/3TaO3 phases with traces of pyrochlore LaNbO4. Eu and Nd doped LNT films were smoother with roughness 17.1 and 25.4 nm in comparison with LNT (43.3 nm). In all films was observed heterogeneous microstructure with the perovskite spherical and pyrochlore needle-like particles. The mechanical properties of films were characterized for the first time by conventional and continuous stiffness (CSM) nanoindentation. The Eu and Nd doped LNT film modulus (E) and hardness (H) were higher than LNT (˜99.8 and 4.4 GPa) determined by conventional nanoindentation. It was measured the significant effect of substrate on properties of Eu or Nd films (H ˜ 5.9 or 4.9 GPa and E ˜ 107.3 or 104.1 GPa) by CSM nanoindentation.

  16. Regulatory Initiatives for Control and Release of Technologically Enhanced Naturally-Occurring Radioactive Materials

    SciTech Connect

    Egidi, P.V.

    1999-03-02

    Current drafts of proposed standards and suggested State regulations for control and release of technologically-enhanced naturally-occurring radioactive material (TENORM), and standards for release of volumetrically-contaminated material in the US are reviewed. These are compared to the recommendations of the International Atomic Energy Association (IAEA) Safety Series and the European Commission (EC) proposals. Past regulatory efforts with respect to TENORM in the US dealt primarily with oil-field related wastes. Currently, nine states (AK, GA, LA, MS, NM, OH, OR SC, TX) have specific regulations pertaining to TENORM, mostly based on uranium mill tailings cleanup criteria. The new US proposals are dose- or risk-based, as are the IAEA and EC recommendations, and are grounded in the linear no threshold hypothesis (LNT). TENORM wastes involve extremely large volumes, particularly scrap metal and mine wastes. Costs to control and dispose of these wastes can be considerable. The current debate over the validity of LNT at low doses and low dose rates is particularly germane to this discussion. Most standards setting organizations and regulatory agencies base their recommendations on the LNT. The US Environmental Protection Agency has released a draft Federal Guidance Report that recommends calculating health risks from low-level exposure to radionuclides based on the LNT. However, some scientific and professional organizations are openly questioning the validity of LNT and its basis for regulations, practices, and costs to society in general. It is not clear at this time how a non-linear regulatory scheme would be implemented.

  17. Survey of cryogenic semiconductor devices

    SciTech Connect

    Talarico, L.J.; McKeever, J.W.

    1996-04-01

    Improved reliability and electronic performance can be achieved in a system operated at cryogenic temperatures because of the reduction in mechanical insult and in disruptive effects of thermal energy on electronic devices. Continuing discoveries of new superconductors with ever increasing values of T{sub c} above that of liquid nitrogen temperature (LNT) have provided incentive for developing semiconductor electronic systems that may also operate in the superconductor`s liquid nitrogen bath. Because of the interest in high-temperature superconductor (HTS) devices, liquid nitrogen is the cryogen of choice and LNT is the temperature on which this review is focused. The purpose of this survey is to locate and assemble published information comparing the room temperature (298 K), performance of commercially available conventional and hybrid semiconductor device with their performance at LNT (77K), to help establish their candidacy as cryogenic electronic devices specifically for use at LNT. The approach to gathering information for this survey included the following activities. Periodicals and proceedings were searched for information on the behavior of semiconductor devices at LNT. Telephone calls were made to representatives of semiconductor industries, to semiconductor subcontractors, to university faculty members prominent for their research in the area of cryogenic semiconductors, and to representatives of the National Aeronautics and Space Administration (NASA) and NASA subcontractors. The sources and contacts are listed with their responses in the introduction, and a list of references appears at the end of the survey.

  18. Kinetic and Performance Studies of the Regeneration Phase of Model Pt/Ba/Rh NOx Traps for Design and Optimization

    SciTech Connect

    Michael Harold; Vemuri Balakotaiah

    2010-05-31

    In this project a combined experimental and theoretical approach was taken to advance our understanding of lean NOx trap (LNT) technology. Fundamental kinetics studies were carried out of model LNT catalysts containing variable loadings of precious metals (Pt, Rh), and storage components (BaO, CeO{sub 2}). The Temporal Analysis of Products (TAP) reactor provided transient data under well-characterized conditions for both powder and monolith catalysts, enabling the identification of key reaction pathways and estimation of the corresponding kinetic parameters. The performance of model NOx storage and reduction (NSR) monolith catalysts were evaluated in a bench scale NOx trap using synthetic exhaust, with attention placed on the effect of the pulse timing and composition on the instantaneous and cycle-averaged product distributions. From these experiments we formulated a global model that predicts the main spatio-temporal features of the LNT and a mechanistic-based microkinetic models that incorporates a detailed understanding of the chemistry and predicts more detailed selectivity features of the LNT. The NOx trap models were used to determine its ability to simulate bench-scale data and ultimately to evaluate alternative LNT designs and operating strategies. The four-year project led to the training of several doctoral students and the dissemination of the findings as 47 presentations in conferences, catalysis societies, and academic departments as well 23 manuscripts in peer-reviewed journals. A condensed review of NOx storage and reduction was published in an encyclopedia of technology.

  19. Experimental Assessment of NOx Emissions from 73 Euro 6 Diesel Passenger Cars.

    PubMed

    Yang, Liuhanzi; Franco, Vicente; Mock, Peter; Kolke, Reinhard; Zhang, Shaojun; Wu, Ye; German, John

    2015-12-15

    Controlling nitrogen oxides (NOx) emissions from diesel passenger cars during real-world driving is one of the major technical challenges facing diesel auto manufacturers. Three main technologies are available for this purpose: exhaust gas recirculation (EGR), lean-burn NOx traps (LNT), and selective catalytic reduction (SCR). Seventy-three Euro 6 diesel passenger cars (8 EGR only, 40 LNT, and 25 SCR) were tested on a chassis dynamometer over both the European type-approval cycle (NEDC, cold engine start) and the more realistic Worldwide harmonized light-duty test cycle (WLTC version 2.0, hot start) between 2012 and 2015. Most vehicles met the legislative limit of 0.08 g/km of NOx over NEDC (average emission factors by technology: EGR-only 0.07 g/km, LNT 0.04 g/km, and SCR 0.05 g/km), but the average emission factors rose dramatically over WLTC (EGR-only 0.17 g/km, LNT 0.21 g/km, and SCR 0.13 g/km). Five LNT-equipped vehicles exhibited very poor performance over the WLTC, emitting 7-15 times the regulated limit. These results illustrate how diesel NOx emissions are not properly controlled under the current, NEDC-based homologation framework. The upcoming real-driving emissions (RDE) regulation, which mandates an additional on-road emissions test for EU type approvals, could be a step in the right direction to address this problem.

  20. Liquid Nitrogen Temperature Operation of a Switching Power Converter

    NASA Technical Reports Server (NTRS)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

  1. CRADA Final Report for CRADA Number ORNL00-0605: Advanced Engine/Aftertreatment System R&D

    SciTech Connect

    Pihl, Josh A; West, Brian H; Toops, Todd J; Adelman, Brad; Derybowski, Edward

    2011-10-01

    Navistar and ORNL established this CRADA to develop diesel engine aftertreatment configurations and control strategies that could meet emissions regulations while maintaining or improving vehicle efficiency. The early years of the project focused on reducing the fuel penalty associated with lean NOx trap (LNT), also known as NOx adsorber catalyst regeneration and desulfation. While Navistar pursued engine-based (in-cylinder) approaches to LNT regeneration, complementary experiments at ORNL focused on in-exhaust fuel injection. ORNL developed a PC-based controller for transient electronic control of EGR valve position, intake throttle position, and actuation of fuel injectors in the exhaust system of a Navistar engine installed at Oak Ridge. Aftertreatment systems consisting of different diesel oxidation catalysts (DOCs) in conjunction with a diesel particle filter and LNT were evaluated under quasi-steady-state conditions. Hydrocarbon (HC) species were measured at multiple locations in the exhaust system with Gas chromatograph mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) spectroscopy. Under full-load, rated speed conditions, injection of fuel upstream of the DOC reduced the fuel penalty for a given level of NOx reduction by 10-20%. GC-MS showed that fuel compounds were 'cracked' into smaller hydrocarbon species over the DOC, particularly light alkenes. GC-MS analysis of HC species entering and exiting the LNT showed high utilization of light alkenes, followed by mono-aromatics; branched alkanes passed through the LNT largely unreacted. Follow-on experiments at a 'road load' condition were conducted, revealing that the NOx reduction was better without the DOC at lower temperatures. The improved performance was attributed to the large swings in the NOx adsorber core temperature. Split-injection experiments were conducted with ultra-low sulfur diesel fuel and three pure HC compounds: 1-pentene, toluene, and iso-octane. The pure compound experiments

  2. Atomic bomb health benefits.

    PubMed

    Luckey, T D

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation, leukemia and solid tissue cancer mortality rates, and increased average lifespan. Each study exhibits a threshold that repudiates the LNT dogma. The average threshold for acute exposures to atomic bombs is about 100 cSv. Conclusions from these studies of atomic bomb survivors are: One burst of low dose irradiation elicits a lifetime of improved health.Improved health from low dose irradiation negates the LNT paradigm.Effective triage should include radiation hormesis for survivor treatment.

  3. Atomic Bomb Health Benefits

    PubMed Central

    Luckey, T. D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation, leukemia and solid tissue cancer mortality rates, and increased average lifespan. Each study exhibits a threshold that repudiates the LNT dogma. The average threshold for acute exposures to atomic bombs is about 100 cSv. Conclusions from these studies of atomic bomb survivors are: One burst of low dose irradiation elicits a lifetime of improved health.Improved health from low dose irradiation negates the LNT paradigm.Effective triage should include radiation hormesis for survivor treatment. PMID:19088902

  4. Time to Reject the Linear-No Threshold Hypothesis and Accept Thresholds and Hormesis: A Petition to the U.S. Nuclear Regulatory Commission.

    PubMed

    Marcus, Carol S

    2015-07-01

    On February 9, 2015, I submitted a petition to the U.S. Nuclear Regulatory Commission (NRC) to reject the linear-no threshold (LNT) hypothesis and ALARA as the bases for radiation safety regulation in the United States, using instead threshold and hormesis evidence. In this article, I will briefly review the history of LNT and its use by regulators, the lack of evidence supporting LNT, and the large body of evidence supporting thresholds and hormesis. Physician acceptance of cancer risk from low dose radiation based upon federal regulatory claims is unfortunate and needs to be reevaluated. This is dangerous to patients and impedes good medical care. A link to my petition is available: http://radiationeffects.org/wp-content/uploads/2015/03/Hormesis-Petition-to-NRC-02-09-15.pdf, and support by individual physicians once the public comment period begins would be extremely important.

  5. Lipoproteins of slow-growing Mycobacteria carry three fatty acids and are N-acylated by apolipoprotein N-acyltransferase BCG_2070c.

    PubMed

    Brülle, Juliane K; Tschumi, Andreas; Sander, Peter

    2013-10-05

    Lipoproteins are virulence factors of Mycobacterium tuberculosis. Bacterial lipoproteins are modified by the consecutive action of preprolipoprotein diacylglyceryl transferase (Lgt), prolipoprotein signal peptidase (LspA) and apolipoprotein N- acyltransferase (Lnt) leading to the formation of mature triacylated lipoproteins. Lnt homologues are found in Gram-negative and high GC-rich Gram-positive, but not in low GC-rich Gram-positive bacteria, although N-acylation is observed. In fast-growing Mycobacterium smegmatis, the molecular structure of the lipid modification of lipoproteins was resolved recently as a diacylglyceryl residue carrying ester-bound palmitic acid and ester-bound tuberculostearic acid and an additional amide-bound palmitic acid. We exploit the vaccine strain Mycobacterium bovis BCG as model organism to investigate lipoprotein modifications in slow-growing mycobacteria. Using Escherichia coli Lnt as a query in BLASTp search, we identified BCG_2070c and BCG_2279c as putative lnt genes in M. bovis BCG. Lipoproteins LprF, LpqH, LpqL and LppX were expressed in M. bovis BCG and BCG_2070c lnt knock-out mutant and lipid modifications were analyzed at molecular level by matrix-assisted laser desorption ionization time-of-flight/time-of-flight analysis. Lipoprotein N-acylation was observed in wildtype but not in BCG_2070c mutants. Lipoprotein N- acylation with palmitoyl and tuberculostearyl residues was observed. Lipoproteins are triacylated in slow-growing mycobacteria. BCG_2070c encodes a functional Lnt in M. bovis BCG. We identified mycobacteria-specific tuberculostearic acid as further substrate for N-acylation in slow-growing mycobacteria.

  6. Lipoproteins of slow-growing Mycobacteria carry three fatty acids and are N-acylated by Apolipoprotein N-Acyltransferase BCG_2070c

    PubMed Central

    2013-01-01

    Background Lipoproteins are virulence factors of Mycobacterium tuberculosis. Bacterial lipoproteins are modified by the consecutive action of preprolipoprotein diacylglyceryl transferase (Lgt), prolipoprotein signal peptidase (LspA) and apolipoprotein N- acyltransferase (Lnt) leading to the formation of mature triacylated lipoproteins. Lnt homologues are found in Gram-negative and high GC-rich Gram-positive, but not in low GC-rich Gram-positive bacteria, although N-acylation is observed. In fast-growing Mycobacterium smegmatis, the molecular structure of the lipid modification of lipoproteins was resolved recently as a diacylglyceryl residue carrying ester-bound palmitic acid and ester-bound tuberculostearic acid and an additional amide-bound palmitic acid. Results We exploit the vaccine strain Mycobacterium bovis BCG as model organism to investigate lipoprotein modifications in slow-growing mycobacteria. Using Escherichia coli Lnt as a query in BLASTp search, we identified BCG_2070c and BCG_2279c as putative lnt genes in M. bovis BCG. Lipoproteins LprF, LpqH, LpqL and LppX were expressed in M. bovis BCG and BCG_2070c lnt knock-out mutant and lipid modifications were analyzed at molecular level by matrix-assisted laser desorption ionization time-of-flight/time-of-flight analysis. Lipoprotein N-acylation was observed in wildtype but not in BCG_2070c mutants. Lipoprotein N- acylation with palmitoyl and tuberculostearyl residues was observed. Conclusions Lipoproteins are triacylated in slow-growing mycobacteria. BCG_2070c encodes a functional Lnt in M. bovis BCG. We identified mycobacteria-specific tuberculostearic acid as further substrate for N-acylation in slow-growing mycobacteria. PMID:24093492

  7. A Kilogauss-scale, High-vacuum Toroidal Electron Plasma Experiment

    SciTech Connect

    Marler, J. P.; Stoneking, M. R.

    2006-10-18

    We describe in detail the newly constructed Lawrence Non-Neutral Torus (LNT) II apparatus. The LNT II features an improved toroidal magnetic field magnitude ({approx} 1 kG) and base vacuum pressure (<10-9 Torr). A segmented Au-plated Al electrode shell contributes to the reduction in field asymmetries and enables enhanced diagnostic capabilities. Additionally, the electron source is located on a retractable bellows for study of confinement dynamics in a complete torus. Conservative estimates suggest confinement times on the order of 1 second are achievable which would represent almost two orders of magnitude improvement over measurements made with the previous apparatus.

  8. Plant Physiological, Morphological and Yield-Related Responses to Night Temperature Changes across Different Species and Plant Functional Types

    PubMed Central

    Jing, Panpan; Wang, Dan; Zhu, Chunwu; Chen, Jiquan

    2016-01-01

    Land surface temperature over the past decades has shown a faster warming trend during the night than during the day. Extremely low night temperatures have occurred frequently due to the influence of land-sea thermal difference, topography and climate change. This asymmetric night temperature change is expected to affect plant ecophysiology and growth, as the plant carbon consumption processes could be affected more than the assimilation processes because photosynthesis in most plants occurs during the daytime whereas plant respiration occurs throughout the day. The effects of high night temperature (HNT) and low night temperature (LNT) on plant ecophysiological and growing processes and how the effects vary among different plant functional types (PFTs) have not been analyzed extensively. In this meta-analysis, we examined the effect of HNT and LNT on plant physiology and growth across different PFTs and experimental settings. Plant species were grouped according to their photosynthetic pathways (C3, C4, and CAM), growth forms (herbaceous, woody), and economic purposes (crop, non-crop). We found that HNT and LNT both had a negative effect on plant yield, but the effect of HNT on plant yield was primarily related to a reduction in biomass allocation to reproduction organs and the effect of LNT on plant yield was more related to a negative effect on total biomass. Leaf growth was stimulated at HNT and suppressed at LNT. HNT accelerated plants ecophysiological processes, including photosynthesis and dark respiration, while LNT slowed these processes. Overall, the results showed that the effects of night temperature on plant physiology and growth varied between HNT and LNT, among the response variables and PFTs, and depended on the magnitude of temperature change and experimental design. These findings suggest complexities and challenges in seeking general patterns of terrestrial plant growth in HNT and LNT. The PFT specific responses of plants are critical for

  9. Plant Physiological, Morphological and Yield-Related Responses to Night Temperature Changes across Different Species and Plant Functional Types.

    PubMed

    Jing, Panpan; Wang, Dan; Zhu, Chunwu; Chen, Jiquan

    2016-01-01

    Land surface temperature over the past decades has shown a faster warming trend during the night than during the day. Extremely low night temperatures have occurred frequently due to the influence of land-sea thermal difference, topography and climate change. This asymmetric night temperature change is expected to affect plant ecophysiology and growth, as the plant carbon consumption processes could be affected more than the assimilation processes because photosynthesis in most plants occurs during the daytime whereas plant respiration occurs throughout the day. The effects of high night temperature (HNT) and low night temperature (LNT) on plant ecophysiological and growing processes and how the effects vary among different plant functional types (PFTs) have not been analyzed extensively. In this meta-analysis, we examined the effect of HNT and LNT on plant physiology and growth across different PFTs and experimental settings. Plant species were grouped according to their photosynthetic pathways (C3, C4, and CAM), growth forms (herbaceous, woody), and economic purposes (crop, non-crop). We found that HNT and LNT both had a negative effect on plant yield, but the effect of HNT on plant yield was primarily related to a reduction in biomass allocation to reproduction organs and the effect of LNT on plant yield was more related to a negative effect on total biomass. Leaf growth was stimulated at HNT and suppressed at LNT. HNT accelerated plants ecophysiological processes, including photosynthesis and dark respiration, while LNT slowed these processes. Overall, the results showed that the effects of night temperature on plant physiology and growth varied between HNT and LNT, among the response variables and PFTs, and depended on the magnitude of temperature change and experimental design. These findings suggest complexities and challenges in seeking general patterns of terrestrial plant growth in HNT and LNT. The PFT specific responses of plants are critical for

  10. Radiation leukaemogenesis at low doses DE-FG02-05 ER 63947 Final Technical Report 15 May 2005; 14 May 2010

    SciTech Connect

    Bouffler, Simon

    2010-07-28

    This report provides a complete summary of the work undertaken and results obtained under US Department of Energy grant DF-FG02-05 ER 63947, Radiation leukaemogenesis at low doses. There is ample epidemiological evidence indicating that ionizing radiation is carcinogenic in the higher dose range. This evidence, however, weakens and carries increasing uncertainties at doses below 100-200 mSv. At these low dose levels the form of the dose-response curve for radiation-induced cancer cannot be determined reliably or directly from studies of human populations. Therefore animal, cellular and other experimental systems must be employed to provide supporting evidence on which to base judgements of risk at low doses. Currently in radiological protection a linear non-threshold (LNT) extrapolation of risk estimates derived from human epidemiological studies is used to estimate risks in the dose range of interest for protection purposes. Myeloid leukaemias feature prominently among the cancers associated with human exposures to ionising radiation (eg UNSCEAR 2006; IARC 2000). Good animal models of radiation-induced acute myeloid leukaemia (AML) are available including strains such as CBA, RFM and SJL (eg Major and Mole 1978; Ullrich et al 1976; Resnitzky et al 1985). Early mechanistic studies using cytogenetic methods in these mouse models established that the majority of radiation-induced AMLs carried substantial interstitial deletions in one copy of chromosome (chr) 2 (eg Hayata et al 1983; Trakhtenbrot et al 1988; Breckon et al 1991; Rithidech et al 1993; Bouffler et al 1996). Chr2 aberrations are known to occur in bone marrow cells as early as 24 hours after in vivo irradiation (Bouffler et al 1997). Subsequent molecular mapping studies defined a distinct region of chr2 that is commonly lost in AMLs (Clark et al 1996; Silver et al 1999). Further, more detailed, analysis identified point mutations at a specific region of the Sfpi1/PU.1 haemopoietic transcription factor gene

  11. TU-C-18A-01: Models of Risk From Low-Dose Radiation Exposures: What Does the Evidence Say?

    SciTech Connect

    Bushberg, J; Boreham, D; Ulsh, B

    2014-06-15

    At dose levels of (approximately) 500 mSv or more, increased cancer incidence and mortality have been clearly demonstrated. However, at the low doses of radiation used in medical imaging, the relationship between dose and cancer risk is not well established. As such, assumptions about the shape of the dose-response curve are made. These assumptions, or risk models, are used to estimate potential long term effects. Common models include 1) the linear non-threshold (LNT) model, 2) threshold models with either a linear or curvilinear dose response above the threshold, and 3) a hormetic model, where the risk is initially decreased below background levels before increasing. The choice of model used when making radiation risk or protection calculations and decisions can have significant implications on public policy and health care decisions. However, the ongoing debate about which risk model best describes the dose-response relationship at low doses of radiation makes informed decision making difficult. This symposium will review the two fundamental approaches to determining the risk associated with low doses of ionizing radiation, namely radiation epidemiology and radiation biology. The strengths and limitations of each approach will be reviewed, the results of recent studies presented, and the appropriateness of different risk models for various real world scenarios discussed. Examples of well-designed and poorly-designed studies will be provided to assist medical physicists in 1) critically evaluating publications in the field and 2) communicating accurate information to medical professionals, patients, and members of the general public. Equipped with the best information that radiation epidemiology and radiation biology can currently provide, and an understanding of the limitations of such information, individuals and organizations will be able to make more informed decisions regarding questions such as 1) how much shielding to install at medical facilities, 2) at

  12. Structure-based rationale for differential recognition of lacto- and neolacto- series glycosphingolipids by the N-terminal domain of human galectin-8

    PubMed Central

    Bohari, Mohammad H.; Yu, Xing; Zick, Yehiel; Blanchard, Helen

    2016-01-01

    Glycosphingolipids are ubiquitous cell surface molecules undertaking fundamental cellular processes. Lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT) are the representative core structures for lacto- and neolacto-series glycosphingolipids. These glycolipids are the carriers to the blood group antigen and human natural killer antigens mainly found on blood cells, and are also principal components in human milk, contributing to infant health. The β-galactoside recognising galectins mediate various cellular functions of these glycosphingolipids. We report crystallographic structures of the galectin-8 N-terminal domain (galectin-8N) in complex with LNT and LNnT. We reveal the first example in which the non-reducing end of LNT binds to the primary binding site of a galectin, and provide a structure-based rationale for the significant ten-fold difference in binding affinities of galectin-8N toward LNT compared to LNnT, such a magnitude of difference not being observed for any other galectin. In addition, the LNnT complex showed that the unique Arg59 has ability to adopt a new orientation, and comparison of glycerol- and lactose-bound galectin-8N structures reveals a minimum atomic framework for ligand recognition. Overall, these results enhance our understanding of glycosphingolipids interactions with galectin-8N, and highlight a structure-based rationale for its significantly different affinity for components of biologically relevant glycosphingolipids. PMID:28000747

  13. Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control

    SciTech Connect

    David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

    2006-04-01

    The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

  14. Nonmonotonic dose response curves (NMDRCs) are common after Estrogen or Androgen signaling pathway disruption. Fact or Falderal? ###SETAC

    EPA Science Inventory

    The shape of the dose response curve in the low dose region has been debated since the late 1940s. The debate originally focused on linear no threshold (LNT) vs threshold responses in the low dose range for cancer and noncancer related effects. Recently, claims have arisen tha...

  15. ENERGY EFFICIENT THERMAL MANAGEMENT FOR NATURAL GAS ENGINE AFTERTREATMENT VIA ACTIVE FLOW CONTROL

    SciTech Connect

    David K. Irick; Ke Nguyen

    2004-04-01

    The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

  16. Dose Response Data for Hormonally Active Chemicals: Estrogens, Antiandrogens and Androgens

    EPA Science Inventory

    The shape of the dose response curve in the low dose region has been debated since the late 1940s. The debate originally focused on linear no threshold (LNT) vs threshold responses in the low dose range for cancer and noncancer related effects. For noncancer effects the defaul...

  17. Investigation of the Dielectric Strength of Syntactic Foam at 77 K under DC Stress

    NASA Astrophysics Data System (ADS)

    Winkel, D.; Puffer, R.; Schnettler, A.

    2014-05-01

    Liquid nitrogen (LN2) based electrical insulation systems for superconducting equipment of electrical power distribution networks are state of the art. Since LN2 is a cryogenic liquid it has some disadvantages when used as insulation. This paper deals with syntactic foam as an alternative insulation system for superconducting apparatus. Syntactic foam is a composite material consisting of a polymeric matrix and embedded hollow microspheres with diameters of several 10 μp?. As hollow microspheres are gas-filled, using those as filling material features significant reductions of the relative permittivity and of the thermal contraction due to cooling the material to liquid nitrogen temperature (LNT, T = 77 K). In this study both an epoxy resin (ER) and an unsaturated polyester resin (UPR) serve as matrix material. The hollow microspheres used in this investigation are made of untreated and silanized glass. The results of measurements of the dielectric DC strength show, that the dielectric strength of all investigated syntactic foam compositions are significantly higher at LNT compared to ambient temperature (AT). Furthermore, the effect of a higher dielectric strength of syntactic foam with silanized glass spheres at ambient temperature vanishes at LNT. Hence, the dielectric strength at LNT is unaffected by silanization of glass microspheres.

  18. The debate on the use of linear no threshold for assessing the effects of low doses.

    PubMed

    Tubiana, M; Aurengo, A; Averbeck, D; Masse, R

    2006-09-01

    From December 2004 to July 2005, three reports on the effects of low doses of ionising radiation were released: ICRP (2004), the joint report of the French Academies of Science and Medicine (Tubiana et al 2005), and a report from the American Academy of Sciences (BEIR VII 2005). These reports quote the same recent articles on the biological effects of low doses, yet their conclusions diverge. The French report concludes that recent biological data show that the efficacy of defense mechanisms is modulated by dose and dose rate and that linear no threshold (LNT) is no longer plausible. The ICRP and the BEIR VII reports recognise that there are biologic arguments against LNT but feel that there are not sufficient biological proofs against it to change risk assessment methodology and subsequent regulatory policy based on LNT. They point out the remaining uncertainties and the lack of mechanistic explanations of phenomena such as low dose hyperlethality or the adaptive response. In this context, a critical analysis of the available data is necessary. The epidemiological data and the experimental data challenge the validity of the LNT hypothesis for assessing the carcinogenic effect of low doses, but do not allow its exclusion. Therefore, the main criteria for selecting the most reliable dose-effect relationship from a scientific point of view should be based on biological data. Their analysis should help one to understand the current controversy.

  19. Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control

    SciTech Connect

    David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

    2005-04-01

    The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

  20. Assessment of interbreeding and introgression of farm genes into a small Scottish Atlantic salmon Salmo salar stock: ad hoc samples - ad hoc results?

    PubMed

    Verspoor, E; Knox, D; Marshall, S

    2016-12-01

    An eclectic set of tissues and existing data, including purposely collected samples, spanning 1997-2006, was used in an ad hoc assessment of hybridization and introgression of farmed wild Atlantic salmon Salmo salar in the small Loch na Thull (LnT) catchment in north-west Scotland. The catchment is in an area of marine farm production and contains freshwater smolt rearing cages. The LnT S. salar stock was found to be genetically distinctive from stocks in neighbouring rivers and, despite regular reports of feral farm S. salar, there was no evidence of physical or genetic mixing. This cannot be completely ruled out, however, and low level mixing with other local wild stocks has been suggested. The LnT population appeared underpinned by relatively smaller effective number of breeders (Neb ) and showed relatively low levels of genetic diversity, consistent with a small effective population size. Small sample sizes, an incomplete farm baseline and the use of non-diagnostic molecular markers, constrain the power of the analysis but the findings strongly support the LnT catchment having a genetically distinct wild S. salar population little affected by interbreeding with feral farm escapes. © 2016 The Fisheries Society of the British Isles.

  1. Mechanistic Basis for Nonlinear Dose-Response Relationships for Low-Dose Radiation-Induced Stochastic Effects

    PubMed Central

    Scott, Bobby R.; Walker, Dale M.; Tesfaigzi, Yohannes; Schöllnberger, Helmut; Walker, Vernon

    2003-01-01

    The linear nonthreshold (LNT) model plays a central role in low-dose radiation risk assessment for humans. With the LNT model, any radiation exposure is assumed to increase one’s risk of cancer. Based on the LNT model, others have predicted tens of thousands of deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Here, we introduce a mechanism-based model for low-dose, radiation-induced, stochastic effects (genomic instability, apoptosis, mutations, neoplastic transformation) that leads to a LNT relationship between the risk for neoplastic transformation and dose only in special cases. It is shown that nonlinear dose-response relationships for risk of stochastic effects (problematic nonlethal mutations, neoplastic transformation) should be expected based on known biological mechanisms. Further, for low-dose, low-dose rate, low-LET radiation, large thresholds may exist for cancer induction. We summarize previously published data demonstrating large thresholds for cancer induction. We also provide evidence for low-dose-radiation-induced, protection (assumed via apoptosis) from neoplastic transformation. We speculate based on work of others (Chung 2002) that such protection may also be induced to operate on existing cancer cells and may be amplified by apoptosis-inducing agents such as dietary isothiocyanates. PMID:19330114

  2. US EPA, Pesticide Product Label, VULCAN FORMULA 72 ...

    EPA Pesticide Factsheets

    2011-04-14

    ... L H .... , ldl ,I-. t frltt'r. f: .... lnt •.• It ,nt. r ~.I: th" tlln , f 1m, ·tl,,' ,lf1 ,11';' 'Cltt ") t', n',L~t' ~'(t t 'Ct'~ t~, "tl;htf':t,! A't,,' l~ ,I'\\"!'I °'1 ~l:!"frt',lf, " ,. " f ,1( h ...

  3. NONMONOTONIC DOSE RESPONSE CURVES (NMDRCS) ARE COMMON AFTER ESTROGEN OR ANDROGEN SIGNALING PATHWAY DISRUPTION. FACT OR FALDERAL?

    EPA Science Inventory

    ABSTRACT BODY: The shape of the dose response curve in the low dose region has been debated since the 1940s, originally focusing on linear no threshold (LNT) versus threshold responses for cancer and noncancer effects. Recently, it has been claimed that endocrine disrupters (EDCs...

  4. Nonmonotonic Dose-Response Curves and Endocrine-Disrupting Chemicals: Fact or Falderal?**

    EPA Science Inventory

    Nonmonotonic Dose-Response Curves and Endocrine-Disrupting Chemicals: Fact or Falderal? The shape of the dose response curve in the low dose region has been debated since the 1940s, originally focusing on linear no threshold (LNT) versus threshold responses for cancer and noncanc...

  5. Dose Response Data for Hormonally Active Chemicals: Estrogens, Antiandrogens and Androgens

    EPA Science Inventory

    The shape of the dose response curve in the low dose region has been debated since the late 1940s. The debate originally focused on linear no threshold (LNT) vs threshold responses in the low dose range for cancer and noncancer related effects. For noncancer effects the defaul...

  6. Structure-based rationale for differential recognition of lacto- and neolacto- series glycosphingolipids by the N-terminal domain of human galectin-8

    NASA Astrophysics Data System (ADS)

    Bohari, Mohammad H.; Yu, Xing; Zick, Yehiel; Blanchard, Helen

    2016-12-01

    Glycosphingolipids are ubiquitous cell surface molecules undertaking fundamental cellular processes. Lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT) are the representative core structures for lacto- and neolacto-series glycosphingolipids. These glycolipids are the carriers to the blood group antigen and human natural killer antigens mainly found on blood cells, and are also principal components in human milk, contributing to infant health. The β-galactoside recognising galectins mediate various cellular functions of these glycosphingolipids. We report crystallographic structures of the galectin-8 N-terminal domain (galectin-8N) in complex with LNT and LNnT. We reveal the first example in which the non-reducing end of LNT binds to the primary binding site of a galectin, and provide a structure-based rationale for the significant ten-fold difference in binding affinities of galectin-8N toward LNT compared to LNnT, such a magnitude of difference not being observed for any other galectin. In addition, the LNnT complex showed that the unique Arg59 has ability to adopt a new orientation, and comparison of glycerol- and lactose-bound galectin-8N structures reveals a minimum atomic framework for ligand recognition. Overall, these results enhance our understanding of glycosphingolipids interactions with galectin-8N, and highlight a structure-based rationale for its significantly different affinity for components of biologically relevant glycosphingolipids.

  7. A Participative and Individualized Laboratory: A Strategy for Increasing Student Success in College-Level Math Courses

    ERIC Educational Resources Information Center

    Toro Clarke, Jose Antonio

    2016-01-01

    This research was carried out within a qualitative research paradigm. The objective was to observe, analyze and enrich pedagogical practice through the use of pedagogical learning strategies. The learning strategy was a participative and individualized lab carried out during a research project in a non-Traditional Laboratory (LnT). The primary aim…

  8. Nonmonotonic dose response curves (NMDRCs) are common after Estrogen or Androgen signaling pathway disruption. Fact or Falderal? ###SETAC

    EPA Science Inventory

    The shape of the dose response curve in the low dose region has been debated since the late 1940s. The debate originally focused on linear no threshold (LNT) vs threshold responses in the low dose range for cancer and noncancer related effects. Recently, claims have arisen tha...

  9. Synergies of PCCI-Type Combustion and Lean NOx Trap Catalysis for Diesel Engines

    SciTech Connect

    Parks, II, James E; Prikhodko, Vitaly Y; Kass, Michael D; Huff, Shean P

    2008-01-01

    It is widely recognized that future NOx and PM emission targets for diesel engines cannot be met solely via advanced combustion over the full engine drive cycle. Therefore some combination of advanced combustion methodology with an aftertreatment technology will be required. In this study, NOx reduction, fuel efficiency, and regeneration performance of lean NOx trap (LNT) were evaluated for four operating conditions. The combustion approaches included baseline engine operation with and without EGR, two exhaust enrichment methods (post injection and delayed injection), and one advanced combustion mode to enable high efficiency clean combustion (HECC). A 1.7 liter 4-cylinder diesel engine was operated under five conditions, which represent key interest points for light-duty diesel operation. At the low load setting the exhaust temperature was too low to enable LNT regeneration and oxidation; however, HECC (low NOx) was achievable. HECC was also reached under more moderate loads and the exhaust temperatures were high enough to enable even further NOx reductions by the LNT. At high loads HECC becomes difficult but the LNT performance improves and acceptable regeneration can be met with enrichment methodologies.

  10. SU (N ) Fermi liquid at finite temperature

    NASA Astrophysics Data System (ADS)

    Cheng, Chi-Ho; Yip, S.-K.

    2017-03-01

    We consider the thermodynamic potential Ω of an N component Fermi gas with a short-range interaction obeying SU (N ) symmetry. We analyze especially the nonanalytic part of Ω in the temperature T at low T . We examine the temperature range where one can observe this T4lnT contribution and discuss how it can be extracted experimentally.

  11. US EPA, Pesticide Product Label, SPECTRACIDE ...

    EPA Pesticide Factsheets

    2011-04-13

    ... Bro ..... o noq t icllnt.:-~t'-'d Jt-(l,]S arolll1(l basc- boor-I!; r • .... lndc}'''' il!l(j ti()!)r :r("lrn'-'~~ all (·r<.-lc~!-;, sl,.:'npitYl qllurt0rs ...

  12. Revisiting the gram-negative lipoprotein paradigm

    USDA-ARS?s Scientific Manuscript database

    The processing of lipoproteins (lpps) in Gram-negative bacteria is generally considered to be an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein n-acyltransferase. The mature lipoproteins are then sorted...

  13. NONMONOTONIC DOSE RESPONSE CURVES (NMDRCS) ARE COMMON AFTER ESTROGEN OR ANDROGEN SIGNALING PATHWAY DISRUPTION. FACT OR FALDERAL?

    EPA Science Inventory

    ABSTRACT BODY: The shape of the dose response curve in the low dose region has been debated since the 1940s, originally focusing on linear no threshold (LNT) versus threshold responses for cancer and noncancer effects. Recently, it has been claimed that endocrine disrupters (EDCs...

  14. Nonmonotonic Dose-Response Curves and Endocrine-Disrupting Chemicals: Fact or Falderal?**

    EPA Science Inventory

    Nonmonotonic Dose-Response Curves and Endocrine-Disrupting Chemicals: Fact or Falderal? The shape of the dose response curve in the low dose region has been debated since the 1940s, originally focusing on linear no threshold (LNT) versus threshold responses for cancer and noncanc...

  15. Dose Response Data for Hormonally Active Chemicals ...

    EPA Pesticide Factsheets

    The shape of the dose response curve in the low dose region has been debated since the late 1940s. The debate originally focused on linear no threshold (LNT) vs threshold responses in the low dose range for cancer and noncancer related effects. For noncancer effects the default assumption is that noncancer effects generally display threshold rather than LNT responses. More recently, claims have arisen that the chemicals, like endocrine disrupters (EDS), which act via high affinity, low capacity nuclear receptors, may display LNT or nonmonotonic low dose responses: responses that could be missed in multigenerational guideline toxicity testing. This presentation will discuss LNT, threshold and nonmonotonic dose response relationships from case studies of chemicals that disrupt reproductive development and function via the ER, AR and AhR pathways and will include in vitro and in vivo multigenerational data. The in vivo studies in this discussion include only robust, well designed, comprehensive studies that administered the chemical via a relevant route(s) of exposure over a broad dose response range, including low dose(s) in the microgram/kg/d range. The chemicals include ethinyl estradiol, estradiol, genistein, bisphenol a, trenbolone, finasteride, flutamide, phthalate esters and 2,3,7,8 TCDD. The objective is to critically evaluate the data from well done studies in this field to address concerns that current multigenerational reproductive test gui

  16. A Participative and Individualized Laboratory: A Strategy for Increasing Student Success in College-Level Math Courses

    ERIC Educational Resources Information Center

    Toro Clarke, Jose Antonio

    2016-01-01

    This research was carried out within a qualitative research paradigm. The objective was to observe, analyze and enrich pedagogical practice through the use of pedagogical learning strategies. The learning strategy was a participative and individualized lab carried out during a research project in a non-Traditional Laboratory (LnT). The primary aim…

  17. Practical Approaches for Teaching Leave No Trace.

    ERIC Educational Resources Information Center

    Attarian, Aram

    As participation in outdoor recreation grows, natural resources suffer a variety of environmental and social impacts. A minimum-impact back country educational program first developed during the 1970s, Leave No Trace (LNT), has been revitalized by the National Outdoor Leadership School, six federal agencies, and members of the outdoor products…

  18. Emissions from premixed charge compression ignition (PCCI) combustion and affect on emission control devices

    SciTech Connect

    Parks, II, James E; Kass, Michael D; Huff, Shean P; Barone, Teresa L; Lewis Sr, Samuel Arthur; Prikhodko, Vitaly Y; Storey, John Morse

    2010-01-01

    A light-duty diesel engine has been operated in advanced combustion modes known generally as premixed charge compression ignition (PCCI). The emissions have been characterized for several load and speed combinations. Fewer NO{sub x} and particulate matter (PM) emissions are produced by PCCI, but higher CO and hydrocarbon (HC) emissions result. In addition, the nature of the PM differs from conventional combustion; the PM is smaller and has a much higher soluble organic fraction (SOF) content (68% vs. 30% for conventional combustion). Three catalyst technologies were studied to determine the affects of HECC on catalyst performance; the technologies were a lean NO{sub x} trap (LNT), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF). The LNT benefited greatly from the reduced NO{sub x} emissions associated with PCCI. NO{sub x} capacity requirements are reduced as well as overall tailpipe NO{sub x} levels particularly at low load and temperature conditions where regeneration of the LNT is difficult. The DOC performance requirements for PCCI are more stringent due to the higher CO and HC emissions; however, the DOC was effective at controlling the higher CO and HC emissions at conditions above the light-off temperature. Below light-off, CO and HC emissions are problematic. The study of DPF technology focused on the fuel penalties associated with DPF regeneration or 'desoot' due to the different PM loading rates from PCCI vs. conventional combustion. Less frequent desoot events were required from the lower PM from PCCI and, when used in conjunction with an LNT, the lower PM from less frequent LNT regeneration. The lower desoot frequency leads a {approx}3% fuel penalty for a mixture of PCCI and conventional loads vs. {approx}4% for conventional only combustion.

  19. Sulfur impact on NOx storage, oxygen storage and ammonia breakthrough during cyclic lean/rich operation of a commercial lean NOx trap

    SciTech Connect

    Choi, Jae-Soon; Partridge Jr, William P; Daw, C Stuart

    2007-01-01

    The objective of the present study was to develop an improved understanding of how sulfur affects the spatiotemporal distribution of reactions and temperature inside a monolithic lean NO{sub x} trap (LNT). These spatiotemporal distributions are believed to be major factors in LNT function, and thus, we expect that a better understanding of these phenomena can benefit the design and operation of commercial LNTs. In our study, we experimentally evaluated a commercial LNT monolith installed in a bench-flow reactor with simulated engine exhaust. The reactor feed gas composition was cycled to simulate fast lean/rich LNT operation at 325 C, and spatiotemporal species and temperature profiles were monitored along the LNT axis at different sulfur loadings. Reactor outlet NO{sub x}, NO, N{sub 2}O, and NH{sub 3} were also measured. Sulfur tended to accumulate in a plug-like fashion in the reactor and progressively inhibited NO{sub x} storage capacity along the axis. The NO{sub x} storage/reduction (NSR) reactions occurred over a relatively short portion of the reactor (NSR zone) under the conditions used in this study, and thus, net NO{sub x} conversion was only significantly reduced at high sulfur loading. Oxygen storage capacity (OSC) was poisoned by sulfur also in a progressive manner but to a lesser extent than the NO{sub x} storage capacity. Global selectivity for N{sub 2}O remained low at all sulfur loadings, but NH{sub 3} selectivity increased significantly with sulfur loading. We conjecture that NH{sub 3} breakthrough increased because of decreasing oxidation of NH{sub 3}, slipping from the NSR zone, by downstream stored oxygen. The NSR and oxygen storage/reduction (OSR) generated distinctive exotherms during the rich phase and at the rich/lean transition. Exotherm locations shifted downstream with sulfur accumulation in a manner that was consistent with the progressive poisoning of NSR and OSR sites.

  20. Revisiting the Gram-negative lipoprotein paradigm.

    PubMed

    LoVullo, Eric D; Wright, Lori F; Isabella, Vincent; Huntley, Jason F; Pavelka, Martin S

    2015-05-01

    The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Effects of Rapid High Temperature Cyclic Aging on a Fully-Formulated Lean NOx Trap Catalyst

    SciTech Connect

    Ottinger, Nathan; Nguyen, Ke; Bunting, Bruce G; Toops, Todd J; Howe, Janet E

    2009-01-01

    In this study, high-temperature deactivation of a fully-formulated lean NOx trap (LNT) is investigated with an accelerated aging protocol where accelerated aging is accomplished by rapid temperature cycling and by higher temperatures. Thermal aging is carried out in a bench-flow reactor at nominal temperatures of 700, 800, 900, and 1000 C using an aging cycle consisting of a 130s lean-phase and a 50s rich-phase. After a prescribed number of lean/rich aging cycles, the NOx conversion of the aged LNT is evaluated at 200, 300, and 400 C. The NOx performance is obtained at a GHSV of 30,000 h-1 using an evaluation cycle consisting of a 60s lean-phase and 5s rich-phase. The effects of aging on the LNT washcoat are determined with EPMA, XRD, STEM/EDS, and BET. Aging at 700 and 800 C has a minimal effect on LNT performance and material properties. However, at aging temperatures of 900 and 1000 C reduction in surface area and sintering of PGM particles are observed and result in a drastic reduction in NOx conversion. Additionally, after aging at 900 C and 1000 C the NOx storage medium, BaCO3, is no longer visible in the XRD patterns, even though a Ba-phase identified by EPMA still exists in all aged samples. BaAl2O4 is not identified at any aging temperatures; possibly due to stabilization effects provided by washcoat additives present in this particular LNT.

  2. Revisiting the Gram-Negative Lipoprotein Paradigm

    PubMed Central

    LoVullo, Eric D.; Wright, Lori F.; Isabella, Vincent; Huntley, Jason F.

    2015-01-01

    ABSTRACT The processing of lipoproteins (Lpps) in Gram-negative bacteria is generally considered an essential pathway. Mature lipoproteins in these bacteria are triacylated, with the final fatty acid addition performed by Lnt, an apolipoprotein N-acyltransferase. The mature lipoproteins are then sorted by the Lol system, with most Lpps inserted into the outer membrane (OM). We demonstrate here that the lnt gene is not essential to the Gram-negative pathogen Francisella tularensis subsp. tularensis strain Schu or to the live vaccine strain LVS. An LVS Δlnt mutant has a small-colony phenotype on sucrose medium and increased susceptibility to globomycin and rifampin. We provide data indicating that the OM lipoprotein Tul4A (LpnA) is diacylated but that it, and its paralog Tul4B (LpnB), still sort to the OM in the Δlnt mutant. We present a model in which the Lol sorting pathway of Francisella has a modified ABC transporter system that is capable of recognizing and sorting both triacylated and diacylated lipoproteins, and we show that this modified system is present in many other Gram-negative bacteria. We examined this model using Neisseria gonorrhoeae, which has the same Lol architecture as that of Francisella, and found that the lnt gene is not essential in this organism. This work suggests that Gram-negative bacteria fall into two groups, one in which full lipoprotein processing is essential and one in which the final acylation step is not essential, potentially due to the ability of the Lol sorting pathway in these bacteria to sort immature apolipoproteins to the OM. IMPORTANCE This paper describes the novel finding that the final stage in lipoprotein processing (normally considered an essential process) is not required by Francisella tularensis or Neisseria gonorrhoeae. The paper provides a potential reason for this and shows that it may be widespread in other Gram-negative bacteria. PMID:25755189

  3. CLEERS Aftertreatment Modeling and Analysis

    SciTech Connect

    Devarakonda, Maruthi N.; Herling, Darrell R.; Kim, Do Heui; Kwak, Ja Hun; Peden, Charles HF; Stewart, Mark L.; Strzelec, Andrea; Szanyi, Janos; Tran, Diana N.; Lee, Jong H.

    2012-02-08

    DOE FY 2011 Advanced Combustion Technologies Annual Report. CLEERS is a research and development focus project of the Diesel Cross-Cut Team. The overall objective is to promote the development of improved computational tools for simulating realistic full-system performance of lean-burn engines and the associated emissions control systems. Three fundamental research projects are sponsored at PNNL through CLEERS: DPF, SCR, and LNT. Resources are shared between the three efforts in order to actively respond to current industrial needs. In FY 2011, more emphasis was placed on the SCR and LNT activities because of urgent application issues associated with these technologies. Objectives of this project are to lead and contribute to the Cross-Cut Lean Exhaust Emissions Reduction Simulations (CLEERS) activities - (a) Provide project updates to the industry sub-team, solicit feedback, and adjust work scope accordingly; and (b) Lead technical discussions, invite distinguished speakers, and maintain an open dialogue on selective catalytic reduction (SCR), lean-NOx trap (LNT), and diesel particulate filter (DPF) modeling issues. Fiscal Year (FY) 2011 Objectives are to: (1) Develop improved modeling capabilities for SCR and DPFs through fundamental experiments; and (2) Develop a fundamental understanding of SCR and LNT catalysts with primary focus on reaction mechanisms and material characterization. Some accomplishments are: (1) Participated in monthly CLEERS teleconferences and coordinated the calls focused on SCR, LNT and DPF technologies; (2) Updated PNNL's SCR model for the state-of-the-art commercial Cu-zeolite SCR catalyst to extract kinetic parameters and to quantitatively describe the effects of hydrothermal aging; (3) Examined the effects of hydrothermal aging on the physicochemical properties and SCR reactions using the commercial Cu catalyst in collaboration with Oak Ridge National Laboratory (ORNL); (4) Investigated the nature of Cu species and obtained kinetic

  4. Cathodoluminescence microscopy and spectroscopy of micro- and nanodiamonds: an implication for laboratory astrophysics.

    PubMed

    Gucsik, Arnold; Nishido, Hirotsugu; Ninagawa, Kiyotaka; Ott, Ulrich; Tsuchiyama, Akira; Kayama, Masahiro; Simonia, Irakli; Boudou, Jean-Paul

    2012-12-01

    Color centers in selected micro- and nanodiamond samples were investigated by cathodoluminescence (CL) microscopy and spectroscopy at 298 K [room temperature (RT)] and 77 K [liquid-nitrogen temperature (LNT)] to assess the value of the technique for astrophysics. Nanodiamonds from meteorites were compared with synthetic diamonds made with different processes involving distinct synthesis mechanisms (chemical vapor deposition, static high pressure high temperature, detonation). A CL emission peak centered at around 540 nm at 77 K was observed in almost all of the selected diamond samples and is assigned to the dislocation defect with nitrogen atoms. Additional peaks were identified at 387 and 452 nm, which are related to the vacancy defect. In general, peak intensity at LNT at the samples was increased in comparison to RT. The results indicate a clear temperature-dependence of the spectroscopic properties of diamond. This suggests the method is a useful tool in laboratory astrophysics.

  5. Effect of sulfur loading on the desulfation chemistry of a commercial lean NOx trap catalyst

    SciTech Connect

    Kim, Do Heui; Yezerets, Aleksey; Li, Junhui; Currier, Neal; Chen, Haiying; Hess, Howard ..; Engelhard, Mark H.; Muntean, George G.; Peden, Charles HF

    2012-12-15

    We investigate the effects of initial sulfur loadings on the desulfation chemistry and the subsequent final activity of a commercial LNT catalyst. Identical total amounts of SO2 are applied to the samples, albeit with the frequency of desulfation varied. The results indicate that performance is better with less frequent desulfations. The greater the amount of sulfur deposited before desulfation, the more amount of SO2 evolution before H2S is observed during desulfation, which can be explained by two sequential reactions; initial conversion of sulfate to SO2, followed by the reduction of SO2 to H2S. After completing all sulfation/desulfation steps, the sample with only a single desulfation results in a fairly uniform sulfur distribution along the z-axis inside of the monolith. We expect that the results obtained in this study will provide useful information for optimizing regeneration strategies in vehicles that utilize the LNT technology.

  6. Bifidobacterium breve UCC2003 metabolises the human milk oligosaccharides lacto-N-tetraose and lacto-N-neo-tetraose through overlapping, yet distinct pathways

    PubMed Central

    James, Kieran; Motherway, Mary O’Connell; Bottacini, Francesca; van Sinderen, Douwe

    2016-01-01

    In this study, we demonstrate that the prototype B. breve strain UCC2003 possesses specific metabolic pathways for the utilisation of lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT), which represent the central moieties of Type I and Type II human milk oligosaccharides (HMOs), respectively. Using a combination of experimental approaches, the enzymatic machinery involved in the metabolism of LNT and LNnT was identified and characterised. Homologs of the key genetic loci involved in the utilisation of these HMO substrates were identified in B. breve, B. bifidum, B. longum subsp. infantis and B. longum subsp. longum using bioinformatic analyses, and were shown to be variably present among other members of the Bifidobacterium genus, with a distinct pattern of conservation among human-associated bifidobacterial species. PMID:27929046

  7. Spin fluctuations and superconductivity in UPt3

    NASA Astrophysics Data System (ADS)

    Fay, D.; Appel, J.

    1985-11-01

    We attempt to assess the importance of spin fluctuations in the heavy-fermion system UPt3, the most unambiguous evidence for which is the T3 lnT term in the specific heat. We investigate whether other contributions, such as that from a peak in the electronic density of states or from the electron-phonon interaction, could account for the experimental data. We conclude that they cannot although the data are consistent with the presence of both a T3 lnT term and a density-of-states peak of width greater than about 60 K. We determine the input parameters for the paramagnon theory with a self-consistent method developed by Boring, Albers, Stewart, and Koelling for UAl2 and we calculate the s- and p-wave pairing interactions. A one-band model favors p-wave pairing, while a two-band model leads to conventional s-wave superconductivity.

  8. Low Noise Performance Perspectives Of Wideband Aperture Phased Arrays

    NASA Astrophysics Data System (ADS)

    Woestenburg, E. E. M.; Kuenen, J. C.

    2004-06-01

    A general analysis of phased array noise properties and measurements, applied to one square meter tiles of the Thousand Element Array (THEA), has resulted in a procedure to define the noise budget for a THEA-tile (Woestenburg and Dijkstra, 2003). The THEA system temperature includes LNA and receiver noise, antenna connecting loss, noise coupling between antenna elements and other possible contributions. This paper discusses the various noise contributions to the THEA system temperature and identifies the areas where improvement can be realized. We will present better understanding of the individual noise contributions using measurements and analysis of single antenna/receiver elements. An improved design for a 1-m2 Low Noise Tile (LNT) will be discussed and optimized low noise performance for the LNT is presented. We will also give future perspectives of the noise performance for such tiles, in relation to the requirements for SKA in the 1 GHz frequency range.

  9. Health Benefits of Exposure to Low-dose Radiation.

    PubMed

    Rithidech, Kanokporn Noy

    2016-03-01

    Although there is no doubt that exposure to high doses of radiation (delivered at a high dose-rate) induces harmful effects, the health risks and benefits of exposure to low levels (delivered at a low dose-rate) of toxic agents is still a challenging public health issue. There has been a considerable amount of published data against the linear no-threshold (LNT) model for assessing risk of cancers induced by radiation. The LNT model for risk assessment creates "radiophobia," which is a serious public health issue. It is now time to move forward to a paradigm shift in health risk assessment of low-dose exposure by taking the differences between responses to low and high doses into consideration. Moreover, future research directed toward the identification of mechanisms associated with responses to low-dose radiation is critically needed to fully understand their beneficial effects.

  10. The Healthy Worker Effect and Nuclear Industry Workers

    PubMed Central

    Fornalski, Krzysztof W.; Dobrzyński, Ludwik

    2010-01-01

    The linear no-threshold (LNT) dose-effect relationship has been consistently used by most radiation epidemiologists to estimate cancer mortality risk. The large scattering of data by International Agency for Research on Cancer, IARC (Vrijheid et al. 2007; Therry-Chef et al. 2007; Cardis et al. 2007), interpreted in accordance with LNT, has been previously demonstrated (Fornalski and Dobrzyński 2009). Using conventional and Bayesian methods the present paper demonstrates that the standard mortality ratios (SMRs), lower in the IARC cohort of exposed nuclear workers than in the non exposed group, should be considered as a hormetic effect, rather than a healthy worker effect (HWE) as claimed by the IARC group. PMID:20585442

  11. Using numerical simulations to extract parameters of toroidal electron plasmas from experimental data

    SciTech Connect

    Ha, B. N.; Stoneking, M. R.; Marler, J. P.

    2009-03-15

    Measurements of the image charge induced on electrodes provide the primary means of diagnosing plasmas in the Lawrence Non-neutral Torus II (LNT II) [Phys. Rev. Lett. 100, 155001 (2008)]. Therefore, it is necessary to develop techniques that determine characteristics of the electron plasma from features of the induced image charge signal. This paper presents a numerical study which finds that the frequency of the image charge signal due to the toroidal version of the m=1 diocotron mode is proportional to the total trapped charge and inversely proportional to magnetic field strength, as in the cylindrical case. In the toroidal case, additional information about the m=1 motion of the plasma can be obtained by analysis of the image charge signal amplitude and shape. Finally, results from the numerical simulations are compared to experimental data from the LNT II and plasma characteristics are reported.

  12. CLEERS Aftertreatment Modeling and Analysis

    SciTech Connect

    Devarakonda, Maruthi N.; Kim, Do Heui; Kwak, Ja Hun; Lee, Jong H.; Peden, Charles HF; Stewart, Mark L.; Szanyi, Janos; Tonkyn, Russell G.; Tran, Diana N.; Zelenyuk, Alla; Herling, Darrell R.

    2009-12-01

    Cross-Cut Lean Exhaust Emissions Reduction Simulations (CLEERS) is a R&D focus project of the Diesel Cross-Cut Team. The overall objective is to promote the development of improved computational tools for simulating realistic full-system performance of lean-burn engines and the associated emissions control systems. Three fundamental research projects are sponsored at Pacific Northwest National Laboratory through CLEERS, focusing on the three most prominent technologies for diesel exhaust after-treatment: • Diesel Particulate Filters (DPF) • Selective Catalytic Reduction (SCR) • Lean NOX Traps (LNT) Resources are shared between the three efforts in order to actively respond to current industrial needs. In FY09, more emphasis was placed on the SCR and LNT activities because of urgent application issues associated with these technologies.

  13. Lean Gasoline Engine Reductant Chemistry During Lean NOx Trap Regeneration

    SciTech Connect

    Choi, Jae-Soon; Prikhodko, Vitaly Y; Partridge Jr, William P; Parks, II, James E; Norman, Kevin M; Huff, Shean P; Chambon, Paul H; Thomas, John F

    2010-01-01

    Lean NOx Trap (LNT) catalysts can effectively reduce NOx from lean engine exhaust. Significant research for LNTs in diesel engine applications has been performed and has led to commercialization of the technology. For lean gasoline engine applications, advanced direct injection engines have led to a renewed interest in the potential for lean gasoline vehicles and, thereby, a renewed demand for lean NOx control. To understand the gasoline-based reductant chemistry during regeneration, a BMW lean gasoline vehicle has been studied on a chassis dynamometer. Exhaust samples were collected and analyzed for key reductant species such as H2, CO, NH3, and hydrocarbons during transient drive cycles. The relation of the reductant species to LNT performance will be discussed. Furthermore, the challenges of NOx storage in the lean gasoline application are reviewed.

  14. Effect of Ceria on the Storage and Regeneration Behavior of a Model Lean NOx Trap Catalyst

    SciTech Connect

    Ji, Yaying; Toops, Todd J; Crocker, Dr. Mark

    2007-01-01

    In this study the effect of ceria addition on the performance of a model Ba-based lean NO{sub x} trap (LNT) catalyst was examined. The presence of ceria improved NO{sub x} storage capacity in the temperature range 200-400 C under both continuous lean and lean-rich cycling conditions. Temperature-programmed experiments showed that NO{sub x} stored in the ceria-containing catalyst was thermally less stable and more reactive to reduction with both H{sub 2} and CO as reductants, albeit at the expense of additional reductant consumed by reduction of the ceria. These findings demonstrate that the incorporation of ceria in LNTs not only improves NO{sub x} storage efficiency but also positively impacts LNT regeneration behavior.

  15. Forward sum rule for the 2 γ -exchange correction to the charge-radius extraction from elastic electron scattering

    NASA Astrophysics Data System (ADS)

    Gorchtein, Mikhail

    2014-11-01

    Two-photon-exchange (TPE) contributions to elastic electron-proton scattering in the forward regime in leading logarithmic ˜t ln|t | approximation in the momentum transfer t are considered. The imaginary part of the TPE amplitude in the forward kinematics is related to the total photoabsorption cross section. The real part of the TPE amplitude is obtained from an unsubtracted fixed-t dispersion relation. This allows a clean prediction of the real part of the TPE amplitude at forward angles with the leading term ˜t ln|t | . Numerical estimates are comparable with or exceed the experimental precision in extracting the charge radius from the experimental data.

  16. Radiation Hormesis: The Good, the Bad, and the Ugly

    PubMed Central

    Luckey, T.D.

    2006-01-01

    Three aspects of hormesis with low doses of ionizing radiation are presented: the good, the bad, and the ugly. The good is acceptance by France, Japan, and China of the thousands of studies showing stimulation and/or benefit, with no harm, from low dose irradiation. This includes thousands of people who live in good health with high background radiation. The bad is the nonacceptance of radiation hormesis by the U. S. and most other governments; their linear no threshold (LNT) concept promulgates fear of all radiation and produces laws which have no basis in mammalian physiology. The LNT concept leads to poor health, unreasonable medicine and oppressed industries. The ugly is decades of deception by medical and radiation committees which refuse to consider valid evidence of radiation hormesis in cancer, other diseases, and health. Specific examples are provided for the good, the bad, and the ugly in radiation hormesis. PMID:18648595

  17. A Certified Health Physicist’s Reflections on a 40-Year Career in Radiation Protection

    PubMed Central

    2016-01-01

    This is a reflection from a certified health physicist regarding his becoming aware, during his 40-year career, that the linear no-threshold (LNT) model and the associated As Low As Reasonably Achievable concept have no scientific basis and make no positive contribution to radiation safety. They should be replaced by an alternative, scientifically based model that includes a threshold, below which there is no harm, and recognition of hormesis and the adaptive response, which reflect the benefits of low-dose and low-dose-rate radiation exposure. Continued use of the unscientific LNT model is not conservative, as most regulators complacently claim but actually harmful. Examples of these harmful impacts in the areas of nuclear power, nuclear medicine, and environmental management are included. PMID:27867322

  18. A Certified Health Physicist's Reflections on a 40-Year Career in Radiation Protection.

    PubMed

    Miller, Mark L

    2016-01-01

    This is a reflection from a certified health physicist regarding his becoming aware, during his 40-year career, that the linear no-threshold (LNT) model and the associated As Low As Reasonably Achievable concept have no scientific basis and make no positive contribution to radiation safety. They should be replaced by an alternative, scientifically based model that includes a threshold, below which there is no harm, and recognition of hormesis and the adaptive response, which reflect the benefits of low-dose and low-dose-rate radiation exposure. Continued use of the unscientific LNT model is not conservative, as most regulators complacently claim but actually harmful. Examples of these harmful impacts in the areas of nuclear power, nuclear medicine, and environmental management are included.

  19. Travel time statistics under radially converging flow in single fractures

    NASA Astrophysics Data System (ADS)

    Gotovac, Hrvoje; Srzic, Veljko; Cvetkovic, Vladimir; Kekez, Toni; Malenica, Luka

    2015-04-01

    A stochastic methodology based on Adaptive Fup Monte Carlo Method is used to investigate transport of a conservative solute by steady flow to a single pumping well in two-dimensional randomly heterogeneous single fractures. The spatially variable hydraulic transmissivity is modeled as a stationary random function for three different correlation structures (multi-Gaussian, connected and disconnected fields with correlated mean, high and low lnT values, respectively, according to the Zinn and Harvey, 2003) and heterogeneity levels (lnT variance is 1 and 8). Initially, solute particles are injected at outer circle located at 32 correlation lengths from well according to the in flux and resident injection mode. Therefore, breakthrough curve (BTC) statistics in single well due to different spatial structures, heterogeneity levels, injection modes and dispersion influence is considered. For small heterogeneity, all considered effects have small influences on BTC and related moments. As expected in single fractures, high lnT variance is more usual case which considerably changes flow patterns including channelling effect and fact that only few narrow channels carry out most pumping flow rate. Channelling implies significant differences between different injection modes. Resident mode uniformly injects particles implying that most particles pass through "slower" zones that especially increase late arrivals and contribute to the non-Fickian behaviour of transport. Contrary, "in flux" mode drastically reduces first arrivals and mean values, especially for connected correlation fields. The results from two injection modes lie on different sides of homogeneous mean travel time solution and give complementary information for complete representation of conservative transport. For advection transport, correlation structure and especially lnT variance seems to have major influence on BTC characteristics. On the other side, influence of longitudinal and lateral local scale

  20. The 10th anniversary of the publication of genes and environment: memoir of establishing the Japanese environmental mutagen society and a proposal for a new collaborative study on mutagenic hormesis.

    PubMed

    Sutou, Shizuyo

    2017-01-01

    The Japanese Environmental Mutagen Society (JEMS) was established in 1972 by 147 members, 11 of whom are still on the active list as of May 1, 2016. As one of them, I introduce some historic topics here. These include 1) establishment of JEMS, 2) the issue of 2-(2-furyl)-3-(3-nitro-2-furyl)acrylamide (AF-2), 3) the Mammalian Mutagenicity Study Group (MMS) and its achievements, and 4) the Collaborative Study Group of the Micronucleus Test (CSGMT) and its achievements. In addition to these historic matters, some of which are still ongoing, a new collaborative study is proposed on adaptive response or hormesis by mutagens. There is a close relationship between mutagens and carcinogens, the dose-response relationship of which has been thought to follow the linear no-threshold model (LNT). LNT was fabricated on the basis of Drosophila sperm experiments using high dose radiation delivered in a short period. The fallacious 60 years-old LNT is applied to cancer induction by radiation without solid data and then to cancer induction by carcinogens also without solid data. Therefore, even the smallest amount of carcinogens is postulated to be carcinogenic without thresholds now. Radiation hormesis is observed in a large variety of living organisms; radiation is beneficial at low doses, but hazardous at high doses. There is a threshold at the boundary between benefit and hazard. Hormesis denies LNT. Not a few papers report existence of chemical hormesis. If mutagens and carcinogens show hormesis, the linear dose-response relationship in mutagenesis and carcinogenesis is denied and thresholds can be introduced.

  1. A randomized control study of treating secondary stage II breast cancer-related lymphoedema with free lymph node transfer.

    PubMed

    Dionyssiou, Dimitrios; Demiri, Efterpi; Tsimponis, Antonis; Sarafis, Alexandros; Mpalaris, Vasillios; Tatsidou, Georgia; Arsos, Georgios

    2016-02-01

    Microsurgical techniques are increasingly used for treating severe lymphoedema cases. The purpose of this study was to evaluate the effectiveness of free vascularized lymph node transfer (LNT) in stage II breast cancer-related lymphoedema patients in comparison with non-surgical management. During the last 3 years, 83 female patients were examined at our lymphoedema clinic. Finally, 36 cases were included in this study and randomly divided in two groups: group A patients (n = 18, mean age 47 years) underwent microsurgical LNT; followed by 6 months of physiotherapy and compression, while group B patients (n = 18, mean age 49 years) were managed by physiotherapy and compression alone for 6 months. Patients of both groups removed their elastic garments after 6 months and were re-examined 1 year later. All the 36 patients had detailed evaluation of the affected extremity including limb volume measurement, infection episodes and scale scoring of pain, feeling of heaviness and functional status both at baseline and 18 month. Limb volume reduction was observed in both groups; mean reduction was greater in group A (57 %) than in group B (18 %). Infection episodes in group A were significantly reduced compared to those in group B patients. All group A patients reported painless and feeling of heaviness-free extremities with overall functional improvement, while the corresponding changes in group B patients were no more than marginal. Moreover, the LNT procedure was estimated as cost effective compared to conservative treatment alone. LNT represents an effective therapeutic approach for stage II lymphoedema patients; it significantly reduces limb volume, decreases recurrent infections and improves the overall function.

  2. A More Flexible Lipoprotein Sorting Pathway

    PubMed Central

    Chahales, Peter

    2015-01-01

    Lipoprotein biogenesis in Gram-negative bacteria occurs by a conserved pathway, each step of which is considered essential. In contrast to this model, LoVullo and colleagues demonstrate that the N-acyl transferase Lnt is not required in Francisella tularensis or Neisseria gonorrhoeae. This suggests the existence of a more flexible lipoprotein pathway, likely due to a modified Lol transporter complex, and raises the possibility that pathogens may regulate lipoprotein processing to modulate interactions with the host. PMID:25755190

  3. Characterization of the Human Proteomic Response to Hydrocodone: A Preliminary Study

    DTIC Science & Technology

    2013-03-01

    hippocampus and striatum after exposure to morphine , lnt J Mol Med 18 (2006) 775-784. [50] Z.H. Wen, G.J. Wu, L.C. Hsu, W.F. Chen, J.Y. Chen, H.A...McMillin, F.M. Urry, Simultaneous determination of codeine, morphine , hydrocodone, hydromorphone, oxycodone, and 6-acetylmorphine in urine, serum...Simultaneous assay of morphine , morphine -3-glucuronide and morphine -6-glucuronide in human plasma using normal-phase liquid chromatography-tandem

  4. Development of the United States Leave No Trace programme: A historical perspective

    USGS Publications Warehouse

    Marion, J.L.; Reid, S.; Usher, M.B.

    2001-01-01

    This paper describes the historical development of the U.S. Leave No Trace (LNT) educational program. It begins with a review of the need for the program and traces it?s conception and early development in the 1970`s, revitalization in 1991, creation of Leave No Trace, Inc., and the current status. The paper concludes with a discussion of the program?s elements that have made it successful and recommendations for the development of similar educational programs.

  5. Enhanced Preliminary Assessment. Task Order 2. Nike Battery Kansas City 30, Pleasant Hill, Missouri

    DTIC Science & Technology

    1989-12-01

    a/ Geneva Van Cami Doty _ :.’ .S .. ,, I:.~ io ~ b~.±2, bar ~.2 c.ir~w~j €" -- .’ ’ .:u :.x\\ ’Z :,. (a.’,:, Lh....... . .. .b"n, J.Ŕ" A -7: .: : I...thence:in anortheastcrlydirection blong :thd. coextar of said ditch, nprorximatoly 125" fdot.torthe poLnt of Latersaction*with I-[n- the abova-d

  6. US EPA, Pesticide Product Label, BAR-TEK M-20, 09/07/1984

    EPA Pesticide Factsheets

    2011-04-21

    ... d'r.'IIt.·,! ... On Ihf' hI~I'" "f Inf"ITl'"IIOn fUllll'.Ilt'rl h\\ Ih,' fI·~~I'S.lr,lnt, 1111 ,.1".\\'" Il.'n· •• ·d '.· .. IIt·leie· IS he'fI'h\\" Rt·fl-;lC'tf'd!Rt'fl'~I!-:.I("f('d un"t.'r ...

  7. Correlation function for generalized Pólya urns: Finite-size scaling analysis

    NASA Astrophysics Data System (ADS)

    Mori, Shintaro; Hisakado, Masato

    2015-11-01

    We describe a universality class for the transitions of a generalized Pólya urn by studying the asymptotic behavior of the normalized correlation function C (t ) using finite-size scaling analysis. X (1 ),X (2 ),... are the successive additions of a red (blue) ball [X (t )=1 (0 )] at stage t and C (t )≡Cov[X (1 ),X (t +1 )]/Var[X (1 )] . Furthermore, z (t ) =∑s=1tX (s ) /t represents the successive proportions of red balls in an urn to which, at the (t +1 )th stage, a red ball is added [X (t +1 )=1 ] with probability q [z (t )]=(tanh{J [2 z (t )-1 ]+h }+1 )/2 ,J ≥0 , and a blue ball is added [X (t +1 )=0 ] with probability 1 -q [z (t )] . A boundary [Jc(h ) ,h ] exists in the (J ,h ) plane between a region with one stable fixed point and another region with two stable fixed points for q (z ) . C (t ) ˜c +c'.tl -1 with c =0 (>0 ) for J Jc) , and l is the (larger) value of the slope(s) of q (z ) at the stable fixed point(s). On the boundary J =Jc(h ) ,C (t ) ≃c +c'.(lnt) -α' and c =0 (c >0 ) ,α'=1 /2 (1 ) for h =0 (h ≠0 ) . The system shows a continuous phase transition for h =0 and C (t ) behaves as C (t ) ≃(lnt) -α'g [(1 -l ) lnt ] with a universal function g (x ) and a length scale 1 /(1 -l ) with respect to lnt . β =ν||.α' holds with β =1 /2 and ν||=1 .

  8. An Automated Hollow Fiber System for the Deglycerolization of Thawed Frozen Human Blood. Phase 1.

    DTIC Science & Technology

    1994-09-13

    EDTA, Vol. 17, 1980, pp. 353-356. 22. Tova A. Stepner and Edward F. Leonard, "Evaluation of Plasmapheresis Membranes, Journal of Membrane Science...Research Laboratory, Boston, MA, December 20, 1993. 31. C.R. Valeri, et al, "The Safety and Therapeutic Effectiveness of Human Red Cells Stored at - 80 0C...Membrane Plasmapheresis ," Proc. lnt Symposium on Artificial Organs, Biomedical Engineering and Transplantation, Salt Lake City, Utah, January 20-23

  9. Lipid nanotechnologies for structural studies of membrane-associated proteins.

    PubMed

    Stoilova-McPhie, Svetla; Grushin, Kirill; Dalm, Daniela; Miller, Jaimy

    2014-11-01

    We present a methodology of lipid nanotubes (LNT) and nanodisks technologies optimized in our laboratory for structural studies of membrane-associated proteins at close to physiological conditions. The application of these lipid nanotechnologies for structure determination by cryo-electron microscopy (cryo-EM) is fundamental for understanding and modulating their function. The LNTs in our studies are single bilayer galactosylceramide based nanotubes of ∼20 nm inner diameter and a few microns in length, that self-assemble in aqueous solutions. The lipid nanodisks (NDs) are self-assembled discoid lipid bilayers of ∼10 nm diameter, which are stabilized in aqueous solutions by a belt of amphipathic helical scaffold proteins. By combining LNT and ND technologies, we can examine structurally how the membrane curvature and lipid composition modulates the function of the membrane-associated proteins. As proof of principle, we have engineered these lipid nanotechnologies to mimic the activated platelet's phosphtaidylserine rich membrane and have successfully assembled functional membrane-bound coagulation factor VIII in vitro for structure determination by cryo-EM. The macromolecular organization of the proteins bound to ND and LNT are further defined by fitting the known atomic structures within the calculated three-dimensional maps. The combination of LNT and ND technologies offers a means to control the design and assembly of a wide range of functional membrane-associated proteins and complexes for structural studies by cryo-EM. The presented results confirm the suitability of the developed methodology for studying the functional structure of membrane-associated proteins, such as the coagulation factors, at a close to physiological environment. © 2014 Wiley Periodicals, Inc.

  10. Comment on ``Critical behavior of the zero-temperature conductivity in compensated silicon, Si:(P,B)''

    NASA Astrophysics Data System (ADS)

    Möbius, A.

    1989-08-01

    In a recently published conductivity study of Si:(P,B) very close to the metal-insulator transition, Hirsch and co-workers performed the zero-temperature extrapolation by using the relation σ(T)=σ(0)+mT1/2+BT3/4, based on modern localization theory. This extrapolation is critically reconsidered studying the temperature dependence of the logarithmic derivative, dlnσ/d lnT. .AE

  11. Lean NOx Trap Modeling in Vehicle Systems Simulations

    SciTech Connect

    Gao, Zhiming; Chakravarthy, Veerathu K; Daw, C Stuart; Conklin, Jim

    2010-09-01

    A one-dimensional model for simulating lean NOx trap (LNT) performance is developed and validated using both steady state cycling data and transient data from FTP testing cycles. The model consists of the conservation equations for chemical species and energy in the bulk flow, energy of the solid walls, O2 storage and NOx storage (in the form of nitrites and nitrates). Nitrites and nitrates are formed by diffusion of NO and NO2, respectively, into sorbent particles (assumed to be hemi-spherical in shape) along with O2 and their formation rates are controlled by chemical kinetics as well as solid-phase diffusion rates of NOx species. The model also accounts for thermal aging and sulfation of LNTs. Empirical correlations are developed on the basis of published experimental data to capture these effects. These empirical correlations depend on total mileage for which the LNT has been in use, the mileage accumulated since the last desulfation event in addition to the freshly degreened catalyst characteristics. The model has been used in studies of vehicle systems (integration, performance etc.) including hybrid powertrain configurations. Since the engines in hybrid vehicles turn on and off multiple number of times during single drive cycles, the exhaust systems may encounter multiple cold start transients. Accurate modeling of catalyst warm-up and cooling is, therefore, very important to simulate LNT performance in such vehicles. For this purpose, the convective heat loss from the LNT to the ambient is modeled using a Nusselt number correlation that includes effects of both forced convection and natural convection (with later being important when vehicle is stationary). Using the model, the fuel penalty associated with operating LNTs on small diesel engine powered car during FTP drive cycles is estimated.

  12. Micro Computer Feedback Report for the Strategic Leader Development Inventory; Source Code

    DTIC Science & Technology

    1994-03-01

    dir INC DI ;ptr to next byte LOOP COP3 ;loop until CX m 0 -------.find next match NOV AX,4F00h ;fine next file function lNT 21h ;do next search aNC COP0...continue if J > 0. COP3 : POP DX ;restore registers POP CX POP AX RUT ;return to ShellSort ENDP COI1ARX SWAP IMP SHILLSORT ;------- oSend a 16 byte

  13. Qualitative Assessment of Speech Perception Performance of Early and Late Cochlear Implantees.

    PubMed

    Kant, Anjali R; Pathak, Sonal

    2015-09-01

    The present study aims to provide a qualitative description and comparison of speech perception performance using model based tests like multisyllabic lexical neighborhood test (MLNT) and lexical neighborhood test (LNT), in early and late implanted (prelingual) hearing impaired children using cochlear implants. The subjects comprised of cochlear implantees; Group I (early implantees)-n = 15, 3-6 years of age; mean age at implantation-3½ years. Group II (late implantees)-n = 15, 7-13 years of age; mean age at implantation-5 years. The tests were presented in a sound treated room at 70 dBSPL. The children were instructed to repeat the words on hearing them. Responses were scored as percentage of words correctly repeated. Their means were computed. The late implantees achieved higher scores for words on MLNT than those on LNT. This may imply that late implantees are making use of length cues in order to aid them in speech perception. The major phonological process used by early implantees was deletion and by the late implantees was substitution. One needs to wait until the child achieves a score of 20 % on LNT before assessing other aspects of his/her speech perception abilities. There appears to be a need to use speech perception tests which are based on theoretical empirical models, in order to enable us to give a descriptive analysis of post implant speech perception performance.

  14. Investigation of Mixed Oxide Catalysts for NO Oxidation

    SciTech Connect

    Szanyi, Janos; Karim, Ayman M.; Pederson, Larry R.; Kwak, Ja Hun; Mei, Donghai; Tran, Diana N.; Herling, Darrell R.; Muntean, George G.; Peden, Charles HF; Howden, Ken; Qi, Gongshin; Li, Wei

    2014-12-09

    The oxidation of engine-generated NO to NO2 is an important step in the reduction of NOx in lean engine exhaust because NO2 is required for the performance of the LNT technology [2], and it enhances the activities of ammonia selective catalytic reduction (SCR) catalysts [1]. In particular, for SCR catalysts an NO:NO2 ratio of 1:1 is most effective for NOx reduction, whereas for LNT catalysts, NO must be oxidized to NO2 before adsorption on the storage components. However, NO2 typically constitutes less than 10% of NOx in lean exhaust, so catalytic oxidation of NO is essential. Platinum has been found to be especially active for NO oxidation, and is widely used in DOC and LNT catalysts. However, because of the high cost and poor thermal durability of Pt-based catalysts, there is substantial interest in the development of alternatives. The objective of this project, in collaboration with partner General Motors, is to develop mixed metal oxide catalysts for NO oxidation, enabling lower precious metal usage in emission control systems. [1] M. Koebel, G. Madia, and M. Elsener, Catalysis Today 73, 239 (2002). [2] C. H. Kim, G. S. Qi, K. Dahlberg, and W. Li, Science 327, 1624 (2010).

  15. Linear No-Threshold Model VS. Radiation Hormesis

    PubMed Central

    Doss, Mohan

    2013-01-01

    The atomic bomb survivor cancer mortality data have been used in the past to justify the use of the linear no-threshold (LNT) model for estimating the carcinogenic effects of low dose radiation. An analysis of the recently updated atomic bomb survivor cancer mortality dose-response data shows that the data no longer support the LNT model but are consistent with a radiation hormesis model when a correction is applied for a likely bias in the baseline cancer mortality rate. If the validity of the phenomenon of radiation hormesis is confirmed in prospective human pilot studies, and is applied to the wider population, it could result in a considerable reduction in cancers. The idea of using radiation hormesis to prevent cancers was proposed more than three decades ago, but was never investigated in humans to determine its validity because of the dominance of the LNT model and the consequent carcinogenic concerns regarding low dose radiation. Since cancer continues to be a major health problem and the age-adjusted cancer mortality rates have declined by only ∼10% in the past 45 years, it may be prudent to investigate radiation hormesis as an alternative approach to reduce cancers. Prompt action is urged. PMID:24298226

  16. Cochlear implant characteristics and speech perception skills of adolescents with long-term device use.

    PubMed

    Davidson, Lisa S; Geers, Ann E; Brenner, Christine

    2010-10-01

    Updated cochlear implant technology and optimized fitting can have a substantial impact on speech perception. The effects of upgrades in processor technology and aided thresholds on word recognition at soft input levels and sentence recognition in noise were examined. We hypothesized that updated speech processors and lower aided thresholds would allow improved recognition of soft speech without compromising performance in noise. 109 teenagers who had used a Nucleus 22-cochlear implant since preschool were tested with their current speech processor(s) (101 unilateral and 8 bilateral): 13 used the Spectra, 22 the ESPrit 22, 61 the ESPrit 3G, and 13 the Freedom. The Lexical Neighborhood Test (LNT) was administered at 70 and 50 dB SPL and the Bamford Kowal Bench sentences were administered in quiet and in noise. Aided thresholds were obtained for frequency-modulated tones from 250 to 4,000 Hz. Results were analyzed using repeated measures analysis of variance. Aided thresholds for the Freedom/3G group were significantly lower (better) than the Spectra/Sprint group. LNT scores at 50 dB were significantly higher for the Freedom/3G group. No significant differences between the 2 groups were found for the LNT at 70 or sentences in quiet or noise. Adolescents using updated processors that allowed for aided detection thresholds of 30 dB HL or better performed the best at soft levels. The BKB in noise results suggest that greater access to soft speech does not compromise listening in noise.

  17. Effect of Grain Refinement on the Mechanical Behaviour of an Al6061 Alloy at Cryogenic Temperatures

    SciTech Connect

    Moreno-Valle, E.; Sabirov, I.; Murashkin, M. Yu.; Valiev, R. Z.; Bobruk, E. V.; Perez-Prado, M. T.

    2011-05-04

    A solution treated coarse grained (CG) Al6061 was subjected to high pressure torsion (HPT) at room temperature resulting in the formation of a homogeneous ultra-fine grained (UFG) microstructure with an average grain size of 170 nm. Tensile tests were performed at room temperature (RT) and liquid nitrogen temperature (LNT). The as-HPT UFG Al6061 alloy shows an increased strength at both RT and LNT. The decrease of testing temperature results in increased flow stress and in enhanced elongation to failure in both CG and UFG samples. The ratio {sigma}{sub y}{sup LNT}/{sigma}{sub y}{sup RT} was found to be larger for the CG Al6061 than for the UFG Al6061. Both surface relief and fracture surface observations were performed. The effect of the grain size and of the testing temperature on the mechanical behaviour of the Al6061 alloy is analyzed in detail. It is suggested that the solute atoms play an important role in the plastic deformation of the UFG Al6061 alloy.

  18. Honoring Identity Through Mealtimes in Chinese Canadian Immigrants.

    PubMed

    Lam, Ivy T Y; Keller, Heather H

    2015-11-01

    Mealtimes are opportunities for social interactions and expressions of individual and family identity, and serve as a microcosm of the broader lives of families living with dementia. The Eating Together study and its resulting Life Nourishment Theory (LNT) explicated the importance of mealtimes for honouring individual and family identities in the context of dementia. This sub-study examined a specific ethnocultural group with cultural food-ways and caring expectations, to determine if the concept of honouring identity needed to be modified or extended. Using active interview techniques, two Cantonese speaking researchers completed dyad/triad family and individual interviews with six Chinese Canadian immigrant families, recruited from two service providers in a large, urban, multicultural city. This sub-study provided insight into the challenges and rewards of mealtimes for Chinese immigrant families with dementia in the community and specifically provided further insights into the honouring identity concept. Although LNT and specifically the honouring identity concept was generally confirmed in this group, some culturally-specific themes were also identified. This work serves as a basis for future studies examining the meaning and experience of mealtimes in specific cultural groups living with dementia. Such work would confirm if the LNT can be applied to specific ethnocultural groups as well as the general population living with dementia.

  19. Epidemiology Without Biology: False Paradigms, Unfounded Assumptions, and Specious Statistics in Radiation Science (with Commentaries by Inge Schmitz-Feuerhake and Christopher Busby and a Reply by the Authors).

    PubMed

    Sacks, Bill; Meyerson, Gregory; Siegel, Jeffry A

    Radiation science is dominated by a paradigm based on an assumption without empirical foundation. Known as the linear no-threshold (LNT) hypothesis, it holds that all ionizing radiation is harmful no matter how low the dose or dose rate. Epidemiological studies that claim to confirm LNT either neglect experimental and/or observational discoveries at the cellular, tissue, and organismal levels, or mention them only to distort or dismiss them. The appearance of validity in these studies rests on circular reasoning, cherry picking, faulty experimental design, and/or misleading inferences from weak statistical evidence. In contrast, studies based on biological discoveries demonstrate the reality of hormesis: the stimulation of biological responses that defend the organism against damage from environmental agents. Normal metabolic processes are far more damaging than all but the most extreme exposures to radiation. However, evolution has provided all extant plants and animals with defenses that repair such damage or remove the damaged cells, conferring on the organism even greater ability to defend against subsequent damage. Editors of medical journals now admit that perhaps half of the scientific literature may be untrue. Radiation science falls into that category. Belief in LNT informs the practice of radiology, radiation regulatory policies, and popular culture through the media. The result is mass radiophobia and harmful outcomes, including forced relocations of populations near nuclear power plant accidents, reluctance to avail oneself of needed medical imaging studies, and aversion to nuclear energy-all unwarranted and all harmful to millions of people.

  20. Advanced Engine/Aftertreatment System R&D

    SciTech Connect

    Pihl, J.; West, B.; Toops, T.; Adelman, B.; Derybowski, E.

    2011-09-30

    Navistar and ORNL established this CRADA to develop diesel engine aftertreatment configurations and control strategies that could meet emissions regulations while maintaining or improving vehicle efficiency. The early years of the project focused on reducing the fuel penalty associated with lean NOx trap (LNT, also known as NOx adsorber catalyst) regeneration and desulfation. While Navistar pursued engine-based (in-cylinder) approaches to LNT regeneration, complementary experiments at ORNL focused on in-exhaust fuel injection. ORNL developed a PC-based controller for transient electronic control of EGR valve position, intake throttle position, and actuation of fuel injectors in the exhaust system of a Navistar engine installed at Oak Ridge. Aftertreatment systems consisting of different diesel oxidation catalysts (DOCs) in conjunction with a diesel particle filter and LNT were evaluated under quasi-steady-state conditions. Hydrocarbon (HC) species were measured at multiple locations in the exhaust system with Gas chromatograph mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) spectroscopy.

  1. Probabilistic Interpolation of Wind Hazard Maps

    NASA Astrophysics Data System (ADS)

    Xu, L.

    2012-12-01

    Wind hazard maps are widely used to compute design loads and to evaluate insurance risks. While building codes often provide these maps for only a few return periods, wind hazard maps for other return periods are often needed for risk assessments. In this study, we evaluate a probabilistic interpolation approach for deriving wind hazard maps for return periods other than those available. The probabilistic interpolation approach assumes that probabilities of wind values in a wind hazard map follow Gumbel distribution. Although most studies have been performed on data from individual weather stations, it remains to be seen how well the Gumbel distribution-based interpolation performs for wind hazard maps. The Gumbel distribution F(V) =exp{-exp[-α(V - u)]} is assumed for wind speed at a wind map location, where α and u are parameters that vary with location. VT = u + α-1lnT is the wind speed of return period T when T is large. If T0 and T1 are two given return periods and T1 is greater, then VT = (1-θ)VT0 + θVT1 where θ = (lnT - lnT0)/(lnT1 - lnT0). Therefore, VT is a weighted average between VT0 and VT1. Here we select the US and Mexican hazard maps to evaluate the probabilistic interpolation method. In ASCE 7-10 wind maps, the basic wind speed has a single value for most inland areas, which is 54, 51, and 47 m/s for 1700-year, 700-year, and 300-year return periods, respectively. We use the 1700-year and 300-year values to obtain the 700-year value using the Gumbel distribution-based interpolation. The computed 700-year value is 50.4 m/s compared to 51 m/s provided in the code, about 1% difference. For coastal regions subjected to hurricane winds, the relative error between the interpolated 700-year values and the original 700-year values are within 2% for most areas except for areas where hurricane zones transition to inland non-hurricane zones; there the relative errors can increase to 4%. The Mexican wind code includes wind maps of three return periods: 10

  2. A Longitudinal Study of Speech Perception Skills and Device Characteristics of Adolescent Cochlear Implant Users

    PubMed Central

    Robinson, Elizabeth J.; Davidson, Lisa S.; Uchanski, Rosalie M.; Brenner, Christine M.; Geers, Ann E.

    2012-01-01

    Background For pediatric cochlear implant (CI) users, CI processor technology, map characteristics and fitting strategies are known to have a substantial impact on speech perception scores at young ages. It is unknown whether these benefits continue over time as these children reach adolescence. Purpose To document changes in CI technology, map characteristics, and speech perception scores in children between elementary grades and high school, and to describe relations between map characteristics and speech perception scores over time. Research Design A longitudinal design with participants 8–9 years old at session 1 and 15–18 years old at session 2. Study Sample Participants were 82 adolescents with unilateral CIs, who are a subset of a larger longitudinal study. Mean age at implantation was 3.4 years (range: 1.7 – 5.4), and mean duration of device use was 5.5 years (range: 3.8–7.5) at session 1 and 13.3 years (range: 10.9–15) at session 2. Data Collection and Analysis Speech perception tests at sessions 1 and 2 were the Lexical Neighborhood word Test (LNT-70) and Bamford-Kowal-Bench sentences in quiet (BKB-Q), presented at 70 dB SPL. At session 2, the LNT was also administered at 50 dB SPL (LNT-50) and BKB sentences were administered in noise with a +10 dB SNR (BKB-N). CI processor technology type and CI map characteristics (coding strategy, number of electrodes, map threshold levels [T levels], and map comfort levels [C levels]) were obtained at both sessions. Electrical dynamic range [EDR] was computed [C level – T level], and descriptive statistics, correlations, and repeated-measures ANOVAs were employed. Results Participants achieved significantly higher LNT and BKB scores, at 70 dB SPL, at ages 15-18 than at ages 8-9 years. Forty-two participants had 1-3 electrodes either activated or deactivated in their map between test sessions, and 40 had no change in number of active electrodes (mean change: -0.5; range: -3 to +2). After conversion from

  3. Phase separation of polymer thin films and some applications

    NASA Astrophysics Data System (ADS)

    Zhu, Shaoming

    Phase separation of polymer thin film is a common issue in polymer thin film application. The existence of surface and surfactant are understood to play an important role in thin film final topography. In chapter two, the configuration of polymer blend thin film phase separation on cobalt substrate with PMMA phase forming column structure, and PS phase encapsulating the PMMA phase was used as resist mask to transfer the topographical feature to cobalt thin film. Isolated near spherical single and multi domain magnetic islands were obtained. The island made using this method had a broad single domain range from below 1000 to 5000A. In chapter three, when the polymer blend thin film was in bilayer configuration and diblock copolymer was added on the top layer, we found the confinement can increase the mixing of two homopolymers in highly incompatible polymer blends. By affecting the formation of micelles, the copolymers are forced to the interface between the two homopolymer phases where they reduce the interfacial tension to zero and form a microemulsion. Our findings have two important implications: first, they elucidate the role entropy plays in determining the phase behaviour of confined polymer blends and second, they offer a simple pathway to create thin film coatings with precisely controlled properties and surfaces. In chapter four, the kinetics process of microemulsion formation in confinement configuration has been analyzed. The microemulsion formation proceeded at initial stage by capillary wave, then it followed the growth regime t1/3 and lnt, then followed a more slow growth regime (lnt).56 or (lnt).60 till finally reached equilibrium, when the structure was frozen. In chapter five, we study the evolution of the morphologies of polymer blend thin films on silicon, cobalt, and gold substrates. In asymmetrical system, the substrate surface energy determined the wetting degree of the substrate preferring phases. In chapter six, we present a novel method for

  4. Dose-responses from multi-model inference for the non-cancer disease mortality of atomic bomb survivors.

    PubMed

    Schöllnberger, H; Kaiser, J C; Jacob, P; Walsh, L

    2012-05-01

    The non-cancer mortality data for cerebrovascular disease (CVD) and cardiovascular diseases from Report 13 on the atomic bomb survivors published by the Radiation Effects Research Foundation were analysed to investigate the dose-response for the influence of radiation on these detrimental health effects. Various parametric and categorical models (such as linear-no-threshold (LNT) and a number of threshold and step models) were analysed with a statistical selection protocol that rated the model description of the data. Instead of applying the usual approach of identifying one preferred model for each data set, a set of plausible models was applied, and a sub-set of non-nested models was identified that all fitted the data about equally well. Subsequently, this sub-set of non-nested models was used to perform multi-model inference (MMI), an innovative method of mathematically combining different models to allow risk estimates to be based on several plausible dose-response models rather than just relying on a single model of choice. This procedure thereby produces more reliable risk estimates based on a more comprehensive appraisal of model uncertainties. For CVD, MMI yielded a weak dose-response (with a risk estimate of about one-third of the LNT model) below a step at 0.6 Gy and a stronger dose-response at higher doses. The calculated risk estimates are consistent with zero risk below this threshold-dose. For mortalities related to cardiovascular diseases, an LNT-type dose-response was found with risk estimates consistent with zero risk below 2.2 Gy based on 90% confidence intervals. The MMI approach described here resolves a dilemma in practical radiation protection when one is forced to select between models with profoundly different dose-responses for risk estimates.

  5. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate ( struvite) and its isomorphous analogues. VII: Spectra of protiated and partially deuterated hexagonal magnesium caesium phosphate hexahydrate

    NASA Astrophysics Data System (ADS)

    Stefov, V.; Cahil, A.; Šoptrajanov, B.; Najdoski, M.; Spirovski, F.; Engelen, B.; Lutz, H. D.; Koleva, V.

    2009-04-01

    The Fourier transform infrared and Raman spectra of the struvite analogue, hexagonal magnesium caesium phosphate hexahydrate, MgCsPO 4·6H 2O ( hP50) and of its partially deuterated analogues were recorded from room temperature (RT) down to the boiling temperature of liquid nitrogen (LNT). The existence of strong hydrogen bonds between water molecules and PO 43- ions is supported by the appearance of a broad band from 3600 to 2200 cm -1 in the O-H stretching region of the vibrational spectra. In the region of the OD stretching vibrations of isotopically isolated HDO molecules of the analogue with a small deuterium content (≈5% D), at least two bands (from the expected three) are observed in the difference LNT infrared spectrum. In the region of ν3(PO 4) modes of the infrared spectra, a broad and asymmetric band (at around 1000 cm -1) is found, while in the region of the ν4(PO 4) bending vibration and of the external modes of the water molecules, several bands can be seen. The intense band at 945 cm -1 in the Raman spectra can with certainty be attributed to the ν1(PO 4) mode. On the basis of a careful analysis of the RT and LNT spectra of the protiated compound, as well as those of its partially deuterated analogues, the asymmetric band at around 550 cm -1 could be assigned to the components of the ν4(PO 4) mode, the bands between 470 and 430 cm -1 to the ν2(PO 4) vibrations and the remaining ones as due to pure or coupled librational and translational modes of the water molecules. The external modes of the phosphate ions and those of the water molecules are mixed.

  6. Implications of the temperature dependence of Nd:YAG spectroscopic values for low temperature laser operation at 946 nm

    NASA Astrophysics Data System (ADS)

    Yoon, S. J.; Mackenzie, J. I.

    2014-05-01

    We present our measurements of the key spectroscopic properties over the temperature range of 77 K to 450 K for Nd3+ ions doped in Y3Al5O12 (YAG). From room to liquid nitrogen temperature (LNT), the peak absorption cross section around 808 nm increased by almost 3 times, in conjunction the bandwidth of this absorption line reduced by the same factor. At LNT the peak of the absorption line was blue shifted by 0.25 nm with respect to that at 300 K. The fluorescence spectrum between 850 nm - 1450 nm was measured, from which the emission cross sections for the three main transitions were calculated. One note of particular interest for the dominant emission wavelengths around 1064nm and 1061nm (4F3/2 --> 4I11/2) was the switch in their relative strength below 170K, and at LNT the 1061 nm line has almost twice the cross section as at 1064nm.. The fluorescence and lifetime of the upper laser level (4F3/2) was measured and the effective emission cross section determined by the Fuchtbauer-Ladenburg (F-L) method. The effective emission cross section for 946 nm (R1 --> Z5) increased by more than two times over the 300 K to 77 K range. A numerical fit for the temperature dependent emission cross section at 946 nm and 1064 nm and also calculated absorption coefficient at 808 nm pump diode laser have also obtained from the measured spectroscopic data.

  7. Investigation of the Effects of Biodiesel-based Na on Emissions Control Components

    SciTech Connect

    Brookshear, D. William; Nguyen, Ke; Toops, Todd J; Bunting, Bruce G; Howe, Janet E

    2012-01-01

    A single-cylinder diesel engine was used to investigate the impact of biodiesel-based Na on emissions control components using specially blended 20% biodiesel fuel (B20). The emissions control components investigated were a diesel oxidation catalyst (DOC), a Cu-zeolite-based NH{sub 3}-SCR (selective catalytic reduction) catalyst, and a diesel particulate filter (DPF). Both light-duty vehicle, DOC-SCR-DPF, and heavy-duty vehicle, DOC-DPF-SCR, emissions control configurations were employed. The accelerated Na aging is achieved by introducing elevated Na levels in the fuel, to represent full useful life exposure, and periodically increasing the exhaust temperature to replicate DPF regeneration. To assess the validity of the implemented accelerated Na aging protocol, engine-aged lean NO{sub x} traps (LNTs), DOCs and DPFs are also evaluated. To fully characterize the impact on the catalytic activity the LNT, DOC and SCR catalysts were evaluated using a bench flow reactor. The evaluation of the aged DOC samples and LNT show little to no deactivation as a result of Na contamination. However, the SCR in the light-duty configuration (DOC-SCR-DPF) was severely affected by Na contamination, especially when NO was the only fed NO{sub x} source. In the heavy-duty configuration (DOC-DPF-SCR), no impact is observed in the SCR NO{sub x} reduction activity. Electron probe micro-analysis (EPMA) reveals that Na contamination on the LNT, DOC, and SCR samples is present throughout the length of the catalysts with a higher concentration on the washcoat surface. In both the long-term engine-aged DPF and the accelerated Na-aged DPFs, there is significant Na ash present in the upstream channels; however, in the engine-aged sample lube oil-based ash is the predominant constituent.

  8. Lessons to be learned from a contentious challenge to mainstream radiobiological science (the linear no-threshold theory of genetic mutations).

    PubMed

    Beyea, Jan

    2017-04-01

    There are both statistically valid and invalid reasons why scientists with differing default hypotheses can disagree in high-profile situations. Examples can be found in recent correspondence in this journal, which may offer lessons for resolving challenges to mainstream science, particularly when adherents of a minority view attempt to elevate the status of outlier studies and/or claim that self-interest explains the acceptance of the dominant theory. Edward J. Calabrese and I have been debating the historical origins of the linear no-threshold theory (LNT) of carcinogenesis and its use in the regulation of ionizing radiation. Professor Calabrese, a supporter of hormesis, has charged a committee of scientists with misconduct in their preparation of a 1956 report on the genetic effects of atomic radiation. Specifically he argues that the report mischaracterized the LNT research record and suppressed calculations of some committee members. After reviewing the available scientific literature, I found that the contemporaneous evidence overwhelmingly favored a (genetics) LNT and that no calculations were suppressed. Calabrese's claims about the scientific record do not hold up primarily because of lack of attention to statistical analysis. Ironically, outlier studies were more likely to favor supra-linearity, not sub-linearity. Finally, the claim of investigator bias, which underlies Calabrese's accusations about key studies, is based on misreading of text. Attention to ethics charges, early on, may help seed a counter narrative explaining the community's adoption of a default hypothesis and may help focus attention on valid evidence and any real weaknesses in the dominant paradigm. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Standard-Chinese Lexical Neighborhood Test in normal-hearing young children.

    PubMed

    Liu, Chang; Liu, Sha; Zhang, Ning; Yang, Yilin; Kong, Ying; Zhang, Luo

    2011-06-01

    The purposes of the present study were to establish the Standard-Chinese version of Lexical Neighborhood Test (LNT) and to examine the lexical and age effects on spoken-word recognition in normal-hearing children. Six lists of monosyllabic and six lists of disyllabic words (20 words/list) were selected from the database of daily speech materials for normal-hearing (NH) children of ages 3-5 years. The lists were further divided into "easy" and "hard" halves according to the word frequency and neighborhood density in the database based on the theory of Neighborhood Activation Model (NAM). Ninety-six NH children (age ranged between 4.0 and 7.0 years) were divided into three different age groups of 1-year intervals. Speech-perception tests were conducted using the Standard-Chinese monosyllabic and disyllabic LNT. The inter-list performance was found to be equivalent and inter-rater reliability was high with 92.5-95% consistency. Results of word-recognition scores showed that the lexical effects were all significant. Children scored higher with disyllabic words than with monosyllabic words. "Easy" words scored higher than "hard" words. The word-recognition performance also increased with age in each lexical category. A multiple linear regression analysis showed that neighborhood density, age, and word frequency appeared to have increasingly more contributions to Chinese word recognition. The results of the present study indicated that performances of Chinese word recognition were influenced by word frequency, age, and neighborhood density, with word frequency playing a major role. These results were consistent with those in other languages, supporting the application of NAM in the Chinese language. The development of Standard-Chinese version of LNT and the establishment of a database of children of 4-6 years old can provide a reliable means for spoken-word recognition test in children with hearing impairment. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  10. Enhanced high temperature performance of MgAl2O4-supported Pt-BaO lean NOx trap catalysts

    SciTech Connect

    Kwak, Ja Hun; Kim, Do Heui; Szanyi, Janos; Cho, Sung June; Peden, Charles HF

    2012-03-05

    The structural and chemical characteristics of Pt/BaO lean-NO{sub x} trap (LNT) catalysts supported on {gamma}-Al{sub 2}O{sub 3} and MgAl{sub 2}O{sub 4} are compared in this study. The Pt-BaO/MgAl{sub 2}O{sub 4} sample shows relatively low NO{sub x} uptake at temperatures below 300 C, and the temperature of maximum NO{sub x} uptake (T{sub max}) is shifted to 350 C in comparison to that of Pt-BaO/Al{sub 2}O{sub 3} (T{sub max} {approx}250 C). More importantly, the NO{sub x} uptake over the MgAl{sub 2}O{sub 4}-supported catalyst at 350 C is twice that of the alumina-based one. The shift toward the higher temperature NO{sub x} uptake is explained by the larger interfacial area between Pt and BaO, due to smaller Pt clusters as evidenced by TEM and Pt L3 EXAFS. In situ TR-XRD results demonstrate that the formation of a BaAl{sub 2}O{sub 4} phase in the BaO/MgAl{sub 2}O{sub 4} LNT catalyst occurs at a temperature about 100 C higher than on BaO/Al{sub 2}O{sub 3}, which may also represent a beneficial attribute of the BaO/MgAl{sub 2}O{sub 4} LNT with respect to catalyst stability.

  11. Controlled synthesis and photocatalytic investigation of different-shaped one-dimensional titanic acid nanomaterials

    NASA Astrophysics Data System (ADS)

    Li, Qiuye; Lu, Gongxuan

    Different-shaped one-dimensional (1D) titanic acid nanomaterials (TANs) were prepared by hydrothermal synthesis. By changing the reaction temperature (120, 170 and 200 °C), three kinds of 1D TAN, short-nanotubes (SNT), long-nanotubes (LNT), and nanorods (NR), were obtained. The obtained TANs were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), and solid-stated diffuse reflectance UV-vis spectra (UV-vis DRS) techniques. Based on these 1D TAN, Eosin Y-sensitized Pt-loaded TAN were prepared by the in situ impregnation and photo-reduction method. Their photocatalytic activity for hydrogen generation was evaluated in triethanolamine (TEOA) aqueous solution under visible light irradiation (λ ≥ 420 nm). The results indicated that the morphology difference led to a significant variation of photocatalytic performance for hydrogen generation, with the activity order as follows: Eosin Y-sensitized Pt-loaded LNT > Eosin Y-sensitized Pt-loaded NR > Eosin Y-sensitized Pt-loaded SNT. The experimental conditions for photocatalytic hydrogen generation such as Pt loading content, the mass ratio of Eosin Y to TAN, and so on, were optimized. As a result, the highest apparent quantum yields of hydrogen generation for Eosin Y-sensitized Pt-loaded SNT, LNT, and NR were 6.65, 17.36, and 15.04%, respectively. The stability of these photocatalysts and the reaction mechanism of the photocatalytic hydrogen generation are also discussed in detail.

  12. Future of Radiation Protection Regulations.

    PubMed

    Doss, Mohan

    2016-03-01

    THERE IS considerable disagreement in the scientific community regarding the carcinogenicity of low-dose radiation (LDR), with publications supporting opposing points of view. However, major flaws have been identified in many of the publications claiming increased cancer risk from LDR. The data generally recognized as the most important for assessing radiation effects in humans, the atomic bomb survivor data, are often cited to raise LDR cancer concerns. However, these data no longer support the linear no-threshold (LNT) model after the 2012 update but are consistent with radiation hormesis. Thus, a resolution of the controversy regarding the carcinogenicity of LDR appears to be imminent, with the rejection of the LNT model and acceptance of radiation hormesis. Hence, for setting radiation protection regulations, an alternative approach to the present one based on the LNT model is needed. One approach would be to determine the threshold dose for the carcinogenic effect of radiation from existing data and establish regulations to ensure radiation doses are kept well below the threshold dose. This can be done by setting dose guidelines specifying safe levels of radiation doses, with the requirement that these safe levels, referred to as guidance levels, not be exceeded significantly. Using this approach, a dose guidance level of 10 cGy for acute radiation exposures and 10 cGy y for exposures over extended periods of time are recommended. The concept of keeping doses as low as reasonably achievable, known as ALARA, would no longer be required for low-level radiation exposures not expected to exceed the dose guidance levels significantly. These regulations would facilitate studies using LDR for prevention and treatment of diseases. Results from such studies would be helpful in refining dose guidance levels. The dose guidance levels would be the same for the public and radiation workers to ensure everyone's safety.

  13. Strategies and Scientific Basis of Dose Reduction on State-of-the-Art Multirow Detector X-Ray CT Systems.

    PubMed

    Karamat, Muhammad Irfan

    2015-01-01

    The continued development in multirow detector computed tomography (MDCT) technology accompanied by tremendous enhancement in the clinical utility and rapid increase in the number of MDCT scanners worldwide are causing a steep rise in the number of diagnostic computed tomography (CT) procedures performed each year. The everincreasing use of this X-radiation-based imaging technique has raised radiation protection concerns among the clinical community and general public. To address these concerns, significant efforts have been made by the clinical community as well as industry, research, and government organizations. Because of these efforts, modern MDCT systems are now equipped with a variety of tools that can lead to "radiation dose-optimized" CT images if used properly. This review describes CT dose metrics and their limitations, radiation dose reduction techniques and strategies implemented using modern MDCT scanners, and the role of research and regulatory organizations in developing guidelines and regulations to facilitate the adoption of the dose reduction strategies. An account of further developments required to achieve submillisievert X-ray CT doses and to make X-ray CT a radiation risk-free imaging modality is also given. A detailed description of the scientific basis and controversies surrounding the linear no threshold (LNT) model, which forms the basis of all radiation dose reduction strategies, is also provided in this review. According to the LNT model, there is no amount of radiation that is safe or beneficial for human beings. Based on recent epidemiological studies, despite all of the controversies, the LNT model continues to be the basis of the ALARA (as low as reasonably achievable) principle of radiation protection framework in CT.

  14. High-Redundancy Draft Sequencing of 15 Clinical and Environmental Burkholderia Strains

    DTIC Science & Technology

    2010-12-01

    after a near-drowning incident (5). B. ubonensis strain Bu was isolated from a rhizosphere sam- ple from a mine site in northern Australia ( 12...species formerly known as the Oklahoma s1rain of Pseudomonas pseudoma- llei. lnt. J. Syst. Evol. Microhiol. 56:217l-217!i. 8. Howard. K .. and T. J. Inglis... Pseudomonas pseudoma- llei-lik.: organism isolated from the soil: case report and epidemiol(lgJc study J. Infect. Dis. l.lS:l03-l07. 15. Nussbaum, J. J

  15. Computer Aided Engineering of Semiconductor Integrated Circuits

    DTIC Science & Technology

    1976-04-01

    transistor opera tion; (4) theoretical invest! jations of carrifr mobli *!;y *"« inversion layer of an MOSFET; (5) mathematical investigations for high...satisfactory greLnt «Lh experiment. In time, the rapid groWth of se.r- oonduotor integrated circuit (IC, technology created ^ ^ °n" £or which this theory was...and Technology of Semiconductor Devices, John Wiley and Sons, Inc., N.Y. (1967). [2] S. K. Ghandi, The Theory and Practice of

  16. Region visited by a spherical Brownian particle in the presence of an absorbing boundary

    NASA Astrophysics Data System (ADS)

    Berezhkovskii, Alexander M.; Larralde, Hernan; Weiss, George H.

    2001-12-01

    We calculate the time dependence of the average volume of a Wiener sausage in the presence of an absorbing boundary in one and three dimensions. In one dimension it is shown that the presence of an absorbing point reduces the time dependence of the average span from being proportional to t in an unbounded space, to being proportional to ln(t) at long times. In three dimensions the average volume increases as t at long times rather than being proportional to t as in free space.

  17. DYNLET1: Dynamic Implicit Numerical Model of One-Dimensional Tidal Flow through Inlets

    DTIC Science & Technology

    1991-09-01

    tor)’ ), tdoiemrer il -0 Budogel Papie- -rrt Rfdro0 crn P-rJ,. C𔃾 ’~ ihn r r > 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND...MONITORING US Army Cors of r , Leers AGENCY REPORT NUMBER ",-ashi n4ton, 1)C :1314-1Ouo 11. SUPPLEMENTARY NOTES Avai[able from Natir.,nai Technicai...i rctan ce-’rve. quantitative studies o inlets rare pre orLnt.,. , :Au .c. 4I,, Ii ror its nL- lmenlsional mode lin1g of the ol’,’li’. I t ilt 5. r

  18. Commentary on Inhaled 239PuO2 in Dogs — A Prophylaxis against Lung Cancer?

    SciTech Connect

    Cuttler, Jerry M.; Feinendegen, Ludwig E.

    2015-01-01

    Several studies on the effect of inhaled plutonium-dioxide particulates and the incidence of lung tumors in dogs reveal beneficial effects when the cumulative alpha-radiation dose is low. There is a threshold at an exposure level of about 100 cGy for excess tumor incidence and reduced lifespan. The observations conform to the expectations of the radiation hormesis dose-response model and contradict the predictions of the LNT hypothesis. These studies suggest investigating the possibility of employing low-dose alpha-radiation, such as from 239PuO2 inhalation, as a prophylaxis against lung cancer.

  19. Commentary on Inhaled 239PuO2 in Dogs — A Prophylaxis against Lung Cancer?

    DOE PAGES

    Cuttler, Jerry M.; Feinendegen, Ludwig E.

    2015-01-01

    Several studies on the effect of inhaled plutonium-dioxide particulates and the incidence of lung tumors in dogs reveal beneficial effects when the cumulative alpha-radiation dose is low. There is a threshold at an exposure level of about 100 cGy for excess tumor incidence and reduced lifespan. The observations conform to the expectations of the radiation hormesis dose-response model and contradict the predictions of the LNT hypothesis. These studies suggest investigating the possibility of employing low-dose alpha-radiation, such as from 239PuO2 inhalation, as a prophylaxis against lung cancer.

  20. Multidimensional Many-Body Theory.

    DTIC Science & Technology

    1982-03-31

    which is for U n thro h the resolvent operator a unit matrix in the van Vleck case). The correspond- R 0) = Q )i (24) ing eigenfunctions k, of H are...Bent, G. D. Purvis, and R . J. Bartlett. J. Chem. Phys. 71, 3697 (1979). tions, beginning with Eq. (68) and using Eqs. (58) and 18j. A . Pople, J. S...expressed in any of the " R . Krishnan and J. A . Pople, Lnt. J. Quantum Chem. 14, 91 forms (1978). iot 20S. Wilson and D. M. Silver, J. Chem. Phvs. 66

  1. Maildriver: A Distributed Campus-Wide Mail System.

    DTIC Science & Technology

    1986-01-01

    Machine List (DM1). Then it creates a list for that machine, called the Dead Machine Catchup List (I)MCI), which will contain all actions which the dead...DoYouHavelt; /* list of files we couldn’t find a/ Queue *DMCL; /* array of Dead Machine Catchup Lists 5/ extern void EmergencyBailout0; nt FinishUpAndDie = 0... Catchup LI3t */ void MessageHandler(sig, fd) lnt sg, fd; { whatever message = read message from fd; switch(message) { "sending letter": "deleting letter

  2. Restructuring NATO Forces--Northern Tier

    DTIC Science & Technology

    1975-06-06

    attac. tbera „Ui, "uided weapons bevond thp r-in™ ^^ eyona the ran-e of weapon release for free fall ^ or direet fire ^ and roo.eta...Scjot,. „nlv iM free rort ln ^^ ^^ ^^^ to th« ocnann 1, at -,lrraanSk. u „an boen Cn^op«, lnt,0 an enormou£ "n-Uan.v bann...rather Orpheus , orGani?,atlo„s. hATO has not yet reached the ataße of Interdependence where national ^^li.ation Is a possibility

  3. CLEERS Aftertreatment Modeling and Analysis

    SciTech Connect

    Stewart, Mark L.; Zelenyuk, Alla; Gao, Feng; Muntean, George G.; Peden, Charles HF; Rappe, Kenneth G.; Szanyi, Janos; Howden, Ken

    2014-12-09

    CLEERS is an R&D focus project of the Diesel Cross-Cut Team. The overall objective is to promote the development of improved computational tools for simulating realistic full-system performance of lean-burn engines and the associated emissions control systems. Three fundamental research projects are sponsored at PNNL through CLEERS: DPF, SCR, and LNT. Resources are shared between the three efforts in order to actively respond to current industrial needs. This report documents recent results obtained during FY14.

  4. Detailed Analysis Plan for Validation of Close Air Support (CAS). Phase 2 Results

    DTIC Science & Technology

    1974-06-01

    CONMTL DATA PORN QUESTIONS LftIM/AIR b 1M MDRQUVEST PrASE RD, DIV OR CORPS (ALLOCATED RESOURCE ABORTS, ONLY) 1. Unit 1D No: 2. Location of TACP in UTM...Terminal Area Control (FAC(r) , PiC (A) , or ASRT) Type Control Call Sign Delay Abort CNX N/A Reason Codes Ist Znd 01 Cons Security 07 lnt’rm’t Com 14...NETWORK FOR ATTACK HELICOPTER CAB - DATA PORN QUESTIONS TO ANNEX C[ DATA COLLECTION CIoS CABA D AND CONTROL DATA FOlRM QUESTIONS No. 1-2-3-4-S.-6* ARMY

  5. Commentary on Inhaled 239PUO2 in Dogs — A Prophylaxis Against Lung Cancer?

    PubMed Central

    Feinendegen, Ludwig E.

    2015-01-01

    Several studies on the effect of inhaled plutonium-dioxide particulates and the incidence of lung tumors in dogs reveal beneficial effects when the cumulative alpha-radiation dose is low. There is a threshold at an exposure level of about 100 cGy for excess tumor incidence and reduced lifespan. The observations conform to the expectations of the radiation hormesis dose-response model and contradict the predictions of the LNT hypothesis. These studies suggest investigating the possibility of employing low-dose alpha-radiation, such as from 239PuO2 inhalation, as a prophylaxis against lung cancer. PMID:26675366

  6. CLEERS Aftertreatment Modeling and Analysis

    SciTech Connect

    Muntean, George G.; Devarakonda, Maruthi N.; Gao, Feng; Kwak, Ja Hun; Luo, Jin-Yong; Peden, Charles HF; Stewart, Mark L.; Szanyi, Janos; Tran, Diana N.; Howden, Ken

    2012-12-31

    CLEERS is a research and development focus project of the Diesel Cross-Cut Team. The overall objective is to promote the development of improved computational tools for simulating realistic full-system performance of lean-burn engines and the associated emissions control systems. Three fundamental research projects are sponsored at PNNL through CLEERS: DPF, SCR, and LNT. Resources are shared between the three efforts in order to actively respond to current industrial needs. In FY 2012, primary emphasis continued to be placed on the SCR activities because of urgent application issues associated with these technologies.

  7. Prime Contract Awards Alphabetically by Contractor, by State or Country, and Place, Fiscal Year 1987. Part 6. Donnegan Systems, Incorporated-Fairfield Machine Company, Incorporated.

    DTIC Science & Technology

    1987-01-01

    U) -w 4l C O - 0) -w C-c CAN CAN M~C 1,- : o 0 N j ON >0.-i D Ui -4L. ’ u 3 0 0w 0 ZCC 2101 V.) I ) > -)I -. w.l L ’-.Z 10 20000 .JZ .1*.... u U...40) 0)NŔ) M0)C0)() 0) 0) 0) 0) 01 M F- InC J) U Y) M ) -40 0a)40))M-a) Itil X.- a)) Q 0 n0 a000 0 00000 C000r r- t-4 < 0 0n < - 4oooLnLntLnkn<A CO UI

  8. Changing the Risk Paradigms Can be Good for Our Health: J-Shaped, Linear and Threshold Dose-Response Models.

    PubMed

    Ricci, P F; Straja, S R; Cox, A L

    2012-01-01

    Both the linear (at low doses)-no-threshold (LNT) and the threshold models (S-shapes) dose-response lead to no benefit from low exposure. We propose three new models that allow and include, but do not require - unlike LNT and S-shaped models - this strong assumption. We also provide the means to calculate benefits associated with bi-phasic biological behaviors, when they occur and propose:THREE HORMETIC (PHASIC) MODELS: the J-shaped, inverse J-shaped, the min-max, andMethod for calculating the direct benefits associated with the J and inverse J-shaped models.The J-shaped and min-max models for mutagens and carcinogenic agents include an experimentally justified repair stage for toxic and carcinogenic damage. We link these to stochastic transition models for cancer and show how abrupt transitions in cancer hazard rates, as functions of exposure concentrations and durations, can emerge naturally in large cell populations even when the rates of cell-level events increase smoothly (e.g., proportionally) with concentration. In this very general family of models, J-shaped dose-response curves emerge. These results are universal, i.e., independent of specific biological details represented by the stochastic transition networks. Thus, using them suggests a more complete and realistic way to assess risks at low doses or dose-rates.

  9. Could time itself be logarithmic?

    NASA Astrophysics Data System (ADS)

    George, William

    2016-11-01

    This presentation hypothesizes that increments of time may be logarithmic and measured from an initial instant - the log of absolute time if you will. In this alternative view all equations involving time must be written with lnt /to where t is measured in linear increments from the beginning of the universe and to is the universal time scale. All equations involving time derivatives must be written not as d / dt but d / dlnt / to = td / dt . An immediate consequence, for example, is that our definition of mass in Newton's Law must change as well: from mdv / dt = F to m* dv / dlnt / to =m* tdv / dt = F where F is force applied and v is velocity (however defined). m* = m / t is the 'true' or absolute mass. Since we have been measuring for only about 500 years and the universe is estimated to be about 18 billion years (millions of billions of seconds) old, the differences are impossible to measure; i.e., ln (t + δt) - lnt δt / t . It is only when we look backwards towards the beginning of the universe that we notice the difference - mass, m =m* t , appears to be missing. So we need "dark matter" to make our equations balance - when in fact it might be our "linear-time" equations and definitions that are wrong.

  10. Ion-beam synthesis of zinc-based nanoparticles in SiO2

    NASA Astrophysics Data System (ADS)

    Czarnacka, Karolina; Makhavikou, Maksim A.; Komarov, Fadei F.

    2016-12-01

    In this paper production process of Zn nanocrystals in SiO2 by using an implantation of high dose zinc ions with energy of 130 keV and annealing process in 700°C were described. Using electron microscopy was established that annealing causes extension of admixtures distribution on depth and zinc nanoparticles size increasing from approx. 1 - 6 nm to 12 - 18 nm. For prepared material AC conductivity measurements were made in temperatures range from liquid nitride temperature (LNT) to 373 K and at frequencies range from 50 Hz to 5 MHz. Strong frequency dependence on conductivity proves that in this nanocomposite Zn-SiO2 conduction takes place by electron hopping exchange (tunneling) between metallic phase nanoparticles. It was established that three activation energies of conductivity occurs in temperatures range of LNT - 373 K - in low temperatures ΔE1≍0.001 eV, in medium temperatures ΔE2≍0.025 eV and in higher temperatures area ΔE3≍0.096 eV. This is due to the presence of at least two types of nanoparticles. First there are zinc nanoparticles with zinc oxide coating, second there are nanoparticles without the coating. The highest activation energy occurs during electrons tunneling between nanoparticles with zinc oxide coating. Intermediate activation energy corresponds to tunneling from nanoparticle with coating to nanoparticle without coating or conversely. The lowest activation energy corresponds to electrons hopping between nanoparticles without coatings.

  11. Evidence supporting radiation hormesis in atomic bomb survivor cancer mortality data.

    PubMed

    Doss, Mohan

    2012-12-01

    A recent update on the atomic bomb survivor cancer mortality data has concluded that excess relative risk (ERR) for solid cancers increases linearly with dose and that zero dose is the best estimate for the threshold, apparently validating the present use of the linear no threshold (LNT) model for estimating the cancer risk from low dose radiation. A major flaw in the standard ERR formalism for estimating cancer risk from radiation (and other carcinogens) is that it ignores the potential for a large systematic bias in the measured baseline cancer mortality rate, which can have a major effect on the ERR values. Cancer rates are highly variable from year to year and between adjacent regions and so the likelihood of such a bias is high. Calculations show that a correction for such a bias can lower the ERRs in the atomic bomb survivor data to negative values for intermediate doses. This is consistent with the phenomenon of radiation hormesis, providing a rational explanation for the decreased risk of cancer observed at intermediate doses for which there is no explanation based on the LNT model. The recent atomic bomb survivor data provides additional evidence for radiation hormesis in humans.

  12. Radon Treatment Controversy

    PubMed Central

    Zdrojewicz, Zygmunt; Strzelczyk, Jadwiga (Jodi)

    2006-01-01

    In spite of long traditions, treatments utilizing radon-rich air or water have not been unequivocally embraced by modern medicine. The objective of this work is to examine factors that contribute to this continuing controversy. While the exact mechanism of radon's effect on human body is not completely understood, recent advances in radiobiology offer new insights into biochemical processes occurring at low-level exposures to ionizing radiation. Medical evidence and patients' testimonials regarding effectiveness of radon spa treatments of various ailments, most notably rheumatoid arthritis are accumulating worldwide. They challenge the premise of the Linear-No-Threshold (LNT) theory that the dose-effect response is the same per unit dose regardless of the total dose. Historically, such inference overshadowed scientific inquiries into the low-dose region and lead to a popular belief that no amount of radiation can be good. Fortunately, the LNT theory, which lacks any scientific basis, did not remain unchallenged. As the reviewed literature suggests, a paradigm shift, reflected in the consideration of hormetic effects at low-doses, is gaining momentum in the scientific community worldwide. The impetus comes from significant evidence of adaptive and stimulatory effects of low-levels of radiation on human immune system. PMID:18648641

  13. Aminoacylation of the N-terminal cysteine is essential for Lol-dependent release of lipoproteins from membranes but does not depend on lipoprotein sorting signals.

    PubMed

    Fukuda, Ayumu; Matsuyama, Shin-Ichi; Hara, Takashi; Nakayama, Jiro; Nagasawa, Hiromichi; Tokuda, Hajime

    2002-11-08

    Lipoproteins are present in a wide variety of bacteria and are anchored to membranes through lipids attached to the N-terminal cysteine. The Lol system of Escherichia coli mediates the membrane-specific localization of lipoproteins. Aspartate at position 2 functions as a Lol avoidance signal and causes the retention of lipoproteins in the inner membrane, whereas lipoproteins having residues other than aspartate at position 2 are released from the inner membrane and localized to the outer membrane by the Lol system. Phospholipid:apolipoprotein transacylase, Lnt, catalyzes the last step of lipoprotein modification, converting apolipoprotein into mature lipoprotein. To reveal the importance of this aminoacylation for the Lol-dependent membrane localization, apolipoproteins were prepared by inhibiting lipoprotein maturation. Lnt was also purified and used to convert apolipoprotein into mature lipoprotein in vitro. The release of these lipoproteins was examined in proteoliposomes. We show here that the aminoacylation is essential for the Lol-dependent release of lipoproteins from membranes. Furthermore, lipoproteins with aspartate at position 2 were found to be aminoacylated both in vivo and in vitro, indicating that the lipoprotein-sorting signal does not affect lipid modification.

  14. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. Part VI: FT-IR spectra of isomorphously isolated species. NH4+ ions isolated in MKPO 4·6H 2O (M = Mg; Ni) and PO43- ions isolated in MgNH 4AsO 4·6H 2O

    NASA Astrophysics Data System (ADS)

    Cahil, A.; Šoptrajanov, B.; Najdoski, M.; Lutz, H. D.; Engelen, B.; Stefov, V.

    2008-03-01

    Examination of mixed crystals, especially those with isomorphously isolated ions, has proved very useful in spectra-structure correlation studies. Room (RT) and low temperature (LNT) FT-IR spectra of ammonium doped in MgKPO 4·6H 2O and NiKPO 4·6H 2O and phosphate doped in MgNH 4AsO 4·6H 2O in different degrees were recorded. All three compounds are isostructural with struvite, MgNH 4PO 4·6H 2O, space group Pmn2 1, forming substitutional mixed crystals with Cs symmetry of the anions. Analysis of the region of ν 4(NH 4), ν 3(PO 4) and ν 4(PO 4) modes of LNT FT-IR difference spectra of analogues with a small content of NH4+ and PO43- revealed the expected decrease of Td symmetry of free NH4+ and PO43- ions to Cs site symmetry. Due to the Cs site symmetry of the anions, the degeneration of the ν 4(NH 4), ν 3PO 4) and ν 4PO 4) modes is raised and, hence, three components are observed in the difference FT-IR spectra. This conclusion can not be derived only from studies of no-doped polycrystalline samples of struvite type compounds.

  15. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate ( struvite) and its isomorphous analogues. IV. FTIR spectra of protiated and partially deuterated nickel ammonium phosphate hexahydrate and nickel potassium phosphate hexahydrate

    NASA Astrophysics Data System (ADS)

    Cahil, A.; Najdoski, M.; Stefov, V.

    2007-05-01

    The Fourier transform infrared spectra recorded from room temperature down to the boiling temperature of liquid nitrogen of two struvite analogues, nickel ammonium phosphate hexahydrate (NiNH 4PO 4·6H 2O) and nickel potassium phosphate hexahydrate (NiKPO 4·6H 2O) and their partially deuterated analogues were analyzed and compared to the previously studied spectra of struvite and its potassium analogue. In the stretching mode region of the water molecules and ammonium ions, a broad asymmetric and deuteration sensitive band appears, which is an indication for strong hydrogen bonds in the structure of NiNP. In the LNT difference spectra of samples with low deuterium content (≈2-3% D), several bands appear between 2520 and 2080 cm -1 due to vibrations of isotopically isolated HDO molecules and NH 3D + ions. The most significant difference between the two studied spectra is between 2350 and 2250 cm -1 where additional bands from ND stretching modes of isotopically isolated NH 3D + ions are expected in the spectrum of NiNP. In the region of ν3(PO 4) modes one strong, slightly asymmetric, temperature-sensitive band appears above 1000 cm -1 in both spectra. The analysis of the RT and LNT spectra of the protiated and partially deuterated compounds, the band at around 575 cm -1 is assigned to the ν4(PO 4) modes and the remaining ones as due to librational and translational modes of the water molecules.

  16. [Clinical trial of non-specific immunotherapy using Lentinan in advanced or recurrent gastric cancer].

    PubMed

    Yoshino, Shigefumi; Oka, Masaaki

    2008-11-01

    Randomized phase III study of S-1 alone versus S-1 plus Lentinan (LNT) in advanced or recurrent gastric cancer started in February 2007 conducted by the Japanese Foundation for Multidisciplinary Treatment of Cancer. The objective of this study is to evaluate the superiority of S-1/LNT to S-1 alone. The primary end point is to compare over all survival between both treatment groups. Secondary end points include time to treatment failure, the grade and rate of the adverse events, the evaluation of quality of life (QOL), response rate evaluated by RECIST and immunological parameters. QOL is evaluated by Japanese version of FACT-BRM questionnaire. Immunological parameters include serum complements (CH50, C3) and beta-1, 3 binding monocytes. The sample size is estimated at 150 patients per arm. Registration period is 2 years with 2-year follow-up. This study has a chance to prove the efficacy of the non-specific biological response modifier. We will have to cooperate in order to make this study a success.

  17. Enzyme catalysed production of sialylated human milk oligosaccharides and galactooligosaccharides by Trypanosoma cruzi trans-sialidase.

    PubMed

    Holck, Jesper; Larsen, Dorte M; Michalak, Malwina; Li, Haiying; Kjærulff, Louise; Kirpekar, Finn; Gotfredsen, Charlotte H; Forssten, Sofia; Ouwehand, Arthur C; Mikkelsen, Jørn D; Meyer, Anne S

    2014-03-25

    A Trypanosoma cruzi trans-sialidase (E.C. 3.2.1.18) was cloned into Pichia pastoris and expressed. The pH and temperature optimum of the enzyme was determined as pH 5.7 and 30°C. Using casein glycomacropeptide (CGMP) and lactose as sialyl-donor and acceptor respectively, the optimal donor/acceptor ratio for the trans-sialidase catalysed 3'-sialyllactose production was found to be 1:4. Quantitative amounts of 3'-sialyllactose were produced from CGMP and lactose at a yield of 40mg/g CGMP. The 3'-sialyllactose obtained exerted a stimulatory effect on selected probiotic strains, including different Bifidobacterium strains in single culture fermentations. The trans-sialidase also catalysed the transfer of sialic acid from CGMP to galacto-oligosaccharides (GOS) and to the human milk oligosaccharide (HMO) backbone lacto-N-tetraose (LNT) to produce 3'-sialyl-GOS, including doubly sialylated GOS products, and 3'-sialyl-LNT, respectively. This work thus provides proof of the concept of producing 3'-sialyllactose and potentially other sialylated HMOs as well as sialylated GOS enzymatically by trans-sialidase activity, while at the same time providing valorisation of CGMP, a co-processing product from cheese manufacture.

  18. Oscillatory characteristics of metallic nanoparticles inside lipid nanotubes

    NASA Astrophysics Data System (ADS)

    Sadeghi, Fatemeh; Ansari, Reza; Darvizeh, Mansour

    2015-12-01

    This study is concerned with the oscillatory behavior of metallic nanoparticles, and in particular silver and gold nanoparticles, inside lipid nanotubes (LNTs) using the continuum approximation along with the 6-12 Lennard-Jones (LJ) potential function. The nanoparticle is modeled as a dense sphere and the LNT is assumed to be comprised of six layers including two head groups, two intermediate layers and two tail groups. To evaluate van der Waals (vdW) interactions, analytical expressions are first derived through undertaking surface and volume integrals which are then validated by a fully numerical scheme based on the differential quadrature (DQ) technique. Using the actual force distribution between the two interacting molecules, the equation of motion is directly solved utilizing the Runge-Kutta numerical integration scheme to arrive at the time history of displacement and velocity of the inner core. Also, a semi-analytical expression incorporating both geometrical parameters and initial conditions is introduced for the precise evaluation of oscillation frequency. A comprehensive study is conducted to gain an insight into the influences of nanoparticle radius, LNT length, head and tail group thicknesses and initial conditions on the oscillatory behavior of the metallic nanoparticles inside LNTs. It is found that the escape velocity and oscillation frequency of silver nanoparticles are higher than those of gold ones. It is further shown that the oscillation frequency is less affected by the tail group thickness when compared to the head group thickness.

  19. The Effect of Short-Term Auditory Training on Speech in Noise Perception and Cortical Auditory Evoked Potentials in Adults with Cochlear Implants.

    PubMed

    Barlow, Nathan; Purdy, Suzanne C; Sharma, Mridula; Giles, Ellen; Narne, Vijay

    2016-02-01

    This study investigated whether a short intensive psychophysical auditory training program is associated with speech perception benefits and changes in cortical auditory evoked potentials (CAEPs) in adult cochlear implant (CI) users. Ten adult implant recipients trained approximately 7 hours on psychophysical tasks (Gap-in-Noise Detection, Frequency Discrimination, Spectral Rippled Noise [SRN], Iterated Rippled Noise, Temporal Modulation). Speech performance was assessed before and after training using Lexical Neighborhood Test (LNT) words in quiet and in eight-speaker babble. CAEPs evoked by a natural speech stimulus /baba/ with varying syllable stress were assessed pre- and post-training, in quiet and in noise. SRN psychophysical thresholds showed a significant improvement (78% on average) over the training period, but performance on other psychophysical tasks did not change. LNT scores in noise improved significantly post-training by 11% on average compared with three pretraining baseline measures. N1P2 amplitude changed post-training for /baba/ in quiet (p = 0.005, visit 3 pretraining versus visit 4 post-training). CAEP changes did not correlate with behavioral measures. CI recipients' clinical records indicated a plateau in speech perception performance prior to participation in the study. A short period of intensive psychophysical training produced small but significant gains in speech perception in noise and spectral discrimination ability. There remain questions about the most appropriate type of training and the duration or dosage of training that provides the most robust outcomes for adults with CIs.

  20. Impact strength of denture base and reline acrylic resins: An in vitro study

    PubMed Central

    Bochio, Bruna C; Wady, Amanda F; Jorge, Janaina H; Canevarolo, Sebastião V; Vergani, Carlos E

    2012-01-01

    This study evaluated the impact strength of a denture base resin (Lucitone 550—L) and four reline resins (Tokuyama Rebase II—T; Ufi Gel Hard—U; New Truliner—NT, and Kooliner—K), both intact and in a reline combination (L/L, L/T, L/U, L/NT, and L/K). For each group (n = 20), half of the specimens were thermocycled before testing. Charpy tests were performed, and the impact strengths were calculated. Data were analyzed by two-way analyses of variance and Tukey’s test (p = 0.05). For the intact groups, mean impact strength values for L (1.65 and 1.50) were significantly higher than those of the reline resins (0.38–1.17). For the relined groups, the highest mean impact strength values were produced by L/T (5.76 and 5.12), L/NT (6.20 and 6.03), and L/K (5.60 and 5.31) and the lowest by L/U (0.76 and 0.78). There were no significant differences between L and L/L. Thermocycling reduced the impact strength of T (from 0.73 to 0.38) and L/L (from 1.82 to 1.56). PMID:22977461

  1. Simulating Study of Premixed Charge Compression Ignition on Light-Duty Diesel Fuel Economy and Emissions Control

    SciTech Connect

    Gao, Zhiming; Daw, C Stuart; Wagner, Robert M

    2012-01-01

    We utilize the Powertrain Systems Analysis Toolkit (PSAT) combined with transient engine and aftertreatment component models to simulate the impact of premixed charge compression ignition (PCCI) on the fuel economy and emissions of light-duty (LD) diesel-powered conventional and hybrid electric vehicles (HEVs). Our simulated aftertreatment train consists of a diesel oxidation catalyst (DOC), lean NOx trap (LNT), and catalyzed diesel particulate filter (DPF). The results indicate that utilizing PCCI combustion significantly reduces fuel consumption and tailpipe emissions for the conventional diesel-powered vehicle with NOx and particulate emissions controls. These benefits result from a favorable engine speed-load distribution over the cycle combined with a corresponding reduction in the need to regenerate the LNT and DPF. However, the current PCCI technology appears to offer less potential benefit for diesel HEVs equipped with similar emissions controls. This is because PCCI can only be activated over a relatively small part of the drive cycle. Thus we conclude that future utilization of PCCI in diesel HEVs will require significant extension of the available speed-load range for PCCI and revision of current HEV engine management strategies before significant benefits can be realized.

  2. Simulating the Impact of Premixed Charge Compression Ignition on Light-Duty Diesel Fuel Economy and Emissions of Particulates and NOx

    SciTech Connect

    Gao, Zhiming; Daw, C Stuart; Wagner, Robert M; Edwards, Kevin Dean; Smith, David E

    2013-01-01

    We utilize the Powertrain Systems Analysis Toolkit (PSAT) combined with transient engine and aftertreatment component models implemented in Matlab/Simulink to simulate the effect of premixed charge compression ignition (PCCI) on the fuel economy and emissions of light-duty diesel-powered conventional and hybrid electric vehicles (HEVs). Our simulated engine is capable of both conventional diesel combustion (CDC) and premixed charge compression ignition (PCCI) over real transient driving cycles. Our simulated aftertreatment train consists of a diesel oxidation catalyst (DOC), lean NOx trap (LNT), and catalyzed diesel particulate filter (DPF). The results demonstrate that, in the simulated conventional vehicle, PCCI can significantly reduce fuel consumption and emissions by reducing the need for LNT and DPF regeneration. However, the opportunity for PCCI operation in the simulated HEV is limited because the engine typically experiences higher loads and multiple stop-start transients that are outside the allowable PCCI operating range. Thus developing ways of extending the PCCI operating range combined with improved control strategies for engine and emissions control management will be especially important for realizing the potential benefits of PCCI in HEVs.

  3. Crystal Structure and Anisotropic c--f Hybridization in CeT2Al10 (T=Ru, Fe)

    NASA Astrophysics Data System (ADS)

    Sera, Masafumi; Tanaka, Daiki; Tanida, Hiroshi; Moriyoshi, Chikako; Ogawa, Mayuko; Kuroiwa, Yoshihiro; Nishioka, Takashi; Matsumura, Masahiro; Kim, Jungeun; Tsuji, Naruki; Takata, Masaki

    2013-02-01

    We have performed the investigation of the charge density distribution of CeT2Al10 (T=Ru, Fe) and the crystal structure parameters of LnT2Al10. The lattice parameters of a-, b-, and c-axes exhibit the anisotropic contraction when Ru is replaced by Fe in LnT2Al10, different from the isotropic contraction simply expected from the smaller ionic radius of Fe than Ru. The contraction is larger in the a- and c-axes than in the b-axis. This anisotropic contraction of the YbFe2Al10-type crystal structure originates from the zigzag degree of the zigzag chain formed by T and Al bond along the a- and c-axes are larger than that along the b-axis. The lattice parameters of CeT2Al10 (T=Ru, Fe) exhibit the anisotropic deviation from the lanthanide contraction. The deviation is largest in the a-axis and is very small in the b-axis. Both the characteristic YbFe2Al10-type crystal structure and the anisotropic deviation towards the intermediate valence indicate that the largest c--f hybridization along the a-axis plays the important role and is associated with the unusual antiferromagnetic order in CeT2Al10 (T=Ru, Os).

  4. Preserving the Anti-Scientific Linear No-Threshold Myth: Authority, Agnosticism, Transparency, and the Standard of Care

    PubMed Central

    Siegel, Jeffry A.

    2017-01-01

    The linear no-threshold (LNT) assumption is over 70 years old and holds that all ionizing radiation exposure leaves cumulative effects, all of which are harmful regardless of how low the dose or dose rate is. The claimed harm centers on the risk of future radiogenic cancer. This has been shown countless times to be fallacious, and hundreds of scientific studies—both experimental and observational/epidemiological—demonstrate that at low enough doses and dose rates, ionizing radiation stimulates an evolved adaptive response and therefore is beneficial to health, lowering rather than raising the risk of cancer. Yet the myth of uncorrected lifetime cumulative risk still pervades the field of radiation science and underlies the policies of virtually all regulatory agencies around the world. This article explores some of the motivations behind, and methods used to assure, the extreme durability of the LNT myth in the face of the preponderance of contrary evidence and the manifest harms of radiophobia. These include subservience to the voice of authority, tactics such as claiming agnosticism on behalf of the entire field, transparent references to contrary evidence while dismissing the findings without refutation, and seeking shelter behind the legally protective medical standard of care. PMID:28814947

  5. The Effect of Short-Term Auditory Training on Speech in Noise Perception and Cortical Auditory Evoked Potentials in Adults with Cochlear Implants

    PubMed Central

    Barlow, Nathan; Purdy, Suzanne C.; Sharma, Mridula; Giles, Ellen; Narne, Vijay

    2016-01-01

    This study investigated whether a short intensive psychophysical auditory training program is associated with speech perception benefits and changes in cortical auditory evoked potentials (CAEPs) in adult cochlear implant (CI) users. Ten adult implant recipients trained approximately 7 hours on psychophysical tasks (Gap-in-Noise Detection, Frequency Discrimination, Spectral Rippled Noise [SRN], Iterated Rippled Noise, Temporal Modulation). Speech performance was assessed before and after training using Lexical Neighborhood Test (LNT) words in quiet and in eight-speaker babble. CAEPs evoked by a natural speech stimulus /baba/ with varying syllable stress were assessed pre- and post-training, in quiet and in noise. SRN psychophysical thresholds showed a significant improvement (78% on average) over the training period, but performance on other psychophysical tasks did not change. LNT scores in noise improved significantly post-training by 11% on average compared with three pretraining baseline measures. N1P2 amplitude changed post-training for /baba/ in quiet (p = 0.005, visit 3 pretraining versus visit 4 post-training). CAEP changes did not correlate with behavioral measures. CI recipients' clinical records indicated a plateau in speech perception performance prior to participation in the study. A short period of intensive psychophysical training produced small but significant gains in speech perception in noise and spectral discrimination ability. There remain questions about the most appropriate type of training and the duration or dosage of training that provides the most robust outcomes for adults with CIs. PMID:27587925

  6. Preserving the Anti-Scientific Linear No-Threshold Myth: Authority, Agnosticism, Transparency, and the Standard of Care.

    PubMed

    Sacks, Bill; Siegel, Jeffry A

    2017-01-01

    The linear no-threshold (LNT) assumption is over 70 years old and holds that all ionizing radiation exposure leaves cumulative effects, all of which are harmful regardless of how low the dose or dose rate is. The claimed harm centers on the risk of future radiogenic cancer. This has been shown countless times to be fallacious, and hundreds of scientific studies-both experimental and observational/epidemiological-demonstrate that at low enough doses and dose rates, ionizing radiation stimulates an evolved adaptive response and therefore is beneficial to health, lowering rather than raising the risk of cancer. Yet the myth of uncorrected lifetime cumulative risk still pervades the field of radiation science and underlies the policies of virtually all regulatory agencies around the world. This article explores some of the motivations behind, and methods used to assure, the extreme durability of the LNT myth in the face of the preponderance of contrary evidence and the manifest harms of radiophobia. These include subservience to the voice of authority, tactics such as claiming agnosticism on behalf of the entire field, transparent references to contrary evidence while dismissing the findings without refutation, and seeking shelter behind the legally protective medical standard of care.

  7. Experimental realization of nearly steady-state toroidal electron plasmas

    SciTech Connect

    Stoneking, M. R.; Ha, B. N.; Smoniewski, J.; Marler, J. P.

    2009-05-15

    Electron plasmas with densities of 5x10{sup 6} cm{sup -3} are trapped in the Lawrence Non-neutral Torus II (LNT II) for times exceeding 1 s. LNT II is a high aspect ratio (R{sub 0}/a > or approx.10) partially toroidal trap (270 deg. arc, B{sub 0}=670 G). The m=1 diocotron mode is launched and detected using isolated segments of a fully sectored conducting boundary and its frequency is used to determine the total trapped charge as a function of time. The observed confinement time ({approx_equal}3 s) approaches the theoretical limit ({approx_equal}6 s) set by the magnetic pumping transport mechanism of Crooks and O'Neil [Phys. Plasmas 3, 2533 (1996)]. We also present equilibrium modeling and numerical simulations of the toroidal m=1 mode constrained by experimental data. Future work includes the identification of the dominant transport mechanisms via confinement scaling experiments and measurement of the m=2 mode frequency and development of a strategy for making a transition to fully toroidal confinement.

  8. Urgent Change Needed to Radiation Protection Policy.

    PubMed

    Cuttler, Jerry M

    2016-03-01

    Although almost 120 y of medical experience and data exist on human exposure to ionizing radiation, advisory bodies and regulators claim there are still significant uncertainties about radiation health risks that require extreme precautions be taken. Decades of evidence led to recommendations in the 1920s for protecting radiologists by limiting their daily exposure. These were shown in later studies to decrease both their overall mortality and cancer mortality below those of unexposed groups. In the 1950s, without scientific evidence, the National Academy of Sciences Biological Effects of Atomic Radiation (BEAR) Committee and the NCRP recommended that the linear no-threshold (LNT) model be used to assess the risk of radiation-induced mutations in germ cells and the risk of cancer in somatic cells. This policy change was accepted by the regulators of every country without a thorough review of its basis. Because use of the LNT model has created extreme public fear of radiation, which impairs vital medical applications of low-dose radiation in diagnostics and therapy and blocks nuclear energy projects, it is time to change radiation protection policy back into line with the data.

  9. Effect of reductive treatments on Pt behavior and NOx storage in lean NOx trap catalysts

    SciTech Connect

    Wang, Xianqin; Kim, Do Heui; Kwak, Ja Hun; Wang, Chong M.; Szanyi, Janos; Peden, Charles HF

    2011-10-01

    Lean NOx trap (LNT) catalysts represent a promising approach to meet increasingly stringent NOx emission regulations on diesel and other lean-burn engines. Pt material properties, including dispersion and particle size, are known to be important factors in determining NOx uptake performance, since Pt provides active sites for NO oxidation to NO2 necessary for storing NOx as nitrates, and for the reduction of nitrates to N2. In this work, the physicochemical properties of Pt in Pt-BaO/Al2O3 LNT catalysts, such as the Pt accessible surface area and particle size, were investigated by using various tools, such as irreversible volumetric H2 chemisorption, high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), following successive reductive treatments at elevated temperatures. NOx uptake activities were also measured to establish a relationship between the properties of Pt and NOx storage following identical high-temperature reductive treatments. We find that the reductive treatments of Pt-BaO/Al2O3 lean NOx trap catalysts at temperatures up to 500 ºC promote a significant increase in NOx uptake explained, in part, by an induced close interaction between Pt and BaO phases in the catalyst, thus enabling facilitation of the NOx storage process.

  10. Microkinetic Modeling of Lean NOx Trap Storage and Regeneration

    SciTech Connect

    Larson, Richard S.; Chakravarthy, V. Kalyana; Pihl, Josh A.; Daw, C. Stuart

    2011-12-01

    A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NOx trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NOx storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code (including boundary layer mass transfer) to simulate not only a set of long storage/regeneration cycles with a CO/H2 reductant, but also a series of steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code neglecting mass transfer. The results show that, while mass transfer effects are generally minor, NOx storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with the transient simulations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants.

  11. Implications of Low Particulate Matter Emissions on System Fuel Efficiency for High Efficiency Clean Combustion

    SciTech Connect

    Parks, II, James E; Prikhodko, Vitaly Y

    2009-01-01

    Advanced diesel combustion regimes such as High Efficiency Clean Combustion (HECC) offer the benefits of reduced engine out NOX and particulate matter (PM) emissions. Lower PM emissions during advanced combustion reduce the demand on diesel particulate filters (DPFs) and can, thereby, reduce the fuel penalty associated with DPF regeneration. In this study, a SiC DPF was loaded and regenerated on a 1.7-liter 4-cylinder diesel engine operated in conventional and advanced combustion modes at different speed and load conditions. A diesel oxidation catalyst (DOC) and a lean NOX trap (LNT) were also installed in the exhaust stream. Five steady-state speed and load conditions were weighted to estimate Federal Test Procedure (FTP) fuel efficiency. The DPF was loaded using lean-rich cycling with frequencies that resulted in similar levels of NOX emissions downstream of the LNT. The pressure drop across the DPF was measured at a standard point (1500 rpm, 5.0 bar) before and after loading, and a P rise rate was determined for comparison between conventional and advanced combustion modes. Higher PM emissions in conventional combustion resulted in a higher rate of backpressure rise across the DPF at all of the load points leading to more frequent DPF regenerations and higher fuel penalty. The fuel penalty during conventional combustion was 4.2% compared with 3.1% for a mixture of conventional and advanced modes.

  12. Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

    SciTech Connect

    Larson, Rich; Daw, C. Stuart; Pihl, Josh A.; Chakravarthy, V. Kalyana

    2011-08-01

    A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO{sub x} trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NO{sub x} storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code to simulate not only conventional storage/regeneration cycles with a CO/H{sub 2} reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code. The results show that NO{sub x} storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with these purely kinetic simulations, i.e., without including mass-transfer limitations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants.

  13. Longitudinal change of selected human milk oligosaccharides and association to infants' growth, an observatory, single center, longitudinal cohort study.

    PubMed

    Sprenger, Norbert; Lee, Le Ye; De Castro, Carlos Antonio; Steenhout, Philippe; Thakkar, Sagar K

    2017-01-01

    Human milk is the recommended and sole nutrient source for newborns. One of the largest components of human milk is oligosaccharides (HMOs) with major constituents determined by the mother genotype for the fucosyltransferase 2 (FUT2, secretor) gene. HMO variation has been related with infant microbiota establishment, diarrhea incidence, morbidity and mortality, IgE associated eczema and body composition. We investigated the (i) dependence of several major representative HMOs on the FUT2 status assessed through breast milk 2'Fucosyllactose (2'FL) and (ii) the relation of the 2'FL status with infant growth up to 4 months of life. From an open observatory, single center, longitudinal cohort study with quantitative human milk collection at 30, 60, and 120 days postpartum from 50 mothers, who gave birth to 25 female and 25 male singleton infants, we collected a representative sample of human milk. We quantified the following 5 representative HMOs: 2'FL, Lacto-N-tetraose (LNT), Lacto-N-neotetraose (LNnT), 3'Sialyllactose (3'SL) and 6'Sialyllactose (6'SL). We grouped the milk samples and corresponding infants according to the measured milk 2'FL concentrations at 30 days of lactation, which clustered around low concentrations (95% CI of mean 12-42 mg/L) and high concentrations (95% CI of mean 1880-2460 mg/L) with the former likely representing Secretor negative mothers. Infant anthropometric measures were recorded at birth, 1, 2 and 4 months of age. Relations among the quantified HMOs and the relation of the high and low 2'FL HMOs groups with infant growth parameters were investigated via linear mixed models. The milk samples with low 2'FL concentration had higher LNT and lower LNnT concentrations compared to the samples with high 2'FL. The milk 3'- and 6'SL concentrations were independent of 2'FL. Over lactation time we observed a drop in the concentration of 2'FL, LNT, LNnT and 6'SL, especially from 1 to 2 months, while 3'SL remained at relatively constant concentration

  14. Longitudinal change of selected human milk oligosaccharides and association to infants’ growth, an observatory, single center, longitudinal cohort study

    PubMed Central

    Lee, Le Ye; De Castro, Carlos Antonio; Steenhout, Philippe; Thakkar, Sagar K.

    2017-01-01

    Background Human milk is the recommended and sole nutrient source for newborns. One of the largest components of human milk is oligosaccharides (HMOs) with major constituents determined by the mother genotype for the fucosyltransferase 2 (FUT2, secretor) gene. HMO variation has been related with infant microbiota establishment, diarrhea incidence, morbidity and mortality, IgE associated eczema and body composition. Objectives We investigated the (i) dependence of several major representative HMOs on the FUT2 status assessed through breast milk 2’Fucosyllactose (2’FL) and (ii) the relation of the 2’FL status with infant growth up to 4 months of life. Design From an open observatory, single center, longitudinal cohort study with quantitative human milk collection at 30, 60, and 120 days postpartum from 50 mothers, who gave birth to 25 female and 25 male singleton infants, we collected a representative sample of human milk. We quantified the following 5 representative HMOs: 2’FL, Lacto-N-tetraose (LNT), Lacto-N-neotetraose (LNnT), 3’Sialyllactose (3’SL) and 6’Sialyllactose (6’SL). We grouped the milk samples and corresponding infants according to the measured milk 2’FL concentrations at 30 days of lactation, which clustered around low concentrations (95% CI of mean 12–42 mg/L) and high concentrations (95% CI of mean 1880–2460 mg/L) with the former likely representing Secretor negative mothers. Infant anthropometric measures were recorded at birth, 1, 2 and 4 months of age. Relations among the quantified HMOs and the relation of the high and low 2’FL HMOs groups with infant growth parameters were investigated via linear mixed models. Results The milk samples with low 2’FL concentration had higher LNT and lower LNnT concentrations compared to the samples with high 2’FL. The milk 3’- and 6’SL concentrations were independent of 2’FL. Over lactation time we observed a drop in the concentration of 2’FL, LNT, LNnT and 6’SL, especially

  15. Application of Low Dose Radiation Adaptive Response to Control Aging-Related Disease

    SciTech Connect

    Doss, Mohan

    2013-11-01

    Oxidative damage has been implicated in the pathogenesis of most aging-related diseases including neurodegenerative diseases. Antioxidant supplementation has been found to be ineffective in reducing such diseases, but increased endogenous production of antioxidants from the adaptive response due to physical and cognitive exercises (which increase oxidative metabolism and oxidative stress) has been effective in reducing some of the diseases. Low dose radiation (LDR), which increases oxidative stress and results in adaptive response of increased antioxidants, may provide an alternative method of controlling the aging-related diseases. We have studied the effect of LDR on the induction of adaptive response in rat brains and the effectiveness of the LDR in reducing the oxidative damage caused by subsequent high dose radiation. We have also investigated the effect of LDR on apomorphine-induced rotations in the 6-hydroxydopamine (6-OHDA) unilaterally-lesioned rat model of Parkinson?s disease (PD). LDR was observed to initiate an adaptive response in the brain, and reduce the oxidative damage from subsequent high dose radiation exposure, confirming the effectiveness of LDR adaptive response in reducing the oxidative damage from the free radicals due to high dose radiation. LDR resulted in a slight improvement in Tyrosine hydroxylase expression on the lesioned side of substantia nigra (indicative of its protective effect on the dopaminergic neurons), and reduced the behavioral symptoms in the 6-OHDA rat model of PD. Translation of this concept to humans, if found to be applicable, may be a possible approach for controlling the progression of PD and other neurodegenerative diseases. Since any translation of the concept to humans would be hindered by the currently prevalent carcinogenic concerns regarding LDR based on the linear no-threshold (LNT) model, we have also studied the justifications for the use of the LNT model. One of the shortcomings of the LNT model is that it

  16. Effect of Aging on the NOx Storage and Regeneration Characteristics of Fully Formulated Lean NOx Trap Catalysts

    SciTech Connect

    Ji, Yaying; Easterling, Vencon; Graham, Uschi; Fisk, Courtney; Crocker, Mark; Choi, Jae-Soon

    2011-01-01

    In order to elucidate the effect of washcoat composition on lean NO{sub x} trap (LNT) aging characteristics, fully formulated monolithic LNT catalysts containing varying amounts of Pt, Rh and BaO were subjected to accelerated aging on a bench reactor. Subsequent catalyst evaluation revealed that in all cases aging resulted in deterioration of the NO{sub x} conversion as a consequence of impaired NO{sub x} storage and NO{sub x} reduction functions, while increased selectivity to NH{sub 3} was observed in the temperature range 250--450 C. Elemental analysis, H{sub 2} chemisorption and TEM data revealed two main changes which account for the degradation in LNT performance. First, residual sulfur in the catalysts, associated with the Ba phase, decreased catalyst NO{sub x} storage capacity. Second, sintering of the precious metals in the washcoat occurred, resulting in decreased contact between the Pt and Ba, and hence in less efficient NO{sub x} spillover from Pt to Ba during NO{sub x} adsorption, as well as decreased rates of reductant spillover from Pt to Ba and reverse NO{sub x} spillover during catalyst regeneration. For the aged catalysts, halving the Pt loading from 100 to 50 g/ft{sup 3} was found to result in a significant decrease in overall NO{sub x} conversion, while for catalysts with the same 100 g/ft{sup 3} Pt loading, increasing the relative amount of Pt on the NO{sub x} storage components (BaO and La-stabilized CeO{sub 2}), as opposed to an Al{sub 2}O{sub 3} support material (where it was co-located with Rh), was found to be beneficial. The effect of Rh loading on aged catalyst performance was found to be marginal within the range studied (10--20 g/ft{sup 3}), as was the effect of BaO loading in the range 30--45 g/L.

  17. WE-C-217A-03: Biology versus Epidemiology: The Need for an Integrated Model of Radiation Risk.

    PubMed

    Vetter, D

    2012-06-01

    The lifetime attributable risk estimates from the National Academy of Sciences BEIR VII report have been used by a number of authors to estimate cancer mortality caused by radiation exposure from medical diagnostic radiology exams. This controversial practice assumes that the dose response relationship between radiation and cancer is linear with no threshold (LNT). For purposes of protecting public health, use of the LNT model is widely accepted. But is it appropriate for estimating risk to individuals exposed to low doses of radiation from medical procedures? Radiation biology research demonstrates that not all biological processes are linear. Italso has provided data that support not only LNT but supra linear and sub linear response models. Results from epidemiology studies can also be used to support the use of any of these models, but the confidence intervals are much larger. Since we can't prove which model is correct, for purposes of protecting patients we assume that any exposure has the potential for harm and we use optimization to keep exposures as low as reasonably achievable.Several areas of research are contributing insight into this dilemma, but they still leave several important questions unanswered: • How can we accurately extrapolate low-dose biological effects generated in the laboratory to risk in a human? • Is extrapolation from high dose, high dose rate, acute exposures appropriate when human exposures are primarily chronic low dose exposures. Epidemiology alone is unlikely to provide information that will resolve this dilemma. The numbers of individuals required in a sample are too large, and the homogeneity among subjects is lacking. Reliance on radiation biology research alone is problematic because the research is focused primarily on mechanisms and not risk. This paper will present an overview of the issues and suggest areas of research that may contribute to our understanding of the level of risk associated with low doses of medical

  18. A Perspective on the Scientific, Philosophical, and Policy Dimensions of Hormesis

    PubMed Central

    Hoffmann, George R.

    2009-01-01

    The hormesis concept has broad implications for biology and the biomedical sciences. This perspective on hormesis concentrates on toxicology and toxicological risk assessment and secondarily explores observations from other fields. It considers the varied manifestations of hormesis in the context of a broad family of biological stress responses. Evidence for hormesis is reviewed, and the hormesis model is contrasted with more widely accepted dose-response models in toxicology: a linear nonthreshold (LNT) model for mutagenesis and carcinogenesis, and a threshold model for most other toxicologic effects. Scientific, philosophical, and political objections to the hormesis concept are explored, and complications in the hormesis concept are analyzed. The review concludes with a perspective on the current state of hormesis and challenges that the hormesis model poses for risk assessment. PMID:19343115

  19. Threshold dose model: It`s time to line up our ducks

    SciTech Connect

    Logan, S.E.

    1997-12-01

    Evidence has accumulated that discredits the linear no-threshold (LNT) relationship for low-level radiation exposure and provides the basis on which to adopt a threshold model. This paper examines steps that need to be taken to bring about the change. Some of the evidence supporting the threshold concept comes from incidents such as the atom bombs over Japan and the Chernobyl accident. Other evidence concerns extended exposure such as that with shipyard workers, radiation treatment, and high-background-radiation geographic regions. Not only does the evidence show an absence of net health damage at doses below some level, but radiation hormesis or net benefits are shown to occur at low levels of radiation dose.

  20. Reaction kinetics of diffusing particles injected into a d-dimensional reactive substrate

    NASA Astrophysics Data System (ADS)

    Larralde, H.; Lereah, Y.; Trunfio, P.; Dror, J.; Havlin, S.; Rosenbaum, R.; Stanley, H. E.

    1993-03-01

    We study a system in which diffusing particles (species A) are injected into a reactive d-dimensional substrate (species B) at rate λ, with the rule that A+B-->C (inert). The amount of species C, C(t), and the number of surviving A particles, A(t), are calculated for substrate dimensions d=1, 2, and 3. We find the surprising results A(t)~t2/3 for d=3 and C(t)~ √t lnt for d=1. We confirm our predictions by performing Monte Carlo simulations for d=1, 2, and 3 and experiments for the reaction I2(gas)+2Ag(solid)-->2AgI(solid) for d=2.

  1. Irradiation effect of the insulating materials for fusion superconducting magnets at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Kobayashi, Koji; Akiyama, Yoko; Nishijima, Shigehiro

    2017-09-01

    In ITER, superconducting magnets should be used in such severe environment as high fluence of fast neutron, cryogenic temperature and large electromagnetic forces. Insulating material is one of the most sensitive component to radiation. So radiation resistance on mechanical properties at cryogenic temperature are required for insulating material. The purpose of this study is to evaluate irradiation effect of insulating material at cryogenic temperature by gamma-ray irradiation. Firstly, glass fiber reinforced plastic (GFRP) and hybrid composite were prepared. After irradiation at room temperature (RT) or liquid nitrogen temperature (LNT, 77 K), interlaminar shear strength (ILSS) and glass-transition temperature (Tg) measurement were conducted. It was shown that insulating materials irradiated at room temperature were much degraded than those at cryogenic temperature.

  2. KWIK Smoke Obscuration Model: User’s Guide.

    DTIC Science & Technology

    1982-09-01

    t ’ustr ( td I IK,j) 384: prt 3o :: pr t 6 k AC 1-4G" 36~b : pr t " ~ L 3b7: if j~i;prt &t(t1,] 3 8 8: it J=2;pr. "&str(Zjl,1,KI) 3 0 9: j~r t "I 39u...t.2~t71. * j3 3 2u: w r t 7uX ,"i(Lz~j i21iJ "c3wt70, )i: lnt 4 5X, "irI I U uIL - = 01 17.2;wrt 701,kq3 j~b: Lirt. 45x,"a..~c4 uAT - LiLY = g,t4.2

  3. Mach-6 Receptivity Measurements of Laser-Generated Perturbations on a Flared Cone

    DTIC Science & Technology

    2014-08-01

    The window is mounted using Cerrotru, a low-melting point tin-bismuth alloy, and a Dow Corning 734 Flowable RTV silicone. The window mounts into the...T∞ ln ∣∣∣∣ ∆TT∞ + A∆T ∣∣∣∣ = Bt + C ln ∣∣∣∣ ∆TT∞ + A∆T ∣∣∣∣ = T∞ Bt + CT∞ Since A and ∆T are always positive, can take away the absolute value signs: ln...T T∞ + A∆T ) = T∞ Bt + CT∞ exp [ ln ( ∆T T∞ + A∆T )] = exp (T∞ Bt + CT∞) ∆T T∞ + A∆T = exp (T∞ Bt + CT∞) ∆T = (T∞ + A∆T ) exp (T∞ Bt + CT∞) ∆T = T∞ exp (T

  4. Superconducting fluctuations in a thin NbN film probed by the Hall effect

    NASA Astrophysics Data System (ADS)

    Destraz, Daniel; Ilin, Konstantin; Siegel, Michael; Schilling, Andreas; Chang, Johan

    2017-06-01

    We present a comprehensive study of how superconducting fluctuations in the normal state contribute to the conductivity tensor in a thin (119 Å) film of NbN. It is shown how these fluctuations drive a sign change in the Hall coefficient RH for low magnetic fields near the superconducting transition. The scaling behaviors as a function of distance to the transition ɛ =ln(T /Tc) of the longitudinal (σxx) and transverse (σxy) conductivity are found to be consistent with Gaussian fluctuation theory. Moreover, excellent quantitative agreement between theory and experiment is obtained without any adjustable parameters. Our experimental results thus provide a case study of the conductivity tensor originating from short-lived Cooper pairs.

  5. Low doses of ionizing radiation to mammalian cells may rather control than cause DNA damage

    SciTech Connect

    Feinendegen, L.E.; Bond, V.P.; Sondhaus, C.A.; Altman, K.I.

    1998-12-31

    This report examines the origin of tissue effects that may follow from different cellular responses to low-dose irradiation, using published data. Two principal categories of cellular responses are considered. One response category relates to the probability of radiation-induced DNA damage. The other category consists of low-dose induced metabolic changes that induce mechanisms of DNA damage mitigation, which do not operate at high levels of exposure. Modeled in this way, tissue is treated as a complex adaptive system. The interaction of the various cellular responses results in a net tissue dose-effect relation that is likely to deviate from linearity in the low-dose region. This suggests that the LNT hypothesis should be reexamined. This paper aims at demonstrating tissue effects as an expression of cellular responses, both damaging and defensive, in relation to the energy deposited in cell mass, by use of microdosimetric concepts.

  6. Protecting effects specifically from low doses of ionizing radiation to mammalian cells challenge the concept of linearity

    SciTech Connect

    Feinendegen, L.E.; Bond, V.P.; Sondhaus, C.A.; Altman, K.I.

    1998-12-31

    This report examines the origin of tissue effects that may follow from different cellular responses to low-dose irradiation, using published data. Two principal categories of cellular responses are considered. One response category relates to the probability of radiation-induced DNA damage. The other category consists of low-dose induced changes in intracellular signaling that induce mechanisms of DNA damage control different from those operating at high levels of exposure. Modeled in this way, tissue is treated as a complex adaptive system. The interaction of the various cellular responses results in a net tissue dose-effect relation that is likely to deviate from linearity in the low-dose region. This suggests that the LNT hypothesis should be reexamined. The aim of this paper is to demonstrate that by use of microdosimetric concepts, the energy deposited in cell mass can be related to the occurrence of cellular responses, both damaging and defensive.

  7. Magnetic excitations and c-f hybridization effect in PrTi2Al20 and PrV2Al20

    NASA Astrophysics Data System (ADS)

    Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Sakai, Akito; Nakatsuji, Satoru; Harima, Hisatomo

    2013-08-01

    By means of 27Al NMR studies, we have investigated magnetic excitations and the hybridization effect between Pr 4f and conduction electrons in a pair of cubic compounds PrTr2Al20 (Tr=Ti, V). From Knight shift measurements we have evaluated comparative strengths for the c-f hybridization effect in these compounds and confirm a definite increase of hybridization on replacing Ti with V. Analysis of the spin-lattice relaxation rate 1/T1 reveals that the spectral width of magnetic fluctuations in crystalline electric field excited states is strongly temperature dependent. This result indicates that magnetic fluctuations are dominated by strong c-f exchange coupling at high temperatures and thus is nicely consistent with the Kondo picture that features lnT dependence of resistivity over the same temperature region.

  8. Quantum statistical vibrational entropy and enthalpy of formation of helium-vacancy complex in BCC W

    NASA Astrophysics Data System (ADS)

    Wen, Haohua; Woo, C. H.

    2016-12-01

    High-temperature advance-reactor design and operation require knowledge of in-reactor materials properties far from the thermal ground state. Temperature-dependence due to the effects of lattice vibrations is important to the understanding and formulation of atomic processes involved in irradiation-damage accumulation. In this paper, we concentrate on the formation of He-V complex. The free-energy change in this regard is derived via thermodynamic integration from the phase-space trajectories generated from MD simulations based on the quantum fluctuation-dissipation relation. The change of frequency distribution of vibration modes during the complex formation is properly accounted for, and the corresponding entropy change avoids the classical ln(T) divergence that violates the third law. The vibrational enthalpy and entropy of formation calculated this way have significant effects on the He kinetics during irradiation.

  9. Effect of long-range hopping and interactions on entanglement dynamics and many-body localization

    NASA Astrophysics Data System (ADS)

    Singh, Rajeev; Moessner, Roderich; Roy, Dibyendu

    2017-03-01

    We numerically investigate the dynamics of entanglement in a chain of spinless fermions with nonrandom but long-range hopping and interactions, and with random on-site energies. For moderate disorder in the absence of interactions, the chain hosts delocalized states at the top of the band which undergo a delocalization-localization transition with increasing disorder. We find an interesting regime in this noninteracting disordered chain where the long-time entanglement entropy scales as S (t )˜lnt and the saturated entanglement entropy scales with system size L as S (L ,t →∞ )˜lnL . We further study the interplay of long-range hopping and interactions on the growth of entanglement and the many-body localization (MBL) transition in this system. We develop an analogy to higher-dimensional short-range systems to compare and contrast such behavior with the physics of MBL in a higher dimension.

  10. Inkjet printing technology and conductive inks synthesis for microfabrication techniques

    NASA Astrophysics Data System (ADS)

    Chien Dang, Mau; Dung Dang, Thi My; Fribourg-Blanc, Eric

    2013-03-01

    Inkjet printing is an advanced technique which reliably reproduces text, images and photos on paper and some other substrates by desktop printers and is now used in the field of materials deposition. This interest in maskless materials deposition is coupled with the development of microfabrication techniques for the realization of circuits or patterns on flexible substrates for which printing techniques are of primary interest. This paper is a review of some results obtained in inkjet printing technology to develop microfabrication techniques at Laboratory for Nanotechnology (LNT). Ink development, in particular conductive ink, study of printed patterns, as well as application of these to the realization of radio-frequency identification (RFID) tags on flexible substrates, are presented. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November 2012, Ha Long, Vietnam.

  11. Experimental determination of the solubilities of dissolver off-gas constituents in a Kr-85 recovery solvent (CCl/sub 2/F/sub 2/). Final report

    SciTech Connect

    van Brunt, V.

    1983-05-01

    The experimental determination of the solubility of the major off-gas constituent-Nitrogen was performed with a new solubility measurement apparatus. The new apparatus was designed, built and tested; an algorithm for thermodynamic consistency testing of P-T-x-y data for solubility systems was developed, and thermodynamically consistent Nitrogen-R-12 solubility data were taken. The Henry's Law constant for the Nitrogen-R-12 system can be represented by the equation ln H/sub N/sub 2/-R-12/ (atm) = 0.44 + 1.0708 lnT (/sup 0/K). The solubility data extend the range of known equilibrium data into a region where process equipment operate and are consistent with both other data at lower temperatures by other researchers and with regular solution theory.

  12. Compliance of Royal Naval ships with nitrogen oxide emissions legislation.

    PubMed

    Blatcher, D J; Eames, I

    2013-09-15

    Nitrogen oxide (NOx) emissions from marine diesel engines pose a hazard to human health and the environment. From 2021, demanding emissions limits are expected to be applied to sea areas that the Royal Navy (RN) accesses. We analyze how these future constraints affect the choice of NOx abatement systems for RN ships, which are subject to more design constraints than civilian ships. A weighted matrix approach is used to facilitate a quantitative assessment. For most warships to be built soon after 2021 Lean Nitrogen Traps (LNT) in conjunction with Exhaust Gas Recirculation (EGR) represents a relatively achievable option with fewer drawbacks than other system types. Urea-selective catalytic reduction is likely to be most appropriate for ships that are built to civilian standards. The future technologies that are at an early stage of development are discussed.

  13. Threshold for Radon-Induced Lung Cancer From Inhaled Plutonium Data.

    PubMed

    Cuttler, Jerry M; Sanders, Charles L

    2015-01-01

    Cohen's lung cancer mortality data, from his test of the LNT theory, do not extend to the no observed adverse effects level (NOAEL) above which inhaled radon decay products begin to induce excess lung cancer mortality. Since there is concern about the level of radon in homes, it is important to set the radon limit near the NOAEL to avoid the risk of losing a health benefit. Assuming that dogs model humans, data from a study on inhaled plutonium dioxide particulates in dogs were assessed, and the NOAEL for radon-induced lung tumors was estimated to be about 2100 Bq/m(3). The US Environmental Protection Agency should consider raising its radon action level from 150 to at least 1000 Bq/m(3).

  14. Slow relaxation in granular compaction

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Knight, J. B.; Nowak, E. R.; Jaeger, H. M.; Nagel, S. R.

    1998-11-01

    Experimental studies show that the density of a vibrated granular material evolves from a low density initial state into a higher density final steady state. The relaxation towards the final density follows an inverse logarithmic law. As the system approaches its final state, a growing number of beads have to be rearranged to enable a local density increase. A free volume argument shows that this number grows as N = {ϱ}/{(1-ϱ)}. The time scale associated with such events increases exponentially ∼ e N, and as a result a logarithmically slow approach to the final state is found ϱ ∞ - ϱ(t) ∼ {1}/{lnt }. Furthermore, a one-dimensional toy model that captures this relaxation dynamics as well as the observed density fluctuations is discussed.

  15. In defence of collective dose.

    PubMed

    Fairlie, I; Sumner, D

    2000-03-01

    Recent proposals for a new scheme of radiation protection leave little room for collective dose estimations. This article discusses the history and present use of collective doses for occupational, ALARA, EIS and other purposes with reference to practical industry papers and government reports. The linear no-threshold (LNT) hypothesis suggests that collective doses which consist of very small doses added together should be used. Moral and ethical questions are discussed, particularly the emphasis on individual doses to the exclusion of societal risks, uncertainty over effects into the distant future and hesitation over calculating collective detriments. It is concluded that for moral, practical and legal reasons, collective dose is a valid parameter which should continue to be used.

  16. Risk of low-dose radiation and the BEIR VII report: A critical review of what it does and doesn't say.

    PubMed

    O'Connor, Michael K

    2017-08-18

    This article briefly reviews the history behind the BEIR VII report and the use of the linear no-threshold hypothesis. The BEIR VII committee considered four primary sources of data on the stochastic effects of ionizing radiation. These were environmental studies, occupational studies, medical studies and studies on the atomic bomb survivors. These sources are briefly reviewed along with key studies that run counter to the LNT hypothesis. We review many of the assumptions, hypotheses and subjective decisions used to generate risk estimates in the BEIR VII report. Position statement by the Health Physics Society, American Association of Physicists in Medicine, and UNSCEAR support the conclusion that the risk estimates in the BEIR VII report should not be used for estimating cancer risks from low doses of ionizing radiation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Threshold for Radon-Induced Lung Cancer From Inhaled Plutonium Data

    PubMed Central

    Sanders, Charles L.

    2015-01-01

    Cohen’s lung cancer mortality data, from his test of the LNT theory, do not extend to the no observed adverse effects level (NOAEL) above which inhaled radon decay products begin to induce excess lung cancer mortality. Since there is concern about the level of radon in homes, it is important to set the radon limit near the NOAEL to avoid the risk of losing a health benefit. Assuming that dogs model humans, data from a study on inhaled plutonium dioxide particulates in dogs were assessed, and the NOAEL for radon-induced lung tumors was estimated to be about 2100 Bq/m3. The US Environmental Protection Agency should consider raising its radon action level from 150 to at least 1000 Bq/m3. PMID:26740812

  18. Effect of Ceria on the Sulfation and Desulfation Characteristics of a Model Lean NOx Trap Catalyst

    SciTech Connect

    Ji, Yaying; Toops, Todd J; Crocker, Mark

    2009-01-01

    The effect of ceria addition on the sulfation and desulfation characteristics of a model Ba-based lean NO{sub x} trap (LNT) catalyst was studied. According to DRIFTS and NO{sub x} storage capacity measurements, ceria is able to store sulfur during catalyst exposure to SO{sub 2}, thereby helping to limit sulfation of the main (Ba) NO{sub x} storage phase and maintain NO{sub x} storage capacity. Temperature programmed desulfation experiments revealed that desulfation of a model ceria-containing catalyst occurred in two stages, corresponding to sulfur elimination from the ceria phase at {approx}450 C, followed by sulfur loss from the Ba phase at {approx}650 C. Significantly, the ceria-containing catalyst displayed relatively lower sulfur evolution from the Ba phase than its non-ceria analog, confirming that the presence of ceria lessened the degree of sulfur accumulation on the Ba phase.

  19. Nanofoams Response to Radiation Damage

    SciTech Connect

    Fu, Engang; Serrano De Caro, Magdalena; Wang, Yongqiang; Nastasi, Michael; Zepeda-Ruiz, Luis; Bringa, Eduardo M.; Baldwin, Jon K.; Caro, Jose A.

    2012-07-30

    Conclusions of this presentation are: (1) np-Au foams were successfully synthesized by de-alloying process; (2) np-Au foams remain porous structure after Ne ion irradiation to 1 dpa; (3) SFTs were observed in irradiated np-Au foams with highest and intermediate flux, while no SFTs were observed with lowest flux; (4) SFTs were observed in irradiated np-Au foams at RT, whereas no SFTs were observed at LNT irradiation; (5) The diffusivity of vacancies in Au at RT is high enough so that the vacancies have enough time to agglomerate and thus collapse. As a result, SFTs were formed; (6) The high flux created much more damage/time, vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed.

  20. Non-Fermi-liquid behavior and spin fluctuations in doped UAl{sub 2}

    SciTech Connect

    Mayr, F.; Blanckenhagen, G.v.; Stewart, G.R.

    1997-01-01

    Using the canonical spin-fluctuation system UAl{sub 2} as a starting point, via negative chemical pressure (doping with Y) we have expanded d{sub U-U} in a system known to be near the Hill limit of f-electron localization, and characterized the samples via resistivity, magnetic susceptibility, and specific-heat measurements. All system parameters, including magnetic susceptibility, specific heat {gamma} ({equivalent_to}C/Tlim{sub T{r_arrow}0}), and spin-fluctuation temperature, behave monotonically. For U{sub 1{minus}x}Y{sub x}Al{sub 2}, 0.30{le}x{le}0.70, spin-glass behavior is found with T{sub f}{approx_equal};5.1{plus_minus}0.5 K. This spin-glass behavior weakens (T{sub f} sinks, smaller magnetic signature, no specific-heat anomaly) for x{ge}0.75 while, at the same time, the spin-fluctuation T{sup 3}lnT term also gradually disappears from the specific heat. For x{ge}0.875, a non-Fermi-liquid (nFl) lnT term is found in the low temperature C/T. This new, perhaps equilibrium, ground state persists upon further dilution of the U ions with Y. Thus, we report on the evolution of nFl behavior in the neighborhood of a spin-glass ground state but, indeed, directly out of a yet weaker form of magnetism than heretofore reported, that of spin fluctuations. {copyright} {ital 1997} {ital The American Physical Society}

  1. Identification of transmissivity fields using a Bayesian strategy and perturbative approach

    NASA Astrophysics Data System (ADS)

    Zanini, Andrea; Tanda, Maria Giovanna; Woodbury, Allan D.

    2017-10-01

    The paper deals with the crucial problem of the groundwater parameter estimation that is the basis for efficient modeling and reclamation activities. A hierarchical Bayesian approach is developed: it uses the Akaike's Bayesian Information Criteria in order to estimate the hyperparameters (related to the covariance model chosen) and to quantify the unknown noise variance. The transmissivity identification proceeds in two steps: the first, called empirical Bayesian interpolation, uses Y* (Y = lnT) observations to interpolate Y values on a specified grid; the second, called empirical Bayesian update, improve the previous Y estimate through the addition of hydraulic head observations. The relationship between the head and the lnT has been linearized through a perturbative solution of the flow equation. In order to test the proposed approach, synthetic aquifers from literature have been considered. The aquifers in question contain a variety of boundary conditions (both Dirichelet and Neuman type) and scales of heterogeneities (σY2 = 1.0 and σY2 = 5.3). The estimated transmissivity fields were compared to the true one. The joint use of Y* and head measurements improves the estimation of Y considering both degrees of heterogeneity. Even if the variance of the strong transmissivity field can be considered high for the application of the perturbative approach, the results show the same order of approximation of the non-linear methods proposed in literature. The procedure allows to compute the posterior probability distribution of the target quantities and to quantify the uncertainty in the model prediction. Bayesian updating has advantages related both to the Monte-Carlo (MC) and non-MC approaches. In fact, as the MC methods, Bayesian updating allows computing the direct posterior probability distribution of the target quantities and as non-MC methods it has computational times in the order of seconds.

  2. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. III. Spectra of protiated and partially deuterated magnesium ammonium phosphate hexahydrate

    NASA Astrophysics Data System (ADS)

    Stefov, V.; Šoptrajanov, B.; Kuzmanovski, I.; Lutz, H. D.; Engelen, B.

    2005-10-01

    Magnesium ammonium phosphate hexahydrate, MgNH 4PO 4·6H 2O (synthetic struvite) is a well-known biomineral, its major biological importance being related to its presence in human urinary sediments and vesical and renal calculi. The Fourier transform infrared and Raman spectra of magnesium ammonium phosphate hexahydrate were recorded and analyzed from room temperature (RT) down to the boiling temperature of liquid nitrogen (LNT). Also recorded and analyzed were the spectra of its partially deuterated analogues. The recorded spectra were compared with the corresponding ones of the previously studied potassium analogue. On the basis of such a comparison it was concluded that the main contribution to the intensity of the broad and structured feature in the O-H/N-H stretching region comes from the bands originating from the H-O-H stretches. The location of at least some of the stretching vibrations of the ammonium ions (albeit one of its deuterated forms) is possible in the spectrum of the sample containing ≈2% deuterium. The bands at 2326 and 2277 cm -1 (and probably, at least partially, that at 2393 cm -1) can be assigned with certainty to N-D stretching vibrations of isotopically isolated NH 3D + ions. The LNT Raman bands at 1702 and 1685 cm -1 are attributed to the ν2NH4+ mode and those at 1477 and 1442 cm -1 are observed are attributed to the ν4 mode. The relatively high frequencies (1302 and 1295 cm -1) of some of the bands due to the ND bending vibrations of isotopically isolated NH 3D + ions are in line with the existence of quite strong hydrogen bonds formed by ammonium ions. The librations of the deuterated forms of water molecules may be coupled with the components of the phosphate ν4 vibration.

  3. Cytogenetic Low-Dose Hyperradiosensitivity Is Observed in Human Peripheral Blood Lymphocytes

    SciTech Connect

    Seth, Isheeta; Joiner, Michael C.; Tucker, James D.

    2015-01-01

    Purpose: The shape of the ionizing radiation response curve at very low doses has been the subject of considerable debate. Linear-no-threshold (LNT) models are widely used to estimate risks associated with low-dose exposures. However, the low-dose hyperradiosensitivity (HRS) phenomenon, in which cells are especially sensitive at low doses but then show increased radioresistance at higher doses, provides evidence of nonlinearity in the low-dose region. HRS is more prominent in the G2 phase of the cell cycle than in the G0/G1 or S phases. Here we provide the first cytogenetic mechanistic evidence of low-dose HRS in human peripheral blood lymphocytes using structural chromosomal aberrations. Methods and Materials: Human peripheral blood lymphocytes from 2 normal healthy female donors were acutely exposed to cobalt 60 γ rays in either G0 or G2 using closely spaced doses ranging from 0 to 1.5 Gy. Structural chromosomal aberrations were enumerated, and the slopes of the regression lines at low doses (0-0.4 Gy) were compared with doses of 0.5 Gy and above. Results: HRS was clearly evident in both donors for cells irradiated in G2. No HRS was observed in cells irradiated in G0. The radiation effect per unit dose was 2.5- to 3.5-fold higher for doses ≤0.4 Gy than for doses >0.5 Gy. Conclusions: These data provide the first cytogenetic evidence for the existence of HRS in human cells irradiated in G2 and suggest that LNT models may not always be optimal for making radiation risk assessments at low doses.

  4. Collective dose: Dogma, tool, or trauma?

    SciTech Connect

    Becker, K.

    1996-12-31

    In Europe as well as in the United States, the argument continues in the radiation protection community between the {open_quotes}fundamentalists,{close_quotes} who firmly believe in the linear no-threshold (LNT) hypothesis and the closely related concept of collective dose, and {open_quotes}pragmatists,{close_quotes} who have serious doubts about these concepts for both radiobiological and socioeconomic reasons. The latter view is reflected in many recent compilations in the scientific literature, in particular in the books by G. Walinder and S. Kondo. The fundamentalist view has been expressed in other recent publications. What has been described as the good old boys` network of the establishment threatens nonbelievers with excommunication: in his 1996 Sievert lecture, D. Beninson described doubts about the LNT hypothesis as {open_quotes}arrogant ignorance{close_quotes}; A. Gonzales, in a 1995 letter to the author, described them as {open_quotes}intellectual laziness{close_quotes}; and R. Clarke, chairman of the International Commission on Radiological Protection (ICRP), during the 1996 IRPA Congress, described them as {open_quotes}seriously misguided.{close_quotes} Threshold or no threshold, that is the question - the most important one for this and the next generation of health physicists. Corrections of the current dogmas are needed soon and should be initiated not only by the nuclear community (which may be blamed by opinion makers for a biased view) but by those members of the radiation protection community, who are not only interested in order to `keep the hazard alive` for reasons of publicity, research funding, and sales of instruments and services. The International Atomic Energy Agency will devote a symposium to these questions next year. The results should be interesting.

  5. Distribution of shortest path lengths in a class of node duplication network models

    NASA Astrophysics Data System (ADS)

    Steinbock, Chanania; Biham, Ofer; Katzav, Eytan

    2017-09-01

    We present analytical results for the distribution of shortest path lengths (DSPL) in a network growth model which evolves by node duplication (ND). The model captures essential properties of the structure and growth dynamics of social networks, acquaintance networks, and scientific citation networks, where duplication mechanisms play a major role. Starting from an initial seed network, at each time step a random node, referred to as a mother node, is selected for duplication. Its daughter node is added to the network, forming a link to the mother node, and with probability p to each one of its neighbors. The degree distribution of the resulting network turns out to follow a power-law distribution, thus the ND network is a scale-free network. To calculate the DSPL we derive a master equation for the time evolution of the probability Pt(L =ℓ ) , ℓ =1 ,2 ,⋯ , where L is the distance between a pair of nodes and t is the time. Finding an exact analytical solution of the master equation, we obtain a closed form expression for Pt(L =ℓ ) . The mean distance 〈L〉 t and the diameter Δt are found to scale like lnt , namely, the ND network is a small-world network. The variance of the DSPL is also found to scale like lnt . Interestingly, the mean distance and the diameter exhibit properties of a small-world network, rather than the ultrasmall-world network behavior observed in other scale-free networks, in which 〈L〉 t˜lnlnt .

  6. Cancer risk modelling and radiological protection.

    PubMed

    Wakeford, Richard

    2012-03-01

    Statistical models describing how the radiation-related risks of particular types of cancer vary with the doses of radiation received by specific tissues are derived from data gathered in epidemiological studies of exposed groups of people, guided by an incomplete understanding of radiobiological mechanisms gleaned from experimental studies. Cancer risk models have been developed for a dozen or so different types of cancer, and take account of the effect of important risk modifying factors such as age at exposure and time since exposure. Of primary importance in the development of cancer risk models is the experience of the Japanese atomic bomb survivors, but other exposed groups contribute information, including those exposed to radiation from internally deposited radioactive material, such as inhaled radon. Cancer risk models predict that at low doses or low dose rates the excess risk of cancer is directly proportional to the dose of radiation received, with no threshold dose--the linear no threshold (LNT) dose-response model--and the inferred summary estimate of the overall average lifetime excess risk of developing a serious cancer is ∼ 5%/Sv. It is these cancer risk models and this inferred nominal risk estimate that provide the technical basis of radiological protection. Although it is difficult to definitively test the LNT model at low doses or low dose rates, because the predicted excess risk is small compared with fluctuations in the baseline risk, evidence exists that a small risk of cancer results from low-level exposure to radiation and that the excess risk is around that predicted by current risk models.

  7. NOx Storage and Reduction Properties of Model Ceria-based Lean NOx Trap Catalysts

    SciTech Connect

    Shi, Chuan; Ji, Yaying; Graham, Uschi; Jacobs, Gary; Crocker, Mark; Zhang, Zhaoshun; Wang, Yu; Toops, Todd J

    2012-01-01

    Three kinds of model ceria-containing LNT catalysts, corresponding to Pt/Ba/CeO{sub 2}, Pt/CeO{sub 2}/Al{sub 2}O{sub 3} and Pt/BaO/CeO{sub 2}/Al{sub 2}O{sub 3}, were prepared for comparison with a standard LNT catalyst of the Pt/BaO/Al{sub 2}O{sub 3} type. In these catalysts ceria functioned as a No{sub x} storage component and/or a support material. The influence of ceria on the microstructure of the catalysts was investigated, in addition to the effect on No{sub x} storage capacity, regeneration behavior and catalyst performance during lean/rich cycling. The Pt/Ba/CeO{sub 2} and Pt/BaO/CeO{sub 2}/Al{sub 2}O{sub 3} catalysts exhibited higher No{sub x} storage capacity at 200 and 300 C relative to the Pt/BaO/Al{sub 2}O{sub 3} catalyst, although the latter displayed better storage capacity at 400 C. Catalyst regeneration behavior at low temperature was also improved by the presence of ceria, as reflected by TPR measurements. These factors contributed to the superior No{sub x} storage-reduction performance exhibited by the Pt/Ba/CeO{sub 2} and Pt/BaO/CeO{sub 2}/Al{sub 2}O{sub 3} catalysts under cycling conditions in the temperature range 200-300 C. Overall, Pt/BaO/CeO{sub 2}/Al{sub 2}O{sub 3} (which displayed well balanced No{sub x} storage and regeneration behavior), showed the best performance, affording consistently high No{sub x} conversion levels in the temperature range 200-400 C under lean-rich cycling conditions.

  8. Microkinetic Modeling of Lean NOx Trap Sulfation and Desulfation

    SciTech Connect

    Larson, Richard S.

    2011-08-01

    A microkinetic reaction sub-mechanism designed to account for the sulfation and desulfation of a commercial lean NOx trap (LNT) is presented. This set of reactions is appended to a previously developed mechanism for the normal storage and regeneration processes in an LNT in order to provide a comprehensive modeling tool. The reactions describing the storage, release, and reduction of sulfur oxides are patterned after those involving NOx, but the number of reactions is kept to the minimum necessary to give an adequate simulation of the experimental observations. Values for the kinetic constants are estimated by fitting semi-quantitatively the somewhat limited experimental data, using a transient plug flow reactor code to model the processes occurring in a single monolith channel. Rigorous thermodynamic constraints are imposed in order to ensure that the overall mechanism is consistent both internally and with the known properties of all gas-phase species. The final mechanism is shown to be capable of reproducing the principal aspects of sulfation/desulfation behavior, most notably (a) the essentially complete trapping of SO2 during normal cycling; (b) the preferential sulfation of NOx storage sites over oxygen storage sites and the consequent plug-like and diffuse sulfation profiles; (c) the degradation of NOx storage and reduction (NSR) capability with increasing sulfation level; and (d) the mix of H2S and SO2 evolved during desulfation by temperature-programmed reduction.

  9. Characteristics of Pt-K/MgAl2O4 lean NOx trap catalysts

    SciTech Connect

    Kim, Do Heui; Mudiyanselage, Kumudu K.; Szanyi, Janos; Zhu, Haiyang; Kwak, Ja Hun; Peden, Charles HF

    2012-04-30

    We report the various characteristics of Pt-K/MgAl{sub 2}O{sub 4} lean NOx trap (LNT) catalysts including the effect of K loading on nitrate formation/decomposition, NOx storage activity and durability. Upon the adsorption of NO{sub 2} on K/MgAl{sub 2}O{sub 4} samples, potassium nitrates formed on Mg-related sites in MgAl{sub 2}O{sub 4} support are observed, in addition to the typical two potassium nitrates (ionic and bidentate) formed also on Al{sub 2}O{sub 3} supported sample. Based on NO{sub 2} TPD and FTIR results, the Mg-bound KNO{sub 3} thermally decompose at higher temperature than Al-bound KNO{sub 3}, implying its superior thermal stability. At a potassium loading of 5wt%, the temperature of maximum NOx uptake (T{sub max}) is 300 C. Increasing the potassium loading from 5wt% to 10 wt%, the T{sub max} gradually shifted from 300 C to 450 C, indicating the dependence of T{sub max} on the potassium loading. However, increase in potassium loading above 10 wt% only gives rise to the reduction in the overall NOx storage capacity. This work also underlines the obstacles these materials have prior to their practical application (e.g., durability and sulfur poisoning/ removal). This work provides fundamental understanding of Pt-K/MgAl{sub 2}O{sub 4}-based lean NOx trap catalysts, which could be good candidates for high temperature LNT applications.

  10. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    SciTech Connect

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  11. Nonlinear threshold effect in the Z-scan method of characterizing limiters for high-intensity laser light

    NASA Astrophysics Data System (ADS)

    Tereshchenko, S. A.; Savelyev, M. S.; Podgaetsky, V. M.; Gerasimenko, A. Yu.; Selishchev, S. V.

    2016-09-01

    A threshold model is described which permits one to determine the properties of limiters for high-powered laser light. It takes into account the threshold characteristics of the nonlinear optical interaction between the laser beam and the limiter working material. The traditional non-threshold model is a particular case of the threshold model when the limiting threshold is zero. The nonlinear characteristics of carbon nanotubes in liquid and solid media are obtained from experimental Z-scan data. Specifically, the nonlinear threshold effect was observed for aqueous dispersions of nanotubes, but not for nanotubes in solid polymethylmethacrylate. The threshold model fits the experimental Z-scan data better than the non-threshold model. Output characteristics were obtained that integrally describe the nonlinear properties of the optical limiters.

  12. Nonlinear threshold effect in the Z-scan method of characterizing limiters for high-intensity laser light

    SciTech Connect

    Tereshchenko, S. A. Savelyev, M. S.; Podgaetsky, V. M.; Gerasimenko, A. Yu.; Selishchev, S. V.

    2016-09-07

    A threshold model is described which permits one to determine the properties of limiters for high-powered laser light. It takes into account the threshold characteristics of the nonlinear optical interaction between the laser beam and the limiter working material. The traditional non-threshold model is a particular case of the threshold model when the limiting threshold is zero. The nonlinear characteristics of carbon nanotubes in liquid and solid media are obtained from experimental Z-scan data. Specifically, the nonlinear threshold effect was observed for aqueous dispersions of nanotubes, but not for nanotubes in solid polymethylmethacrylate. The threshold model fits the experimental Z-scan data better than the non-threshold model. Output characteristics were obtained that integrally describe the nonlinear properties of the optical limiters.

  13. Observation of suppressed Auger mechanism in type-I quantum well structures with delocalized electron-hole wavefunctions

    SciTech Connect

    Hassani Nia, Iman; Fathipour, Vala; Mohseni, Hooman

    2015-08-15

    We report the first observation of non-threshold Auger mechanism for a quantum well structure with Type-I band alignment. Excitation-dependent photoluminescence measurements were used to extract the Auger recombination coefficients from 77 K up to room temperature. The results verify the role of interface mediated momentum exchange as well as suppression of Auger recombination for delocalized electron-hole wavefunctions.

  14. Effects of cobalt-60 exposure on health of Taiwan residents suggest new approach needed in radiation protection.

    PubMed

    Chen, W L; Luan, Y C; Shieh, M C; Chen, S T; Kung, H T; Soong, K L; Yeh, Y C; Chou, T S; Mong, S H; Wu, J T; Sun, C P; Deng, W P; Wu, M F; Shen, M L

    2006-08-25

    The conventional approach for radiation protection is based on the ICRP's linear, no threshold (LNT) model of radiation carcinogenesis, which implies that ionizing radiation is always harmful, no matter how small the dose. But a different approach can be derived from the observed health effects of the serendipitous contamination of 1700 apartments in Taiwan with cobalt-60 (T(1/2) = 5.3 y). This experience indicates that chronic exposure of the whole body to low-dose-rate radiation, even accumulated to a high annual dose, may be beneficial to human health. Approximately 10,000 people occupied these buildings and received an average radiation dose of 0.4 Sv, unknowingly, during a 9-20 year period. They did not suffer a higher incidence of cancer mortality, as the LNT theory would predict. On the contrary, the incidence of cancer deaths in this population was greatly reduced-to about 3 per cent of the incidence of spontaneous cancer death in the general Taiwan public. In addition, the incidence of congenital malformations was also reduced--to about 7 per cent of the incidence in the general public. These observations appear to be compatible with the radiation hormesis model. Information about this Taiwan experience should be communicated to the public worldwide to help allay its fear of radiation and create a positive impression about important radiation applications. Expenditures of many billions of dollars in nuclear reactor operation could be saved and expansion of nuclear electricity generation could be facilitated. In addition, this knowledge would encourage further investigation and implementation of very important applications of total-body, low-dose irradiation to treat and cure many illnesses, including cancer. The findings of this study are such a departure from expectations, based on ICRP criteria, that we believe that they ought to be carefully reviewed by other, independent organizations and that population data not available to the authors be provided

  15. [Effects of radiation exposure on human body].

    PubMed

    Kamiya, Kenji; Sasatani, Megumi

    2012-03-01

    There are two types of radiation health effect; acute disorder and late on-set disorder. Acute disorder is a deterministic effect that the symptoms appear by exposure above a threshold. Tissues and cells that compose the human body have different radiation sensitivity respectively, and the symptoms appear in order, from highly radiosensitive tissues. The clinical symptoms of acute disorder begin with a decrease in lymphocytes, and then the symptoms appear such as alopecia, skin erythema, hematopoietic damage, gastrointestinal damage, central nervous system damage with increasing radiation dose. Regarding the late on-set disorder, a predominant health effect is the cancer among the symptoms of such as cancer, non-cancer disease and genetic effect. Cancer and genetic effect are recognized as stochastic effects without the threshold. When radiation dose is equal to or more than 100 mSv, it is observed that the cancer risk by radiation exposure increases linearly with an increase in dose. On the other hand, the risk of developing cancer through low-dose radiation exposure, less 100 mSv, has not yet been clarified scientifically. Although uncertainty still remains regarding low level risk estimation, ICRP propound LNT model and conduct radiation protection in accordance with LNT model in the low-dose and low-dose rate radiation from a position of radiation protection. Meanwhile, the mechanism of radiation damage has been gradually clarified. The initial event of radiation-induced diseases is thought to be the damage to genome such as radiation-induced DNA double-strand breaks. Recently, it is clarified that our cells could recognize genome damage and induce the diverse cell response to maintain genome integrity. This phenomenon is called DNA damage response which induces the cell cycle arrest, DNA repair, apoptosis, cell senescence and so on. These responses act in the direction to maintain genome integrity against genome damage, however, the death of large number of

  16. CRADA Final Report: Mechanisms of Sulfur Poisoning of NOx Adsorber Materials

    SciTech Connect

    Kim, Do Heui; Muntean, George G.; Peden, Charles H. F.; Howden, Ken; Stafford, Randy; Stang, John; Yezerets, Aleksey; Currier, Neal; Chen, H. -Y.; Hess, H.

    2009-03-01

    The control of NOx (NO and NO2) emissions from so-called ‘lean-burn’ vehicle engines remains a challenge. The now commercial NOx adsorber (also known as lean-NOx trap (LNT) and NOx storage reduction (NSR) catalyst) technology is based upon the concept of storing NOx as nitrates over storage components, typically alkali or alkaline-earth species such as barium, during a lean-burn operation cycle and then reducing the stored nitrates to N2 during fuel-rich conditions over a precious metal catalyst. In part via this successful five-year CRADA project between PNNL and Cummins Inc. (CRADA PNNL/213), Cummins and the Johnson/Matthey Company commercialized this technology on the 2007 Dodge Ram pickup truck. In particular, this CRADA has focused on problems arising from either or both thermal and SO2 deactivation which were impeding the ability of the technology to meet durability standards. The results obtained in this CRADA have provided an essential understanding of these deactivation processes thereby leading to materials and process improvements that enabled the commercialization effort. The objective of this project has been to identify a clear pathway to robust NOx after-treatment solutions for light-duty diesel engines. The project focussed on understanding and characterizing the NOx storage, release and conversion of existing NOx adsorber materials. The impact of sulfur on these processes was studied, with special attention given to methods of regenerating the catalyst in the presence of sulfur and the effects of these regeneration treatments on long-term catalyst durability. Model catalysts and more fully formulated catalysts were both studied. The goal of this project has been to identify and understand the deactivation mechanisms of LNT materials in order to provide more robust systems for diesel after-treatment systems that will meet the key emission standards for NOx. Furthermore, the project aimed to provide information critical to

  17. a Dynamic Light Scattering Study of the Relaxation Dynamics in Aqueous Polymer Gelatin Solutions and Gels.

    NASA Astrophysics Data System (ADS)

    Ren, Shangzhi

    1992-01-01

    The dynamics of the molecular relaxations in semi -dilute polymer solutions and gels has important implications in fundamental physics and technological applications. Dynamic Light Scattering (DLS) techniques directly probe such dynamics by monitoring and analyzing the pattern of fluctuations of the light scattered from polymer molecules. We have employed the DLS to explore the molecular relaxation behavior of thermally reversible, semi-dilute, aqueous gelatin solutions and gels. Our experiment results indicate that there are three relaxation modes in the DLS spectrum for the semi-dilute aqueous gelatin solutions: a fast exponential cooperative diffusion mode, an intermediate power-law mode, and a stretched exponential slow mode. When the system evolves from sol to gel under a thermal quench, the fast mode remains unchanged while the characteristic relaxation time of the slow mode diverges, leaving the power-law intermediate mode most apparent for ~ 5 decades in correlation time. The power -law mode is novel in the experimental studies of the relaxation dynamics in linear polymer chain systems and is found to be q dependent. The DLS data is analyzed under a new scheme separating the dynamic scattering component from the static counterpart developed under the growing chain crosslinking. It is the first attempt ever made to deal with the non-ergodicity effect in the DLS studies not only for the gels, as suggested by Pusey and van Megen (80), but also for the DLS during the sol-gel transitions. We have considered a possible interpretation for the observed relaxation based on anomalous diffusion of < x^2>~ lnt and < x^2 >~ t^beta, with < {rm x}^2> being mean-square-displacement and 0~ lnt behavior is associated with the intermediate power-law relaxation mode while the < x^2>~ t^beta behavior is

  18. Interpretation of the source-specific substantive control measures of the Minamata Convention on Mercury.

    PubMed

    You, Mingqing

    2015-02-01

    Being persistent, toxic, and bio-accumulative, Mercury (Hg) seriously affects the environment and human health. Due to Hg's attribute of long-range environmental transport across national borders, especially through atmospheric transport, no country can fully protect its environment and human health with its own efforts, without global cooperation. The Minamata Convention on Mercury, which was formally adopted and opened for signature in October 2013, is the only global environmental regime on the control of Hg pollution. Its main substantive control measures are source-specific: its phasing-out, phasing-down, and other main substantive requirements all direct to specific categories of pollution sources through the regulation of specific sectors of the economy and social life. This Convention does not take a national quota approach to quantify the Parties' nationwide total allowable consumption or discharge of Hg or Hg compounds, nor does it quantify their nationwide total reduction requirements. This paper attempts to find the underlying reasons for this source-specific approach and offers two interpretations. One possible interpretation is that Hg might be a non-threshold pollutant, i.e., a pollutant without a risk-free value of concentration. The existence of a reference dose (RfD), reference concentration (RfC), provisional tolerable weekly intake (PTWI), minimal risk level (MRL) or other similar reference values of Hg does not necessarily mean that Hg cannot be regarded as non-threshold because such reference values have scientific uncertainties and may also involve policy considerations. Another interpretation is that Hg lacks a feasibly determinable total allowable quantity. There is evidence that negotiators might have treated Hg as non-threshold, or at least accepted that Hg lacks a feasibly determinable total allowable quantity: (1) The negotiators were informed about the serious situations of the current emissions, releases, and legacy deposition; (2

  19. Axial length effects on lean NOx trap performance

    SciTech Connect

    Prikhodko, Vitaly Y; Nguyen, Ke; Choi, Jae-Soon; Daw, C Stuart

    2009-01-01

    The effect of axial length on the NO{sub x} reduction performance of two different commercial Lean NO{sub x} Trap (LNT) monolithic catalysts was experimentally investigated in a bench flow reactor. The washcoat composition of one of the catalysts consisted of Pt and K on {gamma}-Al{sub 2}O{sub 3}; whereas the other catalyst contained a complex mixture of Pt, Pd, Rh, Ba, Ce, Zr, Mg, Al and others. The NO{sub x} removal characteristics of cylindrical monolith segments of constant diameter (2.22 cm) and axial lengths of 2.54, 5.08 and 7.62 cm were evaluated using a simulated lean engine exhaust containing water and carbon dioxide at a constant space velocity of 30,000 h{sup -1}. No significant effects of length were observed when the catalysts were fully reduced with hydrogen between NO{sub x} capture phases. However when the catalysts were only partially regenerated NO{sub x} reduction efficiency increased with monolith length. Intra-catalyst H{sub 2} measurements at different axial locations indicated that at least some of the efficiency loss during partial regeneration occurred when back-mixed H{sub 2} was directly oxidized and became unavailable for nitrate reduction.

  20. Fractionated elution using the TEKCIS technetium-99m generator.

    PubMed

    Vigne, Jonathan; De Mil, Rémy; Peyronnet, Damien; Hecquard, Claudine; Agostini, Denis; Lemonnier, Françoise

    2016-06-01

    The TEKCIS technetium-99m (Tc) generator was designed to allow dry column shipment and automatized conception. A high Tc radioactive concentration is required in a subset of radiopharmacy procedures. Fractionated elution can be a useful tool to meet this requirement, especially when current elution is close to the generator expiration date. The aim of our study was to assess TEKCIS generator elution kinetics and to determine the optimal fractionated elution time to fit with procedures requiring the highest Tc radioactive concentration in clinical use. After duplicate elution at several predetermined elution times, the volume and activity of each eluate were measured. Two optimal time points were selected to perform fractionated elution and repeatability (n=34 and 33) assessed on TEKCIS generators calibrated at 6 or 8 GBq. The complete eluate volume (5 ml) was collected after 60 s of elution. A logarithmic equation was established between eluate volume (v, ml) from elapsed elution time (t, s): v=1.8335ln(t)-2.5965. Using the reciprocal equation, elution times required to obtain some commonly eluted volumes were calculated. Fractionated elutions during 15 and 20 s were selected and an average elution volume from 2.74 to 3.27 ml was collected, with an average elution yield of approximately 90 and 100%, respectively. Our work provides a simple and reliable methodology for the use of fractionated elution with the new TEKCIS generator.

  1. Spectroscopic study of copper(II) complexes with carboxymethyl dextran and dextran sulfate

    NASA Astrophysics Data System (ADS)

    Glišić, S.; Nikolić, G.; Cakić, M.; Trutić, N.

    2015-07-01

    The copper(II) ion complexes with carboxymethyl dextran (CMD) and dextran sulfate (DS) were studied by different methods. Content of copper was determined by atomic absorption spectroscopy. It was found that copper : ligand mole ratio (Cu : CMD) is 1 : 2, and Cu : DS is 1 : 1 by mole ratio method. Spectrophotometric parameters of synthesized compounds are characteristic for Cu(II) ion in octahedral ( O h ) coordination. Analyzing of FTIR spectra in ν(C=O) vibration region has showed that -COOH group acts as bidentate ligand, while the compounds of Cu(II) with DS copper ions are in the region of four oxygen atoms of two adjacent sulfo groups. The presence of crystalline water was determined by isotopic substitution of H2O molecules with D2O molecules. Comparison of spectra recorded at room (RT) and liquid nitrogen temperature (LNT) has enabled detection bands of water molecules libration indicating that they are coordinated complementing coordination sphere of Cu(II) ions to six. The complexes are of Cu(II) · (CMD)2 · (H2O)2 or Cu(II) · DS · (H2O)2 type. The similarities of the γ(C-H) range in a part of FTIR spectra indicate that there is no difference in the conformation of the 4 C 1 glucopyranose (Glc) unit CMD and DS synthesized Cu(II) complexes.

  2. Time evolution of distributive entropy in rectangular microchannel mixers

    NASA Astrophysics Data System (ADS)

    Kaufman, Miron; Fodor, Petru

    2009-03-01

    Patterning ridges on the surface of microchannels has been found to be a viable strategy to induce mixing in straight channels, despite the characteristically small Reynolds numbers. In this work we evaluate the time evolution of the R'enyi entropy associated with the spatial distribution of tracers advected by an incompressible fluid moving in several straight rectangular channels: staggered herring bone [1], fractal surface patterning [2]. The steady state flow fields are obtained by solving the Navier -- Stokes and continuity equations using a finite element analysis package. The R'enyi entropy is then evaluated at different times using the spatial distribution of the tracers. The entropy increases with time as lnt with a slope approximately equal to unity. The slope quantifies the rate of distributive mixing. The rate of increase in the entropy is found to be independent of the Renyi beta parameter. This is qualitatively different than the distributive mixing in channels with moving walls [3] where the rate of distributive mixing changes with the beta parameter. We also study the dependence of the distributive entropy on the Reynolds number. [1] A.D. Stroock et al., Science 295, 647 (2002); [2] M. Camesasca, M. Kaufman, I. Manas-Zloczower, J. Micromech. Microeng. 16, 2298 (2006); [3] W. Wang, I. Manas-Zloczower, M. Kaufman, Chemical Engineering Communications, 192(4), 405-423 (2005).

  3. Conformal invariance beyond the leading order in the supersymmetric nonlinear σ model with dilaton

    NASA Astrophysics Data System (ADS)

    Diamandis, G. A.; Georgalas, B. C.; Lahanas, A. B.

    1990-12-01

    We calculate the O(α'3) contributions to the renormalization-group β functions in the N=1 supersymmetric σ model with a dilaton. At this order both metric and dilaton β functions are found to depend nontrivially on the dilaton field and vanish if the dilaton satisfies ∇μ∇νφ=0. By employing the Curci-Paffuti relation it is shown that such dilaton backgrounds in Ricci-flat spaces Rμν=0 satisfy the conformal invariance conditions up to this order. The particular class of Ricci-flat, compact, and orientable manifolds naturally emerge as appropriate internal-space configurations consistent with local scale invariance. We further explore the cosmological consequences of these dilaton configurations. In a Robertson-Walker four-dimensional background we find all dilatons satisfying ∇μ∇νφ=0. Except for the constant and the time-dependent dilaton φ(t)=-2 lnt+λ whose cosmological implications have been already discussed in the literature, additional solutions are found. These may be of relevance beyond leading order and for nonvanishing background values for the antisymmetric tensor Bμν. For these solutions, also the cosmic scale factor is at most linear in time therefore giving rise to either a static or a linearly expanding (contracting) universe.

  4. Inferring spatial distribution of the radially integrated transmissivity from pumping tests in heterogeneous confined aquifers

    NASA Astrophysics Data System (ADS)

    Copty, Nadim K.; Trinchero, Paolo; Sanchez-Vila, Xavier

    2011-05-01

    Hydrologists routinely analyze pumping test data using conventional interpretation methods that are based on the assumption of homogeneity and that, consequently, yield single estimates of representative flow parameters. However, natural subsurface formations are intrinsically heterogeneous, and hence, the flow parameters influencing the drawdown vary as the cone of depression expands in time. In this paper a novel procedure for the analysis of pumping tests in heterogeneous confined aquifers is developed. We assume that a given heterogeneous aquifer can be represented by a homogeneous system whose flow parameters evolve in time as the pumping test progresses. At any point in time, the interpreted flow parameters are estimated using the ratio of the drawdown and its derivative observed at that particular time. The procedure is repeated for all times, yielding time-dependent estimates of transmissivity Ti(t) and storativity, Si(t). Based on the analysis of the sensitivity of drawdown to inhomogeneities in the T field, the time-dependent interpreted transmissivity values are found to be a good estimate of Tg(r), the geometric mean of the transmissivity values encompassed within a progressively increasing radius r from the well. The procedure is illustrated for Gaussian heterogeneous fields with ln(T) variances up to a value of 2. The impact of the separation distance between the pumping well and observation point on data interpretation is discussed. The results show that information about the spatial variability of the transmissivity field can be inferred from time-drawdown data collected at a single observation point.

  5. Catalytic activity of acid and base with different concentration on sol-gel kinetics of silica by ultrasonic method.

    PubMed

    Das, R K; Das, M

    2015-09-01

    The effects of both acid (acetic acid) and base (ammonia) catalysts in varying on the sol-gel synthesis of SiO2 nanoparticles using tetra ethyl ortho silicate (TEOS) as a precursor was determined by ultrasonic method. The ultrasonic velocity was received by pulsar receiver. The ultrasonic velocity in the sol and the parameter ΔT (time difference between the original pulse and first back wall echo of the sol) was varied with time of gelation. The graphs of ln[ln1/ΔT] vs ln(t), indicate two region - nonlinear region and a linear region. The time corresponds to the point at which the non-linear region change to linear region is considered as gel time for the respective solutions. Gelation time is found to be dependent on the concentration and types of catalyst and is found from the graphs based on Avrami equation. The rate of condensation is found to be faster for base catalyst. The gelation process was also characterized by viscosity measurement. Normal sol-gel process was also carried out along with the ultrasonic one to compare the effectiveness of ultrasonic. The silica gel was calcined and the powdered sample was characterized with scanning electron microscopy, energy dispersive spectra, X-ray diffractogram, and FTIR spectroscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Alpha List of Prime Contract Awards. Oct 91 - Sep 92. FY 92 (Branscome Julius Inc - Chriscott Supply)

    DTIC Science & Technology

    1993-01-01

    LL M Mn AULA oLALALALAWW0WfL A LAWII* n~LntLAWOLAUmLAiflLALA LAWWLA WIALAWLALA it I (0-4ŕ ifI -4-1-4 _q4 -1 -f -4 -1- -4 -4 -4 .- f ’ -4 ’ -4 -.4. -4...cc M tic o 0 C113 ɛ -4 11 Z)0000anionoon => u C) 0 U u (-) C) 0 :D (-) D C) D C) (.) = 0 D a : uj I m C, -- 4 It m 0 o v Cp 0 o 0 Cý 0 C> o 00 cr) 0...Z -4O0 C -- 0 MC C O C 4 0 C 00 OC- ccN wm0’)- a0CC- C0 2 2 C- "c) CD(I.- 2 O) CC 0) C 030N 14zCC .20 <>Z 0z 02 tic CX 0.1 z 2 2 00 0 Wcoc CC E C

  7. Effective field theory and dispersion law of the phonons of a nonrelativistic superfluid

    SciTech Connect

    Escobedo, Miguel Angel; Manuel, Cristina

    2010-08-15

    We study the recently proposed effective-field theory for the phonon of an arbitrary nonrelativistic superfluid. After computing the one-loop phonon self-energy, we obtain the low-temperature T contributions to the phonon dispersion law at low momentum and see that the real part of those can be parametrized as a thermal correction to the phonon velocity. Because the phonons are the quanta of the sound waves, at low momentum their velocity should agree with the speed of sound. We find that our results match at order T{sup 4}lnT with those predicted by Andreev and Khalatnikov for the speed of sound, derived from the superfluid hydrodynamical equations and the phonon kinetic theory. We get also higher-order corrections of order T{sup 4}, which are not reproduced pushing naively the kinetic theory computation. Finally, as an application, we consider the cold Fermi gas in the unitarity limit and find a universal expression for the low-T relative correction to the speed of sound for these systems.

  8. A Portable Emissions Measurement System (PEMS) study of NOx and primary NO2 emissions from Euro 6 diesel passenger cars and comparison with COPERT emission factors

    NASA Astrophysics Data System (ADS)

    O'Driscoll, Rosalind; ApSimon, Helen M.; Oxley, Tim; Molden, Nick; Stettler, Marc E. J.; Thiyagarajah, Aravinth

    2016-11-01

    Real world emissions of oxides of nitrogen (NOx) often greatly exceed those achieved in the laboratory based type approval process. In this paper the real world emissions from a substantial sample of the latest Euro 6 diesel passenger cars are presented with a focus on NOx and primary NO2. Portable Emissions Measurement System (PEMS) data is analysed from 39 Euro 6 diesel passenger cars over a test route comprised of urban and motorway sections. The sample includes vehicles installed with exhaust gas recirculation (EGR), lean NOx traps (LNT), or selective catalytic reduction (SCR). The results show wide variability in NOx emissions from 1 to 22 times the type approval limit. The average NOx emission, 0.36 (sd. 0.36) g km-1, is 4.5 times the Euro 6 limit. The average fraction primary NO2 (fNO2) is 44 (sd. 20) %. Higher emissions during the urban section of the route are attributed to an increased number of acceleration events. Comparisons between PEMS measurements and COPERT speed dependent emissions factors show PEMS measurements to be on average 1.6 times higher than COPERT estimates for NOx and 2.5 times for NO2. However, by removing the 5 most polluting vehicles average emissions were reduced considerably.

  9. EPA’s Stage 2 Disinfection Byproducts Rules (DBPR) and Northern Kentucky Water: An Economic and Scientific Review

    PubMed Central

    Henry, Hugh

    2013-01-01

    Implementation of EPA’s Stage 2 Disinfection Byproducts Rules (DBPR) in Northern Kentucky will cause a water rate increase of over 25%. Hence a review was undertaken, considering both economics and science in the context of President Obama’s 2009 scientific integrity directive. The rules purport to avoid up to 0.49% of new bladder cancers by reducing the levels of DBPs in drinking water – a benefit so small that failure to implement will not cause unreasonable risk to health (URTH). It suggests at most one Northern Kentucky death avoided over 17 years for a cost of $136,000,000 ($1700 per household). Even this small benefit is probably overstated. EPA finds no “causal link” between DBPs and bladder cancer, and EPA acknowledges problems with the epidemiological data used in their calculation: the data appear contradictory and inconsistent, may be skewed toward “positive” results, and suggest different cancer sites than animal studies. Two similar international agencies disagree with EPA’s conclusions. The science is based on the Linear No Threshold (LNT) dose response model for DBPs, but this may not be the correct model. 83% of EPA’s epidemiological data show a statistical possibility that low levels of DBPs might be beneficial or have no effect. PMID:24298228

  10. Mesoscopic structure of neuronal tracts from time-dependent diffusion

    PubMed Central

    Burcaw, Lauren M.; Fieremans, Els; Novikov, Dmitry S.

    2015-01-01

    Interpreting brain diffusion MRI measurements in terms of neuronal structure at a micrometer level is an exciting unresolved problem. Here we consider diffusion transverse to a bundle of fibers, and show theoretically, as well as using Monte Carlo simulations and measurements in a phantom made of parallel fibers mimicking axons, that the time dependent diffusion coefficient approaches its macroscopic limit slowly, in a (lnt)/t fashion. The logarithmic singularity arises due to short range disorder in the fiber packing. We identify short range disorder in axonal fibers based on histological data from the splenium, and argue that the time dependent contribution to the overall diffusion coefficient from the extra-axonal water dominates that of the intra-axonal water. This dominance may explain the bias in measuring axon diameters in clinical settings. The short range disorder is also reflected in the linear frequency dependence of the diffusion coefficient measured with oscillating gradients, in agreement with recent experiments. Our results relate the measured diffusion to the mesoscopic structure of neuronal tissue, uncovering the sensitivity of diffusion metrics to axonal arrangement within a fiber tract, and providing an alternative interpretation of axonal diameter mapping techniques. PMID:25837598

  11. Functional films of maleic anhydride copolymers under physiological conditions.

    PubMed

    Pompe, Tilo; Renner, Lars; Grimmer, Milauscha; Herold, Nicole; Werner, Carsten

    2005-09-16

    Reactivity and swelling of nanometer films of alternating maleic anhydride copolymers were investigated in dependence on the kind of comonomer and molar mass of copolymer in aqueous solution at pH 7.4 and pH 3.0 in order to reveal their characteristics under physiological conditions. Fully hydrolyzed (maleic acid) chains of the copolymers with styrene, propene, and ethylene comonomers covalently bound to SiO2 substrates showed a "mushroom" swelling behavior at pH 7.4 with a layer thickness scaling of N3/5. Decreasing the environmental pH was found to induce a comonomer-dependent shrinking or collapse of the immobilized polymers due to the change in ionization. From the swelling kinetics of non-hydrolyzed chains, the time constants and characteristics of swelling and anhydride hydrolysis were determined and found to depend on the type of comonomer. The short- and long-term swelling kinetics [l approximately t and approximately ln(t)1/2] were found to be in agreement with theoretical models of polymer swelling, while at intermediate time scales enhanced swelling was observed due to hydrolysis reaction of maleic anhydride groups. The findings elucidate the variety of properties of maleic anhydride copolymer films under physiological conditions, which can advantageously be applied for biofunctionalization of different templates.

  12. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand.

    PubMed

    Kanchana Devi, A; Ramesh, R

    2014-01-03

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E=P or As; X=Cl or Br; L=binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx≠gy≠gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (Ru(III)-Ru(III)/Ru(III)-Ru(IV); Ru(III)-Ru(IV)/Ru(IV)-Ru(IV)) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  13. Thermal conductivity measurement in clay dominant consolidated material by Transient Hot-Wire method.

    NASA Astrophysics Data System (ADS)

    Garnier, J. P.; Gallier, J.; Mercx, B.; Dudoignon, P.; Milcent, D.

    2010-06-01

    The transient hot-wire (THW) technique is widely used for measurements of the thermal-conductivity of most fluids and some attempts have also been carried out for simultaneous measurements of the thermal-diffusivity with the same hot wire. This technique was also tried to determine thermal properties of soils by the mean of probes which can be considered as wire with some assumptions. The purpose of this paper is to validate the thermal conductivity measurement by the THW technique in geomaterials, composed of compacted sand + clay mineral that can be used for earth construction (Compacted Earth Brick). The thermal transfer behaviors are mainly governed by the texture and moisture of the geomaterials. Thus the investigations were performed (1) in media made of glass beads of different diameters in dry and saturated state in order to observe the role of grain sizes and saturation state on the wire temperature (Δt) measurements and (2) in the compacted clay-geomaterial at different moisture states. The Δt / ln(t) diagrams allow the calculation of two thermal conductivities. The first one, measured in the short time acquisition (< 1s), characterizes the microtexture of the material and its hydrated state. The second one, measured for longer time acquisitions, characterizes the mean thermal conductivity of the material.

  14. Reduction in mutation frequency by very low-dose gamma irradiation of Drosophila melanogaster germ cells.

    PubMed

    Ogura, Keiji; Magae, Junji; Kawakami, Yasushi; Koana, Takao

    2009-01-01

    To determine whether the linear no-threshold (LNT) model for stochastic effects of ionizing radiation is applicable to very low-dose radiation at a low dose rate, we irradiated immature male germ cells of the fruit fly, Drosophila melanogaster, with several doses of (60)Co gamma rays at a dose rate of 22.4 mGy/h. Thereafter, we performed the sex-linked recessive lethal mutation assay by mating the irradiated males with nonirradiated females. The mutation frequency in the group irradiated with 500 microGy was found to be significantly lower than that in the control group (P < 0.01), whereas in the group subjected to 10 Gy irradiation, the mutation frequency was significantly higher than that in the control group (P < 0.03). A J-shaped dose-response relationship was evident. Molecular experiments using DNA microarray and quantitative reverse transcription PCR indicated that several genes known to be expressed in response to heat or chemical stress and grim, a positive regulator of apoptosis, were up-regulated immediately after irradiation with 500 microGy. The involvement of an apoptosis function in the non-linear dose-response relationship was suggested.

  15. The New Radiobiology: Returning to Our Roots

    PubMed Central

    Ulsh, Brant A.

    2012-01-01

    In 2005, two expert advisory bodies examined the evidence on the effects of low doses of ionizing radiation. The U.S. National Research Council concluded that current scientific evidence is consistent with the linear no-threshold dose-response relationship (NRCNA 2005) while the French National Academies of Science and Medicine concluded the opposite (Aurengo et al. 2005). These contradictory conclusions may stem in part from an emphasis on epidemiological data (a “top down” approach) versus an emphasis on biological mechanisms (a “bottom up” approach). In this paper, the strengths and limitations of the top down and bottom up approaches are discussed, and proposals for strengthening and reconciling them are suggested. The past seven years since these two reports were published have yielded increasing evidence of nonlinear responses of biological systems to low radiation doses delivered at low dose-rates. This growing body of evidence is casting ever more doubt on the extrapolation of risks observed at high doses and dose-rates to estimate risks associated with typical environmental and occupational exposures. This paper compares current evidence on low dose, low dose-rate effects against objective criteria of causation. Finally, some questions for a post-LNT world are posed. PMID:23304107

  16. Geographic List of Prime Contract Awards. Oct 1992-Sep 1993. FY 1993. (Alachua, Florida-DeKalb, Georgia). Part 4

    DTIC Science & Technology

    1994-03-01

    3V 10 100 Nf I (000 N - Sig t o( a0) a) -N -- 4N4) cN -0)0 r, P,( 6N -to) z N 1 (00 N c 1L.nt S-N ItnfV)go S-c S-4 n a)) S-t G -ON SU -- -o S-to Y wN I...Q m m) mo 04I)45 , 1)~vL 0(i) mooc )- A M311)o1Coo)I C04~) 0 IS 1 CIO 00 Go L-W000.4(0 L.Nr L. W IN-W44N(0wmow0( CN L. M0 (n L. 4*N L. CDV(0ILn IS OC...4(W X( n Xw fw V ; a4 D( D(0C D( 4c0 ID v a. N 4c1o 0 m -v 1`4 a)(7)a) x a) x 00 00() MOOc U 7) 0 rn0) ( ) a)a) 0) 00) LU0) 00y) Z U Ic (0 0- 11100

  17. Irradiation response and stability of nanoporous materials

    SciTech Connect

    Fu, Engang; Wang, Yongqiang; Serrano De Caro, Magdalena; Caro, Jose A.; Zepeda-Ruiz, L; Bringa, E.; Nastasi, Mike; Baldwin, Jon K.

    2012-08-28

    Nanoporous materials consist of a regular organic or inorganic framework supporting a regular, porous structure. Pores are by definition roughly in the nanometre range, that is between 0.2 nm and 100 nm. Nanoporous materials can be subdivided into 3 categories (IUPAC): (1) Microporous materials - 0.2-2 nm; (2) Mesoporous materials - 2-50 nm; and (3) Macroporous materials - 50-1000 nm. np-Au foams were successfully synthesized by de-alloying process. np-Au foams remain porous structure after Ne ion irradiation to 1 dpa. Stacking Fault Tetrahedra (SFTs) were observed in RT irradiated np-Au foams under the highest and intermediate fluxes, but not under the lowest flux. SFTs were not observed in LNT irradiated np-Au foams under all fluxes. The vacancy diffusivity in Au at RT is high enough so that the vacancies have enough time to agglomerate and then collapse to form SFTs. The high ion flux creates more damage per unit time; vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed at high ion fluxes.

  18. Ergodic properties of fractional Brownian-Langevin motion.

    PubMed

    Deng, Weihua; Barkai, Eli

    2009-01-01

    We investigate the time average mean-square displacement delta;{2}[over ](x(t))=integral_{0};{t-Delta}[x(t;{'}+Delta)-x(t;{'})];{2}dt;{'}(t-Delta) for fractional Brownian-Langevin motion where x(t) is the stochastic trajectory and Delta is the lag time. Unlike the previously investigated continuous-time random-walk model, delta;{2}[over ] converges to the ensemble average x;{2} approximately t;{2H} in the long measurement time limit. The convergence to ergodic behavior is slow, however, and surprisingly the Hurst exponent H=3/4 marks the critical point of the speed of convergence. When H<3/4 , the ergodicity breaking parameter E_{B}=[[delta;{2}[over ](x(t))];{2}-delta;{2}[over ](x(t));{2}]/delta;{2}[over ](x(t));{2} approximately k(H)Deltat;{-1} , when H=3/4 , E_{B} approximately (9/16)(lnt)Deltat;{-1} , and when 3/41 ergodicity is broken and E_{B} approximately 2 . The critical point H=3/4 is marked by the divergence of the coefficient k(H) . Fractional Brownian motion as a model for recent experiments of subdiffusion of mRNA in the cell is briefly discussed, and a comparison with the continuous-time random-walk model is made.

  19. Long-time tails in two-dimensional fluids by molecular dynamics

    NASA Astrophysics Data System (ADS)

    Ferrario, Mauro; Fionino, Antonino; Ciccotti, Giovanni

    1997-02-01

    We report on molecular dynamics simulation of long-time tails in the velocity and stress autocorrelation functions of a dense two-dimensional fluid. Large systems of the order of hundred thousand particles have been investigated, performing canonical averages over an ensemble of trajectories generated on a parallel computer. We find the well-known t-1 decay for the velocity autocorrelation function at two different densities of the fluid, together with a faster than linear time dependence for the mean-square displacement at long times. Although there are indications of an asymptotically faster decay, the data are not precise enough to discriminate whether the decay is in agreement with the (t lnt ) -1 prediction of consistent mode-coupling theory or it is due to finite size effects. No evidence, within the statistical errors, is found for a long-time tail in the stress autocorrelation function. This finding is in agreement with recent NEMD results [Hoover et al., Phys. Rev. E 51 (1995) 273; Gravina et al., Phys. Rev. E 52 (1995) 6123], who find an analytical dependence of the shear viscosity upon the shear rate with no evidence for divergence in the Green-Kubo value.

  20. Ergodic properties of fractional Brownian-Langevin motion

    NASA Astrophysics Data System (ADS)

    Deng, Weihua; Barkai, Eli

    2009-01-01

    We investigate the time average mean-square displacement δ2¯(x(t))=∫0t-Δ[x(t'+Δ)-x(t')]2dt'/(t-Δ) for fractional Brownian-Langevin motion where x(t) is the stochastic trajectory and Δ is the lag time. Unlike the previously investigated continuous-time random-walk model, δ2¯ converges to the ensemble average ⟨x2⟩˜t2H in the long measurement time limit. The convergence to ergodic behavior is slow, however, and surprisingly the Hurst exponent H=(3)/(4) marks the critical point of the speed of convergence. When H<(3)/(4) , the ergodicity breaking parameter EB=[⟨[δ2¯(x(t))]2⟩-⟨δ2¯(x(t))⟩2]/⟨δ2¯(x(t))⟩2˜k(H)Δt-1 , when H=(3)/(4) , EB˜((9)/(16))(lnt)Δt-1 , and when (3)/(4)

  1. Localized electrons on a lattice with incommensurate magnetic flux

    NASA Astrophysics Data System (ADS)

    Fishman, Shmuel; Shapir, Yonathan; Wang, Xiang-Rong

    1992-11-01

    The magnetic-field effects on lattice wave functions of Hofstadter electrons strongly localized at boundaries are studied analytically and numerically. The exponential decay of the wave function is modulated by a field-dependent amplitude J(t)=tprodt-1r=02 cos(παr), where α is the magnetic flux per plaquette (in units of a flux quantum) and t is the distance from the boundary (in units of the lattice spacing). The behavior of ||J(t)|| is found to depend sensitively on the value of α. While for rational values α=p/q the envelope of J(t) increases as 2t/q, the behavior for α irrational (q-->∞) is erratic with an aperiodic structure which drastically changes with α. For algebraic α it is found that J(t) increases as a power law tβ(α) while it grows faster (presumably as tβ(α)lnt) for transcendental α. This is very different from the growth rate J(t)~e√t that is typical for cosines with random phases. The theoretical analysis is extended to products of the type Jν(t)=tprodt-1r=02 cos(παrν) with ν>0. Different behavior of Jν(t) is found in various regimes of ν. It changes from periodic for small ν to randomlike for large ν.

  2. Synthesis, crystal structure and spectroscopic and electrochemical properties of bridged trisbenzoato copper-zinc heterobinuclear complex of 2,2‧-bipyridine

    NASA Astrophysics Data System (ADS)

    Koch, Angira; Kumar, Arvind; Singh, Suryabhan; Borthakur, Rosmita; Basumatary, Debajani; Lal, Ram A.; Shangpung, Sankey

    2015-03-01

    The synthesis of the heterobinuclear copper-zinc complex [CuZn(bz)3(bpy)2]ClO4 (bz = benzoate) from benzoic acid and bipyridine is described. Single crystal X-ray diffraction studies of the heterobinuclear complex reveals the geometry of the benzoato bridged Cu(II)-Zn(II) centre. The copper or zinc atom is pentacoordinate, with two oxygen atoms from bridging benzoato groups and two nitrogen atoms from one bipyridine forming an approximate plane and a bridging oxygen atom from a monodentate benzoate group. The Cu-Zn distance is 3.345 Å. The complex is normal paramagnetic having μeff value equal to 1.75 BM, ruling out the possibility of Cu-Cu interaction in the structural unit. The ESR spectrum of the complex in CH3CN at RT exhibit an isotropic four line spectrum centred at g = 2.142 and hyperfine coupling constants Aav = 63 × 10-4 cm-1, characteristic of a mononuclear square-pyramidal copper(II) complexes. At LNT, the complex shows an isotropic spectrum with g|| = 2.254 and g⊥ = 2.071 and A|| = 160 × 10-4 cm-1. The Hamiltonian parameters are characteristic of distorted square pyramidal geometry. Cyclic voltammetric studies of the complex have indicated quasi-reversible behaviour in acetonitrile solution.

  3. Phase Evolution upon Aging of Air-Plasma Sprayed t'-Zirconia Coatings: I-Synchrotron X-Ray Diffraction

    SciTech Connect

    Lipkin, Don M; Krogstad, Jessica A; Gao, Yan; Johnson, Curtis A; Nelson, Warren A; Levi, Carlos G

    2012-10-08

    Phase evolution accompanying the isothermal aging of free-standing air-plasma sprayed (APS) 7–8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) is described. Aging was carried out at temperatures ranging from 982°C to 1482°C in air. The high-temperature kinetics of the phase evolution from the metastable t' phase into a mixture of transformable Y-rich (cubic) and Y-lean (tetragonal) phases are documented through ambient temperature X-ray diffraction (XRD) characterization. A Hollomon–Jaffe parameter (HJP), T[27 + ln(t)], was used to satisfactorily normalize the extent of phase decomposition over the full range of times and temperatures. Comparison to vapor deposited TBCs reveal potential differences in the destabilization mechanism in APS coatings. Furthermore, the lattice parameters extracted from Rietveld refinement of the XRD patterns were used to deduce the stabilizer concentrations of the respective phases, which suggest a retrograde tetragonal solvus over the temperature range studied. In concert with a complementary microstructural study presented in Part II, this effort offers new insights into the mechanisms governing the phase evolution and raises implications for the high-temperature use of 8YSZ ceramics.

  4. Observation of a new field-induced phase transition and its concomitant quantum critical fluctuations in CeCo(In1 -xZnx )5

    NASA Astrophysics Data System (ADS)

    Yokoyama, Makoto; Mashiko, Hiroaki; Otaka, Ryo; Oshima, Yoshiki; Suzuki, Kohei; Tenya, Kenichi; Shimizu, Yusei; Nakamura, Ai; Aoki, Dai; Kondo, Akihiro; Kindo, Koichi; Nakamura, Shota; Sakakibara, Toshiro

    2017-06-01

    We demonstrate a close connection between observed field-induced antiferromagnetic (AFM) order and quantum critical fluctuation (QCF) in the Zn7%-doped heavy-fermion superconductor CeCoIn5. Magnetization, specific heat, and electrical resistivity at low temperatures all show the presence of new field-induced AFM order under the magnetic field B of 5-10 T, whose order parameter is clearly distinguished from the low-field AFM phase observed for B <5 T and the superconducting phase for B <3 T . The 4f electronic specific heat divided by the temperature, Ce/T , exhibits -lnT dependence at B ˜10 T (≡B0 ), and furthermore, the Ce/T data for B ≥B0 are well scaled by the logarithmic function of B and T : ln[(B -B0) /T2.7] . These features are quite similar to the scaling behavior found in pure CeCoIn5, strongly suggesting that the field-induced QCF in pure CeCoIn5 originates from the hidden AFM order parameter equivalent to high-field AFM order in Zn7%-doped CeCoIn5.

  5. Response properties in the adsorption-desorption model on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Šćepanović, J. R.; Stojiljković, D.; Jakšić, Z. M.; Budinski-Petković, Lj.; Vrhovac, S. B.

    2016-06-01

    The out-of-equilibrium dynamical processes during the reversible random sequential adsorption (RSA) of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. We focused on the influence of the order of symmetry axis of the shape on the response of the reversible RSA model to sudden perturbations of the desorption probability Pd. We provide a detailed discussion of the significance of collective events for governing the time coverage behavior of shapes with different rotational symmetries. We calculate the two-time density-density correlation function C(t ,tw) for various waiting times tw and show that longer memory of the initial state persists for the more symmetrical shapes. Our model displays nonequilibrium dynamical effects such as aging. We find that the correlation function C(t ,tw) for all objects scales as a function of single variable ln(tw) / ln(t) . We also study the short-term memory effects in two-component mixtures of extended objects and give a detailed analysis of the contribution to the densification kinetics coming from each mixture component. We observe the weakening of correlation features for the deposition processes in multicomponent systems.

  6. Organization of growing random networks

    SciTech Connect

    Krapivsky, P. L.; Redner, S.

    2001-06-01

    The organizational development of growing random networks is investigated. These growing networks are built by adding nodes successively, and linking each to an earlier node of degree k with an attachment probability A{sub k}. When A{sub k} grows more slowly than linearly with k, the number of nodes with k links, N{sub k}(t), decays faster than a power law in k, while for A{sub k} growing faster than linearly in k, a single node emerges which connects to nearly all other nodes. When A{sub k} is asymptotically linear, N{sub k}(t){similar_to}tk{sup {minus}{nu}}, with {nu} dependent on details of the attachment probability, but in the range 2{lt}{nu}{lt}{infinity}. The combined age and degree distribution of nodes shows that old nodes typically have a large degree. There is also a significant correlation in the degrees of neighboring nodes, so that nodes of similar degree are more likely to be connected. The size distributions of the in and out components of the network with respect to a given node{emdash}namely, its {open_quotes}descendants{close_quotes} and {open_quotes}ancestors{close_quotes}{emdash}are also determined. The in component exhibits a robust s{sup {minus}2} power-law tail, where s is the component size. The out component has a typical size of order lnt, and it provides basic insights into the genealogy of the network.

  7. Altered native stability is the dominant basis for susceptibility of α1-antitrypsin mutants to polymerization.

    PubMed

    Irving, James A; Haq, Imran; Dickens, Jennifer A; Faull, Sarah V; Lomas, David A

    2014-05-15

    Serpins are protease inhibitors whose most stable state is achieved upon transition of a central 5-stranded β-sheet to a 6-stranded form. Mutations, low pH, denaturants and elevated temperatures promote this transition, which can result in a growing polymer chain of inactive molecules. Different types of polymer are possible, but, experimentally only heat has been shown to generate polymers in vitro consistent with ex vivo pathological specimens. Many mutations that alter the rate of heat-induced polymerization have been described, but interpretation is problematic because discrimination is lacking between the effect of global changes in native stability and specific effects on structural mechanism. We show that the temperature midpoint (Tm) of thermal denaturation reflects the transition of α1-antitrypsin to the polymerization intermediate, and determine the relationship with fixed-temperature polymerization half-times (t0.5) in the presence of stabilizing additives [TMAO (trimethylamine N-oxide), sucrose and sodium sulfate], point mutations and disulfide bonds. Combined with a retrospective analysis of 31 mutants characterized in the literature, the results of the present study show that global changes to native state stability are the predominant basis for the effects of mutations and osmolytes on heat-induced polymerization, summarized by the equation: ln(t0.5,mutant/t0.5,wild-type)=0.34×ΔTm. It is deviations from this relationship that hold key information about the polymerization process.

  8. Nernst effect in the electron-doped cuprate superconductor Pr2-xCexCuO4: Superconducting fluctuations, upper critical field Hc2, and the origin of the Tc dome

    NASA Astrophysics Data System (ADS)

    Tafti, F. F.; Laliberté, F.; Dion, M.; Gaudet, J.; Fournier, P.; Taillefer, Louis

    2014-07-01

    The Nernst effect was measured in the electron-doped cuprate superconductor Pr2-xCexCuO4 (PCCO) at four concentrations, from underdoped (x =0.13) to overdoped (x=0.17), for a wide range of temperatures above the critical temperature Tc. A magnetic field H up to 15 T was used to reliably access the normal-state quasiparticle contribution to the Nernst signal Nqp, which is subtracted from the total signal N, to obtain the superconducting contribution Nsc. As a function of H, Nsc peaks at a field H whose temperature dependence obeys Hc2ln(T /Tc), as it does in a conventional superconductor such as NbxSi1-x. The doping dependence of the characteristic field scale Hc2, shown to be closely related to the upper critical field Hc2, tracks the domelike dependence of Tc, showing that superconductivity is weakened below the quantum critical point where the Fermi surface is reconstructed, presumably by the onset of antiferromagnetic order. Our data at all dopings are quantitatively consistent with the theory of Gaussian superconducting fluctuations, eliminating the need to invoke unusual vortexlike excitations above Tc, and ruling out phase fluctuations as the mechanism for the fall of Tc with underdoping. We compare the properties of PCCO with those of hole-doped cuprates and conclude that the domes of Tc and Hc2 versus doping in the latter materials are also controlled predominantly by phase competition rather than phase fluctuations.

  9. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand

    NASA Astrophysics Data System (ADS)

    Kanchana Devi, A.; Ramesh, R.

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E = P or As; X = Cl or Br; L = binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx ≠ gy ≠ gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (RuIII-RuIII/RuIII-RuIV; RuIII-RuIV/RuIV-RuIV) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  10. Low-Let-Induced Radioprotective Mechanisms Within a Stochastic Two-Stage Cancer Model

    PubMed Central

    Schöllnberger, H.; Stewart, R.D.; Mitchel, R.E.J.

    2005-01-01

    A stochastic two-stage cancer model with clonal expansion was used to investigate the potential impact on human lung cancer incidence of some aspects of the hormesis mechanisms suggested by Feinendegen (Health Phys. 52 663–669, 1987). The model was applied to low doses of low-LET radiation delivered at low dose rates. Non-linear responses arise in the model because radiologically induced adaptations in radical scavenging and DNA repair may reduce the biological consequences of DNA damage formed by endogenous processes and ionizing radiation. Sensitivity studies were conducted to identify critical model inputs and to help define the changes in cellular defense mechanisms necessary to produce a lifetime probability for lung cancer that deviates from a linear no-threshold (LNT) type of response. Our studies suggest that lung cancer risk predictions may be very sensitive to the induction of DNA damage by endogenous processes. For doses comparable to background radiation levels, endogenous DNA damage may account for as much as 50 to 80% of the predicted lung cancers. For an additional lifetime dose of 1 Gy from low-LET radiation, endogenous processes may still account for as much as 20% of the predicted cancers (Fig. 2). When both repair and scavengers are considered as inducible, radiation must enhance DNA repair and radical scavenging in excess of 30 to 40% of the baseline values to produce lifetime probabilities for lung cancer outside the range expected for endogenous processes and background radiation. PMID:18648628

  11. The Adaptive Response, Genetic Haplo-Insufficiency and Genomic Instability

    SciTech Connect

    Geard, Charles R.

    2014-12-12

    The linear no-threshold (LNT) hypothesis is the driving force in the establishment of radiation protection standards. However, the scientific basis for linearity has been brought into question, particularly due to the concerns about induced radiation resistance as it pertains to oxidative stress. Specifically, we investigated the observation that tumor hypoxia is associated with malignant progression, increased metastases, chemo- and radioresistance and poor prognosis. Experiments were conducted with non-malignant 3T3/NIH cells and normal human lung fibroblasts (NHLF) that were subjected to γ-irradiation under the levels of oxygen resembling those in growing tumors, and related our data to the concentrations of dissolved oxygen (DO), which is a better indicator of the amounts of residual oxygen inside the cells cultured in the hypoxic or anoxic atmosphere. We found that at DO levels about 0.5 mg/L cells subjected to both short-term (17 hours) and prolonged (48-72 hours) hypoxia continued to proliferate, and that apoptotic events were decreased at the early hours of hypoxic treatment. We showed that the short-term hypoxia up-regulated p53-binding protein 1 (53BP1) and resulted in facilitated 53BP1 nuclear foci formation and disappearance, thus indicating the higher efficiency of DNA double strand breaks repair processes. The latter was confirmed by the lower micronuclei incidence in irradiated hypoxic cells.

  12. Long-range epidemic spreading in a random environment

    NASA Astrophysics Data System (ADS)

    Juhász, Róbert; Kovács, István A.; Iglói, Ferenc

    2015-03-01

    Modeling long-range epidemic spreading in a random environment, we consider a quenched, disordered, d -dimensional contact process with infection rates decaying with distance as 1 /rd +σ . We study the dynamical behavior of the model at and below the epidemic threshold by a variant of the strong-disorder renormalization-group method and by Monte Carlo simulations in one and two spatial dimensions. Starting from a single infected site, the average survival probability is found to decay as P (t ) ˜t-d /z up to multiplicative logarithmic corrections. Below the epidemic threshold, a Griffiths phase emerges, where the dynamical exponent z varies continuously with the control parameter and tends to zc=d +σ as the threshold is approached. At the threshold, the spatial extension of the infected cluster (in surviving trials) is found to grow as R (t ) ˜t1 /zc with a multiplicative logarithmic correction and the average number of infected sites in surviving trials is found to increase as Ns(t ) ˜(lnt) χ with χ =2 in one dimension.

  13. Long-range epidemic spreading in a random environment.

    PubMed

    Juhász, Róbert; Kovács, István A; Iglói, Ferenc

    2015-03-01

    Modeling long-range epidemic spreading in a random environment, we consider a quenched, disordered, d-dimensional contact process with infection rates decaying with distance as 1/rd+σ. We study the dynamical behavior of the model at and below the epidemic threshold by a variant of the strong-disorder renormalization-group method and by Monte Carlo simulations in one and two spatial dimensions. Starting from a single infected site, the average survival probability is found to decay as P(t)∼t-d/z up to multiplicative logarithmic corrections. Below the epidemic threshold, a Griffiths phase emerges, where the dynamical exponent z varies continuously with the control parameter and tends to zc=d+σ as the threshold is approached. At the threshold, the spatial extension of the infected cluster (in surviving trials) is found to grow as R(t)∼t1/zc with a multiplicative logarithmic correction and the average number of infected sites in surviving trials is found to increase as Ns(t)∼(lnt)χ with χ=2 in one dimension.

  14. Spectroscopy of the Schwarzschild black hole at arbitrary frequencies.

    PubMed

    Casals, Marc; Ottewill, Adrian

    2012-09-14

    Linear field perturbations of a black hole are described by the Green function of the wave equation that they obey. After Fourier decomposing the Green function, its two natural contributions are given by poles (quasinormal modes) and a largely unexplored branch cut in the complex frequency plane. We present new analytic methods for calculating the branch cut on a Schwarzschild black hole for arbitrary values of the frequency. The branch cut yields a power-law tail decay for late times in the response of a black hole to an initial perturbation. We determine explicitly the first three orders in the power-law and show that the branch cut also yields a new logarithmic behavior T(-2ℓ-5)lnT for late times. Before the tail sets in, the quasinormal modes dominate the black hole response. For electromagnetic perturbations, the quasinormal mode frequencies approach the branch cut at large overtone index n. We determine these frequencies up to n(-5/2) and, formally, to arbitrary order. Highly damped quasinormal modes are of particular interest in that they have been linked to quantum properties of black holes.

  15. Toxicological awakenings: the rebirth of hormesis as a central pillar of toxicology

    SciTech Connect

    Calabrese, Edward J. . E-mail: edwardc@schoolph.umass.edu

    2005-04-01

    This paper assesses historical reasons that may account for the marginalization of hormesis as a dose-response model in the biomedical sciences in general and toxicology in particular. The most significant and enduring explanatory factors are the early and close association of the concept of hormesis with the highly controversial medical practice of homeopathy and the difficulty in assessing hormesis with high-dose testing protocols which have dominated the discipline of toxicology, especially regulatory toxicology. The long-standing and intensely acrimonious conflict between homeopathy and 'traditional' medicine (allopathy) lead to the exclusion of the hormesis concept from a vast array of medical- and public health-related activities including research, teaching, grant funding, publishing, professional societal meetings, and regulatory initiatives of governmental agencies and their advisory bodies. Recent publications indicate that the hormetic dose-response is far more common and fundamental than the dose-response models [threshold/linear no threshold (LNT)] used in toxicology and risk assessment, and by governmental regulatory agencies in the establishment of exposure standards for workers and the general public. Acceptance of the possibility of hormesis has the potential to profoundly affect the practice of toxicology and risk assessment, especially with respect to carcinogen assessment.

  16. Improved Radiation Dosimetry/Risk Estimates to Facilitate Environmental Management of Plutonium Contaminated Sites

    SciTech Connect

    Scott, Bobby R.; Cheng, Yung-Sung; Zhou, Yue; Tokarskaya, Zoya B.; Zhuntova, Galina V.

    2003-06-11

    Our Phase II research evaluated health risks associated with inhaled plutonium. Our research objectives were to: (1) extend our stochastic model for deposition of plutonium in the respiratory tract to include additional key variability and uncertainty; (2) generate and analyze risk distributions for deterministic effects in the lung from inhaled plutonium that reflect risk model uncertainty; (3) acquire an improved understanding of key physiological effects of inhaled plutonium, based on evaluations of clinical data (e.g., hematological, respiratory function, chromosomal aberrations in lymphocytes) for Mayak workers in Russia who inhaled plutonium-239; (4) develop biological dosimetry for plutonium-239 that was inhaled by some Mayak workers (with unknown intake) based on clinical data for other workers with known plutonium-239 intake; (5) critically evaluate the validity of the linear no-threshold (LNT) risk model as it relates to cancer risks from inhaled plutonium-239 (base d on Mayak worker data); and (6) evaluate respirator filter penetration frequencies for airborne plutonium aerosols using surrogate high-density metals.

  17. Reaction rate theory of radiation exposure:Effects of dose rate on mutation frequency

    NASA Astrophysics Data System (ADS)

    Bando, Masako; Nakamura, Issei; Manabe, Yuichiro

    2014-03-01

    We revisit the linear no threshold (LNT) hypothesis deduced from the prominent works done by H. J. Muller for the DNA mutation induced by the artificial radiation and by W. L. Russell and E. M. Kelly for that of mega-mouse experiments, developing a new kinetic reaction theory. While the existing theoretical models primarily rely on the dependence of the total dose D on the mutation frequency, the key ingredient in our theory is the dose rate d(t) that accounts for decrease in the mutation rate during the time course of the cellular reactions. The general form for the mutation frequency with the constant dose rate d is simply expressed as, dFm(t)/dt = A - BFm(t) , with A =a0 +a1(d +deff) and B =b0 +b1(d +deff) . We discuss the solution for a most likely case with B > 0 ; Fm(t) = [A/B -Fm(0) ] (1 -e-Bt) +Fm(0) with the control value Fm(0) . We show that all the data of mega-mouse experiments by Russel with different dose rates fall on the universal scaling function Φ(τ) ≡ [Fm(τ) -Fm(0) ]/[ A / B -Fm(0) ] = 1 - exp(- τ) with scaled time τ = Bt . The concept of such a scaling rule provides us with a strong tool to study different species in a unified manner.

  18. Dosimeter-Type NOx Sensing Properties of KMnO4 and Its Electrical Conductivity during Temperature Programmed Desorption

    PubMed Central

    Groβ, Andrea; Kremling, Michael; Marr, Isabella; Kubinski, David J.; Visser, Jacobus H.; Tuller, Harry L.; Moos, Ralf

    2013-01-01

    An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release. PMID:23549366

  19. Magnetotransport study of Kondo compound Ce(Ni0.7Cu0.3)2Al3

    NASA Astrophysics Data System (ADS)

    Yadam, Sankararao; Singh, Durgesh; Venkateshwarlu, D.; Gangrade, Mohan Kumar; Samatham, S. Shanmukharao; Ganesan, V.

    2015-06-01

    CeNi2Al3 system has evolved in to a known thermoelectric material with a usable figure of merit at low temperatures. Kondo effect plays a crucial role in the enhancement of TEP in this system especially when the Ni site is substituted with non-magnetic elements like Cu. Effect of high magnetic fields on various properties of this system is yet to be explored. Ce(Ni0.7Cu0.3)2Al3 is a representative sample that has a significant enhancement of TEP whose reasons are being explored recently. Here we report the magnetoresistivity measurements on this sample down to 2K and fields upto 14T. The famous negative ln(T) rise with a minimum at 14.5 K is getting suppressed by the magnetic fields. Magnetic correlations are observed with increasing magnetic field strength in the form of a hump like behavior due to competition between Kondo and RKKY interactions. This hump is shifted to higher temperatures with increase in the field strength which indicates probable onset of ferromagnetic correlations that is being corroborated by the observed negative magnetoresistance at low temperatures.

  20. Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: Synthesis, characterization and catalytic property

    NASA Astrophysics Data System (ADS)

    Raja, N.; Ramesh, R.

    2010-02-01

    Mononuclear ruthenium(III) complexes of the type [RuX(EPh 3) 2(L)] (E = P or As; X = Cl or Br; L = dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX 3(EPh 3) 3] (where E = P, X = Cl; E = As, X = Cl or Br) and [RuBr 3(PPh 3) 2(CH 3OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis and EPR spectral data. These complexes are paramagnetic and show intense d-d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh 3) 2(DHA-PTSC)] ( 5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.

  1. Mycobacterium tuberculosis lipoproteins in virulence and immunity - fighting with a double-edged sword.

    PubMed

    Becker, Katja; Sander, Peter

    2016-11-01

    Bacterial lipoproteins are secreted membrane-anchored proteins characterized by a lipobox motif. This lipobox motif directs post-translational modifications at the conserved cysteine through the consecutive action of three enzymes: Lgt, LspA and Lnt, which results in di- or triacylated forms. Lipoproteins are abundant in all bacteria including Mycobacterium tuberculosis and often involved in virulence and immunoregulatory processes. On the one hand, disruption of the biosynthesis pathway of lipoproteins leads to attenuation of M. tuberculosis in vivo, and mycobacteria deficient for certain lipoproteins have been assessed as attenuated live vaccine candidates. On the other hand, several mycobacterial lipoproteins form immunodominant antigens which promote an immune response. Some of these have been explored in DNA or subunit vaccination approaches against tuberculosis. The immune recognition of specific lipoproteins, however, might also benefit long-term survival of M. tuberculosis through immune modulation, while others induce protective responses. Exploiting lipoproteins as vaccines is thus a complex matter which requires deliberative investigation. The dual role of lipoproteins in the immunity to and pathogenicity of mycobacteria is discussed here. © 2016 Federation of European Biochemical Societies.

  2. Successive superconducting transitions in Ta2S2C studied by electrical resistivity and nonlinear ac magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Suzuki, Masatsugu; Suzuki, Itsuko S.; Noji, Takashi; Koike, Yoji; Walter, Jürgen

    2007-05-01

    Ta2S2C compound undergoes superconducting transitions at Tcl=3.60±0.02K and Tcu=9.0±0.2K . The nature of successive superconducting transitions has been studied from electrical resistivity and linear and nonlinear ac magnetic susceptibilities. The resistivity ρ at H=0 shows a local maximum near Tcu , a kinklike behavior around Tcl , and reduces to zero at below T0=2.1K . The lnT dependence of ρ is observed at H=50kOe at low temperatures, which is due to a two-dimensional weak-localization effect. Below Tcu , a two-dimensional superconducting phase occurs in each TaC layer. The linear and nonlinear susceptibilities χ1″ , χ3' , χ5' , and χ7' as well as the difference δχ (=χFC-χZFC) between the field-cooled (FC) and zero-field-cooled (ZFC) susceptibilities start to appear below 6.0K , the onset temperature of irreversibility. A drastic growth of the in-plane superconducting coherence length below 6.0K gives rise to a three-dimensional superconducting phase below Tcl through interplanar Josephson couplings between adjacent TaC layers. The oscillatory behavior of χ3″ , χ5″ , and χ7″ below Tcl is related to the nonlinear behavior arising from the thermally activated flux flow.

  3. Centrifugal Scaling Laws for Ground Launch Cruise Missile Shelter

    DTIC Science & Technology

    1984-04-01

    d P (46) m n / 31 S... _ _mn. R R p R m R H R 6 Rr m"p m p R .R : n (47)m n AST ASTP AST A H2 AS• = A r~STpx11 : "-"-HT- ASTm :HTJ1 H-H7 Hm p m p...d .. d - (67) m n R R H R*- R zHm) R~•6 TF M • =,q- .R P p m p R .. R (68) m n 45 AST AST ASTM H2 =1 u---• • AST = - AST H H H m H p m p AST A - P...zNQ- [163 LNT0.Ef4TO+1 £17) $FOR R~OW l,(tEmTD)pI ENTCR COLUMN 11(jENTG) E18 ) AEENTD;Z~lT03+-0 C203 4MCRiOw 1213 sO:*’GO:’ E22) TV+-20- E233

  4. Ultrasonic disruption of fungal mycelia for efficient recovery of polysaccharide-protein complexes from viscous fermentation broth of a medicinal fungus.

    PubMed

    Cheung, Yi-Ching; Liu, Xing-Xun; Wang, Wing-Qiang; Wu, Jian-Yong

    2015-01-01

    High-intensity ultrasound (US) was applied to facilitate the extraction of intracellular and extracellular polysaccharide-protein complexes (PSPs) from the viscous mycelial fermentation broth of a medicinal fungus Cordyceps sinensis Cs-HK1. The US treatment caused the disruption of fungal mycelia, a dramatic reduction of the apparent broth viscosity, and the release of intracellular products into the liquid medium. The degree of mycelium disruption and the rate of intracellular product release were dependent on US power intensity, treatment period and biomass concentration of broth. The extraction or release kinetics of total water-soluble products and PSPs (yield Y versus time t) under the effect of US was fitted closely to the Elovich model Y=Yo+Y1 lnt and parabolic model Y=Yo+Y1t(½), respectively. Another interesting effect of the US treatment was a notable increase in the antioxidant cytoprotective activity of PSP against H2O2 induced cell death. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Risk evaluation - conventional and low level effects of radiation

    SciTech Connect

    Bond, V.P.; Varma, M.N.

    1984-04-01

    Any discussion of the risk of exposure to potentially-hazardous agents in the environment inevitably involves the question of whether the dose effect curve is of the threshold or linear, non-threshold type. A principal objective of this presentation is to show that the function is actually two separate relationships, each representing distinctly different functions with differing variables on the axes, and each characteristic of quite different functions with differing variables on the axes, and each characteristic of quite different disciplines (i.e., the threshold function, of Pharmacology, Toxicology and Medicine (PTM); the linear, non-threshold function, of Public Health including safety and accident statistics (PHS)). It is shown that low-level exposure (LLE) to radiation falls clearly in the PHS category. A function for cell dose vs. the fraction of single cell quantal responses is characterized, which reflects the absolute and relative sensitivities of cells. Acceptance of this function would obviate any requirement for the use in Radiation Protection of the concepts of a standard radiation, Q, dose equivalent and rem. 9 references, 4 figures.

  6. The effect of luteinizing hormone releasing hormone analog regime and stage of oocyte maturity for induced ovulation of channel catfish Ictalurus punctatus

    USDA-ARS?s Scientific Manuscript database

    The effective LHRHa (luteinizing hormone releasing hormone analog) dose based on the gonadal maturity of channel catfish, Ictalurus punctatus to optimize channel x blue hybrid catfish production was evaluated in 4 trials (twice in early part of the season and twice in the peak spawning season) in a ...

  7. Using the Concept of "Population Dose" in Planning and Evaluating Community-Level Obesity Prevention Initiatives

    ERIC Educational Resources Information Center

    Cheadle, Allen; Schwartz, Pamela M.; Rauzon, Suzanne; Bourcier, Emily; Senter, Sandra; Spring, Rebecca; Beery, William L.

    2013-01-01

    When planning and evaluating community-level initiatives focused on policy and environment change, it is useful to have estimates of the impact on behavioral outcomes of particular strategies (e.g., building a new walking trail to promote physical activity). We have created a measure of estimated strategy-level impact--"population dose"--based on…

  8. Using the Concept of "Population Dose" in Planning and Evaluating Community-Level Obesity Prevention Initiatives

    ERIC Educational Resources Information Center

    Cheadle, Allen; Schwartz, Pamela M.; Rauzon, Suzanne; Bourcier, Emily; Senter, Sandra; Spring, Rebecca; Beery, William L.

    2013-01-01

    When planning and evaluating community-level initiatives focused on policy and environment change, it is useful to have estimates of the impact on behavioral outcomes of particular strategies (e.g., building a new walking trail to promote physical activity). We have created a measure of estimated strategy-level impact--"population dose"--based on…

  9. Investigation of Aging Mechanisms in Lean NOx Traps

    SciTech Connect

    Mark Crocker

    2010-03-31

    Lean NO{sub x} traps (LNTs) represent a promising technology for the abatement of NO{sub x} under lean conditions. Although LNTs are starting to find commercial application, the issue of catalyst durability remains problematic. LNT susceptibility to sulfur poisoning is the single most important factor determining effective catalyst lifetime. The NO{sub x} storage element of the catalyst has a greater affinity for SO{sub 3} than it does for NO{sub 2}, and the resulting sulfate is more stable than the stored nitrate. Although this sulfate can be removed from the catalyst by means of high temperature treatment under rich conditions, the required conditions give rise to deactivation mechanisms such as precious metal sintering, total surface area loss, and solid state reactions between the various oxides present. The principle objective of this project was to improve understanding of the mechanisms of lean NO{sub x} trap aging, and to understand the effect of washcoat composition on catalyst aging characteristics. The approach utilized involved detailed characterization of model catalysts prior to and after aging, in tandem with measurement of catalyst performance in NO{sub x} storage and reduction. In this manner, NO{sub x} storage and reduction characteristics were correlated with the evolution of catalyst physico-chemical properties upon aging. Rather than using poorly characterized proprietary catalysts, or simple model catalysts of the Pt/BaO/Al{sub 2}O{sub 3} type (representing the first generation of LNTs), Pt/Rh/BaO/Al{sub 2}O{sub 3} catalysts were employed which also incorporated CeO{sub 2} or CeO{sub 2}-ZrO{sub 2}, representing a model system which more accurately reflects current LNT formulations. Catalysts were prepared in which the concentration of each of the main components was systematically varied: Pt (50, 75 or 100 g/ft{sup 3}), Rh (10 or 20 g/ft{sup 3}), BaO (15, 30 or 45 g/L), and either CeO{sub 2} (0, 50 or 100 g/L) or CeO{sub 2}-ZrO{sub 2} (0, 50

  10. Biological-Based Modeling of Low Dose Radiation Risks

    SciTech Connect

    Scott, Bobby R., Ph.D.

    2006-11-08

    The objective of this project was to refine a biological-based model (called NEOTRANS2) for low-dose, radiation-induced stochastic effects taking into consideration newly available data, including data on bystander effects (deleterious and protective). The initial refinement led to our NEOTRANS3 model which has undergone further refinement (e.g., to allow for differential DNA repair/apoptosis over different dose regions). The model has been successfully used to explain nonlinear dose-response curves for low-linear-energy-transfer (LET) radiation-induced mutations (in vivo) and neoplastic transformation (in vitro). Relative risk dose-response functions developed for neoplastic transformation have been adapted for application to cancer relative risk evaluation for irradiated humans. Our low-dose research along with that conducted by others collectively demonstrate the following regarding induced protection associated with exposure to low doses of low-LET radiation: (1) protects against cell killing by high-LET alpha particles; (2) protects against spontaneous chromosomal damage; (3) protects against spontaneous mutations and neoplastic transformations; (4) suppresses mutations induced by a large radiation dose even when the low dose is given after the large dose; (5) suppresses spontaneous and alpha-radiation-induced cancers; (6) suppresses metastasis of existing cancer; (7) extends tumor latent period; (8) protects against diseases other than cancer; and (9) extends life expectancy. These forms of radiation-induced protection are called adapted protection as they relate to induced adaptive response. Thus, low doses and dose rates of low-LET radiation generally protect rather than harm us. These findings invalidate the linear not threshold (LNT) hypothesis which is based on the premise that any amount of radiation is harmful irrespective of its type. The hypothesis also implicates a linear dose-response curve for cancer induction that has a positive slope and no

  11. Anomalies and peculiarities of radiation-induced light absorption in pure silica optical fibers at different temperatures

    NASA Astrophysics Data System (ADS)

    Kashaykin, Pavel F.; Tomashuk, Alexander L.; Salgansky, Mikhail Yu.; Guryanov, Alexey N.; Dianov, Evgeny M.

    2017-06-01

    Undoped-silica-core F-doped-silica-cladding optical fibers ("undoped fibers") are an important fiber type for applications requiring resistance to ionizing radiation (e.g., the nuclear industry, space, and military applications), the most important fundamental radiation-induced color centers arising in such fibers being self-trapped holes (STH). Despite the previous in-depth STH investigations, there have remained a few not-fully understood issues, such as the relationship between the radiation-induced absorption (RIA) bands due to STH in undoped fibers, on the one hand, and in bulk silica samples, on the other, the role of strain in the silica network in the STH occurrence, and possible peculiarities of short-lived STH-like radiation-induced color centers at temperatures above RT. To address these issues, we investigate the RIA spectra in undoped fibers with different frozen-in strain in their silica network immediately in the process of γ-irradiation to a dose of 1 kGy, the irradiation temperature being in the range ±60 °C or liquid nitrogen temperature (LNT). Gaussian decomposition of the RIA spectra measured at LNT has yielded STH bands at 2.6 and 2.16 eV together with the "classical" STH bands at 1.88 and 1.63 eV observed in fibers more frequently than the former bands. Based on this observation, it is proposed that all the STH bands observable in fibers fall into two classes: those inherent in silica and those strain-assisted, which can adjoin each other in the fiber silica network. The inherent STH include the well-known low-temperature infrared absorption and the bands at 2.6 and 2.16 eV; the strain assisted STH, the 1.88- and 1.63-eV bands. The 1.88-eV band is argued to be due to STH1, the 1.63-eV one, due to STH2. Anomalously high RIA at T = 0 and +60 °C is revealed and explained for the first time. The former effect is found to be caused by extreme compression of silica at T ˜ 0 °C enhancing the strain-assisted STH bands. The anomaly at T = +60

  12. ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection.

    PubMed

    Niwa, O; Barcellos-Hoff, M H; Globus, R K; Harrison, J D; Hendry, J H; Jacob, P; Martin, M T; Seed, T M; Shay, J W; Story, M D; Suzuki, K; Yamashita, S

    2015-12-01

    This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells

  13. FTIR spectroscopic characterization of Cu(II) coordination compounds with exopolysaccharide pullulan and its derivatives

    NASA Astrophysics Data System (ADS)

    Mitić, Ž.; Nikolić, G. S.; Cakić, M.; Premović, P.; Ilić, Lj.

    2009-04-01

    Pullulan is a water-soluble, extracellular neutral polysaccharide with a linear flexible chain of α-(1 → 6)-linked maltotriose units, the structure of which is intermediate between pullulan and amylose structures because of the co-existence of both α-(1 → 6) and α-(1 → 4)-glycosidic linkages in single compounds. In alkali solutions Cu(II) ion forms complexes with reduced low-molar pullulan (RLMP). The metal content and the solution composition depends on pH. The complexing process begins in a weak alkali solution (pH > 7), and involves OH groups in C(2) and C(3) or C(6) pullulan monomer units (α- D-glucopyranose). Complexes of Cu(II) ion with reduced low-molar pullulan were synthesized in the water solutions, at the boiling temperature and at different pH values (7.512). Fourier-Transform Infrared (FTIR) spectroscopic data of synthesized complexes are rare in literature. FTIR spectroscopic characterization (FTIR, LNT-FTIR, ATR-FTIR, and FTIR microspectroscopy) of Cu(II) ion complexes with RLMP ( M w 6000 g mol -1) was carried out in this work. The similarities of the γ(C sbnd H) range in a part of FTIR spectra indicate that there is no difference in the conformation of the C 1 glucopyranose (Glc) unit in the RLMP and synthesized Cu(II) complexes. The complexing Cu(II) ion with RLMP in the dependence from the pH form different types of complex (pH 7-8: Cu(II)(Glc) 2(H 2O) 2, pH 8-10: Cu(II)(Glc) 2(H 2O)(OH), pH 10-12: Cu(II)(Glc) 2(OH) 2).

  14. Radiation dose response estimation with emphasis on low dose range using restricted cubic splines: application to all solid cancer mortality data, 1950-2003, in atomic bomb survivors.

    PubMed

    Nakashima, Eiji

    2015-07-01

    Using the all solid cancer mortality data set of the Life Span Study (LSS) cohort from 1950 to 2003 (LSS Report 14) data among atomic bomb survivors, excess relative risk (ERR) statistical analyses were performed using the second degree polynomial and the threshold and restricted cubic spline (RCS) dose response models. For the RCS models with 3 to 7 knots of equally spaced percentiles with margins in the dose range greater than 50 mGy, the dose response was assumed to be linear at less than 70 to 90 mGy. Due to the skewed dose distribution of atomic bomb survivors, the current knot system for the RCS analysis results in a detailed depiction of the dose response as less than approximately 0.5 Gy. The 6 knot RCS models for the all-solid cancer mortality dose response of the whole dose or less than 2 Gy were selected with the AIC model selection criterion and fit significantly better (p < 0.05) than the linear (L) model. The usual RCS includes the L-global model but not the quadratic (Q) nor linear-quadratic (LQ) global models. The authors extended the RCS to include L or LQ global models by putting L or LQ constraints on the cubic spline in the lower and upper tails, and the best RCS model selected with AIC criterion was the usual RCS with L-constraints in both the lower and upper tails. The selected RCS had a linear dose-response model in the lower dose range (i.e., < 0.2-0.3 Gy) and was compatible with the linear no-threshold (LNT) model in this dose range. The proposed method is also useful in describing the dose response of a specific cancer or non-cancer disease incidence/mortality.

  15. Experimental Realization of Nearly Steady-State Toroidal Electron Plasmas

    NASA Astrophysics Data System (ADS)

    Stoneking, M. R.

    2008-11-01

    Non-neutral plasmas are routinely confined in the uniform magnetic field of a Penning-Malmberg trap for arbitrarily long times and approach thermal equilibrium. Theory predicts that dynamically stable and therefore long-lived equilibria exist for non-neutral plasmas confined in the curved, non-uniform field of a toroidal trap, but that ultimately thermal equilibrium states do not exist. On long timescales, the poloidal ExB rotation through the non-uniform toroidal magnetic field leads to magnetic pumping transport. A new experiment has, for the first time, demonstrated the existence of a stable, long-lived (i.e. nearly steady-state) toroidal equilibrium for pure electron plasmas and is poised to observe the magnetic pumping transport mechanism. Electron plasmas with densities of order 10^6 cm-3 are trapped in the Lawrence Non-neutral Torus II for several seconds. LNT II is a high aspect ratio (Ro/a 10), partially toroidal trap (a 270^o arc with Bo=670 G). The m=1 diocotron mode is launched and detected using isolated segments of a fully-sectored conducting boundary and its frequency is used to determine the total trapped charge as a function of time. The observed confinement time ( 3 s) approaches the theoretical limit ( 6 s) set by the magnetic pumping transport mechanism of Crooks and O'Neil. We also present equilibrium modeling and numerical simulation of the toroidal m=1 mode constrained by experimental data. Future work includes the identification of the dominant transport mechanisms via confinement scaling experiments and measurement of the m=2 mode frequency, and development of a strategy for making a transition to fully toroidal confinement. J.P. Marler and M.R. Stoneking, Phys. Rev. Lett. 100, 155001 (2008). S.M. Crooks and T.M. O'Neil, Phys Plamas 3, 2533 (1996).

  16. Biogenesis and Membrane Targeting of Lipoproteins.

    PubMed

    Narita, Shin-Ichiro; Tokuda, Hajime

    2010-09-01

    Bacterial lipoproteins represent a unique class of membrane proteins, which are anchored to membranes through triacyl chains attached to the amino-terminal cysteine. They are involved in various functions localized in cell envelope. Escherichia coli possesses more than 90 species of lipoproteins, most of which are localized in the outer membrane, with others being in the inner membrane. All lipoproteins are synthesized in the cytoplasm with an N-terminal signal peptide, translocated across the inner membrane by the Sec translocon to the periplasmic surface of the inner membrane, and converted to mature lipoproteins through sequential reactions catalyzed by three lipoprotein-processing enzymes: Lgt, LspA, and Lnt. The sorting of lipoproteins to the outer membrane requires a system comprising five Lol proteins. An ATP-binding cassette transporter, LolCDE, initiates the sorting by mediating the detachment of lipoproteins from the inner membrane. Formation of the LolA-lipoprotein complex is coupled to this LolCDE-dependent release reaction. LolA accommodates the amino-terminal acyl chain of lipoproteins in its hydrophobic cavity, thereby generating a hydrophilic complex that can traverse the periplasmic space by diffusion. Lipoproteins are then transferred to LolB on the outer membrane and anchored to the inner leaflet of the outer membrane by the action of LolB. In contrast, since LolCDE does not recognize lipoproteins possessing Asp at position +2, these lipoproteins remain anchored to the inner membrane. Genes for Lol proteins are widely conserved among gram-negative bacteria, and Lol-mediated outer membrane targeting of lipoproteins is considered to be the general lipoprotein localization mechanism.

  17. Backbone structures in human milk oligosaccharides: trans-glycosylation by metagenomic β-N-acetylhexosaminidases.

    PubMed

    Nyffenegger, Christian; Nordvang, Rune Thorbjørn; Zeuner, Birgitte; Łężyk, Mateusz; Difilippo, Elisabetta; Logtenberg, Madelon J; Schols, Henk A; Meyer, Anne S; Mikkelsen, Jørn Dalgaard

    2015-10-01

    This paper describes the discovery and characterization of two novel β-N-acetylhexosaminidases HEX1 and HEX2, capable of catalyzing the synthesis of human milk oligosaccharides (HMO) backbone structures with fair yields using chitin oligomers as β-N-acetylglucosamine (GlcNAc) donor. The enzyme-encoding genes were identified by functional screening of a soil-derived metagenomic library. The β-N-acetylhexosaminidases were expressed in Escherichia coli with an N-terminal His6-tag and were purified by nickel affinity chromatography. The sequence similarities of the enzymes with their respective closest homologues are 59 % for HEX1 and 51 % for HEX2 on the protein level. Both β-N-acetylhexosaminidases are classified into glycosyl hydrolase family 20 (GH 20) are able to hydrolyze para-nitrophenyl-β-N-acetylglucosamine (pNP-GlcNAc) as well as para-nitrophenyl-β-N-acetylgalactosamine (pNP-GalNAc) and exhibit pH optima of 8 and 6 for HEX1 and HEX2, respectively. The enzymes are able to hydrolyze N-acetylchitooligosaccharides with a degree of polymerization of two, three, and four. The major findings were, that HEX1 and HEX2 catalyze trans-glycosylation reactions with lactose as acceptor, giving rise to the human milk oligosaccharide precursor lacto-N-triose II (LNT2) with yields of 2 and 8 % based on the donor substrate. In total, trans-glycosylation reactions were tested with the disaccharide acceptors β-lactose, sucrose, and maltose, as well as with the monosaccharides galactose and glucose resulting in the successful attachment of GlcNAc to the acceptor in all cases.

  18. Detection of milk oligosaccharides in plasma of infants

    PubMed Central

    Ruhaak, L. Renee; Stroble, Carol; Underwood, Mark A.; Lebrilla, Carlito B.

    2014-01-01

    Human Milk Oligosaccharides (HMO) are one of the major components of human milk. HMO are non-digestible by the human gut, where they are known to play important functions as prebiotics and decoys for binding pathogens. Moreover, it has been proposed that HMO may provide sialic acids to the infant that are important in brain development, however this would require absorption of HMO into the bloodstream. HMO have consistently been found in the urine of humans and other mammals, suggesting systemic absorption. Here we present a procedure for the profiling of milk oligosaccharides (MO) in plasma samples obtained from 13 term infants hospitalized for surgery for congenital heart disease. The method comprises protein denaturation, oligosaccharide reduction and porous graphitized carbon solid phase extraction for purification followed by analysis using nHPLC-PGC-chip-TOF-MS. Approximately 15 free MO were typically observed in the plasma of human infants, including LNT, LDFP, LNFT, 3’SL, 6’SL, 3’SLN and 6’SLN, of which the presence was confirmed using fragmentation studies. A novel third isomer of SLN, not found in human or bovine milk was also consistently detected. Differences in the free MO profiles were observed between infants that were totally formula-fed and infants that received at least some part breast milk. Our results indicate that free MO similar in structure to those found in human milk and urine are present in the blood of infants. The method and results presented here will facilitate further research toward the possible roles of free MO in the development of the infant. PMID:25059723

  19. Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. V. Spectra of protiated and partially deuterated magnesium ammonium arsenate hexahydrate (arsenstruvite)

    NASA Astrophysics Data System (ADS)

    Stefov, V.; Šoptrajanov, B.; Najdoski, M.; Engelen, B.; Lutz, H. D.

    2008-01-01

    The Fourier transform infrared and Raman spectra of magnesium ammonium arsenate hexahydrate, MgNH 4AsO 4 · 6H 2O (arsenstruvite) and of its deuterated analogues were recorded at room temperature (RT) and the boiling temperature of liquid nitrogen (LNT). Not surprisingly, the spectra show pronounced similarities with the corresponding spectra of the previously studied magnesium potassium phosphate hexahydrate and magnesium ammonium phosphate hexahydrate with the expected differences in the regions of the arsenate vibrations. The main contribution to the intensity of the complex feature in the X-H stretching region (X being O or N) comes from the stretching vibrations of the water molecules, whereas the vibrations of the ammonium ions are less important as long as the intensity is concerned. This is due not only to the fact that four crystallographically different water molecules of crystallization exist in the structure (as compared with a single type of ammonium ions) but also because the hydrogen bonds formed by the water molecules are much stronger than those in which the ammonium ions take part. Difference infrared spectra were obtained by subtracting the properly normalized spectrum of the protiated compound from the spectrum of a deuterated analogue with low deuterium content. As evidenced by the spectra of the partially deuterated analogues and by the difference spectra, vibrational interactions are present in the crystal. Probably the most dramatic is the result of such an interaction producing a deep Evans-type hole in the stretching region of the difference spectrum but additional cases of vibrational mixing are found in the low-frequency region.

  20. Fecal Microbiota Composition of Breast-fed Infants is Correlated with Human Milk Oligosaccharides Consumed

    PubMed Central

    Wang, Mei; Li, Min; Wu, Shuai; Lebrilla, Carlito B.; Chapkin, Robert S.; Ivanov, Ivan; Donovan, Sharon M.

    2015-01-01

    Objectives This study tested the hypothesis that the fecal bacterial genera of breast-fed (BF) and formula-fed (FF) infants differ and that human milk oligosaccharides (HMO) modulate the microbiota of BF infants. Methods Fecal samples were obtained from BF (n = 16) or FF (n = 6) infants at 3-month postpartum. Human milk were collected on the same day when feces were collected. The microbiota was assessed by pyrosequencing of bacterial 16S rRNA genes. HMO were measured by HPLC-Chip time-of-flight mass spectrometry. Results The overall microbiota of BF differed from that of FF (P = 0.005). Compared to FF, BF had higher relative abundances of Bacteroides, lower proportions of Clostridium XVIII, Lachnospiracea incertae sedis, Streptococcus, Enterococcus and Veillonella (P < 0.05). Bifidobacterium predominated in both BF and FF infants, with no difference in abundance between the two groups. The most abundant HMO were lacto-N-tetraose + lacto-N-neotetraose (LNT + LNnT, 22.6%), followed by 2′-fucosyllactose (2′FL, 14.5%) and lacto-N-fucopentaose I (LNFP I, 9.5%). Partial least squares regression of HMO and microbiota showed several infant fecal bacterial genera could be predicted by their mothers’ HMO profiles and the important HMO for the prediction of bacterial genera were identified by variable importance in the projection scores. Conclusions These results strengthen the established relationship between HMO and the infant microbiota, identify statistical means whereby infant bacterial genera can be predicted by milk HMO. Future studies are needed to validate these findings and determine if supplementation of formula with defined HMO could selectively modify the gut microbiota. PMID:25651488

  1. Quark gluon bags as reggeons

    SciTech Connect

    Bugaev, K. A.; Petrov, V. K.; Zinovjev, G. M.

    2009-05-15

    The influence of the medium-dependent finite width of quark gluon plasma (QGP) bags on their equation of state is analyzed within an exactly solvable model. It is argued that the large width of the QGP bags not only explains the observed deficit in the number of hadronic resonances but also clarifies the reason why the heavy QGP bags cannot be directly observed as metastable states in a hadronic phase. The model allows us to estimate the minimal value of the width of QGP bags being heavier than 2 GeV from a variety of the lattice QCD data and get that the minimal resonance width at zero temperature is about 600 MeV, whereas the minimal resonance width at the Hagedorn temperature is about 2000 MeV. As shown, these estimates are almost insensitive to the number of the elementary degrees of freedom. The recent lattice QCD data are analyzed and it is found that in addition to the {sigma}T{sup 4} term the lattice QCD pressure contains T-linear and T{sup 4}lnT terms in the range of temperatures between 240 and 420 MeV. The presence of the last term in the pressure bears almost no effect on the width estimates. Our analysis shows that at high temperatures the average mass and width of the QGP bags behave in accordance with the upper bound of the Regge trajectory asymptotics (the linear asymptotics), whereas at low temperatures they obey the lower bound of the Regge trajectory asymptotics (the square root one). Since the model explicitly contains the Hagedorn mass spectrum, it allows us to remove an existing contradiction between the finite number of hadronic Regge families and the Hagedorn idea of the exponentially growing mass spectrum of hadronic bags.

  2. Photoconductivity, low-temperature conductivity, and magnetoresistance studies on the layered semiconductor GaTe

    SciTech Connect

    Bose, D. N.; Pal, Sarbari

    2001-06-15

    Single crystals of p-GaTe were grown by the Bridgman technique and characterized through x-ray diffraction, energy-dispersive x-ray analysis, x-ray photoemission spectroscopy, and transmission electron microscopy studies. The photoconductivity spectral response for in-plane conduction showed a peak at 747 nm (1.66 eV). Photoconductivity gain was determined in two orthogonal directions from which the majority carrier (hole) lifetimes were found to be 3.43{times}10{sup {minus}7} and 2.03{times}10{sup {minus}6}s, respectively, parallel and perpendicular to the layer planes. Studies of the temperature dependence of conductivity in the directions along and perpendicular to the layer planes were carried out between 10 and 80 K. Along the layer planes the conductance G{sub {parallel}} varied as lnT between 12 and 20 K, characteristic of weak localization, while between 20 and 50 K the conductivity {sigma}{sub {parallel}} varied as T{sup 1/2}. In the perpendicular direction the conductance G{sub {perpendicular}} varied as exp(T/T{sub 0}){sup 1/3} between 9 and 20 K and the conductivity {sigma}{sub {perpendicular}} varied as exp(T/T{sub 0}){sup 1/4} between 20 and 50 K, characteristic of hopping conduction in two and three dimensions, respectively. Negative transverse magnetoresistance was observed at 10 K for conduction in both directions for magnetic fields H{lt}0.4T, the increase in conductance being found to be proportional to H{sup 2}. Band conduction with positive magnetoresistance was observed for both current directions at T{gt}70K. The I-V characteristics at 10 K showed quantized behavior due to electron tunneling across potential barriers caused by stacking faults between layer planes.

  3. Ferromagnetic behavior of the Kondo lattice compound Np2PtGa3

    NASA Astrophysics Data System (ADS)

    Tran, V. H.; Griveau, J.-C.; Eloirdi, R.; Colineau, E.

    2014-02-01

    Here we report on a study of the ternary Np2PtGa3 compound. The x-ray-powder diffraction analysis reveals that the compound crystallizes in the orthorhombic CeCu2-type crystal structure (space group Imma) with lattice parameters a =0.4409(2) nm, b =0.7077(3) nm, and c =0.7683(3) nm at room temperature. The measurements of dc magnetization, specific heat, and electron transport properties in the temperature range 1.7-300 K and in magnetic fields up to 9 T imply that this intermetallic compound belongs to a class of ferromagnetic Kondo systems. The Curie temperature of TC˜ 26 K is determined from the magnetization and specific-heat data. An enhanced coefficient of the electronic specific heat γ = 180 mJ/(mol at. Np K2) and a -lnT dependence of the electrical resistivity indicate the presence of a Kondo effect, which can be described in terms of the S =1 underscreened Kondo-lattice model. The estimated Kondo temperature TK˜24 K, Hall mobility of ˜16.8 cm2/V s, and effective mass of ˜83me are consistent with an assumption that the heavy-fermion state develops in Np2PtGa3 at low temperatures. We compare the observed properties of Np2PtGa3 to that found in Np2PdGa3 and discuss their difference in regard to change in the exchange interaction between the conduction and localized 5f electrons. We have used the Fermi wave vector kF to evaluate the Rudermann-Kittel-Kasuya-Yosida (RKKY) exchange. Based on experimental data of the (U, Np)2(Pd,Pt)Ga3 compounds we suggest that the evolution of the magnetic ground states in these actinide compounds can be explained within the RKKY formalism.

  4. A tool for the prediction of structures of complex sugars.

    PubMed

    Xia, Junchao; Margulis, Claudio

    2008-12-01

    In two recent back to back articles(Xia et al., J Chem Theory Comput 3:1620-1628 and 1629-1643, 2007a, b) we have started to address the problem of complex oligosaccharide conformation and folding. The scheme previously presented was based on exhaustive searches in configuration space in conjunction with Nuclear Overhauser Effect (NOE) calculations and the use of a complex rotameric library that takes branching into account. NOEs are extremely useful for structural determination but only provide information about short range interactions and ordering. Instead, the measurement of residual dipolar couplings (RDC), yields information about molecular ordering or folding that is long range in nature. In this article we show the results obtained by incorporation RDC calculations into our prediction scheme. Using this new approach we are able to accurately predict the structure of six human milk sugars: LNF-1, LND-1, LNF-2, LNF-3, LNnT and LNT. Our exhaustive search in dihedral configuration space combined with RDC and NOE calculations allows for highly accurate structural predictions that, because of the non-ergodic nature of these molecules on a time scale compatible with molecular dynamics simulations, are extremely hard to obtain otherwise (Almond et al., Biochemistry 43:5853-5863, 2004). Molecular dynamics simulations in explicit solvent using as initial configurations the structures predicted by our algorithm show that the histo-blood group epitopes in these sugars are relatively rigid and that the whole family of oligosaccharides derives its conformational variability almost exclusively from their common linkage (beta-D: -GlcNAc-(1-->3)-beta-D: -Gal) which can exist in two distinct conformational states. A population analysis based on the conformational variability of this flexible glycosidic link indicates that the relative population of the two distinct states varies for different human milk oligosaccharides.

  5. Experimental determination of Henry's law constants of difluoromethane (HFC-32) and the salting-out effects in aqueous salt solutions relevant to seawater

    NASA Astrophysics Data System (ADS)

    Kutsuna, Shuzo

    2017-06-01

    Gas-to-water equilibrium coefficients, KeqS (in M atm-1), of difluoromethane (CH2F2), a hydrofluorocarbon refrigerant (HFC-32), in aqueous salt solutions relevant to seawater were determined over a temperature (T) range from 276 to 313 K and a salinity (S) range up to 51 ‰ by means of an inert-gas stripping method. From the van't Hoff equation, the KeqS value in water, which corresponds to the Henry's law constant (KH), at 298 K was determined to be 0.065 M atm-1. The salinity dependence of KeqS (the salting-out effect), ln(KH/KeqS), did not obey the Sechenov equation but was proportional to S0. 5. Overall, the KeqS(T) value was expressed by ln(KeqS(T)) = -49.71 + (77.70 - 0.134 × S0. 5) × (100/T) + 19.14 × ln(T/100). By using this equation in a lower-tropospheric semi-hemisphere (30-90 °S) of the Advanced Global Atmospheric Gases Experiment (AGAGE) 12-box model, we estimated that 1 to 4 % of the atmospheric burden of CH2F2 resided in the ocean mixed layer and that this percentage was at least 4 % in the winter; dissolution of CH2F2 in the ocean may partially influence estimates of CH2F2 emissions from long-term observational data of atmospheric CH2F2 concentrations.

  6. Effect of age at cochlear implantation on auditory and speech development of children with auditory neuropathy spectrum disorder.

    PubMed

    Liu, Yuying; Dong, Ruijuan; Li, Yuling; Xu, Tianqiu; Li, Yongxin; Chen, Xueqing; Gong, Shusheng

    2014-12-01

    To evaluate the auditory and speech abilities in children with auditory neuropathy spectrum disorder (ANSD) after cochlear implantation (CI) and determine the role of age at implantation. Ten children participated in this retrospective case series study. All children had evidence of ANSD. All subjects had no cochlear nerve deficiency on magnetic resonance imaging and had used the cochlear implants for a period of 12-84 months. We divided our children into two groups: children who underwent implantation before 24 months of age and children who underwent implantation after 24 months of age. Their auditory and speech abilities were evaluated using the following: behavioral audiometry, the Categories of Auditory Performance (CAP), the Meaningful Auditory Integration Scale (MAIS), the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS), the Standard-Chinese version of the Monosyllabic Lexical Neighborhood Test (LNT), the Multisyllabic Lexical Neighborhood Test (MLNT), the Speech Intelligibility Rating (SIR) and the Meaningful Use of Speech Scale (MUSS). All children showed progress in their auditory and language abilities. The 4-frequency average hearing level (HL) (500Hz, 1000Hz, 2000Hz and 4000Hz) of aided hearing thresholds ranged from 17.5 to 57.5dB HL. All children developed time-related auditory perception and speech skills. Scores of children with ANSD who received cochlear implants before 24 months tended to be better than those of children who received cochlear implants after 24 months. Seven children completed the Mandarin Lexical Neighborhood Test. Approximately half of the children showed improved open-set speech recognition. Cochlear implantation is helpful for children with ANSD and may be a good optional treatment for many ANSD children. In addition, children with ANSD fitted with cochlear implants before 24 months tended to acquire auditory and speech skills better than children fitted with cochlear implants after 24 months. Copyright © 2014

  7. Effects of Potassium loading and thermal aging on K/Pt/Al2O3 high-temperature lean NOx trap catalysts

    SciTech Connect

    Luo, Jinyong; Gao, Feng; Kim, Do Heui; Peden, Charles HF

    2014-03-31

    The effects of K loading and thermal aging on the structural properties and high temperature performance of Pt/K/Al2O3 lean NOx trap (LNT) catalysts were investigated using in situ X-ray diffraction (XRD), temperature-programmed decomposition/desorption of NOx (NOx-TPD), transmission electron microscopy (TEM), NO oxidation and NOx storage tests. In situ XRD results demonstrate that KNO3 becomes extremely mobile on the Al2O3 surface, and experiences complex transformations between orthorhombic and rhombohedral structures, accompanied by sintering, melting and thermal decomposition upon heating. NOx storage results show an optimum K loading around 10% for the best performance at high temperatures. At lower K loadings where the majority of KNO3 stays as a surface layer, the strong interaction between KNO3 and Al2O3 promotes KNO3 decomposition and deteriorates high-temperature performance. At K loadings higher than 10%, the performance drop is not caused by NOx diffusion limitations as for the case of barium-based LNTs, but rather from the blocking of Pt sites by K species, which adversely affects NO oxidation. Thermal aging at 800 ºC severely deactivates the Pt/K/Al2O3 catalysts due to Pt sintering. However, in the presence of potassium, some Pt remains in a dispersed and oxidized form. These Pt species interact strongly with K and, therefore, do not sinter. After a reduction treatment, these Pt species remain finely dispersed, contributing to a partial recovery of NOx storage performance.

  8. Secretion of Bacterial Lipoproteins: Through the Cytoplasmic Membrane, the Periplasm and Beyond

    PubMed Central

    Zückert, Wolfram R.

    2014-01-01

    Bacterial lipoproteins are peripherally anchored membrane proteins that play a variety of roles in bacterial physiology and virulence in monoderm (single membrane-enveloped, e.g., grampositive) and diderm (double membrane-enveloped, e.g., gram-negative) bacteria. After export of prolipoproteins through the cytoplasmic membrane, which occurs predominantly but not exclusively via the general secretory or Sec pathway, the proteins are lipid-modified at the cytoplasmic membrane in a multistep process that involves sequential modification of a cysteine residue and cleavage of the signal peptide by the signal II peptidase Lsp. In both monoderms and diderms, signal peptide processing is preceded by acylation with a diacylglycerol through preprolipoprotein diacylglycerol transferase (Lgt). In diderms but also some monoderms, lipoproteins are further modified with a third acyl chain through lipoprotein N-acyl transferase (Lnt). Fully modified lipoproteins that are destined to be anchored in the inner leaflet of the outer membrane (OM) are selected, transported and inserted by the Lol (lipoprotein outer membrane localization) pathway machinery, which consists of the inner-membrane (IM) ABC transporterlike LolCDE complex, the periplasmic LolA chaperone and the OM LolB lipoprotein receptor. Retention of lipoproteins in the cytoplasmic membrane results from Lol avoidance signals that were originally described as the “+2 rule”. Surface localization of lipoproteins in diderms is rare in most bacteria, with the exception of several spirochetal species. Type 2 (T2SS) and type 5 (T5SS) secretion systems are involved in secretion of specific surface lipoproteins of γ-proteobacteria. In the model spirochete Borrelia burgdorferi, surface lipoprotein secretion does not follow established sorting rules, but remains dependent on N-terminal peptide sequences. Secretion through the outer membrane requires maintenance of lipoproteins in a translocation-competent unfolded conformation

  9. Combination of photocatalysis and HC/SCR for improved activity and durability of DeNOx catalysts.

    PubMed

    Heo, Iljeong; Kim, Mun Kyu; Sung, Samkyung; Nam, In-Sik; Cho, Byong K; Olson, Keith L; Li, Wei

    2013-04-16

    A photocatalytic HC/SCR system has been developed and its high deNOx performance (54.0-98.6% NOx conversion) at low temperatures (150-250 °C) demonstrated by using a representative diesel fuel hydrocarbon (dodecane) as the reductant over a hybrid SCR system of a photocatalytic reactor (PCR) and a dual-bed HC/SCR reactor. The PCR generates highly active oxidants such as O3 and NO2 from O2 and NO in the feed stream, followed by the subsequent formation of highly efficient reductants such as oxygenated hydrocarbon (OHC), NH3, and organo-nitrogen compounds. These reductants are the key components for enhancing the low temperature deNOx performance of the dual-bed HC/SCR system containing Ag/Al2O3 and CuCoY in the front and rear bed of the reactor, respectively. The OHCs are particularly effective for both NOx reduction and NH3 formation over the Ag/Al2O3 catalyst, while NH3 and organo-nitrogen compounds are effective for NOx reduction over the CuCoY catalyst. The hybrid HC/SCR system assisted by photocatalysis has shown an overall deNOx performance comparable to that of the NH3/SCR, demonstrating its potential as a promising alternative to the current urea/SCR and LNT technologies. Superior durability of HC/SCR catalysts against coking by HCs has also been demonstrated by a PCR-assisted regeneration scheme for deactivating catalysts.

  10. Detailed investigation of thermal and electron transport properties in strongly correlated compound Ce6Pd12In5 and its nonmagnetic analog La6Pd12In5

    NASA Astrophysics Data System (ADS)

    Falkowski, M.; Krychowski, D.; Strydom, A. M.

    2016-11-01

    An in-depth study of thermal and electron transport properties including thermal conductivity κ(T), thermoelectric power S(T), and electrical resistivity ρ(T) of the heavy fermion Kondo lattice Ce6Pd12In5 and its nonmagnetic reference compound La6Pd12In5 is presented. The absolute κ(T) value of Ce6Pd12In5 is smaller that than of La6Pd12In5, which indicates that conduction electron-4f electron scattering has a large impact on the reduction of thermal conductivity. The isolated 4f electron contributions to the electrical resistivity ρ 4 f (T), electronic thermal resistivity displayed in the form W e l , 4 f (T) .T, and thermoelectric power S 4 f (T) reveal a low- and high-temperature -lnT behaviour characteristic of Kondo systems with strong crystal-electric field (CEF) interactions. The analysis of phonon scattering processes of lattice thermal conductivity κph(T) in (Ce, La)6Pd12In5 was performed over the whole accessible temperature range according to the Callaway model. In the scope of a theoretical approach based on the perturbation type calculation, we were able to describe our experimental data of ρ 4 f (T) and W e l , 4 f (T) .T by using the model incorporating simultaneously the Kondo effect in the presence of the CEF splitting, as it is foreseen in the framework of the Cornut-Coqblin and Bhattacharjee-Coqblin theory. Considering the fact that there are not many cases of similar studies at all, we also show the numerical calculations of temperature-dependent behaviour of spin-disorder resistivity ρs(T), magnetic resistivity ρ 4 f (T), and occupation number ⟨ N i ⟩ due to the various types of degeneracy of the ground state multiplet of Ce 3 + (J = 5/2).

  11. Threshold effect under nonlinear limitation of the intensity of high-power light

    SciTech Connect

    Tereshchenko, S A; Podgaetskii, V M; Gerasimenko, A Yu; Savel'ev, M S

    2015-04-30

    A model is proposed to describe the properties of limiters of high-power laser radiation, which takes into account the threshold character of nonlinear interaction of radiation with the working medium of the limiter. The generally accepted non-threshold model is a particular case of the threshold model if the threshold radiation intensity is zero. Experimental z-scan data are used to determine the nonlinear optical characteristics of media with carbon nanotubes, polymethine and pyran dyes, zinc selenide, porphyrin-graphene and fullerene-graphene. A threshold effect of nonlinear interaction between laser radiation and some of investigated working media of limiters is revealed. It is shown that the threshold model more adequately describes experimental z-scan data. (nonlinear optical phenomena)

  12. Radiation cancer analysis and low dose risk estimation: new developments and perspectives - conference to be held Feb 2002. Final technical report for period November 1, 2001--October 31, 2002

    SciTech Connect

    Brugmans, M.J.P.; Leenhouts, H.P.

    2002-10-01

    The Proceedings of the 20th LH Gray Conference on Radiation Cancer Analysis and Low Dose Risk Estimation: New Developments and Perspectives (17-21 February 2002, Ede, the Netherlands) comprises 32 peer-reviewed papers on invited and proffered contributions to the conference with a preface by the guest editors. The on-going discussion of low dose radiation risk; the issue of the linear, non-threshold extrapolation; and the anticipated new recommendations, e.g. from BEIR and ICRP, provided the back-drop for the conference. The meeting dealt with topics such as basic mechanisms and bystander effects, cancer modeling, cancer genetics, radon exposure and lung cancer risk, cancer after medical exposure, cancer risk estimation, dose-effect relationships, and application to radiation protection.

  13. Synthetic holograms based on photochromic diarylethenes

    NASA Astrophysics Data System (ADS)

    Pariani, Giorgio; Alata, Romain; Oggioni, Luca; Colella, Letizia; Bertarelli, Chiara; Bianco, Andrea; Lanzoni, Patric; Zamkotsian, Frederic

    2017-05-01

    Diarylethenes are P-type photochromic systems showing reversible light-induced modulation of optical properties, e.g., transmittance and refractive index, in the visible and near infrared regions. Transmittance can be progressively tuned according to the illumination dose, and the pattern written and erased several times with light. We demonstrated binary Computer Generated Holograms based on of photochromic materials, to be used as adaptable reference surfaces in interferometric tests. We encoded by Direct Laser Writing binary amplitude Fresnel Zone Plates into photochromic substrates and successfully tested them into an interferometric setup. More recently, we exploited the non-threshold behavior of photochromic materials to encode grayscale CGHs, which give a better wavefront reconstruction than binary holograms. We propose to use a device based on a Digital Micro-mirror Device as a real-time reconfigurable mask. We recorded for the first time amplitude grayscale CGHs and reconstructed them with high fidelity in shape, intensity and size.

  14. [About Dose-Effect Relationship in the Environment Radiation Protection].

    PubMed

    Udalova, A A

    2015-01-01

    One of the most important stages in the development of a methodology for the environment radiation protection is the assessment and justification of critical radiation exposure levels for ecosystem components. In this study application of the approach for critical dose level estimation is demonstrated on the example of the data about ionizing radiation effect on reproduction and survival of agricultural plants after acute and chronic exposures. Influence of the type of dose-effect relationship on the estimated values of the critical doses and dose rates is studied using three models (linear, logarithmic and logistic). The findings obtained do not provide any robust recommendations in favor of one of the three tested functions. The models of dose-effect relationship (threshold or non-threshold) and types of radiation-induced effects (stochastic and deterministic) are discussed from the viewpoint of developing a system for radiation protection of human and non-human biota.

  15. Inorganic arsenic in rice-based products for infants and young children.

    PubMed

    Signes-Pastor, Antonio J; Carey, Manus; Meharg, Andrew A

    2016-01-15

    Inorganic arsenic (Asi) is a chronic, non-threshold carcinogen. Rice and rice-based products can be the major source of Asi for many subpopulations. Baby rice, rice cereals and rice crackers are widely used to feed infants and young children. The Asi concentration in rice-based products may pose a health risk for infants and young children. Asi concentration was determined in rice-based products produced in the European Union and risk assessment associated with the consumption of these products by infants and young children, and compared to an identical US FDA survey. There are currently no European Union or United States of America regulations applicable to Asi in food. However, this study suggests that the samples evaluated may introduce significant concentration of Asi into infants' and young children's diets. Thus, there is an urgent need for regulatory limits on Asi in food, especially for baby rice-based products.

  16. Legitimating a nuclear critic: John Gofman, radiation safety, and cancer risks.

    PubMed

    Semendeferi, Ioanna

    2008-01-01

    Whether low-level ionizing radiation has an effect on humans has been a polarizing issue for the last fifty years. The epicenter of this controversy has been the validity of the linear non-threshold dose-response model, according to which any amount of radiation, however small, causes damage to human genes and health. In the late 1960s and early 1970s, the nuclear scientist and medical researcher John Gofman (1918-2007) played a pivotal role in the debate. Historical accounts have treated Gofman as a radical antinuclear scientist whose unscientific arguments put enormous political pressure on the nuclear power industry and regulatory agencies. Gofman's bitter struggle with the Atomic Energy Commission, which funded his research at Lawrence Livermore National Laboratory, partly accounts for this view. However, my analysis of Gofman's involvement in the low-level radiation debate shows how he also helped shift the focus in radiation safety from the risks of genetic damage or leukemia to somatic or cancer risks. His arguments led to the introduction of the linear non-threshold radiation model as a means of numerically estimating cancer risks. This was a watershed event in radiation-safety science and politics. Gofman's case sheds light on the process by which a scientist could secure legitimation even when his technical arguments threatened the government's interests. I conclude that it also points to an open issue in the history of antinuclear scientists, or of other politically active scientists or technology critics: treating them as critics should not preclude historians from treating them as scientists.

  17. Cardiac Arrests Associated with Low Plasma and Tissue Levels of Local Anaesthetics.

    PubMed

    Alexandre, Joachim; Humbert, Xavier; Sassier, Marion; Cesbron, Alexandre; Le Naourès, Cécile; Pottier, Véronique; Puddu, Paolo-Emilio; Milliez, Paul; Coquerel, Antoine; Fedrizzi, Sophie

    2015-10-16

    Although local anaesthetics cardiac toxicity is usually the result of high local anaesthetics dose, based on a pharmacovigilance case report and an analyze of the French Pharmacovigilance Database between January 1(st), 2007 and December 31(st), 2013, we hypothesized that in some patients, the combination of medical or drug risk factors may be responsible for cardiac anaesthetics toxicity at lower plasma concentrations. © 2015 Société Française de Pharmacologie et de Thérapeutique.

  18. Data for the Chilton-Huddleston photon-albedo approximations

    SciTech Connect

    Brockhoff, R.C.; Shultis, J.K.; Faw, R.E.

    1997-05-01

    Empirical parameters for two different gamma-ray albedo formulas, originally proposed by Chilton and Huddleston, are presented for water, concrete, iron, and lead for 12 photon energies ranging from 0.1 to 10 MeV and for reflected doses based on the ambient dose equivalent, the effective dose equivalent, and the exposure. The parameters were obtained by fitting the albedo formulas to MCNP-calculated albedo values over the complete ranges of incident and reflected directions.

  19. Status report on the development of draft MCLGs for disinfectants and by-products

    SciTech Connect

    Not Available

    1992-10-01

    The Maximum Contaminant level goals (MCLG) are set at concentration levels at which no known or anticipated adverse health effects occur, allowing for an adequate margin of safety. Establishment of an MCLG for each specific contaminant depends on the evidence of carcinogenicity from drinking water exposure or the Agency's oral reference dose based on noncarcinogenic data. The report discusses the status of the development of draft MCLG5 for disinfectants and disinfection by-products.

  20. 21 CFR 520.538 - Deracoxib.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... chewable tablet contains 25, 50, 75, or 100 milligrams (mg) deracoxib. (b) Sponsor. See No. 058198 in § 510... a single daily dose based on body weight. (i) 1 to 2 mg/kilograms (kg) (0.45 to 0.91 mg/pound (lb), for use as in paragraph (d)(2)(i) of this section. (ii) 3 to 4 mg/kg (1.4 to 1.8 mg/lb) for up to...

  1. 21 CFR 520.538 - Deracoxib.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... chewable tablet contains 25, 50, 75, or 100 milligrams (mg) deracoxib. (b) Sponsor. See No. 058198 in § 510... a single daily dose based on body weight. (i) 1 to 2 mg/kilograms (kg) (0.45 to 0.91 mg/pound (lb), for use as in paragraph (d)(2)(i) of this section. (ii) 3 to 4 mg/kg (1.4 to 1.8 mg/lb) for up to...

  2. Radiochromic film based transit dosimetry for verification of dose delivery with intensity modulated radiotherapy

    SciTech Connect

    Chung, Kwangzoo; Lee, Kiho; Shin, Dongho; Kyung Lim, Young; Byeong Lee, Se; Yoon, Myonggeun; Son, Jaeman; Yong Park, Sung

    2013-02-15

    Purpose: To evaluate the transit dose based patient specific quality assurance (QA) of intensity modulated radiation therapy (IMRT) for verification of the accuracy of dose delivered to the patient. Methods: Five IMRT plans were selected and utilized to irradiate a homogeneous plastic water phantom and an inhomogeneous anthropomorphic phantom. The transit dose distribution was measured with radiochromic film and was compared with the computed dose map on the same plane using a gamma index with a 3% dose and a 3 mm distance-to-dose agreement tolerance limit. Results: While the average gamma index for comparisons of dose distributions was less than one for 98.9% of all pixels from the transit dose with the homogeneous phantom, the passing rate was reduced to 95.0% for the transit dose with the inhomogeneous phantom. Transit doses due to a 5 mm setup error may cause up to a 50% failure rate of the gamma index. Conclusions: Transit dose based IMRT QA may be superior to the traditional QA method since the former can show whether the inhomogeneity correction algorithm from TPS is accurate. In addition, transit dose based IMRT QA can be used to verify the accuracy of the dose delivered to the patient during treatment by revealing significant increases in the failure rate of the gamma index resulting from errors in patient positioning during treatment.

  3. Kinetic and spectroscopic study of catalysts for water-gas shift and nitrogen oxide removal

    NASA Astrophysics Data System (ADS)

    Kispersky, Vincent Frederick

    Nitrogen oxides (NOx) are formed in high temperature combustion processes such as in power generation and motor vehicles. Increasingly stringent regulation of these harmful emissions continues to drive interest in developing, understanding and studying new catalytic formulations for exhaust aftertreatment. For mobile sources, predominantly heavy duty diesel engines, selective catalytic reduction (SCR) with NH3 has become the principal means of NO x abatement. An alternative technology developed, but now surpassed by SCR, is NOx Storage Reduction (NSR) catalysis. Both technologies have been studied in our laboratory and are the basis for this dissertation. We studied seven different lean NOx trap (LNT) monolith formulations for NSR ranging from 0.6 to 6.2 wt.% Pt and 4 to 20 wt.% Ba loadings on γ-Al 2O3. The noble metal component of a LNT oxidizes NO to NO 2 aiding in the storage of NO2 on the alkaline earth component. Before the storage component saturates, a reductant such as H2 is introduced into the vehicular exhaust and the stored NOx is released and reduced to N2. Once the storage component is free of NOx, reductant flow is ceased and storage is begun anew. Our research focused on understanding the effects that CO2 and H2O have on the storage capacity of the LNT over short as well as extended periods of time. We found that for high Ba loadings, CO 2 had a consistently detrimental effect on the fast NOx storage capacity (NSC), defined as the amount of NOx the catalyst can store before 1% of the inlet NOx is measured in the reactor outlet. Over long NOx storage periods, CO2 continued to inhibit storage compared to the same catalyst in CO2 free conditions. On low loadings of Ba, however, the inhibition of CO2 was significantly reduced. We found that the loading dependent characteristics of the Ba phase affected the way in which CO2 adsorbed on the storage component, which greatly affected the stability of the species on lower Ba loadings. The less stable

  4. Advantages of MgAlOx over gamma-Al2O3 as a support material for potassium-based high temperature lean NOx traps

    SciTech Connect

    Luo, Jinyong; Gao, Feng; Karim, Ayman M.; Xu, Pinghong; Browning, Nigel D.; Peden, Charles HF

    2015-08-07

    MgAlOx mixed oxides were employed as supports for potassium-based lean NOx traps (LNTs) targeted for high temperature applications. Effects of support compositions, K/Pt loadings, thermal aging and catalyst regeneration on NOx storage capacity were systematically investigated. The catalysts were characterized by XRD, NOx-TPD, TEM, STEM-HAADF and in-situ XAFS. The results indicate that MgAlOx mixed oxides have significant advantages over conventional gamma-Al2O3-supports for LNT catalysts, in terms of high temperature NOx trapping capacity and thermal stability. First, as a basic support, MgAlOx stabilizes stored nitrates (in the form of KNO3) to much higher temperatures than mildly acidic gamma-Al2O3. Second, MgAlOx minimizes Pt sintering during thermal aging, which is not possible for gamma-Al2O3 supports. Notably, combined XRD, in-situ XAFS and STEM-HAADF results indicate that Pt species in the thermally aged Pt/MgAlOx samples are finely dispersed in the oxide matrix as isolated atoms. This strong metal-support interaction stabilizes Pt and minimizes the extent of sintering. However, such strong interactions result in Pt oxidation via coordination with the support so that NO oxidation activity can be adversely affected after aging which, in turn, decreases NOx trapping ability for these catalysts. Interestingly, a high-temperature reduction treatment regenerates essentially full NOx trapping performance. In fact, regenerated Pt/K/MgAlOx catalyst exhibits much better NOx trapping performance than fresh Pt/K/Al2O3 LNTs over the entire temperature range investigated here. In addition to thermal aging, Pt/K loading effects were systemically studied over the fresh samples. The results indicate that NOx trapping is kinetically limited at low temperatures, while thermodynamically limited at high temperatures. A simple conceptual model was developed to explain the Pt and K loading effects on NOx storage. An optimized K loading, which allows balancing between the

  5. Genetic Differences in Transcript Responses to Low-Dose Ionizing Radiation Identify Tissue Functions Associated with Breast Cancer Susceptibility

    PubMed Central

    Snijders, Antoine M.; Marchetti, Francesco; Bhatnagar, Sandhya; Duru, Nadire; Han, Ju; Hu, Zhi; Mao, Jian-Hua; Gray, Joe W.; Wyrobek, Andrew J.

    2012-01-01

    High dose ionizing radiation (IR) is a well-known risk factor for breast cancer but the health effects after low-dose (LD, <10 cGy) exposures remain highly uncertain. We explored a systems approach that compared LD-induced chromosome damage and transcriptional responses in strains of mice with genetic differences in their sensitivity to radiation-induced mammary cancer (BALB/c and C57BL/6) for the purpose of identifying mechanisms of mammary cancer susceptibility. Unirradiated mammary and blood tissues of these strains differed significantly in baseline expressions of DNA repair, tumor suppressor, and stress response genes. LD exposures of 7.5 cGy (weekly for 4 weeks) did not induce detectable genomic instability in either strain. However, the mammary glands of the sensitive strain but not the resistant strain showed early transcriptional responses involving: (a) diminished immune response, (b) increased cellular stress, (c) altered TGFβ-signaling, and (d) inappropriate expression of developmental genes. One month after LD exposure, the two strains showed opposing responses in transcriptional signatures linked to proliferation, senescence, and microenvironment functions. We also discovered a pre-exposure expression signature in both blood and mammary tissues that is predictive for poor survival among human cancer patients (p = 0.0001), and a post-LD-exposure signature also predictive for poor patient survival (p<0.0001). There is concordant direction of expression in the LD-exposed sensitive mouse strain, in biomarkers of human DCIS and in biomarkers of human breast tumors. Our findings support the hypothesis that genetic mechanisms that determine susceptibility to LD radiation induced mammary cancer in mice are similar to the tissue mechanisms that determine poor-survival in breast cancer patients. We observed non-linearity of the LD responses providing molecular evidence against the LNT risk model and obtained new evidence that LD responses are strongly

  6. Tuning magnetism by Kondo effect and frustration

    NASA Astrophysics Data System (ADS)

    Löhneysen, Hilbert V.

    2014-03-01

    Heavy-fermion systems are an ideal playground for studying the quantum phase transition (QPT) between paramagnetic and magnetically ordered ground states arising from the competition between Kondo and RKKY interactions. Two different routes have been identified by various experiments, i. e., the more traditional spin-density-wave (SDW) and the Kondo-breakdown approaches. However, up to now an a-priori assignment of a given system to these different routes has not been possible. Yet another route to quantum criticality not included in the above approaches might be geometric frustration of magnetic moments, a route well known for insulating magnets with competing interactions. First experiments on metallic systems have recently been conducted. In the canonical partially frustrated antiferromagnetic system CePd1-xNixAl, the Néel temperature TN(x) decreases, with TN --> 0 at the critical concentration xc ~ 0.144. The low-temperature specific heat C(T) evolves toward C/ Tα ln(T0/ T) for x -->xc. The unusual T dependence of C/ T is compatible with the Hertz-Millis-Moriya (HMM) scenario of quantum criticality if the quantum-critical fluctuations are two-dimensional in nature. Here two-dimensionality might arise from antiferromagnetic planes that are effectively decoupled by the frustrated Ce atoms in between. An exciting possibility is that the planes of frustrated Ce moments form a two-dimensional spin liquid. In the prototypical heavy-fermion system CeCu6-xAux the experiments by Schröder et al. provided the initial evidence of local quantum criticality. While concentration and pressure tuning of the quantum phase transition (QPT) are described by this scenario, magnetic-field tuning the QPT is in line with the SDW scenario. Elastic neutron scattering experiments on CeCu5.5Au0.5 under hydrostatic pressure p show that at p = 8 kbar, TN and the magnetic propagation vector attain almost the values of CeCu5.7Au0.3. This x - p analogy away from the QPT is highly remarkable

  7. Combinatorial DNA Damage Pairing Model Based on X-Ray-Induced Foci Predicts the Dose and LET Dependence of Cell Death in Human Breast Cells

    SciTech Connect

    Vadhavkar, Nikhil; Pham, Christopher; Georgescu, Walter; Deschamps, Thomas; Heuskin, Anne-Catherine; Tang, Jonathan; Costes, Sylvain V.

    2014-09-01

    are based on experimental RIF and are three times larger than the hypothetical LEM voxel used to fit survival curves. Our model is therefore an alternative to previous approaches that provides a testable biological mechanism (i.e., RIF). In addition, we propose that DSB pairing will help develop more accurate alternatives to the linear cancer risk model (LNT) currently used for regulating exposure to very low levels of ionizing radiation.

  8. Suppression of alkylating agent induced cell transformation and gastric ulceration by low-dose alkylating agent pretreatment

    SciTech Connect

    Onodera, Akira; Kawai, Yuichi; Kashimura, Asako; Ogita, Fumiya; Tsutsumi, Yasuo; Itoh, Norio

    2013-06-14

    Highlights: •Low-dose MNNG pretreatment suppresses high-dose MNNG induced in vitro transformation. •Gastric ulcers induced by high-dose MNNG decreased after low-dose MNNG pretreatment. •Efficacy of low-dose MNNG related to resistance of mutation and oxidative stress. -- Abstract: Exposure to mild stress by chemicals and radiation causes DNA damage and leads to acquired stress resistance. Although the linear no-threshold (LNT) model of safety assessment assumes risk from any dose, evidence from radiological research demonstrates a conflicting hormetic phenomenon known as the hormesis effect. However, the mechanisms underlying radiation hormesis have not yet been clarified, and little is known about the effects of low doses of chemical carcinogens. We analyzed the efficacy of pretreatment with low doses of the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) on the subsequent induction of cell transformation and gastric ulceration by high-dose MNNG. We used an in vitro Balb/3T3 A31-1-1 cell transformation test and monitored the formation of gastric ulcers in 5-week-old male ICR mice that were administered MNNG in drinking water. The treatment concentrations of MNNG were determined by the cell survival rate and past reports. For low-dose in vitro and in vivo experiments, MNNG was used at 0.028 μM, and 2.8 μg/mL, respectively. The frequency of cell transformation induced by 10 μm MNNG was decreased by low-dose MNNG pretreatment to levels similar to that of spontaneous transformation. In addition, reactive oxygen species (ROS) and mutation frequencies induced by 10 μm MNNG were decreased by low-dose MNNG pretreatment. Importantly, low-dose MNNG pretreatment had no effect on cell proliferation. In vivo studies showed that the number of gastric ulcers induced by 1 mg/mL MNNG decreased after low-dose MNNG pretreatment. These data indicate that low-dose pretreatment with carcinogens may play a beneficial role in the prevention of chemical toxicity

  9. Raman, dielectric and variable range hopping nature of Gd2O3-doped K0.5N0.5NbO3 piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Peddigari, Mahesh; Dobbidi, Pamu

    2015-10-01

    (K0.5Na0.5)NbO3 (KNN) + x wt% Gd2O3 (x = 0 -1.5) ceramics have been prepared by conventional solid state reaction method. The effect of Gd2O3 on the structural, microstructural and dielectric properties of KNN ceramics were studied systematically. The effect of Gd2O3 on phase transformation from orthorhombic to psuedocubic structure is explained interms of changes in the internal vibration modes of NbO6 octahedra. The Raman intensity of the stretching mode v1 enhanced and shifted toward higher wavenumber with Gd2O3 concentration, which is attributed to the increase in polarizability and change in the O-Nb-O bond angles. Microstructural analysis revealed that the grain size of the KNN ceramics decreases from 2.26 ± 1.07 μm to 0.35 ± 0.13 μm and becomes homogenous with an increase in Gd2O3 concentration. The frequency dependent dielectric spectra are analyzed by using Havriliak-Negami function. The fitted symmetry parameter and relaxation time (τ) are found to be 0.914 and 8.78 × 10-10 ± 5.5 × 10-11 s, respectively for the sample doped with x = 1.0. The addition of Gd2O3 to the KNN shifted the polymorphic phase transition orthorhombic to tetragonal transition temperature (TO-T) from 199oC to 85oC with enhanced dielectric permittivity (ɛ' = 1139 at 1 MHz). The sample with x = 1.0, shown a high dielectric permittivity (ɛ' = 879) and low dielectric loss (<5%) in the broad temperature range (-140oC - 150oC) with the Curie temperature 307 oC can have the potential for high temperature piezoelectric and tunable RF circuit applications. The temperature dependent AC-conductivity follows the variable range hopping conduction mechanism by obtaining the slope -0.25 from the ln[ln(ρac)] versus ln(T) graph in the temperature range of 133 K-308 K. The effect of Gd2O3 on the Mott's parameters such as density of states (N(EF)), hopping length (RH), and hopping energy (WH) have been discussed.

  10. Final Report [The c-Abl signaling network in the radioadaptive response

    SciTech Connect

    Chi-Min, Yuan

    2014-01-28

    The radioadaptive response, or radiation hormesis, i.e. a low dose of radiation can protect cells and organisms from the effects of a subsequent higher dose, is a widely recognized phenomenon. Mechanisms underlying such radiation hormesis, however, remain largely unclear. Preliminary studies indicate an important role of c-Abl signaling in mediating the radioadaptive response. We propose to investigate how c-Abl regulates the crosstalk between p53 and NFκB in response to low doses irradiation. We found in our recent study that low dose IR induces a reciprocal p53 suppression and NFκB activation, which induces HIF-a and subsequently a metabolic reprogramming resulting in a transition from oxidative phosphorylation to glycolysis. Of importance is that this glycolytic switch is essential for the radioadaptive response. This low-dose radiationinduced HIF1α activation was in sharp contrast with the high-dose IR-induced p53 activation and HIF1α inhibition. HIF1α and p53 seem to play distinct roles in mediating the radiation dose-dependent metabolic response. The induction of HIF1α-mediated glycolysis is restricted to a low dose range of radiation, which may have important implications in assessing the level of radiation exposure and its potential health risk. Our results support a dose-dependent metabolic response to IR. When IR doses are below the threshold of causing detectable DNA damage (<0.2Gy) and thus little p53 activation, HIF1α is induced resulting in induction of glycolysis and increased radiation resistance. When the radiation dose reaches levels eliciting DNA damage, p53 is activated and diminishes the activity of HIF1α and glycolysis, leading to the induction of cell death. Our work challenges the LNT model of radiation exposure risk and provides a metabolic mechanism of radioadaptive response. The study supports a need for determining the p53 and HIF1α activity as a potential reliable biological readout of radiation exposure in humans. The

  11. Mammography-oncogenecity at low doses.

    PubMed

    Heyes, G J; Mill, A J; Charles, M W

    2009-06-01

    dose exposure, it is not a low dose rate examination, and protraction of dose should not be confused with fractionation. Although there is potential for a suppressive effect at low doses, recent epidemiological data, and several international radiation risk assessments, continue to promote the linear no-threshold (LNT) model. Finally, recent studies have shown that magnetic resonance imaging (MRI) is more sensitive than mammography in detecting invasive breast cancer in women with a genetic sensitivity. Since an increase in the risk associated with mammographic screening would blur the justification of exposure for this high risk subgroup, the use of other (non-ionising) screening modalities is preferable.

  12. Combinatorial DNA damage pairing model based on X-ray-induced foci predicts the dose and LET dependence of cell death in human breast cells.

    PubMed

    Vadhavkar, Nikhil; Pham, Christopher; Georgescu, Walter; Deschamps, Thomas; Heuskin, Anne-Catherine; Tang, Jonathan; Costes, Sylvain V

    2014-09-01

    model are based on experimental RIF and are three times larger than the hypothetical LEM voxel used to fit survival curves. Our model is therefore an alternative to previous approaches that provides a testable biological mechanism (i.e., RIF). In addition, we propose that DSB pairing will help develop more accurate alternatives to the linear cancer risk model (LNT) currently used for regulating exposure to very low levels of ionizing radiation.

  13. Swift heavy ion irradiation of InP: Thermal spike modeling of track formation

    SciTech Connect

    Kamarou, A.; Wesch, W.; Wendler, E.; Undisz, A.; Rettenmayr, M.

    2006-05-01

    Irradiation of single-crystalline InP with swift heavy ions (SHI's) causes the formation of ion tracks for certain irradiation temperatures if the electronic energy deposition exceeds a threshold value. With increasing SHI fluence, more and more ion tracks are formed, until a continuous amorphous layer is produced due to the multiple overlapping of the tracks at high ion fluences. Single-crystalline InP samples were irradiated either at liquid nitrogen temperature (LNT) or at room temperature (RT) with Kr, Xe, or Au ions with specific energies ranging from ca. 0.3 to 3.0 MeV/u. Afterwards, the samples were investigated by means of Rutherford backscattering spectrometry and transmission electron microscopy in the plan-view and cross-section geometry. We show that the experimental data obtained can be qualitatively and quantitatively described on the basis of the inelastic thermal spike (TS) model, which was originally used only for metallic targets. The presented extension of the TS model on semiconductors covers mainly the very first stage of the energy transfer from SHI's (so-called 'ionization spikes'). Our results show that the extended TS model offers a self-consistent way to explain the influence of various irradiation conditions (ion mass, ion energy, irradiation temperature, etc.) on the ion track formation and damage accumulation in InP and, therefore, can make a contribution to a better understanding of the underlying mechanisms. Further, our results prejudice the amenity of a single value of the threshold electronic energy loss as a fundamental quantity that is commonly used for the description of track formation in solids irradiated with different ion species. There is no universal RT threshold for track formation in InP, but it is noticeably higher for lighter ions (12.0 and 14.8 keV/nm for RT irradiations with Au and Xe, respectively). Our experimental and simulation results support the idea that the formation of visible tracks requires a predamaging

  14. Swift heavy ion irradiation of InP: Thermal spike modeling of track formation

    NASA Astrophysics Data System (ADS)

    Kamarou, A.; Wesch, W.; Wendler, E.; Undisz, A.; Rettenmayr, M.

    2006-05-01

    Irradiation of single-crystalline InP with swift heavy ions (SHI’s) causes the formation of ion tracks for certain irradiation temperatures if the electronic energy deposition exceeds a threshold value. With increasing SHI fluence, more and more ion tracks are formed, until a continuous amorphous layer is produced due to the multiple overlapping of the tracks at high ion fluences. Single-crystalline InP samples were irradiated either at liquid nitrogen temperature (LNT) or at room temperature (RT) with Kr, Xe, or Au ions with specific energies ranging from ca. 0.3to3.0MeV/u . Afterwards, the samples were investigated by means of Rutherford backscattering spectrometry and transmission electron microscopy in the plan-view and cross-section geometry. We show that the experimental data obtained can be qualitatively and quantitatively described on the basis of the inelastic thermal spike (TS) model, which was originally used only for metallic targets. The presented extension of the TS model on semiconductors covers mainly the very first stage of the energy transfer from SHI’s (so-called “ionization spikes”). Our results show that the extended TS model offers a self-consistent way to explain the influence of various irradiation conditions (ion mass, ion energy, irradiation temperature, etc.) on the ion track formation and damage accumulation in InP and, therefore, can make a contribution to a better understanding of the underlying mechanisms. Further, our results prejudice the amenity of a single value of the threshold electronic energy loss as a fundamental quantity that is commonly used for the description of track formation in solids irradiated with different ion species. There is no universal RT threshold for track formation in InP, but it is noticeably higher for lighter ions (12.0 and 14.8keV/nm for RT irradiations with Au and Xe, respectively). Our experimental and simulation results support the idea that the formation of visible tracks requires a

  15. Application of Logistic Modeling to the Biochar Heterogeneity Conundrum

    NASA Astrophysics Data System (ADS)

    Harvey, O. R.; Kuo, L. J.

    2016-12-01

    Although widely discussed in qualitative terms, there is a dearth of information on quantitative values for biochar heterogeneity and their use to predict biochar performance as sorbents or long-term carbon sinks. Two logistic models of the general form, y= 1/(1+Mα(x±β) ) were developed and used to determine heterogeneity factors and predict cation sorption and carbon sequestration potential for different biochars. In the first model, M=10 and biochars are viewed as unique Bronsted-acid-type surfaces with y proportion of deprotonatable sites available for cation sorption at solution pH = x. β and α represents the pKa and heterogeneity factor of the biochar surface, respectively. For an ideal, homogeneous Bronsted-type acid α has a value -1 and the model is equivalent to the Henderson-Hasselbalch equation. Application of the model to K+/Na+ ion exchange data for a range of grass and wood biochars yielded βsurf values of 3.66 to 4.98 and αsurf of -0.94 to -0.21; indicative of weakly acidic, fairly homogenous (αsurf = -0.94) to very heterogeneous (αsurf = -0.21) biochar surface. In the second model, M = Euler's number (e) and biochar biodegradability (and hence carbon sequestration potential) is modeled based on biochar relative recalcitrance with y being the fraction of biochar carbon remaining after t years;; x being the biochar recalcitrance index, R50, and β and α representing kinetic and biochar heterogeneity factors, respectively. For two suites of grass-, wood- and manure-derived biochars, βdeg = 0.0312ln(t)+0.279 and values for αdeg ranged from -0.22 to -0.12. The presentation will discuss in further details 1) model calibration/validation, 2) variation in model parameters with key biochar production parameters, 3) prediction of metal sorption behavior of a given biochar and 4) biochar CO2-equivalents on the decadal- and centennial-scale.

  16. Spectroscopic measurements of the pH in NaCl brines

    NASA Astrophysics Data System (ADS)

    Millero, Frank J.; DiTrolio, Benjamin; Suarez, Andres F.; Lando, Gabriele

    2009-06-01

    Spectrophotometric measurements of the pH in natural waters such as seawater have been shown to yield precise results. In this paper, the sulfonephthalein indicator m-cresol purple ( mCP, H 2I) has been used to determine the pH of NaCl brines. The indicator has been calibrated in NaCl solutions from 5 to 45 °C and ionic strengths from 0.03 to 5.5 m. The calibrations were made using TRIS buffers (0.03 m, TRIS/TRIS-HCl) with known dissociation constants pK TRIS in NaCl solutions [Foti C., Rigano C. and Sammartano S. (1999) Analysis of thermodynamic data for complex formation: protonation of THAM and fluoride ion at different temperatures and ionic strength. Ann. Chim. 89, 1-12]. The values of pH were determined from pH=pK+log{(R-e1)/(e2-Re3)} where R = 578A/ 434A, the ratios of the indicator absorbance maximum at 578 and 434 nm, e1 = 0.00691, e2 = 2.222 and e3 = 0.1331 [Clayton T. and Byrne R. H. (1993) Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results. Deep-Sea Res. 40, 2115-2129]. Measurements were also made in NaCl solutions with different levels of TRIS (0.01-0.11 m). At low levels of TRIS buffer (<0.03 m), the values of pK mCP increased significantly. This effect can lead to erroneous values of pK mCP at low ionic strengths in estuaries and lakes. The measured values of pK mCP in NaCl as a function of ionic strength ( I/m) and temperature ( T/K) were fitted to the equation ( σ = 0.0072) pK=-29.095+2639.2/T+5.0417lnT-0.3307I0.5-186.80I0.5/T-0.28346I+296.44I/T+0.12841I1.5-68.23I1.5/T These results should be useful in determining the pH of NaCl brines in natural waters from 0 to 50 °C.

  17. Transport in thin polarized Fermi-liquid films

    NASA Astrophysics Data System (ADS)

    Li, David Z.; Anderson, R. H.; Miller, M. D.

    2015-10-01

    We calculate expressions for the state-dependent quasiparticle lifetime τσ, the thermal conductivity κ , the shear viscosity η , and discuss the spin diffusion coefficient D for Fermi-liquid films in two dimensions. The expressions are valid for low temperatures and arbitrary polarization. In two dimensions, as in three dimensions, the integrals over the transition rates factor into energy and angular parts. However, the angular integrations contain a weak divergence. This problem is addressed using the method of K. Miyake and W. J. Mullin [Phys. Rev. Lett. 50, 197 (1983), 10.1103/PhysRevLett.50.197; J. Low Temp. Phys. 56, 499 (1984), 10.1007/BF00681808]. The low-temperature expressions for the transport coefficients are essentially exact. We find that κ-1˜T lnT , and η-1˜T2 for arbitrary polarizations 0 ≤P ≤1 . These results are in agreement with earlier zero-polarization results of H. H. Fu and C. Ebner [Phys. Rev. A 10, 338 (1974)., 10.1103/PhysRevA.10.338], but differ from the temperature dependence of the shear viscosity found by D. S. Novikov (arXiv:cond-mat/0603184). They also differ from the discontinuous change of temperature dependence in D from zero to nonzero polarization that was discovered by Miyake and Mullin. We note that in two dimensions the shear viscosity requires a unique analysis. We obtain predictions for the density, temperature, and polarization dependence of κ ,η , and D for second-layer 3He films on graphite, and thin 3He-4He superfluid mixtures. For 3He on graphite, we find roughly an order of magnitude increase in magnitude for κ and η as the polarization is increased from 0 to 1. For D a similar large increase is predicted from zero polarization to the polarization where D is a maximum (˜0.74 ). We discuss the applicability of 3He thin films to

  18. Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community

    PubMed Central

    2010-01-01

    Background Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). In the Río Tinto (Spain), brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum) and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery) and environmental applications (acid mine drainage, bioremediation). The aim of this study was to investigate the physiological differences between the free living (planktonic) and the sessile (biofilm associated) lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Results Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB), synthesis of cell wall structures (lnt, murA, murB), specific proteases (clpX/clpP), stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL), etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA) were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively) in the acidic (pH 1.8) water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Conclusions Our results indicate that the acidophilic

  19. Astrophysical blastwaves

    NASA Astrophysics Data System (ADS)

    Ostriker, Jeremiah P.; McKee, Christopher F.

    numerical integration. In addition to the new methods presented, the authors have obtained new results for evaporative blastwaves, impeded blastwaves, blastwaves with cloud crushing, bubbles, cosmological blastwaves (self-similar and non-self-similar, radiative and nonradiative), blastwaves in a wind, and detonations. Some of the new results found are exact. Included are the radiative, cosmological self-similar solution, appropriate to the universe (z>10) when inverse Compton cooling is efficient [lnR=const+(lnt)(15+17)24], and certain properties of the solutions mentioned above. In a series of appendixes several related issues are treated: energy conservation for multicomponent fluid in an expanding universe; central and edge derivatives of physical quantities in self-similar adiabatic blastwaves; shock jump conditions including energy input (detonations), and a variety of other matters.

  20. Genotypic and phenotypic analyses of hepatitis C virus variants observed in clinical studies of VX-222, a nonnucleoside NS5B polymerase inhibitor.

    PubMed

    Jiang, Min; Zhang, Eileen Z; Ardzinski, Andrzej; Tigges, Ann; Davis, Andrew; Sullivan, James C; Nelson, Michelle; Spanks, Joan; Dorrian, Jennifer; Nicolas, Olivier; Bartels, Doug J; Rao, B Govinda; Rijnbrand, Rene; Kieffer, Tara L

    2014-09-01

    VX-222, a thiophene-2-carboxylic acid derivative, is a selective nonnucleoside inhibitor of the hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase. In phase 1 and 2 clinical studies, VX-222 demonstrated effective antiviral efficacy, with substantial reductions in plasma HCV RNA in patients chronically infected with genotype 1 HCV. To characterize the potential for selection of VX-222-resistant variants in HCV-infected patients, the HCV NS5B gene was sequenced at baseline and during and after 3 days of VX-222 dosing (monotherapy) in a phase 1 study. Variants with the substitutions L419C/I/M/P/S/V, R422K, M423I/T/V, I482L/N/T, A486S/T/V, and V494A were selected during VX-222 dosing, and their levels declined over time after the end of dosing. Phenotypic analysis of these variants was conducted using HCV replicons carrying site-directed mutations. Of the 17 variants, 14 showed reduced susceptibility to VX-222 compared with the wild type, with the L419C/S and R422K variants having higher levels of resistance (>200-fold) than the rest of the variants (6.8- to 76-fold). The M423I and A486S variants remained susceptible to VX-222. The 50% effective concentration (EC50) for the L419P variant could not be obtained due to the poor replication of this replicon. The majority of the variants (15/17) were less fit than the wild type. A subset of the variants, predominately the L419S and R422K variants, were observed when the efficacy and safety of VX-222- and telaprevir-based regimens given for 12 weeks were investigated in genotype 1 HCV-infected patients in a phase 2 study. The NS3 and NS5B variants selected during the dual combination therapy showed reduced susceptibility to both telaprevir and VX-222 and had a lower replication capacity than the wild type. The phase 1b study has the ClinicalTrials.gov identifier NCT00911963, and the phase 2a study has ClinicalTrials.gov identifier NCT01080222.

  1. Secretion of bacterial lipoproteins: through the cytoplasmic membrane, the periplasm and beyond.

    PubMed

    Zückert, Wolfram R

    2014-08-01

    Bacterial lipoproteins are peripherally anchored membrane proteins that play a variety of roles in bacterial physiology and virulence in monoderm (single membrane-enveloped, e.g., gram-positive) and diderm (double membrane-enveloped, e.g., gram-negative) bacteria. After export of prolipoproteins through the cytoplasmic membrane, which occurs predominantly but not exclusively via the general secretory or Sec pathway, the proteins are lipid-modified at the cytoplasmic membrane in a multistep process that involves sequential modification of a cysteine residue and cleavage of the signal peptide by the signal II peptidase Lsp. In both monoderms and diderms, signal peptide processing is preceded by acylation with a diacylglycerol through preprolipoprotein diacylglycerol transferase (Lgt). In diderms but also some monoderms, lipoproteins are further modified with a third acyl chain through lipoprotein N-acyl transferase (Lnt). Fully modified lipoproteins that are destined to be anchored in the inner leaflet of the outer membrane (OM) are selected, transported and inserted by the Lol (lipoprotein outer membrane localization) pathway machinery, which consists of the inner-membrane (IM) ABC transporter-like LolCDE complex, the periplasmic LolA chaperone and the OM LolB lipoprotein receptor. Retention of lipoproteins in the cytoplasmic membrane results from Lol avoidance signals that were originally described as the "+2 rule". Surface localization of lipoproteins in diderms is rare in most bacteria, with the exception of several spirochetal species. Type 2 (T2SS) and type 5 (T5SS) secretion systems are involved in secretion of specific surface lipoproteins of γ-proteobacteria. In the model spirochete Borrelia burgdorferi, surface lipoprotein secretion does not follow established sorting rules, but remains dependent on N-terminal peptide sequences. Secretion through the outer membrane requires maintenance of lipoproteins in a translocation-competent unfolded conformation

  2. Wildfires in Chernobyl-contaminated forests and risks to the population and the environment: a new nuclear disaster about to happen?

    PubMed

    Evangeliou, Nikolaos; Balkanski, Yves; Cozic, Anne; Hao, Wei Min; Møller, Anders Pape

    2014-12-01

    Radioactive contamination in Ukraine, Belarus and Russia after the Chernobyl accident left large rural and forest areas to their own fate. Forest succession in conjunction with lack of forest management started gradually transforming the landscape. During the last 28 years dead wood and litter have dramatically accumulated in these areas, whereas climate change has increased temperature and favored drought. The present situation in these forests suggests an increased risk of wildfires, especially after the pronounced forest fires of 2010, which remobilized Chernobyl-deposited radioactive materials transporting them thousand kilometers far. For the aforementioned reasons, we study the consequences of different forest fires on the redistribution of (137)Cs. Using the time frequency of the fires that occurred in the area during 2010, we study three scenarios assuming that 10%, 50% and 100% of the area are burnt. We aim to sensitize the scientific community and the European authorities for the foreseen risks from radioactivity redistribution over Europe. The global model LMDZORINCA that reads deposition density of radionuclides and burnt area from satellites was used, whereas risks for the human and animal population were calculated using the Linear No-Threshold (LNT) model and the computerized software ERICA Tool, respectively. Depending on the scenario, whereas between 20 and 240 humans may suffer from solid cancers, of which 10-170 may be fatal. ERICA predicts insignificant changes in animal populations from the fires, whereas the already extreme radioactivity background plays a major role in their living quality. The resulting releases of (137)Cs after hypothetical wildfires in Chernobyl's forests are classified as high in the International Nuclear Events Scale (INES). The estimated cancer incidents and fatalities are expected to be comparable to those predicted for Fukushima. This is attributed to the fact that the distribution of radioactive fallout after the

  3. SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    NASA Astrophysics Data System (ADS)

    Pankow, J. F.; Asher, W. E.

    2007-08-01

    The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm) and enthalpy of vaporization ΔHvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10pL,io(T)=Σkνk,ibk(T) where νk,i is the number of groups of type k, and bk(T) is the contribution to log10 pL,io(T) by each group of type k. A zeroeth group is included that uses b0(T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C-C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T) is assumed to follow b(T)=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test set of 161 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10pL,io(T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, pL,io(T) values are predicted to within a factor of 2. Because d(log10pL,io(T))/d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of

  4. Ectopic and Visceral Fat Deposition in Lean and Obese Patients With Type 2 Diabetes.

    PubMed

    Levelt, Eylem; Pavlides, Michael; Banerjee, Rajarshi; Mahmod, Masliza; Kelly, Catherine; Sellwood, Joanna; Ariga, Rina; Thomas, Sheena; Francis, Jane; Rodgers, Christopher; Clarke, William; Sabharwal, Nikant; Antoniades, Charalambos; Schneider, Jurgen; Robson, Matthew; Clarke, Kieran; Karamitsos, Theodoros; Rider, Oliver; Neubauer, Stefan

    2016-07-05

    Type 2 diabetes (T2D) and obesity are associated with nonalcoholic fatty liver disease, cardiomyopathy, and cardiovascular mortality. Both show stronger links between ectopic and visceral fat deposition, and an increased cardiometabolic risk compared with subcutaneous fat. This study investigated whether lean patients (Ln) with T2D exhibit increased ectopic and visceral fat deposition and whether these are linked to cardiac and hepatic changes. Twenty-seven obese patients (Ob) with T2D, 15 Ln-T2D, and 12 normal-weight control subjects were studied. Subjects underwent cardiac computed tomography, cardiac magnetic resonance imaging (MRI), proton and phosphorus MR spectroscopy, and multiparametric liver MR, including hepatic proton MRS, T1- and T2*-mapping yielding "iron-corrected T1" [cT1]. Diabetes, with or without obesity, was associated with increased myocardial triglyceride content (p = 0.01), increased hepatic triglyceride content (p = 0.04), and impaired myocardial energetics (p = 0.04). Although cardiac structural changes, steatosis, and energetics were similar between the T2D groups, epicardial fat (p = 0.04), hepatic triglyceride (p = 0.01), and insulin resistance (p = 0.03) were higher in Ob-T2D. Epicardial fat, hepatic triglyceride, and insulin resistance correlated negatively with systolic strain and diastolic strain rates, which were only significantly impaired in Ob-T2D (p < 0.001 and p = 0.006, respectively). Fibroinflammatory liver disease (elevated cT1) was only evident in Ob-T2D patients. cT1 correlated with hepatic and epicardial fat (p < 0.001 and p = 0.01, respectively). Irrespective of body mass index, diabetes is related to significant abnormalities in cardiac structure, energetics, and cardiac and hepatic steatosis. Obese patients with T2D show a greater propensity for ectopic and visceral fat deposition. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  5. Evaluation of potential human health effects associated with the agricultural uses of 1,3-D: Spatial and temporal stochastic risk analysis.

    PubMed

    Driver, Jeffrey H; Price, Paul S; Van Wesenbeeck, Ian; Ross, John H; Gehen, Sean; Holden, Larry R; Landenberger, Bryce; Hastings, Kerry; Yan, Zhongyu June; Rasoulpour, Reza

    2016-11-15

    Dow AgroSciences (DAS) markets and sells 1,3-Dichloropropene (1,3-D), the active ingredient in Telone®, which is used as a pre-plant soil fumigant nematicide in economically important crops in California. 1,3-D has been regulated as a "probable human carcinogen" and the California Department of Pesticide Regulation limits use of 1,3-D based on human health risk assessments for bystanders. This paper presents a risk characterization for bystanders based on advances in the assessment of both exposure and hazard. The revised bystander risk assessment incorporates significant advances: 1) new data on residency duration and mobility in communities where 1,3-D is in high demand; 2) new information on spatial and temporal concentrations of 1,3-D in air based on multi-year modeling using a validated model; and 3) a new stochastic spatial and temporal model of long-term exposures. Predicted distributions of long-term, chronic exposures indicate that current, and anticipated uses of 1,3-D would result in lifetime average daily doses lower than 0.002mg/kg/d, a dose associated with theoretical lifetime excess cancer risk of <10(-5) to >95% of the local population based on a non-threshold risk assessment approach. Additionally, examination of 1,3-D toxicity studies including new chronic toxicity data and mechanism of action supports the use of a non-linear, threshold based risk assessment approach. The estimated maximum annual average daily dose of <0.0016mg/kg/d derived from the updated exposure assessment was then compared with a threshold point of departure. The calculated margin of exposure is >1000-fold, a clear indication of acceptable risk for human health. In summary, the best available science supports 1,3-D's threshold nature of hazard and the revised exposure assessment supports that current agricultural uses of 1,3-D are associated with reasonable certainty of no harm, i.e., estimated long-term exposures pose insignificant health risks to bystanders even when the

  6. Importance of age and postimplantation experience on speech perception measures in children with sequential bilateral cochlear implants.

    PubMed

    Peters, B Robert; Litovsky, Ruth; Parkinson, Aaron; Lake, Jennifer

    2007-08-01

    Clinical trials in which children received bilateral cochlear implants in sequential operations were conducted to analyze the extent to which bilateral implantation offers benefits on a number of measures. The present investigation was particularly focused on measuring the effects of age at implantation and experience after activation of the second implant on speech perception performance. Thirty children aged 3 to 13 years were recipients of 2 cochlear implants, received in sequential operations, a minimum of 6 months apart. All children received their first implant before 5 years of age and had acquired speech perception capabilities with the first device. They were divided into 3 age groups on the basis of age at time of second ear implantation: Group I, 3 to 5 years; Group II, 5.1 to 8 years; and Group III, 8.1 to 13 years. Speech perception measures in quiet included the Multisyllabic Lexical Neighborhood Test (MLNT) for Group I, the Lexical Neighborhood Test (LNT) for Groups II and III, and the Hearing In Noise Test for Children (HINT-C) sentences in quiet for Group III. Speech perception in noise was assessed using the Children's Realistic Intelligibility and Speech Perception (CRISP) test. Testing was performed preoperatively and again postactivation of the second implant at 3, 6, and 12 months (CRISP at 3 and 9 mo) in both the unilateral and bilateral conditions in a repeated-measures study design. Two-way repeated-measures analysis of variance was used to analyze statistical significance among device configurations and performance over time. US Multicenter. Results for speech perception in quiet show that children implanted sequentially acquire open-set speech perception in the second ear relatively quickly (within 6 mo). However, children younger than 8 years do so more rapidly and to a higher level of speech perception ability at 12 months than older children (mean second ear MLNT/LNT scores at 12 months: Group I, 83.9%; range, 71-96%; Group II, 59

  7. Genetic Control of the Trigger for the G2/M Checkpoint

    SciTech Connect

    Hall, Eric J.; Smilenov, Lubomir B.; Young, Erik F.

    2013-10-01

    The work undertaken in this project addressed two seminal areas of low dose radiation biology that are poorly understood and controversial. These areas are the challenge to the linear-no-threshold (LNT) paradigm at low doses of radiation and, the fundamental elements of radiation bystander effect biology Genetic contributions to low dose checkpoint engagement: The LNT paradigm is an extrapolation of known, measured cancer induction endpoints. Importantly, data for lower doses is often not available. Debatably, radiation protection standards have been introduced which are prudently contingent on the adherence of cancer risk to the established trend seen at higher doses. Intriguing findings from other labs have hinted at separate DNA damage response programs that engage at low or high levels of radiation. Individual radiation sensitivity commensurate with hemizygosity for a radiation sensitivity gene has been estimated at 1-2% in the U.S.. Careful interrogation of the DNA damage response at low doses of radiation became important and served as the basis for this grant. Several genes were tested in combinations to determine if combined haploinsufficiency for multiple radiosensitizing genes could render a cell more sensitive to lower levels of acute radiation exposure. We measured a classical radiation response endpoint, cell cycle arrest prior to mitosis. Mouse embryo fibroblasts were used and provided a uniform, rapidly dividing and genetically manipulable population of study. Our system did not report checkpoint engagement at acute doses of gamma rays below 100 mGy. The system did report checkpoint engagement reproducibly at 500 mGy establishing a threshold for activation between 100 and 500 mGy. Engagement of the checkpoint was ablated in cells nullizygous for ATM but was otherwise unperturbed in cells combinatorially haploinsufficient for ATM and Rad9, ATM and PTEN or PTEN and Rad9. Taken together, these experiments tell us that, in a sensitive fibroblast culture

  8. Human health risk assessment of nitrosamines and nitramines for potential application in CO2 capture.

    PubMed

    Ravnum, S; Rundén-Pran, E; Fjellsbø, L M; Dusinska, M

    2014-07-01

    Emission and accumulation of carbon dioxide (CO2) in the atmosphere exert an environmental and climate change challenge. An attempt to deal with this challenge is made at Mongstad by application of amines for CO2 capture and storage (CO2 capture Mongstad (CCM) project). As part of the CO2 capture process, nitrosamines and nitramines may be emitted. Toxicological testing of nitrosamines and nitramines indicate a genotoxic potential of these substances. Here we present a risk characterization and assessment for five nitrosamines (N-Nitrosodi-methylamine (NDMA) N-Nitrosodi-ethylamine (NDEA), N-Nitroso-morpholine (NNM), N-Nitroso-piperidine (NPIP), and Dinitroso-piperazine (DNP)) and two nitramines (N-Methyl-nitramine (NTMA), Dimethyl-nitramine (NDTMA)), which are potentially emitted from the CO2 capture plant (CCP). Human health risk assessment of genotoxic non-threshold substances is a heavily debated topic, and no consensus methodology exists internationally. Extrapolation modeling from high-dose animal exposures to low-dose human exposures can be crucial for the final risk calculation. In the work presented here, different extrapolation models are discussed, and suggestions on applications are given. Then, preferred methods for calculating derived minimal effect level (DMEL) are presented with the selected nitrosamines and nitramines.

  9. Iron plaque formed under aerobic conditions efficiently immobilizes arsenic in Lupinus albus L roots.

    PubMed

    Fresno, Teresa; Peñalosa, Jesús M; Santner, Jakob; Puschenreiter, Markus; Prohaska, Thomas; Moreno-Jiménez, Eduardo

    2016-09-01

    Arsenic is a non-threshold carcinogenic metalloid. Thus, human exposure should be minimised, e.g. by chemically stabilizing As in soil. Since iron is a potential As immobiliser, it was investigated whether root iron plaque, formed under aerobic conditions, affects As uptake, metabolism and distribution in Lupinus albus plants. White lupin plants were cultivated in a continuously aerated hydroponic culture containing Fe/EDDHA or FeSO4 and exposed to arsenate (5 or 20 μM). Only FeSO4 induced surficial iron plaque in roots. LA-ICP-MS analysis accomplished on root sections corroborated the association of As to this surficial Fe. Additionally, As(V) was the predominant species in FeSO4-treated roots, suggesting less efficient As uptake in the presence of iron plaque. Fe/EDDHA-exposed roots neither showed such surficial FeAs co-localisation nor As(V) accumulation; in contrast As(III) was the predominant species in root tissue. Furthermore, FeSO4-treated plants showed reduced shoot-to-root As ratios, which were >10-fold lower compared to Fe/EDDHA treatment. Our results highlight the role of an iron plaque formed in roots of white lupin under aerobic conditions on As immobilisation. These findings, to our knowledge, have not been addressed before for this plant and have potential implications on soil remediation (phytostabilisation) and food security (minimising As in crops).

  10. When is a dose not a dose

    SciTech Connect

    Bond, V.P.

    1991-01-01

    Although an enormous amount of progress has been made in the fields of radiation protection and risk assessment, a number of significant problems remain. The one problem which transcends all the rest, and which has been subject to considerable misunderstanding, involves what has come to be known as the 'linear non-threshold hypothesis', or 'linear hypothesis'. Particularly troublesome has been the interpretation that any amount of radiation can cause an increase in the excess incidence of cancer. The linear hypothesis has dominated radiation protection philosophy for more than three decades, with enormous financial, societal and political impacts and has engendered an almost morbid fear of low-level exposure to ionizing radiation in large segments of the population. This document presents a different interpretation of the linear hypothesis. The basis for this view lies in the evolution of dose-response functions, particularly with respect to their use initially in the context of early acute effects, and then for the late effects, carcinogenesis and mutagenesis. 11 refs., 4 figs. (MHB)

  11. Health risk estimates for groundwater and soil contamination in the Slovak Republic: a convenient tool for identification and mapping of risk areas.

    PubMed

    Fajčíková, K; Cvečková, V; Stewart, A; Rapant, S

    2014-10-01

    We undertook a quantitative estimation of health risks to residents living in the Slovak Republic and exposed to contaminated groundwater (ingestion by adult population) and/or soils (ingestion by adult and child population). Potential risk areas were mapped to give a visual presentation at basic administrative units of the country (municipalities, districts, regions) for easy discussion with policy and decision-makers. The health risk estimates were calculated by US EPA methods, applying threshold values for chronic risk and non-threshold values for cancer risk. The potential health risk was evaluated for As, Ba, Cd, Cu, F, Hg, Mn, NO3 (-), Pb, Sb, Se and Zn for groundwater and As, B, Ba, Be, Cd, Cu, F, Hg, Mn, Mo, Ni, Pb, Sb, Se and Zn for soils. An increased health risk was identified mainly in historical mining areas highly contaminated by geogenic-anthropogenic sources (ore deposit occurrence, mining, metallurgy). Arsenic and antimony were the most significant elements in relation to health risks from groundwater and soil contamination in the Slovak Republic contributing a significant part of total chronic risk levels. Health risk estimation for soil contamination has highlighted the significance of exposure through soil ingestion in children. Increased cancer risks from groundwater and soil contamination by arsenic were noted in several municipalities and districts throughout the country in areas with significantly high arsenic levels in the environment. This approach to health risk estimations and visualization represents a fast, clear and convenient tool for delineation of risk areas at national and local levels.

  12. Inorganic arsenic removal in rice bran by percolating cooking water.

    PubMed

    Signes-Pastor, Antonio J; Carey, Manus; Meharg, Andrew A

    2017-11-01

    Rice bran, a by-product of milling rice, is highly nutritious but contains very high levels of the non-threshold carcinogen inorganic arsenic (i-As), at concentrations around 1mg/kg. This i-As content needs to be reduced to make rice bran a useful food ingredient. Evaluated here is a novel approach to minimizing rice bran i-As content which is also suitable for its stabilization namely, cooking bran in percolating arsenic-free boiling water. Up to 96% of i-As removal was observed for a range of rice bran products, with i-As removal related to the volume of cooking water used. This process reduced the copper, potassium, and phosphorus content, but had little effect on other trace- and macro-nutrient elements in the rice bran. There was little change in organic composition, as assayed by NIR, except for a decrease in the soluble sugar and an increase, due to biomass loss, in dietary fiber. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Genotoxicity--threshold or not? Introduction of cases of industrial chemicals.

    PubMed

    Bolt, Hermann M

    2003-04-11

    Many industrially and environmentally important industrial carcinogens display effects that lead them to be viewed and regulated as 'genotoxic compounds'. Some of these chemicals cause experimental tumours only at high or toxic doses. The current view is that non-threshold principles should be applied for risk assessments and to define permissible exposure values. The toxicological impact of underlying mechanisms is frequently not well investigated and understood. The classification of carcinogens is now in a state of discussion. In Germany, the 'MAK-Commission' has issued new recommendations to distinguish between 5 groups of proven and suspected carcinogens. This proposal includes a category of 'substances with carcinogenic potential for which genotoxicity plays no or at most a minor role'. Another category comprises 'substances with carcinogenic and genotoxic potential, the potency of which is considered so low that, provided that the MAK-value is observed, no significant contribution to human cancer risk is to be expected'. There is also a number of apparently genotoxic carcinogens where the existence of 'practical thresholds' is at least debated. One outstanding example is vinyl acetate, which must be viewed against the background of discussions on other industrial high-volume chemicals like formaldehyde, acrylonitrile, acrylamide and trichloroethylene. Main arguments in favour or against thresholds of carcinogenicity of these individual compounds are summarised. Current instruments of regulation should be adjusted to allow adequate consideration of carcinogenic effects of chemicals that are practically relevant at high doses only. Also, research into this field is encouraged.

  14. Health risk assessment linked to filling coastal quarries with treated dredged seaport sediments.

    PubMed

    Perrodin, Yves; Donguy, Gilles; Emmanuel, Evens; Winiarski, Thierry

    2014-07-01

    Dredged seaport sediments raise complex management problems since it is no longer possible to discharge them into the sea. Traditional waste treatments are poorly adapted for these materials in terms of absorbable volumes and cost. In this context, filling quarries with treated sediments appears interesting but its safety regarding human health must be demonstrated. To achieve this, a specific methodology for assessing health risks has been developed and tested on three seaport sediments. This methodology includes the development of a conceptual model of the global scenario studied and the definition of specific protocols for each of its major steps. The approach proposed includes in particular the use of metrological and experimental tools that are new in this context: (i) an experimental lysimeter for characterizing the deposit emissions, and (ii) a geological radar for identifying potential preferential pathways between the sediment deposit and the groundwater. The application of this approach on the three sediments tested for the scenario studied showed the absence of health risk associated with the consumption of groundwater for substances having a "threshold effect" (risk quotient <1), and an acceptable risk for substances having a "non-threshold effect", with the notable exception of arsenic (individual risk equal to 3.10(-6)).

  15. Risk of radiogenic second cancers following volumetric modulated arc therapy and proton arc therapy for prostate cancer.

    PubMed

    Rechner, Laura A; Howell, Rebecca M; Zhang, Rui; Etzel, Carol; Lee, Andrew K; Newhauser, Wayne D

    2012-11-07

    Prostate cancer patients who undergo radiotherapy are at an increased risk to develop a radiogenic second cancer. Proton therapy has been shown to reduce the predicted risk of second cancer when compared to intensity modulated radiotherapy. However, it is unknown if this is also true for the rotational therapies proton arc therapy and volumetric modulated arc therapy (VMAT). The objective of this study was to compare the predicted risk of cancer following proton arc therapy and VMAT for prostate cancer. Proton arc therapy and VMAT plans were created for three patients. Various risk models were combined with the dosimetric data (therapeutic and stray dose) to predict the excess relative risk (ERR) of cancer in the bladder and rectum. Ratios of ERR values (RRR) from proton arc therapy and VMAT were calculated. RRR values ranged from 0.74 to 0.99, and all RRR values were shown to be statistically less than 1, except for the value calculated with the linear-non-threshold risk model. We conclude that the predicted risk of cancer in the bladder or rectum following proton arc therapy for prostate cancer is either less than or approximately equal to the risk following VMAT, depending on which risk model is applied.

  16. Risk of radiogenic second cancers following volumetric modulated arc therapy and proton arc therapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Rechner, Laura A.; Howell, Rebecca M.; Zhang, Rui; Etzel, Carol; Lee, Andrew K.; Newhauser, Wayne D.

    2012-11-01

    Prostate cancer patients who undergo radiotherapy are at an increased risk to develop a radiogenic second cancer. Proton therapy has been shown to reduce the predicted risk of second cancer when compared to intensity modulated radiotherapy. However, it is unknown if this is also true for the rotational therapies proton arc therapy and volumetric modulated arc therapy (VMAT). The objective of this study was to compare the predicted risk of cancer following proton arc therapy and VMAT for prostate cancer. Proton arc therapy and VMAT plans were created for three patients. Various risk models were combined with the dosimetric data (therapeutic and stray dose) to predict the excess relative risk (ERR) of cancer in the bladder and rectum. Ratios of ERR values (RRR) from proton arc therapy and VMAT were calculated. RRR values ranged from 0.74 to 0.99, and all RRR values were shown to be statistically less than 1, except for the value calculated with the linear-non-threshold risk model. We conclude that the predicted risk of cancer in the bladder or rectum following proton arc therapy for prostate cancer is either less than or approximately equal to the risk following VMAT, depending on which risk model is applied.

  17. Activation of the Fanconi anemia/BRCA pathway at low doses of ionization radiation.

    PubMed

    Bosch, Pau Castillo; Bogliolo, Massimo; Surrallés, Jordi

    2015-11-01

    Fanconi anemia (FA) is a rare, clinically heterogeneous autosomal recessive or X-linked genetic disease characterized by chromosome fragility, congenital malformations and cancer susceptibility. FA patients are usually radiosensitive when exposed to radiotherapy but the role of the FA in response to ionizing radiation (IR) is controversial. Here we have investigated IR-induced activation of the FA pathway by systematically analyzing monoubiquitination of the central protein FANCD2 and subsequent recruitment to stalled replication forks in primary fibroblasts. We developed an immunolabelling method to simultaneously visualize IR-induced FANCD2 and γH2AX foci in S-phase. We observed FANCD2 foci formation in a subset of IR-induced γH2AX foci in S-phase cells. This was observed at doses of IR ranging from 0.1 to 5.0Gy in a dose dependent non-threshold fashion. Our results indicate that minimum doses of IR can produce replication fork stalling and FA pathway activation during S-phase in primary cells.

  18. Linear Versus Non-Linear Dose-Response Relationship Between Prenatal Alcohol Exposure and Meconium Concentration of Nine Different Fatty Acid Ethyl Esters

    PubMed Central

    Yang, J.Y.; Kwak, H.S.; Choi, J.S.; Ahn, H.K.; Oh, Y.J.; Velázquez-Armenta, E.Y.; Nava-Ocampo, A.A.

    2015-01-01

    Presence of individual fatty acid ethyl esters (FAEEs) in meconium is considered to be a reliable biomarker of prenatal alcohol exposure, and their concentration has been found to be linearly associated with poor postnatal development, supporting the widely extended idea that ethanol is a non-threshold teratogen. However, a growing number of epidemiological studies have consistently found a lack of adverse short- and long-term fetal outcomes at low exposure levels. We therefore aimed to investigate the relationship between the concentration of individual FAEEs and prenatal alcohol exposure in meconium samples collected within the first 6 to 12?h after birth from 182 babies born to abstainer mothers and from 54 babies born to women who self-reported either light or moderate alcohol ingestion in the second or third trimester of pregnancy. In most cases, the individual FAEE concentrations were negligible and not significantly different (P >0.05) between exposed and control babies. The concentrations appeared to increase linearly with the dose only in the few babies born to mothers who reported >3 drinks/week. These results provide evidence that the correlation between prenatal alcohol exposure and individual FAEE concentrations in meconium is non-linear shape, with a threshold probably at 3 drinks/week. PMID:26691866

  19. The effects of lead sources on oral bioaccessibility in soil and implications for contaminated land risk management.

    PubMed

    Palmer, Sherry; McIlwaine, Rebekka; Ofterdinger, Ulrich; Cox, Siobhan F; McKinley, Jennifer M; Doherty, Rory; Wragg, Joanna; Cave, Mark

    2015-03-01

    Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation, peat and granite domains accounted for elevated Pb concentrations compared to rural samples. High Pb solubility explained moderate-high gastric (G) bioaccessible fractions throughout the study area. Higher maximum G concentrations were measured in urban (97.6 mg kg(-1)) and mineralisation (199.8 mg kg(-1)) domains. Higher average G concentrations occurred in mineralisation (36.4 mg kg(-1)) and granite (36.0 mg kg(-1)) domains. Findings suggest diffuse anthropogenic and widespread geogenic contamination could be capable of presenting health risks, having implications for land management decisions in jurisdictions where guidance advises these forms of pollution should not be regarded as contaminated land. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Extreme sensitivity and the practical implications of risk assessment thresholds.

    PubMed

    Bukowski, John; Nicolich, Mark; Lewis, R Jeffrey

    2013-01-01

    Traditional risk-assessment theory assumes the existence of a threshold for non-cancer health effects. However, a recent trend in environmental regulation rejects this assumption in favor of non-threshold linearity for these endpoints. This trend is driven largely by two related concepts: (1) a theoretical assumption of wide-ranging human sensitivity, and (2) inability to detect thresholds in epidemiologic models. Wide-ranging sensitivity assumes a subpopulation with extreme background vulnerability, so that even trivial environmental exposures are hazardous to someone somewhere. We use examples from the real world of clinical medicine to show that this theoretical assumption is inconsistent with the biology of mammalian systems and the realities of patient care. Using examples from particulate-matter air-pollution research, we further show that failure to reject linearity is usually driven by statistical rather than biological considerations, and that nonlinear/threshold models often have a similar or better fit than their linear counterparts. This evidence suggests the existence of practical, real-world thresholds for most chemical exposures.

  1. Health related guide values for drinking-water since 1993 as guidance to assess presence of new analytes in drinking-water.

    PubMed

    Dieter, Hermann H

    2014-03-01

    Regulatory toxicologists, when going into assessment of a new analyte in drinking-water, very often miss the occasion to revert to scientifically consensual virtually safe lifetime exposure reference doses and corresponding health-related guide values (HRGV) for drinking-water, be those derived either to avoid concern over "threshold effects" or concern over exceedance of an unacceptable non-threshold cancer risk level. They then need a more restrictive precautionary yet science-compatible approach to directly avoid concern over the presence (measured concentration) of a new analyte in drinking-water. Therefore, the German Environment Agency (UBA, Umweltbundesamt) decided in 2003 to extrapolate international toxicological expertise collected since 1993 from assessing "old" analytes in drinking-water on new ones in form of five HRIV=health related indication values. They indicate the reasonable lowest maximal concentration from which on tiered or stepwise human toxicological evaluation of a new analyte might be necessary and meaningful. Their regulatory-toxicological function is that of placeholders as long as a possibly higher scientific HRGV or a surrogate value based on a threshold of toxicological concern (TTC) was not broadly agreed by science. The five-step HRIV scale between 0.01 and 3.0 μg/l combines international toxicological experience gained from "old" analytes since 1993 with the concepts of safety factors (SF(D)) to assess database deficiency and science-related extrapolation factors (EF) to extrapolate experimental data on humans. Each HRIV is valid and safe for a 2 l/day drinking-water exposure scenario either counting for 10% relative source contribution (compounds with threshold effects) or for a lifetime non-threshold cancer risk of up to 10(-6) and is the higher the more positive information exists regarding possible effects at critical toxic endpoints and for length of possible exposure. Past (historical) and present evaluations of "old

  2. Visualization of risk of radiogenic second cancer in the organs and tissues of the human body.

    PubMed

    Zhang, Rui; Mirkovic, Dragan; Newhauser, Wayne D

    2015-04-28

    Radiogenic second cancer is a common late effect in long term cancer survivors. Currently there are few methods or tools available to visually evaluate the spatial distribution of risks of radiogenic late effects in the human body. We developed a risk visualization method and demonstrated it for radiogenic second cancers in tissues and organs of one patient treated with photon volumetric modulated arc therapy and one patient treated with proton craniospinal irradiation. Treatment plans were generated using radiotherapy treatment planning systems (TPS) and dose information was obtained from TPS. Linear non-threshold risk coefficients for organs at risk of second cancer incidence were taken from the Biological Effects of Ionization Radiation VII report. Alternative risk models including linear exponential model and linear plateau model were also examined. The predicted absolute lifetime risk distributions were visualized together with images of the patient anatomy. The risk distributions of second cancer for the two patients were visually presented. The risk distributions varied with tissue, dose, dose-risk model used, and the risk distribution could be similar to or very different from the dose distribution. Our method provides a convenient way to directly visualize and evaluate the risks of radiogenic second cancer in organs and tissues of the human body. In the future, visual assessment of risk distribution could be an influential determinant for treatment plan scoring.

  3. Extreme Sensitivity and the Practical Implications of Risk Assessment Thresholds

    PubMed Central

    Bukowski, John; Nicolich, Mark; Lewis, R. Jeffrey

    2013-01-01

    Traditional risk-assessment theory assumes the existence of a threshold for non-cancer health effects. However, a recent trend in environmental regulation rejects this assumption in favor of non-threshold linearity for these endpoints. This trend is driven largely by two related concepts: (1) a theoretical assumption of wide-ranging human sensitivity, and (2) inability to detect thresholds in epidemiologic models. Wide-ranging sensitivity assumes a subpopulation with extreme background vulnerability, so that even trivial environmental exposures are hazardous to someone somewhere. We use examples from the real world of clinical medicine to show that this theoretical assumption is inconsistent with the biology of mammalian systems and the realities of patient care. Using examples from particulate-matter air-pollution research, we further show that failure to reject linearity is usually driven by statistical rather than biological considerations, and that nonlinear/threshold models often have a similar or better fit than their linear counterparts. This evidence suggests the existence of practical, real-world thresholds for most chemical exposures. PMID:23930098

  4. ICRP Publication 131: Stem cell biology with respect to carcinogenesis aspects of radiological protection.

    PubMed

    Hendry, J H; Niwa, O; Barcellos-Hoff, M H; Globus, R K; Harrison, J D; Martin, M T; Seed, T M; Shay, J W; Story, M D; Suzuki, K; Yamashita, S

    2016-06-01

    Current knowledge of stem cell characteristics, maintenance and renewal, evolution with age, location in 'niches', and radiosensitivity to acute and protracted exposures is reviewed regarding haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. The identity of the target cells for carcinogenesis continues to point to the more primitive and mostly quiescent stem cell population (able to accumulate the protracted sequence of mutations necessary to result in malignancy), and, in a few tissues, to daughter progenitor cells. Several biological processes could contribute to the protection of stem cells from mutation accumulation: (1) accurate DNA repair; (2) rapid induced death of injured stem cells; (3) retention of the intact parental strand during divisions in some tissues so that mutations are passed to the daughter differentiating cells; and (4) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the vital niche. DNA repair mainly operates within a few days of irradiation, while stem cell replications and competition require weeks or many months depending on the tissue type. This foundation is used to provide a biological insight to protection issues including the linear-non-threshold and relative risk models, differences in cancer risk between tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. © The International Society for Prosthetics and Orthotics.

  5. Influence of rovibrational excitation on the non-diabatic state-to-state dynamics for the Li(2p) + H2 → LiH + H reaction.

    PubMed

    He, Di; Yuan, Jiuchuang; Chen, Maodu

    2017-06-08

    The non-adiabatic state-to-state dynamics of the Li(2p) + H2 → LiH + H reaction has been studied using the time-dependent wave packet method, based on a set of diabatic potential energy surfaces recently developed by our group. Integral cross sections (ICSs) can be increase more than an order of magnitude by the vibrational excitation of H2, whereas the ICSs are barely affected by the rotational excitation of H2. Moreover, ICSs of the title reaction with vibrationally excited H2 decrease rapidly with increasing collision energy, which is a typical feature of non-threshold reaction. This phenomenon implies that the title reaction can transformed from an endothermic to an exothermic reaction by vibrational excitation of H2. With the increase of the collision energy, the sideways and backward scattered tendencies of LiH for the Li(2p) + H2(v = 0, j = 0, 1) → LiH + H reactions are enhanced slightly, while the backward scattering tendency of LiH for the Li(2p) + H2(v = 1, j = 0) → LiH + H reaction becomes remarkably weakened. For the reaction with vibrationally excited H2 molecule, both direct and indirect reaction mechanism exist simultaneously.

  6. An estimation error bound for pixelated sensing

    NASA Astrophysics Data System (ADS)

    Kreucher, Chris; Bell, Kristine

    2016-05-01

    This paper considers the ubiquitous problem of estimating the state (e.g., position) of an object based on a series of noisy measurements. The standard approach is to formulate this problem as one of measuring the state (or a function of the state) corrupted by additive Gaussian noise. This model assumes both (i) the sensor provides a measurement of the true target (or, alternatively, a separate signal processing step has eliminated false alarms), and (ii) The error source in the measurement is accurately described by a Gaussian model. In reality, however, sensor measurement are often formed on a grid of pixels - e.g., Ground Moving Target Indication (GMTI) measurements are formed for a discrete set of (angle, range, velocity) voxels, and EO imagery is made on (x, y) grids. When a target is present in a pixel, therefore, uncertainty is not Gaussian (instead it is a boxcar function) and unbiased estimation is not generally possible as the location of the target within the pixel defines the bias of the estimator. It turns out that this small modification to the measurement model makes traditional bounding approaches not applicable. This paper discusses pixelated sensing in more detail and derives the minimum mean squared error (MMSE) bound for estimation in the pixelated scenario. We then use this error calculation to investigate the utility of using non-thresholded measurements.

  7. Definition of medical event is to be based on the total source strength for evaluation of permanent prostate brachytherapy: A report from the American Society for Radiation Oncology.

    PubMed

    Nag, Subir; Demanes, D Jeffrey; Hagan, Michael; Rivard, Mark J; Thomadsen, Bruce R; Welsh, James S; Williamson, Jeffrey F

    2011-10-01

    The Nuclear Regulatory Commission deems it to be a medical event (ME) if the total dose delivered differs from the prescribed dose by 20% or more. A dose-based definition of ME is not appropriate for permanent prostate brachytherapy as it generates too many spurious MEs and thereby creates unnecessary apprehension in patients, and ties up regulatory bodies and the licensees in unnecessary and burdensome investigations. A more suitable definition of ME is required for permanent prostate brachytherapy. The American Society for Radiation Oncology (ASTRO) formed a working group of experienced clinicians to review the literature, assess the validity of current regulations, and make specific recommendations about the definition of an ME in permanent prostate brachytherapy. The working group found that the current definition of ME in §35.3045 as "the total dose delivered differs from the prescribed dose by 20 percent or more" was not suitable for permanent prostate brachytherapy since the prostate volume (and hence the resultant calculated prostate dose) is dependent on the timing of the imaging, the imaging modality used, the observer variability in prostate contouring, the planning margins used, inadequacies of brachytherapy treatment planning systems to calculate tissue doses, and seed migration within and outside the prostate. If a dose-based definition for permanent implants is applied strictly, many properly executed implants would be improperly classified as an ME leading to a detrimental effect on brachytherapy. The working group found that a source strength-based criterion, of >20% of source strength prescribed in the post-procedure written directive being implanted outside the planning target volume is more appropriate for defining ME in permanent prostate brachytherapy. ASTRO recommends that the definition of ME for permanent prostate brachytherapy should not be dose based but should be based upon the source strength (air-kerma strength) administered.

  8. Outpatient treatment with (131)I-anti-B1 antibody: radiation exposure to family members.

    PubMed

    Rutar, F J; Augustine, S C; Colcher, D; Siegel, J A; Jacobson, D A; Tempero, M A; Dukat, V J; Hohenstein, M A; Gobar, L S; Vose, J M

    2001-06-01

    The Nuclear Regulatory Commission (NRC) regulations that govern release of patients administered radioactive material have been revised to include dose-based criteria in addition to the conventional activity-based criteria. A licensee may now release a patient if the total effective dose equivalent to another individual from exposure to the released patient is not likely to exceed 5 mSv (500 mrem). The result of this dose-based release limit is that now many patients given therapeutic amounts of radioactive material no longer require hospitalization. This article presents measured dose data for 26 family members exposed to 22 patients treated for non-Hodgkin's lymphoma with (131)I-anti-B1 antibody after their release according to the new NRC dose-based regulations. The patients received administered activities ranging from 0.94 to 4.77 GBq (25--129 mCi). Family members were provided with radiation monitoring devices (film badges, thermoluminescent or optically stimulated luminescent dosimeters, or electronic digital dosimeters). Radiation safety personnel instructed the family members on the proper wearing and use of the devices. Instruction was also provided on actions recommended to maintain doses to potentially exposed individuals as low as is reasonably achievable. Family members wore the dosimeters for 2--17 d, with the range of measured dose values extending from 0.17 to 4.09 mSv (17--409 mrem). The average dose for infinite time based on dosimeter readings was 32% of the predicted doses projected to be received by the family members using the NRC method provided in regulatory guide 8.39. Therapy with (131)I-anti-B1 antibody can be conducted on an outpatient basis using the established recommended protocol. The patients can be released immediately with confidence that doses to other individuals will be below the 5-mSv (500 mrem) limit.

  9. Matlab Tools: An Alternative to Planning Systems in Brachytherapy Treatments

    SciTech Connect

    Herrera, Higmar

    2006-09-08

    This work proposes the use of the Matlab environment to obtain the treatment dose based on the reported data by Krishnaswamy and Liu et al. The comparison with reported measurements is showed for the Amersham source model. For the 3M source model, measurements with TLDs and a Monte Carlo simulation are compared to the data obtained by Matlab. The difference for the Amersham model is well under the 15% recommended by the IAEA and for the 3M model, although the difference is greater, the results are consistent. The good agreement to the reported data allows the Matlab calculations to be used in daily brachytherapy treatments.

  10. Risk assessment for neurobehavioral toxicity: SGOMSEC joint report.

    PubMed Central

    Hattis, D; Glowa, J; Tilson, H; Ulbrich, B

    1996-01-01

    Behavioral end points for neurotoxicity risk assessment have been developed and examined over the past three decades. They are now ready to move from simple qualitative guidelines, such as exemplified by reference doses, to more quantitative models, such as benchmark doses, based on dose-response information. Risk assessors, confronted by a wider array of methodologies and data than in the past, should be offered guidance in interpretation because now they have to deal with unaccustomed questions and problems. These include reversibility, susceptible populations, multiple end points, and the details of dose-response and dose-effect distributions. PMID:8860324

  11. Development and evaluation of a technique for in vivo monitoring of 60Co in human lungs

    NASA Astrophysics Data System (ADS)

    de Mello, J. Q.; Lucena, E. A.; Dantas, A. L. A.; Dantas, B. M.

    2016-07-01

    60Co is a fission product of 235U and represents a risk of internal exposure of workers in nuclear power plants, especially those involved in the maintenance of potentially contaminated parts and equipment. The control of 60Co intake by inhalation can be performed through in vivo monitoring. This work describes the evaluation of a technique through the minimum detectable activity and the corresponding minimum detectable effective doses, based on biokinetic and dosimetric models of 60Co in the human body. The results allow to state that the technique is suitable either for monitoring of occupational exposures or evaluation of accidental intake.

  12. Comparison of UV-B measurements performed with a Brewer spectrophotometer and a new UVB-1 broad band detector

    NASA Technical Reports Server (NTRS)

    Bais, Alkiviadis F.; Zerefos, Christos S.; Meleti, Charicleia; Ziomas, Ioannis C.

    1994-01-01

    Measurements of the UV-B erythemal dose, based on solar spectra acquired with a Brewer spectrophotometer at Thessaloniki, Greece, are compared to measurements performed with the recently introduced, by the Yankee Environmental Systems, (Robertson type) broad band solar UV-B detector. The spectral response function of this detector, when applied to the Brewer spectral UV-B measurements, results in remarkably comparable estimates of the erythemal UV-B dose. The two instruments provide similar information on the UV-B dose when they are cross-examined under a variety of meteorological and atmospheric conditions and over the a large range of solar zenith angles and total ozone.

  13. [Determining the optimal fluorine dose in the drinking water of the South Center hydrological region of Haiti].

    PubMed

    Emmanuel, Evens; Fanfan, Pierre N; Louis, Régine; Michel, Gérard-Alain

    2002-01-01

    This study aims at determining the optimal dose of fluorine in the drinking water in the South Center region of Haiti. This region has an average daily temperature ranging from 17 to 33 C. Water samples were collected from November 15th to December 20th 2000 on the water resource of some of the counties of the hydrological South Center region of Haiti. The results show that the concentration of fluorine in this region varies between 0 and 0.83 mg/litre. However, the calculated optimal dose based on the temperature measured show that fluorine concentration of water should be between 0.7 and 1 mg/litre.

  14. Radiation biodosimetry: Applications for spaceflight

    NASA Astrophysics Data System (ADS)

    Blakely, W. F.; Miller, A. C.; Grace, M. B.; McLeland, C. B.; Luo, L.; Muderhwa, J. M.; Miner, V. L.; Prasanna, P. G. S.

    The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted personnel dosimeters and cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a portable hematology analyzer, molecular biodosimetry using nucleic acid and antigen-based diagnostic equipment, and a dose assessment management software application. A dry-capillary tube reagent-based centrifuge blood cell counter (QBC Autoread Plus, Beckon Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins) can be measured in real time using such diagnostic detection technologies as miniaturized nucleic acid sequences and antigen-based biosensors, but they require validation of dose-dependent targets and development of optimized protocols and analysis systems. The Biodosimetry Assessment Tool, a software application, calculates radiation dose based on a patient's physical signs and symptoms and blood cell count analysis. It also annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. These radiation assessment diagnostic technologies can have dual-use applications supporting general medical-related care.

  15. Ideal rather than actual body weight should be used to calculate cell dose in allogeneic hematopoietic stem cell transplantation.

    PubMed

    Singhal, S; Gordon, L I; Tallman, M S; Winter, J N; Evens, A M; Evens, A O; Frankfurt, O; Williams, S F; Grinblatt, D; Kaminer, L; Meagher, R; Mehta, J

    2006-03-01

    Whether the CD34+ and CD3+ cell doses in allogeneic HSCT should be estimated using actual (ABW) or ideal (IBW) body weight has never been definitively determined. We have shown that CD34+ cell doses based upon IBW are better predictive of engraftment after autologous and allogeneic HSCT. Sixty-three patients undergoing reduced-intensity HSCT after a uniform preparative regimen were evaluated to determine the effect of cell dose. ABW and IBW were 45-147 kg (median 79) and 52-85 kg (median 67) respectively. The ABW-IBW difference was -24% to +133% (median +16%); nine patients were >5% underweight and 41 were >5% overweight. The CD34+ cell dose (10(6)/kg) was 1.4-11.8 (median 5) by IBW and 1.2-9.3 (median 4.5) by ABW. The CD3+ cell dose (10(8)/kg) was 0.9-14.9 (median 3) by IBW and 0.7-19.7 (median 2.7) by ABW. While CD34+ and CD3+ cell doses based upon IBW were found to affect transplant-related mortality, and disease-free and overall survival significantly, those based on ABW were either not predictive of outcome or the differences were of borderline significance. We suggest using IBW rather than ABW to calculate cell doses for HSCT; for statistical analyses and for clinical practice if a specific cell dose is being targeted.

  16. Ideal or actual body weight to calculate CD34+ cell doses for allogeneic hematopoietic stem cell transplantation?

    PubMed

    Cilley, J; Rihn, C; Monreal, J; Gordon, L I; Singhal, S; Tallman, M; Williams, S; Winter, J; Mehta, J

    2004-01-01

    The number of CD34+ cells infused influences hematologic recovery after transplantation. Limited data suggest that cell dose should be based on ideal (IBW) rather than actual (ABW) body weight for autotransplantation, but none in allografts. We compared the correlation between recovery to 0.5 x 10(9)/l neutrophils and the CD34+ cell dose based upon ABW and IBW in 78 allograft recipients. ABW was > or =25% over IBW in 47% of patients. The median CD34+ cell dose was 5.1 x 10(6)/kg IBW and 4.4 x 10(6)/kg ABW. The time to neutrophil recovery was 8-26 days (median 12). There was a stronger inverse correlation between CD34+ cell dose/IBW and neutrophil recovery (r(2)=0.160; P<0.0001) than between CD34+ cell dose/ABW and neutrophil recovery (r(2)=0.138; P=0.001). When neutrophil recovery in patients receiving <3 or <5 x 10(6) CD34+ cells/kg was compared to those receiving > or =3 or > or =5 x 10(6) CD34+ cells/kg, respectively, separately by IBW and ABW, the magnitude and significance of the differences were greater for IBW-based comparisons. These data suggest the CD34+ cell dose based on IBW is a better predictor of neutrophil recovery after allografting. Further work in a larger, more homogeneous group of patients is required to confirm this observation.

  17. Estimation of breast dose reduction potential for organ-based tube current modulated CT with wide dose reduction arc

    NASA Astrophysics Data System (ADS)

    Fu, Wanyi; Sturgeon, Gregory M.; Agasthya, Greeshma; Segars, W. Paul; Kapadia, Anuj J.; Samei, Ehsan

    2017-03-01

    This study aimed to estimate the organ dose reduction potential for organ-dose-based tube current modulated (ODM) thoracic CT with wide dose reduction arc. Twenty-one computational anthropomorphic phantoms (XCAT, age range: 27- 75 years, weight range: 52.0-105.8 kg) were used to create a virtual patient population with clinical anatomic variations. For each phantom, two breast tissue compositions were simulated: 50/50 and 20/80 (glandular-to-adipose ratio). A validated Monte Carlo program was used to estimate the organ dose for standard tube current modulation (TCM) (SmartmA, GE Healthcare) and ODM (GE Healthcare) for a commercial CT scanner (Revolution, GE Healthcare) with explicitly modeled tube current modulation profile, scanner geometry, bowtie filtration, and source spectrum. Organ dose was determined using a typical clinical thoracic CT protocol. Both organ dose and CTDIvol-to-organ dose conversion coefficients (h factors) were compared between TCM and ODM. ODM significantly reduced all radiosensitive organ doses (p<0.01). The breast dose was reduced by 30+/-2%. For h factors, organs in the anterior region (e.g. thyroid, stomach) exhibited substantial decreases, and the medial, distributed, and posterior region either saw an increase or no significant change. The organ-dose-based tube current modulation significantly reduced organ doses especially for radiosensitive superficial anterior organs such as the breasts.

  18. Radiation biodosimetry: applications for spaceflight

    NASA Astrophysics Data System (ADS)

    Blakely, W.; Miller, A.; Grace, M.; Prasanna, P.; Muderhwa, J.

    The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a dose assessment software application, a portable blood cell counter, and molecular biodosimetry using miniaturized equipment. The Biodosimetry Assessment Tool (BAT) software application calculates radiation dose based on a patient's physical signs and symptoms and blood analysis, annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. The dry reagent centrifuge-based blood cell counter (QBC Autoread Plus, Beckon Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins), once dose-dependent targets are identified, optimized, and validated, will make use of miniaturized diagnostic equipment for nucleic acid sequence and antigen-based biosensor detection technologies. These radiation assessment diagnostic technologies can have dual use for other medical related applications. [The Armed Forces Radiobiology Research Institute, under work unit AFRRI-01-3, and the Defense Threat Reduction Agency, under contract GG4661, supported this research.

  19. Feasibility, efficacy, and safety of a simple insulin infusion protocol in a large volume cardiac surgery unit in India.

    PubMed

    Bansal, Beena; Mithal, Ambrish; Carvalho, Pravin; Mehta, Yatin; Trehan, Naresh

    2015-01-01

    Inpatient hyperglycemia management is essential, but difficult to achieve especially in a large volume cardiac surgery setup, thus necessitating use of nurse-led insulin protocols. A rapid flux of nurses dealing with a huge workload has been a cause for traditionally not using nurse-led protocols in most Indian institutes. The challenges we faced were to have a simple protocol for the nurses to accept it without compromising on glycemic control. Therefore, this observational study was planned to measure the efficacy and safety of the insulin infusion protocol in cardiac surgery patients. Insulin protocol was implemented, using seven fixed columns of infusion with the nurse making decisions to initiate and titrate doses based on simple rules. Blood glucose (BG) data captured from blood gas analyzers (glucometrics) in the intervention group (i.e., after protocol implementation) were compared to control group (i.e., before the protocol implementation). The mean BG for the first 48 h was lower in the intervention group as compared to control group, without an increase in the episodes of hypoglycemia. The nurses found the protocol easy to understand, less time-consuming and there was no protocol deviation over 8 months after implementation. A small change in the process, allowing nurses to titrate insulin doses based on some rules and having seven fixed columns of insulin infusion rates, improved glycemic control and efficiency.

  20. Final Report of a CRADA Between Pacific Northwest National Laboratory and Cummins, Incorporated (CRADA No.PNNL/283): “Enhanced High and Low Temperature Performance of NOx Reduction Catalyst Materials”

    SciTech Connect

    Gao, Feng; Szanyi, Janos; Wang, Yilin; Wang, Yong; Peden, Charles HF; Howden, Ken; Currier, Neal; Kamasamudram, Krishna; Kumar, Ashok; Li, J.; Stafford, R. J.; Yezerets, Aleksey; Luo, J.; Chen, H. Y.

    2016-09-01

    The NOx Storage-Reduction (NSR, also known as lean-NOx trap – LNT), is based upon the concept of storing NOx as nitrates over storage components, typically barium species, during a lean-burn operation cycle and then reducing the stored nitrates to N2 during fuel-rich conditions over a precious metal catalyst [1]. NOx Selective Catalytic Reduction (SCR), on the other hand, is accomplished by deliberately introducing reductant urea into the engine exhaust to reduce NOx with the aid of a Cu(Fe)/zeolite catalyst [2]. These two technologies have been recognized as the most promising approaches for meeting stringent NOx emission standards for diesel vehicles within the Environmental Protection Agency’s (EPA’s) 2007/2010 mandated limits. For NSR, problems arising from either or both thermal and SO2 deactivation must be addressed to meet durability standards. For SCR, SO2 deactivation is less of an issue, but hydrothermal deactivation of the zeolite catalysts must be addressed. With continuing R&D efforts in advanced powertrains, highly novel operating modes for internal combustion engines (ICEs) are being researched in order to meet the very stringent new demands for fuel efficiency (e.g., U.S. ‘‘CAFE’’ standards for average miles/gallon are scheduled to increase dramatically over the next 10–15 years). These new ICE engine operation modes, while highly fuel-efficient, result in much lower exhaust temperatures than current engines; temperatures so low that it is hard to imagine how the current catalytic emission control technologies will be able to function. For example, while steady-state operation of the NOx reduction technology at 150 °C may be required, current ‘‘light-off’’ temperatures for CHA-based zeolite catalysts are closer to 200 °C. Therefore, understanding low-temperature limitations in NOx reduction has become one

  1. B-site substitutions in LaNb{sub 1-x}M{sub x}O{sub 4-{delta}} materials in the search for potential proton conductors (M=Ga, Ge, Si, B, Ti, Zr, P, Al)

    SciTech Connect

    Brandao, A.D.; Gracio, J.; Mather, G.C.; Kharton, V.V.; Fagg, D.P.

    2011-04-15

    The solid solubilities of potential B-site dopants in LaNb{sub 1-x}M{sub x}O{sub 4-{delta},} materials, M=Ga, Ge, Si, Al, B, P, Zr or Ti, have been investigated in the search for possible novel proton conductors. In general, the solubility levels of these cations were found to be very low (x{<=}0.03). At the maximum value x=0.03, only compositions containing Ti, Ge, Ga and Si appeared pure at the limit of resolution of XRD. The literature phase diagram, La{sub 2}O{sub 3}-Nb{sub 2}O{sub 5}-ZrO{sub 2}, has been re-analysed for compositions of low Zr-content around the composition LaNbO{sub 4}. The electrical properties of phase pure Ti-doped compositions have been studied. Higher bulk and total conductivities were observed in wet than dry conditions, suggesting a significant protonic contribution to total conductivity. In wet conditions, the activation energy for bulk conductivity of LaNb{sub 0.98}Ti{sub 0.02}O{sub 4-{delta}} was found to be much higher than that of an A-site, Sr-doped material, Sr{sub 0.02}La{sub 0.98}NbO{sub 4-{delta},} of similar acceptor dopant concentration. The Sr-doped composition offered higher conductivities than the Ti-doped composition up to approximately 900{sup o}C. -- Graphical abstract: Comparison of total (open symbols) and bulk (closed symbols) conductivities measured in wet (p(H{sub 2}O){approx}0.026 atm.) nitrogen and oxygen atmospheres for LaNb{sub 0.98}Ti{sub 0.02}O{sub 4-{delta}} (LNT2O) and Sr{sub 0.02}La{sub 0.98}NbO{sub 4-{delta}} (S2LNO) materials. Display Omitted Research highlights: {yields} The article investigates solid solubilities of potential B-site dopants in the potential proton conductor LaNb{sub 1-x}M{sub x}O{sub 4-{delta},} {yields} The literature phase diagram, La{sub 2}O{sub 3}-Nb{sub 2}O{sub 5}-ZrO{sub 2}, has been corrected for compositions of low Zr-content around the composition LaNbO{sub 4}. {yields} The electrical properties of Ti-doped compositions have been assessed in wet and dry conditions. {yields

  2. [Accuracy of procalcitonin for diagnosis of sepsis in adults: a Meta-analysis].

    PubMed

    Chengfen, Yin; Tong, Li; Xinjing, Gao; Zhibo, Li; Lei, Xu

    2015-09-01

    To assess the clinical value of procalcitonin (PCT ) in the diagnosis of sepsis in adults. An extensive search for related literature from the Wanfang data, CNKI, VIP, Medline/PubMed, Embase/OvidSP and the Cochrane Library up to December 2014 was performed. The articles, including prospective observational studies or randomized controlled trials, regarding PCT for the diagnosing of sepsis were enrolled. Only patients older than 18 years were included. Patients with sepsis, severe sepsis, or septic shock served as the experimental group, and those with a systemic inflammatory response syndrome (SIRS) of non-infectious origin as control group. The language of literature included was English or Chinese. The quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Heterogeneity, pooled diagnostic odds ratio (DOR), pooled sensitivity, pooled specificity, pooled positive likelihood ratio, pooled negative likelihood ratio, the area under the summary receiver operating characteristic curve (SROC) and subgroup analysis were analyzed with the software of Metadisc 1.4. A total of 6 385 published reports were collected, and among them 24 met the inclusion criteria, including a total. of 3 107 patients. The studies showed substantial heterogeneity (I2 = 69.4%), and random effect model was used for Meta analysis, showing that the pooled DOR was 10.37 [95% confidence interval (95%CI) = 7.10-15.17]. No evidence of a threshold effect was found (Spearman correlation coefficient = 0.27, calculated by logarithm of sensitivity and logarithm of 1-specificity, P = 0.20). The DOR values of pooled and each study were not distributed along the same line in forest plots, and Cochran-Q = 78.33, P = 0.000 0, showing that there was heterogeneity in result from non threshold effect. Except for partial heterogeneity caused by non threshold effect, the result of Meta regression analysis including PCT detection method, categories of disease

  3. Dynamics of Cellular Responses to Radiation

    PubMed Central

    Wodarz, Dominik; Sorace, Ron; Komarova, Natalia L.

    2014-01-01

    Understanding the consequences of exposure to low dose ionizing radiation is an important public health concern. While the risk of low dose radiation has been estimated by extrapolation from data at higher doses according to the linear non-threshold model, it has become clear that cellular responses can be very different at low compared to high radiation doses. Important phenomena in this respect include radioadaptive responses as well as low-dose hyper-radiosensitivity (HRS) and increased radioresistance (IRR). With radioadaptive responses, low dose exposure can protect against subsequent challenges, and two mechanisms have been suggested: an intracellular mechanism, inducing cellular changes as a result of the priming radiation, and induction of a protected state by inter-cellular communication. We use mathematical models to examine the effect of these mechanisms on cellular responses to low dose radiation. We find that the intracellular mechanism can account for the occurrence of radioadaptive responses. Interestingly, the same mechanism can also explain the existence of the HRS and IRR phenomena, and successfully describe experimentally observed dose-response relationships for a variety of cell types. This indicates that different, seemingly unrelated, low dose phenomena might be connected and driven by common core processes. With respect to the inter-cellular communication mechanism, we find that it can also account for the occurrence of radioadaptive responses, indicating redundancy in this respect. The model, however, also suggests that the communication mechanism can be vital for the long term survival of cell populations that are continuously exposed to relatively low levels of radiation, which cannot be achieved with the intracellular mechanism in our model. Experimental tests to address our model predictions are proposed. PMID:24722167

  4. [New drinking water reference values for monocyclic nitro compounds].

    PubMed

    Wollin, K-M; Dieter, H H

    2005-11-01

    Nitro compounds are important industrial chemicals with a broad range of applications. During their commercial production or practical use and through leaching from military waste sites they may be released into the environment and thus lead to a contamination of drinking water resources. In the last 15-20 years, the wider public first became aware of nitro compounds as contaminants in groundwater and drinking water resources that originated from manufacturing and processing of secondary explosives during World War II. In 1980, the former Bundesgesundheitsamt (BGA; Federal Health Office) had based its first risk assessment of monocyclic nitro compounds in drinking water on the known carcinogenicity of some aromatic amines in the working environment. On this basis, the BGA recommended for metabolites of aromatic nitro compounds a guide value of 0.1 mug/l for the sum of aromatic amines. From the beginning to the middle of the 1990s, the BGA established a more specific health-related assessment for the individual compounds, but not on the basis of tolerable or acceptable body doses but of dimensionless risk assessment scores ranking their combined toxic and carcinogenic potential on a scale from 1 to 100. In this contribution, we derived new health-based drinking water guide values for 19 nitro(aromatic) compounds and nitramines, including hexogen, octogen, and tetryl as well as the O-nitro compound PETN. All compounds under consideration have been detected within the last 15 years in Germany at contaminated sites close to or directly in groundwater resources for drinking water. For toxicological evaluation and derivation of guideline values for the nitro compounds of interest, the tolerable daily intake (TDI) approach was used for chemicals exhibiting a threshold for toxic effects. This was done by using established tolerable body doses for humans based on an identified NOAEL/LOAEL for the most sensitive toxic endpoint. In the case of non-threshold chemical

  5. Important considerations in the development of public health advisories for arsenic and arsenic-containing compounds in drinking water.

    PubMed

    Tchounwou, P B; Wilson, B; Ishaque, A

    1999-01-01

    Drinking water contamination by arsenic remains a major public health problem. Acute and chronic arsenic exposure via drinking water has been reported in many countries of the world; especially in Argentina, Bangladesh, India, Mexico, Thailand, and Taiwan, where a large proportion of drinking water (ground water) is contaminated with a high concentration of arsenic. Research has also pointed out significantly higher standardized mortality ratios and cumulative mortality rates for cancers of the bladder, kidney, skin, liver, and colon in many areas of arsenic pollution. General health effects that are associated with arsenic exposure include cardiovascular and peripheral vascular disease, developmental anomalies, neurologic and neurobehavioral disorders, diabetes, hearing loss, portal fibrosis of the liver, lung fibrosis, hematologic disorders (anemia, leukopenia, and eosinophilia), and carcinoma. Although, the clinical manifestations of arsenic poisoning appear similar, the toxicity of arsenic compounds depends largely u[on the chemical species and the form of arsenic involved. On the basis of its high degree of toxicity to humans, and the non-threshold dose-response assumption, a zero level exposure is recommended for arsenic, even though this level is practically non-attainable. In this review, we provide and discuss important information on the physical and chemical properties, production and use, fate and transport, toxicokinetics, systemic and carcinogenic health effects, regulatory and health guidelines, analytical methods, and treatment technologies that are applied to arsenic pollution. Such information is critical in assisting the federal, state and local officials who are responsible for protecting public health in dealing with the problem of drinking water contamination by arsenic and arsenic-containing compounds.

  6. Neutron flux and spectrum characterization in the University of Illinois TRIGA

    SciTech Connect

    Peach, R.O.; Williams, J.G.; Ougouag, A.M.

    1988-07-01

    The principal irradiation facilities at the University of Illinois TRIGA are a central thimble, a pneumatic 'rabbit' tube in the G-hexagon, a forty- position Lazy Susan facility in the reflector, a through-port passing tangentially through the reflector, and a recently installed rotating tube in a three-element cluster position in the F- and G-hexagons. These facilities are used primarily for thermal and epithermal neutron activation, and for radiation damage studies in semiconductor and other materials. Thermal and epithermal neutron fluence rates have recently been measured by means of radiometric monitors in all the core and reflector facilities at a variety of reactor power levels. In addition, the fast neutron fluences have been characterized by means of threshold and non-threshold activation reaction rates measured in those positions used for radiation damage studies. Unfolding of neutron spectra from the measured reaction rates was done by means of the code LSL-M2, which was made available in 1986 from the Radiation Shielding Information Center. This code uses the generalized least squares method and incorporates a full propagation of uncertainties due to errors in measured reaction rates, cross section data, and input neutron spectra. The input spectra, needed in LSL-M2, were taken from the General Atomic report GA4361 which includes 24-group spectra, calculated by the code GAZE, for the center of the core, the F-hexagon and the Lazy Susan. These positions, and some of the material and geometrical specifications, do not correspond exactly with the actual ones at the University of Illinois TRIGA, but the differences in the neutron spectra were found to be small. The unfolded neutron spectra may be used to obtain fast neutron spectrum parameters needed in radiation damage studies and hardness testing. For example, the 1-MeV equivalent fluence rates for displacement damage in silicon, calculated according to the ASTM Standard E722, are reported. (author)

  7. Risk assessment of ochratoxin: current views of the European Scientific Committee on Food, the JECFA and the Codex Committee on Food Additives and Contaminants.

    PubMed

    Walker, Ron

    2002-01-01

    The chlorinated isocoumarin compound, ochratoxin A (OTA), together with some related derivatives (ochratoxins B, C, alpha, beta) are produced by Penicillium verrucosum and by several spp. of Aspergillus, most notably A. ochraceus. P. verrucosum is the principal source of OTA contamination of stored foods in temperate climates while Aspergillus spp. predominate in warmer countries. The major dietary sources of OTA are cereals but significant levels of contamination may be found in grape juice and red wine, coffee, cocoa, nuts, spices and dried fruits. Because of the chemical stability of OTA and long half-life in mammalian tissues, contamination may also carry over into pork and pig blood products and into beer. OTA is potently nephrotoxic and carcinogenic, the potency varying markedly between species and sexes; it is also teratogenic and immunotoxic. There have been different approaches to the risk assessment of OTA in different jurisdictions, largely arising from whether or not the carcinogenicity of OTA is considered to arise through a thresholded or non-thresholded mechanism. Consequently the tolerable intakes have variously been estimated at 100 ng/kg bw/week (JECFA), 1.5 to 5.7 ng/kg bw/day (Canada) and not more than 5 ng/kg bw/day (European Commission). These differences are also reflected in risk management measures that have been implemented or proposed with different maximum contamination levels being applied to different commodities and to the same commodity in different countries. Prevention of contamination at source is considered to be the most effective public health measure. There is also a need to harmonise the risk assessment and management processes to a greater extent than currently exist if barriers to trade are to be avoided.

  8. Benzene and its methyl-derivatives: derivation of maximum exposure levels in automobiles.

    PubMed

    Schupp, Thomas; Bolt, Hermann M; Jaeckh, Rudolf; Hengstler, Jan G

    2006-01-05

    Automobile drivers are exposed to several organic hydrocarbons. Concentrations measured in passenger compartments have been reported to range between 13 and 560 microg/m(3) for benzene, 33-258 microg/m(3) for toluene, 20-250 microg/m(3) for xylene (mixed isomers) and 3-23 microg/m(3) for trimethylbenzene (mixed isomers). These aromatic hydrocarbons are emitted from gasoline and from materials inside a car. In the present study we evaluated, whether these exposures pose a potential risk to the health of drivers. Therefore, we derived maximum exposure levels inside cars for chronic (ELIA(chronic)) and short-term (STELIA) exposure. The lowest ELIA's(chronic) for benzene, toluene, xylene and trimethylbenzene were 0.083, 1.2, 8.8 and 0.31 mg/m(3), respectively. The respective STELIA's were 16, 30, 29 and 25 mg/m(3). Obviously concentrations of toluene, xylene and trimethylbenzene inside cars do not exceed their individual STELIA's. In contrast, benzene seems to be problematic, since concentrations inside cars amount up to 0.56 mg/m(3), which exceeds the ELIA(chronic) derived for benzene. This should not be underestimated, since benzene is a genotoxic carcinogen that probably acts by non-threshold mechanisms. In conclusion, concentrations of toluene, xylene and trimethylbenzene usually observed inside cars are unlikely to pose a risk to the health of drivers. A systematic toxicological evaluation of the risk associated with benzene exposure in cars seems to be necessary.

  9. Arsenic accumulation in native plants of West Bengal, India: prospects for phytoremediation but concerns with the use of medicinal plants.

    PubMed

    Tripathi, Preeti; Dwivedi, Sanjay; Mishra, Aradhana; Kumar, Amit; Dave, Richa; Srivastava, Sudhakar; Shukla, Mridul Kumar; Srivastava, Pankaj Kumar; Chakrabarty, Debasis; Trivedi, Prabodh Kumar; Tripathi, Rudra Deo

    2012-05-01

    Arsenic (As) is a widespread environmental and food chain contaminant and class I, non-threshold carcinogen. Plants accumulate As due to ionic mimicry that is of importance as a measure of phytoremediation but of concern due to the use of plants in alternative medicine. The present study investigated As accumulation in native plants including some medicinal plants, from three districts [Chinsurah (Hoogly), Porbosthali (Bardhman), and Birnagar (Nadia)] of West Bengal, India, having a history of As pollution. A site-specific response was observed for Specific Arsenic Uptake (SAU; mg kg(-1) dw) in total number of 13 (8 aquatic and 5 terrestrial) collected plants. SAU was higher in aquatic plants (5-60 mg kg(-1) dw) than in terrestrial species (4-19 mg kg(-1) dw). The level of As was lower in medicinal plants (MPs) than in non-medicinal plants, however it was still beyond the WHO permissible limit (1 mg kg(-1) dw). The concentration of other elements (Cu, Zn, Se, and Pb) was found to be within prescribed limits in medicinal plants (MP). Among the aquatic plants, Marsilea showed the highest SAU (avg. 45 mg kg(-1) dw), however, transfer factor (TF) of As was the maximum in Centella asiatica (MP, avg. 1). Among the terrestrial plants, the maximum SAU and TF were demonstrated by Alternanthera ficoidea (avg. 15) and Phyllanthus amarus (MP, avg. 1.27), respectively. In conclusion, the direct use of MP or their by products for humans should not be practiced without proper regulation. In other way, one fern species (Marsilea) and some aquatic plants (Eichhornia crassipes and Cyperus difformis) might be suitable candidates for As phytoremediation of paddy fields.

  10. Genotoxicity assessment of 4-methylimidazole: regulatory perspectives.

    PubMed

    Morita, Takeshi; Uneyama, Chikako

    2016-01-01

    4-Methylimidazole (4-MI) is formed as a result of the Maillard reaction process, and therefore is found in many foods and beverages. It is also found in soft drinks (i.e., cola) as a by-product in the production of some caramel colors. NTP bioassays revealed clear evidence of lung carcinogenicity of 4-MI in male and female mice, but not in rats and then IARC classified 4-MI as group 2B carcinogen. Genotoxicity studies with 4-MI were negative in the Ames tests and in the erythrocyte micronucleus tests with mice or rats. US California EPA (CEPA) evaluated the testing has not been adequately comprehensive to rule out a genotoxic mode of action; as target tissue of the carcinogenicity of 4-MI was lung, the lung should be used as a source tissue for in vitro metabolic activation system. Thus, CEPA defined the No Significant Risk Level (NSRL) for 10(-5) lifetime risk level of cancer by 4-MI as 29 μg/day based on the non-threshold approach. As higher levels of 4-MI than the NSRL were identified in some kinds of cola, health concerns of 4-MI were drawn the attention. On the other hand, other regulatory bodies (e.g., European Food Safety Authority, EFSA) showed no concerns of 4-MI from the use of caramel colors in food. EFSA evaluated 4-MI is not genotoxic, so, non-observed adverse effect level of 4-MI was considered to be 80 mg/kg/day. In this paper, genotoxic assessments of 4-MI in different regulatory bodies are presented and the risk evaluation of 4-MI is discussed based on new genotoxicity data.

  11. Limited English proficient Asian Americans: Threshold language policy and access to mental health treatment.

    PubMed

    Snowden, Lonnie R; Masland, Mary C; Peng, Carol J; Wei-Mien Lou, Christine; Wallace, Neal T

    2011-01-01

    The importance of providing timely, effective mental health services is increasingly recognized worldwide, and language barriers are a formidable obstacle to achieving this objective. Threshold language policy is one response implemented by California and other states within the U.S., in accordance with Title VI of the Civil Rights Act of 1964, which prohibits discrimination on the basis of race, color, and national origin in programs receiving federal funding. This policy mandates language assistance services for Medicaid enrollees whose primary language is other than English once their population size reaches a designated level. Medicaid is the federal-state-funded health insurance program for specific classifications of low-income Americans. This study evaluated the impact of threshold language policy on Vietnamese, Cantonese, Hmong, and Cambodian limited English proficiency persons' use of public mental health services in California. Using random-effects regression on 247 observations, we regressed aggregate Vietnamese, Cantonese, Hmong, and Cambodian Medicaid mental health service penetration rates on an indicator of the threshold language policy's implementation, while controlling for a linear time trend and the effects of non-threshold language assistance programming. Immediately after implementation, threshold language policy requirements were associated with a penetration rate increase among this population. The penetration rate increase became greater after accounting for the impact of concurrent language assistance. However, this increase diminished over time. The findings indicate that, at least in the short run, language assistance measures requiring reasonable accommodations once populations of LEP persons reach a specified size have detectable effects on their mental health service use. These requirements increase the number of mental health consumers, but appear to provide declining benefit over time. California's threshold language policy provides

  12. Urine interleukin-18 in prediction of acute kidney injury: a systemic review and meta-analysis.

    PubMed

    Lin, Xin; Yuan, Jing; Zhao, Yingting; Zha, Yan

    2015-02-01

    Interleukin-18 (IL-18) mediates ischemic acute tubular necrosis; it has been proved as a rapid, reliable, and affordable test marker for the early detection of acute kidney injury (AKI), but its predictive accuracy varies greatly. MEDLINE and EMBASE, Cochrane Library, Ovid, and Springerlink (from inception to November 15, 2013) were searched for relevant studies (in English) investigating diagnostic accuracy of urine IL-18 to predict AKI in various clinical settings. The text index was increasing or increased urine IL-18 level and the main outcome was the development of AKI, which was primarily based on serum creatinine level [using risk, injury, failure, loss and end-stage renal disease (RIFLE), acute kidney injury network, or modified pediatric RIFLE criteria in pediatric patients]. Pooled estimates of diagnostic odds ratio (OR), sensitivity and specificity were calculated. Summary receiver operating characteristic curves were used to calculate the measures of accuracy and Q point value (Q*). Remarkable heterogeneity was explored further by subgroup analysis based on the different clinical settings. We analyzed data from 11 studies of 3 countries covering 2,796 patients. These studies were marked by limitations of threshold and non-threshold effect heterogeneity. Across all settings, the diagnostic OR for urine IL-18 level to predict AKI was 5.11 [95% confidence interval (CI) 3.22-8.12], with sensitivity and specificity respectively at 0.51 and 0.79. The area under the ROC curve of urine IL-18 level to predict AKI was 0.77 (95% CI 0.71-0.83). Subgroup analysis showed that urine IL-18 level in pediatric patients (<18 years) and early AKI predictive time (<12 h) were more effective in predicting AKI, with diagnostic ORs of 7.51 (2.99-18.88), 8.18 (2.19-30.51), respectively. Urine IL-18 holds promise as a biomarker in the prediction of AKI but has only moderate diagnostic value.

  13. Classification of radiation effects for dose limitation purposes: history, current situation and future prospects.

    PubMed

    Hamada, Nobuyuki; Fujimichi, Yuki

    2014-07-01

    Radiation exposure causes cancer and non-cancer health effects, each of which differs greatly in the shape of the dose-response curve, latency, persistency, recurrence, curability, fatality and impact on quality of life. In recent decades, for dose limitation purposes, the International Commission on Radiological Protection has divided such diverse effects into tissue reactions (formerly termed non-stochastic and deterministic effects) and stochastic effects. On the one hand, effective dose limits aim to reduce the risks of stochastic effects (cancer/heritable effects) and are based on the detriment-adjusted nominal risk coefficients, assuming a linear-non-threshold dose response and a dose and dose rate effectiveness factor of 2. On the other hand, equivalent dose limits aim to avoid tissue reactions (vision-impairing cataracts and cosmetically unacceptable non-cancer skin changes) and are based on a threshold dose. However, the boundary between these two categories is becoming vague. Thus, we review the changes in radiation effect classification, dose limitation concepts, and the definition of detriment and threshold. Then, the current situation is overviewed focusing on (i) stochastic effects with a threshold, (ii) tissue reactions without a threshold, (iii) target organs/tissues for circulatory disease, (iv) dose levels for limitation of cancer risks vs prevention of non-life-threatening tissue reactions vs prevention of life-threatening tissue reactions, (v) mortality or incidence of thyroid cancer, and (vi) the detriment for tissue reactions. For future discussion, one approach is suggested that classifies radiation effects according to whether effects are life threatening, and radiobiological research needs are also briefly discussed.

  14. Potential health impacts of residential exposures to extremely low frequency magnetic fields in Europe.

    PubMed

    Grellier, James; Ravazzani, Paolo; Cardis, Elisabeth

    2014-01-01

    Over the last two decades residential exposure to extremely low frequency magnetic fields (ELF MF) has been associated with childhood leukaemia relatively consistently in epidemiological studies, though causality is still under investigation. We aimed to estimate the cases of childhood leukaemia that might be attributable to exposure to ELF MF in the European Union (EU27), if the associations seen in epidemiological studies were causal. We estimated distributions of ELF MF exposure using studies identified in the existing literature. Individual distributions of exposure were integrated using a probabilistic mixture distribution approach. Exposure-response functions were estimated from the most recently published pooled analysis of epidemiological data. Probabilistic simulation was used to estimate population attributable fractions (AFP) and attributable cases of childhood leukaemia in the EU27. By assigning the literature review-based exposure distribution to all EU27 countries, we estimated the total annual number of cases of leukaemia attributable to ELF MF at between ~50 (95% CIs: -14, 132) and ~60 (95% CIs: -9, 610), depending on whether exposure-response was modelled categorically or continuously, respectively, for a non-threshold effect. This corresponds to between ~1.5% and ~2.0% of all incident cases of childhood leukaemia occurring annually in the EU27. Considerable uncertainties are due to scarce data on exposure and the choice of exposure-response model, demonstrating the importance of further research into better understanding mechanisms of the potential association between ELF MF exposure and childhood leukaemia and the need for improved monitoring of residential exposures to ELF MF in Europe.

  15. Community health risk assessment after a fire with asbestos containing fallout

    PubMed Central

    Bridgman, S

    2001-01-01

    BACKGROUND—A factory fire in Tranmere, Merseyside, England, deposited asbestos containing fallout in an urban area. There was considerable community anxiety for months after the incident. Therefore an assessment of the long term health risks of this acute environmental incident were requested by the local health authority.
METHODS—The facts of the incident were gathered and appraised from unpublished and press reports, involved personnel, and further analysis of material collected at the time of the incident. The literature on the long term health risks of asbestos was reviewed, and combined with evidence on asbestos exposure to estimate community health risk.
RESULTS—Risk was almost entirely from exposure to fire fallout of chrysotile in asbestos bitumen paper covering the factory roof. Amosite was only detected in a few samples and in trace amounts. The number of people who lived in the area of fallout was 16 000 to 48 000. From a non-threshold model with assumptions likely to overestimate risk, the lung cancer risk is estimated to be undetectably small. Risk of mesothelioma from chrysotile exposure, and risks of lung cancer and mesothelioma from amosite exposure were based on observational studies and were estimated to be even lower than that of lung cancer risk from chrysotile exposure. Academically, there are assumptions that while reasonable cannot be proven, for example, the validity of extrapolating observed risk from much higher exposures to lower exposures, estimates of individual exposure, and that there is no threshold for asbestos to cause cancer.
CONCLUSIONS—The author is unaware of a similar study on long term health risks in a community exposed to asbestos in a fire. It is concluded that, using methods that do not underestimate risk, risk is undetectably small. Practical lessons from this methodology and approach to health risk assessment are discussed.


Keywords: asbestos; environmental pollutants; mesothelioma; health risk

  16. Classification of radiation effects for dose limitation purposes: history, current situation and future prospects

    PubMed Central

    Hamada, Nobuyuki; Fujimichi, Yuki

    2014-01-01

    Radiation exposure causes cancer and non-cancer health effects, each of which differs greatly in the shape of the dose–response curve, latency, persistency, recurrence, curability, fatality and impact on quality of life. In recent decades, for dose limitation purposes, the International Commission on Radiological Protection has divided such diverse effects into tissue reactions (formerly termed non-stochastic and deterministic effects) and stochastic effects. On the one hand, effective dose limits aim to reduce the risks of stochastic effects (cancer/heritable effects) and are based on the detriment-adjusted nominal risk coefficients, assuming a linear-non-threshold dose response and a dose and dose rate effectiveness factor of 2. On the other hand, equivalent dose limits aim to avoid tissue reactions (vision-impairing cataracts and cosmetically unacceptable non-cancer skin changes) and are based on a threshold dose. However, the boundary between these two categories is becoming vague. Thus, we review the changes in radiation effect classification, dose limitation concepts, and the definition of detriment and threshold. Then, the current situation is overviewed focusing on (i) stochastic effects with a threshold, (ii) tissue reactions without a threshold, (iii) target organs/tissues for circulatory disease, (iv) dose levels for limitation of cancer risks vs prevention of non-life-threatening tissue reactions vs prevention of life-threatening tissue reactions, (v) mortality or incidence of thyroid cancer, and (vi) the detriment for tissue reactions. For future discussion, one approach is suggested that classifies radiation effects according to whether effects are life threatening, and radiobiological research needs are also briefly discussed. PMID:24794798

  17. Linear low-dose extrapolation for noncancer health effects is the exception, not the rule

    PubMed Central

    Rhomberg, Lorenz R; Goodman, Julie E; Haber, Lynne T; Dourson, Michael; Andersen, Melvin E; Klaunig, James E; Meek, Bette; Price, Paul S; McClellan, Roger O; Cohen, Samuel M

    2011-01-01

    The nature of the exposure-response relationship has a profound influence on risk analyses. Several arguments have been proffered as to why all exposure-response relationships for both cancer and noncarcinogenic end-points should be assumed to be linear at low doses. We focused on three arguments that have been put forth for noncarcinogens. First, the general “additivity-to-background” argument proposes that if an agent enhances an already existing disease-causing process, then even small exposures increase disease incidence in a linear manner. This only holds if it is related to a specific mode of action that has nonuniversal properties—properties that would not be expected for most noncancer effects. Second, the “heterogeneity in the population” argument states that variations in sensitivity among members ofthe target population tend to “flatten out and linearize” the exposure-response curve, but this actually only tends to broaden, not linearize, the dose-response relationship. Third, it has been argued that a review of epidemiological evidence shows linear or no-threshold effects at low exposures in humans, despite nonlinear exposure-response in the experimental dose range in animal testing for similar endpoints. It is more likely that this is attributable to exposure measurement error rather than a true non-threshold association. Assuming that every chemical is toxic at high exposures and linear at low exposures does not comport to modern-day scientific knowledge of biology. There is no compelling evidence-based justification for a general low-exposure linearity; rather, case-specific mechanistic arguments are needed. PMID:21226629

  18. Use of a dose-dependent follow-up protocol and mechanisms to reduce patients and staff radiation exposure in congenital and structural interventions.

    PubMed

    Sawdy, Jaclynn M; Kempton, Tanya Maria; Olshove, Vincent; Gocha, Mark; Chisolm, Joanne L; Hill, Sharon L; Kirk, Amy; Cheatham, John P; Holzer, Ralf J

    2011-07-01

    Increasingly complex structural/congenital cardiac interventions require efforts at reducing patient/staff radiation exposure. Standard follow-up protocols are often inadequate in detecting all patients that may have sustained radiation burns. Single-center retrospective chart review divided into four intervals. Phase 1 (07/07-06/08, 413 procedures (proc)): follow-up based on fluoroscopy time only; frame rate for digital acquisition (DA) 30 fps, and fluoroscopy (FL) 30 fps. Dose-based follow-up was used for phase 2-4. Phase 2 (07/08-08/09, 458 proc): DA: 30 fps, FL: 15 fps. Phase 3 (09/09-06/10, 350 proc): DA: 15-30 fps, FL: 15 fps, use of added radiation protection drape. Phase 4 (07/10-10/10, 89 proc): DA: 15-30 fps, FL: 15 fps, superior noise reduction filter (SNRF) with high-quality fluoro-record capabilities. There was a significant reduction in the median cumulative air kerma between the four study periods (710 mGy vs. 566 mGy vs. 498 mGy vs. 241 mGy, P < 0.001), even though the overall fluoroscopy times remained very similar (25 min vs. 26 min vs. 26 min vs. 23 min, P = 0.957). There was a trend towards lower physician radiation exposure over the four study periods (137 mrem vs. 126 mrem vs. 108 mrem vs. 59 mrem, P = 0.15). Fifteen patients with radiation burns were identified during the study period. When changing to a dose-based follow-up protocol (phase 1 vs. phase 2), there was a significant increase in the incidence of detected radiation burns (0.5% vs. 2%, P = 0.04). Dose-based follow-up protocols are superior in detecting radiation burns when compared to fluoroscopy time-based protocols. Frame rate reduction of fluoroscopy and cine acquisition and use of modified imaging equipment can achieve a significant reduction to patient/staff exposure. Copyright © 2011 Wiley-Liss, Inc.

  19. Optimal propofol induction dose in morbidly obese patients: A randomized controlled trial comparing the bispectral index and lean body weight scalar.

    PubMed

    Subramani, Yamini; Riad, Waleed; Chung, Frances; Wong, Jean

    2017-05-01

    Propofol dosing based on total body weight (TBW) can lead to overdosing in morbidly obese (MO) patients. Our aim was to determine whether an induction dose of propofol based on a bispectral index (BIS) target is better for achieving loss of consciousness in MO patients than dosing based on lean body weight (LBW). Sixty MO patients with a body mass index (BMI) of ≥ 40 kg·m(-2) were randomized to either BIS- or LBW-based propofol dosing groups. Anesthesia was induced with a propofol infusion of 100 mg·kg(-1)·hr(-1) to an initial target endpoint of a BIS of 50 (BIS group) or until a precalculated dose of 2.6 mg·kg(-1) LBW based on the Janmahasatian equation was administered (LBW group). Induction was assessed using the observer's assessment alertness/sedation scale (OAA/S). If an OAA/S score of 0 was not achieved, infusions continued until it reached 0. The groups were compared for the primary outcome which was the difference in the propofol doses at the initial target endpoint. The median [interquartile range] OAA/S score at the initial target endpoint was lower in the BIS group than in the LBW group (0 [0-0] vs 1 [0-3], respectively; median difference 1, 95% confidence interval [CI] 0 to 3; P = 0.001). The number of patients requiring additional propofol doses was also higher for the LBW group [1 vs 18 patients, respectively; relative risk of requiring additional propofol 18; 95% CI 3 to 126; P = 0.001]. The mean (SD) propofol dose at the target endpoint was significantly lower in the LBW group than in the BIS group [164 (36) mg vs 225 (44) mg, respectively; mean difference 61 mg; 95% CI 41 to 83 mg; P = 0.002]. There was no difference between the two groups, however, regarding the total induction dose of propofol needed for the OAA/S to reach 0 (P = 0.07). The induction dose of propofol based on the BIS index was different from the induction dose based on LBW in MO patients. Patients in the LBW group required additional propofol to achieve an OAA/S of 0.

  20. Loss of local control due to tumor displacement as a function of margin size, dose-response slope, and number of fractions.

    PubMed

    Selvaraj, Jothybasu; Uzan, Julien; Baker, Colin; Nahum, Alan

    2013-04-01

    Geometric uncertainties are inevitable in radiotherapy. To account for these uncertainties, a margin is added to the clinical target volume (CTV) to create the planning target volume (PTV), and its size is critical for obtaining an optimal treatment plan. Dose-based (i.e., physical) margin recipes have been published and widely used, but it is important to consider fractionation and the radiobiological characteristics of the tumor when deriving margins. Hence a tumor control probability (TCP)-based margin is arguably more appropriate. Margins required for ≤ 1% loss in mean population TCP (relative to a static tumor) for varying numbers of fractions, varying slope of the dose-response curve (γ50) and varying degrees of dose distribution conformity are investigated for spherical and four-field (4F)-brick dose distributions. To simulate geometric uncertainties, systematic (Σ) and random (σ) tumor displacements were sampled from Gaussian distributions and applied to each fraction for a spherical CTV. Interfraction tumor motion was simulated and the dose accumulated from fraction to fraction on a voxel-by-voxel basis to calculate TCP. PTV margins derived from this work for various fraction numbers and dose-response slopes (γ50) for different degrees of geometric uncertainties are compared with margins calculated using published physical-dose- and TCP-based recipes. Larger margins are required for a decrease in the number of fractions and for an increase in γ50 for both spherical and 4F-brick dose distributions. However, the margins can be close to zero for the 4F-brick distribution for small geometric uncertainties (Σ = 1, σ = 1 mm) irrespective of the number of fractions and the magnitude of γ50 due to the higher "incidental" dose outside the tumor. For Σ = 1 mm and σ = 3 mm, physical-dose-based recipes underestimate the margin only for the combination of hypofractionated treatments and tumors with a high γ50. For all other situations TCP-based margins are

  1. Slide Rule for Rapid Response Estimation of Radiological Dose from Criticality Accidents

    SciTech Connect

    Broadhead, B L; Childs, R L; Hopper, C M; Parks, C V

    1999-09-20

    This paper describes a functional slide rule that provides a readily usable "in-hand" method for estimating nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material concentration, critical vessel geometry, and solution addition rate. Another graph provides neutron and gamma dose-reduction factors for water, steel, and concrete shields.

  2. First results from electron-photon damage equivalence studies on a generic ethylene-propylene rubber

    SciTech Connect

    Buckalew, W.H.

    1986-04-01

    As part of a simulator adequacy assessment program, the relative effectiveness of electrons and photons to produce damage in a generic ethylene propylene rubber (EPR) has been investigated. The investigation was limited in extent in that a single EPR material, in three thickness, was exposed to Cobalt-60 photons and three electron beam energies. Basing material damage on changes in the EPR mechanical properties elongation and tensile strength, we observed that EPR damage was a smoothly varying function of absorbed energy and independent of irradiating particle type. EPR damage tracked equally well as a function of both incident particle energy and material front surface dose. Based on these preliminary data, we tentatively concluded that a correlation between particle, particle energy, and material damage (as measured by changes in material elongation and/or tensile strength) has been demonstrated. 14 figs.

  3. Environmental Monitoring Plan for the Oak Ridge Reservation, 2012

    SciTech Connect

    Thompson, Sharon D.

    2012-10-01

    The purpose of Oak Ridge Reservation (ORR) environmental surveillance is to characterize radiological and nonradiological conditions of the off-site environs and estimate public doses related to these conditions, confirm estimations of public dose based on effluent monitoring data, and, where appropriate, provide supplemental data to support compliance monitoring for applicable environmental regulations. This environmental monitoring plan (EMP) is intended to document the rationale, frequency, parameters, and analytical methods for the ORR environmental surveillance program and provides information on ORR site characteristics, environmental pathways, dose assessment methods, and quality management. ORR-wide environmental monitoring activities include a variety of media including air, surface water, vegetation, biota, and wildlife. In addition to these activities, site-specific effluent, groundwater, and best management monitoring programs are conducted at the Oak Ridge National Laboratory (ORNL), the Y-12 National Security Complex (Y-12), and the East Tennessee Technology Park (ETTP). This is revision 5.

  4. Simplification of an Erythropoiesis Model for Design of Anemia Management Protocols in End Stage Renal Disease

    PubMed Central

    Nichols, B; Shrestha, RP; Horowitz, J; Hollot, CV; Chait, Y; Germain, MJ; Gaweda, AE

    2014-01-01

    Many end stage renal disease (ESRD) patients suffer from anemia due to insufficient endogenous production of erythropoietin (EPO). The discovery of recombinant human EPO (rHuEPO) over 30 years ago has shifted the treatment of anemia for patients on dialysis from blood transfusions to rHuEPO therapy. Many anemia management protocols (AMPs) used by clinicians comprise a set of experience-based rules for weekly-to-monthly titration of rHuEPO doses based on hemoglobin (Hgb) measurements. In order to facilitate the design of an AMP based on formal control design methods, we present a physiologically-relevant erythropoiesis model, and show that its nonlinear dynamics can be approximated using a static nonlinearity, a step that greatly simplifies AMP design. We demonstrate applicability of our results using clinical data. PMID:22254256

  5. "Visually clean" as a sole acceptance criterion for cleaning validation protocols.

    PubMed

    LeBlanc, Destin A

    2002-01-01

    The role of visual examination as the sole acceptance criterion in cleaning validation protocols is explored, including the proper definition of "visual limit" for a given residue. Such a visual limit is specific to the surface the residue is on, and is further defined by viewing conditions, such as lighting, distance, and angle of viewing. A visually clean standard may only be properly utilized if the visual limit is below any scientifically calculated residue limit, such as that determined by a traditional dose-based limit determination. While such an approach, properly applied, has scientific justification and appears to be accepted by the proposed Annex 15 to the European GMPs, the approach is still untested with regulatory authorities.

  6. Resveratrol products resulting by free radical attack

    NASA Astrophysics Data System (ADS)

    Bader, Yvonne; Quint, R. M.; Getoff, Nikola

    2008-06-01

    Trans-resveratrol ( trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented.

  7. RESRAD for Radiological Risk Assessment. Comparison with EPA CERCLA Tools - PRG and DCC Calculators

    SciTech Connect

    Yu, C.; Cheng, J. -J.; Kamboj, S.

    2015-07-01

    The purpose of this report is two-fold. First, the risk assessment methodology for both RESRAD and the EPA’s tools is reviewed. This includes a review of the EPA’s justification for 2 using a dose-to-risk conversion factor to reduce the dose-based protective ARAR from 15 to 12 mrem/yr. Second, the models and parameters used in RESRAD and the EPA PRG and DCC Calculators are compared in detail, and the results are summarized and discussed. Although there are suites of software tools in the RESRAD family of codes and the EPA Calculators, the scope of this report is limited to the RESRAD (onsite) code for soil contamination and the EPA’s PRG and DCC Calculators also for soil contamination.

  8. Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Anderson, D.M.; Bates, D.J.; Marsh, T.L.

    1993-07-01

    This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.

  9. Estimation of 1945 to 1957 food consumption

    SciTech Connect

    Anderson, D.M.; Bates, D.J.; Marsh, T.L.

    1993-03-01

    This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.

  10. Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project: Draft

    SciTech Connect

    Anderson, D.M.; Bates, D.J.; Marsh, T.L.

    1993-03-01

    This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.

  11. Alcohol withdrawal pharmacotherapy for inpatients with medical comorbidity.

    PubMed

    Weaver, Michael F; Hoffman, Heather J; Johnson, Robert E; Mauck, Kimberly

    2006-01-01

    Studies show that symptom-triggered dosing is best for treatment of alcohol withdrawal in patients on chemical dependence wards without other illness. On general medical hospital wards, withdrawal may be affected by comorbid medical illness. A clinical trial was undertaken to determine whether there is a difference between symptom-triggered (ST) and fixed-schedule (FS) dosing of lorazepam in patients hospitalized on general medical wards at a university medical center. One hundred eighty-three subjects were assessed by their nurses with the Revised Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar) scale. Subjects in the ST arm received lorazepam doses based on CIWA-Ar score. Subjects in the FS arm received scheduled lorazepam with tapering over 4 days. Symptom-triggered dosing for alcohol withdrawal for general medicine inpatients results in less lorazepam given with similar reduction in CIWA-Ar scores for the first 2 days, but a higher proportion of protocol errors.

  12. GAMMA IRRADIATION TESTING OF MONTAN WAX FOR USE IN WASTE MANAGEMENT SYSTEMS

    SciTech Connect

    SOO,P.; HEISER,J.; HART,A.

    1996-09-08

    A field demonstration was funded by the US Department of Energy (DOE) to quantify the potential use of montan wax as a subsurface barrier material for nuclear waste management applications. As part of that demonstration, a study was completed to address some of the characteristics of the wax. Of particular interest is its resistance to chemical and structural changes that would influence its integrity as a barrier to minimize the migration of contaminants from their storage or disposal locations. Properties that were evaluated included hardness, melting point, molecular weight, and biodegradation as a function of gamma radiation dose. Based on the data obtained to date the wax is extremely resistant to radiation-induced change. Coupled with low permeability, the material shows promise as a subsurface barrier material.

  13. Photodynamic therapy: superficial and interstitial illumination

    NASA Astrophysics Data System (ADS)

    Svanberg, Katarina; Bendsoe, Niels; Axelsson, Johan; Andersson-Engels, Stefan; Svanberg, Sune

    2010-07-01

    Photodynamic therapy (PDT) is reviewed using the treatment of skin tumors as an example of superficial lesions and prostate cancer as an example of deep-lying lesions requiring interstitial intervention. These two applications are among the most commonly studied in oncological PDT, and illustrate well the different challenges facing the two modalities of PDT-superficial and interstitial. They thus serve as good examples to illustrate the entire field of PDT in oncology. PDT is discussed based on the Lund University group's over 20 yr of experience in the field. In particular, the interplay between optical diagnostics and dosimetry and the delivery of the therapeutic light dose are highlighted. An interactive multiple-fiber interstitial procedure to deliver the required therapeutic dose based on the assessment of light fluence rate and sensitizer concentration and oxygen level throughout the tumor is presented.

  14. Guidelines for acceptable soil concentrations in the Old F- and H-Area Retention Basins. Revision 1

    SciTech Connect

    Hamby, D.M.

    1994-04-18

    Concentration guidelines for residual radionuclides in soil at the sites of the Old F- and a Retention Basins (281-3F, 281-3H) have been calculated using a dose-based approach. The guidelines also are being applied to areas around the F-Basin`s Process Line. Estimation of these soil guidelines was completed using RESRAD 5.0 in accordance with the DOE RESRAD methodology specified in DOE/CH/8901 (Gi89). Guidelines are provided for the nuclides known to be present in the soils at each basin (Sc87). Soil and hydrologic characteristics specific to each basin are defined for the areas above, within, and beneath the contaminated zones.

  15. Guidelines for acceptable soil concentrations in the old F- and H-Area Retention Basins

    SciTech Connect

    Hamby, D.M.

    1994-04-18

    Concentration guidelines for residual radionuclides in soil at the sites of the Old F- and H-Area Retention Basins (281-3F, 281-3H) have been calculated using a dose-based approach. The guidelines also are being applied to areas around the F-Basin`s Process Line. Estimation of these soil guidelines was completed using RESRAD 5.0 in accordance with the DOE RESRAD methodology specified in DOE/CH/8901 (Gi89). Guidelines are provided for the nuclides known to be present in the soils at each basin (Sc87). Soil and hydrologic characteristics specific to each basin are defined for the areas above, within, and beneath the contaminated zones.

  16. Phase I clinical trial of an injectable contraceptive for the male.

    PubMed

    Guha, S K; Singh, G; Anand, S; Ansari, S; Kumar, S; Koul, V

    1993-10-01

    Earlier studies on the rat and the monkey had demonstrated that an injection of styrene maleic anhydride (SMA) in a solvent vehicle of dimethyl sulphoxide (DMSO) into the lumen of the vas deferens is toxicologically safe and has contraceptive action. Phase I clinical trial was therefore undertaken on 38 male volunteers giving varying doses of SMA, ranging between 5 mg and 140 mg, into each vas deferens. A dose of 70 mg is the predicted therapeutic dose based on animal data. That the compound is within the vas deferens lumen during the period of the safety assessment is inferred from the effect on the spermatozoa count in ejaculates which reach azoospermic levels in the higher dose ranges. The treatment is well tolerated with only minimal side effects in a few cases and no long-term adverse effects.

  17. Considerations for Bioassay Monitoring of Mixtures of Radionuclides

    DOE PAGES

    Klumpp, John; Waters, Tom; Bertelli, Luiz

    2017-10-01

    Complying with regulations for bioassay monitoring of radionuclide intakes is significantly more complex for mixtures than it is for pure radionuclides. Different constituents will naturally have different dose coefficients, be detectable at significantly different levels, and may require very different amounts of effort to bioassay. The ability to use certain constituents as surrogates for others will depend on how well characterized the mixture is, as well as whether the employee is also working with other radionuclides. This is further compounded by the fact that the composition of a mixture (or even of a pure radionuclide) is likely to change overmore » time. Internal dosimetrists must decide how best to monitor employees who work with radionuclide mixtures. In particular, they must decide which constituents should be monitored routinely, which constituents only need to be monitored in the case of an intake, and how to estimate doses based on intakes of monitored and unmonitored constituents.« less

  18. RESRAD soil concentration guidelines for the Old F-Area Retention Basin

    SciTech Connect

    Hamby, D.M.

    1994-02-24

    Concentration guidelines for residual radionuclides in soil at the site of the Old F-Area Retention Basin have been calculated using a dose-based approach. Estimation of these soil guidelines was completed using RESRAD 5.0 in accordance with the DOE RESRAD methodology specified in DOE/CH/8901. Guidelines are provided for the two predominant nuclides, Sr-90 and Cs-137, known to be present in the soil beneath the old basin. A guideline is also given for Pu-238 since it is known to exist at the H-Area Retention Basin. Site-specific soil characteristics are defined for the areas above, within, and beneath the contaminated zone.

  19. Estimation of body surface area in the musk shrew ( Suncus murinus): a small animal for testing chemotherapy-induced emesis.

    PubMed

    Eiseman, Julie L; Sciullo, Michael; Wang, Hong; Beumer, Jan H; Horn, Charles C

    2017-10-01

    Several cancer chemotherapies cause nausea and vomiting, which can be dose-limiting. Musk shrews are used as preclinical models for chemotherapy-induced emesis and for antiemetic effectiveness. Unlike rats and mice, shrews possess a vomiting reflex and demonstrate an emetic profile similar to humans, including acute and delayed phases. As with most animals, dosing of shrews is based on body weight, while translation of such doses to clinically equivalent exposure requires doses based on body surface area. In the current study body surface area in musk shrews was directly assessed to determine the Meeh constant (Km) conversion factor (female = 9.97, male = 9.10), allowing estimation of body surface area based on body weight. These parameters can be used to determine dosing strategies for shrew studies that model human drug exposures, particularly for investigating the emetic liability of cancer chemotherapeutic agents.

  20. Discovery of phenyl acetamides as potent and selective GPR119 agonists.

    PubMed

    Zhu, Cheng; Wang, Liping; Zhu, Yuping; Guo, Zack Zhiqiang; Liu, Ping; Hu, Zhiyong; Szewczyk, Jason W; Kang, Ling; Chicchi, Gary; Ehrhardt, Anka; Woods, Andrea; Seo, Toru; Woods, Morgan; van Heek, Margaret; Dingley, Karen H; Pang, Jianmei; Salituro, Gino M; Powell, Joyce; Terebetski, Jenna L; Hornak, Viktor; Campeau, Louis-Charles; Orr, Robert K; Ujjainwalla, Feroze; Miller, Michael; Stamford, Andrew; Wood, Harold B; Kowalski, Timothy; Nargund, Ravi P; Edmondson, Scott D

    2017-03-01

    The paper describes the SAR/SPR studies that led to the discovery of phenoxy cyclopropyl phenyl acetamide derivatives as potent and selective GPR119 agonists. Based on a cis cyclopropane scaffold discovered previously, phenyl acetamides such as compound 17 were found to have excellent GPR119 potency and improved physicochemical properties. Pharmacokinetic data of compound 17 in rat, dog and rhesus will be described. Compound 17 was suitable for QD dosing based on its predicted human half-life, and its projected human dose was much lower than that of the recently reported structurally-related benzyloxy compound 2. Compound 17 was selected as a tool compound candidate for NHP (Non-Human Primate) efficacy studies.

  1. High energy neutron response characteristics of a passive survey instrument for the determination of cosmic radiation fields in aircraft.

    PubMed

    Bartlett, D T; Tanner, R J; Hager, L G

    2002-01-01

    A passive survey instrument has been developed for the determination of cosmic radiation fields in aircraft. The instrument contains 30 TLDs and 36 PADC etched track detectors in order to obtain the required precision and an isotropic response. Two active electronic personal dosemeters are included to record the time profile of the field intensity. The instrument is robust and reliable, and is particularly useful to verify values of route doses based on calculations. The energy of the neutron component of the field to be determined extends to over 500 MeV, but with the majority of the dose equivalent below 200 MeV. The results are reported of measurements at Uppsala University and Physikalisch-Technische Bundesanstalt of the response characteristics of the instrument to quasi-monoenergetic neutrons in the energy range 60 to 180 MeV and for monoenergetic neutrons of energy from 70 keV to 14.7 MeV.

  2. Brachytherapy optimization using radiobiological-based planning for high dose rate and permanent implants for prostate cancer treatment

    NASA Astrophysics Data System (ADS)

    Seeley, Kaelyn; Cunha, J. Adam; Hong, Tae Min

    2017-01-01

    We discuss an improvement in brachytherapy--a prostate cancer treatment method that directly places radioactive seeds inside target cancerous regions--by optimizing the current standard for delivering dose. Currently, the seeds' spatiotemporal placement is determined by optimizing the dose based on a set of physical, user-defined constraints. One particular approach is the ``inverse planning'' algorithms that allow for tightly fit isodose lines around the target volumes in order to reduce dose to the patient's organs at risk. However, these dose distributions are typically computed assuming the same biological response to radiation for different types of tissues. In our work, we consider radiobiological parameters to account for the differences in the individual sensitivities and responses to radiation for tissues surrounding the target. Among the benefits are a more accurate toxicity rate and more coverage to target regions for planning high-dose-rate treatments as well as permanent implants.

  3. Prediction of multidimensional drug dose responses based on measurements of drug pairs

    PubMed Central

    Zimmer, Anat; Katzir, Itay; Dekel, Erez; Alon, Uri

    2016-01-01

    Finding potent multidrug combinations against cancer and infections is a pressing therapeutic challenge; however, screening all combinations is difficult because the number of experiments grows exponentially with the number of drugs and doses. To address this, we present a mathematical model that predicts the effects of three or more antibiotics or anticancer drugs at all doses based only on measurements of drug pairs at a few doses, without need for mechanistic information. The model provides accurate predictions on available data for antibiotic combinations, and on experiments presented here on the response matrix of three cancer drugs at eight doses per drug. This approach offers a way to search for effective multidrug combinations using a small number of experiments. PMID:27562164

  4. Prediction of multidimensional drug dose responses based on measurements of drug pairs.

    PubMed

    Zimmer, Anat; Katzir, Itay; Dekel, Erez; Mayo, Avraham E; Alon, Uri

    2016-09-13

    Finding potent multidrug combinations against cancer and infections is a pressing therapeutic challenge; however, screening all combinations is difficult because the number of experiments grows exponentially with the number of drugs and doses. To address this, we present a mathematical model that predicts the effects of three or more antibiotics or anticancer drugs at all doses based only on measurements of drug pairs at a few doses, without need for mechanistic information. The model provides accurate predictions on available data for antibiotic combinations, and on experiments presented here on the response matrix of three cancer drugs at eight doses per drug. This approach offers a way to search for effective multidrug combinations using a small number of experiments.

  5. Two years comparative studies on biological effects of environmental UV radiation

    NASA Astrophysics Data System (ADS)

    Grof, P.; Ronto, Gyorgyi; Gaspar, S.; Berces, A.; Szabo, Laszlo D.

    1994-07-01

    A method has been developed for determination of the biologically effective UV dose based on T7 phage as biosensor. In field experiments clockwork driven telescope has been used for determining doses from direct and global (direct plus diffuse) solar radiation. On fine summer days at mid-latitude this arrangement allowed the following comparisons: measured doses from direct and global radiation obtained at the same time and measuring site reflecting the biological importance of diffuse radiation; direct and global radiation obtained at the same time and measuring site reflecting the biological importance of diffuse radiation; direct and global doses obtained at the same time on different measuring sites (downtown, suburb, outside the town) reflecting the differences caused by air quality; direct and global doses obtained on the same measuring place, in summertime of two different years reflecting the importance of the long-term measurements for estimating the biological risk caused by increased UV-B radiation; measured data and model calculations.

  6. Protamine overdose and its impact on coagulation, bleeding, and transfusions after cardiopulmonary bypass: results of a randomized double-blind controlled pilot study.

    PubMed

    Koster, Andreas; Börgermann, Jochen; Gummert, Jan; Rudloff, Markus; Zittermann, Armin; Schirmer, Uwe

    2014-04-01

    We assessed the effects of protamine overdosing on thrombelastometry, bleeding, and transfusions in patients after cardiopulmonary bypass (CPB). In group 1 (n = 15), representing the clinical standard, the protamine dose was based on the initial heparin dose, and group 2 (n = 15) received protamine based on the heparin concentration measured after CPB. Primary end points were thromboelastometric parameters. Secondary end points were perioperative blood loss and utilization of blood products. During CPB, heparin concentrations decreased by 40%, resulting in overdosing of protamine in group 1. Thromboelastometry revealed longer clotting time (CT) in group 1 (P values < .05). Four patients in group 1 but none in group 2 had excessive prolonged CT values (>360 seconds) and concomitant microvascular bleeding, requiring substantial replacement of coagulation factors. Heparin dose-based protamine management leads to protamine overdosing with inhibition of the coagulation process. Protamine management guided by heparin concentration avoids these complications.

  7. A review of the fixed dose use of new oral anticoagulants in obese patients: Is it really enough?

    PubMed Central

    Güler, Ekrem; Güler, Gamze Babur; Demir, Gültekin Günhan; Hatipoğlu, Suzan

    2016-01-01

    Obesity is a significant cause of morbidity and mortality, and it is becoming increasingly prevalent worldwide. Altered pharmacodynamics and pharmacokinetics of drugs in obese patients require dose adjustment according to body weight. New oral anticoagulants (NOACs), which are more frequently used for anticoagulation, are recommended to be used at a fixed dose based on data derived from phase 2 and 3 studies. However, the representation of obese patients [>100 kg or a body mass index (BMI) of >30 kg/m2] in subgroups with a small sample size and reports of various emboli cases under drug treatment have raised suspicions about the adequacy of fixed dose use. To address this issue, we analyzed several patients with a body weight of >100 kg or BMI of >30 kg/m2 participating in NOAC studies and evaluated whether these numbers were sufficient to enable an accurate recommendation of fixed dose use in obese patients. PMID:26663225

  8. Individual external dose monitoring of all citizens of Date City by passive dosimeter 5 to 51 months after the Fukushima NPP accident (series): 1. Comparison of individual dose with ambient dose rate monitored by aircraft surveys.

    PubMed

    Miyazaki, Makoto; Hayano, Ryugo

    2016-12-06

    Date (da'te) City in Fukushima Prefecture has conducted a population-wide individual dose monitoring program after the Fukushima Daiichi Nuclear Power Plant Accident, which provides a unique and comprehensive data set of the individual doses of citizens. The purpose of this paper, the first in the series, is to establish a method for estimating effective doses based on the available ambient dose rate survey data. We thus examined the relationship between the individual external doses and the corresponding ambient doses assessed from airborne surveys. The results show that the individual doses were about 0.15 times the ambient doses, the coefficient of 0.15 being a factor of 4 smaller than the value employed by the Japanese government, throughout the period of the airborne surveys used. The method obtained in this study could aid in the prediction of individual doses in the early phase of future radiological accidents involving large-scale contamination.

  9. Use of the nonavalent HPV vaccine in individuals previously fully or partially vaccinated with bivalent or quadrivalent HPV vaccines.

    PubMed

    Van Damme, Pierre; Bonanni, Paolo; Bosch, F Xavier; Joura, Elmar; Kjaer, Susanne Krüger; Meijer, Chris J L M; Petry, Karl-Ulrich; Soubeyrand, Benoit; Verstraeten, Thomas; Stanley, Margaret

    2016-02-03

    With the availability of the nonavalent human papillomavirus (HPV) vaccine, vaccinees, parents and healthcare providers need guidance on how to complete an immunization course started with the bi- or quadrivalent vaccine and whether to revaccinate individuals who have completed a full immunization course with the bi- or quadrivalent vaccine. To answer these questions three parameters should be considered: age at the start of vaccination (9 to 14 years of age versus 15 years and older, the cut-off for 2 or 3 doses schedule), the number of doses already received and the time interval between doses. Based on a number of scenarios, we propose that the 9-valent vaccine can be used to complete an incomplete vaccination regimen or might be added to a previous completed schedule to extend protection. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Consequences of meta-stable (177m)Lu admixture in (177)Lu for patient dosimetry.

    PubMed

    Konijnenberg, Mark W

    2015-01-01

    Lutetium-177 ((177)Lu) is a rare earth metal in the lanthanides series which decays by beta emission with a half life of 6.647 days to three excited states and the ground state of (177)Hf. When (177)Lu is produced by neutron capture in (176)Lu, inevitably an admixture is formed of the long-lived isomer (177)mLu. As its half-life of 160.4 days is so much longer than that of (177)Lu, concerns are raised on its possible enhancement in radiation dose to the patient treated with (177)Lu-DOTA-octreotate. This report evaluates this possible enhancement of the absorbed dose, based on the published pharmacokinetic profile of (177)Lu-DOTA-octreotate and assuming an admixture of 1 kBq (177)mLu /MBq (177)Lu (0.1%).

  11. Real-Time Statistical Modeling of Blood Sugar.

    PubMed

    Otoom, Mwaffaq; Alshraideh, Hussam; Almasaeid, Hisham M; López-de-Ipiña, Diego; Bravo, José

    2015-10-01

    Diabetes is considered a chronic disease that incurs various types of cost to the world. One major challenge in the control of Diabetes is the real time determination of the proper insulin dose. In this paper, we develop a prototype for real time blood sugar control, integrated with the cloud. Our system controls blood sugar by observing the blood sugar level and accordingly determining the appropriate insulin dose based on patient's historical data, all in real time and automatically. To determine the appropriate insulin dose, we propose two statistical models for modeling blood sugar profiles, namely ARIMA and Markov-based model. Our experiment used to evaluate the performance of the two models shows that the ARIMA model outperforms the Markov-based model in terms of prediction accuracy.

  12. Radiation-induced degradation of 4-chloroaniline in aqueous solution

    NASA Astrophysics Data System (ADS)

    Sánchez, M.; Wolfger, H.; Getoff, N.

    2002-12-01

    The radiation-induced decomposition of 4-chloroaniline (4-ClA) was studied under steady-state conditions using aqueous solutions saturated with air, pure oxygen, N 2O, argon and argon in the presence of t-Butanol. Using HPLC-method, the initial G-values of the substrate degradation as well as of a number of radiolytic products were determined. The formation of aminophenols, chlorophenols, aniline and phenol in addition to chloride, ammonia, formaldehyde and mixture of aldehydes as well as carboxylic acids was studied as a function of absorbed dose. Based on the experimental data, probable reaction mechanisms for the degradation of 4-ClA by γ-rays and the formation of the identified products are presented.

  13. Personal dose-equivalent conversion coefficients for 1252 radionuclides.

    PubMed

    Otto, Thomas

    2016-01-01

    Dose conversion coefficients for radionuclides are useful for routine calculations in radiation protection in industry, medicine and research. They give a simple and often sufficient estimate of dose rates during production, handling and storage of radionuclide sources, based solely on the source's activity. The latest compilation of such conversion coefficients dates from 20 y ago, based on nuclear decay data published 30 y ago. The present publication provides radionuclide-specific conversion coefficients to personal dose based on the most recent evaluations of nuclear decay data for 1252 radionuclides and fluence-to-dose-equivalent conversion coefficients for monoenergetic radiations. It contains previously unknown conversion coefficients for >400 nuclides and corrects those conversion coefficients that were based on erroneous decay schemes. For the first time, estimates for the protection quantity Hp(3) are included.

  14. Haze defect control and containment in a high volume DRAM manufacturing environment

    NASA Astrophysics Data System (ADS)

    Chen, Jerry X.; Nguyen, Maihan; Arasaki, Osamu; Maraquin, Tammy; Sawyer, Daniel; Morrison, Pedro

    2005-11-01

    Haze and other progressive reticle defects have been known in the semiconductor industry for more than a decade [1]. Extensive research and experiments have been carried out to determine the sources and origins of the progressive haze growth, but the true mechanisms of its cause are still under speculation. To minimize the wafer yield loss at Samsung Austin Semiconductor (SAS), we introduced a practical method to control the haze defects in a DRAM manufacturing environment that integrates reticle and wafer inspections, reticle cleaning, and a dose-based and time-based control forecast software system. This development has been proven to be very effective in controlling the haze defects and reducing the related yield loss while still supporting high volume wafer production.

  15. Environmental ALARA Program at the Savannah River Site

    SciTech Connect

    Jannik, G.T.

    1993-08-01

    The Savannah River Site (SRS) follows the ALARA (As Low As Reasonably Achievable) philosophy of keeping radiation doses to the general public as low as practical by minimizing radioactive releases to the environment. SRS accomplishes this goal by establishing challenging sitewide and area-specific Environmental ALARA Release Guides and trending radioactive releases against these guides on a monthly basis. The SRS Environmental ALARA Program, mandated by DOE Order 5400.5, is a dose-based program that has gone through many changes and improvements in recent years. A description of the SRS Environmental ALARA Program and its performance is presented in this paper. Recent SRS studies of the ``Zero Release`` option also are described.

  16. Proposed changes for part N of suggested state regulations

    SciTech Connect

    Paris, R.

    1997-02-01

    This paper discusses proposed changes for Part N regulations regarding naturally occuring radioactive materials. It describes the work of the Commission on NORM of the Conference of Radiation Control Program Directors (CRCPD), toward adjusting the regulations. A set of questions was formulated and a review panel established to address these questions and come back with recommended actions. The panel recommended the distinction that the material being regulated is `Technologically Enhanced Naturally Occurring Radioactive Material` (TENORM). By this they mean `naturally occurring radioactive material not regulated under the Atomic Energy Act (AEA) whose radionuclide concentrations have been increased by or as a result of human practices.` Recommendations also include: using a dose based instead of concentration based standard; refined definition of exemptions from regulations; exclusion of radon from Total Effective Dose Equivalent (TEDE) calculations; provide states flexibility in implementation; inclusion of prospective remedial and operations aspects for TENORM; provision of institutional controls.

  17. Quorum quenching analysis in Pseudomonas aeruginosa and Escherichia coli: network topology and inhibition mechanism effect on the optimized inhibitor dose.

    PubMed

    Barrios, Andrés Fernando González; Covo, Virginia; Medina, Luis Miguel; Vives-Florez, Martha; Achenie, Luke

    2009-06-01

    The discovery of quorum sensing as a mechanism for regulating specific phenotypes in bacteria based on population density has conveyed attention to find molecules capable of interfering quorum sensing networks (QSN) in a process coined quorum quenching. Here, we examined the dynamics of Escherichia coli AI-2 and Pseudomonas aeruginosa QSN exposed to signal degraders or competitors for binding transcriptional regulators. Stability analysis was performed for E. coli and P. aeruginosa finding no multistability in E. coli. However, our model allowed to discern that quenchers influence P. aeruginosa QSN multistability by reducing the interval of the amount of molecules of the extracellular signal that originate several steady states. We proposed a simulated annealing algorithm to optimize the quencher dose based on stochastic kinetics. E. coli QSN requires around 640 while P. aeruginosa QSN needs 253 quencher molecules per microorganism. This dose was found to be negatively influenced by the quencher-signal affinity.

  18. Large Cohort Dose-Volume Response Analysis of Parotid Gland Function After Radiotherapy: Intensity-Modulated Versus Conventional Radiotherapy

    SciTech Connect

    Dijkema, Tim Terhaard, Chris H.J.; Roesink, Judith M.; Braam, Petra M.; Gils, Carla H. van; Moerland, Marinus A.; Raaijmakers, Cornelis P.J.

    2008-11-15

    Purpose: To compare parotid gland dose-volume response relationships in a large cohort of patients treated with intensity-modulated (IMRT) and conventional radiotherapy (CRT). Methods and materials: A total of 221 patients (64 treated with IMRT, 157 with CRT) with various head-and-neck malignancies were prospectively evaluated. The distribution of tumor subsites in both groups was unbalanced. Stimulated parotid flow rates were measured before and 6 weeks, 6 months, and 1 year after radiotherapy. Parotid gland dose-volume histograms were derived from computed tomography-based treatment planning. The normal tissue complication probability (NTCP) model proposed by Lyman was fit to the data. A complication was defined as stimulated parotid flow ratio <25% of the pretreatment flow rate. The relative risk of complications was determined for IMRT vs. CRT and adjusted for the mean parotid gland dose using Poisson regression modeling. Results: One year after radiotherapy, NTCP curves for IMRT and CRT were comparable with a TD{sub 50} (uniform dose leading to a 50% complication probability) of 38 and 40 Gy, respectively. Until 6 months after RT, corrected for mean dose, different complication probabilities existed for IMRT vs. CRT. The relative risk of a complication for IMRT vs. CRT after 6 weeks was 1.42 (95% CI 1.21-1.67), after 6 months 1.41 (95% CI; 1.12-1.77), and at 1 year 1.21 (95% CI 0.87-1.68), after correcting for mean dose. Conclusions: One year after radiotherapy, no difference existed in the mean dose-based NTCP curves for IMRT and CRT. Early after radiotherapy (up to 6 months) mean dose based (Lyman) models failed to fully describe the effects of radiotherapy on the parotid glands.

  19. SU-E-T-109: An Investigation of Including Variable Relative Biological Effectiveness in Intensity Modulated Proton Therapy Planning Optimization for Head and Neck Cancer Patients

    SciTech Connect

    Cao, W; Zaghian, M; Lim, G; Randeniya, K; Mohan, R; Titt, U

    2015-06-15

    Purpose: The current practice of considering the relative biological effectiveness (RBE) of protons in intensity modulated proton therapy (IMPT) planning is to use a generic RBE value of 1.1. However, RBE is indeed a variable depending on the dose per fraction, the linear energy transfer, tissue parameters, etc. In this study, we investigate the impact of using variable RBE based optimization (vRBE-OPT) on IMPT dose distributions compared by conventional fixed RBE based optimization (fRBE-OPT). Methods: Proton plans of three head and neck cancer patients were included for our study. In order to calculate variable RBE, tissue specific parameters were obtained from the literature and dose averaged LET values were calculated by Monte Carlo simulations. Biological effects were calculated using the linear quadratic model and they were utilized in the variable RBE based optimization. We used a Polak-Ribiere conjugate gradient algorithm to solve the model. In fixed RBE based optimization, we used conventional physical dose optimization to optimize doses weighted by 1.1. IMPT plans for each patient were optimized by both methods (vRBE-OPT and fRBE-OPT). Both variable and fixed RBE weighted dose distributions were calculated for both methods and compared by dosimetric measures. Results: The variable RBE weighted dose distributions were more homogenous within the targets, compared with the fixed RBE weighted dose distributions for the plans created by vRBE-OPT. We observed that there were noticeable deviations between variable and fixed RBE weighted dose distributions if the plan were optimized by fRBE-OPT. For organs at risk sparing, dose distributions from both methods were comparable. Conclusion: Biological dose based optimization rather than conventional physical dose based optimization in IMPT planning may bring benefit in improved tumor control when evaluating biologically equivalent dose, without sacrificing OAR sparing, for head and neck cancer patients. The research

  20. Different effects of lansoprazole and rabeprazole on the plasma voriconazole trough levels in allogeneic hematopoietic cell transplant recipients.

    PubMed

    Yasu, Takeo; Konuma, Takaaki; Kato, Seiko; Kurokawa, Yosuke; Takahashi, Satoshi; Tojo, Arinobu

    2016-10-01

    Voriconazole (VRC) is widely used as prophylaxis and in the treatment of invasive fungal disease (IFD) after allogeneic hematopoietic cell transplantation (HCT). We retrospectively examined the results of VRC therapeutic drug monitoring (TDM) in allogeneic HCT recipients. A total of 474 samples were obtained from 59 adult patients who received VRC during the first 100 days following HCT between 2009 and 2014 in our institute. Seventeen patients received VRC for prophylaxis of IFD, and 42 received VRC for the empirical or preemptive therapy for IFD. A total of 299 samples (63 %) were obtained during the administration of the intravenous form of VRC. The median VRC daily dose based on the actual body weight was 6.68 mg/kg/day (range, 1.92-10.41 mg/kg/day). The median VRC trough level was 0.99 mg/l (range, <0.09-5.45 mg/l). The multivariate analysis using a logistic regression model demonstrated significantly higher VRC trough levels (≥1.0 mg/l) in males (P < 0.001), empirical or preemptive therapy (P = 0.002), VRC daily dose based on the actual body weight ≥7 mg/kg/day (P < 0.001), and concomitant use of lansoprazole as compared to rabeprazole (P < 0.001). The concomitant use of calcineurin inhibitors and corticosteroids had no effects on VRC trough levels in multivariate analysis. These data suggest that lansoprazole and rabeprazole have different effects on the plasma VRC trough levels in the allogeneic HCT recipients.

  1. Pharmacodynamic Considerations with Recombinant Human Insulin-Like Growth Factor-I in Children

    PubMed Central

    Ferry, Robert J.; Cohen, Pinchas; Levitt Katz, Lorraine E.

    2011-01-01

    Aim To report effects of weight-based recombinant human insulin-like growth factor-I (rhIGF-I) on IGF axis parameters in children with hyperinsulinism. Methods Open label trial with subcutaneous rhIGF-I (40 μg/kg/dose). Patients studied were children (1 month to 11 years) with diffuse hyperinsulinism (n = 7). Serial serum IGF and insulin-like growth factor binding protein (IGFBP) concentrations were measured by RIA and analyzed by linear Pearson regression. Results Following the initial rhIGF-I dose, total insulin-like growth factor-I (IGF-I) rose by 56% at 30 min (p < 0.01) and 85% at 120 min (p < 0.02). Serum IGF-II, IGFBP-2, and IGFBP-3 levels did not change. Peak serum IGF-I levels within 12 h of the initial rhIGF-I dose were 167–700 mg/ml. The variable peak IGF-I response is attributable in part to IGFBP-3 differences across this pediatric age range. Models of rhIGF-I dosing based upon body surface area (BSA) or initial IGFBP-3 resulted in predictable peak serum IGF-I levels (r = 0.78; p < 0.03). Recalculating rhIGF-I dosing based upon the BSA · IGFBP-3 product correlated closely with peak IGF-I level (r = 0.85; p < 0.007). Conclusions Weight-based IGF-I dosing in this cohort resulted in variable IGF-I levels. Considering BSA and serum IGFBP-3 concentration in children is appropriate for subcutaneous IGF-I administration. A combination of these values may yield predictable individualization of rhIGF-I dosing. PMID:15886488

  2. Actual or ideal body weight to calculate CD34+ cell dose in patients undergoing autologous hematopoietic SCT for myeloma?

    PubMed

    Singh, V; Krishnamurthy, J; Duffey, S; Meagher, R; Villa, M; Monreal, J; Evens, A; Frankfurt, O; Altman, J; Gordon, L; Tallman, M; Williams, S; Winter, J; Singhal, S; Mehta, J

    2009-02-01

    CD34+ cell dose calculations are usually based on actual body weight (ABW). We have shown that ideal body weight (IBW) may provide a better basis for this in a small population of patients with hematologic malignancies. This was studied further in 514 myeloma autografts. The CD34+ cell doses (10(6)/kg) by IBW and ABW were 1.37-39.36 (median 6.03) and 1.15-29.67 (median 4.84), respectively. IBW-based cell doses correlated slightly better with engraftment than ABW-based doses (higher r(2)): 0.5 x 10(9)/l neutrophils 0.83 versus 0.82, 1.0 x 10(9)/l neutrophils 0.78 versus 0.77, 20 x 10(9)/l platelets 0.54 versus 0.53 and 50 x 10(9)/l platelets 0.57 versus 0.55. When outliers (hematologic recovery in <8 or >16 days) were excluded, the findings were similar: 0.5 x 10(9)/l neutrophils 0.85 versus 0.84, 1.0 x 10(9)/l neutrophils 0.85 versus 0.84, 20 x 10(9)/l platelets 0.86 versus 0.85 and 50 x 10(9)/l platelets 0.85 versus 0.84. CD34+ cell doses based on IBW as well as ABW significantly affected engraftment when analyzed separately as continuous variables. However, when analyzed together, only the dose based on IBW retained significance. We conclude that calculation of CD34+ cell numbers for autotransplantation should be based on IBW.

  3. Ideal or actual body weight to calculate CD34+ cell doses for autologous hematopoietic stem cell transplantation?

    PubMed

    Ali, M Y; Oyama, Y; Monreal, J; Winter, J N; Tallman, M S; Williams, S F; Singhal, S; Gordon, L I; Mehta, J

    2003-05-01

    The number of CD34+ cells infused influences the speed of hematologic recovery post-transplant. There are limited data on whether ideal (IBW) or actual (ABW) body weight should be used to calculate CD34+ cell dose. We compared the correlation between recovery to 0.5 x 10(9)/l neutrophils and the CD34+ cell dose based upon ABW as well as IBW in 87 patients autografted for cancer. ABW was >or=25% over IBW in 43% of patients. The median number of CD34+ cells administered was 3.6 x 10(6)/kg ABW and 4.2 x 10(6)/kg IBW. The time to neutrophil recovery was 8-15 days (median 10). There was a stronger inverse correlation between CD34+ cell dose/IBW and neutrophil recovery (r(2)=0.308; P<0.0001) than between CD34+ cell dose/ABW and neutrophil recovery (r(2)=0.267; P<0.0001). The median time to neutrophil recovery was comparable for those receiving >or=2 x 10(6)/kg CD34+ cells/kg IBW as well as ABW (10 days) and those receiving >or=2 x 10(6)/kg CD34+ cells/kg IBW but <2/kg ABW (10 days), but was significantly slower for those receiving <2 x 10(6)/kg CD34+ cells/kg IBW (12 days). These data show that the CD34+ cell dose based on IBW is a better predictor of neutrophil recovery after autotransplantation.

  4. Heparin and Protamine Titration Does Not Improve Haemostasis after Cardiac Surgery: A Prospective Randomized Study.

    PubMed

    Radulovic, Vladimir; Laffin, Anna; Hansson, Kenny M; Backlund, Erika; Baghaei, Fariba; Jeppsson, Anders

    2015-01-01

    Bleeding complications are common in cardiac surgery. Perioperative handling of heparin and protamine may influence the haemostasis. We hypothesized that heparin and protamine dosing based on individual titration curves would improve haemostasis in comparison to standard dosing. Sixty patients scheduled for first time elective coronary artery bypass grafting or valve surgery were included in a prospective randomized study. The patients were randomized to heparin and protamine dosing with Hepcon HMS Plus device or to standard weight and activated clotting time (ACT) based dosing. Blood samples were collected before and 10 minutes, 2 hours and 4 hours after cardiopulmonary bypass. Primary endpoint was endogenous thrombin potential in plasma 2 hours after surgery as assessed by calibrated automated thrombography. Secondary endpoints included total heparin and protamine doses, whole blood clot formation (thromboelastometry) and post-operative bleeding volume and transfusions. Heparin effect was assessed by measuring anti-Xa activity. Endogenous thrombin potential and clot formation deteriorated in both groups after surgery without statistically significant intergroup difference. There were no significant differences between the groups in total heparin and protamine doses, heparin effect, or postoperative bleeding and transfusions at any time point. Significant inverse correlations between anti-Xa activity and endogenous thrombin potential were observed 10 min (r = -0.43, p = 0.001), 2 hours (r = -0.66, p<0.001) and 4 hours after surgery (r = -0.58, p<0.001). In conclusion, the results suggest that perioperative heparin and protamine dosing based on individual titration curves does not improve haemostasis after cardiac surgery. Postoperative thrombin generation capacity correlates to residual heparin effect. www.isrctn.com ISRCTN14201041.

  5. Developing equations to predict surface dose and therapeutic interval in bolused electron fields: A Monte Carlo Study

    NASA Astrophysics Data System (ADS)

    Jabbari, Nasrollah; Khalkhali, Hamid Reza

    2017-07-01

    In this research, we aim to investigate the influence of different materials, as a bolus, on the low-energy electron beam dose distributions and to develop equations for predicting surface dose based on bolus thickness, as well as the therapeutic interval based on surface dose. All the Monte Carlo (MC) calculations and measurements were conducted on a Siemens PRIMUS linac. Based on EGSnrc MC code, BEAMnrc system was used to model a Siemens linac and generate phase-space files for three electron beams (6, 8, and 10 MeV). The particles were transported from the phase-space files to the bolus materials and the simulated water phantom using DOSXYZnrc. Various materials with different thicknesses were examined as a bolus, and appropriate equations were determined for each material and electron beam. The comparison of percent depth dose (PDD) curves and beam profiles, using MC, with the measured data demonstrated that the calculated values properly matched with the measurements. The results indicated that the use of bolus materials with the density of higher than soft tissue can increase both surface dose and therapeutic interval simultaneously. This finding arises from the fact that the required bolus thickness for achieving the therapeutic surface dose decreases in the case of high-density materials. Two series of prediction equations were proposed for predicting the surface dose based on bolus thickness and the therapeutic interval based on surface dose. These equations are able to calculate properly the bolus thickness required for producing a therapeutic surface dose (above 90%) for any therapeutic interval.

  6. Comparison of a continuous glucose monitoring system with a portable blood glucose meter to determine insulin dose in cats with diabetes mellitus.

    PubMed

    Dietiker-Moretti, S; Müller, C; Sieber-Ruckstuhl, N; Tschuor, F; Osto, M; Franchini, M; Ackermann, M; Lutz, T A; Reusch, C E; Zini, E

    2011-01-01

    The continuous glucose monitoring system (CGMS) Guardian REAL-Time(®) allows the generation of very detailed glucose profiles in cats. The performance of CGMS to generate short-term glucose profiles to evaluate treatment response has not been yet evaluated in diabetic cats. Analysis of glucose profiles generated using the CGMS produces insulin dose recommendations that differ from those of profiles generated using the portable blood glucose meter (PBGM) in diabetic cats. Thirteen client-owned diabetic cats. Prospective, observational study. Simultaneous glucose profiles were generated over an 8-10 hour period using the CGMS, blood glucose concentration was measured every 2 hours with the PBGM. Profiles were submitted to three internal medicine specialists who used them to determine the insulin dose. Differences between insulin doses deduced from paired profiles were compared. Percentages of nadirs recorded with the CGMS that were lower, higher, or equal to those derived with the PBGM were calculated. Twenty-one paired glucose profiles were obtained. There was no difference of insulin doses based on CGMS and PBGM profiles (median 0 U; range: -1 to +0.5). Treatment decisions did not differ among investigators. Compared with the observed PBGM nadir, the CGMS nadir was lower, higher, or equal in 17, 2, and 2 of 21 cases, respectively. Adjustments in insulin dose based on glucose profiles generated with the CGMS are similar to those based on the PBGM. The common occurrence of lower nadirs recorded with the CGMS suggests that this device detects hypoglycemic periods that are not identified with the PBGM. Copyright © 2011 by the American College of Veterinary Internal Medicine.

  7. Comparison of human growth hormone products' cost in pediatric and adult patients. A budgetary impact model.

    PubMed

    Bazalo, Gary R; Joshi, Ashish V; Germak, John

    2007-09-01

    We assessed the economic impact to the United States payer of recombinant human growth hormone (rhGH) utilization, comparing the relative dosage efficiency of marketed pen-based and vial-based products in a pediatric and in an adult population. A budgetary impact model calculated drug costs based on product waste and cost. Waste was the difference between prescribed dose, based on patient weight, and actual delivered dose, based on dosing increments and maximum deliverable dose for pens and a fixed-percent waste as derived from the literature for vials. Annual wholesale acquisition costs were calculated based upon total milligrams delivered, using a daily dose of 0.03 mg/kg for pediatric patients and 0.016 mg/kg for adults. Total annual drug costs were compared for two scenarios: 1) a product mix based on national market share and 2) restricting use to the product with lowest waste. Based on the literature, waste for each vial product was 23 percent. Among individual pens, waste was highest for Humatrope 24 mg (19.5 percent pediatric, 14.3 percent adult) and lowest for Norditropin Nordi-Flex 5 mg (1.1 percent pediatric, 1 percent adult). Restricting use to the brand with least waste (Norditropin), compared to national product share mix, resulted in a 10.2 percent reduction in annual pediatric patient cost from $19,026 to $17,089 and an 8 percent reduction in annual adult patient cost from $24,099 to $22,161. We concluded that pen delivery systems result in less waste than vial and syringe. Considering all approved delivery systems, Norditropin resulted in the least product waste and lower annual patient cost for both pediatric and adult populations.

  8. Cancer and the environment: Ten topics in environmental cancer epidemiology in Canada.

    PubMed

    Huchcroft, Shirley A; Mao, Yang; Semenciw, Robert

    2010-01-01

    This Chronic Diseases in Canada supplement is a compilation of literature reviews by scientific experts. It was initiated as follow-up to the Green Plan, the federal government's environmental agenda in the 1990s. In recognizing that Canadians are concerned about the environment and its relationship to their health, this document attempts to address some of these concerns in relation to cancer by reviewing and summarizing the epidemiological literature for ten environmental exposures, and highlighting future research needs. The topics include three types of radiation exposure (ultraviolet, radon and electromagnetic (powerfrequency electromagnetic fields)), three classes of chemical exposure (organochlorines, disinfection by-products, and pesticides), two types of air pollution (environmental tobacco smoke and outdoor air pollution), and two industrial sources (pulp and paper milling, and metal mining and processing). This publication is intended to provide a base of information for researchers interested in environmental cancer epidemiology and to assist with the formulation of research priorities. The ten topics reviewed here were selected because concern about them has been expressed or because they involve known animal carcinogens. Complete elimination of exposures to carcinogens in the environment, synthetic or natural, is not technically feasible if cancer can potentially occur at any level of exposure (i.e., the linear non-threshold theory). Consequently, it is important to have an operational concept of safety which is more practical than that of zero risk. Such an approach uses the concept of acceptable or essentially negligible risk to determine the exposure levels at which carcinogens are regulated. Acceptable risk has been defined as one that is "so small, whose consequences are so slight, or whose associated benefits (perceived or real) are so great that persons or groups in society are willing to take or be subjected to that risk". The level of risk

  9. Precautionary principles: a jurisdiction-free framework for decision-making under risk.

    PubMed

    Ricci, Paolo F; Cox, Louis A; MacDonald, Thomas R

    2004-12-01

    relevance of new information, relative to the initial (and smaller) set of data on which the decision was based. We exemplify this seemingly simple situation using risk management of BSE. As an integral aspect of causal analysis under risk, the methods developed in this paper permit the addition of non-linear, hormetic dose-response models to the current set of regulatory defaults such as the linear, non-threshold models. This increase in the number of defaults is an important improvement because most of the variants of the precautionary principle require cost-benefit balancing. Specifically, increasing the set of causal defaults accounts for beneficial effects at very low doses. We also show and conclude that quantitative risk assessment dominates qualitative risk assessment, supporting the extension of the set of default causal models.

  10. Radiation protection issues in dynamic contrast-enhanced (perfusion) computed tomography.

    PubMed

    Brix, Gunnar; Lechel, Ursula; Nekolla, Elke; Griebel, Jürgen; Becker, Christoph

    2015-12-01

    Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions. To characterize stochastic radiation risks of patients from these studies, life-time attributable cancer risks (LAR) were estimated using sex-, age-, and organ-specific risk models based on the hypothesis of a linear non-threshold dose-response relationship. For the brain, heart and pelvic cancer studies considered, local absorbed doses in the imaging field were about 100-190 mGy (total CTDI(vol), 200 mGy), 15-30 mGy (16 mGy) and 80-270 mGy (140 mGy), respectively. According to a recent publication of the International Commission on Radiological Protection (ICRP Publication 118, 2012), harmful tissue reactions of the cerebro- and cardiovascular systems as well as of the lenses of the eye become increasingly important at radiation doses of more than 0.5 Gy. The LARs estimated for the investigated cerebral and myocardial DCE-CT scenarios are less than 0.07% for males and 0.1% for females at an age of exposure of 40 years. For the considered tumor location and protocol, the corresponding LARs are more than 6 times as high

  11. Chromosomal and carcinogenic effects of sequential HZE and low-LET irradiations

    NASA Astrophysics Data System (ADS)

    Simonson, Dustin Mark

    All persons are exposed to a natural background of ionizing radiations with different spatial patterns of energy deposition resulting in differential biologic response. Astronauts, aircrew and radioactive contamination clean-up personnel are exposed to particularly complex radiation spectra. The current method for calculating radiation-induced exposure limits in mixed radiation environments is based on the linear summation of non-threshold risks, a methodology grounded in the premise that each component of the radiation field acts independently of the presence of other components. The assumption of effect independence of in-vitro exposed samples was tested by evaluating the frequency of chromosome aberrations induced by sequential irradiation of immortalized human mammary epithelial cells with 1 GeV/nucleon 56Fe ions and 137Cs gamma-rays. Experimental response was found to be significantly less than calculated on the basis of effect independence, but only when 56Fe ions preceded the photon exposure. That there was order dependence is interpreted as evidence that response may not simply be a result of interactions between similar sublesions but rather may involve qualitatively different time-ordered parameters. The presence of this sub-additive response is phenomenologically similar to adaptive response, which had not been previously reported as a consequence to high-energy heavy ion irradiation. Calculations based on effect independence predict a significantly greater average number and lifetime cumulative incidence of breast cancers in female Sprague-Dawley rats irradiated with both 56Fe ions and 250 MeV protons than was experimentally observed. This finding supports the hypothesis that the presence of non-additive response is not exclusively an in vitro phenomenon. Results from an evaluation of mammary epithelial cell response induced in a rat cancer model are marginally consistent with the use of in vivo induced chromosome aberrations as a biomarker of breast

  12. [Risk of postirradiation induction of cancer of the modern methods of radiotherapy (3D CRT and IMRT) head and neck cancer].

    PubMed

    Milecki, Piotr; Szyfter, Krzysztof; Skowronek, Janusz

    2004-01-01

    Ionizing radiation is a known "universal carcinogen" for a wide variety of tumors in man. Human populations are exposed to radiation coming from natural and industrial environment, and from medical sources. However, these are radiotherapy patients who receive the highest doses. Radiation both mutates and sterilizes cells (lethal effect). The risk of cancer induction from cells that have received very high doses of radiation (therapeutic dose about 2 Gy) is lower then from the cells with low doses, since the majority of them will have been sterilized. The epidemiological studies based on the population of atomic bomb survivors have indicated that the most acceptable model of carcinogenesis is the linear non-threshold model. The evaluation of clinical risk related to a wide range of radiation doses, which range from 0.01 Gy to 2 Gy, is connected with many methodological problems such as: differences in treatment factors (dose range, irradiated volume, anatomical site), unknown epidemiological data (smoking abuse, comorbidity), shortening of the follow-up (short lifespan, migration), evaluation of small groups of patients. The most important difficulty is lack of the sufficient knowledge of genetic background which is probably most significant in carcinogenesis process. The introduction into clinical practice of a new sophisticated method of irradiation such as the three-dimensional conformal radiotherapy (3D CRT) or intensity modulated radiotherapy (IMRT) leads to the increase of low irradiation dose for very large volume of normal tissue. Thus, the evaluation of these new methods in the context of carcinogenesis is a very important objective in the future. Today, we can only introduce the most important questions concerned with the risk of carcinogenesis induction which await answers: what is the risk of induction of cancer due to the implementation of these new methods of treatment, and how important is this risk for clinical practice, especially in the case of

  13. Method for Implementing Subsurface Solid Derived Concentration Guideline Levels (DCGL) - 12331

    SciTech Connect

    Lively, J.W.

    2012-07-01

    The U.S. Nuclear Regulatory Commission (NRC) and other federal agencies currently approve the Multi-Agency Radiation Site Survey and Investigation Manual (MARSSIM) as guidance for licensees who are conducting final radiological status surveys in support of decommissioning. MARSSIM provides a method to demonstrate compliance with the applicable regulation by comparing residual radioactivity in surface soils with derived concentration guideline levels (DCGLs), but specifically discounts its applicability to subsurface soils. Many sites and facilities undergoing decommissioning contain subsurface soils that are potentially impacted by radiological constituents. In the absence of specific guidance designed to address the derivation of subsurface soil DCGLs and compliance demonstration, decommissioning facilities have attempted to apply DCGLs and final status survey techniques designed specifically for surface soils to subsurface soils. The decision to apply surface soil limits and surface soil compliance metrics to subsurface soils typically results in significant over-excavation with associated cost escalation. MACTEC, Inc. has developed the overarching concepts and principles found in recent NRC decommissioning guidance in NUREG 1757 to establish a functional method to derive dose-based subsurface soil DCGLs. The subsurface soil method developed by MACTEC also establishes a rigorous set of criterion-based data evaluation metrics (with analogs to the MARSSIM methodology) that can be used to demonstrate compliance with the developed subsurface soil DCGLs. The method establishes a continuum of volume factors that relate the size and depth of a volume of subsurface soil having elevated concentrations of residual radioactivity with its ability to produce dose. The method integrates the subsurface soil sampling regime with the derivation of the subsurface soil DCGL such that a self-regulating optimization is naturally sought by both the responsible party and regulator

  14. Web-based training related to NRC staff review of dose modeling aspects of license termination and decommissioning plans.

    SciTech Connect

    LePoire, D.; Arnish, J.; Cheng, J. J.; Kamboj, S.; Richmond, P.; Chen, S. Y.; Barr, C.; McKenney, C.; Environmental Science Division; NRC

    2007-01-01

    NRC licensees at decommissioning nuclear facilities submit License Termination Plans (LTP) or Decommissioning Plans (DP) to NRC for review and approval. To facilitate a uniform and consistent review of these plans, the NRC developed training for its staff. A live classroom course was first developed in 2005, which targeted specific aspects of the LTP and DP review process related to dose-based compliance demonstrations or modeling. A web-based training (WBT) course is being developed in 2006 to replace the classroom-based course. The advantage of the WBT is that it will allow for staff training or refreshers at any time, while the advantage of a classroom-based course is that it provides a forum for lively discussion and the sharing of experience of classroom participants. The training course consists of the core and advanced modules tailored to specific NRC job functions. Topics for individual modules include identifying the characteristics of simple and complex sites, identifying when outside expertise or consultation is needed, demonstrating how to conduct acceptance and technical reviews of dose modeling, and providing details regarding the level of justification needed for realistic scenarios for both dose modeling and derivation of DCGLs. Various methods of applying probabilistic uncertainty analysis to demonstrate compliance with dose-based requirements are presented. These approaches include: (1) modeling the pathways of radiological exposure and estimating doses to receptors from a combination of contaminated media and radionuclides, and (2) using probabilistic analysis to determine an appropriate set of input parameters to develop derived concentration guideline limits or DCGLs (DCGLs are media- and nuclide-specific concentration limits that will meet dose-based, license termination rule criteria found in 10 CFR Part 20, Subpart E). Calculation of operational (field) DCGL's from media- and nuclide-specific DCGLs and use of operational DCGLs in conducting

  15. Web-based training related to NRC staff review of dose modeling aspects of license termination and decommissioning plans

    SciTech Connect

    LePoire, D.; Arnish, J.; Cheng, J.J.; Kamboj, S.; Richmond, P.; Chen, S.Y.; Barr, C.; McKenney, C.

    2007-07-01

    NRC licensees at decommissioning nuclear facilities submit License Termination Plans (LTP) or Decommissioning Plans (DP) to NRC for review and approval. To facilitate a uniform and consistent review of these plans, the NRC developed training for its staff. A live classroom course was first developed in 2005, which targeted specific aspects of the LTP and DP review process related to dose-based compliance demonstrations or modeling. A web-based training (WBT) course is being developed in 2006 to replace the classroom-based course. The advantage of the WBT is that it will allow for staff training or refreshers at any time, while the advantage of a classroom-based course is that it provides a forum for lively discussion and the sharing of experience of classroom participants. The training course consists of the core and advanced modules tailored to specific NRC job functions. Topics for individual modules include identifying the characteristics of simple and complex sites, identifying when outside expertise or consultation is needed, demonstrating how to conduct acceptance and technical reviews of dose modeling, and providing details regarding the level of justification needed for realistic scenarios for both dose modeling and derivation of DCGLs. Various methods of applying probabilistic uncertainty analysis to demonstrate compliance with dose-based requirements are presented. These approaches include 1) modeling the pathways of radiological exposure and estimating doses to receptors from a combination of contaminated media and radionuclides, and 2) using probabilistic analysis to determine an appropriate set of input parameters to develop derived concentration guideline limits or DCGLs (DCGLs are media- and nuclide-specific concentration limits that will meet dose-based, license termination rule criteria found in 10 CFR Part 20, Subpart E). Calculation of operational (field) DCGL's from media- and nuclide-specific DCGLs and use of operational DCGLs in conducting

  16. Assessment of normal tissue complications following prostate cancer irradiation: Comparison of radiation treatment modalities using NTCP models

    SciTech Connect

    Takam, Rungdham; Bezak, Eva; Yeoh, Eric E.; Marcu, Loredana

    2010-09-15

    Purpose: Normal tissue complication probability (NTCP) of the rectum, bladder, urethra, and femoral heads following several techniques for radiation treatment of prostate cancer were evaluated applying the relative seriality and Lyman models. Methods: Model parameters from literature were used in this evaluation. The treatment techniques included external (standard fractionated, hypofractionated, and dose-escalated) three-dimensional conformal radiotherapy (3D-CRT), low-dose-rate (LDR) brachytherapy (I-125 seeds), and high-dose-rate (HDR) brachytherapy (Ir-192 source). Dose-volume histograms (DVHs) of the rectum, bladder, and urethra retrieved from corresponding treatment planning systems were converted to biological effective dose-based and equivalent dose-based DVHs, respectively, in order to account for differences in radiation treatment modality and fractionation schedule. Results: Results indicated that with hypofractionated 3D-CRT (20 fractions of 2.75 Gy/fraction delivered five times/week to total dose of 55 Gy), NTCP of the rectum, bladder, and urethra were less than those for standard fractionated 3D-CRT using a four-field technique (32 fractions of 2 Gy/fraction delivered five times/week to total dose of 64 Gy) and dose-escalated 3D-CRT. Rectal and bladder NTCPs (5.2% and 6.6%, respectively) following the dose-escalated four-field 3D-CRT (2 Gy/fraction to total dose of 74 Gy) were the highest among analyzed treatment techniques. The average NTCP for the rectum and urethra were 0.6% and 24.7% for LDR-BT and 0.5% and 11.2% for HDR-BT. Conclusions: Although brachytherapy techniques resulted in delivering larger equivalent doses to normal tissues, the corresponding NTCPs were lower than those of external beam techniques other than the urethra because of much smaller volumes irradiated to higher doses. Among analyzed normal tissues, the femoral heads were found to have the lowest probability of complications as most of their volume was irradiated to lower

  17. Cryopreserved CD34(+) Cell Dose, but Not Total Nucleated Cell Dose, Influences Hematopoietic Recovery and Extensive Chronic Graft-versus-Host Disease after Single-Unit Cord Blood Transplantation in Adult Patients.

    PubMed

    Konuma, Takaaki; Kato, Seiko; Oiwa-Monna, Maki; Tanoue, Susumu; Ogawa, Miho; Isobe, Masamichi; Tojo, Arinobu; Takahashi, Satoshi

    2017-07-01

    Low cryopreserved total nucleated cell (TNC) dose in a cord blood (CB) unit has been shown to be associated with engraftment failure and mortality after single-unit cord blood transplantation (CBT) in adults. Although CB banks offer specific characteristics of cryopreserved cell dose, such as TNC, CD34(+) cells, and colony-forming unit for granulocyte/macrophage (CFU-GM), the impact of each cell dose on engraftment and outcomes after single-unit CBT in adults remains unclear. We retrospectively analyzed the results of 306 CBTs for 261 adult patients in our institution between 1998 and 2016. The median age was 43 years (range, 16 to 68), the median actual body weight (ABW) was 56.2 kg (range, 36.2 to 104.0), the median ideal body weight (IBW) was 62.3 kg (range, 39.7 to 81.3), the median TNC dose was 2.46 × 10(7)/ABW kg (range, 1.07 to 5.69), the median CD34(+) cell dose was .91 × 10(5)/ABW kg (range, .15 to 7.75), and the median CFU-GM dose was 24.46 × 10(3)/ABW kg (range, .04 to 121.81). Among patients who achieved engraftment, the speed of neutrophil, platelet, and red blood cell engraftment significantly correlated with CD34(+) cell dose, but not with TNC and CFU-GM dose, based on both ABW and IBW. In multivariate analysis, the incidence of extensive chronic graft-versus-host disease (GVHD) was significantly higher in patients receiving the highest CD34(+) cell dose, based on both ABW and IBW. Nevertheless, no cell dose was associated with survival, transplantation-related mortality, and relapse. In conclusion, cryopreserved CD34(+) cell dose was the best predictor for hematopoietic recovery and extensive chronic GVHD after CBT. The cryopreserved CD34(+) cell dose should be used for unit selection criteria in single-unit CBT for adults. Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

  18. Historical Doses from Tritiated Water and Tritiated Hydrogen Gas Released to the Atmosphere from Lawrence Livermore National Laboratory (LLNL). Part 3. Routine Releases, 1973 - 2005

    SciTech Connect

    Peterson, S

    2007-08-15

    Annual mean concentrations of tritium in air moisture, calculated from data obtained from an air tritium sampler near the LLNL Discovery Center, were compared with annual mean air moisture concentrations predicted from atmospheric releases of tritium for the years 1973 through 2005. The 95% confidence intervals on the predictions and observations usually overlapped. When the distributions of predictions and observations were different, predictions were higher. Using both the observed and predicted air concentrations as input to the tritium dose model, DCART, annual doses to a hypothetical adult, child (age 10) and infant (age 6 months to 1 year) assumed to be living at LLNL's Discovery Center were calculated. Although the doses based on predicted air concentrations tended to be higher, they were nevertheless indistinguishable from doses based on observed air concentrations when uncertainties were taken into account. Annual doses, calculated by DCART and based on observed and predicted air concentrations, were compared with historical tritium doses reported annually by LLNL. Although the historical doses were calculated using various assumptions over the years, their agreement with the DCART predictions is remarkable. The Discovery Center was not the location of the site-wide maximally exposed individual (SWMEI) from 1974 through 1978. However, doses at the location of the SW-MEI for those years were indistinguishable from those at the Discovery Center when uncertainties were taken into account. The upper confidence limits for all doses were always well below the current regulatory limit for dose to a member of the public (100 {micro}Sv or 10 mrem per year) from atmospheric releases (40 CFR Part 61, Subpart H). Based on observed air concentrations, the 97.5% confidence limit on the cumulative dose to the hypothetical person born in 1973 and living through 2005 at the Discovery Center was 150 {micro}Sv (15 mrem), while that of the hypothetical adult who spent his

  19. Product wastage from modern human growth hormone administration devices: a laboratory and computer simulation analysis.

    PubMed

    Pollock, Richard F; Qian, Yujun; Wisniewski, Tami; Seitz, Lisa; Kappelgaard, Anne-Marie

    2013-01-01

    Treatment of growth hormone disorders typically involves daily injections of human growth hormone (GH) over many years, incurring substantial costs. We assessed the extent of undesired GH loss due to leakage in the course of pen preparation prior to injection, and differences between the prescribed dose, based on patient weight, and the actual delivered dose based on pen dosing increments in five GH administration devices. Norditropin® prefilled FlexPro®, NordiFlex®, NordiLet®, and durable NordiPen®/SimpleXx® 5 mg pens (Novo Nordisk A/S, Bagsværd, Denmark) and durable Omnitrope® Pen-5 devices (Sandoz, Holzkirchen, Germany) were tested (n = 40 for each device type). Product wastage was measured in accordance with validated protocols in an ISO (International Organization for Standardization) 11608-1 and Good Manufacturing Practice compliant laboratory. The average mass of wasted GH from each device type was measured in simulations of dripping with the needle attached prior to injection and while setting a dose. Statistical significance (P < 0.05) was confirmed by Student's t-test, and a model was constructed to estimate mean annual GH wastage per patient in cohorts of pediatric patients with GH disorders. Mean GH mass wasted with the needle on prior to injection was 0.0 μg with Norditropin pens, relative to 98 μg with Omnitrope Pen-5. During dose dialing, 0.0-2.3 μg of GH was lost with Norditropin pens versus 0.8 μg with Omnitrope Pen-5. All Norditropin and Omnitrope device comparisons were statistically significant. Modeling GH wastage in a US cohort showed 5.5 mg of annual GH wastage per patient with FlexPro versus 43.6 mg with Omnitrope, corresponding to 7-8 additional pens per patient annually. Overall, Norditropin pens resulted in significantly less wastage than the Omnitrope Pen-5. The study suggests that GH devices of the same nominal volume exhibit differences that may affect the frequency of GH prescription refills required to remain adherent to

  20. Corrective Action Decision Document for Corrective Action Unit 536: Area 3 Release Site, Nevada Test Site, Nevada, Revision 0 with Errata

    SciTech Connect

    Boehlecke, Robert

    2004-11-01

    corrective action investigation (CAI). Record of Technical Change No. 1 to the CAIP documents changes to the PALs agreed to by the Nevada Division of Environmental Protection (NDEP) and DOE, National Nuclear Security Administration Nevada Site Office (NNSA/NSO). This ROTC provides the justification for changing from background-based to dose-b