Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)

DEFF Research Database (Denmark)

Nordberg, Monika; Templeton, Douglas M.; Andersen, Ole

2009-01-01

The objective of the "Glossary of terms used in ecotoxicology" is to give clear definitions for those who contribute to studies relevant to ecotoxicology but are not themselves ecotoxicologists. This objective applies especially to chemists who need to understand the ecotoxicological literature w...

Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays

International Nuclear Information System (INIS)

Wahyudi, Agung; Bartzke, Mariana; Küster, Eberhard; Bogaert, Patrick

2013-01-01

Ecotoxicological bioassays, e.g. based on Danio rerio teratogenicity (DarT) or the acute luminescence inhibition with Vibrio fischeri, could potentially lead to significant benefits for detecting on site contaminations on qualitative or semi-quantitative bases. The aim was to use the observed effects of two ecotoxicological assays for estimating the extent of a Benzene groundwater contamination plume. We used a Maximum Entropy (MaxEnt) method to rebuild a bivariate probability table that links the observed toxicity from the bioassays with Benzene concentrations. Compared with direct mapping of the contamination plume as obtained from groundwater samples, the MaxEnt concentration map exhibits on average slightly higher concentrations though the global pattern is close to it. This suggest MaxEnt is a valuable method to build a relationship between quantitative data, e.g. contaminant concentrations, and more qualitative or indirect measurements, in a spatial mapping framework, which is especially useful when clear quantitative relation is not at hand. - Highlights: ► Ecotoxicological shows significant benefits for detecting on site contaminations. ► MaxEnt to rebuild qualitative link on concentration and ecotoxicological assays. ► MaxEnt shows similar pattern when compared with concentrations map of groundwater. ► MaxEnt is a valuable method especially when quantitative relation is not at hand. - A Maximum Entropy method to rebuild qualitative relationships between Benzene groundwater concentrations and their ecotoxicological effect.

Ecotoxicology of Amphibians and Reptiles

Science.gov (United States)

2000-01-01

For many years, ecological research on amphibians and reptiles has lagged behind that of other vertebrates such as fishes, birds, and mammals, despite the known importance of these animals in their environments. The lack of study has been particularly acute in the he area of ecotoxicology where the number of published scientific papers is a fraction of that found for the other vertebrate classes. Recently, scientists have become aware of severe crises among amphibian populations, including unexplained and sudden extinctions, worldwide declines, and hideous malformations. In many of these instances, contaminants have been listed as probable contributors. Data on the effects of contaminants on reptiles are so depauperate that even the most elementary interpretations are difficult. This state-of-the-science review and synthesis of amphibian and reptile ecotoxicology demonstrates the inter-relationships among distribution, ecology, physiology, and contaminant exposure, and interprets these topics as they pertain to comparative toxicity, population declines, malformations, and risk assessment . In this way, the book identifies and serves as a basis for the most pressing research needs in the coming years. The editors have invited 27 other internationally respected experts to examine the state of existing data in specific areas, interpret it in light of current problems, and identify research gaps and needs. Through its emphasis on recent research, extensive reviews and synthesis, Ecotoxicology of Amphibians and Reptiles will remain a definitive reference work well into the new century.

Ecotoxicological effects of decabromodiphenyl ether and cadmium contamination on soil microbes and enzymes.

Science.gov (United States)

Zhang, Wei; Zhang, Meng; An, Shuai; Xiong, Bang; Li, Hui; Cui, Changzheng; Lin, Kuangfei

2012-08-01

The ecotoxicological effects of decabromodiphenyl ether (BDE209) and cadmium (Cd) contamination on soil culturable microbial population, enzyme activity and bacterial community structure were investigated. Results of the indoor incubation test runs performed on many series of control and contaminated soil samples have demonstrated some notable toxic effects due to long term exposure to either or both contaminants. The two contaminants produced notable yet different toxic effects on the test microbes; the population of the exposed species generally declined according to certain dose-response relationships. The soil culturable microbial population and enzyme activity data show that the sensitivity to one or both contaminants followed the order of: bacteria>fungi>actinomycete and urease>saccharase, respectively. The interaction between BDE209 and Cd was dependent on both the exposure dose and time and that the joint toxic effects were synergistic, antagonistic or additive. The PCR-DGGE analysis data of species composition and richness suggest the synergistic combined effects on bacterial community structure during the 30d exposure. Pseudomonas tuomuerensis strain CCM 7280 and Pseudomonas alcaliphila strain AL15-21 were enriched, indicating these species might be major functional populations and highly tolerant. Such observations have provided the useful information of potential ecotoxicological effects of BDE209 and Cd contamination in the environment. Copyright © 2012 Elsevier Inc. All rights reserved.

Contributions on ecotoxicology. Proceedings; Beitraege zur Oekotoxikologie. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Hartmann, A.; Brueggemann, R. [eds.

1997-11-01

Ecotoxicological effects can be defined in terms of changes in reaction patterns, processes, structures, and functions of ecosystems. At an all-day workshop at GSF on 10. November 1995 various working groups presented their reports on this subject. Taken together the contributions provide good coverage of the present state of knowledge on ecotoxicology. (orig./SR) [Deutsch] Oekotoxikologische Wirkungen lassen sich als Aenderungen hinsichtlich auftretender Reaktionsmuster, Prozesse, Strukturen und Funktionen von Oekosystemen definieren. 1. Molekulare, noxenbezogene Ebene; 2. Zellebene; 3. Organismenebene; 4. Modellsysteme; 5. Systemebene; Oekotoxikologische Bewertung; Im Rahmen eines ganztaegigen Workshops am 10. November 1995 in der GSF wurden Berichte verschiedener Arbeitsgruppe allen Themenbereichen vorgestellt. (orig./SR)

Efficient Wavefield Extrapolation In Anisotropic Media

KAUST Repository

Alkhalifah, Tariq; Ma, Xuxin; Waheed, Umair bin; Zuberi, Mohammad Akbar Hosain

2014-01-01

Various examples are provided for wavefield extrapolation in anisotropic media. In one example, among others, a method includes determining an effective isotropic velocity model and extrapolating an equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. The effective isotropic velocity model can be based upon a kinematic geometrical representation of an anisotropic, poroelastic or viscoelastic wavefield. Extrapolating the equivalent propagation can use isotopic, acoustic or elastic operators based upon the determined effective isotropic velocity model. In another example, non-transitory computer readable medium stores an application that, when executed by processing circuitry, causes the processing circuitry to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. In another example, a system includes processing circuitry and an application configured to cause the system to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield.

Efficient Wavefield Extrapolation In Anisotropic Media

KAUST Repository

Alkhalifah, Tariq

2014-07-03

Various examples are provided for wavefield extrapolation in anisotropic media. In one example, among others, a method includes determining an effective isotropic velocity model and extrapolating an equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. The effective isotropic velocity model can be based upon a kinematic geometrical representation of an anisotropic, poroelastic or viscoelastic wavefield. Extrapolating the equivalent propagation can use isotopic, acoustic or elastic operators based upon the determined effective isotropic velocity model. In another example, non-transitory computer readable medium stores an application that, when executed by processing circuitry, causes the processing circuitry to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. In another example, a system includes processing circuitry and an application configured to cause the system to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield.

Environmental chemistry and ecotoxicology: in greater demand than ever.

Science.gov (United States)

Scheringer, Martin

2017-01-01

Environmental chemistry and ecotoxicology have been losing support, resources, and recognition at universities for many years. What are the possible causes of this process? A first problem may be that the need for research and teaching in environmental chemistry and ecotoxicology is no longer seen because chemical pollution problems are considered as largely solved. Second, environmental chemistry and ecotoxicology may be seen as fields dominated by routine work and where there are not many interesting research questions left. A third part of the problem may be that other environmental impacts such as climate change are given higher priority than chemical pollution problems. Here, several cases are presented that illustrate the great demand for innovative research and teaching in environmental chemistry and ecotoxicology. It is crucial that environmental chemistry and ecotoxicology are rooted in academic science and are provided with sufficient equipment, resources, and prospects for development.

Omics Advances in Ecotoxicology.

Science.gov (United States)

Zhang, Xiaowei; Xia, Pu; Wang, Pingping; Yang, Jianghu; Baird, Donald J

2018-04-03

Toxic substances in the environment generate adverse effects at all levels of biological organization from the molecular level to community and ecosystem. Given this complexity, it is not surprising that ecotoxicologists have struggled to address the full consequences of toxic substance release at ecosystem level, due to the limits of observational and experimental tools to reveal the changes in deep structure at different levels of organization. -Omics technologies, consisting of genomics and ecogenomics, have the power to reveal, in unprecedented detail, the cellular processes of an individual or biodiversity of a community in response to environmental change with high sample/observation throughput. This represents a historic opportunity to transform the way we study toxic substances in ecosystems, through direct linkage of ecological effects with the systems biology of organisms. Three recent examples of -omics advance in the assessment of toxic substances are explored here: (1) the use of functional genomics in the discovery of novel molecular mechanisms of toxicity of chemicals in the environment; (2) the development of laboratory pipelines of dose-dependent, reduced transcriptomics to support high-throughput chemical testing at the biological pathway level; and (3) the use of eDNA metabarcoding approaches for assessing chemical effects on biological communities in mesocosm experiments and through direct observation in field monitoring. -Omics advances in ecotoxicological studies not only generate new knowledge regarding mechanisms of toxicity and environmental effect, improving the relevance and immediacy of laboratory toxicological assessment, but can provide a wholly new paradigm for ecotoxicology by linking ecological models to mechanism-based, systems biology approaches.

Effective wavefield extrapolation in anisotropic media: Accounting for resolvable anisotropy

KAUST Repository

Alkhalifah, Tariq Ali

2014-04-30

Spectral methods provide artefact-free and generally dispersion-free wavefield extrapolation in anisotropic media. Their apparent weakness is in accessing the medium-inhomogeneity information in an efficient manner. This is usually handled through a velocity-weighted summation (interpolation) of representative constant-velocity extrapolated wavefields, with the number of these extrapolations controlled by the effective rank of the original mixed-domain operator or, more specifically, by the complexity of the velocity model. Conversely, with pseudo-spectral methods, because only the space derivatives are handled in the wavenumber domain, we obtain relatively efficient access to the inhomogeneity in isotropic media, but we often resort to weak approximations to handle the anisotropy efficiently. Utilizing perturbation theory, I isolate the contribution of anisotropy to the wavefield extrapolation process. This allows us to factorize as much of the inhomogeneity in the anisotropic parameters as possible out of the spectral implementation, yielding effectively a pseudo-spectral formulation. This is particularly true if the inhomogeneity of the dimensionless anisotropic parameters are mild compared with the velocity (i.e., factorized anisotropic media). I improve on the accuracy by using the Shanks transformation to incorporate a denominator in the expansion that predicts the higher-order omitted terms; thus, we deal with fewer terms for a high level of accuracy. In fact, when we use this new separation-based implementation, the anisotropy correction to the extrapolation can be applied separately as a residual operation, which provides a tool for anisotropic parameter sensitivity analysis. The accuracy of the approximation is high, as demonstrated in a complex tilted transversely isotropic model. © 2014 European Association of Geoscientists & Engineers.

Effective wavefield extrapolation in anisotropic media: Accounting for resolvable anisotropy

KAUST Repository

Alkhalifah, Tariq Ali

2014-01-01

Spectral methods provide artefact-free and generally dispersion-free wavefield extrapolation in anisotropic media. Their apparent weakness is in accessing the medium-inhomogeneity information in an efficient manner. This is usually handled through a velocity-weighted summation (interpolation) of representative constant-velocity extrapolated wavefields, with the number of these extrapolations controlled by the effective rank of the original mixed-domain operator or, more specifically, by the complexity of the velocity model. Conversely, with pseudo-spectral methods, because only the space derivatives are handled in the wavenumber domain, we obtain relatively efficient access to the inhomogeneity in isotropic media, but we often resort to weak approximations to handle the anisotropy efficiently. Utilizing perturbation theory, I isolate the contribution of anisotropy to the wavefield extrapolation process. This allows us to factorize as much of the inhomogeneity in the anisotropic parameters as possible out of the spectral implementation, yielding effectively a pseudo-spectral formulation. This is particularly true if the inhomogeneity of the dimensionless anisotropic parameters are mild compared with the velocity (i.e., factorized anisotropic media). I improve on the accuracy by using the Shanks transformation to incorporate a denominator in the expansion that predicts the higher-order omitted terms; thus, we deal with fewer terms for a high level of accuracy. In fact, when we use this new separation-based implementation, the anisotropy correction to the extrapolation can be applied separately as a residual operation, which provides a tool for anisotropic parameter sensitivity analysis. The accuracy of the approximation is high, as demonstrated in a complex tilted transversely isotropic model. © 2014 European Association of Geoscientists & Engineers.

Efficient anisotropic wavefield extrapolation using effective isotropic models

KAUST Repository

Alkhalifah, Tariq Ali; Ma, X.; Waheed, Umair bin; Zuberi, Mohammad

2013-01-01

Isotropic wavefield extrapolation is more efficient than anisotropic extrapolation, and this is especially true when the anisotropy of the medium is tilted (from the vertical). We use the kinematics of the wavefield, appropriately represented

Ecotoxicology: problems and approaches

National Research Council Canada - National Science Library

Levin, Simon A

1989-01-01

This book conveys to the reader an up-to-date overview of the science of ecotoxicology, which describes and predicts ecological changes resulting from a variety of human activities involving release...

Incorporating evolutionary insights to improve ecotoxicology for freshwater species

Science.gov (United States)

Brady, Steven P.; Richardson, Jonathan L.; Kunz, Bethany K.

2017-01-01

Ecotoxicological studies have provided extensive insights into the lethal and sublethal effects of environmental contaminants. These insights are critical for environmental regulatory frameworks, which rely on knowledge of toxicity for developing policies to manage contaminants. While varied approaches have been applied to ecotoxicological questions, perspectives related to the evolutionary history of focal species or populations have received little consideration. Here, we evaluate chloride toxicity from the perspectives of both macroevolution and contemporary evolution. First, by mapping chloride toxicity values derived from the literature onto a phylogeny of macroinvertebrates, fish, and amphibians, we tested whether macroevolutionary relationships across species and taxa are predictive of chloride tolerance. Next, we conducted chloride exposure tests for two amphibian species to assess whether potential contemporary evolutionary change associated with environmental chloride contamination influences chloride tolerance across local populations. We show that explicitly evaluating both macroevolution and contemporary evolution can provide important and even qualitatively different insights from those obtained via traditional ecotoxicological studies. While macroevolutionary perspectives can help forecast toxicological end points for species with untested sensitivities, contemporary evolutionary perspectives demonstrate the need to consider the environmental context of exposed populations when measuring toxicity. Accounting for divergence among populations of interest can provide more accurate and relevant information related to the sensitivity of populations that may be evolving in response to selection from contaminant exposure. Our data show that approaches accounting for and specifically examining variation among natural populations should become standard practice in ecotoxicology.

Effective ellipsoidal models for wavefield extrapolation in tilted orthorhombic media

KAUST Repository

Waheed, Umair Bin

2016-04-22

Wavefield computations using the ellipsoidally anisotropic extrapolation operator offer significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate wavefield representation or imaging for media of orthorhombic symmetry. Therefore, we propose the use of ‘effective ellipsoidally anisotropic’ models that correctly capture the kinematic behaviour of wavefields for tilted orthorhombic (TOR) media. We compute effective velocities for the ellipsoidally anisotropic medium using kinematic high-frequency representation of the TOR wavefield, obtained by solving the TOR eikonal equation. The effective model allows us to use the cheaper ellipsoidally anisotropic wave extrapolation operators. Although the effective models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The proposed methodology offers a much better cost versus accuracy trade-off for wavefield computations in TOR media, particularly for media of low to moderate anisotropic strength. Furthermore, the computed wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference based TOR wave extrapolation scheme. We demonstrate applicability and usefulness of our formulation through numerical tests on synthetic TOR models. © 2016 Institute of Geophysics of the ASCR, v.v.i

Industrial ecotoxicology "acid rain".

Science.gov (United States)

Astolfi, E; Gotelli, C; Higa, J

1986-01-01

The acid rain phenomenon was studied in the province of Cordoba, Argentina. This study, based on a previously outlined framework, determined the anthropogenic origin of the low pH due to the presence of industrial hydrochloric acid wastage. This industrial ecotoxicological phenomenon seriously affected the forest wealth, causing a great defoliation of trees and shrubs, with a lower effect on crops. A survey on its effects on human beings has not been carried out, but considering the corrosion caused to different metals and its denouncing biocide effect on plants and animals, we should expect to find some kind of harm to the health of the workers involved or others engaged in farming, and even to those who are far away from the polluting agent.

Green technology meets ecotoxicology

Directory of Open Access Journals (Sweden)

Kristina Radošević

2016-01-01

Full Text Available By applying concept and principles of green chemistry into different technological processes, green technologies are developed. The environmental and economic benefits of “green” approach is achieved through several directions, such as the use of renewable raw materials, creation of economic efficiency, the use of alternative reaction conditions, as well as the application of non-conventional solvents. From the point view of green chemistry, alternative solvents, in order to be a “green“ substitution to hazardous organic solvents, should be: non-volatile, non-flammable, stabile, synthesized by an environmentally friendly procedure, nontoxic and biodegradable. The toxic impact of all newly synthesized chemicals, such as alternative solvents, could be determined by methods and techniques of ecotoxicology. Ecotoxicology, an interdisciplinary scientific field, can serve as a way of monitoring the greenness of the processes. In vivo and in vitro experiments are used to study the effects of chemicals on different levels of organizations, from molecules to communities and ecosystem. The usage of in vitro methods is encouraged by a scientific community and regulatory agencies as an alternative to in vivo studies in order to reduce the number of laboratory animals used in the toxicological studies. Therefore, in this paper we gave a brief overview on the usage of animal cell cultures within the field of green chemistry and technology.

Ethics in science: ecotoxicology

Directory of Open Access Journals (Sweden)

John Cairns Jr.

2003-05-01

Full Text Available Predictive ecotoxicology emphasizes the probable environmental outcome of exposure to toxics, rather than the mere appraisal of existing damage, and in so doing raises some complex but interesting ethical issues. Awareness of endocrine-disrupting chemicals is blurring the line between humankind and other life forms in toxicity testing by providing evidence that both humans and wildlife suffer adverse reproductive and developmental effect. There is a wide variety of chemicals that have been reported as potential endocrine disruptors. Finally, with the increasing loss of wildlife habitat, protecting the quality and ultimate fate of the remaining habitat from the effects of toxis substances becomes increasingly important to the moral quest for sustainable use of the planet.

Comparing sensitivity of ecotoxicological effect endpoints between laboratory and field

DEFF Research Database (Denmark)

Selck, H.; Riemann, B.; Christoffersen, K.

2002-01-01

multispecies field tests using tributyltin (TBT) and linear alkylbenzene sulfonates (LAS) were compared with published laboratory single-species test results and measured in situ concentrations. Extrapolation methods were evaluated by comparing predicted no-effect concentrations (PNECs), calculated by AF...

Effect of extrapolation length on the phase transformation of epitaxial ferroelectric thin films

International Nuclear Information System (INIS)

Hu, Z.S.; Tang, M.H.; Wang, J.B.; Zheng, X.J.; Zhou, Y.C.

2008-01-01

Effects of extrapolation length on the phase transformation of epitaxial ferroelectric thin films on dissimilar cubic substrates have been studied on the basis of the mean-field Landau-Ginzburg-Devonshire (LGD) thermodynamic theory by taking an uneven distribution of the interior stress with thickness into account. It was found that the polarization of epitaxial ferroelectric thin films is strongly dependent on the extrapolation length of films. The physical origin of the extrapolation length during the phase transformation from paraelectric to ferroelectric was revealed in the case of ferroelectric thin films

Ecotoxicology of arsenic in the hydrosphere: Implications for public ...

African Journals Online (AJOL)

STORAGESEVER

2008-12-29

Dec 29, 2008 ... health. This paper is therefore a review of the ecotoxicological effects of arsenic on human and ecological health. .... tissues of wild birds (Fairbrother et al.,1994) and in many ..... Mercury, arsenic, lead and cadmium in fish and ...

Towards a renewed research agenda in ecotoxicology

International Nuclear Information System (INIS)

Artigas, Joan; Arts, Gertie; Babut, Marc; Caracciolo, Anna Barra; Charles, Sandrine; Chaumot, Arnaud; Combourieu, Bruno; Dahllöf, Ingela; Despréaux, Denis; Ferrari, Benoit; Friberg, Nikolai; Garric, Jeanne; Geffard, Olivier; Gourlay-Francé, Catherine; Hein, Michaela; Hjorth, Morten; Krauss, Martin

2012-01-01

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management. - New regulations and innovative biological tools change the way ecotoxicological risk assessment should be seen. A new research agenda is therefore needed.

Ecotoxicological effect characterisation of widely used organic UV filters

International Nuclear Information System (INIS)

Kaiser, D.; Sieratowicz, A.; Zielke, H.; Oetken, M.; Hollert, H.; Oehlmann, J.

2012-01-01

Chemical UV filters are used in sun protection and personal care products in order to protect consumers from skin cancer induced by ultraviolet (UV) radiation. The present study aims to evaluate the effects of three common UV filters butyl-methoxydibenzoylmethane (B-MDM) ethylhexyl-methoxycinnamate (EHMC) and octocrylene (OCR) on aquatic organism, focussing particularly on infaunal and epibentic invertebrates (Chironomus riparius, Lumbriculus variegatus, Melanoides tuberculata and Potamopyrgus antipodarum). Due to their life habits, these organism are especially affected by lipophilic substances. Additionally, two direct sediment contact assays utilising zebra fish (Danio rerio) embryos and bacteria (Arthrobacter globiformis) were conducted. EHMC caused a toxic effect on reproduction in both snails with lowest observed effect concentrations (LOEC) of 0.4 mg/kg (Potamopyrgus antipodarum) and 10 mg/kg (Melanoides tuberculata). At high concentrations sublethal effects could be observed for D. rerio after exposure to EHMC (NOEC 100 mg/kg). B-MDM and OCR showed no effects on any of the tested organism. - Highlights: ► Ecotoxicological effects of common used UV filters on aquatic invertebrates. ► Butyl-methoxydibenzoylmethane, ethylhexyl-methoxycinnamate, and octocrylene used. ► Sediment based test systems. ► Ethylhexyl-methoxycinnamate caused a toxic effect on reproduction in both snails. ► Other substances showed no effects on any of the tested organism. - Ethylhexyl-methoxycinnamate caused a toxic effect on reproduction in both snails. Butyl-methoxydibenzoylmethane and octocrylene showed no effects on any of the tested organism.

Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media

KAUST Repository

Waheed, Umair bin

2014-05-01

Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.

Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media

KAUST Repository

Waheed, Umair bin; Alkhalifah, Tariq Ali

2014-01-01

Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.

Reviewing the serotonin reuptake inhibitors (SSRIs) footprint in the aquatic biota: Uptake, bioaccumulation and ecotoxicology

International Nuclear Information System (INIS)

a Comba, 3000-548 Coimbra (Portugal))" data-affiliation=" (REQUIMTE, Group of Bromatology, Pharmacognosy and Analytical Sciences, Faculty of Pharmacy, University of Coimbra, Polo III, Azinhaga de Sta Comba, 3000-548 Coimbra (Portugal))" >Silva, Liliana J.G.; a Comba, 3000-548 Coimbra (Portugal))" data-affiliation=" (REQUIMTE, Group of Bromatology, Pharmacognosy and Analytical Sciences, Faculty of Pharmacy, University of Coimbra, Polo III, Azinhaga de Sta Comba, 3000-548 Coimbra (Portugal))" >Pereira, André a Comba, 3000-548 Coimbra (Portugal))" data-affiliation=" (REQUIMTE, Group of Bromatology, Pharmacognosy and Analytical Sciences, Faculty of Pharmacy, University of Coimbra, Polo III, Azinhaga de Sta Comba, 3000-548 Coimbra (Portugal))" >M.P.T.; Meisel, Leonor M.; a Comba, 3000-548 Coimbra (Portugal))" data-affiliation=" (REQUIMTE, Group of Bromatology, Pharmacognosy and Analytical Sciences, Faculty of Pharmacy, University of Coimbra, Polo III, Azinhaga de Sta Comba, 3000-548 Coimbra (Portugal))" >Lino, Celeste M.; a Comba, 3000-548 Coimbra (Portugal))" data-affiliation=" (REQUIMTE, Group of Bromatology, Pharmacognosy and Analytical Sciences, Faculty of Pharmacy, University of Coimbra, Polo III, Azinhaga de Sta Comba, 3000-548 Coimbra (Portugal))" >Pena, Angelina

2015-01-01

Selective serotonin re-uptake inhibitors (SSRIs) antidepressants are amongst the most prescribed pharmaceutical active substances throughout the world. Their presence, already described in different environmental compartments such as wastewaters, surface, ground and drinking waters, and sediments, and their remarkable effects on non-target organisms justify the growing concern about these emerging environmental pollutants. A comprehensive review of the literature data with focus on their footprint in the aquatic biota, namely their uptake, bioaccumulation and both acute and chronic ecotoxicology is presented. Long-term multigenerational exposure studies, at environmental relevant concentrations and in mixtures of related compounds, such as oestrogenic endocrine disruptors, continue to be sparse and are imperative to better know their environmental impact. - Highlights: • Current knowledge of uptake and bioaccumulation of SSRIs. • Ecotoxicology and effects of SSRIs in the aquatic biota. • Identification of existing knowledge gaps. - A comprehensive review focussing SSRIs antidepressants footprint in the aquatic biota, namely their uptake, bioaccumulation, and both acute and chronic ecotoxicology is presented

Ecotoxicological Effects of Chemical Contaminants Adsorbed to Microplastics in the Clam Scrobicularia plana

Directory of Open Access Journals (Sweden)

Sarit O'Donovan

2018-04-01

Full Text Available Although microplastics (MPs are distributed globally in the marine environment, a great deal of unknowns relating to their ecotoxicological effects on the marine biota remains. Due to their lipophilic nature, microplastics have the potential to adsorb persistent organic pollutants present in contaminated regions, which may increase their detrimental impact once assimilated by organisms. This study investigates the ecotoxicological effects of exposure to low-density polyethylene (LDPE microplastics (11–13 μm, with and without adsorbed contaminants (benzo[a]pyrene—BaP and perfluorooctane sulfonic acid—PFOS, in the peppery furrow shell clam, Scrobicularia plana. Environmentally relevant concentrations of contaminants (BaP−16.87 ± 0.22 μg g−1 and PFOS−70.22 ± 12.41 μg g−1 were adsorbed to microplastics to evaluate the potential role of plastic particles as a source of chemical contamination once ingested. S. plana were exposed to microplastics, at a concentration of 1 mg L−1, in a water-sediment exposure setup for 14 days. Clams were sampled at the beginning of the experiment (day 0 and after 3, 7, and 14 days. BaP accumulation, in whole clam tissues, was analyzed. A multi-biomarker assessment was conducted in the gills, digestive gland, and haemolymph of clams to clarify the effects of exposure. This included the quantification of antioxidant (superoxide dismutase, catalase, glutathione peroxidase and biotransformation (glutathione-S-transferases enzyme activities, oxidative damage (lipid peroxidation levels, genotoxicity (single and double strand DNA breaks, and neurotoxicity (acetylcholinesterase activity. Results suggest a potential mechanical injury of gills caused by ingestion of microplastics that may also affect the analyzed biomarkers. The digestive gland seems less affected by mechanical damage caused by virgin microplastic exposure, with the MPs-adsorbed BaP and PFOS exerting a negative influence over the assessed

Ecotoxicological evaluation of sediments applied to environmental forensic investigation

Directory of Open Access Journals (Sweden)

R. H. Alves

Full Text Available Abstract The present study aimed to evaluate the potential for using toxicity assays with sediment samples for the detection of water pollution caused by the discharge of tannery effluents into water bodies and its application to environmental forensic investigation. The study included ecotoxicological evaluation of sediments, survey of benthic organisms in the field, as well as chromium, cadmium and lead dosage which provided data for a sediment quality triad evaluation. The sediment samples showed acute and chronic toxicity to the bioindicators, low biodiversity of benthic macrofauna and high chromium concentration, reaching up to 4365 mg.Kg–1. A close relationship was observed between the separate results of ecotoxicological sediment evaluation and the sediment quality triad. The sediment ecotoxicological assessment proved to be applicable to tracking sources of contamination related to tanneries and similar activities in environmental forensics.

Distillation fraction-specific ecotoxicological evaluation of a paraffin-rich crude oil.

Science.gov (United States)

Erlacher, Elisabeth; Loibner, Andreas P; Kendler, Romana; Scherr, Kerstin E

2013-03-01

Crude oil is a complex mixture of petroleum hydrocarbons (PHC) with distinct chemical, physical and toxicological properties relevant for contaminated site risk assessment. Ecotoxicological effects of crude oil distillation fractions on luminescent bacteria (Vibrio fischeri), earthworms (Dendrobaena hortensis) and invertebrates (Heterocypris incongruens) were tested using two spiked soils and their elutriates. Fraction 2 (F2) had an equivalent carbon number (ECN) range of >10 to 16, and F3 from >16 to 39. F2 showed a substantially higher ecotoxicological effect than F3 for Vibrio and Dendrobaena. In contrast, severe inhibition of Heterocypris by the poorly soluble F3 is attributed to mechanical organ blockage. Immediate sequestration of PHC to the organic matter-rich soil effected reduced toxicity for all organisms. This study indicates that a more differentiated consideration (i) of PHC mixtures based on ECN range and (ii) of model soil properties employed for ecotoxicity testing should be included into PHC-contaminated site risk assessment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Assessing ecological effects of radionuclides: data gaps and extrapolation issues

International Nuclear Information System (INIS)

Garnier-Laplace, Jacqueline; Gilek, Michael; Sundell-Bergman, Synnoeve; Larsson, Carl-Magnus

2004-01-01

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors> individual to population> ecosystem structure to function

General extrapolation model for an important chemical dose-rate effect

International Nuclear Information System (INIS)

Gillen, K.T.; Clough, R.L.

1984-12-01

In order to extrapolate material accelerated aging data, methodologies must be developed based on sufficient understanding of the processes leading to material degradation. One of the most important mechanisms leading to chemical dose-rate effects in polymers involves the breakdown of intermediate hydroperoxide species. A general model for this mechanism is derived based on the underlying chemical steps. The results lead to a general formalism for understanding dose rate and sequential aging effects when hydroperoxide breakdown is important. We apply the model to combined radiation/temperature aging data for a PVC material and show that this data is consistent with the model and that model extrapolations are in excellent agreement with 12-year real-time aging results from an actual nuclear plant. This model and other techniques discussed in this report can aid in the selection of appropriate accelerated aging methods and can also be used to compare and select materials for use in safety-related components. This will result in increased assurance that equipment qualification procedures are adequate

Ecotoxicological evaluation of industrial port of Venice (Italy) sediment samples after a decontamination treatment.

Science.gov (United States)

Libralato, Giovanni; Losso, Chiara; Arizzi Novelli, Alessandra; Citron, Marta; Della Sala, Stefano; Zanotto, Emanuele; Cepak, Franka; Volpi Ghirardini, Annamaria

2008-12-01

This work assesses the ecotoxicological effects of polluted sediment after a decontamination treatment process using a new sediment washing technique. Sediment samples were collected from four sites in Marghera Port industrial channels (Venice, Italy). Ecotoxicological evaluations were performed with Vibrio fischeri and Crassostrea gigas bioassays. Whole sediment and elutriate were deemed as the most suitable environmental matrices for this study. Toxicity scores developed in the Lagoon of Venice for V. fischeri on whole sediment and for C. gigas on elutriate were considered for the final ranking of samples. Ecotoxicological results showed that the treated sediment samples presented both acute and sub-chronic toxicities, which were mainly attributed to the presence of some remaining chemicals such as metals and polyaromatic hydrocarbons. The acute toxicity ranged from low to medium, while the sub-chronic one from absent to very high, suggesting that treated sediments could not be reused in direct contact with seawater.

Methodology for the Assessment of the Ecotoxicological Potential of Construction Materials

Science.gov (United States)

Rodrigues, Patrícia; Silvestre, José D.; Flores-Colen, Inês; Viegas, Cristina A.; de Brito, Jorge; Kurad, Rawaz; Demertzi, Martha

2017-01-01

Innovation in construction materials (CM) implies changing their composition by incorporating raw materials, usually non-traditional ones, which confer the desired characteristics. However, this practice may have unknown risks. This paper discusses the ecotoxicological potential associated with raw and construction materials, and proposes and applies a methodology for the assessment of their ecotoxicological potential. This methodology is based on existing laws, such as Regulation (European Commission) No. 1907/2006 (REACH—Registration, Evaluation, Authorization and Restriction of Chemicals) and Regulation (European Commission) No. 1272/2008 (CLP—Classification, Labelling and Packaging). Its application and validation showed that raw material without clear evidence of ecotoxicological potential, but with some ability to release chemicals, can lead to the formulation of a CM with a slightly lower hazardousness in terms of chemical characterization despite a slightly higher ecotoxicological potential than the raw materials. The proposed methodology can be a useful tool for the development and manufacturing of products and the design choice of the most appropriate CM, aiming at the reduction of their environmental impact and contributing to construction sustainability. PMID:28773011

Methodology for the Assessment of the Ecotoxicological Potential of Construction Materials.

Science.gov (United States)

Rodrigues, Patrícia; Silvestre, José D; Flores-Colen, Inês; Viegas, Cristina A; de Brito, Jorge; Kurad, Rawaz; Demertzi, Martha

2017-06-13

Innovation in construction materials (CM) implies changing their composition by incorporating raw materials, usually non-traditional ones, which confer the desired characteristics. However, this practice may have unknown risks. This paper discusses the ecotoxicological potential associated with raw and construction materials, and proposes and applies a methodology for the assessment of their ecotoxicological potential. This methodology is based on existing laws, such as Regulation (European Commission) No. 1907/2006 (REACH-Registration, Evaluation, Authorization and Restriction of Chemicals) and Regulation (European Commission) No. 1272/2008 (CLP-Classification, Labelling and Packaging). Its application and validation showed that raw material without clear evidence of ecotoxicological potential, but with some ability to release chemicals, can lead to the formulation of a CM with a slightly lower hazardousness in terms of chemical characterization despite a slightly higher ecotoxicological potential than the raw materials. The proposed methodology can be a useful tool for the development and manufacturing of products and the design choice of the most appropriate CM, aiming at the reduction of their environmental impact and contributing to construction sustainability.

On the necessity of ecotoxicological assessments of aquatic sediments

International Nuclear Information System (INIS)

Krebs, F.

1992-01-01

The guidelines for dredged material adopted by the Oslo Commission in June 1991 impose stricter obligations on its member states regarding the management of dredged material in the marine environment. It can be assumed that the basic ideas of these guidelines will become the model for inland waterways as well. For an environmentally acceptable management of dredging operations and the collection of evidence against polluters, ecotoxicological investigations on the behaviour of contaminants in waters are required in addition to chemical analyses. The practical application of these guidelines is hampered by the fact that no standardized biotests for sediments exist in Germany to date. The paper describes situations in which standardized biotest methods of aquatic ecotoxicology can already be used. A concept for the biological assessment of sediments is still lacking. It is necessary to define quality objectives for the evaluation of chemical and ecotoxicological data with a view to ecologically acceptable management of dredged material. (orig.) [de

Extrapolation methods theory and practice

CERN Document Server

Brezinski, C

1991-01-01

This volume is a self-contained, exhaustive exposition of the extrapolation methods theory, and of the various algorithms and procedures for accelerating the convergence of scalar and vector sequences. Many subroutines (written in FORTRAN 77) with instructions for their use are provided on a floppy disk in order to demonstrate to those working with sequences the advantages of the use of extrapolation methods. Many numerical examples showing the effectiveness of the procedures and a consequent chapter on applications are also provided - including some never before published results and applicat

Ecotoxicological testing of performance fluids

International Nuclear Information System (INIS)

Kallqvist, T.

1990-05-01

The report deals with a project comprising the testing of drilling fluids concerning ecotoxicology, biological degradation, and toxicity. Two types of drilling fluids were tested for toxic effects on marine algae and biological degradability. A fluid based on mineral oil was readily degradable (98% DOC removal in 28 days) while an ether based oil degraded more slowly (56% DOC removal in 28 days). The toxicity of both fluids was tested after emulsification of the oils in water and separating the oil and water phase after equilibration. The EC 50 values obtained with this approach were 8.15 g/l for the oil based fluid and 116 g/l for the ether fluid. 9 figs., 8 tabs

[Ecotoxicological study of chlorinated pesticides].

Science.gov (United States)

Rosival, L; Szokolay, A; Uhnák, J

1980-01-01

The authors describe a model for the ecotoxicological investigation of pesticide residues guided by the analysis of various links of the food chain and of human materials. It is pointed to the possibility of studying the dynamics of the exposure to human beings by analyzing gynaecological material (prenatal stage) and samples obtained at necropsy from human beings of varying age (different durations of exposure). The observations of the relative accumulation of hexachlorobenzene, beta-BHC and DDT in butter, human milk and human fat in a region with intensive cultivation revealed a considerble accumulation of hexachlorobenzene which reaches the level of DDT. The conclusion drawn from ecotoxicological studies indicates that a reduction of the tolerances of pesticide residues in raw materials for baby foods is imperative. The analyses of gynaecological material (202 samples of the available content of the uterus and 24 placental and embryonic specimens) permitted to evidence a significant difference between two regions and a specific relationship of the observed substances and their metabolites to the fat-dissolving power of the analyzed materials.

Principles of animal extrapolation

Energy Technology Data Exchange (ETDEWEB)

Calabrese, E.J.

1991-01-01

Animal Extrapolation presents a comprehensive examination of the scientific issues involved in extrapolating results of animal experiments to human response. This text attempts to present a comprehensive synthesis and analysis of the host of biomedical and toxicological studies of interspecies extrapolation. Calabrese's work presents not only the conceptual basis of interspecies extrapolation, but also illustrates how these principles may be better used in selection of animal experimentation models and in the interpretation of animal experimental results. The book's theme centers around four types of extrapolation: (1) from average animal model to the average human; (2) from small animals to large ones; (3) from high-risk animal to the high risk human; and (4) from high doses of exposure to lower, more realistic, doses. Calabrese attacks the issues of interspecies extrapolation by dealing individually with the factors which contribute to interspecies variability: differences in absorption, intestinal flora, tissue distribution, metabolism, repair mechanisms, and excretion. From this foundation, Calabrese then discusses the heterogeneticity of these same factors in the human population in an attempt to evaluate the representativeness of various animal models in light of interindividual variations. In addition to discussing the question of suitable animal models for specific high-risk groups and specific toxicological endpoints, the author also examines extrapolation questions related to the use of short-term tests to predict long-term human carcinogenicity and birth defects. The book is comprehensive in scope and specific in detail; for those environmental health professions seeking to understand the toxicological models which underlay health risk assessments, Animal Extrapolation is a valuable information source.

Drug residues in urban water: A database for ecotoxicological risk management.

Science.gov (United States)

Destrieux, Doriane; Laurent, François; Budzinski, Hélène; Pedelucq, Julie; Vervier, Philippe; Gerino, Magali

2017-12-31

Human-use drug residues (DR) are only partially eliminated by waste water treatment plants (WWTPs), so that residual amounts can reach natural waters and cause environmental hazards. In order to properly manage these hazards in the aquatic environment, a database is made available that integrates the concentration ranges for DR, which cause adverse effects for aquatic organisms, and the temporal variations of the ecotoxicological risks. To implement this database for the ecotoxicological risk assessment (ERA database), the required information for each DR is the predicted no effect concentrations (PNECs), along with the predicted environmental concentrations (PECs). The risk assessment is based on the ratio between the PNECs and the PECs. Adverse effect data or PNECs have been found in the publicly available literature for 45 substances. These ecotoxicity test data have been extracted from 125 different sources. This ERA database contains 1157 adverse effect data and 287 PNECs. The efficiency of this ERA database was tested with a data set coming from a simultaneous survey of WWTPs and the natural environment. In this data set, 26 DR were searched for in two WWTPs and in the river. On five sampling dates, concentrations measured in the river for 10 DR could pose environmental problems of which 7 were measured only downstream of WWTP outlets. From scientific literature and measurements, data implementation with unit homogenisation in a single database facilitates the actual ecotoxicological risk assessment, and may be useful for further risk coming from data arising from the future field survey. Moreover, the accumulation of a large ecotoxicity data set in a single database should not only improve knowledge of higher risk molecules but also supply an objective tool to help the rapid and efficient evaluation of the risk. Copyright © 2017 Elsevier B.V. All rights reserved.

Toward a unified approach to dose-response modeling in ecotoxicology.

Science.gov (United States)

Ritz, Christian

2010-01-01

This study reviews dose-response models that are used in ecotoxicology. The focus lies on clarification of differences and similarities between models, and as a side effect, their different guises in ecotoxicology are unravelled. A look at frequently used dose-response models reveals major discrepancies, among other things in naming conventions. Therefore, there is a need for a unified view on dose-response modeling in order to improve the understanding of it and to facilitate communication and comparison of findings across studies, thus realizing its full potential. This study attempts to establish a general framework that encompasses most dose-response models that are of interest to ecotoxicologists in practice. The framework includes commonly used models such as the log-logistic and Weibull models, but also features entire suites of models as found in various guidance documents. An outline on how the proposed framework can be implemented in statistical software systems is also provided.

Ecotoxicological evaluation of industrial port of Venice (Italy) sediment samples after a decontamination treatment

International Nuclear Information System (INIS)

Libralato, Giovanni; Losso, Chiara; Arizzi Novelli, Alessandra; Citron, Marta; Della Sala, Stefano; Zanotto, Emanuele; Cepak, Franka; Volpi Ghirardini, Annamaria

2008-01-01

This work assesses the ecotoxicological effects of polluted sediment after a decontamination treatment process using a new sediment washing technique. Sediment samples were collected from four sites in Marghera Port industrial channels (Venice, Italy). Ecotoxicological evaluations were performed with Vibrio fischeri and Crassostrea gigas bioassays. Whole sediment and elutriate were deemed as the most suitable environmental matrices for this study. Toxicity scores developed in the Lagoon of Venice for V. fischeri on whole sediment and for C. gigas on elutriate were considered for the final ranking of samples. Ecotoxicological results showed that the treated sediment samples presented both acute and sub-chronic toxicities, which were mainly attributed to the presence of some remaining chemicals such as metals and polyaromatic hydrocarbons. The acute toxicity ranged from low to medium, while the sub-chronic one from absent to very high, suggesting that treated sediments could not be reused in direct contact with seawater. - A sediment washing technique was assessed for port contaminated sediment remediation and reuse, indicating its reduced efficiency and the need for further improvements

Ecotoxicological evaluation of industrial port of Venice (Italy) sediment samples after a decontamination treatment

Energy Technology Data Exchange (ETDEWEB)

Libralato, Giovanni [Environmental Sciences Department, Venice University Ca Foscari, Campo della Celestia 2737/b, I-30122 Venice (Italy)], E-mail: giovanni.libralato@unive.it; Losso, Chiara; Arizzi Novelli, Alessandra [Environmental Sciences Department, Venice University Ca Foscari, Campo della Celestia 2737/b, I-30122 Venice (Italy); Citron, Marta; Della Sala, Stefano; Zanotto, Emanuele [Environmental Department, Venice Port Authority, Zattere 1401, I-30123, Venice (Italy); Cepak, Franka [Institute of Public Health, Vojkovo nabrezje 4a, 6000 Koper (Slovenia); Volpi Ghirardini, Annamaria [Environmental Sciences Department, Venice University Ca Foscari, Campo della Celestia 2737/b, I-30122 Venice (Italy)

2008-12-15

This work assesses the ecotoxicological effects of polluted sediment after a decontamination treatment process using a new sediment washing technique. Sediment samples were collected from four sites in Marghera Port industrial channels (Venice, Italy). Ecotoxicological evaluations were performed with Vibrio fischeri and Crassostrea gigas bioassays. Whole sediment and elutriate were deemed as the most suitable environmental matrices for this study. Toxicity scores developed in the Lagoon of Venice for V. fischeri on whole sediment and for C. gigas on elutriate were considered for the final ranking of samples. Ecotoxicological results showed that the treated sediment samples presented both acute and sub-chronic toxicities, which were mainly attributed to the presence of some remaining chemicals such as metals and polyaromatic hydrocarbons. The acute toxicity ranged from low to medium, while the sub-chronic one from absent to very high, suggesting that treated sediments could not be reused in direct contact with seawater. - A sediment washing technique was assessed for port contaminated sediment remediation and reuse, indicating its reduced efficiency and the need for further improvements.

Assessing the ecotoxicologic hazards of a pandemic influenza medical response.

Science.gov (United States)

Singer, Andrew C; Colizza, Vittoria; Schmitt, Heike; Andrews, Johanna; Balcan, Duygu; Huang, Wei E; Keller, Virginie D J; Vespignani, Alessandro; Williams, Richard J

2011-08-01

The global public health community has closely monitored the unfolding of the 2009 H1N1 influenza pandemic to best mitigate its impact on society. However, little attention has been given to the impact of this response on the environment. Antivirals and antibiotics prescribed to treat influenza are excreted into wastewater in a biologically active form, which presents a new and potentially significant ecotoxicologic challenge to microorganisms responsible for wastewater nutrient removal in wastewater treatment plants (WWTPs) and receiving rivers. We assessed the ecotoxicologic risks of a pandemic influenza medical response. To evaluate this risk, we coupled a global spatially structured epidemic model that simulates the quantities of antivirals and antibiotics used during an influenza pandemic of varying severity and a water quality model applied to the Thames catchment to determine predicted environmental concentrations. An additional model was then used to assess the effects of antibiotics on microorganisms in WWTPs and rivers. Consistent with expectations, our model projected a mild pandemic to exhibit a negligible ecotoxicologic hazard. In a moderate and severe pandemic, we projected WWTP toxicity to vary between 0-14% and 5-32% potentially affected fraction (PAF), respectively, and river toxicity to vary between 0-14% and 0-30% PAF, respectively, where PAF is the fraction of microbial species predicted to be growth inhibited (lower and upper 95% reference range). The current medical response to pandemic influenza might result in the discharge of insufficiently treated wastewater into receiving rivers, thereby increasing the risk of eutrophication and contamination of drinking water abstraction points. Widespread drugs in the environment could hasten the generation of drug resistance. Our results highlight the need for empirical data on the effects of antibiotics and antiviral medications on WWTPs and freshwater ecotoxicity.

Miniature circulatory systems: A new exposure system for ecotoxicological effect assessments in riverine organisms.

Science.gov (United States)

Feiner, Mona; Beggel, Sebastian; Geist, Juergen

2016-11-01

Long-term effect assessments in ecotoxicological investigations are important, yet there is a lack of suitable exposure systems for these experiments that can be used for riverine species. A cost-efficient miniature circulatory system was developed that was evaluated for its applicability in long-term exposures in 2 stream-dwelling species: brown trout (Salmo trutta) and an amphipod (Gammarus roeseli). In an egg-to-fry exposure of S. trutta, the toxicity of 2 reverse osmosis concentrates was investigated as examples. Control hatching rate of yolk sac fry was 75 ± 7% and thus complies with the Organisation for Economic Co-operation and Development validity criterion (≥66%). The reverse osmosis concentrates did not impair the hatching rate in any tested concentration. In G. roeseli, mortality rates remained below 20% during a 21-d cultivation, fulfilling the common validity criterion in ecotoxicological testing. Mortality was significantly lower when the species was fed with conditioned alder leaves instead of an artificial shrimp food. Finally, a toxicity test on G. roeseli using copper as the test substance revealed median lethal concentration (LC50) values of 156 μg/L after 96 h and 99 μg/L after 264 h, which is in line with literature findings using other accepted exposure units. In conclusion, the miniature circulatory system provides a novel and cost-efficient exposure system for long-term investigations on riverine species that may also be applicable for other species of fishes and macroinvertebrates. Environ Toxicol Chem 2016;35:2827-2833. © 2016 SETAC. © 2016 SETAC.

An efficient wave extrapolation method for tilted orthorhombic media using effective ellipsoidal models

KAUST Repository

Waheed, Umair bin

2014-08-01

The wavefield extrapolation operator for ellipsoidally anisotropic (EA) media offers significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate focusing for media of orthorhombic anisotropy. Therefore, we develop effective EA models that correctly capture the kinematic behavior of the wavefield for tilted orthorhombic (TOR) media. Specifically, we compute effective source-dependent velocities for the EA model using kinematic high-frequency representation of the TOR wavefield. The effective model allows us to use the cheaper EA wavefield extrapolation operator to obtain approximate wavefield solutions for a TOR model. Despite the fact that the effective EA models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TOR media, particularly for media of low to moderate complexity. We demonstrate applicability of the proposed approach on a layered TOR model.

An efficient wave extrapolation method for tilted orthorhombic media using effective ellipsoidal models

KAUST Repository

Waheed, Umair bin; Alkhalifah, Tariq Ali

2014-01-01

The wavefield extrapolation operator for ellipsoidally anisotropic (EA) media offers significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate focusing for media of orthorhombic anisotropy. Therefore, we develop effective EA models that correctly capture the kinematic behavior of the wavefield for tilted orthorhombic (TOR) media. Specifically, we compute effective source-dependent velocities for the EA model using kinematic high-frequency representation of the TOR wavefield. The effective model allows us to use the cheaper EA wavefield extrapolation operator to obtain approximate wavefield solutions for a TOR model. Despite the fact that the effective EA models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TOR media, particularly for media of low to moderate complexity. We demonstrate applicability of the proposed approach on a layered TOR model.

Towards a renewed research agenda in ecotoxicology

DEFF Research Database (Denmark)

Artigas, Joan; Arts, Gertie; Babut, Marc

2012-01-01

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologic...

Center for Ecotoxicological Research of Montenegro

International Nuclear Information System (INIS)

Vucinic, Z.

2006-01-01

PI Center for Ecotoxicological Research of Montenegro (CETI) is founded 1996's in accordance with Government policy, for the purpose to: Unite the problems of protecting the environment in one institution, Organize the monitoring of the all segments of environment (air, waters soils, waste, ionizing and non-ionizing radiation, noise measurements etc.), Organize control of human and animal food and toxicological analysis of all kind of samples, forensic analyses etc. To concentrate the expensive instrumental equipment and human resources in one institution. December 1996 - CETI founded by decision of Montenegrin government 1997-CETI starting with acquisition of equipment and education of the staff March of 1998 - Officially starting with the job and realization with Program's September 2004 - Took the ISO 9001:2000 Certificate and Accreditation under ISO/IEC 17025 in November 2004 Organisation Scheme of CETI: Laboratory For Ecotoxicological Research And Radiation Protection I. Department For Laboratory Diagnostic And Monitoring II. Department For Radiation Protection And Monitoring Sector For Administration Department For Economy Department For Administration Total number of Employs is 63 of permanent staff

Resilience in ecotoxicology: Toward a multiple equilibrium concept.

Science.gov (United States)

Bundschuh, Mirco; Schulz, Ralf; Schäfer, Ralf B; Allen, Craig R; Angeler, David G

2017-10-01

The term resilience describes stress-response patterns across scientific disciplines. In ecology, advances have been made to clearly define resilience based on underlying mechanistic assumptions. Engineering resilience (rebound) is used to describe the ability of organisms to recover from adverse conditions (disturbances), which is termed the rate of recovery. By contrast, the ecological resilience definition considers a systemic change, that is, when ecosystems reorganize into a new regime following disturbance. Under this new regime, structural and functional aspects change considerably relative to the previous regime, without recovery. In this context, resilience is an emergent property of complex systems. In the present study, we argue that both definitions and uses are appropriate in ecotoxicology, and although the differences are subtle, the implications and uses are profoundly different. We discuss resilience concepts in ecotoxicology, where the prevailing view of resilience is engineering resilience from chemical stress. Ecological resilience may also be useful for describing systemic ecological changes because of chemical stress. We present quantitative methods that allow ecotoxicologists and risk managers to assess whether an ecosystem faces an impending regime shift or whether it has already undergone such a shift. We contend that engineering and ecological resilience help to distinguish ecotoxicological responses to chemical stressors mechanistically and thus have implications for theory, policy, and application. Environ Toxicol Chem 2017;36:2574-2580. © 2017 SETAC. © 2017 SETAC.

Ecotoxicological, ecophysiological and biogeochemical fundamentals of risk assessment

International Nuclear Information System (INIS)

Bashkin, V.; Evstafjeva, E.

1995-01-01

A quantitative risk assessment (RA) for complex influence of different factors in heavy polluted regions is possible to carry out only on a basis of determination of various links of biogeochemical trophical chains and analysis of the whole biogeochemical structure of the region under study. As an integrative assessment, the human adaptability should be chosen because the majority of trophical chains are closed by man. The given integrative criteria includes biogeochemical, ecophysiological and ecotoxicological assessment of risk factors. Consequently, ecological-biogeochemical regionalization, ecophysiological and ecotoxicological monitoring of human population health are the important approaches to RA. These criteria should be conjugated with LCA of various industrial and agricultural products. At the ultimate degree, the given approaches are needed for areas where traditional pollutants (heavy metals, POPS, pesticides, fertilizers) are enforced sharply by radioactive pollution. Due to the complex influence of pollutants, it is impossible to use individual guidelines. For RA of these complex pollutants, the methods of human adaptability assessment to a polluted environment have to be carried out. These methods include biogeochemical, ecotoxicological and ecophysiological analysis of risk factors as well as quantitative uncertainty analysis. Furthermore, the modern statistical methods such as correlative graphs etc., have to be used for quantitative assessment of human adaptability to complex influence of pollutants. The results obtained in the Chernobyl region have shown the acceptability of suggested methods

Wavefield extrapolation in pseudo-depth domain

KAUST Repository

Ma, Xuxin; Alkhalifah, Tariq Ali

2012-01-01

Extrapolating seismic waves in Cartesian coordinate is prone to uneven spatial sampling, because the seismic wavelength tends to grow with depth, as velocity increase. We transform the vertical depth axis to a pseudo one using a velocity weighted mapping, which can effectively mitigate this wavelength variation. We derive acoustic wave equations in this new domain based on the direct transformation of the Laplacian derivatives, which admits solutions that are more accurate and stable than those derived from the kinematic transformation. The anisotropic versions of these equations allow us to isolate the vertical velocity influence and reduce its impact on modeling and imaging. The major benefit of extrapolating wavefields in pseudo-depth space is its near uniform wavelength as opposed to the normally dramatic change of wavelength with the conventional approach. Time wavefield extrapolation on a complex velocity shows some of the features of this approach.

Effect of soil compaction on the degradation and ecotoxicological impact of isoproturon

Science.gov (United States)

Mamy, L.; Vrignaud, P.; Cheviron, N.; Perreau, F.; Belkacem, M.; Brault, A.; Breuil, S.; Delarue, G.; Touton, I.; Chaplain, V.

2009-04-01

Soil is essentially a non-renewable resource which performs many functions and delivers services vital to human activities and ecosystems survival. However the capacity of soil to keep on fully performing its broad variety of crucial functions is damaged by several threats and, among them, chemical contamination by pesticides and compaction due to intensive agriculture practices. How these two threats could interact is largely unknown: compaction may modify the fate of pesticides in soil therefore their effects on the biological functioning of soil. The aim of this work was to study the effect of soil compaction on (1) the degradation of one herbicide, isoproturon (2) the ecotoxicological impact of this herbicide measured through two enzyme activities involved in C (beta-glucosidase) and N (urease) cycles in soil. Undisturbed soil cylinders were sampled in the 2-4 cm layer of La Cage experimental site (INRA, Versailles, France), under intensive agriculture practices. Several soil samples were prepared with different bulk density then treated with isoproturon (IPU). The samples were incubated at 18 ± 1°C in darkness for 63 days. At 0, 2, 7, 14, 28 and 63 days, the concentrations of isoproturon and of two of its main metabolites in soil (monodesmethyl-isoproturon, IPPMU; didesmethyl-isoproturon, IPPU), and the enzyme activities were measured. The results showed that there was no significant difference in IPU degradation under no and moderate soil compaction. IPU was less persistent in the highly compacted soil, but this soil had also higher humidity which is known to increase the degradation. Only one metabolite, IPPMU, was detected independently of the conditions of compaction. The compaction did not modify the effect of IPU on beta-glucosidase and urease activities in the long term, but microbial communities were probably the same in all the soil samples that were initially not compacted. The communities developed in durably compacted zones in the field are

Acute and chronic sensitivity to copper of a promising ecotoxicological model species, the annual killifish Nothobranchius furzeri.

Science.gov (United States)

Philippe, Charlotte; Grégoir, Arnout F; Janssens, Lizanne; Pinceel, Tom; De Boeck, Gudrun; Brendonck, Luc

2017-10-01

Nothobranchius furzeri is a promising model for ecotoxicological research due to the species' short life cycle and the production of drought-resistant eggs. Although the species is an emerging vertebrate fish model for several fundamental as well as applied research domains, its potential for ecotoxicological research has not yet been tested. The aim of this study was to characterise the acute and chronic sensitivity of this species to copper as compared to other model organisms. Effects of both acute and chronic copper exposure were tested on survival, life history and physiological traits. We report a 24h-LC 50 of 53.93µg Cu/L, which is situated within the sensitivity range of other model species such as Brook Trout, Fathead Minnow and Rainbow Trout. Moreover, in the full life cycle exposure, we show that an exposure concentration of 10.27µg/L did not cause acute adverse effects (96h), but did cause mortality after prolonged exposure (3-4 weeks). Also chronic, sublethal effects were observed, such as a reduction in growth rate, delayed maturation and postponed reproduction. Based on our results, we define the NOEC at 6.68µg Cu/L, making N. furzeri more sensitive to copper as compared to Brook Trout and Fathead Minnow. We found stimulatory effects on peak fecundity at subinhibitory levels of copper concentrations (hormesis). Finally, we found indications for detoxifying and copper-excreting mechanisms, demonstrating the ability of the fish to cope with this essential metal, even when exposed to stressful amounts. The successful application of current ecotoxicological protocols on N. furzeri and its sensitivity range comparable to that of other model organisms forms the basis to exploit this species in further ecotoxicological practices. Copyright © 2017 Elsevier Inc. All rights reserved.

Cosmogony as an extrapolation of magnetospheric research

International Nuclear Information System (INIS)

Alfven, H.

1984-03-01

A theory of the origin and evolution of the Solar System (Alfven and Arrhenius, 1975: 1976) which considered electromagnetic forces and plasma effects is revised in the light of new information supplied by space research. In situ measurements in the magnetospheres and solar wind have changed our views of basic properties of cosmic plasmas. These results can be extrapolated both outwards in space, to interstellar clouds, backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of some cloud properties which are essential for the early phases in the formation of stars and solar nebule. The latter extrapolation makes possible to approach the cosmogonic processes by extrapolation of (rather) well-known magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it seems possible to reconstruct certain events 4-5 billion years ago with an accuracy of a few percent. This will cause a change in our views of the evolution of the solar system.(author)

Distillation fraction-specific ecotoxicological evaluation of a paraffin-rich crude oil

International Nuclear Information System (INIS)

Erlacher, Elisabeth; Loibner, Andreas P.; Kendler, Romana; Scherr, Kerstin E.

2013-01-01

Crude oil is a complex mixture of petroleum hydrocarbons (PHC) with distinct chemical, physical and toxicological properties relevant for contaminated site risk assessment. Ecotoxicological effects of crude oil distillation fractions on luminescent bacteria (Vibrio fischeri), earthworms (Dendrobaena hortensis) and invertebrates (Heterocypris incongruens) were tested using two spiked soils and their elutriates. Fraction 2 (F2) had an equivalent carbon number (ECN) range of >10 to 16, and F3 from >16 to 39. F2 showed a substantially higher ecotoxicological effect than F3 for Vibrio and Dendrobaena. In contrast, severe inhibition of Heterocypris by the poorly soluble F3 is attributed to mechanical organ blockage. Immediate sequestration of PHC to the organic matter-rich soil effected reduced toxicity for all organisms. This study indicates that a more differentiated consideration (i) of PHC mixtures based on ECN range and (ii) of model soil properties employed for ecotoxicity testing should be included into PHC-contaminated site risk assessment. -- Highlights: ► Crude oil distillates show distinctly different effects on receptor organisms. ► Toxicity of the higher boiling point Fraction is attributed to physical effects. ► TPH sorption to the organic-matter rich soil occurred immediately after spiking. -- A differentiated consideration of the prevailing crude oil distillation fractions and of model soil properties employed for ecotoxicity testing should be included into the risk assessment of crude oil contaminated sites

Status seminar on BMBF-funded research projects in ecotoxicology. Proceedings; Statusseminar zum Foerderschwerpunkt `Oekotoxikologie` des BMBF. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Kirchner, M. [ed.; Bauer, H. [ed.

1995-07-01

Research projects in the field of ecotoxicology are presented, with particular regard to aquatic and terrestrial ecotoxicology. The report covers pollutant effects on plancton and fish and pollutant monitoring in streams. The effects, distribution and mobility of PAH, PCB and other pollutants in soils and pollutant concentrations in microorganisms are gone into. (SR) [Deutsch] Vorgestellt werden die Forschungsvorhaben zum Thema Oekotoxikologie. Schwerpunkte hierbei sind die aquatische Oekotoxokologie und die terrestrische Oekotoxikologie. Berichtet wird ueber die Wirkung von Fremdstoffen auf Plankton und Fischen, sowie die Bewertung der Belastung von Fliessgewaessern.Ausserdem wird die Wirkung, Verteilung und die Mobilitaet von PAK, PCB und anderen Schadstoffen in Boeden dargestellt, sowie die Belastung von Mikroorganismen mit Schadstoffen. (SR)

A comparative experimental approach to ecotoxicology in shallow-water and deep-sea holothurians suggests similar behavioural responses.

Science.gov (United States)

Brown, Alastair; Wright, Roseanna; Mevenkamp, Lisa; Hauton, Chris

2017-10-01

Exploration of deep-sea mineral resources is burgeoning, raising concerns regarding ecotoxicological impacts on deep-sea fauna. Assessing toxicity in deep-sea species is technologically challenging, which promotes interest in establishing shallow-water ecotoxicological proxy species. However, the effects of temperature and hydrostatic pressure on toxicity, and how adaptation to deep-sea environmental conditions might moderate these effects, are unknown. To address these uncertainties we assessed behavioural and physiological (antioxidant enzyme activity) responses to exposure to copper-spiked artificial sediments in a laboratory experiment using a shallow-water holothurian (Holothuria forskali), and in an in situ experiment using a deep-sea holothurian (Amperima sp.). Both species demonstrated sustained avoidance behaviour, evading contact with contaminated artificial sediment. However, A. sp. demonstrated sustained avoidance of 5mgl -1 copper-contaminated artificial sediment whereas H. forskali demonstrated only temporary avoidance of 5mgl -1 copper-contaminated artificial sediment, suggesting that H. forskali may be more tolerant of metal exposure over 96h. Nonetheless, the acute behavioural response appears consistent between the shallow-water species and the deep-sea species, suggesting that H. forskali may be a suitable ecotoxicological proxy for A. sp. in acute (≤24h) exposures, which may be representative of deep-sea mining impacts. No antioxidant response was observed in either species, which was interpreted to be the consequence of avoiding copper exposure. Although these data suggest that shallow-water taxa may be suitable ecotoxicological proxies for deep-sea taxa, differences in methodological and analytical approaches, and in sex and reproductive stage of experimental subjects, require caution in assessing the suitability of H. forskali as an ecotoxicological proxy for A. sp. Nonetheless, avoidance behaviour may have bioenergetic consequences that

Load Extrapolation During Operation for Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2008-01-01

In the recent years load extrapolation for wind turbines has been widely considered in the wind turbine industry. Loads on wind turbines during operations are normally dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. All these parameters...... must be taken into account when characteristic load effects during operation are determined. In the wind turbine standard IEC 61400-1 a method for load extrapolation using the peak over threshold method is recommended. In this paper this method is considered and some of the assumptions are examined...

Ecotoxicological, ecophysiological, and biogeochemical fundamentals of risk assessment

International Nuclear Information System (INIS)

Bashkin, V.N.; Kozlov, M.Ya.; Evstafjeva, E.V.

1993-01-01

Risk assessment (RA) influenced by different factors in radionuclide polluted regions is carried out by determining the biogeochemical structure of a region. Consequently, ecological-biogeochemical regionalization, ecotoxicological and ecophysiological monitoring of human population health are the important approach to RA. These criteria should conjugate with LCA of various industrial and agricultural products. Given fundamentals and approaches are needed for areas where traditional pollutants (heavy metals, pesticides, fertilizers, POPs etc) are enforced sharply by radioactive pollution. For RA of these complex pollutants, the methods of human adaptability to a polluted environment have been carried out. These techniques include biogeochemical, ecotoxicological, and ecophysiological analyses of risk factors as well as quantitative analysis of uncertainties using expert-modeling systems. Furthermore, the modern statistical methods are used for quantitative assessment of human adaptability to radioactive and nonradioactive pollutants. The results obtained in Chernobyl regions show the acceptability of these methods for risk assessment

Hierarchical responses to organic contaminants in aquatic ecotoxicological bioassays: from microcystins to biodegradation

OpenAIRE

Montenegro, Katia

2008-01-01

In this thesis I explore the ecotoxicological responses of aquatic organisms at different hierarchical levels to organic contaminants by means of bioassays. The bioassays use novel endpoints or approaches to elucidate the effects of exposure to contaminants and attempt to give mechanistic explanations that could be used to interpret effects at higher hierarchical scales. The sensitivity of population growth rate in the cyanobacteria species Microcystis aeruginosa to the herbicide glyp...

One-step lowrank wave extrapolation

KAUST Repository

Sindi, Ghada Atif

2014-01-01

Wavefield extrapolation is at the heart of modeling, imaging, and Full waveform inversion. Spectral methods gained well deserved attention due to their dispersion free solutions and their natural handling of anisotropic media. We propose a scheme a modified one-step lowrank wave extrapolation using Shanks transform in isotropic, and anisotropic media. Specifically, we utilize a velocity gradient term to add to the accuracy of the phase approximation function in the spectral implementation. With the higher accuracy, we can utilize larger time steps and make the extrapolation more efficient. Applications to models with strong inhomogeneity and considerable anisotropy demonstrates the utility of the approach.

Chemical control of vegetation on urban sites: agronomic and ecotoxicological aspects

International Nuclear Information System (INIS)

Zanin, G.; Otto, S.

1996-01-01

The problem of the chemical control of spontaneous vegetation on urban sites is tackled. A method is presented to identify the best herbicides under both the agronomic and ecotoxicological aspects. Selection of the herbicides from the agronomic point of view is on the basis of the qualitative characteristics of the vegetation (life-form types periodicity types botanical composition), surveyed at 5 different times on the year while selection from the environmental viewpoint is based on an evaluation integrated with a series of ecotoxicological indices. The best solution was tested in a pilot area and the contamination of the water compartment evaluated both on entering and leaving the water treatment works

Assessing the relevance of ecotoxicological studies for regulatory decision making.

Science.gov (United States)

Rudén, Christina; Adams, Julie; Ågerstrand, Marlene; Brock, Theo Cm; Poulsen, Veronique; Schlekat, Christian E; Wheeler, James R; Henry, Tala R

2017-07-01

Regulatory policies in many parts of the world recognize either the utility of or the mandate that all available studies be considered in environmental or ecological hazard and risk assessment (ERA) of chemicals, including studies from the peer-reviewed literature. Consequently, a vast array of different studies and data types need to be considered. The first steps in the evaluation process involve determining whether the study is relevant to the ERA and sufficiently reliable. Relevance evaluation is typically performed using existing guidance but involves application of "expert judgment" by risk assessors. In the present paper, we review published guidance for relevance evaluation and, on the basis of the practical experience within the group of authors, we identify additional aspects and further develop already proposed aspects that should be considered when conducting a relevance assessment for ecotoxicological studies. From a regulatory point of view, the overarching key aspect of relevance concerns the ability to directly or indirectly use the study in ERA with the purpose of addressing specific protection goals and ultimately regulatory decision making. Because ERA schemes are based on the appropriate linking of exposure and effect estimates, important features of ecotoxicological studies relate to exposure relevance and biological relevance. Exposure relevance addresses the representativeness of the test substance, environmental exposure media, and exposure regime. Biological relevance deals with the environmental significance of the test organism and the endpoints selected, the ecological realism of the test conditions simulated in the study, as well as a mechanistic link of treatment-related effects for endpoints to the protection goal identified in the ERA. In addition, uncertainties associated with relevance should be considered in the assessment. A systematic and transparent assessment of relevance is needed for regulatory decision making. The relevance

Wavefield extrapolation in pseudodepth domain

KAUST Repository

Ma, Xuxin

2013-02-01

Wavefields are commonly computed in the Cartesian coordinate frame. Its efficiency is inherently limited due to spatial oversampling in deep layers, where the velocity is high and wavelengths are long. To alleviate this computational waste due to uneven wavelength sampling, we convert the vertical axis of the conventional domain from depth to vertical time or pseudodepth. This creates a nonorthognal Riemannian coordinate system. Isotropic and anisotropic wavefields can be extrapolated in the new coordinate frame with improved efficiency and good consistency with Cartesian domain extrapolation results. Prestack depth migrations are also evaluated based on the wavefield extrapolation in the pseudodepth domain.© 2013 Society of Exploration Geophysicists. All rights reserved.

Ecorad 2001. Radioecology/ ecotoxicology in continental and estuarine media

International Nuclear Information System (INIS)

2001-11-01

This conference about radioecology is divided in eight sessions that concern the following subjects: behaviour and transfer of radionuclides in soil, in terrestrial ecosystems (plants and animal transfers), in freshwater ecosystems, in estuaries are the subjects of the four first sessions. The effects of toxicants in environment are detailed in the fifth session. The sixth session is devoted to the methods of measurement of environmental radioactivity. The seventh session is relative to the consequences of accidental and chronicle situations (Chernobyl consequences, countermeasures and decontamination). This conference ends with the ethical aspects of environmental radio ecotoxicology with the eighth session. (N.C.)

Environmental impact of industrial sludge stabilization/solidification products: chemical or ecotoxicological hazard evaluation?

Science.gov (United States)

Silva, Marcos A R; Testolin, Renan C; Godinho-Castro, Alcione P; Corrêa, Albertina X R; Radetski, Claudemir M

2011-09-15

Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of this study was to compare the toxicity classifications based on the chemical and ecotoxicological characterization of four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. To classify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulations were adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids) which were carried out with soluble and leaching fractions. In some cases the hazardous potential of industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics and automotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicity tests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impact was overestimated, since the S/S products of the textile sludges were chemically classified as non-inert (but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae. From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulations related to solid waste classification based on leachability and solubility tests do not ensure reliable results with respect to environmental protection; (ii) the two-step process was very effective in terms of metal immobilization, even at higher metal-concentrations. Considering that S/S products will be subject to environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminants release from these products with a view to avoiding environmental impact given the unreliability of ecotoxicological estimations originating from chemical analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Builtin vs. auxiliary detection of extrapolation risk.

Energy Technology Data Exchange (ETDEWEB)

Munson, Miles Arthur; Kegelmeyer, W. Philip,

2013-02-01

A key assumption in supervised machine learning is that future data will be similar to historical data. This assumption is often false in real world applications, and as a result, prediction models often return predictions that are extrapolations. We compare four approaches to estimating extrapolation risk for machine learning predictions. Two builtin methods use information available from the classification model to decide if the model would be extrapolating for an input data point. The other two build auxiliary models to supplement the classification model and explicitly model extrapolation risk. Experiments with synthetic and real data sets show that the auxiliary models are more reliable risk detectors. To best safeguard against extrapolating predictions, however, we recommend combining builtin and auxiliary diagnostics.

Motion extrapolation in the central fovea.

Directory of Open Access Journals (Sweden)

Zhuanghua Shi

Full Text Available Neural transmission latency would introduce a spatial lag when an object moves across the visual field, if the latency was not compensated. A visual predictive mechanism has been proposed, which overcomes such spatial lag by extrapolating the position of the moving object forward. However, a forward position shift is often absent if the object abruptly stops moving (motion-termination. A recent "correction-for-extrapolation" hypothesis suggests that the absence of forward shifts is caused by sensory signals representing 'failed' predictions. Thus far, this hypothesis has been tested only for extra-foveal retinal locations. We tested this hypothesis using two foveal scotomas: scotoma to dim light and scotoma to blue light. We found that the perceived position of a dim dot is extrapolated into the fovea during motion-termination. Next, we compared the perceived position shifts of a blue versus a green moving dot. As predicted the extrapolation at motion-termination was only found with the blue moving dot. The results provide new evidence for the correction-for-extrapolation hypothesis for the region with highest spatial acuity, the fovea.

Combined effect of external irradiation and radiostrontium administration (extrapolation of experimental data)

International Nuclear Information System (INIS)

Kiradzhiev, G.

1987-01-01

Assessment was made of the activities of strontium-89 and strontium-90, which may aggravate the effect of external irradiation, causing changes in peripheral blood leucocytes. Extrapolation of the results was carried out on the basis of the so called radiosensitivity coefficients (laboratory rat/man). Inference is drawn that summing of the effects of the radiation factors may be expected in cases of external irradiation with 100 Gy and oral administration of 150-200 MBq strontium-89 or 60-90 MBq strontium-90 and through the air passages of 110-150 MBq strontium-89 or 40-60 MBq strontium-90

Procedural Guidelines for Ecological Risk Assessments at U.S. Army Sites. Volume 1.

Science.gov (United States)

1994-12-01

altered chemically or physically. Stressors may also result from management practices such as harvesting of fishery or forest resources, or cultivation ...Inferring population-level significance from individual- level effects: An extrapolation from fisheries science to ecotoxicology . p. 289-300. In G.W

Use of ecotoxicological screening action levels in ecological risk assessment at Los Alamos National Laboratory

International Nuclear Information System (INIS)

Ferenbauah, R.; Ebinger, M.; Gallegos, A.; Hansen, W.; Myers, O.; Wenzel, W.

1995-01-01

Regulatory drivers found in several environmental statutes require that ecological risk assessment and Natural Resource Damage Assessment be performed to assess potential environmental impact from contaminated sites and from proposed remedial alternatives. At Los Alamos National Laboratory, the initial phase of the ecological risk assessment process required preliminary evaluation of contaminated sites to determine whether potential for ecological impact exists. The preliminary evaluations were made using Ecotoxicological Screening Action Levels (ESALS) calculated as a function of reference toxicity dose, body weight, food/water/air intake, and fraction of soil intake with food. Reference toxicity doses were derived from the Environmental Protection Agency Integrated Risk Information System (IRIS) and Health Effects Assessment Summary Tables (HEAST) toxicology databases. Other parameters required for ESAL calculations were derived from physiological, metabolic, and behavioral data available in the literature. The Los Alamos ESALs were derived for guilds of animals with similar behavioral patterns, which were identified from natural resource survey data collected at Los Alamos. Subsequent to development of Ecotoxicological Screening Action Levels, Hazard Quotients, which are ratios of soil concentrations to Ecotoxicological Screening Action Levels, were calculated for potential contaminants of concern. The Hazard Quotients were used to identify which potential contaminants of concern should be evaluated further for ecological impact. There is potential for ecological impact when the Hazard Quotient is equal to or greater than one

Peculiarities of ecotoxicological assessment nanoagrochemicals used in crop production

Directory of Open Access Journals (Sweden)

N. Makarenko

2016-06-01

Full Text Available The article presents the results of studying the toxic effect of nanoagrochemicals on the processes of a plant's cell division, growth and development of plants at the early stages of ontogeny. It can be assume that the toxic effect of nanoagrochemicals depends on the size and structure of the nanoparticles, which are included in their composition: the toxic effect is stronger, the smaller the size of the nanoparticles is; nanocomposites of crystal structure are more toxic compared to nanocomposites of amorphous structure. Nanoagrochemicals ecotoxicological risk assessment should not be based only on the study of the dependence “dose-effect” on the level of the organism and population; it should include the research of the toxic process, starting from the level of the cell and its organelles.

Gravitactic orientation of Euglena gracilis – a sensitive endpoint for ecotoxicological assessment of water pollutants

Directory of Open Access Journals (Sweden)

Aziz eUllah

2013-12-01

Full Text Available Pollution of aquatic environments with natural and anthropogenically produced substances is one of the major environmental problems of the world. In many countries the decreasing quantity of water coupled with its increasing usage in multiple sectors has adversely affected water quality and caused problems of water pollution. Polluted water has been a main cause of adverse effects on plants, animals and humans throughout the world. Physicochemical analysis of water, which is a common method used for quality assessment of water, alone may not be enough as it cannot evaluate the impact on living organisms. Therefore, bioassessment of water and wastewater quality is considered to be essential to reflect the ultimate effects on living organisms. Many organisms like bacteria, algae, fish, invertebrates and protozoan are used as bioassay organisms for assessment of water quality. This review article elucidates the use of Euglena gracilis, a freshwater motile flagellate of the phylum Euglenophyta, as a suitable organism in ecotoxicological studies with special emphasis on its gravitactic orientation as a sensitive end point in ecotoxicological assessment of water pollutants.

Ecotoxicological Assessment of Sediment Leachates of Small Watercourses in the Brno City Suburban Area (South Moravia, Czech Republic

Directory of Open Access Journals (Sweden)

Miroslava Beklová

2010-01-01

Full Text Available Sediments of two small watercourses Leskava and Troubsky Brook in the Brno city suburban area were examined for their ecotoxicity. Using a standard procedure, extracts of the sediments were prepared for diagnostic tests. These extracts were tested for acute toxicity to fresh-water organisms. The ecotoxicological tests were performed on the fresh-water alga Pseudokirchneriella subcapitata, the vascular water plant Lemna minor, on a representative of invertebrates – the water flea Daphnia magna and on the Xenopus laevis frog embryo and luminiscent Vibrio fischeri bacteria. Possible toxic effects were evaluated using the test determining the inhibition of the growth of white mustard root Sinapis alba. Results of ecotoxicological assessment of sediment leachates showed that their quality varied significantly during the year. Differences were found between results of sediment evaluations from different collection profiles, which may indicate effects of point source pollution. Of the ecotoxicological tests used, the most sensitive organisms included the green algae Pseudokirchneriella subcapitata, bioluminiscent bacteria Vibrio fischeri and the African clawed frog Xenopus laevis. The highest concentrations of arsenic were found by chemical analysis in both spring and autumn sediment leachate samples collected at Site L1 (Leskava. The highest organic pollutant concentrations were found in autumn sediment leachate samples from Site L1. In total PAH sums, phenanthrene was the dominant pollutant at all the sites investigated.

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments

Energy Technology Data Exchange (ETDEWEB)

Perrodin, Yves, E-mail: perrodin@entpe.fr [Universite de Lyon, ENTPE, CNRS, UMR 5023 LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); Donguy, Gilles [Universite de Lyon, ENTPE, CNRS, UMR 5023 LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); Bazin, Christine [INSAVALOR, 20 avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Volatier, Laurence; Durrieu, Claude [Universite de Lyon, ENTPE, CNRS, UMR 5023 LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); Bony, Sylvie; Devaux, Alain [Universite de Lyon, ENTPE, CNRS, UMR 5023 LEHNA, 2 rue Maurice Audin, 69518 Vaulx-en-Velin (France); INRA, USC IGH, UMR LEHNA, 2, rue Maurice Audin, 69518 Vaulx-en-Velin (France); Abdelghafour, Mohammed; Moretto, Robert [INSAVALOR, 20 avenue Albert Einstein, 69621 Villeurbanne Cedex (France)

2012-08-01

The dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the 'substances' approach derived from the European methodology for assessing new substances placed on the market, and the 'matrix' approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, Horizontal-Ellipsis ). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments '1' and '2' presented a low risk for

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments

International Nuclear Information System (INIS)

Perrodin, Yves; Donguy, Gilles; Bazin, Christine; Volatier, Laurence; Durrieu, Claude; Bony, Sylvie; Devaux, Alain; Abdelghafour, Mohammed; Moretto, Robert

2012-01-01

The dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the “substances” approach derived from the European methodology for assessing new substances placed on the market, and the “matrix” approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, …). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments “1” and “2” presented a low risk for the peripheral aquatic ecosystems while

SU-D-204-02: BED Consistent Extrapolation of Mean Dose Tolerances

Energy Technology Data Exchange (ETDEWEB)

Perko, Z; Bortfeld, T; Hong, T; Wolfgang, J; Unkelbach, J [Massachusetts General Hospital, Boston, MA (United States)

2016-06-15

Purpose: The safe use of radiotherapy requires the knowledge of tolerable organ doses. For experimental fractionation schemes (e.g. hypofractionation) these are typically extrapolated from traditional fractionation schedules using the Biologically Effective Dose (BED) model. This work demonstrates that using the mean dose in the standard BED equation may overestimate tolerances, potentially leading to unsafe treatments. Instead, extrapolation of mean dose tolerances should take the spatial dose distribution into account. Methods: A formula has been derived to extrapolate mean physical dose constraints such that they are mean BED equivalent. This formula constitutes a modified BED equation where the influence of the spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 14 liver cancer patients previously treated with proton therapy in 5 or 15 fractions, for whom also photon IMRT plans were available. Results: Our work has two main implications. First, in typical clinical plans the dose distribution can have significant effects. When mean dose tolerances are extrapolated from standard fractionation towards hypofractionation they can be overestimated by 10–15%. Second, the shape difference between photon and proton dose distributions can cause 30–40% differences in mean physical dose for plans having the same mean BED. The combined effect when extrapolating proton doses to mean BED equivalent photon doses in traditional 35 fraction regimens resulted in up to 7–8 Gy higher doses than when applying the standard BED formula. This can potentially lead to unsafe treatments (in 1 of the 14 analyzed plans the liver mean dose was above its 32 Gy tolerance). Conclusion: The shape effect should be accounted for to avoid unsafe overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. In addition, tolerances established for a given treatment modality cannot

An efficient wave extrapolation method for anisotropic media with tilt

KAUST Repository

Waheed, Umair bin

2015-03-23

Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

An efficient wave extrapolation method for anisotropic media with tilt

KAUST Repository

Waheed, Umair bin; Alkhalifah, Tariq Ali

2015-01-01

Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

Review of the ecotoxicological effects of emerging contaminants to soil biota.

Science.gov (United States)

Gomes, Ana R; Justino, Celine; Rocha-Santos, Teresa; Freitas, Ana C; Duarte, Armando C; Pereira, Ruth

2017-08-24

In recent years, emerging contaminants (e.g. pesticides and their metabolites, pharmaceuticals, personal and house care products, life-style compounds, food additives, industrial products and wastes, as well as nanomaterials) have become a problem to the environment. In fact, the cumulative use of a panoply of chemical substances in agriculture, industrial activities, in our homes and in health care services has led to their recent appearance in detectable levels in soils, surface, and groundwater resources, with unpredictable consequences for these ecosystems. Few data exist regarding the toxicity and potential for bioaccumulation in biota. When available, data were obtained only for some representatives of the main groups of chemical substances, and for a limited number of species, following non-standard protocols. This makes difficult the calculation of predicted no effect concentrations (PNEC) and the existence of sufficient data to set limits for their release into the environment. This is particularly concerning for the soil compartment, since only recently the scientific community, regulators, and the public have realised the importance of protecting this natural resource and its services to guarantee the sustainability of terrestrial ecosystems and human well-being. In this context, this review paper aims to identify the major groups of soil emerging contaminants, their sources, pathways and receptors, and in parallel to analyse existing ecotoxicological data for soil biota.

Looking at biological community level to improve ecotoxicological assessment of freshwater sediments: report on a first French-Swiss workshop.

Science.gov (United States)

Pesce, Stéphane; Perceval, Olivier; Bonnineau, Chloé; Casado-Martinez, Carmen; Dabrin, Aymeric; Lyautey, Emilie; Naffrechoux, Emmanuel; Ferrari, Benoit J D

2018-01-01

The first French-Swiss workshop on ecotoxicology of freshwater sediment communities was co-organized by the French Research Institute of Science and Technology for Environment and Agriculture (Irstea) and the Swiss Centre for Applied Ecotoxicology (Ecotox Centre EAWAG-EPFL) in Villié-Morgon (Beaujolais Region, France) on April 27-28, 2017. The workshop brought together scientists working in different fields of expertise (ecotoxicologists, ecologists, environmental chemists…), environmental stakeholder groups and managers, as well as economic players (start-ups and consultancies) to better connect research needs of potential end-users with research outputs. The objectives of this workshop were (i) to establish the state of the art of research in the characterization of sediment contamination and in the evaluation of the effects on sediment-associated biological communities and ecosystem functioning and (ii) to give an overview of the French and Swiss regulations dealing with the assessment of contaminated sediments in freshwater ecosystems. The ultimate goal was to collectively identify research needs and knowledge gaps, as well as to highlight ways to improve the ecotoxicological assessment of sediments in freshwater environments by further considering the structure and functions of associated microbial and invertebrate communities.

Aquatic ecotoxicology: what has been accomplished and what lies ahead? An Eastern Canada historical perspective

Directory of Open Access Journals (Sweden)

Christian Blaise

2013-10-01

Full Text Available Our recent history shows that degradation of aquatic ecosystems essentially stems from industrialization, urbanization and increasing human populations. After a first industrial boom in the late 19th century, contamination pressures on receiving waters now appear to be continual because of expanding economies and technologies developing at the planetary scale. Given the diversity of issues, problems and challenges facing water quality today because of complex waste and chemical discharges into waterways, aquatic ecotoxicology has blossomed with time into a more mature discipline of the environmental sciences. Its two fundamental pillars, bioassays and biomarkers, have become essential tools that allow the determination of numerous and versatile effects measurements. Herein, we demonstrate some of the ways in which thesetools have been applied and how they have evolved over the past decades to appraise the ecotoxicity of contaminants impacting aquatic systems. Examples discussed are largely reflective of work conducted in the Environment Canada (EC laboratories (Saint-Lawrence Centre, Montréal, Canada. Success stories include improvement of industrial effluent quality contributing to beluga whale population recovery in the Saint-Lawrence River, biomarker field studies conducted with endemic and caged bivalves to more fully comprehend urban effluent adverse effects, and increased discernment on the hazard potential posed by emerging classes of chemicals. Ecotoxicology continues to be confronted with diverse issues and needs related to a myriad of chemical contaminants released to aquatic environments worldwide. To cope with these, ecotoxicology will have to bank on new tools (e.g., toxicogenomics, bio-informatics, modelingand become more interdisciplinary by taking into account knowledge provided by other disciplines (e.g., ecology, chemistry, climatology, microbiology in order to more fully understand and adequately interpret hazard. This will

Line-of-sight extrapolation noise in dust polarization

Energy Technology Data Exchange (ETDEWEB)

Poh, Jason; Dodelson, Scott

2017-05-19

The B-modes of polarization at frequencies ranging from 50-1000 GHz are produced by Galactic dust, lensing of primordial E-modes in the cosmic microwave background (CMB) by intervening large scale structure, and possibly by primordial B-modes in the CMB imprinted by gravitational waves produced during inflation. The conventional method used to separate the dust component of the signal is to assume that the signal at high frequencies (e.g., 350 GHz) is due solely to dust and then extrapolate the signal down to lower frequency (e.g., 150 GHz) using the measured scaling of the polarized dust signal amplitude with frequency. For typical Galactic thermal dust temperatures of about 20K, these frequencies are not fully in the Rayleigh-Jeans limit. Therefore, deviations in the dust cloud temperatures from cloud to cloud will lead to different scaling factors for clouds of different temperatures. Hence, when multiple clouds of different temperatures and polarization angles contribute to the integrated line-of-sight polarization signal, the relative contribution of individual clouds to the integrated signal can change between frequencies. This can cause the integrated signal to be decorrelated in both amplitude and direction when extrapolating in frequency. Here we carry out a Monte Carlo analysis on the impact of this line-of-sight extrapolation noise, enabling us to quantify its effect. Using results from the Planck experiment, we find that this effect is small, more than an order of magnitude smaller than the current uncertainties. However, line-of-sight extrapolation noise may be a significant source of uncertainty in future low-noise primordial B-mode experiments. Scaling from Planck results, we find that accounting for this uncertainty becomes potentially important when experiments are sensitive to primordial B-mode signals with amplitude r < 0.0015 .

Arsenic rich iron plaque on macrophyte roots - an ecotoxicological risk?

International Nuclear Information System (INIS)

Taggart, M.A.; Mateo, R.; Charnock, J.M.; Bahrami, F.; Green, A.J.; Meharg, A.A.

2009-01-01

Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcollar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root + plaque' material in excess of 1000 mg kg -1 , and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcollar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque. - Accumulation of metals with iron plaque on macrophyte roots in wetlands poses an ecotoxicological risk to certain herbivores

Ecotoxicological study of used lubricating oil

International Nuclear Information System (INIS)

Wong, P.K.; Chan, W.L.; Wang, J.; Wong, C.K.

1995-01-01

Used lubricating oil is more toxic than crude oil and fuel oil since it contains comparatively high levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs). No detail toxicological study has been conducted to evaluate the hazards of used lubricating oil to the environment. This study reports a battery of bioassays using bacteria (Microtox test and Mutatox test), algae, amphipod and shrimp larvae to determine the toxicity of water soluble fraction of used lubricating oil. The results will be used to formulate a complete and extensive ecotoxicological assessment of the impacts of used lubricating oil on aquatic environment

Ecotoxicologic diagnosis of a sealed municipal district landfill

International Nuclear Information System (INIS)

Hernandez, A. J.; Perez-Leblic, M. I.; Bartolome, C.; Pastor, J.

2009-01-01

Assessing the environmental impact of a soil-topped landfill requires and ecotoxicologic diagnosis. Here we describe a set of protocols for such a diagnosis as well as their application to a real case ( the urban soil waste, USW, landfill of Getafe, Madrid). Since their initial sealing some 20 years ago with soils taken from the surroundings, waste deposition has continued in most USW landfills of the Comunidad de Madrid. (Author)

DarT: The embryo test with the Zebrafish Danio rerio--a general model in ecotoxicology and toxicology.

Science.gov (United States)

Nagel, Roland

2002-01-01

The acute fish test is an animal test whose ecotoxicological relevance is worthy of discussion. The primary aim of protection in ecotoxicology is the population and not the individual. Furthermore the concentration of pollutants in the environment is normally not in the lethal range. Therefore the acute fish test covers solely the situation after chemical spills. Nevertheless, acute fish toxicity data still belong to the base set used for the assessment of chemicals. The embryo test with the zebrafish Danio rerio (DarT) is recommended as a substitute for the acute fish test. For validation an international laboratory comparison test was carried out. A summary of the results is presented in this paper. Based on the promising results of testing chemicals and waste water the test design was validated by the DIN-working group "7.6 Fischei-Test". A normed test guideline for testing waste water with fish is available. The test duration is short (48 h) and within the test different toxicological endpoints can be examined. Endpoints from the embryo test are suitable for QSAR-studies. Besides the use in ecotoxicology the introduction as a toxicological model was investigated. Disturbance of pigmentation and effects on the frequency of heart-beat were examined. A further important application is testing of teratogenic chemicals. Based on the results DarT could be a screening test within preclinical studies.

Properties of an extrapolation chamber for beta radiation dosimetry

International Nuclear Information System (INIS)

Caldas, L.V.E.

The properties of a commercial extrapolation chamber were studied, and the possibility is shown of its use in beta radiation dosimetry. The chamber calibration factors were determined for several sources ( 90 Sr, 90 Y- 204 Tl and 147 Pm) making known the dependence of its response on the energy of the incident radiation. Extrapolation curves allow to obtain independence on energy for each source. One of such curves, shown for the 90 Sr- 90 Y source at 50 cm from the detector, is obtained through the variation of the chamber window thickness and the extrapolation to the null distance (determined graphically). Different curves shown also: 1) the dependence of the calibration factor on the average energy of beta radiation; 2) the variation of ionization current with the distance between the chamber and the sources; 3) the effect of the collecting electrode area on the value of calibration factors for the different sources. (I.C.R.) [pt

Recommended approaches to the scientific evaluation of ecotoxicological hazards and risks of endocrine-active substances

Science.gov (United States)

Matthiessen, Peter; Ankley, Gerald T.; Biever, Ronald C.; Bjerregaard, Poul; Borgert, Christopher; Brugger, Kristin; Blankinship, Amy; Chambers, Janice; Coady, Katherine K.; Constantine, Lisa; Dang, Zhichao; Denslow, Nancy D.; Dreier, David; Dungey, Steve; Gray, L. Earl; Gross, Melanie; Guiney, Patrick D.; Hecker, Markus; Holbech, Henrik; Iguchi, Taisen; Kadlec, Sarah; Karouna-Renier, Natalie K.; Katsiadaki, Ioanna; Kawashima, Yukio; Kloas, Werner; Krueger, Henry; Kumar, Anu; Lagadic, Laurent; Leopold, Annegaaike; Levine, Steven L.; Maack, Gerd; Marty, Sue; Meador, James P.; Mihaich, Ellen; Odum, Jenny; Ortego, Lisa; Parrott, Joanne L.; Pickford, Daniel; Roberts, Mike; Schaefers, Christoph; Schwarz, Tamar; Solomon, Keith; Verslycke, Tim; Weltje, Lennart; Wheeler, James R.; Williams, Mike; Wolf, Jeffery C.; Yamazaki, Kunihiko

2017-01-01

A SETAC Pellston Workshop® “Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA)” was held in February 2016 in Pensacola, Florida, USA. The primary objective of the workshop was to provide advice, based on current scientific understanding, to regulators and policy makers; the aim being to make considered, informed decisions on whether to select an ecotoxicological hazard- or a risk-based approach for regulating a given endocrine-disrupting substance (EDS) under review. The workshop additionally considered recent developments in the identification of EDS. Case studies were undertaken on 6 endocrine-active substances (EAS—not necessarily proven EDS, but substances known to interact directly with the endocrine system) that are representative of a range of perturbations of the endocrine system and considered to be data rich in relevant information at multiple biological levels of organization for 1 or more ecologically relevant taxa. The substances selected were 17α-ethinylestradiol, perchlorate, propiconazole, 17β-trenbolone, tributyltin, and vinclozolin. The 6 case studies were not comprehensive safety evaluations but provided foundations for clarifying key issues and procedures that should be considered when assessing the ecotoxicological hazards and risks of EAS and EDS. The workshop also highlighted areas of scientific uncertainty, and made specific recommendations for research and methods-development to resolve some of the identified issues. The present paper provides broad guidance for scientists in regulatory authorities, industry, and academia on issues likely to arise during the ecotoxicological hazard and risk assessment of EAS and EDS. The primary conclusion of this paper, and of the SETAC Pellston Workshop on which it is based, is that if data on environmental exposure, effects on sensitive species and life-stages, delayed effects, and effects at low concentrations are robust, initiating environmental risk

Bioavailability and mobility of organic contaminants in soil: new three-step ecotoxicological evaluation.

Science.gov (United States)

Prokop, Zbyněk; Nečasová, Anežka; Klánová, Jana; Čupr, Pavel

2016-03-01

A novel approach was developed for rapid assessment of bioavailability and potential mobility of contaminants in soil. The response of the same test organism to the organic extract, water extract and solid phase of soil was recorded and compared. This approach was designed to give an initial estimate of the total organic toxicity (response to organic extractable fraction), as well as the mobile (response to water extract) and bioavailable fraction (response to solid phase) of soil samples. Eighteen soil samples with different levels of pollution and content of organic carbon were selected to validate the novel three-step ecotoxicological evaluation approach. All samples were chemically analysed for priority contaminants, including aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) and dichlordiphenyltrichloroethane (DDT). The ecotoxicological evaluation involved determination of toxicity of the organic, mobile and bioavailable fractions of soil to the test organism, bacterium Bacillus cereus. We found a good correlation between the chemical analysis and the toxicity of organic extract. The low toxicity of water extracts indicated low water solubility, and thus, low potential mobility of toxic contaminants present in the soil samples. The toxicity of the bioavailable fraction was significantly greater than the toxicity of water-soluble (mobile) fraction of the contaminants as deduced from comparing untreated samples and water extracts. The bioavailability of the contaminants decreased with increasing concentrations of organic carbon in evaluated soil samples. In conclusion, the three-step ecotoxicological evaluation utilised in this study can give a quick insight into soil contamination in context with bioavailability and mobility of the contaminants present. This information can be useful for hazard identification and risk assessment of soil-associated contaminants. Graphical Abstract New three-step ecotoxicological

A Vision and Strategy:Predictive Ecotoxicology in the 21st Century

Science.gov (United States)

The manuscript provides an introduction and overview for a series of five papers resulting from a SETAC Pellston Workshop titled A Vision and Strategy for Predictive Ecotoxicology in the 21st Century: Defining Adverse Outcome Pathways Associated with Ecological Risk. It proposes...

Chemical and ecotoxicological assessments of water samples before and after being processed by a Water Treatment Plant

Directory of Open Access Journals (Sweden)

Regina Teresa Rosim Monteiro

2014-01-01

Full Text Available Physicochemical and ecotoxicological measurements were employed to appraise the water quality of the Corumbataí River raw water (RW intake, and that of its filtered (FW and treated (TW waters, processed by the Water Treatment Plant (WTP of Piracicaba (SP, Brazil during 2010. Some herbicides: ametrine, atrazine, simazine and tebuthiuron, were measured, with levels ranging from 0.01 to 10.3 µg L-1 . These were lower than those required to produce ecotoxicological effects to aquatic life based on published literature. Similarly, trihalomethanes, such as chloroform and bromodichloromethane produced as a result of the WTP process were also shown to be present in concentrations that would neither harm environmental nor human health. Elevated free chlorine concentrations found in FW and TW were credibly responsible for toxicity effects observed in algae and daphnids. (Pseudokirchneriella subcapitata and Daphnia magna. In contrast, results of toxicity testing conducted with Hydra attenuata suggested that this organism is resistant to free chorine and could be used for drinking water evaluations. Coupling bioassays with chemical analyses proved valuable to uncover putative cause-effect relationships existing between physical, chemical and toxic results, as well as in optimizing data interpretation of water quality.

Arsenic rich iron plaque on macrophyte roots - an ecotoxicological risk?

Energy Technology Data Exchange (ETDEWEB)

Taggart, M.A. [School of Biological Sciences, University of Aberdeen, Cruickshank Bld, St Machar Drive, Aberdeen, AB24 3UU (United Kingdom); Instituto de Investigacion en Recursos Cinegeticos, IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real (Spain)], E-mail: mark.taggart@uclm.es; Mateo, R. [Instituto de Investigacion en Recursos Cinegeticos, IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real (Spain); Charnock, J.M.; Bahrami, F. [Synchrotron Radiation Department, CCLRC Daresbury Laboratory, Warrington, Cheshire, WA4 4AD (United Kingdom); Green, A.J. [Department of Wetland Ecology, Estacion Biologica de Donana, CSIC, Pabellon del Peru, Avenida Maria Luisa s/n, 41013 Seville (Spain); Meharg, A.A. [School of Biological Sciences, University of Aberdeen, Cruickshank Bld, St Machar Drive, Aberdeen, AB24 3UU (United Kingdom)

2009-03-15

Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcollar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root + plaque' material in excess of 1000 mg kg{sup -1}, and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcollar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque. - Accumulation of metals with iron plaque on macrophyte roots in wetlands poses an ecotoxicological risk to certain herbivores.

Ecotoxicological evaluation of diesel-contaminated soil before and after a bioremediation process.

Science.gov (United States)

Molina-Barahona, L; Vega-Loyo, L; Guerrero, M; Ramírez, S; Romero, I; Vega-Jarquín, C; Albores, A

2005-02-01

Evaluation of contaminated sites is usually performed by chemical analysis of pollutants in soil. This is not enough either to evaluate the environmental risk of contaminated soil nor to evaluate the efficiency of soil cleanup techniques. Information on the bioavailability of complex mixtures of xenobiotics and degradation products cannot be totally provided by chemical analytical data, but results from bioassays can integrate the effects of pollutants in complex mixtures. In the preservation of human health and environment quality, it is important to assess the ecotoxicological effects of contaminated soils to obtain a better evaluation of the healthiness of this system. The monitoring of a diesel-contaminated soil and the evaluation of a bioremediation technique conducted on a microcosm scale were performed by a battery of ecotoxicological tests including phytotoxicity, Daphnia magna, and nematode assays. In this study we biostimulated the native microflora of soil contaminated with diesel by adding nutrients and crop residue (corn straw) as a bulking agent and as a source of microorganisms and nutrients; in addition, moisture was adjusted to enhance diesel removal. The bioremediation process efficiency was evaluated directly by an innovative, simple phytotoxicity test system and the diesel extracts by Daphnia magna and nematode assays. Contaminated soil samples were revealed to have toxic effects on seed germination, seedling growth, and Daphnia survival. After biostimulation, the diesel concentration was reduced by 50.6%, and the soil samples showed a significant reduction in phytotoxicity (9%-15%) and Daphnia assays (3-fold), confirming the effectiveness of the bioremediation process. Results from our microcosm study suggest that in addition to the evaluation of the bioremediation processes efficiency, toxicity testing is different with organisms representative of diverse phylogenic levels. The integration of analytical, toxicological and bioremediation data

Experiences and extrapolations from Hiroshima and Nagasaki

International Nuclear Information System (INIS)

Harwell, C.C.

1985-01-01

This paper examines the events following the atomic bombings of Hiroshima and Nagasaki in 1945 and extrapolates from these experiences to further understand the possible consequences of detonations on a local area from weapons in the current world nuclear arsenal. The first section deals with a report of the events that occurred in Hiroshima and Nagasaki just after the 1945 bombings with respect to the physical conditions of the affected areas, the immediate effects on humans, the psychological response of the victims, and the nature of outside assistance. Because there can be no experimental data to validate the effects on cities and their populations of detonations from current weapons, the data from the actual explosions on Hiroshima and Nagasaki provide a point of departure. The second section examines possible extrapolations from and comparisons with the Hiroshima and Nagasaki experiences. The limitations of drawing upon the Hiroshima and Nagasaki experiences are discussed. A comparison is made of the scale of effects from other major disasters for urban systems, such as damages from the conventional bombings of cities during World War II, the consequences of major earthquakes, the historical effects of the Black Plague and widespread famines, and other extreme natural events. The potential effects of detonating a modern 1 MT warhead on the city of Hiroshima as it exists today are simulated. This is extended to the local effects on a targeted city from a global nuclear war, and attention is directed to problems of estimating the societal effects from such a war

Problems in the extrapolation of laboratory rheological data

Science.gov (United States)

Paterson, M. S.

1987-02-01

The many types of variables and deformation regimes that need to be taken into account in extrapolating rheological behaviour from the laboratory to the earth are reviewed. The problems of extrapolation are then illustrated with two particular cases. In the case of divine-rich rocks, recent experimental work indicates that, within present uncertainties of extrapolation, the flow in the upper mantle could be either grain size dependent and near-Newtonian or grain size independent and distinctly non-Newtonian. Both types of behaviour would be influenced by the present of trace amounts of water. In the case of quartz-rich rocks, the uncertainties are even greater and it is still premature to attempt any extrapolation to geological conditions except as an upper bound; the fugacity and the scale of dispersion of the water are probably two important variables but the quantitative laws governing their influence are not yet clear.

Response Load Extrapolation for Wind Turbines during Operation Based on Average Conditional Exceedance Rates

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Naess, Arvid; Saha, Nilanjan

2011-01-01

to cases where the Gumbel distribution is the appropriate asymptotic extreme value distribution. However, two extra parameters are introduced by which a more general and flexible class of extreme value distributions is obtained with the Gumbel distribution as a subclass. The general method is implemented...... within a hierarchical model where the variables that influence the loading are divided into ergodic variables and time-invariant non-ergodic variables. The presented method for statistical response load extrapolation was compared with the existing methods based on peak extrapolation for the blade out......The paper explores a recently developed method for statistical response load (load effect) extrapolation for application to extreme response of wind turbines during operation. The extrapolation method is based on average conditional exceedance rates and is in the present implementation restricted...

40 CFR 86.435-78 - Extrapolated emission values.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Extrapolated emission values. 86.435-78 Section 86.435-78 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Regulations for 1978 and Later New Motorcycles, General Provisions § 86.435-78 Extrapolated emission values...

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal.

Science.gov (United States)

Belhaj, Dalel; Athmouni, Khaled; Jerbi, Bouthaina; Kallel, Monem; Ayadi, Habib; Zhou, John L

2016-12-01

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 μg L -1 and from 11.8 to 792.9 μg kg -1 dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17β-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17β-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.

Development of mosquitofish (Gambusia affinis holbrooki populations in lentic mesocosms. Perspectives for ecotoxicological studies

Directory of Open Access Journals (Sweden)

DREZE V.

1998-07-01

Full Text Available In the perspective of ecotoxicological assays in mesocosms, the development of mosquitofish populations (Gambusia affinis holbrooki has been assessed. The objective was to evaluate the ability of fish to reproduce in these experimental ponds under the climatic conditions of Brittany, and to see if population size and individual criteria were related to the number of adults initially introduced. Six mesocosms (3.2 m diameter and 0.7 m water depth similarly designed received sexually mature mosquitofish at the rate of 12 (6 females and 6 males, 6 (3 females and 3 males and 2 (1 female and 1 male in June 1996. Each assay was duplicated. In December 1996, the entire populations were collected and the weight, size and sex of the individuals were noted. Length-frequency distributions were relatively similar between mesocosms and the different mode groups showed that the reproductive activity occurred until the beginning of fall. The produced biomass (from 4.1 to 38.3 g and number of fish collected (from 26 to 301 were statistically correlated to the number of pairs initially introduced. This study provides interesting perspectives for ecotoxicological investigations in which the effects of pollutants on mosquitofish would be assessed at the population level.

The optimizied expansion method for wavefield extrapolation

KAUST Repository

Wu, Zedong

2013-01-01

Spectral methods are fast becoming an indispensable tool for wave-field extrapolation, especially in anisotropic media, because of its dispersion and artifact free, as well as highly accurate, solutions of the wave equation. However, for inhomogeneous media, we face difficulties in dealing with the mixed space-wavenumber domain operator.In this abstract, we propose an optimized expansion method that can approximate this operator with its low rank representation. The rank defines the number of inverse FFT required per time extrapolation step, and thus, a lower rank admits faster extrapolations. The method uses optimization instead of matrix decomposition to find the optimal wavenumbers and velocities needed to approximate the full operator with its low rank representation.Thus,we obtain more accurate wave-fields using lower rank representation, and thus cheaper extrapolations. The optimization operation to define the low rank representation depends only on the velocity model, and this is done only once, and valid for a full reverse time migration (many shots) or one iteration of full waveform inversion. Applications on the BP model yielded superior results than those obtained using the decomposition approach. For transversely isotopic media, the solutions were free of the shear wave artifacts, and does not require that eta>0.

Aquatic ecotoxicology: properties of compounds and ecological risk; Aquatische Oekotoxikologie: Stoffeigenschaften und oekologisches Risiko

Energy Technology Data Exchange (ETDEWEB)

Klein, W. [Fraunhofer-Institut fuer Umweltchemie und Oekotoxikologie, Schmallenberg (Germany)

1999-07-01

In spite of considerable advances in research ecotoxicology and ecotoxicology for testing purposes, fundamental problems exist owing to the immense range of concepts, prerequisites and goals. Alleged weaknesses of ecotoxicology in terms of knowledge acquisition so far have had their cause not only in its pragmatic empirism but also in inadequate methodics and, especially, inconsistent or diversified target orientation. The methodics currently available provide tools permitting to a very large extent to fulfill requirements with the necessary precision and acuity. But practical execution has to heed the magnitude of effort that society is prepared to make for the benefit of the environment. Here, setting the appropriate priorities is the second major challenge to the objectivity of experts, following the assessment of risk versus benefit. (orig.) [German] Trotz erheblicher Fortschritte in der wissenschaftlichen und Pruefoekotoxikologie bestehen aufgrund der Vielfalt der Konzeptionen, Anforderungen und Zielvorgaben grundsaetzliche Probleme. Bisherige behauptete Schwaechen der Oekotoxikologie im Hinblick auf Erkenntnisfortschritt sind nicht nur durch pragmatische Empirie begruendet, sondern auch in ungenuegender Methodik und insbesondere inkonsistenter bzw. vielfaeltiger Zielorientierung. Mit der derzeit verfuegbaren Methodik koennen Anforderungen mit der jeweils notwendigen Praezision und Aussageschaerfe weitestgehend bearbeitet werden. Die praktische Bearbeitung hat sich jedoch danach zu richten, welchen Aufwand die Gesellschaft bereit ist fuer die Gesundheit der Umwelt zu tragen, wobei die richtige Prioritaetensetzung nach den Kriterien Risiko-Nutzen-Aufwand die wohl groesste Herausforderung an Expertenobjektivitaet darstellt. (orig.)

Ecotoxicological assessment of metal-polluted urban soils using bioassays with three soil invertebrates.

NARCIS (Netherlands)

Santarufo, L.; van Gestel, C.A.M.; Maisto, G.

2012-01-01

This study aimed at assessing the quality of urban soils by integrating chemical and ecotoxicological approaches. Soils from five sites in downtown Naples, Italy, were sampled and characterized for physical-chemical properties and total and water-extractable metal concentrations. Bioassays with

Food mediated life history strategies in Daphnia magna : their relevance to ecotoxicological evaluations

NARCIS (Netherlands)

Enserink, E.L.

1995-01-01

The waterflea Daphnia magna is a widely used test organism in ecotoxicological studies. Acute and chronic laboratory tests yield basic information for the development of water quality standards, assessment of potential hazards of (new) chemicals, waste water licences and

A model compound study: The ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays

International Nuclear Information System (INIS)

Macken, Ailbhe; Giltrap, Michelle; Foley, Barry; McGovern, Evin; McHugh, Brendan; Davoren, Maria

2008-01-01

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C 18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone. - Ecotoxicological evaluation of five organic marine sediment contaminants was conducted and the suitability of the test species for marine porewater TIE discussed

A model compound study: The ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays

Energy Technology Data Exchange (ETDEWEB)

Macken, Ailbhe [Radiation and Environmental Science Centre, Focas Institute, DIT, Kevin Street, Dublin 8 (Ireland)], E-mail: ailbhe.macken@dit.ie; Giltrap, Michelle [Radiation and Environmental Science Centre, Focas Institute, DIT, Kevin Street, Dublin 8 (Ireland); Marine Institute, Rinville, Oranmore, Co. Galway (Ireland)], E-mail: michelle.giltrap@marine.ie; Foley, Barry [School of Chemical and Pharmaceutical Sciences, DIT, Kevin Street, Dublin 8 (Ireland)], E-mail: barry.foley@dit.ie; McGovern, Evin [Marine Institute, Rinville, Oranmore, Co. Galway (Ireland)], E-mail: evin.mcgovern@marine.ie; McHugh, Brendan [Marine Institute, Rinville, Oranmore, Co. Galway (Ireland)], E-mail: brendan.mchugh@marine.ie; Davoren, Maria [Radiation and Environmental Science Centre, Focas Institute, DIT, Kevin Street, Dublin 8 (Ireland)], E-mail: maria.davoren@dit.ie

2008-06-15

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C{sub 18} resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone. - Ecotoxicological evaluation of five organic marine sediment contaminants was conducted and the suitability of the test species for marine porewater TIE discussed.

Ecotoxicological evaluation of the short term effects of fresh and stabilized textile sludges before application in forest soil restoration

International Nuclear Information System (INIS)

Rosa, Edson V.C.; Giuradelli, Thayse M.; Correa, Albertina X.R.; Roerig, Leonardo R.; Schwingel, Paulo R.; Resgalla, Charrid; Radetski, Claudemir M.

2007-01-01

The short term (eco)toxicity potential of fresh and stabilized textile sludges, as well as the short term (eco)toxicity of leachates obtained from both fresh and stabilized textile sludges, was evaluated by a battery of toxicity tests carried out with bacteria, algae, daphnids, fish, earthworms, and higher plants. The (eco)toxicological results showed that, after 120 d of stabilization, the experimental loading ratio of 25% sludge:75% soil (v/v) (equivalent to 64.4 ton/ha) did not significantly increase toxicity effects and increased significantly the biomass yield for earthworms and higher plants. The rank of biological sensitivity endpoints was: Algae ∼ Plant biomass > Plant germination ∼ Daphnids > Bacteria ∼ Fish > Annelids. The lack of short term toxicity effects and the stimulant effect observed with higher plants and earthworms are good indications of the fertilizer/conditioner potential of this industrial waste, which after stabilization can be used in the restoration of a non-productive forest soil. - Short term ecotoxicity evaluation of textile sludge showed that stabilized sludge can be used in the restoration of a non-productive forest soil

Ecotoxicological criteria for final storage quality: Possibilities and limits

Science.gov (United States)

Zeyer, Josef; Meyer, Joseph

Landfills are complex chemical and biological reactors whose internal processes are often beyond the immediate control of process engineers. Therefore, the concept of a "Final Storage Landfill" may be deceptive. Furthermore, traditional approaches to establishing discharge criteria and treatment requirements for industrial effluents may not work well for landfill emissions. Factories can often be treated as steady-state processes whose inputs and outputs are predictable; however, landfills are batch reactors whose contents and emissions may be unknown and will vary temporally and spatially. If the contents of a landfill are known, the sequence of chemical reactions can be predicted qualitatively. Even if that sequence is predictable, though, quantitative ecotoxicological criteria will be difficult to establish, and risk assessments based on chemical "laundry lists" will be questionable. The situation is not hopeless, though. New approaches can be developed to monitor and predict landfill emissions. We believe these will include (1) testing (biological and chemical) of internal components of landfills as well as emissions; (2) development of laboratory and/or field methods in which the chemical and biological evolution of landfills can be studied at accelerated rates, thus allowing better prediction of future emissions; and (3) flexible ecotoxicological criteria that are adaptable to the evolving nature of landfill emissions. These criteria should be based on complementary chemical analyses and biological tests that fit into a hierarchical (decision-tree) hazard assessment strategy.

Ecotoxicological potential of the biocides terbutryn, octhilinone and methylisothiazolinone: Underestimated risk from biocidal pathways?

Science.gov (United States)

Kresmann, Simon; Arokia, Arokia Hansel Rajan; Koch, Christoph; Sures, Bernd

2018-06-01

The use of biocides by industry, agriculture and households increased throughout the last two decades. Many new applications with known substances enriched the variety of biocidal pollution sources for the aquatic environment. While agriculture was the major source for a long time, leaching from building facades and preservation of personal care and cleaning products was identified as new sources in the last few years. With the different usage forms of biocidal products the complexity of legislative regulation increased as well. The requirements for risk assessment differ from one law to another and the potential risk of substances under different regulations might be underestimated. Still EC 50 and predicted no-effect concentration (PNEC) values gained from testing with different species are the core of environmental risk assessment, but ecotoxicological data is limited or lacking for many biocides. In this study the biocides widely used in facade coatings and household products terbutryn, octhilinone and methylisothiazolinone were tested with the Daphnia magna acute immobilisation assay, the neutral red uptake assay and the ethoxyresorufin-O-deethylase (EROD) assay, performed with rainbow trout liver (RTL-W1) cells. Further, the MTT assay with the ovarian cell line CHO-9 from Chinese hamster was used as mammalian model. Octhilinone induced the strongest effects with EC 50 values of 156μg/l in the D. magna assay, while terbutryn showed the weakest effects with 8390μg/l and methylisothiazolinone 513μg/l respectively. All other assays showed higher EC 50 values and thus only weak effects. EROD assays did not show any effects. With additional literature and database records PNEC values were calculated: terbutryn reached 0.003μg/l, octhilinone 0.05μg/l and methylisothiazolinone 0.5μg/l. Potential ecotoxicological risks of these biocides are discussed, considering environmental concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

The ATLAS Track Extrapolation Package

CERN Document Server

Salzburger, A

2007-01-01

The extrapolation of track parameters and their associated covariances to destination surfaces of different types is a very frequent process in the event reconstruction of high energy physics experiments. This is amongst other reasons due to the fact that most track and vertex fitting techniques are based on the first and second momentum of the underlying probability density distribution. The correct stochastic or deterministic treatment of interactions with the traversed detector material is hereby crucial for high quality track reconstruction throughout the entire momentum range of final state particles that are produced in high energy physics collision experiments. This document presents the main concepts, the algorithms and the implementation of the newly developed, powerful ATLAS track extrapolation engine. It also emphasises on validation procedures, timing measurements and the integration into the ATLAS offline reconstruction software.

Making sense of soil ecotoxicology

Science.gov (United States)

Beyer, W. Nelson; Linder, Greg L.; Hoffman, David J.; Rattner, Barnett A.; Burton, G. Allen; Cairns, John

1995-01-01

The toxicity of pesticides and environmental contaminants to soil organisms has been measured in studies on earthworms,1 soil arthropods,3-6 soil microorganisms,7 and other soil organisms.8 Toxicity data on earthworms produced in the pesticide registration procedure required by the OECD (Organization for economic cooperation and Development) will provide data on many additional chemicals.9 Deciding how to use the data generated is troublesome. In 1965, Edwards10 suggested that the effects of soil insecticides on soils may remain long after the pesticides have disappeared, and that it was clear that pesticides could drastically change the populations of soil organisms; Edwards noted, however, that the effects did not seem to be serious when compared with the benefits to crop production of using pesticides. Since 1965, many studies have been conducted on changes in soil ecosystems caused by environmental contaminants, but we still know little about what the toxicity to particular groups of soil organisms means to the functioning of the soil ecosystem. the problem was illustrated in discussions at the International Conference on Earthworm Ecotoxicology in Sheffield, England, in 1991. there was general agreement that earthworms ahould be taken into account when evaluating pesticides. However, it was unclear what level of reduction in earthworm populations would reduce soil quality or crop yeild. Because populations of earthworms naturally fluctuate greatly even in the absence of pesticides, and because some soils are fertile without any earthworms, it is difficult to equate their population decreases with damage to the soil ecosystem. Broadbent and Tomlin found that the insecticide carbofuran caused fluctuations in the populations of some microarthropods in a cornfield but, in comparing the effects to those of cultivation or adding compost, they concluded that it was unlikely that litter decomposition was significantly affected.3

Multiparameter extrapolation and deflation methods for solving equation systems

Directory of Open Access Journals (Sweden)

A. J. Hughes Hallett

1984-01-01

Full Text Available Most models in economics and the applied sciences are solved by first order iterative techniques, usually those based on the Gauss-Seidel algorithm. This paper examines the convergence of multiparameter extrapolations (accelerations of first order iterations, as an improved approximation to the Newton method for solving arbitrary nonlinear equation systems. It generalises my earlier results on single parameter extrapolations. Richardson's generalised method and the deflation method for detecting successive solutions in nonlinear equation systems are also presented as multiparameter extrapolations of first order iterations. New convergence results are obtained for those methods.

Efficient and stable extrapolation of prestack wavefields

KAUST Repository

Wu, Zedong

2013-09-22

The double-square-root (DSR) relation offers a platform to perform prestack imaging using an extended single wavefield that honors the geometrical configuration between sources, receivers and the image point, or in other words, prestack wavefields. Extrapolating such wavefields in time, nevertheless, is a big challenge because the radicand can be negative, thus reduce to a complex phase velocity, which will make the rank of the mixed domain matrix very high. Using the vertical offset between the sources and receivers, we introduce a method for deriving the DSR formulation, which gives us the opportunity to derive approximations for the mixed domain operator. The method extrapolates prestack wavefields by combining all data into one wave extrapolation procedure, allowing both upgoing and downgoing wavefields since the extrapolation is done in time, and doesn’t have the v(z) assumption in the offset axis of the media. Thus, the imaging condition is imposed by taking the zero-time and zero-offset slice from the multi-dimensional prestack wavefield. Unlike reverse time migration (RTM), no crosscorrelation is needed and we also have access to the subsurface offset information, which is important for migration velocity analysis. Numerical examples show the capability of this approach in dealing with complex velocity models and can provide a better quality image compared to RTM more efficiently.

Efficient and stable extrapolation of prestack wavefields

KAUST Repository

Wu, Zedong; Alkhalifah, Tariq Ali

2013-01-01

The double-square-root (DSR) relation offers a platform to perform prestack imaging using an extended single wavefield that honors the geometrical configuration between sources, receivers and the image point, or in other words, prestack wavefields. Extrapolating such wavefields in time, nevertheless, is a big challenge because the radicand can be negative, thus reduce to a complex phase velocity, which will make the rank of the mixed domain matrix very high. Using the vertical offset between the sources and receivers, we introduce a method for deriving the DSR formulation, which gives us the opportunity to derive approximations for the mixed domain operator. The method extrapolates prestack wavefields by combining all data into one wave extrapolation procedure, allowing both upgoing and downgoing wavefields since the extrapolation is done in time, and doesn’t have the v(z) assumption in the offset axis of the media. Thus, the imaging condition is imposed by taking the zero-time and zero-offset slice from the multi-dimensional prestack wavefield. Unlike reverse time migration (RTM), no crosscorrelation is needed and we also have access to the subsurface offset information, which is important for migration velocity analysis. Numerical examples show the capability of this approach in dealing with complex velocity models and can provide a better quality image compared to RTM more efficiently.

One-step lowrank wave extrapolation

KAUST Repository

Sindi, Ghada Atif; Alkhalifah, Tariq Ali

2014-01-01

Wavefield extrapolation is at the heart of modeling, imaging, and Full waveform inversion. Spectral methods gained well deserved attention due to their dispersion free solutions and their natural handling of anisotropic media. We propose a scheme a

Flavor extrapolation in lattice QCD

International Nuclear Information System (INIS)

Duffy, W.C.

1984-01-01

Explicit calculation of the effect of virtual quark-antiquark pairs in lattice QCD has eluded researchers. To include their effect explicitly one must calculate the determinant of the fermion-fermion coupling matrix. Owing to the large number of sites in a continuum limit size lattice, direct evaluation of this term requires an unrealistic amount of computer time. The effect of the virtual pairs can be approximated by ignoring this term and adjusting lattice couplings to reproduce experimental results. This procedure is called the valence approximation since it ignores all but the minimal number of quarks needed to describe hadrons. In this work the effect of the quark-antiquark pairs has been incorporated in a theory with an effective negative number of quark flavors contributing to the closed loops. Various particle masses and decay constants have been calculated for this theory and for one with no virtual pairs. The author attempts to extrapolate results towards positive numbers of quark flavors. The results show approximate agreement with experimental measurements and demonstrate the smoothness of lattice expectations in the number of quark flavors

Ecotoxicological evaluation of swine manure disposal on tropical soils in Brazil.

Science.gov (United States)

Segat, Julia Corá; Alves, Paulo Roger Lopes; Baretta, Dilmar; Cardoso, Elke Jurandy Bran Nogueira

2015-12-01

Swine production in Brazil results in a great volume of manure that normally is disposed of as agricultural fertilizer. However, this form of soil disposal, generally on small farms, causes the accumulation of large amounts of manure and this results in contaminated soil and water tables. To evaluate the effects of increasing concentrations of swine manure on earthworms, several ecotoxicological tests were performed using Eisenia andrei as test organism in different tropical soils, classified respectively as Ultisol, Oxisol, and Entisol, as well as Tropical Artificial Soil (TAS). The survival, reproduction and behavior of the earthworms were evaluated in experiments using a completely randomized design, with five replications. In the Ultisol, Oxisol and TAS the swine manure showed no lethality, but in the Entisol it caused earthworm mortality (LOEC=45 m(3)ha(-1)). In the Entisol, the waste reduced the reproductive rate and caused avoidance behavior in E. andrei (LOEC=30 m(3)ha(-1)) even in lower concentrations. The Entisol is extremely sandy, with low cation exchange capacity (CEC), and this may be the reason for the higher toxicity on soil fauna, with the soil not being able to hold large amounts of pollutants (e.g. toxic metals), but leaving them in bioavailable forms. These results should be a warning of the necessity to consider soil parameters (e.g. texture and CEC) when evaluating soil contamination by means of ecotoxicological assays, as there still are no standards for natural soils in tropical regions. E. andrei earthworms act as indicators for a soil to support disposal of swine manure without generating harm to agriculture and ecosystems. Copyright © 2015 Elsevier Inc. All rights reserved.

Clustering pesticides according to their molecular properties and their impacts by considering additional ecotoxicological parameters in the TyPol method

Science.gov (United States)

Traore, Harouna; Crouzet, Olivier; Mamy, Laure; Sireyjol, Christine; Rossard, Virginie; Servien, Remy; Latrille, Eric; Benoit, Pierre

2017-04-01

The understanding of the fate of pesticides and their environmental impacts largely relies on their molecular properties. We recently developed 'TyPol' (Typology of Pollutants), a clustering method based on statistical analyses combining several environmental endpoints (i.e. environmental parameters such as sorption coefficient, degradation half-life) and one ecotoxicological one (bioconcentration factor), and structural molecular descriptors (number of atoms in the molecule, molecular surface, dipole moment, energy of orbitals…). TyPol has been conceived on the available knowledge on QSAR of a wide diversity of organic compounds (Mamy et al., 2015). This approach also allows to focus on transformation products present in different clusters and to infer possible changes in environmental fate consecutively to different degradation processes (Servien et al., 2014; Benoit et al., 2016). The initial version of TyPol did not include any ecotoxicological parameters except the bioconcentration factor (BCF), which informs more on the transfer along the trophic chain rather than on the effects on non-target organisms. The objective was to implement the TyPol database with a data set of ecotoxicological data concerning pesticides and several aquatic and terrestrial organisms, in order to test the possibility to extend TyPol to ecotoxicological effects on various organisms. The data analysis (available literature and databases) revealed that relevant ecotoxicological endpoints for terrestrial organisms such as soil microorganisms and macroinvertebrates are lacking compared to aquatic organisms. We have added seven parameters for acute (EC50, LC50) and chronic (NOEC) toxicological effects for the following organisms: Daphnia, Algae, Lemna and Earthworm. In this new configuration, TyPol was used to classify about 45 pesticides in different behavioural and ecotoxicity clusters. The clustering results were analyzed to reveals relationships between molecular descriptors

Design and construction of an interface system for the extrapolation chamber from the beta secondary standard

International Nuclear Information System (INIS)

Jimenez C, L.F.

1995-01-01

The Interface System for the Extrapolation Chamber (SICE) contains several devices handled by a personal computer (PC), it is able to get the required data to calculate the absorbed dose due to Beta radiation. The main functions of the system are: a) Measures the ionization current or charge stored in the extrapolation chamber. b) Adjusts the distance between the plates of the extrapolation chamber automatically. c) Adjust the bias voltage of the extrapolation chamber automatically. d) Acquires the data of the temperature, atmospheric pressure, relative humidity of the environment and the voltage applied between the plates of the extrapolation chamber. e) Calculates the effective area of the plates of the extrapolation chamber and the real distance between them. f) Stores all the obtained information in hard disk or diskette. A comparison between the desired distance and the distance in the dial of the extrapolation chamber, show us that the resolution of the system is of 20 μm. The voltage can be changed between -399.9 V and +399.9 V with an error of less the 3 % with a resolution of 0.1 V. These uncertainties are between the accepted limits to be used in the determination of the absolute absorbed dose due to beta radiation. (Author)

Recommended approaches to the scientific evaluation of ecotoxicological hazards and risks of endocrine-active substances.

Science.gov (United States)

Matthiessen, Peter; Ankley, Gerald T; Biever, Ronald C; Bjerregaard, Poul; Borgert, Christopher; Brugger, Kristin; Blankinship, Amy; Chambers, Janice; Coady, Katherine K; Constantine, Lisa; Dang, Zhichao; Denslow, Nancy D; Dreier, David A; Dungey, Steve; Gray, L Earl; Gross, Melanie; Guiney, Patrick D; Hecker, Markus; Holbech, Henrik; Iguchi, Taisen; Kadlec, Sarah; Karouna-Renier, Natalie K; Katsiadaki, Ioanna; Kawashima, Yukio; Kloas, Werner; Krueger, Henry; Kumar, Anu; Lagadic, Laurent; Leopold, Annegaaike; Levine, Steven L; Maack, Gerd; Marty, Sue; Meador, James; Mihaich, Ellen; Odum, Jenny; Ortego, Lisa; Parrott, Joanne; Pickford, Daniel; Roberts, Mike; Schaefers, Christoph; Schwarz, Tamar; Solomon, Keith; Verslycke, Tim; Weltje, Lennart; Wheeler, James R; Williams, Mike; Wolf, Jeffrey C; Yamazaki, Kunihiko

2017-03-01

A SETAC Pellston Workshop ® "Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA)" was held in February 2016 in Pensacola, Florida, USA. The primary objective of the workshop was to provide advice, based on current scientific understanding, to regulators and policy makers; the aim being to make considered, informed decisions on whether to select an ecotoxicological hazard- or a risk-based approach for regulating a given endocrine-disrupting substance (EDS) under review. The workshop additionally considered recent developments in the identification of EDS. Case studies were undertaken on 6 endocrine-active substances (EAS-not necessarily proven EDS, but substances known to interact directly with the endocrine system) that are representative of a range of perturbations of the endocrine system and considered to be data rich in relevant information at multiple biological levels of organization for 1 or more ecologically relevant taxa. The substances selected were 17α-ethinylestradiol, perchlorate, propiconazole, 17β-trenbolone, tributyltin, and vinclozolin. The 6 case studies were not comprehensive safety evaluations but provided foundations for clarifying key issues and procedures that should be considered when assessing the ecotoxicological hazards and risks of EAS and EDS. The workshop also highlighted areas of scientific uncertainty, and made specific recommendations for research and methods-development to resolve some of the identified issues. The present paper provides broad guidance for scientists in regulatory authorities, industry, and academia on issues likely to arise during the ecotoxicological hazard and risk assessment of EAS and EDS. The primary conclusion of this paper, and of the SETAC Pellston Workshop on which it is based, is that if data on environmental exposure, effects on sensitive species and life-stages, delayed effects, and effects at low concentrations are robust, initiating environmental risk

Generalized empirical equation for the extrapolated range of electrons in elemental and compound materials

International Nuclear Information System (INIS)

Lima, W. de; Poli CR, D. de

1999-01-01

The extrapolated range R ex of electrons is useful for various purposes in research and in the application of electrons, for example, in polymer modification, electron energy determination and estimation of effects associated with deep penetration of electrons. A number of works have used empirical equations to express the extrapolated range for some elements. In this work a generalized empirical equation, very simple and accurate, in the energy region 0.3 keV - 50 MeV is proposed. The extrapolated range for elements, in organic or inorganic molecules and compound materials, can be well expressed as a function of the atomic number Z or two empirical parameters Zm for molecules and Zc for compound materials instead of Z. (author)

A Method for Extrapolation of Atmospheric Soundings

Science.gov (United States)

2014-05-01

case are not shown here. We also briefly examined data for the Anchorage, AK ( PANC ), radiosonde site for the case of the inversion height equal to...or greater than the extrapolation depth (i.e., hinv ≥ hext). PANC lies at the end of a broad inlet extending northward from the Gulf of Alaska at...type of terrain can affect the model and in turn affect the extrapolation. We examined a sounding from PANC (61.16 N and –150.01 W, elevation of 40

Proposition of Improved Methodology in Creep Life Extrapolation

International Nuclear Information System (INIS)

Kim, Woo Gon; Park, Jae Young; Jang, Jin Sung

2016-01-01

To design SFRs for a 60-year operation, it is desirable to have the experimental creep-rupture data for Gr. 91 steel close to 20 y, or at least rupture lives significantly higher than 10"5 h. This requirement arises from the fact that, for the creep design, a factor of 3 times for extrapolation is considered to be appropriate. However, obtaining experimental data close to 20 y would be expensive and also take considerable time. Therefore, reliable creep life extrapolation techniques become necessary for a safe design life of 60 y. In addition, it is appropriate to obtain experimental longterm creep-rupture data in the range 10"5 ∼ 2x10"5 h to improve the reliability of extrapolation. In the present investigation, a new function of a hyperbolic sine ('sinh') form for a master curve in time-temperature parameter (TTP) methods, was proposed to accurately extrapolate the long-term creep rupture stress of Gr. 91 steel. Constant values used for each parametric equation were optimized on the basis of the creep rupture data. Average stress values predicted for up to 60 y were evaluated and compared with those of French Nuclear Design Code, RCC-MRx. The results showed that the master curve of the 'sinh' function was a wider acceptance with good flexibility in the low stress ranges beyond the experimental data. It was clarified clarified that the 'sinh' function was reasonable in creep life extrapolation compared with polynomial forms, which have been used conventionally until now.

Proposition of Improved Methodology in Creep Life Extrapolation

Energy Technology Data Exchange (ETDEWEB)

Kim, Woo Gon; Park, Jae Young; Jang, Jin Sung [KAERI, Daejeon (Korea, Republic of)

2016-05-15

To design SFRs for a 60-year operation, it is desirable to have the experimental creep-rupture data for Gr. 91 steel close to 20 y, or at least rupture lives significantly higher than 10{sup 5} h. This requirement arises from the fact that, for the creep design, a factor of 3 times for extrapolation is considered to be appropriate. However, obtaining experimental data close to 20 y would be expensive and also take considerable time. Therefore, reliable creep life extrapolation techniques become necessary for a safe design life of 60 y. In addition, it is appropriate to obtain experimental longterm creep-rupture data in the range 10{sup 5} ∼ 2x10{sup 5} h to improve the reliability of extrapolation. In the present investigation, a new function of a hyperbolic sine ('sinh') form for a master curve in time-temperature parameter (TTP) methods, was proposed to accurately extrapolate the long-term creep rupture stress of Gr. 91 steel. Constant values used for each parametric equation were optimized on the basis of the creep rupture data. Average stress values predicted for up to 60 y were evaluated and compared with those of French Nuclear Design Code, RCC-MRx. The results showed that the master curve of the 'sinh' function was a wider acceptance with good flexibility in the low stress ranges beyond the experimental data. It was clarified clarified that the 'sinh' function was reasonable in creep life extrapolation compared with polynomial forms, which have been used conventionally until now.

Extrapolation Method for System Reliability Assessment

DEFF Research Database (Denmark)

Qin, Jianjun; Nishijima, Kazuyoshi; Faber, Michael Havbro

2012-01-01

of integrals with scaled domains. The performance of this class of approximation depends on the approach applied for the scaling and the functional form utilized for the extrapolation. A scheme for this task is derived here taking basis in the theory of asymptotic solutions to multinormal probability integrals......The present paper presents a new scheme for probability integral solution for system reliability analysis, which takes basis in the approaches by Naess et al. (2009) and Bucher (2009). The idea is to evaluate the probability integral by extrapolation, based on a sequence of MC approximations...... that the proposed scheme is efficient and adds to generality for this class of approximations for probability integrals....

Finite lattice extrapolation algorithms

International Nuclear Information System (INIS)

Henkel, M.; Schuetz, G.

1987-08-01

Two algorithms for sequence extrapolation, due to von den Broeck and Schwartz and Bulirsch and Stoer are reviewed and critically compared. Applications to three states and six states quantum chains and to the (2+1)D Ising model show that the algorithm of Bulirsch and Stoer is superior, in particular if only very few finite lattice data are available. (orig.)

Irradiated food: validity of extrapolating wholesomeness data

International Nuclear Information System (INIS)

Taub, I.A.; Angelini, P.; Merritt, C. Jr.

1976-01-01

Criteria are considered for validly extrapolating the conclusions reached on the wholesomeness of an irradiated food receiving high doses to the same food receiving a lower dose. A consideration first is made of the possible chemical mechanisms that could give rise to different functional dependences of radiolytic products on dose. It is shown that such products should increase linearly with dose and the ratio of products should be constant throughout the dose range considered. The assumption, generally accepted in pharmacology, then is made that if any adverse effects related to the food are discerned in the test animals, then the intensity of these effects would increase with the concentration of radiolytic products in the food. Lastly, the need to compare data from animal studies with foods irradiated to several doses against chemical evidence obtained over a comparable dose range is considered. It is concluded that if the products depend linearly on dose and if feeding studies indicate no adverse effects, then an extrapolation to lower doses is clearly valid. This approach is illustrated for irradiated codfish. The formation of selected volatile products in samples receiving between 0.1 and 3 Mrads was examined, and their concentrations were found to increase linearly at least up to 1 Mrad. These data were compared with results from animal feeding studies establishing the wholesomeness of codfish and haddock irradiated to 0.2, 0.6 and 2.8 Mrads. It is stated, therefore, that if ocean fish, currently under consideration for onboard processing, were irradiated to 0.1 Mrad, it would be correspondingly wholesome

Radiographic film: surface dose extrapolation techniques

International Nuclear Information System (INIS)

Cheung, T.; Yu, P.K.N.; Butson, M.J.; Cancer Services, Wollongong, NSW; Currie, M.

2004-01-01

Full text: Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate 2 dimensional map of surface dose if required. Results have shown that surface % dose can be estimated within ±3% of parallel plate ionisation chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10cm, 20cmand 30cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. Corresponding parallel plate ionisation chamber measurement are 16%, 27% and 37% respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine

Cryopreserved semen in ecotoxicological bioassays: sensitivity and reliability of cryopreserved Sparus aurata spermatozoa.

Science.gov (United States)

Fabbrocini, Adele; D'Adamo, Raffaele; Del Prete, Francesco; Langellotti, Antonio Luca; Rinna, Francesca; Silvestri, Fausto; Sorrenti, Gerarda; Vitiello, Valentina; Sansone, Giovanni

2012-10-01

The aim of this study was to evaluate the feasibility of using cryopreserved S. aurata semen in spermiotoxicity tests. Cryopreservation is a biotechnology that can provide viable gametes and embryos on demand, rather than only in the spawning season, thus overcoming a limitation that has hindered the use of some species in ecotoxicological bioassays. Firstly, the sperm motility pattern of cryopreserved semen was evaluated after thawing by means of both visual and computer-assisted analyses. Motility parameters in the cryopreserved semen did not change significantly in the first hour after thawing, meaning that they were maintained for long enough to enable their use in spermiotoxicity tests. In the second phase of the research, bioassays were performed, using cadmium as the reference toxicant, in order to evaluate the sensitivity of cryopreserved S. aurata semen to ecotoxicological contamination. The sensitivity of the sperm motility parameters used as endpoints (motility percentages and velocities) proved to be comparable to what has been recorded for the fresh semen of other aquatic species (LOECs from 0.02 to 0.03 mg L(-1)). The test showed good reliability and was found to be rapid and easy to perform, requiring only a small volume of the sample. Moreover, cryopreserved semen is easy to store and transfer and makes it possible to perform bioassays in different sites or at different times with the same batch of semen. The proposed bioassay is therefore a promising starting point for the development of toxicity tests that are increasingly tailored to the needs of ecotoxicology and environmental quality evaluation strategies. Copyright © 2012 Elsevier Inc. All rights reserved.

Residual extrapolation operators for efficient wavefield construction

KAUST Repository

Alkhalifah, Tariq Ali

2013-02-27

Solving the wave equation using finite-difference approximations allows for fast extrapolation of the wavefield for modelling, imaging and inversion in complex media. It, however, suffers from dispersion and stability-related limitations that might hamper its efficient or proper application to high frequencies. Spectral-based time extrapolation methods tend to mitigate these problems, but at an additional cost to the extrapolation. I investigate the prospective of using a residual formulation of the spectral approach, along with utilizing Shanks transform-based expansions, that adheres to the residual requirements, to improve accuracy and reduce the cost. Utilizing the fact that spectral methods excel (time steps are allowed to be large) in homogeneous and smooth media, the residual implementation based on velocity perturbation optimizes the use of this feature. Most of the other implementations based on the spectral approach are focussed on reducing cost by reducing the number of inverse Fourier transforms required in every step of the spectral-based implementation. The approach here fixes that by improving the accuracy of each, potentially longer, time step.

Impact of soil properties on critical concentrations of cadmium, lead, copper, zinc and mercury in soil and soil solution in view of ecotoxicological effects

NARCIS (Netherlands)

Vries, de W.; Lofts, S.; Tipping, E.; Meili, M.; Groenenberg, J.E.; Schutze, G.

2007-01-01

Concern about the input of metals to terrestrial ecosystems is related to (i) the ecotoxicological impact on soil organisms and plants (Bringmark et al. 1998; Palmborg et al. 1998) and also on aquatic organisms resulting from runoff to surface water and (ii) the uptake via food chains into animal

Design for low dose extrapolation of carcinogenicity data. Technical report No. 24

International Nuclear Information System (INIS)

Wong, S.C.

1979-06-01

Parameters for modelling dose-response relationships in carcinogenesis models were found to be very complicated, especially for distinguishing low dose effects. The author concluded that extrapolation always bears the danger of providing misleading information

An extrapolation scheme for solid-state NMR chemical shift calculations

Science.gov (United States)

Nakajima, Takahito

2017-06-01

Conventional quantum chemical and solid-state physical approaches include several problems to accurately calculate solid-state nuclear magnetic resonance (NMR) properties. We propose a reliable computational scheme for solid-state NMR chemical shifts using an extrapolation scheme that retains the advantages of these approaches but reduces their disadvantages. Our scheme can satisfactorily yield solid-state NMR magnetic shielding constants. The estimated values have only a small dependence on the low-level density functional theory calculation with the extrapolation scheme. Thus, our approach is efficient because the rough calculation can be performed in the extrapolation scheme.

Lowrank seismic-wave extrapolation on a staggered grid

KAUST Repository

Fang, Gang

2014-05-01

© 2014 Society of Exploration Geophysicists. We evaluated a new spectral method and a new finite-difference (FD) method for seismic-wave extrapolation in time. Using staggered temporal and spatial grids, we derived a wave-extrapolation operator using a lowrank decomposition for a first-order system of wave equations and designed the corresponding FD scheme. The proposed methods extend previously proposed lowrank and lowrank FD wave extrapolation methods from the cases of constant density to those of variable density. Dispersion analysis demonstrated that the proposed methods have high accuracy for a wide wavenumber range and significantly reduce the numerical dispersion. The method of manufactured solutions coupled with mesh refinement was used to verify each method and to compare numerical errors. Tests on 2D synthetic examples demonstrated that the proposed method is highly accurate and stable. The proposed methods can be used for seismic modeling or reverse-time migration.

Lowrank seismic-wave extrapolation on a staggered grid

KAUST Repository

Fang, Gang; Fomel, Sergey; Du, Qizhen; Hu, Jingwei

2014-01-01

© 2014 Society of Exploration Geophysicists. We evaluated a new spectral method and a new finite-difference (FD) method for seismic-wave extrapolation in time. Using staggered temporal and spatial grids, we derived a wave-extrapolation operator using a lowrank decomposition for a first-order system of wave equations and designed the corresponding FD scheme. The proposed methods extend previously proposed lowrank and lowrank FD wave extrapolation methods from the cases of constant density to those of variable density. Dispersion analysis demonstrated that the proposed methods have high accuracy for a wide wavenumber range and significantly reduce the numerical dispersion. The method of manufactured solutions coupled with mesh refinement was used to verify each method and to compare numerical errors. Tests on 2D synthetic examples demonstrated that the proposed method is highly accurate and stable. The proposed methods can be used for seismic modeling or reverse-time migration.

Extrapolation of ZPR sodium void measurements to the power reactor

International Nuclear Information System (INIS)

Beck, C.L.; Collins, P.J.; Lineberry, M.J.; Grasseschi, G.L.

1976-01-01

Sodium-voiding measurements of ZPPR assemblies 2 and 5 are analyzed with ENDF/B Version IV data. Computations include directional diffusion coefficients to account for streaming effects resulting from the plate structure of the critical assembly. Bias factors for extrapolating critical assembly data to the CRBR design are derived from the results of this analysis

Ecotoxicology of Hexavalent Chromium in Freshwater Fish: A Critical Review

Science.gov (United States)

Velma, Venkatramreddy; Vutukuru, S.S.; Tchounwou, Paul B.

2010-01-01

Chromium (Cr) is a naturally occurring element found in rocks, animals, plants, and soil, predominantly in its insoluble trivalent form [Cr(III)]. Intense industrialization and other anthropogenic activities have led to the global occurrence of soluble Cr(VI), which is readily leached from soil to groundwater or surface water, in concentrations above permissible levels. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce a variety of adverse effects in biologic systems, including fish. In aquatic ecosystems, Cr(VI) exposure poses a significant threat to aquatic life. This paper reviews the fate and transport of Cr(VI) in the environment and its acute and chronic effects on fish. We also discuss Cr(VI) toxicity at the cellular, biochemical, and genetic levels. An attempt is made in this review to comprehend the staggered data on the toxic effects of Cr(VI) to various species of fish. Such data are extremely useful to the scientific community and public officials involved in health risk assessment and management of environmental contaminants as a guide to the best course of action to restore ecosystems and, in turn, to preserve human health. PMID:19658319

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor.

Science.gov (United States)

Lapa, N; Barbosa, R; Lopes, M H; Mendes, B; Abelha, P; Boavida, D; Gulyurtlu, I; Oliveira, J Santos

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub-products of such type

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Lapa, N. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)]. E-mail: ncsn@fct.unl.pt; Barbosa, R. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Lopes, M.H. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Mendes, B. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Abelha, P. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Gulyurtlu, I. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Santos Oliveira, J. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

International Nuclear Information System (INIS)

Lapa, N.; Barbosa, R.; Lopes, M.H.; Mendes, B.; Abelha, P.; Gulyurtlu, I.; Santos Oliveira, J.

2007-01-01

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Extrapolation of rate constants of reactions producing H2 and O2 in radiolysis of water at high temperatures

International Nuclear Information System (INIS)

Leblanc, R.; Ghandi, K.; Hackman, B.; Liu, G.

2014-01-01

One target of our research is to extrapolate known data on the rate constants of reactions and add corrections to estimate the rate constants at the higher temperatures reached by the SCWR reactors. The focus of this work was to extrapolate known data on the rate constants of reactions that produce Hydrogen or Oxygen with a rate constant below 10 10 mol -1 s -1 at room temperature. The extrapolation is done taking into account the change in the diffusion rate of the interacting species and the cage effect with thermodynamic conditions. The extrapolations are done over a wide temperature range and under isobaric conditions. (author)

Extrapolation of experimental data on late effects of low-dose radionuclides in man

International Nuclear Information System (INIS)

Kalistratova, V.S.; Nisimov, P.G.

1997-01-01

The situation of living of population on radionuclide contamination areas was simulated in the experimental study using white strainless rats of different ages. The significance of age for late stochastic effects of internal radionuclide contamination with low doses of 131 I, 137 Cs, 144 Ce and 106 Ru was studied. Some common regularities and differences in late effects formation depending on age were found. Results of the study showed that the number of tumors developed increased in groups of animals exposed at the youngest age. The younger animal at the moment of internal radionuclide contamination, the higher percentage of malignant tumors appeared. It was especially so for tumors of endocrine glands (pituitary, suprarenal,- and thyroid). Differences in late effects formation related to different type of radionuclide distribution within the body were estimated. On the base of extrapolation the conclusion was made that human organism being exposed at early postnatal or pubertal period could be the most radiosensitive (1.5-2.0 or sometimes even 3-5 times higher than adults). Data confirmed the opinion that children are the most critical part of population even in case of low dose radiation exposure. (author)

In situ LTE exposure of the general public: Characterization and extrapolation.

Science.gov (United States)

Joseph, Wout; Verloock, Leen; Goeminne, Francis; Vermeeren, Günter; Martens, Luc

2012-09-01

In situ radiofrequency (RF) exposure of the different RF sources is characterized in Reading, United Kingdom, and an extrapolation method to estimate worst-case long-term evolution (LTE) exposure is proposed. All electric field levels satisfy the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels with a maximal total electric field value of 4.5 V/m. The total values are dominated by frequency modulation (FM). Exposure levels for LTE of 0.2 V/m on average and 0.5 V/m maximally are obtained. Contributions of LTE to the total exposure are limited to 0.4% on average. Exposure ratios from 0.8% (LTE) to 12.5% (FM) are obtained. An extrapolation method is proposed and validated to assess the worst-case LTE exposure. For this method, the reference signal (RS) and secondary synchronization signal (S-SYNC) are measured and extrapolated to the worst-case value using an extrapolation factor. The influence of the traffic load and output power of the base station on in situ RS and S-SYNC signals are lower than 1 dB for all power and traffic load settings, showing that these signals can be used for the extrapolation method. The maximal extrapolated field value for LTE exposure equals 1.9 V/m, which is 32 times below the ICNIRP reference levels for electric fields. Copyright © 2012 Wiley Periodicals, Inc.

The optimized expansion based low-rank method for wavefield extrapolation

KAUST Repository

Wu, Zedong

2014-03-01

Spectral methods are fast becoming an indispensable tool for wavefield extrapolation, especially in anisotropic media because it tends to be dispersion and artifact free as well as highly accurate when solving the wave equation. However, for inhomogeneous media, we face difficulties in dealing with the mixed space-wavenumber domain extrapolation operator efficiently. To solve this problem, we evaluated an optimized expansion method that can approximate this operator with a low-rank variable separation representation. The rank defines the number of inverse Fourier transforms for each time extrapolation step, and thus, the lower the rank, the faster the extrapolation. The method uses optimization instead of matrix decomposition to find the optimal wavenumbers and velocities needed to approximate the full operator with its explicit low-rank representation. As a result, we obtain lower rank representations compared with the standard low-rank method within reasonable accuracy and thus cheaper extrapolations. Additional bounds set on the range of propagated wavenumbers to adhere to the physical wave limits yield unconditionally stable extrapolations regardless of the time step. An application on the BP model provided superior results compared to those obtained using the decomposition approach. For transversely isotopic media, because we used the pure P-wave dispersion relation, we obtained solutions that were free of the shear wave artifacts, and the algorithm does not require that n > 0. In addition, the required rank for the optimization approach to obtain high accuracy in anisotropic media was lower than that obtained by the decomposition approach, and thus, it was more efficient. A reverse time migration result for the BP tilted transverse isotropy model using this method as a wave propagator demonstrated the ability of the algorithm.

Seismic wave extrapolation using lowrank symbol approximation

KAUST Repository

Fomel, Sergey

2012-04-30

We consider the problem of constructing a wave extrapolation operator in a variable and possibly anisotropic medium. Our construction involves Fourier transforms in space combined with the help of a lowrank approximation of the space-wavenumber wave-propagator matrix. A lowrank approximation implies selecting a small set of representative spatial locations and a small set of representative wavenumbers. We present a mathematical derivation of this method, a description of the lowrank approximation algorithm and numerical examples that confirm the validity of the proposed approach. Wave extrapolation using lowrank approximation can be applied to seismic imaging by reverse-time migration in 3D heterogeneous isotropic or anisotropic media. © 2012 European Association of Geoscientists & Engineers.

Higher Order Aitken Extrapolation with Application to Converging and Diverging Gauss-Seidel Iterations

OpenAIRE

Tiruneh, Ababu Teklemariam

2013-01-01

Aitken extrapolation normally applied to convergent fixed point iteration is extended to extrapolate the solution of a divergent iteration. In addition, higher order Aitken extrapolation is introduced that enables successive decomposition of high Eigen values of the iteration matrix to enable convergence. While extrapolation of a convergent fixed point iteration using a geometric series sum is a known form of Aitken acceleration, it is shown in this paper that the same formula can be used to ...

Surface dose extrapolation measurements with radiographic film

International Nuclear Information System (INIS)

Butson, Martin J; Cheung Tsang; Yu, Peter K N; Currie, Michael

2004-01-01

Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown that the surface percentage dose can be estimated within ±3% of parallel plate ionization chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10 cm, 20 cm and 30 cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. The corresponding parallel plate ionization chamber measurements are 16%, 27% and 37%, respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. (note)

Ecotoxicological risk assessment linked to infilling quarries with treated dredged seaport sediments.

Science.gov (United States)

Perrodin, Yves; Donguy, Gilles; Bazin, Christine; Volatier, Laurence; Durrieu, Claude; Bony, Sylvie; Devaux, Alain; Abdelghafour, Mohammed; Moretto, Robert

2012-08-01

The dredged sediments of polluted seaports now raise complex management problems since it is no longer possible to discharge them into the sea. This results in the need to manage them on land, raising other types of technical, economic and environmental problems. Regarding the technical and economic dimensions, traditional waste treatment methods have proved to be poorly adapted, due to very high costs and low absorbable volumes. In this context, filling quarries in coastal areas with treated sediments could represent an interesting alternative for these materials. Nevertheless, for the environmental dimension, it is necessary to demonstrate that this possibility is harmless to inland ecosystems. Consequently, a specific ecotoxicological risk assessment methodology has been formulated and tested on three sediments taken from seaboards of France, in view to providing an operational and usable tool for the prior validation of any operation to fill quarries with treated seaport sediments. This method incorporates the formulation of a global conceptual model of the scenario studied and the definition of protocols for each of its steps: the characterisation of exposures (based on a simulation of sediment deposit), the characterisation of effects (via the study of sediments ecotoxicity), and the final ecotoxicological risk assessment performed as a calculation of a risk quotient. It includes the implementation in parallel of two types of complementary approach: the "substances" approach derived from the European methodology for assessing new substances placed on the market, and the "matrix" approach which is similar to methods developed in France to assess ecological risks in other domains (waste management, polluted site management, …). The application of this dual approach to the three sediments tested led to conclude with reliability that the project to deposit sediments "1" and "2" presented a low risk for the peripheral aquatic ecosystems while sediment "3

Threatened southern African soils: A need for appropriate ecotoxicological risk assessment

Energy Technology Data Exchange (ETDEWEB)

Eijsackers, Herman [Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Reinecke, Adriaan; Reinecke, Sophie [Department of Botany & Zoology, Stellenbosch University, Private Bag X1, Matieland 7602 (South Africa); Maboeta, Mark, E-mail: mark.maboeta@nwu.ac.za [Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa)

2017-03-15

In southern Africa arable soils are limited due to low rainfall and are threatened by anthropogenic activities like agriculture and mining making it susceptible to degradation. The aim of this study is to review the existing information available with regards to soil contamination and its possible threats towards biodiversity and quality of southern African soils. Some of the issues being addressed in this paper include the focus areas of ecotoxicological research in southern African countries, levels of contaminants in soils, the impacts of climate on soil animals and the representativity of standardised test species. In order to address this, we report on a literature search, which was done to determine the main focus areas of soil ecotoxicological research, highlighting strengths and research needs in comparison to approaches elsewhere in the world. Further, to address if the risk assessment approaches of Europe and the USA are valid for southern African environmental conditions; this in the light of differences in temperature, rainfall and fauna. It is concluded that risk assessment procedures for Europe and the USA were based on non-southern African conditions making it necessary to rethink risk assessment studies; although limited, in southern Africa. We recommend future research that has to be undertaken to address these issues. This research should include investigating species sensitivities in responses to contamination and including insects likes ants and termites in ecological risk assessment studies.

Threatened southern African soils: A need for appropriate ecotoxicological risk assessment

International Nuclear Information System (INIS)

Eijsackers, Herman; Reinecke, Adriaan; Reinecke, Sophie; Maboeta, Mark

2017-01-01

In southern Africa arable soils are limited due to low rainfall and are threatened by anthropogenic activities like agriculture and mining making it susceptible to degradation. The aim of this study is to review the existing information available with regards to soil contamination and its possible threats towards biodiversity and quality of southern African soils. Some of the issues being addressed in this paper include the focus areas of ecotoxicological research in southern African countries, levels of contaminants in soils, the impacts of climate on soil animals and the representativity of standardised test species. In order to address this, we report on a literature search, which was done to determine the main focus areas of soil ecotoxicological research, highlighting strengths and research needs in comparison to approaches elsewhere in the world. Further, to address if the risk assessment approaches of Europe and the USA are valid for southern African environmental conditions; this in the light of differences in temperature, rainfall and fauna. It is concluded that risk assessment procedures for Europe and the USA were based on non-southern African conditions making it necessary to rethink risk assessment studies; although limited, in southern Africa. We recommend future research that has to be undertaken to address these issues. This research should include investigating species sensitivities in responses to contamination and including insects likes ants and termites in ecological risk assessment studies.

Processing radioactive effluents with ion-exchanging resins: study of result extrapolation; Traitement des effluents radioactifs par resines echangeuses d'ions: etude de l'extrapolation des resultats

Energy Technology Data Exchange (ETDEWEB)

Wormser, G.

1960-05-03

As a previous study showed the ion-exchanging resins could be used in Saclay for the treatment of radioactive effluents, the author reports a study which aimed at investigating to which extent thus obtained results could be extrapolated to the case of higher industrial columns. The author reports experiments which aimed at determining extrapolation modes which could be used for columns of organic resin used for radioactive effluent decontamination. He notably studied whether the Hiester and Vermeulen extrapolation law could be applied. Experiments are performed at constant percolation flow rate, at varying flow rate, and at constant flow rate [French] Plusieurs etudes ont ete faites dans le but d'examiner les possibilites d'emploi des resines echangeuses d'ions pour le traitement des effluents radioactifs. Dans un rapport preliminaire, nous avons montre dans quelles limites un tel procede pouvait etre utilise au Centre d'Etudes Nucleaires de Saclay. Les essais ont ete effectues sur des petites colonnes de resine au laboratoire; il est apparu ensuite necessaire de prevoir dans quelle mesure les resultats ainsi obtenus peuvent etre extrapoles a des colonnes industrielles, de plus grande hauteur. Les experiences dont les resultats sont exposes dans ce rapport, ont pour but de determiner les modes d'extrapolation qui pourraient etre employes pour des colonnes de resine organique utilisees pour la decontamination d'effluents radioactifs. Nous avons en particulier recherche si la loi d'extrapolation de Hiester et Vermeulen qui donne de bons resultats dans le cas de fixation d'ions radioactifs en presence d'un ion macrocomposant sur des terres, pouvait etre appliquee. Les experiences, en nombre limite, ont montre que la loi d'extrapolation de Hiester et Vermeulen pouvait s'appliquer dans le cas de l'effluent considere quand les debits de percolation sont tres faibles; quand ils sont plus forts, les volumes de liquide percoles, a fixation egale, sont proportionnels aux

Settling fluxes and ecotoxicological risk assessment of fine sedimentary metals in Tema Harbour (Ghana).

Science.gov (United States)

Botwe, Benjamin O; Nyarko, Elvis; Lens, Piet N L

2018-01-01

Sediment traps were deployed in the Tema Harbour to estimate the settling fluxes of silt-clay particles and associated metals (Fe, Mn, Pb, Cr, Cu, Zn, Ni, Hg, Sn and As) and characterise their potential ecotoxicological risks. The mean daily settling fluxes of the silt-clay particles and associated metals ranged from 42.7 to 85.0gm -2 d -1 and 1.3×10 -2 to 49.4mgm -2 d -1 , respectively, and were characterised by large fluctuations at each station. The silt-clay and metal fluxes strongly correlated, indicating the important role of the silt-clay particles in metal transport and distribution in the harbour. Geochemical indices indicated anthropogenic influences on the harbour as the Pb, Cr, Zn, Hg, Sn and As content in the settling silt-clay particles exceeded their average crustal concentrations. Sediment quality guidelines indicated these metals pose appreciable ecotoxicological risks, particularly As. Increasing temporal trends in As necessitates increased pollution control efforts at the harbour. Copyright © 2017 Elsevier Ltd. All rights reserved.

Implications of water hardness in ecotoxicological assessments for water quality regulatory purposes: a case study with the aquatic snail Biomphalaria glabrata (Say, 1818

Directory of Open Access Journals (Sweden)

EC Oliveira-Filho

Full Text Available Water hardness is a property depending on the presence of alkaline earth metals, mainly calcium and magnesium. Among the strategies for water quality monitoring, ecotoxicological assays are performed to minimize impacts and classify water bodies. For these laboratory evaluations parameters are previously defined in the guidelines, including water hardness for both cultivation and testing medium. The present work was performed to evaluate the effects of different levels of water hardness on the survival and reproduction of the freshwater snail Biomphalaria glabrata and discuss the influence of natural water hardness on the results of ecotoxicological tests with these environmental samples. Comparing the groups it was possible to observe that those maintained in waters with least hardness had lower reproductive success, while the groups maintained in highest hardness showed better reproduction. These data show that waters with low hardness make the reproduction of the snail B. glabrata unfeasible, and this reveal a problem for ecotoxicity assays using natural water samples.

Characterization of low energy X-rays beams with an extrapolation chamber

International Nuclear Information System (INIS)

Bastos, Fernanda Martins

2015-01-01

In laboratories involving Radiological Protection practices, it is usual to use reference radiations for calibrating dosimeters and to study their response in terms of energy dependence. The International Organization for Standardization (ISO) established four series of reference X-rays beams in the ISO- 4037 standard: the L and H series, as low and high air Kerma rates, respectively, the N series of narrow spectrum and W series of wide spectrum. The X-rays beams with tube potential below 30 kV, called 'low energy beams' are, in most cases, critical as far as the determination of their parameters for characterization purpose, such as half-value layer. Extrapolation chambers are parallel plate ionization chambers that have one mobile electrode that allows variation of the air volume in its interior. These detectors are commonly used to measure the quantity Absorbed Dose, mostly in the medium surface, based on the extrapolation of the linear ionization current as a function of the distance between the electrodes. In this work, a characterization of a model 23392 PTW extrapolation chamber was done in low energy X-rays beams of the ISO- 4037 standard, by determining the polarization voltage range through the saturation curves and the value of the true null electrode spacing. In addition, the metrological reliability of the extrapolation chamber was studied with measurements of the value of leakage current and repeatability tests; limit values were established for the proper use of the chamber. The PTW23392 extrapolation chamber was calibrated in terms of air Kerma in some of the ISO radiation series of low energy; the traceability of the chamber to the National Standard Dosimeter was established. The study of energy dependency of the extrapolation chamber and the assessment of the uncertainties related to the calibration coefficient were also done; it was shown that the energy dependence was reduced to 4% when the extrapolation technique was used. Finally, the first

Chiral and continuum extrapolation of partially-quenched hadron masses

International Nuclear Information System (INIS)

Chris Allton; Wes Armour; Derek Leinweber; Anthony Thomas; Ross Young

2005-01-01

Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement (∼1%) with the experimental value of M ρ from the former approach. These results are extended to the case of the nucleon mass

Chiral and continuum extrapolation of partially-quenched hadron masses

Energy Technology Data Exchange (ETDEWEB)

Chris Allton; Wes Armour; Derek Leinweber; Anthony Thomas; Ross Young

2005-09-29

Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement ({approx}1%) with the experimental value of M{sub {rho}} from the former approach. These results are extended to the case of the nucleon mass.

Predicting structural properties of fluids by thermodynamic extrapolation

Science.gov (United States)

Mahynski, Nathan A.; Jiao, Sally; Hatch, Harold W.; Blanco, Marco A.; Shen, Vincent K.

2018-05-01

We describe a methodology for extrapolating the structural properties of multicomponent fluids from one thermodynamic state to another. These properties generally include features of a system that may be computed from an individual configuration such as radial distribution functions, cluster size distributions, or a polymer's radius of gyration. This approach is based on the principle of using fluctuations in a system's extensive thermodynamic variables, such as energy, to construct an appropriate Taylor series expansion for these structural properties in terms of intensive conjugate variables, such as temperature. Thus, one may extrapolate these properties from one state to another when the series is truncated to some finite order. We demonstrate this extrapolation for simple and coarse-grained fluids in both the canonical and grand canonical ensembles, in terms of both temperatures and the chemical potentials of different components. The results show that this method is able to reasonably approximate structural properties of such fluids over a broad range of conditions. Consequently, this methodology may be employed to increase the computational efficiency of molecular simulations used to measure the structural properties of certain fluid systems, especially those used in high-throughput or data-driven investigations.

A high precision extrapolation method in multiphase-field model for simulating dendrite growth

Science.gov (United States)

Yang, Cong; Xu, Qingyan; Liu, Baicheng

2018-05-01

The phase-field method coupling with thermodynamic data has become a trend for predicting the microstructure formation in technical alloys. Nevertheless, the frequent access to thermodynamic database and calculation of local equilibrium conditions can be time intensive. The extrapolation methods, which are derived based on Taylor expansion, can provide approximation results with a high computational efficiency, and have been proven successful in applications. This paper presents a high precision second order extrapolation method for calculating the driving force in phase transformation. To obtain the phase compositions, different methods in solving the quasi-equilibrium condition are tested, and the M-slope approach is chosen for its best accuracy. The developed second order extrapolation method along with the M-slope approach and the first order extrapolation method are applied to simulate dendrite growth in a Ni-Al-Cr ternary alloy. The results of the extrapolation methods are compared with the exact solution with respect to the composition profile and dendrite tip position, which demonstrate the high precision and efficiency of the newly developed algorithm. To accelerate the phase-field and extrapolation computation, the graphic processing unit (GPU) based parallel computing scheme is developed. The application to large-scale simulation of multi-dendrite growth in an isothermal cross-section has demonstrated the ability of the developed GPU-accelerated second order extrapolation approach for multiphase-field model.

Medical extrapolation chamber dosimeter model XW6012A

International Nuclear Information System (INIS)

Jin Tao; Wang Mi; Wu Jinzheng; Guo Qi

1992-01-01

An extrapolation chamber dosimeter has been developed for clinical dosimetry of electron beams and X-rays from medical linear accelerators. It consists of a new type extrapolation chamber, a water phantom and an intelligent portable instrument. With a thin entrance window and a φ20 mm collecting electrode made of polystyrene, the electrode spacing can be varied from 0.2 to 6 mm. The dosimeter can accomplish dose measurement automatically, and has functions of error self-diagnosis and dose self-recording. The energy range applicable is 0.5-20 MeV, and the dose-rate range 0.02-40 Gy/min. The total uncertainty is 2.7%

Evaluating the efficacy of bioremediating a diesel-contaminated soil using ecotoxicological and bacterial community indices.

Science.gov (United States)

Khudur, Leadin Salah; Shahsavari, Esmaeil; Miranda, Ana F; Morrison, Paul D; Nugegoda, Dayanthi; Ball, Andrew S

2015-10-01

Diesel represents a common environmental contaminant as a result of operation, storage, and transportation accidents. The bioremediation of diesel in a contaminated soil is seen as an environmentally safe approach to treat contaminated land. The effectiveness of the remediation process is usually assessed by the degradation of the total petroleum hydrocarbon (TPH) concentration, without considering ecotoxicological effects. The aim of this study was to assess the efficacy of two bioremediation strategies in terms of reduction in TPH concentration together with ecotoxicity indices and changes in the bacterial diversity assessed using PCR-denaturing gradient gel electrophoresis (DGGE). The biostimulation strategy resulted in a 90 % reduction in the TPH concentration versus 78 % reduction from the natural attenuation strategy over 12 weeks incubation in a laboratory mesocosm-containing diesel-contaminated soil. In contrast, the reduction in the ecotoxicity resulting from the natural attenuation treatment using the Microtox and earthworm toxicity assays was more than double the reduction resulting from the biostimulation treatment (45 and 20 % reduction, respectively). The biostimulated treatment involved the addition of nitrogen and phosphorus in order to stimulate the microorganisms by creating an optimal C:N:P molar ratio. An increased concentration of ammonium and phosphate was detected in the biostimulated soil compared with the naturally attenuated samples before and after the remediation process. Furthermore, through PCR-DGGE, significant changes in the bacterial community were observed as a consequence of adding the nutrients together with the diesel (biostimulation), resulting in the formation of distinctly different bacterial communities in the soil subjected to the two strategies used in this study. These findings indicate the suitability of both bioremediation approaches in treating hydrocarbon-contaminated soil, particularly biostimulation. Although

Ecotoxicological Assessment of Water and Sediment Pollution of the Iskar River bellow Samokov

Directory of Open Access Journals (Sweden)

Ivan Diadovski

2005-04-01

Full Text Available A system of integral ecological indices has been worked out to assess the level of pollution of water and sediments with hazardous substances. A model for the dynamics of the integral index for water and sediments pollution is proposed. This index was applied for ecotoxicological assessment of water and sediments pollution of the Iskar river bellow Samokov. A modification method on time series analysis is applied.

Extrapolation of rate constants of reactions producing H{sub 2} and O{sub 2} in radiolysis of water at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Leblanc, R.; Ghandi, K.; Hackman, B.; Liu, G. [Mount Allison Univ., Sackville, NB (Canada)

2014-07-01

One target of our research is to extrapolate known data on the rate constants of reactions and add corrections to estimate the rate constants at the higher temperatures reached by the SCWR reactors. The focus of this work was to extrapolate known data on the rate constants of reactions that produce Hydrogen or Oxygen with a rate constant below 10{sup 10} mol{sup -1} s{sup -1} at room temperature. The extrapolation is done taking into account the change in the diffusion rate of the interacting species and the cage effect with thermodynamic conditions. The extrapolations are done over a wide temperature range and under isobaric conditions. (author)

Ecotoxicological assessment of bioremediation of a petroleum hydrocarbon-contaminated soil

International Nuclear Information System (INIS)

Renoux, A.Y.; Tyagi, R.D.; Samson, R.

1995-01-01

A battery of bioassays [barley seed germination, barley plant growth, lettuce seed germination, worm mortality, Microtox reg-sign, lettuce root elongation, algae Selenastrum capricornutum growth, Daphnia magna mortality, and SOS Chromotest (±S9)] was used to assess an above-ground heap pile treatment of a soil contaminated with aliphatic petroleum hydrocarbons (12 to 24 carbons). Despite an initial oil and grease concentration of 2,000 mg/kg, no significant (geno)toxicity was apparent in the soil sample before treatment. During the treatment, which decreased oil and grease concentrations to 800 mg/kg, slight toxicity was revealed by three bioassays (barley seed germination, worm mortality, Daphnia magna mortality), and a significant increase in genotoxicity was measured with the SOS Chromotest (± S9). It appears that ecotoxicological evaluation revealed harmful condition(s) that were not detected by chemical assessment. This suggests that the remediation had ceased before complete detoxification occurred. This phenomenon must be further investigated, however, to furnish solid conclusions on the toxicological effectiveness of the biotreatment

Ecotoxicological hazard assessment of hydrocarbon contaminated soils: A case study

International Nuclear Information System (INIS)

Roy, Y.; Pauwels, S.J.; Chasse, R.

1994-01-01

The Ecotoxicological Hazard Assessment (EHA) developed by the Quebec Ministry of Environment and Wildlife was used as part of the management scheme of contaminated soils from a former refinery. The study consists of assessing five types of soils (reference, heavily contaminated, slightly contaminated, thermally-treated, and biotreated) to determine their relative intrinsic hazard. During the exploratory activities a series of ten assessment endpoints where identified to support this typical EHA. During SOURCE characterization, the physicochemical make-up of the soils is described and the presence and concentrations of priority pollutants is determined. During FATE characterization, the potential for bioconcentration, mobility, and persistence of pollutants is determined. During EFFECTS characterization, the soils and their leachates are tested using standard terrestrial and aquatic bioassays. The data from the toxicological and analytical testing program are evaluated semi-quantitatively on the basis of a scoring system developed by consensus. The discussion will highlight how data are used within an EHA to streamline the decision-making process regarding the follow-up cleanup and disposal of contaminated soils

Extrapolation of zircon fission-track annealing models

International Nuclear Information System (INIS)

Palissari, R.; Guedes, S.; Curvo, E.A.C.; Moreira, P.A.F.P.; Tello, C.A.; Hadler, J.C.

2013-01-01

One of the purposes of this study is to give further constraints on the temperature range of the zircon partial annealing zone over a geological time scale using data from borehole zircon samples, which have experienced stable temperatures for ∼1 Ma. In this way, the extrapolation problem is explicitly addressed by fitting the zircon annealing models with geological timescale data. Several empirical model formulations have been proposed to perform these calibrations and have been compared in this work. The basic form proposed for annealing models is the Arrhenius-type model. There are other annealing models, that are based on the same general formulation. These empirical model equations have been preferred due to the great number of phenomena from track formation to chemical etching that are not well understood. However, there are two other models, which try to establish a direct correlation between their parameters and the related phenomena. To compare the response of the different annealing models, thermal indexes, such as closure temperature, total annealing temperature and the partial annealing zone, have been calculated and compared with field evidence. After comparing the different models, it was concluded that the fanning curvilinear models yield the best agreement between predicted index temperatures and field evidence. - Highlights: ► Geological data were used along with lab data for improving model extrapolation. ► Index temperatures were simulated for testing model extrapolation. ► Curvilinear Arrhenius models produced better geological temperature predictions

Endangered species toxicity extrapolation using ICE models

Science.gov (United States)

The National Research Council’s (NRC) report on assessing pesticide risks to threatened and endangered species (T&E) included the recommendation of using interspecies correlation models (ICE) as an alternative to general safety factors for extrapolating across species. ...

Functional differential equations with unbounded delay in extrapolation spaces

Directory of Open Access Journals (Sweden)

Mostafa Adimy

2014-08-01

Full Text Available We study the existence, regularity and stability of solutions for nonlinear partial neutral functional differential equations with unbounded delay and a Hille-Yosida operator on a Banach space X. We consider two nonlinear perturbations: the first one is a function taking its values in X and the second one is a function belonging to a space larger than X, an extrapolated space. We use the extrapolation techniques to prove the existence and regularity of solutions and we establish a linearization principle for the stability of the equilibria of our equation.

The developing framework of marine ecotoxicology: Pollutants as a variable in marine ecosystems?

Science.gov (United States)

Luoma, Samuel N.

1996-01-01

Marine ecosystems include a subset in which at least some interrelated geochemical, biochemical, physiological, population and community characteristics are changed by pollutants. Moderate contamination is relatively widespread in coastal and estuarine ecosystems, so the subset of ecosystems with at least some processes affected could be relatively large. Pollutant influences have changed and will probably continue to change on time scales of decades. Biological exposures and dose in such ecosystems are species-specific and determined by how the species is exposed to different environmental media and the geochemistry of individual pollutants within those media. Bioaccumulation models offer significant promise for interpreting such exposures. Biological responses to pollutants need to be more directly linked to exposure and dose. At the level of the individual this might be improved by better understanding relationships between tissue concentrations of pollutants and responses to pollutants. Multi-discipline field and laboratory studies combined with advanced understanding of some basic processes have reduced the ambiguities in interpreting a few physiological/organismic responses to pollutants in nature. Recognition of pollutant-induced patterns in population responses could lead to similar advances. A rational framework for ecotoxicology is developing, but its further advance is dependent upon better integration of ecotoxicology with basic marine ecology and biology.

Dead time corrections using the backward extrapolation method

Energy Technology Data Exchange (ETDEWEB)

Gilad, E., E-mail: gilade@bgu.ac.il [The Unit of Nuclear Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Dubi, C. [Department of Physics, Nuclear Research Center NEGEV (NRCN), Beer-Sheva 84190 (Israel); Geslot, B.; Blaise, P. [DEN/CAD/DER/SPEx/LPE, CEA Cadarache, Saint-Paul-les-Durance 13108 (France); Kolin, A. [Department of Physics, Nuclear Research Center NEGEV (NRCN), Beer-Sheva 84190 (Israel)

2017-05-11

Dead time losses in neutron detection, caused by both the detector and the electronics dead time, is a highly nonlinear effect, known to create high biasing in physical experiments as the power grows over a certain threshold, up to total saturation of the detector system. Analytic modeling of the dead time losses is a highly complicated task due to the different nature of the dead time in the different components of the monitoring system (e.g., paralyzing vs. non paralyzing), and the stochastic nature of the fission chains. In the present study, a new technique is introduced for dead time corrections on the sampled Count Per Second (CPS), based on backward extrapolation of the losses, created by increasingly growing artificially imposed dead time on the data, back to zero. The method has been implemented on actual neutron noise measurements carried out in the MINERVE zero power reactor, demonstrating high accuracy (of 1–2%) in restoring the corrected count rate. - Highlights: • A new method for dead time corrections is introduced and experimentally validated. • The method does not depend on any prior calibration nor assumes any specific model. • Different dead times are imposed on the signal and the losses are extrapolated to zero. • The method is implemented and validated using neutron measurements from the MINERVE. • Result show very good correspondence to empirical results.

Environmental fate and ecotoxicological risk of the antibiotic sulfamethoxazole across the Katari catchment (Bolivian Altiplano) : application of the GREAT-ER model

OpenAIRE

Archundia, D.; Boithias, Laurie; Duwig, Céline; Morel, M. C.; Aviles, G. F.; Martins, J. M. F.

2018-01-01

Antibiotics are emergent contaminants that can induce adverse effects in terrestrial and aquatic organisms. The surface water compartment is of particular concern as it receives direct waste water discharge. Modeling is highlighted as an essential tool to understand the fate and behavior of these compounds and to assess their eco-toxicological risk. This study aims at testing the ability of the GREAT-ER model in simulating sulfamethoxazole (SMX) concentrations in the surface waters of the ari...

On the existence of the optimal order for wavefunction extrapolation in Born-Oppenheimer molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Fang, Jun; Wang, Han, E-mail: wang-han@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing (China); CAEP Software Center for High Performance Numerical Simulation, Beijing (China); Gao, Xingyu; Song, Haifeng [Institute of Applied Physics and Computational Mathematics, Beijing (China); CAEP Software Center for High Performance Numerical Simulation, Beijing (China); Laboratory of Computational Physics, Beijing (China)

2016-06-28

Wavefunction extrapolation greatly reduces the number of self-consistent field (SCF) iterations and thus the overall computational cost of Born-Oppenheimer molecular dynamics (BOMD) that is based on the Kohn–Sham density functional theory. Going against the intuition that the higher order of extrapolation possesses a better accuracy, we demonstrate, from both theoretical and numerical perspectives, that the extrapolation accuracy firstly increases and then decreases with respect to the order, and an optimal extrapolation order in terms of minimal number of SCF iterations always exists. We also prove that the optimal order tends to be larger when using larger MD time steps or more strict SCF convergence criteria. By example BOMD simulations of a solid copper system, we show that the optimal extrapolation order covers a broad range when varying the MD time step or the SCF convergence criterion. Therefore, we suggest the necessity for BOMD simulation packages to open the user interface and to provide more choices on the extrapolation order. Another factor that may influence the extrapolation accuracy is the alignment scheme that eliminates the discontinuity in the wavefunctions with respect to the atomic or cell variables. We prove the equivalence between the two existing schemes, thus the implementation of either of them does not lead to essential difference in the extrapolation accuracy.

UFOs: Observations, Studies and Extrapolations

CERN Document Server

Baer, T; Barnes, M J; Bartmann, W; Bracco, C; Carlier, E; Cerutti, F; Dehning, B; Ducimetière, L; Ferrari, A; Ferro-Luzzi, M; Garrel, N; Gerardin, A; Goddard, B; Holzer, E B; Jackson, S; Jimenez, J M; Kain, V; Zimmermann, F; Lechner, A; Mertens, V; Misiowiec, M; Nebot Del Busto, E; Morón Ballester, R; Norderhaug Drosdal, L; Nordt, A; Papotti, G; Redaelli, S; Uythoven, J; Velghe, B; Vlachoudis, V; Wenninger, J; Zamantzas, C; Zerlauth, M; Fuster Martinez, N

2012-01-01

UFOs (“ Unidentified Falling Objects”) could be one of the major performance limitations for nominal LHC operation. Therefore, in 2011, the diagnostics for UFO events were significantly improved, dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge is summarized and extrapolations for LHC operation in 2012 and beyond are presented. Mitigation strategies are proposed and related tests and measures for 2012 are specified.

Extrapolation bias and the predictability of stock returns by price-scaled variables

NARCIS (Netherlands)

Cassella, Stefano; Gulen, H.

Using survey data on expectations of future stock returns, we recursively estimate the degree of extrapolative weighting in investors' beliefs (DOX). In an extrapolation framework, DOX determines the relative weight investors place on recent-versus-distant past returns. DOX varies considerably over

Ecotoxicological Assessment of Aquatic Genotoxicity Using the Comet Assay

Directory of Open Access Journals (Sweden)

KHUSNUL YAQIN

2006-09-01

Full Text Available Comet assay is a novel biological analysis, which is a sensitive, flexible, simple, rapid, and inexpensive method to assess aquatic genotoxicant. Since Singh and co-workers developed the method in 1988, its use has increased exponentially in various fields. This review discourses on the application of this assay in aquatic ecosystems. Various types of cells from various aquatic organisms have been tested by various genotoxicant both direct- and indirect-acting using the comet assay. The applications of this assay suggest that it is a useful assay to assess aquatic genotoxicants. However, there are some factors, which should be taken into account when using this assay as aquatic ecotoxicological assessment device such as inter-animal and cell variability.

Assessment of the application of an ecotoxicological procedure to screen illicit toxic discharges in domestic septic tank sludge.

Science.gov (United States)

López-Gastey, J; Choucri, A; Robidoux, P Y; Sunahara, G I

2000-06-01

An innovative screening procedure has been developed to detect illicit toxic discharges in domestic septic tank sludge hauled to the Montreal Urban Community waste-water treatment plant. This new means of control is based on an integrative approach, using bioassays and chemical analyses. Conservative criteria are applied to detect abnormal toxicity with great reliability while avoiding false positive results. The complementary data obtained from toxicity tests and chemical analyses support the use of this efficient and easy-to-apply procedure. This study assesses the control procedure in which 231 samples were analyzed over a 30-month period. Data clearly demonstrate the deterrent power of an efficient control procedure combined with a public awareness campaign among the carriers. In the first 15 months of application, between January 1996 and March 1997, approximately 30% of the 123 samples analyzed showed abnormal toxicity. Between April 1997 and June 1998, that is, after a public hearing presentation of this procedure, this proportion dropped significantly to approximately 9% based on 108 analyzed samples. The results of a 30-month application of this new control procedure show the superior efficiency of the ecotoxicological approach compared with the previously used chemical control procedure. To be able to apply it effectively and, if necessary, to apply the appropriate coercive measures, ecotoxicological criteria should be included in regulatory guidelines.

Ecorad 2001. Radioecology/ ecotoxicology in continental and estuarine media; Ecorad 2001. Radioecologie / ecotoxicologie des milieux continentaux et estuariens

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-11-01

This conference about radioecology is divided in eight sessions that concern the following subjects: behaviour and transfer of radionuclides in soil, in terrestrial ecosystems (plants and animal transfers), in freshwater ecosystems, in estuaries are the subjects of the four first sessions. The effects of toxicants in environment are detailed in the fifth session. The sixth session is devoted to the methods of measurement of environmental radioactivity. The seventh session is relative to the consequences of accidental and chronicle situations (Chernobyl consequences, countermeasures and decontamination). This conference ends with the ethical aspects of environmental radio ecotoxicology with the eighth session. (N.C.)

Micro-computed tomography (μCT) as a novel method in ecotoxicology — determination of morphometric and somatic data in rainbow trout (Oncorhynchus mykiss)

International Nuclear Information System (INIS)

Brinkmann, Markus; Rizzo, Larissa Y.; Lammers, Twan; Gremse, Felix; Schiwy, Sabrina; Kiessling, Fabian; Hollert, Henner

2016-01-01

Fish are important sentinel organisms for the assessment of water quality and play a central role in ecotoxicological research. Of particular importance to the assessment of health and fitness of fish stocks in response to environmental conditions or pollution are morphometric (e.g. Fulton's condition index) and somatic indices (e.g. hepatosomatic, and gonadosomatic index). Standard measurements of somatic indices are invasive and require, by definition, the sacrifice of examined animals, thus prohibiting longitudinal studies and relocation of animals captured in the field. As a potential solution, in the present study, we propose the use of micro-computed tomography (μCT) as imaging modality to non-invasively tomographically image rainbow trout (Oncorhynchus mykiss) exposed to different sediment suspensions. We here demonstrate that μCT can be used as a tool to reliably measure the volumes of different organs, which could then be applied as a substitute of their weights in calculation of somatic indices. To the best of our knowledge, this study is the first to report the results of μCT analyses in the context of ecotoxicological research in rainbow trout. It has the potential to greatly increase the information value of experiments conducted with fish and also to potentially reduce the number of animals required for studying temporal effects through facilitating longitudinal studies within the same individuals. - Highlights: • μCT was used for volumetric imaging sediment-exposed and unexposed rainbow trout • Liver volumes determined by μCT were highly correlated with liver weights. • The perfusion of organs in fish could also be studied by means of μCT. • It was shown that μCT is a useful tool in context of ecotoxicological research.

The Extrapolation-Accelerated Multilevel Aggregation Method in PageRank Computation

Directory of Open Access Journals (Sweden)

Bing-Yuan Pu

2013-01-01

Full Text Available An accelerated multilevel aggregation method is presented for calculating the stationary probability vector of an irreducible stochastic matrix in PageRank computation, where the vector extrapolation method is its accelerator. We show how to periodically combine the extrapolation method together with the multilevel aggregation method on the finest level for speeding up the PageRank computation. Detailed numerical results are given to illustrate the behavior of this method, and comparisons with the typical methods are also made.

Study of energy dependence of a extrapolation chamber in low energy X-rays beams

International Nuclear Information System (INIS)

Bastos, Fernanda M.; Silva, Teogenes A. da

2014-01-01

This work was with the main objective to study the energy dependence of extrapolation chamber in low energy X-rays to determine the value of the uncertainty associated with the variation of the incident radiation energy in the measures in which it is used. For studying the dependence of energy, were conducted comparative ionization current measurements between the extrapolation chamber and two ionization chambers: a chamber mammography, RC6M model, Radcal with energy dependence less than 5% and a 2575 model radioprotection chamber NE Technology; both chambers have very thin windows, allowing its application in low power beams. Measurements were made at four different depths of 1.0 to 4.0 mm extrapolation chamber, 1.0 mm interval, for each reference radiation. The study showed that there is a variable energy dependence on the volume of the extrapolation chamber. In other analysis, it is concluded that the energy dependence of extrapolation chamber becomes smaller when using the slope of the ionization current versus depth for the different radiation reference; this shows that the extrapolation technique, used for the absorbed dose calculation, reduces the uncertainty associated with the influence of the response variation with energy radiation

New approach to weight-of-evidence assessment of ecotoxicological effects in regulatory decision-making.

Science.gov (United States)

Hall, A Tilghman; Belanger, Scott E; Guiney, Pat D; Galay-Burgos, Malyka; Maack, Gerd; Stubblefield, William; Martin, Olwenn

2017-07-01

Ecological risk assessments and risk management decisions are only as sound as the underlying information and processes to integrate them. It is important to develop transparent and reproducible procedures a priori to integrate often-heterogeneous evidence. Current weight-of-evidence (WoE) approaches for effects or hazard assessment tend to conflate aspects of the assessment of the quality of the data with the strength of the body of evidence as a whole. We take forward recent developments in the critical appraisal of the reliability and relevance of individual ecotoxicological studies as part of the effect or hazard assessment of prospective risk assessments and propose a streamlined WoE approach. The aim is to avoid overlap and double accounting of criteria used in reliability and relevance with that used in current WoE methods. The protection goals, problem formulation, and evaluation process need to be clarified at the outset. The data are first integrated according to lines of evidence (LoEs), typically mechanistic insights (e.g., cellular, subcellular, genomic), in vivo experiments, and higher-tiered field or observational studies. Data are then plotted on the basis of both relevance and reliability scores or categories. This graphical approach provides a means to visually assess and communicate the credibility (reliability and relevance of available individual studies), quantity, diversity, and consistency of the evidence. In addition, the external coherence of the body of evidence needs to be considered. The final step in the process is to derive an expression of the confidence in the conclusions of integrating the information considering these 5 aspects in the context of remaining uncertainties. We suggest that this streamlined approach to WoE for the effects or hazard characterization should facilitate reproducible and transparent assessments of data across different regulatory requirements. Integr Environ Assess Manag 2017;13:573-579. © 2017 The Authors

Loop integration results using numerical extrapolation for a non-scalar integral

International Nuclear Information System (INIS)

Doncker, E. de; Shimizu, Y.; Fujimoto, J.; Yuasa, F.; Kaugars, K.; Cucos, L.; Van Voorst, J.

2004-01-01

Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards

Soil quality in the Lomellina area using in vitro models and ecotoxicological assays

Energy Technology Data Exchange (ETDEWEB)

Baderna, Diego, E-mail: diego.baderna@marionegri.it [Laboratory of Environmental Chemistry and Toxicology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Colombo, Andrea [Laboratory of Environmental Chemistry and Toxicology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Romeo, Margherita [Department of Molecular Biochemistry and Pharmacology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Cambria, Felice; Teoldi, Federico; Lodi, Marco [Laboratory of Environmental Chemistry and Toxicology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Diomede, Luisa [Department of Molecular Biochemistry and Pharmacology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Benfenati, Emilio [Laboratory of Environmental Chemistry and Toxicology, IRCCS—Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy)

2014-08-15

Soil quality is traditionally evaluated by chemical characterization to determine levels of pollutants. Biological tools are now employed for soil monitoring since they can take account of the global biological effects induced by all xenobiotics. A combined monitoring of soils based on chemical analyses, human-related in vitro models and ecotoxicological assay was applied in the Lomellina, a semirural area of northern Italy. Chemical characterization indicated overall good quality of the soils, with low levels of toxic and carcinogenic pollutants such as heavy metals, PAHs, PCDD/Fs and PCBs. HepG2 cells were used as a model for the human liver and BALB/c 3T3 cells to evaluate carcinogenic potential. Cells were treated with soil extractable organic matter (EOM) and the MTS assay, DNA release and morphological transformation were selected as endpoints for toxicity and carcinogenicity. Soil EOMs induced dose-dependent inhibition of cell growth at low doses and cytotoxicity only at doses of 500 and 1000 mg soil equivalents/ml. Potential issues for human health can be hypothesized after ingestion of soil samples from some sites. No statistically significant inductions of foci were recorded after exposure to EOMs, indicating that the levels of the soil-extracted organic pollutants were too low to induce carcinogenesis in our experimental conditions. An acute phytotoxicity test and studies on Caenorhabditis elegans were used as ecotoxicological assays for plants and small invertebrates. No significant alerts for ecotoxicity were found. In this proposed case study, HepG2 cells detected differences in the toxicity of soil EOMs, indicating that this cell line could be appropriate to assess the potential harm caused by the ingestion of contaminated soil. Additional information on the carcinogenic potential of mixtures was provided by the cell transformation assay, strengthening the combined approach. - Highlights: • A combined approach for evaluation of soil quality is

Biosimilars: From Extrapolation into Off Label Use.

Science.gov (United States)

Zhao, Sizheng; Nair, Jagdish R; Moots, Robert J

2017-01-01

Biologic drugs have revolutionised the management of many inflammatory conditions. Patent expirations have stimulated development of highly similar but non-identical molecules, the biosimilars. Extrapolation of indications is a key concept in the development of biosimilars. However, this has been met with concerns around mechanisms of action, equivalence in efficacy and immunogenicity, which are reviewed in this article. Narrative overview composed from literature search and the authors' experience. Literature search included Pubmed, Web of Science, and online document archives of the Food and Drug Administration and European Medicines Agency. The concepts of biosimilarity and extrapolation of indications are revisited. Concerns around extrapolation are exemplified using the biosimilar infliximab, CT-P13, focusing on mechanisms of action, immunogenicity and trial design. The opportunities and cautions for using biologics and biosimilars in unlicensed inflammatory conditions are reviewed. Biosimilars offer many potential opportunities in improving treatment access and increasing treatment options. The high cost associated with marketing approval means that many bio-originators may never become licenced for rarer inflammatory conditions, despite clinical efficacy. Biosimilars, with lower acquisition cost, may improve access for off-label use of biologics in the management of these patients. They may also provide opportunities to explore off-label treatment of conditions where biologic therapy is less established. However, this potential advantage must be balanced with the awareness that off-label prescribing can potentially expose patients to risky and ineffective treatments. Post-marketing surveillance is critical to developing long-term evidence to provide assurances on efficacy as well as safety. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Characterization of an extrapolation chamber in a 90Sr/90Y beta radiation field

International Nuclear Information System (INIS)

Oramas Polo, I.; Tamayo Garcia, J. A.

2015-01-01

The extrapolation chamber is a parallel plate chamber and variable volume based on the Bragg-Gray theory. It determines in absolute mode, with high accuracy the dose absorbed by the extrapolation of the ionization current measured for a null distance between the electrodes. This camera is used for dosimetry of external beta rays for radiation protection. This paper presents the characterization of an extrapolation chamber in a 90 Sr/ 90 Y beta radiation field. The absorbed dose rate to tissue at a depth of 0.07 mm was calculated and is (0.13206±0.0028) μGy. The extrapolation chamber null depth was determined and its value is 60 μm. The influence of temperature, pressure and humidity on the value of the corrected current was also evaluated. Temperature is the parameter that has more influence on this value and the influence of pressure and the humidity is not very significant. Extrapolation curves were obtained. (Author)

Eco-toxicological studies of diesel and biodiesel fuels in aerated soil

International Nuclear Information System (INIS)

Lapinskiene, Asta; Martinkus, Povilas; Rebzdaite, Vilija

2006-01-01

The goal of this study was to compare diesel fuel to biodiesel fuel by determining the toxicity of analyzed materials and by quantitatively evaluating the microbial transformation of these materials in non-adapted aerated soil. The toxicity levels were determined by measuring the respiration of soil microorganisms as well as the activity of soil dehydrogenases. The quantitative evaluation of biotransformation of analyzed materials was based on the principle of balancing carbon in the following final products: (a) carbon dioxide; (b) humus compounds; (c) the remainder of non-biodegraded analyzed material; and (d) intermediate biodegradation products and the biomass of microorganisms. The results of these studies indicate that diesel fuel has toxic properties at concentrations above 3% (w/w), while biodiesel fuel has none up to a concentration of 12% (w/w). The diesel fuel is more resistant to biodegradation and produces more humus products. The biodiesel is easily biotransformed. - The comparison of diesel and biodiesel fuels' eco-toxicological parameters in non-adapted aerated soil is relevant when considering the effects of these substances on the environment in cases of accidental spills

The extrapolation of creep rupture data by PD6605 - An independent case study

Energy Technology Data Exchange (ETDEWEB)

Bolton, J., E-mail: john.bolton@uwclub.net [65 Fisher Avenue, Rugby, Warks CV22 5HW (United Kingdom)

2011-04-15

The worked example presented in BSI document PD6605-1:1998, to illustrate the selection, validation and extrapolation of a creep rupture model using statistical analysis, was independently examined. Alternative rupture models were formulated and analysed by the same statistical methods, and were shown to represent the test data more accurately than the original model. Median rupture lives extrapolated from the original and alternative models were found to diverge widely under some conditions of practical interest. The tests prescribed in PD6605 and employed to validate the original model were applied to the better of the alternative models. But the tests were unable to discriminate between the two, demonstrating that these tests fail to ensure reliability in extrapolation. The difficulties of determining when a model is sufficiently reliable for use in extrapolation are discussed and some proposals are made.

Influence of test conditions and exposure duration on the result of ecotoxicological tests

DEFF Research Database (Denmark)

Rosenkrantz, Rikke Tjørnhøj

be calculated from results of ecotoxicological tests performed according to internationally approved guidelines, such as from the Organisation for Economic Co-operation and Development (OECD) or International Standardization Organisation (ISO). Such guidelines were originally developed to enable classification......H and exposure duration on the toxicity recorded in tests using four sulfonylurea herbicides (SUs) and the aquatic macrophyte Lemna gibba as study objects. The study showed that changing the physical and chemical test conditions influenced the toxicity of sulfonylurea herbicides towards L. gibba. Lowering...

NLT and extrapolated DLT:3-D cinematography alternatives for enlarging the volume of calibration.

Science.gov (United States)

Hinrichs, R N; McLean, S P

1995-10-01

This study investigated the accuracy of the direct linear transformation (DLT) and non-linear transformation (NLT) methods of 3-D cinematography/videography. A comparison of standard DLT, extrapolated DLT, and NLT calibrations showed the standard (non-extrapolated) DLT to be the most accurate, especially when a large number of control points (40-60) were used. The NLT was more accurate than the extrapolated DLT when the level of extrapolation exceeded 100%. The results indicated that when possible one should use the DLT with a control object, sufficiently large as to encompass the entire activity being studied. However, in situations where the activity volume exceeds the size of one's DLT control object, the NLT method should be considered.

Development of preliminary trigger values for selected pollutants for the protection of soils as a habitat for soil organisms; Entwicklungen von Pruefwertempfehlungen fuer ausgewaehlte Schadstoffe zum Schutz des Bodens als Lebensraum fuer Bodenorganismen

Energy Technology Data Exchange (ETDEWEB)

Wilke, B.M. [Technische Univ. Berlin (Germany). Inst. fuer Oekologie; Hund-Rinke, K. [FhG-IUCT Schmallenberg (Germany); Pieper, S. [Freie Univ. Berlin (Germany). Inst. fuer Biologie; Roembke, J. [ECT Oekotoxikologie GmbH, Floersheim (Germany); Marschner, A. [Umweltbundesamt, Berlin (Germany)

2004-07-01

Goal and Scope. In the German Federal Soil Protection and Contaminated Sites Ordinance there are no ecotoxicological trigger values for the protection of soil as a habitat for soil organisms. The objective of this study was to derive preliminary trigger values for the habitat function of soils. This was done by collecting data on the impact of priority pollutants on soil organisms and plants followed by the parallel use of the Factorial Application Method (FAME) and Distribution Based Extrapolation (DIBAEX) and a final verification of the plausibility of the calculated trigger values by means of an ecotoxicological test battery. Methods. Data on the effects of pollutants on soil organisms and plants were recorded in a specific database (Soil Value). Subsequently, we derived so-called ''working trigger values'' using the extrapolation methods FAME (factorial application method) and DIBAEX (distribution based extrapolation). In the second phase of the project, we verified experimentally the plausibility of these values by means of an ecotoxicological test battery. Test substrate was a sandy soil with low sorption capacity and organic carbon content which was mixed with fresh pollutants (e.g. heavy metal salts) and polluted soil material from contaminated sites (aged contamination), respectively. Organisms tested were microorganisms, plants, earthworms, springtails and nematodes. Results and Conclusions. We calculated working trigger values for 12 pollutants based on 900 datasets compiled in the data base. The lavoratory investigations showed the freshly added contaminants to be less strongly adsorbed to the soil than those added by the use of contaminated soil material. Nevertheless, aged contaminations displayed often the same inhibitive effects as the freshly added chemicals. The results achieved in the second phase of the project were also recorded in the Soil-Value database. Based on the new data set, final trigger values were derived for the

Extrapolation of vertical target motion through a brief visual occlusion.

Science.gov (United States)

Zago, Myrka; Iosa, Marco; Maffei, Vincenzo; Lacquaniti, Francesco

2010-03-01

It is known that arbitrary target accelerations along the horizontal generally are extrapolated much less accurately than target speed through a visual occlusion. The extent to which vertical accelerations can be extrapolated through an occlusion is much less understood. Here, we presented a virtual target rapidly descending on a blank screen with different motion laws. The target accelerated under gravity (1g), decelerated under reversed gravity (-1g), or moved at constant speed (0g). Probability of each type of acceleration differed across experiments: one acceleration at a time, or two to three different accelerations randomly intermingled could be presented. After a given viewing period, the target disappeared for a brief, variable period until arrival (occluded trials) or it remained visible throughout (visible trials). Subjects were asked to press a button when the target arrived at destination. We found that, in visible trials, the average performance with 1g targets could be better or worse than that with 0g targets depending on the acceleration probability, and both were always superior to the performance with -1g targets. By contrast, the average performance with 1g targets was always superior to that with 0g and -1g targets in occluded trials. Moreover, the response times of 1g trials tended to approach the ideal value with practice in occluded protocols. To gain insight into the mechanisms of extrapolation, we modeled the response timing based on different types of threshold models. We found that occlusion was accompanied by an adaptation of model parameters (threshold time and central processing time) in a direction that suggests a strategy oriented to the interception of 1g targets at the expense of the interception of the other types of tested targets. We argue that the prediction of occluded vertical motion may incorporate an expectation of gravity effects.

Melting of “non-magic” argon clusters and extrapolation to the bulk limit

International Nuclear Information System (INIS)

Senn, Florian; Wiebke, Jonas; Schumann, Ole; Gohr, Sebastian; Schwerdtfeger, Peter; Pahl, Elke

2014-01-01

The melting of argon clusters Ar N is investigated by applying a parallel-tempering Monte Carlo algorithm for all cluster sizes in the range from 55 to 309 atoms. Extrapolation to the bulk gives a melting temperature of 85.9 K in good agreement with the previous value of 88.9 K using only Mackay icosahedral clusters for the extrapolation [E. Pahl, F. Calvo, L. Koči, and P. Schwerdtfeger, “Accurate melting temperatures for neon and argon from ab initio Monte Carlo simulations,” Angew. Chem., Int. Ed. 47, 8207 (2008)]. Our results for argon demonstrate that for the extrapolation to the bulk one does not have to restrict to magic number cluster sizes in order to obtain good estimates for the bulk melting temperature. However, the extrapolation to the bulk remains a problem, especially for the systematic selection of suitable cluster sizes

SNSEDextend: SuperNova Spectral Energy Distributions extrapolation toolkit

Science.gov (United States)

Pierel, Justin D. R.; Rodney, Steven A.; Avelino, Arturo; Bianco, Federica; Foley, Ryan J.; Friedman, Andrew; Hicken, Malcolm; Hounsell, Rebekah; Jha, Saurabh W.; Kessler, Richard; Kirshner, Robert; Mandel, Kaisey; Narayan, Gautham; Filippenko, Alexei V.; Scolnic, Daniel; Strolger, Louis-Gregory

2018-05-01

SNSEDextend extrapolates core-collapse and Type Ia Spectral Energy Distributions (SEDs) into the UV and IR for use in simulations and photometric classifications. The user provides a library of existing SED templates (such as those in the authors' SN SED Repository) along with new photometric constraints in the UV and/or NIR wavelength ranges. The software then extends the existing template SEDs so their colors match the input data at all phases. SNSEDextend can also extend the SALT2 spectral time-series model for Type Ia SN for a "first-order" extrapolation of the SALT2 model components, suitable for use in survey simulations and photometric classification tools; as the code does not do a rigorous re-training of the SALT2 model, the results should not be relied on for precision applications such as light curve fitting for cosmology.

Preliminary assays for lemongrass essential oil ecotoxicological test in D. similis and C. silvestrii submitted to gamma radiation

International Nuclear Information System (INIS)

Gimiliani, Giovana T.; Rogero, Sizue O.; Rogero, Jose R.; Cruz, Aurea S.

2011-01-01

Pharmaceutical products are of great interest in ecotoxicological studies due to being found some of these products in the superficial waters and sediments, water and sewage treatment effluents. It was verified an increase of insect repellent chemical products in the aquatic environment because of the increase of diseases transmitted by mosquitoes like dengue. As these compounds show toxicity, the use of essential oils natural products with repellent properties is increasing and the literature about the impact in the aquatic environment is scarce. The hydric frame would suffer natural radiation and radiations from energy generation nuclear plants impacts fall out of tests and nuclear accidents. There is no universal definition of environmental protection and there are few studies on radiation effects in the aquatic environment. In this study was determined the lemon grass essential oil toxicity level as well as the lethal dose of ionizing radiation, LD 50 , in aquatic organisms. Cytotoxicity test was performed by in vitro neutral red uptake method in NCTC clone L929 cell line. In the LD 50 test aquatic organisms were submitted to gamma radiation. The essential oil of lemongrass Cymbopogon flexuosus showed cytotoxicity index IC 50 about 50μg.mL -1 . The LD 50 for Daphnia similis was 242 Gy and Ceriodaphnia silvestrii about 525 Gy. Studies will be continued with acute and chronic ecotoxicological tests of lemongrass essential oil in natural organisms and in organisms submitted to gamma radiation, utilizing the results obtained in this work. (author)

A simple extrapolation of thermodynamic perturbation theory to infinite order

International Nuclear Information System (INIS)

Ghobadi, Ahmadreza F.; Elliott, J. Richard

2015-01-01

Recent analyses of the third and fourth order perturbation contributions to the equations of state for square well spheres and Lennard-Jones chains show trends that persist across orders and molecular models. In particular, the ratio between orders (e.g., A 3 /A 2 , where A i is the ith order perturbation contribution) exhibits a peak when plotted with respect to density. The trend resembles a Gaussian curve with the peak near the critical density. This observation can form the basis for a simple recursion and extrapolation from the highest available order to infinite order. The resulting extrapolation is analytic and therefore cannot fully characterize the critical region, but it remarkably improves accuracy, especially for the binodal curve. Whereas a second order theory is typically accurate for the binodal at temperatures within 90% of the critical temperature, the extrapolated result is accurate to within 99% of the critical temperature. In addition to square well spheres and Lennard-Jones chains, we demonstrate how the method can be applied semi-empirically to the Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT)

Chemical and ecotoxicological evaluation of biochar produced from residues of biogas production.

Science.gov (United States)

Stefaniuk, Magdalena; Oleszczuk, Patryk; Bartmiński, Piotr

2016-11-15

Analyses were carried out for biochars produced at three temperatures of pyrolysis (400, 600 and 800°C) from solid residue from biogas production (RBP). Separated and non-separated RBP from biogas plants employing different biogas production conditions were pyrolyzed. The contents of heavy metals and polycyclic aromatic hydrocarbons (PAHs) (16 PAH US EPA) were analyzed in biochars. The analyses showed that with an increased pyrolysis temperature, there was an increase in the contents of PAHs and of certain heavy metals (Cr, Cu, Cd, Pb and Mn). In the ecotoxicological tests, it was noted that the effect depended on the temperature of pyrolysis and on the feedstock from which the biochar was produced. The least harmful effect on the test organisms was from biochar produced by separated RBP in a biogas plant operating in mesophilic conditions. The most negative effect on the test organisms was characteristic of biochar produced from non-separated mesophilic RBP. This study shows that the main factors determining the level of toxicity of biochars produced from RBP towards various living organisms are both the method of feedstock production and the temperature at which the process of pyrolysis is conducted. Copyright © 2016 Elsevier B.V. All rights reserved.

Micro-computed tomography (μCT) as a novel method in ecotoxicology — determination of morphometric and somatic data in rainbow trout (Oncorhynchus mykiss)

Energy Technology Data Exchange (ETDEWEB)

Brinkmann, Markus, E-mail: markus.brinkmann@bio5.rwth-aachen.de [Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Rizzo, Larissa Y.; Lammers, Twan; Gremse, Felix [Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen (Germany); Schiwy, Sabrina [Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Kiessling, Fabian [Department of Experimental Molecular Imaging, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen (Germany); Hollert, Henner, E-mail: henner.hollert@bio5.rwth-aachen.de [Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); College of Resources and Environmental Science, Chongqing University, 1 Tiansheng Road Beibei, Chongqing 400715 (China); College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, 1239 Siping Road, Shanghai (China); State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University (China)

2016-02-01

Fish are important sentinel organisms for the assessment of water quality and play a central role in ecotoxicological research. Of particular importance to the assessment of health and fitness of fish stocks in response to environmental conditions or pollution are morphometric (e.g. Fulton's condition index) and somatic indices (e.g. hepatosomatic, and gonadosomatic index). Standard measurements of somatic indices are invasive and require, by definition, the sacrifice of examined animals, thus prohibiting longitudinal studies and relocation of animals captured in the field. As a potential solution, in the present study, we propose the use of micro-computed tomography (μCT) as imaging modality to non-invasively tomographically image rainbow trout (Oncorhynchus mykiss) exposed to different sediment suspensions. We here demonstrate that μCT can be used as a tool to reliably measure the volumes of different organs, which could then be applied as a substitute of their weights in calculation of somatic indices. To the best of our knowledge, this study is the first to report the results of μCT analyses in the context of ecotoxicological research in rainbow trout. It has the potential to greatly increase the information value of experiments conducted with fish and also to potentially reduce the number of animals required for studying temporal effects through facilitating longitudinal studies within the same individuals. - Highlights: • μCT was used for volumetric imaging sediment-exposed and unexposed rainbow trout • Liver volumes determined by μCT were highly correlated with liver weights. • The perfusion of organs in fish could also be studied by means of μCT. • It was shown that μCT is a useful tool in context of ecotoxicological research.

Why does the Aitken extrapolation often help to attain convergence in self-consistent field calculations?

International Nuclear Information System (INIS)

Cioslowski, J.

1988-01-01

The Aitken (three-point) extrapolation is one of the most popular convergence accelerators in the SCF calculations. The conditions that guarantee the Aitken extrapolation to bring about an unconditional convergence in the SCF process are examined. Classification of the SCF divergences is presented and it is shown that the extrapolation can be expected to work properly only in the case of oscillatory divergence

Ultrasonic computerized tomography (CT) for temperature measurements with limited projection data based on extrapolated filtered back projection (FBP) method

International Nuclear Information System (INIS)

Zhu Ning; Jiang Yong; Kato, Seizo

2005-01-01

This study uses ultrasound in combination with tomography to obtain three-dimensional temperature measurements using projection data obtained from limited projection angle. The main feature of the new computerized tomography (CT) reconstruction algorithm is to employ extrapolation scheme to make up for the incomplete projection data, it is based on the conventional filtered back projection (FBP) method while on top of that taking into account the correlation between the projection data and Fourier transform-based extrapolation. Computer simulation is conducted to verify the above algorithm. An experimental 3D temperature distribution measurement is also carried out to validate the proposed algorithm. The simulation and experimental results demonstrate that the extrapolated FBP CT algorithm is highly effective in dealing with projection data from limited projection angle

Hazard characterisation of chemicals in food and diet : dose response, mechanisms and extrapolation issues

NARCIS (Netherlands)

Dybing, E.; Doe, J.; Groten, J.; Kleiner, J.; O'Brien, J.; Renwick, A.G.; Schlatter, J.; Steinberg, P.; Tritscher, A.; Walker, R.; Younes, M.

2002-01-01

Hazard characterisation of low molecular weight chemicals in food and diet generally use a no-observed-adverse-effect level (NOAEL) or a benchmark dose as the starting point. For hazards that are considered not to have thresholds for their mode of action, low-dose extrapolation and other modelling

Extrapolation of π-meson form factor, zeros in the analyticity domain

International Nuclear Information System (INIS)

Morozov, P.T.

1978-01-01

The problem of a stable extrapolation from the cut to an arbitrary interior of the analyticity domain for the pion form factor is formulated and solved. As it is shown a stable solution can be derived if module representations with the Karleman weight function are used as the analyticity conditions. The case when the form factor has zeros is discussed. If there are zeros in the complex plane they must be taken into account when determining the extrapolation function

Extrapolation method in the Monte Carlo Shell Model and its applications

International Nuclear Information System (INIS)

Shimizu, Noritaka; Abe, Takashi; Utsuno, Yutaka; Mizusaki, Takahiro; Otsuka, Takaharu; Honma, Michio

2011-01-01

We demonstrate how the energy-variance extrapolation method works using the sequence of the approximated wave functions obtained by the Monte Carlo Shell Model (MCSM), taking 56 Ni with pf-shell as an example. The extrapolation method is shown to work well even in the case that the MCSM shows slow convergence, such as 72 Ge with f5pg9-shell. The structure of 72 Se is also studied including the discussion of the shape-coexistence phenomenon.

Ecotoxicological water assessment of an estuarine river from the Brazilian Northeast, potentially affected by industrial wastewater discharge.

Science.gov (United States)

de Melo Gurgel, Piatã; Navoni, Julio Alejandro; de Morais Ferreira, Douglisnilson; do Amaral, Viviane Souza

2016-12-01

Water pollution generated by industrial effluents discharge is a threat to the maintenance of aquatic ecosystems and human development. The Jundiai River estuarine, located in Northeast Brazil, receives an industrial pretreated effluent load from the city of Macaíba/RN/Brazil. The present study aimed to assess the water quality of this water reservoir through i) physicochemical characterization, ii) quantification of metal concentration and iii) by an ecotoxicological assessment carried out using Mysidopsis juniae and Pomacea lineata. The study was performed throughout the period comprising May to September 2014. Physicochemical variables such as chloride, total solids and electrical conductivity presented values in the waste discharge point, significantly different with those located out of the waste releasing point. Apart from that, metal concentration showed variable behavior throughout the monitored period. Levels of Al, Fe, Cu, Cd, Cr, Ni, Pb and Ag were over the considered guidelines. Both natural and anthropogenic sources seem to be involved in the resulting environmental scenario. A reduction in the fecundity rate (using Mysidopsis juniae) along with an increase in mortality rate (in both species) was observed ratifying the presence of toxic substances in this water reservoir. Moreover, a correlation analysis stated an association of the aforementioned toxicological effects with the delivery of industrial waste products. The ecotoxicological assessment performed highlighted the presence of toxic substance/s in water from the Jundiai River. Especially as a consequence of industrial activity, a fact that might threaten the bioma and, therefore, the human health of the population settled in the studied region. Copyright © 2016 Elsevier B.V. All rights reserved.

Oral-to-inhalation route extrapolation in occupational health risk assessment: A critical assessment

NARCIS (Netherlands)

Rennen, M.A.J.; Bouwman, T.; Wilschut, A.; Bessems, J.G.M.; Heer, C.de

2004-01-01

Due to a lack of route-specific toxicity data, the health risks resulting from occupational exposure are frequently assessed by route-to-route (RtR) extrapolation based on oral toxicity data. Insight into the conditions for and the uncertainties connected with the application of RtR extrapolation

Automated detection of structural alerts (chemical fragments in (ecotoxicology

Directory of Open Access Journals (Sweden)

Ronan Bureau

2013-02-01

Full Text Available This mini-review describes the evolution of different algorithms dedicated to the automated discovery of chemical fragments associated to (ecotoxicological endpoints. These structural alerts correspond to one of the most interesting approach of in silico toxicology due to their direct link with specific toxicological mechanisms. A number of expert systems are already available but, since the first work in this field which considered a binomial distribution of chemical fragments between two datasets, new data miners were developed and applied with success in chemoinformatics. The frequency of a chemical fragment in a dataset is often at the core of the process for the definition of its toxicological relevance. However, recent progresses in data mining provide new insights into the automated discovery of new rules. Particularly, this review highlights the notion of Emerging Patterns that can capture contrasts between classes of data.

AUTOMATED DETECTION OF STRUCTURAL ALERTS (CHEMICAL FRAGMENTS IN (ECOTOXICOLOGY

Directory of Open Access Journals (Sweden)

Alban Lepailleur

2013-02-01

Full Text Available This mini-review describes the evolution of different algorithms dedicated to the automated discovery of chemical fragments associated to (ecotoxicological endpoints. These structural alerts correspond to one of the most interesting approach of in silico toxicology due to their direct link with specific toxicological mechanisms. A number of expert systems are already available but, since the first work in this field which considered a binomial distribution of chemical fragments between two datasets, new data miners were developed and applied with success in chemoinformatics. The frequency of a chemical fragment in a dataset is often at the core of the process for the definition of its toxicological relevance. However, recent progresses in data mining provide new insights into the automated discovery of new rules. Particularly, this review highlights the notion of Emerging Patterns that can capture contrasts between classes of data.

A generalized sound extrapolation method for turbulent flows

Science.gov (United States)

Zhong, Siyang; Zhang, Xin

2018-02-01

Sound extrapolation methods are often used to compute acoustic far-field directivities using near-field flow data in aeroacoustics applications. The results may be erroneous if the volume integrals are neglected (to save computational cost), while non-acoustic fluctuations are collected on the integration surfaces. In this work, we develop a new sound extrapolation method based on an acoustic analogy using Taylor's hypothesis (Taylor 1938 Proc. R. Soc. Lon. A 164, 476-490. (doi:10.1098/rspa.1938.0032)). Typically, a convection operator is used to filter out the acoustically inefficient components in the turbulent flows, and an acoustics dominant indirect variable Dcp‧ is solved. The sound pressure p' at the far field is computed from Dcp‧ based on the asymptotic properties of the Green's function. Validations results for benchmark problems with well-defined sources match well with the exact solutions. For aeroacoustics applications: the sound predictions by the aerofoil-gust interaction are close to those by an earlier method specially developed to remove the effect of vortical fluctuations (Zhong & Zhang 2017 J. Fluid Mech. 820, 424-450. (doi:10.1017/jfm.2017.219)); for the case of vortex shedding noise from a cylinder, the off-body predictions by the proposed method match well with the on-body Ffowcs-Williams and Hawkings result; different integration surfaces yield close predictions (of both spectra and far-field directivities) for a co-flowing jet case using an established direct numerical simulation database. The results suggest that the method may be a potential candidate for sound projection in aeroacoustics applications.

Outlier robustness for wind turbine extrapolated extreme loads

DEFF Research Database (Denmark)

Natarajan, Anand; Verelst, David Robert

2012-01-01

. Stochastic identification of numerical artifacts in simulated loads is demonstrated using the method of principal component analysis. The extrapolation methodology is made robust to outliers through a weighted loads approach, whereby the eigenvalues of the correlation matrix obtained using the loads with its...

Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells

Energy Technology Data Exchange (ETDEWEB)

Brun, Nadja Rebecca [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland); Wehrli, Bernhard [Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland); Fent, Karl, E-mail: karl.fent@fhnw.ch [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland)

2016-02-01

Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L{sup −1} molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L{sup −1}. From OPV, copper (14 μg L{sup −1}), zinc (87 μg L{sup −1}) and silver (78 μg L{sup −1}) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. - Highlights: • Photovoltaics may be disposed in the environment after usage. • Copper indium gallium selenide (CIGS) and organic (OPV) cells were compared. • Morphological and molecular effects were assessed in zebrafish embryos. • Environmental condition affected metal leaching and ecotoxicological activity. • Damaged CIGS cells pose higher risk to the environment than OPV cells.

Nuclear lattice simulations using symmetry-sign extrapolation

Energy Technology Data Exchange (ETDEWEB)

Laehde, Timo A.; Luu, Thomas [Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Juelich (Germany); Lee, Dean [North Carolina State University, Department of Physics, Raleigh, NC (United States); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany); Epelbaum, Evgeny; Krebs, Hermann [Ruhr-Universitaet Bochum, Institut fuer Theoretische Physik II, Bochum (Germany); Rupak, Gautam [Mississippi State University, Department of Physics and Astronomy, Mississippi State, MS (United States)

2015-07-15

Projection Monte Carlo calculations of lattice Chiral Effective Field Theory suffer from sign oscillations to a varying degree dependent on the number of protons and neutrons. Hence, such studies have hitherto been concentrated on nuclei with equal numbers of protons and neutrons, and especially on the alpha nuclei where the sign oscillations are smallest. Here, we introduce the ''symmetry-sign extrapolation'' method, which allows us to use the approximate Wigner SU(4) symmetry of the nuclear interaction to systematically extend the Projection Monte Carlo calculations to nuclear systems where the sign problem is severe. We benchmark this method by calculating the ground-state energies of the {sup 12}C, {sup 6}He and {sup 6}Be nuclei, and discuss its potential for studies of neutron-rich halo nuclei and asymmetric nuclear matter. (orig.)

Dose rates from a C-14 source using extrapolation chamber and MC calculations

International Nuclear Information System (INIS)

Borg, J.

1996-05-01

The extrapolation chamber technique and the Monte Carlo (MC) calculation technique based on the EGS4 system have been studied for application for determination of dose rates in a low-energy β radiation field e.g., that from a 14 C source. The extrapolation chamber measurement method is the basic method for determination of dose rates in β radiation fields. Applying a number of correction factors and the stopping power ratio, tissue to air, the measured dose rate in an air volume surrounded by tissue equivalent material is converted into dose to tissue. Various details of the extrapolation chamber measurement method and evaluation procedure have been studied and further developed, and a complete procedure for the experimental determination of dose rates from a 14 C source is presented. A number of correction factors and other parameters used in the evaluation procedure for the measured data have been obtained by MC calculations. The whole extrapolation chamber measurement procedure was simulated using the MC method. The measured dose rates showed an increasing deviation from the MC calculated dose rates as the absorber thickness increased. This indicates that the EGS4 code may have some limitations for transport of very low-energy electrons. i.e., electrons with estimated energies less than 10 - 20 keV. MC calculations of dose to tissue were performed using two models: a cylindrical tissue phantom and a computer model of the extrapolation chamber. The dose to tissue in the extrapolation chamber model showed an additional buildup dose compared to the dose in the tissue model. (au) 10 tabs., 11 ills., 18 refs

A thermal extrapolation method for the effective temperatures and internal energies of activated ions

Science.gov (United States)

Meot-Ner (Mautner), Michael; Somogyi, Árpád

2007-11-01

The internal energies of dissociating ions, activated chemically or collisionally, can be estimated using the kinetics of thermal dissociation. The thermal Arrhenius parameters can be combined with the observed dissociation rate of the activated ions using kdiss = Athermalexp(-Ea,thermal/RTeff). This Arrhenius-type relation yields the effective temperature, Teff, at which the ions would dissociate thermally at the same rate, or yield the same product distributions, as the activated ions. In turn, Teff is used to calculate the internal energy of the ions and the energy deposited by the activation process. The method yields an energy deposition efficiency of 10% for a chemical ionization proton transfer reaction and 8-26% for the surface collisions of various peptide ions. Internal energies of ions activated by chemical ionization or by gas phase collisions, and of ions produced by desorption methods such as fast atom bombardment, can be also evaluated. Thermal extrapolation is especially useful for ion-molecule reaction products and for biological ions, where other methods to evaluate internal energies are laborious or unavailable.

Methodology for classification of the H14 criterion according to the directive 2008/98/EC on waste. Proposal of a biotest battery for the classification of hazardous waste. Ecotoxicological testing with bacterium, algae, crustacean and fish embryo; Metodik foer klassificering av H14-kriteriet i Avfallsfoerordningen. Foerslag till biotestbatteri foer klassificering av farligt avfall. Ekotoxikologisk testning med bakterie, alg, kraeftdjur och fiskembryo

Energy Technology Data Exchange (ETDEWEB)

Stiernstroem, Sara; Hemstroem, Kristian; Wik, Ola; Carlsson, Gunnar; Breitholtz, Magnus

2009-02-15

Waste, including ashes that can cause ecotoxicological effects, should be classified under criterion H-14 in the Directive on Waste 2008/98/EC. The complex nature of ash production and the fact that it has a complex chemical composition makes ecotoxicological hazard and risk assessment of ashes based on mere chemical analysis insufficient. Biological test systems are thus indispensable tools to support the ecotoxicological characterisation and classification of the properties of ashes. The objectives of this study were (1) to develop a leaching procedure suitable for preparation of water extracts for ecotoxicity testing, and (2) to evaluate an ecotoxicological test battery for the characterisation of ashes. A leaching procedure developed for organic compounds was assumed to be more realistic than existing standard methods for preparation of eluates for ecotoxic tests from complex matrices. A modified version of a recirculation column test, the ER-H method, developed for leaching of nonvolatile organic compounds and validated for PAHs and CPs, was used in this study and compared with the batch test EN 14735 (Characterization of waste - Preparation of waste samples for ecotoxicity tests). The ecotoxicological test battery included species representing different trophic levels; the bacterium Vibrio fisheri, a growth inhibition test with the micro algae Pseudokirchneriella subcapitata formerly known as Selenastrum capricornutum, a larval development test with the copepod Nitocra spinipes and an embryo toxicity test with sebra fish (Danio rerio). These test species show a relatively low sensitivity to elevated salinity levels. This test battery can be used to test a wide variety of matrices (e.g. single chemicals, complex effluents, eluates and sediments), and therefore offers flexible solutions for testing of leachates with differing and difficult properties. Both the ashes and their leachates were also analyzed chemically for organic and inorganic substances. All the

Corrosion allowances for sodium heated steam generators: evaluation of effects and extrapolation to component life time

Energy Technology Data Exchange (ETDEWEB)

Grosser, E E; Menken, G

1975-07-01

Steam generator tubes are subjected to two categories of corrosion; metal/sodium reactions and metal/water-steam interactions. Referring to these environmental conditions the relevant parameters are discussed. The influences of these parameters on the sodium corrosion and water/steam-reactions are evaluated. Extrapolations of corrosion values to steam generator design conditions are performed and discussed in detail. (author)

Corrosion allowances for sodium heated steam generators: evaluation of effects and extrapolation to component life time

International Nuclear Information System (INIS)

Grosser, E.E.; Menken, G.

1975-01-01

Steam generator tubes are subjected to two categories of corrosion; metal/sodium reactions and metal/water-steam interactions. Referring to these environmental conditions the relevant parameters are discussed. The influences of these parameters on the sodium corrosion and water/steam-reactions are evaluated. Extrapolations of corrosion values to steam generator design conditions are performed and discussed in detail. (author)

From the sea to the laboratory: Characterization of microplastic as prerequisite for the assessment of ecotoxicological impact.

Science.gov (United States)

Potthoff, Annegret; Oelschlägel, Kathrin; Schmitt-Jansen, Mechthild; Rummel, Christoph Daniel; Kühnel, Dana

2017-05-01

The presence of microplastic (MP) in the aquatic environment is recognized as a global-scale pollution issue. Secondary MP particles result from an ongoing fragmentation process governed by various biotic and abiotic factors. For a reliable risk assessment of these MP particles, knowledge about interactions with biota is needed. However, extensive testing with standard organisms under reproducible laboratory conditions with well-characterized MP suspensions is not available yet. As MP in the environment represents a mixture of particles differing in properties (e.g., size, color, polymer type, surface characteristics), it is likely that only specific particle fractions pose a threat towards organisms. In order to assign hazardous effects to specific particle properties, these characteristics need to be analyzed. As shown by the testing of particles (e.g. nanoparticles), characteristics other than chemical properties are important for the emergence of toxicity in organisms, and parameters such as surface area or size distribution need consideration. Therefore, the use of "well-defined" particles for ecotoxicological testing (i.e., standard particles) facilitates the establishment of causal links between physical-chemical properties of MP particles and toxic effects in organisms. However, the benefits of well-defined particles under laboratory conditions are offset by the disadvantage of the unknown comparability with MP in the environment. Therefore, weathering effects caused by biological, chemical, physical or mechanical processes have to be considered. To date, the characterization of the progression of MP weathering based on powder and suspension characterization methods is in its infancy. The aim of this commentary is to illustrate the prerequisites for testing MP in the laboratory from 3 perspectives: (i) knowledge of particle properties; (ii) behavior of MP in test setups involving ecotoxicological test organisms; and (iii) accordingly, test conditions that

Methodology Of PACS Effectiveness Evaluation As Part Of A Technology Assessment. The Dutch PACS Project Extrapolated.

Science.gov (United States)

Andriessen, J. H. T. H.; van der Horst-Bruinsma, I. E.; ter Haar Romeny, B. M.

1989-05-01

The present phase of the clinical evaluation within the Dutch PACS project mainly focuses on the development and evaluation of a PACSystem for a few departments in the Utrecht University hospital (UUH). A report on the first clinical experiences and a detailed cost/savings analysis of the PACSystem in the UUH are presented elsewhere. However, an assessment of the wider fmancial and organizational implications for hospitals and for the health sector is also needed. To this end a model for (financial) cost assessment of PACSystems is being developed by BAZIS. Learning from the actual pilot implementation in UUH we realized that general Technology Assessment (TA) also calls for an extra-polation of the medical and organizational effects. After a short excursion into the various approaches towards TA, this paper discusses the (inter) organizational dimensions relevant to the development of the necessary exttapolationmodels.

Metal-contaminated soil remediation by means of paper mill sludges addition: chemical and ecotoxicological evaluation

International Nuclear Information System (INIS)

Calace, N.; Campisi, T.; Iacondini, A.; Leoni, M.; Petronio, B.M.; Pietroletti, M.

2005-01-01

Metal pollution of soils is a great environmental problem. The major risks due to metal pollution of soil consist of leaching to groundwater and potential toxicity to plants and/or animals. The objective of this study is to evaluate by means of chemical and ecotoxicological approach the effects of paper mill sludge addition on the mobile metal fraction of polluted metal soils. The study was carried out on acidic soil derived from mining activities and thus polluted with heavy metals, and on two paper mill sludges having different chemical features. The results obtained by leaching experiments showed that the addition of a paper mill sludge, consisting mainly of carbonates, silicates and organic matter, to a heavy-metal polluted soil produces a decrease of available metal forms. The carbonate content seems to play a key role in the chemical stabilisation of metals and consequently in a decrease of toxicity of soil. The leached solutions have a non-toxic effect. The mild remediation by addition of sludge has moreover a lasting effect. - Paper mill sludge decreased available metals

Efficient anisotropic quasi-P wavefield extrapolation using an isotropic low-rank approximation

KAUST Repository

Zhang, Zhendong

2017-12-17

The computational cost of quasi-P wave extrapolation depends on the complexity of the medium, and specifically the anisotropy. Our effective-model method splits the anisotropic dispersion relation into an isotropic background and a correction factor to handle this dependency. The correction term depends on the slope (measured using the gradient) of current wavefields and the anisotropy. As a result, the computational cost is independent of the nature of anisotropy, which makes the extrapolation efficient. A dynamic implementation of this approach decomposes the original pseudo-differential operator into a Laplacian, handled using the low-rank approximation of the spectral operator, plus an angular dependent correction factor applied in the space domain to correct for anisotropy. We analyze the role played by the correction factor and propose a new spherical decomposition of the dispersion relation. The proposed method provides accurate wavefields in phase and more balanced amplitudes than a previous spherical decomposition. Also, it is free of SV-wave artifacts. Applications to a simple homogeneous transverse isotropic medium with a vertical symmetry axis (VTI) and a modified Hess VTI model demonstrate the effectiveness of the approach. The Reverse Time Migration (RTM) applied to a modified BP VTI model reveals that the anisotropic migration using the proposed modeling engine performs better than an isotropic migration.

Estimating the CCSD basis-set limit energy from small basis sets: basis-set extrapolations vs additivity schemes

Energy Technology Data Exchange (ETDEWEB)

Spackman, Peter R.; Karton, Amir, E-mail: amir.karton@uwa.edu.au [School of Chemistry and Biochemistry, The University of Western Australia, Perth, WA 6009 (Australia)

2015-05-15

Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/L{sup α} two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For example, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol{sup –1}. The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol{sup –1}.

Estimating the CCSD basis-set limit energy from small basis sets: basis-set extrapolations vs additivity schemes

International Nuclear Information System (INIS)

Spackman, Peter R.; Karton, Amir

2015-01-01

Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/L α two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For example, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol –1 . The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol –1

On Richardson extrapolation for low-dissipation low-dispersion diagonally implicit Runge-Kutta schemes

Science.gov (United States)

Havasi, Ágnes; Kazemi, Ehsan

2018-04-01

In the modeling of wave propagation phenomena it is necessary to use time integration methods which are not only sufficiently accurate, but also properly describe the amplitude and phase of the propagating waves. It is not clear if amending the developed schemes by extrapolation methods to obtain a high order of accuracy preserves the qualitative properties of these schemes in the perspective of dissipation, dispersion and stability analysis. It is illustrated that the combination of various optimized schemes with Richardson extrapolation is not optimal for minimal dissipation and dispersion errors. Optimized third-order and fourth-order methods are obtained, and it is shown that the proposed methods combined with Richardson extrapolation result in fourth and fifth orders of accuracy correspondingly, while preserving optimality and stability. The numerical applications include the linear wave equation, a stiff system of reaction-diffusion equations and the nonlinear Euler equations with oscillatory initial conditions. It is demonstrated that the extrapolated third-order scheme outperforms the recently developed fourth-order diagonally implicit Runge-Kutta scheme in terms of accuracy and stability.

Molecular ecotoxicology of nanosilver guided using in vitro prognosis

DEFF Research Database (Denmark)

Hayashi, Yuya; Heckmann, Lars-Henrik; Engelmann, Péter

2012-01-01

To study the molecular and cellular basis of silver nanoparticle (AgNP) toxicity, we here used a recently established in vitro model of earthworm coelomocytes in comparison to the conventional in vivo molecular ecotoxicology approach. Compared to the latter where the test organisms are exposed...... to NPs of interest held in an environmental matrix, in vitro models benefit from the ease of controlling exposure conditions in a defined set of biochemical milieus that NPs may encounter. The AgNPs tested in the present study originated from the same source, but to enhance the colloidal stability...... in the in vitro test media the NPs were pre-treated with serum proteins. In addition to physical characterisation of AgNPs, the active silver ion fraction was measured (in serum-supplemented cell culture medium and in soil pore-water). Using flow cytometry and atomic absorption spectrophotometry, we show...

SU-F-T-579: Extrapolation Techniques for Small Field Dosimetry Using Gafchromic EBT3 Film

Energy Technology Data Exchange (ETDEWEB)

Morales, J [Chris OBrien Lifehouse, Camperdown, NSW (Australia)

2016-06-15

Purpose: The purpose of this project is to test an experimental approach using an extrapolation technique for Gafchromic EBT3 film for small field x-ray dosimetry. Methods: Small fields from a Novalis Tx linear accelerator with HD Multileaf Collimators with 6 MV was used. The field sizes ranged from 5 × 5 to 50 × 50 mm2 MLC fields and a range of circular cones of 4 to 30 mm2 diameters. All measurements were performed in water at an SSD of 100 cm and at a depth of 10 cm. The relative output factors (ROFs) were determined from an extrapolation technique developed to eliminate the effects of partial volume averaging in film scan by scanning films with high resolution (1200 DPI). The size of the regions of interest (ROI) was varied to produce a plot of ROFs versus ROI which was then extrapolated to zero ROI to determine the relative output factor. The results were compared with other solid state detectors with proper correction, namely, IBA SFD diode, PTW 60008 and PTW 60012 diode. Results: For the 4 mm cone, the extrapolated ROF had a value of 0.658 ± 0.014 as compared to 0.642 and 0.636 for 0.5 mm and 1 mm2 ROI analysis, respectively. This showed a change in output factor of 2.4% and 3.3% at this comparative ROI sizes. In comparison, the 25 mm cone had a difference in measured output factor of 0.3% and 0.5% between 0.5 and 1.0 mm, respectively compared to zero volume. For the fields defined by MLCs a difference of up to 2% for 5×5 mm2 was observed. Conclusion: A measureable difference can be seen in ROF based on the ROI when radiochromic film is used. Using extrapolation technique from high resolution scanning a good agreement can be achieved.

Overview of ecotoxicological studies performed in the Venice Lagoon (Italy).

Science.gov (United States)

Losso, C; Ghirardini, A Volpi

2010-01-01

This work reports on the state of the art of the bioindicators used to assess environmental quality (regarding chemical pollutant impacts) in the Venice lagoon. After a brief description of the roles, advantages and limitations of bioindicators in marine and transitional environments and a summary of the Venice lagoon characteristics, the ecotoxicological methods used during scientific studies and research projects in the Lagoon are reported. Since not all data are available and no database can be formulated, the main evidence from toxicity bioassays, biomarkers and bioaccumulation analyses since the end of the 1970s is spatially synthesized using maps and discussed according to the four Venice lagoon basins. The majority of indicators showed that the Lido basin (north-central lagoon), affected by the presence of the industrial area and the city of Venice, is the one most highly impacted (particularly in the sites located within or in front of the industrial area, which showed very high sediment toxicity and high levels of DNA damage). The Malamocco basin (south-central lagoon) seems to be the least problematic. The southern basin (Chioggia basin) was shown to be impacted by urban contaminants from the town of Chioggia. The northern basin (Treporti basin) presented both impacted sites (high toxicity and high bioaccumulation factor) and relatively unpolluted sites (absence of toxicity, absence of imposex and low levels of bioaccumulation). This review can serve as a basis on which to select pragmatic, cost-effective biomonitoring techniques for environmental effects in lagoon ecosystems.

Scintillation counting: an extrapolation into the future

International Nuclear Information System (INIS)

Ross, H.H.

1983-01-01

Progress in scintillation counting is intimately related to advances in a variety of other disciplines such as photochemistry, photophysics, and instrumentation. And while there is steady progress in the understanding of luminescent phenomena, there is a virtual explosion in the application of semiconductor technology to detectors, counting systems, and data processing. The exponential growth of this technology has had, and will continue to have, a profound effect on the art of scintillation spectroscopy. This paper will review key events in technology that have had an impact on the development of scintillation science (solid and liquid) and will attempt to extrapolate future directions based on existing and projected capability in associated fields. Along the way there have been occasional pitfalls and several false starts; these too will be discussed as a reminder that if you want the future to be different than the past, study the past

Assessment of load extrapolation methods for wind turbines

DEFF Research Database (Denmark)

Toft, H.S.; Sørensen, John Dalsgaard; Veldkamp, D.

2010-01-01

an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima and the peak over...

Assessment of Load Extrapolation Methods for Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Veldkamp, Dick

2011-01-01

, an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper, three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima, and the peak over...

On extrapolation blowups in the $L_p$ scale

Czech Academy of Sciences Publication Activity Database

Capone, C.; Fiorenza, A.; Krbec, Miroslav

2006-01-01

Roč. 9, č. 4 (2006), s. 1-15 ISSN 1025-5834 R&D Projects: GA ČR(CZ) GA201/01/1201 Institutional research plan: CEZ:AV0Z10190503 Keywords : extrapolation * Lebesgue spaces * small Lebesgue spaces Subject RIV: BA - General Mathematics Impact factor: 0.349, year: 2004

Preliminary assays for lemongrass essential oil ecotoxicological test in D. similis and C. silvestrii submitted to gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Gimiliani, Giovana T.; Rogero, Sizue O.; Rogero, Jose R., E-mail: gtgimiliani@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Cruz, Aurea S. [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil). Culturas Celulares

2011-07-01

Pharmaceutical products are of great interest in ecotoxicological studies due to being found some of these products in the superficial waters and sediments, water and sewage treatment effluents. It was verified an increase of insect repellent chemical products in the aquatic environment because of the increase of diseases transmitted by mosquitoes like dengue. As these compounds show toxicity, the use of essential oils natural products with repellent properties is increasing and the literature about the impact in the aquatic environment is scarce. The hydric frame would suffer natural radiation and radiations from energy generation nuclear plants impacts fall out of tests and nuclear accidents. There is no universal definition of environmental protection and there are few studies on radiation effects in the aquatic environment. In this study was determined the lemon grass essential oil toxicity level as well as the lethal dose of ionizing radiation, LD{sub 50}, in aquatic organisms. Cytotoxicity test was performed by in vitro neutral red uptake method in NCTC clone L929 cell line. In the LD{sub 50} test aquatic organisms were submitted to gamma radiation. The essential oil of lemongrass Cymbopogon flexuosus showed cytotoxicity index IC{sub 50} about 50{mu}g.mL{sup -1}. The LD{sub 50} for Daphnia similis was 242 Gy and Ceriodaphnia silvestrii about 525 Gy. Studies will be continued with acute and chronic ecotoxicological tests of lemongrass essential oil in natural organisms and in organisms submitted to gamma radiation, utilizing the results obtained in this work. (author)

Ecotoxicology in Baden-Wuerttemberg. Research profile and possible joint research projects; Oekotoxikologie in Baden-Wuerttemberg. Forschungsprofil und moegliche Forschungsverbuende

Energy Technology Data Exchange (ETDEWEB)

Flaig, H.; Lohmann, U.; Ballschmiter, K.; Deissler, A.; Froescheis, O.; Kochte-Clemens, B.

2000-07-01

In 1996 the 'Landesforschungsbeirat Baden-Wuerttemberg' (Research Council of the Federal State) recommended a critical inventory of ecotoxicological research activities in Baden-Wuerttemberg in order to get a clearly defined orientation as well as a promotion of research. Assigned by the Ministry of Science, Research and Arts Baden-Wuerttemberg, the Center of Technology Assessment (Center of TA) designed and performed a project 'The Research Profile of Ecotoxicology in Baden-Wuerttemberg' with a focus on universities. Research activities in the federal state were registered, documented, and classified. In two round table discussions with experts from university and non-university research institutions, chemical industry, and ministries, the concept of the Center of TA for joint research projects in the field of ecotoxicology in Baden-Wuerttemberg was put in concrete terms. Joint research projects beyond university boundaries are presumably the most promising tool for ecotoxicology to grain profile as a discipline. Ideally, the strong points of several subjects should be combined; thus, creating synergy effects and enabling a comprehensive view of the research topic. We assume some organizational preconditions to be necessary for joint projects in order to be successful. Apart from a tight coordination, integrating measures are particularly important. Thus, a project should be obligatorily performed by at least one representative of environmental chemistry and one representative of research on biological effects. Financial means must be assigned, too, e.g. for the exchange of scientists and joint seminars, workshops or conferences. It should be checked thoroughly whether the 'Transregio'-program of the 'Deutsche Forschungsgemeinschaft' could serve as a model for implementing these integrating measures. Moreover, the results of the different working groups should be regularly combined and condensed to a comprehensive view of

Analysis reports on the ecotoxicological evaluation of discharges of spent water at the cogeneration/central heating plants Alloeverket, Borgaas, Haendeloeverket, Moelnlycke, Saevenaes and Aelmhult; Analysrapporter avseende ekotoxikologisk bedoemning av utslaepp av utgaaende vatten vid Alloeverket, Borgaas, Haendeloeverket, Moelnlycke, Saevenaes och Aelmhult

Energy Technology Data Exchange (ETDEWEB)

Andersson, Jonas; Axby, Fredrik; Persson, Maarten; Rossander, Annelie; Schultz, Emma; Svaerd, Sara [Carl Bro AB, Kristianstad (Sweden)

2007-04-15

The discharges to water at six biofuelled Swedish cogeneration/district heating plants are evaluated in light of the EU Water Framework Directive concerning ecotoxicological impacts. Ecotoxicological data for the 33 prioritized substances are also reviewed.

Acute toxicity tests and meta-analysis identify gaps in tropical ecotoxicology for amphibians.

Science.gov (United States)

Ghose, Sonia L; Donnelly, Maureen A; Kerby, Jacob; Whitfield, Steven M

2014-09-01

Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions. © 2014 SETAC.

Can Pearlite form Outside of the Hultgren Extrapolation of the Ae3 and Acm Phase Boundaries?

Science.gov (United States)

Aranda, M. M.; Rementeria, R.; Capdevila, C.; Hackenberg, R. E.

2016-02-01

It is usually assumed that ferrous pearlite can form only when the average austenite carbon concentration C 0 lies between the extrapolated Ae3 ( γ/ α) and Acm ( γ/ θ) phase boundaries (the "Hultgren extrapolation"). This "mutual supersaturation" criterion for cooperative lamellar nucleation and growth is critically examined from a historical perspective and in light of recent experiments on coarse-grained hypoeutectoid steels which show pearlite formation outside the Hultgren extrapolation. This criterion, at least as interpreted in terms of the average austenite composition, is shown to be unnecessarily restrictive. The carbon fluxes evaluated from Brandt's solution are sufficient to allow pearlite growth both inside and outside the Hultgren Extrapolation. As for the feasibility of the nucleation events leading to pearlite, the only criterion is that there are some local regions of austenite inside the Hultgren Extrapolation, even if the average austenite composition is outside.

Biosimilars in Inflammatory Bowel Disease: Facts and Fears of Extrapolation.

Science.gov (United States)

Ben-Horin, Shomron; Vande Casteele, Niels; Schreiber, Stefan; Lakatos, Peter Laszlo

2016-12-01

Biologic drugs such as infliximab and other anti-tumor necrosis factor monoclonal antibodies have transformed the treatment of immune-mediated inflammatory conditions such as Crohn's disease and ulcerative colitis (collectively known as inflammatory bowel disease [IBD]). However, the complex manufacturing processes involved in producing these drugs mean their use in clinical practice is expensive. Recent or impending expiration of patents for several biologics has led to development of biosimilar versions of these drugs, with the aim of providing substantial cost savings and increased accessibility to treatment. Biosimilars undergo an expedited regulatory process. This involves proving structural, functional, and biological biosimilarity to the reference product (RP). It is also expected that clinical equivalency/comparability will be demonstrated in a clinical trial in one (or more) sensitive population. Once these requirements are fulfilled, extrapolation of biosimilar approval to other indications for which the RP is approved is permitted without the need for further clinical trials, as long as this is scientifically justifiable. However, such justification requires that the mechanism(s) of action of the RP in question should be similar across indications and also comparable between the RP and the biosimilar in the clinically tested population(s). Likewise, the pharmacokinetics, immunogenicity, and safety of the RP should be similar across indications and comparable between the RP and biosimilar in the clinically tested population(s). To date, most anti-tumor necrosis factor biosimilars have been tested in trials recruiting patients with rheumatoid arthritis. Concerns have been raised regarding extrapolation of clinical data obtained in rheumatologic populations to IBD indications. In this review, we discuss the issues surrounding indication extrapolation, with a focus on extrapolation to IBD. Copyright © 2016 AGA Institute. Published by Elsevier Inc. All

A regularization method for extrapolation of solar potential magnetic fields

Science.gov (United States)

Gary, G. A.; Musielak, Z. E.

1992-01-01

The mathematical basis of a Tikhonov regularization method for extrapolating the chromospheric-coronal magnetic field using photospheric vector magnetograms is discussed. The basic techniques show that the Cauchy initial value problem can be formulated for potential magnetic fields. The potential field analysis considers a set of linear, elliptic partial differential equations. It is found that, by introducing an appropriate smoothing of the initial data of the Cauchy potential problem, an approximate Fourier integral solution is found, and an upper bound to the error in the solution is derived. This specific regularization technique, which is a function of magnetograph measurement sensitivities, provides a method to extrapolate the potential magnetic field above an active region into the chromosphere and low corona.

Statistically extrapolated nowcasting of summertime precipitation over the Eastern Alps

Science.gov (United States)

Chen, Min; Bica, Benedikt; Tüchler, Lukas; Kann, Alexander; Wang, Yong

2017-07-01

This paper presents a new multiple linear regression (MLR) approach to updating the hourly, extrapolated precipitation forecasts generated by the INCA (Integrated Nowcasting through Comprehensive Analysis) system for the Eastern Alps. The generalized form of the model approximates the updated precipitation forecast as a linear response to combinations of predictors selected through a backward elimination algorithm from a pool of predictors. The predictors comprise the raw output of the extrapolated precipitation forecast, the latest radar observations, the convective analysis, and the precipitation analysis. For every MLR model, bias and distribution correction procedures are designed to further correct the systematic regression errors. Applications of the MLR models to a verification dataset containing two months of qualified samples, and to one-month gridded data, are performed and evaluated. Generally, MLR yields slight, but definite, improvements in the intensity accuracy of forecasts during the late evening to morning period, and significantly improves the forecasts for large thresholds. The structure-amplitude-location scores, used to evaluate the performance of the MLR approach, based on its simulation of morphological features, indicate that MLR typically reduces the overestimation of amplitudes and generates similar horizontal structures in precipitation patterns and slightly degraded location forecasts, when compared with the extrapolated nowcasting.

A new bioassay for the ecotoxicological testing of VOCs on groundwater invertebrates and the effects of toluene on Niphargus inopinatus

Energy Technology Data Exchange (ETDEWEB)

Avramov, Maria; Schmidt, Susanne I. [Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Groundwater Ecology, Ingolstädter Landstrasse 1, D-85764 Neuherberg (Germany); Griebler, Christian, E-mail: christian.griebler@helmholtz-muenchen.de [Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Groundwater Ecology, Ingolstädter Landstrasse 1, D-85764 Neuherberg (Germany)

2013-04-15

Highlights: ► A new bioassay for testing the toxicity of VOCs on groundwater fauna is presented. ► Results on the toxicity of toluene to Niphargus inopinatus are now available. ► Henry equilibrium needs to be considered when bioassays with VOCs are designed. ► Methodological aspects related to “difficult-to-test substances” are discussed. -- Abstract: A protocol was developed for testing the ecotoxicological effects of volatile organic compounds (VOCs) on groundwater invertebrates. Test substance volatility was addressed in a “closed from start to analysis”-design. Since manifestation of toxic effects may be delayed in ‘slower metabolizing’ organisms such as groundwater fauna, a time-independent (TI-) approach was adopted. Toluene was used as a model substance and its toxicity to the groundwater amphipod Niphargus inopinatus was assessed as an example. The method evaluation process considered various methodological issues such as partitioning of the toxicant between the water and the gas phase (Henry equilibrium), the possible depletion of oxygen in closed test vials, as well as microbial biodegradation of the test substance. For N. inopinatus, an LC{sub 50},{sub 14} {sub days} of 46.6 mg L{sup −1} toluene was obtained. The ultimate LC{sub 50} value was estimated at 23.3 mg L{sup −1} toluene. No oxygen depletion occurred in the test vials and Henry equilibrium was found to be established after 6 h. The new test system proposed now awaits broad practical application.

Source-receiver two-way wave extrapolation for prestack exploding-reflector modelling and migration

KAUST Repository

Alkhalifah, Tariq Ali

2014-10-08

Most modern seismic imaging methods separate input data into parts (shot gathers). We develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield forward or backward in time. This approach has the potential for generating accurate images free of artiefacts associated with conventional approaches. We derive novel high-order partial differential equations in the source-receiver time domain. The fourth-order nature of the extrapolation in time leads to four solutions, two of which correspond to the incoming and outgoing P-waves and reduce to the zero-offset exploding-reflector solutions when the source coincides with the receiver. A challenge for implementing two-way time extrapolation is an essential singularity for horizontally travelling waves. This singularity can be avoided by limiting the range of wavenumbers treated in a spectral-based extrapolation. Using spectral methods based on the low-rank approximation of the propagation symbol, we extrapolate only the desired solutions in an accurate and efficient manner with reduced dispersion artiefacts. Applications to synthetic data demonstrate the accuracy of the new prestack modelling and migration approach.

Molecular Target Homology as a Basis for Species Extrapolation to Assess the Ecological Risk of Veterinary Drugs

Science.gov (United States)

Increased identification of veterinary pharmaceutical contaminants in aquatic environments has raised concerns regarding potential adverse effects of these chemicals on non-target organisms. The purpose of this work was to develop a method for predictive species extrapolation ut...

Extrapolation of Nitrogen Fertiliser Recommendation Zones for Maize in Kisii District Using Geographical Information Systems

International Nuclear Information System (INIS)

Okoth, P.F.; Wamae, D.K.

1999-01-01

A GIS database was established for fertiliser recommendation domains in Kisii District by using FURP fertiliser trial results, KSS soils data and MDBP climatic data. These are manipulated in ESRI's (Personal Computer Environmental Systems Research Institute) ARCINFO and ARCVIEW softwares. The extrapolations were only done for the long rains season (March- August) with three to four years data. GIS technology was used to cluster fertiliser recommendation domains as a geographical area expressed in terms of variation over space and not limited to the site of experiment where a certain agronomic or economic fertiliser recommendation was made. The extrapolation over space was found to be more representative for any recommendation, the result being digital maps describing each area in the geographical space. From the results of the extrapolations, approximately 38,255 ha of the district require zero Nitrogen (N) fertilisation while 94,330 ha requires 75 kg ha -1 Nitrogen fertilisation during the (March-August) long rains. The extrapolation was made difficult since no direct relationships could be established to occur between the available-N, % Carbon (C) or any of the other soil properties with the obtained yields. Decision rules were however developed based on % C which was the soil variable with values closest to the obtained yields. 3% organic carbon was found to be the boundary between 0 application and 75 kg-N application. GIS techniques made it possible to model and extrapolates the results using the available data. The extrapolations still need to be verified with more ground data from fertiliser trials. Data gaps in the soil map left some soil mapping units with no recommendations. Elevation was observed to influence yields and it should be included in future extrapolation by clustering digital elevation models with rainfall data in a spatial model at the district scale

Emotional experience is subject to social and technological change: extrapolating to the future

OpenAIRE

Scherer, Klaus R.

2001-01-01

While the emotion mechanism is generally considered to be evolutionarily continuous, suggesting a certain degree of universality of emotional responding, there is evidence that emotional experience may differ across cultures and historical periods. This article extrapolates potential changes in future emotional experiences that can be expected to be caused by rapid social and technological change. Specifically, four issues are discussed: (1) the effect of social change on emotions that are st...

extrap: Software to assist the selection of extrapolation methods for moving-boat ADCP streamflow measurements

Science.gov (United States)

Mueller, David S.

2013-04-01

Selection of the appropriate extrapolation methods for computing the discharge in the unmeasured top and bottom parts of a moving-boat acoustic Doppler current profiler (ADCP) streamflow measurement is critical to the total discharge computation. The software tool, extrap, combines normalized velocity profiles from the entire cross section and multiple transects to determine a mean profile for the measurement. The use of an exponent derived from normalized data from the entire cross section is shown to be valid for application of the power velocity distribution law in the computation of the unmeasured discharge in a cross section. Selected statistics are combined with empirically derived criteria to automatically select the appropriate extrapolation methods. A graphical user interface (GUI) provides the user tools to visually evaluate the automatically selected extrapolation methods and manually change them, as necessary. The sensitivity of the total discharge to available extrapolation methods is presented in the GUI. Use of extrap by field hydrographers has demonstrated that extrap is a more accurate and efficient method of determining the appropriate extrapolation methods compared with tools currently (2012) provided in the ADCP manufacturers' software.

Ecotoxicological evaluation of leachate from the Limeira sanitary landfill with a view to identifying acute toxicity

OpenAIRE

José Euclides Stipp Paterniani; Ronaldo Teixeira Pelegrini; Núbia Natália de Brito Pelegrini

2007-01-01

Final disposal of solid waste is still a cause for serious impacts on the environment. In sanitary landfills, waste undergoes physical, chemical, and biological decomposition, generating biogas and leachate. Leachate is a highly toxic liquid with a very high pollution potential. The purpose of this work is to evaluate toxicity of in natura leachate samples collected from Limeira Sanitary Landfill, in Limeira, SP. The ecotoxicological evaluation comprised acute toxicity assays using as test or...

Unified Scaling Law for flux pinning in practical superconductors: III. Minimum datasets, core parameters, and application of the Extrapolative Scaling Expression

Science.gov (United States)

Ekin, Jack W.; Cheggour, Najib; Goodrich, Loren; Splett, Jolene

2017-03-01

In Part 2 of these articles, an extensive analysis of pinning-force curves and raw scaling data was used to derive the Extrapolative Scaling Expression (ESE). This is a parameterization of the Unified Scaling Law (USL) that has the extrapolation capability of fundamental unified scaling, coupled with the application ease of a simple fitting equation. Here in Part 3, the accuracy of the ESE relation to interpolate and extrapolate limited critical-current data to obtain complete I c(B,T,ɛ) datasets is evaluated and compared with present fitting equations. Accuracy is analyzed in terms of root mean square (RMS) error and fractional deviation statistics. Highlights from 92 test cases are condensed and summarized, covering most fitting protocols and proposed parameterizations of the USL. The results show that ESE reliably extrapolates critical currents at fields B, temperatures T, and strains ɛ that are remarkably different from the fitted minimum dataset. Depending on whether the conductor is moderate-J c or high-J c, effective RMS extrapolation errors for ESE are in the range 2-5 A at 12 T, which approaches the I c measurement error (1-2%). The minimum dataset for extrapolating full I c(B,T,ɛ) characteristics is also determined from raw scaling data. It consists of one set of I c(B,ɛ) data at a fixed temperature (e.g., liquid helium temperature), and one set of I c(B,T) data at a fixed strain (e.g., zero applied strain). Error analysis of extrapolations from the minimum dataset with different fitting equations shows that ESE reduces the percentage extrapolation errors at individual data points at high fields, temperatures, and compressive strains down to 1/10th to 1/40th the size of those for extrapolations with present fitting equations. Depending on the conductor, percentage fitting errors for interpolations are also reduced to as little as 1/15th the size. The extrapolation accuracy of the ESE relation offers the prospect of straightforward implementation of

Technique of Critical Current Density Measurement of Bulk Superconductor with Linear Extrapolation Method

International Nuclear Information System (INIS)

Adi, Wisnu Ari; Sukirman, Engkir; Winatapura, Didin S.

2000-01-01

Technique of critical current density measurement (Jc) of HTc bulk ceramic superconductor has been performed by using linear extrapolation with four-point probes method. The measurement of critical current density HTc bulk ceramic superconductor usually causes damage in contact resistance. In order to decrease this damage factor, we introduce extrapolation method. The extrapolating data show that the critical current density Jc for YBCO (123) and BSCCO (2212) at 77 K are 10,85(6) Amp.cm - 2 and 14,46(6) Amp.cm - 2, respectively. This technique is easier, simpler, and the use of the current flow is low, so it will not damage the contact resistance of the sample. We expect that the method can give a better solution for bulk superconductor application. Key words. : superconductor, critical temperature, and critical current density

Are whale sharks exposed to persistent organic pollutants and plastic pollution in the Gulf of California (Mexico)? First ecotoxicological investigation using skin biopsies.

Science.gov (United States)

Fossi, Maria Cristina; Baini, Matteo; Panti, Cristina; Galli, Matteo; Jiménez, Begoña; Muñoz-Arnanz, Juan; Marsili, Letizia; Finoia, Maria Grazia; Ramírez-Macías, Dení

2017-09-01

The whale shark (Rhincodon typus) is an endangered species that may be exposed to micro- and macro-plastic ingestion as a result of their filter-feeding activity, particularly on the sea surface. In this pilot project we perform the first ecotoxicological investigation on whale sharks sampled in the Gulf of California exploring the potential interaction of this species with plastic debris (macro-, micro-plastics and related sorbed contaminants). Due to the difficulty in obtaining stranded specimens of this endangered species, an indirect approach, by skin biopsies was used for the evaluation of the whale shark ecotoxicological status. The levels of organochlorine compounds (PCBs, DDTs), polybrominated diphenyl ethers (PBDEs) plastic additives, and related biomarkers responses (CYP1A) were investigated for the first time in the whale shark. Twelve whale shark skin biopsy samples were collected in January 2014 in La Paz Bay (BCS, Mexico) and a preliminary investigation on microplastic concentration and polymer composition was also carried out in seawater samples from the same area. The average abundance pattern for the target contaminants was PCBs>DDTs>PBDEs>HCB. Mean concentration values of 8.42ng/g w.w. were found for PCBs, 1.31ng/g w.w. for DDTs, 0.29ng/g w.w. for PBDEs and 0.19ng/g w.w. for HCB. CYP1A-like protein was detected, for the first time, in whale shark skin samples. First data on the average density of microplastics in the superficial zooplankton/microplastic samples showed values ranging from 0.00items/m 3 to 0.14items/m 3 . A focused PCA analysis was performed to evaluate a possible correlation among the size of the whale sharks, contaminants and CYP1A reponses. Further ecotoxicological investigation on whale shark skin biopsies will be carried out for a worldwide ecotoxicological risk assessment of this endangerd species. Copyright © 2017 Elsevier Inc. All rights reserved.

Forests and methane - at the intersection of science and politics, experimentation and extrapolation, objectivity and subjectivity

International Nuclear Information System (INIS)

Peyron, Jean-Luc

2005-01-01

According to recent information, vegetation is thought to be a major source of methane. This phenomenon had not been contemplated until now and still remains to be explained. According to the authors and on the basis of rough extrapolations, it may cast light on some missing pieces in the global methane balance. The initial reaction by commentators following this discovery was to discuss its consequences on the strategy to fight the greenhouse effect considering methane's considerable impact on global warming. However, a preliminary analysis based on opinions from a range of experts underscores three aspects - the experimental discovery needs to be confirmed and explained before drawing any hasty conclusions; extrapolations performed so far on a global scale are highly inadequate and probably overestimated; implications for fighting the greenhouse effect are limited because the phenomenon in question is a natural one and not extensive enough to offset the benefits of forests as a sink for carbon dioxide. (authors)

Statistical modeling and extrapolation of carcinogenesis data

International Nuclear Information System (INIS)

Krewski, D.; Murdoch, D.; Dewanji, A.

1986-01-01

Mathematical models of carcinogenesis are reviewed, including pharmacokinetic models for metabolic activation of carcinogenic substances. Maximum likelihood procedures for fitting these models to epidemiological data are discussed, including situations where the time to tumor occurrence is unobservable. The plausibility of different possible shapes of the dose response curve at low doses is examined, and a robust method for linear extrapolation to low doses is proposed and applied to epidemiological data on radiation carcinogenesis

Calibration of the 90Sr+90Y ophthalmic and dermatological applicators with an extrapolation ionization minichamber

International Nuclear Information System (INIS)

Antonio, Patrícia L.; Oliveira, Mércia L.; Caldas, Linda V.E.

2014-01-01

90 Sr+ 90 Y clinical applicators are used for brachytherapy in Brazilian clinics even though they are not manufactured anymore. Such sources must be calibrated periodically, and one of the calibration methods in use is ionometry with extrapolation ionization chambers. 90 Sr+ 90 Y clinical applicators were calibrated using an extrapolation minichamber developed at the Calibration Laboratory at IPEN. The obtained results agree satisfactorily with the data provided in calibration certificates of the sources. - Highlights: • 90 Sr+ 90 Y clinical applicators were calibrated using a mini-extrapolation chamber. • An extrapolation curve was obtained for each applicator during its calibration. • The results were compared with those provided by the calibration certificates. • All results of the dermatological applicators presented lower differences than 5%

Micro-computed tomography (μCT) as a novel method in ecotoxicology--determination of morphometric and somatic data in rainbow trout (Oncorhynchus mykiss).

Science.gov (United States)

Brinkmann, Markus; Rizzo, Larissa Y; Lammers, Twan; Gremse, Felix; Schiwy, Sabrina; Kiessling, Fabian; Hollert, Henner

2016-02-01

Fish are important sentinel organisms for the assessment of water quality and play a central role in ecotoxicological research. Of particular importance to the assessment of health and fitness of fish stocks in response to environmental conditions or pollution are morphometric (e.g. Fulton's condition index) and somatic indices (e.g. hepatosomatic, and gonadosomatic index). Standard measurements of somatic indices are invasive and require, by definition, the sacrifice of examined animals, thus prohibiting longitudinal studies and relocation of animals captured in the field. As a potential solution, in the present study, we propose the use of micro-computed tomography (μCT) as imaging modality to non-invasively tomographically image rainbow trout (Oncorhynchus mykiss) exposed to different sediment suspensions. We here demonstrate that μCT can be used as a tool to reliably measure the volumes of different organs, which could then be applied as a substitute of their weights in calculation of somatic indices. To the best of our knowledge, this study is the first to report the results of μCT analyses in the context of ecotoxicological research in rainbow trout. It has the potential to greatly increase the information value of experiments conducted with fish and also to potentially reduce the number of animals required for studying temporal effects through facilitating longitudinal studies within the same individuals. Copyright © 2015 Elsevier B.V. All rights reserved.

Smooth extrapolation of unknown anatomy via statistical shape models

Science.gov (United States)

Grupp, R. B.; Chiang, H.; Otake, Y.; Murphy, R. J.; Gordon, C. R.; Armand, M.; Taylor, R. H.

2015-03-01

Several methods to perform extrapolation of unknown anatomy were evaluated. The primary application is to enhance surgical procedures that may use partial medical images or medical images of incomplete anatomy. Le Fort-based, face-jaw-teeth transplant is one such procedure. From CT data of 36 skulls and 21 mandibles separate Statistical Shape Models of the anatomical surfaces were created. Using the Statistical Shape Models, incomplete surfaces were projected to obtain complete surface estimates. The surface estimates exhibit non-zero error in regions where the true surface is known; it is desirable to keep the true surface and seamlessly merge the estimated unknown surface. Existing extrapolation techniques produce non-smooth transitions from the true surface to the estimated surface, resulting in additional error and a less aesthetically pleasing result. The three extrapolation techniques evaluated were: copying and pasting of the surface estimate (non-smooth baseline), a feathering between the patient surface and surface estimate, and an estimate generated via a Thin Plate Spline trained from displacements between the surface estimate and corresponding vertices of the known patient surface. Feathering and Thin Plate Spline approaches both yielded smooth transitions. However, feathering corrupted known vertex values. Leave-one-out analyses were conducted, with 5% to 50% of known anatomy removed from the left-out patient and estimated via the proposed approaches. The Thin Plate Spline approach yielded smaller errors than the other two approaches, with an average vertex error improvement of 1.46 mm and 1.38 mm for the skull and mandible respectively, over the baseline approach.

Simultaneous determination of metal traces using SPE preconcentration on Amberlite XAD-7 by ICP-MS in environmental water and sample ecotoxicology assessment

Czech Academy of Sciences Publication Activity Database

Holubova, Z.; Sommer, L.; Moos, Martin; Kuta, J.

2012-01-01

Roč. 21, 10A (2012), s. 3127-3135 ISSN 1018-4619 Institutional support: RVO:67179843 Keywords : Solid Phase Extraction * Amberlite XAD-7 * ICP-MS and Waters * Ecotoxicology Subject RIV: EH - Ecology, Behaviour Impact factor: 0.641, year: 2012

Assessment of DDT, HCH and PAH contamination and associated ecotoxicological risks in surface sediments of coastal Tema Harbour (Ghana).

Science.gov (United States)

Botwe, Benjamin O; Kelderman, Peter; Nyarko, Elvis; Lens, Piet N L

2017-02-15

This study assessed DDTs, HCHs and PAHs contamination in sediments from the Tema Harbour (Ghana) and the associated ecotoxicological risks. The results showed widespread DDTs, HCHs and PAHs contamination in the harbour sediments with mean concentrations ranging from 6.0-12.8, 2.8-12.7 and 2750-5130μg·kg -1 d·w, respectively. The silt-clay and total organic carbon contents of the sediments poorly correlated with the pollutant concentrations. DDTs and HCHs contamination relate to past use of DDT and lindane, which under the anoxic harbour conditions resulted in disproportionately higher concentrations of p,p'-DDD and γ-HCH in the sediments. No conclusion could be drawn on the sources of PAHs as either petrogenic or pyrogenic. The pollutant concentrations in the harbour sediments, particularly γ-HCH, may pose high ecotoxicological risks. In comparison to a previous study, this study indicates there has been a considerable reduction in PAH contamination in the Tema Harbour since the last major oil spill in 2007. Copyright © 2016 Elsevier Ltd. All rights reserved.

Avoidance, biomass and survival response of soil dwelling (endogeic) earthworms to OECD artificial soil: potential implications for earthworm ecotoxicology.

Science.gov (United States)

Brami, C; Glover, A R; Butt, K R; Lowe, C N

2017-05-01

Soil dwelling earthworms are now adopted more widely in ecotoxicology, so it is vital to establish if standardised test parameters remain applicable. The main aim of this study was to determine the influence of OECD artificial soil on selected soil-dwelling, endogeic earthworm species. In an initial experiment, biomass change in mature Allolobophora chlorotica was recorded in Standard OECD Artificial Soil (AS) and also in Kettering Loam (KL). In a second experiment, avoidance behaviour was recorded in a linear gradient with varying proportions of AS and KL (100% AS, 75% AS + 25% KL, 50% KS + 50% KL, 25% AS + 75% KL, 100% KL) with either A. chlorotica or Octolasion cyaneum. Results showed a significant decrease in A. chlorotica biomass in AS relative to KL, and in the linear gradient, both earthworm species preferentially occupied sections containing higher proportions of KL over AS. Soil texture and specifically % composition and particle size of sand are proposed as key factors that influenced observed results. This research suggests that more suitable substrates are required for ecotoxicology tests with soil dwelling earthworms.

Hydrologic nonstationarity and extrapolating models to predict the future: overview of session and proceeding

Directory of Open Access Journals (Sweden)

F. H. S. Chiew

2015-06-01

Full Text Available This paper provides an overview of this IAHS symposium and PIAHS proceeding on "hydrologic nonstationarity and extrapolating models to predict the future". The paper provides a brief review of research on this topic, presents approaches used to account for nonstationarity when extrapolating models to predict the future, and summarises the papers in this session and proceeding.

A NEW CODE FOR NONLINEAR FORCE-FREE FIELD EXTRAPOLATION OF THE GLOBAL CORONA

International Nuclear Information System (INIS)

Jiang Chaowei; Feng Xueshang; Xiang Changqing

2012-01-01

Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolations from photospheric magnetograms using physical models, e.g., the nonlinear force-free field (NLFFF) model that is usually adopted. Most of the currently available NLFFF codes have been developed with computational volume such as a Cartesian box or a spherical wedge, while a global full-sphere extrapolation is still under development. A high-performance global extrapolation code is in particular urgently needed considering that the Solar Dynamics Observatory can provide a full-disk magnetogram with resolution up to 4096 × 4096. In this work, we present a new parallelized code for global NLFFF extrapolation with the photosphere magnetogram as input. The method is based on the magnetohydrodynamics relaxation approach, the CESE-MHD numerical scheme, and a Yin-Yang spherical grid that is used to overcome the polar problems of the standard spherical grid. The code is validated by two full-sphere force-free solutions from Low and Lou's semi-analytic force-free field model. The code shows high accuracy and fast convergence, and can be ready for future practical application if combined with an adaptive mesh refinement technique.

A Model Compound Study: The ecotoxicological evaluation of five organic contaminants with a battery of marine bioassays

OpenAIRE

Macken, A.; Giltrap, M.; Foley, B.; McGovern, E.; McHugh, B.; Davoren, M.

2008-01-01

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contam...

A special mini-extrapolation chamber for calibration of 90Sr+90Y sources

International Nuclear Information System (INIS)

Oliveira, Mercia L; Caldas, Linda V E

2005-01-01

90 Sr+ 90 Y applicators are commonly utilized in brachytherapy, including ophthalmic procedures. The recommended instruments for the calibration of these applicators are extrapolation chambers, which are ionization chambers that allow the variation of their sensitive volume. Using the extrapolation method, the absorbed dose rate at the applicator surface can be determined. The aim of the present work was to develop a mini-extrapolation chamber for the calibration of 90 Sr+ 90 Y beta ray applicators. The developed mini-chamber has a 3.0 cm outer diameter and is 11.3 cm in length. An aluminized polyester foil is used as the entrance window while the collecting electrode is made of graphited polymethylmethacrylate. This mini-chamber was tested in 90 Sr+ 90 Y radiation beams from a beta particle check source and with a plane ophthalmic applicator, showing adequate results

An Efficient Method of Reweighting and Reconstructing Monte Carlo Molecular Simulation Data for Extrapolation to Different Temperature and Density Conditions

KAUST Repository

Sun, Shuyu

2013-06-01

This paper introduces an efficient technique to generate new molecular simulation Markov chains for different temperature and density conditions, which allow for rapid extrapolation of canonical ensemble averages at a range of temperatures and densities different from the original conditions where a single simulation is conducted. Obtained information from the original simulation are reweighted and even reconstructed in order to extrapolate our knowledge to the new conditions. Our technique allows not only the extrapolation to a new temperature or density, but also the double extrapolation to both new temperature and density. The method was implemented for Lennard-Jones fluid with structureless particles in single-gas phase region. Extrapolation behaviors as functions of extrapolation ranges were studied. Limits of extrapolation ranges showed a remarkable capability especially along isochors where only reweighting is required. Various factors that could affect the limits of extrapolation ranges were investigated and compared. In particular, these limits were shown to be sensitive to the number of particles used and starting point where the simulation was originally conducted.

An Efficient Method of Reweighting and Reconstructing Monte Carlo Molecular Simulation Data for Extrapolation to Different Temperature and Density Conditions

KAUST Repository

Sun, Shuyu; Kadoura, Ahmad Salim; Salama, Amgad

2013-01-01

This paper introduces an efficient technique to generate new molecular simulation Markov chains for different temperature and density conditions, which allow for rapid extrapolation of canonical ensemble averages at a range of temperatures and densities different from the original conditions where a single simulation is conducted. Obtained information from the original simulation are reweighted and even reconstructed in order to extrapolate our knowledge to the new conditions. Our technique allows not only the extrapolation to a new temperature or density, but also the double extrapolation to both new temperature and density. The method was implemented for Lennard-Jones fluid with structureless particles in single-gas phase region. Extrapolation behaviors as functions of extrapolation ranges were studied. Limits of extrapolation ranges showed a remarkable capability especially along isochors where only reweighting is required. Various factors that could affect the limits of extrapolation ranges were investigated and compared. In particular, these limits were shown to be sensitive to the number of particles used and starting point where the simulation was originally conducted.

Determination of the most appropriate method for extrapolating overall survival data from a placebo-controlled clinical trial of lenvatinib for progressive, radioiodine-refractory differentiated thyroid cancer.

Science.gov (United States)

Tremblay, Gabriel; Livings, Christopher; Crowe, Lydia; Kapetanakis, Venediktos; Briggs, Andrew

2016-01-01

Cost-effectiveness models for the treatment of long-term conditions often require information on survival beyond the period of available data. This paper aims to identify a robust and reliable method for the extrapolation of overall survival (OS) in patients with radioiodine-refractory differentiated thyroid cancer receiving lenvatinib or placebo. Data from 392 patients (lenvatinib: 261, placebo: 131) from the SELECT trial are used over a 34-month period of follow-up. A previously published criterion-based approach is employed to ascertain credible estimates of OS beyond the trial data. Parametric models with and without a treatment covariate and piecewise models are used to extrapolate OS, and a holistic approach, where a series of statistical and visual tests are considered collectively, is taken in determining the most appropriate extrapolation model. A piecewise model, in which the Kaplan-Meier survivor function is used over the trial period and an extrapolated tail is based on the Exponential distribution, is identified as the optimal model. In the absence of long-term survival estimates from clinical trials, survival estimates often need to be extrapolated from the available data. The use of a systematic method based on a priori determined selection criteria provides a transparent approach and reduces the risk of bias. The extrapolated OS estimates will be used to investigate the potential long-term benefits of lenvatinib in the treatment of radioiodine-refractory differentiated thyroid cancer patients and populate future cost-effectiveness analyses.

Urban influence on the water quality of the Uberaba River basin: an ecotoxicological assessment

Directory of Open Access Journals (Sweden)

Ana Luisa Curado

2018-03-01

Full Text Available Ecotoxicological tests applied to Tradescantia pallida, Allium cepa and Lactuca sativa were used to assess the quality of the Uberaba River basin under urban area influence. Water samples were collected at eight different points during the dry season. The samples were assessed using the following toxicity indicators: micronuclei percentage in T. pallida pollen grains (TRAD-MN, seed germination, root growth, mitotic index (MI and micronuclei in A. cepa root-cells, and seed germination and root growth in L. sativa. Water physicochemical parameters such as temperature, dissolved oxygen (DO, pH and electric conductivity were assessed in situ. The three plant species were efficient bio-indicators, since they presented good cost-benefit and fast and easily interpreted results, thus completing the physicochemical parameters. There was strong correlation between seed germination and root growth among the ecotoxicological parameters assessed in L. sativa and A. cepa. The micronuclei percentage in T. pallida and the MI in A. cepa presented strong correlation with water electric conductivity and moderate and negative correlation with DO. Water electric conductivity ranged from 75 to 438 µS.cm-1; and the DO concentrations ranged from 0.5 to 6.9 mg.L-1. The importance of pollution control measures in the Uberaba River basin stands out. From the supply-water capture point, the basin is strongly affected by pollution, mainly in the tributaries that cross the city. It presents a short, or almost absent, riparian forest line, residues on the river banks, and it is impacted by discharges of untreated sewage, among other anthropic actions.

π π scattering by pole extrapolation methods

International Nuclear Information System (INIS)

Lott, F.W. III.

1978-01-01

A 25-inch hydrogen bubble chamber was used at the Lawrence Berkeley Laboratory Bevatron to produce 300,000 pictures of π + p interactions at an incident momentum of the π + of 2.67 GeV/c. The 2-prong events were processed using the FSD and the FOG-CLOUDY-FAIR data reduction system. Events of the nature π + p→π + pπ 0 and π + p→π + π + n with values of momentum transfer to the proton of -t less than or equal to 0.238 GeV 2 were selected. These events were used to extrapolate to the pion pole (t = m/sub π/ 2 ) in order to investigate the π π interaction with isospins of both T=1 and T=2. Two methods were used to do the extrapolation: the original Chew-Low method developed in 1959 and the Durr-Pilkuhn method developed in 1965, which takes into account centrifugal barrier penetration factors. At first it seemed that, while the Durr-Pilkuhn method gave better values for the total π π cross section, the Chew-Low method gave better values for the angular distribution. Further analysis, however, showed that, if the requirement of total OPE (one-pion-exchange) was dropped, then the Durr-Pilkuhn method gave more reasonable values of the angular distribution as well as for the total π π cross section

π π scattering by pole extrapolation methods

International Nuclear Information System (INIS)

Lott, F.W. III.

1977-01-01

A 25-inch hydrogen bubble chamber was used at the Lawrence Berkeley Laboratory Bevatron to produce 300,000 pictures of π + p interactions at an incident momentum of the π + of 2.67 GeV/c. The 2-prong events were processed using the FSD and the FOG-CLOUDY-FAIR data reduction system. Events of the nature π + p → π + pπ 0 and π + p → π + π + n with values of momentum transfer to the proton of -t less than or equal to 0.238 GeV 2 were selected. These events were used to extrapolate to the pion pole (t = m/sub π/ 2 ) in order to investigate the π π interaction with isospins of both T = 1 and T = 2. Two methods were used to do the extrapolation: the original Chew-Low method developed in 1959 and the Durr-Pilkuhn method developed in 1965 which takes into account centrifugal barrier penetration factors. At first it seemed that, while the Durr-Pilkuhn method gave better values for the total π π cross section, the Chew-Low method gave better values for the angular distribution. Further analysis, however, showed that if the requirement of total OPE (one-pion-exchange) were dropped, then the Durr-Pilkuhn method gave more reasonable values of the angular distribution as well as for the total π π cross section

Correction method for critical extrapolation of control-rods-rising during physical start-up of reactor

International Nuclear Information System (INIS)

Zhang Fan; Chen Wenzhen; Yu Lei

2008-01-01

During physical start-up of nuclear reactor, the curve got by lifting the con- trol rods to extrapolate to the critical state is often in protruding shape, by which the supercritical phenomena is led. In the paper, the reason why the curve was in protruding was analyzed. A correction method was introduced, and the calculations were carried out by the practical data used in a nuclear power plant. The results show that the correction method reverses the protruding shape of the extrapolating curve, and the risk of reactor supercritical phenomena can be reduced using the extrapolated curve got by the correction method during physical start-up of the reactor. (authors)

Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2009-01-01

extrapolation are presented. The first method is based on the same assumptions as the existing method but the statistical extrapolation is only performed for a limited number of mean wind speeds where the extreme load is likely to occur. For the second method the mean wind speeds are divided into storms which......The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load...... are assumed independent and the characteristic loads are determined from the extreme load in each storm....

Empirical models of the Solar Wind : Extrapolations from the Helios & Ulysses observations back to the corona

Science.gov (United States)

Maksimovic, M.; Zaslavsky, A.

2017-12-01

We will present extrapolation of the HELIOS & Ulysses proton density, temperature & bulk velocities back to the corona. Using simple mass flux conservations we show a very good agreement between these extrapolations and the current state knowledge of these parameters in the corona, based on SOHO mesurements. These simple extrapolations could potentially be very useful for the science planning of both the Parker Solar Probe and Solar Orbiter missions. Finally will also present some modelling considerations, based on simple energy balance equations which arise from these empirical observationnal models.

Extrapolated HPGe efficiency estimates based on a single calibration measurement

International Nuclear Information System (INIS)

Winn, W.G.

1994-01-01

Gamma spectroscopists often must analyze samples with geometries for which their detectors are not calibrated. The effort to experimentally recalibrate a detector for a new geometry can be quite time consuming, causing delay in reporting useful results. Such concerns have motivated development of a method for extrapolating HPGe efficiency estimates from an existing single measured efficiency. Overall, the method provides useful preliminary results for analyses that do not require exceptional accuracy, while reliably bracketing the credible range. The estimated efficiency element-of for a uniform sample in a geometry with volume V is extrapolated from the measured element-of 0 of the base sample of volume V 0 . Assuming all samples are centered atop the detector for maximum efficiency, element-of decreases monotonically as V increases about V 0 , and vice versa. Extrapolation of high and low efficiency estimates element-of h and element-of L provides an average estimate of element-of = 1/2 [element-of h + element-of L ] ± 1/2 [element-of h - element-of L ] (general) where an uncertainty D element-of = 1/2 (element-of h - element-of L ] brackets limits for a maximum possible error. The element-of h and element-of L both diverge from element-of 0 as V deviates from V 0 , causing D element-of to increase accordingly. The above concepts guided development of both conservative and refined estimates for element-of

Micro-computed tomography (μCT) as a novel method in ecotoxicology - determination of morphometric and somatic data in rainbow trout (Oncorhynchus mykiss)

NARCIS (Netherlands)

Brinkmann, M.; Rizzo, L.Y.; Lammers, Twan Gerardus Gertudis Maria; Gremse, F.; Schiwy, S.; Kiessling, F.; Hollert, H.

2016-01-01

Fish are important sentinel organisms for the assessment of water quality and play a central role in ecotoxicological research. Of particular importance to the assessment of health and fitness of fish stocks in response to environmental conditions or pollution are morphometric (e.g. Fulton's

Ecotoxicological risks associated with tannery effluent wastewater.

Science.gov (United States)

Shakir, Lubna; Ejaz, Sohail; Ashraf, Muhammad; Qureshi, Naureen Aziz; Anjum, Aftab Ahmad; Iltaf, Imran; Javeed, Aqeel

2012-09-01

The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P<0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural

Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces

International Nuclear Information System (INIS)

Omelyan, Igor; Kovalenko, Andriy

2013-01-01

We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics

On the limits of toxicant-induced tolerance testing: cotolerance and response variation of antibiotic effects.

NARCIS (Netherlands)

Schmitt, Heike; Martinali, Bennie; Beelen, Patrick van; Seinen, Willem

2006-01-01

Pollution-induced community tolerance (PICT) as an ecotoxicological test system has been claimed to detect pollutant effects highly specifically and sensitively. However, the specificity might be limited by the occurrence of cotolerance. Another limitation of the application of any ecotoxicological

Impact of soil properties on critical concentrations of cadmium, lead, copper, zinc, and mercury in soil and soil solution in view of ecotoxicological effects.

Science.gov (United States)

de Vries, Wim; Lofts, Steve; Tipping, Ed; Meili, Markus; Groenenberg, Jan E; Schütze, Gudrun

2007-01-01

Risk assessment for metals in terrestrial ecosystems, including assessments of critical loads, requires appropriate critical limits for metal concentrations in soil and soil solution. This chapter presents an overview of methodologies used to derive critical (i) reactive and total metal concentrations in soils and (ii) free metal ion and total metal concentrations in soil solution for Cd, Pb, Cu, Zn, and Hg, taking into account the effect of soil properties related to ecotoxicological effects. Most emphasis is given to the derivation of critical free and total metal concentrations in soil solution, using available NOEC soil data and transfer functions relating solid-phase and dissolved metal concentrations. This approach is based on the assumption that impacts on test organisms (plants, microorganisms, and soil invertebrates) are mainly related to the soil solution concentration (activity) and not to the soil solid-phase content. Critical Cd, Pb, Cu, Zn, and Hg concentrations in soil solution vary with pH and DOC level. The results obtained are generally comparable to those derived for surface waters based on impacts to aquatic organisms. Critical soil metal concentrations, related to the derived soil solution limits, can be described as a function of pH and organic matter and clay content, and varying about one order of magnitude between different soil types.

Regression models in the determination of the absorbed dose with extrapolation chamber for ophthalmological applicators

International Nuclear Information System (INIS)

Alvarez R, J.T.; Morales P, R.

1992-06-01

The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, ( 90 Sr/ 90 Y, 1850 MBq) using an extrapolation chamber of variable electrodes; when estimating the slope of the extrapolation curve using a simple lineal regression model is observed that the dose values are underestimated from 17.7 percent up to a 20.4 percent in relation to the estimate of this dose by means of a regression model polynomial two grade, at the same time are observed an improvement in the standard error for the quadratic model until in 50%. Finally the global uncertainty of the dose is presented, taking into account the reproducibility of the experimental arrangement. As conclusion it can infers that in experimental arrangements where the source is to contact with the extrapolation chamber, it was recommended to substitute the lineal regression model by the quadratic regression model, in the determination of the slope of the extrapolation curve, for more exact and accurate measurements of the absorbed dose. (Author)

Arsenic rich iron plaque on macrophyte roots--an ecotoxicological risk?

Science.gov (United States)

Taggart, M A; Mateo, R; Charnock, J M; Bahrami, F; Green, A J; Meharg, A A

2009-03-01

Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcóllar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root+plaque' material in excess of 1000 mg kg(-1), and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcóllar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque.

Organic Trace Compounds as Emisions of Incineration Plants and their Toxicological and Ecotoxicological Classification - Part 2. Toxicological and ecotoxicological classification; Organische Spurenstoffe als Emissionen aus Verbrennungsanlagen und deren humantoxikologische und oekotoxikologische Einordnung. T. 2. Humantoxikologische und oekotoxikologische Einordnung

Energy Technology Data Exchange (ETDEWEB)

Kaiser, G.; Wiedmann, T.; Ballschmiter, K.

1998-02-01

In this report (`Organic Trace Compounds as Emissions of Incineration Plants and their Toxicological and Ecotoxicologial Classification - Part 2: Toxicological and Ecotoxicological Classification`) emissions of organic compounds, measured from German municipal waste incineration plants, are compared with toxicological and ecotoxicological data, limits and threshold values and environmental baseline levels. Emission data of other combustion processes are integrated if available. A modern waste incineration plant, observing German emission regulations, emits less of most substances reported here than other industrial processes or e.g. the combustion of wood or coal. (orig.) [Deutsch] Im vorliegenden Arbeitsbericht (`Organische Spurenstoffe als Emissionen aus Verbrennungsanlagen und deren humantoxikologische und oekotoxikologische Einordnung - Teil 2: Humantoxikologische und oekotoxikologische Einordnung`) werden die realen organischen Emissionen von Muellverbrennungsanlagen in groesstmoeglicher stofflicher Differenzierung toxikologisch eingeordnet. Hierzu werden die Daten mit human-/oekotoxikologischen Kenngroessen, Grenz- und Orientierungswerten sowie mit der Hintergrundbelastung verglichen und die inhalative Zusatzbelastung wird berechnet. Diese liegt fuer alle Stoffe im Bereich von 10{sup -9} bis 10{sup -1} Prozent. Eine Ausnahme bilden die Phthalsaeureester mit einem Spitzenwert fuer die Zusatzbelastung von 6,5%. Wenn vorhanden, werden die Emissionsdaten von anderen Verbrennungsprozessen mit in die Einordnung aufgenommen. Von vielen Substanzklassen wird bei einer Abfallverbrennungsanlage, die die Grenzwerte der 17. BImSchV einhaelt, weniger an die Umgebungsluft abgegeben als bei anderen industriellen Prozessen oder z.B. bei der Verbrennung von Kohle oder Holz. (orig.)

Dynamic Aperture Extrapolation in Presence of Tune Modulation

CERN Document Server

Giovannozzi, Massimo; Todesco, Ezio

1998-01-01

In hadron colliders, such as the Large Hadron Collider (LHC) to be built at CERN, the long-term stability of the single-particle motion is mostly determined by the field-shape quality of the superconducting magnets. The mechanism of particle loss may be largely enhanced by modulation of betatron tunes, induced either by synchro-betatron coupling (via the residual uncorrected chromaticity), or by unavoidable power supply ripple. This harmful effect is investigated in a simple dynamical system model, the Henon map with modulated linear frequencies. Then, a realistic accelerator model describing the injection optics of the LHC lattice is analyzed. Orbital data obtained with long-term tracking simulations ($10^5$-$10^7$ turns) are post-processed to obtain the dynamic aperture. It turns out that the dynamic aperture can be interpolated using a simple mpirical formula, and it decays proportionally to a power of the inverse logarithm of the number of turns. Furthermore, the extrapolation of tracking data at $10^5$ t...

131I-SPGP internal dosimetry: animal model and human extrapolation

International Nuclear Information System (INIS)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soprani, Juliana; Santos, Raquel Gouvea dos; Figueiredo, Suely Gomes de

2009-01-01

Scorpaena plumieri is commonly called moreia-ati or manganga and is the most venomous and one of the most abundant fish species of the Brazilian coast. Soprani 2006, demonstrated that SPGP - an isolated protein from S. plumieri fish- possess high antitumoral activity against malignant tumours and can be a source of template molecules for the development (design) of antitumoral drugs. In the present work, Soprani's 125 ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the 131 I-SPGP uptake were determinate in several organs of mice, as well as in the implanted tumor. Doses obtained for animal model were extrapolated to humans assuming a similar ratio for various mouse and human tissues. For the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 131 I were considered. (author)

Accelerating Monte Carlo Molecular Simulations Using Novel Extrapolation Schemes Combined with Fast Database Generation on Massively Parallel Machines

KAUST Repository

Amir, Sahar Z.

2013-05-01

We introduce an efficient thermodynamically consistent technique to extrapolate and interpolate normalized Canonical NVT ensemble averages like pressure and energy for Lennard-Jones (L-J) fluids. Preliminary results show promising applicability in oil and gas modeling, where accurate determination of thermodynamic properties in reservoirs is challenging. The thermodynamic interpolation and thermodynamic extrapolation schemes predict ensemble averages at different thermodynamic conditions from expensively simulated data points. The methods reweight and reconstruct previously generated database values of Markov chains at neighboring temperature and density conditions. To investigate the efficiency of these methods, two databases corresponding to different combinations of normalized density and temperature are generated. One contains 175 Markov chains with 10,000,000 MC cycles each and the other contains 3000 Markov chains with 61,000,000 MC cycles each. For such massive database creation, two algorithms to parallelize the computations have been investigated. The accuracy of the thermodynamic extrapolation scheme is investigated with respect to classical interpolation and extrapolation. Finally, thermodynamic interpolation benefiting from four neighboring Markov chains points is implemented and compared with previous schemes. The thermodynamic interpolation scheme using knowledge from the four neighboring points proves to be more accurate than the thermodynamic extrapolation from the closest point only, while both thermodynamic extrapolation and thermodynamic interpolation are more accurate than the classical interpolation and extrapolation. The investigated extrapolation scheme has great potential in oil and gas reservoir modeling.That is, such a scheme has the potential to speed up the MCMC thermodynamic computation to be comparable with conventional Equation of State approaches in efficiency. In particular, this makes it applicable to large-scale optimization of L

Extrapolating Satellite Winds to Turbine Operating Heights

DEFF Research Database (Denmark)

Badger, Merete; Pena Diaz, Alfredo; Hahmann, Andrea N.

2016-01-01

Ocean wind retrievals from satellite sensors are typically performed for the standard level of 10 m. This restricts their full exploitation for wind energy planning, which requires wind information at much higher levels where wind turbines operate. A new method is presented for the vertical...... extrapolation of satellitebased wind maps. Winds near the sea surface are obtained from satellite data and used together with an adaptation of the Monin–Obukhov similarity theory to estimate the wind speed at higher levels. The thermal stratification of the atmosphere is taken into account through a long...

Ecotoxicological assessments and the setting of limit values for chemicals in the environment

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-11-01

The Committee on the Setting of Limit Values for Chemicals held its first open conference in Denmark in March 1992 at Mogenstrup Kro, Zealand. The conference proceedings were entitled `Risk Management and Risk Assessment in Different Sectors in Denmark`. The conference focused on risk assessment and the setting of limit values for chemicals in connection with human exposure to chemicals. The conference held in January 1996, which is covered by the present proceedings, dealt with the exposure of the environment to chemicals and the state-of-the-art as well as perspectives of ecotoxicological research. Special emphasis was placed on the illustration and discussion of the problems that have to be solved in order to secure satisfactory levels of protection of soil and aquatic environments in connection with exposure to chemicals. Also, problems connected with exposure through the atmosphere were discussed and exemplified by the work on the setting of limit values for tropospheric ozone. Furthermore, the global problems pertaining to what is believed to be the greenhouse effect and the degradation of the stratospheric ozone layer as well as the damage to crops caused by ozone were mentioned. (au)

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor.

Science.gov (United States)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M

2017-04-01

Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ 13 C) were measured among treatments ranging from 0 to 15000nmol/L-sucralose and 0-323nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ 13 C of L. minor at environmentally relevant concentrations. The increase of δ 13 C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor-a mixotrophic plant-can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine significantly decreased L. minor root growth, daily growth rate, and asexual reproduction at 323nmol/L-fluoxetine; however, ambiguity remains regarding the mechanisms responsible and the applicability of these extreme concentrations unprecedented in the natural environment. To our knowledge, this was the

Evaluation of functioning of an extrapolation chamber using Monte Carlo method

International Nuclear Information System (INIS)

Oramas Polo, I.; Alfonso Laguardia, R.

2015-01-01

The extrapolation chamber is a parallel plate chamber and variable volume based on the Braff-Gray theory. It determines in absolute mode, with high accuracy the dose absorbed by the extrapolation of the ionization current measured for a null distance between the electrodes. This camera is used for dosimetry of external beta rays for radiation protection. This paper presents a simulation for evaluating the functioning of an extrapolation chamber type 23392 of PTW, using the MCNPX Monte Carlo method. In the simulation, the fluence in the air collector cavity of the chamber was obtained. The influence of the materials that compose the camera on its response against beta radiation beam was also analysed. A comparison of the contribution of primary and secondary radiation was performed. The energy deposition in the air collector cavity for different depths was calculated. The component with the higher energy deposition is the Polymethyl methacrylate block. The energy deposition in the air collector cavity for chamber depth 2500 μm is greater with a value of 9.708E-07 MeV. The fluence in the air collector cavity decreases with depth. It's value is 1.758E-04 1/cm 2 for chamber depth 500 μm. The values reported are for individual electron and photon histories. The graphics of simulated parameters are presented in the paper. (Author)

Ecotoxicological analysis during the removal of carbofuran in fungal bioaugmented matrices.

Science.gov (United States)

Ruíz-Hidalgo, Karla; Masís-Mora, Mario; Barbieri, Edison; Carazo-Rojas, Elizabeth; Rodríguez-Rodríguez, Carlos E

2016-02-01

Biomixtures are used for the removal of pesticides from agricultural wastewater. As biomixtures employ high content of lignocellulosic substrates, their bioaugmentation with ligninolytic fungi represents a novel approach for their enhancement. Nonetheless, the decrease in the concentration of the pesticide may result in sublethal concentrations that still affect ecosystems. Two matrices, a microcosm of rice husk (lignocellulosic substrate) bioaugmented with the fungus Trametes versicolor and a biomixture that contained fungally colonized rice husk were used in the degradation of the insecticide/nematicide carbofuran (CFN). Elutriates simulating lixiviates from these matrices were used to assay the ecotoxicological effects at sublethal level over Daphnia magna (Straus) and the fish Oreochromis aureus (Steindachner) and Oncorhynchus mykiss (Walbaum). Elutriates obtained after 30 d of treatment in the rice husk microcosms at dilutions over 2.5% increased the offspring of D. magna as a trade-off stress response, and produced mortality of neonates at dilutions over 5%. Elutriates (dilution 1:200) obtained during a 30 d period did not produce alterations on the oxygen consumption and ammonium excretion of O. mykiss, however these physiological parameters were affected in O. aureus at every time point of treatment, irrespective of the decrease in CFN concentration. When the fungally colonized rice husk was used to prepare a biomixture, where more accelerated degradation is expected, similar alterations on the responses by O. aureus were achieved. Results suggest that despite the good removal of the pesticide, it is necessary to optimize biomixtures to minimize their residual toxicity and potential chronic effects on aquatic life. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ecotoxicology of aluminum to fish and wildlife

Science.gov (United States)

Sparling, D.W.; Lowe, T.P.; Campbell, P.G.C.; Yokel, Robert A.; Golub, Mari S.

1997-01-01

The toxicity of aluminum has been studied extensively in fish, less so in invertebrates, amphibians, and birds, and not at all in reptiles and free-ranging mammals. For aquatic organisms, Al bioavailability and toxicity are intimately related to ambient pH; changes in ambient acidity may affect Al solubility, dissolved Al speciation, and organism sensitivity to Al. At moderate acidity (pH 5.5 to 7.0), fish and invertebrates may be stressed due to Al adsorption onto gill surfaces and subsequent asphyxiation. At pH 4.5 to 5.5, Al can impair ion regulation and augment the toxicity of H+. At lower pH, elevated Al can temporarily ameliorate the toxic effects of acidity by competing for binding sites with H+. Aluminum toxicity in aquatic environments is further affected by the concentration of ligands such as dissolved organic matter, fluoride, or sulfate, and of other cations such as Ca and Mg which compete for cellular binding sites. Although risk of Al toxicity is often based on a model of free-ion (Al3+) activity, recent evidence suggests that factors determining Al toxicity may be more complex. In general, aquatic invertebrates are less sensitive to Al toxicity and acidity than fish; thus acidified, Al-rich waters may actually reduce predation pressure. Fish may be affected by asphyxiation at moderate acidic conditions or electrolyte imbalances at lower pH. In amphibians, embryos and young larvae are typically more sensitive than older larvae. Early breeding amphibians, which lay eggs in ephemeral ponds and streams subject to spring runoff, are most at risk from Al and acidification; those that breed later in the year in lakes or rivers are least vulnerable. Birds and mammals are most likely exposed through dietary ingestion of soil or Al-contaminated foods. Concentrations > 1000 mg.kg-1 in food may be toxic to young birds and mammals. Clinical signs in these animals are consistent with rickets because Al precipitates with P in the gut. Suggestions for additional

Editorial : Laudation to prof.dr. Hans-Toni Tarre- towards conceptual, theory-based ecological science and its transfer to the applied field of ecotoxicology

NARCIS (Netherlands)

Brock, T.C.M.; Giesy, J.P.; Heimbach, F.; Hollert, H.; Ross-Nickoll, M.; Schaffer, A.; Steinhauser, K.G.

2011-01-01

In order to thank Prof. Dr. Hans-Toni Ratte on the occasion of his retirement for his outstanding experimental and modelling merits in the field of ecotoxicology and ecology and his personal 65th anniversary on November 25th this article will present a laudation.

Extrapolations of nuclear binding energies from new linear mass relations

DEFF Research Database (Denmark)

Hove, D.; Jensen, A. S.; Riisager, K.

2013-01-01

We present a method to extrapolate nuclear binding energies from known values for neighboring nuclei. We select four specific mass relations constructed to eliminate smooth variation of the binding energy as function nucleon numbers. The fast odd-even variations are avoided by comparing nuclei...

Extrapolated stabilized explicit Runge-Kutta methods

Science.gov (United States)

Martín-Vaquero, J.; Kleefeld, B.

2016-12-01

Extrapolated Stabilized Explicit Runge-Kutta methods (ESERK) are proposed to solve multi-dimensional nonlinear partial differential equations (PDEs). In such methods it is necessary to evaluate the function nt times per step, but the stability region is O (nt2). Hence, the computational cost is O (nt) times lower than for a traditional explicit algorithm. In that way stiff problems can be integrated by the use of simple explicit evaluations in which case implicit methods usually had to be used. Therefore, they are especially well-suited for the method of lines (MOL) discretizations of parabolic nonlinear multi-dimensional PDEs. In this work, first s-stages first-order methods with extended stability along the negative real axis are obtained. They have slightly shorter stability regions than other traditional first-order stabilized explicit Runge-Kutta algorithms (also called Runge-Kutta-Chebyshev codes). Later, they are used to derive nt-stages second- and fourth-order schemes using Richardson extrapolation. The stability regions of these fourth-order codes include the interval [ - 0.01nt2, 0 ] (nt being the number of total functions evaluations), which are shorter than stability regions of ROCK4 methods, for example. However, the new algorithms neither suffer from propagation of errors (as other Runge-Kutta-Chebyshev codes as ROCK4 or DUMKA) nor internal instabilities. Additionally, many other types of higher-order (and also lower-order) methods can be obtained easily in a similar way. These methods also allow adaptation of the length step with no extra cost. Hence, the stability domain is adapted precisely to the spectrum of the problem at the current time of integration in an optimal way, i.e., with minimal number of additional stages. We compare the new techniques with other well-known algorithms with good results in very stiff diffusion or reaction-diffusion multi-dimensional nonlinear equations.

Selecting chemical and ecotoxicological test batteries for risk assessment of trace element-contaminated soils (phyto)managed by gentle remediation options (GRO).

Science.gov (United States)

Kumpiene, Jurate; Bert, Valérie; Dimitriou, Ioannis; Eriksson, Jan; Friesl-Hanl, Wolfgang; Galazka, Rafal; Herzig, Rolf; Janssen, Jolien; Kidd, Petra; Mench, Michel; Müller, Ingo; Neu, Silke; Oustriere, Nadège; Puschenreiter, Markus; Renella, Giancarlo; Roumier, Pierre-Hervé; Siebielec, Grzegorz; Vangronsveld, Jaco; Manier, Nicolas

2014-10-15

During the past decades a number of field trials with gentle remediation options (GRO) have been established on trace element (TE) contaminated sites throughout Europe. Each research group selects different methods to assess the remediation success making it difficult to compare efficacy between various sites and treatments. This study aimed at selecting a minimum risk assessment battery combining chemical and ecotoxicological assays for assessing and comparing the effectiveness of GRO implemented in seven European case studies. Two test batteries were pre-selected; a chemical one for quantifying TE exposure in untreated soils and GRO-managed soils and a biological one for characterizing soil functionality and ecotoxicity. Soil samples from field studies representing one of the main GROs (phytoextraction in Belgium, Sweden, Germany and Switzerland, aided phytoextraction in France, and aided phytostabilization or in situ stabilization/phytoexclusion in Poland, France and Austria) were collected and assessed using the selected test batteries. The best correlations were obtained between NH4NO3-extractable, followed by NaNO3-extractable TE and the ecotoxicological responses. Biometrical parameters and biomarkers of dwarf beans were the most responsive indicators for the soil treatments and changes in soil TE exposures. Plant growth was inhibited at the higher extractable TE concentrations, while plant stress enzyme activities increased with the higher TE extractability. Based on these results, a minimum risk assessment battery to compare/biomonitor the sites phytomanaged by GROs might consist of the NH4NO3 extraction and the bean Plantox test including the stress enzyme activities. Copyright © 2014 Elsevier B.V. All rights reserved.

Terrestrial Eco-Toxicological Tests as Screening Tool to Assess Soil Contamination in Krompachy Area

Science.gov (United States)

Ol'ga, Šestinová; Findoráková, Lenka; Hančuľák, Jozef; Fedorová, Erika; Tomislav, Špaldon

2016-10-01

In this study, we present screening tool of heavy metal inputs to agricultural and permanent grass vegetation of the soils in Krompachy. This study is devoted to Ecotoxicity tests, Terrestrial Plant Test (modification of OECD 208, Phytotoxkit microbiotest on Sinapis Alba) and chronic tests of Earthworm (Dendrobaena veneta, modification of OECD Guidelines for the testing of chemicals 317, Bioaccumulation in Terrestrial Oligochaetes) as practical and sensitive screening method for assessing the effects of heavy metals in Krompachy soils. The total Cu, Zn, As, Pb and Hg concentrations and eco-toxicological tests of soils from the Krompachy area were determined of 4 sampling sites in 2015. An influence of the sampling sites distance from the copper smeltery on the absolutely concentrations of metals were recorded for copper, lead, zinc, arsenic and mercury. The highest concentrations of these metals were detected on the sampling sites up to 3 km from the copper smeltery. The samples of soil were used to assess of phytotoxic effect. Total mortality was established at earthworms using chronic toxicity test after 7 exposure days. The results of our study confirmed that no mortality was observed in any of the study soils. Based on the phytotoxicity testing, phytotoxic effects of the metals contaminated soils from the samples 3KR (7-9) S.alba seeds was observed.

Content of PAHs, activities of γ-radionuclides and ecotoxicological assessment in biochars

Directory of Open Access Journals (Sweden)

Gondek Krzysztof

2016-12-01

Full Text Available The aim of this research was to determine the effect of thermal conversion temperature and plant material addition to sewage sludge on the PAHs content and the activity of selected γ-radionuclides in biochars, and to conduct an ecotoxicological assessment. The pyrolysis of the mixtures of sewage sludge and plant materials at 300°C and such temperature caused an increase in the contents of 2- and 3-ring hydrocarbons. During the pyrolysis of organic materials at 600°C, the amount of the following compounds was reduced in biochars: benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene. Among γ-radioisotopes of the elements, natural radiogenic isotopes were dominant. 137Cs was the only artificial radioactive isotope. The pyrolysis of the mixtures of municipal sewage sludge and plant materials revealed that isotope 40K had the highest radioactive activity. In the case of other analysed nuclides, activities of 212Pb, 214Pb, 214Bi, and 137Cs were determined after the sample pyrolysis. The extracts from the mixtures of sewage sludge and plant materials were non-toxic to Vibrio fischeri.

An ecotoxicological approach to evaluate the effects of tourism impacts in the Marine Protected Area of La Maddalena (Sardinia, Italy).

Science.gov (United States)

Moschino, V; Schintu, M; Marrucci, A; Marras, B; Nesto, N; Da Ros, L

2017-09-15

In the Marine Protected Area of La Maddalena Archipelago, environmental protection rules and safeguard measures for nautical activities have helped in reducing anthropogenic pressure; however, tourism related activities remain particularly significant in summer. With the aim of evaluating their impacts, the biomarker approach using transplanted Mytilus galloprovincialis as sentinel organisms coupled with POCIS deployment was applied. Mussels, translocated to four marine areas differently impacted by tourism activities, were sampled before, during and after the tourist season. Moreover, endocrine disruptors in passive samplers POCIS and the cellular toxicity of whole POCIS extracts on mussel haemocytes were evaluated to integrate ecotoxicological information. Lysosomal biomarkers, condition index and mortality rate, as well as metals in tissues suggested an alteration of the health status of mussels transplanted to the most impacted sites. The cellular toxicity of POCIS extracts was pointed out, notwithstanding the concentrations of the examined compounds were always below the detection limits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ecotoxicological and analytical assessment of hydrocarbon-contaminated soils and application to ecological risk assessment

Energy Technology Data Exchange (ETDEWEB)

Saterbak, A.; Toy, R.J.; Wong, D.C.L.; McMain, B.J.; Williams, M.P.; Dorn, P.B.; Brzuzy, L.P.; Chai, E.Y.; Salanitro, J.P.

1999-07-01

Ecotoxicological assessments of contaminated soil aim to understand the effect of introduced chemicals on the soil flora and fauna. Ecotoxicity test methods were developed and conducted on hydrocarbon-contaminated soils and on adjacent uncontaminated control soils from eight field locations. Tests included 7-d, 14-d, and chronic survival tests and reproduction assays for the earthworm (Eisenia fetida) and seed germination, root length, and plant growth assays for corn, lettuce, mustard, and wheat. Species-specific responses were observed with no-observed effect concentrations (NOECs) ranging from <1 to 100% contaminated soil. The 14-d earthworm survival NOEC was equal to or greater than the reproduction NOEC values for numbers of cocoons and juveniles, which were similar to one another. Cocoon and juvenile production varied among the control soils. Germination and root length NOECs for mustard and lettuce were less than NOECs for corn and wheat. Root length NOECs were similar to or less than seed germination NOECs. Statistically significant correlations for earthworm survival and seed germination as a function of hydrocarbon measurements were found. The 14-d earthworm survival and the seed germination tests are recommended for use in the context of a risk-based framework for the ecological assessment of contaminated sites.

An experimental extrapolation technique using the Gafchromic EBT3 film for relative output factor measurements in small x-ray fields

Energy Technology Data Exchange (ETDEWEB)

Morales, Johnny E., E-mail: johnny.morales@lh.org.au [Department of Radiation Oncology, Chris O’Brien Lifehouse, 119-143 Missenden Road, Camperdown, NSW 2050, Australia and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Level 4 O Block, Garden’s Point, QLD 4001 (Australia); Butson, Martin; Hill, Robin [Department of Radiation Oncology, Chris O’Brien Lifehouse, 119-143 Missenden Road, Camperdown, NSW 2050, Australia and Institute of Medical Physics, University of Sydney, NSW 2006 (Australia); Crowe, Scott B. [School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Level 4 O Block, Garden’s Point, QLD 4001, Australia and Cancer Care Services, Royal Brisbane and Women’s Hospital, Butterfield Street, Herston, QLD 4029 (Australia); Trapp, J. V. [School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Level 4 O Block, Garden’s Point, QLD 4001 (Australia)

2016-08-15

Purpose: An experimental extrapolation technique is presented, which can be used to determine the relative output factors for very small x-ray fields using the Gafchromic EBT3 film. Methods: Relative output factors were measured for the Brainlab SRS cones ranging in diameters from 4 to 30 mm{sup 2} on a Novalis Trilogy linear accelerator with 6 MV SRS x-rays. The relative output factor was determined from an experimental reducing circular region of interest (ROI) extrapolation technique developed to remove the effects of volume averaging. This was achieved by scanning the EBT3 film measurements with a high scanning resolution of 1200 dpi. From the high resolution scans, the size of the circular regions of interest was varied to produce a plot of relative output factors versus area of analysis. The plot was then extrapolated to zero to determine the relative output factor corresponding to zero volume. Results: Results have shown that for a 4 mm field size, the extrapolated relative output factor was measured as a value of 0.651 ± 0.018 as compared to 0.639 ± 0.019 and 0.633 ± 0.021 for 0.5 and 1.0 mm diameter of analysis values, respectively. This showed a change in the relative output factors of 1.8% and 2.8% at these comparative regions of interest sizes. In comparison, the 25 mm cone had negligible differences in the measured output factor between zero extrapolation, 0.5 and 1.0 mm diameter ROIs, respectively. Conclusions: This work shows that for very small fields such as 4.0 mm cone sizes, a measureable difference can be seen in the relative output factor based on the circular ROI and the size of the area of analysis using radiochromic film dosimetry. The authors recommend to scan the Gafchromic EBT3 film at a resolution of 1200 dpi for cone sizes less than 7.5 mm and to utilize an extrapolation technique for the output factor measurements of very small field dosimetry.

Aitken extrapolation and epsilon algorithm for an accelerated solution of weakly singular nonlinear Volterra integral equations

International Nuclear Information System (INIS)

Mesgarani, H; Parmour, P; Aghazadeh, N

2010-01-01

In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl. 324 225-37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.

The crab Carcinus maenas as a suitable experimental model in ecotoxicology.

Science.gov (United States)

Rodrigues, Elsa Teresa; Pardal, Miguel Ângelo

2014-09-01

Aquatic ecotoxicology broadly focuses on how aquatic organisms interact with pollutants in their environment in order to determine environmental hazard and potential risks to humans. Research has produced increasing evidence on the pivotal role of aquatic invertebrates in the assessment of the impact of pollutants on the environment. Its potential use to replace fish bioassays, which offers ethical advantages, has already been widely studied. Nevertheless, the selection of adequate invertebrate experimental models, appropriate experimental designs and bioassays, as well as the control of potential confounding factors in toxicity testing are of major importance to obtain scientifically valid results. Therefore, the present study reviews more than four decades of published research papers in which the Green crab Carcinus maenas was used as an experimental test organism. In general, the surveyed literature indicates that C. maenas is sensitive to a wide range of aquatic pollutants and that its biological responses are linked to exposure concentrations or doses. Current scientific knowledge regarding the biology and ecology of C. maenas and the extensive studies on toxicology found for the present review recognise the Green crab as a reliable estuarine/marine model for routine testing in ecotoxicology research and environmental quality assessment, especially in what concerns the application of the biomarker approach. Data gathered provide valuable information for the selection of adequate and trustworthy bioassays to be used in C. maenas toxicity testing. Since the final expression of high quality testing is a reliable outcome, the present review recommends gender, size and morphotype separation in C. maenas experimental designs and data evaluation. Moreover, the organisms' nutritional status should be taken into account, especially in long-term studies. Studies should also consider the crabs' resilience when facing historical and concurrent contamination. Finally

Brief communication: the ecosystem perspective in ecotoxicology as a way forward for the ecological risk assessment of chemicals.

Science.gov (United States)

De Laender, Frederik; Janssen, Colin R

2013-07-01

One of the objectives of the European Union (EU) ecological risk assessment of chemicals (ERA) is to derive maximum environmental concentrations that are not expected to cause adverse ecological effects. To this end, related EU directives list protection goals as well as guidelines that should be used to reach these goals. It is generally accepted that the individual-level endpoints on which these guidelines are based do not correspond to the listed population- and ecosystem-level protection goals. In this article, we identify 5 research topics that are key to bridging this gap: 1) the refinement of population-level effects and recovery rates by explicitly taking into account competition and 2) predation, 3) the assessment of chemical effects on biodiversity, 4) the assessment of chemical stress on ecosystem functions and services, and 5) the quantification of the effects of chemical mixtures. In addition, we illustrate why an ecosystem perspective is needed to address these topics and to inform the risk assessment process. We propose the use of existing ecotoxicological community, food web, and ecosystem models to tackle these issues and discuss why new models are needed to predict chemical effects on biodiversity. Copyright © 2013 SETAC.

Projecting species' vulnerability to climate change: Which uncertainty sources matter most and extrapolate best?

Science.gov (United States)

Steen, Valerie; Sofaer, Helen R; Skagen, Susan K; Ray, Andrea J; Noon, Barry R

2017-11-01

Species distribution models (SDMs) are commonly used to assess potential climate change impacts on biodiversity, but several critical methodological decisions are often made arbitrarily. We compare variability arising from these decisions to the uncertainty in future climate change itself. We also test whether certain choices offer improved skill for extrapolating to a changed climate and whether internal cross-validation skill indicates extrapolative skill. We compared projected vulnerability for 29 wetland-dependent bird species breeding in the climatically dynamic Prairie Pothole Region, USA. For each species we built 1,080 SDMs to represent a unique combination of: future climate, class of climate covariates, collinearity level, and thresholding procedure. We examined the variation in projected vulnerability attributed to each uncertainty source. To assess extrapolation skill under a changed climate, we compared model predictions with observations from historic drought years. Uncertainty in projected vulnerability was substantial, and the largest source was that of future climate change. Large uncertainty was also attributed to climate covariate class with hydrological covariates projecting half the range loss of bioclimatic covariates or other summaries of temperature and precipitation. We found that choices based on performance in cross-validation improved skill in extrapolation. Qualitative rankings were also highly uncertain. Given uncertainty in projected vulnerability and resulting uncertainty in rankings used for conservation prioritization, a number of considerations appear critical for using bioclimatic SDMs to inform climate change mitigation strategies. Our results emphasize explicitly selecting climate summaries that most closely represent processes likely to underlie ecological response to climate change. For example, hydrological covariates projected substantially reduced vulnerability, highlighting the importance of considering whether water

Evaluation of extrapolation methods for actual state expenditures on health care in Russian Federation

Directory of Open Access Journals (Sweden)

S. A. Banin

2016-01-01

Full Text Available Forecasting methods, extrapolation ones in particular, are used in health care for medical, biological and clinical research. The author, using accessible internet space, has not met a single publication devoted to extrapolation of financial parameters of health care activities. This determined the relevance of the material presented in the article: based on health care financing dynamics in Russia in 2000–2010 the author examined possibility of application of basic perspective extrapolation methods - moving average, exponential smoothing and least squares. It is hypothesized that all three methods can equally forecast actual public expenditures on health care in medium term in Russia’s current financial and economic conditions. The study result was evaluated in two time periods: within the studied interval and a five-year period. It was found that within the study period all methods have an average relative extrapolation error of 3–5%, which means high precision of the forecast. The study shown a specific feature of the least squares method which were gradually accumulating results so their economic interpretation became possible only in the end of the studied period. That is why the extrapolating results obtained by least squares method are not applicable in an entire study period and rather have a theoretical value. Beyond the study period, however, this feature was found to be the most corresponding to the real situation. It was the least squares method that proved to be the most appropriate for economic interpretation of the forecast results of actual public expenditures on health care. The hypothesis was not confirmed, the author received three differently directed results, while each method had independent significance and its application depended on evaluation study objectives and real social, economic and financial situation in Russian health care system.

131I-CRTX internal dosimetry: animal model and human extrapolation

International Nuclear Information System (INIS)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soares, Marcella Araugio; Silveira, Marina Bicalho; Santos, Raquel Gouvea dos

2009-01-01

Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. 125 I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, 125 I-Crtx biokinetic data (evaluated in mice bearing Erlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for 131 I-Crtx. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 131 I in the tissue were considered in dose calculations. (author)

Performance of a prototype of an extrapolation minichamber in various radiation beams

International Nuclear Information System (INIS)

Oliveira, M.L.; Caldas, L.V.E.

2007-01-01

An extrapolation minichamber was developed for measuring doses from weakly penetrating types of radiation. The chamber was tested at the radiotherapeutic dose level in a beam from a 90 Sr+ 90 Y check source, in a beam from a plane 90 Sr+ 90 Y ophthalmic applicator, and in several reference beams from an X-ray tube. Saturation, ion collection efficiency, stabilization time, extrapolation curves, linearity of chamber response vs. air kerma rate, and dependences of the response on the energy and irradiation angle were characterized. The results are satisfactory; they show that the chamber can be used in the dosimetry of 90 Sr+ 90 Y beta particles and low-energy X-ray beams

Windtunnel Rebuilding And Extrapolation To Flight At Transsonic Speed For ExoMars

Science.gov (United States)

Fertig, Markus; Neeb, Dominik; Gulhan, Ali

2011-05-01

The static as well as the dynamic behaviour of the EXOMARS vehicle in the transonic velocity regime has been investigated experimentally by the Supersonic and Hypersonic Technology Department of DLR in order to investigate the behaviour prior to parachute opening. Since the experimental work was performed in air, a numerical extrapolation to flight by means of CFD is necessary. At low supersonic speed this extrapolation to flight was performed by the Spacecraft Department of the Institute of Flow Technology of DLR employing the CFD code TAU. Numerical as well as experimental results for the wind tunnel test at Mach 1.2 will be compared and discussed for three different angles of attack.

In vitro to in vivo extrapolation of effective dosimetry in developmental toxicity testing : Application of a generic PBK modelling approach

NARCIS (Netherlands)

Fragki, Styliani; Piersma, Aldert H; Rorije, Emiel; Zeilmaker, Marco J

2017-01-01

Incorporation of kinetics to quantitative in vitro to in vivo extrapolations (QIVIVE) is a key step for the realization of a non-animal testing paradigm, in the sphere of regulatory toxicology. The use of Physiologically-Based Kinetic (PBK) modelling for determining systemic doses of chemicals at

In vitro to in vivo extrapolation of effective dosimetry in developmental toxicity testing: Application of a generic PBK modelling approach.

NARCIS (Netherlands)

Fragki, Styliani; Piersma, Aldert H; Rorije, Emiel; Zeilmaker, Marco J

2017-01-01

Incorporation of kinetics to quantitative in vitro to in vivo extrapolations (QIVIVE) is a key step for the realization of a non-animal testing paradigm, in the sphere of regulatory toxicology. The use of Physiologically-Based Kinetic (PBK) modelling for determining systemic doses of chemicals at

Determination of the most appropriate method for extrapolating overall survival data from a placebo-controlled clinical trial of lenvatinib for progressive, radioiodine-refractory differentiated thyroid cancer

Directory of Open Access Journals (Sweden)

Tremblay G

2016-06-01

Full Text Available Gabriel Tremblay,1 Christopher Livings,2 Lydia Crowe,2 Venediktos Kapetanakis,2 Andrew Briggs3 1Global Health Economics and Health Technology Assessment, Eisai Inc., Woodcliff Lake, NJ, USA; 2Health Economics, Decision Resources Group, Bicester, Oxfordshire, 3Health Economics and Health Technology Assessment, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK Background: Cost-effectiveness models for the treatment of long-term conditions often require information on survival beyond the period of available data. Objectives: This paper aims to identify a robust and reliable method for the extrapolation of overall survival (OS in patients with radioiodine-refractory differentiated thyroid cancer receiving lenvatinib or placebo. Methods: Data from 392 patients (lenvatinib: 261, placebo: 131 from the SELECT trial are used over a 34-month period of follow-up. A previously published criterion-based approach is employed to ascertain credible estimates of OS beyond the trial data. Parametric models with and without a treatment covariate and piecewise models are used to extrapolate OS, and a holistic approach, where a series of statistical and visual tests are considered collectively, is taken in determining the most appropriate extrapolation model. Results: A piecewise model, in which the Kaplan–Meier survivor function is used over the trial period and an extrapolated tail is based on the Exponential distribution, is identified as the optimal model. Conclusion: In the absence of long-term survival estimates from clinical trials, survival estimates often need to be extrapolated from the available data. The use of a systematic method based on a priori determined selection criteria provides a transparent approach and reduces the risk of bias. The extrapolated OS estimates will be used to investigate the potential long-term benefits of lenvatinib in the treatment of radioiodine-refractory differentiated thyroid cancer patients and

Assessment of the disinfection capacity and eco-toxicological impact of atmospheric cold plasma for treatment of food industry effluents.

Science.gov (United States)

Patange, Apurva; Boehm, Daniela; Giltrap, Michelle; Lu, Peng; Cullen, P J; Bourke, Paula

2018-08-01

Generation of wastewater is one of the main environmental sustainability issues across food sector industries. The constituents of food process effluents are often complex and require high energy and processing for regulatory compliance. Wastewater streams are the subject of microbiological and chemical criteria, and can have a significant eco-toxicological impact on the aquatic life. Thus, innovative treatment approaches are required to mitigate environmental impact in an energy efficient manner. Here, dielectric barrier discharge atmospheric cold plasma (ACP) was evaluated for control of key microbial indicators encountered in food industry effluent. This study also investigated the eco-toxicological impact of cold plasma treatment of the effluents using a range of aquatic bioassays. Continuous ACP treatment was applied to synthetic dairy and meat effluents. Microbial inactivation showed treatment time dependence with significant reduction in microbial populations within 120 s, and to undetectable levels after 300 s. Post treatment retention time emerged as critical control parameter which promoted ACP bacterial inactivation efficiency. Moreover, ACP treatment for 20 min achieved significant reduction (≥2 Log 10 ) in Bacillus megaterium endospores in wastewater effluent. Acute aquatic toxicity was assessed using two fish cell lines (PLHC-1 and RTG-2) and a crustacean model (Daphnia magna). Untreated effluents were toxic to the aquatic models, however, plasma treatment limited the toxic effects. Differing sensitivities were observed to ACP treated effluents across the different test bio-assays in the following order: PLHC-1 > RTG-2 ≥ D. magna; with greater sensitivity retained to plasma treated meat effluent than dairy effluent. The toxic effects were dependent on concentration and treatment time of the ACP treated effluent; with 30% cytotoxicity in D. magna and fish cells observed after 24 h of exposure to ACP treated effluent for

A new mini-extrapolation chamber for beta source uniformity measurements

International Nuclear Information System (INIS)

Oliveira, M.L.; Caldas, L.V.E.

2006-01-01

According to recent international recommendations, beta particle sources should be specified in terms of absorbed dose rates to water at the reference point. However, because of the clinical use of these sources, additional information should be supplied in the calibration reports. This additional information include the source uniformity. A new small volume extrapolation chamber was designed and constructed at the Calibration Laboratory at Instituto de Pesquisas Energeticas e Nucleares, IPEN, Brazil, for the calibration of 90 Sr+ 90 Y ophthalmic plaques. This chamber can be used as a primary standard for the calibration of this type of source. Recent additional studies showed the feasibility of the utilization of this chamber to perform source uniformity measurements. Because of the small effective electrode area, it is possible to perform independent measurements by varying the chamber position by small steps. The aim of the present work was to study the uniformity of a 90 Sr+ 90 Y plane ophthalmic plaque utilizing the mini extrapolation chamber developed at IPEN. The uniformity measurements were performed by varying the chamber position by steps of 2 mm in the source central axis (x-and y-directions) and by varying the chamber position off-axis by 3 mm steps. The results obtained showed that this small volume chamber can be used for this purpose with a great advantage: it is a direct method, being unnecessary a previously calibration of the measurement device in relation to a reference instrument, and it provides real -time results, reducing the time necessary for the study and the determination of the uncertainties related to the measurements. (authors)

Implementation of the ecotoxicological, effects module

DEFF Research Database (Denmark)

Larsen, Henrik Fred; Payet, Jerome; Molander, S

pelagic compartment is dealt with here. For about a year discussions have been going on within the ecotox task force established within the OMNIITOX consortium, especially about which estimation principle to chose, i.e. whether it should be no-effect based (PNEC) or effect based (e.g. median or geometric...... mean). As a starting point existing approaches used within LCIA has been described and evaluated. Reports on these two issues (estimation principle and evaluation of existing approaches) are enclosed with this report as possible sources for background information In this report further theoretical...... elaboration of effect based average approaches (arithmetic mean, geometric mean and median) and the non-effect based approach (PNEC, here only as lowest EC50 in the dataset) are done focusing on their statistical robustness and the possibility to relate the effect indicator (based on a measure of effect...

Accurate Conformational Energy Differences of Carbohydrates: A Complete Basis Set Extrapolation

Czech Academy of Sciences Publication Activity Database

Csonka, G. I.; Kaminský, Jakub

2011-01-01

Roč. 7, č. 4 (2011), s. 988-997 ISSN 1549-9618 Institutional research plan: CEZ:AV0Z40550506 Keywords : MP2 * basis set extrapolation * saccharides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.215, year: 2011

Evolutionary ecotoxicology of pesticide resistance: a case study in Daphnia.

Science.gov (United States)

Jansen, Mieke; Coors, Anja; Stoks, Robby; De Meester, Luc

2011-05-01

Natural populations that are exposed to pesticides in their environment may at the same time be exposed to natural stressors like parasites and predators, which may interact with pesticide exposure. This may not only impact target pest species but also a wide variety of non-target species. This review reports on a joint research program in the water flea Daphnia magna, a non-target species often used as model organism in ecology and ecotoxicology. The focus is on different aspects that are of key importance to understand the evolutionary ecology of pesticide exposure: (1) the capacity of natural populations to genetically adapt to pesticide exposure (2) the added complexity of synergistic effects caused by simultaneous exposure to natural stressors, and (3) the potential interference of evolutionary costs of adaptation to pesticide exposure. Our results showed that natural populations were able to rapidly evolve resistance to the pesticide carbaryl but at the expense of fitness costs. Individuals selected for carbaryl resistance had higher survival rates when exposed to the pesticide but also a greater susceptibility to the challenge imposed by the bacterial endoparasite Pasteuria ramosa. The evolved resistance to carbaryl was in some cases only expressed in the absence of fish kairomones. Further, it became clear that the responses to both exposure to single and combined stressors was for several life history variables strongly dependent upon past exposure to carbaryl. This indicates that past exposures to pesticides are important and can not be neglected when evaluating responses to current stressors. © Springer Science+Business Media, LLC 2011

Methodology for the ecotoxicological evaluation of areas polluted by phosphogypsum wastes.

Science.gov (United States)

Martínez-Sanchez, M. J.; Garcia-Lorenzo, M. L.; Perez-Sirvent, C.; Martinez-Lopez, S.; Hernandez-Cordoba, M.; Bech, J.

2012-04-01

In Spain, the production of phosphoric acid, and hence of phosphogypsum, is restricted to a fertilizer industrial site. The residues contain some radionuclides of the U-series and other contaminants. In order to estimate the risk posed by these materials, chemical methods need to be complemented with biological methods. Then, the aim of this study was to develop a battery of bioassays for the ecotoxicological screening of areas polluted by phosphogypsum wastes. Particularly, the toxicity of water samples, sediments and their pore-water extracts was evaluated by using three assays: bacteria, plants and ostracods. The applied bioassays were: the bioluminescence inhibition of Vibrio fischeri in superficial water samples using Microtox® bioassay; the root and shoot elongation inhibition and the mortality of Lepidium sativum, Sorghum saccharatum and Sinapis alba using Phytotoxkit® bioassay; and inhibition of Heterocypris incongruens by way of Ostracodtoxkit®. Proposed methodology allows the identification of contamination sources and non contaminated areas, corresponding to decreasing toxicity values.

Proposal of concentration limits for determining the hazard property HP 14 for waste using ecotoxicological tests.

Science.gov (United States)

Hennebert, Pierre

2018-04-01

Different ecotoxicological test batteries and concentration limits have been proposed to assess the hazard property (HP) HP 14 'Ecotoxic' for waste in the European Union and its member states. In test batteries, if the concentration of waste in the culture/dilution medium producing 50% of inhibitory biological effect in one or more test(s) is below the concentration limit of the test, the waste is classified as hazardous. A summarized review of the test batteries proposed since 1998 is presented. The last proposed test battery uses seven aquatic and terrestrial species with standardized methods, but with options and uniform concentration limits of 10% of waste eluate or solid waste in the culture/dilution medium. No attempt was made to match this hazard assessment with the classification made in the European List of Waste (LoW). The aim of this paper is to propose for the same test battery (reduced to 6 tests without options) concentration limits that match with the European List of Waste. This list was taken as reference (despite the fact that waste can be hazardous for other properties than the most frequent HP 14, and its partly political nature for some opinions). The concentration limits (CLs) for tests are the concentrations producing the highest ecotoxicological effects for each test observed in a non-hazardous waste set. Data from Germany, France and Belgium (from in total 5 different sources from 2009 to 2016) with the above-mentioned test battery (without options) were gathered for 81 samples, being the largest set ever published. In total, ten non-hazardous (NH) waste samples (as defined by the LoW and for most of them checked by chemical composition) were used to establish CLs. These CLs were then applied to 13 hazardous (H) waste by the LoW, and all were classified as hazardous. The matching of the resulting classification with the LoW is convincing. For the 58 'mirror entries' in the LoW (hazardous or not depending of the presence of hazardous

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide.

Science.gov (United States)

Kissling, Wilm Daniel; Dalby, Lars; Fløjgaard, Camilla; Lenoir, Jonathan; Sandel, Brody; Sandom, Christopher; Trøjelsgaard, Kristian; Svenning, Jens-Christian

2014-07-01

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species' evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals ("MammalDIET"). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external

A model compound study: the ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays.

Science.gov (United States)

Macken, Ailbhe; Giltrap, Michelle; Foley, Barry; McGovern, Evin; McHugh, Brendan; Davoren, Maria

2008-06-01

This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone.

{sup 131}I-SPGP internal dosimetry: animal model and human extrapolation

Energy Technology Data Exchange (ETDEWEB)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soprani, Juliana; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br; Figueiredo, Suely Gomes de [Universidade Federal do Espirito Santo, (UFES), Vitoria, ES (Brazil). Dept. de Ciencias Fisiologicas. Lab. de Quimica de Proteinas

2009-07-01

Scorpaena plumieri is commonly called moreia-ati or manganga and is the most venomous and one of the most abundant fish species of the Brazilian coast. Soprani 2006, demonstrated that SPGP - an isolated protein from S. plumieri fish- possess high antitumoral activity against malignant tumours and can be a source of template molecules for the development (design) of antitumoral drugs. In the present work, Soprani's {sup 125}ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the {sup 131}I-SPGP uptake were determinate in several organs of mice, as well as in the implanted tumor. Doses obtained for animal model were extrapolated to humans assuming a similar ratio for various mouse and human tissues. For the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 131}I were considered. (author)

Guided wave tomography in anisotropic media using recursive extrapolation operators

Science.gov (United States)

Volker, Arno

2018-04-01

Guided wave tomography is an advanced technology for quantitative wall thickness mapping to image wall loss due to corrosion or erosion. An inversion approach is used to match the measured phase (time) at a specific frequency to a model. The accuracy of the model determines the sizing accuracy. Particularly for seam welded pipes there is a measurable amount of anisotropy. Moreover, for small defects a ray-tracing based modelling approach is no longer accurate. Both issues are solved by applying a recursive wave field extrapolation operator assuming vertical transverse anisotropy. The inversion scheme is extended by not only estimating the wall loss profile but also the anisotropy, local material changes and transducer ring alignment errors. This makes the approach more robust. The approach will be demonstrated experimentally on different defect sizes, and a comparison will be made between this new approach and an isotropic ray-tracing approach. An example is given in Fig. 1 for a 75 mm wide, 5 mm deep defect. The wave field extrapolation based tomography clearly provides superior results.

Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview

Directory of Open Access Journals (Sweden)

Kaja Kasemets

2008-08-01

Full Text Available Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles.

The influence of an extrapolation chamber over the low energy X-ray beam radiation field

Energy Technology Data Exchange (ETDEWEB)

Tanuri de F, M. T.; Da Silva, T. A., E-mail: mttf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

The extrapolation chambers are detectors whose sensitive volume can be modified by changing the distance between the electrodes and has been widely used for beta particles primary measurement system. In this work, was performed a PTW 23392 extrapolation chamber Monte Carlo simulation, by mean the MCNPX code. Although the sensitive volume of an extrapolation chamber can be reduced to very small size, their packaging is large enough to modify the radiation field and change the absorbed dose measurements values. Experiments were performed to calculate correction factors for this purpose. The validation of the Monte Carlo model was done by comparing the spectra obtained with a CdTe detector according to the ISO 4037 criteria. Agreements smaller than 5% for half value layers, 10% for spectral resolution and 1% for mean energy, were found. It was verified that the correction factors are dependent of the X-ray beam quality. (Author)

The influence of an extrapolation chamber over the low energy X-ray beam radiation field

International Nuclear Information System (INIS)

Tanuri de F, M. T.; Da Silva, T. A.

2016-10-01

The extrapolation chambers are detectors whose sensitive volume can be modified by changing the distance between the electrodes and has been widely used for beta particles primary measurement system. In this work, was performed a PTW 23392 extrapolation chamber Monte Carlo simulation, by mean the MCNPX code. Although the sensitive volume of an extrapolation chamber can be reduced to very small size, their packaging is large enough to modify the radiation field and change the absorbed dose measurements values. Experiments were performed to calculate correction factors for this purpose. The validation of the Monte Carlo model was done by comparing the spectra obtained with a CdTe detector according to the ISO 4037 criteria. Agreements smaller than 5% for half value layers, 10% for spectral resolution and 1% for mean energy, were found. It was verified that the correction factors are dependent of the X-ray beam quality. (Author)

Spatial and temporal behavior and acute ecotoxicological effects of Tributyltin (TBT) on coral reef and adjacent ecosystems around Okinawa Island, Japan.

Science.gov (United States)

Sheikh, M. A.; Higuchi, T.; Imo, T. S.; Fujimura, H.; Oomori, T.

2007-12-01

Spatial and temporal behavior of the tributyl tin (TBT) were investigated in the coastal areas around Okinawa Island, Japan. A seasonal monitoring study was conducted between February and October 2006. The effects of TBT on the carbon metabolisms (net production and calcification) on the intact coral-alga association Galaxea fascicularis were also investigated. Mean concentration of TBT (2.45 ng/L) found in the Manko estuary waters have exceeded some international permissible targets of waters quality guideline for TBT (1ng/L). The sediments in Manko estuary sediments can be considered lightly contaminated (0-20 ng/g dw) and Okukubi estuary as uncontaminated (below 3ng/g dw) with TBT. The seasonal concentration pattern of TBT at the Manko estuary was autumn > spring > summer > winter. The acute ecotoxicological results show that the photosynthesis rate and calcification rate were significantly reduced by 78 % and 72 % relative to the control (ANOVA, p0.05) were observed when corals were exposed to 1000 ng/LTBT. The present study reports the occurrence and continuous input of TBT in the coastal areas around Okinawa Island, even 16 years after legal restriction of TBT usage in coastal waters was implemented by the Japanese Environmental Authorities. However, the nominal sensitive concentration of TBT that causes alteration of carbon metabolisms of coral within 96 hrs exposure are much higher than those recently found in the coral reef waters and adjacent ecosystems.

Toxicological and ecotoxicological risk-based prioritization of pharmaceuticals in the natural environment.

Science.gov (United States)

Guo, Jiahua; Sinclair, Chris J; Selby, Katherine; Boxall, Alistair B A

2016-06-01

Approximately 1500 active pharmaceutical ingredients are currently in use; however, the environmental occurrence and impacts of only a small proportion of these have been investigated. Recognizing that it would be impractical to monitor and assess all pharmaceuticals that are in use, several previous studies have proposed the use of prioritization approaches to identify substances of most concern so that resources can be focused on these. All of these previous approaches suffer from limitations. In the present study, the authors draw on experience from previous prioritization exercises and present a holistic approach for prioritizing pharmaceuticals in the environment in terms of risks to aquatic and soil organisms, avian and mammalian wildlife, and humans. The approach considers both apical ecotoxicological endpoints as well as potential nonapical effects related to the therapeutic mode of action. Application of the approach is illustrated for 146 active pharmaceuticals that are used either in the community or in hospital settings in the United Kingdom. Using the approach, 16 compounds were identified as a potential priority. These substances include compounds belonging to the antibiotic, antidepressant, anti-inflammatory, antidiabetic, antiobesity, and estrogen classes as well as associated metabolites. In the future, the prioritization approach should be applied more broadly around the different regions of the world. Environ Toxicol Chem 2016;35:1550-1559. © 2016 SETAC. © 2016 SETAC.

Ecotoxicological assessment of metal-polluted urban soils using bioassays with three soil invertebrates.

Science.gov (United States)

Santorufo, Lucia; Van Gestel, Cornelis A M; Maisto, Giulia

2012-07-01

This study aimed at assessing the quality of urban soils by integrating chemical and ecotoxicological approaches. Soils from five sites in downtown Naples, Italy, were sampled and characterized for physical-chemical properties and total and water-extractable metal concentrations. Bioassays with Eisenia andrei, Enchytraeus crypticus and Folsomia candida were performed to assess toxicity of the soils, using survival, reproduction and growth as the endpoints. Metal bioaccumulation in the animals was also measured. The properties and metal concentrations of the soils strongly differed. Metal bioaccumulation was related with total metal concentrations in soil and was highest in E. crypticus, which was more sensitive than E. andrei and F. candida. Responses of the three species to the investigated soils seemed due to both metal contamination and soil properties. Copyright © 2012 Elsevier Ltd. All rights reserved.

Making the most of what we have: application of extrapolation approaches in radioecological wildlife transfer models

International Nuclear Information System (INIS)

Beresford, Nicholas A.; Wood, Michael D.; Vives i Batlle, Jordi; Yankovich, Tamara L.; Bradshaw, Clare; Willey, Neil

2016-01-01

We will never have data to populate all of the potential radioecological modelling parameters required for wildlife assessments. Therefore, we need robust extrapolation approaches which allow us to make best use of our available knowledge. This paper reviews and, in some cases, develops, tests and validates some of the suggested extrapolation approaches. The concentration ratio (CR_p_r_o_d_u_c_t_-_d_i_e_t or CR_w_o_-_d_i_e_t) is shown to be a generic (trans-species) parameter which should enable the more abundant data for farm animals to be applied to wild species. An allometric model for predicting the biological half-life of radionuclides in vertebrates is further tested and generally shown to perform acceptably. However, to fully exploit allometry we need to understand why some elements do not scale to expected values. For aquatic ecosystems, the relationship between log_1_0(a) (a parameter from the allometric relationship for the organism-water concentration ratio) and log(K_d) presents a potential opportunity to estimate concentration ratios using K_d values. An alternative approach to the CR_w_o_-_m_e_d_i_a model proposed for estimating the transfer of radionuclides to freshwater fish is used to satisfactorily predict activity concentrations in fish of different species from three lakes. We recommend that this approach (REML modelling) be further investigated and developed for other radionuclides and across a wider range of organisms and ecosystems. Ecological stoichiometry shows potential as an extrapolation method in radioecology, either from one element to another or from one species to another. Although some of the approaches considered require further development and testing, we demonstrate the potential to significantly improve predictions of radionuclide transfer to wildlife by making better use of available data. - Highlights: • Robust extrapolation approaches allowing best use of available knowledge are needed. • Extrapolation approaches are

Comparison of precipitation nowcasting by extrapolation and statistical-advection methods

Czech Academy of Sciences Publication Activity Database

Sokol, Zbyněk; Kitzmiller, D.; Pešice, Petr; Mejsnar, Jan

2013-01-01

Roč. 123, 1 April (2013), s. 17-30 ISSN 0169-8095 R&D Projects: GA MŠk ME09033 Institutional support: RVO:68378289 Keywords : Precipitation forecast * Statistical models * Regression * Quantitative precipitation forecast * Extrapolation forecast Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.421, year: 2013 http://www.sciencedirect.com/science/article/pii/S0169809512003390

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M., E-mail: danellelarson77@gmail.com

2017-04-15

Highlights: • Sucralose increased leaf area and photosynthetic capacity of Lemna minor. • Sucralose increased δ {sup 13}C of Lemna, indicating substantial uptake and assimilation. • 100 μg/L-fluoxetine decreased Lemna minor growth and asexual reproduction. - Abstract: Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ{sup 13}C) were measured among treatments ranging from 0 to 15000 nmol/L-sucralose and 0–323 nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ {sup 13}C of L. minor at environmentally relevant concentrations. The increase of δ {sup 13}C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor—a mixotrophic plant—can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor

International Nuclear Information System (INIS)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M.

2017-01-01

Highlights: • Sucralose increased leaf area and photosynthetic capacity of Lemna minor. • Sucralose increased δ "1"3C of Lemna, indicating substantial uptake and assimilation. • 100 μg/L-fluoxetine decreased Lemna minor growth and asexual reproduction. - Abstract: Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ"1"3C) were measured among treatments ranging from 0 to 15000 nmol/L-sucralose and 0–323 nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ "1"3C of L. minor at environmentally relevant concentrations. The increase of δ "1"3C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor—a mixotrophic plant—can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine significantly

Performance of an extrapolation chamber in computed tomography standard beams

International Nuclear Information System (INIS)

Castro, Maysa C.; Silva, Natália F.; Caldas, Linda V.E.

2017-01-01

Among the medical uses of ionizing radiations, the computed tomography (CT) diagnostic exams are responsible for the highest dose values to the patients. The dosimetry procedure in CT scanner beams makes use of pencil ionization chambers with sensitive volume lengths of 10 cm. The aim of its calibration is to compare the values that are obtained with the instrument to be calibrated and a standard reference system. However, there is no primary standard system for this kind of radiation beam. Therefore, an extrapolation ionization chamber built at the Calibration Laboratory (LCI), was used to establish a CT primary standard. The objective of this work was to perform some characterization tests (short- and medium-term stabilities, saturation curve, polarity effect and ion collection efficiency) in the standard X-rays beams established for computed tomography at the LCI. (author)

Performance of an extrapolation chamber in computed tomography standard beams

Energy Technology Data Exchange (ETDEWEB)

Castro, Maysa C.; Silva, Natália F.; Caldas, Linda V.E., E-mail: mcastro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2017-07-01

Among the medical uses of ionizing radiations, the computed tomography (CT) diagnostic exams are responsible for the highest dose values to the patients. The dosimetry procedure in CT scanner beams makes use of pencil ionization chambers with sensitive volume lengths of 10 cm. The aim of its calibration is to compare the values that are obtained with the instrument to be calibrated and a standard reference system. However, there is no primary standard system for this kind of radiation beam. Therefore, an extrapolation ionization chamber built at the Calibration Laboratory (LCI), was used to establish a CT primary standard. The objective of this work was to perform some characterization tests (short- and medium-term stabilities, saturation curve, polarity effect and ion collection efficiency) in the standard X-rays beams established for computed tomography at the LCI. (author)

Improving in vitro to in vivo extrapolation by incorporating toxicokinetic measurements: A case study of lindane-induced neurotoxicity

Energy Technology Data Exchange (ETDEWEB)

Croom, Edward L.; Shafer, Timothy J.; Evans, Marina V.; Mundy, William R.; Eklund, Chris R.; Johnstone, Andrew F.M.; Mack, Cina M.; Pegram, Rex A., E-mail: pegram.rex@epa.gov

2015-02-15

Approaches for extrapolating in vitro toxicity testing results for prediction of human in vivo outcomes are needed. The purpose of this case study was to employ in vitro toxicokinetics and PBPK modeling to perform in vitro to in vivo extrapolation (IVIVE) of lindane neurotoxicity. Lindane cell and media concentrations in vitro, together with in vitro concentration-response data for lindane effects on neuronal network firing rates, were compared to in vivo data and model simulations as an exercise in extrapolation for chemical-induced neurotoxicity in rodents and humans. Time- and concentration-dependent lindane dosimetry was determined in primary cultures of rat cortical neurons in vitro using “faux” (without electrodes) microelectrode arrays (MEAs). In vivo data were derived from literature values, and physiologically based pharmacokinetic (PBPK) modeling was used to extrapolate from rat to human. The previously determined EC{sub 50} for increased firing rates in primary cultures of cortical neurons was 0.6 μg/ml. Media and cell lindane concentrations at the EC{sub 50} were 0.4 μg/ml and 7.1 μg/ml, respectively, and cellular lindane accumulation was time- and concentration-dependent. Rat blood and brain lindane levels during seizures were 1.7–1.9 μg/ml and 5–11 μg/ml, respectively. Brain lindane levels associated with seizures in rats and those predicted for humans (average = 7 μg/ml) by PBPK modeling were very similar to in vitro concentrations detected in cortical cells at the EC{sub 50} dose. PBPK model predictions matched literature data and timing. These findings indicate that in vitro MEA results are predictive of in vivo responses to lindane and demonstrate a successful modeling approach for IVIVE of rat and human neurotoxicity. - Highlights: • In vitro to in vivo extrapolation for lindane neurotoxicity was performed. • Dosimetry of lindane in a micro-electrode array (MEA) test system was assessed. • Cell concentrations at the MEA EC

{sup 131}I-CRTX internal dosimetry: animal model and human extrapolation

Energy Technology Data Exchange (ETDEWEB)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soares, Marcella Araugio; Silveira, Marina Bicalho; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br

2009-07-01

Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. {sup 125}I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, {sup 125}I-Crtx biokinetic data (evaluated in mice bearing Erlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for {sup 131}I-Crtx. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 131}I in the tissue were considered in dose calculations. (author)

Design and construction of an interface system for the extrapolation chamber from the beta secondary standard.; Diseno y construccion del sistema de interfaz para la camara de extrapolacion del patron secundario beta.

Energy Technology Data Exchange (ETDEWEB)

Jimenez C, L F

1995-10-01

The Interface System for the Extrapolation Chamber (SICE) contains several devices handled by a personal computer (PC), it is able to get the required data to calculate the absorbed dose due to Beta radiation. The main functions of the system are: (a) Measures the ionization current or charge stored in the extrapolation chamber. (b) Adjusts the distance between the plates of the extrapolation chamber automatically. (c) Adjust the bias voltage of the extrapolation chamber automatically. (d) Acquires the data of the temperature, atmospheric pressure, relative humidity of the environment and the voltage applied between the plates of the extrapolation chamber. (e) Calculates the effective area of the plates of the extrapolation chamber and the real distance between them. (f) Stores all the obtained information in hard disk or diskette. A comparison between the desired distance and the distance in the dial of the extrapolation chamber, show us that the resolution of the system is of 20 {mu}m. The voltage can be changed between -399.9 V and +399.9 V with an error of less the 3% with a resolution of 0.1 V. These uncertainties are between the accepted limits to be used in the determination of the absolute absorbed dose due to beta radiation. (Author).

Ecological and ecotoxicological responses in the assessment of the ecological status of freshwater systems: A case-study of the temporary stream Brejo of Cagarrão (South of Portugal).

Science.gov (United States)

Palma, P; Matos, C; Alvarenga, P; Köck-Schulmeyer, M; Simões, I; Barceló, D; López de Alda, M J

2018-09-01

The objective of the study was to assess the integrated use of macroinvertebrate indexes and ecotoxicological parameters in the evaluation of the ecological status of a temporary stream with a strong agricultural influence. Water quality was analysed at two sampling sites along the stream, considering: chemical supporting parameters; hazardous substances (pesticides); benthic macroinvertebrate communities, through quality (Iberian Biological Monitoring Working Party and Iberian Average Score Per Taxon) and multi-metric indices (Southern Portuguese Index of Invertebrates and Ecological Quality Ratio); and ecotoxicological responses using lethal and sub-lethal bioassays. The water chemical characterization showed high levels of organic matter and nutrients, mainly in the dry period ((biochemical oxygen demand (BOD 5 ): 18.5-25.5mgL -1 , chemical oxygen demand (COD): 60.8-193.7mgL -1 ; total phosphorus (TP): 0.17-0.33mgL -1 )), which may compromise the support of biological life. In accordance with the physicochemical results, the stream had an ecological status less than good. Of the 25 pesticides analysed, only five, namely terbuthylazine, 2-methyl-chlorophenoxyacetic acid, bentazone, mecoprop and metolachlor were quantified. In general, the concentrations of pesticides detected were low, except at the source of the stream in January 2012 (sum of pesticides 2.29μgL -1 ), mainly due to the concentration of bentazone (1.77μgL -1 ), both values surpassing the European Commission threshold values. The analysis of benthic macroinvertebrates showed low levels of abundance and family diversity, with communities dominated by resistant groups to organic pollution and pesticides, such as the Chironomidae family. In general, the reproduction ecotoxicological results showed a very marked decrease in the number of juveniles per female. The Spearman correlation identified pesticides, namely MCPA (R=-0.89; p<0.05), as the main responsible for the observed effect. The results

Comparison of solid-phase and eluate assays to gauge the ecotoxicological risk of organic wastes on soil organisms

International Nuclear Information System (INIS)

Domene, Xavier; Alcaniz, Josep M.; Andres, Pilar

2008-01-01

Development of methodologies to assess the safety of reusing polluted organic wastes in soil is a priority in Europe. In this study, and coupled with chemical analysis, seven organic wastes were subjected to different aquatic and soil bioassays. Tests were carried out with solid-phase waste and three different waste eluates (water, methanol, and dichloromethane). Solid-phase assays were indicated as the most suitable for waste testing not only in terms of relevance for real situations, but also because toxicity in eluates was generally not representative of the chronic effects in solid-phase. No general correlations were found between toxicity and waste pollutant burden, neither in solid-phase nor in eluate assays, showing the inability of chemical methods to predict the ecotoxicological risks of wastes. On the contrary, several physicochemical parameters reflecting the degree of low organic matter stability in wastes were the main contributors to the acute toxicity seen in collembolans and daphnids. - Comparison of solid-phase and eluate bioassays for organic waste testing

Uptake of propranolol, a cardiovascular pharmaceutical, from water into fish plasma and its effects on growth and organ biometry

Energy Technology Data Exchange (ETDEWEB)

Owen, Stewart F. [Institute for the Environment, Brunel University, Uxbridge, Middlesex, UB8 3PH (United Kingdom); Global Safety Health and Environment, AstraZeneca, Brixham Environmental Laboratory, Freshwater Quarry, Brixham, Devon, TQ5 8BA (United Kingdom); Huggett, Duane B. [Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT 06340 (United States); Hutchinson, Thomas H.; Hetheridge, Malcolm J. [Global Safety Health and Environment, AstraZeneca, Brixham Environmental Laboratory, Freshwater Quarry, Brixham, Devon, TQ5 8BA (United Kingdom); Kinter, Lewis B. [AstraZeneca Pharmaceuticals US, 1800 Concord Pike, Wilmington, DE 19850 (United States); Ericson, Jon. F. [Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT 06340 (United States); Sumpter, John P., E-mail: john.sumpter@brunel.ac.uk [Institute for the Environment, Brunel University, Uxbridge, Middlesex, UB8 3PH (United Kingdom)

2009-07-26

Pharmaceuticals in the environment (PIE) are of importance since these compounds are designed to affect biological receptors/enzymes that are often conserved across vertebrate families. Across-species extrapolation of these therapeutic targets suggests potential for impacting amphibia and fish in the aquatic environment. Due to the scarcity of relevant ecotoxicological data, the long-tem impact of PIE remains a research question. Efficient use of mammalian data has been proposed to better understand and predict the potential for a given pharmaceutical to impact the environment. Using a model cardiovascular pharmaceutical (propranolol, a non-specific {beta}{sub 1}/{beta}{sub 2}-adrenergic antagonist), the hypothesis that mammalian data can be used to predict toxicity in fish was tested. Rainbow trout (Oncorhynchus mykiss (Walbaum)) have {beta}-adrenergic signalling mechanisms analogous to human cardiovascular receptors that respond to pharmacological doses of agonists and antagonists. Trout absorbed propranolol from water such that after 40 days of exposure, the linear relationship was [plasma] = 0.59[water] (n = 31, r = 0.96). Growth rate was affected only at very high aqueous concentrations (10-day {sup growth}NOEC = 1.0 and {sup growth}LOEC = 10 mg/l). Growth recovered with time (40-day {sup growth}NOEC = 10 mg/l), suggesting possible adaptation to the pharmaceutical, although the internal plasma concentration in trout exposed to 10 mg propranolol/l of water was higher than the mammalian therapeutic plasma concentration. Additional endpoints suggested subtle changes of liver and heart size at much lower concentrations may have occurred, although these were not concentration-related. There was, however, a dose-dependent effect upon overall body condition. The trout plasma concentrations at these effective aqueous concentrations fell within the range of mammalian effective plasma concentrations, supporting the potential for developing 'read-across' from

Uptake of propranolol, a cardiovascular pharmaceutical, from water into fish plasma and its effects on growth and organ biometry

International Nuclear Information System (INIS)

Owen, Stewart F.; Huggett, Duane B.; Hutchinson, Thomas H.; Hetheridge, Malcolm J.; Kinter, Lewis B.; Ericson, Jon. F.; Sumpter, John P.

2009-01-01

Pharmaceuticals in the environment (PIE) are of importance since these compounds are designed to affect biological receptors/enzymes that are often conserved across vertebrate families. Across-species extrapolation of these therapeutic targets suggests potential for impacting amphibia and fish in the aquatic environment. Due to the scarcity of relevant ecotoxicological data, the long-tem impact of PIE remains a research question. Efficient use of mammalian data has been proposed to better understand and predict the potential for a given pharmaceutical to impact the environment. Using a model cardiovascular pharmaceutical (propranolol, a non-specific β 1 /β 2 -adrenergic antagonist), the hypothesis that mammalian data can be used to predict toxicity in fish was tested. Rainbow trout (Oncorhynchus mykiss (Walbaum)) have β-adrenergic signalling mechanisms analogous to human cardiovascular receptors that respond to pharmacological doses of agonists and antagonists. Trout absorbed propranolol from water such that after 40 days of exposure, the linear relationship was [plasma] = 0.59[water] (n = 31, r = 0.96). Growth rate was affected only at very high aqueous concentrations (10-day growth NOEC = 1.0 and growth LOEC = 10 mg/l). Growth recovered with time (40-day growth NOEC = 10 mg/l), suggesting possible adaptation to the pharmaceutical, although the internal plasma concentration in trout exposed to 10 mg propranolol/l of water was higher than the mammalian therapeutic plasma concentration. Additional endpoints suggested subtle changes of liver and heart size at much lower concentrations may have occurred, although these were not concentration-related. There was, however, a dose-dependent effect upon overall body condition. The trout plasma concentrations at these effective aqueous concentrations fell within the range of mammalian effective plasma concentrations, supporting the potential for developing 'read-across' from mammalian pharmacology safety data to fish

Assessing sediment hazard through a weight of evidence approach with bioindicator organisms: a practical model to elaborate data from sediment chemistry, bioavailability, biomarkers and ecotoxicological bioassays.

Science.gov (United States)

Piva, Francesco; Ciaprini, Francesco; Onorati, Fulvio; Benedetti, Maura; Fattorini, Daniele; Ausili, Antonella; Regoli, Francesco

2011-04-01

Quality assessments are crucial to all activities related to removal and management of sediments. Following a multidisciplinary, weight of evidence approach, a new model is presented here for comprehensive assessment of hazards associated to polluted sediments. The lines of evidence considered were sediment chemistry, assessment of bioavailability, sub-lethal effects on biomarkers, and ecotoxicological bioassays. A conceptual and software-assisted model was developed with logical flow-charts elaborating results from each line of evidence on the basis of several chemical and biological parameters, normative guidelines or scientific evidence; the data are thus summarized into four specific synthetic indices, before their integration into an overall sediment hazard evaluation. This model was validated using European eels (Anguilla anguilla) as the bioindicator species, exposed under laboratory conditions to sediments from an industrial site, and caged under field conditions in two harbour areas. The concentrations of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons and trace metals were much higher in the industrial compared to harbour sediments, and accordingly the bioaccumulation in liver and gills of exposed eels showed marked differences between conditions seen. Among biomarkers, significant variations were observed for cytochrome P450-related responses, oxidative stress biomarkers, lysosomal stability and genotoxic effects; the overall elaboration of these data, as those of standard ecotoxicological bioassays with bacteria, algae and copepods, confirmed a higher level of biological hazard for industrial sediments. Based on comparisons with expert judgment, the model presented efficiently discriminates between the various conditions, both as individual modules and as an integrated final evaluation, and it appears to be a powerful tool to support more complex processes of environmental risk assessment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Modeling response of species to microcontaminants: comparative ecotoxicology by (sub)lethal body burdens as a function of species size and partition ratio of chemicals.

Science.gov (United States)

Hendriks, A J

1995-11-01

A model was designed and calibrated with accumulation data to calculate the internal concentrations of microcontaminants in organisms as a function of a few constants and variables. The main factors are the exposure time, the external exposure concentration, the partition ratio of the compound, and the size of the taxon concerned. The model was applied to calculate the lethal and sublethal body burdens of several priority compounds and some major taxa. Estimations were generally confirmed at the order of magnitude level by measured residues and applied doses if available. According to the estimations, most priority compounds chosen were critical for most taxa above internal concentrations of 0.1 mmol.kg-1 wet wt. Trichloromethane, 1,2,4-trichlorobenzene, and hexachlorobenzene were lethal above this level only, whereas other organic microcontaminants affected at least some taxa at lower body burdens. The log(Kow) of the organic compounds ranged from 2.0 to 7.0. Keeping in mind that bioconcentration and -magnification ratios for metals may be quite variable, the lowest critical residues estimated were just below the value of 0.1 mmol.kg-1 wet wt. Here, external concentrations encountered in natural habitats seem to be a promising tool for predictive comparative ecotoxicology. The critical body burdens for plants and invertebrates may have been overestimated due to uncertainty about the parameters. Among the different taxa, however, the fish families chosen (Salmonidae and Cyprinidae) seem to be most sensitive to most compounds. Internal response concentrations of the herbicide atrazine were the lowest in micro- and macrophytes, whereas parathion affected invertebrates at low levels. The database that provided the external response concentrations was also consulted to estimate so-called extrapolation or safety factors. On average, long-term no effect concentrations in water are estimated to be about 10-30 times below short-term median lethal levels. In general, short

Ecotoxicological screen of Potential Release Site 50-006(d) of Operable Unit 1147 of Mortandad Canyon and relationship to the Radioactive Liquid Waste Treatment Facilities project

International Nuclear Information System (INIS)

Gonzales, G.J.; Newell, P.G.

1996-04-01

Potential ecological risk associated with soil contaminants in Potential Release Site (PRS) 50-006(d) of Mortandad Canyon at the Los Alamos National Laboratory was assessed by performing an ecotoxicological risk screen. The PRS surrounds Outfall 051, which discharges treated effluent from the Radioactive Liquid Waste Treatment Facility. Discharge at the outfall is permitted under the Clean Water Act National Pollution Discharge Elimination System. Radionuclide discharge is regulated by US Department of Energy (DOE) Order 5400.5. Ecotoxicological Screening Action Levels (ESALSs) were computed for nonradionuclide constituents in the soil, and human risk SALs for radionuclides were used as ESALs. Within the PRS and beginning at Outfall 051, soil was sampled at three points along each of nine linear transects at 100-ft intervals. Soil samples from 3 depths for each sampling point were analyzed for the concentration of a total of 121 constituents. Only the results of the surface sampling are reported in this report

Testing an extrapolation chamber in computed tomography standard beams

Science.gov (United States)

Castro, M. C.; Silva, N. F.; Caldas, L. V. E.

2018-03-01

The computed tomography (CT) is responsible for the highest dose values to the patients. Therefore, the radiation doses in this procedure must be accurate. However, there is no primary standard system for this kind of radiation beam yet. In order to search for a CT primary standard, an extrapolation ionization chamber built at the Calibration Laboratory (LCI) of the Instituto de Pesquisas Energéticas e Nucleares (IPEN), was tested in this work. The results showed to be within the international recommended limits.

Analysis of the Elodea nuttallii transcriptome in response to mercury and cadmium pollution: development of sensitive tools for rapid ecotoxicological testing.

Science.gov (United States)

Regier, Nicole; Baerlocher, Loïc; Münsterkötter, Martin; Farinelli, Laurent; Cosio, Claudia

2013-08-06

Toxic metals polluting aquatic ecosystems are taken up by inhabitants and accumulate in the food web, affecting species at all trophic levels. It is therefore important to have good tools to assess the level of risk represented by toxic metals in the environment. Macrophytes are potential organisms for the identification of metal-responsive biomarkers but are still underrepresented in ecotoxicology. In the present study, we used next-generation sequencing to investigate the transcriptomic response of Elodea nuttallii exposed to enhanced concentrations of Hg and Cd. We de novo assembled more than 60 000 contigs, of which we found 170 to be regulated dose-dependently by Hg and 212 by Cd. Functional analysis showed that these genes were notably related to energy and metal homeostasis. Expression analysis using nCounter of a subset of genes showed that the gene expression pattern was able to assess toxic metal exposure in complex environmental samples and was more sensitive than other end points (e.g., bioaccumulation, photosynthesis, etc.). In conclusion, we demonstrate the feasibility of using gene expression signatures for the assessment of environmental contamination, using an organism without previous genetic information. This is of interest to ecotoxicology in a wider sense given the possibility to develop specific and sensitive bioassays.

Failure of the straight-line DCS boundary when extrapolated to the hypobaric realm.

Science.gov (United States)

Conkin, J; Van Liew, H D

1992-11-01

The lowest pressure (P2) to which a diver can ascend without developing decompression sickness (DCS) after becoming equilibrated at some higher pressure (P1) is described by a straight line with a negative y-intercept. We tested whether extrapolation of such a line also predicts safe decompression to altitude. We substituted tissue nitrogen pressure (P1N2) calculated for a compartment with a 360-min half-time for P1 values; this allows data from hypobaric exposures to be plotted on a P2 vs. P1N2 graph, even if the subject breathes oxygen before ascent. In literature sources, we found 40 reports of human exposures in hypobaric chambers that fell in the region of a P2 vs. P1N2 plot where the extrapolation from hyperbaric data predicted that the decompression should be free of DCS. Of 4,576 exposures, 785 persons suffered decompression sickness (17%), indicating that extrapolation of the diver line to altitude is not valid. Over the pressure range spanned by human hypobaric exposures and hyperbaric air exposures, the best separation between no DCS and DCS on a P2 vs. P1N2 plot seems to be a curve which approximates a straight line in the hyperbaric region but bends toward the origin in the hypobaric region.

Combining extrapolation with ghost interaction correction in range-separated ensemble density functional theory for excited states

Science.gov (United States)

Alam, Md. Mehboob; Deur, Killian; Knecht, Stefan; Fromager, Emmanuel

2017-11-01

The extrapolation technique of Savin [J. Chem. Phys. 140, 18A509 (2014)], which was initially applied to range-separated ground-state-density-functional Hamiltonians, is adapted in this work to ghost-interaction-corrected (GIC) range-separated ensemble density-functional theory (eDFT) for excited states. While standard extrapolations rely on energies that decay as μ-2 in the large range-separation-parameter μ limit, we show analytically that (approximate) range-separated GIC ensemble energies converge more rapidly (as μ-3) towards their pure wavefunction theory values (μ → +∞ limit), thus requiring a different extrapolation correction. The purpose of such a correction is to further improve on the convergence and, consequently, to obtain more accurate excitation energies for a finite (and, in practice, relatively small) μ value. As a proof of concept, we apply the extrapolation method to He and small molecular systems (viz., H2, HeH+, and LiH), thus considering different types of excitations such as Rydberg, charge transfer, and double excitations. Potential energy profiles of the first three and four singlet Σ+ excitation energies in HeH+ and H2, respectively, are studied with a particular focus on avoided crossings for the latter. Finally, the extraction of individual state energies from the ensemble energy is discussed in the context of range-separated eDFT, as a perspective.

Free magnetic energy and relative magnetic helicity diagnostics for the quality of NLFF field extrapolations

Science.gov (United States)

Moraitis, Kostas; Archontis, Vasilis; Tziotziou, Konstantinos; Georgoulis, Manolis K.

We calculate the instantaneous free magnetic energy and relative magnetic helicity of solar active regions using two independent approaches: a) a non-linear force-free (NLFF) method that requires only a single photospheric vector magnetogram, and b) well known semi-analytical formulas that require the full three-dimensional (3D) magnetic field structure. The 3D field is obtained either from MHD simulations, or from observed magnetograms via respective NLFF field extrapolations. We find qualitative agreement between the two methods and, quantitatively, a discrepancy not exceeding a factor of 4. The comparison of the two methods reveals, as a byproduct, two independent tests for the quality of a given force-free field extrapolation. We find that not all extrapolations manage to achieve the force-free condition in a valid, divergence-free, magnetic configuration. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales. Investing in knowledge society through the European Social Fund.

A comparative approach using ecotoxicological methods from single-species bioassays to model ecosystems.

Science.gov (United States)

Haegerbaeumer, Arne; Höss, Sebastian; Ristau, Kai; Claus, Evelyn; Möhlenkamp, Christel; Heininger, Peter; Traunspurger, Walter

2016-12-01

Soft sediments are often hotspots of chemical contamination, and a thorough ecotoxicological assessment of this habitat can help to identify the causes of stress and to improve the health of the respective ecosystems. As an important component of the ecologically relevant meiobenthic fauna, nematodes can be used for sediment assessments, with various assay tools ranging from single-species toxicity tests to field studies. In the present study, microcosms containing sediment were used to investigate direct and indirect effects of zinc on natural nematode assemblages, and acute community toxicity tests considering only direct toxicity were conducted. The responses of the various freshwater nematode species in both approaches were compared with those of Caenorhabditis elegans, determined in standardized tests (ISO 10872). At a median lethal concentration (LC50) of 20 mg Zn/L, C. elegans represented the median susceptibility of 15 examined nematode species examined in the acute community toxicity tests. In the microcosms, Zn affected the nematodes dose-dependently, with changes in species composition first detected at 13 mg Zn/kg to 19 mg Zn/kg sediment dry weight. The observed species sensitivities in the microcosms corresponded better to field observations than to the results of the acute community toxicity tests. Environ Toxicol Chem 2016;35:2987-2997. © 2016 SETAC. © 2016 SETAC.

Edge database analysis for extrapolation to ITER

International Nuclear Information System (INIS)

Shimada, M.; Janeschitz, G.; Stambaugh, R.D.

1999-01-01

An edge database has been archived to facilitate cross-machine comparisons of SOL and edge pedestal characteristics, and to enable comparison with theoretical models with an aim to extrapolate to ITER. The SOL decay lengths of power, density and temperature become broader for increasing density and q 95 . The power decay length is predicted to be 1.4-3.5 cm (L-mode) and 1.4-2.7 cm (H-mode) at the midplane in ITER. Analysis of Type I ELMs suggests that each giant ELM on ITER would exceed the ablation threshold of the divertor plates. Theoretical models are proposed for the H-mode transition, for Type I and Type III ELMs and are compared with the edge pedestal database. (author)

A method of creep rupture data extrapolation based on physical processes

International Nuclear Information System (INIS)

Leinster, M.G.

2008-01-01

There is a need for a reliable method to extrapolate generic creep rupture data to failure times in excess of the currently published times. A method based on well-understood and mathematically described physical processes is likely to be stable and reliable. Creep process descriptions have been developed based on accepted theory, to the extent that good fits with published data have been obtained. Methods have been developed to apply these descriptions to extrapolate creep rupture data to stresses below the published values. The relationship creep life parameter=f(ln(sinh(stress))) has been shown to be justifiable over the stress ranges of most interest, and gives realistic results at high temperatures and long times to failure. In the interests of continuity with past and present practice, the suggested method is intended to extend existing polynomial descriptions of life parameters at low stress. Where no polynomials exist, the method can be used to describe the behaviour of life parameters throughout the full range of a particular failure mode in the published data

Extrapolation in the development of paediatric medicines: examples from approvals for biological treatments for paediatric chronic immune-mediated inflammatory diseases.

Science.gov (United States)

Stefanska, Anna M; Distlerová, Dorota; Musaus, Joachim; Olski, Thorsten M; Dunder, Kristina; Salmonson, Tomas; Mentzer, Dirk; Müller-Berghaus, Jan; Hemmings, Robert; Veselý, Richard

2017-10-01

The European Union (EU) Paediatric Regulation requires that all new medicinal products applying for a marketing authorisation (MA) in the EU provide a paediatric investigation plan (PIP) covering a clinical and non-clinical trial programme relating to the use in the paediatric population, unless a waiver applies. Conducting trials in children is challenging on many levels, including ethical and practical issues, which may affect the availability of the clinical evidence. In scientifically justified cases, extrapolation of data from other populations can be an option to gather evidence supporting the benefit-risk assessment of the medicinal product for paediatric use. The European Medicines Agency (EMA) is working on providing a framework for extrapolation that is scientifically valid, reliable and adequate to support MA of medicines for children. It is expected that the extrapolation framework together with therapeutic area guidelines and individual case studies will support future PIPs. Extrapolation has already been employed in several paediatric development programmes including biological treatment for immune-mediated diseases. This article reviews extrapolation strategies from MA applications for products for the treatment of juvenile idiopathic arthritis, paediatric psoriasis and paediatric inflammatory bowel disease. It also provides a summary of extrapolation advice expressed in relevant EMA guidelines and initiatives supporting the use of alternative approaches in paediatric medicine development. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Source‐receiver two‐way wave extrapolation for prestack exploding‐reflector modeling and migration

KAUST Repository

Alkhalifah, Tariq Ali; Fomel, Sergey

2010-01-01

While most of the modern seismic imaging methods perform imaging by separating input data into parts (shot gathers), we develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield backward in time. While computationally extensive, this approach has the potential of generating accurate images, free of artifacts associated with conventional approaches. We derive novel high‐order partial differential equations in source‐receiver‐time domain. The fourth order nature of the extrapolation in time has four solutions two of which correspond to the ingoing and outgoing P‐waves and reduces to the zero‐offset exploding‐reflector solutions when the source coincides with the receiver. Using asymptotic approximations, we develop an approach to extrapolating the full prestack wavefield forward or backward in time.

Source‐receiver two‐way wave extrapolation for prestack exploding‐reflector modeling and migration

KAUST Repository

Alkhalifah, Tariq Ali

2010-10-17

While most of the modern seismic imaging methods perform imaging by separating input data into parts (shot gathers), we develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield backward in time. While computationally extensive, this approach has the potential of generating accurate images, free of artifacts associated with conventional approaches. We derive novel high‐order partial differential equations in source‐receiver‐time domain. The fourth order nature of the extrapolation in time has four solutions two of which correspond to the ingoing and outgoing P‐waves and reduces to the zero‐offset exploding‐reflector solutions when the source coincides with the receiver. Using asymptotic approximations, we develop an approach to extrapolating the full prestack wavefield forward or backward in time.

Characterization of an extrapolation chamber for low-energy X-rays: Experimental and Monte Carlo preliminary results

Energy Technology Data Exchange (ETDEWEB)

Neves, Lucio P., E-mail: lpneves@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Silva, Eric A.B., E-mail: ebrito@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Perini, Ana P., E-mail: aperini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil); Maidana, Nora L., E-mail: nmaidana@if.usp.br [Universidade de Sao Paulo, Instituto de Fisica, Travessa R 187, 05508-900 Sao Paulo, SP (Brazil); Caldas, Linda V.E., E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes 2242, 05508-000 Sao Paulo, SP (Brazil)

2012-07-15

The extrapolation chamber is a parallel-plate ionization chamber that allows variation of its air-cavity volume. In this work, an experimental study and MCNP-4C Monte Carlo code simulations of an ionization chamber designed and constructed at the Calibration Laboratory at IPEN to be used as a secondary dosimetry standard for low-energy X-rays are reported. The results obtained were within the international recommendations, and the simulations showed that the components of the extrapolation chamber may influence its response up to 11.0%. - Highlights: Black-Right-Pointing-Pointer A homemade extrapolation chamber was studied experimentally and with Monte Carlo. Black-Right-Pointing-Pointer It was characterized as a secondary dosimetry standard, for low energy X-rays. Black-Right-Pointing-Pointer Several characterization tests were performed and the results were satisfactory. Black-Right-Pointing-Pointer Simulation showed that its components may influence the response up to 11.0%. Black-Right-Pointing-Pointer This chamber may be used as a secondary standard at our laboratory.

Recommended approaches to the scientific evaluation of ecotoxicological hazards and risks of endocrine-active substances

DEFF Research Database (Denmark)

Matthiessen, Peter; Ankley, Gerald T.; Biever, Ronald C

2017-01-01

A SETAC Pellston Workshop(®) "Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA)" was held in February 2016 in Pensacola, Florida, USA. The primary objective of the workshop was to provide advice, based on current scientific understanding, to regulators...... and policy makers; the aim being to make considered, informed decisions on whether to select an ecotoxicological hazard- or a risk-based approach for regulating a given endocrine-disrupting substance (EDS) under review. The workshop additionally considered recent developments in the identification of EDS...... at multiple biological levels of organization for 1 or more ecologically relevant taxa. The substances selected were 17α-ethinylestradiol, perchlorate, propiconazole, 17β-trenbolone, tributyltin, and vinclozolin. The 6 case studies were not comprehensive safety evaluations but provided foundations...

Swimming speed alteration of Artemia sp. and Brachionus plicatilis as a sub-lethal behavioural end-point for ecotoxicological surveys.

Science.gov (United States)

Garaventa, Francesca; Gambardella, Chiara; Di Fino, Alessio; Pittore, Massimiliano; Faimali, Marco

2010-03-01

In this study, we investigated the possibility to improve a new behavioural bioassay (Swimming Speed Alteration test-SSA test) using larvae of marine cyst-forming organisms: e.g. the brine shrimp Artemia sp. and the rotifer Brachionus plicatilis. Swimming speed was investigated as a behavioural end-point for application in ecotoxicology studies. A first experiment to analyse the linear swimming speed of the two organisms was performed to verify the applicability of the video-camera tracking system, here referred to as Swimming Behavioural Recorder (SBR). A second experiment was performed, exposing organisms to different toxic compounds (zinc pyrithione, Macrotrol MT-200, and Eserine). Swimming speed alteration was analyzed together with mortality. The results of the first experiment indicate that SBR is a suitable tool to detect linear swimming speed of the two organisms, since the values have been obtained in accordance with other studies using the same organisms (3.05 mm s(-1) for Artemia sp. and 0.62 mm s(-1) for B. plicatilis). Toxicity test results clearly indicate that swimming speed of Artemia sp. and B. plicatilis is a valid behavioural end-point to detect stress at sub-lethal toxic substance concentrations. Indeed, alterations in swimming speed have been detected at toxic compound concentrations as low as less then 0.1-5% of their LC(50) values. In conclusion, the SSA test with B. plicatilis and Artemia sp. can be a good behavioural integrated output for application in marine ecotoxicology and environmental monitoring programs.

Entropy Rate Estimates for Natural Language—A New Extrapolation of Compressed Large-Scale Corpora

Directory of Open Access Journals (Sweden)

Ryosuke Takahira

2016-10-01

Full Text Available One of the fundamental questions about human language is whether its entropy rate is positive. The entropy rate measures the average amount of information communicated per unit time. The question about the entropy of language dates back to experiments by Shannon in 1951, but in 1990 Hilberg raised doubt regarding a correct interpretation of these experiments. This article provides an in-depth empirical analysis, using 20 corpora of up to 7.8 gigabytes across six languages (English, French, Russian, Korean, Chinese, and Japanese, to conclude that the entropy rate is positive. To obtain the estimates for data length tending to infinity, we use an extrapolation function given by an ansatz. Whereas some ansatzes were proposed previously, here we use a new stretched exponential extrapolation function that has a smaller error of fit. Thus, we conclude that the entropy rates of human languages are positive but approximately 20% smaller than without extrapolation. Although the entropy rate estimates depend on the script kind, the exponent of the ansatz function turns out to be constant across different languages and governs the complexity of natural language in general. In other words, in spite of typological differences, all languages seem equally hard to learn, which partly confirms Hilberg’s hypothesis.

Pollution Assessment of the Biobío River (Chile): Prioritization of Substances of Concern Under an Ecotoxicological Approach

Science.gov (United States)

Alonso, Álvaro; Figueroa, Ricardo; Castro-Díez, Pilar

2017-05-01

The water demand for human activities is rapidly increasing in developing countries. Under these circumstances, preserving aquatic ecosystems should be a priority which requires the development of quality criteria. In this study we perform a preliminary prioritization of the risky substances based on reported ecotoxicological studies and guidelines for the Biobío watershed (Central Chile). Our specific aims are (1) reviewing the scientific information on the aquatic pollution of this watershed, (2) determining the presence and concentration of potential toxic substances in water, sediment and effluents, (3) searching for quality criteria developed by other countries for the selected substances and (4) prioritizing the most risky substances by means of deterministic ecotoxicological risk assessment. We found that paper and mill industries were the main sources of point pollution, while forestry and agriculture were mostly responsible for non-point pollution. The most risky organic substances in the water column were pentachlorophenol and heptachlor, while the most relevant inorganic ones were aluminum, copper, unionized ammonia and mercury. The most risky organic and inorganic substances in the sediment were phenanthrene and mercury, respectively. Our review highlights that an important effort has been done to monitor pollution in the Biobío watershed. However there are emerging pollutants and banned compounds—especially in sediments—that require to be monitored. We suggest that site-specific water quality criteria and sediment quality criteria should be developed for the Biobío watershed, considering the toxicity of mixtures of chemicals to endemic species, and the high natural background level of aluminum in the Biobío.

Novel extrapolation method in the Monte Carlo shell model

International Nuclear Information System (INIS)

Shimizu, Noritaka; Abe, Takashi; Utsuno, Yutaka; Mizusaki, Takahiro; Otsuka, Takaharu; Honma, Michio

2010-01-01

We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full pf-shell calculation of 56 Ni, and the applicability of the method to a system beyond the current limit of exact diagonalization is shown for the pf+g 9/2 -shell calculation of 64 Ge.

SU-E-J-145: Geometric Uncertainty in CBCT Extrapolation for Head and Neck Adaptive Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Liu, C; Kumarasiri, A; Chetvertkov, M; Gordon, J; Chetty, I; Siddiqui, F; Kim, J [Henry Ford Health System, Detroit, MI (United States)

2014-06-01

Purpose: One primary limitation of using CBCT images for H'N adaptive radiotherapy (ART) is the limited field of view (FOV) range. We propose a method to extrapolate the CBCT by using a deformed planning CT for the dose of the day calculations. The aim was to estimate the geometric uncertainty of our extrapolation method. Methods: Ten H'N patients, each with a planning CT (CT1) and a subsequent CT (CT2) taken, were selected. Furthermore, a small FOV CBCT (CT2short) was synthetically created by cropping CT2 to the size of a CBCT image. Then, an extrapolated CBCT (CBCTextrp) was generated by deformably registering CT1 to CT2short and resampling with a wider FOV (42mm more from the CT2short borders), where CT1 is deformed through translation, rigid, affine, and b-spline transformations in order. The geometric error is measured as the distance map ||DVF|| produced by a deformable registration between CBCTextrp and CT2. Mean errors were calculated as a function of the distance away from the CBCT borders. The quality of all the registrations was visually verified. Results: Results were collected based on the average numbers from 10 patients. The extrapolation error increased linearly as a function of the distance (at a rate of 0.7mm per 1 cm) away from the CBCT borders in the S/I direction. The errors (μ±σ) at the superior and inferior boarders were 0.8 ± 0.5mm and 3.0 ± 1.5mm respectively, and increased to 2.7 ± 2.2mm and 5.9 ± 1.9mm at 4.2cm away. The mean error within CBCT borders was 1.16 ± 0.54mm . The overall errors within 4.2cm error expansion were 2.0 ± 1.2mm (sup) and 4.5 ± 1.6mm (inf). Conclusion: The overall error in inf direction is larger due to more large unpredictable deformations in the chest. The error introduced by extrapolation is plan dependent. The mean error in the expanded region can be large, and must be considered during implementation. This work is supported in part by Varian Medical Systems, Palo Alto, CA.

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation

International Nuclear Information System (INIS)

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M.; Pleiter, D.; Stueben, H.

2014-03-01

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q 2 in the range 0.2-1.3 GeV 2 . The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio μ p G E p /G M p . This quantity decreases with Q 2 in a way qualitatively consistent with recent experimental results.

Neural extrapolation of motion for a ball rolling down an inclined plane.

Science.gov (United States)

La Scaleia, Barbara; Lacquaniti, Francesco; Zago, Myrka

2014-01-01

It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

Neural extrapolation of motion for a ball rolling down an inclined plane.

Directory of Open Access Journals (Sweden)

Barbara La Scaleia

Full Text Available It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions and slope (30°, 45° or 60°. In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1. However, even when participants punched an imaginary moving ball (Experiment 2 or drew in air the imaginary trajectory (Experiment 3, they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

Ecotoxicological standard tests confirm beneficial effects of nitrate capture in organically coated grapewood biochar

Science.gov (United States)

Haller, Andreas; Kammann, Claudia; Löhnertz, Otmar

2017-04-01

Due to the rising use of mineral N fertilizers and legume use in agriculture, the input of reactive N into the global N cycle has dramatically increased. Therefore new agricultural techniques that increase N use efficiency and reduce the loss of soil mineral N to surface and ground waters are urgently required. Pyrogenic carbon (biochar) produced from biomass may be used as a beneficial soil amendment to sequester carbon (C) in soils, increase soil fertility in the long term, and reduce environmental pollution such as nitrate leaching or N2O emissions. However, reduced nitrate leaching is not a constant finding when using biochar as a soil amendment and the mechanisms are poorly understood. To investigate if biochar is able to reduce nitrate pollution and its subsequent effects on soil and aquatic fauna, we conducted a series of experiments using standard ecotoxicological test methods: (1) the collembolan reproduction test (ISO 11267 (1999)), (2) the earthworm reproduction test (ISO 11268-2 (1998)), (3) the aquatic Daphnia acute test (ISO 6341 (1996)) and (4) a seedling emergence and growth test (ISO 11269-2 (2006)) also involving leaching events. For the tests grapewood biochar produced with a Kon-Tiki kiln (600-700°C) was used which had previously demonstrated nitrate capture; terrestrial tests were carried out with loamy sand standard soil 2.2 (LUFA-Speyer, Germany). The tests included the factors: (A) nitrate addition (using critical values for the test organisms) or no nitrate addition, (B) control (no biochar), pure biochar and organically-coated biochar. In the aquatic test (3), a nitrate amount which caused 50% of the Daphnia-immobilizing toxic nitrate concentration in leachates was applied to the soil or soil-biochar mixtures. Subsequently, soils were incubated overnight and leached on the next day, producing (in the control) the calculated nitrate concentrations. Daphnids were incubated for 48 hours. Test results without nitrate confirmed that soil

Linear extrapolation distance for a black cylindrical control rod with the pulsed neutron method

International Nuclear Information System (INIS)

Loewenhielm, G.

1978-03-01

The objective of this experiment was to measure the linear extrapolation distance for a central black cylindrical control rod in a cylindrical water moderator. The radius for both the control rod and the moderator was varied. The pulsed neutron technique was used and the decay constant was measured for both a homogeneous and a heterogeneous system. From the difference in the decay constants the extrapolation distance could be calculated. The conclusion is that within experimental error it is safe to use the approximate formula given by Pellaud or the more exact one given by Kavenoky. We can also conclude that linear anisotropic scattering is accounted for in a correct way in the approximate formula given by Pellaud and Prinja and Williams

Standardization of electron-capture and complex beta-gamma radionuclides by the efficiency extrapolation method

International Nuclear Information System (INIS)

Grigorescu, L.

1976-07-01

The efficiency extrapolation method was improved by establishing ''linearity conditions'' for the discrimination on the gamma channel of the coincidence equipment. These conditions were proved to eliminate the systematic error of the method. A control procedure for the fulfilment of linearity conditions and estimation of residual systematic error was given. For law-energy gamma transitions an ''equivalent scheme principle'' was established, which allow for a correct application of the method. Solutions of Cs-134, Co-57, Ba-133 and Zn-65 were standardized with an ''effective standard deviation'' of 0.3-0.7 per cent. For Zn-65 ''special linearity conditions'' were applied. (author)

Extrapolated surface dose measurements using a NdFeB magnetic deflector for 6 MV x-ray beams.

Science.gov (United States)

Damrongkijudom, N; Butson, M; Rosenfeld, A

2007-03-01

Extrapolated surface dose measurements have been performed using radiographic film to measure 2-Dimensional maps of skin and surface dose with and without a magnetic deflector device aimed at reducing surface dose. Experiments are also performed using an Attix parallel plate ionisation chamber for comparison to radiographic film extrapolation surface dose analysis. Extrapolated percentage surface dose assessments from radiographic film at the central axis of a 6 MV x-ray beam with magnetic deflector for field size 10 x 10 cm2, 15 x 15 cm2 and 20 x 20 cm2 are 9 +/- 3%, 13 +/- 3% and 16 +/- 3%, these compared to 14 +/- 3%, 19 +/- 3%, and 27 +/- 3% for open fields, respectively. Results from Attix chamber for the same field size are 12 +/- 1%, 15 +/- 1% and 18 +/- 1%, these compared to 16 +/- 1%, 21 +/- 1% and 27 +/- 1% for open fields, respectively. Results are also shown for profiles measured in-plane and cross-plane to the magnetic deflector and compared to open field data. Results have shown that the surface dose is reduced at all sites within the treatment field with larger reductions seen on one side of the field due to the sweeping nature of the designed magnetic field. Radiographic film extrapolation provides an advanced surface dose assessment and has matched well with Attix chamber results. Film measurement allows for easy 2 dimensional dose assessments.

Eco-toxicology effect on Moina mongolica Daday exposed to Cd2+, Pb2+, and Hg2+ by the food chain.

Science.gov (United States)

Wang, Meiru; Zhao, Wen; Jia, Xuying; Wei, Jie; Wang, Shan

2018-03-28

As one of the most important contaminants, heavy metals can seriously influence human health via the food chain. In this study, the eco-toxicological effects of Cd 2+ , Pb 2+ , and Hg 2+ on Moina mongolica Daday were investigated by feeding them Chlorella sp. that contained heavy metals. The relative body lengths of the M. mongolica changed rapidly, peaking at 2 days for Hg 2+ , 6 days for Cd 2+ , and 8 days for Pb 2+ . Moreover, grazing and clearance rates of the experimental group were apparently lower than those of the control group after immersion in heavy metals. Additionally, Cd 2+ and Pd 2+ in the food significantly influenced the mean lifespan of M. mongolica of the P and F 1 generations. Egg production per brood was also significantly impacted by Cd 2+ and Pb 2+ in the food in generation P. Interestingly, Pb 2+ was the only metal that significantly influenced the reproduction times of F 2 , while the reproductive times were significantly influenced by Cd 2+ for generation P. Moreover, Cd 2+ , Pb 2+ , and Hg 2+ in the food significantly influenced the fecundity of generation P. Evaluation of the population growth parameters of M. mongolica revealed that the intrinsic rate of increase, net reproduction rate, and finite rate of increase were significantly influenced by Cd 2+ , Pb 2+ , and Hg 2+ in the food in generation P. Additionally, Hg 2+ slightly impacted generation time for generation P. Finally, the acute toxicity toward M. mongolica was Hg 2+  > Cd 2+  > Pb 2+ . Overall, heavy metals in the food were likely to influence the growth, survival, and population growth of M. mongolica through the food chain.

Video error concealment using block matching and frequency selective extrapolation algorithms

Science.gov (United States)

P. K., Rajani; Khaparde, Arti

2017-06-01

Error Concealment (EC) is a technique at the decoder side to hide the transmission errors. It is done by analyzing the spatial or temporal information from available video frames. It is very important to recover distorted video because they are used for various applications such as video-telephone, video-conference, TV, DVD, internet video streaming, video games etc .Retransmission-based and resilient-based methods, are also used for error removal. But these methods add delay and redundant data. So error concealment is the best option for error hiding. In this paper, the error concealment methods such as Block Matching error concealment algorithm is compared with Frequency Selective Extrapolation algorithm. Both the works are based on concealment of manually error video frames as input. The parameter used for objective quality measurement was PSNR (Peak Signal to Noise Ratio) and SSIM(Structural Similarity Index). The original video frames along with error video frames are compared with both the Error concealment algorithms. According to simulation results, Frequency Selective Extrapolation is showing better quality measures such as 48% improved PSNR and 94% increased SSIM than Block Matching Algorithm.

Making the most of what we have: application of extrapolation approaches in wildlife transfer models

Energy Technology Data Exchange (ETDEWEB)

Beresford, Nicholas A.; Barnett, Catherine L.; Wells, Claire [NERC Centre for Ecology and Hydrology, Lancaster Environment Center, Library Av., Bailrigg, Lancaster, LA1 4AP (United Kingdom); School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Wood, Michael D. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Vives i Batlle, Jordi [Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol (Belgium); Brown, Justin E.; Hosseini, Ali [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Yankovich, Tamara L. [International Atomic Energy Agency, Vienna International Centre, 1400, Vienna (Austria); Bradshaw, Clare [Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 (Sweden); Willey, Neil [Centre for Research in Biosciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY (United Kingdom)

2014-07-01

Radiological environmental protection models need to predict the transfer of many radionuclides to a large number of organisms. There has been considerable development of transfer (predominantly concentration ratio) databases over the last decade. However, in reality it is unlikely we will ever have empirical data for all the species-radionuclide combinations which may need to be included in assessments. To provide default values for a number of existing models/frameworks various extrapolation approaches have been suggested (e.g. using data for a similar organism or element). This paper presents recent developments in two such extrapolation approaches, namely phylogeny and allometry. An evaluation of how extrapolation approaches have performed and the potential application of Bayesian statistics to make best use of available data will also be given. Using a Residual Maximum Likelihood (REML) mixed-model regression we initially analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites to investigate if phylogenetic variation in transfer could be identified. The REML analysis generated an estimated mean value for each species on a common scale after taking account of the effect of the inter-site variation. Using an independent dataset, we tested the hypothesis that the REML model outputs could be used to predict radionuclide activity concentrations in other species from the results of a species which had been sampled at a specific site. The outputs of the REML analysis accurately predicted {sup 137}Cs activity concentrations in different species of fish from 27 lakes. Although initially investigated as an extrapolation approach the output of this work is a potential alternative to the highly site dependent concentration ratio model. We are currently applying this approach to a wider range of organism types and different ecosystems. An initial analysis of these results will be presented. The application of allometric, or mass

Nowcasting of precipitation by an NWP model using assimilation of extrapolated radar reflectivity

Czech Academy of Sciences Publication Activity Database

Sokol, Zbyněk; Zacharov, Petr, jr.

2012-01-01

Roč. 138, č. 665 (2012), s. 1072-1082 ISSN 0035-9009 Institutional support: RVO:68378289 Keywords : precipitation forecast * radar extrapolation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.327, year: 2012 http://onlinelibrary.wiley.com/doi/10.1002/qj.970/abstract

Ecotoxicological assays of Diethyltoluamide and Lemongrass Essencial Oil in irradiated and non-irradiated aquatic organisms

International Nuclear Information System (INIS)

Gimiliani, Giovana T.; Rogero, Sizue O.; Martini, Gisela A.; Rogero, Jose R.

2015-01-01

Aquatic invertebrates can be potentially exposed to nonradioactive contaminants in conjunction with ionizing radiation, especially in highly industrialized areas surrounding nuclear facilities, where radionuclides can accidentally be discharged in the aquatic environment containing stable chemicals. The aquatic organisms have continually been exposed to chemical contaminants like personal care products (PCPs) which have been found in various environmental matrices and may cause adverse effects to aquatic life and human health as radioactive products. In this study was used C. silvestrii as bioindicator organism in chronic ecotoxicity assays with lemongrass essencial oil (LEO) and Diethyltoluamide (DEET), both are insect repellent. In addition to exposition of the compounds, the organisms were irradiated with gamma rays from Co-60 source. Thus, the aim of this study was to evaluate the possible synergistic effect of gamma radiation and mosquito repellent products in the reproduction of Ceriodaphnia silvestrii utilizing standardized ecotoxicological tests. The C. silvestrii inhibition concentration (IC25; 7 days) result after DEET exposition was 16.4 ± 1.4 mg L -1 and for LEO was 3.1 ± 1.4 mg L -1 . In the irradiated (25 Gy) C. silvestrii exposed to DEET and LEO, the concentration that inhibited reproduction was 16.1 ± 0.9 mg L -1 and 2.4 ± 0.3 mg L -1 respectively. The results showed that the reproduction of irradiated C. silvestrii was not significantly affected when compared with non-irradiated organisms when exposed to DEET or LEO. (author)

Ecotoxicological assays of Diethyltoluamide and Lemongrass Essencial Oil in irradiated and non-irradiated aquatic organisms

Energy Technology Data Exchange (ETDEWEB)

Gimiliani, Giovana T.; Rogero, Sizue O.; Martini, Gisela A.; Rogero, Jose R., E-mail: sorogero@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Aquatic invertebrates can be potentially exposed to nonradioactive contaminants in conjunction with ionizing radiation, especially in highly industrialized areas surrounding nuclear facilities, where radionuclides can accidentally be discharged in the aquatic environment containing stable chemicals. The aquatic organisms have continually been exposed to chemical contaminants like personal care products (PCPs) which have been found in various environmental matrices and may cause adverse effects to aquatic life and human health as radioactive products. In this study was used C. silvestrii as bioindicator organism in chronic ecotoxicity assays with lemongrass essencial oil (LEO) and Diethyltoluamide (DEET), both are insect repellent. In addition to exposition of the compounds, the organisms were irradiated with gamma rays from Co-60 source. Thus, the aim of this study was to evaluate the possible synergistic effect of gamma radiation and mosquito repellent products in the reproduction of Ceriodaphnia silvestrii utilizing standardized ecotoxicological tests. The C. silvestrii inhibition concentration (IC25; 7 days) result after DEET exposition was 16.4 ± 1.4 mg L{sup -1} and for LEO was 3.1 ± 1.4 mg L{sup -1}. In the irradiated (25 Gy) C. silvestrii exposed to DEET and LEO, the concentration that inhibited reproduction was 16.1 ± 0.9 mg L{sup -1} and 2.4 ± 0.3 mg L{sup -1} respectively. The results showed that the reproduction of irradiated C. silvestrii was not significantly affected when compared with non-irradiated organisms when exposed to DEET or LEO. (author)

Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies

International Nuclear Information System (INIS)

Rothe, R.E.

1997-12-01

Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments

A comparison of high-order explicit Runge–Kutta, extrapolation, and deferred correction methods in serial and parallel

KAUST Repository

Ketcheson, David I.

2014-06-13

We compare the three main types of high-order one-step initial value solvers: extrapolation, spectral deferred correction, and embedded Runge–Kutta pairs. We consider orders four through twelve, including both serial and parallel implementations. We cast extrapolation and deferred correction methods as fixed-order Runge–Kutta methods, providing a natural framework for the comparison. The stability and accuracy properties of the methods are analyzed by theoretical measures, and these are compared with the results of numerical tests. In serial, the eighth-order pair of Prince and Dormand (DOP8) is most efficient. But other high-order methods can be more efficient than DOP8 when implemented in parallel. This is demonstrated by comparing a parallelized version of the wellknown ODEX code with the (serial) DOP853 code. For an N-body problem with N = 400, the experimental extrapolation code is as fast as the tuned Runge–Kutta pair at loose tolerances, and is up to two times as fast at tight tolerances.

Predicting treatment effect from surrogate endpoints and historical trials: an extrapolation involving probabilities of a binary outcome or survival to a specific time.

Science.gov (United States)

Baker, Stuart G; Sargent, Daniel J; Buyse, Marc; Burzykowski, Tomasz

2012-03-01

Using multiple historical trials with surrogate and true endpoints, we consider various models to predict the effect of treatment on a true endpoint in a target trial in which only a surrogate endpoint is observed. This predicted result is computed using (1) a prediction model (mixture, linear, or principal stratification) estimated from historical trials and the surrogate endpoint of the target trial and (2) a random extrapolation error estimated from successively leaving out each trial among the historical trials. The method applies to either binary outcomes or survival to a particular time that is computed from censored survival data. We compute a 95% confidence interval for the predicted result and validate its coverage using simulation. To summarize the additional uncertainty from using a predicted instead of true result for the estimated treatment effect, we compute its multiplier of standard error. Software is available for download. © 2011, The International Biometric Society No claim to original US government works.

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation

Energy Technology Data Exchange (ETDEWEB)

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ., SA (Australia). ARC Centre of Excellence in Particle Physics at the Terascale and CSSM; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). JSC; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations

2014-03-15

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q{sup 2} in the range 0.2-1.3 GeV{sup 2}. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio μ{sub p}G{sub E}{sup p}/G{sub M}{sup p}. This quantity decreases with Q{sup 2} in a way qualitatively consistent with recent experimental results.

Quantification of the biocontrol agent Trichoderma harzianum with real-time TaqMan PCR and its potential extrapolation to the hyphal biomass.

Science.gov (United States)

López-Mondéjar, Rubén; Antón, Anabel; Raidl, Stefan; Ros, Margarita; Pascual, José Antonio

2010-04-01

The species of the genus Trichoderma are used successfully as biocontrol agents against a wide range of phytopathogenic fungi. Among them, Trichoderma harzianum is especially effective. However, to develop more effective fungal biocontrol strategies in organic substrates and soil, tools for monitoring the control agents are required. Real-time PCR is potentially an effective tool for the quantification of fungi in environmental samples. The aim of this study consisted of the development and application of a real-time PCR-based method to the quantification of T. harzianum, and the extrapolation of these data to fungal biomass values. A set of primers and a TaqMan probe for the ITS region of the fungal genome were designed and tested, and amplification was correlated to biomass measurements obtained with optical microscopy and image analysis, of the hyphal length of the mycelium of the colony. A correlation of 0.76 between ITS copies and biomass was obtained. The extrapolation of the quantity of ITS copies, calculated based on real-time PCR data, into quantities of fungal biomass provides potentially a more accurate value of the quantity of soil fungi. Copyright 2009 Elsevier Ltd. All rights reserved.

Potential Hydraulic Modelling Errors Associated with Rheological Data Extrapolation in Laminar Flow

International Nuclear Information System (INIS)

Shadday, Martin A. Jr.

1997-01-01

The potential errors associated with the modelling of flows of non-Newtonian slurries through pipes, due to inadequate rheological models and extrapolation outside of the ranges of data bases, are demonstrated. The behaviors of both dilatant and pseudoplastic fluids with yield stresses, and the errors associated with treating them as Bingham plastics, are investigated

Mass extrapolation of quarks and leptons to higher generations

Energy Technology Data Exchange (ETDEWEB)

Barik, N [Utkal Univ., Bhubaneswar (India). Dept. of Physics

1981-05-01

An empirical mass formula is tested for the basic fermion sequences of charged quarks and leptons. This relation is a generalization of Barut's mass formula for the lepton sequence (e, ..mu.., tau ....). It is found that successful mass extrapolation to the third and possibly to other higher generations (N > 2) can be obtained with the first and second generation masses as inputs, which predicts the top quark mass msub(t) to be around 20 GeV. This also leads to the mass ratios between members of two different sequences (i) and (i') corresponding to the same higher generations (N > 2).

Mass extrapolation of quarks and leptons to higher generations

International Nuclear Information System (INIS)

Barik, N.

1981-01-01

An empirical mass formula is tested for the basic fermion sequences of charged quarks and leptons. This relation is a generalization of Barut's mass formula for the lepton sequence (e, μ, tau ....). It is found that successful mass extrapolation to the third and possibly to other higher generations (N > 2) can be obtained with the first and second generation masses as inputs, which predicts the top quark mass msub(t) to be around 20 GeV. This also leads to the mass ratios between members of two different sequences (i) and (i') corresponding to the same higher generations (N > 2). (author)

EXTRAPOLATION METHOD FOR MAXIMAL AND 24-H AVERAGE LTE TDD EXPOSURE ESTIMATION.

Science.gov (United States)

Franci, D; Grillo, E; Pavoncello, S; Coltellacci, S; Buccella, C; Aureli, T

2018-01-01

The Long-Term Evolution (LTE) system represents the evolution of the Universal Mobile Telecommunication System technology. This technology introduces two duplex modes: Frequency Division Duplex and Time Division Duplex (TDD). Despite having experienced a limited expansion in the European countries since the debut of the LTE technology, a renewed commercial interest for LTE TDD technology has recently been shown. Therefore, the development of extrapolation procedures optimised for TDD systems becomes crucial, especially for the regulatory authorities. This article presents an extrapolation method aimed to assess the exposure to LTE TDD sources, based on the detection of the Cell-Specific Reference Signal power level. The method introduces a βTDD parameter intended to quantify the fraction of the LTE TDD frame duration reserved for downlink transmission. The method has been validated by experimental measurements performed on signals generated by both a vector signal generator and a test Base Transceiver Station installed at Linkem S.p.A facility in Rome. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ground-state inversion method applied to calculation of molecular photoionization cross-sections by atomic extrapolation: Interference effects at low energies

International Nuclear Information System (INIS)

Hilton, P.R.; Nordholm, S.; Hush, N.S.

1980-01-01

The ground-state inversion method, which we have previously developed for the calculation of atomic cross-sections, is applied to the calculation of molecular photoionization cross-sections. These are obtained as a weighted sum of atomic subshell cross-sections plus multi-centre interference terms. The atomic cross-sections are calculated directly for the atomic functions which when summed over centre and symmetry yield the molecular orbital wave function. The use of the ground-state inversion method for this allows the effect of the molecular environment on the atomic cross-sections to be calculated. Multi-centre terms are estimated on the basis of an effective plane-wave expression for this contribution to the total cross-section. Finally the method is applied to the range of photon energies from 0 to 44 eV where atomic extrapolation procedures have not previously been tested. Results obtained for H 2 , N 2 and CO show good agreement with experiment, particularly when interference effects and effects of the molecular environment on the atomic cross-sections are included. The accuracy is very much better than that of previous plane-wave and orthogonalized plane-wave methods, and can stand comparison with that of recent more sophisticated approaches. It is a feature of the method that calculation of cross-sections either of atoms or of large molecules requires very little computer time, provided that good quality wave functions are available, and it is then of considerable potential practical interest for photoelectorn spectroscopy. (orig.)

WE-DE-201-05: Evaluation of a Windowless Extrapolation Chamber Design and Monte Carlo Based Corrections for the Calibration of Ophthalmic Applicators

Energy Technology Data Exchange (ETDEWEB)

Hansen, J; Culberson, W; DeWerd, L [University of Wisconsin Medical Radiation Research Center, Madison, WI (United States); Soares, C [NIST (retired), Gaithersburg, MD (United States)

2016-06-15

Purpose: To test the validity of a windowless extrapolation chamber used to measure surface dose rate from planar ophthalmic applicators and to compare different Monte Carlo based codes for deriving correction factors. Methods: Dose rate measurements were performed using a windowless, planar extrapolation chamber with a {sup 90}Sr/{sup 90}Y Tracerlab RA-1 ophthalmic applicator previously calibrated at the National Institute of Standards and Technology (NIST). Capacitance measurements were performed to estimate the initial air gap width between the source face and collecting electrode. Current was measured as a function of air gap, and Bragg-Gray cavity theory was used to calculate the absorbed dose rate to water. To determine correction factors for backscatter, divergence, and attenuation from the Mylar entrance window found in the NIST extrapolation chamber, both EGSnrc Monte Carlo user code and Monte Carlo N-Particle Transport Code (MCNP) were utilized. Simulation results were compared with experimental current readings from the windowless extrapolation chamber as a function of air gap. Additionally, measured dose rate values were compared with the expected result from the NIST source calibration to test the validity of the windowless chamber design. Results: Better agreement was seen between EGSnrc simulated dose results and experimental current readings at very small air gaps (<100 µm) for the windowless extrapolation chamber, while MCNP results demonstrated divergence at these small gap widths. Three separate dose rate measurements were performed with the RA-1 applicator. The average observed difference from the expected result based on the NIST calibration was −1.88% with a statistical standard deviation of 0.39% (k=1). Conclusion: EGSnrc user code will be used during future work to derive correction factors for extrapolation chamber measurements. Additionally, experiment results suggest that an entrance window is not needed in order for an extrapolation

Beyond the plot: technology extrapolation domains for scaling out agronomic science

Science.gov (United States)

Rattalino Edreira, Juan I.; Cassman, Kenneth G.; Hochman, Zvi; van Ittersum, Martin K.; van Bussel, Lenny; Claessens, Lieven; Grassini, Patricio

2018-05-01

Ensuring an adequate food supply in systems that protect environmental quality and conserve natural resources requires productive and resource-efficient cropping systems on existing farmland. Meeting this challenge will be difficult without a robust spatial framework that facilitates rapid evaluation and scaling-out of currently available and emerging technologies. Here we develop a global spatial framework to delineate ‘technology extrapolation domains’ based on key climate and soil factors that govern crop yields and yield stability in rainfed crop production. The proposed framework adequately represents the spatial pattern of crop yields and stability when evaluated over the data-rich US Corn Belt. It also facilitates evaluation of cropping system performance across continents, which can improve efficiency of agricultural research that seeks to intensify production on existing farmland. Populating this biophysical spatial framework with appropriate socio-economic attributes provides the potential to amplify the return on investments in agricultural research and development by improving the effectiveness of research prioritization and impact assessment.

Some remarks on non-monotonic effects at low radiation intensities, on the problem of extrapolating doses between high and low intensities and on the problem of thresholds

International Nuclear Information System (INIS)

Delattre, P.

1983-01-01

On the basis of a general descriptive framework which takes into account the intensity factor and the time distribution of radiation, a detailed justification for which is to be found in earlier publications, the three fundamental problems mentioned in the title of this paper can be approached in a new way. If the biological effect e for a given dose D delivered at different radiation intensities phi is studied, we find that the curve e=f(phi) can exhibit non-monotonic shapes. This type of phenomenon is known in pharmacology and toxicology and may well exist also for low- or medium-intensity radiation effects. Extrapolation of the effects of a given dose between high and low radiation intensities phi is usually carried out by means of an empirical linear or linear-quadratic formulation. This procedure is insufficiently justified from a theoretical point of view. It is shown here that the effects can be written in the form e=k(phi)D and that the factor of proportionality k(phi) is a generally very complicated function of phi. Hence, the usual extrapolation procedures cannot deal with certain ranges of values of phi within which the effects observed at a given dose may be greater than when the dose is delivered at higher intensity. The problem of thresholds is actually far more difficult than the current literature on the subject would suggest. It is shown here, on the basis of considerations of qualitative dynamics, that several types of threshold must be defined, starting with a threshold for the radiation intensity phi. All these thresholds are interrelated hierarchically in fairly complex ways which must be studied case by case. These results show that it is illusory to attempt to define a universal notion of threshold in terms of dose. The conceptual framework used in the proposed approach proves also to be very illuminating for other studies in progress, particularly in the investigation of phenomena associated with ageing and carcinogenesis. (author)

UFOs in the LHC: Observations, studies and extrapolations

CERN Document Server

Baer, T; Cerutti, F; Ferrari, A; Garrel, N; Goddard, B; Holzer, EB; Jackson, S; Lechner, A; Mertens, V; Misiowiec, M; Nebot del Busto, E; Nordt, A; Uythoven, J; Vlachoudis, V; Wenninger, J; Zamantzas, C; Zimmermann, F; Fuster, N

2012-01-01

Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented

Communication: Predicting virial coefficients and alchemical transformations by extrapolating Mayer-sampling Monte Carlo simulations

Science.gov (United States)

Hatch, Harold W.; Jiao, Sally; Mahynski, Nathan A.; Blanco, Marco A.; Shen, Vincent K.

2017-12-01

Virial coefficients are predicted over a large range of both temperatures and model parameter values (i.e., alchemical transformation) from an individual Mayer-sampling Monte Carlo simulation by statistical mechanical extrapolation with minimal increase in computational cost. With this extrapolation method, a Mayer-sampling Monte Carlo simulation of the SPC/E (extended simple point charge) water model quantitatively predicted the second virial coefficient as a continuous function spanning over four orders of magnitude in value and over three orders of magnitude in temperature with less than a 2% deviation. In addition, the same simulation predicted the second virial coefficient if the site charges were scaled by a constant factor, from an increase of 40% down to zero charge. This method is also shown to perform well for the third virial coefficient and the exponential parameter for a Lennard-Jones fluid.

Parametric methods of describing and extrapolating the characteristics of long-term strength of refractory materials

International Nuclear Information System (INIS)

Tsvilyuk, I.S.; Avramenko, D.S.

1986-01-01

This paper carries out the comparative analysis of the suitability of parametric methods for describing and extrapolating the results of longterm tests on refractory materials. Diagrams are presented of the longterm strength of niobium based alloys tested in a vacuum of 1.3 X 10 -3 Pa. The predicted values and variance of the estimate of endurance of refractory alloys are presented by parametric dependences. The longterm strength characteristics can be described most adequately by the Manson-Sakkop and Sherby-Dorn methods. Several methods must be used to ensure the reliable extrapolation of the longterm strength characteristics to the time period an order of magnitude longer than the experimental data. The most suitable method cannot always be selected on the basis of the correlation ratio

Quantitative Cross-Species Extrapolation between Humans and Fish: The Case of the Anti-Depressant Fluoxetine

Science.gov (United States)

Margiotta-Casaluci, Luigi; Owen, Stewart F.; Cumming, Rob I.; de Polo, Anna; Winter, Matthew J.; Panter, Grace H.; Rand-Weaver, Mariann; Sumpter, John P.

2014-01-01

Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE) based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis). To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas) were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 µg/L) to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (HTPCs). Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the HTPC range, whereas no effects were observed at plasma concentrations below the HTPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool to guide the

Quantitative cross-species extrapolation between humans and fish: the case of the anti-depressant fluoxetine.

Directory of Open Access Journals (Sweden)

Luigi Margiotta-Casaluci

Full Text Available Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis. To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 µg/L to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (H(TPCs. Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the H(TPC range, whereas no effects were observed at plasma concentrations below the H(TPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool

Community assessment techniques and the implications for rarefaction and extrapolation with Hill numbers.

Science.gov (United States)

Cox, Kieran D; Black, Morgan J; Filip, Natalia; Miller, Matthew R; Mohns, Kayla; Mortimor, James; Freitas, Thaise R; Greiter Loerzer, Raquel; Gerwing, Travis G; Juanes, Francis; Dudas, Sarah E

2017-12-01

Diversity estimates play a key role in ecological assessments. Species richness and abundance are commonly used to generate complex diversity indices that are dependent on the quality of these estimates. As such, there is a long-standing interest in the development of monitoring techniques, their ability to adequately assess species diversity, and the implications for generated indices. To determine the ability of substratum community assessment methods to capture species diversity, we evaluated four methods: photo quadrat, point intercept, random subsampling, and full quadrat assessments. Species density, abundance, richness, Shannon diversity, and Simpson diversity were then calculated for each method. We then conducted a method validation at a subset of locations to serve as an indication for how well each method captured the totality of the diversity present. Density, richness, Shannon diversity, and Simpson diversity estimates varied between methods, despite assessments occurring at the same locations, with photo quadrats detecting the lowest estimates and full quadrat assessments the highest. Abundance estimates were consistent among methods. Sample-based rarefaction and extrapolation curves indicated that differences between Hill numbers (richness, Shannon diversity, and Simpson diversity) were significant in the majority of cases, and coverage-based rarefaction and extrapolation curves confirmed that these dissimilarities were due to differences between the methods, not the sample completeness. Method validation highlighted the inability of the tested methods to capture the totality of the diversity present, while further supporting the notion of extrapolating abundances. Our results highlight the need for consistency across research methods, the advantages of utilizing multiple diversity indices, and potential concerns and considerations when comparing data from multiple sources.

AMEG: the new SETAC advisory group on aquatic macrophyte ecotoxicology.

Science.gov (United States)

Arts, Gertie; Davies, Jo; Dobbs, Michael; Ebke, Peter; Hanson, Mark; Hommen, Udo; Knauer, Katja; Loutseti, Stefania; Maltby, Lorraine; Mohr, Silvia; Poovey, Angela; Poulsen, Véronique

2010-05-01

Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species because of differences in the duration and mode of exposure; sensitivity to the specific toxic mode of action of the chemical; and species-specific traits (e.g., duckweed's very short generation time). These topics were addressed during the workshop entitled "Aquatic Macrophyte Risk Assessment for Pesticides" (AMRAP) where a risk assessment scheme for aquatic macrophytes was proposed. Four working groups evolved from this workshop and were charged with the task of developing Tier 1 and higher-tier aquatic macrophyte risk assessment procedures. Subsequently, a SETAC Advisory Group, the Macrophyte Ecotoxicology Group (AMEG) was formed as an umbrella organization for various macrophyte working groups. The purpose of AMEG is to provide scientifically based guidance in all aspects of aquatic macrophyte testing in the laboratory and field, including prospective as well as retrospective risk assessments for chemicals. As AMEG expands, it will begin to address new topics including bioremediation and sustainable management of aquatic macrophytes in the context of ecosystem services.

Comparison among creep rupture strength extrapolation methods with application to data for AISI 316 SS from Italy, France, U.K. and F.R.G

International Nuclear Information System (INIS)

Brunori, G.; Cappellato, S.; Vacchiano, S.; Guglielmi, F.

1982-01-01

Inside Activity 3 ''Materials'' of WGCS, the member states UK and FRG have developed a work regarding extrapolation methods for creep data. This work has been done by comparising extrapolation methods in use in their countries by applying them to creep rupture strength data on AISI 316 SS obtained in UK and FRG. This work has been issued on April 1978 and the Community has dealed it to all Activity 3 Members. Italy, in the figure of NIRA S.p.A., has received, from the European Community a contract to extend the work to Italian and French data, using extrapolation methods currently in use in Italy. The work should deal with the following points: - Collect of Italian experimental data; - Chemical analysis on Italian Specimen; - Comparison among Italian experimental data with French, FRG and UK data; - Description of extrapolation methods in use in Italy; - Application of these extrapolation methods to Italian, French, British and Germany data; - Extensions of a Final Report

Differentiation of sympatric zebra and quagga mussels in ecotoxicological studies: A comparison of morphometric data, gene expression, and body metal concentrations.

Science.gov (United States)

Kerambrun, E; Delahaut, L; Geffard, A; David, E

2018-06-15

The zebra mussel is among the best studied freshwater molluscs in ecotoxicology, but information on the quagga mussel is lacking. Considering its potential spread, we selected a river in France in which zebra and quagga mussels coexisted, and then we used genetic markers to differentiate the two species and compared morphological parameters. cDNA sequencing assays of ten genes already used in zebra mussels were performed on quagga mussels to obtain functional specific primers. Then we analyzed the expression of genes involved in cellular metabolic activities (Cytochrome-c-oxidase - cox, and ATP synthase - atp), detoxification processes (Glutathione-S-Transferase - gst), oxidative stress (Catalase - cat), and digestive functions (Amylase - amy) on the two species. Whereas morphometric analysis underlined similarities in shape between the two species, relative gene expression profiles and metal concentrations evidenced strong differences. Quagga mussels notably presented half as high concentrations in Cd and Pb, two particularly toxic elements, as zebra mussels. These results imply that i) particular attention should be paid to properly distinguish the two species considering their similar external appearance, and ii) zebra mussels cannot be replaced by quagga mussels in ecotoxicological studies without preliminary investigations on biomarker response patterns. To our knowledge, this study is the first to have undertaken such an approach in gene expression analysis in quagga mussels, and more generally to have compared such biomarker responses of zebra and quagga mussels in the field. Copyright © 2018 Elsevier Inc. All rights reserved.

Resolution enhancement in digital holography by self-extrapolation of holograms.

Science.gov (United States)

Latychevskaia, Tatiana; Fink, Hans-Werner

2013-03-25

It is generally believed that the resolution in digital holography is limited by the size of the captured holographic record. Here, we present a method to circumvent this limit by self-extrapolating experimental holograms beyond the area that is actually captured. This is done by first padding the surroundings of the hologram and then conducting an iterative reconstruction procedure. The wavefront beyond the experimentally detected area is thus retrieved and the hologram reconstruction shows enhanced resolution. To demonstrate the power of this concept, we apply it to simulated as well as experimental holograms.

The effects of different expansions of the exit distribution on the extrapolation length for linearly anisotropic scattering

International Nuclear Information System (INIS)

Bulut, S.; Guelecyuez, M.C.; Kaskas, A.; Tezcan, C.

2007-01-01

H N and singular eigenfunction methods are used to determine the neutron distribution everywhere in a source-free half space with zero incident flux for a linearly anisotropic scattering kernel. The singular eigenfunction expansion of the method of elementary solutions is used. The orthogonality relations of the discrete and continuous eigenfunctions for linearly anisotropic scattering provides the determination of the expansion coefficients. Different expansions of the exit distribution are used: the expansion in powers of μ, the expansion in terms of Legendre polynomials and the expansion in powers of 1/(1+μ). The results are compared to each other. In the second part of our work, the transport equation and the infinite medium Green function are used. The numerical results of the extrapolation length obtained for the different expansions is discussed. (orig.)

To describe and control exposure in nanoecotoxicology tests

DEFF Research Database (Denmark)

Baun, Anders

are fulfilling the purpose they originally were intended for (ranking and classification). The validity of extrapolations made from these data (e.g. predicted no-effect concentrations for environmental risk assessments) is therefore further questionable. Based on own experiences these fundamental problems......There is an urgent need for reliable and reproducible results of ecotoxicological experiments in order to identify, rank, and classify the environmental hazards of nanomaterials. Standardized methods and guideline tests traditionally used for chemicals are today recommended for the testing...... of nanomaterials. While the database of results from these tests is rapidly expanding, problems with controlling the exposure are often reported, e.g. due to the particle behavior in the test media used. Problems encountered include uncontrollable aggregation, agglomeration, sedimentation, or dissolution...

Improving Predictions with Reliable Extrapolation Schemes and Better Understanding of Factorization

Science.gov (United States)

More, Sushant N.

New insights into the inter-nucleon interactions, developments in many-body technology, and the surge in computational capabilities has led to phenomenal progress in low-energy nuclear physics in the past few years. Nonetheless, many calculations still lack a robust uncertainty quantification which is essential for making reliable predictions. In this work we investigate two distinct sources of uncertainty and develop ways to account for them. Harmonic oscillator basis expansions are widely used in ab-initio nuclear structure calculations. Finite computational resources usually require that the basis be truncated before observables are fully converged, necessitating reliable extrapolation schemes. It has been demonstrated recently that errors introduced from basis truncation can be taken into account by focusing on the infrared and ultraviolet cutoffs induced by a truncated basis. We show that a finite oscillator basis effectively imposes a hard-wall boundary condition in coordinate space. We accurately determine the position of the hard-wall as a function of oscillator space parameters, derive infrared extrapolation formulas for the energy and other observables, and discuss the extension of this approach to higher angular momentum and to other localized bases. We exploit the duality of the harmonic oscillator to account for the errors introduced by a finite ultraviolet cutoff. Nucleon knockout reactions have been widely used to study and understand nuclear properties. Such an analysis implicitly assumes that the effects of the probe can be separated from the physics of the target nucleus. This factorization between nuclear structure and reaction components depends on the renormalization scale and scheme, and has not been well understood. But it is potentially critical for interpreting experiments and for extracting process-independent nuclear properties. We use a class of unitary transformations called the similarity renormalization group (SRG) transformations to

Ecotoxicological assessment of dewatered drinking water treatment residue for environmental recycling.

Science.gov (United States)

Yuan, Nannan; Wang, Changhui; Wendling, Laura A; Pei, Yuansheng

2017-09-01

The beneficial recycle of drinking water treatment residue (DWTR) in environmental remediation has been demonstrated in many reports. However, the lack of information concerning the potential toxicity of dewatered DWTR hinders its widespread use. The present study examined the ecotoxicity of dewatered aluminum (Al) and iron (Fe) DWTR leachates to a green alga, Chlorella vulgaris. Data from the variations of cell density and chlorophyll a content suggested that algal growth in DWTR leachates was inhibited. The algal cellular oxidation stress was initially induced but completely eliminated within 72 h by antioxidant enzymes. The expression of three photosynthesis-related algae genes (psaB, psbC, and rbcL) also temporarily decreased (within 72 h). Moreover, the algal cells showed intact cytomembranes after exposure to DWTR leachates. Further investigation confirmed that inhibition of algal growth was due to DWTR-induced phosphorus (P) deficiency in growth medium, rather than potentially toxic contaminants (e.g. copper and Al) contained in DWTR. Interestingly, the leachates could potentially promote algal growth via increasing the supply of new components (e.g. calcium, kalium, magnesium, and ammonia nitrogen) from DWTR. In summary, based on the algae toxicity test, the dewatered Fe/Al DWTR was nontoxic and its environment recycling does not represent an ecotoxicological risk to algae.

Ecotoxicological impact of Zequanox®, a novel biocide, on selected non-target Irish aquatic species.

Science.gov (United States)

Meehan, Sara; Shannon, Adam; Gruber, Bridget; Rackl, Sarahann M; Lucy, Frances E

2014-09-01

Effective, species-specific zebra mussel control is needed urgently for Ireland׳s freshwater bodies, which became infested with non-native zebra mussels in the 1990s. Zequanox®, a newly commercialized product for zebra and quagga mussel control, is composed of dead Pseudomonas fluorescens CL 145A cells. This paper describes ecotoxicology tests on three representative native Irish freshwater species: Anodonta (duck mussel), Chironomus plumosus (non-biting midge), and Austropotamobius pallipes (white-clawed crayfish). The species were exposed to Zequanox in a 72-h static renewal toxicity test at concentrations of 100-750mg active ingredient per liter (mga.i./L). Water quality parameters were measured every 12-24h before and after water and product renewal. After 72h, endpoints were reported as LC10, LC50, and LC100. The LC50 values derived were (1) Anodonta: ≥500mga.i./L (2) C. plumosus: 1075mga.i./L, and (3) A. pallipes: ≥750mga.i./L. These results demonstrate that Zequanox does not negatively affect these organisms at the concentration required for >80percent zebra mussel mortality (150mg a.i/L) and the maximum allowable treatment concentration in the United Sates (200mga.i./L). They also show the overall species-specificity of Zequanox, and support its use in commercial facilities and open waters. Copyright © 2014 Elsevier Inc. All rights reserved.

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide

DEFF Research Database (Denmark)

Kissling, W. Daniel; Dalby, Lars; Fløjgaard, Camilla

2014-01-01

, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (“MammalDIET”). Diet information was digitized from two global...... species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally...... information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (“Animal”, “Mammal...

Biological test methods for the ecotoxicological characterization of wastes. Final report; Biologische Testerverfahren zur oekotoxikologischen Charakterisierung von Abfaellen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Becker, Roland [Bundesanstalt fuer Materialforschung, Berlin (Germany); Donnevert, Gerhild [Fachhochschule Giessen-Friedberg (Germany). FB MNI; Roembke, Joerg [ECT Oekotoxikologie GmbH, Floersheim am Main (Germany)

2007-11-15

battery the acceptance rate varied between 74.1% (Algae test) and 92.6% (Daphnia test). Methodologically, no problems occurred but further guidance on moisture determination in the terrestrial tests as well as details concerning reference testing and data evaluation for several tests are needed. Independently which test system is considered, SOI always caused the lowest effects and WOO was most toxic, while the EC50 values of INC show an intermediate toxicity. Among the aquatic tests, daphnids and one algal species were the most sensitive ones, while plants were always more sensitive than earthworms in the solid waste samples. Based on the test results from additional tests proposals for the modification of the existing basic test battery could be made. For example, the earthworm acute test could be replaced by another soil invertebrate test with higher sensitivity. Further work performed in parallel to the ring test improves waste testing considerably (e.g. the use of artificial soil as control substrate). A comparison of the ring test results with literature data published so far revealed a good agreement. The results of this ring test support confirm that a combination of a battery of biological tests and chemical residue analysis is needed for an ecotoxicological characterization of wastes. With small modifications proposed in this report the basic test battery is considered to be well suitable for the hazard and risk assessment of wastes. Further, probably multi-variate evaluation of the ring test results will improve the identification of those tests most qualified for the ecotoxicological characterization of wastes. Finally, the experiences made in the ring test support also the proposals made in CEN guideline 14735 (2005) concerning the performance of such tests. (orig.)

Effect of heterogeneity of human population in cell radiosensitivity on the extrapolation of dose-response relationships to low doses

International Nuclear Information System (INIS)

Filyushkin, I.V.; Bragin, Yu.N.; Khandogina, E.K.

1989-01-01

Presented are the results of an investigation of the dose-response relationship for the yield of chromosome aberrations in peripheral blood lymphocytes of persons with some hereditary diseases which represent the high risk group with respect to the increased incidence of malignant tumors and decreased life span. Despite substantially different absolute radiosensitivities of chromosomes, the variations of the alpha/beta ratio determining the extrapolation of experimental dose-response relationships to low doses did not prove to be too high, the mean deviation from the control being 15%. This points to the possible practical use of the dose-response relationships averaged over the human population as a whole

The 2015 Annual Meeting of SETAC German Language Branch in Zurich (7-10 September, 2015): ecotoxicology and environmental chemistry-from research to application

OpenAIRE

Werner, Inge; Aldrich, Annette; Becker, Benjamin; Becker, Dennis; Brinkmann, Markus; Burkhardt, Michael; Caspers, Norbert; Campiche, Sophie; Chèvre, Nathalie; Düring, Rolf-Alexander; Escher, Beate I.; Fischer, Fabian; Giebner, Sabrina; Heye, Katharina; Hollert, Henner

2016-01-01

This report provides a brief review of the 20th annual meeting of the German Language Branch of the Society of Environmental Toxicology and Chemistry (SETAC GLB) held from September 7th to 10th 2015 at ETH (Swiss Technical University) in Zurich, Switzerland. The event was chaired by Inge Werner, Director of the Swiss Centre for Applied Ecotoxicology (Ecotox Centre) Eawag-EPFL, and organized by a team from Ecotox Centre, Eawag, Federal Office of the Environment, Federal Office of Agriculture, ...

Straightening the Hierarchical Staircase for Basis Set Extrapolations: A Low-Cost Approach to High-Accuracy Computational Chemistry

Science.gov (United States)

Varandas, António J. C.

2018-04-01

Because the one-electron basis set limit is difficult to reach in correlated post-Hartree-Fock ab initio calculations, the low-cost route of using methods that extrapolate to the estimated basis set limit attracts immediate interest. The situation is somewhat more satisfactory at the Hartree-Fock level because numerical calculation of the energy is often affordable at nearly converged basis set levels. Still, extrapolation schemes for the Hartree-Fock energy are addressed here, although the focus is on the more slowly convergent and computationally demanding correlation energy. Because they are frequently based on the gold-standard coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)], correlated calculations are often affordable only with the smallest basis sets, and hence single-level extrapolations from one raw energy could attain maximum usefulness. This possibility is examined. Whenever possible, this review uses raw data from second-order Møller-Plesset perturbation theory, as well as CCSD, CCSD(T), and multireference configuration interaction methods. Inescapably, the emphasis is on work done by the author's research group. Certain issues in need of further research or review are pinpointed.

Hematological responses after inhaling 238PuO2: An extrapolation from beagle dogs to humans

International Nuclear Information System (INIS)

Scott, B.R.; Muggenburg, B.A.; Welsh, C.A.; Angerstein, D.A.

1994-01-01

The alpha emitter plutonium-238 ( 238 Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to 238 PuO 2 have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of 238 Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled 238 PuO 2 on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting 238 PuO 2 particles and to extrapolate results to humans

Contribution for tier 1 of the ecological risk assessment of Cunha Baixa uranium mine (Central Portugal): II. Soil ecotoxicological screening

International Nuclear Information System (INIS)

Antunes, S.C.; Castro, B.B.; Pereira, R.; Goncalves, F.

2008-01-01

This study presents the first ecotoxicological data concerning the soils of the area surrounding the Cunha Baixa uranium mine. Our main goal was to categorise soils from the area based on their toxicity profiles using a battery of cost- and time-effective bioassays (elutriate approach - Microtox (registered) and Daphnia acute tests; whole-soil approach - Microtox (registered) and avoidance assays with Eisenia andrei), as a part of tier 1 of an ongoing Environmental Risk Assessment. No acute toxicity was found for any of the 10 sites/soils using Microtox (registered) or Daphnia. On the contrary, the behavioural response of E. andrei was found to be an extremely sensitive endpoint, allowing the discrimination of highly to moderately toxic soils based on their toxicity profiles (as a function of soil concentration). Soils exhibiting highest toxicity corresponded to areas subjected to runoffs or sludge deposition from the aquatic effluent, while non-toxic soils were farthest to the mine. Data obtained in avoidance assays strengthen the previous evaluation of risks based on chemical data and supported decisions about proceeding for tier 2

BACTERIAL COMMUNITY DYNAMICS AND ECOTOXICOLOGICAL ASSESSMENT DURING BIOREMEDIATION OF SOILS CONTAMINATED BY BIODIESEL AND DIESEL/BIODIESEL BLENDS.

Science.gov (United States)

Matos, G I; Junior, C S; Oliva, T C; Subtil, D F; Matsushita, L Y; Chaves, A L; Lutterbach, M T; Sérvulo, E F; Agathos, S N; Stenuit, B

2015-01-01

The gradual introduction of biodiesel in the Brazilian energy landscape has primarily occurred through its blending with conventional petroleum diesel (e.g., B20 (20% biodiesel) and B5 (5% biodiesel) formulations). Because B20 and lower-level blends generally do not require engine modifications, their use as transportation fuel is increasing in the Brazilian distribution networks. However, the environmental fate of low-level biodiesel blends and pure biodiesel (B100) is poorly understood and the ecotoxicological-safety endpoints of biodiesel-contaminated environments are unknown. Using laboratory microcosms consisting of closed reactor columns filled with clay loam soil contaminated with pure biodiesel (EXPB100) and a low-level blend (EXPB5) (10% w/v), this study presents soil ecotoxicity assessement and dynamics of culturable heterotrophic bacteria. Most-probable-number (MPN) procedures for enumeration of bacteria, dehydrogenase assays and soil ecotoxicological tests using Eisenia fetida have been performed at different column depths over the course of incubation. After 60 days of incubation, the ecotoxicity of EXPB100-derived samples showed a decrease from 63% of mortality to 0% while EXPB5-derived samples exhibited a reduction from 100% to 53% and 90% on the top and at the bottom of the reactor column, respectively. The dehydrogenase activity of samples from EXPB100 and EXPB5 increased significantly compared to pristine soil after 60 days of incubation. Growth of aerobic bacterial biomass was only observed on the top of the reactor column while the anaerobic bacteria exhibited significant growth at different column depths in EXPB100 and EXPB5. These preliminary results suggest the involvement of soil indigenous microbiota in the biodegradation of biodiesel and blends. However, GC-FID analyses for quantification of fatty acid methyl esters (FAMEs) and aliphatic hydrocarbons and targeted sequencing of 16S rRNA tags using illumina platforms will provide important

Extrapolation for exposure duration in oral toxicity: A quantitative analysis of historical toxicity data

NARCIS (Netherlands)

Groeneveld, C.N.; Hakkert, B.C.; Bos, P.M.J.; Heer, C.de

2004-01-01

For human risk assessment, experimental data often have to be extrapolated for exposure duration, which is generally done by means of default values. The purpose of the present study was twofold. First, to derive a statistical distribution for differences in exposure duration that can be used in a

Theoretically exploring direct and indirect chemical effects across ecological and exposure scenarios using mechanistic fate and effects modelling

NARCIS (Netherlands)

Laender, de F.; Morselli, M.; Baveco, H.; Brink, van den P.J.; Guardo, Di A.

2015-01-01

Predicting ecosystem response to chemicals is a complex problem in ecotoxicology and a challenge for risk assessors. The variables potentially influencing chemical fate and exposure define the exposure scenario while the variables determining effects at the ecosystem level define the ecological

Ecotoxicological evaluation of propranolol hydrochloride and losartan potassium to Lemna minor L. (1753) individually and in binary mixtures.

Science.gov (United States)

Godoy, Aline A; Kummrow, Fábio; Pamplin, Paulo Augusto Z

2015-07-01

Antihypertensive pharmaceuticals, including the beta-blockers, are one of the most detected therapeutic classes in the environment. The ecotoxicity of propranolol hydrochloride and losartan potassium was evaluated, both individually and combined in a binary mixture, by using the Lemna minor growth inhibition test. The endpoints evaluated in the single-pharmaceutical tests were frond number, total frond area and fresh weight. For the evaluation of the mixture toxicity, the selected endpoint was frond number. Water quality criteria values (WQC) were derived for the protection of freshwater and saltwater pelagic communities regarding the effects induced by propranolol and losartan using ecotoxicological data from the literature, including our data. The risks associated with both pharmaceutical effects on non-target organisms were quantified through the measured environmental concentration (MEC)/predicted-no-effect concentration (PNEC) ratios. For propranolol, the total frond area was the most sensitive endpoint (EC50 = 77.3 mg L(-1)), while for losartan there was no statistically significant difference between the endpoints. Losartan is only slightly more toxic than propranolol. Both concentration addition and independent action models overestimated the mixture toxicity of the pharmaceuticals at all the effect concentration levels evaluated. The joint action of both pharmaceuticals showed an antagonistic interaction to L. minor. Derived WQC assumed lower values for propranolol than for losartan. The MEC/PNEC ratios showed that propranolol may pose a risk for the most sensitive aquatic species, while acceptable risks posed by losartan were estimated for most of aquatic matrices. To the authors knowledge these are the first data about losartan toxicity for L. minor.

Measurement of the surface field on open magnetic samples by the extrapolation method

Czech Academy of Sciences Publication Activity Database

Perevertov, Oleksiy

2005-01-01

Roč. 76, - (2005), 104701/1-104701/7 ISSN 0034-6748 R&D Projects: GA ČR(CZ) GP202/04/P010; GA AV ČR(CZ) 1QS100100508 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic field measurement * extrapolation * air gaps * magnetic permeability Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.235, year: 2005

The chronic toxicity of molybdate to marine organisms. I. Generating reliable effects data

International Nuclear Information System (INIS)

Heijerick, D.G.; Regoli, L.; Stubblefield, W.

2012-01-01

A scientific research program was initiated by the International Molybdenum Association (IMOA) which addressed identified gaps in the environmental toxicity data for the molybdate ion (MoO 4 2− ). These gaps were previously identified during the preparation of EU-REACH-dossiers for different molybdenum compounds (European Union regulation on Registration, Evaluation, Authorization and Restriction of Chemical substances; EC, 2006). Evaluation of the open literature identified few reliable marine ecotoxicological data that could be used for deriving a Predicted No-Effect Concentration (PNEC) for the marine environment. Rather than calculating a PNEC marine using the assessment factor methodology on a combined freshwater/marine dataset, IMOA decided to generate sufficient reliable marine chronic data to permit derivation of a PNEC by means of the more scientifically robust species sensitivity distribution (SSD) approach (also called the statistical extrapolation approach). Nine test species were chronically exposed to molybdate (added as sodium molybdate dihydrate, Na 2 MoO 4 ·2H 2 O) according to published standard testing guidelines that are acceptable for a broad range of regulatory purposes. The selected test organisms were representative for typical marine trophic levels: micro-algae/diatom (Phaeodactylum tricornutum, Dunaliella tertiolecta), macro-alga (Ceramium tenuicorne), mysids (Americamysis bahia), copepod (Acartia tonsa), fish (Cyprinodon variegatus), echinoderms (Dendraster exentricus, Strongylocentrotus purpuratus) and molluscs (Mytilus edulis, Crassostrea gigas). Available NOEC/EC 10 levels ranged between 4.4 mg Mo/L (blue mussel M. edulis) and 1174 mg Mo/L (oyster C. gigas). Using all available reliable marine chronic effects data that are currently available, a HC 5,50% (median hazardous concentration affecting 5% of the species) of 5.74 (mg Mo)/L was derived with the statistical extrapolation approach, a value that can be used for national and

Extrapolation of bulk rock elastic moduli of different rock types to high pressure conditions and comparison with texture-derived elastic moduli

Science.gov (United States)

Ullemeyer, Klaus; Lokajíček, Tomás; Vasin, Roman N.; Keppler, Ruth; Behrmann, Jan H.

2018-02-01

In this study elastic moduli of three different rock types of simple (calcite marble) and more complex (amphibolite, micaschist) mineralogical compositions were determined by modeling of elastic moduli using texture (crystallographic preferred orientation; CPO) data, experimental investigation and extrapolation. 3D models were calculated using single crystal elastic moduli, and CPO measured using time-of-flight neutron diffraction at the SKAT diffractometer in Dubna (Russia) and subsequently analyzed using Rietveld Texture Analysis. To define extrinsic factors influencing elastic behaviour, P-wave and S-wave velocity anisotropies were experimentally determined at 200, 400 and 600 MPa confining pressure. Functions describing variations of the elastic moduli with confining pressure were then used to predict elastic properties at 1000 MPa, revealing anisotropies in a supposedly crack-free medium. In the calcite marble elastic anisotropy is dominated by the CPO. Velocities continuously increase, while anisotropies decrease from measured, over extrapolated to CPO derived data. Differences in velocity patterns with sample orientation suggest that the foliation forms an important mechanical anisotropy. The amphibolite sample shows similar magnitudes of extrapolated and CPO derived velocities, however the pattern of CPO derived velocity is closer to that measured at 200 MPa. Anisotropy decreases from the extrapolated to the CPO derived data. In the micaschist, velocities are higher and anisotropies are lower in the extrapolated data, in comparison to the data from measurements at lower pressures. Generally our results show that predictions for the elastic behavior of rocks at great depths are possible based on experimental data and those computed from CPO. The elastic properties of the lower crust can, thus, be characterized with an improved degree of confidence using extrapolations. Anisotropically distributed spherical micro-pores are likely to be preserved, affecting

Lethal and sublethal endpoints observed for Artemia exposed to two reference toxicants and an ecotoxicological concern organic compound.

Science.gov (United States)

Manfra, Loredana; Canepa, Sara; Piazza, Veronica; Faimali, Marco

2016-01-01

Swimming speed alteration and mortality assays with the marine crustacean Artemia franciscana were carried out. EC50 and LC50 values after 24-48h exposures were calculated for two reference toxicants, copper sulphate pentahydrate (CuSO4·5H2O) and Sodium Dodecyl Sulphate (SDS), and an ecotoxicological concern organic compound, Diethylene Glycol (DEG). Different end-points have been evaluated, in order to point out their sensitivity levels. The swimming speed alteration (SSA) was compared to mortality values and also to the hatching rate inhibition (literature data). SSA resulted to be more sensitive than the mortality and with a sensitivity comparable to (or even higher than) the hatching rate endpoint. Copyright © 2015 Elsevier Inc. All rights reserved.

Short-Term Forecasting of Urban Storm Water Runoff in Real-Time using Extrapolated Radar Rainfall Data

DEFF Research Database (Denmark)

Thorndahl, Søren Liedtke; Rasmussen, Michael R.

2013-01-01

Model based short-term forecasting of urban storm water runoff can be applied in realtime control of drainage systems in order to optimize system capacity during rain and minimize combined sewer overflows, improve wastewater treatment or activate alarms if local flooding is impending. A novel onl....... The radar rainfall extrapolation (nowcast) limits the lead time of the system to two hours. In this paper, the model set-up is tested on a small urban catchment for a period of 1.5 years. The 50 largest events are presented....... online system, which forecasts flows and water levels in real-time with inputs from extrapolated radar rainfall data, has been developed. The fully distributed urban drainage model includes auto-calibration using online in-sewer measurements which is seen to improve forecast skills significantly...

Potential ecotoxicological significance of elevated concentrations of strontium in eggshells of passerine birds

Science.gov (United States)

Mora, Miguel A.; Taylor, Robert J.; Brattin, Bryan L.

2007-01-01

We investigated the occurrence and potential ecotoxicological significance of elevated concentrations of strontium (Sr) in eggshells of nine passerine birds from four regions in Arizona. Concentrations of Sr in eggshells ranged from 70 to 1360 µg g−1 dry weight (overall mean  =  684 ± 345 SD µg g−1 dw) for the four regions. 23% of the eggshells had Sr concentrations greater than 1000 µg g−1 dw. To our knowledge, these are among the highest levels of Sr that have been reported in bird eggshells in North America. Of the nine species, Brown-headed Cowbirds (Molothrus ater) had the greatest concentrations of Sr. There was a significant positive correlation between Sr and calcium (Ca), and between barium (Ba) and Ca. Ca, Sr, and Ba interact with each other and can exert similar chemical and pharmacological effects. Mean (n ≥ 3) eggshell∶egg ratios for Sr varied with species and ranged from 6.1∶1 to 40.2∶1; ratios for individual eggs reached 92.7∶1. Mean Sr/Ca values ranged from 1.3 × 10−3 to 3.0 × 10−3 and mean eggshell thickness ranged from 83 ± 6 to 120 ± 9 µm for all species. Eggshell thickness was not significantly correlated with Sr for any species but tended to increase with Sr concentrations. We postulate that high concentrations of Sr in the shell could affect later-stage embryos by possible interference with Ca metabolism and bone growth, resulting in reduced hatching success and potential minor beak deformities.

Ecotoxicological impact of highway runoff using brown trout (Salmo trutta L.) as an indicator model.

Science.gov (United States)

Meland, Sondre; Salbu, Brit; Rosseland, Bjørn Olav

2010-03-01

The ecotoxicological impact of highway runoff on brown trout (Salmo trutta L.) was studied in an in situ experiment consisting of four 24 h simulated runoff episodes. Fish were maintained in 5 tanks and exposed to highway runoff from a sedimentation pond close to E6 outside the city of Oslo, Norway. The tanks had the following contaminant loadings during the episodes: stream water (control), pond inlet, pond outlet, pond inlet + stream water and pond outlet + stream water. Opposite to road salt and compared to earlier findings, the first two episodes had rather low concentrations of trace metals, hydrocarbons and polycyclic aromatic hydrocarbons. A heavy rainfall before episode 3 increased the concentrations of all the contaminants except road salt which was diluted. In addition, lowered oxygen levels led to hypoxic conditions. Overall the fish exposed to highway runoff had, compared to the control fish, higher concentrations of trace metals in gills and liver, increased activity of the antioxidant defense system represented by superoxide dismutase, catalase and metallothionein, problems with the regulation of plasma Cl and Na, as well as increased levels of blood glucose and pCO(2). Finally, this seemed to affect the metabolism of the fish through reduced condition factor. The observed effects were likely caused by multiple stressors and not by a single contaminant. The sedimentation pond clearly reduced the toxicity of the highway runoff. But even in the least polluted exposure tank (pond outlet + stream water) signs of physiological disturbances were evident.

Microphytobenthos in ecotoxicology: a review of the use of marine benthic diatoms in bioassays.

Science.gov (United States)

Araújo, Cristiano V M; Blasco, Julián; Moreno-Garrido, Ignacio

2010-08-01

Contamination in coastal zones is an increasing problem that adversely affects biological diversity and the functioning of coastal ecosystems. Sediment is an important compartment of these zones since large quantities of diverse contaminants can accumulate there. Whole-sediment toxicity assays are of increasing importance, and several assay methods using mainly invertebrates have been developed. However, an important part of the benthic community, the microphytobenthos (represented principally by benthic diatoms and cyanobacteria), has surprisingly been neglected. Recently, comprehensive studies have been conducted using benthic marine microalgae with the object of establishing a toxicity assay method for sediment samples. The main results published to date in the literature and obtained by our own team have been compiled and are discussed in this review. The value and feasibility of using certain organisms of the microphytobenthos group in ecotoxicology studies are also discussed, and a sediment quality guideline based on multivariate procedure has been derived from data obtained in previous studies. Finally, future perspectives for research in this field are discussed. Copyright 2010 Elsevier Ltd. All rights reserved.

Development of criteria for an ecotoxicological examination procedure by differentially high integrated parts of aquatic model ecosystems and mathematical models. Final report

International Nuclear Information System (INIS)

Huber, W.; Zieris, F.J.; Lay, J.P.; Weiss, K.; Brueggemann, R.; Benz, J.

1994-01-01

It is difficult to assess the risks of environmental toxicants, especially when they have to be extrapolated from laboratory datas. Therefore efforts are made to determine the potential hazards of chemicals with the help of artificial ecosystems or parts of them. These kinds of test systems are similar to the structure and function of natural ecosystems and therefore allow to make representative extrapolations to real nature. As a disadvantage they are expensive and not yet standardized. To be accepted for the risk assessment of chemicals it was attempted to standardize artificial aquatic ecosystems in this project. It was tried to minimize the costs of the testing procedures by using a mathematical model simulating artificial littoral ecosystems. With increasing complexity of the system a better description of expected effects caused by a substance in environment can be given. With the help of outdoor ecosystems the threshold concentration of a chemical could be determined that is not likely to affect an aquatic ecosystem. Further we succeeded in providing a prototype modeling the effects in the microcosms used in our experiments. This model is able to approximately describe the behavior of macrophytes, algae, and secondary consumers in uncontaminated and contaminated systems (with the test chemical atrazine). (orig.) [de

Evaluating In Vitro-In Vivo Extrapolation of Toxicokinetics.

Science.gov (United States)

Wambaugh, John F; Hughes, Michael F; Ring, Caroline L; MacMillan, Denise K; Ford, Jermaine; Fennell, Timothy R; Black, Sherry R; Snyder, Rodney W; Sipes, Nisha S; Wetmore, Barbara A; Westerhout, Joost; Setzer, R Woodrow; Pearce, Robert G; Simmons, Jane Ellen; Thomas, Russell S

2018-05-01

Prioritizing the risk posed by thousands of chemicals potentially present in the environment requires exposure, toxicity, and toxicokinetic (TK) data, which are often unavailable. Relatively high throughput, in vitro TK (HTTK) assays and in vitro-to-in vivo extrapolation (IVIVE) methods have been developed to predict TK, but most of the in vivo TK data available to benchmark these methods are from pharmaceuticals. Here we report on new, in vivo rat TK experiments for 26 non-pharmaceutical chemicals with environmental relevance. Both intravenous and oral dosing were used to calculate bioavailability. These chemicals, and an additional 19 chemicals (including some pharmaceuticals) from previously published in vivo rat studies, were systematically analyzed to estimate in vivo TK parameters (e.g., volume of distribution [Vd], elimination rate). For each of the chemicals, rat-specific HTTK data were available and key TK predictions were examined: oral bioavailability, clearance, Vd, and uncertainty. For the non-pharmaceutical chemicals, predictions for bioavailability were not effective. While no pharmaceutical was absorbed at less than 10%, the fraction bioavailable for non-pharmaceutical chemicals was as low as 0.3%. Total clearance was generally more under-estimated for nonpharmaceuticals and Vd methods calibrated to pharmaceuticals may not be appropriate for other chemicals. However, the steady-state, peak, and time-integrated plasma concentrations of nonpharmaceuticals were predicted with reasonable accuracy. The plasma concentration predictions improved when experimental measurements of bioavailability were incorporated. In summary, HTTK and IVIVE methods are adequately robust to be applied to high throughput in vitro toxicity screening data of environmentally relevant chemicals for prioritizing based on human health risks.

ECOTOXICOLOGICAL EFFECTS OF BIODIESEL IN THE SOIL

Directory of Open Access Journals (Sweden)

Małgorzata Hawrot-Paw

2015-11-01

Full Text Available The paper analysed the toxic effect of the presence of biodiesel in the soil. The study involved tests with microorganisms that evaluated changes in their number and activity, and phytotoxicity tests with garden cress (Lepidium sativum and spring barley (Hordeum vulgare. Biodiesel produced in laboratory conditions and biofuel purchased at a petrol station were introduced to the soil. Two levels of contamination were used – 1% and 5% (per dry mass of the soil. Based on the results, it was discovered that biofuels both stimulated and reduced the number and activity of microorganisms. The changes observed depended on the type of biofuel and, most often, on its dose. Laboratory biodiesel exhibited more toxic effects, especially for actinobacteria and fungi. The tested plants showed diverse sensitivity to the presence of biodiesel. Given the determined value of the germination index, laboratory biodiesel was more toxic to spring barley and commercial biofuel to garden cress. In both cases, toxicity increased with an increase in the amount of biofuel.

Human risk assessment of dermal and inhalation exposures to chemicals assessed by route-to-route extrapolation: the necessity of kinetic data.

Science.gov (United States)

Geraets, Liesbeth; Bessems, Jos G M; Zeilmaker, Marco J; Bos, Peter M J

2014-10-01

In toxicity testing the oral route is in general the first choice. Often, appropriate inhalation and dermal toxicity data are absent. Risk assessment for these latter routes usually has to rely on route-to-route extrapolation starting from oral toxicity data. Although it is generally recognized that the uncertainties involved are (too) large, route-to-route extrapolation is applied in many cases because of a strong need of an assessment of risks linked to a given exposure scenario. For an adequate route-to-route extrapolation the availability of at least some basic toxicokinetic data is a pre-requisite. These toxicokinetic data include all phases of kinetics, from absorption (both absorbed fraction and absorption rate for both the starting route and route of interest) via distribution and biotransformation to excretion. However, in practice only differences in absorption between the different routes are accounted for. The present paper demonstrates the necessity of route-specific absorption data by showing the impact of its absence on the uncertainty of the human health risk assessment using route-to-route extrapolation. Quantification of the absorption (by in vivo, in vitro or in silico methods), particularly for the starting route, is considered essential. Copyright © 2014 Elsevier Inc. All rights reserved.

Potential application of ecological models in the European environmental risk assessment of chemicals. I. Review of protection goals in EU directives and regulations.

Science.gov (United States)

Hommen, Udo; Baveco, J M Hans; Galic, Nika; van den Brink, Paul J

2010-07-01

Several European directives and regulations address the environmental risk assessment of chemicals. We used the protection of freshwater ecosystems against plant protection products, biocidal products, human and veterinary pharmaceuticals, and other chemicals and priority substances under the Water Framework Directive as examples to explore the potential of ecological effect models for a refined risk assessment. Our analysis of the directives, regulations, and related guidance documents lead us to distinguish the following 5 areas for the application of ecological models in chemical risk assessment: 1) Extrapolation of organism-level effects to the population level: The protection goals are formulated in general terms, e.g., avoiding "unacceptable effects" or "adverse impact" on the environment or the "viability of exposed species." In contrast, most of the standard ecotoxicological tests provide data only on organism-level endpoints and are thus not directly linked to the protection goals which focus on populations and communities. 2) Extrapolation of effects between different exposure profiles: Especially for plant protection products, exposure profiles can be very variable and impossible to cover in toxicological tests. 3) Extrapolation of recovery processes: As a consequence of the often short-term exposures to plant protection products, the risk assessment is based on the community recovery principle. On the other hand, assessments under the other directives assume a more or less constant exposure and are based on the ecosystem threshold principle. 4) Analysis and prediction of indirect effects: Because effects on 1 or a few taxa might have consequences on other taxa that are not directly affected by the chemical, such indirect effects on communities have to be considered. 5) Prediction of bioaccumulation within food chains: All directives take the possibility of bioaccumulation, and thus secondary poisoning within the food chain, into account. (c) 2010 SETAC.

Financial research support for ecotoxicology and environmental chemistry in Germany. Results of an online survey; Foerdersituation oekotoxikologischer und umweltchemischer Forschung in Deutschland. Ergebnisse einer Online-Befragung

Energy Technology Data Exchange (ETDEWEB)

Hollert, Henner; Schiwy, Andreas [RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research (Biology V), Aachen (Germany); Filser, Juliane [University of Bremen, UFT, Department of General and Theoretical Ecology, Bremen (Germany); Haeussling, Roger [RWTH Aachen University, Sociology of Technology and Organization, Institute of Sociology, Aachen (Germany); Hein, Michaela [Helmholtz Centre for Environmental Research - UFZ, CITE (Chemicals In The Environment), Department Bioanalytical Ecotoxicology, Leipzig (Germany); Matthies, Michael [University of Osnabrueck, Institute for Environmental System Research, Osnabrueck (Germany); Oehlmann, Joerg [Goethe University Frankfurt am Main, Department Aquatic Ecotoxicology, Institute for Ecology, Evolution and Diversity, Frankfurt am Main (Germany); Ratte, Hans-Toni; Ross-Nickoll, Martina; Schaeffer, Andreas [RWTH Aachen University, Chair for Environmental Biology and Chemodynamics, Institute for Environmental Research (Biology V), Aachen (Germany); Scheringer, Martin [ETH Zuerich, HCI G 127, Safety and Environmental Technology Group, Zuerich (Switzerland)

2011-12-15

In recent years several initiatives addressed the inadequate financial support of pollutant-related environmental research in the Federal Republic of Germany. For an objective analysis about the research funding in ecotoxicology and environmental chemistry in Germany, an anonymous online survey was prepared. With support of the Society of Environmental Toxicology and Chemistry (SETAC) - German Language Branch and the German Chemical Society (GDCh) - Division of Environmental Chemistry and Ecotoxicology an invitation to participate in the survey was sent to all members of these two major associations for ecotoxicology and environmental chemistry in Germany (D), Switzerland (CH) and Austria (A). Only senior staff from the areas academics, government and industry was invited. The present article introduces the results of the survey. It is segmented in a section on socio-economic characterization of the participants, a section on support of research by the DFG and a section on funding by other funding organizations. A total of 71 male and female scientists in senior positions from various areas participated in the survey. The results revealed that the participants are to be classified as having excellent records. 48.5 % of the respondents had submitted at least one research proposal to the DFG in the past, but one third actually received financial support by the DFG. 64% are not satisfied with the DFG support of pollutantrelated research, only 7 % are satisfied. It turned out that the research proposals are generally very heterogeneous and thus distributed to various units of the DFG with geosciences, water research and chemistry ranking highest, followed by biology and ecology. 91.2 % of the respondents indicated that they have submitted proposals for research funding to other funding institutions (except the DFG), and 83.6 % already have received appropriate external funding. 62.3 % of the scientists believe that overall support for chemicals-related research in

Dose and dose rate extrapolation factors for malignant and non-malignant health endpoints after exposure to gamma and neutron radiation

Energy Technology Data Exchange (ETDEWEB)

Tran, Van; Little, Mark P. [National Cancer Institute, Radiation Epidemiology Branch, Rockville, MD (United States)

2017-11-15

Murine experiments were conducted at the JANUS reactor in Argonne National Laboratory from 1970 to 1992 to study the effect of acute and protracted radiation dose from gamma rays and fission neutron whole body exposure. The present study reports the reanalysis of the JANUS data on 36,718 mice, of which 16,973 mice were irradiated with neutrons, 13,638 were irradiated with gamma rays, and 6107 were controls. Mice were mostly Mus musculus, but one experiment used Peromyscus leucopus. For both types of radiation exposure, a Cox proportional hazards model was used, using age as timescale, and stratifying on sex and experiment. The optimal model was one with linear and quadratic terms in cumulative lagged dose, with adjustments to both linear and quadratic dose terms for low-dose rate irradiation (<5 mGy/h) and with adjustments to the dose for age at exposure and sex. After gamma ray exposure there is significant non-linearity (generally with upward curvature) for all tumours, lymphoreticular, respiratory, connective tissue and gastrointestinal tumours, also for all non-tumour, other non-tumour, non-malignant pulmonary and non-malignant renal diseases (p < 0.001). Associated with this the low-dose extrapolation factor, measuring the overestimation in low-dose risk resulting from linear extrapolation is significantly elevated for lymphoreticular tumours 1.16 (95% CI 1.06, 1.31), elevated also for a number of non-malignant endpoints, specifically all non-tumour diseases, 1.63 (95% CI 1.43, 2.00), non-malignant pulmonary disease, 1.70 (95% CI 1.17, 2.76) and other non-tumour diseases, 1.47 (95% CI 1.29, 1.82). However, for a rather larger group of malignant endpoints the low-dose extrapolation factor is significantly less than 1 (implying downward curvature), with central estimates generally ranging from 0.2 to 0.8, in particular for tumours of the respiratory system, vasculature, ovary, kidney/urinary bladder and testis. For neutron exposure most endpoints, malignant and

Direct observations of the viscosity of Earth's outer core and extrapolation of measurements of the viscosity of liquid iron

International Nuclear Information System (INIS)

Smylie, D E; Brazhkin, Vadim V; Palmer, Andrew

2009-01-01

Estimates vary widely as to the viscosity of Earth's outer fluid core. Directly observed viscosity is usually orders of magnitude higher than the values extrapolated from high-pressure high-temperature laboratory experiments, which are close to those for liquid iron at atmospheric pressure. It turned out that this discrepancy can be removed by extrapolating via the widely known Arrhenius activation model modified by lifting the commonly used assumption of pressure-independent activation volume (which is possible due to the discovery that at high pressures the activation volume increases strongly with pressure, resulting in 10 2 Pa s at the top of the fluid core, and in 10 11 Pa s at its bottom). There are of course many uncertainties affecting this extrapolation process. This paper reviews two viscosity determination methods, one for the top and the other for the bottom of the outer core, the former of which relies on the decay of free core nutations and yields 2371 ± 1530 Pa s, while the other relies on the reduction in the rotational splitting of the two equatorial translational modes of the solid inner core oscillations and yields an average of 1.247 ± 0.035 Pa s. Encouraged by the good performance of the Arrhenius extrapolation, a differential form of the Arrhenius activation model is used to interpolate along the melting temperature curve and to find the viscosity profile across the entire outer core. The viscosity variation is found to be nearly log-linear between the measured boundary values. (methodological notes)

SU-F-T-64: An Alternative Approach to Determining the Reference Air-Kerma Rate from Extrapolation Chamber Measurements

International Nuclear Information System (INIS)

Schneider, T

2016-01-01

Purpose: Since 2008 the Physikalisch-Technische Bundesanstalt (PTB) has been offering the calibration of "1"2"5I-brachytherapy sources in terms of the reference air-kerma rate (RAKR). The primary standard is a large air-filled parallel-plate extrapolation chamber. The measurement principle is based on the fact that the air-kerma rate is proportional to the increment of ionization per increment of chamber volume at chamber depths greater than the range of secondary electrons originating from the electrode x_0. Methods: Two methods for deriving the RAKR from the measured ionization charges are: (1) to determine the RAKR from the slope of the linear fit to the so-called ’extrapolation curve’, the measured ionization charges Q vs. plate separations x or (2) to differentiate Q(x) and to derive the RAKR by a linear extrapolation towards zero plate separation. For both methods, correcting the measured data for all known influencing effects before the evaluation method is applied is a precondition. However, the discrepancy of their results is larger than the uncertainty given for the determination of the RAKR with both methods. Results: A new approach to derive the RAKR from the measurements is investigated as an alternative. The method was developed from the ground up, based on radiation transport theory. A conversion factor C(x_1, x_2) is applied to the difference of charges measured at the two plate separations x_1 and x_2. This factor is composed of quotients of three air-kerma values calculated for different plate separations in the chamber: the air kerma Ka(0) for plate separation zero, and the mean air kermas at the plate separations x_1 and x_2, respectively. The RAKR determined with method (1) yields 4.877 µGy/h, and with method (2) 4.596 µGy/h. The application of the alternative approach results in 4.810 µGy/h. Conclusion: The alternative method shall be established in the future.

WE-A-17A-01: Absorbed Dose Rate-To-Water at the Surface of a Beta-Emitting Planar Ophthalmic Applicator with a Planar, Windowless Extrapolation Chamber

Energy Technology Data Exchange (ETDEWEB)

Riley, A [of Wisconsin Medical Radiation Research Center, Madison, WI (United States); Soares, C [NIST (Retired), Gaithersburg, MD (United States); Micka, J; Culberson, W [University of Wisconsin Medical Radiation Research Center, Madison, WI (United States); DeWerd, L [University of WIMadison/ ADCL, Madison, WI (United States)

2014-06-15

Purpose: Currently there is no primary calibration standard for determining the absorbed dose rate-to-water at the surface of β-emitting concave ophthalmic applicators and plaques. Machining tolerances involved in the design of concave window extrapolation chambers are a limiting factor for development of such a standard. Use of a windowless extrapolation chamber avoids these window-machining tolerance issues. As a windowless extrapolation chamber has never been attempted, this work focuses on proof of principle measurements with a planar, windowless extrapolation chamber to verify the accuracy in comparison to initial calibration, which could be extended to the design of a hemispherical, windowless extrapolation chamber. Methods: The window of an extrapolation chamber defines the electrical field, aids in aligning the source parallel to the collector-guard assembly, and decreases the backscatter due to attenuation of lower electron energy. To create a uniform and parallel electric field in this research, the source was made common to the collector-guard assembly. A precise positioning protocol was designed to enhance the parallelism of the source and collector-guard assembly. Additionally, MCNP5 was used to determine a backscatter correction factor to apply to the calibration. With these issues addressed, the absorbed dose rate-to-water of a Tracerlab 90Sr planar ophthalmic applicator was determined using National Institute of Standards and Technology's (NIST) calibration formalism, and the results of five trials with this source were compared to measurements at NIST with a traditional extrapolation chamber. Results: The absorbed dose rate-to-water of the planar applicator was determined to be 0.473 Gy/s ±0.6%. Comparing these results to NIST's determination of 0.474 Gy/s yields a −0.6% difference. Conclusion: The feasibility of a planar, windowless extrapolation chamber has been demonstrated. A similar principle will be applied to developing a

Pollutant threshold concentration determination in marine ecosystems using an ecological interaction endpoint

International Nuclear Information System (INIS)

Wang, Changyou; Liang, Shengkang; Guo, Wenting; Yu, Hua; Xing, Wenhui

2015-01-01

The threshold concentrations of pollutants are determined by extrapolating single-species effect data to community-level effects. This assumes the most sensitive endpoint of the life cycle of individuals and the species sensitivity distribution from single-species toxic effect tests, thus, ignoring the ecological interactions. The uncertainties due to this extrapolation can be partially overcome using the equilibrium point of a customized ecosystem. This method incorporates ecological interactions and integrates the effects on growth, survival, and ingestion into a single effect measure, the equilibrium point excursion in the customized ecosystem, in order to describe the toxic effects on plankton. A case study showed that the threshold concentration of copper calculated with the endpoint of the equilibrium point was 10 μg L −1 , which is significantly different from the threshold calculated with a single-species endpoint. The endpoint calculated using this method provides a more relevant measure of the ecological impact than any single individual-level endpoint. - Highlights: • Ecotoxicological effect of exposure to copper was tested on a customized ecosystem. • Equilibrium point of biomasses in the customized ecosystem was used as an endpoint. • Exposure–response relationship in a community level was built on equilibrium point. • A threshold concentration incorporating ecological interactions was derived. - The equilibrium biomass incorporating ecological interactions in a customized ecosystem was used as an endpoint to calculate the threshold concentration at a community level

Aquatic Ecotoxicity Testing of Nanoparticles—The Quest To Disclose Nanoparticle Effects

DEFF Research Database (Denmark)

Skjolding, Lars Michael; Sørensen, Sara Nørgaard; Hartmann, Nanna B.

2016-01-01

The number of products on the market containing engineered nanoparticles (ENPs) has increased significantly, and concerns have been raised regarding their ecotoxicological effects. Environmental safety assessments as well as relevant and reliable ecotoxicological data are required for the safe...... to ENPs in aquatic test systems. Filling this gap is not straightforward, because of the broad range of ENPs and the different behavior of ENPs compared to “ordinary” (dissolved) chemicals in the ecotoxicity test systems. The risk of generating false negatives, and false positives, in the currently used...... tests is high, and in most cases difficult to assess. This Review outlines some of the pitfalls in the aquatic toxicity testing of ENPs which may lead to misinterpretation of test results. Response types are also proposed to reveal potential nanoparticle effects in the aquatic test organisms....

Effect of heavy metals on marine Bacillus sp. and Flavobacterium sp.

Digital Repository Service at National Institute of Oceanography (India)

Nair, S.; LokaBharathi, P.A.; Chandramohan, D.

stream_size 10 stream_content_type text/plain stream_name Ecotoxicology_2_220.pdf.txt stream_source_info Ecotoxicology_2_220.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

Heavy metals in earthworms of Baden-Wuerttemberg. Pt. 2. Ecotoxicological assessment of soil; Schwermetalle in Regenwuermern Baden-Wuerttembergs. T. 2. Oekotoxikologische Bewertung des Bodens

Energy Technology Data Exchange (ETDEWEB)

Rahtkens, K.; Trenck, K.T. von der [Landesanstalt fuer Umwelt, Messungen und Naturschutz Baden-Wuerttemberg (LUBW), Karlsruhe (Germany)

2007-02-15

Goal and Scope. The heavy metal burden of the soil and of earth-worms from representative long-term forest observation plots has been measured since 1984 as one component of the media-embracing environmental monitoring network of the State of Baden-Wuerttemberg. These investigations are aimed at elucidating and assessing adverse effects of pollutants on the soil biocenosis. Methods. So-called characteristic curves for the metals Cd, Cu, Ni, Pb, and Zn were developed for the assessment. Earthworm toxicity data and background values in soil served as criteria. This procedure facilitates a comparative assessment of different pollutants. The mobility of the metals, which greatly influences their bioavailability and toxicity, was taken into account for the effects assessment. Results and Conclusion. Besides inventorying the heavy metals (Part 1), the question of threshold values for toxic reactions as well as for accumulation was raised. The metal concentrations were assessed in the soil with regard to its habitat function. The ecotoxicological assessment revealed that the heavy metal burden of the investigated plots lies within the background- or precautionary range, well below the screening value established here to indicate the effect threshold in earthworms. This result means that a pollution of the forest observation plots with the metals cadmium, copper, lead, nickel, and zinc is low or absent. Only the distribution of the lead content is centered slightly above background (but clearly below the toxicity threshold). This slight lead burden of the soil of the observation plots can be explained by emissions from motor vehicles. Investigations at sites that are contaminated with either chromium or copper or cadmium showed that an accumulation of these metals in the body of the worms can be observed only above a threshold concentration of several hundred micrograms of mobile metal per kilogram in the upper layer of the soil. Recommendations and Perspectives. The

Occurrence, fate and ecotoxicological assessment of pharmaceutically active compounds in wastewater and sludge from wastewater treatment plants in Chongqing, the Three Gorges Reservoir Area

Energy Technology Data Exchange (ETDEWEB)

Yan, Qing, E-mail: qyan2005@hotmail.com [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environments of Ministry of Education, Chongqing University, Chongqing 400045 (China); College of Geography Science and Tourism, Chongqing Normal University, Chongqing 400047 (China); Gao, Xu, E-mail: gaoxu@cqu.edu.cn [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environments of Ministry of Education, Chongqing University, Chongqing 400045 (China); Chen, You-Peng [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environments of Ministry of Education, Chongqing University, Chongqing 400045 (China); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China); Peng, Xu-Ya; Zhang, Yi-Xin; Gan, Xiu-Mei; Zi, Cheng-Fang [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environments of Ministry of Education, Chongqing University, Chongqing 400045 (China); Guo, Jin-Song [Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environments of Ministry of Education, Chongqing University, Chongqing 400045 (China); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China)

2014-02-01

The occurrence, removal and ecotoxicological assessment of 21 pharmaceutically active compounds (PhACs) including antibiotics, analgesics, antiepileptics, antilipidemics and antihypersensitives, were studied at four municipal wastewater treatment plants (WWTP) in Chongqing, the Three Gorges Reservoir Area. Individual treatment unit effluents, as well as primary and secondary sludge, were sampled and analyzed for the selected PhACs to evaluate their biodegradation, persistence and partitioning behaviors. PhACs were identified and quantified using high performance liquid chromatography/tandem mass spectrometry after solid-phase extraction. All the 21 analyzed PhACs were detected in wastewater and the target PhACs except acetaminophen, ibuprofen and gemfibrozil, were also found in sludge. The concentrations of the antibiotics and SVT were comparable to or even higher than those reported in developed countries, while the case of other target PhACs was opposite. The elimination of PhACs except acetaminophen was incomplete and a wide range of elimination efficiencies during the treatment were observed, i.e. from “negative removal” to 99.5%. The removal of PhACs was insignificant in primary and disinfection processes, and was mainly achieved during the biological treatment. Based on the mass balance analysis, biodegradation is believed to be the primary removal mechanism, whereas only about 1.5% of the total mass load of the target PhACs was removed by sorption. Experimentally estimated distribution coefficients (< 500 L/kg, with a few exceptions) also indicate that biodegradation/transformation was responsible for the removal of the target PhACs. Ecotoxicological assessment indicated that the environment concentrations of single compounds (including sulfadiazine, sulfamethoxazole, ofloxacin, azithromycin and erythromycin-H{sub 2}O) in effluent and sludge, as well as the mixture of the 21 detected PhACs in effluent, sludge and receiving water had a significant

An Extrapolation of a Radical Equation More Accurately Predicts Shelf Life of Frozen Biological Matrices.

Science.gov (United States)

De Vore, Karl W; Fatahi, Nadia M; Sass, John E

2016-08-01

Arrhenius modeling of analyte recovery at increased temperatures to predict long-term colder storage stability of biological raw materials, reagents, calibrators, and controls is standard practice in the diagnostics industry. Predicting subzero temperature stability using the same practice is frequently criticized but nevertheless heavily relied upon. We compared the ability to predict analyte recovery during frozen storage using 3 separate strategies: traditional accelerated studies with Arrhenius modeling, and extrapolation of recovery at 20% of shelf life using either ordinary least squares or a radical equation y = B1x(0.5) + B0. Computer simulations were performed to establish equivalence of statistical power to discern the expected changes during frozen storage or accelerated stress. This was followed by actual predictive and follow-up confirmatory testing of 12 chemistry and immunoassay analytes. Linear extrapolations tended to be the most conservative in the predicted percent recovery, reducing customer and patient risk. However, the majority of analytes followed a rate of change that slowed over time, which was fit best to a radical equation of the form y = B1x(0.5) + B0. Other evidence strongly suggested that the slowing of the rate was not due to higher-order kinetics, but to changes in the matrix during storage. Predicting shelf life of frozen products through extrapolation of early initial real-time storage analyte recovery should be considered the most accurate method. Although in this study the time required for a prediction was longer than a typical accelerated testing protocol, there are less potential sources of error, reduced costs, and a lower expenditure of resources. © 2016 American Association for Clinical Chemistry.

Testing a solar coronal magnetic field extrapolation code with the Titov–Démoulin magnetic flux rope model

International Nuclear Information System (INIS)

Jiang, Chao-Wei; Feng, Xue-Shang

2016-01-01

In the solar corona, the magnetic flux rope is believed to be a fundamental structure that accounts for magnetic free energy storage and solar eruptions. Up to the present, the extrapolation of the magnetic field from boundary data has been the primary way to obtain fully three-dimensional magnetic information about the corona. As a result, the ability to reliably recover the coronal magnetic flux rope is important for coronal field extrapolation. In this paper, our coronal field extrapolation code is examined with an analytical magnetic flux rope model proposed by Titov and Démoulin, which consists of a bipolar magnetic configuration holding a semi-circular line-tied flux rope in force-free equilibrium. By only using the vector field at the bottom boundary as input, we test our code with the model in a representative range of parameter space and find that the model field can be reconstructed with high accuracy. In particular, the magnetic topological interfaces formed between the flux rope and the surrounding arcade, i.e., the “hyperbolic flux tube” and “bald patch separatrix surface,” are also reliably reproduced. By this test, we demonstrate that our CESE–MHD–NLFFF code can be applied to recovering the magnetic flux rope in the solar corona as long as the vector magnetogram satisfies the force-free constraints. (paper)

Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination.

Science.gov (United States)

Pavlova, Viola; Nabe-Nielsen, Jacob; Dietz, Rune; Sonne, Christian; Grimm, Volker

2016-11-30

Polar bears (Ursus maritimus) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose-response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male-male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male-male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10-14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour. © 2016 The Author(s).

Characterization of an extrapolation chamber and radiochromic films for verifying the metrological coherence among beta radiation fields

International Nuclear Information System (INIS)

Castillo, Jhonny Antonio Benavente

2011-01-01

The metrological coherence among standard systems is a requirement for assuring the reliability of dosimetric quantities measurements in ionizing radiation field. Scientific and technologic improvements happened in beta radiation metrology with the installment of the new beta secondary standard BSS2 in Brazil and with the adoption of the internationally recommended beta reference radiations. The Dosimeter Calibration Laboratory of the Development Center for Nuclear Technology (LCD/CDTN), in Belo Horizonte, implemented the BSS2 and methodologies are investigated for characterizing the beta radiation fields by determining the field homogeneity, the accuracy and uncertainties in the absorbed dose in air measurements. In this work, a methodology to be used for verifying the metrological coherence among beta radiation fields in standard systems was investigated; an extrapolation chamber and radiochromic films were used and measurements were done in terms of absorbed dose in air. The reliability of both the extrapolation chamber and the radiochromic film was confirmed and their calibrations were done in the LCD/CDTN in 90 Sr/ 90 Y, 85 Kr and 147 Pm beta radiation fields. The angular coefficients of the extrapolation curves were determined with the chamber; the field mapping and homogeneity were obtained from dose profiles and isodose with the radiochromic films. A preliminary comparison between the LCD/CDTN and the Instrument Calibration Laboratory of the Nuclear and Energy Research Institute / Sao Paulo (LCI/IPEN) was carried out. Results with the extrapolation chamber measurements showed in terms of absorbed dose in air rates showed differences between both laboratories up to de -I % e 3%, for 90 Sr/ 90 Y, 85 Kr and 147 Pm beta radiation fields, respectively. Results with the EBT radiochromic films for 0.1, 0.3 and 0.15 Gy absorbed dose in air, for the same beta radiation fields, showed differences up to 3%, -9% and -53%. The beta radiation field mappings with

-Error Estimates of the Extrapolated Crank-Nicolson Discontinuous Galerkin Approximations for Nonlinear Sobolev Equations

Directory of Open Access Journals (Sweden)

Lee HyunYoung

2010-01-01

Full Text Available We analyze discontinuous Galerkin methods with penalty terms, namely, symmetric interior penalty Galerkin methods, to solve nonlinear Sobolev equations. We construct finite element spaces on which we develop fully discrete approximations using extrapolated Crank-Nicolson method. We adopt an appropriate elliptic-type projection, which leads to optimal error estimates of discontinuous Galerkin approximations in both spatial direction and temporal direction.

Ecotoxicological assessment of soils polluted with chemical waste from lindane production: Use of bacterial communities and earthworms as bioremediation tools.

Science.gov (United States)

Muñiz, Selene; Gonzalvo, Pilar; Valdehita, Ana; Molina-Molina, José Manuel; Navas, José María; Olea, Nicolás; Fernández-Cascán, Jesús; Navarro, Enrique

2017-11-01

An ecotoxicological survey of soils that were polluted with wastes from lindane (γ-HCH) production assessed the effects of organochlorine compounds on the metabolism of microbial communities and the toxicity of these compounds to a native earthworm (Allolobophora chlorotica). Furthermore, the bioremediation role of earthworms as facilitators of soil washing and the microbial degradation of these organic pollutants were also studied. Soil samples that presented the highest concentrations of ε-HCH, 2,4,6-trichlorophenol, pentachlorobenzene and γ-HCH were extremely toxic to earthworms in the short term, causing the death of almost half of the population. In addition, these soils inhibited the heterotrophic metabolic activity of the microbial community. These highly polluted samples also presented substances that were able to activate cellular detoxification mechanisms (measured as EROD and BFCOD activities), as well as compounds that were able to cause endocrine disruption. A few days of earthworm activity increased the extractability of HCH isomers (e.g., γ-HCH), facilitating the biodegradation of organochlorine compounds and reducing the intensity of endocrine disruption in soils that had low or medium contamination levels. Copyright © 2017 Elsevier Inc. All rights reserved.

Verification of absorbed dose rates in reference beta radiation fields: measurements with an extrapolation chamber and radiochromic film

International Nuclear Information System (INIS)

Reynaldo, S. R.; Benavente C, J. A.; Da Silva, T. A.

2015-10-01

Beta Secondary Standard 2 (Bss 2) provides beta radiation fields with certified values of absorbed dose to tissue and the derived operational radiation protection quantities. As part of the quality assurance, metrology laboratories are required to verify the reliability of the Bss-2 system by performing additional verification measurements. In the CDTN Calibration Laboratory, the absorbed dose rates and their angular variation in the 90 Sr/ 90 Y and 85 Kr beta radiation fields were studied. Measurements were done with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. In comparison to the certificate values provided by the Bss-2, absorbed dose rates measured with the extrapolation chamber differed from -1.4 to 2.9% for the 90 Sr/ 90 Y and -0.3% for the 85 Kr fields; their angular variation showed differences lower than 2% for incidence angles up to 40-degrees and it reached 11% for higher angles, when compared to ISO values. Measurements with the radiochromic film showed an asymmetry of the radiation field that is caused by a misalignment. Differences between the angular variations of absorbed dose rates determined by both dosimetry systems suggested that some correction factors for the extrapolation chamber that were not considered should be determined. (Author)

Direct activity determination of Mn-54 and Zn-65 by a non-extrapolation liquid scintillation method

CSIR Research Space (South Africa)

Simpson, BRS

2004-02-01

Full Text Available . The simple decay scheme exhibited by these radionuclides, with the emission of an energetic gamma ray, allows the absolute activity to be determined from 4pie-gamma data by direct calculation without the need for efficiency extrapolation. The method, which...

Bulk rock elastic moduli at high pressures, derived from the mineral textures and from extrapolated laboratory data

International Nuclear Information System (INIS)

Ullemeyer, K; Keppler, R; Lokajíček, T; Vasin, R N; Behrmann, J H

2015-01-01

The elastic anisotropy of bulk rock depends on the mineral textures, the crack fabric and external parameters like, e.g., confining pressure. The texture-related contribution to elastic anisotropy can be predicted from the mineral textures, the largely sample-dependent contribution of the other parameters must be determined experimentally. Laboratory measurements of the elastic wave velocities are mostly limited to pressures of the intermediate crust. We describe a method, how the elastic wave velocity trends and, by this means, the elastic constants can be extrapolated to the pressure conditions of the lower crust. The extrapolated elastic constants are compared to the texture-derived ones. Pronounced elastic anisotropy is evident for phyllosilicate minerals, hence, the approach is demonstrated for two phyllosilicate-rich gneisses with approximately identical volume fractions of the phyllosilicates but different texture types. (paper)

Application of the largest Lyapunov exponent and non-linear fractal extrapolation algorithm to short-term load forecasting

International Nuclear Information System (INIS)

Wang Jianzhou; Jia Ruiling; Zhao Weigang; Wu Jie; Dong Yao

2012-01-01

Highlights: ► The maximal predictive step size is determined by the largest Lyapunov exponent. ► A proper forecasting step size is applied to load demand forecasting. ► The improved approach is validated by the actual load demand data. ► Non-linear fractal extrapolation method is compared with three forecasting models. ► Performance of the models is evaluated by three different error measures. - Abstract: Precise short-term load forecasting (STLF) plays a key role in unit commitment, maintenance and economic dispatch problems. Employing a subjective and arbitrary predictive step size is one of the most important factors causing the low forecasting accuracy. To solve this problem, the largest Lyapunov exponent is adopted to estimate the maximal predictive step size so that the step size in the forecasting is no more than this maximal one. In addition, in this paper a seldom used forecasting model, which is based on the non-linear fractal extrapolation (NLFE) algorithm, is considered to develop the accuracy of predictions. The suitability and superiority of the two solutions are illustrated through an application to real load forecasting using New South Wales electricity load data from the Australian National Electricity Market. Meanwhile, three forecasting models: the gray model, the seasonal autoregressive integrated moving average approach and the support vector machine method, which received high approval in STLF, are selected to compare with the NLFE algorithm. Comparison results also show that the NLFE model is outstanding, effective, practical and feasible.

Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

Science.gov (United States)

Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

2016-02-01

Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. Copyright © 2015 Elsevier B.V. All rights reserved.

The use of natural analogues in the long-term extrapolation of glass corrosion processes

International Nuclear Information System (INIS)

Lutze, W.; Grambow, B.; Ewing, R.C.; Jercinovic, M.J.

1987-01-01

One of the most critical aspects of nuclear waste management is the extrapolation of materials and systems behavior from short term experiments, typically on the order of one year, over comparatively very long periods of time. Safety and risk analyses have to rely on extrapolations and the respective findings have to be evaluated in the frame of licensing procedures. In this unique situation, any source of information that can lend support to the credibility of predicted behavior, should be exploited and investigated with great care. There are natural systems, e.g. the Oklo reactor, which can provide evidence of radionuclide migration over very long periods of time and thus help to answer specific questions of interest. Natural glasses and minerals can serve as analogues for both glass and crystalline nuclear waste forms, and the alteration of the natural materials can be studied to infer information on the behavior of the man-made products in geologic environments. This paper reviews most of the work performed by the authors and their colleagues in this field together with information available from literature and discusses the extent to which natural glasses can be used to validate or verify predictions. (author)

Extrapolation of model tests measurements of whipping to identify the dimensioning sea states for container ships

DEFF Research Database (Denmark)

Storhaug, Gaute; Andersen, Ingrid Marie Vincent

2015-01-01

to small storms. Model tests of three container ships have been carried out in different sea states under realistic assumptions. Preliminary extrapolation of the measured data suggested that moderate storms are dimensioning when whipping is included due to higher maximum speed in moderate storms...

extrap: Software to assist the selection of extrapolation methods for moving-boat ADCP streamflow measurements

Science.gov (United States)

Mueller, David S.

2013-01-01

Selection of the appropriate extrapolation methods for computing the discharge in the unmeasured top and bottom parts of a moving-boat acoustic Doppler current profiler (ADCP) streamflow measurement is critical to the total discharge computation. The software tool, extrap, combines normalized velocity

Environmental impact of engineered carbon nanoparticles: from releases to effects on the aquatic biota.

Science.gov (United States)

Mottier, Antoine; Mouchet, Florence; Pinelli, Éric; Gauthier, Laury; Flahaut, Emmanuel

2017-08-01

Nano-ecotoxicology is an emerging science which aims to assess the environmental effect of nanotechnologies. The development of this particular aspect of ecotoxicology was made necessary in order to evaluate the potential impact of recently produced and used materials: nanoparticles (NPs). Among all the types of NPs, carbon nanoparticles (CNPs) especially draw attention giving the increasing number of applications and integration into consumer products. However the potential impacts of CNPs in the environment remain poorly known. This review aims to point out the critical issues and aspects that will govern the toxicity of CNPs in the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Effects of Temperature and Hydrostatic Pressure on Metal Toxicity: Insights into Toxicity in the Deep Sea.

Science.gov (United States)

Brown, Alastair; Thatje, Sven; Hauton, Chris

2017-09-05

Mineral prospecting in the deep sea is increasing, promoting concern regarding potential ecotoxicological impacts on deep-sea fauna. Technological difficulties in assessing toxicity in deep-sea species has promoted interest in developing shallow-water ecotoxicological proxy species. However, it is unclear how the low temperature and high hydrostatic pressure prevalent in the deep sea affect toxicity, and whether adaptation to deep-sea environmental conditions moderates any effects of these factors. To address these uncertainties we assessed the effects of temperature and hydrostatic pressure on lethal and sublethal (respiration rate, antioxidant enzyme activity) toxicity in acute (96 h) copper and cadmium exposures, using the shallow-water ecophysiological model organism Palaemon varians. Low temperature reduced toxicity in both metals, but reduced cadmium toxicity significantly more. In contrast, elevated hydrostatic pressure increased copper toxicity, but did not affect cadmium toxicity. The synergistic interaction between copper and cadmium was not affected by low temperature, but high hydrostatic pressure significantly enhanced the synergism. Differential environmental effects on toxicity suggest different mechanisms of action for copper and cadmium, and highlight that mechanistic understanding of toxicity is fundamental to predicting environmental effects on toxicity. Although results infer that sensitivity to toxicants differs across biogeographic ranges, shallow-water species may be suitable ecotoxicological proxies for deep-sea species, dependent on adaptation to habitats with similar environmental variability.

Ecotoxicological evaluation of the additive butylated hydroxyanisole using a battery with six model systems and eighteen endpoints.

Science.gov (United States)

Jos, Angeles; Repetto, Guillermo; Ríos, Juan Carlos; del Peso, Ana; Salguero, Manuel; Hazen, María José; Molero, María Luisa; Fernández-Freire, Paloma; Pérez-Martín, Jose Manuel; Labrador, Verónica; Cameán, Ana

2005-01-26

The occurrence and fate of additives in the aquatic environment is an emerging issue in environmental chemistry. This paper describes the ecotoxicological effects of the commonly used additive butylated hydroxyanisole (BHA) using a test battery, comprising of several different organisms and in vitro test systems, representing a proportion of the different trophic levels. The most sensitive system to BHA was the inhibition of bioluminescence in Vibrio fischeri bacteria, which resulted in an acute low observed adverse effect concentration (LOAEC) of 0.28 microM. The next most sensitive system was the immobilization of the cladoceran Daphnia magna followed by: the inhibition of the growth of the unicellular alga Chlorella vulgaris; the endpoints evaluated in Vero (mammalian) cells (total protein content, LDH activity, neutral red uptake and MTT metabolization), mitotic index and root growth inhibition in the terrestrial plant Allium cepa, and finally, the endpoints used on the RTG-2 salmonid fish cell line (neutral red uptake, total protein content, MTS metabolization, lactate dehydrogenase leakage and activity, and glucose-6-phosphate dehydrogenase activity). Morphological alterations in RTG-2 cells were also assessed and these included loss of cells, induction of cellular pleomorphism, hydropic degeneration and induction of apoptosis at high concentrations. The results from this study also indicated that micronuclei were not induced in A.cepa exposed to BHA. The differences in sensitivity for the diverse systems that were used (EC50 ranged from 1.2 to >500 microM) suggest the importance for a test battery approach in the evaluation of the ecological consequences of chemicals. According to the results, the levels of BHA reported in industrial wastewater would elicit adverse effects in the environment. This, coupled with its potential to bioaccumulate, makes BHA a pollutant of concern not only for acute exposures, but also for the long-term.

Ecotoxicological risk assessment of hospital wastewater: a proposed framework for raw effluents discharging into urban sewer network

International Nuclear Information System (INIS)

Emmanuel, E.; Perrodin, Y.; Keck, G.; Blanchard, J.-M.; Vermande, P.

2005-01-01

In hospitals a large variety of substances are in use for medical purposes such as diagnostics and research. After application, diagnostic agents, disinfectants and excreted non-metabolized pharmaceuticals by patients, reach the wastewater. This form of elimination may generate risks for aquatic organisms. The aim of this study was to present: (i) the steps of an ecological risk assessment and management framework related to hospital effluents evacuating into wastewater treatment plant (WWTP) without preliminary treatment; and (ii) the results of its application on wastewater from an infectious and tropical diseases department of a hospital of a large city in southeastern France. The characterization of effects has been made under two assumptions, which were related to: (a) the effects of hospital wastewater on biological treatment process of WWTP, particularly on the community of organisms in charge of the biological decomposition of the organic matter; (b) the effects on aquatic organisms. COD and BOD 5 have been measured for studying global organic pollution. Assessment of halogenated organic compounds was made using halogenated organic compounds absorbable on activated carbon (AOX) concentrations. Heavy metals (arsenic, cadmium, chrome, copper, mercury, nickel, lead and zinc) were measured. Low most probable number (MPP) for faecal coliforms has been considered as an indirect detection of antibiotics and disinfectants presence. For toxicity assessment, bioluminescence assay using Vibrio fischeri photobacteria, 72-h EC 50 algae growth Pseudokirchneriella subcapitata and 24-h EC 50 on Daphnia magna were used. The scenario allows to a semi-quantitative risk characterization. It needs to be improved on some aspects, particularly those linked to: long term toxicity assessment on target organisms (bioaccumulation of pollutants, genotoxicity, etc.); ecotoxicological interactions between pharmaceuticals, disinfectants used both in diagnostics and in cleaning of

Verification of absorbed dose rates in reference beta radiation fields: measurements with an extrapolation chamber and radiochromic film

Energy Technology Data Exchange (ETDEWEB)

Reynaldo, S. R. [Development Centre of Nuclear Technology, Posgraduate Course in Science and Technology of Radiations, Minerals and Materials / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Benavente C, J. A.; Da Silva, T. A., E-mail: sirr@cdtn.br [Development Centre of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2015-10-15

Beta Secondary Standard 2 (Bss 2) provides beta radiation fields with certified values of absorbed dose to tissue and the derived operational radiation protection quantities. As part of the quality assurance, metrology laboratories are required to verify the reliability of the Bss-2 system by performing additional verification measurements. In the CDTN Calibration Laboratory, the absorbed dose rates and their angular variation in the {sup 90}Sr/{sup 90}Y and {sup 85}Kr beta radiation fields were studied. Measurements were done with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. In comparison to the certificate values provided by the Bss-2, absorbed dose rates measured with the extrapolation chamber differed from -1.4 to 2.9% for the {sup 90}Sr/{sup 90}Y and -0.3% for the {sup 85}Kr fields; their angular variation showed differences lower than 2% for incidence angles up to 40-degrees and it reached 11% for higher angles, when compared to ISO values. Measurements with the radiochromic film showed an asymmetry of the radiation field that is caused by a misalignment. Differences between the angular variations of absorbed dose rates determined by both dosimetry systems suggested that some correction factors for the extrapolation chamber that were not considered should be determined. (Author)

Determination of the bulk melting temperature of nickel using Monte Carlo simulations: Inaccuracy of extrapolation from cluster melting temperatures

Science.gov (United States)

Los, J. H.; Pellenq, R. J. M.

2010-02-01

We have determined the bulk melting temperature Tm of nickel according to a recent interatomic interaction model via Monte Carlo simulation by two methods: extrapolation from cluster melting temperatures based on the Pavlov model (a variant of the Gibbs-Thompson model) and by calculation of the liquid and solid Gibbs free energies via thermodynamic integration. The result of the latter, which is the most reliable method, gives Tm=2010±35K , to be compared to the experimental value of 1726 K. The cluster extrapolation method, however, gives a 325° higher value of Tm=2335K . This remarkable result is shown to be due to a barrier for melting, which is associated with a nonwetting behavior.

Deposition of inhaled radionuclides in bronchial airways: Implications for extrapolation modeling

International Nuclear Information System (INIS)

Balashazy, I.; Hofmann, W.; Heistracher, T.

1996-01-01

The laboratory rat has frequently been used as a human surrogate to estimate potential health effects following the inhalation of radioactive aerosol particles. Interspecies differences in biological response are commonly related to interspecies differences in particle deposition efficiencies. In addition, the documented site selectivity of bronchial carcinomas suggests that localized particle deposition patterns within bronchial airway bifurcations may have important implications for inhalation risk assessments. Interspecies differences in particle deposition patterns may be related primarily to differences in airway morphometries. Thus the validity of extrapolating rat deposition data to human inhalation conditions depends on their morphometric similarities and differences. It is well known that there are significant structural differences between the human - rather symmetric - and the rat - monopodial - airway systems. In the present approach, we focus on localized deposition patterns and deposition efficiencies in selected asymmetric bronchial airway bifurcations, whose diameters, lengths and branching angles were derived from the stochastic airway models of human and rat lungs (Koblinger and Hofmann, 1985;1988), which are based on the morphometric data of Raabe et al. (1976). The effects of interspecies differences in particle deposition patterns are explored in this study for two asymmetric bifurcation geometries in segmental bronchi and terminal bronchioles of both the human and rat lungs at different particle sizes. In order to examine the effect of flow rate on particle deposition in the human lung, we selected two different minute volumes, i.e., 10 and 60 1 min -1 , which are representative of low and heavy physical activity breathing conditions. In the case of the rat we used a minute volume of 0.234 1 min -1 (Hofmann et al., 1993)

Calibration of a scintillation dosemeter for beta rays using an extrapolation ionization chamber

International Nuclear Information System (INIS)

Hakanen, A.T.; Sipilae, P.M.; Kosunen, A.

2004-01-01

A scintillation dosemeter is calibrated for 90 Sr/ 90 Y beta rays from an ophthalmic applicator, using an extrapolation ionization chamber as a reference instrument. The calibration factor for the scintillation dosemeter agrees with that given by the manufacturer of the dosemeter within ca. 2%. The estimated overall uncertainty of the present calibration is ca. 6% (2 sd). A calibrated beta-ray ophthalmic applicator can be used as a reference source for further calibrations performed in the laboratory or in the hospital

The effect of Cu2+ on osmoregulation in rainbow trout (Oncorhynchus mykiss) assayed by changes in plasma salinity and gill lipid metabolism

DEFF Research Database (Denmark)

Hansen, Heinz J.M.; Olsen, Allan Gylling; Rosenkilde, Per

1993-01-01

Zoofysiologi, Osmoregulation, Lipid metabolism, Ecotoxicology, Rainbow trout, Oncorhynchus mykiss.......Zoofysiologi, Osmoregulation, Lipid metabolism, Ecotoxicology, Rainbow trout, Oncorhynchus mykiss....

In vitro to in vivo extrapolation of biotransformation rates for assessing bioaccumulation of hydrophobic organic chemicals in mammals.

Science.gov (United States)

Lee, Yung-Shan; Lo, Justin C; Otton, S Victoria; Moore, Margo M; Kennedy, Chris J; Gobas, Frank A P C

2017-07-01

Incorporating biotransformation in bioaccumulation assessments of hydrophobic chemicals in both aquatic and terrestrial organisms in a simple, rapid, and cost-effective manner is urgently needed to improve bioaccumulation assessments of potentially bioaccumulative substances. One approach to estimate whole-animal biotransformation rate constants is to combine in vitro measurements of hepatic biotransformation kinetics with in vitro to in vivo extrapolation (IVIVE) and bioaccumulation modeling. An established IVIVE modeling approach exists for pharmaceuticals (referred to in the present study as IVIVE-Ph) and has recently been adapted for chemical bioaccumulation assessments in fish. The present study proposes and tests an alternative IVIVE-B technique to support bioaccumulation assessment of hydrophobic chemicals with a log octanol-water partition coefficient (K OW ) ≥ 4 in mammals. The IVIVE-B approach requires fewer physiological and physiochemical parameters than the IVIVE-Ph approach and does not involve interconversions between clearance and rate constants in the extrapolation. Using in vitro depletion rates, the results show that the IVIVE-B and IVIVE-Ph models yield similar estimates of rat whole-organism biotransformation rate constants for hypothetical chemicals with log K OW  ≥ 4. The IVIVE-B approach generated in vivo biotransformation rate constants and biomagnification factors (BMFs) for benzo[a]pyrene that are within the range of empirical observations. The proposed IVIVE-B technique may be a useful tool for assessing BMFs of hydrophobic organic chemicals in mammals. Environ Toxicol Chem 2017;36:1934-1946. © 2016 SETAC. © 2016 SETAC.

Comparison of various state equations for approximation and extrapolation of experimental hydrogen molar volumes in wide temperature and pressure intervals

International Nuclear Information System (INIS)

Didyk, A.Yu.; Altynov, V.A.; Wisniewski, R.

2009-01-01

The numerical analysis of practically all existing formulae such as expansion series, Tait, logarithm, Van der Waals and virial equations for interpolation of experimental molar volumes versus high pressure was carried out. One can conclude that extrapolating dependences of molar volumes versus pressure and temperature can be valid. It was shown that virial equations can be used for fitting experimental data at relatively low pressures P<3 kbar too in distinction to other equations. Direct solving of a linear equation of the third order relatively to volume using extrapolated virial coefficients allows us to obtain good agreement between existing experimental data for high pressure and calculated values

Hematological responses after inhaling {sup 238}PuO{sub 2}: An extrapolation from beagle dogs to humans

Energy Technology Data Exchange (ETDEWEB)

Scott, B.R.; Muggenburg, B.A.; Welsh, C.A.; Angerstein, D.A.

1994-11-01

The alpha emitter plutonium-238 ({sup 238}Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to {sup 238}PuO{sub 2} have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of {sup 238}Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled {sup 238}PuO{sub 2} on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting {sup 238}PuO{sub 2} particles and to extrapolate results to humans.

The OECD expert meeting on ecotoxicology and environmental fate — Towards the development of improved OECD guidelines for the testing of nanomaterials

International Nuclear Information System (INIS)

Kühnel, Dana; Nickel, Carmen

2014-01-01

On behalf of the OECD Working Party on Manufactured Nanomaterials (WPMN) an expert meeting on ecotoxicology and environmental fate of nanomaterials (NMs) took place in January 2013 in Berlin. At this meeting experts from science, industry and regulatory bodies discussed the applicability of OECD test guidelines (TGs) for chemicals to nanomaterials. The objective was to discuss the current state of the relevant science and provide recommendations to the OECD WPMN on (1) the need for updating current OECD TGs and the need for developing new ones specific to nanomaterials; and (2) guidance needed for the appropriate and valid testing of environmental fate and ecotoxicity endpoints for NMs. Experts at the workshop agreed that the majority of the OECD TG for chemicals were generally applicable for the testing of NM, with the exception of TG 105 (water solubility) and 106 (adsorption-desorption). Additionally, the workshop also highlighted considerations when conducting OECD chemical TG on nanomaterials (e.g., sample preparation, dispersion, analysis, dosimetry and characterisation). These considerations will lead to the future development of proposals for new TG and guidance documents (GDs) to ensure that OECD TG give meaningful, repeatable, and accurate results when used for nanomaterials. This report provides a short overview of topics discussed during the meeting and the main outcomes. A more detailed report of the workshop will become available through the OECD, however, due to the urgency of having OECD TG relevant for nanomaterials, this brief report is being shared with the scientific community through this communication. - Highlights: • OECD test guidelines (TGs) were developed for the testing of conventional chemicals. • Need for discussion on applicability of current TGs to nanomaterials • An expert meeting addressing this issue was held. • The focus was on TGs covering ecotoxicology and environmental fate. • Recommendations for updating current OECD

CT image construction of a totally deflated lung using deformable model extrapolation

International Nuclear Information System (INIS)

Sadeghi Naini, Ali; Pierce, Greg; Lee, Ting-Yim

2011-01-01

Purpose: A novel technique is proposed to construct CT image of a totally deflated lung from a free-breathing 4D-CT image sequence acquired preoperatively. Such a constructed CT image is very useful in performing tumor ablative procedures such as lung brachytherapy. Tumor ablative procedures are frequently performed while the lung is totally deflated. Deflating the lung during such procedures renders preoperative images ineffective for targeting the tumor. Furthermore, the problem cannot be solved using intraoperative ultrasound (U.S.) images because U.S. images are very sensitive to small residual amount of air remaining in the deflated lung. One possible solution to address these issues is to register high quality preoperative CT images of the deflated lung with their corresponding low quality intraoperative U.S. images. However, given that such preoperative images correspond to an inflated lung, such CT images need to be processed to construct CT images pertaining to the lung's deflated state. Methods: To obtain the CT images of deflated lung, we present a novel image construction technique using extrapolated deformable registration to predict the deformation the lung undergoes during full deflation. The proposed construction technique involves estimating the lung's air volume in each preoperative image automatically in order to track the respiration phase of each 4D-CT image throughout a respiratory cycle; i.e., the technique does not need any external marker to form a respiratory signal in the process of curve fitting and extrapolation. The extrapolated deformation field is then applied on a preoperative reference image in order to construct the totally deflated lung's CT image. The technique was evaluated experimentally using ex vivo porcine lung. Results: The ex vivo lung experiments led to very encouraging results. In comparison with the CT image of the deflated lung we acquired for the purpose of validation, the constructed CT image was very similar. The

Modeling the systemic retention of beryllium in rat. Extrapolation to human

International Nuclear Information System (INIS)

Montero Prieto, M.; Vidania Munoz, R. de

1994-01-01

In this work, we analyzed different approaches, assayed in order to numerically describe the systemic behaviour of Beryllium. The experimental results used in this work, were previously obtained by Furchner et al. (1973), using Sprague-Dawley rats, and others animal species. Furchner's work includes the obtained model for whole body retention in rats, but not for each target organ. In this work we present the results obtained by modeling the kinetic behaviour of Beryllium in several target organs. The results of this kind of models were used in order to establish correlations among the estimated kinetic constants. The parameters of the model were extrapolated to humans and, finally, compared with others previously published. (Author) 12 refs

Modeling of systematic retention of beryllium in rats. Extrapolation to humans

International Nuclear Information System (INIS)

Montero Prieto, M.; Vidania Munoz, R. de.

1994-01-01

In this work, we analyzed different approaches, assayed in order to numerically describe the systemic behaviour of Beryllium. The experimental results used in this work, were previously obtained by Furchner et al. (1973), using Sprague-Dawley rats, and other animal species. Furchner's work includes the obtained model for whole body retention in rats but not for each target organ. In this work we present the results obtained by modeling the kinetic behaviour of Beryllium in several target organs. The results of this kind of models were used in order to establish correlations among the estimated kinetic constants. The parameters of the model were extrapolated to humans and, finally, compared with other previously published

Extrapolation of the FOM 1 MW free-electron maser to a multi-megawatt millimeter microwave source

NARCIS (Netherlands)

Caplan, M.; Valentini, M.; Verhoeven, A.; Urbanus, W.; Tulupov, A.

1997-01-01

A Free-Electron Maser is now under test at the FOM Institute (Rijnhuizen, Netherlands) with the goal of producing 1 MW long pulse to CW microwave output in the range 130-250 GHz with wall plug efficiencies of 60%. An extrapolated version of this device is proposed, which by scaling up beam current

Ecotoxicological effect characterisation of widely used organic UV filters.

Science.gov (United States)

Kaiser, D; Sieratowicz, A; Zielke, H; Oetken, M; Hollert, H; Oehlmann, J

2012-04-01

Chemical UV filters are used in sun protection and personal care products in order to protect consumers from skin cancer induced by ultraviolet (UV) radiation. The present study aims to evaluate the effects of three common UV filters butyl-methoxydibenzoylmethane (B-MDM) ethylhexyl-methoxycinnamate (EHMC) and octocrylene (OCR) on aquatic organism, focussing particularly on infaunal and epibentic invertebrates (Chironomus riparius, Lumbriculus variegatus, Melanoides tuberculata and Potamopyrgus antipodarum). Due to their life habits, these organism are especially affected by lipophilic substances. Additionally, two direct sediment contact assays utilising zebra fish (Danio rerio) embryos and bacteria (Arthrobacter globiformis) were conducted. EHMC caused a toxic effect on reproduction in both snails with lowest observed effect concentrations (LOEC) of 0.4 mg/kg (Potamopyrgus antipodarum) and 10 mg/kg (Melanoides tuberculata). At high concentrations sublethal effects could be observed for D. rerio after exposure to EHMC (NOEC 100 mg/kg). B-MDM and OCR showed no effects on any of the tested organism. Copyright © 2011 Elsevier Ltd. All rights reserved.

NONLINEAR FORCE-FREE FIELD EXTRAPOLATION OF A CORONAL MAGNETIC FLUX ROPE SUPPORTING A LARGE-SCALE SOLAR FILAMENT FROM A PHOTOSPHERIC VECTOR MAGNETOGRAM

Energy Technology Data Exchange (ETDEWEB)

Jiang, Chaowei; Wu, S. T.; Hu, Qiang [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Feng, Xueshang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu, E-mail: fengx@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)

2014-05-10

Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength ≲ 100 G), where the PIL is very fragmented due to small parasitic polarities on both sides of the PIL and the transverse field has a low signal-to-noise ratio. Thus, extrapolating a large-scale FR in such a case represents a far more difficult challenge. We demonstrate that our CESE-MHD-NLFFF code is sufficient for the challenge. The numerically reproduced magnetic dips of the extrapolated FR match observations of the filament and its barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.

Investigation of the ecotoxicologic effect of pesticide industry ...

African Journals Online (AJOL)

In this study, when the raw wastewater, which resulted from the manufacturing of 2,4- dichlorophenoxyacetic acid (2,4-D) dimethylamine salt and 2,4-D acid isooctylester herbicides in the factory, was discharged to the ecosystem without treatment, its ecotoxic effect on the pancreas and liver of rats was investigated.

Objective classification of ecological status in marine water bodies using ecotoxicological information and multivariate analysis.

Science.gov (United States)

Beiras, Ricardo; Durán, Iria

2014-12-01

Some relevant shortcomings have been identified in the current approach for the classification of ecological status in marine water bodies, leading to delays in the fulfillment of the Water Framework Directive objectives. Natural variability makes difficult to settle fixed reference values and boundary values for the Ecological Quality Ratios (EQR) for the biological quality elements. Biological responses to environmental degradation are frequently of nonmonotonic nature, hampering the EQR approach. Community structure traits respond only once ecological damage has already been done and do not provide early warning signals. An alternative methodology for the classification of ecological status integrating chemical measurements, ecotoxicological bioassays and community structure traits (species richness and diversity), and using multivariate analyses (multidimensional scaling and cluster analysis), is proposed. This approach does not depend on the arbitrary definition of fixed reference values and EQR boundary values, and it is suitable to integrate nonlinear, sensitive signals of ecological degradation. As a disadvantage, this approach demands the inclusion of sampling sites representing the full range of ecological status in each monitoring campaign. National or international agencies in charge of coastal pollution monitoring have comprehensive data sets available to overcome this limitation.

Classification of solid industrial waste based on ecotoxicology tests using Daphnia magna: an alternative

Directory of Open Access Journals (Sweden)

William Gerson Matias

2005-11-01

Full Text Available The adequate treatment and final disposal of solid industrial wastes depends on their classification into class I or II. This classification is proposed by NBR 10.004; however, it is complex and time-consuming. With a view to facilitating this classification, the use of assays with Daphnia magna is proposed. These assays make possible the identification of toxic chemicals in the leach, which denotes the presence of one of the characteristics described by NBR 10.004, the toxicity, which is a sufficient argument to put the waste into class I. Ecotoxicological tests were carried out with ten samples of solid wastes of frequent production and, on the basis of the results from EC(I50/48h of those samples in comparison with the official classification of NBR 10.004, limits were established for the classification of wastes into class I or II. A coincidence in the classification of 50% of the analyzed samples was observed. In cases in which there is no coherence between the methods, the method proposed in this work classifies the waste into class I. These data are preliminary, but they reveal that the classification system proposed here is promising because of its quickness and economic viability.

The chronic toxicity of molybdate to marine organisms. I. Generating reliable effects data

Energy Technology Data Exchange (ETDEWEB)

Heijerick, D.G., E-mail: Dagobert.heijerick@arche-consulting.be [ARCHE - Assessing Risks of Chemicals, Stapelplein 70 Bus 104, Gent (Belgium); Regoli, L. [International Molybdenum Association, 4 Heathfield Terrace, London, W4 4JE (United Kingdom); Stubblefield, W. [Oregon State University, Department of Environmental and Molecular Toxicology, 421 Weniger Hall, Corvallis, OR 97331 (United States)

2012-07-15

A scientific research program was initiated by the International Molybdenum Association (IMOA) which addressed identified gaps in the environmental toxicity data for the molybdate ion (MoO{sub 4}{sup 2-}). These gaps were previously identified during the preparation of EU-REACH-dossiers for different molybdenum compounds (European Union regulation on Registration, Evaluation, Authorization and Restriction of Chemical substances; EC, 2006). Evaluation of the open literature identified few reliable marine ecotoxicological data that could be used for deriving a Predicted No-Effect Concentration (PNEC) for the marine environment. Rather than calculating a PNEC{sub marine} using the assessment factor methodology on a combined freshwater/marine dataset, IMOA decided to generate sufficient reliable marine chronic data to permit derivation of a PNEC by means of the more scientifically robust species sensitivity distribution (SSD) approach (also called the statistical extrapolation approach). Nine test species were chronically exposed to molybdate (added as sodium molybdate dihydrate, Na{sub 2}MoO{sub 4}{center_dot}2H{sub 2}O) according to published standard testing guidelines that are acceptable for a broad range of regulatory purposes. The selected test organisms were representative for typical marine trophic levels: micro-algae/diatom (Phaeodactylum tricornutum, Dunaliella tertiolecta), macro-alga (Ceramium tenuicorne), mysids (Americamysis bahia), copepod (Acartia tonsa), fish (Cyprinodon variegatus), echinoderms (Dendraster exentricus, Strongylocentrotus purpuratus) and molluscs (Mytilus edulis, Crassostrea gigas). Available NOEC/EC{sub 10} levels ranged between 4.4 mg Mo/L (blue mussel M. edulis) and 1174 mg Mo/L (oyster C. gigas). Using all available reliable marine chronic effects data that are currently available, a HC{sub 5,50%} (median hazardous concentration affecting 5% of the species) of 5.74 (mg Mo)/L was derived with the statistical extrapolation approach, a

A novel cost-effectiveness model of prescription eicosapentaenoic acid extrapolated to secondary prevention of cardiovascular diseases in the United States.

Science.gov (United States)

Philip, Sephy; Chowdhury, Sumita; Nelson, John R; Benjamin Everett, P; Hulme-Lowe, Carolyn K; Schmier, Jordana K

2016-10-01

Given the substantial economic and health burden of cardiovascular disease and the residual cardiovascular risk that remains despite statin therapy, adjunctive therapies are needed. The purpose of this model was to estimate the cost-effectiveness of high-purity prescription eicosapentaenoic acid (EPA) omega-3 fatty acid intervention in secondary prevention of cardiovascular diseases in statin-treated patient populations extrapolated to the US. The deterministic model utilized inputs for cardiovascular events, costs, and utilities from published sources. Expert opinion was used when assumptions were required. The model takes the perspective of a US commercial, third-party payer with costs presented in 2014 US dollars. The model extends to 5 years and applies a 3% discount rate to costs and benefits. Sensitivity analyses were conducted to explore the influence of various input parameters on costs and outcomes. Using base case parameters, EPA-plus-statin therapy compared with statin monotherapy resulted in cost savings (total 5-year costs $29,393 vs $30,587 per person, respectively) and improved utilities (average 3.627 vs 3.575, respectively). The results were not sensitive to multiple variations in model inputs and consistently identified EPA-plus-statin therapy to be the economically dominant strategy, with both lower costs and better patient utilities over the modeled 5-year period. The model is only an approximation of reality and does not capture all complexities of a real-world scenario without further inputs from ongoing trials. The model may under-estimate the cost-effectiveness of EPA-plus-statin therapy because it allows only a single event per patient. This novel model suggests that combining EPA with statin therapy for secondary prevention of cardiovascular disease in the US may be a cost-saving and more compelling intervention than statin monotherapy.

Statistical validation of engineering and scientific models : bounds, calibration, and extrapolation.

Energy Technology Data Exchange (ETDEWEB)

Dowding, Kevin J.; Hills, Richard Guy (New Mexico State University, Las Cruces, NM)

2005-04-01

Numerical models of complex phenomena often contain approximations due to our inability to fully model the underlying physics, the excessive computational resources required to fully resolve the physics, the need to calibrate constitutive models, or in some cases, our ability to only bound behavior. Here we illustrate the relationship between approximation, calibration, extrapolation, and model validation through a series of examples that use the linear transient convective/dispersion equation to represent the nonlinear behavior of Burgers equation. While the use of these models represents a simplification relative to the types of systems we normally address in engineering and science, the present examples do support the tutorial nature of this document without obscuring the basic issues presented with unnecessarily complex models.

Extrapolation of dynamic load behaviour on hydroelectric turbine blades with cyclostationary modelling

Science.gov (United States)

Poirier, Marc; Gagnon, Martin; Tahan, Antoine; Coutu, André; Chamberland-lauzon, Joël

2017-01-01

In this paper, we present the application of cyclostationary modelling for the extrapolation of short stationary load strain samples measured in situ on hydraulic turbine blades. Long periods of measurements allow for a wide range of fluctuations representative of long-term reality to be considered. However, sampling over short periods limits the dynamic strain fluctuations available for analysis. The purpose of the technique presented here is therefore to generate a representative signal containing proper long term characteristics and expected spectrum starting with a much shorter signal period. The final objective is to obtain a strain history that can be used to estimate long-term fatigue behaviour of hydroelectric turbine runners.

Characterization of a extrapolation chamber in standard X-ray beam, radiodiagnosis level; Caracterizacao de uma camara de extrapolacao em feixes padroes de raios X, nivel radiodiagnostico

Energy Technology Data Exchange (ETDEWEB)

Silva, Eric A.B. da; Caldas, Linda V.E., E-mail: ebrito@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-10-26

The extrapolation chamber is a ionization chamber used for detection low energy radiation and can be used as an standard instrument for beta radiation beams. This type of ionization chamber have as main characteristic the variation of sensible volume. This paper performs a study of characterization of a PTW commercial extrapolation chamber, in the energy interval of the qualities of conventional radiodiagnostic

Comparison of extrapolation methods for creep rupture stresses of 12Cr and 18Cr10NiTi steels

International Nuclear Information System (INIS)

Ivarsson, B.

1979-01-01

As a part of a Soviet-Swedish research programme the creep rupture properties of two heat resisting steels namely a 12% Cr steel and an 18% Cr12% Ni titanium stabilized steel have been studied. One heat from each country of both steels were creep tested. The strength of the 12% Cr steels was similar to earlier reported strength values, the Soviet steel being some-what stronger due to a higher tungsten content. The strength of the Swedish 18/12 Ti steel agreed with earlier results, while the properties of the Soviet steel were inferior to those reported from earlier Soviet creep testings. Three extrapolation methods were compared on creep rupture data collected in both countries. Isothermal extrapolation and an algebraic method of Soviet origin gave in many cases rather similar results, while the parameter method recommended by ISO resulted in higher rupture strength values at longer times. (author)

Propagation of internal errors in explicit Runge–Kutta methods and internal stability of SSP and extrapolation methods

KAUST Repository

Ketcheson, David I.

2014-04-11

In practical computation with Runge--Kutta methods, the stage equations are not satisfied exactly, due to roundoff errors, algebraic solver errors, and so forth. We show by example that propagation of such errors within a single step can have catastrophic effects for otherwise practical and well-known methods. We perform a general analysis of internal error propagation, emphasizing that it depends significantly on how the method is implemented. We show that for a fixed method, essentially any set of internal stability polynomials can be obtained by modifying the implementation details. We provide bounds on the internal error amplification constants for some classes of methods with many stages, including strong stability preserving methods and extrapolation methods. These results are used to prove error bounds in the presence of roundoff or other internal errors.

Ecotoxicological impacts of effluents generated by oil sands bitumen extraction and oil sands lixiviation on Pseudokirchneriella subcapitata

Energy Technology Data Exchange (ETDEWEB)

Debenest, T., E-mail: tdebenest@yahoo.fr [Environment Canada, Fluvial Ecosystem Research, 105 McGill Street, 7 floor, Montreal, Quebec, H2Y 2E7 (Canada); Turcotte, P. [Environment Canada, Fluvial Ecosystem Research, 105 McGill Street, 7 floor, Montreal, Quebec, H2Y 2E7 (Canada); Gagne, F., E-mail: francois.gagne@ec.gc.ca [Environment Canada, Fluvial Ecosystem Research, 105 McGill Street, 7 floor, Montreal, Quebec, H2Y 2E7 (Canada); Gagnon, C.; Blaise, C. [Environment Canada, Fluvial Ecosystem Research, 105 McGill Street, 7 floor, Montreal, Quebec, H2Y 2E7 (Canada)

2012-05-15

The exploitation of Athabasca oil sands deposits in northern Alberta has known an intense development in recent years. This development has raised concern about the ecotoxicological risk of such industrial activities adjacent to the Athabasca River. Indeed, bitumen extraction generated large amounts of oil sands process-affected water (OSPW) which are discharged in tailing ponds in the Athabasca River watershed. This study sought to evaluate and compare the toxicity of OSPW and oil sands lixiviate water (OSLW) with a baseline (oil sands exposed to water; OSW) on a microalgae, Pseudokirchneriella subcapitata, at different concentrations (1.9, 5.5, 12.25, 25 and 37.5%, v/v). Chemical analyses of water-soluble contaminants showed that OSPW and OSLW were enriched in different elements such as vanadium (enrichment factor, EF = 66 and 12, respectively), aluminum (EF = 64 and 15, respectively), iron (EF = 52.5 and 17.1, respectively) and chromium (39 and 10, respectively). The toxicity of OSPW on cells with optimal intracellular esterase activity and chlorophyll autofluorescence (viable cells) (72 h-IC 50% < 1.9%) was 20 times higher than the one of OSW (72 h-IC 50% > 37.5%, v/v). OSLW was 4.4 times less toxic (IC 50% = 8.5%, v/v) than OSPW and 4.5 times more toxic than OSW. The inhibition of viable cell growth was significantly and highly correlated (<-0.7) with the increase of arsenic, beryllium, chromium, copper, lead, molybdenum and vanadium concentrations. The specific photosynthetic responses studied with JIP-test (rapid and polyphasic chlorophyll a fluorescence emission) showed a stimulation of the different functional parameters (efficiency of PSII to absorb energy from photons, size of effective PSII antenna and vitality of photosynthetic apparatus for energy conversion) in cultures exposed to OSPW and OSLW. To our knowledge, our study highlights the first evidence of physiological effects of OSPW and OSLW on microalgae.

Time extrapolation aspects in the performance assessment of high and medium level radioactive waste disposal in the Boom Clay at Mol (Belgium)

International Nuclear Information System (INIS)

Volckaert, G.

2000-01-01

SCK-CEN is studying the disposal of high and long-lived medium level waste in the Boom Clay at Mol, Belgium. In the performance assessment for such a repository time extrapolation is an inherent problem due to the extremely long half-life of some important radionuclides. To increase the confidence in these time extrapolations SCK-CEN applies a combination of different experimental and modelling approaches including laboratory and in situ experiments, natural analogue studies, deterministic (or mechanistic) models and stochastical models. An overview is given of these approaches and some examples of applications to the different repository system components are given. (author)

Quantitative in vitro-to-in vivo extrapolation in a high-throughput environment

International Nuclear Information System (INIS)

Wetmore, Barbara A.

2015-01-01

High-throughput in vitro toxicity screening provides an efficient way to identify potential biological targets for environmental and industrial chemicals while conserving limited testing resources. However, reliance on the nominal chemical concentrations in these in vitro assays as an indicator of bioactivity may misrepresent potential in vivo effects of these chemicals due to differences in clearance, protein binding, bioavailability, and other pharmacokinetic factors. Development of high-throughput in vitro hepatic clearance and protein binding assays and refinement of quantitative in vitro-to-in vivo extrapolation (QIVIVE) methods have provided key tools to predict xenobiotic steady state pharmacokinetics. Using a process known as reverse dosimetry, knowledge of the chemical steady state behavior can be incorporated with HTS data to determine the external in vivo oral exposure needed to achieve internal blood concentrations equivalent to those eliciting bioactivity in the assays. These daily oral doses, known as oral equivalents, can be compared to chronic human exposure estimates to assess whether in vitro bioactivity would be expected at the dose-equivalent level of human exposure. This review will describe the use of QIVIVE methods in a high-throughput environment and the promise they hold in shaping chemical testing priorities and, potentially, high-throughput risk assessment strategies

Ecotoxicological effects of highway and tunnel wash water runoff

OpenAIRE

Meland, Sondre

2010-01-01

In Norway, the traffic loadings have shown a substantial increase during the last decades. From 1948 to 2008 the transportation load has increased from 2.5 to 60.6 million passenger km. Hence, the ever increasing traffic has without doubt a significant negative effect on the environment. For example, highway runoffs typically contain a cocktail of both organic and inorganic contaminants being able to cause detrimental effects on the aquatic ecosystem. The present thesis, which is part of t...

Use of digestate from a decentralized on-farm biogas plant as fertilizer in soils: An ecotoxicological study for future indicators in risk and life cycle assessment

DEFF Research Database (Denmark)

Pivato, Alberto; Vanin, Stefano; Raga, Roberto

2016-01-01

Over the last decade, the number of decentralized farm biogas plants has increased significantly in the EU. This development leads not only to an increasing amount of biogas produced, but also to a higher amount of digestate obtained. One of the most attractive options to manage the digestate......, on the eluate, with the using aquatic organisms and luminescent bacteria showed an LC50 value of 13.61% volume/volume percent, v/v) for D. magna and no toxicityfor Artemia sp. and V. fischeri.The ecotoxicological parameters obtained from the experimental activity have been analyzed so that they could serve...