WorldWideScience

Sample records for surrogate triso material

  1. Fabrication and Characterization of Surrogate TRISO Particles Using 800μm ZrO2 Kernels

    Energy Technology Data Exchange (ETDEWEB)

    Jolly, Brian C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Helmreich, Grant [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cooley, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dyer, John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-07-01

    In support of fully ceramic microencapsulated (FCM) fuel development, coating development work is ongoing at Oak Ridge National Laboratory (ORNL) to produce tri-structural isotropic (TRISO) coated fuel particles with both UN kernels and surrogate (uranium-free) kernels. The nitride kernels are used to increase fissile density in these SiC-matrix fuel pellets with details described elsewhere. The surrogate TRISO particles are necessary for separate effects testing and for utilization in the consolidation process development. This report focuses on the fabrication and characterization of surrogate TRISO particles which use 800μm in diameter ZrO2 microspheres as the kernel.

  2. Preparation of SiC and Ag/SiC coatings on TRISO surrogate particles by Pulsed Laser Deposition

    International Nuclear Information System (INIS)

    Lustfeld, Martin; Reinecke, Anne-Maria; Lippman, Wolfgang; Hurtado, Antonio; Ruiz-Moreno, Ana

    2014-01-01

    Recently published research results suggest significant advantages of using nanocrystalline instead of coarse grained SiC for nuclear applications. In this work it was attempted to prepare nanocrystalline SiC coatings on TRISO surrogate kernels using the pulsed laser deposition (PLD) process. As a plasma-based physical vapor deposition process, PLD allows the synthesis of dense and stoichiometric coatings in the amorphous or nanocrystalline phase. Two different types of TRISO surrogate kernels were used with outer diameters of 500 pm and 800 μm, respectively: plain Al_2O_3 kernels and ZrO_2 kernels coated with TRISO-like buffer and pyrolytic carbon (PyC) layers. In a second step, the PLD process was used for the preparation of multilayer coatings consisting of a Ag layer buried with a SiC layer. The samples were analyzed regarding their morphology, microstructure, crystalline phase and chemical composition using scanning electron microscopy (SEM), laser scanning microscopy (LSM), x-ray diffraction (XRD) and energy- dispersive x-ray spectroscopy (EDX). The samples will be used in future work for out-of-pile investigations of both thermal stability and Ag retention capability of nanocrystalline SiC layers. X-ray diflraction measurements did not confirm nano crystallinity of the SiC coatings, but rather indicated that the coatings were mainly amorphous possibly with a little fraction of the nanocrystalline phase. Further analyses showed that some of the SiC coatings had an adequate stoichiometric composition and that Ag/SiC multilayer coatings were successfully produced by PLD. Coatings on TRISO- like buffer and PyC layers exhibited good adhesion to the substrate while coatings on Al_2O_3 kernels were susceptible to delamination. The results suggest that PLD is generally suitable for SiC coating of TRISO particles. However, further optimization of the process parameters such as the coating temperature is needed to obtain fine- grained non-columnar SiC layers that are

  3. Pre- and post-irradiation characterization and properties measurements of ZrC coated surrogate TRISO particles

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevamurthy, Gokul [ORNL; Katoh, Yutai [ORNL; Hunn, John D [ORNL; Snead, Lance Lewis [ORNL

    2010-09-01

    Zirconium carbide is a candidate to either replace or supplement silicon carbide as a coating material in TRISO fuel particles for high temperature gas-cooled reactor fuels. Six sets of ZrC coated surrogate microsphere samples, fabricated by the Japan Atomic Energy Agency using the fluidized bed chemical vapor deposition method, were irradiated in the High Flux Isotope Reactor at the Oak Ridge National Laboratory. These developmental samples available for the irradiation experiment were in conditions of either as-fabricated coated particles or particles that had been heat-treated to simulate the fuel compacting process. Five sets of samples were composed of nominally stoichiometric compositions, with the sixth being richer in carbon (C/Zr = 1.4). The samples were irradiated at 800 and 1250 C with fast neutron fluences of 2 and 6 dpa. Post-irradiation, the samples were retrieved from the irradiation capsules followed by microstructural examination performed at the Oak Ridge National Laboratory's Low Activation Materials Development and Analysis Laboratory. This work was supported by the US Department of Energy Office of Nuclear Energy's Advanced Gas Reactor program as part of International Nuclear Energy Research Initiative collaboration with Japan. This report includes progress from that INERI collaboration, as well as results of some follow-up examination of the irradiated specimens. Post-irradiation examination items included microstructural characterization, and nanoindentation hardness/modulus measurements. The examinations revealed grain size enhancement and softening as the primary effects of both heat-treatment and irradiation in stoichiometric ZrC with a non-layered, homogeneous grain structure, raising serious concerns on the mechanical suitability of these particular developmental coatings as a replacement for SiC in TRISO fuel. Samples with either free carbon or carbon-rich layers dispersed in the ZrC coatings experienced negligible grain size

  4. A high-temperature, short-duration method of fabricating surrogate fuel microkernels for carbide-based TRISO nuclear fuels

    International Nuclear Information System (INIS)

    Vasudevamurthy, G.; Radecka, A.; Massey, C.

    2015-01-01

    High-temperature gas-cooled reactor technology is a frontrunner among generation IV nuclear reactor designs. Among the advanced nuclear fuel forms proposed for these reactors, dispersion-type fuel consisting of microencapsulated uranium di-oxide kernels, popularly known as tri-structural isotropic (TRISO) fuel, has emerged as the fuel form of choice. Generation IV gas-cooled fast reactors offer the benefit of recycling nuclear waste with increased burn-ups in addition to producing the required power and hydrogen. Uranium carbide has shown great potential to replace uranium di-oxide for use in these fast spectrum reactors. Uranium carbide microkernels for fast reactor TRISO fuel have traditionally been fabricated by long-duration carbothermic reduction and sintering of precursor uranium dioxide microkernels produced using sol-gel techniques. These long-duration conversion processes are often plagued by issues such as final product purity and process parameters that are detrimental to minor actinide retention. In this context a relatively simple, high-temperature but relatively quick-rotating electrode arc melting method to fabricate microkernels directly from a feedstock electrode was investigated. The process was demonstrated using surrogate tungsten carbide on account of its easy availability, accessibility and the similarity of its melting point relative to uranium carbide and uranium di-oxide.

  5. A high-temperature, short-duration method of fabricating surrogate fuel microkernels for carbide-based TRISO nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevamurthy, G.; Radecka, A.; Massey, C. [Virginia Commonwealth Univ., Richmond, VA (United States). High Temperature Materials Lab.

    2015-07-01

    High-temperature gas-cooled reactor technology is a frontrunner among generation IV nuclear reactor designs. Among the advanced nuclear fuel forms proposed for these reactors, dispersion-type fuel consisting of microencapsulated uranium di-oxide kernels, popularly known as tri-structural isotropic (TRISO) fuel, has emerged as the fuel form of choice. Generation IV gas-cooled fast reactors offer the benefit of recycling nuclear waste with increased burn-ups in addition to producing the required power and hydrogen. Uranium carbide has shown great potential to replace uranium di-oxide for use in these fast spectrum reactors. Uranium carbide microkernels for fast reactor TRISO fuel have traditionally been fabricated by long-duration carbothermic reduction and sintering of precursor uranium dioxide microkernels produced using sol-gel techniques. These long-duration conversion processes are often plagued by issues such as final product purity and process parameters that are detrimental to minor actinide retention. In this context a relatively simple, high-temperature but relatively quick-rotating electrode arc melting method to fabricate microkernels directly from a feedstock electrode was investigated. The process was demonstrated using surrogate tungsten carbide on account of its easy availability, accessibility and the similarity of its melting point relative to uranium carbide and uranium di-oxide.

  6. Analysis of triso packing fraction and fissile material to DB-MHR using LWR reprocessed fuel

    International Nuclear Information System (INIS)

    Silva, Clarysson A.M. da; Pereira, Claubia; Costa, Antonella L.; Veloso, Maria Auxiliadora F.; Gual, Maritza R.

    2013-01-01

    Gas-cooled and graphite-moderated reactor is being considered the next generation of nuclear power plants because of its characteristic to operate with reprocessed fuel. The typical fuel element consists of a hexagonal block with coolant and fuel channels. The fuel pin is manufactured into compacted ceramic-coated particles (TRISO) which are used to achieve both a high burnup and a high degree of passive safety. This work uses the MCNPX 2.6.0 to simulate the active core of Deep Burn Modular Helium Reactor (DB-MHR) employing PWR (Pressurized Water Reactor) reprocessed fuel. However, before a complete study of DB-MHR fuel cycle and recharge, it is necessary to evaluate the neutronic parameters to some values of TRISO Packing Fractions (PF) and Fissile Material (FM). Each PF and FM combination would generate the best behaviour of neutronic parameters. Therefore, this study configures several PF and FM combinations considering the heterogeneity of TRISO layers and lattice. The results present the best combination of PF and FM values according with the more appropriated behaviour of the neutronic parameters during the burnup. In this way, the optimized combination can be used to future works of MHR fuel cycle and recharge. (author)

  7. Testing of HTR UO{sub 2} TRISO fuels in AVR and in material test reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kania, Michael J., E-mail: MichaelJKania@googlemail.com [Retired from Lockheed Martin Corp, 20 Beach Road, Averill Park, NY 12018 (United States); Nabielek, Heinz, E-mail: heinznabielek@me.com [Retired from Research Center Jülich, Monschauerstrasse 61, 52355 Düren (Germany); Verfondern, Karl [Research Center Juelich,Research Center Jülich, Institute of Energy and Climate Research, 52425 Jülich (Germany); Allelein, Hans-Josef [Research Center Juelich,Research Center Jülich, Institute of Energy and Climate Research, 52425 Jülich (Germany); RWTH Aachen, 52072 Aachen (Germany)

    2013-10-15

    The German High Temperature Reactor Fuel Development Program successfully developed, licensed and manufactured many thousands of spherical fuel elements that were used to power the experimental AVR reactor and the commercial THTR reactor. In the 1970s, this program extended the performance envelope of HTR fuels by developing and qualifying the TRISO-coated particle system. Irradiation testing in real-time AVR tests and accelerated MTR tests demonstrated the superior manufacturing process of this fuel and its irradiation performance. In the 1980s, another program direction change was made to a low enriched UO{sub 2} TRISO-coated particle system coupled with high-quality manufacturing specifications designed to meet new HTR plant design needs. These needs included requirements for inherent safety under normal operation and accident conditions. Again, the German fuel development program met and exceeded these challenges by manufacturing and qualifying the low-enriched UO{sub 2} TRISO-fuel system for HTR systems with steam generation, gas-turbine systems and very high temperature process heat applications. Fuel elements were manufactured in production scale facilities that contained near defect free UO{sub 2} TRISO coated particles, homogeneously distributed within a graphite matrix with very low levels of uranium contamination. Good irradiation performance for these elements was demonstrated under normal operating conditions to 12% FIMA and under accident conditions not exceeding 1600 °C.

  8. Experimental Measurement and Numerical Modeling of the Effective Thermal Conductivity of TRISO Fuel Compacts

    International Nuclear Information System (INIS)

    Folsom, Charles

    2015-01-01

    Accurate modeling capability of thermal conductivity of tristructural-isotropic (TRISO) fuel compacts is important to fuel performance modeling and safety of Generation IV reactors. To date, the effective thermal conductivity (ETC) of tristructural-isotropic (TRISO) fuel compacts has not been measured directly. The composite fuel is a complicated structure comprised of layered particles in a graphite matrix. In this work, finite element modeling is used to validate an analytic ETC model for application to the composite fuel material for particle-volume fractions up to 40%. The effect of each individual layer of a TRISO particle is analyzed showing that the overall ETC of the compact is most sensitive to the outer layer constituent. In conjunction with the modeling results, the thermal conductivity of matrix-graphite compacts and the ETC of surrogate TRISO fuel compacts have been successfully measured using a previously developed measurement system. The ETC of the surrogate fuel compacts varies between 50-30 W m -1 K -1 over a temperature range of 50-600°C. As a result of the numerical modeling and experimental measurements of the fuel compacts, a new model and approach for analyzing the effect of compact constituent materials on ETC is proposed that can estimate the fuel compact ETC with approximately 15-20% more accuracy than the old method. Using the ETC model with measured thermal conductivity of the graphite matrix-only material indicate that, in the composite form, the matrix material has a much greater thermal conductivity, which is attributed to the high anisotropy of graphite thermal conductivity. Therefore, simpler measurements of individual TRISO compact constituents combined with an analytic ETC model, will not provide accurate predictions of overall ETC of the compacts emphasizing the need for measurements of composite, surrogate compacts.

  9. Physical and mechanical properties of degraded waste surrogate material

    International Nuclear Information System (INIS)

    Hansen, F.D.; Mellegard, K.D.

    1998-03-01

    This paper discusses rock mechanics testing of surrogate materials to provide failure criteria for compacted, degraded nuclear waste. This daunting proposition was approached by first assembling all known parameters such as the initial waste inventory and rock mechanics response of the underground setting after the waste is stored. Conservative assumptions allowing for extensive degradation processes helped quantify the lowest possible strength conditions of the future state of the waste. In the larger conceptual setting, computations involve degraded waste behavior in transient pressure gradients as gas exits the waste horizon into a wellbore. Therefore, a defensible evaluation of tensile strength is paramount for successful analyses and intentionally provided maximal failed volumes. The very conservative approach assumes rampant degradation to define waste surrogate composition. Specimens prepared from derivative degradation product were consolidated into simple geometries for rock mechanics testing. Tensile strength thus derived helped convince a skeptical peer review panel that drilling into the Waste Isolation Pilot Plant (WIPP) would not likely expel appreciable solids via the drill string

  10. Laboratory Testing of Waste Isolation Pilot Plant Surrogate Waste Materials

    Science.gov (United States)

    Broome, S.; Bronowski, D.; Pfeifle, T.; Herrick, C. G.

    2011-12-01

    The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy geological repository for the permanent disposal of defense-related transuranic (TRU) waste. The waste is emplaced in rooms excavated in the bedded Salado salt formation at a depth of 655 m below the ground surface. After emplacement of the waste, the repository will be sealed and decommissioned. WIPP Performance Assessment modeling of the underground material response requires a full and accurate understanding of coupled mechanical, hydrological, and geochemical processes and how they evolve with time. This study was part of a broader test program focused on room closure, specifically the compaction behavior of waste and the constitutive relations to model this behavior. The goal of this study was to develop an improved waste constitutive model. The model parameters are developed based on a well designed set of test data. The constitutive model will then be used to realistically model evolution of the underground and to better understand the impacts on repository performance. The present study results are focused on laboratory testing of surrogate waste materials. The surrogate wastes correspond to a conservative estimate of the degraded containers and TRU waste materials after the 10,000 year regulatory period. Testing consists of hydrostatic, uniaxial, and triaxial tests performed on surrogate waste recipes that were previously developed by Hansen et al. (1997). These recipes can be divided into materials that simulate 50% and 100% degraded waste by weight. The percent degradation indicates the anticipated amount of iron corrosion, as well as the decomposition of cellulosics, plastics, and rubbers. Axial, lateral, and volumetric strain and axial and lateral stress measurements were made. Two unique testing techniques were developed during the course of the experimental program. The first involves the use of dilatometry to measure sample volumetric strain under a hydrostatic condition. Bulk

  11. Attachment and Detachment Behavior of Human Adenovirus and Surrogates in Fine Granular Limestone Aquifer Material.

    Science.gov (United States)

    Stevenson, Margaret E; Sommer, Regina; Lindner, Gerhard; Farnleitner, Andreas H; Toze, Simon; Kirschner, Alexander K T; Blaschke, Alfred P; Sidhu, Jatinder P S

    2015-09-01

    The transport of human adenovirus, nanoparticles, and PRD1 and MS2 bacteriophages was tested in fine granular limestone aquifer material taken from a borehole at a managed aquifer recharge site in Adelaide, South Australia. Comparison of transport and removal of virus surrogates with the pathogenic virus is necessary to understand the differences between the virus and surrogate. Because experiments using pathogenic viruses cannot be done in the field, laboratory tests using flow-through soil columns were used. Results show that PRD1 is the most appropriate surrogate for adenovirus in an aquifer dominated by calcite material but not under high ionic strength or high pH conditions. It was also found that straining due to size and the charge of the colloid were not dominant removal mechanisms in this system. Implications of this study indicate that a certain surrogate may not represent a specific pathogen solely based on similar size, morphology, and/or surface charge. Moreover, if a particular surrogate is representative of a pathogen in one aquifer system, it may not be the most appropriate surrogate in another porous media system. This was apparent in the inferior performance of MS2 as a surrogate, which is commonly used in virus transport studies. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  12. Microstructural analysis of TRISO particles using multi-scale X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, T., E-mail: tristan.lowe@manchester.ac.uk [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Bradley, R.S. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Yue, S. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); The Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Barii, K. [School of Mechanical Engineering, University of Manchester, M13 9PL (United Kingdom); Gelb, J. [Zeiss Xradia Inc., Pleasanton, CA (United States); Rohbeck, N. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Turner, J. [School of Mechanical Engineering, University of Manchester, M13 9PL (United Kingdom); Withers, P.J. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); The Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom)

    2015-06-15

    TRISO particles, a composite nuclear fuel built up by ceramic and graphitic layers, have outstanding high temperature resistance. TRISO fuel is the key technology for High Temperature Reactors (HTRs) and the Generation IV Very High Temperature Reactor (VHTR) variant. TRISO offers unparalleled containment of fission products and is extremely robust during accident conditions. An understanding of the thermal performance and mechanical properties of TRISO fuel requires a detailed knowledge of pore sizes, their distribution and interconnectivity. Here 50 nm, nano-, and 1 μm resolution, micro-computed tomography (CT), have been used to quantify non-destructively porosity of a surrogate TRISO particle at the 0.3–10 μm and 3–100 μm scales respectively. This indicates that pore distributions can reliably be measured down to a size approximately 3 times the pixel size which is consistent with the segmentation process. Direct comparison with Scanning Electron Microscopy (SEM) sections indicates that destructive sectioning can introduce significant levels of coarse damage, especially in the pyrolytic carbon layers. Further comparative work is required to identify means of minimizing such damage for SEM studies. Finally since it is non-destructive, multi-scale time-lapse X-ray CT opens the possibility of intermittently tracking the degradation of TRISO structure under thermal cycles or radiation conditions in order to validate models of degradation such as kernel movement. X-ray CT in-situ experimentation of TRISO particles under load and temperature could also be used to understand the internal changes that occur in the particles under accident conditions.

  13. TRISO-Coated Fuel Durability Under Extreme Conditions

    International Nuclear Information System (INIS)

    2014-01-01

    The PIs propose to examine TRISO-coated particles (SiC and ZrC coatings) in an integrated two-part study. In the first part, experiments will be performed to assess the reaction kinetics of the carbides under CO-CO2 environments at temperatures up to 1800 degree C. Kinetic model will be applied to describe the degradation. Scanning and transmission electron microscopy will be employed to establish the chemical and microstructure evolution under the imposed environmental conditions. The second part of the proposed work focuses on establishing the role of the high temperature, environmental exposure described above on the mechanical behavior of TRISO-coated particles. Electron microscopy and other advanced techniques will be subsequently performed to evaluate failure mechanisms. The work is expected to reveal relationships between corrosion reactions, starting material characteristics (polytype of SiC, impurity concentration, flaw distribution), flaw healing behavior, and crack growth.

  14. Determination of partition behavior of organic surrogates between paperboard packaging materials and air.

    Science.gov (United States)

    Triantafyllou, V I; Akrida-Demertzi, K; Demertzis, P G

    2005-06-03

    The suitability of recycled paperboard packaging materials for direct food contact applications is a major area of investigation. Chemical contaminants (surrogates) partitioning between recycled paper packaging and foods may affect the safety and health of the consumer. The partition behavior of all possible organic compounds between cardboards and individual foodstuffs is difficult and too time consuming for being fully investigated. Therefore it may be more efficient to determine these partition coefficients indirectly through experimental determination of the partitioning behavior between cardboard samples and air. In this work, the behavior of organic pollutants present in a set of two paper and board samples intended to be in contact with foods was studied. Adsorption isotherms have been plotted and partition coefficients between paper and air have been calculated as a basis for the estimation of their migration potential into food. Values of partition coefficients (Kpaper/air) from 47 to 1207 were obtained at different temperatures. For the less volatile surrogates such as dibutyl phthalate and methyl stearate higher Kpaper/air values were obtained. The adsorption curves showed that the more volatile substances are partitioning mainly in air phase and increasing the temperature from 70 to 100 degrees C their concentrations in air (Cair) have almost doubled. The analysis of surrogates was performed with a method based on solvent extraction and gas chromatographic-flame ionization detection (GC-FID) quantification.

  15. Characterisation of TRISO fuel particles

    International Nuclear Information System (INIS)

    Lopez H, E.; Yang, D.

    2012-10-01

    The TRISO (tri structural isotropic) coated fuel particle is a key component contributing to the inherent safety of the High Temperature Reactor. A uranium kernel is coated with three layers of pyrolytic carbon and one of silicon carbide. The purpose of these coatings is to work as a miniature fission product containment vessel capable of enclosing all important radio nuclei under normal and off-normal reactor operating conditions. Due to the importance of these coatings, is of great interest to establish characterisation techniques capable of providing a detailed description of their microstructure and physical properties. Here we describe the use of Raman spectroscopy and two modulator generalised ellipsometry to study the anisotropy and thermal conductivity of pyrolytic carbon coatings, as well as the stoichiometry of the silicon carbide coatings and fibres. (Author)

  16. Irradiation Testing of TRISO-Coated Particle Fuel in Korea

    International Nuclear Information System (INIS)

    Kim, Bong Goo; Yeo, Sunghwan; Jeong, Kyung-Chai; Eom, Sung-Ho; Kim, Yeon-Ku; Kim, Woong Ki; Lee, Young Woo; Cho, Moon Sung; Kim, Yong Wan

    2014-01-01

    In Korea, coated particle fuel is being developed to support development of a VHTR. At the end of March 2014, the first irradiation test in HANARO at KAERI to demonstrate and qualify TRISO-coated particle fuel for use in a VHTR was terminated. This experiment was conducted in an inert gas atmosphere without on-line temperature monitoring and control, or on-line fission product monitoring of the sweep gas. The irradiation device contained two test rods, one has nine fuel compacts and the other five compacts and eight graphite specimens. Each compact contains about 260 TRISO-coated particles. The duration of irradiation testing at HANARO was about 135 full power days from last August 2013. The maximum average power per particle was about 165 mW/particle. The calculated peak burnup of the TRISO-coated fuel was a little less than 4 atom percent. Post-irradiation examination is being carried out at KAERI’s Irradiated Material Examination Facility beginning in September of 2014. This paper describes characteristics of coated particle fuel, the design of the test rod and irradiation device for this coated particle fuel, and discusses the technical results of irradiation testing at HANARO. (author)

  17. Accelerator-Based Irradiation Creep of Pyrolytic Carbon Used in TRISO Fuel Particles for the (VHTR) Very High Temperature Reactors

    International Nuclear Information System (INIS)

    Wang, Lumin; Was, Gary

    2010-01-01

    Pyrolytic carbon (PyC) is one of the important structural materials in the TRISO fuel particles which will be used in the next generation of gas-cooled very-high-temperature reactors (VHTR). When the TRISO particles are under irradiation at high temperatures, creep of the PyC layers may cause radial cracking leading to catastrophic particle failure. Therefore, a fundamental understanding of the creep behavior of PyC during irradiation is required to predict the overall fuel performance.

  18. Advances in Automated QA/QC for TRISO Fuel Particle Production

    International Nuclear Information System (INIS)

    Hockey, Ronald L.; Bond, Leonard J.; Batishko, Charles R.; Gray, Joseph N.; Saurwein, John J.; Lowden, Richard A.

    2004-01-01

    Fuel in most Generation IV reactor designs typically encompasses billions of the TRISO particles. Present day QA/QC methods, done manually and in many cases destructively, cannot economically test a statistically significant fraction of the large number of the individual fuel particles required. Fully automated inspection technologies are essential to economical TRISO fuel particle production. A combination of in-line nondestructive (NDE) measurements employing electromagnetic induction and digital optical imaging analysis is currently under investigation and preliminary data indicate the potential for meeting the demands of this application. To calibrate high-speed NDE methods, surrogate fuel particle samples are being coated with layers containing a wide array of defect types found to degrade fuel performance and these are being characterized via high-resolution CT and digital radiographic images

  19. Deposition and Characterization of TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. K.; Choi, D. J.; Lee, H. K.; Kim, J. K.; Kim, J. H.; Chun, J. H. [KAIST, Daejeon (Korea, Republic of)

    2007-03-15

    Zirconium carbide has been chosen and studied as an advanced material of silicon carbide. In order to collect data on the basic properties and characteristics of Zirconium carbide, studies have been conducted using various methods. As a result of chemically vapor deposed subliming zirconium tetrachloride(ZrCl4) and using methane(CH4) as a source in hydrogen atmosphere, graphite film is deposited.. Zirconium carbide was deposited on the sample where silicon carbide was deposited on a graphite substrate using Zirconium sponge as a Zirconium source. In terms of physical characteristics, the deposited Zirconium carbide showed higher strength, but slightly lower elastic modulus than silicon carbide. In order to evaluate the mechanical properties of a coating layer in pre-irradiation step, internal pressure induced method and direct strength measurement method is carried out. In the internal pressure induced method, in order to produce the requirement pressure, pressure media is used. In the direct strength measurement method, the indentation experiment that indent on a hemisphere shell with plate indenter is conducted. For this method, the finite element analysis is used and the analysis is verified by indentation experiments. To measure the strength of TRISO particle SiC coating, SiC hemisphere shell is performed through grinding and heat treatment. Through the finite element analysis, strength evaluation equation is suggested. Using suggested equation, Strength evaluation is performed and the strength value shows 1025MPa as a result of statistical analysis.

  20. Deposition and Characterization of TRISO Coating Layers

    International Nuclear Information System (INIS)

    Kim, D. K.; Choi, D. J.; Lee, H. K.; Kim, J. K.; Kim, J. H.; Chun, J. H.

    2007-03-01

    Zirconium carbide has been chosen and studied as an advanced material of silicon carbide. In order to collect data on the basic properties and characteristics of Zirconium carbide, studies have been conducted using various methods. As a result of chemically vapor deposed subliming zirconium tetrachloride(ZrCl4) and using methane(CH4) as a source in hydrogen atmosphere, graphite film is deposited.. Zirconium carbide was deposited on the sample where silicon carbide was deposited on a graphite substrate using Zirconium sponge as a Zirconium source. In terms of physical characteristics, the deposited Zirconium carbide showed higher strength, but slightly lower elastic modulus than silicon carbide. In order to evaluate the mechanical properties of a coating layer in pre-irradiation step, internal pressure induced method and direct strength measurement method is carried out. In the internal pressure induced method, in order to produce the requirement pressure, pressure media is used. In the direct strength measurement method, the indentation experiment that indent on a hemisphere shell with plate indenter is conducted. For this method, the finite element analysis is used and the analysis is verified by indentation experiments. To measure the strength of TRISO particle SiC coating, SiC hemisphere shell is performed through grinding and heat treatment. Through the finite element analysis, strength evaluation equation is suggested. Using suggested equation, Strength evaluation is performed and the strength value shows 1025MPa as a result of statistical analysis

  1. Real time in-situ sensing of damage evolution in nanocomposite bonded surrogate energetic materials

    Science.gov (United States)

    Sengezer, Engin C.; Seidel, Gary D.

    2016-04-01

    The current work aims to explore the potential for in-situ structural health monitoring in polymer bonded energetic materials through the introduction of carbon nanotubes (CNTs) into the binder phase as a means to establish a significant piezoresistive response through the resulting nanocomposite binder. The experimental effort herein is focused towards electro-mechanical characterization of surrogate materials in place of actual energetic (explosive) materials in order to provide proof of concept for the strain and damage sensing. The electrical conductivity and the piezoresistive behavior of samples containing randomly oriented MWCNTs introduced into the epoxy (EPON 862) binder of 70 wt% ammonium perchlorate-epoxy hybrid composites are quantitatively and qualitatively evaluated. Brittle failure going through linear elastic behavior, formation of microcracks leading to reduction in composite load carrying capacity and finally macrocracks resulting in eventual failure are observed in the mechanical response of MWNT-ammonium perchlorateepoxy hybrid composites. Incorporating MWNTs into local polymer binder improves the effective stiffness about 40% compared to neat ammonium perchlorate-polymer samples. The real time in-situ relative change in resistance for MWNT hybrid composites was detected with the applied strains through piezoresistive response.

  2. TRISO-coated spent fuel processing using a Grind-Leach head-end

    International Nuclear Information System (INIS)

    Spencer, Barry B.; Del Cul, Guillermo D.; Mattus, Catherine H.; Collins, Emory D.

    2005-01-01

    Processing of TRISO-coated HTGR fuels with the grind-leach process requires that the fuel be finely pulverized for efficient and effective acid dissolution of the fuel components. Mechanical size reduction of the fuel is being investigated with jet mill technology as the final milling step. Laboratory experiments were performed with surrogates of crushed fuel compacts that indicate that milling to very small particle sizes is feasible. The size distribution of the milled product is sensitive to the solids feed rate, and the distribution may be bimodal which could support an effective solid-solid separation. (author)

  3. Assessment of Radiation Embrittlement in Nuclear Reactor Pressure Vessel Surrogate Materials

    Science.gov (United States)

    Balzar, Davor

    2010-10-01

    The radiation-enhanced formation of small (1-2 nm) copper-rich precipitates (CRPs) is critical for the occurrence of embrittlement in nuclear-reactor pressure vessels. Small CRPs are coherent with the bcc matrix, which causes local matrix strain and interaction with the dislocation strain fields, thus impeding dislocation mobility. As CRPs grow, there is a critical size at which a phase transformation occurs, whereby the CRPs are no longer coherent with the matrix, and the strain is relieved. Diffraction-line-broadening analysis (DLBA) and small-angle neutron scattering (SANS) were used to characterize the precipitate formation in surrogate ferritic reactor-pressure vessel steels. The materials were aged for different times at elevated temperature to produce a series of specimens with different degrees of copper precipitation. SANS measurements showed that the precipitate size distribution broadens and shifts toward larger sizes as a function of ageing time. Mechanical hardness showed an increase with ageing time, followed by a decrease, which can be associated with the reduction in the number density as well as the loss of coherency at larger sizes. Inhomogeneous strain correlated with mechanical hardness.

  4. Inter-comparison of Computer Codes for TRISO-based Fuel Micro-Modeling and Performance Assessment

    International Nuclear Information System (INIS)

    Boer, Brian; Keun Jo, Chang; Wu, Wen; Ougouag, Abderrafi M.; McEachren, Donald; Venneri, Francesco

    2010-01-01

    The Next Generation Nuclear Plant (NGNP), the Deep Burn Pebble Bed Reactor (DB-PBR) and the Deep Burn Prismatic Block Reactor (DB-PMR) are all based on fuels that use TRISO particles as their fundamental constituent. The TRISO particle properties include very high durability in radiation environments, hence the designs reliance on the TRISO to form the principal barrier to radioactive materials release. This durability forms the basis for the selection of this fuel type for applications such as Deep Bun (DB), which require exposures up to four times those expected for light water reactors. It follows that the study and prediction of the durability of TRISO particles must be carried as part of the safety and overall performance characterization of all the designs mentioned above. Such evaluations have been carried out independently by the performers of the DB project using independently developed codes. These codes, PASTA, PISA and COPA, incorporate models for stress analysis on the various layers of the TRISO particle (and of the intervening matrix material for some of them), model for fission products release and migration then accumulation within the SiC layer of the TRISO particle, just next to the layer, models for free oxygen and CO formation and migration to the same location, models for temperature field modeling within the various layers of the TRISO particle and models for the prediction of failure rates. All these models may be either internal to the code or external. This large number of models and the possibility of different constitutive data and model formulations and the possibility of a variety of solution techniques makes it highly unlikely that the model would give identical results in the modeling of identical situations. The purpose of this paper is to present the results of an inter-comparison between the codes and to identify areas of agreement and areas that need reconciliation. The inter-comparison has been carried out by the cooperating

  5. Precession electron diffraction for SiC grain boundary characterization in unirradiated TRISO fuel

    International Nuclear Information System (INIS)

    Lillo, T.M.; Rooyen, I.J. van; Wu, Y.Q.

    2016-01-01

    Highlights: • SiC grain orientation determined by TEM-based precession electron diffraction. • Orientation data improved with increasing TEM sample thickness. • Fraction of low angle grain boundaries lower from PED data than EBSD data. • Fractions of high angle and CSL-related boundaries similar to EBSD data. - Abstract: Precession electron diffraction (PED), a transmission electron microscopy-based technique, has been evaluated for the suitability for evaluating grain boundary character in the SiC layer of tristructural isotropic (TRISO) fuel. This work reports the effect of transmission electron microscope (TEM) lamella thickness on the quality of data and establishes a baseline comparison to SiC grain boundary characteristics, in an unirradiated TRISO particle, determined previously using a conventional electron backscatter diffraction (EBSD) scanning electron microscope (SEM)-based technique. In general, it was determined that the lamella thickness produced using the standard focused ion beam (FIB) fabrication process (∼80 nm), is sufficient to provide reliable PED measurements, although thicker lamellae (∼120 nm) were found to produce higher quality orientation data. Also, analysis of SiC grain boundary character from the TEM-based PED data showed a much lower fraction of low-angle grain boundaries compared to SEM-based EBSD data from the SiC layer of a TRISO-coated particle made using the same fabrication parameters and a SiC layer deposited at a slightly lower temperature from a surrogate TRISO particle. However, the fractions of high-angle and coincident site lattice (CSL)-related grain boundaries determined by PED are similar to those found using SEM-based EBSD. Since the grain size of the SiC layer of TRSIO fuel can be as small as 250 nm (Kirchhofer et al., 2013), depending on the fabrication parameters, and since grain boundary fission product precipitates in irradiated TRISO fuel can be nano-sized, the TEM-based PED orientation data

  6. Deposition and Characterization of TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Kyung; Kim, Min Woo; Lee, Hyeon Keun [KAIST, Daejeon (Korea, Republic of); Choi, Doo Jin; Kim, Jun Kyu; Cho, Sung Hyuk [Younsei University, Seoul (Korea, Republic of)

    2008-03-15

    Both ZrC and SiC layers are crucial layers in TRISO coated fuel particles since they prevent diffusion of fission products and provide mechanical strength for the fuel particle. However, each layer has its own defects, so the purpose of this study is to complement such defects of these layers. In this study, we carried out thermodynamic simulations before actual experiments. With these simulation results, we deposited the ZrC layers on SiC/graphite substrates through CVD process. SiC films on graphite have different microstructures which are a hemispherical angular, domed top and faceted structure at different deposition temperature, respectively. According to the microstructures of SiC, preferred orientation, hardness and elastic modules of deposited ZrC layer were changed. TRISO particles. The fracture the SiC coating layer occurred by the tensile stress due to the traditional pressure vessel failure criteria. It is important to find fracture stress of SiC coating layer by the internal pressurization test method. The finite-element analysis was carried out to obtain the empirical equation of strength evaluation. By using this empirical equation, the mechanical properties of several types of SiC coating film with different microstructure and thicknesses will discussed.

  7. Deposition and Characterization of TRISO Coating Layers

    International Nuclear Information System (INIS)

    Kim, Do Kyung; Kim, Min Woo; Lee, Hyeon Keun; Choi, Doo Jin; Kim, Jun Kyu; Cho, Sung Hyuk

    2008-03-01

    Both ZrC and SiC layers are crucial layers in TRISO coated fuel particles since they prevent diffusion of fission products and provide mechanical strength for the fuel particle. However, each layer has its own defects, so the purpose of this study is to complement such defects of these layers. In this study, we carried out thermodynamic simulations before actual experiments. With these simulation results, we deposited the ZrC layers on SiC/graphite substrates through CVD process. SiC films on graphite have different microstructures which are a hemispherical angular, domed top and faceted structure at different deposition temperature, respectively. According to the microstructures of SiC, preferred orientation, hardness and elastic modules of deposited ZrC layer were changed. TRISO particles. The fracture the SiC coating layer occurred by the tensile stress due to the traditional pressure vessel failure criteria. It is important to find fracture stress of SiC coating layer by the internal pressurization test method. The finite-element analysis was carried out to obtain the empirical equation of strength evaluation. By using this empirical equation, the mechanical properties of several types of SiC coating film with different microstructure and thicknesses will discussed

  8. High temperature vitrification of surrogate Savannah River Site (SRS) mixed waste materials

    International Nuclear Information System (INIS)

    Applewhite-Ramsey, A.; Schumacher, R.F.; Spatz, T.L.; Newsom, R.A.; Circeo, L.J.; Danjaji, M.B.

    1995-01-01

    The Savannah River Technology Center (SRTC) has been funded through the DOE Office of Technology Development (DOE-OTD) to investigate high-temperature vitrification technologies for the treatment of diverse low-level and mixed wastes. High temperature vitrification is a likely candidate for processing heterogeneous solid wastes containing low levels of activity. Many SRS wastes fit into this category. Plasma torch technology is one high temperature vitrification method. A trial demonstration of plasma torch processing is being performed at the Georgia Institute of Technology on surrogate SRS wastes. This effort is in cooperation with the Engineering Research and Development Association of Georgia Universities (ERDA) program. The results of phase 1 of these plasma torch trials will be presented

  9. Local-metrics error-based Shepard interpolation as surrogate for highly non-linear material models in high dimensions

    Science.gov (United States)

    Lorenzi, Juan M.; Stecher, Thomas; Reuter, Karsten; Matera, Sebastian

    2017-10-01

    Many problems in computational materials science and chemistry require the evaluation of expensive functions with locally rapid changes, such as the turn-over frequency of first principles kinetic Monte Carlo models for heterogeneous catalysis. Because of the high computational cost, it is often desirable to replace the original with a surrogate model, e.g., for use in coupled multiscale simulations. The construction of surrogates becomes particularly challenging in high-dimensions. Here, we present a novel version of the modified Shepard interpolation method which can overcome the curse of dimensionality for such functions to give faithful reconstructions even from very modest numbers of function evaluations. The introduction of local metrics allows us to take advantage of the fact that, on a local scale, rapid variation often occurs only across a small number of directions. Furthermore, we use local error estimates to weigh different local approximations, which helps avoid artificial oscillations. Finally, we test our approach on a number of challenging analytic functions as well as a realistic kinetic Monte Carlo model. Our method not only outperforms existing isotropic metric Shepard methods but also state-of-the-art Gaussian process regression.

  10. The influence of annealing temperature on the strength of TRISO coated particles

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabel.vanrooyen@pbmr.co.z [Pebble Bed Modular Reactor (Pty) Ltd., 1279 Mike Crawford Avenue, Centurion (South Africa); Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Rooyen, P.M. van [Pebble Bed Modular Reactor (Pty) Ltd., 1279 Mike Crawford Avenue, Centurion (South Africa)

    2010-07-31

    The integrity of the Pebble Bed Modular Reactor (PBMR) fuel, and specifically the SiC layer system of the Tristructural Isotropic (TRISO) coated particle (CP), namely inner pyrolytic carbon, silicon carbide and outer pyrolytic carbon (I-PyC-SiC-O-PyC), determines the containment of fission products. The PBMR fuel consists of TRISO coated particles (CPs) embedded in a graphite matrix. One of the characterization techniques investigated by PBMR is the determination of strength of CPs. It is a well known metallurgical fact that temperature, amongst many other parameters, may influence the strength of a material. A recently developed method for measuring the strength of the TRISO coated particles was used and is briefly described in this article. The advantages of this method are demonstrated by the comparison of strength measurements of five experimental PBMR CP batches as a function of annealing temperature. Significant modification of strength after annealing was measured with increased temperature within the range 1000-2100 {sup o}C. The interesting feature of decreasing standard deviation of the strength with increasing temperature will also be discussed with a possible explanation. A significant difference in coated particle strength is also demonstrated for two CP batches with layer thickness on the extremities of the SiC layer thickness specification. The effect of long duration annealing on these strength values will also be demonstrated by comparing results from 1 h to 100 h annealing periods of coated particles at a temperature of 1600 {sup o}C.

  11. The influence of annealing temperature on the strength of TRISO coated particles

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Neethling, J.H.; Rooyen, P.M. van

    2010-01-01

    The integrity of the Pebble Bed Modular Reactor (PBMR) fuel, and specifically the SiC layer system of the Tristructural Isotropic (TRISO) coated particle (CP), namely inner pyrolytic carbon, silicon carbide and outer pyrolytic carbon (I-PyC-SiC-O-PyC), determines the containment of fission products. The PBMR fuel consists of TRISO coated particles (CPs) embedded in a graphite matrix. One of the characterization techniques investigated by PBMR is the determination of strength of CPs. It is a well known metallurgical fact that temperature, amongst many other parameters, may influence the strength of a material. A recently developed method for measuring the strength of the TRISO coated particles was used and is briefly described in this article. The advantages of this method are demonstrated by the comparison of strength measurements of five experimental PBMR CP batches as a function of annealing temperature. Significant modification of strength after annealing was measured with increased temperature within the range 1000-2100 o C. The interesting feature of decreasing standard deviation of the strength with increasing temperature will also be discussed with a possible explanation. A significant difference in coated particle strength is also demonstrated for two CP batches with layer thickness on the extremities of the SiC layer thickness specification. The effect of long duration annealing on these strength values will also be demonstrated by comparing results from 1 h to 100 h annealing periods of coated particles at a temperature of 1600 o C.

  12. Investigation of the Feasibility of Utilizing Gamma Emission Computed Tomography in Evaluating Fission Product Migration in Irradiated TRISO Fuel Experiments

    International Nuclear Information System (INIS)

    Harp, Jason M.; Demkowicz, Paul A.

    2014-01-01

    In the High Temperature Gas-Cooled Reactor (HTGR) the TRISO particle fuel serves as the primary fission product containment. However the large number of TRISO particles present in proposed HTGRs dictates that there will be a small fraction (~10"-"4 to 10"-"5) of as manufactured defects and in-pile particle failures that will lead to some fission product release. The matrix material surrounding the TRISO particles in fuel compacts and the structural graphite holding the TRISO particles in place can also serve as sinks for containing any released fission products. However data on the migration of solid fission products through these materials is lacking. One of the primary goals of the AGR-3/4 experiment is to study fission product migration from intentionally failed TRISO particles in prototypic HTGR components such as structural graphite and compact matrix material. In this work, the potential for a Gamma Emission Computed Tomography (GECT) technique to non-destructively examine the fission product distribution in AGR-3/4 components and other irradiation experiments is explored. Specifically, the feasibility of using the Idaho National Laboratory (INL) Hot Fuels Examination Facility (HFEF) Precision Gamma Scanner (PGS) system for this GECT application was considered. Previous experience utilizing similar techniques, the expected activities in AGR-3/4 rings, and analysis of this work indicate using GECT to evaluate AGR-3/4 will be feasible. The GECT technique was also applied to other irradiated nuclear fuel systems currently available in the HFEF hot cell, including oxide fuel pins, metallic fuel pins, and monolithic plate fuel. Results indicate GECT with the HFEF PGS is effective. (author)

  13. Design and fabrication of an advanced TRISO fuel with ZrC coating

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Ian E., E-mail: porteri@email.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Knight, Travis W., E-mail: knighttw@cec.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Dulude, Michael C., E-mail: dulude@email.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Roberts, Elwyn, E-mail: robertse@cec.sc.edu [University of South Carolina, Mechanical Engineering Department, 300 Main Street, Columbia, SC 29208, United Sates (United States); Hobbs, Jim, E-mail: JSHobbs@nuclearfuelservices.com [Nuclear Fuel Services, Inc., 1205 Banner Hill Road, Erwin, TN 37650 (United States)

    2013-06-15

    Highlights: • Zirconium carbide was deposited on surrogate zirconia and UO{sub 2} kernels. • Deposition rates were found to be dependent on temperature and gas concentration. • Calcining and sintering parameters were optimized to reduce cracking in UO{sub 2} kernel production. -- Abstract: Very high temperature reactors (VHTRs) are expected to achieve coolant outlet temperatures up to 1000 °C, allowing for increased plant efficiency as well as the ability to use the process heat for hydrogen production and various uses in the process chemical industry. The feasibility of using VHTRs as part of the next generation of nuclear reactors greatly depends on the reliability of tri-structural isotropic (TRISO) fuel particles to retain both gaseous and metallic fission products created in irradiated uranium dioxide (UO{sub 2}). This work sought the deposition parameters necessary to produce an additional zirconium carbide (ZrC) layer used in advanced coated particle fuels. The additional ZrC layer will act as an oxygen getter to prevent typical TRISO failure mechanisms including over pressurization of the particle and kernel migration of the kernel within the particle, also known as the amoeba effect. In this study, ZrC coatings were applied to surrogate zirconia kernels as well as UO{sub 2} kernels using a chemical vapor deposition (CVD) fluidized bed reactor, and the deposition characteristics were analyzed via scanning electron microscopy (SEM) techniques. The ZrC layer was confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The calcining and sintering of urania kernels for use in these coating experiments is also discussed.

  14. Design and fabrication of an advanced TRISO fuel with ZrC coating

    International Nuclear Information System (INIS)

    Porter, Ian E.; Knight, Travis W.; Dulude, Michael C.; Roberts, Elwyn; Hobbs, Jim

    2013-01-01

    Highlights: • Zirconium carbide was deposited on surrogate zirconia and UO 2 kernels. • Deposition rates were found to be dependent on temperature and gas concentration. • Calcining and sintering parameters were optimized to reduce cracking in UO 2 kernel production. -- Abstract: Very high temperature reactors (VHTRs) are expected to achieve coolant outlet temperatures up to 1000 °C, allowing for increased plant efficiency as well as the ability to use the process heat for hydrogen production and various uses in the process chemical industry. The feasibility of using VHTRs as part of the next generation of nuclear reactors greatly depends on the reliability of tri-structural isotropic (TRISO) fuel particles to retain both gaseous and metallic fission products created in irradiated uranium dioxide (UO 2 ). This work sought the deposition parameters necessary to produce an additional zirconium carbide (ZrC) layer used in advanced coated particle fuels. The additional ZrC layer will act as an oxygen getter to prevent typical TRISO failure mechanisms including over pressurization of the particle and kernel migration of the kernel within the particle, also known as the amoeba effect. In this study, ZrC coatings were applied to surrogate zirconia kernels as well as UO 2 kernels using a chemical vapor deposition (CVD) fluidized bed reactor, and the deposition characteristics were analyzed via scanning electron microscopy (SEM) techniques. The ZrC layer was confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The calcining and sintering of urania kernels for use in these coating experiments is also discussed

  15. HIGH-TEMPERATURE SAFETY TESTING OF IRRADIATED AGR-1 TRISO FUEL

    Energy Technology Data Exchange (ETDEWEB)

    Stempien, John D.; Demkowicz, Paul A.; Reber, Edward L.; Chrisensen, Cad L.

    2016-11-01

    primary goals. First, the test was intended to assess the retention of fission products in loose kernels without the effects of the other TRISO layers (buffer, IPyC, SiC, and OPyC) or the graphitic matrix material comprising the compact. Second, this test served as an evaluation of the FACS fission product condensation plate collection efficiency.

  16. Local atomic structure of Pd and Ag in the SiC containment layer of TRISO fuel particles fissioned to 20% burn-up

    Science.gov (United States)

    Seibert, Rachel L.; Terrani, Kurt A.; Velázquez, Daniel; Hunn, John D.; Baldwin, Charles A.; Montgomery, Fred C.; Terry, Jeff

    2018-03-01

    The structure and speciation of fission products within the SiC barrier layer of tristructural-isotropic (TRISO) fuel particles irradiated to 19.6% fissions per initial metal atom (FIMA) burnup in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) was investigated. As-irradiated fuel particles, as well as those subjected to simulated accident scenarios, were examined. The TRISO particles were characterized using synchrotron X-ray absorption fine-structure spectroscopy (XAFS) at the Materials Research Collaborative Access Team (MRCAT) beamline at the Advanced Photon Source. The TRISO particles were produced at Oak Ridge National Laboratory under the Advanced Gas Reactor Fuel Development and Qualification Program and sent to the ATR for irradiation. XAFS measurements on the palladium and silver K-edges were collected using the MRCAT undulator beamline. Analysis of the Pd edge indicated the formation of palladium silicides of the form PdxSi (2 ≤ x ≤ 3). In contrast, Ag was found to be metallic within the SiC shell safety tested to 1700 °C. To the best of our knowledge, this is the first result demonstrating metallic bonding of silver from fissioned samples. Knowledge of these reaction pathways will allow for better simulations of radionuclide transport in the various coating layers of TRISO fuels for next generation nuclear reactors. They may also suggest different ways to modify TRISO particles to improve their fuel performance and to mitigate potential fission product release under both normal operation and accident conditions.

  17. Fragrance materials in asthma: a pilot study using a surrogate aerosol product.

    Science.gov (United States)

    Vethanayagam, Dilini; Vliagoftis, Harissios; Mah, Dennell; Beach, Jeremy; Smith, Ladd; Moqbel, Redwan

    2013-11-01

    Many household products contain fragrances. Little is known about exposure to fragrances on human health, particularly within the airways. This study aimed to evaluate how common household fragrance products (i.e. air fresheners, cleaning products) affect people with asthma, who frequently report sensitivity to these products. Many of these products have volatile organic compounds or semi-volatile organic compounds. This study evaluated nine fragrance materials in an aerosol formulation to assess effects on airway physiology, airway inflammation and symptom perception in normal controls and those with asthma. The effects of fragrances were evaluated in people without asthma, people with mild asthma and people with moderate asthma in a four-way crossover placebo-controlled study. Subjects were exposed twice to a fragranced aerosol and twice to a placebo aerosol (15 and 30 min each). Subjects completed a questionnaire for 29 symptoms during and up to 3 h after each exposure scenario. Spirometry was performed prior to and 3 h post-exposure; sputum induction was conducted 3 h post-exposure. Nasal symptoms showed the greatest frequency of response in all three subject groups, and moderate asthmatics reported the greatest symptom severity and symptom types. No significant differences were noted in physiology or cellular inflammation. A trend for increased symptoms was noted in moderate asthmatics, suggesting that asthma severity may play a factor in fragrance sensitivity.

  18. Evaluation of the mechanical performance of silicon carbide in TRISO fuel at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rohbeck, Nadia, E-mail: nadia.rohbeck@manchester.ac.uk; Xiao, Ping, E-mail: p.xiao@manchester.ac.uk

    2016-09-15

    The HTR design envisions fuel operating temperatures of up to 1000 °C and in case of an accident even 1600 °C are conceivable. To ensure safety in all conditions a thorough understanding of the impact of an extreme temperature environment is necessary. This work assesses the high temperature mechanical performance of the silicon carbide (SiC) layer within the tristructural-isotropic (TRISO) fuel particle as it poses the main barrier against fission product release into the primary circuit. Therefore, simulated fuel was fabricated by fluidized bed chemical vapour deposition; varying the deposition conditions resulted in strongly differing SiC microstructures for the various samples. Subsequently the TRISO particles were annealed in inert atmosphere at temperatures ranging from 1600 °C up to 2200 °C. Scanning electron microscopy and Raman spectroscopy showed that strong disintegration of the SiC layer occurred from 2100 °C onwards, but initial signs of porosity formation were visible already at 1800 °C. Still, the elastic modulus and hardness as measured by nanoindentation were hardly impaired. After annealing stoichiometric SiC coatings showed a reduction in fracture strength as determined by a modified crush test, however the actual annealing temperature from 1600 °C to 2000 °C had no measureable effect. Furthermore, a technique was developed to measure the elastic modulus and hardness in situ up to 500 °C using a high temperature nanoindentation facility. This approach allows conducting tests while the specimen and indenter tip are heated to a specific measurement temperature, thus obtaining reliable values for the temperature dependent mechanical properties of the material. For the SiC layer in TRISO particles it was found that the elastic modulus decreased slightly from room temperature up to 500 °C, whereas the hardness was reduced more severely to approximately half of its ambient temperature value.

  19. Selection and properties of alternative forming fluids for TRISO fuel kernel production

    Energy Technology Data Exchange (ETDEWEB)

    Baker, M.P. [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); King, J.C., E-mail: kingjc@mines.edu [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Gorman, B.P. [Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Marshall, D.W. [Idaho National Laboratory, 2525 N. Fremont Avenue, P.O. Box 1625, Idaho Falls, ID 83415 (United States)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Forming fluid selection criteria developed for TRISO kernel production. Black-Right-Pointing-Pointer Ten candidates selected for further study. Black-Right-Pointing-Pointer Density, viscosity, and surface tension measured for first time. Black-Right-Pointing-Pointer Settling velocity and heat transfer rates calculated. Black-Right-Pointing-Pointer Three fluids recommended for kernel production testing. - Abstract: Current Very High Temperature Reactor (VHTR) designs incorporate TRi-structural ISOtropic (TRISO) fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel using wet chemistry to produce uranium oxyhydroxide gel spheres by dropping a cold precursor solution into a hot column of trichloroethylene (TCE). Over time, gelation byproducts inhibit complete gelation, and the TCE must be purified or discarded. The resulting TCE waste stream contains both radioactive and hazardous materials and is thus considered a mixed hazardous waste. Changing the forming fluid to a non-hazardous alternative could greatly improve the economics of TRISO fuel kernel production. Selection criteria for a replacement forming fluid narrowed a list of {approx}10,800 chemicals to yield ten potential replacement forming fluids: 1-bromododecane, 1-bromotetradecane, 1-bromoundecane, 1-chlorooctadecane, 1-chlorotetradecane, 1-iododecane, 1-iodododecane, 1-iodohexadecane, 1-iodooctadecane, and squalane. The density, viscosity, and surface tension for each potential replacement forming fluid were measured as a function of temperature between 25 Degree-Sign C and 80 Degree-Sign C. Calculated settling velocities and heat transfer rates give an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane show the greatest promise as replacements, and future tests will verify their ability to form satisfactory

  20. Evaluation of the mechanical performance of silicon carbide in TRISO fuel at high temperatures

    International Nuclear Information System (INIS)

    Rohbeck, Nadia; Xiao, Ping

    2016-01-01

    The HTR design envisions fuel operating temperatures of up to 1000 °C and in case of an accident even 1600 °C are conceivable. To ensure safety in all conditions a thorough understanding of the impact of an extreme temperature environment is necessary. This work assesses the high temperature mechanical performance of the silicon carbide (SiC) layer within the tristructural-isotropic (TRISO) fuel particle as it poses the main barrier against fission product release into the primary circuit. Therefore, simulated fuel was fabricated by fluidized bed chemical vapour deposition; varying the deposition conditions resulted in strongly differing SiC microstructures for the various samples. Subsequently the TRISO particles were annealed in inert atmosphere at temperatures ranging from 1600 °C up to 2200 °C. Scanning electron microscopy and Raman spectroscopy showed that strong disintegration of the SiC layer occurred from 2100 °C onwards, but initial signs of porosity formation were visible already at 1800 °C. Still, the elastic modulus and hardness as measured by nanoindentation were hardly impaired. After annealing stoichiometric SiC coatings showed a reduction in fracture strength as determined by a modified crush test, however the actual annealing temperature from 1600 °C to 2000 °C had no measureable effect. Furthermore, a technique was developed to measure the elastic modulus and hardness in situ up to 500 °C using a high temperature nanoindentation facility. This approach allows conducting tests while the specimen and indenter tip are heated to a specific measurement temperature, thus obtaining reliable values for the temperature dependent mechanical properties of the material. For the SiC layer in TRISO particles it was found that the elastic modulus decreased slightly from room temperature up to 500 °C, whereas the hardness was reduced more severely to approximately half of its ambient temperature value.

  1. A study on the basic CVD process technology for TRISO coated particle fuel

    International Nuclear Information System (INIS)

    Choi, D. J.; Cheon, J. H.; Keum, I. S.; Lee, H. S.; Kim, J. G.

    2006-03-01

    Hydrogen energy has many advantages and is suitable as alternative energy of fossil fuel. The study of nuclear hydrogen production has performed at present. For nuclear hydrogen production, it is needed the study of VHTR(Very High Temperature Reactor) and TRISO(TRI-iSOtropic) coated fuel. TRISO coated fuel particle deposited by FBCVD(Fludized Bed CVD) method is composed of three isotropic layers: Inner Pyrolytic Carbon (IPyC), Silicon Carbide (SiC), Outer Pyrolytic Carbon (OPyC) layers. Silicon carbide was chemically vapor deposed on graphite substrate using methyltrichlorosilane (CH 3 SiCl 3 ) as a source in hydrogen atmosphere. The effect of deposition temperature and input gas ratios ( α=Q H2 /Q MTS =P H2 /P MTS ) was investigated in order to find out characteristics of silicon carbide layer. From results of those, SiC-TRISO coating deposition was conducted and achieved. Zirconium carbide layer as an advanced material of silicon carbide layer has studied. In order to find out basic properties and characteristics, studies have conducted using various methods. Zirconium carbide is chemically vapor deposed subliming zirconium tetrachloride(ZrCl 4 ) and using methan(CH 4 ) as a source in hydrogen atmosphere. Many experiments were conducted on graphite substrate about many deposition conditions such as ZrCl 4 heating temperatures and variables of H2 and CH 4 flow rate. but carbon graphite was deposited. For deposition of zirconium carbide, several different methods were approached. so zirconium carbide deposed on ZrO 2 substrate. In this experiments. source subliming type and equipment are no problems. But deposition of zirconium carbide will be continuously studied on graphite substrate approaching views of experimental way and equipment structure

  2. Surrogate motherhood

    OpenAIRE

    Arteta-Acosta Cindy

    2011-01-01

    Surrogate motherhood, also known as surrogacy, has recently become achance to exercise the right of paternity by some people. Surrogacy itself did notinvolve a disadvantaged idea, but when this is coupled with scientific experimentsand economic and personal interests, requires intervention of the State tolegislate about consequences arising from the unlimited execution of this practice. Since 70’s,developed countries have been creating laws, decrees and regulations to regulateassisted reprodu...

  3. A simple surrogate test method to rank the wear performance of prospective ceramic materials under hip prosthesis edge-loading conditions.

    Science.gov (United States)

    Sanders, Anthony P; Brannon, Rebecca M

    2014-02-01

    This research has developed a novel test method for evaluating the wear resistance of ceramic materials under severe contact stresses simulating edge loading in prosthetic hip bearings. Simply shaped test specimens - a cylinder and a spheroid - were designed as surrogates for an edge-loaded, head/liner implant pair. Equivalency of the simpler specimens was assured in the sense that their theoretical contact dimensions and pressures were identical, according to Hertzian contact theory, to those of the head/liner pair. The surrogates were fabricated in three ceramic materials: Al2 O3 , zirconia-toughened alumina (ZTA), and ZrO2 . They were mated in three different material pairs and reciprocated under a 200 N normal contact force for 1000-2000 cycles, which created small (material pairs were ranked by their wear resistance, quantified by the volume of abraded material measured using an interferometer. Similar tests were performed on edge-loaded hip implants in the same material pairs. The surrogates replicated the wear rankings of their full-scale implant counterparts and mimicked their friction force trends. The results show that a proxy test using simple test specimens can validly rank the wear performance of ceramic materials under severe, edge-loading contact stresses, while replicating the beginning stage of edge-loading wear. This simple wear test is therefore potentially useful for screening and ranking new, prospective materials early in their development, to produce optimized candidates for more complicated full-scale hip simulator wear tests. Copyright © 2013 Wiley Periodicals, Inc.

  4. Fabrication and characterization of SiC and ZrC composite coating on TRISO coated particle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. G.; Lee, S. H.; Kim, D. J.; Park, J. Y.; Kim, W. J. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    SiC coating is widely suggested as structural materials for nuclear application due to its excellent high irradiation resistance properties and high temperature mechanical properties. SiC coating on TRistructural-ISOtropic (TRISO) coated fuel particles plays an important role as a protective layer from radioactive fission gas and a mechanical structural layer. TRISO coating layer was deposited on a spherical particle by a FBCVD method. The ZrO{sub 2} spherical particles were used as a simulant kernel. TRISO coating layers consisting of a porous buffer layer, an inner PyC layer were sequentially deposited before depositing SiC or ZrC coating layer. In order investigate the phase of each composite coating layer, Raman analysis was conducted. SiC, ZrC coating and SiC/ZrC composite coating on spherical particle were successfully deposited via FBCVD method by adjusting source gas flow rate. In the SiC and ZrC composite coating, SiC phase and ZrC phase were observed by XRD and SEM analysis. In the condition of 100 sccm of ZrCl{sub 4}, 25 sccm of CH{sub 4}, and 30 sccm of MTS, only two phases of SiC and ZrC were observed and two phases are located with clean grain boundary.

  5. High-quality thorium TRISO fuel performance in HTGRs

    Energy Technology Data Exchange (ETDEWEB)

    Verfondern, Karl [Forschungszentrum Juelich GmbH (Germany); Allelein, Hans-Josef [Forschungszentrum Juelich GmbH (Germany); Technische Hochschule Aachen (Germany); Nabielek, Heinz; Kania, Michael J.

    2013-11-01

    Thorium as a nuclear fuel has received renewed interest, because of its widespread availability and the good irradiation performance of Th and mixed (Th,U) oxide compounds as fuels in nuclear power systems. Early HTGR development employed thorium together with high-enriched uranium (HEU). After 1980, HTGR fuel systems switched to low-enriched uranium (LEU). After completing fuel development for the AVR and the THTR with BISO coated particles, the German program expanded its efforts utilizing thorium and HEU TRISO coated particles in advanced HTGR concepts for process heat applications (PNP) and direct-cycle electricity production (HHT). The combination of a low-temperature isotropic (LTI) inner and outer pyrocarbon layers surrounding a strong, stable SiC layer greatly improved manufacturing conditions and the subsequent contamination and defective particle fractions in production fuel elements. In addition, this combination provided improved mechanical strength and a higher degree of solid fission product retention, not known previously with high-temperature isotropic (HTI) BISO coatings. The improved performance of the HEU (Th, U)O{sub 2} TRISO fuel system was successfully demonstrated in three primary areas of development: manufacturing, irradiation testing under normal operating conditions, and accident simulation testing. In terms of demonstrating performance for advanced HTGR applications, the experimental failure statistic from manufacture and irradiation testing are significantly below the coated particle requirements specified for PNP and HHT designs at the time. Covering a range to 1300 C in normal operations and 1600 C in accidents, with burnups to 13% FIMA and fast fluences to 8 x 10{sup 25} n/m{sup 2} (E> 16 fJ), the performance results exceed the design limits on manufacturing and operational requirements for the German HTR-Modul concept, which are 6.5 x 10{sup -5} for manufacturing, 2 x 10{sup -4} for normal operating conditions, and 5 x 10{sup -4

  6. Silver diffusion through silicon carbide in microencapsulated nuclear fuels TRISO

    International Nuclear Information System (INIS)

    Cancino T, F.; Lopez H, E.

    2013-10-01

    The silver diffusion through silicon carbide is a challenge that has persisted in the development of microencapsulated fuels TRISO (Tri structural Isotropic) for more than four decades. The silver is known as a strong emitter of gamma radiation, for what is able to diffuse through the ceramic coatings of pyrolytic coal and silicon carbide and to be deposited in the heat exchangers. In this work we carry out a recount about the art state in the topic of the diffusion of Ag through silicon carbide in microencapsulated fuels and we propose the role that the complexities in the grain limit can have this problem. (Author)

  7. High-quality thorium TRISO fuel performance in HTGRs

    International Nuclear Information System (INIS)

    Verfondern, Karl; Allelein, Hans-Josef; Nabielek, Heinz; Kania, Michael J.

    2013-01-01

    Thorium as a nuclear fuel has received renewed interest, because of its widespread availability and the good irradiation performance of Th and mixed (Th,U) oxide compounds as fuels in nuclear power systems. Early HTGR development employed thorium together with high-enriched uranium (HEU). After 1980, HTGR fuel systems switched to low-enriched uranium (LEU). After completing fuel development for the AVR and the THTR with BISO coated particles, the German program expanded its efforts utilizing thorium and HEU TRISO coated particles in advanced HTGR concepts for process heat applications (PNP) and direct-cycle electricity production (HHT). The combination of a low-temperature isotropic (LTI) inner and outer pyrocarbon layers surrounding a strong, stable SiC layer greatly improved manufacturing conditions and the subsequent contamination and defective particle fractions in production fuel elements. In addition, this combination provided improved mechanical strength and a higher degree of solid fission product retention, not known previously with high-temperature isotropic (HTI) BISO coatings. The improved performance of the HEU (Th, U)O 2 TRISO fuel system was successfully demonstrated in three primary areas of development: manufacturing, irradiation testing under normal operating conditions, and accident simulation testing. In terms of demonstrating performance for advanced HTGR applications, the experimental failure statistic from manufacture and irradiation testing are significantly below the coated particle requirements specified for PNP and HHT designs at the time. Covering a range to 1300 C in normal operations and 1600 C in accidents, with burnups to 13% FIMA and fast fluences to 8 x 10 25 n/m 2 (E> 16 fJ), the performance results exceed the design limits on manufacturing and operational requirements for the German HTR-Modul concept, which are 6.5 x 10 -5 for manufacturing, 2 x 10 -4 for normal operating conditions, and 5 x 10 -4 for accident conditions. These

  8. TRISO fuel thermal simulations in the LS-VHTR

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Mario C.; Scari, Maria E.; Costa, Antonella L.; Pereira, Claubia; Veloso, Maria A.F., E-mail: marc5663@gmail.com, E-mail: melizabethscari@yahoo.com, E-mail: antonella@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br, E-mail: dora@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Instituto Nacional de Ciência e Tecnologia de Reatores Nucleares Inovadores/CNPq (Brazil)

    2017-07-01

    The liquid-salt-cooled very high-temperature reactor (LS-VHTR) is a reactor that presents very good characteristics in terms of energy production and safety aspects. It uses as fuel the TRISO particles immersed in a graphite matrix with a cylindrical shape called fuel compact, as moderator graphite and as coolant liquid salt Li{sub 2}BeF{sub 4} called Flibe. This work evaluates the thermal hydraulic performance of the heat removal system and the reactor core by performing different simplifications to represent the reactor core and the fuel compact under steady-state conditions, starting the modeling from a single fuel element, until complete the studies with the entire core model developed in the RELAP5-3D code. Two models were considered for representation of the fuel compact, homogeneous and non-homogeneous models, as well as different geometries of the heat structures was considered. The aim to develop several models was to compare the thermal hydraulic characteristics resulting from the construction of a more economical and less discretized model with much more refined models that can lead to more complexes analyzes to representing TRISO effect particles in the fuel compact. The different results found, mainly, for the core temperature distributions are presented and discussed. (author)

  9. Experimental Design for a Macrofoam-Swab Study Relating the Recovery Efficiency and False Negative Rate to Low Concentrations of Two Bacillus anthracis Surrogates on Four Surface Materials

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-12-05

    This report describes the experimental design for a laboratory study to quantify the recovery efficiencies and false negative rates of a validated, macrofoam-swab sampling method for low concentrations of Bacillus anthracis Sterne (BAS) and Bacillus atrophaeus (BG) spores on four surface materials (stainless steel, glass, vinyl tile, plastic light cover panel). Two analytical methods (culture and polymerase chain reaction) will be used. Only one previous study has investigated how the false negative rate depends on test factors. The surrogates BAS and BG have not been tested together in the same study previously. Hence, this study will provide for completing gaps in the available information on the performance of macrofoam-swab sampling at low concentrations.

  10. Experimental Design for a Macrofoam Swab Study Relating the Recovery Efficiency and False Negative Rate to Low Concentrations of Two Bacillus anthracis Surrogates on Four Surface Materials

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F.; Hutchison, Janine R.

    2014-04-16

    This report describes the experimental design for a laboratory study to quantify the recovery efficiencies and false negative rates of a validated, macrofoam swab sampling method for low concentrations of Bacillus anthracis Sterne (BAS) and Bacillus atrophaeus (BG) spores on four surface materials (stainless steel, glass, vinyl tile, plastic light cover panel). Two analytical methods (plating/counting and polymerase chain reaction) will be used. Only one previous study has investigated false negative as a function of affecting test factors. The surrogates BAS and BG have not been tested together in the same study previously. Hence, this study will provide for completing gaps in the available information on the performance of macrofoam swab sampling at low concentrations.

  11. Thermochemical equilibrium in a kernel of a UN TRISO coated fuel particle

    International Nuclear Information System (INIS)

    Kim, Young Min; Jo, C. K.; Lim, H. S.; Cho, M. S.; Lee, W. J.

    2012-01-01

    A coated fuel particle (CFP) with a uranium mononitride (UN) kernel has been recently considered as an advanced fuel option, such as in fully ceramic micro encapsulated (FCM) replacement fuel for light water reactors (LWRs). In FCM fuel, a large number of tri isotropic coated fuel particles (TRISOs) are embedded in a silicon carbide (SiC) matrix. Thermochemical equilibrium calculations can predict the chemical behaviors of a kernel in a TRISO of FCM fuel during irradiation. They give information on the kind and quantity of gases generated in a kernel during irradiation. This study treats the quantitative analysis of thermochemical equilibrium in a UN TRISO of FCM LWR fuel using HSC software

  12. TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Jeffrey James [Univ. of California, Berkeley, CA (United States)

    2011-11-30

    This study focused on creating a new tristructural isotropic (TRISO) coated particle fuel performance model and demonstrating the integration of this model into an existing system of neutronics and heat transfer codes, creating a user-friendly option for including fuel performance analysis within system design optimization and system-level trade-off studies. The end product enables both a deeper understanding and better overall system performance of nuclear energy systems limited or greatly impacted by TRISO fuel performance. A thorium-fueled hybrid fusion-fission Laser Inertial Fusion Energy (LIFE) blanket design was used for illustrating the application of this new capability and demonstrated both the importance of integrating fuel performance calculations into mainstream design studies and the impact that this new integrated analysis had on system-level design decisions. A new TRISO fuel performance model named TRIUNE was developed and verified and validated during this work with a novel methodology established for simulating the actual lifetime of a TRISO particle during repeated passes through a pebble bed. In addition, integrated self-consistent calculations were performed for neutronics depletion analysis, heat transfer calculations, and then fuel performance modeling for a full parametric study that encompassed over 80 different design options that went through all three phases of analysis. Lastly, side studies were performed that included a comparison of thorium and depleted uranium (DU) LIFE blankets as well as some uncertainty quantification work to help guide future experimental work by assessing what material properties in TRISO fuel performance modeling are most in need of improvement. A recommended thorium-fueled hybrid LIFE engine design was identified with an initial fuel load of 20MT of thorium, 15% TRISO packing within the graphite fuel pebbles, and a 20cm neutron multiplier layer with beryllium pebbles in flibe molten salt coolant. It operated

  13. Acceptance Test Data for Candidate AGR-5/6/7 TRISO Particle Batches BWXT Coater Batches 93165 93172 Defective IPyC Fraction and Pyrocarbon Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Helmreich, Grant W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hunn, John D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Skitt, Darren J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dyer, John A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schumacher, Austin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    Coated particle fuel batches J52O-16-93165, 93166, 93168, 93169, 93170, and 93172 were produced by Babcock and Wilcox Technologies (BWXT) for possible selection as fuel for the Advanced Gas Reactor Fuel Development and Qualification (AGR) Program’s AGR-5/6/7 irradiation test in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR). Some of these batches may alternately be used as demonstration coated particle fuel for other experiments. Each batch was coated in a 150-mm-diameter production-scale fluidized-bed chemical vapor deposition (CVD) furnace. Tristructural isotropic (TRISO) coatings were deposited on 425-μm-nominal-diameter spherical kernels from BWXT lot J52R-16-69317 containing a mixture of 15.5%-enriched uranium carbide and uranium oxide (UCO). The TRISO coatings consisted of four consecutive CVD layers: a ~50% dense carbon buffer layer with 100-μm-nominal thickness, a dense inner pyrolytic carbon (IPyC) layer with 40-μm-nominal thickness, a silicon carbide (SiC) layer with 35-μm-nominal thickness, and a dense outer pyrolytic carbon (OPyC) layer with 40-μmnominal thickness. The TRISO-coated particle batches were sieved to upgrade the particles by removing over-sized and under-sized material, and the upgraded batches were designated by appending the letter A to the end of the batch number (e.g., 93165A).

  14. Straight-chain halocarbon forming fluids for TRISO fuel kernel production – Tests with yttria-stabilized zirconia microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Baker, M.P. [Nuclear Science and Engineering Program, Metallurgical and Materials Engineering Department, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); King, J.C., E-mail: kingjc@mines.edu [Nuclear Science and Engineering Program, Metallurgical and Materials Engineering Department, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Gorman, B.P. [Metallurgical and Materials Engineering Department, Colorado Center for Advanced Ceramics, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Braley, J.C. [Nuclear Science and Engineering Program, Chemistry and Geochemistry Department, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States)

    2015-03-15

    Highlights: • YSZ TRISO kernels formed in three alternative, non-hazardous forming fluids. • Kernels characterized for size, shape, pore/grain size, density, and composition. • Bromotetradecane is suitable for further investigation with uranium-based precursor. - Abstract: Current methods of TRISO fuel kernel production in the United States use a sol–gel process with trichloroethylene (TCE) as the forming fluid. After contact with radioactive materials, the spent TCE becomes a mixed hazardous waste, and high costs are associated with its recycling or disposal. Reducing or eliminating this mixed waste stream would not only benefit the environment, but would also enhance the economics of kernel production. Previous research yielded three candidates for testing as alternatives to TCE: 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane. This study considers the production of yttria-stabilized zirconia (YSZ) kernels in silicone oil and the three chosen alternative formation fluids, with subsequent characterization of the produced kernels and used forming fluid. Kernels formed in silicone oil and bromotetradecane were comparable to those produced by previous kernel production efforts, while those produced in chlorooctadecane and iodododecane experienced gelation issues leading to poor kernel formation and geometry.

  15. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    International Nuclear Information System (INIS)

    Heath, Paul G.; Corkhill, Claire L.; Stennett, Martin C.; Hand, Russell J.; Meyer, Willem C.H.M.; Hyatt, Neil C.

    2013-01-01

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle–glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers’ hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H 2 /N 2 atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle–glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required

  16. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Heath, Paul G.; Corkhill, Claire L.; Stennett, Martin C.; Hand, Russell J. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, Robert Hadfield Building, University of Sheffield, Sheffield S1 3JD (United Kingdom); Meyer, Willem C.H.M. [Necsa, South African Nuclear Energy Corporation, PO Box 582, Pretoria, Gauteng (South Africa); Hyatt, Neil C., E-mail: n.c.hyatt@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, Robert Hadfield Building, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2013-05-15

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle–glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers’ hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H{sub 2}/N{sub 2} atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle–glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required.

  17. Novel approaches for the in situ study of the sintering of nuclear oxide fuel materials and their surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, Nicolas; Nkou Bouala, Galy Ingrid; Dacheux, Nicolas; Podor, Renaud [Montpellier Univ., Bagnols sur Ceze (France). ICSM - UMR 5257 CEA/CNRS/ENSCM; Lechelle, Jacques [CEA, DNE, DEC, SESC, LLCC, St-Paul lez Durance (France); Martinez, Julien [CEA, DEN, DTEC, SECA, LFC, Bagnols sur Ceze (France)

    2017-07-01

    Sintering is one of the key-points of the processing of ceramic materials. It is then of primary interest for the nuclear fuel cycle, in which it constitutes an important step in the fabrication of either UO{sub 2} or (U,Pu)O{sub 2} pellets used in current PWR reactors. The sintering of actinides oxides not only drives the final density and microstructure of the fuels, but also several characteristics that can impact significantly their behavior in the reactor. Dedicated tools are then needed to monitor the microstructure of such materials and forecast their evolution. In this frame, this paper presents the new potentialities offered by the use of environmental scanning electron microscope at high temperature (HT-ESEM) for the study of nuclear ceramics sintering. First, the results obtained from bulk pellets are detailed, either regarding original fundamental data at the grain level (such as grain boundaries and pores motion), or design of dedicated microstructures through the assessment of grain growth kinetics. Acquisition of sintering maps thanks to the combination of HT-ESEM observations and classical dilatometric measurements are also addressed. In a second part, observations undertaken at the 2-grain scale to monitor the first stage of sintering, dedicated to neck elaboration, are presented, and compared to the results currently provided by numerical models.

  18. X-ray Analysis of Defects and Anomalies in AGR-5/6/7 TRISO Particles

    Energy Technology Data Exchange (ETDEWEB)

    Helmreich, Grant W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hunn, John D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Skitt, Darren J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dyer, John A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schumacher, Austin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    Coated particle fuel batches J52O-16-93164, 93165, 93166, 93168, 93169, 93170, and 93172 were produced by Babcock and Wilcox Technologies (BWXT) for possible selection as fuel for the Advanced Gas Reactor Fuel Development and Qualification (AGR) Program’s AGR-5/6/7 irradiation test in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR), or may be used for other tests. Each batch was coated in a 150-mm-diameter production-scale fluidized-bed chemical vapor deposition (CVD) furnace. Tristructural isotropic (TRISO) coatings were deposited on 425-μm-nominal-diameter spherical kernels from BWXT lot J52R-16-69317 containing a mixture of 15.4%-enriched uranium carbide and uranium oxide (UCO), with the exception of Batch 93164, which used similar kernels from BWXT lot J52L-16-69316. The TRISO-coatings consisted of a ~50% dense carbon buffer layer with 100-μmnominal thickness, a dense inner pyrolytic carbon (IPyC) layer with 40-μm-nominal thickness, a silicon carbide (SiC) layer with 35-μm-nominal thickness, and a dense outer pyrolytic carbon (OPyC) layer with 40-μm-nominal thickness. Each coated particle batch was sieved to upgrade the particles by removing over-sized and under-sized material, and the upgraded batch was designated by appending the letter A to the end of the batch number (e.g., 93164A). Secondary upgrading by sieving was performed on the upgraded batches to remove specific anomalies identified during analysis for Defective IPyC, and the upgraded batches were designated by appending the letter B to the end of the batch number (e.g., 93165B). Following this secondary upgrading, coated particle composite J52R-16-98005 was produced by BWXT as fuel for the AGR Program’s AGR-5/6/7 irradiation test in the INL ATR. This composite was comprised of coated particle fuel batches J52O-16-93165B, 93168B, 93169B, and 93170B.

  19. Performance Analysis Review of Thorium TRISO Coated Particles during Manufacture, Irradiation and Accident Condition Heating Tests

    International Nuclear Information System (INIS)

    2015-03-01

    Thorium, in combination with high enriched uranium, was used in all early high temperature reactors (HTRs). Initially, the fuel was contained in a kernel of coated particles. However, particle quality was low in the 1960s and early 1970s. Modern, high quality, tristructural isotropic (TRISO) fuel particles with thorium oxide and uranium dioxide (UO 2 ) had been manufactured since 1978 and were successfully demonstrated in irradiation and accident tests. In 1980, HTR fuels changed to low enriched uranium UO 2 TRISO fuels. The wide ranging development and demonstration programme was successful, and it established a worldwide standard that is still valid today. During the process, results of the thorium work with high quality TRISO fuel particles had not been fully evaluated or documented. This publication collects and presents the information and demonstrates the performance of thorium TRISO fuels.This publication is an outcome of the technical contract awarded under the IAEA Coordinated Research Project on Near Term and Promising Long Term Options for Deployment of Thorium Based Nuclear Energy, initiated in 2012. It is based on the compilation and analysis of available results on thorium TRISO coated particle performance in manufacturing and during irradiation and accident condition heating tests

  20. TRISO coated fuel particles with enhanced SiC properties

    International Nuclear Information System (INIS)

    Lopez-Honorato, E.; Tan, J.; Meadows, P.J.; Marsh, G.; Xiao, P.

    2009-01-01

    The silicon carbide (SiC) layer used for the formation of TRISO coated fuel particles is normally produced at 1500-1650 deg. C via fluidized bed chemical vapor deposition from methyltrichlorosilane in a hydrogen environment. In this work, we show the deposition of SiC coatings with uniform grain size throughout the coating thickness, as opposed to standard coatings which have larger grain sizes in the outer sections of the coating. Furthermore, the use of argon as the fluidizing gas and propylene as a carbon precursor, in addition to hydrogen and methyltrichlorosilane, allowed the deposition of stoichiometric SiC coatings with refined microstructure at 1400 and 1300 deg. C. The deposition of SiC at lower deposition temperatures was also advantageous since the reduced heat treatment was not detrimental to the properties of the inner pyrolytic carbon which generally occurs when SiC is deposited at 1500 deg. C. The use of a chemical vapor deposition coater with four spouts allowed the deposition of uniform and spherical coatings.

  1. Nanocrystalline SiC and Ti3SiC2 Alloys for Reactor Materials: Diffusion of Fission Product Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jiang, Weilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-11-01

    MAX phases, such as titanium silicon carbide (Ti3SiC2), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti3SiC2 has been suggested in the literature as a possible fuel cladding material. Prior to the application, it is necessary to investigate diffusivities of fission products in the ternary compound at elevated temperatures. This study attempts to obtain relevant data and make an initial assessment for Ti3SiC2. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti3SiC2, SiC, and a dual-phase nanocomposite of Ti3SiC2/SiC synthesized at PNNL. Thermal annealing and in-situ Rutherford backscattering spectrometry (RBS) were employed to study the diffusivity of the various implanted species in the materials. In-situ RBS study of Ti3SiC2 implanted with Au ions at various temperatures was also performed. The experimental results indicate that the implanted Ag in SiC is immobile up to the highest temperature (1273 K) applied in this study; in contrast, significant out-diffusion of both Ag and Au in MAX phase Ti3SiC2 occurs during ion implantation at 873 K. Cs in Ti3SiC2 is found to diffuse during post-irradiation annealing at 973 K, and noticeable Cs release from the sample is observed. This study may suggest caution in using Ti3SiC2 as a fuel cladding material for advanced nuclear reactors operating at very high temperatures. Further studies of the related materials are recommended.

  2. Birds as biodiversity surrogates

    DEFF Research Database (Denmark)

    Larsen, Frank Wugt; Bladt, Jesper Stentoft; Balmford, Andrew

    2012-01-01

    1. Most biodiversity is still unknown, and therefore, priority areas for conservation typically are identified based on the presence of surrogates, or indicator groups. Birds are commonly used as surrogates of biodiversity owing to the wide availability of relevant data and their broad popular...... and applications.?Good surrogates of biodiversity are necessary to help identify conservation areas that will be effective in preventing species extinctions. Birds perform fairly well as surrogates in cases where birds are relatively speciose, but overall effectiveness will be improved by adding additional data...... from other taxa, in particular from range-restricted species. Conservation solutions with focus on birds as biodiversity surrogate could therefore benefit from also incorporating species data from other taxa....

  3. Development of a FE Model for the Stress Analysis of HTGR TRISO-coated particle fuel

    International Nuclear Information System (INIS)

    Cho, Moon Sung; Lee, Y. W.; Jeong, K. C.; Kim, Y. K.; Oh, S. C.; Chang, J. H.

    2005-12-01

    Finite element modelling of the stresses in TRISO-coated fuel particle under normal operating conditions was carried out with use of the structural analysis computer code ABAQUS. The FE model took into account the irradiation induced swelling and the creep of the PyC layers, the internal fission gas pressure that builds up during irradiation and the constant external ambient pressure. All of the inputs such as particle dimensions, swelling rates and creep rates of PyC layers and other mechanical properties used in these calculations were adopted from Miller's publication published in 1993. The FE model was verified against Miller's solution. Results of this model were found to be in good agreement with Miller's results. With use of the FE model, the static behavior of the TRISO-coated fuel particle, such as load shares, stress contours, stress variations as a function of fluence and shape changes of the TRISO -coated layers were investigated

  4. Diffusivities of Ag, Cs, Sr, and Kr in TRISO fuel particles and graphite

    Energy Technology Data Exchange (ETDEWEB)

    Collin, Blaise Paul [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    Tri-structural isotropic (TRISO) coated particles have been developed and studied since the late 1950s when the concept of coated particles was invented by Roy Huddle of the United Kingdom Atomic Energy Authority. Several decades of work by half a dozen countries on fission product transport in TRISO fuel through numerous irradiation and heating experiments have led to several recommendations of transport data and to the adoption of various sets of diffusion coefficients. In 1997, the International Atomic Energy Agency (IAEA) gathered all these historical results and issued a technical document (TECDOC-978 [IAEA]) that summarizes these sets of recommended diffusion coefficients. Table 1 shows the reference literature articles for the diffusivities that have historically been recommended by the American and German TRISO fuel development programs and that are summarized in the IAEA report (see section 7 for full references of these articles).

  5. Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: What is new?

    Energy Technology Data Exchange (ETDEWEB)

    Isabella Van Rooyen

    2014-10-01

    The TRISO particle for HTRs has been developed to an advanced state where the coating withstands internal gas pressures and retains fission products during irradiation and under postulated accidents. However, one exception is Ag that has been found to be released from high quality TRISO coated particles when irradiated and can also during high temperature accident heating tests. Although out- of- pile laboratory tests have never hither to been able to demonstrate a diffusion process of Ag in SiC, effective diffusion coefficients have been derived to successfully reproduce measured Ag-110m releases from irradiated HTR fuel elements, compacts and TRISO particles It was found that silver transport through SiC does not proceed via bulk volume diffusion. Presently grain boundary diffusion that may be irradiation enhanced either by neutron bombardment or by the presence of fission products such as Pd, are being investigated. Recent studies of irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), transmission kukuchi diffraction (TKD) patterns and high resolution transmission electron microscopy (HRTEM) have been used to further the understanding of Ag transport through TRISO particles. No silver was observed in SiC grains, but Ag was identified at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in some of the very same triple junctions, but this could be related to silver behavior as Ag-110m decays to Cd-110. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries and in most SiC grain boundaries and the potential role of Pd in the transport of Ag will be discussed.

  6. 3D thermal modeling of TRISO fuel coupled with neutronic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jianwei [Los Alamos National Laboratory; Uddin, Rizwan [UNIV OF ILLINIOS

    2010-01-01

    The Very High Temperature Gas Reactor (VHTR) is widely considered as one of the top candidates identified in the Next Generation Nuclear Power-plant (NGNP) Technology Roadmap under the U.S . Depanment of Energy's Generation IV program. TRlSO particle is a common element among different VHTR designs and its performance is critical to the safety and reliability of the whole reactor. A TRISO particle experiences complex thermo-mechanical changes during reactor operation in high temperature and high burnup conditions. TRISO fuel performance analysis requires evaluation of these changes on micro scale. Since most of these changes are temperature dependent, 3D thermal modeling of TRISO fuel is a crucial step of the whole analysis package. In this paper, a 3D numerical thermal model was developed to calculate temperature distribution inside TRISO and pebble under different scenarios. 3D simulation is required because pebbles or TRISOs are always subjected to asymmetric thermal conditions since they are randomly packed together. The numerical model was developed using finite difference method and it was benchmarked against ID analytical results and also results reported from literature. Monte-Carlo models were set up to calculate radial power density profile. Complex convective boundary condition was applied on the pebble outer surface. Three reactors were simulated using this model to calculate temperature distribution under different power levels. Two asymmetric boundary conditions were applied to the pebble to test the 3D capabilities. A gas bubble was hypothesized inside the TRISO kernel and 3D simulation was also carried out under this scenario. Intuition-coherent results were obtained and reported in this paper.

  7. Progress on Fabrication of Planar Diffusion Couples with Representative TRISO PyC/SiC Microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Hunn, John D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jolly, Brian C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gerczak, Tyler J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Campbell, Anne A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schumacher, Austin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-10-01

    Release of fission products from tristructural-isotropic (TRISO) coated particle fuel limits the fuel’s operational lifetime and creates potential safety and maintenance concerns. A need for diffusion analysis in representative TRISO layers exists to provide fuel performance models with high fidelity data to improve fuel performance and efficiency. An effort has been initiated to better understand fission product transport in, and release from, quality TRISO fuel by investigating diffusion couples with representative pyrocarbon (PyC) and silicon carbide (SiC). Here planar PyC/SiC diffusion couples are being developed with representative PyC/SiC layers using a fluidized bed chemical vapor deposition (FBCVD) system identical to those used to produce laboratory-scale TRISO fuel for the Advanced Gas Reactor Fuel Qualification and Development Program’s (AGR) first fuel irradiation. The diffusivity of silver, the silver and palladium system, europium, and strontium in the PyC/SiC will be studied at elevated temperatures and under high temperature neutron irradiation. The study also includes a comparative study of PyC/SiC diffusion couples with varying TRISO layer properties to understand the influence of SiC microstructure (grain size) and the PyC/SiC interface on fission product transport. The first step in accomplishing these goals is the development of the planar diffusion couples. The diffusion couple construction consists of multiple steps which includes fabrication of the primary PyC/SiC structures with targeted layer properties, introduction of fission product species and seal coating to create an isolated system. Coating development has shown planar PyC/SiC diffusion couples with similar properties to AGR TRISO fuel can be produced. A summary of the coating development process, characterization methods, and status are presented.

  8. Evaluation of Fracture Stress for the SiC Layer of TRISO-Coated Fuel Particles by A Modified Crush Testing

    International Nuclear Information System (INIS)

    Byun, Thak Sang; Kim, Jin Weon; Miller, James Henry; Snead, Lance Lewis; Hunn, John D.

    2010-01-01

    Fracture stress data for the chemical vapor deposition (CVD) SiC coatings of tri-isotropic (TRISO) carbon/silicon carbide coated fuel particles were obtained using a newly developed testing and evaluation method, and their relationship with microstructure investigated. A crush testing technique using a blanket foil at load-transferring contact has been developed for hemispherical shell SiC specimens based on finite element (FE) analysis results. Mean fracture stress varied with test material in the range of 330-650 MPa, and was connected to the combined characteristics of inner surface roughness and porosity.

  9. Surrogate waveform models

    Science.gov (United States)

    Blackman, Jonathan; Field, Scott; Galley, Chad; Scheel, Mark; Szilagyi, Bela; Tiglio, Manuel

    2015-04-01

    With the advanced detector era just around the corner, there is a strong need for fast and accurate models of gravitational waveforms from compact binary coalescence. Fast surrogate models can be built out of an accurate but slow waveform model with minimal to no loss in accuracy, but may require a large number of evaluations of the underlying model. This may be prohibitively expensive if the underlying is extremely slow, for example if we wish to build a surrogate for numerical relativity. We examine alternate choices to building surrogate models which allow for a more sparse set of input waveforms. Research supported in part by NSERC.

  10. STATUS OF TRISO FUEL IRRADIATIONS IN THE ADVANCED TEST REACTOR SUPPORTING HIGH-TEMPERATURE GAS-COOLED REACTOR DESIGNS

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, Michael; Petti, D. A.; Palmer, Joe

    2016-11-01

    The United States Department of Energy’s Advanced Reactor Technologies (ART) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program is irradiating up to seven low enriched uranium (LEU) tri-isotopic (TRISO) particle fuel (in compact form) experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). These irradiations and fuel development are being accomplished to support development of the next generation reactors in the United States. The experiments will be irradiated over the next several years to demonstrate and qualify new TRISO coated particle fuel for use in high temperature gas reactors. The goals of the experiments are to provide irradiation performance data to support fuel process development, to qualify fuel for normal operating conditions, to support development and validation of fuel performance and fission product transport models and codes, and to provide irradiated fuel and materials for post irradiation examination (PIE) and safety testing. The experiments, which will each consist of several independent capsules, will be irradiated in an inert sweep gas atmosphere with individual on-line temperature monitoring and control of each capsule. The sweep gas will also have on-line fission product monitoring on its effluent to track performance of the fuel in each individual capsule during irradiation. The first experiment (designated AGR-1) started irradiation in December 2006 and was completed in November 2009. The second experiment (AGR-2) started irradiation in June 2010 and completed in October 2013. The third and fourth experiments have been combined into a single experiment designated (AGR-3/4), which started its irradiation in December 2011 and completed in April 2014. Since the purpose of this experiment was to provide data on fission product migration and retention in the NGNP reactor, the design of this experiment was significantly different from the first two experiments, though the control

  11. Relative Release-to-Birth Indicators for Investigating TRISO Fuel Fission Gas Release Models

    International Nuclear Information System (INIS)

    Harp, Jason M.; Hawari, Ayman I.

    2008-01-01

    TRISO microsphere fuel is the fundamental fuel unit for Very High Temperature Reactors (VHTR). A single TRISO particle consists of an inner kernel of uranium dioxide or uranium oxycarbide surrounded by layers of pyrolytic carbon and silicon carbide. If the silicon carbide layer fails, fission products, especially the noble fission gases Kr and Xe, will begin to escape the failed particle. The release of fission gas is usually quantified by measuring the ratio of the released activity (R) to the original birth activity (B), which is designated as the R/B ratio. In this work, relative Release-to-Birth indicators (I) are proposed as a technique for interpreting the results of TRISO irradiation experiments. By implementing a relative metric, it is possible to reduce the sensitivity of the indicators to instrumental uncertainties and variations in experimental conditions. As an example, relative R/B indicators are applied to the interpretation of representative data from the Advanced Gas Reactor-1 TRISO fuel experiment that is currently taking place at the Advanced Test Reactor of Idaho National Laboratory. It is shown that the comparison of measured to predicted relative R/B indicators (I) gives insight into the physics of release and helps validate release models. Different trends displayed by the indicators are related to the mechanisms of fission gas release such as diffusion and recoil. The current analysis shows evidence for separate diffusion coefficients for Kr and Xe and supports the need to account for recoil release. (authors)

  12. Prediction of TRISO coated particle performances for a one-pass deep burn

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439 (United States)], E-mail: alby@anl.gov

    2008-02-15

    In the present studies, TRISO coated particle performances have been investigated for incinerating plutonium and minor actinides by the Gas Turbine-Modular Helium Reactor, whose fresh fuel is fabricated after the uranium extraction (UREX) process applied to Light Water Reactors irradiated fuel. The analyses divide into two parts: in the first part, the latest design of the reactor core proposed by General Atomics, which takes advantage of four fuel rings, has been modeled in deep details by the Monte Carlo MCNP code and a burnup process has been simulated by the MCB code. In the second part, the TRISO coated particle performances have been investigated by the PANAMA code with the goal of verifying the design constraints proposed by General Atomics. During burnup, the refueling and shuffling schedule followed the one-pass deep burn concept, where the fuel is utilized, since fabrication for the Gas Turbine-Modular Helium Reactor, without any reprocessing until the final disposal into the geological repository. During the reactor operation, the fast fluence on all TRISO particles layers has been evaluated and the production of the key fission products monitored. During an hypothetical reactor accident scenario, the TRISO particle failure fraction has been estimated.

  13. Prediction of TRISO coated particle performances for a one-pass deep burn

    International Nuclear Information System (INIS)

    Talamo, Alberto

    2008-01-01

    In the present studies, TRISO coated particle performances have been investigated for incinerating plutonium and minor actinides by the Gas Turbine-Modular Helium Reactor, whose fresh fuel is fabricated after the uranium extraction (UREX) process applied to Light Water Reactors irradiated fuel. The analyses divide into two parts: in the first part, the latest design of the reactor core proposed by General Atomics, which takes advantage of four fuel rings, has been modeled in deep details by the Monte Carlo MCNP code and a burnup process has been simulated by the MCB code. In the second part, the TRISO coated particle performances have been investigated by the PANAMA code with the goal of verifying the design constraints proposed by General Atomics. During burnup, the refueling and shuffling schedule followed the one-pass deep burn concept, where the fuel is utilized, since fabrication for the Gas Turbine-Modular Helium Reactor, without any reprocessing until the final disposal into the geological repository. During the reactor operation, the fast fluence on all TRISO particles layers has been evaluated and the production of the key fission products monitored. During an hypothetical reactor accident scenario, the TRISO particle failure fraction has been estimated

  14. Quantification of TRISO fuel heterogeneity effects in HTGR lattice physics calculations

    International Nuclear Information System (INIS)

    Perfetti, C. M.; Anghaie, S.; Dugan, E.; Marcille, T.

    2010-01-01

    A large number of LEU-MHR fuel compact models were generated with randomly distributed TRISO particle fuel and were simulated using MCNP5, and it was determined how several neutronic parameters, including k-infinite, the thermal and fast diffusion coefficients, and the four factors, varied across the randomly-generated cases. A sensitivity study was also performed to determine how the four factors depend on the definition of the thermal energy group. Values of k-infinite for the cases had a sample standard deviation of 248 pcm and were found to follow an approximately normal distribution about the mean value of k-infinite. Although all of the four factors were found to have similar sample standard deviations, the resonance escape probability was found to be the most variable parameter with a sample relative standard deviation between 0.07% and 0.08%. HTGR fuel compact homogenization methods typically examine only one reference fuel compact that contains a uniform distribution of TRISO particles, but in reality the TRISO particles are randomly distributed throughout the fuel compact. Thus, the neutronic parameters for actual fuel compacts differ randomly from those in the reference model. To license next-generation High-Temperature Gas Reactors engineers must quantify all uncertainties of the design and this random variation in neutron parameters is a previously unmeasured quantity; this study measures this uncertainty by examining the variation in k-infinite for HTGR fuel compact models with randomly distributed TRISO fuel. (authors)

  15. Analytical Dancoff factor evaluations for reactor designs loaded with TRISO particle fuel

    International Nuclear Information System (INIS)

    Ji, Wei; Liang, Chao; Pusateri, Elise N.

    2014-01-01

    Highlights: • The Dancoff factors for randomly distributed TRISO fuel particles are evaluated. • A new “dual-sphere” model is proposed to predict Dancoff factors. • The new model accurately accounts for the coating regions of fuel particles. • High accuracy is achieved over a broad range of design parameters. • The new model can be used to analyze reactors with double heterogeneity. - Abstract: A new mathematical model, the dual-sphere model, is proposed to analytically evaluate Dancoff factors of TRISO fuel kernels based on the chord method. The accurate evaluation of fuel kernel Dancoff factors is needed when one analyzes nuclear reactors loaded with TRISO particle fuel. In these reactor designs, fuel kernels are randomly distributed and shield each other, causing a shadowing effect. The Dancoff factor is a quantitative measure of this effect and is determined by the spatial distribution of fuel kernels. A TRISO fuel particle usually consists of four layers that form a coating region outside the fuel kernel. When fuel particles are loaded in the reactor, the spatial distribution of fuel kernels can be affected by the thickness of the coating region. Therefore, the coating region should be taken into account in the calculation of Dancoff factors. However, the previous model, the single-sphere model, assumes no coating regions in the Dancoff factor predictions. To address this model deficiency, the dual-sphere model is proposed by deriving a new chord length distribution function between two fuel kernels that explicitly accounts for coating regions. The new model is employed to derive analytical solutions of infinite medium, intra-fuel pebble and intra-fuel compact/pin Dancoff factors over a wide range of volume packing fractions of TRISO fuel particles, varying from 2% to 60%. Comparisons are made with the predictions from the single-sphere model and reference Monte Carlo simulations. A significant improvement of the accuracy, over the ranges of

  16. Science and technology of kernels and TRISO coated particle sorting

    International Nuclear Information System (INIS)

    Nothnagel, G.

    2006-09-01

    The ~1mm diameter TRISO coated particles, which form the elemental units of PBMR nuclear fuel, has to be close to spherical in order to best survive damage during sphere pressing. Spherical silicon carbide layers further provide the strongest miniature pressure vessels for fission product retention. To make sure that the final product contains particles of acceptable shape, 100% of kernels and coated particles have to be sorted on a surface-ground sorting table. Broken particles, twins, irregular (odd) shapes and extreme ellipsoids have to be separated from the final kernel and coated particle batches. Proper sorting of particles is an extremely important step in quality fuel production as the final failure fraction depends sensitively on the quality of sorting. After sorting a statistically significant sample of the sorted product is analysed for sphericity, which is defined as the ratio of maximum to minimum diameter, as part of a standard QC test to ensure conformance to German specifications. In addition a burn-leach test is done on coated particles (before pressing) and fuel spheres (after pressing) to ensure adherence to failure specifications. Because of the extreme importance of particle sorting for assurance of fuel quality it is essential to have an in-depth understanding of the capabilities and limitations of particle sorting. In this report a systematic scientific rationale is developed, from fundamental principles, to provide a basis for understanding the relationship between product quality and sorting parameters. The principles and concepts, developed in this report, will be of importance when future sorting tables (or equivalents) are to be designed. A number of new concepts and methodologies are developed to assist with equivalence validation of any two sorting tables. This is aimed in particular towards quantitative assessment of equivalence between current QC tables (closely based on the original NUKEM parameters, except for the driving mechanism

  17. Stress Analysis of a TRISO Coated Particle Fuel by Using ABAQUS Finite Element Visco-Elastoplastic Solutions

    International Nuclear Information System (INIS)

    Cho, Moon Sung; Kim, Y. M.; Lee, Y. W.

    2006-01-01

    The fundamental design for a gas-cooled reactor relies on an understanding of the behavior of a coated particle fuel. KAERI, which has been carrying out the Korean VHTR (Very High Temperature modular gas cooled Reactor) Project since 2004, is developing a fuel performance analysis code for a VHTR named COPA (COated Particle fuel Analysis). A validation of COPA was attempted by comparing its benchmark results with the visco-elastic solutions obtained from the ABAQUS code calculations for the IAEA-CRP-6 TRISO coated particle benchmark problems involving a creep, swelling, and pressure. However, the ABAQUS finite element model used for the above-mentioned analysis did not consider the material nonlinearity of the SiC coating layer that showed stress levels higher than the assumed yield point of the material. In this study, a consideration of the material nonlinearity is included in the ABAQUS model to obtain the visco-elastoplastic solutions and the results are compared with the visco-elastic solutions obtained from the previous ABAQUS model

  18. Silver diffusion through silicon carbide in microencapsulated nuclear fuels TRISO; Difusion de plata a traves de carburo de silicio en combustibles nucleares microencapsulados TRISO

    Energy Technology Data Exchange (ETDEWEB)

    Cancino T, F.; Lopez H, E., E-mail: Felix.cancino@cinvestav.edu.mx [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Av. Industria Metalurgica No. 1062, Col. Ramos Arizpe, 25900 Saltillo, Coahuila (Mexico)

    2013-10-15

    The silver diffusion through silicon carbide is a challenge that has persisted in the development of microencapsulated fuels TRISO (Tri structural Isotropic) for more than four decades. The silver is known as a strong emitter of gamma radiation, for what is able to diffuse through the ceramic coatings of pyrolytic coal and silicon carbide and to be deposited in the heat exchangers. In this work we carry out a recount about the art state in the topic of the diffusion of Ag through silicon carbide in microencapsulated fuels and we propose the role that the complexities in the grain limit can have this problem. (Author)

  19. Videotrees: Improving video surrogate presentation using hierarchy

    NARCIS (Netherlands)

    Jansen, Michel; Heeren, W.F.L.; van Dijk, Elisabeth M.A.G.

    As the amount of available video content increases, so does the need for better ways of browsing all this material. Because the nature of video makes it hard to process, the need arises for adequate surrogates for video that can readily be skimmed and browsed. In this paper, the effects of the use

  20. Fission product monitoring of TRISO coated fuel for the advanced gas reactor-1 experiment

    International Nuclear Information System (INIS)

    Scates, Dawn M.; Hartwell, John K.; Walter, John B.; Drigert, Mark W.; Harp, Jason M.

    2010-01-01

    The US Department of Energy has embarked on a series of tests of TRISO coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burnup of 9% FIMA with no known TRISO fuel particle failures in March 2008. The burnup goal for the majority of the fuel compacts is to have a compact averaged burnup greater than 18% FIMA and a minimum compact averaged burnup of 14% FIMA. At the INL the TRISO fuel in the AGR-1 experiment is closely monitored while it is being irradiated in the ATR. The effluent monitoring system used for the AGR-1 fuel is the Fission Product Monitoring System (FPMS). The FPMS is a valuable tool that provides near real-time data indicative of the AGR-1 test fuel performance and incorporates both high-purity germanium (HPGe) gamma-ray spectrometers and sodium iodide [NaI(Tl)] scintillation detector-based gross radiation monitors. To quantify the fuel performance, release-to-birth ratios (R/B's) of radioactive fission gases are computed. The gamma-ray spectra acquired by the AGR-1 FPMS are analyzed and used to determine the released activities of specific fission gases, while a dedicated detector provides near-real time count rate information. Isotopic build up and depletion calculations provide the associated isotopic birth rates. This paper highlights the features of the FPMS, encompassing the equipment, methods and measures that enable the calculation of the release-to-birth ratios. Some preliminary results from the AGR-1 experiment are also presented.

  1. Stress Calculation of a TRISO Coated Particle Fuel by Using a Poisson's Ratio in Creep Condition

    International Nuclear Information System (INIS)

    Cho, Moon-Sung; Kim, Y. M.; Lee, Y. W.; Jeong, K. C.; Kim, Y. K.; Oh, S. C.; Kim, W. K.

    2007-01-01

    KAERI, which has been carrying out the Korean VHTR (Very High Temperature modular gas cooled Reactor) project since 2004, has been developing a performance analysis code for the TRISO coated particle fuel named COPA (COated Particle fuel Analysis). COPA predicts temperatures, stresses, a fission gas release and failure probabilities of a coated particle fuel in normal operating conditions. KAERI, on the other hand, is developing an ABAQUS based finite element(FE) model to cover the non-linear behaviors of a coated particle fuel such as cracking or debonding of the TRISO coating layers. Using the ABAQUS based FE model, verification calculations were carried out for the IAEA CRP-6 benchmark problems involving creep, swelling, and pressure. However, in this model the Poisson's ratio for elastic solution was used for creep strain calculation. In this study, an improvement is made for the ABAQUS based finite element model by using the Poisson's ratio in creep condition for the calculation of the creep strain rate. As a direct input of the coefficient in a creep condition is impossible, a user subroutine for the ABAQUS solution is prepared in FORTRAN for use in the calculations of the creep strain of the coating layers in the radial and hoop directions of the spherical fuel. This paper shows the calculation results of a TRISO coated particle fuel subject to an irradiation condition assumed as in the Miller's publication in comparison with the results obtained from the old FE model used in the CRP-6 benchmark calculations

  2. Developments in Surrogating Methods

    Directory of Open Access Journals (Sweden)

    Hans van Dormolen

    2005-11-01

    Full Text Available In this paper, I would like to talk about the developments in surrogating methods for preservation. My main focus will be on the technical aspects of preservation surrogates. This means that I will tell you something about my job as Quality Manager Microfilming for the Netherlands’ national preservation program, Metamorfoze, which is coordinated by the National Library. I am responsible for the quality of the preservation microfilms, which are produced for Metamorfoze. Firstly, I will elaborate on developments in preservation methods in relation to the following subjects: · Preservation microfilms · Scanning of preservation microfilms · Preservation scanning · Computer Output Microfilm. In the closing paragraphs of this paper, I would like to tell you something about the methylene blue test. This is an important test for long-term storage of preservation microfilms. Also, I will give you a brief report on the Cellulose Acetate Microfilm Conference that was held in the British Library in London, May 2005.

  3. An improved design of TRISO particle with porous SiC inner layer by fluidized bed-chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rongzheng; Liu, Malin, E-mail: liumalin@tsinghua.edu.cn; Chang, Jiaxing; Shao, Youlin; Liu, Bing

    2015-12-15

    Tristructural-isotropic (TRISO) particle has been successful in high temperature gas cooled reactor (HTGR), but an improved design is required for future development. In this paper, the coating layers are reconsidered, and an improved design of TRISO particle with porous SiC inner layer is proposed. Three methods of preparing the porous SiC layer, called high methyltrichlorosilane (MTS) concentration method, high Ar concentration method and hexamethyldisilane (HMDS) method, are experimentally studied. It is indicated that porous SiC layer can be successfully prepared and the density of SiC layer can be adjusted by tuning the preparation parameters. Microstructure and characterization of the improved TRISO coated particle are given based on scanning electron microscope (SEM), X-ray diffraction (XRD), Raman scattering and energy dispersive X-ray (EDX) analysis. It can be found that the improved TRISO coated particle with porous SiC layer can be mass produced successfully. The formation mechanisms of porous SiC layer are also discussed based on the fluidized bed-chemical vapor deposition principle. - Graphical abstract: An improved design of TRISO particle with porous SiC inner layer to replace the inner porous pyrolytic carbon layer was proposed and prepared by FB-CVD method. This new design is aimed to reduce the total internal pressure of the particles by reducing the formation of CO and to reduce the risks of amoeba effect. - Highlights: • An improved design of TRISO particle with porous SiC inner layer was proposed. • Three methods of preparing porous SiC layer are proposed and experimentally studied. • The density of porous SiC layer can be controlled by adjusting experimental parameters. • Formation mechanisms of porous SiC layer were given based on the FB-CVD principle. • TRISO particles with porous SiC inner layer were mass produced successfully.

  4. Effect of Coating Parameters of the Buffer Layer on the Shape Ratio of TRISO-Coated Particles

    International Nuclear Information System (INIS)

    KIm, Weon Ju; Park, Jong Hoon; Park, Ji Yeon; Lee, Young Woo; Chang, Jong Hwa

    2005-01-01

    Fuel for high temperature gas-cooled reactors (HTGR's) consists of TRISO-coated particles. Fluidized bed chemical vapor deposition (FBCVD) has been applied to fabricate the TRISO-coated fuel particles. The TRISO particles consist of UO 2 microspheres coated with layers of porous pyrolytic carbon (PyC), inner dense PyC (IPyC), SiC, and outer dense PyC (OPyC). The porous PyC coating layer, called the buffer layer, attenuates fission recoils and provides void volume for gaseous fission products and carbon monoxide. The buffer layer, which has the highest coating rate among the coating layers, shows the largest variation of the coating thickness within a particle and a batch. This could be the most plausible source of an asphericity in the TRISO particles. The aspherical particles are expected to have an inferior fuel performance. Miller et al. have predicted that a larger stress is developed within the coating layers and thus the failure probability increases in the particles with high aspect ratios. Therefore, the shape of the TRISO-coated particles should be controlled properly and has been one of the important inspection items for the quality control of the fabrication process. In this paper, we investigated the effect of coating parameters of the buffer layer on the shape of the TRISO particles. The flow rate of coating gas and the coating temperature were varied to control the buffer layer. The asphericity of the TRISO-coated particles was evaluated for the various coating conditions of the buffer layer, but at constant coating parameters for the IPyC/SiC/OPyC layers

  5. A Statistical Analysis on the Coating Layer Thicknesses of a TRISO of 350 MWth Block-type HTR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Min; Jo, C. K.; Cho, M. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    A tri-isotropic coated fuel particle (TRISO) is a basic fuel element of a high temperature reactor (HTR). The block-type HTR fuel is a cylindrical graphite compact in which a large number of TRISOs are embedded. There are more than 11 billion TRISOs in a 350 MW{sub th} block-type HTR core. Among the RSM quadratic models, the BBD model produces the smallest errors at both interior and exterior points. The errors in the quadratic model of the small-type CCD is the biggest, particularly at exterior points. The CCD has a disadvantage of generating a number of decimal places in its factor levels because of its axial points. It is recommended to use the BBD or the full-type CCD with an adjusted axial point which does not produce the decimal places in its factor levels. More general statistical model for a TRISO design will be secured when the number of factors and responses increases. This study treats a statistical analysis on the optimal layer thicknesses of a UCO TRISO of 350 MW{sub th} block-type HTR which cause a minimum tangential stress to act on the SiC layer. Three response surface methods (RSMs) are used as statistical methods and their resulting quadratic models are compared.

  6. A Statistical Analysis on the Coating Layer Thicknesses of a TRISO of 350 MWth Block-type HTR

    International Nuclear Information System (INIS)

    Kim, Young Min; Jo, C. K.; Cho, M. S.

    2016-01-01

    A tri-isotropic coated fuel particle (TRISO) is a basic fuel element of a high temperature reactor (HTR). The block-type HTR fuel is a cylindrical graphite compact in which a large number of TRISOs are embedded. There are more than 11 billion TRISOs in a 350 MW_t_h block-type HTR core. Among the RSM quadratic models, the BBD model produces the smallest errors at both interior and exterior points. The errors in the quadratic model of the small-type CCD is the biggest, particularly at exterior points. The CCD has a disadvantage of generating a number of decimal places in its factor levels because of its axial points. It is recommended to use the BBD or the full-type CCD with an adjusted axial point which does not produce the decimal places in its factor levels. More general statistical model for a TRISO design will be secured when the number of factors and responses increases. This study treats a statistical analysis on the optimal layer thicknesses of a UCO TRISO of 350 MW_t_h block-type HTR which cause a minimum tangential stress to act on the SiC layer. Three response surface methods (RSMs) are used as statistical methods and their resulting quadratic models are compared

  7. 3D Nondestructive Visualization and Evaluation of TRISO Particles Distribution in HTGR Fuel Pebbles Using Cone-Beam Computed Tomography

    Directory of Open Access Journals (Sweden)

    Gongyi Yu

    2017-01-01

    Full Text Available A nonuniform distribution of tristructural isotropic (TRISO particles within a high-temperature gas-cooled reactor (HTGR pebble may lead to excessive thermal gradients and nonuniform thermal expansion during operation. If the particles are closely clustered, local hotspots may form, leading to excessive stresses on particle layers and an increased probability of particle failure. Although X-ray digital radiography (DR is currently used to evaluate the TRISO distributions in pebbles, X-ray DR projection images are two-dimensional in nature, which would potentially miss some details for 3D evaluation. This paper proposes a method of 3D visualization and evaluation of the TRISO distribution in HTGR pebbles using cone-beam computed tomography (CBCT: first, a pebble is scanned on our high-resolution CBCT, and 2D cross-sectional images are reconstructed; secondly, all cross-sectional images are restructured to form the 3D model of the pebble; then, volume rendering is applied to segment and display the TRISO particles in 3D for visualization and distribution evaluation. For method validation, several pebbles were scanned and the 3D distributions of the TRISO particles within the pebbles were produced. Experiment results show that the proposed method provides more 3D than DR, which will facilitate pebble fabrication research and production quality control.

  8. Meet the surrogate fish

    International Nuclear Information System (INIS)

    Johnson, Bob; Neitzel, Duane; Moxon, Suzanne

    1999-01-01

    This article gives details of the US Department of Energy's innovative research into the development of a sensor system that will work as a surrogate fish to provide information to aid the design of fish-friendly turbines for hydroelectric power plants. The selection of the dams for the testing of sensor fish, the release and recovery of the sensor fish, the recording of the physical forces exerted on fish as they pass through the turbines, and use of the information gathered to build more sensor fish are discussed. Fish investigations conducted at the Pacific Northwest National Laboratory are briefly described. (UK)

  9. Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: “What is new?”

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Petti, D.A.; Nabielek, H.; Neethling, J.H; Kania, M.J.

    2014-01-01

    The tristructural isotropic (TRISO) particle for a high temperature reactor (HTR) has been developed to an advanced state where the coating withstands internal gas pressures and retains nearly all fission products during irradiation and under postulated accidents. However, one exception is silver (Ag) that has been found to be released from high quality TRISO coated particles during irradiation and high temperature accident heating tests. Although out-of-pile laboratory tests have yet to elucidate the mechanism of transport of Ag through silicon carbide (SiC), effective diffusion coefficients have been derived to successfully reproduce measured "1"1"0"mAg- releases from irradiated HTR fuel elements, compacts and TRISO particles. It was found that Ag transport through SiC does not proceed via bulk volume diffusion. Presently grain boundary diffusion that may be irradiation enhanced either by neutron bombardment or by the presence of fission products such as palladium (Pd), are the two hypotheses that have been proposed. Recent studies of irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), transmission Kikuchi diffraction (TKD) patterns, and high resolution transmission electron microscopy (HRTEM) have been used to further the understanding of Ag transport through TRISO particles. No Ag was observed in SiC grains, but Ag was identified at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium (Cd) was also found in some of the very same triple junctions, but this could be related to silver behavior as "1"1"0"mAg decays to "1"1"0Cd or true Cd release as a fission product. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries. The potential role of Pd in the transport of Ag will be discussed further. (author)

  10. Development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel

    International Nuclear Information System (INIS)

    Garcia, Lorena P. Rodríguez; Pérez, Daniel Milian; Hernández, Carlos Rafael García; Lorenzo, Daniel E. Milian; Lira, Carlos A. Brayner de Oliveira; Universidad Federal de Pernambuco

    2017-01-01

    The use of the Generation IV Very High Temperature Reactors (VHTR) presents significant perspectives to assume the future nuclear energy and hydrogen production. VHTR has advantages because its low electricity generation costs, short construction periods, high hydrogen production efficiency, safety and reliability, proliferation resistance and inherent safety features of the fuel and reactor. However, it faces substantial challenges to be successfully deployed as a sustainable energy source. One of these key challenges is the nuclear safety which mainly relies on the quality and integrity of the coated fuel particles (TRISO) planned to be used in these reactors taking into consideration the high temperatures (1000°C in normal operation and up to 1800°C in accidents conditions) and burnup degrees (150 - 200 GWd/tonU) achievable in these reactors. In this paper is presented the current state of development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel in function of the variation of different parameters in the VHTR. In order to achieve this goal will be used coupled computational modeling using analytical methods and Monte Carlo and CFD codes such as MCNPX version 2.6e and Ansys version 14. The studies performed in this investigation included the evaluation of key parameters in the TRISO such as the release of fission gases and CO, gas pressure, temperature distributions, kernel migration, maximum stress values, and failure probabilities. The results achieved in this investigation contributes to demonstrating the viability of the proposed methodology for the study, the design and safety calculations of VHTR. (author)

  11. Evaluation of the Mechanical Performance of Silicon Carbide in TRISO Fuel at High Temperatures

    International Nuclear Information System (INIS)

    Rohbeck, N.; Xiao, P.

    2014-01-01

    The HTR design envisions fuel operating temperatures of up to 1000°C and in case of an accident even 1600°C are conceivable. To ensure safety in all conditions a thorough understanding of the impact of an extreme temperature environment is necessary. This work assesses the high temperature mechanical performance of the silicon carbide (SiC) layer within the tristructural-isotropic (TRISO) fuel particle as it poses the main barrier against fission product release into the primary circuit. Therefore simulated fuel was fabricated by fluidized bed chemical vapour deposition; varying the deposition conditions resulted in strongly differing SiC microstructures for the various samples. Subsequently the TRISO particles were annealed in inert atmosphere at temperatures ranging from 1600°C up to 2200°C. Scanning electron microscopy and Raman spectroscopy showed that strong disintegration of the SiC layer occurred from 2100°C onwards, but initial signs of porosity formation were visible already at 1800°C. Still, the elastic modulus and hardness as measured by nanoindentation were hardly impaired. After annealing stoichiometric SiC coatings showed a reduction in fracture strength as determined by a modified crush test, however the actual annealing temperature from 1600°C to 2000°C had no measureable effect. Furthermore, a technique was developed to measure the elastic modulus and hardness in-situ up to 500°C using a high temperature nanoindentation facility. This approach allows conducting numerous tests on small sample volumes and thus promises to improve our knowledge of irradiation effects on the mechanical properties. For the SiC layer in TRISO particles it was found that the elastic modulus decreased slightly from room temperature up to 500°C, whereas the hardness was reduced more severely to approximately half of its ambient temperature value. (author)

  12. Development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Lorena P. Rodríguez; Pérez, Daniel Milian; Hernández, Carlos Rafael García; Lorenzo, Daniel E. Milian; Lira, Carlos A. Brayner de Oliveira, E-mail: lorenapilar1109@gmail.com, E-mail: milianperez89@gmail.com, E-mail: cgh@instec.cu, E-mail: dmilian@instec.cu, E-mail: cabol@ufpe.br [Higher Institute of Technologies and Applied Sciences (InSTEC), Habana (Cuba); Universidad Federal de Pernambuco (UFPE), Recife (Brazil). Departamento de Energia Nuclear

    2017-11-01

    The use of the Generation IV Very High Temperature Reactors (VHTR) presents significant perspectives to assume the future nuclear energy and hydrogen production. VHTR has advantages because its low electricity generation costs, short construction periods, high hydrogen production efficiency, safety and reliability, proliferation resistance and inherent safety features of the fuel and reactor. However, it faces substantial challenges to be successfully deployed as a sustainable energy source. One of these key challenges is the nuclear safety which mainly relies on the quality and integrity of the coated fuel particles (TRISO) planned to be used in these reactors taking into consideration the high temperatures (1000°C in normal operation and up to 1800°C in accidents conditions) and burnup degrees (150 - 200 GWd/tonU) achievable in these reactors. In this paper is presented the current state of development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel in function of the variation of different parameters in the VHTR. In order to achieve this goal will be used coupled computational modeling using analytical methods and Monte Carlo and CFD codes such as MCNPX version 2.6e and Ansys version 14. The studies performed in this investigation included the evaluation of key parameters in the TRISO such as the release of fission gases and CO, gas pressure, temperature distributions, kernel migration, maximum stress values, and failure probabilities. The results achieved in this investigation contributes to demonstrating the viability of the proposed methodology for the study, the design and safety calculations of VHTR. (author)

  13. Development of a Human Cranial Bone Surrogate for Impact Studies

    International Nuclear Information System (INIS)

    Roberts, Jack C.; Merkle, Andrew C.; Carneal, Catherine M.; Voo, Liming M.; Johannes, Matthew S.; Paulson, Jeff M.; Tankard, Sara; Uy, O. Manny

    2013-01-01

    In order to replicate the fracture behavior of the intact human skull under impact it becomes necessary to develop a material having the mechanical properties of cranial bone. The most important properties to replicate in a surrogate human skull were found to be the fracture toughness and tensile strength of the cranial tables as well as the bending strength of the three-layer (inner table-diplöe-outer table) architecture of the human skull. The materials selected to represent the surrogate cranial tables consisted of two different epoxy resins systems with random milled glass fiber to enhance the strength and stiffness and the materials to represent the surrogate diplöe consisted of three low density foams. Forty-one three-point bending fracture toughness tests were performed on nine material combinations. The materials that best represented the fracture toughness of cranial tables were then selected and formed into tensile samples and tested. These materials were then used with the two surrogate diplöe foam materials to create the three-layer surrogate cranial bone samples for three-point bending tests. Drop tower tests were performed on flat samples created from these materials and the fracture patterns were very similar to the linear fractures in pendulum impacts of intact human skulls, previously reported in the literature. The surrogate cranial tables had the quasi-static fracture toughness and tensile strength of 2.5 MPa√ m and 53 ± 4.9 MPa, respectively, while the same properties of human compact bone were 3.1 ± 1.8 MPa√ m and 68 ± 18 MPa, respectively. The cranial surrogate had a quasi-static bending strength of 68 ± 5.7 MPa, while that of cranial bone was 82 ± 26 MPa. This material/design is currently being used to construct spherical shell samples for drop tower and ballistic tests.

  14. MICRO/NANO-STRUCTURAL EXAMINATION AND FISSION PRODUCT IDENTIFICATION IN NEUTRON IRRADIATED AGR-1 TRISO FUEL

    Energy Technology Data Exchange (ETDEWEB)

    van Rooyen, I. J.; Lillo, T. M.; Wen, H. M.; Hill, C. M.; Holesinger, T. G.; Wu, Y. Q.; Aguiara, J. A.

    2016-11-01

    Advanced microscopic and microanalysis techniques were developed and applied to study irradiation effects and fission product behavior in selected low-enriched uranium oxide/uranium carbide TRISO-coated particles from fuel compacts in six capsules irradiated to burnups of 11.2 to 19.6% FIMA. Although no TRISO coating failures were detected during the irradiation, the fraction of Ag-110m retained in individual particles often varied considerably within a single compact and at the capsule level. At the capsule level Ag-110m release fractions ranged from 1.2 to 38% and within a single compact, silver release from individual particles often spanned a range that extended from 100% retention to nearly 100% release. In this paper, selected irradiated particles from Baseline, Variant 1 and Variant 3 type fueled TRISO coated particles were examined using Scanning Electron Microscopy, Atom Probe Tomography; Electron Energy Loss Spectroscopy; Precession Electron Diffraction, Transmission Electron Microscopy, Scanning Transmission Electron Microscopy (STEM), High Resolution Electron Microscopy (HRTEM) examinations and Electron Probe Micro-Analyzer. Particle selection in this study allowed for comparison of the fission product distribution with Ag retention, fuel type and irradiation level. Nano sized Ag-containing features were predominantly identified in SiC grain boundaries and/or triple points in contrast with only two sitings of Ag inside a SiC grain in two different compacts (Baseline and Variant 3 fueled compacts). STEM and HRTEM analysis showed evidence of Ag and Pd co-existence in some cases and it was found that fission product precipitates can consist of multiple or single phases. STEM analysis also showed differences in precipitate compositions between Baseline and Variant 3 fuels. A higher density of fission product precipitate clusters were identified in the SiC layer in particles from the Variant 3 compact compared with the Variant 1 compact. Trend analysis shows

  15. Study of Some Innovant Reactors without on- Site Refueling with Triso and Cermet Fuel

    OpenAIRE

    A.Chetaine; A. Benchrif; H. Amsil; V. Kuznetsov; Y. Shimazu

    2012-01-01

    The evaluation of unit cell neutronic parameters and lifetime for some innovant reactors without on sit-refuling will be held in this work. the behavior of some small and medium reactors without on site refueling with triso and cermet fuel. For the FBNR long life except we propose to change the enrichment of the Cermet MFE to 9%. For the AFPR reactor we can see that the use of the Cermet MFE can extend the life of this reactor but to maintain the same life period for AFPR...

  16. UN TRISO Compaction in SiC for FCM Fuel Irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Trammell, Michael P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kiggans, James O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jolly, Brian C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Skitt, Darren J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-11-01

    The U.S. Department of Energy Office of Nuclear Energy (DOE-NE) Advanced Fuels Campaign (AFC) is conducting research and development to elevate the technology readiness level of Fully Ceramic Microencapsulated (FCM) fuels, a candidate nuclear fuel with potentially enhanced accident tolerance due to very high fission product retention. One of the early activities in FY17 was to demonstrate production of FCM pellets with uranium nitride TRISO particles. This was carried out in preparation of the larger pellet production campaign in support of the upcoming irradiation testing of this fuel form at INL’s Advanced Test Reactor.

  17. Neutron-induced cross-sections via the surrogate method

    International Nuclear Information System (INIS)

    Boutoux, G.

    2011-11-01

    The surrogate reaction method is an indirect way of determining neutron-induced cross sections through transfer or inelastic scattering reactions. This method presents the advantage that in some cases the target material is stable or less radioactive than the material required for a neutron-induced measurement. The method is based on the hypothesis that the excited nucleus is a compound nucleus whose decay depends essentially on its excitation energy and on the spin and parity state of the populated compound state. Nevertheless, the spin and parity population differences between the compound-nuclei produced in the neutron and transfer-induced reactions may be different. This work reviews the surrogate method and its validity. Neutron-induced fission cross sections obtained with the surrogate method are in general good agreement. However, it is not yet clear to what extent the surrogate method can be applied to infer radiative capture cross sections. We performed an experiment to determine the gamma decay probabilities for 176 Lu and 173 Yb by using the surrogate reactions 174 Yb( 3 He,pγ) 176 Lu * and 174 Yb( 3 He,αγ) 173 Yb * , respectively, and compare them with the well-known corresponding probabilities obtained in the 175 Lu(n,γ) and 172 Yb(n,γ) reactions. This experiment provides answers to understand why, in the case of gamma-decay, the surrogate method gives significant deviations compared to the corresponding neutron-induced reaction. In this work, we have also assessed whether the surrogate method can be applied to extract capture probabilities in the actinide region. Previous experiments on fission have also been reinterpreted. Thus, this work provides new insights into the surrogate method. This work is organised in the following way: in chapter 1, the theoretical aspects related to the surrogate method will be introduced. The validity of the surrogate method will be investigated by means of statistical model calculations. In chapter 2, a review on

  18. Surrogate Modeling for Geometry Optimization

    DEFF Research Database (Denmark)

    Rojas Larrazabal, Marielba de la Caridad; Abraham, Yonas; Holzwarth, Natalie

    2009-01-01

    A new approach for optimizing the nuclear geometry of an atomic system is described. Instead of the original expensive objective function (energy functional), a small number of simpler surrogates is used.......A new approach for optimizing the nuclear geometry of an atomic system is described. Instead of the original expensive objective function (energy functional), a small number of simpler surrogates is used....

  19. Silver (Ag) Transport Mechanisms in TRISO coated particles: A Critical Review

    Energy Technology Data Exchange (ETDEWEB)

    I J van Rooyen; J H Neethling; J A A Engelbrecht; P M van Rooyen; G Strydom

    2012-10-01

    Transport of 110mAg in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coated particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE’s fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.

  20. Ceramography of Irradiated tristructural isotropic (TRISO) Fuel from the AGR-2 Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rice, Francine Joyce [Idaho National Lab. (INL), Idaho Falls, ID (United States); Stempien, John Dennis [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    Ceramography was performed on cross sections from four tristructural isotropic (TRISO) coated particle fuel compacts taken from the AGR-2 experiment, which was irradiated between June 2010 and October 2013 in the Advanced Test Reactor (ATR). The fuel compacts examined in this study contained TRISO-coated particles with either uranium oxide (UO2) kernels or uranium oxide/uranium carbide (UCO) kernels that were irradiated to final burnup values between 9.0 and 11.1% FIMA. These examinations are intended to explore kernel and coating morphology evolution during irradiation. This includes kernel porosity, swelling, and migration, and irradiation-induced coating fracture and separation. Variations in behavior within a specific cross section, which could be related to temperature or burnup gradients within the fuel compact, are also explored. The criteria for categorizing post-irradiation particle morphologies developed for AGR-1 ceramographic exams, was applied to the particles in the AGR-2 compacts particles examined. Results are compared with similar investigations performed as part of the earlier AGR-1 irradiation experiment. This paper presents the results of the AGR-2 examinations and discusses the key implications for fuel irradiation performance.

  1. Silver (Ag) transport mechanisms in TRISO coated particles: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: isabella.vanrooyen@inl.gov [Idaho National Laboratory, Idaho Falls, ID 83415-6188 (United States); Dunzik-Gougar, M.L. [Department of Nuclear Engineering, Idaho State University, ID (United States); Rooyen, P.M. van [Philip M. van Rooyen Network Consultants, Midlands Estates (South Africa)

    2014-05-01

    Transport of {sup 110m}Ag in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coated particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE's fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.

  2. Temperature Dependence of Mechanical Properties of TRISO SiC Coatings

    International Nuclear Information System (INIS)

    Kim, Do Kyung; Park, Kwi Il; Lee, Hyeon Keun; Seong, Young Hoon; Lee, Seung Jun

    2009-04-01

    SiC coating layer has been introduced as protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to excellent mechanical stability at high temperature. It is important to study for high temperature stability in SiC coating layers, because TRISO fuel particles were operating at high temperature around 1000 .deg. C. In this study, the nanoindentation test and micro tensile test were conducted in order to measure the mechanical properties of SiC coating layers at elevated temperature. SiC coating film was fabricated on the carbon substrate using chemical vapor deposition process with different microstructures and thicknesses. Nanoindentation test was performed for the analysis of the hardness, modulus and creep properties up to 500 .deg. C. Impression creep method applied to nanoindentation and creep properties of SiC coating layers were characterized by nanoindentation creep test. The fracture strength of SiC coating layers was measured by the micro tensile method at room temperature and 500 .deg. C. From the results, we can conclude that the hardness and fracture strength are decreased with temperature and no significant change in the modulus is observed with increase in temperature. The deformation mechanism for indentation creep and creep rate changes as the testing temperature increased

  3. Electron probe micro-analysis of irradiated Triso-coated UO2 particles, (1)

    International Nuclear Information System (INIS)

    Ogawa, Toru; Minato, Kazuo; Fukuda, Kosaku; Ikawa, Katsuichi

    1983-11-01

    The Triso-coated low-enriched UO 2 particles were subjected to the post-irradiation electron probe micro-analysis. Observations and analyses on the amoeba effect, inclusions and solutes in the UO 2 matrix were made. In the cooler side of the particle which suffered extensive kernel migration, two significant features were observed: (1) the wake of minute particles, presumably UO 2 , left by the moving kernel in the carbon phase and (2) carbon precipitation in the pores and along the grain boundaries of the UO 2 kernel. Both features could be hardly explained by the gas-phase mechanism of carbon transport and rather suggest the solid state mechanism. Two-types of 4d-transition metal inclusions were observed: the one which was predominantly Mo with a fraction of Tc and another which was enriched with Ru and containing significant amount of Si. The Mo and Si were also found in the UO 2 matrix; the observation led to the discussion of the oxygen potential in the irradiated Triso-coated UO 2 particle. (author)

  4. High temperature oxidation behavior of SiC coating in TRISO coated particles

    International Nuclear Information System (INIS)

    Liu, Rongzheng; Liu, Bing; Zhang, Kaihong; Liu, Malin; Shao, Youlin; Tang, Chunhe

    2014-01-01

    Highlights: • High temperature oxidation tests of SiC coating in TRISO particles were carried out. • The dynamic oxidation process was established. • Oxidation mechanisms were proposed. • The existence of silicon oxycarbides at the SiO 2 /SiC interface was demonstrated. • Carbon was detected at the interface at high temperatures and long oxidation time. - Abstract: High temperature oxidation behavior of SiC coatings in tristructural-isotropic (TRISO) coated particles is crucial to the in-pile safety of fuel particles for a high temperature gas cooled reactor (HTGR). The postulated accident condition of air ingress was taken into account in evaluating the reliability of the SiC layer. Oxidation tests of SiC coatings were carried out in the ranges of temperature between 800 and 1600 °C and time between 1 and 48 h in air atmosphere. Based on the microstructure evolution of the oxide layer, the mechanisms and kinetics of the oxidation process were proposed. The existence of silicon oxycarbides (SiO x C y ) at the SiO 2 /SiC interface was demonstrated by X-ray photospectroscopy (XPS) analysis. Carbon was detected by Raman spectroscopy at the interface under conditions of very high temperatures and long oxidation time. From oxidation kinetics calculation, activation energies were 145 kJ/mol and 352 kJ/mol for the temperature ranges of 1200–1500 °C and 1550–1600 °C, respectively

  5. Pressure analysis in the fabrication process of TRISO UO2-coated fuel particle

    International Nuclear Information System (INIS)

    Liu Malin; Shao Youlin; Liu Bing

    2012-01-01

    Highlights: ► The pressure signals during the real TRISO UO2-coated fuel particle fabrication process. ► A new relationship about the pressure drop change and the coated fuel particles properties. ► The proposed relationship is validated by experimental results during successive coating. ► A convenient method for monitoring the fluidized state during coating process. - Abstract: The pressure signals in the coating furnace are obtained experimentally from the TRISO UO 2 -coated fuel particle fabrication process. The pressure signals during the coating process are analyzed and a simplified relationship about the pressure drop change due to the coated layer is proposed based on the spouted bed hydrodynamics. The change of pressure drop is found to be consistent with the change of the combination factor about particle density, bed density, particle diameter and static bed height, during the successive coating process of the buffer PyC, IPyC, SiC and OPyC layer. The newly proposed relationship is validated by the experimental values. Based on this relationship, a convenient method is proposed for real-time monitoring the fluidized state of the particles in a high-temperature coating process in the spouted bed. It can be found that the pressure signals analysis is an effective method to monitor the fluidized state on-line in the coating process at high temperature up to 1600 °C.

  6. Comparative study of random and uniform models for the distribution of TRISO particles in HTR-10 fuel elements

    International Nuclear Information System (INIS)

    Rosales, J.; Perez, J.; Garcia, C.; Munnoz, A.; Lira, C. A. B. O.

    2015-01-01

    TRISO particles are the specific features of HTR-10 and generally HTGR reactors. Their heterogeneity and random arrangement in graphite matrix of these reactors create a significant modeling challenge. In the simulation of spherical fuel elements using MCNPX are usually created repetitive structures using uniform distribution models. The use of these repetitive structures introduces two major approaches: the non-randomness of the TRISO particles inside the pebbles and the intersection of the pebble surface with the TRISO particles. These approaches could affect significantly the multiplicative properties of the core. In order to study the influence of these approaches in the multiplicative properties was estimated the K inf value in one pebble with white boundary conditions using 4 different configurations regarding the distribution of the TRISO particles inside the pebble: uniform hexagonal model, cubic uniform model, cubic uniform without the effect of cutting and a random distribution model. It was studied the impact these models on core scale solving the problem B1, from the Benchmark Problems presented in a Coordinated Research Program of the IAEA. (Author)

  7. Urethral and periurethral dosimetry in prostate brachytherapy: is there a convenient surrogate?

    International Nuclear Information System (INIS)

    Bucci, Joseph; Spadinger, Ingrid; Hilts, Michelle; Sidhu, Sabeena; Smith, Clarke; Keyes, Mira; Morris, W. James

    2002-01-01

    Purpose: To assess and compare two models for a surrogate urethra to be used for postimplant dosimetry in prostate brachytherapy. Methods and Materials: Twenty men with a urinary catheter present at the time of postimplant computed tomographic imaging were studied. Urethral and periurethral volumes were defined as 5-mm and 10-mm diameter volumes, respectively. Three contours of each were used: one contour of the true urethra (and periurethra), and two surrogate models. The true volumes were centered on the catheter center. One surrogate model used volumes centered on the geometrical center of each prostate contour (centered surrogate). The other surrogate model was based on the average deviation of the true urethra from a reference line through the geometrical center of the axial midplane of the prostate (deviated surrogate). Maximum point doses and the D 10 , D 25 , D 50 , D 90 , V 100 , V 120 , and V 150 of the true and surrogate volumes were measured and compared (D n is the minimum dose [Gy] received by n% of the structure, and V m is the volume [%] of the structure that received m% of the prescribed dose) as well as the distances between the surrogate urethras and the true urethra. Results: Doses determined from both surrogate urethral and periurethral volumes were in good agreement with the true urethral and periurethral doses except in the superior third of the gland. The deviated surrogate provided a physically superior likeness to the true urethra. Certain dose-volume histogram (DVH)-based parameters could also be predicted reasonably well on the basis of the surrogates. Correlation coefficients ≥0.85 were seen for D 25 , D 50 , V 100 , V 120 , and V 150 for both models. All the other parameters had correlation coefficients in the range of 0.73 - 0.85. Conclusions: Both surrogate models predicted true urethral dosimetry reasonably well. It is recommended that the simpler deviated surrogate would be a more suitable surrogate for routine clinical practice

  8. Measurement of kernel swelling and buffer densification in irradiated UCO-TRISO particles

    Energy Technology Data Exchange (ETDEWEB)

    Bower, Gordon R., E-mail: bowegr@inl.gov [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415-6188 (United States); Ploger, Scott A.; Demkowicz, Paul A. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415-6188 (United States); Hunn, John D. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37830-6093 (United States)

    2017-04-01

    Radiation-induced volume changes in the fuel kernels and buffer layers of UCO-TRISO particles irradiated to an average burnup of 16.1% FIMA have been determined. Measurements of particle dimensions were made on polished cross-sections of 56 irradiated particles at several different polish planes. The data were then analyzed to compute the equivalent spherical diameters of the kernels and the various coating layers, and these were compared to the average as-fabricated values to determine changes due to irradiation. The kernel volume was found to have increased by an average of 26 ± 6%. Buffer volume decreased by an average of 39 ± 2% due to densification.

  9. Psychosocial aspects of surrogate motherhood.

    Science.gov (United States)

    van den Akker, Olga B A

    2007-01-01

    This review addresses the psychosocial research carried out on surrogacy triads (surrogate mothers, commissioning mothers and offspring) and shows that research has focused on a number of specific issues: attachment and disclosure to surrogate offspring; experiences, characteristics and motivations of surrogate mothers; and changes in profiles of the commissioning/intended mothers. Virtually all studies have used highly selected samples making generalizations difficult. There have been a notable lack of theory, no interventions and only a handful of longitudinal studies or studies comparing different populations. Few studies have specifically questioned the meaning of and need for a family or the influence and impact that professionals, treatment availability and financial factors have on the choices made for surrogate and intended mothers. Societal attitudes have changed somewhat; however, according to public opinion, women giving up babies still fall outside the acceptable remit. Surrogate and intended mothers appear to reconcile their unusual choice through a process of cognitive restructuring, and the success or failure of this cognitive appraisal affects people's willingness to be open and honest about their choices. Normal population surveys, on the contrary, are less accepting of third party reproduction; they have no personal need to reconsider and hence maintain their original normative cognitively consonant state.

  10. Licensing Surrogate Decision-Makers.

    Science.gov (United States)

    Rosoff, Philip M

    2017-06-01

    As medical technology continues to improve, more people will live longer lives with multiple chronic illnesses with increasing cumulative debilitation, including cognitive dysfunction. Combined with the aging of society in most developed countries, an ever-growing number of patients will require surrogate decision-makers. While advance care planning by patients still capable of expressing their preferences about medical interventions and end-of-life care can improve the quality and accuracy of surrogate decisions, this is often not the case, not infrequently leading to demands for ineffective, inappropriate and prolonged interventions. In 1980 LaFollette called for the licensing of prospective parents, basing his argument on the harm they can do to vulnerable people (children). In this paper, I apply his arguments to surrogate decision-makers for cognitively incapacitated patients, rhetorically suggesting that we require potential surrogates to qualify for this position by demonstrating their ability to make reasonable and rational decisions for others. I employ this theoretical approach to argue that the loose criteria by which we authorize surrogates' generally unchallenged power should be reconsidered.

  11. Long-Term Stability Testing Results Using Surrogates And Sorbents For Savannah River Site Organic And Aqueous Wastestreams - 10016

    International Nuclear Information System (INIS)

    Burns, H.

    2009-01-01

    The U.S. Department of Energy (DOE) has tasked MSE Technology Applications, Inc. (MSE) with evaluating the long-term stability of various commercially available sorbent materials to solidify two organic surrogate wastestreams (both volatile and nonvolatile), a volatile organic surrogate with a residual aqueous phase, an aqueous surrogate, and an aqueous surrogate with a residual organic phase. The Savannah River Site (SRS) Legacy and F-Canyon plutonium/uranium extraction (PUREX) process waste surrogates constituted the volatile organic surrogates, and various oils constituted the nonvolatile organic surrogates. The aqueous surrogates included a rainwater surrogate and an aqueous organic surrogate. MSE also evaluated the PUREX surrogate with a residual aqueous component with and without aqueous type sorbent materials. Solidification of the various surrogate wastestreams listed above was performed from 2004 to 2006 at the MSE Test Facility located in Butte, Montana. This paper summarizes the comparison of the initial liquid release test (LRT) values with LRT results obtained during subsequent sampling events in an attempt to understand and define the long-term stability characteristics for the solidified wastestreams.

  12. Glass-Graphite Composite Materials

    International Nuclear Information System (INIS)

    Mayzan, M.Z.H.; Lloyd, J.W.; Heath, P.G.; Stennett, M.C.; Hyatt, N.C.; Hand, R.J.

    2016-01-01

    A summary is presented of investigations into the potential of producing glass-composite materials for the immobilisation of graphite or other carbonaceous materials arising from nuclear power generation. The methods are primarily based on the production of base glasses which are subsequently sintered with powdered graphite or simulant TRISO particles. Consideration is also given to the direct preparation of glass-graphite composite materials using microwave technology. Production of dense composite wasteforms with TRISO particles was more successful than with powdered graphite, as wasteforms containing larger amounts of graphite were resistant to densification and the glasses tried did not penetrate the pores under the pressureless conditions used. Based on the results obtained it is concluded that the production of dense glassgraphite composite wasteforms will require the application of pressure. (author)

  13. Coating Thickness Measurement of the Simulated TRISO-Coated Fuel Particles using an Image Plate and a High Resolution Scanner

    International Nuclear Information System (INIS)

    Kim, Woong Ki; Kim, Yeon Ku; Jeong, Kyung Chai; Lee, Young Woo; Kim, Bong Goo; Eom, Sung Ho; Kim, Young Min; Yeo, Sung Hwan; Cho, Moon Sung

    2014-01-01

    In this study, the thickness of the coating layers of 196 coated particles was measured using an Image Plate detector, high resolution scanner and digital image processing techniques. The experimental results are as follows. - An X-ray image was acquired for 196 simulated TRISO-coated fuel particles with ZrO 2 kernel using an Image Plate with high resolution in a reduced amount of time. - We could observe clear boundaries between coating layers for 196 particles. - The geometric distortion error was compensated for the calculation. - The coating thickness of the TRISO-coated fuel particles can be nondestructively measured using X-ray radiography and digital image processing technology. - We can increase the number of TRISO-coated particles to be inspected by increasing the number of Image Plate detectors. A TRISO-coated fuel particle for an HTGR (high temperature gas-cooled reactor) is composed of a nuclear fuel kernel and outer coating layers. The coating layers consist of buffer PyC (pyrolytic carbon), inner PyC (I-PyC), SiC, and outer PyC (O-PyC) layer. The coating thickness is measured to evaluate the soundness of the coating layers. X-ray radiography is one of the nondestructive alternatives for measuring the coating thickness without generating a radioactive waste. Several billion particles are subject to be loaded in a reactor. A lot of sample particles should be tested as much as possible. The acquired X-ray images for the measurement of coating thickness have included a small number of particles because of the restricted resolution and size of the X-ray detector. We tried to test many particles for an X-ray exposure to reduce the measurement time. In this experiment, an X-ray image was acquired for 196 simulated TRISO-coated fuel particles using an image plate and high resolution scanner with a pixel size of 25Χ25 μm 2 . The coating thickness for the particles could be measured on the image

  14. KEY RESULTS FROM IRRADIATION AND POST-IRRADIATION EXAMINATION OF AGR-1 UCO TRISO FUEL

    Energy Technology Data Exchange (ETDEWEB)

    Demkowicz, Paul A.; Hunn, John D.; Petti, David A.; Morris, Robert N.

    2016-11-01

    The AGR-1 irradiation experiment was performed as the first test of tristructural isotropic (TRISO) fuel in the US Advanced Gas Reactor Fuel Development and Qualification Program. The experiment consisted of 72 right cylinder fuel compacts containing approximately 3×105 coated fuel particles with uranium oxide/uranium carbide (UCO) fuel kernels. The fuel was irradiated in the Advanced Test Reactor for a total of 620 effective full power days. Fuel burnup ranged from 11.3 to 19.6% fissions per initial metal atom and time average, volume average irradiation temperatures of the individual compacts ranged from 955 to 1136°C. This paper focuses on key results from the irradiation and post-irradiation examination, which revealed a robust fuel with excellent performance characteristics under the conditions tested and have significantly improved the understanding of UCO coated particle fuel irradiation behavior within the US program. The fuel exhibited a very low incidence of TRISO coating failure during irradiation and post-irradiation safety testing at temperatures up to 1800°C. Advanced PIE methods have allowed particles with SiC coating failure to be isolated and meticulously examined, which has elucidated the specific causes of SiC failure in these specimens. The level of fission product release from the fuel during irradiation and post-irradiation safety testing has been studied in detail. Results indicated very low release of krypton and cesium through intact SiC and modest release of europium and strontium, while also confirming the potential for significant silver release through the coatings depending on irradiation conditions. Focused study of fission products within the coating layers of irradiated particles down to nanometer length scales has provided new insights into fission product transport through the coating layers and the role various fission products may have on coating integrity. The broader implications of these results and the application of

  15. 1976 scientific progress report. [Fuel and coating materials for HTGR]; Wissenschaftlicher Ergebnisberict 1976

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, H.

    1976-07-01

    Activities at the Institute for Reactor Materials in the production and properties of high temperature gas cooled reactor fuel and coating materials are summarized. Major emphasis was placed on investigations of pyrocarbon, BISO and TRISO coatings, uranium and thorium oxides and carbides, and graphite and matrix materials. A list of publications is included. (HDR)

  16. Operation Procedure of Inspection Equipment for TRISO-coated Fuel Particle

    International Nuclear Information System (INIS)

    Kim, S. H.; Kim, Y. K.; Cho, M. S.; Kim, Y. M.; Park, J. Y.; Kim, W. J.; Jeong, K. C.; Oh, S. C.; Lee, Y. W.

    2007-03-01

    TRISO-coated fuel particle for HTGR(high temperature gas cooled reactor) is composed of fuel kernel and coating layers. The kernel and coated particle are characterized by inspection processes for inspection items such as diameter of kernel, thickness, density and an-isotropy of coating layer. The coating thickness can be nondestructively measured by X-ray inspection equipment. The coating thickness as well as the sphericity can be also measured by optical inspection system as a ceramography method. The an-isotropy can be characterized by photometer. The density of coating layer can be measured by density column. The size and sphericity of particles can be measured by PSA(particle size analyzer). The thermo-chemical characteristics of kernel can be analyzed by TG/DTA(Thermogravimetric/Differential Thermal Analyzer). The inspection objective, equipment composition, operation principle, operation manual for each equipment was described in this operation procedure, which will be used for the characterization of inspection items described above

  17. Calculating failure probabilities for TRISO-coated fuel particles using an integral formulation

    International Nuclear Information System (INIS)

    Miller, Gregory K.; Maki, John T.; Knudson, Darrell L.; Petti, David A.

    2010-01-01

    The fundamental design for a gas-cooled reactor relies on the safe behavior of the coated particle fuel. The coating layers surrounding the fuel kernels in these spherical particles, termed the TRISO coating, act as a pressure vessel that retains fission products. The quality of the fuel is reflected in the number of particle failures that occur during reactor operation, where failed particles become a source for fission products that can then diffuse through the fuel element. The failure probability for any batch of particles, which has traditionally been calculated using the Monte Carlo method, depends on statistical variations in design parameters and on variations in the strengths of coating layers among particles in the batch. An alternative approach to calculating failure probabilities is developed herein that uses direct numerical integration of a failure probability integral. Because this is a multiple integral where the statistically varying parameters become integration variables, a fast numerical integration approach is also developed. In sample cases analyzed involving multiple failure mechanisms, results from the integration methods agree closely with Monte Carlo results. Additionally, the fast integration approach, particularly, is shown to significantly improve efficiency of failure probability calculations. These integration methods have been implemented in the PARFUME fuel performance code along with the Monte Carlo method, where each serves to verify accuracy of the others.

  18. Surrogate mothering: exploitation or empowerment?

    Science.gov (United States)

    Purdy, Laura M

    1989-01-01

    The morality of surrogate mothering is analyzed from a "consequentialist" framework which attempts to separate those consequences that invariably accompany a given act from those that accompany it only in particular circumstances. Critics of surrogacy argue that it transfers the burden and risk of pregnancy onto another woman, separates sex and reproduction, and separates reproduction and childrearing; none of these acts is necessarily wrong, either morally or for women's or society's basic interests. While surrogate mothering can be rendered immoral if women are coerced into the practice or become victims of subordinating or penalizing contracts, it has the potential to empower women and increase their status in society by providing a job that is less risky and more enjoyable than other jobs women are forced to take and by achieving greater social recognition for reproductive labor.

  19. Toward a Psychology of Surrogate Decision Making.

    Science.gov (United States)

    Tunney, Richard J; Ziegler, Fenja V

    2015-11-01

    In everyday life, many of the decisions that we make are made on behalf of other people. A growing body of research suggests that we often, but not always, make different decisions on behalf of other people than the other person would choose. This is problematic in the practical case of legally designated surrogate decision makers, who may not meet the substituted judgment standard. Here, we review evidence from studies of surrogate decision making and examine the extent to which surrogate decision making accurately predicts the recipient's wishes, or if it is an incomplete or distorted application of the surrogate's own decision-making processes. We find no existing domain-general model of surrogate decision making. We propose a framework by which surrogate decision making can be assessed and a novel domain-general theory as a unifying explanatory concept for surrogate decisions. © The Author(s) 2015.

  20. Bedload-surrogate monitoring technologies

    Science.gov (United States)

    Gray, John R.; Laronne, Jonathan B.; Marr, Jeffrey D.G.

    2010-01-01

    Advances in technologies for quantifying bedload fluxes and in some cases bedload size distributions in rivers show promise toward supplanting traditional physical samplers and sampling methods predicated on the collection and analysis of physical bedload samples. Four workshops held from 2002 to 2007 directly or peripherally addressed bedload-surrogate technologies, and results from these workshops have been compiled to evaluate the state-of-the-art in bedload monitoring. Papers from the 2007 workshop are published for the first time with this report. Selected research and publications since the 2007 workshop also are presented. Traditional samplers used for some or all of the last eight decades include box or basket samplers, pan or tray samplers, pressure-difference samplers, and trough or pit samplers. Although still useful, the future niche of these devices may be as a means for calibrating bedload-surrogate technologies operating with active- and passive-type sensors, in many cases continuously and automatically at a river site. Active sensors include acoustic Doppler current profilers (ADCPs), sonar, radar, and smart sensors. Passive sensors include geophones (pipes or plates) in direct contact with the streambed, hydrophones deployed in the water column, impact columns, and magnetic detection. The ADCP for sand and geophones for gravel are currently the most developed techniques, several of which have been calibrated under both laboratory and field conditions. Although none of the bedload-surrogate technologies described herein are broadly accepted for use in large-scale monitoring programs, several are under evaluation. The benefits of verifying and operationally deploying selected bedload-surrogate monitoring technologies could be considerable, providing for more frequent and consistent, less expensive, and arguably more accurate bedload data obtained with reduced personal risk for use in managing the world's sedimentary resources. Twenty-six papers are

  1. On Design Mining: Coevolution and Surrogate Models.

    Science.gov (United States)

    Preen, Richard J; Bull, Larry

    2017-01-01

    Design mining is the use of computational intelligence techniques to iteratively search and model the attribute space of physical objects evaluated directly through rapid prototyping to meet given objectives. It enables the exploitation of novel materials and processes without formal models or complex simulation. In this article, we focus upon the coevolutionary nature of the design process when it is decomposed into concurrent sub-design-threads due to the overall complexity of the task. Using an abstract, tunable model of coevolution, we consider strategies to sample subthread designs for whole-system testing and how best to construct and use surrogate models within the coevolutionary scenario. Drawing on our findings, we then describe the effective design of an array of six heterogeneous vertical-axis wind turbines.

  2. The shifting study of the active core or a VHTR based on the TRISO packing fraction changing

    Energy Technology Data Exchange (ETDEWEB)

    Silva, F.C.; Pereira, C.; Veloso, M.A.F., E-mail: claubia@nuclear.ufmg.br, E-mail: antonella@nuclear.ufmg.br, E-mail: dora@nuclear.ufmg.br [Departamento de Engenharia Nuclear. Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Costa, A.L. [Instituto Nacional de Ciencias e Tecnologia de Reatores Nucleares Inovadores (CNPq), Brasilia, DF (Brazil)

    2011-07-01

    A simplified VHTR core was analyzed, loaded with a fuel mixture of uranium oxide together with reprocessed transuranic nuclides. The TRUs were reprocessed together with Pu, Am, Np and Cm (23.80%) from PWR spent fuel, and dissolved in depleted uranium (0.2% {sup 235}U) until obtain 15% LEU-fuel ({sup 235}U, {sup 239}Pu and {sup 241}Pu). The shifting study of the active core was based on changes in the TRISO particle. Five cases were analyzed changing the VM/VF ratio (moderator volume/ fuel volume) making changes in the TRISO packing fraction (tpf), where tpf represents the ratio of TRISO particle on the fuel pin. The fuels were evaluated during the burnup up to 100,000.0 MWd/THM, during 990 days and without reloads. Then, it evaluated the multiplication (k{sub eff}) at zero and full power, fuel temperature coefficient ({alpha}{sub TF}), moderator temperature coefficient ({alpha}{sub TM}), and fuel composition at BOL (begin of life) and EOL (end of life), using the code Winfrith Improved Multi-Group Scheme (WIMSD5). The results show an overall heavy metal decrease in relation to the total TRU, with some Pu and Np being transmuted in the VHTR core. The results also clearly show the advantage of using reprocessed fuel in VHTR. It decreases the impact of the final spent fuel deposition, minimizes the cost of new fuel using reprocessed fuel and depleted uranium and demonstrated the promising neutronic behavior of the new types of nuclear reactors. (author)

  3. Spent UO{sub 2} TRISO coated particles. Instant release fraction and microstructure evolution

    Energy Technology Data Exchange (ETDEWEB)

    Curtius, Hildegard; Kaiser, Gabriele; Lieck, Norman; Guengoer, Murat; Klinkenberg, Martina; Bosbach, Dirk [Research Center Juelich (Germany). Inst. of Energy and Climate Research IEK-6: Nuclear Waste Management and Reactor Safety

    2015-09-01

    The impact of burn-up on the instant release fraction (IRF) from spent fuel was studied using very high burn-up UO{sub 2} fuel (∝ 100 GWd/t) from a prototype high temperature reactor (HTR). TRISO (TRi-structural-ISO-tropic) particles from the spherical fuel elements contain UO{sub 2} fuel kernels (500 μm diameter) which are coated by three tight layers ensuring the encapsulation of fission products during reactor operation. After cracking of the tight coatings {sup 85}Kr and {sup 14}C as {sup 14}CO{sub 2} were detected in the gas fraction. Xe was not detected in the gas fraction, although ESEM (Environmental Scanning Electron Microscope) investigations revealed an accumulation in the buffer. UO{sub 2} fuel kernels were exposed to synthetic groundwater under oxic and anoxic/reducing conditions. U concentration in the leachate was below the detection limit, indicating an extremely low matrix dissolution. Within the leach period of 276 d {sup 90}Sr and {sup 134/137}Cs fractions located at grain boundaries were released and contribution to IRF up to max. 0.2% respectively 8%. Depending on the environmental conditions, different release functions were observed. Second relevant release steps occurred in air after ∝ 120 d, indicating the formation of new accessible leaching sites. ESEM investigations were performed to study the impact of leaching on the microstructure. In oxic environment, numerous intragranular open pores acting as new accessible leaching sites were formed and white spherical spots containing Mo and Zr were identified. Under anoxic/reducing conditions numerous metallic precipitates (Mo, Tc and Ru) filling the intragranular pores and white spherical spots containing Mo and Zr, were detected. In conclusion, leaching in different geochemical environments influenced the speciation of radionuclides and in consequence the stability of neoformed phases, which has an impact on IRF.

  4. Ethical Problems Related to Surrogate Motherhood

    OpenAIRE

    Erdem Aydin

    2006-01-01

    Being unable to have children is an important problem for married couples. At present, new reproduction techniques help these couples while those who can not find any solution try new approaches. One of these is the phenomenon of surrogate motherhood, which is based upon an agreement between the infertile couple and surrogate mother. Surrogate mother may conceive with the sperm of the male of the involved couple as well as by the transfer of the embryo formed by invitro fertilization. Couples...

  5. Interpretations, perspectives and intentions in surrogate motherhood

    OpenAIRE

    van Zyl, L.; van Niekerk, A.

    2000-01-01

    In this paper we examine the questions "What does it mean to be a surrogate mother?" and "What would be an appropriate perspective for a surrogate mother to have on her pregnancy?" In response to the objection that such contracts are alienating or dehumanising since they require women to suppress their evolving perspective on their pregnancies, liberal supporters of surrogate motherhood argue that the freedom to contract includes the freedom to enter a contract to bear a child for an infertil...

  6. ETHICAL ISSUES IN THE SURROGATE MATERNITY PRACTICE

    OpenAIRE

    TÜRK, Rukiye; TERZİOĞLU, Fusun

    2014-01-01

    The assisted reproductive technology was initially considered to be a treatment tool for infertile couples. However, as it was started in time to use the uteri of other women for the embryos of the other ones, the concept of surrogate maternity appeared.The surrogate maternity is practiced in three types. In the first type of surrogate maternity, the sperm of the spouse of the prospective mother is inseminated with the ovum of the surrogate mother. The second method is the in-vitro inseminati...

  7. Surrogate Analysis and Index Developer (SAID) tool

    Science.gov (United States)

    Domanski, Marian M.; Straub, Timothy D.; Landers, Mark N.

    2015-10-01

    The use of acoustic and other parameters as surrogates for suspended-sediment concentrations (SSC) in rivers has been successful in multiple applications across the Nation. Tools to process and evaluate the data are critical to advancing the operational use of surrogates along with the subsequent development of regression models from which real-time sediment concentrations can be made available to the public. Recent developments in both areas are having an immediate impact on surrogate research and on surrogate monitoring sites currently (2015) in operation.

  8. Mechanical Properties of K Basin Sludge Constituents and Their Surrogates

    International Nuclear Information System (INIS)

    Delegard, Calvin H.; Schmidt, Andrew J.; Chenault, Jeffrey W.

    2004-01-01

    A survey of the technical literature was performed to summarize the mechanical properties of inorganic components in K Basins sludge. The components included gibbsite, ferrihydrite, lepidocrocite and goethite, hematite, quartz, anorthite, calcite, basalt, Zircaloy, aluminum, and, in particular, irradiated uranium metal and uranium dioxide. Review of the technical literature showed that information on the hardness of uranium metal at irradiation exposures similar to those experienced by the N Reactor fuel present in the K Basins (typically up to 3000 MWd/t) were not available. Measurements therefore were performed to determine the hardness of coupons taken from three irradiated N Reactor uranium metal fuel elements taken from K Basins. Hardness values averaged 30 ± 8 Rockwell C units, similar to values previously reported for uranium irradiated to ∼1200 MWd/t. The physical properties of candidate uranium metal and uranium dioxide surrogates were gathered and compared. Surrogates having properties closest to those of irradiated uranium metal appear to be alloys of tungsten. The surrogate for uranium dioxide, present both as particles and agglomerates in actual K Basin sludge, likely requires two materials. Cerium oxide, CeO2, was identified as a surrogate of the smaller UO2 particles while steel grit was identified for the UO2 agglomerates

  9. Key differences in the fabrication of US and German TRISO-coated particle fuel, and their implications on fuel performance

    International Nuclear Information System (INIS)

    Petti, D.A.; Buongiorno, J.; Maki, J.T.; Miller, G.K.; Hobbins, R.R.

    2002-01-01

    Historically, the irradiation performance of TRISO-coated gas reactor particle fuel in Germany has been superior to that in the US. German fuel generally displayed in-pile gas release values that were three orders of magnitude lower than US fuel. Thus, we have critically examined the TRISO-coated fuel fabrication processes in the US and German and the associated irradiation database with a goal of understanding why the German fuel behaves acceptably, why the US fuel has not faired as well, and what process/production parameters impart the reliable performance to this fuel form. The postirradiation examination results are also reviewed to identify failure mechanisms that may be the cause of the poorer US irradiation performance. This comparison will help determine the roles that particle fuel process/product attributes and irradiation conditions (burnup, fast neutron fluence, temperature, degree of acceleration, power per particle) have on the behavior of the fuel during irradiation and provide a more quantitative linkage between acceptable processing parameters, as-fabricated fuel properties and subsequent in-reactor performance. (author)

  10. ADVANCING THE FUNDAMENTAL UNDERSTANDING AND SCALE-UP OF TRISO FUEL COATERS VIA ADVANCED MEASUREMENT AND COMPUTATIONAL TECHNIQUES

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Pratim; Al-Dahhan, Muthanna

    2012-11-01

    Tri-isotropic (TRISO) fuel particle coating is critical for the future use of nuclear energy produced byadvanced gas reactors (AGRs). The fuel kernels are coated using chemical vapor deposition in a spouted fluidized bed. The challenges encountered in operating TRISO fuel coaters are due to the fact that in modern AGRs, such as High Temperature Gas Reactors (HTGRs), the acceptable level of defective/failed coated particles is essentially zero. This specification requires processes that produce coated spherical particles with even coatings having extremely low defect fractions. Unfortunately, the scale-up and design of the current processes and coaters have been based on empirical approaches and are operated as black boxes. Hence, a voluminous amount of experimental development and trial and error work has been conducted. It has been clearly demonstrated that the quality of the coating applied to the fuel kernels is impacted by the hydrodynamics, solids flow field, and flow regime characteristics of the spouted bed coaters, which themselves are influenced by design parameters and operating variables. Further complicating the outlook for future fuel-coating technology and nuclear energy production is the fact that a variety of new concepts will involve fuel kernels of different sizes and with compositions of different densities. Therefore, without a fundamental understanding the underlying phenomena of the spouted bed TRISO coater, a significant amount of effort is required for production of each type of particle with a significant risk of not meeting the specifications. This difficulty will significantly and negatively impact the applications of AGRs for power generation and cause further challenges to them as an alternative source of commercial energy production. Accordingly, the proposed work seeks to overcome such hurdles and advance the scale-up, design, and performance of TRISO fuel particle spouted bed coaters. The overall objectives of the proposed work are

  11. Pan masala advertisements are surrogate for tobacco products

    OpenAIRE

    Sushma C; Sharang C

    2005-01-01

    BACKGROUND: Pan masala is a comparatively recent habit in India and is marketed with and without tobacco. Advertisements of tobacco products have been banned in India since 1st May 2004. The advertisements of plain pan masala, which continue in Indian media, have been suspected to be surrogate for tobacco products bearing the same name. The study was carried out to assess whether these advertisements were for the intended product, or for tobacco products with same brand name. MATERIALS AND ...

  12. The Reparative Motive in Surrogate Mothers.

    Science.gov (United States)

    Kanefield, Linda

    1999-01-01

    Explores the motivations of surrogate mothers, focusing on underlying reparative motive--to compensate for or repair an earlier loss or sense of damage. Provides an overview of the typical surrogate's characteristics and personality, discusses the theoretical underpinnings of the reparative motive, and considers the tension between reparation and…

  13. 34 CFR 303.406 - Surrogate parents.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Surrogate parents. 303.406 Section 303.406 Education... DISABILITIES Procedural Safeguards General § 303.406 Surrogate parents. (a) General. Each lead agency shall ensure that the rights of children eligible under this part are protected if— (1) No parent (as defined...

  14. 34 CFR 300.519 - Surrogate parents.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Surrogate parents. 300.519 Section 300.519 Education... DISABILITIES Procedural Safeguards Due Process Procedures for Parents and Children § 300.519 Surrogate parents... parent (as defined in § 300.30) can be identified; (2) The public agency, after reasonable efforts...

  15. Imaging Seeker Surrogate for IRCM evaluation

    NARCIS (Netherlands)

    Schleijpen, H.M.A.; Carpenter, S.R.; Mellier, B.; Dimmeler, A.

    2007-01-01

    NATO-SCI-139 and its predecessor groups have more than a decade of history in the evaluation and recommendation of EO and IR Countermeasures against anti-aircraft missiles. Surrogate Seekers have proven to be a valuable tool for this work. The use of surrogate seekers in international co-operations

  16. The interactive surrogate travel system.

    Science.gov (United States)

    Nakajima, I; Ichimura, A; Juzoji, H; Mugita, K

    1999-01-01

    The Interactive Surrogate Travel (IST) system is based on the super-miniaturized system of virtual technology, Cave Automatic Virtual Environment (CAVE). Using bilateral virtual reality (VR-to-VR) communications, IST enables the testing of subjects via interactive communications. It appears that IST will find practical applications in the near future. We examined the utility of IST in medical treatment and psychiatric tests. Psychiatric symptoms reflect human pathos, which in turn are greatly influenced by culture. If these culture-bound symptoms can be adequately communicated between providers and clients of different cultures, we can develop effective telepsychiatric services across different societies and cultures. IST requires high-speed transmission and gigabyte circuits. A pilot project tested the utility of IST (through the use of optical fiber communications on earth) as a basis for experiments via the Gigabit satellite, to be launched in the year 2002.

  17. Use of Surrogate end points in HTA

    Directory of Open Access Journals (Sweden)

    Mangiapane, Sandra

    2009-08-01

    Full Text Available The different actors involved in health system decision-making and regulation have to deal with the question which are valid parameters to assess the health value of health technologies.So called surrogate endpoints represent in the best case preliminary steps in the casual chain leading to the relevant outcome (e. g. mortality, morbidity and are not usually directly perceptible by patients. Surrogate endpoints are not only used in trials of pharmaceuticals but also in studies of other technologies. Their use in the assessment of the benefit of a health technology is however problematic. In this report we intend to answer the following research questions: Which criteria need to be fulfilled for a surrogate parameter to be considered a valid endpoint? Which methods have been described in the literature for the assessment of the validity of surrogate endpoints? Which methodological recommendations concerning the use of surrogate endpoints have been made by international HTA agencies? Which place has been given to surrogate endpoints in international and German HTA reports? For this purpose, we choose three different approaches. Firstly, we conduct a review of the methodological literature dealing with the issue of surrogate endpoints and their validation. Secondly, we analyse current methodological guidelines of HTA agencies members of the International network of agencies for Health Technology Assessment (INAHTA as well as of agencies concerned with assessments for reimbursement purposes. Finally, we analyse the outcome parameter used in a sample of HTA reports available for the public. The analysis of methodological guidelines shows a very cautious position of HTA institutions regarding the use of surrogate endpoints in technology assessment. Surrogate endpoints have not been prominently used in HTA reports. None of the analysed reports based its conclusions solely on the results of surrogate endpoints. The analysis of German HTA reports shows a

  18. An Evaluation of Two Internal Surrogates for Determining the Three-Dimensional Position of Peripheral Lung Tumors

    NARCIS (Netherlands)

    Spoelstra, F.O.B.; Sornsen de Koste, van J.R.; Vincent, A.D.; Cuijpers, J.P.; Slotman, B.J.; Senan, S.

    2009-01-01

    Purpose: Both carina and diaphragm positions have been used as surrogates during respiratory-gated radiotherapy. We studied the correlation of both surrogates with three-dimensional (3D) tumor position. Methods and Materials: A total of 59 repeat artifact-free four-dimensional (4D) computed

  19. Hypothesis test for synchronization: twin surrogates revisited.

    Science.gov (United States)

    Romano, M Carmen; Thiel, Marco; Kurths, Jürgen; Mergenthaler, Konstantin; Engbert, Ralf

    2009-03-01

    The method of twin surrogates has been introduced to test for phase synchronization of complex systems in the case of passive experiments. In this paper we derive new analytical expressions for the number of twins depending on the size of the neighborhood, as well as on the length of the trajectory. This allows us to determine the optimal parameters for the generation of twin surrogates. Furthermore, we determine the quality of the twin surrogates with respect to several linear and nonlinear statistics depending on the parameters of the method. In the second part of the paper we perform a hypothesis test for phase synchronization in the case of experimental data from fixational eye movements. These miniature eye movements have been shown to play a central role in neural information processing underlying the perception of static visual scenes. The high number of data sets (21 subjects and 30 trials per person) allows us to compare the generated twin surrogates with the "natural" surrogates that correspond to the different trials. We show that the generated twin surrogates reproduce very well all linear and nonlinear characteristics of the underlying experimental system. The synchronization analysis of fixational eye movements by means of twin surrogates reveals that the synchronization between the left and right eye is significant, indicating that either the centers in the brain stem generating fixational eye movements are closely linked, or, alternatively that there is only one center controlling both eyes.

  20. Surrogacy: the experiences of surrogate mothers.

    Science.gov (United States)

    Jadva, Vasanti; Murray, Clare; Lycett, Emma; MacCallum, Fiona; Golombok, Susan

    2003-10-01

    This study examined the motivations, experiences and psychological consequences of surrogacy for surrogate mothers. Thirty-four women who had given birth to a surrogate child approximately 1 year previously were interviewed by trained researchers, and the data rated using standardized coding criteria. Information was obtained on: (i) reasons for the woman's decision to become a surrogate mother; (ii) her retrospective view of the relationship with the commissioning couple before the pregnancy, during the pregnancy, and after the birth; (iii) her experiences during and after relinquishing the child; and (iv) how others reacted to her decision to become a surrogate mother. It was found that surrogate mothers do not generally experience major problems in their relationship with the commissioning couple, in handing over the baby, or from the reactions of those around them. The emotional problems experienced by some surrogate mothers in the weeks following the birth appeared to lessen over time. Surrogate mothers do not appear to experience psychological problems as a result of the surrogacy arrangement.

  1. So not mothers: responsibility for surrogate orphans.

    Science.gov (United States)

    Parks, Jennifer A; Murphy, Timothy F

    2018-04-12

    The law ordinarily recognises the woman who gives birth as the mother of a child, but in certain jurisdictions, it will recognise the commissioning couple as the legal parents of a child born to a commercial surrogate. Some commissioning parents have, however, effectively abandoned the children they commission, and in such cases, commercial surrogates may find themselves facing unexpected maternal responsibility for children they had fully intended to give up. Any assumption that commercial surrogates ought to assume maternal responsibility for abandoned children runs contrary to the moral suppositions that typically govern contract surrogacy, in particular, assumptions that gestational carriers are not 'mothers' in any morally significant sense. In general, commercial gestational surrogates are almost entirely conceptualised as 'vessels'. In a moral sense, it is deeply inconsistent to expect commercial surrogates to assume maternal responsibility simply because commissioning parents abandon children for one reason or another. We identify several instances of child abandonment and discuss their implications with regard to the moral conceptualisation of commercial gestational surrogates. We conclude that if gestational surrogates are to remain conceptualised as mere vessels, they should not be expected to assume responsibility for children abandoned by commissioning parents, not even the limited responsibility of giving them up for adoption or surrendering them to the state. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. Calculations of IAEA-CRP-6 Benchmark Case 1 through 7 for a TRISO-Coated Fuel Particle

    International Nuclear Information System (INIS)

    Kim, Young Min; Lee, Y. W.; Chang, J. H.

    2005-01-01

    IAEA-CRP-6 is a coordinated research program of IAEA on Advances in HTGR fuel technology. The CRP examines aspects of HTGR fuel technology, ranging from design and fabrication to characterization, irradiation testing, performance modeling, as well as licensing and quality control issues. The benchmark section of the program treats simple analytical cases, pyrocarbon layer behavior, single TRISO-coated fuel particle behavior, and benchmark calculations of some irradiation experiments performed and planned. There are totally seventeen benchmark cases in the program. Member countries are participating in the benchmark calculations of the CRP with their own developed fuel performance analysis computer codes. Korea is also taking part in the benchmark calculations using a fuel performance analysis code, COPA (COated PArticle), which is being developed in Korea Atomic Energy Research Institute. The study shows the calculational results of IAEACRP- 6 benchmark cases 1 through 7 which describe the structural behaviors for a single fuel particle

  3. Electron Microscopic Examination of Irradiated TRISO Coated Particles of Compact 6-3-2 of AGR-1 Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Van Rooyen, Isabella Johanna [Idaho National Lab. (INL), Idaho Falls, ID (United States); Demkowicz, Paul Andrew [Idaho National Lab. (INL), Idaho Falls, ID (United States); Riesterer, Jessica Lori [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, Brandon Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Janney, Dawn Elizabeth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Harp, Jason Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ploger, Scott Arden [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2012-12-01

    The electron microscopic examination of selected irradiated TRISO coated particles of the AGR-1 experiment of fuel compact 6-3-2 are presented in this report. Compact 6-3-2 refers to the compact in Capsule 6 at level 3 of Stack 2. The fuel used in capsule 6 compacts, are called the “baseline” fuel as it is fabricated with refined coating process conditions used to fabricate historic German fuel, because of its excellent irradiation performance with UO2 kernels. The AGR-1 fuel is however made of low-enriched uranium oxycarbide (UCO). Kernel diameters are approximately 350 µm with a U-235 enrichment of approximately 19.7%. Compact 6-3-2 has been irradiated to 11.3% FIMA compact average burn-up with a time average, volume average temperature of 1070.2°C and with a compact average fast fluence of 2.38E21 n/cm

  4. Performance of the gas turbine-modular helium reactor fuelled with different types of fertile TRISO particles

    International Nuclear Information System (INIS)

    Talamo, Alberto; Gudowski, Waclaw

    2005-01-01

    Preliminary studies have been performed on operation of the gas turbine-modular helium reactor (GT-MHR) with a thorium based fuel. The major options for a thorium fuel are a mixture with light water reactors spent fuel, mixture with military plutonium or with with fissile isotopes of uranium. Consequently, we assumed three models of the fuel containing a mixture of thorium with 239 Pu, 233 U or 235 U in TRISO particles with a different kernel radius keeping constant the packing fraction at the level of 37.5%, which corresponds to the current compacting process limit. In order to allow thorium to act as a breeder of fissile uranium and ensure conditions for a self-sustaining fission chain, the fresh fuel must contain a certain quantity of fissile isotope at beginning of life; we refer to the initial fissile nuclide as triggering isotope. The small capture cross-section of 232 Th in the thermal neutron energy range, compared to the fission one of the common fissile isotopes ( 239 Pu, 233 U and 235 U), requires a quantity of thorium 25-30 times greater than that one of the triggering isotope in order to equilibrate the reaction rates. At the same time, the amount of the triggering isotope must be enough to set the criticality condition of the reactor. These two conditions must be simultaneously satisfied. The necessity of a large mass of fuel forces to utilize TRISO particles with a large radius of the kernel, 300 μm. Moreover, in order to improve the neutron economics, a fuel cycle based on thorium requires a low capture to fission ratio of the triggering isotope. Amid the common fissile isotopes, 233 U, 235 U and 239 Pu, we have found that only the uranium nuclides have shown to have the suitable neutronic features to enable the GT-MHR to work on a fuel based on thorium

  5. Performance of the gas turbine-modular helium reactor fuelled with different types of fertile TRISO particles

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm (Sweden)]. E-mail: alby@neutron.kth.se; Gudowski, Waclaw [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm (Sweden)

    2005-11-15

    Preliminary studies have been performed on operation of the gas turbine-modular helium reactor (GT-MHR) with a thorium based fuel. The major options for a thorium fuel are a mixture with light water reactors spent fuel, mixture with military plutonium or with with fissile isotopes of uranium. Consequently, we assumed three models of the fuel containing a mixture of thorium with {sup 239}Pu, {sup 233}U or {sup 235}U in TRISO particles with a different kernel radius keeping constant the packing fraction at the level of 37.5%, which corresponds to the current compacting process limit. In order to allow thorium to act as a breeder of fissile uranium and ensure conditions for a self-sustaining fission chain, the fresh fuel must contain a certain quantity of fissile isotope at beginning of life; we refer to the initial fissile nuclide as triggering isotope. The small capture cross-section of {sup 232}Th in the thermal neutron energy range, compared to the fission one of the common fissile isotopes ({sup 239}Pu, {sup 233}U and {sup 235}U), requires a quantity of thorium 25-30 times greater than that one of the triggering isotope in order to equilibrate the reaction rates. At the same time, the amount of the triggering isotope must be enough to set the criticality condition of the reactor. These two conditions must be simultaneously satisfied. The necessity of a large mass of fuel forces to utilize TRISO particles with a large radius of the kernel, 300 {mu}m. Moreover, in order to improve the neutron economics, a fuel cycle based on thorium requires a low capture to fission ratio of the triggering isotope. Amid the common fissile isotopes, {sup 233}U, {sup 235}U and {sup 239}Pu, we have found that only the uranium nuclides have shown to have the suitable neutronic features to enable the GT-MHR to work on a fuel based on thorium.

  6. Heavy metals in atmospheric surrogate dry deposition

    Science.gov (United States)

    Morselli; Cecchini; Grandi; Iannuccilli; Barilli; Olivieri

    1999-02-01

    This paper describes a methodological approach for the assessment of the amount of surrogate dry deposition of several toxic heavy metals (Cd, Cr, Cu, Ni, Pb, V, Zn) associated with atmospheric particulate matter at ground level. The objectives of the study were twofold: i) the evaluation of several techniques for the digestion of dry deposition samples for trace metal analysis; ii) the comparison of the results from two samplers with different collecting surfaces. A dry solid surface sampler (DRY sampler, Andersen--USA) and a water layer surface sampler (DAS sampler--MTX Italy) were employed. The samples were collected over a one-year period in an urban site of Bologna (northern Italy). A description is given of the complete procedure, from sampling to data elaboration, including sample storage, digestion and analytical methods. According to the results obtained with three different digestion techniques (Teflon bomb, microwave digester and Teflon flask with vapour cooling system), the highest recovery rate was achieved by the Teflon bomb procedure employing an NBS 1648 Standard Reference Material; 90-95% of the elements considered were recovered by dissolution in a pressurized Teflon bomb with an HNO3-HF mixture. Given these results, the technique was adopted for dry deposition sample digestion. On the basis of the amount of heavy metals measured as monthly deposition fluxes (microg/m2), the collecting efficiency of the DAS sampler for a number of elements was found to be as much as two to three times greater than that of the DRY sampler.

  7. Surrogate Motherhood II: Reflections after "Baby M."

    Science.gov (United States)

    Schwartz, Lita Linzer

    1988-01-01

    Discusses the "Baby M" surrogate motherhood case which has produced heated debate in popular media, legal publications, and other professional journals. Summarizes arguments offered and reasoning behind actions of judiciary. (Author/ABL)

  8. Surrogate versus couple therapy in vaginismus.

    Science.gov (United States)

    Ben-Zion, Itzhak; Rothschild, Shelly; Chudakov, Bella; Aloni, Ronit

    2007-05-01

    Women who do not have a cooperative partner cannot complete the usual therapeutic process in the treatment of vaginismus, because they cannot progress to the stage of practicing the insertion of the man partner's fingers and the insertion of a penis. To compare traditional couple therapy with therapy utilizing a surrogate partner. The study was controlled and retrospective. Data were obtained from the treatment charts of patients who had come to the clinic for treatment of vaginismus. Sixteen vaginismus patients who were treated with a man surrogate partner were compared with 16 vaginismus patients who were treated with their own partners. Successful pain-free intercourse upon completion of therapy. One hundred percent of the surrogate patients succeeded in penile-vaginal intercourse compared with 75% in the couples group (P = 0.1). All surrogate patients ended the therapy because it was fully successful, compared with 69% in the couples group. Twelve percent of the couples group ended the therapy because it failed, and 19% because the couples decided to separate. Treating vaginismus with a man surrogate partner was at least as effective as couple therapy. Surrogate therapy may be considered for vaginismus patients who have no cooperative partner.

  9. Postirradiation examination report of TRISO and BISO coated ThO2 particles irradiated in capsules HT-31 and HT-33

    International Nuclear Information System (INIS)

    Sedlak, B.J.

    1980-01-01

    Capsules HT-31 and HT-33 were uninstrumented capsule experiments irradiated in the target position of the High-Flux Isotope Reactor at Oak Ridge National Laboratory. The experiments were used to evaluate the irradiation performance of (1) fuel fabricated in a 240-mm-diameter coater for production scale-up, (2) TRISO ThO 2 and BISO ThO 2 particles, and (3) fuel with certain OPyC variables. A total of 16 BISO particle samples and 32 TRISO particle samples were irradiated to fast neutron fluences ranging from 4.0 to 11.7 x 10 25 n/m 2 (E > 29 fJ)/sub HTGR/ and heavy metal burnups between 3.5% and 13.2% FIMA at temperatures from 1150 0 to 1530 0 C

  10. Recent progress in gasoline surrogate fuels

    KAUST Repository

    Sarathy, Mani

    2017-12-06

    Petroleum-derived gasoline is currently the most widely used fuel for transportation propulsion. The design and operation of gasoline fuels is governed by specific physical and chemical kinetic fuel properties. These must be thoroughly understood in order to improve sustainable gasoline fuel technologies in the face of economical, technological, and societal challenges. For this reason, surrogate mixtures are formulated to emulate the thermophysical, thermochemical, and chemical kinetic properties of the real fuel, so that fundamental experiments and predictive simulations can be conducted. Early studies on gasoline combustion typically adopted single component or binary mixtures (n-heptane/isooctane) as surrogates. However, the last decade has seen rapid progress in the formulation and utilization of ternary mixtures (n-heptane/isooctane/toluene), as well as multicomponent mixtures that span the entire carbon number range of gasoline fuels (C4–C10). The increased use of oxygenated fuels (ethanol, butanol, MTBE, etc.) as blending components/additives has also motivated studies on their addition to gasoline fuels. This comprehensive review presents the available experimental and chemical kinetic studies which have been performed to better understand the combustion properties of gasoline fuels and their surrogates. Focus is on the development and use of surrogate fuels that emulate real fuel properties governing the design and operation of engines. A detailed analysis is presented for the various classes of compounds used in formulating gasoline surrogate fuels, including n-paraffins, isoparaffins, olefins, naphthenes, and aromatics. Chemical kinetic models for individual molecules and mixtures of molecules to emulate gasoline surrogate fuels are presented. Despite the recent progress in gasoline surrogate fuel combustion research, there are still major gaps remaining; these are critically discussed, as well as their implications on fuel formulation and engine

  11. Recent progress in gasoline surrogate fuels

    KAUST Repository

    Sarathy, Mani; Farooq, Aamir; Kalghatgi, Gautam T.

    2017-01-01

    Petroleum-derived gasoline is currently the most widely used fuel for transportation propulsion. The design and operation of gasoline fuels is governed by specific physical and chemical kinetic fuel properties. These must be thoroughly understood in order to improve sustainable gasoline fuel technologies in the face of economical, technological, and societal challenges. For this reason, surrogate mixtures are formulated to emulate the thermophysical, thermochemical, and chemical kinetic properties of the real fuel, so that fundamental experiments and predictive simulations can be conducted. Early studies on gasoline combustion typically adopted single component or binary mixtures (n-heptane/isooctane) as surrogates. However, the last decade has seen rapid progress in the formulation and utilization of ternary mixtures (n-heptane/isooctane/toluene), as well as multicomponent mixtures that span the entire carbon number range of gasoline fuels (C4–C10). The increased use of oxygenated fuels (ethanol, butanol, MTBE, etc.) as blending components/additives has also motivated studies on their addition to gasoline fuels. This comprehensive review presents the available experimental and chemical kinetic studies which have been performed to better understand the combustion properties of gasoline fuels and their surrogates. Focus is on the development and use of surrogate fuels that emulate real fuel properties governing the design and operation of engines. A detailed analysis is presented for the various classes of compounds used in formulating gasoline surrogate fuels, including n-paraffins, isoparaffins, olefins, naphthenes, and aromatics. Chemical kinetic models for individual molecules and mixtures of molecules to emulate gasoline surrogate fuels are presented. Despite the recent progress in gasoline surrogate fuel combustion research, there are still major gaps remaining; these are critically discussed, as well as their implications on fuel formulation and engine

  12. The development of radioactive sample surrogates for training and exercises

    Energy Technology Data Exchange (ETDEWEB)

    Martha Finck; Bevin Brush; Dick Jansen; David Chamberlain; Don Dry; George Brooks; Margaret Goldberg

    2012-03-01

    The development of radioactive sample surrogates for training and exercises Source term information is required for to reconstruct a device used in a dispersed radiological dispersal device. Simulating a radioactive environment to train and exercise sampling and sample characterization methods with suitable sample materials is a continued challenge. The Idaho National Laboratory has developed and permitted a Radioactive Response Training Range (RRTR), an 800 acre test range that is approved for open air dispersal of activated KBr, for training first responders in the entry and exit from radioactively contaminated areas, and testing protocols for environmental sampling and field characterization. Members from the Department of Defense, Law Enforcement, and the Department of Energy participated in the first contamination exercise that was conducted at the RRTR in the July 2011. The range was contaminated using a short lived radioactive Br-82 isotope (activated KBr). Soil samples contaminated with KBr (dispersed as a solution) and glass particles containing activated potassium bromide that emulated dispersed radioactive materials (such as ceramic-based sealed source materials) were collected to assess environmental sampling and characterization techniques. This presentation summarizes the performance of a radioactive materials surrogate for use as a training aide for nuclear forensics.

  13. Surrogate formulations for thermal treatment of low-level mixed waste

    International Nuclear Information System (INIS)

    Stockdale, J.A.D.; Bostick, W.D.; Hoffmann, D.P.; Lee, H.T.

    1994-01-01

    The evaluation and comparison of proposed thermal treatment systems for mixed wastes can be expedited by tests in which the radioactive components of the wastes are replaced by surrogate materials chosen to mimic, as far as is possible, the chemical and physical properties of the radioactive materials of concern. In this work, sponsored by the Mixed Waste Integrated Project of the US Department of Energy, the authors have examined reported experience with such surrogates and suggest a simplified standard list of materials for use in tests of thermal treatment systems. The chief radioactive nuclides of concern in the treatment of mixed wastes are 239 Pu, 238 U, 235 U, 137 Cs, 103 Ru, 99 Tc, and 90 Sr. These nuclides are largely by-products of uranium enrichment, reactor fuel reprocessing, and weapons program activities. Cs, Ru, and Sr all have stable isotopes that can be used as perfect surrogates for the radioactive forms. Technetium exists only in radioactive form, as do plutonium and uranium. If one wishes to preclude radioactive contamination of the thermal treatment system under trial burn, surrogate elements must be chosen for these three. For technetium, the authors suggest the use of natural ruthenium, and for both plutonium and uranium, they recommend cerium. The seven radionuclides listed can therefore be simulated by a surrogate package containing stable isotopes of ruthenium, strontium, cesium, and cerium

  14. Attitudes toward surrogate motherhood in Canada.

    Science.gov (United States)

    Krishnan, V

    1994-01-01

    The issue of surrogate motherhood captured worldwide attention with the Baby M case in the United States. Some medical practitioners now claim that the surrogate arrangement may be the answer for certain women who are unable to conceive children naturally. Feminist activists are highly critical about the issue. In her landmark book The Mother Machine, Corea (1985) called surrogates "breeders," women whose bodies are being used by men. Lawyers and ethicists debate whether surrogacy is baby selling or not, and religious fundamentalists have condemned any form of procreation outside the "normal" or "natural" form of sexual relations within a marriage. But what do Canadian women think about commercial surrogacy? Findings pertaining to this issue from the latest national fertility survey of 5,315 women in the reproductive ages of 18-49 are reported.

  15. Legal regulation of surrogate motherhood in Israel.

    Science.gov (United States)

    Frenkel, D A

    2001-01-01

    The Israeli Law on surrogate motherhood demands a preconception agreement to include payments to be made to the surrogate mother. Surrogacy arrangements with family members are forbidden. Commercial surrogacy is allowed and encouraged. The Law causes many problems. Validity of consent given by surrogate mothers is doubtful. Possible future psychological harm are ignored. There is a danger of "commodification" of children. Abusing women of low socio-economic status as breeding machines may be another outcome. No clear responsibility is imposed on the "intended parents" for an impaired child. The law ignores possibility of divorce or death of the "intended parents" before the child's birth. Splitting motherhood is another social problem that has to be dealt with. So far the sperm of the husband from the "intended parents" has to be used, but further steps may follow. It is not certain that a policy of "positive eugenics" will not develop.

  16. An analysis of nuclear fuel burnup in the AGR-1 TRISO fuel experiment using gamma spectrometry, mass spectrometry, and computational simulation techniques

    International Nuclear Information System (INIS)

    Harp, Jason M.; Demkowicz, Paul A.; Winston, Philip L.; Sterbentz, James W.

    2014-01-01

    Highlights: • The burnup of irradiated AGR-1 TRISO fuel was analyzed using gamma spectrometry. • The burnup of irradiated AGR-1 TRISO fuel was also analyzed using mass spectrometry. • Agreement between experimental results and neutron physics simulations was excellent. - Abstract: AGR-1 was the first in a series of experiments designed to test US TRISO fuel under high temperature gas-cooled reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post-irradiation examination (PIE) at INL and Oak Ridge National Laboratory. One component of the AGR-1 PIE is the experimental evaluation of the burnup of the fuel by two separate techniques. Gamma spectrometry was used to non-destructively evaluate the burnup of all 72 of the TRISO fuel compacts that comprised the AGR-1 experiment. Two methods for evaluating burnup by gamma spectrometry were developed, one based on the Cs-137 activity and the other based on the ratio of Cs-134 and Cs-137 activities. Burnup values determined from both methods compared well with the values predicted from simulations. The highest measured burnup was 20.1% FIMA (fissions per initial heavy metal atom) for the direct method and 20.0% FIMA for the ratio method (compared to 19.56% FIMA from simulations). An advantage of the ratio method is that the burnup of the cylindrical fuel compacts can be determined in small (2.5 mm) axial increments and an axial burnup profile can be produced. Destructive chemical analysis by inductively coupled mass spectrometry (ICP-MS) was then performed on selected compacts that were representative of the expected range of fuel burnups in the experiment to compare with the burnup values determined by gamma spectrometry. The compacts analyzed by mass spectrometry had a burnup range of 19.3% FIMA to 10.7% FIMA. The mass spectrometry evaluation of burnup for the four compacts agreed well with the gamma

  17. Reduced cost mission design using surrogate models

    Science.gov (United States)

    Feldhacker, Juliana D.; Jones, Brandon A.; Doostan, Alireza; Hampton, Jerrad

    2016-01-01

    This paper uses surrogate models to reduce the computational cost associated with spacecraft mission design in three-body dynamical systems. Sampling-based least squares regression is used to project the system response onto a set of orthogonal bases, providing a representation of the ΔV required for rendezvous as a reduced-order surrogate model. Models are presented for mid-field rendezvous of spacecraft in orbits in the Earth-Moon circular restricted three-body problem, including a halo orbit about the Earth-Moon L2 libration point (EML-2) and a distant retrograde orbit (DRO) about the Moon. In each case, the initial position of the spacecraft, the time of flight, and the separation between the chaser and the target vehicles are all considered as design inputs. The results show that sample sizes on the order of 102 are sufficient to produce accurate surrogates, with RMS errors reaching 0.2 m/s for the halo orbit and falling below 0.01 m/s for the DRO. A single function call to the resulting surrogate is up to two orders of magnitude faster than computing the same solution using full fidelity propagators. The expansion coefficients solved for in the surrogates are then used to conduct a global sensitivity analysis of the ΔV on each of the input parameters, which identifies the separation between the spacecraft as the primary contributor to the ΔV cost. Finally, the models are demonstrated to be useful for cheap evaluation of the cost function in constrained optimization problems seeking to minimize the ΔV required for rendezvous. These surrogate models show significant advantages for mission design in three-body systems, in terms of both computational cost and capabilities, over traditional Monte Carlo methods.

  18. SILICON CARBIDE GRAIN BOUNDARY DISTRIBUTIONS, IRRADIATION CONDITIONS, AND SILVER RETENTION IN IRRADIATED AGR-1 TRISO FUEL PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Lillo, T. M.; Rooyen, I. J.; Aguiar, J. A.

    2016-11-01

    Precession electron diffraction in the transmission electron microscope was used to map grain orientation and ultimately determine grain boundary misorientation angle distributions, relative fractions of grain boundary types (random high angle, low angle or coincident site lattice (CSL)-related boundaries) and the distributions of CSL-related grain boundaries in the SiC layer of irradiated TRISO-coated fuel particles. Two particles from the AGR-1 experiment exhibiting high Ag-110m retention (>80%) were compared to a particle exhibiting low Ag-110m retention (<19%). Irradiated particles with high Ag-110m retention exhibited a lower fraction of random, high angle grain boundaries compared to the low Ag-110m retention particle. An inverse relationship between the random, high angle grain boundary fraction and Ag-110m retention is found and is consistent with grain boundary percolation theory. Also, comparison of the grain boundary distributions with previously reported unirradiated grain boundary distributions, based on SEM-based EBSD for similarly fabricated particles, showed only small differences, i.e. a greater low angle grain boundary fraction in unirradiated SiC. It was, thus, concluded that SiC layers with grain boundary distributions susceptible to Ag-110m release were present prior to irradiation. Finally, irradiation parameters were found to have little effect on the association of fission product precipitates with specific grain boundary types.

  19. Fission product retention in TRISO coated UO2 particle fuels subjected to HTR simulated core heating tests

    International Nuclear Information System (INIS)

    Baldwin, C.A.; Kania, M.J.

    1991-01-01

    Results of the examination and analysis of 25,730 individual microspheres from spherical fuel elements HFR-K3/1 and HFR-K3/3 are reported. The parent spheres were irradiated in excess of end-of-life exposure and subsequently subjected to simulated core heating tests in a special high-temperature furnace at Forschungszentrum, Juelich, GmbH (KFA). Following the heating tests, the spheres were electrolytically deconsolidated to obtain unbounded fuel particles for Irradiated Microsphere Gamma Analyzer (IMGA) analysis. For sphere HFR-K3/1, which was heated for 500 h at 1600 deg. C, only four particles were identified as having released fission products. The remaining particles from the sphere showed no statistical evidence of fission product release. Scanning Electron Microscopy (SEM) examination showed that three of the defect particles had large sections of the TRISO coating missing, while the fourth appeared normal. For sphere HFR-K3/3, which was heated for 100 h at 1800 deg. C, the IMGA data revealed that fission product release (cesium) from individual particles was significant and that there was large particle-to-particle variation in retention capabilities. Individual particle release (cesium) averaged ten times the KFA-measured integral spherical fuel element release value. In addition, the bimodal distribution of the individual particle data indicated that two distinct modes of failure at fuel temperatures of 1800 deg. C and above may exist. (author). 6 refs, 6 figs, 4 tabs

  20. Electron Microscopic Examination of Irradiated TRISO Coated Particles of Compact 6-3-2 of AGR-1 Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Van Rooyen, Isabella Johanna [Idaho National Lab. (INL), Idaho Falls, ID (United States); Demkowicz, Paul Andrew [Idaho National Lab. (INL), Idaho Falls, ID (United States); Riesterer, Jessica Lori [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, Brandon Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Janney, Dawn Elizabeth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Harp, Jason Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ploger, Scott Arden [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2012-12-01

    The electron microscopic examination of selected irradiated TRISO coated particles of the AGR-1 experiment of fuel compact 6-3-2 are presented in this report. Compact 6-3-2 refers to the compact in Capsule 6 at level 3 of Stack 2. The fuel used in capsule 6 compacts, are called the “baseline” fuel as it is fabricated with refined coating process conditions used to fabricate historic German fuel, because of its excellent irradiation performance with UO2 kernels. The AGR-1 fuel is however made of low-enriched uranium oxycarbide (UCO). Kernel diameters are approximately 350 µm with a U-235 enrichment of approximately 19.7%. Compact 6-3-2 has been irradiated to 11.3% FIMA compact average burn-up with a time average, volume average temperature of 1070.2°C and with a compact average fast fluence of 2.38E21 n/cm

  1. Ethical Problems Related to Surrogate Motherhood

    Directory of Open Access Journals (Sweden)

    Erdem Aydin

    2006-03-01

    Full Text Available Being unable to have children is an important problem for married couples. At present, new reproduction techniques help these couples while those who can not find any solution try new approaches. One of these is the phenomenon of surrogate motherhood, which is based upon an agreement between the infertile couple and surrogate mother. Surrogate mother may conceive with the sperm of the male of the involved couple as well as by the transfer of the embryo formed by invitro fertilization. Couples who choose to have a child born from a pregnancy or to whom they are genetically partially connected rather than adopting a child give rise to the emergence of some ethical problems. Traditional family notion based upon having children after the union of the reproductive cells of the mother and father do not receive the pheneomenon of surrogate mother favourably. Such practices are criticised as they are far from being natural and other ethical problems are faced in the implementation.

  2. Combustion Kinetic Studies of Gasolines and Surrogates

    KAUST Repository

    Javed, Tamour

    2016-01-01

    . These measurements were performed in shock tubes and rapid compression machines over a wide range of experimental conditions (650 – 1250 K, 10 – 40 bar) relevant to internal combustion engines. Using the measured the data and chemical kinetic analyses, the surrogate

  3. Active Subspaces for Wind Plant Surrogate Modeling

    Energy Technology Data Exchange (ETDEWEB)

    King, Ryan N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Adcock, Christiane [Massachusetts Institute of Technology

    2018-01-12

    Understanding the uncertainty in wind plant performance is crucial to their cost-effective design and operation. However, conventional approaches to uncertainty quantification (UQ), such as Monte Carlo techniques or surrogate modeling, are often computationally intractable for utility-scale wind plants because of poor congergence rates or the curse of dimensionality. In this paper we demonstrate that wind plant power uncertainty can be well represented with a low-dimensional active subspace, thereby achieving a significant reduction in the dimension of the surrogate modeling problem. We apply the active sub-spaces technique to UQ of plant power output with respect to uncertainty in turbine axial induction factors, and find a single active subspace direction dominates the sensitivity in power output. When this single active subspace direction is used to construct a quadratic surrogate model, the number of model unknowns can be reduced by up to 3 orders of magnitude without compromising performance on unseen test data. We conclude that the dimension reduction achieved with active subspaces makes surrogate-based UQ approaches tractable for utility-scale wind plants.

  4. Combustion Kinetic Studies of Gasolines and Surrogates

    KAUST Repository

    Javed, Tamour

    2016-11-01

    Future thrusts for gasoline engine development can be broadly summarized into two categories: (i) efficiency improvements in conventional spark ignition engines, and (ii) development of advance compression ignition (ACI) concepts. Efficiency improvements in conventional spark ignition engines requires downsizing (and turbocharging) which may be achieved by using high octane gasolines, whereas, low octane gasolines fuels are anticipated for ACI concepts. The current work provides the essential combustion kinetic data, targeting both thrusts, that is needed to develop high fidelity gasoline surrogate mechanisms and surrogate complexity guidelines. Ignition delay times of a wide range of certified gasolines and surrogates are reported here. These measurements were performed in shock tubes and rapid compression machines over a wide range of experimental conditions (650 – 1250 K, 10 – 40 bar) relevant to internal combustion engines. Using the measured the data and chemical kinetic analyses, the surrogate complexity requirements for these gasolines in homogeneous environments are specified. For the discussions presented here, gasolines are classified into three categories: (i)\\tLow octane gasolines including Saudi Aramco’s light naphtha fuel (anti-knock index, AKI = (RON + MON)/2 = 64; Sensitivity (S) = RON – MON = 1), certified FACE (Fuels for Advanced Combustion Engines) gasoline I and J (AKI ~ 70, S = 0.7 and 3 respectively), and their Primary Reference Fuels (PRF, mixtures of n-heptane and iso-octane) and multi-component surrogates. (ii)\\t Mid octane gasolines including FACE A and C (AKI ~ 84, S ~ 0 and 1 respectively) and their PRF surrogates. Laser absorption measurements of intermediate and product species formed during gasoline/surrogate oxidation are also reported. (iii)\\t A wide range of n-heptane/iso-octane/toluene (TPRF) blends to adequately represent the octane and sensitivity requirements of high octane gasolines including FACE gasoline F and G

  5. A novel surrogate index for hepatic insulin resistance.

    LENUS (Irish Health Repository)

    Vangipurapu, J

    2011-03-01

    In epidemiological and genetic studies surrogate indices are needed to investigate insulin resistance in different insulin-sensitive tissues. Our objective was to develop a surrogate index for hepatic insulin resistance.

  6. Surrogate losses: Understandings of pregnancy loss and assisted reproduction among surrogate mothers.

    Science.gov (United States)

    Berend, Zsuzsa

    2010-06-01

    I explore surrogate mothers' narrative construction of pregnancy loss on surrogacy support websites. Communicating via the Internet, women construct the public online world of surrogacy. Drawing on anthropological and sociological literature I investigate the connections between conceptualizations of loss and understandings of technological practices and the consequences of these understandings for assisted reproduction. Surrogate mothers define loss broadly, ranging from failure to conceive to miscarriage and stillbirth; loss means the failure to give a baby to the intended parents. Assisted reproductive technologies contribute to loss by raising expectations of success, by attempting to maximize results through the transfer of multiple fertilized ova, and by early monitoring and testing. However, surrogates collectively understand technology as a positive force and advocate for reproductive technology. Surrogates' resolve to "give the gift of life" makes them vulnerable to failure and loss, yet also informs repeated efforts to bear children for others with technological assistance.

  7. Permanent pixels : Building blocks for the longevity of digital surrogates of historical photographs

    NARCIS (Netherlands)

    Van Horik, M.P.M.

    2005-01-01

    Within the context of long-term access to digital objects in general this dissertation takes the longevity of digital surrogates of historical photographs into consideration. For memory institutes digitisation of analogue source material, such as historical photographs, is an exciting way to open up

  8. System Reliability Analysis Capability and Surrogate Model Application in RAVEN

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Huang, Dongli [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gleicher, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Bei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adbel-Khalik, Hany S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pascucci, Valerio [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-11-01

    This report collect the effort performed to improve the reliability analysis capabilities of the RAVEN code and explore new opportunity in the usage of surrogate model by extending the current RAVEN capabilities to multi physics surrogate models and construction of surrogate models for high dimensionality fields.

  9. Fission-product behaviour in irradiated TRISO-coated particles: Results of the HFR-EU1bis experiment and their interpretation

    International Nuclear Information System (INIS)

    Barrachin, M.; Dubourg, R.; Groot, S. de; Kissane, M.P.; Bakker, K.

    2011-01-01

    Highlights: → The microstructure and FPs in UO 2 TRISO particles (10% FIMA, 1573 K) were studied. → Very large porosities (>10 μm) were observed in the high temperature particles. → Significant Xe and Cs releases from the kernel were observed. → Mo and Ru are mainly present in the metallic precipitates in the kernel. - Abstract: It is important to understand fission-product (FP) and kernel micro-structure evolution in TRISO-coated fuel particles. FP behaviour, while central to severe-accident evaluation, impacts: evolution of the kernel oxygen potential governing in turn carbon oxidation (amoeba effect and pressurization); particle pressurization through fission-gas release from the kernel; and coating mechanical resistance via reaction with some FPs (Pd, Cs, Sr). The HFR-Eu1bis experiment irradiated five HTR fuel pebbles containing TRISO-coated UO 2 particles and went beyond current HTR specifications (e.g., central temperature of 1523 K). This study presents ceramographic and EPMA examinations of irradiated urania kernels and coatings. Significant evolutions of the kernel (grain structure, porosity, metallic-inclusion size, intergranular bubbles) as a function of temperature are shown. Results concerning FP migration are presented, e.g., significant xenon, caesium and palladium release from the kernel, molybdenum and ruthenium mainly present in metallic precipitates. The observed FP and micro-structural evolutions are interpreted and explanations proposed. The effect of high flux rate and high temperature on fission-gas behaviour, grain-size evolution and kernel swelling is discussed. Furthermore, Cs, Mo and Zr behaviour is interpreted in connection with oxygen-potential. This paper shows that combining state-of-the-art post-irradiation examination and state-of-the-art modelling fundamentally improves understanding of HTR fuel behaviour.

  10. Influence of temperature on the micro-and nano-structures of experimental PBMR TRISO coated particles: A comparative study - HTR2008-58189

    International Nuclear Information System (INIS)

    Van Rooyen, I. J.; Neethling, J. H.; Mahlangu, J.

    2008-01-01

    The PBMR fuel consists of TRISO Coated Particles (CPs) in a graphite matrix. The three layer system, IPyC-SIC-OPyC, forms the primary barrier to fission product release, with the SiC layer acting as the main pressure boundary of the particle. The containment of fission products inside the CPs is however a function of the operating temperature and microstructure of the SiC layer. During accident conditions, the CPs will reach higher temperatures than normal operating conditions. The Fuel Design Dept. of PBMR is therefore investigating various characteristics of the SiC layer, especially nano characteristics at variant conditions. The integrity of the interface between the SiC and Inner PyC layers is also important for fission product retention and therefore interesting TEM images of this region of the experimental PBMR TRISO particles will be shown. Transmission electron microscope (TEM) images of the microstructure of TRISO coated particles of three different experimental batches after annealing will be discussed. Particles annealed at 1980 deg. C for 1 hour revealed that the inner PyC layer de-bonded from the SiC layer. Changes observed in the diffraction rings are evidence that the PyC structure is becoming organized or anisotropic. The SiC layer, on the other hand, did not show any changes as a result of annealing. Only the cubic 3C-SiC phase was observed for a limited number of grains analyzed. The nano hardness and elasticity measurements of the three test batches were done using a CSM Nano Hardness Tester. These results are compared to indicate possible differences between the 1 hour and 5 hour annealing time as a function of annealing temperature from 1000 deg. C to 1980 deg. C. The variation of hardness and elasticity as a function of temperature for the three experimental batches are identified and discussed. This preliminary TEM investigation and nano hardness measurements have contributed new knowledge about the effect of high temperature annealing on

  11. Effect of high temperature annealing on the grain size of CVD-grown SiC and experimental PBMR TRISO coated particles

    CSIR Research Space (South Africa)

    Mokoduwe, SM

    2010-10-01

    Full Text Available in the PBMR fuel SiC layer. square samples were cut from the original sample received from ORNL and prepared for grain size Prague, Czech Republic, October 18 – 2000 °C. These no significant ion of how the 8] also ge is also of tal THODS -Si... for grain size determination Fig. 5: Influence of high temperature annealing on the CVD ORNL polycrystalline 3 C-SiC. Fig. 6: Influence of high temperature annealing on the polycrystalline 3 C-SiC layer of PBMR TRISO CP batches D and E...

  12. Surrogate decision making and intellectual virtue.

    Science.gov (United States)

    Bock, Gregory L

    2014-01-01

    Patients can be harmed by a religiously motivated surrogate decision maker whose decisions are contrary to the standard of care; therefore, surrogate decision making should be held to a high standard. Stewart Eskew and Christopher Meyers proposed a two-part rule for deciding which religiously based decisions to honor: (1) a secular reason condition and (2) a rationality condition. The second condition is based on a coherence theory of rationality, which they claim is accessible, generous, and culturally sensitive. In this article, I will propose strengthening the rationality condition by grounding it in a theory of intellectual virtue, which is both rigorous and culturally sensitive. Copyright 2014 The Journal of Clinical Ethics. All rights reserved.

  13. Self- and surrogate-reported communication functioning in aphasia.

    Science.gov (United States)

    Doyle, Patrick J; Hula, William D; Austermann Hula, Shannon N; Stone, Clement A; Wambaugh, Julie L; Ross, Katherine B; Schumacher, James G

    2013-06-01

    To evaluate the dimensionality and measurement invariance of the aphasia communication outcome measure (ACOM), a self- and surrogate-reported measure of communicative functioning in aphasia. Responses to a large pool of items describing communication activities were collected from 133 community-dwelling persons with aphasia of ≥ 1 month post-onset and their associated surrogate respondents. These responses were evaluated using confirmatory and exploratory factor analysis. Chi-square difference tests of nested factor models were used to evaluate patient-surrogate measurement invariance and the equality of factor score means and variances. Association and agreement between self- and surrogate reports were examined using correlation and scatterplots of pairwise patient-surrogate differences. Three single-factor scales (Talking, Comprehension, and Writing) approximating patient-surrogate measurement invariance were identified. The variance of patient-reported scores on the Talking and Writing scales was higher than surrogate-reported variances on these scales. Correlations between self- and surrogate reports were moderate-to-strong, but there were significant disagreements in a substantial number of individual cases. Despite minimal bias and relatively strong association, surrogate reports of communicative functioning in aphasia are not reliable substitutes for self-reports by persons with aphasia. Furthermore, although measurement invariance is necessary for direct comparison of self- and surrogate reports, the costs of obtaining invariance in terms of scale reliability and content validity may be substantial. Development of non-invariant self- and surrogate report scales may be preferable for some applications.

  14. Surrogate end points in clinical research: hazardous to your health.

    Science.gov (United States)

    Grimes, David A; Schulz, Kenneth F

    2005-05-01

    Surrogate end points in clinical research pose real danger. A surrogate end point is an outcome measure, commonly a laboratory test, that substitutes for a clinical event of true importance. Resistance to activated protein C, for example, has been used as a surrogate for venous thrombosis in women using oral contraceptives. Other examples of inappropriate surrogate end points in contraception include the postcoital test instead of pregnancy to evaluate new spermicides, breakage and slippage instead of pregnancy to evaluate condoms, and bone mineral density instead of fracture to assess the safety of depo-medroxyprogesterone acetate. None of these markers captures the effect of the treatment on the true outcome. A valid surrogate end point must both correlate with and accurately predict the outcome of interest. Although many surrogate markers correlate with an outcome, few have been shown to capture the effect of a treatment (for example, oral contraceptives) on the outcome (venous thrombosis). As a result, thousands of useless and misleading reports on surrogate end points litter the medical literature. New drugs have been shown to benefit a surrogate marker, but, paradoxically, triple the risk of death. Thousands of patients have died needlessly because of reliance on invalid surrogate markers. Researchers should avoid surrogate end points unless they have been validated; that requires at least one well done trial using both the surrogate and true outcome. The clinical maxim that "a difference to be a difference must make a difference" applies to research as well. Clinical research should focus on outcomes that matter.

  15. Production of Depleted UO2Kernels for the Advanced Gas-Cooled Reactor Program for Use in TRISO Coating Development

    International Nuclear Information System (INIS)

    Collins, J.L.

    2004-01-01

    The main objective of the Depleted UO 2 Kernels Production Task at Oak Ridge National Laboratory (ORNL) was to conduct two small-scale production campaigns to produce 2 kg of UO 2 kernels with diameters of 500 ± 20 (micro)m and 3.5 kg of UO 2 kernels with diameters of 350 ± 10 (micro)m for the U.S. Department of Energy Advanced Fuel Cycle Initiative Program. The final acceptance requirements for the UO 2 kernels are provided in the first section of this report. The kernels were prepared for use by the ORNL Metals and Ceramics Division in a development study to perfect the triisotropic (TRISO) coating process. It was important that the kernels be strong and near theoretical density, with excellent sphericity, minimal surface roughness, and no cracking. This report gives a detailed description of the production efforts and results as well as an in-depth description of the internal gelation process and its chemistry. It describes the laboratory-scale gel-forming apparatus, optimum broth formulation and operating conditions, preparation of the acid-deficient uranyl nitrate stock solution, the system used to provide uniform broth droplet formation and control, and the process of calcining and sintering UO 3 · 2H 2 O microspheres to form dense UO 2 kernels. The report also describes improvements and best past practices for uranium kernel formation via the internal gelation process, which utilizes hexamethylenetetramine and urea. Improvements were made in broth formulation and broth droplet formation and control that made it possible in many of the runs in the campaign to produce the desired 350 ± 10-(micro)m-diameter kernels, and to obtain very high yields

  16. [Biomedical Perspective of the Surrogate Motherhood].

    Science.gov (United States)

    Jouve de la Barreda, Nicolás

    2017-01-01

    The subrogated motherhood takes place when an embryo created by in vitro fertilization (IVF) technology is implanted in a surrogate, sometimes called a gestational mother, by means a contract with her. It can imply to natural families (woman and man) with or without infertility problems, or to monoparental or biparental families of the same sex. Concerning the origin of the gametes used in the IVF emerges different implications on the genetic relationship of the resulting child with the surrogate and the future parents. The subrogated motherhood was initially considered an option to solve infertility problems. Nevertheless this practice has become a possible and attractive option as a source of economic resources for poor women. The cases of benefit of a pregnancy without mediating a contract are exceptional and they are not properly cases of ″subrogated maternity″ but of ″altruistic maternity″ and must be considered as heterologous in vitro fertilization. In this article are analyzed the medical, genetic and bioethics aspects of this new derivation of the fertilization in vitro. As points of special attention are considered the following questions: Is it the surrogate motherhood used preferably to solve infertility problems? Is not this actually a new form of exploitation of the woman? Does not suppose an attack to the natural family? Does not suppose in addition an attack to the dignity of the human being?

  17. Advanced electron microscopic techniques applied to the characterization of irradiation effects and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Lillo, T.M.; Trowbridge, T.L.; Madden, J.M.; Wu, Y.Q.; Goran, D.

    2013-01-01

    Preliminary electron microscopy of coated fuel particles from the AGR-1 experiment was conducted using characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). Microscopic quantification of fission-product precipitates was performed. Although numerous micro- and nano-sized precipitates observed in the coating layers during initial SEM characterization of the cross-sections, and in subsequent TEM diffraction patterns, were indexed as UPd 2 Si 2 , no Ag was conclusively found. Additionally, characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates in the presence of significantly higher concentrations of Pd and U. The electron microscopy team followed a multi-directional and phased approach in the identification of fission products in irradiated TRISO fuel. The advanced electron microscopy techniques discussed in this paper, not only demonstrate the usefulness of the equipment (methods) as relevant research tools, but also provide relevant scientific results which increase the knowledge about TRISO fuel particles microstructure and fission products transport

  18. Distribution of the grain limit character in SiC and its effect on the diffusion of fission products in the TRISO fuel particles

    International Nuclear Information System (INIS)

    Cancino T, F.; Lopez H, E.

    2017-09-01

    At present is accepted that silver diffuses through silicium carbide (SiC) by diffusion in grain boundaries, although little is known about the characteristics of grain boundaries in SiC, and how these change depending on the type of sample. In this work, was observed that there are small but important differences between the SiC in the tri-structural isotropic (TRISO) particles and that of the monoliths, which could explain some of the differences observed in experiments on diffusion in the literature. Five different types (coatings and monoliths) of SiC produced by chemical vapor deposition (CVD) were characterized by electron backscatter diffraction (EBSD). In all the samples the SiC was mainly composed of high-angle grain boundaries (∼ 65%), with a small fraction of grain boundaries of low-angle (about 15%) and 20% of the coincidence site lattice (CSL). The morphology of the monoliths is constituted by large grains, surrounded by smaller grains; in the particles of the TRISO fuel, both columnar and equi axial grains were observed, with a more uniform distribution over the surface of the coating. (Author)

  19. Development of parietal bone surrogates for parietal graft lift training

    Directory of Open Access Journals (Sweden)

    Hollensteiner Marianne

    2016-09-01

    Full Text Available Currently the surgical training of parietal bone graft techniques is performed on patients or specimens. Commercially available bone models do not deliver realistic haptic feedback. Thus customized parietal skull surrogates were developed for surgical training purposes. Two human parietal bones were used as reference. Based on the measurement of insertion forces of drilling, milling and saw procedures suitable material compositions for molding cortical and cancellous calvarial layers were found. Artificial skull caps were manufactured and tested. Additionally microtomograpy images of human and artificial parietal bones were performed to analyze outer table and diploe thicknesses. Significant differences between human and artificial skulls were not detected with the mechanical procedures tested. Highly significant differences were found for the diploe thickness values. In conclusion, an artificial bone has been created, mimicking the properties of human parietal bone thus being suitable for tabula externa graft lift training.

  20. Fission product behaviour - in particular Cs-137 - in HTR-TRISO-coated particle fuel

    International Nuclear Information System (INIS)

    Allelein, H.J.

    1980-12-01

    This work is performed between 1977 and 1979. The main task is to determine a temperature dependent diffusion coefficient of the fission product Cs-137 in the silicon carbide interlayer of HTR particles. The raw material is laso presented as the used measuring techniques and computer codes. The results are discussed in detail and some critical remarks are made about the efficiency of the silicon carbide interlayer to retent fission products including Ag-110m, Sr-90, and Ru-106, which temperature dependent diffusion coefficient is also been determined. (orig.) [de

  1. High-resolution computed tomography of the chest in children with cystic fibrosis: support for use as an outcome surrogate

    Energy Technology Data Exchange (ETDEWEB)

    Brody, A.S. [Departments of Radiology and Pediatrics, Children`s Hospital Medical Center, Cincinnati, OH (United States)]|[University of Cincinnati School of Medicine, Children`s Hospital Medical Center, Cincinnati, OH (United States)]|[Department of Radiology, Cincinnati, OH (United States); Molina, P.L. [Department of Radiology, University of North Carolina at Chapel Hill, North Carolina (United States); Klein, J.S. [Department of Radiology, University of Vermont, Burlington, Vermont (United States); Rothman, B.S. [University of Cincinnati School of Medicine, Children`s Hospital Medical Center, Cincinnati, OH (United States); Ramagopal, M.; Swartz, D.R. [Department of Pediatrics, University of Vermont, Burlington, Vermont (United States)

    1999-10-01

    Background. Outcome surrogates are indicators that reflect, rather than directly measure, patient benefit. In order to provide useful results, however, outcome surrogates must be carefully chosen and must meet specific criteria. Objective. To support development of high-resolution computed tomography (HRCT) as an outcome surrogate in cystic fibrosis (CF) by demonstrating the ability of HRCT to show short-term improvement in the appearance of the lungs in children with CF. Materials and methods. HRCT was performed at admission and after discharge on 8 children during 15 admissions for acute pulmonary exacerbation of CF. Three radiologists scored each study separately, then compared admission and discharge pairs. Results. HRCT scores improved in 13/15 admissions. Mean score decreased from 25 to 22. The decrease was significant (P = 0.014). Comparison of admission and discharge scans showed improvement in peribronchial thickening (P = 0.007), mucous plugging (P = 0.002), and overall appearance (P = 0.025). Conclusion. HRCT has the potential to be a useful outcome surrogate in CF. A necessary attribute of an outcome surrogate is that it improves rapidly with effective therapy. Despite widespread belief among radiologists and pulmonologists that HRCT meets this criterion, no previous report has demonstrated this ability in children. These findings support further development of HRCT as an outcome surrogate in children with CF. (orig.) With 2 figs., 2 tabs., 18 refs.

  2. High-resolution computed tomography of the chest in children with cystic fibrosis: support for use as an outcome surrogate

    International Nuclear Information System (INIS)

    Brody, A.S.; Molina, P.L.; Klein, J.S.; Rothman, B.S.; Ramagopal, M.; Swartz, D.R.

    1999-01-01

    Background. Outcome surrogates are indicators that reflect, rather than directly measure, patient benefit. In order to provide useful results, however, outcome surrogates must be carefully chosen and must meet specific criteria. Objective. To support development of high-resolution computed tomography (HRCT) as an outcome surrogate in cystic fibrosis (CF) by demonstrating the ability of HRCT to show short-term improvement in the appearance of the lungs in children with CF. Materials and methods. HRCT was performed at admission and after discharge on 8 children during 15 admissions for acute pulmonary exacerbation of CF. Three radiologists scored each study separately, then compared admission and discharge pairs. Results. HRCT scores improved in 13/15 admissions. Mean score decreased from 25 to 22. The decrease was significant (P = 0.014). Comparison of admission and discharge scans showed improvement in peribronchial thickening (P = 0.007), mucous plugging (P = 0.002), and overall appearance (P = 0.025). Conclusion. HRCT has the potential to be a useful outcome surrogate in CF. A necessary attribute of an outcome surrogate is that it improves rapidly with effective therapy. Despite widespread belief among radiologists and pulmonologists that HRCT meets this criterion, no previous report has demonstrated this ability in children. These findings support further development of HRCT as an outcome surrogate in children with CF. (orig.)

  3. Surrogate pregnancy: a guide for Canadian prenatal health care providers

    OpenAIRE

    Reilly, Dan R.

    2007-01-01

    Providing health care for a woman with a surrogate pregnancy involves unique challenges. Although the ethical debate surrounding surrogacy continues, Canada has banned commercial, but not altruistic, surrogacy. In the event of a custody dispute between a surrogate mother and the individual(s) intending to parent the child, it is unclear how Canadian courts would rule. The prenatal health care provider must take extra care to protect the autonomy and privacy rights of the surrogate. There is l...

  4. The development of radioactive sample surrogates for training and exercises

    International Nuclear Information System (INIS)

    Kevin Carney; Martha Finck; Christopher McGrath; Bevin Brush; Dick Jansen; Donald Dry; George Brooks; David Chamberlain

    2013-01-01

    Source term information is required for to reconstruct a device used in a dispersed radiological dispersal device. Simulating a radioactive environment to train and exercise sampling and sample characterization methods with suitable sample materials is a continued challenge. The Idaho National Laboratory has developed and permitted a radioactive response training range (RRTR), an 800 acre test range that is approved for open air dispersal of activated KBr, for training first responders in the entry and exit from radioactively contaminated areas, and testing protocols for environmental sampling and field characterization. Members from the Department of Defense, Law Enforcement, and the Department of Energy participated in the first contamination exercise that was conducted at the RRTR in the July 2011. The range was contaminated using a short lived radioactive 82 Br isotope (activated KBr). Soil samples contaminated with KBr (dispersed as a solution) and glass particles containing activated potassium bromide that emulated dispersed radioactive materials (such as ceramic-based sealed source materials) were collected to assess environmental sampling and characterization techniques. This presentation summarizes the performance of a radioactive materials surrogate for use as a training aide for nuclear forensics. (author)

  5. Airfoil Shape Optimization based on Surrogate Model

    Science.gov (United States)

    Mukesh, R.; Lingadurai, K.; Selvakumar, U.

    2018-02-01

    Engineering design problems always require enormous amount of real-time experiments and computational simulations in order to assess and ensure the design objectives of the problems subject to various constraints. In most of the cases, the computational resources and time required per simulation are large. In certain cases like sensitivity analysis, design optimisation etc where thousands and millions of simulations have to be carried out, it leads to have a life time of difficulty for designers. Nowadays approximation models, otherwise called as surrogate models (SM), are more widely employed in order to reduce the requirement of computational resources and time in analysing various engineering systems. Various approaches such as Kriging, neural networks, polynomials, Gaussian processes etc are used to construct the approximation models. The primary intention of this work is to employ the k-fold cross validation approach to study and evaluate the influence of various theoretical variogram models on the accuracy of the surrogate model construction. Ordinary Kriging and design of experiments (DOE) approaches are used to construct the SMs by approximating panel and viscous solution algorithms which are primarily used to solve the flow around airfoils and aircraft wings. The method of coupling the SMs with a suitable optimisation scheme to carryout an aerodynamic design optimisation process for airfoil shapes is also discussed.

  6. Environmental and geographic variables are effective surrogates for genetic variation in conservation planning.

    Science.gov (United States)

    Hanson, Jeffrey O; Rhodes, Jonathan R; Riginos, Cynthia; Fuller, Richard A

    2017-11-28

    Protected areas buffer species from anthropogenic threats and provide places for the processes that generate and maintain biodiversity to continue. However, genetic variation, the raw material for evolution, is difficult to capture in conservation planning, not least because genetic data require considerable resources to obtain and analyze. Here we show that freely available environmental and geographic distance variables can be highly effective surrogates in conservation planning for representing adaptive and neutral intraspecific genetic variation. We obtained occurrence and genetic data from the IntraBioDiv project for 27 plant species collected over the European Alps using a gridded sampling scheme. For each species, we identified loci that were potentially under selection using outlier loci methods, and mapped their main gradients of adaptive and neutral genetic variation across the grid cells. We then used the cells as planning units to prioritize protected area acquisitions. First, we verified that the spatial patterns of environmental and geographic variation were correlated, respectively, with adaptive and neutral genetic variation. Second, we showed that these surrogates can predict the proportion of genetic variation secured in randomly generated solutions. Finally, we discovered that solutions based only on surrogate information secured substantial amounts of adaptive and neutral genetic variation. Our work paves the way for widespread integration of surrogates for genetic variation into conservation planning.

  7. Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method

    Directory of Open Access Journals (Sweden)

    Morel P.

    2011-10-01

    Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

  8. Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method

    Directory of Open Access Journals (Sweden)

    Tassan-Got L.

    2012-02-01

    Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

  9. Generator Approach to Evolutionary Optimization of Catalysts and its Integration with Surrogate Modeling

    Czech Academy of Sciences Publication Activity Database

    Holeňa, Martin; Linke, D.; Rodemerck, U.

    2011-01-01

    Roč. 159, č. 1 (2011), s. 84-95 ISSN 0920-5861 R&D Projects: GA ČR GA201/08/0802 Institutional research plan: CEZ:AV0Z10300504 Keywords : optimization of catalytic materials * evolutionary optimization * surrogate modeling * artificial neural networks * multilayer perceptron * regression boosting Subject RIV: IN - Informatics, Computer Science Impact factor: 3.407, year: 2011

  10. Surrogate motherhood in illness that does not cause infertility

    African Journals Online (AJOL)

    Surrogate motherhood in South Africa (SA) is regulated by the. Children's Act,[1] the National Health Act[2] and its regulations,[3] and court cases.[4-6] The Children's Act formulates the legal requirement for a commissioning parent or parents to legally access surrogacy:[1]. 'A court may not confirm a surrogate motherhood ...

  11. Term clouds as surrogates for user generated speech

    NARCIS (Netherlands)

    Tsagkias, M.; Larson, M.; de Rijke, M.; Myaeng, S.-H.; Oard, D.W.; Sebastiani, F.; Chua, T.-S.; Leong, M.-K.

    2008-01-01

    User generated spoken audio remains a challenge for Automatic Speech Recognition (ASR) technology and content-based audio surrogates derived from ASR-transcripts must be error robust. An investigation of the use of term clouds as surrogates for podcasts demonstrates that ASR term clouds closely

  12. TOXICITY OF PENTACHLOROPHENOL TO ENDANGERED AND SURROGATE FISH SPECIES

    Science.gov (United States)

    Water quality criteria (WQC) generally are based on the responses of easily cultured and tested surrogate species. Little is known about the relative sensitivity of surrogate and endangered species. The objective of this study was to compare acute and chronic (early life-stage) ...

  13. Nonspinning numerical relativity waveform surrogates: assessing the model

    Science.gov (United States)

    Field, Scott; Blackman, Jonathan; Galley, Chad; Scheel, Mark; Szilagyi, Bela; Tiglio, Manuel

    2015-04-01

    Recently, multi-modal gravitational waveform surrogate models have been built directly from data numerically generated by the Spectral Einstein Code (SpEC). I will describe ways in which the surrogate model error can be quantified. This task, in turn, requires (i) characterizing differences between waveforms computed by SpEC with those predicted by the surrogate model and (ii) estimating errors associated with the SpEC waveforms from which the surrogate is built. Both pieces can have numerous sources of numerical and systematic errors. We make an attempt to study the most dominant error sources and, ultimately, the surrogate model's fidelity. These investigations yield information about the surrogate model's uncertainty as a function of time (or frequency) and parameter, and could be useful in parameter estimation studies which seek to incorporate model error. Finally, I will conclude by comparing the numerical relativity surrogate model to other inspiral-merger-ringdown models. A companion talk will cover the building of multi-modal surrogate models.

  14. Human surrogate neck response to +Gz vertical impact

    NARCIS (Netherlands)

    Rooij, L. van; Uittenbogaard, J.

    2011-01-01

    For the evaluation of impact scenarios with a substantial vertical component, the performance of current human surrogates - the RID 3D hardware dummy and two numerical human models - was evaluated. Volunteer tests with 10G and 6G pulses were compared to reconstructed tests with human surrogates.

  15. [Surrogate maternity--literature review and practice].

    Science.gov (United States)

    Pilka, L; Rumpík, D; Pilka, R; Koudelka, M; Prudil, L

    2009-04-01

    This review summarizes opinions on surrogacy including internatinal and governmental organizations attitudes, as well as some religious concerns. Literature review. Reprofit International, Brno, Reproductive medicine and gynecology centre, Zlin, Department of obstetrics and gynecology, Palacky University, Olomouc. The developments in the field of assissted reproduction during the last twenty years have attracted unexpected public interest in some of its ethical and moral aspects. It is very difficult to find a uniform attitude to ethical concerns of assisted conception in plural society. Surrogate mother is defined as a woman who bears and relinquishes a child for another person. The european congress on human reproduction in Barcelona 2008 adopted following résumé on surrogacy: Public opinion has shifted to a position where surrogacy is recognized as an appropriate response to infertility in some circumstances and it is to be expected that this approach will be further strenghtened with stress on positive aspects of familiar life.

  16. Mitigating Errors in External Respiratory Surrogate-Based Models of Tumor Position

    International Nuclear Information System (INIS)

    Malinowski, Kathleen T.; McAvoy, Thomas J.; George, Rohini; Dieterich, Sonja; D'Souza, Warren D.

    2012-01-01

    Purpose: To investigate the effect of tumor site, measurement precision, tumor–surrogate correlation, training data selection, model design, and interpatient and interfraction variations on the accuracy of external marker-based models of tumor position. Methods and Materials: Cyberknife Synchrony system log files comprising synchronously acquired positions of external markers and the tumor from 167 treatment fractions were analyzed. The accuracy of Synchrony, ordinary-least-squares regression, and partial-least-squares regression models for predicting the tumor position from the external markers was evaluated. The quantity and timing of the data used to build the predictive model were varied. The effects of tumor–surrogate correlation and the precision in both the tumor and the external surrogate position measurements were explored by adding noise to the data. Results: The tumor position prediction errors increased during the duration of a fraction. Increasing the training data quantities did not always lead to more accurate models. Adding uncorrelated noise to the external marker-based inputs degraded the tumor–surrogate correlation models by 16% for partial-least-squares and 57% for ordinary-least-squares. External marker and tumor position measurement errors led to tumor position prediction changes 0.3–3.6 times the magnitude of the measurement errors, varying widely with model algorithm. The tumor position prediction errors were significantly associated with the patient index but not with the fraction index or tumor site. Partial-least-squares was as accurate as Synchrony and more accurate than ordinary-least-squares. Conclusions: The accuracy of surrogate-based inferential models of tumor position was affected by all the investigated factors, except for the tumor site and fraction index.

  17. Mitigating Errors in External Respiratory Surrogate-Based Models of Tumor Position

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, Kathleen T. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); McAvoy, Thomas J. [Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); Department of Chemical and Biomolecular Engineering and Institute of Systems Research, University of Maryland, College Park, MD (United States); George, Rohini [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Dieterich, Sonja [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); D' Souza, Warren D., E-mail: wdsou001@umaryland.edu [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States)

    2012-04-01

    Purpose: To investigate the effect of tumor site, measurement precision, tumor-surrogate correlation, training data selection, model design, and interpatient and interfraction variations on the accuracy of external marker-based models of tumor position. Methods and Materials: Cyberknife Synchrony system log files comprising synchronously acquired positions of external markers and the tumor from 167 treatment fractions were analyzed. The accuracy of Synchrony, ordinary-least-squares regression, and partial-least-squares regression models for predicting the tumor position from the external markers was evaluated. The quantity and timing of the data used to build the predictive model were varied. The effects of tumor-surrogate correlation and the precision in both the tumor and the external surrogate position measurements were explored by adding noise to the data. Results: The tumor position prediction errors increased during the duration of a fraction. Increasing the training data quantities did not always lead to more accurate models. Adding uncorrelated noise to the external marker-based inputs degraded the tumor-surrogate correlation models by 16% for partial-least-squares and 57% for ordinary-least-squares. External marker and tumor position measurement errors led to tumor position prediction changes 0.3-3.6 times the magnitude of the measurement errors, varying widely with model algorithm. The tumor position prediction errors were significantly associated with the patient index but not with the fraction index or tumor site. Partial-least-squares was as accurate as Synchrony and more accurate than ordinary-least-squares. Conclusions: The accuracy of surrogate-based inferential models of tumor position was affected by all the investigated factors, except for the tumor site and fraction index.

  18. Naturally occurring flavonoids against human norovirus surrogates.

    Science.gov (United States)

    Su, Xiaowei; D'Souza, Doris H

    2013-06-01

    Naturally occurring plant-derived flavonoids are reported to have antibacterial, antiviral, and pharmacological activities. The objectives of this study were to determine the antiviral effects of four flavonoids (myricetin, L-epicatechin, tangeretin, and naringenin) on the infectivity of food borne norovirus surrogates after 2 h at 37 °C. The lab-culturable surrogates, feline calicivirus (FCV-F9) at titers of ~7 log₁₀ PFU/ml (high titer) or ~5 log₁₀ PFU/ml (low titer) and murine norovirus (MNV-1) at ~5 log₁₀ PFU/ml, were mixed with equal volumes of myricetin, L-epicatechin, tangeretin, or naringenin at concentrations of 0.5 or 1 mM, and incubated for 2 h at 37 °C. Treatments of viruses were neutralized in cell culture medium containing 10 % heat-inactivated fetal bovine serum, serially diluted, and plaque assayed. Each treatment was replicated thrice and assayed in duplicate. FCV-F9 (low titer) was not found to be reduced by tangeretin or naringenin, but was reduced to undetectable levels by myricetin at both concentrations. Low titer FCV-F9 was also decreased by 1.40 log₁₀ PFU/ml with L-epicatechin at 0.5 mM. FCV-F9 at high titers was decreased by 3.17 and 0.72 log₁₀ PFU/ml with myricetin and L-epicatechin at 0.5 mM, and 1.73 log10 PFU/ml with myricetin at 0.25 mM, respectively. However, MNV-1 showed no significant inactivation by the four tested treatments. The antiviral effects of the tested flavonoids are dependent on the virus type, titer, and dose. Further research will focus on understanding the antiviral mechanism of myricetin and L-epicatechin.

  19. Surrogate Motherhood and Abortion for Fetal Abnormality.

    Science.gov (United States)

    Walker, Ruth; van Zyl, Liezl

    2015-10-01

    A diagnosis of fetal abnormality presents parents with a difficult - even tragic - moral dilemma. Where this diagnosis is made in the context of surrogate motherhood there is an added difficulty, namely that it is not obvious who should be involved in making decisions about abortion, for the person who would normally have the right to decide - the pregnant woman - does not intend to raise the child. This raises the question: To what extent, if at all, should the intended parents be involved in decision-making? In commercial surrogacy it is thought that as part of the contractual agreement the intended parents acquire the right to make this decision. By contrast, in altruistic surrogacy the pregnant woman retains the right to make these decisions, but the intended parents are free to decide not to adopt the child. We argue that both these strategies are morally unsound, and that the problems encountered serve to highlight more fundamental defects within the commercial and altruistic models, as well as in the legal and institutional frameworks that support them. We argue in favour of the professional model, which acknowledges the rights and responsibilities of both parties and provides a legal and institutional framework that supports good decision-making. In particular, the professional model acknowledges the surrogate's right to decide whether to undergo an abortion, and the intended parents' obligation to accept legal custody of the child. While not solving all the problems that arise in surrogacy, the model provides a framework that supports good decision-making. © 2015 John Wiley & Sons Ltd.

  20. Multiple Surrogate Modeling for Wire-Wrapped Fuel Assembly Optimization

    International Nuclear Information System (INIS)

    Raza, Wasim; Kim, Kwang-Yong

    2007-01-01

    In this work, shape optimization of seven pin wire wrapped fuel assembly has been carried out in conjunction with RANS analysis in order to evaluate the performances of surrogate models. Previously, Ahmad and Kim performed the flow and heat transfer analysis based on the three-dimensional RANS analysis. But numerical optimization has not been applied to the design of wire-wrapped fuel assembly, yet. Surrogate models are being widely used in multidisciplinary optimization. Queipo et al. reviewed various surrogates based models used in aerospace applications. Goel et al. developed weighted average surrogate model based on response surface approximation (RSA), radial basis neural network (RBNN) and Krigging (KRG) models. In addition to the three basic models, RSA, RBNN and KRG, the multiple surrogate model, PBA also has been employed. Two geometric design variables and a multi-objective function with a weighting factor have been considered for this problem

  1. Final Report on Utilization of TRU TRISO Fuel as Applied to HTR Systems Part I: Pebble Bed Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Brian Boer; Abderrafi M. Ougouag

    2011-03-01

    The Deep-Burn (DB) concept [ ] focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400) [ ]. Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no

  2. Final Report on Utilization of TRU TRISO Fuel as Applied to HTR Systems Part I: Pebble Bed Reactors

    International Nuclear Information System (INIS)

    Boer, Brian; Ougouag, Abderrafi M.

    2011-01-01

    The Deep-Burn (DB) concept focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400). Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no significant

  3. Comments on Surrogates measures and consistent surrogates (by Tyler VanderWeele)

    Science.gov (United States)

    2013-03-01

    as a criterion for “good” surrogate, why can’t we create a new, formal definition of “ surrogacy ” that (1) will automatically avoid the paradox and (2...requirement of avoiding the paradox could not, in itself, constitute a satisfactory definition of surrogacy . As with other paradoxes of causal...situation in practice. A treatment that has such a negative direct effect on outcome would rarely be a candidate for surrogacy analysis. In practice

  4. Fission products silver, palladium, and cadmium identification in neutron-irradiated SiC TRISO particles using a Cs-Corrected HRTEM

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: isabella.vanrooyen@inl.gov [Fuel Design and Development Department, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415-6188 (United States); Olivier, E.J.; Neethling, J.H. [Centre for High Resolution Electron Microscopy, Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2016-08-01

    Electron microscopy investigations of selected coated particles from the first advanced gas reactor experiment at Idaho National Laboratory provided important information on fission product distribution and chemical composition in the silicon-carbide (SiC) layer. Silver precipitates were nano-sized, and therefore high-resolution transmission electron microscopy (HRTEM) was used to provide more information at the atomic level. Based on gamma-ray analysis, this particle which was irradiated to an average burnup of 19.38% fissions per initial metal atom, may have released as much as 10% of its available Ag-110 m inventory during irradiation. The HRTEM investigation focused on silver, palladium, and cadmium due to interest in silver transport mechanisms and possible correlation with palladium and silver previously found. Palladium, silver, and cadmium were found to co-exist in some of the SiC grain boundaries and triple junctions. This study confirmed palladium both at inter and intragranular sites. Phosphor was identified in SiC grain boundaries and triple points. - Highlights: • First high resolution electron microscopy fission product nano-structural locations of irradiated TRISO coated particles. • Pd observed inside SiC grains in proximity to planar defects e.g. stacking faults. • Ag co-exists with Pd and Cd only may suggest a Pd-assisted transport mechanism. • First finding of neutron transmutation product P, in SiC layer of TRISO coated particles. No direct link to Ag transport. • No significant Pd corrosion of SiC observed even at this high resolution images.

  5. Evaluation of protection systems for the lower extremity against the shock and blast effects resulting from anti-personnel mines using the Surrogate Lower Leg (SLL)

    CSIR Research Space (South Africa)

    Smit, E

    2012-10-01

    Full Text Available . Injury assessment Mine trauma score Injury No major injury 0 Salvageable limb 1 Closed 1A Open contained 1B Open contaminated Transtibial amputation 2 Closed 2A Open contained 2B Open contaminated Transtibial/transfemoral amputation 3... Transfemoral amputation 4 SURROGATE LOWER LEG DEVELOPMENT The Surrogate Lower Leg (SLL) approximates an actual human leg in terms of geometry and materials of construction. The SLL is intended for destructive testing in order to assess the degree of tissue...

  6. Dynamic impact indentation of hydrated biological tissues and tissue surrogate gels

    Science.gov (United States)

    Ilke Kalcioglu, Z.; Qu, Meng; Strawhecker, Kenneth E.; Shazly, Tarek; Edelman, Elazer; VanLandingham, Mark R.; Smith, James F.; Van Vliet, Krystyn J.

    2011-03-01

    For both materials engineering research and applied biomedicine, a growing need exists to quantify mechanical behaviour of tissues under defined hydration and loading conditions. In particular, characterisation under dynamic contact-loading conditions can enable quantitative predictions of deformation due to high rate 'impact' events typical of industrial accidents and ballistic insults. The impact indentation responses were examined of both hydrated tissues and candidate tissue surrogate materials. The goals of this work were to determine the mechanical response of fully hydrated soft tissues under defined dynamic loading conditions, and to identify design principles by which synthetic, air-stable polymers could mimic those responses. Soft tissues from two organs (liver and heart), a commercially available tissue surrogate gel (Perma-Gel™) and three styrenic block copolymer gels were investigated. Impact indentation enabled quantification of resistance to penetration and energy dissipative constants under the rates and energy densities of interest for tissue surrogate applications. These analyses indicated that the energy dissipation capacity under dynamic impact increased with increasing diblock concentration in the styrenic gels. Under the impact rates employed (2 mm/s to 20 mm/s, corresponding to approximate strain energy densities from 0.4 kJ/m3 to 20 kJ/m3), the energy dissipation capacities of fully hydrated soft tissues were ultimately well matched by a 50/50 triblock/diblock composition that is stable in ambient environments. More generally, the methodologies detailed here facilitate further optimisation of impact energy dissipation capacity of polymer-based tissue surrogate materials, either in air or in fluids.

  7. Distribution of the grain limit character in SiC and its effect on the diffusion of fission products in the TRISO fuel particles; Distribucion del caracter de limite de grano en SiC y su efecto sobre la difusion de los productos de fision en las particulas de combustible TRISO

    Energy Technology Data Exchange (ETDEWEB)

    Cancino T, F.; Lopez H, E., E-mail: Eddie.lopez@cinvestav.edu.mx [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Av. Industria Metalurgica 1062, Zona Industrial, 25900 Ramos Arizpe, Coahuila (Mexico)

    2017-09-15

    At present is accepted that silver diffuses through silicium carbide (SiC) by diffusion in grain boundaries, although little is known about the characteristics of grain boundaries in SiC, and how these change depending on the type of sample. In this work, was observed that there are small but important differences between the SiC in the tri-structural isotropic (TRISO) particles and that of the monoliths, which could explain some of the differences observed in experiments on diffusion in the literature. Five different types (coatings and monoliths) of SiC produced by chemical vapor deposition (CVD) were characterized by electron backscatter diffraction (EBSD). In all the samples the SiC was mainly composed of high-angle grain boundaries (∼ 65%), with a small fraction of grain boundaries of low-angle (about 15%) and 20% of the coincidence site lattice (CSL). The morphology of the monoliths is constituted by large grains, surrounded by smaller grains; in the particles of the TRISO fuel, both columnar and equi axial grains were observed, with a more uniform distribution over the surface of the coating. (Author)

  8. Materialism.

    Science.gov (United States)

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Emotional experiences in surrogate mothers: A qualitative study.

    Science.gov (United States)

    Ahmari Tehran, Hoda; Tashi, Shohreh; Mehran, Nahid; Eskandari, Narges; Dadkhah Tehrani, Tahmineh

    2014-07-01

    Surrogacy is one of the new techniques of assisted reproduction technology in which a woman carries and bears a child for another woman. In Iran, many Shia clerics and jurists considered it permissible so there is no religious prohibition for it. In addition to the risk of physical complications for complete surrogate mothers, the possibility of psychological complications resulted from emotional attachment to a living creature in the surrogate mother as another injury requires counseling and assessment prior to acceptance by infertile couples and complete surrogate mothers. The purpose of this study was to assess the emotional experiences of surrogate mothers. This was a qualitative, phenomenological study. We selected eight complete surrogate mothers in Isfahan. We used convenient sampling method and in-depth interview to collect the information. The data analysis was fulfilled via Colaizzi's seven-stage method. Reliability and validity study of the roots in the four-axis was done. The findings of these interviews were classified into two main themes and four sub themes: acquired experiences in pregnancy (feelings toward pregnancy, relationship with family, relatives and commissioning couple) and consequences of surrogacy (complications of pregnancy, religious and financial problems of surrogacy). Surrogacy pregnancy should be considered as high-risk emotional experience because many of surrogate mothers may face negative experiences. Therefore, it is recommended that surrogates should receive professional counseling prior to, during and following pregnancy.

  10. [The surrogate: Partner in the shared decision-making].

    Science.gov (United States)

    Sarradon-Eck, Aline; Capodano, Géraldine; Bureau, Eve; Julian-Reynier, Claire

    2016-01-01

    The legislative process of the surrogate appears to be unclear to health professionals and to patients and next of kin. To better adapt this process to the clinical practice our objective was here to document how the persons designated as surrogate perceived their role and how they described the difficulties encountered in oncology. Qualitative survey with an ethnographic approach carried out in 2014-2015, fieldwork, face-to-face interviews (n=26 including 20 surrogates and 6 patients) in a mobile palliative care unit located at a Regional Comprehensive Cancer Centre. Close relationship, psychological and cognitive competences were the main attribute to designate a surrogate. Perceived roles included the fact to be involved in decisions, to protect the patient, to be present, and to be a messenger. This process gives the next of kin the feeling to be part of the patient management. In the context of divorced families, it sometimes allows to rehabilitate and to reinforce the affective links. Our data highlight the confusion between the designation of the 'person to call' and 'the surrogate'. Our results highlight the 'surrogate' protective role of the patient, and the positive sides of the process, in particular in the context of divorced/rebuilt families. We recommend splitting the process to designate the 'person to call' and the 'surrogate', as administrative and medical duties, respectively. Copyright © 2016 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.

  11. Adaptive surrogate model based multiobjective optimization for coastal aquifer management

    Science.gov (United States)

    Song, Jian; Yang, Yun; Wu, Jianfeng; Wu, Jichun; Sun, Xiaomin; Lin, Jin

    2018-06-01

    In this study, a novel surrogate model assisted multiobjective memetic algorithm (SMOMA) is developed for optimal pumping strategies of large-scale coastal groundwater problems. The proposed SMOMA integrates an efficient data-driven surrogate model with an improved non-dominated sorted genetic algorithm-II (NSGAII) that employs a local search operator to accelerate its convergence in optimization. The surrogate model based on Kernel Extreme Learning Machine (KELM) is developed and evaluated as an approximate simulator to generate the patterns of regional groundwater flow and salinity levels in coastal aquifers for reducing huge computational burden. The KELM model is adaptively trained during evolutionary search to satisfy desired fidelity level of surrogate so that it inhibits error accumulation of forecasting and results in correctly converging to true Pareto-optimal front. The proposed methodology is then applied to a large-scale coastal aquifer management in Baldwin County, Alabama. Objectives of minimizing the saltwater mass increase and maximizing the total pumping rate in the coastal aquifers are considered. The optimal solutions achieved by the proposed adaptive surrogate model are compared against those solutions obtained from one-shot surrogate model and original simulation model. The adaptive surrogate model does not only improve the prediction accuracy of Pareto-optimal solutions compared with those by the one-shot surrogate model, but also maintains the equivalent quality of Pareto-optimal solutions compared with those by NSGAII coupled with original simulation model, while retaining the advantage of surrogate models in reducing computational burden up to 94% of time-saving. This study shows that the proposed methodology is a computationally efficient and promising tool for multiobjective optimizations of coastal aquifer managements.

  12. Surrogate motherhood as a medical treatment procedure for women's infertility.

    Science.gov (United States)

    Jovic, Olga S

    2011-03-01

    The content of this work is conceived on the research of the consequences of surrogate motherhood as a process of assisted procreation, which represent a way of parenthood in cases when it is not possible to realize parenthood through a natural way. Surrogate motherhood is a process in which a woman (surrogate mother) agrees to carry a pregnancy with the intent to give the child to the couple with whom she has made a contract on surrogate maternity after the birth. This process of conception and birth makes the determination of the child's origin on its mother's side hard to determine, because of the distinction of the genetic and gestation phases of the two women. The concept of surrogate motherhood is to appear in two forms, depending on the existence or the non-existence of the genetic link between the surrogate mother and the child she gives birth to. There are gestation (full) and genetic (partial) surrogates each with different modalities and legal and ethical implications. In Serbia, Infertility Treatment and the Bio-medically Assisted Procreation Act from 2009 explicitly forbids surrogate motherhood, despite the fact that an infertile couple decides to use it, as a rule, after having tried all other treatment procedures, in cases when there is a diagnosis but the conventional treatment applied has not produced the desired results. Given the fact that no one has the right to ignore the sufferings of people who cannot procreate naturally, the medical practice and legal science in our country plead for a formulation of a legal framework in which to apply surrogate motherhood as an infertility treatment, under particular conditions.

  13. Efficient stochastic EMC/EMI analysis using HDMR-generated surrogate models

    KAUST Repository

    Yücel, Abdulkadir C.

    2011-08-01

    Stochastic methods have been used extensively to quantify effects due to uncertainty in system parameters (e.g. material, geometrical, and electrical constants) and/or excitation on observables pertinent to electromagnetic compatibility and interference (EMC/EMI) analysis (e.g. voltages across mission-critical circuit elements) [1]. In recent years, stochastic collocation (SC) methods, especially those leveraging generalized polynomial chaos (gPC) expansions, have received significant attention [2, 3]. SC-gPC methods probe surrogate models (i.e. compact polynomial input-output representations) to statistically characterize observables. They are nonintrusive, that is they use existing deterministic simulators, and often cost only a fraction of direct Monte-Carlo (MC) methods. Unfortunately, SC-gPC-generated surrogate models often lack accuracy (i) when the number of uncertain/random system variables is large and/or (ii) when the observables exhibit rapid variations. © 2011 IEEE.

  14. Quantum dynamics of a vibronically coupled linear chain using a surrogate Hamiltonian approach

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myeong H., E-mail: myeong.lee@warwick.ac.uk; Troisi, Alessandro [Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-06-07

    Vibronic coupling between the electronic and vibrational degrees of freedom has been reported to play an important role in charge and exciton transport in organic photovoltaic materials, molecular aggregates, and light-harvesting complexes. Explicitly accounting for effective vibrational modes rather than treating them as a thermal environment has been shown to be crucial to describe the effect of vibronic coupling. We present a methodology to study dissipative quantum dynamics of vibronically coupled systems based on a surrogate Hamiltonian approach, which is in principle not limited by Markov approximation or weak system-bath interaction, using a vibronic basis. We apply vibronic surrogate Hamiltonian method to a linear chain system and discuss how different types of relaxation process, intramolecular vibrational relaxation and intermolecular vibronic relaxation, influence population dynamics of dissipative vibronic systems.

  15. A minimalist functional group (MFG) approach for surrogate fuel formulation

    KAUST Repository

    Abdul Jameel, Abdul Gani; Naser, Nimal; Issayev, Gani; Touitou, Jamal; Ghosh, Manik Kumer; Emwas, Abdul-Hamid M.; Farooq, Aamir; Dooley, Stephen; Sarathy, Mani

    2018-01-01

    Surrogate fuel formulation has drawn significant interest due to its relevance towards understanding combustion properties of complex fuel mixtures. In this work, we present a novel approach for surrogate fuel formulation by matching target fuel functional groups, while minimizing the number of surrogate species. Five key functional groups; paraffinic CH, paraffinic CH, paraffinic CH, naphthenic CH–CH and aromatic C–CH groups in addition to structural information provided by the Branching Index (BI) were chosen as matching targets. Surrogates were developed for six FACE (Fuels for Advanced Combustion Engines) gasoline target fuels, namely FACE A, C, F, G, I and J. The five functional groups present in the fuels were qualitatively and quantitatively identified using high resolution H Nuclear Magnetic Resonance (NMR) spectroscopy. A further constraint was imposed in limiting the number of surrogate components to a maximum of two. This simplifies the process of surrogate formulation, facilitates surrogate testing, and significantly reduces the size and time involved in developing chemical kinetic models by reducing the number of thermochemical and kinetic parameters requiring estimation. Fewer species also reduces the computational expenses involved in simulating combustion in practical devices. The proposed surrogate formulation methodology is denoted as the Minimalist Functional Group (MFG) approach. The MFG surrogates were experimentally tested against their target fuels using Ignition Delay Times (IDT) measured in an Ignition Quality Tester (IQT), as specified by the standard ASTM D6890 methodology, and in a Rapid Compression Machine (RCM). Threshold Sooting Index (TSI) and Smoke Point (SP) measurements were also performed to determine the sooting propensities of the surrogates and target fuels. The results showed that MFG surrogates were able to reproduce the aforementioned combustion properties of the target FACE gasolines across a wide range of conditions

  16. A minimalist functional group (MFG) approach for surrogate fuel formulation

    KAUST Repository

    Abdul Jameel, Abdul Gani

    2018-03-20

    Surrogate fuel formulation has drawn significant interest due to its relevance towards understanding combustion properties of complex fuel mixtures. In this work, we present a novel approach for surrogate fuel formulation by matching target fuel functional groups, while minimizing the number of surrogate species. Five key functional groups; paraffinic CH, paraffinic CH, paraffinic CH, naphthenic CH–CH and aromatic C–CH groups in addition to structural information provided by the Branching Index (BI) were chosen as matching targets. Surrogates were developed for six FACE (Fuels for Advanced Combustion Engines) gasoline target fuels, namely FACE A, C, F, G, I and J. The five functional groups present in the fuels were qualitatively and quantitatively identified using high resolution H Nuclear Magnetic Resonance (NMR) spectroscopy. A further constraint was imposed in limiting the number of surrogate components to a maximum of two. This simplifies the process of surrogate formulation, facilitates surrogate testing, and significantly reduces the size and time involved in developing chemical kinetic models by reducing the number of thermochemical and kinetic parameters requiring estimation. Fewer species also reduces the computational expenses involved in simulating combustion in practical devices. The proposed surrogate formulation methodology is denoted as the Minimalist Functional Group (MFG) approach. The MFG surrogates were experimentally tested against their target fuels using Ignition Delay Times (IDT) measured in an Ignition Quality Tester (IQT), as specified by the standard ASTM D6890 methodology, and in a Rapid Compression Machine (RCM). Threshold Sooting Index (TSI) and Smoke Point (SP) measurements were also performed to determine the sooting propensities of the surrogates and target fuels. The results showed that MFG surrogates were able to reproduce the aforementioned combustion properties of the target FACE gasolines across a wide range of conditions

  17. Mother-daughter in vitro fertilization triplet surrogate pregnancy.

    Science.gov (United States)

    Michelow, M C; Bernstein, J; Jacobson, M J; McLoughlin, J L; Rubenstein, D; Hacking, A I; Preddy, S; Van der Wat, I J

    1988-02-01

    A successful triplet pregnancy has been established in a surrogate gestational mother following the transfer of five embryos fertilized in vitro. The oocytes were donated by her biological daughter, and the sperm obtained from the daughter's husband. The daughter's infertility followed a total abdominal hysterectomy performed for a postpartum hemorrhage as a result of a placenta accreta. Synchronization of both their menstrual cycles was obtained using oral contraceptive suppression for 2 months, followed by stimulation of both the surrogate gestational mother and her daughter such that embryo transfer would occur at least 48 hr after the surrogate gestational mother's own ovulation. This case raises a number of medical, social, psychological, and ethical issues.

  18. A Large-Scale Study of Surrogate Physicality and Gesturing on Human–Surrogate Interactions in a Public Space

    Directory of Open Access Journals (Sweden)

    Kangsoo Kim

    2017-07-01

    Full Text Available Technological human surrogates, including robotic and virtual humans, have been popularly used in various scenarios, including training, education, and entertainment. Prior research has investigated the effects of the surrogate’s physicality and gesturing in human perceptions and social influence of the surrogate. However, those studies have been carried out in research laboratories, where the participants were aware that it was an experiment, and the participant demographics are typically relatively narrow—e.g., college students. In this paper, we describe and share results from a large-scale exploratory user study involving 7,685 people in a public space, where they were unaware of the experimental nature of the setting, to investigate the effects of surrogate physicality and gesturing on their behavior during human–surrogate interactions. We evaluate human behaviors using several variables, such as proactivity and reactivity, and proximity. We have identified several interesting phenomena that could lead to hypotheses developed as part of future hypothesis-based studies. Based on the measurements of the variables, we believe people are more likely to be engaged in a human–surrogate interaction when the surrogate is physically present, but movements and gesturing with its body parts have not shown the expected benefits for the interaction engagement. Regarding the demographics of the people in the study, we found higher overall engagement for females than males, and higher reactivity for younger than older people. We discuss implications for practitioners aiming to design a technological surrogate that will directly interact with real humans.

  19. Surrogate Motherhood: A Trust-Based Approach.

    Science.gov (United States)

    Beier, Katharina

    2015-12-01

    Because it is often argued that surrogacy should not be treated as contractual, the question arises in which terms this practice might then be couched. In this article, I argue that a phenomenology of surrogacy centering on the notion of trust provides a description that is illuminating from the moral point of view. My thesis is that surrogacy establishes a complex and extended reproductive unit--the "surrogacy triad" consisting of the surrogate mother, the child, and the intending parents--whose constituents are bound together by mutual trustful commitments. Even though a trust-based approach does not provide an ultimate answer to whether surrogacy should be sanctioned or prohibited, it allows for at least some practical suggestions. In particular, I will argue that, under certain conditions, surrogacy is tenable within familial or other significant relationships, and I will stress the necessity of acknowledging the new relationships and moral commitments that result from this practice. © The Author 2015. Published by Oxford University Press, on behalf of the Journal of Medicine and Philosophy Inc. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. SURROGATE MOTHER DALAM PERSPEKTIF HUKUM PIDANA INDONESIA

    Directory of Open Access Journals (Sweden)

    Mr. Muntaha

    2013-04-01

    Full Text Available The development of science and technology, in particular in the field of health, has already recently brought a huge advantage and problem in human life. An example of technological marvel that not only requires deep legal thoughts but also at the same time solution is the bio-medical technology advancement of surrogacy. Surrogacy deals with human’s inclination towards reproductive activity. However, it opens up legal complication, in particular with regards to the potential commission of a criminal action as well as to the notion of doctor’s liability. Perkembangan ilmu dan teknologi di bidang kesehatan yang semakin maju dan pesat telah membawa berbagai manfaat dan masalah dalam kehidupan manusia dewasa ini. Salah satu perkembangan yang tidak hanya membutuhkan pemikiran di bidang hukum, tetapi juga sekaligus solusinya adalah mengenai kecanggihan teknologi bio-medis surrogate mother. Surrogacy menyentuh sisi kemanusiaan seorang insan terhadap reproduksi. Akan tetapi, lembaga surrogacy juga membawa komplikasi hukum terutama terkait dengan potensi tindak pidana dan dengan persoalan tanggung jawab dokter.

  1. Polynomial Chaos Surrogates for Bayesian Inference

    KAUST Repository

    Le Maitre, Olivier

    2016-01-06

    The Bayesian inference is a popular probabilistic method to solve inverse problems, such as the identification of field parameter in a PDE model. The inference rely on the Bayes rule to update the prior density of the sought field, from observations, and derive its posterior distribution. In most cases the posterior distribution has no explicit form and has to be sampled, for instance using a Markov-Chain Monte Carlo method. In practice the prior field parameter is decomposed and truncated (e.g. by means of Karhunen- Lo´eve decomposition) to recast the inference problem into the inference of a finite number of coordinates. Although proved effective in many situations, the Bayesian inference as sketched above faces several difficulties requiring improvements. First, sampling the posterior can be a extremely costly task as it requires multiple resolutions of the PDE model for different values of the field parameter. Second, when the observations are not very much informative, the inferred parameter field can highly depends on its prior which can be somehow arbitrary. These issues have motivated the introduction of reduced modeling or surrogates for the (approximate) determination of the parametrized PDE solution and hyperparameters in the description of the prior field. Our contribution focuses on recent developments in these two directions: the acceleration of the posterior sampling by means of Polynomial Chaos expansions and the efficient treatment of parametrized covariance functions for the prior field. We also discuss the possibility of making such approach adaptive to further improve its efficiency.

  2. Materials

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2009-02-01

    Full Text Available . It is generally included as part of a structurally insulated panel (SIP) where the foam is sandwiched between external skins of steel, wood or cement. Cement composites Cement bonded composites are an important class of building materials. These products... for their stone buildings, including the Egyptians, Aztecs and Inca’s. As stone is a very dense material it requires intensive heating to become warm. Rocks were generally stacked dry but mud, and later cement, can be used as a mortar to hold the rocks...

  3. The Decomposition of Surrogate Fuel Molecules During Combustion

    National Research Council Canada - National Science Library

    Tsang, Wing; Manion, Jeffrey A

    2006-01-01

    This project is aimed at developing a chemical kinetic database consisting of the rate constants of fundamental single step reactions that describe the pyrolytic decomposition of surrogate fuels molecules...

  4. A Parallel and Distributed Surrogate Model Implementation for Computational Steering

    KAUST Repository

    Butnaru, Daniel; Buse, Gerrit; Pfluger, Dirk

    2012-01-01

    of the input parameters. Such an exploration process is however not possible if the simulation is computationally too expensive. For these cases we present in this paper a scalable computational steering approach utilizing a fast surrogate model as substitute

  5. Altruistic surrogacy: the necessary objectification of surrogate mothers.

    Science.gov (United States)

    Tieu, M M

    2009-03-01

    One of the major concerns about surrogacy is the potential harm that may be inflicted upon the surrogate mother and the child after relinquishment. Even if one were to take the liberal view that surrogacy should be presumptively allowed on the basis of autonomy and/or compassion, evidence of harm must be taken seriously. In this paper I review the evidence from psychological studies on the effect that relinquishing a child has on the surrogate mother and while it appears that many surrogates are able to cope with relinquishment, I argue that there are good reasons, grounded in empirical evidence, to support the view that the subsequent management of the relinquishment necessarily objectifies the surrogate mother.

  6. SURROGATE SPECIES IN ASSESSING CONTAMINANT RISK FOR ENDANGERED FISHES

    Science.gov (United States)

    Rainbow trout, fathead minnows, and sheepshead minnows were tested as surrogate species to assess contaminant risk for 17 endangered fishes and one toad species. Acute toxicity tests were conducted with carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin in accord...

  7. Hepatology may have problems with putative surrogate outcome measures

    DEFF Research Database (Denmark)

    Gluud, Christian; Brok, Jesper; Gong, Yan

    2007-01-01

    A surrogate outcome measure is a laboratory measurement, a physical sign, or another intermediate substitute that is able to predict an intervention's effect on a clinically meaningful outcome. A clinical outcome detects how a patient feels, functions, or survives. Surrogate outcome measures occur...... faster or more often, are cheaper, and/or are less invasively achieved than the clinical outcome. In practice, validation is surprisingly often overlooked, especially if a biologic plausible rationale is proposed. Surrogate outcomes must be validated before use. The first step in validation...... predicts the intervention's effect on the clinical outcome. In hepatology a number of putative surrogate outcomes are used both in clinical research and in clinical practice without having been properly validated. Sustained virological response to interferons and ribavirin in patients with chronic...

  8. Reduced order surrogate modelling (ROSM) of high dimensional deterministic simulations

    Science.gov (United States)

    Mitry, Mina

    Often, computationally expensive engineering simulations can prohibit the engineering design process. As a result, designers may turn to a less computationally demanding approximate, or surrogate, model to facilitate their design process. However, owing to the the curse of dimensionality, classical surrogate models become too computationally expensive for high dimensional data. To address this limitation of classical methods, we develop linear and non-linear Reduced Order Surrogate Modelling (ROSM) techniques. Two algorithms are presented, which are based on a combination of linear/kernel principal component analysis and radial basis functions. These algorithms are applied to subsonic and transonic aerodynamic data, as well as a model for a chemical spill in a channel. The results of this thesis show that ROSM can provide a significant computational benefit over classical surrogate modelling, sometimes at the expense of a minor loss in accuracy.

  9. Premixed flame chemistry of a gasoline primary reference fuel surrogate

    KAUST Repository

    Selim, Hatem; Mohamed, Samah; Hansen, Nils; Sarathy, Mani

    2017-01-01

    Investigating the combustion chemistry of gasoline surrogate fuels promises to improve detailed reaction mechanisms used for simulating their combustion. In this work, the combustion chemistry of one of the simplest, but most frequently used

  10. Emotional experiences in surrogate mothers: A qualitative study

    OpenAIRE

    Ahmari Tehran, Hoda; Tashi, Shohreh; Mehran, Nahid; Eskandari, Narges; Dadkhah Tehrani, Tahmineh

    2014-01-01

    Background: Surrogacy is one of the new techniques of assisted reproduction technology in which a woman carries and bears a child for another woman. In Iran, many Shia clerics and jurists considered it permissible so there is no religious prohibition for it. In addition to the risk of physical complications for complete surrogate mothers, the possibility of psychological complications resulted from emotional attachment to a living creature in the surrogate mother as another injury requires co...

  11. Families in the making: gestational surrogate mothers in California

    OpenAIRE

    Bjørn, Henriette Hårseide

    2014-01-01

    This thesis is based on a field work I conducted in California from January to June 2012, where I explore how gestational surrogate mothers experience the process of surrogacy and how California law has dealt with ART-cases. Through exploring surrogacy from different view point, and in particular from the view of surrogate mothers, this has given an insightful view into surrogacy in California. I have identified two court cases which are important for the establishment of parental rights in s...

  12. Act relating to surrogate parenthood contracts, 10 February 1988.

    Science.gov (United States)

    1988-01-01

    This Nebraska Act provides that surrogate parenthood contracts are void and unenforceable and that the "biological father of a child born pursuant to such a contract shall have all the rights and obligations imposed by law with respect to the child." A surrogate parenthood contract is defined as "a contract by which a woman is to be compensated for bearing a child of a man who is not her husband." full text

  13. Error modeling for surrogates of dynamical systems using machine learning

    Science.gov (United States)

    Trehan, Sumeet; Carlberg, Kevin T.; Durlofsky, Louis J.

    2017-12-01

    A machine-learning-based framework for modeling the error introduced by surrogate models of parameterized dynamical systems is proposed. The framework entails the use of high-dimensional regression techniques (e.g., random forests, LASSO) to map a large set of inexpensively computed `error indicators' (i.e., features) produced by the surrogate model at a given time instance to a prediction of the surrogate-model error in a quantity of interest (QoI). This eliminates the need for the user to hand-select a small number of informative features. The methodology requires a training set of parameter instances at which the time-dependent surrogate-model error is computed by simulating both the high-fidelity and surrogate models. Using these training data, the method first determines regression-model locality (via classification or clustering), and subsequently constructs a `local' regression model to predict the time-instantaneous error within each identified region of feature space. We consider two uses for the resulting error model: (1) as a correction to the surrogate-model QoI prediction at each time instance, and (2) as a way to statistically model arbitrary functions of the time-dependent surrogate-model error (e.g., time-integrated errors). We apply the proposed framework to model errors in reduced-order models of nonlinear oil--water subsurface flow simulations. The reduced-order models used in this work entail application of trajectory piecewise linearization with proper orthogonal decomposition. When the first use of the method is considered, numerical experiments demonstrate consistent improvement in accuracy in the time-instantaneous QoI prediction relative to the original surrogate model, across a large number of test cases. When the second use is considered, results show that the proposed method provides accurate statistical predictions of the time- and well-averaged errors.

  14. Evaluation and comparison of predictive individual-level general surrogates.

    Science.gov (United States)

    Gabriel, Erin E; Sachs, Michael C; Halloran, M Elizabeth

    2018-07-01

    An intermediate response measure that accurately predicts efficacy in a new setting at the individual level could be used both for prediction and personalized medical decisions. In this article, we define a predictive individual-level general surrogate (PIGS), which is an individual-level intermediate response that can be used to accurately predict individual efficacy in a new setting. While methods for evaluating trial-level general surrogates, which are predictors of trial-level efficacy, have been developed previously, few, if any, methods have been developed to evaluate individual-level general surrogates, and no methods have formalized the use of cross-validation to quantify the expected prediction error. Our proposed method uses existing methods of individual-level surrogate evaluation within a given clinical trial setting in combination with cross-validation over a set of clinical trials to evaluate surrogate quality and to estimate the absolute prediction error that is expected in a new trial setting when using a PIGS. Simulations show that our method performs well across a variety of scenarios. We use our method to evaluate and to compare candidate individual-level general surrogates over a set of multi-national trials of a pentavalent rotavirus vaccine.

  15. Statistical characteristics of surrogate data based on geophysical measurements

    Directory of Open Access Journals (Sweden)

    V. Venema

    2006-01-01

    Full Text Available In this study, the statistical properties of a range of measurements are compared with those of their surrogate time series. Seven different records are studied, amongst others, historical time series of mean daily temperature, daily rain sums and runoff from two rivers, and cloud measurements. Seven different algorithms are used to generate the surrogate time series. The best-known method is the iterative amplitude adjusted Fourier transform (IAAFT algorithm, which is able to reproduce the measured distribution as well as the power spectrum. Using this setup, the measurements and their surrogates are compared with respect to their power spectrum, increment distribution, structure functions, annual percentiles and return values. It is found that the surrogates that reproduce the power spectrum and the distribution of the measurements are able to closely match the increment distributions and the structure functions of the measurements, but this often does not hold for surrogates that only mimic the power spectrum of the measurement. However, even the best performing surrogates do not have asymmetric increment distributions, i.e., they cannot reproduce nonlinear dynamical processes that are asymmetric in time. Furthermore, we have found deviations of the structure functions on small scales.

  16. Improving Communication With Surrogate Decision-Makers: A Pilot Initiative.

    Science.gov (United States)

    Meltzer, Ellen C; Shi, Zhenzhen; Suppes, Alexandra; Hersh, Jennifer E; Orlander, Jay D; Calhoun, Aaron W; Tung, Judy; Logio, Lia; Manna, Ruth; Bialer, Philip A; Acres, Cathleen A; Fins, Joseph J

    2017-08-01

    Difficult conversations in medical care often occur between physicians and patients' surrogates, individuals entrusted with medical decisions for patients who lack the capacity to make them. Poor communication between patients' surrogates and physicians may exacerbate anxiety and guilt for surrogates, and may contribute to physician stress and burnout. This pilot study assesses the effectiveness of an experiential learning workshop that was conducted in a clinical setting, and aimed at improving resident physician communication skills with a focus on surrogate decision-making. From April through June 2016, we assessed internal medicine residents' baseline communication skills through an objective structured clinical examination (OSCE) with actors representing standardized surrogates. After an intensive, 6-hour communication skills workshop, residents were reassessed via an OSCE on the same day. A faculty facilitator and the surrogate evaluated participants' communication skills via the expanded Gap Kalamazoo Consensus Statement Assessment Form. Wilcoxon signed rank tests (α of .05) compared mean pre- and postworkshop scores. Of 44 residents, 33 (75%) participated. Participants' average preworkshop OSCE scores ( M  = 3.3, SD = 0.9) were significantly lower than postworkshop scores ( M  = 4.3; SD = 0.8; Z  = 4.193; P  decision-making benefit from focused interventions. Our pilot assessment of a workshop showed promise, and additionally demonstrated the feasibility of bringing OSCEs and simulated encounters into a busy clinical practice.

  17. Incidence of Changes in Respiration-Induced Tumor Motion and Its Relationship With Respiratory Surrogates During Individual Treatment Fractions

    International Nuclear Information System (INIS)

    Malinowski, Kathleen; McAvoy, Thomas J.; George, Rohini; Dietrich, Sonja; D’Souza, Warren D.

    2012-01-01

    Purpose: To determine how frequently (1) tumor motion and (2) the spatial relationship between tumor and respiratory surrogate markers change during a treatment fraction in lung and pancreas cancer patients. Methods and Materials: A Cyberknife Synchrony system radiographically localized the tumor and simultaneously tracked three respiratory surrogate markers fixed to a form-fitting vest. Data in 55 lung and 29 pancreas fractions were divided into successive 10-min blocks. Mean tumor positions and tumor position distributions were compared across 10-min blocks of data. Treatment margins were calculated from both 10 and 30 min of data. Partial least squares (PLS) regression models of tumor positions as a function of external surrogate marker positions were created from the first 10 min of data in each fraction; the incidence of significant PLS model degradation was used to assess changes in the spatial relationship between tumors and surrogate markers. Results: The absolute change in mean tumor position from first to third 10-min blocks was >5 mm in 13% and 7% of lung and pancreas cases, respectively. Superior–inferior and medial–lateral differences in mean tumor position were significantly associated with the lobe of lung. In 61% and 54% of lung and pancreas fractions, respectively, margins calculated from 30 min of data were larger than margins calculated from 10 min of data. The change in treatment margin magnitude for superior–inferior motion was >1 mm in 42% of lung and 45% of pancreas fractions. Significantly increasing tumor position prediction model error (mean ± standard deviation rates of change of 1.6 ± 2.5 mm per 10 min) over 30 min indicated tumor–surrogate relationship changes in 63% of fractions. Conclusions: Both tumor motion and the relationship between tumor and respiratory surrogate displacements change in most treatment fractions for patient in-room time of 30 min.

  18. Incidence of Changes in Respiration-Induced Tumor Motion and Its Relationship With Respiratory Surrogates During Individual Treatment Fractions

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, Kathleen [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); McAvoy, Thomas J. [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Institute of Systems Research, University of Maryland, College Park, MD (United States); George, Rohini [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Dietrich, Sonja [Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA (United States); D' Souza, Warren D., E-mail: wdsou001@umaryland.edu [Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD (United States); Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States)

    2012-04-01

    Purpose: To determine how frequently (1) tumor motion and (2) the spatial relationship between tumor and respiratory surrogate markers change during a treatment fraction in lung and pancreas cancer patients. Methods and Materials: A Cyberknife Synchrony system radiographically localized the tumor and simultaneously tracked three respiratory surrogate markers fixed to a form-fitting vest. Data in 55 lung and 29 pancreas fractions were divided into successive 10-min blocks. Mean tumor positions and tumor position distributions were compared across 10-min blocks of data. Treatment margins were calculated from both 10 and 30 min of data. Partial least squares (PLS) regression models of tumor positions as a function of external surrogate marker positions were created from the first 10 min of data in each fraction; the incidence of significant PLS model degradation was used to assess changes in the spatial relationship between tumors and surrogate markers. Results: The absolute change in mean tumor position from first to third 10-min blocks was >5 mm in 13% and 7% of lung and pancreas cases, respectively. Superior-inferior and medial-lateral differences in mean tumor position were significantly associated with the lobe of lung. In 61% and 54% of lung and pancreas fractions, respectively, margins calculated from 30 min of data were larger than margins calculated from 10 min of data. The change in treatment margin magnitude for superior-inferior motion was >1 mm in 42% of lung and 45% of pancreas fractions. Significantly increasing tumor position prediction model error (mean {+-} standard deviation rates of change of 1.6 {+-} 2.5 mm per 10 min) over 30 min indicated tumor-surrogate relationship changes in 63% of fractions. Conclusions: Both tumor motion and the relationship between tumor and respiratory surrogate displacements change in most treatment fractions for patient in-room time of 30 min.

  19. Desorption of a methamphetamine surrogate from wallboard under remediation conditions

    Science.gov (United States)

    Poppendieck, Dustin; Morrison, Glenn; Corsi, Richard

    2015-04-01

    Thousands of homes in the United States are found to be contaminated with methamphetamine each year. Buildings used to produce illicit methamphetamine are typically remediated by removing soft furnishings and stained materials, cleaning and sometimes encapsulating surfaces using paint. Methamphetamine that has penetrated into paint films, wood and other permanent materials can be slowly released back into the building air over time, exposing future occupants and re-contaminating furnishings. The objective of this study was to determine the efficacy of two wallboard remediation techniques for homes contaminated with methamphetamine: 1) enhancing desorption by elevating temperature and relative humidity while ventilating the interior space, and 2) painting over affected wallboard to seal the methamphetamine in place. The emission of a methamphetamine surrogate, N-isopropylbenzylamine (NIBA), from pre-dosed wallboard chambers over 20 days at 32 °C and two values of relative humidity were studied. Emission rates from wallboard after 15 days at 32 °C ranged from 35 to 1400 μg h-1 m-2. Less than 22% of the NIBA was removed from the chambers over three weeks. Results indicate that elevating temperatures during remediation and latex painting of impacted wallboard will not significantly reduce freebase methamphetamine emissions from wallboard. Raising the relative humidity from 27% to 49% increased the emission rates by a factor of 1.4. A steady-state model of a typical home using the emission rates from this study and typical residential building parameters and conditions shows that adult inhalation reference doses for methamphetamine will be reached when approximately 1 g of methamphetamine is present in the wallboard of a house.

  20. Gating treatment delivery QA based on a surrogate motion analysis

    International Nuclear Information System (INIS)

    Chojnowski, J.; Simpson, E.

    2011-01-01

    Full text: To develop a methodology to estimate intrafractional target position error during a phase-based gated treatment. Westmead Cancer Care Centre is using respiratory correlated phase-based gated beam delivery in the treatment of lung cancer. The gating technique is managed by the Varian Real-time Position Management (RPM) system, version 1.7.5. A 6-dot block is placed on the abdomen of the patient and acts as a surrogate for the target motion. During a treatment session, the motion of the surrogate can be recorded by RPM application. Analysis of the surrogate motion file by in-house developed software allows the intrafractional error of the treatment session to be computed. To validate the computed error, a simple test that involves the introduction of deliberate errors is performed. Errors of up to 1.1 cm are introduced to a metal marker placed on a surrogate using the Varian Breathing Phantom. The moving marker was scanned in prospective mode using a GE Lightspeed 16 CT scanner. Using the CT images, a difference of the marker position with and without introduced errors is compared to the calculated errors based on the surrogate motion. The average and standard deviation of a difference between calculated target position errors and measured introduced artificial errors of the marker position is 0.02 cm and 0.07 cm respectively. Conclusion The calculated target positional error based on surrogate motion analysis provides a quantitative measure of intrafractional target positional errors during treatment. Routine QA for gated treatment using surrogate motion analysis is relatively quick and simple.

  1. On Techniques to Characterize and Correlate Grain Size, Grain Boundary Orientation and the Strength of the SiC Layer of TRISO Coated Particles: A Preliminary Study

    Energy Technology Data Exchange (ETDEWEB)

    I.J.van Rooyen; J.L. Dunzik Gougar; T. Trowbridge; Philip M van Rooyen

    2012-10-01

    The mechanical properties of the silicon carbide (SiC) layer of the TRi-ISOtropic (TRISO) coated particle (CP) for high temperature gas reactors (HTGR) are performance parameters that have not yet been standardized by the international HTR community. Presented in this paper are the results of characterizing coated particles to reveal the effect of annealing temperature (1000 to 2100°C) on the strength and grain size of unirradiated coated particles. This work was further expanded to include possible relationships between the grain size and strength values. The comparative results of two strength measurement techniques and grain size measured by the Lineal intercept method are included. Preliminary grain boundary characterization results determined by electron backscatter diffraction (EBSD) are included. These results are also important for future fission product transport studies, as grain boundary diffusion is identified as a possible mechanism by which 110mAg, one of the fission activation products, might be released through intact SiC layers. Temperature is a parameter known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. Recommendations and future work will also be briefly discussed.

  2. Uncertainty quantification for accident management using ACE surrogates

    International Nuclear Information System (INIS)

    Varuttamaseni, A.; Lee, J. C.; Youngblood, R. W.

    2012-01-01

    The alternating conditional expectation (ACE) regression method is used to generate RELAP5 surrogates which are then used to determine the distribution of the peak clad temperature (PCT) during the loss of feedwater accident coupled with a subsequent initiation of the feed and bleed (F and B) operation in the Zion-1 nuclear power plant. The construction of the surrogates assumes conditional independence relations among key reactor parameters. The choice of parameters to model is based on the macroscopic balance statements governing the behavior of the reactor. The peak clad temperature is calculated based on the independent variables that are known to be important in determining the success of the F and B operation. The relationship between these independent variables and the plant parameters such as coolant pressure and temperature is represented by surrogates that are constructed based on 45 RELAP5 cases. The time-dependent PCT for different values of F and B parameters is calculated by sampling the independent variables from their probability distributions and propagating the information through two layers of surrogates. The results of our analysis show that the ACE surrogates are able to satisfactorily reproduce the behavior of the plant parameters even though a quasi-static assumption is primarily used in their construction. The PCT is found to be lower in cases where the F and B operation is initiated, compared to the case without F and B, regardless of the F and B parameters used. (authors)

  3. Surrogate for oropharyngeal cancer HPV status in cancer database studies.

    Science.gov (United States)

    Megwalu, Uchechukwu C; Chen, Michelle M; Ma, Yifei; Divi, Vasu

    2017-12-01

    The utility of cancer databases for oropharyngeal cancer studies is limited by lack of information on human papillomavirus (HPV) status. The purpose of this study was to develop a surrogate that can be used to adjust for the effect of HPV status on survival. The study cohort included 6419 patients diagnosed with oropharyngeal squamous cell carcinoma between 2004 and 2012, identified in the National Cancer Database (NCDB). The HPV surrogate score was developed using a logistic regression model predicting HPV-positive status. The HPV surrogate score was predictive of HPV status (area under the curve [AUC] 0.73; accuracy of 70.4%). Similar to HPV-positive tumors, HPV surrogate positive tumors were associated with improved overall survival (OS; hazard ratio [HR] 0.73; 95% confidence interval [CI] 0.59-0.91; P = .005), after adjusting for important covariates. The HPV surrogate score is useful for adjusting for the effect of HPV status on survival in studies utilizing cancer databases. © 2017 Wiley Periodicals, Inc.

  4. Surrogate-Based Optimization of Biogeochemical Transport Models

    Science.gov (United States)

    Prieß, Malte; Slawig, Thomas

    2010-09-01

    First approaches towards a surrogate-based optimization method for a one-dimensional marine biogeochemical model of NPZD type are presented. The model, developed by Oschlies and Garcon [1], simulates the distribution of nitrogen, phytoplankton, zooplankton and detritus in a water column and is driven by ocean circulation data. A key issue is to minimize the misfit between the model output and given observational data. Our aim is to reduce the overall optimization cost avoiding expensive function and derivative evaluations by using a surrogate model replacing the high-fidelity model in focus. This in particular becomes important for more complex three-dimensional models. We analyse a coarsening in the discretization of the model equations as one way to create such a surrogate. Here the numerical stability crucially depends upon the discrete stepsize in time and space and the biochemical terms. We show that for given model parameters the level of grid coarsening can be choosen accordingly yielding a stable and satisfactory surrogate. As one example of a surrogate-based optimization method we present results of the Aggressive Space Mapping technique (developed by John W. Bandler [2, 3]) applied to the optimization of this one-dimensional biogeochemical transport model.

  5. Solubility of actinides and surrogates in nuclear glasses

    International Nuclear Information System (INIS)

    Lopez, Ch.

    2003-01-01

    The nuclear wastes are currently incorporated in borosilicate glass matrices. The resulting glass must be perfectly homogeneous. The work discussed here is a study of actinide (thorium and plutonium) solubility in borosilicate glass, undertaken to assess the extent of actinide solubility in the glass and to understand the mechanisms controlling actinide solubilization. Glass specimens containing; actinide surrogates were used to prepare and optimize the fabrication of radioactive glass samples. These preliminary studies revealed that actinide Surrogates solubility in the glass was enhanced by controlling the processing temperature, the dissolution kinetic of the surrogate precursors, the glass composition and the oxidizing versus reducing conditions. The actinide solubility was investigated in the borosilicate glass. The evolution of thorium solubility in borosilicate glass was determined for temperatures ranging from 1200 deg C to 1400 deg C.Borosilicate glass specimens containing plutonium were fabricated. The experimental result showed that the plutonium solubility limit ranged from 1 to 2.5 wt% PuO 2 at 1200 deg C. A structural approach based on the determination of the local structure around actinides and their surrogates by EXAFS spectroscopy was used to determine their structural role in the glass and the nature of their bonding with the vitreous network. This approach revealed a correlation between the length of these bonds and the solubility of the actinides and their surrogates. (author)

  6. A study on the smelting of electrolytically reduced spent fuel by using surrogates

    International Nuclear Information System (INIS)

    Hur, Jin-Mok; Jeong, Myoung-Soo; Cho, Soo-Haeng; Seo, Chung-Seok; Park, Seong-Won

    2005-01-01

    A smelting as a part of the advanced spent fuel conditioning process (ACP) was studied by using surrogate materials. Residual salts including LiCl-Li 2 O were successfully separated from the metal components by an evaporation at 950degC. The melting of the metal was characterized, especially by considering the oxidation of the fine metal particles. The operation procedure of the smelting was set up as 1) removal of residual salts, 2) melting of the metal powder, and 3) a solidification of the melted mass to an ingot. (author)

  7. Surrogate Model for Recirculation Phase LBLOCA and DET Application

    International Nuclear Information System (INIS)

    Fynan, Douglas A; Ahn, Kwang-Il; Lee, John C.

    2014-01-01

    In the nuclear safety field, response surfaces were used in the first demonstration of the code scaling, applicability, and uncertainty (CSAU) methodology to quantify the uncertainty of the peak clad temperature (PCT) during a large-break loss-of-coolant accident (LBLOCA). Surrogates could have applications in other nuclear safety areas such as dynamic probabilistic safety assessment (PSA). Dynamic PSA attempts to couple the probabilistic nature of failure events, component transitions, and human reliability to deterministic calculations of time-dependent nuclear power plant (NPP) responses usually through the use of thermal-hydraulic (TH) system codes. The overall mathematical complexity of the dynamic PSA architectures with many embedded computational expensive TH code calculations with large input/output data streams have limited realistic studies of NPPs. This paper presents a time-dependent surrogate model for the recirculation phase of a hot leg LBLOCA in the OPR-1000. The surrogate model is developed through the ACE algorithm, a powerful nonparametric regression technique, trained on RELAP5 simulations of the LBLOCA. Benchmarking of the surrogate is presented and an application to a simplified dynamic event tree (DET). A time-dependent surrogate model to predict core subcooling during the recirculation phase of a hot leg LBLOCA in the OPR-1000 has been developed. The surrogate assumed the structure of a general discrete time dynamic model and learned the nonlinear functional form by performing nonparametric regression on RELAP5 simulations with the ACE algorithm. The surrogate model input parameters represent mass and energy flux terms to the RCS that appeared as user supplied or code calculated boundary conditions in the RELAP5 model. The surrogate accurately predicted the TH behavior of the core for a variety of HPSI system performance and containment conditions when compared with RELAP5 simulations. The surrogate was applied in a DET application replacing

  8. Surrogate pregnancy: a guide for Canadian prenatal health care providers

    Science.gov (United States)

    Reilly, Dan R.

    2007-01-01

    Providing health care for a woman with a surrogate pregnancy involves unique challenges. Although the ethical debate surrounding surrogacy continues, Canada has banned commercial, but not altruistic, surrogacy. In the event of a custody dispute between a surrogate mother and the individual(s) intending to parent the child, it is unclear how Canadian courts would rule. The prenatal health care provider must take extra care to protect the autonomy and privacy rights of the surrogate. There is limited evidence about the medical and psychological risks ofsurrogacy. Whether theoretical concerns about these risks are clinically relevant remains unknown. In the face of these uncertainties, the prenatal health care provider should have a low threshold for seeking obstetrical, social work, ethical and legal support. PMID:17296962

  9. Surrogate pregnancy: a guide for Canadian prenatal health care providers.

    Science.gov (United States)

    Reilly, Dan R

    2007-02-13

    Providing health care for a woman with a surrogate pregnancy involves unique challenges. Although the ethical debate surrounding surrogacy continues, Canada has banned commercial, but not altruistic, surrogacy. In the event of a custody dispute between a surrogate mother and the individual(s) intending to parent the child, it is unclear how Canadian courts would rule. The prenatal health care provider must take extra care to protect the autonomy and privacy rights of the surrogate. There is limited evidence about the medical and psychological risks of surrogacy. Whether theoretical concerns about these risks are clinically relevant remains unknown. In the face of these uncertainties, the prenatal health care provider should have a low threshold for seeking obstetrical, social work, ethical and legal support.

  10. Surrogate marker evaluation from an information theory perspective.

    Science.gov (United States)

    Alonso, Ariel; Molenberghs, Geert

    2007-03-01

    The last 20 years have seen lots of work in the area of surrogate marker validation, partly devoted to frame the evaluation in a multitrial framework, leading to definitions in terms of the quality of trial- and individual-level association between a potential surrogate and a true endpoint (Buyse et al., 2000, Biostatistics 1, 49-67). A drawback is that different settings have led to different measures at the individual level. Here, we use information theory to create a unified framework, leading to a definition of surrogacy with an intuitive interpretation, offering interpretational advantages, and applicable in a wide range of situations. Our method provides a better insight into the chances of finding a good surrogate endpoint in a given situation. We further show that some of the previous proposals follow as special cases of our method. We illustrate our methodology using data from a clinical study in psychiatry.

  11. Disinfection byproduct regulatory compliance surrogates and bromide-associated risk.

    Science.gov (United States)

    Kolb, Chelsea; Francis, Royce A; VanBriesen, Jeanne M

    2017-08-01

    Natural and anthropogenic factors can alter bromide concentrations in drinking water sources. Increasing source water bromide concentrations increases the formation and alters the speciation of disinfection byproducts (DBPs) formed during drinking water treatment. Brominated DBPs are more toxic than their chlorinated analogs, and thus have a greater impact on human health. However, DBPs are regulated based on the mass sum of DBPs within a given class (e.g., trihalomethanes and haloacetic acids), not based on species-specific risk or extent of bromine incorporation. The regulated surrogate measures are intended to protect against not only the species they directly represent, but also against unregulated DBPs that are not routinely measured. Surrogates that do not incorporate effects of increasing bromide may not adequately capture human health risk associated with drinking water when source water bromide is elevated. The present study analyzes trihalomethanes (THMs), measured as TTHM, with varying source water bromide concentrations, and assesses its correlation with brominated THM, TTHM risk and species-specific THM concentrations and associated risk. Alternative potential surrogates are evaluated to assess their ability to capture THM risk under different source water bromide concentration conditions. The results of the present study indicate that TTHM does not adequately capture risk of the regulated species when source water bromide concentrations are elevated, and thus would also likely be an inadequate surrogate for many unregulated brominated species. Alternative surrogate measures, including THM 3 and the bromodichloromethane concentration, are more robust surrogates for species-specific THM risk at varying source water bromide concentrations. Copyright © 2017. Published by Elsevier B.V.

  12. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    Science.gov (United States)

    Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel

    2014-07-01

    We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a

  13. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    Directory of Open Access Journals (Sweden)

    Scott E. Field

    2014-07-01

    Full Text Available We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform’s value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mc_{fit} online operations, where c_{fit} denotes the fitting function operation count and, typically, m≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 10^{5}M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in

  14. Surrogate Endpoint Evaluation: Principal Stratification Criteria and the Prentice Definition.

    Science.gov (United States)

    Gilbert, Peter B; Gabriel, Erin E; Huang, Ying; Chan, Ivan S F

    2015-09-01

    A common problem of interest within a randomized clinical trial is the evaluation of an inexpensive response endpoint as a valid surrogate endpoint for a clinical endpoint, where a chief purpose of a valid surrogate is to provide a way to make correct inferences on clinical treatment effects in future studies without needing to collect the clinical endpoint data. Within the principal stratification framework for addressing this problem based on data from a single randomized clinical efficacy trial, a variety of definitions and criteria for a good surrogate endpoint have been proposed, all based on or closely related to the "principal effects" or "causal effect predictiveness (CEP)" surface. We discuss CEP-based criteria for a useful surrogate endpoint, including (1) the meaning and relative importance of proposed criteria including average causal necessity (ACN), average causal sufficiency (ACS), and large clinical effect modification; (2) the relationship between these criteria and the Prentice definition of a valid surrogate endpoint; and (3) the relationship between these criteria and the consistency criterion (i.e., assurance against the "surrogate paradox"). This includes the result that ACN plus a strong version of ACS generally do not imply the Prentice definition nor the consistency criterion, but they do have these implications in special cases. Moreover, the converse does not hold except in a special case with a binary candidate surrogate. The results highlight that assumptions about the treatment effect on the clinical endpoint before the candidate surrogate is measured are influential for the ability to draw conclusions about the Prentice definition or consistency. In addition, we emphasize that in some scenarios that occur commonly in practice, the principal strata sub-populations for inference are identifiable from the observable data, in which cases the principal stratification framework has relatively high utility for the purpose of effect

  15. The social context for surrogates' motivations and satisfaction.

    Science.gov (United States)

    Berend, Zsuzsa

    2014-10-01

    This Commentary takes up two of the main findings by Imrie and Jadva's study, namely surrogates' satisfaction with the post-surrogacy contact with intended parents and their motivation for surrogacy. It argues that the findings are in keeping with other qualitative research on surrogacy and that this similarity is not the result of the similarity of surrogates' psychological makeup. The Commentary highlights the centrality of social meanings and definitions, and following Howard Becker, insists on taking into account the collective doings that inform and shape individual feelings and behaviour. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  16. Surrogate Marker Evaluation from an Information Theory Perspective

    OpenAIRE

    Alonso Abad, Ariel; Molenberghs, Geert

    2006-01-01

    The last 20 years have seen lots of work in the area of surrogate marker validation, partly devoted to frame the evaluation in a multitrial framework, leading to definitions in terms of the quality of trial- and individual-level association between a potential surrogate and a true endpoint (Buyse et al., 2000, Biostatistics 1, 49–67). A drawback is that different settings have led to different measures at the individual level. Here, we use information theory to create a unified framework, lea...

  17. Surrogate Endpoint Evaluation: Principal Stratification Criteria and the Prentice Definition

    Science.gov (United States)

    Gilbert, Peter B.; Gabriel, Erin E.; Huang, Ying; Chan, Ivan S.F.

    2015-01-01

    A common problem of interest within a randomized clinical trial is the evaluation of an inexpensive response endpoint as a valid surrogate endpoint for a clinical endpoint, where a chief purpose of a valid surrogate is to provide a way to make correct inferences on clinical treatment effects in future studies without needing to collect the clinical endpoint data. Within the principal stratification framework for addressing this problem based on data from a single randomized clinical efficacy trial, a variety of definitions and criteria for a good surrogate endpoint have been proposed, all based on or closely related to the “principal effects” or “causal effect predictiveness (CEP)” surface. We discuss CEP-based criteria for a useful surrogate endpoint, including (1) the meaning and relative importance of proposed criteria including average causal necessity (ACN), average causal sufficiency (ACS), and large clinical effect modification; (2) the relationship between these criteria and the Prentice definition of a valid surrogate endpoint; and (3) the relationship between these criteria and the consistency criterion (i.e., assurance against the “surrogate paradox”). This includes the result that ACN plus a strong version of ACS generally do not imply the Prentice definition nor the consistency criterion, but they do have these implications in special cases. Moreover, the converse does not hold except in a special case with a binary candidate surrogate. The results highlight that assumptions about the treatment effect on the clinical endpoint before the candidate surrogate is measured are influential for the ability to draw conclusions about the Prentice definition or consistency. In addition, we emphasize that in some scenarios that occur commonly in practice, the principal strata sub-populations for inference are identifiable from the observable data, in which cases the principal stratification framework has relatively high utility for the purpose of

  18. Magnetic Resonance Imaging–Guided versus Surrogate-Based Motion Tracking in Liver Radiation Therapy: A Prospective Comparative Study

    Energy Technology Data Exchange (ETDEWEB)

    Paganelli, Chiara, E-mail: chiara.paganelli@polimi.it [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Seregni, Matteo; Fattori, Giovanni [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Summers, Paul [Division of Radiology, Istituto Europeo di Oncologia, Milano (Italy); Bellomi, Massimo [Division of Radiology, Istituto Europeo di Oncologia, Milano (Italy); Department of Health Sciences, Università degli Studi di Milano, Milano (Italy); Baroni, Guido; Riboldi, Marco [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Bioengineering Unit, CNAO Foundation, Pavia (Italy)

    2015-03-15

    Purpose: This study applied automatic feature detection on cine–magnetic resonance imaging (MRI) liver images in order to provide a prospective comparison between MRI-guided and surrogate-based tracking methods for motion-compensated liver radiation therapy. Methods and Materials: In a population of 30 subjects (5 volunteers plus 25 patients), 2 oblique sagittal slices were acquired across the liver at high temporal resolution. An algorithm based on scale invariant feature transform (SIFT) was used to extract and track multiple features throughout the image sequence. The position of abdominal markers was also measured directly from the image series, and the internal motion of each feature was quantified through multiparametric analysis. Surrogate-based tumor tracking with a state-of-the-art external/internal correlation model was simulated. The geometrical tracking error was measured, and its correlation with external motion parameters was also investigated. Finally, the potential gain in tracking accuracy relying on MRI guidance was quantified as a function of the maximum allowed tracking error. Results: An average of 45 features was extracted for each subject across the whole liver. The multi-parametric motion analysis reported relevant inter- and intrasubject variability, highlighting the value of patient-specific and spatially-distributed measurements. Surrogate-based tracking errors (relative to the motion amplitude) were were in the range 7% to 23% (1.02-3.57mm) and were significantly influenced by external motion parameters. The gain of MRI guidance compared to surrogate-based motion tracking was larger than 30% in 50% of the subjects when considering a 1.5-mm tracking error tolerance. Conclusions: Automatic feature detection applied to cine-MRI allows detailed liver motion description to be obtained. Such information was used to quantify the performance of surrogate-based tracking methods and to provide a prospective comparison with respect to MRI

  19. Mapping surrogate gasoline compositions into RON/MON space

    NARCIS (Netherlands)

    Morgan, N.; Smallbone, A.; Bhave, A.; Kraft, M.; Cracknell, R.; Kalghatgi, G.T.

    2010-01-01

    In this paper, new experimentally determined octane numbers (RON and MON) of blends of a tri-component surrogate consisting of toluene, n-heptane, i-octane (called toluene reference fuel TRF) arranged in an augmented simplex design are used to derive a simple response surface model for the octane

  20. Frequency response as a surrogate eigenvalue problem in topology optimization

    DEFF Research Database (Denmark)

    Andreassen, Erik; Ferrari, Federico; Sigmund, Ole

    2018-01-01

    This article discusses the use of frequency response surrogates for eigenvalue optimization problems in topology optimization that may be used to avoid solving the eigenvalue problem. The motivation is to avoid complications that arise from multiple eigenvalues and the computational complexity as...

  1. Development of Cranial Bone Surrogate Structures Using Stereolithographic Additive Manufacturing

    Science.gov (United States)

    2017-09-29

    Additive Manufacturing by Jared M Gardner and Thomas A Plaisted Approved for public release; distribution is unlimited...Laboratory Development of Cranial Bone Surrogate Structures Using Stereolithographic Additive Manufacturing by Thomas A Plaisted Weapons...Structures Using Stereolithographic Additive Manufacturing 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Jared

  2. Predicting freshwater habitat integrity using land-use surrogates

    African Journals Online (AJOL)

    2007-04-02

    Apr 2, 2007 ... Quantification of potential surrogates of freshwater habitat integrity. We chose a series of land-use variables that might be suitable predictors for assessing freshwater habitat integrity from the land cover map (CSIR 2005) and added separate GIS surfaces for human population density and the distribution of ...

  3. Summary of Remediated Nitrate Salt Surrogate Formulation and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Geoffrey Wayne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leonard, Philip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hartline, Ernest Leon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tian, Hongzhao [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    High Explosives Science and Technology (M-7) completed all required formulation and testing of Remediated Nitrate Salt (RNS) surrogates on April 27, 2016 as specified in PLAN-TA9-2443 Rev B, "Remediated Nitrate Salt (RNS) Surrogate Formulation and Testing Standard Procedure", released February 16, 2016. This report summarizes the results of the work and also includes additional documentation required in that test plan. All formulation and testing was carried out according to PLAN-TA9-2443 Rev B. The work was carried out in three rounds, with the full matrix of samples formulated and tested in each round. Results from the first round of formulation and testing were documented in memorandum M7-J6-6042, " Results from First Round of Remediated Nitrate Salt Surrogate Formulation and Testing." Results from the second round of formulation and testing were documented in M7-16-6053 , "Results from the Second Round of Remediated Nitrate Salt Surrogate Formulation and Testing." Initial results from the third round were documented in M7-16-6057, "Initial Results from the Third Round of Remediated Nitrate Salt Formulation and Testing."

  4. Surrogate motherhood in illness that does not cause infertility ...

    African Journals Online (AJOL)

    The threshold requirement for surrogate motherhood requires that a commissioning parent or parents are permanently unable to give birth to a child. The question has arisen of a commissioning mother who suffers from a permanent illness that does not cause infertility but that renders pregnancy a significant health risk to ...

  5. Plan of development of ZrC-TRISO coated fuel particle and construction of ZrC coater

    Energy Technology Data Exchange (ETDEWEB)

    Ueta, Shohei; Ino, Hiroichi; Sawa, Kazuhiro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tobita, Tsutomu [Nuclear Engineering Company, Ltd., Tokai, Ibaraki (Japan); Takahashi, Masashi [Nuclear Fuel Industries, Ltd., Tokyo (Japan)

    2002-11-01

    In order to use coated fuel particle under higher temperature condition, more refractory coating material, which is more refractory than conventional silicon carbide (SiC), should be applied. Zirconium carbide (ZrC) is considered to be one of the promising materials, which is proposed as candidate for VHTR fuel material in GENERATION-IV, because of its intactness under high temperature of around 2000degC and its higher stability against kernel migration (amoeba effect) and fission product corrosion under normal operating condition. In order to develop ZrC coated particle for commercial use, research and development items were extracted based on review of the previous works. Research and development plan was determined. Based on the plan, a new ZrC coater of 100g batch size, which applies bromine process, was constructed. This report describes the review of precious works, extracted research and develop items and plan, and specifications of the ZrC coater. (author)

  6. Production of Depleted UO2Kernels for the Advanced Gas-Cooled Reactor Program for Use in TRISO Coating Development

    Energy Technology Data Exchange (ETDEWEB)

    Collins, J.L.

    2004-12-02

    The main objective of the Depleted UO{sub 2} Kernels Production Task at Oak Ridge National Laboratory (ORNL) was to conduct two small-scale production campaigns to produce 2 kg of UO{sub 2} kernels with diameters of 500 {+-} 20 {micro}m and 3.5 kg of UO{sub 2} kernels with diameters of 350 {+-} 10 {micro}m for the U.S. Department of Energy Advanced Fuel Cycle Initiative Program. The final acceptance requirements for the UO{sub 2} kernels are provided in the first section of this report. The kernels were prepared for use by the ORNL Metals and Ceramics Division in a development study to perfect the triisotropic (TRISO) coating process. It was important that the kernels be strong and near theoretical density, with excellent sphericity, minimal surface roughness, and no cracking. This report gives a detailed description of the production efforts and results as well as an in-depth description of the internal gelation process and its chemistry. It describes the laboratory-scale gel-forming apparatus, optimum broth formulation and operating conditions, preparation of the acid-deficient uranyl nitrate stock solution, the system used to provide uniform broth droplet formation and control, and the process of calcining and sintering UO{sub 3} {center_dot} 2H{sub 2}O microspheres to form dense UO{sub 2} kernels. The report also describes improvements and best past practices for uranium kernel formation via the internal gelation process, which utilizes hexamethylenetetramine and urea. Improvements were made in broth formulation and broth droplet formation and control that made it possible in many of the runs in the campaign to produce the desired 350 {+-} 10-{micro}m-diameter kernels, and to obtain very high yields.

  7. Recent Progress in the Development of Diesel Surrogate Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W J; Mueller, C J

    2009-12-09

    There has been much recent progress in the area of surrogate fuels for diesel. In the last few years, experiments and modeling have been performed on higher molecular weight components of relevance to diesel fuel such as n-hexadecane (n-cetane) and 2,2,4,4,6,8,8-heptamethylnonane (iso-cetane). Chemical kinetic models have been developed for all the n-alkanes up to 16 carbon atoms. Also, there has been much experimental and modeling work on lower molecular weight surrogate components such as n-decane and n-dodecane that are most relevant to jet fuel surrogates, but are also relevant to diesel surrogates where simulation of the full boiling point range is desired. For two-ring compounds, experimental work on decalin and tetralin recently has been published. For multi-component surrogate fuel mixtures, recent work on modeling of these mixtures and comparisons to real diesel fuel is reviewed. Detailed chemical kinetic models for surrogate fuels are very large in size. Significant progress also has been made in improving the mechanism reduction tools that are needed to make these large models practicable in multi-dimensional reacting flow simulations of diesel combustion. Nevertheless, major research gaps remain. In the case of iso-alkanes, there are experiments and modeling work on only one of relevance to diesel: iso-cetane. Also, the iso-alkanes in diesel are lightly branched and no detailed chemical kinetic models or experimental investigations are available for such compounds. More components are needed to fill out the iso-alkane boiling point range. For the aromatic class of compounds, there has been no new work for compounds in the boiling point range of diesel. Most of the new work has been on alkyl aromatics that are of the range C7 to C8, below the C10 to C20 range that is needed. For the chemical class of cycloalkanes, experiments and modeling on higher molecular weight components are warranted. Finally for multi-component surrogates needed to treat real

  8. Hall et al., 2016 Artificial Turf Surrogate Surface Methods Paper Data File

    Data.gov (United States)

    U.S. Environmental Protection Agency — Mercury dry deposition data quantified via static water surrogate surface (SWSS) and artificial turf surrogate surface (ATSS) collectors. This dataset is associated...

  9. Multi-model polynomial chaos surrogate dictionary for Bayesian inference in elasticity problems

    KAUST Repository

    Contreras, Andres A.; Le Maî tre, Olivier P.; Aquino, Wilkins; Knio, Omar

    2016-01-01

    of stiff inclusions embedded in a soft matrix, mimicking tumors in soft tissues. We rely on a polynomial chaos (PC) surrogate to accelerate the inference process. The PC surrogate predicts the dependence of the displacements field with the random elastic

  10. Global Optimization Employing Gaussian Process-Based Bayesian Surrogates

    Directory of Open Access Journals (Sweden)

    Roland Preuss

    2018-03-01

    Full Text Available The simulation of complex physics models may lead to enormous computer running times. Since the simulations are expensive it is necessary to exploit the computational budget in the best possible manner. If for a few input parameter settings an output data set has been acquired, one could be interested in taking these data as a basis for finding an extremum and possibly an input parameter set for further computer simulations to determine it—a task which belongs to the realm of global optimization. Within the Bayesian framework we utilize Gaussian processes for the creation of a surrogate model function adjusted self-consistently via hyperparameters to represent the data. Although the probability distribution of the hyperparameters may be widely spread over phase space, we make the assumption that only the use of their expectation values is sufficient. While this shortcut facilitates a quickly accessible surrogate, it is somewhat justified by the fact that we are not interested in a full representation of the model by the surrogate but to reveal its maximum. To accomplish this the surrogate is fed to a utility function whose extremum determines the new parameter set for the next data point to obtain. Moreover, we propose to alternate between two utility functions—expected improvement and maximum variance—in order to avoid the drawbacks of each. Subsequent data points are drawn from the model function until the procedure either remains in the points found or the surrogate model does not change with the iteration. The procedure is applied to mock data in one and two dimensions in order to demonstrate proof of principle of the proposed approach.

  11. Comparative Virucidal Efficacy of Seven Disinfectants Against Murine Norovirus and Feline Calicivirus, Surrogates of Human Norovirus.

    Science.gov (United States)

    Zonta, William; Mauroy, Axel; Farnir, Frederic; Thiry, Etienne

    2016-03-01

    Human noroviruses (HuNoV) are the leading cause of acute non-bacterial gastroenteritis in humans and can be transmitted either by person-to-person contact or by consumption of contaminated food. A knowledge of an efficient disinfection for both hands and food-contact surfaces is helpful for the food sector and provides precious information for public health. The aim of this study was to evaluate the effect of seven disinfectants belonging to different groups of biocides (alcohol, halogen, oxidizing agents, quaternary ammonium compounds, aldehyde and biguanide) on infectious viral titre and on genomic copy number. Due to the absence of a cell culture system for HuNoV, two HuNoV surrogates, such as murine norovirus and feline calicivirus, were used and the tests were performed in suspension, on gloves and on stainless steel discs. When, as criteria of efficacy, a log reduction >3 of the infectious viral titre on both surrogates and in the three tests is used, the most efficacious disinfectants in this study appear to be biocidal products B, C and D, representing the halogens, the oxidizing agents group and a mix of QAC, alcohol and aldehyde, respectively. In addition, these three disinfectants also elicited a significant effect on genomic copy number for both surrogate viruses and in all three tests. The results of this study demonstrate that a halogen compound, oxidizing agents and a mix of QAC, alcohol and aldehyde are advisable for HuNoV disinfection of either potentially contaminated surfaces or materials in contact with foodstuffs.

  12. Traces of humanity: Echoes of social and cultural experience in physical objects and digital surrogates in the University of Victoria Libraries

    Directory of Open Access Journals (Sweden)

    Robbyn Gordon Lanning

    2016-12-01

    Full Text Available The relationships between primary source materials and their digital surrogates warrant consideration about how different materials translate into digitized forms. Physical primary source materials found in library special collections and archives and their digital surrogates challenge the viewer to consider what these objects are communicating through their materiality or lack thereof. For example, how does a clay tablet represent itself digitally, as compared to a parchment manuscript, or a paper accounts book? What qualities, stories or narratives do these resources communicate in their original forms, as digital surrogates, or when engaged with together, and how do these differ? How do both physical and digital resources serve as archival objects with the ability to reflect our social and cultural experiences—and indeed our humanity—back to us? As more and more library and museum resources are digitized and made open to researchers, such questions must be addressed as the use and reuse of digital surrogates becomes increasingly complex as digital scholarship evolves.

  13. Summary of Remediated and Unremediated Nitrate Salt Surrogate Testing in Support of the Waste Treatment Permit Application to the New Mexico Environment Department (NMED)

    Energy Technology Data Exchange (ETDEWEB)

    Funk, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-22

    The inadvertent creation of transuranic waste carrying hazardous waste codes D001 and D002 requires the treatment of the material to eliminate the hazardous characteristics and allow its eventual shipment and disposal at the Waste Isolation Pilot Plant (WIPP). This report briefly summarizes the surrogate testing that was done in support of our understanding of this waste form.

  14. Is Diaphragm Motion a Good Surrogate for Liver Tumor Motion?

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Juan [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); School of Information Science and Engineering, Shandong University, Jinan, Shandong (China); Cai, Jing [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Wang, Hongjun [School of Information Science and Engineering, Shandong University, Jinan, Shandong (China); Chang, Zheng; Czito, Brian G. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Bashir, Mustafa R. [Department of Radiology, Duke University Medical Center, Durham, North Carolina (United States); Palta, Manisha [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yin, Fang-Fang, E-mail: fangfang.yin@duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2014-11-15

    Purpose: To evaluate the relationship between liver tumor motion and diaphragm motion. Methods and Materials: Fourteen patients with hepatocellular carcinoma (10 of 14) or liver metastases (4 of 14) undergoing radiation therapy were included in this study. All patients underwent single-slice cine–magnetic resonance imaging simulations across the center of the tumor in 3 orthogonal planes. Tumor and diaphragm motion trajectories in the superior–inferior (SI), anterior–posterior (AP), and medial–lateral (ML) directions were obtained using an in-house-developed normalized cross-correlation–based tracking technique. Agreement between the tumor and diaphragm motion was assessed by calculating phase difference percentage, intraclass correlation coefficient, and Bland-Altman analysis (Diff). The distance between the tumor and tracked diaphragm area was analyzed to understand its impact on the correlation between the 2 motions. Results: Of all patients, the mean (±standard deviation) phase difference percentage values were 7.1% ± 1.1%, 4.5% ± 0.5%, and 17.5% ± 4.5% in the SI, AP, and ML directions, respectively. The mean intraclass correlation coefficient values were 0.98 ± 0.02, 0.97 ± 0.02, and 0.08 ± 0.06 in the SI, AP, and ML directions, respectively. The mean Diff values were 2.8 ± 1.4 mm, 2.4 ± 1.1 mm, and 2.2 ± 0.5 mm in the SI, AP, and ML directions, respectively. Tumor and diaphragm motions had high concordance when the distance between the tumor and tracked diaphragm area was small. Conclusions: This study showed that liver tumor motion had good correlation with diaphragm motion in the SI and AP directions, indicating diaphragm motion in the SI and AP directions could potentially be used as a reliable surrogate for liver tumor motion.

  15. Engineered Option Treatment of Remediated Nitrate Salts: Surrogate Batch-Blending Testing

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    This report provides results from batch-blending test work for remediated nitrate salt (RNS) treatment. Batch blending was identified as a preferred option for blending RNS and unremediated nitrate salt (UNS) material with zeolite to effectively safe the salt/Swheat material identified as ignitable (U.S. Environmental Protection Agency code D001). Blending with zeolite was the preferred remediation option identified in the Options Assessment Report and was originally proposed as the best option for remediation by Clark and Funk in their report, Chemical Reactivity and Recommended Remediation Strategy for Los Alamos Remediated Nitrate Salt (RNS) Wastes, and also found to be a preferred option in the Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing. This test work evaluated equipment and recipe alternatives to achieve effective blending of surrogate waste with zeolite.

  16. Sepia ink as a surrogate for colloid transport tests in porous media

    Science.gov (United States)

    Soto-Gómez, Diego; Pérez-Rodríguez, Paula; López-Periago, J. Eugenio; Paradelo, Marcos

    2016-08-01

    We examined the suitability of the ink of Sepia officinalis as a surrogate for transport studies of microorganisms and microparticles in porous media. Sepia ink is an organic pigment consisted on a suspension of eumelanin, and that has several advantages for its use as a promising material for introducing the frugal-innovation in the fields of public health and environmental research: very low cost, non-toxic, spherical shape, moderate polydispersivity, size near large viruses, non-anomalous electrokinetic behavior, low retention in the soil, and high stability. Electrokinetic determinations and transport experiments in quartz sand columns and soil columns were done with purified suspensions of sepia ink. Influence of ionic strength on the electrophoretic mobility of ink particles showed the typical behavior of polystyrene latex spheres. Breakthrough curve (BTC) and retention profile (RP) in quartz sand columns showed a depth dependent and blocking adsorption model with an increase in adsorption rates with the ionic strength. Partially saturated transport through undisturbed soil showed less retention than in quartz sand, and matrix exclusion was also observed. Quantification of ink in leachate fractions by light absorbance is direct, but quantification in the soil profile with moderate to high organic matter content was rather cumbersome. We concluded that sepia ink is a suitable cheap surrogate for exploring transport of pathogenic viruses, bacteria and particulate contaminants in groundwater, and could be used for developing frugal-innovation related with the assessment of soil and aquifer filtration function, and monitoring of water filtration systems in low-income regions.

  17. Multi-model polynomial chaos surrogate dictionary for Bayesian inference in elasticity problems

    KAUST Repository

    Contreras, Andres A.

    2016-09-19

    A method is presented for inferring the presence of an inclusion inside a domain; the proposed approach is suitable to be used in a diagnostic device with low computational power. Specifically, we use the Bayesian framework for the inference of stiff inclusions embedded in a soft matrix, mimicking tumors in soft tissues. We rely on a polynomial chaos (PC) surrogate to accelerate the inference process. The PC surrogate predicts the dependence of the displacements field with the random elastic moduli of the materials, and are computed by means of the stochastic Galerkin (SG) projection method. Moreover, the inclusion\\'s geometry is assumed to be unknown, and this is addressed by using a dictionary consisting of several geometrical models with different configurations. A model selection approach based on the evidence provided by the data (Bayes factors) is used to discriminate among the different geometrical models and select the most suitable one. The idea of using a dictionary of pre-computed geometrical models helps to maintain the computational cost of the inference process very low, as most of the computational burden is carried out off-line for the resolution of the SG problems. Numerical tests are used to validate the methodology, assess its performance, and analyze the robustness to model errors. © 2016 Elsevier Ltd

  18. Successful surrogate pregnancy after ovarian transposition, pelvic irradiation and hysterectomy.

    Science.gov (United States)

    Zinger, Michael; Liu, James H; Husseinzadeh, Nader; Thomas, Michael A

    2004-07-01

    Treatment of cervical cancer is often effective but at the cost of the woman's fertility. Ovarian transposition with subsequent oocyte retrieval and surrogate pregnancy can enable these patients to become genetic parents. We present the third reported such case. A 22-year-old woman was diagnosed with bulky, stage IB cervical cancer. Following transposition of both ovaries to the upper abdomen, she underwent pelvic irradiation followed by total abdominal hysterectomy. Eleven years later she presented for assisted reproduction. Two oocytes were retrieved following ovarian stimulation and transcutaneous, abdominal oocyte retrieval. One embryo was transferred to the gestational surrogate, resulting in a single intrauterine pregnancy and successful delivery at term. These procedures can preservefertility while successfully treating cervical cancer.

  19. Emulating facial biomechanics using multivariate partial least squares surrogate models.

    Science.gov (United States)

    Wu, Tim; Martens, Harald; Hunter, Peter; Mithraratne, Kumar

    2014-11-01

    A detailed biomechanical model of the human face driven by a network of muscles is a useful tool in relating the muscle activities to facial deformations. However, lengthy computational times often hinder its applications in practical settings. The objective of this study is to replace precise but computationally demanding biomechanical model by a much faster multivariate meta-model (surrogate model), such that a significant speedup (to real-time interactive speed) can be achieved. Using a multilevel fractional factorial design, the parameter space of the biomechanical system was probed from a set of sample points chosen to satisfy maximal rank optimality and volume filling. The input-output relationship at these sampled points was then statistically emulated using linear and nonlinear, cross-validated, partial least squares regression models. It was demonstrated that these surrogate models can mimic facial biomechanics efficiently and reliably in real-time. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Counterfactual reasoning in surrogate decision making -- another look.

    Science.gov (United States)

    Johansson, Mats; Broström, Linus

    2011-06-01

    Incompetent patients need to have someone else make decisions on their behalf. According to the Substituted Judgment Standard the surrogate decision maker ought to make the decision that the patient would have made, had he or she been competent. Objections have been raised against this traditional construal of the standard on the grounds that it involves flawed counterfactual reasoning, and amendments have been suggested within the framework of possible worlds semantics. The paper shows that while this approach may circumvent the alleged problem, the way it has so far been elaborated reflects insufficient understanding of the moral underpinnings of the idea of substituted judgment. Proper recognition of these moral underpinnings has potentially far-reaching implications for our normative assumptions about accuracy and objectivity in surrogate decision making.

  1. A Parallel and Distributed Surrogate Model Implementation for Computational Steering

    KAUST Repository

    Butnaru, Daniel

    2012-06-01

    Understanding the influence of multiple parameters in a complex simulation setting is a difficult task. In the ideal case, the scientist can freely steer such a simulation and is immediately presented with the results for a certain configuration of the input parameters. Such an exploration process is however not possible if the simulation is computationally too expensive. For these cases we present in this paper a scalable computational steering approach utilizing a fast surrogate model as substitute for the time-consuming simulation. The surrogate model we propose is based on the sparse grid technique, and we identify the main computational tasks associated with its evaluation and its extension. We further show how distributed data management combined with the specific use of accelerators allows us to approximate and deliver simulation results to a high-resolution visualization system in real-time. This significantly enhances the steering workflow and facilitates the interactive exploration of large datasets. © 2012 IEEE.

  2. Toward a psychology of surrogate decision-making

    OpenAIRE

    Tunney, Richard J.; Ziegler, Fenja

    2016-01-01

    Many of the decisions that we make in everyday life are made for the benefit of other people. However, research suggests that people often make decisions on behalf of other people that are different from those that the other person would choose for himself or herself. This raises practical problems in the case of legally designated surrogate decision-makers who may not meet the legal normative benchmark — the substituted judgment standard. We review evidence from our own ...

  3. Current issues on a standard for surrogate pregnancy procedures

    OpenAIRE

    Ha, Jung-Ok

    2012-01-01

    While Korea does not have any legal statement on surrogacy, treatments are carried out in practice. As a result, every Institutional Review Board (IRB) of each fertility clinic faces an ethical predicament in reviewing each case. There is a need to arrange the institutions' own standards of surrogate pregnancy procedures before the establishment of national or professional regulation. This article examines the legal, social, and medical issues of surrogacy to help IRBs to judge their cases.

  4. Current issues on a standard for surrogate pregnancy procedures.

    Science.gov (United States)

    Ha, Jung-Ok

    2012-12-01

    While Korea does not have any legal statement on surrogacy, treatments are carried out in practice. As a result, every Institutional Review Board (IRB) of each fertility clinic faces an ethical predicament in reviewing each case. There is a need to arrange the institutions' own standards of surrogate pregnancy procedures before the establishment of national or professional regulation. This article examines the legal, social, and medical issues of surrogacy to help IRBs to judge their cases.

  5. Mexican Surrogates and the Concept of Reproductive Labor

    Directory of Open Access Journals (Sweden)

    María Eugenia Olavarría Patiño

    2018-01-01

    Full Text Available This article explores the meanings of surrogacy motherhood in Mexico throughout its actor’s practices and author’s discourses. The comparisons and analogies established with the mother, the nurse, the concubine and the prostitute are now confronted with testimonies based on an ethnographic fieldwork developed by the 2016. Finally, this article proposes that surrogates women, as a relative modern character, can be understood as a face of the reproductive labor sequence.

  6. ACOG committee opinion number 397, February 2008: surrogate motherhood.

    Science.gov (United States)

    2008-02-01

    Ethical responsibilities are described for obstetrician-gynecologists who choose to participate in surrogacy arrangements by 1) advising couples who are considering surrogacy, 2) counseling potential surrogate mothers, 3) providing obstetric services for pregnant women participating in surrogacy, or 4) offering assisted reproductive technologies related to surrogacy. Although the obligations of physicians will vary depending on the type and level of their involvement, in all cases physicians should carefully examine all relevant issues related to surrogacy, including medical, ethical, legal, and psychologic aspects.

  7. Commercial agencies and surrogate motherhood: a transaction cost approach.

    Science.gov (United States)

    Galbraith, Mhairi; McLachlan, Hugh V; Swales, J Kim

    2005-03-01

    In this paper we investigate the legal arrangements involved in UK surrogate motherhood from a transaction-cost perspective. We outline the specific forms the transaction costs take and critically comment on the way in which the UK institutional and organisational arrangements at present adversely influence transaction costs. We then focus specifically on the potential role of surrogacy agencies and look at UK and US evidence on commercial and voluntary agencies. Policy implications follow.

  8. Regression calibration with more surrogates than mismeasured variables

    KAUST Repository

    Kipnis, Victor

    2012-06-29

    In a recent paper (Weller EA, Milton DK, Eisen EA, Spiegelman D. Regression calibration for logistic regression with multiple surrogates for one exposure. Journal of Statistical Planning and Inference 2007; 137: 449-461), the authors discussed fitting logistic regression models when a scalar main explanatory variable is measured with error by several surrogates, that is, a situation with more surrogates than variables measured with error. They compared two methods of adjusting for measurement error using a regression calibration approximate model as if it were exact. One is the standard regression calibration approach consisting of substituting an estimated conditional expectation of the true covariate given observed data in the logistic regression. The other is a novel two-stage approach when the logistic regression is fitted to multiple surrogates, and then a linear combination of estimated slopes is formed as the estimate of interest. Applying estimated asymptotic variances for both methods in a single data set with some sensitivity analysis, the authors asserted superiority of their two-stage approach. We investigate this claim in some detail. A troubling aspect of the proposed two-stage method is that, unlike standard regression calibration and a natural form of maximum likelihood, the resulting estimates are not invariant to reparameterization of nuisance parameters in the model. We show, however, that, under the regression calibration approximation, the two-stage method is asymptotically equivalent to a maximum likelihood formulation, and is therefore in theory superior to standard regression calibration. However, our extensive finite-sample simulations in the practically important parameter space where the regression calibration model provides a good approximation failed to uncover such superiority of the two-stage method. We also discuss extensions to different data structures.

  9. Regression calibration with more surrogates than mismeasured variables

    KAUST Repository

    Kipnis, Victor; Midthune, Douglas; Freedman, Laurence S.; Carroll, Raymond J.

    2012-01-01

    In a recent paper (Weller EA, Milton DK, Eisen EA, Spiegelman D. Regression calibration for logistic regression with multiple surrogates for one exposure. Journal of Statistical Planning and Inference 2007; 137: 449-461), the authors discussed fitting logistic regression models when a scalar main explanatory variable is measured with error by several surrogates, that is, a situation with more surrogates than variables measured with error. They compared two methods of adjusting for measurement error using a regression calibration approximate model as if it were exact. One is the standard regression calibration approach consisting of substituting an estimated conditional expectation of the true covariate given observed data in the logistic regression. The other is a novel two-stage approach when the logistic regression is fitted to multiple surrogates, and then a linear combination of estimated slopes is formed as the estimate of interest. Applying estimated asymptotic variances for both methods in a single data set with some sensitivity analysis, the authors asserted superiority of their two-stage approach. We investigate this claim in some detail. A troubling aspect of the proposed two-stage method is that, unlike standard regression calibration and a natural form of maximum likelihood, the resulting estimates are not invariant to reparameterization of nuisance parameters in the model. We show, however, that, under the regression calibration approximation, the two-stage method is asymptotically equivalent to a maximum likelihood formulation, and is therefore in theory superior to standard regression calibration. However, our extensive finite-sample simulations in the practically important parameter space where the regression calibration model provides a good approximation failed to uncover such superiority of the two-stage method. We also discuss extensions to different data structures.

  10. Evaluation of bone surrogates for indirect and direct ballistic fractures.

    Science.gov (United States)

    Bir, Cynthia; Andrecovich, Chris; DeMaio, Marlene; Dougherty, Paul J

    2016-04-01

    The mechanism of injury for fractures to long bones has been studied for both direct ballistic loading as well as indirect. However, the majority of these studies have been conducted on both post-mortem human subjects (PMHS) and animal surrogates which have constraints in terms of storage, preparation and testing. The identification of a validated bone surrogate for use in forensic, medical and engineering testing would provide the ability to investigate ballistic loading without these constraints. Two specific bone surrogates, Sawbones and Synbone, were evaluated in comparison to PMHS for both direct and indirect ballistic loading. For the direct loading, the mean velocity to produce fracture was 121 ± 19 m/s for the PMHS, which was statistically different from the Sawbones (140 ± 7 m/s) and Synbone (146 ± 3 m/s). The average distance to fracture in the indirect loading was .70 cm for the PMHS. The Synbone had a statistically similar average distance to fracture (.61 cm, p=0.54) however the Sawbones average distance to fracture was statistically different (.41 cm, pballistic testing was not identified and future work is warranted. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Progress in Chemical Kinetic Modeling for Surrogate Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W J; Westbrook, C K; Herbinet, O; Silke, E J

    2008-06-06

    Gasoline, diesel, and other alternative transportation fuels contain hundreds to thousands of compounds. It is currently not possible to represent all these compounds in detailed chemical kinetic models. Instead, these fuels are represented by surrogate fuel models which contain a limited number of representative compounds. We have been extending the list of compounds for detailed chemical models that are available for use in fuel surrogate models. Detailed models for components with larger and more complicated fuel molecular structures are now available. These advancements are allowing a more accurate representation of practical and alternative fuels. We have developed detailed chemical kinetic models for fuels with higher molecular weight fuel molecules such as n-hexadecane (C16). Also, we can consider more complicated fuel molecular structures like cyclic alkanes and aromatics that are found in practical fuels. For alternative fuels, the capability to model large biodiesel fuels that have ester structures is becoming available. These newly addressed cyclic and ester structures in fuels profoundly affect the reaction rate of the fuel predicted by the model. Finally, these surrogate fuel models contain large numbers of species and reactions and must be reduced for use in multi-dimensional models for spark-ignition, HCCI and diesel engines.

  12. Overview of Biomarkers and Surrogate Endpoints in Drug Development

    Directory of Open Access Journals (Sweden)

    John A. Wagner

    2002-01-01

    Full Text Available There are numerous factors that recommend the use of biomarkers in drug development including the ability to provide a rational basis for selection of lead compounds, as an aid in determining or refining mechanism of action or pathophysiology, and the ability to work towards qualification and use of a biomarker as a surrogate endpoint. Examples of biomarkers come from many different means of clinical and laboratory measurement. Total cholesterol is an example of a clinically useful biomarker that was successfully qualified for use as a surrogate endpoint. Biomarkers require validation in most circumstances. Validation of biomarker assays is a necessary component to delivery of high-quality research data necessary for effective use of biomarkers. Qualification is necessary for use of a biomarker as a surrogate endpoint. Putative biomarkers are typically identified because of a relationship to known or hypothetical steps in a pathophysiologic cascade. Biomarker discovery can also be effected by expression profiling experiment using a variety of array technologies and related methods. For example, expression profiling experiments enabled the discovery of adipocyte related complement protein of 30 kD (Acrp30 or adiponectin as a biomarker for in vivo activation of peroxisome proliferator-activated receptors (PPAR γ activity.

  13. Love as a regulative ideal in surrogate decision making.

    Science.gov (United States)

    Stonestreet, Erica Lucast

    2014-10-01

    This discussion aims to give a normative theoretical basis for a "best judgment" model of surrogate decision making rooted in a regulative ideal of love. Currently, there are two basic models of surrogate decision making for incompetent patients: the "substituted judgment" model and the "best interests" model. The former draws on the value of autonomy and responds with respect; the latter draws on the value of welfare and responds with beneficence. It can be difficult to determine which of these two models is more appropriate for a given patient, and both approaches may seem inadequate for a surrogate who loves the patient. The proposed "best judgment" model effectively draws on the values incorporated in each of the traditional standards, but does so because these values are important to someone who loves a patient, since love responds to the patient as the specific person she is. © The Author 2014. Published by Oxford University Press, on behalf of the Journal of Medicine and Philosophy Inc. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Mapping people's views regarding the acceptability of surrogate motherhood.

    Science.gov (United States)

    Petitfils, Charlotte; Munoz Sastre, Maria Teresa; Sorum, Paul Clay; Mullet, Etienne

    2017-02-01

    The aims of the present study were to map French laypersons' views regarding the acceptability of maternal surrogacy and to delineate the circumstances under which surrogacy is considered, by different groups of people, as especially problematic. Participants (N = 236) were presented with a number of scenarios depicting the circumstances in which a couple has contracted with a surrogate mother and were asked to indicate the extent to which such a contract may present a moral problem. The scenarios were created by varying four factors: the type of surrogacy (traditional or gestational), the surrogate mother's level of autonomy, the family context in which the surrogate mother lives, and whether surrogacy was commercial or altruistic. Three qualitatively different personal positions were found: (a) a majority group for which surrogacy always (30%) or often (34%) presents a moral problem, (b) a minority group (14%) for which maternal surrogacy does not systematically present a moral problem, and (c) another minority group (22%) for which circumstances - mainly the mother's level of autonomy and the family context in which she lives - were completely determining.

  15. Surrogate Assisted Design Optimization of an Air Turbine

    Directory of Open Access Journals (Sweden)

    Rameez Badhurshah

    2014-01-01

    Full Text Available Surrogates are cheaper to evaluate and assist in designing systems with lesser time. On the other hand, the surrogates are problem dependent and they need evaluation for each problem to find a suitable surrogate. The Kriging variants such as ordinary, universal, and blind along with commonly used response surface approximation (RSA model were used in the present problem, to optimize the performance of an air impulse turbine used for ocean wave energy harvesting by CFD analysis. A three-level full factorial design was employed to find sample points in the design space for two design variables. A Reynolds-averaged Navier Stokes solver was used to evaluate the objective function responses, and these responses along with the design variables were used to construct the Kriging variants and RSA functions. A hybrid genetic algorithm was used to find the optimal point in the design space. It was found that the best optimal design was produced by the universal Kriging while the blind Kriging produced the worst. The present approach is suggested for renewable energy application.

  16. Fission-product behaviour during irradiation of TRISO-coated particles in the HFREU1bis experiment - HTR2008-58125

    International Nuclear Information System (INIS)

    De Groot, S.; Bakker, K.; Barrachin, M.; Dubourg, R.; Kissane, M.

    2008-01-01

    The irradiation experiment HFR-EU1bis, coordinated by the European Joint Research Centre - Inst. for Energy, was performed in the High Flux Reactor (HFR) at Petten to test five spherical HTR fuel pebbles of former German production with TRISO coated particles in conditions beyond the specifications of current HTR reactor designs (central temperature of 1250 deg. C). In this paper, the behaviour of the fission products (FPs) and kernel micro-structure evolution during the test are investigated. While FP behaviour is a key issue for potential source term evaluation it also determines the evolution of the oxygen potential in the oxide kernel which in turn is important for formation of carbon oxides (amoeba effect and pressurization). Fission-gas release from the kernel can induce additional mechanical loading and finally some FPs (Ag, Cs, Sr) might alter the mechanical integrity of the coatings. This study is based on post- irradiation examinations (ceramography + EPMA) performed both on UO 2 kernels and on coatings. Significant evolutions of the kernel as a function of temperature are shown (grain structure, porosity, size of metallic inclusions). The quality of the ceramography results allows characteristics of the intergranular bubbles in the kernel (and estimation of swelling) to be determined. Remarkable results considering FP release from the kernel have been observed and will be presented. Examples are the significant release of Cs out of the kernel as well as Pd, whereas Zr remains trapped. Mo and Ru are mainly incorporated in metallic precipitates. These observations are interpreted and mechanisms for FP and micro-structural evolutions are proposed. These results are coupled to the results of calculations performed with the mechanistic code MFPR (Module for Fission Product Release) and the thermodynamic database MEPHISTA (Multiphase Equilibria in Fuels via Standard Thermodynamic Analysis). The effect of high flux rate and high temperature on fission gas

  17. Effectiveness of biological surrogates for predicting patterns of marine biodiversity: a global meta-analysis.

    Directory of Open Access Journals (Sweden)

    Camille Mellin

    Full Text Available The use of biological surrogates as proxies for biodiversity patterns is gaining popularity, particularly in marine systems where field surveys can be expensive and species richness high. Yet, uncertainty regarding their applicability remains because of inconsistency of definitions, a lack of standard methods for estimating effectiveness, and variable spatial scales considered. We present a Bayesian meta-analysis of the effectiveness of biological surrogates in marine ecosystems. Surrogate effectiveness was defined both as the proportion of surrogacy tests where predictions based on surrogates were better than random (i.e., low probability of making a Type I error; P and as the predictability of targets using surrogates (R(2. A total of 264 published surrogacy tests combined with prior probabilities elicited from eight international experts demonstrated that the habitat, spatial scale, type of surrogate and statistical method used all influenced surrogate effectiveness, at least according to either P or R(2. The type of surrogate used (higher-taxa, cross-taxa or subset taxa was the best predictor of P, with the higher-taxa surrogates outperforming all others. The marine habitat was the best predictor of R(2, with particularly low predictability in tropical reefs. Surrogate effectiveness was greatest for higher-taxa surrogates at a <10-km spatial scale, in low-complexity marine habitats such as soft bottoms, and using multivariate-based methods. Comparisons with terrestrial studies in terms of the methods used to study surrogates revealed that marine applications still ignore some problems with several widely used statistical approaches to surrogacy. Our study provides a benchmark for the reliable use of biological surrogates in marine ecosystems, and highlights directions for future development of biological surrogates in predicting biodiversity.

  18. MWIP: Surrogate formulations for thermal treatment of low-level mixed waste

    International Nuclear Information System (INIS)

    Bostick, W.D.; Hoffmann, D.P.; Stevenson, R.J.; Richmond, A.A.; Bickford, D.F.

    1994-01-01

    The category of sludges, filter cakes, and other waste processing residuals represent the largest volume of low-level mixed (hazardous and radioactive) wastes within the US Department of Energy (DOE) complex. Treatment of these wastes to minimize the mobility of contaminants, and to eliminate the presence of free water, is required under the Federal Facility Compliance Act agreements between DOE and the Environmental Protection Agency. In the text, we summarize the currently available data for several of the high priority mixed-waste sludge inventories within DOE. Los Alamos National Laboratory TA-50 Sludge and Rocky Flats Plant By-Pass Sludge are transuranic (TRU)-contaminated sludges that were isolated with the use of silica-based filter aids. The Oak Ridge Y-12 Plant West End Treatment Facility Sludge is predominantly calcium carbonate and biomass. The Oak Ridge K-25 Site Pond Waste is a large-volume waste stream, containing clay, silt, and other debris in addition to precipitated metal hydroxides. We formulate ''simulants'' for the waste streams described above, using cerium oxide as a surrogate for the uranium or plutonium present in the authentic material. Use of nonradiological surrogates greatly simplifies material handling requirements for initial treatability studies. The use of synthetic mixtures for initial treatability testing will facilitate compositional variation for use in conjunction with statistical design experiments; this approach may help to identify any ''operating window'' limitations. The initial treatability testing demonstrations utilizing these ''simulants'' will be based upon vitrification, although the materials are also amenable to testing grout-based and other stabilization procedures. After the feasibility of treatment and the initial evaluation of treatment performance has been demonstrated, performance must be verified using authentic samples of the candidate waste stream

  19. Storytelling in the Early Bereavement Period to Reduce Emotional Distress Among Surrogates Involved in a Decision to Limit Life Support in the ICU: A Pilot Feasibility Trial.

    Science.gov (United States)

    Barnato, Amber E; Schenker, Yael; Tiver, Greer; Dew, Mary Amanda; Arnold, Robert M; Nunez, Eduardo R; Reynolds, Charles F

    2017-01-01

    Surrogate decision makers involved in decisions to limit life support for an incapacitated patient in the ICU have high rates of adverse emotional health outcomes distinct from normal processes of grief and bereavement. Narrative self-disclosure (storytelling) reduces emotional distress after other traumatic experiences. We sought to assess the feasibility, acceptability, and tolerability of storytelling among bereaved surrogates involved in a decision to limit life support in the ICU. Pilot single-blind trial. Five ICUs across three hospitals within a single health system between June 2013 and November 2014. Bereaved surrogates of ICU patients. Storytelling and control conditions involved printed bereavement materials and follow-up assessments. Storytelling involved a single 1- to 2-hour home or telephone visit by a trained interventionist who elicited the surrogate's story. The primary outcomes were feasibility (rates of enrollment, intervention receipt, 3- and 6-mo follow-up), acceptability (closed and open-ended end-of-study feedback at 6 mo), and tolerability (acute mental health services referral). Of 53 eligible surrogates, 32 (60%) consented to treatment allocation. Surrogates' mean age was 55.5 (SD, 11.8), and they were making decisions for their parent (47%), spouse (28%), sibling (13%), child (3%), or other relation (8%). We allocated 14 to control and 18 to storytelling, 17 of 18 (94%) received storytelling, 14 of 14 (100%) and 13 of 14 (94%) control subjects and 16 of 18 (89%) and 17 of 18 (94%) storytelling subjects completed their 3- and 6-month telephone assessments. At 6 months, nine of 13 control participants (69%) and 16 of 17 storytelling subjects (94%) reported feeling "better" or "much better," and none felt "much worse." One control subject (8%) and one storytelling subject (6%) said that the study was burdensome, and one control subject (8%) wished they had not participated. No subjects required acute mental health services referral. A

  20. An Evaluation of Two Internal Surrogates for Determining the Three-Dimensional Position of Peripheral Lung Tumors

    International Nuclear Information System (INIS)

    Spoelstra, Femke; Soernsen de Koste, John R. van; Vincent, Andrew; Cuijpers, Johan P.; Slotman, Ben J.; Senan, Suresh

    2009-01-01

    Purpose: Both carina and diaphragm positions have been used as surrogates during respiratory-gated radiotherapy. We studied the correlation of both surrogates with three-dimensional (3D) tumor position. Methods and Materials: A total of 59 repeat artifact-free four-dimensional (4D) computed tomography (CT) scans, acquired during uncoached breathing, were identified in 23 patients with Stage I lung cancer. Repeat scans were co-registered to the initial 4D CT scan, and tumor, carina, and ipsilateral diaphragm were manually contoured in all phases of each 4D CT data set. Correlation between positions of carina and diaphragm with 3D tumor position was studied by use of log-likelihood ratio statistics. Models to predict 3D tumor position from internal surrogates at end inspiration (EI) and end expiration (EE) were developed, and model accuracy was tested by calculating SDs of differences between predicted and actual tumor positions. Results: Motion of both the carina and diaphragm significantly correlated with tumor motion, but log-likelihood ratios indicated that the carina was more predictive for tumor position. When craniocaudal tumor position was predicted by use of craniocaudal carina positions, the SDs of the differences between the predicted and observed positions were 2.2 mm and 2.4 mm at EI and EE, respectively. The corresponding SDs derived with the diaphragm positions were 3.7 mm and 3.9 mm at EI and EE, respectively. Prediction errors in the other directions were comparable. Prediction accuracy was similar at EI and EE. Conclusions: The carina is a better surrogate of 3D tumor position than diaphragm position. Because residual prediction errors were observed in this analysis, additional studies will be performed using audio-coached scans.

  1. Investigation of microalgae HTL fuel effects on diesel engine performance and exhaust emissions using surrogate fuels

    International Nuclear Information System (INIS)

    Hossain, Farhad M.; Nabi, Md. Nurun; Rainey, Thomas J.; Bodisco, Timothy; Rahman, Md. Mostafizur; Suara, Kabir; Rahman, S.M.A.; Van, Thuy Chu; Ristovski, Zoran; Brown, Richard J.

    2017-01-01

    Highlights: • Development of a microalgae HTL surrogate of biocrude fuel using chemical compounds. • Physiochemical properties of surrogate blends were analysed. • Experimentally investigated diesel engine performance and emissions using surrogate fuels. • No significant changes in engine performance were observed with HTL surrogate blends. • Major emissions including PM, PN and CO were reduced significantly with increasing of NOx emission. - Abstract: This paper builds on previous work using surrogate fuel to investigate advanced internal combustion engine fuels. To date, a surrogate fuel of this nature has not been used for microalgae hydrothermal liquefaction (HTL) biocrude. This research used five different chemical groups found in microalgae HTL biocrude to design a surrogate fuel. Those five chemical groups constitute around 65% (by weight) of a microalgae biocrude produced by HTL. Weight percentage of the microalgae HTL biocrude chemical compounds were used to design the surrogate fuel, which was miscible with diesel at all percentages. The engine experiments were conducted on a EURO IIIA turbocharged common-rail direct-injection six-cylinder diesel engine to test engine performance and emissions. Exhaust emissions, including particulate matter and other gaseous emissions, were measured with the surrogate fuel and a reference diesel fuel. Experimental results showed that without significantly deteriorating engine performance, lower particulate mass, particulate number and CO emissions were observed with a penalty in NOx emissions for all surrogate blends compared to those of the reference diesel.

  2. Evaluation of the toxic properties of naturally weathered Exxon Valdez crude oil to surrogate wildlife species

    International Nuclear Information System (INIS)

    Stubblefield, W.A.; Hancock, G.A.; Ford, W.H.; Prince, H.H.; Ringer, R.K.

    1995-01-01

    The toxic properties of naturally weathered Exxon Valdez crude oil (WEVC) to avian and mammalian wildlife species were evaluated using the surrogate species, mallard duck, Anas platyrhynchos, and European ferret, Mustela putorius. This study was conducted to evaluate the potential for toxic (rather than physical) injury to wildlife species that may have been exposed to WEVC, either through external contact or through dietary uptake. Previous studies have assessed the toxicity of unweathered crude oils, including Alaska North Slope Crude, but little information exists regarding the toxicity of a naturally weathered crude oil, typical of that encountered following a spill. A battery of laboratory toxicity tests was conducted, in compliance with standard and published test procedures, to evaluate acute and subchronic toxicity of WEVC. These included tests of food avoidance, reproductive effects, and direct eggshell application toxicity. Naturally weathered EVC, recovered postspill from Prince William Sound, was used as the test material. 36 refs., 7 figs., 4 tabs

  3. Sperm count as a surrogate endpoint for male fertility control.

    Science.gov (United States)

    Benda, Norbert; Gerlinger, Christoph

    2007-11-30

    When assessing the effectiveness of a hormonal method of fertility control in men, the classical approach used for the assessment of hormonal contraceptives in women, by estimating the pregnancy rate or using a life-table analysis for the time to pregnancy, is difficult to apply in a clinical development program. The main reasons are the dissociation of the treated unit, i.e. the man, and the observed unit, i.e. his female partner, the high variability in the frequency of male intercourse, the logistical cost and ethical concerns related to the monitoring of the trial. A reasonable surrogate endpoint of the definite endpoint time to pregnancy is sperm count. In addition to the avoidance of the mentioned problems, trials that compare different treatments are possible with reasonable sample sizes, and study duration can be shorter. However, current products do not suppress sperm production to 100 per cent in all men and the sperm count is only observed with measurement error. Complete azoospermia might not be necessary in order to achieve an acceptable failure rate compared with other forms of male fertility control. Therefore, the use of sperm count as a surrogate endpoint must rely on the results of a previous trial in which both the definitive- and surrogate-endpoint results were assessed. The paper discusses different estimation functions of the mean pregnancy rate (corresponding to the cumulative hazard) that are based on the results of sperm count trial and a previous trial in which both sperm count and time to pregnancy were assessed, as well as the underlying assumptions. Sample size estimations are given for pregnancy rate estimation with a given precision.

  4. Diesel Surrogate Fuels for Engine Testing and Chemical-Kinetic Modeling: Compositions and Properties.

    Science.gov (United States)

    Mueller, Charles J; Cannella, William J; Bays, J Timothy; Bruno, Thomas J; DeFabio, Kathy; Dettman, Heather D; Gieleciak, Rafal M; Huber, Marcia L; Kweon, Chol-Bum; McConnell, Steven S; Pitz, William J; Ratcliff, Matthew A

    2016-02-18

    The primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e., increasing exactness in matching hydrocarbon structural characteristics) relative to the single target diesel fuel upon which the surrogate fuels are based. This approach was taken to assist in determining the minimum level of surrogate-fuel compositional accuracy that is required to adequately emulate the performance characteristics of the target fuel under different combustion modes. For each of the four surrogate fuels, an approximately 30 L batch was blended, and a number of the physical and chemical properties were measured. This work documents the surrogate-fuel creation process and the results of the property measurements.

  5. Biopolicies and biotechnologies: reflections on surrogate maternity in India

    Directory of Open Access Journals (Sweden)

    Mónica Amador

    2010-07-01

    Full Text Available This article explores the impact of biotechnology, particularly on assisted reproductive technologies such as surrogate motherhood. The study is based on interviews and field work conducted in the city of Hyderabad in India within the frame of the seminar on “Research Methodology” given by Dr. Rohan D´Souza at the Centre for Studies in Science Policy at the Jawaharlal Nehru University in India. The theoretical framework of this analysis focuses on exploring concepts such as cyborg (Haraway,1991 and subaltern subject (Spivak, 1998 in the context of biotechnological production in India

  6. Surrogate based approaches to parameter inference in ocean models

    KAUST Repository

    Knio, Omar

    2016-01-06

    This talk discusses the inference of physical parameters using model surrogates. Attention is focused on the use of sampling schemes to build suitable representations of the dependence of the model response on uncertain input data. Non-intrusive spectral projections and regularized regressions are used for this purpose. A Bayesian inference formalism is then applied to update the uncertain inputs based on available measurements or observations. To perform the update, we consider two alternative approaches, based on the application of Markov Chain Monte Carlo methods or of adjoint-based optimization techniques. We outline the implementation of these techniques to infer dependence of wind drag, bottom drag, and internal mixing coefficients.

  7. Surrogate based approaches to parameter inference in ocean models

    KAUST Repository

    Knio, Omar

    2016-01-01

    This talk discusses the inference of physical parameters using model surrogates. Attention is focused on the use of sampling schemes to build suitable representations of the dependence of the model response on uncertain input data. Non-intrusive spectral projections and regularized regressions are used for this purpose. A Bayesian inference formalism is then applied to update the uncertain inputs based on available measurements or observations. To perform the update, we consider two alternative approaches, based on the application of Markov Chain Monte Carlo methods or of adjoint-based optimization techniques. We outline the implementation of these techniques to infer dependence of wind drag, bottom drag, and internal mixing coefficients.

  8. Psychological Well-Being, Maternal-Foetal Bonding and Experiences of Indian Surrogates

    OpenAIRE

    Lamba, Nishtha

    2018-01-01

    Over the past two decades, India has become an international hub of cross-border surrogacy. The extreme economic and cultural differences between international couples seeking surrogacy and the surrogates themselves, clinics compromising health of surrogates for profit, the stigmatisation of surrogacy in India, and the constant surveillance of these women living in a ‘surrogate house’, have raised concerns regarding the potentially negative psychological impact of surrogacy on Indian surrogat...

  9. The psychological well-being and prenatal bonding of gestational surrogates.

    OpenAIRE

    Lamba, Nishtha; Jadva, Vasanti Harish; Kadam, K; Golombok, Susan Esther

    2018-01-01

    Study question: How does the psychological well-being and prenatal bonding of Indian surrogates differ from a comparison group of mothers? Summary answer: Surrogates had higher levels of depression during pregnancy and post-birth, displayed lower emotional connection with the unborn baby, and greater care towards the healthy growth of the foetus, than the comparison group of mothers. What is already known: Studies in the West have found that surrogates do not suffer long-term psychol...

  10. The representation of healthcare end users' perspectives by surrogates in healthcare decisions: a literature review.

    Science.gov (United States)

    Shah, Syed Ghulam Sarwar; Farrow, Alexandra; Robinson, Ian

    2009-12-01

    The representation of end users' perspectives in healthcare decisions requires involvement of their surrogates when the end users, i.e. certain patients, elderly people, children and people with disabilities, are unable to present their views. To review critical issues, and the advantages and disadvantages of involving surrogates in representing end users' perspectives in healthcare decisions. A systematic review of literature published in peer-reviewed journals from 1990 to 2005. Findings show that surrogates are used widely in health care and that they are necessary to represent end users' perspectives in healthcare decisions when the latter are unable to do so themselves. Critical issues in using surrogates include key ethical, social, cultural, legal and medico-technological factors; ascertaining the best interest of end users; potential conflict of interest; possible biased decisions and the burden on surrogates. The key advantage of surrogate involvement in healthcare decisions is their ability to represent end users' needs, values and wishes. The main disadvantages include potential discrepancies between the decisions and conclusions of surrogates and end users; the failure of surrogates to predict end users' preferences accurately and the lack of certainty that useful information will be obtained through the surrogacy process. This systematic review has revealed that the involvement of surrogates is an additional vital way to represent end users' perspectives in healthcare decisions where for a range of reasons their opinions are unable to be effectively ascertained. However, because of the heterogeneity of surrogates and end users, the selection of appropriate surrogates and deploying surrogate decisions require particularly careful consideration of their value in individual cases; thus, subsequent decision-making must be reviewed on a case-to-case basis to seek to ensure that the best interests, needs and wishes of the end user are fully and accurately

  11. The psychological well-being and prenatal bonding of gestational surrogates.

    Science.gov (United States)

    Lamba, N; Jadva, V; Kadam, K; Golombok, S

    2018-02-23

    How does the psychological well-being and prenatal bonding of Indian surrogates differ from a comparison group of mothers? Surrogates had higher levels of depression during pregnancy and post-birth, displayed lower emotional connection with the unborn baby, and greater care towards the healthy growth of the foetus, than the comparison group of mothers. Studies in the West have found that surrogates do not suffer long-term psychological harm. One study has shown that surrogates bond less with the foetus than expectant mothers. This study uses a prospective, longitudinal and cross-sectional design. Surrogates and a matched group of expectant mothers were seen twice, during 4-9 months of pregnancy and 4-6 months after the birth. Semi-structured interviews and standardized questionnaires were administered to 50 surrogates and 69 expectant mothers during pregnancy and 45 surrogates and 49 expectant mothers post-birth. All gestational surrogates were hosting pregnancies for international intended parents. Surrogates had higher levels of depression compared to the comparison group of mothers, during pregnancy and post-birth (P surrogacy and criticism from others were found to be predictive of higher depression in surrogates post-birth (P < 0.05). Regarding prenatal bonding, surrogates interacted less with and thought less about the foetus but adopted better eating habits and were more likely to avoid unhealthy practices during pregnancy, than expectant mothers (P < 0.05). No associations were found between greater prenatal bonding and greater psychological distress during pregnancy or after relinquishment. All surrogates were recruited from one clinic in Mumbai, and thus the representativeness of this sample is not known. Also, the possibility of socially desirable responding from surrogates cannot be ruled out. As this is the first study of the psychological well-being of surrogates in low-income countries, the findings have important policy implications. Providing

  12. Surrogate Parenthood Act 1988 (No. 65 of 1988), 6 October 1988.

    Science.gov (United States)

    1988-01-01

    This document contains provisions of the 1988 Queensland Australia Act prohibiting surrogate parenthood contracts. The Act defines "surrogate parent" and "prescribed contract" and prohibits the publication of any type of document which intends to induce a person to act as a surrogate parent, to seek such a person, or to state willingness to act as a surrogate. Offering to enter into a prescribed contract holds a penalty of 100 penalty units or three years' imprisonment or both. This Act applies if the offense occurs in Queensland or if the offender is normally a resident of Queensland, irrespective of where the offense occurs.

  13. Analysis of Carina Position as Surrogate Marker for Delivering Phase-Gated Radiotherapy

    International Nuclear Information System (INIS)

    Weide, Lineke van der; Soernsen de Koste, John R. van; Lagerwaard, Frank J.; Vincent, Andrew; Triest, Baukelien van; Slotman, Ben J.; Senan, Suresh

    2008-01-01

    Purpose: Respiratory gating can mitigate the effect of tumor mobility in radiotherapy (RT) for lung cancer. Because the tumor is generally not visualized, external surrogates of tumor position are used to trigger respiration-gated RT. We evaluated the suitability of the carina position as a surrogate in respiration-gated RT. Methods and Materials: A total of 30 four-dimensional (4D) computed tomography (CT) scans from 14 patients with lung cancer were retrospectively analyzed. Both uncoached (free breathing) and audio-coached 4D-CT scans were acquired from 9 patients, and 12 uncoached 4D-CT scans were acquired from 5 other patients during a 2-4-week period of stereotactic RT. The repeat scans were co-registered. The carina position was identified on the coronal cut planes in all 4D-CT phases. The correlation between the carina position and the total lung volume for each phase was determined, and the reproducibility of the carina position was studied in the 5 patients with repeat uncoached 4D-CT scans. Results: The mean extent of carina motion in 21 uncoached scans was 5.3 ± 1.6 mm in the craniocaudal (CC), 2.3 ± 1.4 mm in the anteroposterior, and 1.5 ± 0.7 mm in the mediolateral direction. Audio coaching resulted in a twofold increase in carina mobility in all directions. The CC carina position correlated with changes in the total lung volume (R = 0.89 ± 0.14), but the correlation was better for the audio-coached than for the uncoached 4D-CT scans (R = 0.93 ± 0.08 vs. R = 0.85 ± 0.17; paired t test, p = 0.034). Preliminary data from the 5 patients indicated that the CC carina motion correlated better with tumor motion than did the motion of the diaphragm. Conclusions: The CC position of the carina correlated well with the total lung volume, indicating that the carina is a good surrogate for verifying the total lung volume during respiration-gated RT

  14. Behavior of radioactive metal surrogates under various waste combustion conditions

    International Nuclear Information System (INIS)

    Yang, Hee Chul; Lee, Jae Hee; Kim, Jung Guk; Yoo, Jae Hyung; Kim, Joon Hyung

    2002-01-01

    A laboratory investigation of the behavior of radioactive metals under the various waste combustion atmospheres was conducted to predict the parameters that influence their partitioning behavior during waste incineration. Neodymium, samarium, cerium, gadolinium, cesium and cobalt were used as non-radioactive surrogate metals that are representative of uranium, plutonium, americium, curium, radioactive cesium, and radioactive cobalt, respectively. Except for cesium, all of the investigated surrogate metal compounds converted into each of their stable oxides at medium temperatures from 400 to 900 .deg. C, under oxygen-deficient and oxygen-sufficient atmospheres (0.001-atm and 0.21-atm O 2 ). At high temperatures above 1,400 .deg. C, cerium, neodymium and samarium in the form of their oxides started to vaporize but the vaporization rates were very slow up to 1500 .deg. C. Inorganic chlorine (NaCl) as well as organic chlorine (PVC) did not impact the volatility of investigated Nd 2 O 3 , CoO and Cs 2 O. The results of laboratory investigations suggested that the combustion chamber operating parameters affecting the entrainment of particulate and filtration equipment operating parameters affecting particle collection efficiency be the governing parameters of alpha radionuclides partitioning during waste incineration

  15. Imaging biomarkers as surrogate endpoints for drug development

    International Nuclear Information System (INIS)

    Richter, Wolf S.

    2006-01-01

    The employment of biomarkers (including imaging biomarkers, especially PET) in drug development has gained increasing attention during recent years. This has been partly stimulated by the hope that the integration of biomarkers into drug development programmes may be a means to increase the efficiency and effectiveness of the drug development process by early identification of promising drug candidates - thereby counteracting the rising costs of drug development. More importantly, however, the interest in biomarkers for drug development is the logical consequence of recent advances in biosciences and medicine which are leading to target-specific treatments in the framework of ''personalised medicine''. A considerable proportion of target-specific drugs will show effects in subgroups of patients only. Biomarkers are a means to identify potential responders, or patient subgroups at risk for specific side-effects. Biomarkers are used in early drug development in the context of translational medicine to gain information about the drug's potential in different patient groups and disease states. The information obtained at this stage is mainly important for designing subsequent clinical trials and to identify promising drug candidates. Biomarkers in later phases of clinical development may - if properly validated - serve as surrogate endpoints for clinical outcomes. Regulatory agencies in the EU and the USA have facilitated the use of biomarkers early in the development process. The validation of biomarkers as surrogate endpoints is part of FDA's ''critical path initiative''. (orig.)

  16. Surrogate modeling of joint flood risk across coastal watersheds

    Science.gov (United States)

    Bass, Benjamin; Bedient, Philip

    2018-03-01

    This study discusses the development and performance of a rapid prediction system capable of representing the joint rainfall-runoff and storm surge flood response of tropical cyclones (TCs) for probabilistic risk analysis. Due to the computational demand required for accurately representing storm surge with the high-fidelity ADvanced CIRCulation (ADCIRC) hydrodynamic model and its coupling with additional numerical models to represent rainfall-runoff, a surrogate or statistical model was trained to represent the relationship between hurricane wind- and pressure-field characteristics and their peak joint flood response typically determined from physics based numerical models. This builds upon past studies that have only evaluated surrogate models for predicting peak surge, and provides the first system capable of probabilistically representing joint flood levels from TCs. The utility of this joint flood prediction system is then demonstrated by improving upon probabilistic TC flood risk products, which currently account for storm surge but do not take into account TC associated rainfall-runoff. Results demonstrate the source apportionment of rainfall-runoff versus storm surge and highlight that slight increases in flood risk levels may occur due to the interaction between rainfall-runoff and storm surge as compared to the Federal Emergency Management Association's (FEMAs) current practices.

  17. Eight years' experience with an IVF surrogate gestational pregnancy programme.

    Science.gov (United States)

    Raziel, Arieh; Schachter, Morey; Strassburger, Deborah; Komarovsky, Dafna; Ron-El, Raphael; Friedler, Shevach

    2005-08-01

    The aim of this study was to retrospectively audit eight years' experience of an IVF surrogate gestational programme and to compare the outcome of surrogacy due to absence of the uterus with surrogacy indicated for repeated IVF failure and recurrent abortions. A total of 60 cycles of IVF surrogate pregnancy were initiated in 19 treated couples. Absence of the uterus was the indication for surrogacy in 10 cases: Rokitansky syndrome (eight cases) and post-hysterectomy (two cases) designated as group A. The indications in the remaining nine patients (group B) were: IVF implantation failure (three cases), habitual abortions (four cases) and deteriorating maternal diseases (two cases). IVF performance and subsequent pregnancy outcome of groups A and B were compared. There was no difference in ovarian stimulation parameters and in IVF performance between the groups A and B. The overall pregnancy rate per transfer was 10/60 (17%). The pregnancy rates per patient and per transfer were 7/10 (70%) and 7/35 (20%) in group A compared with 3/9 (33%) and 3/25 (12%) in group B. A median number of three treatment cycles were needed to achieve pregnancy. In conclusion, the existence or absence of the uterus in the commissioning mothers is irrelevant for their IVF performance and conception rates. In patients who conceived after more than three IVF cycles, an additional 'oocyte factor' might be present.

  18. Premixed flame chemistry of a gasoline primary reference fuel surrogate

    KAUST Repository

    Selim, Hatem

    2017-03-10

    Investigating the combustion chemistry of gasoline surrogate fuels promises to improve detailed reaction mechanisms used for simulating their combustion. In this work, the combustion chemistry of one of the simplest, but most frequently used gasoline surrogates – primary reference fuel 84 (PRF 84, 84 vol% iso-octane and 16 vol% n-heptane), has been examined in a stoichiometric premixed laminar flame. Time-of-flight mass spectrometry coupled with a vacuum ultraviolet (VUV) synchrotron light source for species photoionization was used. Reactants, major end-products, stable intermediates, free radicals, and isomeric species were detected and quantified. Numerical simulations were conducted using a detailed chemical kinetic model with the most recently available high temperature sub-mechanisms for iso-octane and heptane, built on the top of an updated pentane isomers model and AramcoMech 2.0 (C0C4) base chemistry. A detailed interpretation of the major differences between the mechanistic pathways of both fuel components is given. A comparison between the experimental and numerical results is depicted and rate of production and sensitivity analyses are shown for the species with considerable disagreement between the experimental and numerical findings.

  19. Simultaneous Thermal Analysis of Remediated Nitrate Salt Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Wayne, David Matthew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-13

    The actinide engineering and science group (MET-1) have completed simultaneous thermal analysis and offgas analysis by mass spectrometry (STA-MS) of remediated nitrate salt (RNS) surrogates formulated by the high explosives science and technology group (M-7). The 1.0 to 1.5g surrogate samples were first analyzed as received, then a new set was analyzed with 100-200mL 10M HNO3 +0.3 MHF added, and a third set was analyzed after 200 mL of a concentrated Pu-AM spike (in 10M HNO3 +0.3 MHF) was added. The acid and spike solutions were formulated by the actinide analytical chemistry group (C-AAC) using reagent-grade HNO3 and HF, which was also used to dissolve a small quantity of mixed, high-fired PuO2/ AmO2 oxide.

  20. Bayesian calibration of the Community Land Model using surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Jaideep; Hou, Zhangshuan; Huang, Maoyi; Swiler, Laura Painton

    2014-02-01

    We present results from the Bayesian calibration of hydrological parameters of the Community Land Model (CLM), which is often used in climate simulations and Earth system models. A statistical inverse problem is formulated for three hydrological parameters, conditional on observations of latent heat surface fluxes over 48 months. Our calibration method uses polynomial and Gaussian process surrogates of the CLM, and solves the parameter estimation problem using a Markov chain Monte Carlo sampler. Posterior probability densities for the parameters are developed for two sites with different soil and vegetation covers. Our method also allows us to examine the structural error in CLM under two error models. We find that surrogate models can be created for CLM in most cases. The posterior distributions are more predictive than the default parameter values in CLM. Climatologically averaging the observations does not modify the parameters' distributions significantly. The structural error model reveals a correlation time-scale which can be used to identify the physical process that could be contributing to it. While the calibrated CLM has a higher predictive skill, the calibration is under-dispersive.

  1. Characterization of surrogate radioactive cemented waste: a laboratory study

    International Nuclear Information System (INIS)

    Fiset, J.F.; Lastra, R.; Bilodeau, A.; Bouzoubaa

    2011-01-01

    Portland cement is commonly used to stabilize intermediate and low level of radioactive wastes. The stabilization/solidification process needs to be well understood as waste constituents can retard or activate cement hydration. The objectives of this project were to prepare surrogate radioactive cemented waste (SRCW), develop a comminution strategy for SRCW, determine its chemical characteristics, and develop processes for long term storage. This paper emphasizes on the characterization of surrogate radioactive cemented waste. The SRCW produced showed a high degree of heterogeneity mainly due to the method used to add the solution to the host cement. Heavy metals such as uranium and mercury were not distributed uniformly in the pail. Mineralogical characterization (SEM, EDS) showed that uranium is located around the rims of hydrated cement particles. In the SRCW, uranium occurs possibly in the form of a hydrated calcium uranate.The SEM-EDS results also suggest that mercury occurs mainly in the form of HgO although some metallic mercury may be also present as a result of partial decomposition of the HgO. (author)

  2. The effectiveness of surrogate taxa to conserve freshwater biodiversity

    Science.gov (United States)

    Stewart, David R.; Underwood, Zachary E.; Rahel, Frank J.; Walters, Annika W.

    2018-01-01

    Establishing protected areas has long been an effective conservation strategy, and is often based on more readily surveyed species. The potential of any freshwater taxa to be a surrogate of other aquatic groups has not been fully explored. We compiled occurrence data on 72 species of freshwater fish, amphibians, mussels, and aquatic reptiles for the Great Plains, Wyoming. We used hierarchical Bayesian multi-species mixture models and MaxEnt models to describe species distributions, and program Zonation to identify conservation priority areas for each aquatic group. The landscape-scale factors that best characterized aquatic species distributions differed among groups. There was low agreement and congruence among taxa-specific conservation priorities (<20%), meaning that no surrogate priority areas would include or protect the best habitats of other aquatic taxa. We found that common, wide-ranging aquatic species were included in taxa-specific priority areas, but rare freshwater species were not included. Thus, the development of conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.

  3. Defining useful surrogates for user participation in online medical learning.

    LENUS (Irish Health Repository)

    Beddy, Peter

    2012-02-01

    "School for Surgeons" is a web-based distance learning program which provides online clinical-based tutorials to surgical trainees. Our aim was to determine surrogates of active participation and to assess the efficacy of methods to improve usage. Server logs of the 82 participants in the "School for Surgeons" were assessed for the two terms of the first year of the program. Data collected included total time online, mean session time, page requests, numbers of sessions online and the total number of assignments. An intervention regarding comparative peer usage patterns was delivered to the cohort between terms one and two. Of the 82 trainees enrolled, 83% (85% second term) logged into the program. Of all participants 88% (97% second term) submitted at least one assignment. Median submissions were four (eight second term) per trainee. Assignment submission closely correlated with number of sessions, total time online, downloads and page requests. Peer-based comparative feedback resulted in a significant increase in the number of assignments submitted (p < 0.01). Despite its recent introduction, "School for Surgeons" has a good participation rate. Assignment submission is a valid surrogate for usage. Students can be encouraged to move from passive observation to active participation in a virtual learning environment by providing structured comparative feedback ranking their performance.

  4. Surrogate reservoir models for CSI well probabilistic production forecast

    Directory of Open Access Journals (Sweden)

    Saúl Buitrago

    2017-09-01

    Full Text Available The aim of this work is to present the construction and use of Surrogate Reservoir Models capable of accurately predicting cumulative oil production for every well stimulated with cyclic steam injection at any given time in a heavy oil reservoir in Mexico considering uncertain variables. The central composite experimental design technique was selected to capture the maximum amount of information from the model response with a minimum number of reservoir models simulations. Four input uncertain variables (the dead oil viscosity with temperature, the reservoir pressure, the reservoir permeability and oil sand thickness hydraulically connected to the well were selected as the ones with more impact on the initial hot oil production rate according to an analytical production prediction model. Twenty five runs were designed and performed with the STARS simulator for each well type on the reservoir model. The results show that the use of Surrogate Reservoir Models is a fast viable alternative to perform probabilistic production forecasting of the reservoir.

  5. Conservative strategy-based ensemble surrogate model for optimal groundwater remediation design at DNAPLs-contaminated sites

    Science.gov (United States)

    Ouyang, Qi; Lu, Wenxi; Lin, Jin; Deng, Wenbing; Cheng, Weiguo

    2017-08-01

    The surrogate-based simulation-optimization techniques are frequently used for optimal groundwater remediation design. When this technique is used, surrogate errors caused by surrogate-modeling uncertainty may lead to generation of infeasible designs. In this paper, a conservative strategy that pushes the optimal design into the feasible region was used to address surrogate-modeling uncertainty. In addition, chance-constrained programming (CCP) was adopted to compare with the conservative strategy in addressing this uncertainty. Three methods, multi-gene genetic programming (MGGP), Kriging (KRG) and support vector regression (SVR), were used to construct surrogate models for a time-consuming multi-phase flow model. To improve the performance of the surrogate model, ensemble surrogates were constructed based on combinations of different stand-alone surrogate models. The results show that: (1) the surrogate-modeling uncertainty was successfully addressed by the conservative strategy, which means that this method is promising for addressing surrogate-modeling uncertainty. (2) The ensemble surrogate model that combines MGGP with KRG showed the most favorable performance, which indicates that this ensemble surrogate can utilize both stand-alone surrogate models to improve the performance of the surrogate model.

  6. Evaluation of Enterococcus faecium NRRL B-2354 as a Surrogate for Salmonella During Extrusion of Low-Moisture Food.

    Science.gov (United States)

    Verma, Tushar; Wei, Xinyao; Lau, Soon Kiat; Bianchini, Andreia; Eskridge, Kent M; Subbiah, Jeyamkondan

    2018-04-01

    Salmonella in low-moisture foods is an emerging challenge due to numerous food product recalls and foodborne illness outbreaks. Identification of suitable surrogate is critical for process validation at industry level due to implementation of new Food Safety Modernization Act of 2011. The objective of this study was to evaluate Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella during the extrusion of low-moisture food. Oat flour, a low-moisture food, was adjusted to different moisture (14% to 26% wet basis) and fat (5% to 15% w/w) contents and was inoculated with E. faecium NRRL B-2354. Inoculated material was then extruded in a lab-scale single-screw extruder running at different screw speeds (75 to 225 rpm) and different temperatures (75, 85, and 95 °C). A split-plot central composite 2nd order response surface design was used, with the central point replicated six times. The data from the selective media (m-Enterococcus agar) was used to build the response surface model for inactivation of E. faecium NRRL B-2354. Results indicated that E. faecium NRRL B-2354 always had higher heat resistance compared to Salmonella at all conditions evaluated in this study. However, the patterns of contour plots showing the effect of various product and process parameters on inactivation of E. faecium NRRL B-2354 was different from that of Salmonella. Although E. faecium NRRL B-2354 may be an acceptable surrogate for extrusion of low-moisture products due to higher resistance than Salmonella, another surrogate with similar inactivation behavior may be preferred and needs to be identified. Food Safety Modernization Act requires the food industry to validate processing interventions. This study validated extrusion processing and demonstrated that E. faecium NRRL B-2354 is an acceptable surrogate for extrusion of low-moisture products. The developed response surface model allows the industry to identify process conditions to achieve a desired lethality for their

  7. Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deatherage Kaiser, Brooke L [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Amidan, Brett G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sydor, Michael A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Barrett, Christopher A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-03-31

    The performance of a macrofoam-swab sampling method was evaluated using Bacillus anthracis Sterne (BAS) and Bacillus atrophaeus Nakamura (BG) spores applied at nine low target amounts (2-500 spores) to positive-control plates and test coupons (2 in. × 2 in.) of four surface materials (glass, stainless steel, vinyl tile, and plastic). Test results from cultured samples were used to evaluate the effects of surrogate, surface concentration, and surface material on recovery efficiency (RE), false negative rate (FNR), and limit of detection. For RE, surrogate and surface material had statistically significant effects, but concentration did not. Mean REs were the lowest for vinyl tile (50.8% with BAS, 40.2% with BG) and the highest for glass (92.8% with BAS, 71.4% with BG). FNR values ranged from 0 to 0.833 for BAS and 0 to 0.806 for BG, with values increasing as concentration decreased in the range tested (0.078 to 19.375 CFU/cm2, where CFU denotes ‘colony forming units’). Surface material also had a statistically significant effect. A FNR-concentration curve was fit for each combination of surrogate and surface material. For both surrogates, the FNR curves tended to be the lowest for glass and highest for vinyl title. The FNR curves for BG tended to be higher than for BAS at lower concentrations, especially for glass. Results using a modified Rapid Viability-Polymerase Chain Reaction (mRV-PCR) analysis method were also obtained. The mRV-PCR results and comparisons to the culture results will be discussed in a subsequent report.

  8. Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kaiser, Brooke L. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Amidan, Brett G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sydor, Michael A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Barrett, Christopher A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-06-16

    The performance of a macrofoam-swab sampling method was evaluated using Bacillus anthracis Sterne (BAS) and Bacillus atrophaeus Nakamura (BG) spores applied at nine low target amounts (2-500 spores) to positive-control plates and test coupons (2 in × 2 in) of four surface materials (glass, stainless steel, vinyl tile, and plastic). Test results from cultured samples were used to evaluate the effects of surrogate, surface concentration, and surface material on recovery efficiency (RE), false negative rate (FNR), and limit of detection. For RE, surrogate and surface material had statistically significant effects, but concentration did not. Mean REs were the lowest for vinyl tile (50.8% with BAS, 40.2% with BG) and the highest for glass (92.8% with BAS, 71.4% with BG). FNR values ranged from 0 to 0.833 for BAS and 0 to 0.806 for BG, with values increasing as concentration decreased in the range tested (0.078 to 19.375 CFU/cm2, where CFU denotes ‘colony forming units’). Surface material also had a statistically significant effect. A FNR-concentration curve was fit for each combination of surrogate and surface material. For both surrogates, the FNR curves tended to be the lowest for glass and highest for vinyl title. The FNR curves for BG tended to be higher than for BAS at lower concentrations, especially for glass. Results using a modified Rapid Viability-Polymerase Chain Reaction (mRV-PCR) analysis method were also obtained. The mRV-PCR results and comparisons to the culture results are discussed in a separate report.

  9. Systematic review: the effect on surrogates of making treatment decisions for others.

    Science.gov (United States)

    Wendler, David; Rid, Annette

    2011-03-01

    Clinical practice relies on surrogates to make or help to make treatment decisions for incapacitated adults; however, the effect of this practice on surrogates has not been evaluated. To assess the effect on surrogates of making treatment decisions for adults who cannot make their own decisions. Empirical studies published in English and listed in MEDLINE, EMBASE, CINAHL, BIOETHICSLINE, PsycINFO, or Scopus before 1 July 2010. Eligible studies provided quantitative or qualitative empirical data, by evaluating surrogates, regarding the effect on surrogates of making treatment decisions for an incapacitated adult. Information on study location, number and type of surrogates, timing of data collection, type of decisions, patient setting, methods, main findings, and limitations. 40 studies, 29 using qualitative and 11 using quantitative methods, provided data on 2854 surrogates, more than one half of whom were family members of the patient. Most surrogates were surveyed several months to years after making treatment decisions, the majority of which were end-of-life decisions. The quantitative studies found that at least one third of surrogates experienced a negative emotional burden as the result of making treatment decisions. The qualitative studies reported that many or most surrogates experienced negative emotional burden. The negative effects on surrogates were often substantial and typically lasted months or, in some cases, years. The most common negative effects cited by surrogates were stress, guilt over the decisions they made, and doubt regarding whether they had made the right decisions. Nine of the 40 studies also reported beneficial effects on a few surrogates, the most common of which were supporting the patient and feeling a sense of satisfaction. Knowing which treatment is consistent with the patient's preferences was frequently cited as reducing the negative effect on surrogates. Thirty-two of the 40 articles reported data collected in the United States

  10. A cross-cultural study on surrogate mother's empathy and maternal-foetal attachment.

    Science.gov (United States)

    Lorenceau, Ellen Schenkel; Mazzucca, Luis; Tisseron, Serge; Pizitz, Todd D

    2015-06-01

    Traditional and gestational surrogate mothers assist infertile couples by carrying their children. In 2005, a meta-analysis on surrogacy was conducted but no study had examined empathy and maternal-foetal attachment of surrogate mothers. Assessments of surrogate mothers show no sign of psychopathology, but one study showed differences on several MMPI-2 scales compared to a normative sample: surrogate mothers identified with stereotypically masculine traits such as assertiveness and competition. They had a higher self-esteem and lower levels of anxiety and depression. To determine if there is a difference in empathy and maternal-foetal attachment of surrogate mothers compared to a comparison group of mothers. Three groups of European traditional and gestational surrogate mothers (n=10), Anglo-Saxon traditional and gestational surrogate mothers (n=34) and a European normative sample of mothers (n=32) completed four published psychometric instruments: the Interpersonal Reactivity Index (empathy index), the Hospital Anxiety and Depressions Scale and the MC20, a social desirability scale. Pregnant surrogate mothers filled the Maternal Antenatal Attachment Scale (n=11). Statistical non-parametric analyses of variance were conducted. Depending on cultural background, surrogate mothers present differences in terms of empathy, anxiety and depression, social desirability and quality of attachment to the foetus compared to a normative sample. Environment plays a role for traditional and gestational surrogacy. Surrogate mothers of both groups are less anxious and depressed than normative samples. Maternal-foetal attachment is strong with a slightly lower quality of attachment. Surrogate mother's empathy indexes are similar to normative samples, sometimes higher. Copyright © 2014 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  11. Critical care physicians’ approaches to negotiating with surrogate decision makers: a qualitative study

    Science.gov (United States)

    Brush, David R.; Brown, Crystal E.; Alexander, G. Caleb

    2013-01-01

    Objective To describe how critical care physicians manage conflicts with surrogates about withdrawing or withholding patients’ life support. Design Qualitative analysis of key informant interviews with critical care physicians during 2010. We transcribed interviews verbatim and used grounded theory to code and revise a taxonomy of themes and to identify illustrative quotes. Setting 3 academic medical centers, 1 academic-affiliated medical center and 4 private practice groups or private hospitals in a large Midwestern city Subjects 14 critical care physicians Measurements and main results Physicians reported tailoring their approach to address specific reasons for disagreement with surrogates. Five common approaches were identified: (1) building trust, (2) educating and informing, (3) providing surrogates more time, (4) adjusting surrogate and physician roles, and (5) highlighting specific values. When mistrust was an issue, physicians endeavored to build a more trusting relationship with the surrogate before re-addressing decision making. Physicians also reported correcting misunderstandings by providing targeted education, and some reported highlighting specific patient, surrogate, or physician values that they hoped would guide surrogates to agree with them. When surrogates struggled with decision making roles, physicians attempted to reinforce the concept of substituted judgment. Physicians noted that some surrogates needed time to “come to terms” with the patent’s illness before agreeing with physicians. Many physicians had witnessed colleagues negotiate in ways they found objectionable, such as providing misleading information, injecting their own values into the negotiation, or behaving unprofessionally towards surrogates. While some physicians viewed their efforts to encourage surrogates’ agreement as persuasive, others strongly denied persuading surrogates and described their actions as “guiding” or “negotiating.” Conclusions Physicians

  12. Technical Note: Radiological properties of tissue surrogates used in a multimodality deformable pelvic phantom for MR-guided radiotherapy

    International Nuclear Information System (INIS)

    Niebuhr, Nina I.; Johnen, Wibke; Güldaglar, Timur; Runz, Armin; Echner, Gernot; Mann, Philipp; Möhler, Christian; Pfaffenberger, Asja; Greilich, Steffen; Jäkel, Oliver

    2016-01-01

    Purpose: Phantom surrogates were developed to allow multimodal [computed tomography (CT), magnetic resonance imaging (MRI), and teletherapy] and anthropomorphic tissue simulation as well as materials and methods to construct deformable organ shapes and anthropomorphic bone models. Methods: Agarose gels of variable concentrations and loadings were investigated to simulate various soft tissue types. Oils, fats, and Vaseline were investigated as surrogates for adipose tissue and bone marrow. Anthropomorphic shapes of bone and organs were realized using 3D-printing techniques based on segmentations of patient CT-scans. All materials were characterized in dual energy CT and MRI to adapt CT numbers, electron density, effective atomic number, as well as T1- and T2-relaxation times to patient and literature values. Results: Soft tissue simulation could be achieved with agarose gels in combination with a gadolinium-based contrast agent and NaF to simulate muscle, prostate, and tumor tissues. Vegetable oils were shown to be a good representation for adipose tissue in all modalities. Inner bone was realized using a mixture of Vaseline and K_2HPO_4, resulting in both a fatty bone marrow signal in MRI and inhomogeneous areas of low and high attenuation in CT. The high attenuation of outer bone was additionally adapted by applying gypsum bandages to the 3D-printed hollow bone case with values up to 1200 HU. Deformable hollow organs were manufactured using silicone. Signal loss in the MR images based on the conductivity of the gels needs to be further investigated. Conclusions: The presented surrogates and techniques allow the customized construction of multimodality, anthropomorphic, and deformable phantoms as exemplarily shown for a pelvic phantom, which is intended to study adaptive treatment scenarios in MR-guided radiation therapy

  13. Technical Note: Radiological properties of tissue surrogates used in a multimodality deformable pelvic phantom for MR-guided radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Niebuhr, Nina I., E-mail: n.niebuhr@dkfz.de; Johnen, Wibke; Güldaglar, Timur; Runz, Armin; Echner, Gernot; Mann, Philipp; Möhler, Christian; Pfaffenberger, Asja; Greilich, Steffen [Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany and Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Jäkel, Oliver [Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, Heidelberg 69120 (Germany); Department of Medical Physics, Heidelberg Ion-Beam Therapy Center (HIT), Im Neuenheimer Feld 450, Heidelberg 69120 (Germany)

    2016-02-15

    Purpose: Phantom surrogates were developed to allow multimodal [computed tomography (CT), magnetic resonance imaging (MRI), and teletherapy] and anthropomorphic tissue simulation as well as materials and methods to construct deformable organ shapes and anthropomorphic bone models. Methods: Agarose gels of variable concentrations and loadings were investigated to simulate various soft tissue types. Oils, fats, and Vaseline were investigated as surrogates for adipose tissue and bone marrow. Anthropomorphic shapes of bone and organs were realized using 3D-printing techniques based on segmentations of patient CT-scans. All materials were characterized in dual energy CT and MRI to adapt CT numbers, electron density, effective atomic number, as well as T1- and T2-relaxation times to patient and literature values. Results: Soft tissue simulation could be achieved with agarose gels in combination with a gadolinium-based contrast agent and NaF to simulate muscle, prostate, and tumor tissues. Vegetable oils were shown to be a good representation for adipose tissue in all modalities. Inner bone was realized using a mixture of Vaseline and K{sub 2}HPO{sub 4}, resulting in both a fatty bone marrow signal in MRI and inhomogeneous areas of low and high attenuation in CT. The high attenuation of outer bone was additionally adapted by applying gypsum bandages to the 3D-printed hollow bone case with values up to 1200 HU. Deformable hollow organs were manufactured using silicone. Signal loss in the MR images based on the conductivity of the gels needs to be further investigated. Conclusions: The presented surrogates and techniques allow the customized construction of multimodality, anthropomorphic, and deformable phantoms as exemplarily shown for a pelvic phantom, which is intended to study adaptive treatment scenarios in MR-guided radiation therapy.

  14. Error modeling for surrogates of dynamical systems using machine learning: Machine-learning-based error model for surrogates of dynamical systems

    International Nuclear Information System (INIS)

    Trehan, Sumeet; Carlberg, Kevin T.; Durlofsky, Louis J.

    2017-01-01

    A machine learning–based framework for modeling the error introduced by surrogate models of parameterized dynamical systems is proposed. The framework entails the use of high-dimensional regression techniques (eg, random forests, and LASSO) to map a large set of inexpensively computed “error indicators” (ie, features) produced by the surrogate model at a given time instance to a prediction of the surrogate-model error in a quantity of interest (QoI). This eliminates the need for the user to hand-select a small number of informative features. The methodology requires a training set of parameter instances at which the time-dependent surrogate-model error is computed by simulating both the high-fidelity and surrogate models. Using these training data, the method first determines regression-model locality (via classification or clustering) and subsequently constructs a “local” regression model to predict the time-instantaneous error within each identified region of feature space. We consider 2 uses for the resulting error model: (1) as a correction to the surrogate-model QoI prediction at each time instance and (2) as a way to statistically model arbitrary functions of the time-dependent surrogate-model error (eg, time-integrated errors). We then apply the proposed framework to model errors in reduced-order models of nonlinear oil-water subsurface flow simulations, with time-varying well-control (bottom-hole pressure) parameters. The reduced-order models used in this work entail application of trajectory piecewise linearization in conjunction with proper orthogonal decomposition. Moreover, when the first use of the method is considered, numerical experiments demonstrate consistent improvement in accuracy in the time-instantaneous QoI prediction relative to the original surrogate model, across a large number of test cases. When the second use is considered, results show that the proposed method provides accurate statistical predictions of the time- and well

  15. Comparing and combining biomarkers as principle surrogates for time-to-event clinical endpoints.

    Science.gov (United States)

    Gabriel, Erin E; Sachs, Michael C; Gilbert, Peter B

    2015-02-10

    Principal surrogate endpoints are useful as targets for phase I and II trials. In many recent trials, multiple post-randomization biomarkers are measured. However, few statistical methods exist for comparison of or combination of biomarkers as principal surrogates, and none of these methods to our knowledge utilize time-to-event clinical endpoint information. We propose a Weibull model extension of the semi-parametric estimated maximum likelihood method that allows for the inclusion of multiple biomarkers in the same risk model as multivariate candidate principal surrogates. We propose several methods for comparing candidate principal surrogates and evaluating multivariate principal surrogates. These include the time-dependent and surrogate-dependent true and false positive fraction, the time-dependent and the integrated standardized total gain, and the cumulative distribution function of the risk difference. We illustrate the operating characteristics of our proposed methods in simulations and outline how these statistics can be used to evaluate and compare candidate principal surrogates. We use these methods to investigate candidate surrogates in the Diabetes Control and Complications Trial. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Selection of Surrogate Bacteria for Use in Food Safety Challenge Studies: A Review.

    Science.gov (United States)

    Hu, Mengyi; Gurtler, Joshua B

    2017-09-01

    Nonpathogenic surrogate bacteria are prevalently used in a variety of food challenge studies in place of foodborne pathogens such as Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Clostridium botulinum because of safety and sanitary concerns. Surrogate bacteria should have growth characteristics and/or inactivation kinetics similar to those of target pathogens under given conditions in challenge studies. It is of great importance to carefully select and validate potential surrogate bacteria when verifying microbial inactivation processes. A validated surrogate responds similar to the targeted pathogen when tested for inactivation kinetics, growth parameters, or survivability under given conditions in agreement with appropriate statistical analyses. However, a considerable number of food studies involving putative surrogate bacteria lack convincing validation sources or adequate validation processes. Most of the validation information for surrogates in these studies is anecdotal and has been collected from previous publications but may not be sufficient for given conditions in the study at hand. This review is limited to an overview of select studies and discussion of the general criteria and approaches for selecting potential surrogate bacteria under given conditions. The review also includes a list of documented bacterial pathogen surrogates and their corresponding food products and treatments to provide guidance for future studies.

  17. Making fire and fire surrogate science available: a summary of regional workshops with clients

    Science.gov (United States)

    Andrew Youngblood; Heidi Bigler-Cole; Christopher J. Fettig; Carl Fiedler; Eric E. Knapp; John F. Lehmkuhl; Kenneth W. Outcalt; Carl N. Skinner; Scott L. Stephens; Thomas A. Waldrop

    2007-01-01

    Operational-scale experiments that evaluate the consequences of fire and mechanical "surrogates" for natural disturbance events are essential to better understand strategies for reducing the incidence and severity of wildfire. The national Fire and Fire Surrogate (FFS) study was initiated in 1999 to establish an integrated network of long-term studies...

  18. Use of surrogate travel to lower training costs and reduce person-rems

    International Nuclear Information System (INIS)

    Scully, M.C.; Porter, N.J.; Scott, J.W.

    1985-01-01

    In the commercial nuclear power industry where access on site may be prohibited by regulations, procedures, or the potential of extremely high radiation levels, a surrogate travel system has potential for the reduction of both exposure and personnel training time. A prototype surrogate travel system using a microcomputer-assisted laser optical video disc has been developed by Southern California Edison and Combustion Engineering

  19. Someone to Lean on: Assessment and Implications of Social Surrogate Use in Childhood

    Science.gov (United States)

    Arbeau, Kimberley A.; Coplan, Robert J.; Matheson, Adrienne

    2012-01-01

    A social surrogate is a person who helps a shy individual deal with the stresses of a social situation. Previous research has only investigated social surrogate use in adults. The purpose of the current study was to develop and evaluate a new self-report measure of social surrogacy in middle childhood and to explore the implications of this…

  20. Outcomes for Gestational Carriers Versus Traditional Surrogates in the United States.

    Science.gov (United States)

    Fuchs, Erika L; Berenson, Abbey B

    2018-05-01

    Little is known about the obstetric and procedural outcomes of traditional surrogates and gestational carriers. Participants included 222 women living in the United States who completed a brief online survey between November 2015 and February 2016. Differences between gestational carriers (n = 204) and traditional surrogates (n = 18) in demographic characteristics, pregnancy outcomes, and procedural outcomes were examined using chi-squared tests, Fisher's exact tests, and t-tests. Out of 248 eligible respondents, 222 surveys were complete, for a response rate of 89.5%. Overall, obstetric outcomes were similar among gestational carriers and traditional surrogates. Traditional surrogates were more likely than gestational carriers to have a Center for Epidemiologic Studies Depression Scale Revised score of 16 or higher (37.5% vs. 4.0%). Gestational carriers reported higher mean compensation ($27,162.80 vs. $17,070.07) and were more likely to travel over 400 miles (46.0% vs. 0.0%) than traditional surrogates. Procedural differences, but not differences in obstetric outcomes, emerged between gestational carriers and traditional surrogates. To ensure that both traditional surrogates and gestational carriers receive optimal medical care, it may be necessary to extend practice guidelines to ensure that traditional surrogates are offered the same level of care offered to gestational carriers.

  1. A fast surrogate model tailor-made for real time control

    DEFF Research Database (Denmark)

    Borup, Morten; Thrysøe, Cecilie; Arnbjerg-Nielsen, Karsten

    A surrogate model of a detailed hydraulic urban drainage model is created for supplying inflow forecasts to an MPC model for 31 separate locations. The original model is subdivided into 66 relationships extracted from the original model. The surrogate model is 9000 times faster than the original...... model, with just a minor deviation from the original model results....

  2. Comparative study of different surrogate markers for individual radiation sensitivity

    International Nuclear Information System (INIS)

    Hoffmann, Nele Julia

    2013-01-01

    Radiotherapy is an important part of therapeutic tumor treatment concept. The applied total dose is limited by the unavoidable radiation effect on the surrounding normal tissue and the risk of radiation induced acute or chronic side effects. The clinical radiation sensitivity, i.e. the risk of radiogenic side effects is strongly coupled to the cellular radiation sensitivity. The contribution is focused on the development of a predictive tool for the individual radiation sensitivity for individual radiotherapeutic planning using lymphocytes. Residual foci, i.e. accumulated repair associated proteins at the residual double strand break are supposed to be surrogate markers of the cellular radiation sensitivity. No relation between the foci detection and the G(0)/G(1) was found assay with respect to the individual radiation sensitivity.

  3. Optimization of inlet plenum of A PBMR using surrogate modeling

    International Nuclear Information System (INIS)

    Lee, Sang-Moon; Kim, Kwang-Yong

    2009-01-01

    The purpose of present work is to optimize the design of inlet plenum of PBMR type gas cooled nuclear reactor numerically using a combining of three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis and surrogate modeling technique. Shear stress transport (SST) turbulence model is used as a turbulence closure. Three geometric design variables are selected, namely, rising channel diameter to plenum height ratio, aspect ratio of the plenum cross section, and inlet port angle. The objective function is defined as a linear combination of uniformity of three-dimensional flow distribution term and pressure drop in the inlet plenum and rising channels of PBMR term with a weighting factor. Twenty design points are selected using Latin-hypercube method of design of experiment and objective function values are obtained at each design point using RANS solver. (author)

  4. Surrogate motherhood, rights and duties: a reply to Campbell.

    Science.gov (United States)

    McLachlan, H V; Swales, J K

    2001-01-01

    In a recent article in Health Care Analysis (Vol. 8, No. 1), Campbell misrepresents our specific arguments about commercial surrogate motherhood (C.S.M.) and our general philosophical and political views by saying or suggesting that we are 'Millsian' liberals and consequentialists. He gives too the false impression that we do not oppose, in principle, slavery and child purchase. Here our position on C.S.M. is re-expressed and elaborated upon in order to eliminate possible confusion. Our general ethical and philosophical framework is also outlined and shown to be other than Campbell says that it is. In particular, a moral philosophy that is based on neither consequentialism nor Kantianism is presented. C.S.M., it is argued, is not child purchase. It is like it in some respects and unlike it in others. It is unlike it in the respects which, relative to the present discussion, matter.

  5. Surrogate mothers: aboriginal grandmothers raising grandchildren in Taiwan.

    Science.gov (United States)

    Chang, Yu-Ting; Hayter, Mark

    2011-05-01

    The purpose of this qualitative study was to understand the experiences of Taiwanese aboriginal grandmothers when raising their grandchildren. Adopting a phenomenological approach, interviews were conducted with 15 Taiwanese aboriginal grandmothers who served as primary caregiver to a grandchild or grandchildren. Data were analyzed using Giorgi's phenomenological method. Four themes emerged from the data analysis, reflecting the parenting experience of grandmothers: using aged bodies to do energetic work: represented the physical effects of raising grandchildren; conflicting emotions: reflected the psychological effects of raising grandchildren; lifelong and privative obligation: described the cultural and societal beliefs of raising grandchildren; and coping strategies for raising grandchildren outlined methods the grandmothers used to cope with parenting their grandchildren. The results of this study offers insights into surrogate parenting within an underresearched group in Taiwan and will enable health care providers to be more aware of the physical, emotional, and social effects of the role of grandparent parenting.

  6. Effectiveness of biodiversity surrogates for conservation planning: different measures of effectiveness generate a kaleidoscope of variation.

    Directory of Open Access Journals (Sweden)

    Hedley S Grantham

    Full Text Available Conservation planners represent many aspects of biodiversity by using surrogates with spatial distributions readily observed or quantified, but tests of their effectiveness have produced varied and conflicting results. We identified four factors likely to have a strong influence on the apparent effectiveness of surrogates: (1 the choice of surrogate; (2 differences among study regions, which might be large and unquantified (3 the test method, that is, how effectiveness is quantified, and (4 the test features that the surrogates are intended to represent. Analysis of an unusually rich dataset enabled us, for the first time, to disentangle these factors and to compare their individual and interacting influences. Using two data-rich regions, we estimated effectiveness using five alternative methods: two forms of incidental representation, two forms of species accumulation index and irreplaceability correlation, to assess the performance of 'forest ecosystems' and 'environmental units' as surrogates for six groups of threatened species-the test features-mammals, birds, reptiles, frogs, plants and all of these combined. Four methods tested the effectiveness of the surrogates by selecting areas for conservation of the surrogates then estimating how effective those areas were at representing test features. One method measured the spatial match between conservation priorities for surrogates and test features. For methods that selected conservation areas, we measured effectiveness using two analytical approaches: (1 when representation targets for the surrogates were achieved (incidental representation, or (2 progressively as areas were selected (species accumulation index. We estimated the spatial correlation of conservation priorities using an index known as summed irreplaceability. In general, the effectiveness of surrogates for our taxa (mostly threatened species was low, although environmental units tended to be more effective than forest ecosystems

  7. Technological advances in suspended‐sediment surrogate monitoring

    Science.gov (United States)

    Gray, John R.; Gartner, Jeffrey W.

    2009-01-01

    Surrogate technologies to continuously monitor suspended sediment show promise toward supplanting traditional data collection methods requiring routine collection and analysis of water samples. Commercially available instruments operating on bulk optic (turbidity), laser optic, pressure difference, and acoustic backscatter principles are evaluated based on cost, reliability, robustness, accuracy, sample volume, susceptibility to biological fouling, and suitable range of mass concentration and particle size distribution. In situ turbidimeters are widely used. They provide reliable data where the point measurements can be reliably correlated to the river's mean cross section concentration value, effects of biological fouling can be minimized, and concentrations remain below the sensor's upper measurement limit. In situ laser diffraction instruments have similar limitations and can cost 6 times the approximate $5000 purchase price of a turbidimeter. However, laser diffraction instruments provide volumetric‐concentration data in 32 size classes. Pressure differential instruments measure mass density in a water column, thus integrating substantially more streamflow than a point measurement. They are designed for monitoring medium‐to‐large concentrations, are generally unaffected by biological fouling, and cost about the same as a turbidimeter. However, their performance has been marginal in field applications. Acoustic Doppler profilers use acoustic backscatter to measure suspended sediment concentrations in orders of magnitude more streamflow than do instruments that rely on point measurements. The technology is relatively robust and generally immune to effects of biological fouling. Cost of a single‐frequency device is about double that of a turbidimeter. Multifrequency arrays also provide the potential to resolve concentrations by clay silt versus sand size fractions. Multifrequency hydroacoustics shows the most promise for revolutionizing collection of

  8. LVAD patients' and surrogates' perspectives on SPIRIT-HF: An advance care planning discussion.

    Science.gov (United States)

    Metzger, Maureen; Song, Mi-Kyung; Devane-Johnson, Stephanie

    2016-01-01

    To describe LVAD patients' and surrogates' experiences with, and perspectives on SPIRIT-HF, an advance care planning (ACP) intervention. ACP is important for patients with LVAD, yet little is known about their experiences or those of their surrogates who have participated in ACP discussions. We used qualitative content analysis techniques to conduct a secondary analysis of 28 interviews with patients with LVAD (n = 14) and their surrogates (n = 14) who had participated in an RCT pilot study of SPIRIT-HF. Main themes from the data include: 1) sharing their HF stories was very beneficial; 2) participating in SPIRIT-HF led to greater peace of mind for patients and surrogates; 3) "one size does not fit all" when it comes to timing of ACP discussions. An understanding patient and surrogate perspectives may inform clinicians' approach to ACP discussions. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. A computational methodology for formulating gasoline surrogate fuels with accurate physical and chemical kinetic properties

    KAUST Repository

    Ahmed, Ahfaz

    2015-03-01

    Gasoline is the most widely used fuel for light duty automobile transportation, but its molecular complexity makes it intractable to experimentally and computationally study the fundamental combustion properties. Therefore, surrogate fuels with a simpler molecular composition that represent real fuel behavior in one or more aspects are needed to enable repeatable experimental and computational combustion investigations. This study presents a novel computational methodology for formulating surrogates for FACE (fuels for advanced combustion engines) gasolines A and C by combining regression modeling with physical and chemical kinetics simulations. The computational methodology integrates simulation tools executed across different software platforms. Initially, the palette of surrogate species and carbon types for the target fuels were determined from a detailed hydrocarbon analysis (DHA). A regression algorithm implemented in MATLAB was linked to REFPROP for simulation of distillation curves and calculation of physical properties of surrogate compositions. The MATLAB code generates a surrogate composition at each iteration, which is then used to automatically generate CHEMKIN input files that are submitted to homogeneous batch reactor simulations for prediction of research octane number (RON). The regression algorithm determines the optimal surrogate composition to match the fuel properties of FACE A and C gasoline, specifically hydrogen/carbon (H/C) ratio, density, distillation characteristics, carbon types, and RON. The optimal surrogate fuel compositions obtained using the present computational approach was compared to the real fuel properties, as well as with surrogate compositions available in the literature. Experiments were conducted within a Cooperative Fuels Research (CFR) engine operating under controlled autoignition (CAI) mode to compare the formulated surrogates against the real fuels. Carbon monoxide measurements indicated that the proposed surrogates

  10. Surrogate formulations for thermal treatment of low-level mixed waste

    International Nuclear Information System (INIS)

    Chiang, J.M.; Bostick, W.D.; Hoffman, D.P.; Hermes, W.H.; Gibson, L.V. Jr.; Richmond, A.A.

    1994-01-01

    The plasma hearth process (PHP) presented in this report has been tested at a facility at Ukiah, California, in a cooperative effort between the Department of Energy (DOE), Science Applications International Corporation, Inc., and ReTech, Inc. The electrically heated plasma gas is used to destroy organic materials and bind radionuclides and Resource Conservation and Recovery Act (RCRA) metals in the glassy slag. Proof-of-principle tests were conducted successfully using nonhazardous and non-radioactive materials placed in 30-gal steel drums. On-line analyses of the gaseous effluents indicated complete combustion; emissions of CO, NO x , and particulates were low. The process also produced highly stable solid waste forms. The experiments for the next phase have been planned employing surrogates for the hazardous and radioactive components of the simulated waste streams. Natural cerium oxide is selected to simulate the behavior of radioactive actinide and transuranium elements, while natural cesium chloride is simulated for the study of relatively volatile radioactive fission products. For RCRA organics, naphthalene and 1,2-dichlorobenzene are semivolatile compounds selected to represent significant challenges to thermal destruction, whereas chlorobenzene is selected for the study of relatively volatile organics. Salts of chromium, nickel, lead, and cadmium are chosen to represent the twelve regulated toxic metals for emission and partitioning studies. The simulated waste packages presented in the text do not necessarily represent an individual waste stream within the DOE complex; rather, they were formulated to represent the most probable components in generic waste stream categories

  11. Health information-seeking on behalf of others: characteristics of "surrogate seekers".

    Science.gov (United States)

    Cutrona, Sarah L; Mazor, Kathleen M; Vieux, Sana N; Luger, Tana M; Volkman, Julie E; Finney Rutten, Lila J

    2015-03-01

    Understanding the behaviors of surrogate seekers (those who seek health information for others) may guide efforts to improve health information transmission. We used 2011-2012 data from the Health Information National Trends Survey to describe behaviors of online surrogate seekers. Respondents were asked about use of the Internet for surrogate-seeking over the prior 12 months. Data were weighted to calculate population estimates. Two thirds (66.6%) reported surrogate-seeking. Compared to those who sought health information online for only themselves, surrogate seekers were more likely to live in households with others (weighted percent 89.4 vs. 82.5% of self-seekers; p user-generated content: email communication with healthcare providers; visits to social networking sites to read and share about medical topics and participation in online health support groups. On multivariate analysis, those who had looked online for healthcare providers were more likely to be surrogate seekers (OR 1.67, 95% CI 1.08-2.59). In addition to seeking health information, surrogate seekers create and pass along communications that may influence medical care decisions. Research is needed to identify ways to facilitate transmission of accurate health information.

  12. Surrogate mobility and orientation affect the early neurobehavioral development of infant rhesus macaques (Macaca mulatta).

    Science.gov (United States)

    Dettmer, Amanda M; Ruggiero, Angela M; Novak, Melinda A; Meyer, Jerrold S; Suomi, Stephen J

    2008-05-01

    A biological mother's movement appears necessary for optimal development in infant monkeys. However, nursery-reared monkeys are typically provided with inanimate surrogate mothers that move very little. The purpose of this study was to evaluate the effects of a novel, highly mobile surrogate mother on motor development, exploration, and reactions to novelty. Six infant rhesus macaques (Macaca mulatta) were reared on mobile hanging surrogates (MS) and compared to six infants reared on standard stationary rocking surrogates (RS) and to 9-15 infants reared with their biological mothers (MR) for early developmental outcome. We predicted that MS infants would develop more similarly to MR infants than RS infants. In neonatal assessments conducted at Day 30, both MS and MR infants showed more highly developed motor activity than RS infants on measures of grasping (p = .009), coordination (p = .038), spontaneous crawl (p = .009), and balance (p = .003). At 2-3 months of age, both MS and MR infants displayed higher levels of exploration in the home cage than RS infants (p = .016). In a novel situation in which only MS and RS infants were tested, MS infants spent less time near their surrogates in the first five minutes of the test session than RS infants (p = .05), indicating a higher level of comfort. Collectively, these results suggest that when nursery-rearing of infant monkeys is necessary, a mobile hanging surrogate may encourage more normative development of gross motor skills and exploratory behavior and may serve as a useful alternative to stationary or rocking surrogates.

  13. Narrative Interest Standard: A Novel Approach to Surrogate Decision-Making for People With Dementia.

    Science.gov (United States)

    Wilkins, James M

    2017-06-17

    Dementia is a common neurodegenerative process that can significantly impair decision-making capacity as the disease progresses. When a person is found to lack capacity to make a decision, a surrogate decision-maker is generally sought to aid in decision-making. Typical bases for surrogate decision-making include the substituted judgment standard and the best interest standard. Given the heterogeneous and progressive course of dementia, however, these standards for surrogate decision-making are often insufficient in providing guidance for the decision-making for a person with dementia, escalating the likelihood of conflict in these decisions. In this article, the narrative interest standard is presented as a novel and more appropriate approach to surrogate decision-making for people with dementia. Through case presentation and ethical analysis, the standard mechanisms for surrogate decision-making for people with dementia are reviewed and critiqued. The narrative interest standard is then introduced and discussed as a dementia-specific model for surrogate decision-making. Through incorporation of elements of a best interest standard in focusing on the current benefit-burden ratio and elements of narrative to provide context, history, and flexibility for values and preferences that may change over time, the narrative interest standard allows for elaboration of an enriched context for surrogate decision-making for people with dementia. More importantly, however, a narrative approach encourages the direct contribution from people with dementia in authoring the story of what matters to them in their lives.

  14. Public’s Approach to Surrogate Consent for Dementia Research: Cautious Pragmatism

    Science.gov (United States)

    De Vries, Raymond; Ryan, Kerry A.; Stanczyk, Aimee; Appelbaum, Paul S.; Damschroder, Laura; Knopman, David S.; Kim, Scott Y. H.

    2011-01-01

    Objectives To describe how members of the older general public deliberate with one another in finding solutions to the dilemma of involving decisionally incapable persons in dementia research. Design, Setting, and Participants 160 persons aged 50+ who participated in an all-day deliberative democracy (DD) session on the ethics of surrogate consent for dementia research. The DD day consisted of both extensive, interactive education with experts in clinical research and ethics, as well as small group deliberations. Measurements Audiotaped small group deliberations were transcribed and analyzed, and the main thematic elements were coded. Results During deliberation, participants acknowledged the limitations of advanced research directives and discussed ways to improve their use. Although there was consensus about the necessity of surrogate consent, the participants recognized potential pitfalls and looked for ways to safeguard the process. Participants supporting surrogate consent for research emphasized societal and individual benefit, the importance of assent, and trust in surrogates and the oversight system. Other participants felt that the high risk of some research scenarios was not sufficiently offset by benefits to patients or society. Conclusions Members of the older general public are able to make use of in-depth education and peer deliberation to provide reasoned and informed opinions on the ethical use of surrogate consent for dementia research. The public’s approach to surrogate consent is one of cautious pragmatism: an overall trust in science and future surrogates with awareness of the potential pitfalls, suggesting that their trust cannot be taken for granted. PMID:23498383

  15. Surrogate alcohol: what do we know and where do we go?

    Science.gov (United States)

    Lachenmeier, Dirk W; Rehm, Jürgen; Gmel, Gerhard

    2007-10-01

    Consumption of surrogate alcohols (i.e., nonbeverage alcohols and illegally produced alcohols) was shown to impact on different causes of death, not only poisoning or liver disease, and appears to be a major public health problem in Russia and elsewhere. A computer-assisted literature review on chemical composition and health consequences of "surrogate alcohol" was conducted and more than 70 references were identified. A wider definition of the term "surrogate alcohol" was derived, including both nonbeverage alcohols and illegally produced alcohols that contain nonbeverage alcohols. Surrogate alcohol may contain substances that cause severe health consequences including death. Known toxic constituents include lead, which may lead to chronic toxicity, and methanol, which leads to acute poisoning. On the other hand, the role of higher alcohols (e.g., propanol, isobutanol, and isoamyl alcohol) in the etiology of surrogate-associated diseases is currently unclear. Whether other constituents of surrogates have contributed to the high all-cause mortality over and above the effect of ethanol in recent studies also remains unclear. Given the high public health importance associated with the consumption of surrogate alcohols, further knowledge on its chemical composition is required as well as research on its links to various disease endpoints should be undertaken with priority. Some interventions to reduce the harm resulting from surrogate alcohol could be undertaken already at this point. For example, the use of methanol or methanol-containing wood alcohol should be abolished in denatured alcohol. Other possible surrogates (e.g., automobile products) should be treated with bittering agents to avoid consumption.

  16. The Different Moral Bases of Patient and Surrogate Decision-Making.

    Science.gov (United States)

    Brudney, Daniel

    2018-01-01

    My topic is a problem with our practice of surrogate decision-making in health care, namely, the problem of the surrogate who is not doing her job-the surrogate who cannot be reached or the surrogate who seems to refuse to understand or to be unable to understand the clinical situation. The analysis raises a question about the surrogate who simply disagrees with the medical team. One might think that such a surrogate is doing her job-the team just doesn't like how she is doing it. My analysis raises the question of whether (or perhaps when) she should be overridden. In approaching this problem, I focus not on the range of difficulties in practice but on the underlying moral conceptual issue. My concern will be to show that the moral values that underpin patient decision-making are fundamentally different from those that underpin surrogate decision-making. Identifying the distinctions will set parameters for any successful solution to the "Who should decide?" A patient has a specific kind of moral right to make her own medical decisions. A surrogate has no analogous moral right to decide for someone else. We want the surrogate to make the decision because we believe that she has a relevant epistemological advantage over anyone else on the scene. If and when she has no such advantage or if she refuses or is unable to use it, then there might not be sufficient reason to let her be the decision-maker. © 2018 The Hastings Center.

  17. Posttreatment prostatic-specific antigen doubling time as a surrogate endpoint for prostate cancer-specific survival: An analysis of Radiation Therapy Oncology Group Protocol 92-02

    International Nuclear Information System (INIS)

    Valicenti, Richard K.; DeSilvio, Michelle; Hanks, Gerald E.; Porter, Arthur; Brereton, Harmar; Rosenthal, Seth A.; Shipley, William U.; Sandler, Howard M.

    2006-01-01

    Purpose: We evaluated whether posttreatment prostatic-specific antigen doubling time (PSADT) was predictive of prostate cancer mortality by testing the Prentice requirements for a surrogate endpoint. Methods and Materials: We analyzed posttreatment PSA measurements in a cohort of 1,514 men with localized prostate cancer (T2c-4 and PSA level Cox = 0.002), PSADT Cox Cox Cox Cox = 0.4). The significant posttreatment PSADTs were also significant predictors of CSS (p Cox < 0.001). After adjusting for T stage, Gleason score and PSA, all of Prentice's requirements were not met, indicating that the effect of PSADT on CSS was not independent of the randomized treatment. Conclusions: Prostatic specific antigen doubling time is significantly associated with CSS, but did not meet all of Prentice's requirements for a surrogate endpoint of CSS. Thus, the risk of dying of prostate cancer is not fully explained by PSADT

  18. First Trimester Hemolysis, Elevated Liver Enzymes, Low Platelets Syndrome in a Surrogate Pregnancy

    OpenAIRE

    Myer, Emily; Hill, James

    2015-01-01

    Background The occurrence of hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome before 20 weeks of gestation is rare. HELLP is a possible but rare syndrome in gestational surrogate pregnancies for surrogates with risk factors for development of preeclampsia. Case A 32-year-old patient with chronic hypertension and positive antinuclear antibody presented for prenatal care at 13 weeks and 1 day. She was a surrogate for the embryo of a 43-year-old couple. By 15 weeks she developed...

  19. Children of surrogate mothers: psychological well-being, family relationships and experiences of surrogacy.

    Science.gov (United States)

    Jadva, V; Imrie, S

    2014-01-01

    What impact does surrogacy have on the surrogates' own children? The children of surrogate mothers do not experience any negative consequences as a result of their mother's decision to be a surrogate, irrespective of whether or not the surrogate uses her own egg. Participants were recruited as part of a study of the long-term effects of surrogacy for surrogates and their family members. Data were collected from 36 children of surrogates at a single time point. Participants whose mother had been a surrogate 5-15 years prior to interview and who were aged over 12 years were eligible to take part. Thirty-six participants (14 male and 22 female) aged 12-25 years were interviewed (response rate = 52%). Questionnaires assessing psychological health and family functioning were administered. Forty-four per cent (15) of participants' mothers had undergone gestational surrogacy, 39% (14) had used their own egg (genetic surrogacy) and 19% (7) had completed both types of surrogacy. Most surrogates' children (86%, 31) had a positive view of their mother's surrogacy. Forty-seven per cent (17) of children were in contact with the surrogacy child and all reported good relationships with him/her. Forty per cent (14) of children referred to the child as a sibling or half-sibling and this did not differ between genetic and gestational surrogacy. Most children (89%, 32), reported a positive view of family life, with all enjoying spending time with their mother. Mean scores on the questionnaire assessments of psychological health and self-esteem were within the normal range and did not differ by surrogacy type. The sample size for this study was relatively small and not all children chose to take part, therefore their views cannot be known. Nevertheless, this is the first study to assess the experiences of surrogacy from the perspective of the surrogates' own children. There may be some bias from the inclusion of siblings from the same family. Findings of this study show that family

  20. Methylene blue as a lignin surrogate in manganese peroxidase reaction systems.

    Science.gov (United States)

    Goby, Jeffrey D; Penner, Michael H; Lajoie, Curtis A; Kelly, Christine J

    2017-11-15

    Manganese peroxidase (MnP) is associated with lignin degradation and is thus relevant to lignocellulosic-utilization technologies. Technological applications require reaction mixture optimization. A surrogate substrate can facilitate this if its susceptibility to degradation is easily monitored and mirrors that of lignin. The dye methylene blue (MB) was evaluated in these respects as a surrogate substrate by testing its reactivity in reaction mixtures containing relevant redox mediators (dicarboxylic acids, fatty acids). Relative rates of MB degradation were compared to available literature reports of lignin degradation under similar conditions, and suggest that MB can be a useful lignin surrogate in MnP systems. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Results from Second Round of Remediated Nitrate Salt Surrogate Formulation and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Geoffrey Wayne [Los Alamos National Laboratory; Leonard, Philip [Los Alamos National Laboratory; Hartline, Ernest Leon [Los Alamos National Laboratory; Tian, Hongzhao [Los Alamos National Laboratory

    2016-04-04

    High Explosives and Technology (M-7) completed the second round of formulation and testing of Remediated Nitrate Salt (RNS) surrogates on March 17, 2016. This report summarizes the results of the work and also includes additional documentation required under test plan PLAN-TA9-2443 Rev B, "Remediated Nitrate Salt (RNS) Surrogate Formulation and Testing Standard Procedure", released February 16, 2016. All formulation and testing was carried out according to PLAN-TA9-2443 Rev B. Results from the first round of formulation and testing were documented in memorandum M7-16-6042, "Results from First Round of Remediated Nitrate Salt Surrogate Formulation and Testing."

  2. Surrogate indicators of sensitivity in gynecologic cytology: Can they be used to improve the measurement of sensitivity in the laboratory?

    Directory of Open Access Journals (Sweden)

    Renshaw Andrew

    2009-01-01

    Full Text Available Background: Measuring the sensitivity of screening in gynecologic cytology in real life is problematic. However, other quality measures may correlate with sensitivity, including the atypical squamous cells (ASC/squamous intraepithelial lesion (SIL ratio. Whether these other measures can function as "surrogate indicators" for sensitivity and improve the assessment of sensitivity in the laboratory is not known. Materials and Methods: We compared multiple quality measures with true screening sensitivity in a variety of situations. Results: The abnormal rate, ASC rate, and ASC/SIL ratio were all highly correlated (r = .83 or greater with sensitivity when the overall laboratory sensitivity was low (85% but became less correlated (.64 or less or uncorrelated when the screening sensitivity was higher (88% or 95%, respectively. Sensitivity was more highly correlated with the abnormal rate than the ASC/SIL ratio at low screening sensitivity. While thresholds could be set that were highly sensitive and specific for suboptimal screening, these thresholds were often less than one standard deviation away from the mean. Conclusion: The correlation of the abnormal rate and the ASC/SIL ratio with sensitivity depends on overall sensitivity. Standards to define minimum screening sensitivity can be defined, but these standards are relatively narrow. These features may limit the utility of these quality measures as surrogates for sensitivity.

  3. An assessment of the validity of cerium oxide as a surrogate for plutonium oxide gallium removal studies

    International Nuclear Information System (INIS)

    Kolman, D.G.; Park, Y.; Stan, M.; Hanrahan, R.J. Jr.; Butt, D.P.

    1999-01-01

    Methods for purifying plutonium metal have long been established. These methods use acid solutions to dissolve and concentrate the metal. However, these methods can produce significant mixed waste, that is, waste containing both radioactive and chemical hazards. The volume of waste produced from the aqueous purification of thousands of weapons would be expensive to treat and dispose. Therefore, a dry method of purification is highly desirable. Recently, a dry gallium removal research program commenced. Based on initial calculations, it appeared that a particular form of gallium (gallium suboxide, Ga 2 O) could be evaporated from plutonium oxide in the presence of a reducing agent, such as small amounts of hydrogen dry gas within an inert environment. Initial tests using ceria-based material (as a surrogate for PuO 2 ) showed that thermally-induced gallium removal (TIGR) from small samples (on the order of one gram) was indeed viable. Because of the expense and difficulty of optimizing TIGR from plutonium dioxide, TIGR optimization tests using ceria have continued. This document details the relationship between the ceria surrogate tests and those conducted using plutonia

  4. Effectiveness of amphibians as biodiversity surrogates in pond conservation.

    Science.gov (United States)

    Ilg, Christiane; Oertli, Beat

    2017-04-01

    Amphibian decline has led to worldwide conservation efforts, including the identification and designation of sites for their protection. These sites could also play an important role in the conservation of other freshwater taxa. In 89 ponds in Switzerland, we assessed the effectiveness of amphibians as a surrogate for 4 taxonomic groups that occur in the same freshwater ecosystems as amphibians: dragonflies, aquatic beetles, aquatic gastropods, and aquatic plants. The ponds were all of high value for amphibian conservation. Cross-taxon correlations were tested for species richness and conservation value, and Mantel tests were used to investigate community congruence. Species richness, conservation value, and community composition of amphibians were weakly congruent with these measures for the other taxonomic groups. Paired comparisons for the 5 groups considered showed that for each metric, amphibians had the lowest degree of congruence. Our results imply that site designation for amphibian conservation will not necessarily provide protection for freshwater biodiversity as a whole. To provide adequate protection for freshwater species, we recommend other taxonomic groups be considered in addition to amphibians in the prioritization and site designation process. © 2016 Society for Conservation Biology.

  5. Capturing heterogeneity in gene expression studies by surrogate variable analysis.

    Directory of Open Access Journals (Sweden)

    Jeffrey T Leek

    2007-09-01

    Full Text Available It has unambiguously been shown that genetic, environmental, demographic, and technical factors may have substantial effects on gene expression levels. In addition to the measured variable(s of interest, there will tend to be sources of signal due to factors that are unknown, unmeasured, or too complicated to capture through simple models. We show that failing to incorporate these sources of heterogeneity into an analysis can have widespread and detrimental effects on the study. Not only can this reduce power or induce unwanted dependence across genes, but it can also introduce sources of spurious signal to many genes. This phenomenon is true even for well-designed, randomized studies. We introduce "surrogate variable analysis" (SVA to overcome the problems caused by heterogeneity in expression studies. SVA can be applied in conjunction with standard analysis techniques to accurately capture the relationship between expression and any modeled variables of interest. We apply SVA to disease class, time course, and genetics of gene expression studies. We show that SVA increases the biological accuracy and reproducibility of analyses in genome-wide expression studies.

  6. The composition of surrogate and illegal alcohol products in Estonia.

    Science.gov (United States)

    Lang, Katrin; Väli, Marika; Szucs, Sándor; Adány, Róza; McKee, Martin

    2006-01-01

    To identify the composition of illegal and surrogate alcohol products consumed in Estonia. The initial source of information was a series of visits made in August 2005 to a soup kitchen in central Tartu, Estonia. Individuals were asked for brief details of their personal circumstances, what they normally drank, and in addition they were asked to bring samples of the substances they usually consumed. In other cases, the substances identified were purchased by the investigators or from informal contacts in north-eastern part of Estonia, an area that is well known for illegal alcohol consumption. Samples were tested for chemical contents. We identified a range of alcohol-containing substances that are consumed, although, not intended for consumption. These comprised medicinal products, aftershaves, illegally produced spirits, and fire-lighting fuel. The medicinal compounds contained, on average, 67% ethanol by volume; the aftershaves contained slightly less. Both were typically pure, with a few containing detectable quantities of isoamyl alcohol. The illegally produced alcohol contained, on average, 43% ethanol by volume, ranging from 32 to 53%. However, many also contained detectable quantities of long chain alcohols. These substances are half the price or less of commercial vodka, with fire lighting fuels especially inexpensive. There is in Estonia a range of alcohol-containing substances easily available at low cost. Some contain substantially higher concentrations of ethanol than commercial spirits and others also contain toxic long chain alcohols.

  7. Black-hole kicks from numerical-relativity surrogate models

    Science.gov (United States)

    Gerosa, Davide; Hébert, François; Stein, Leo C.

    2018-05-01

    Binary black holes radiate linear momentum in gravitational waves as they merge. Recoils imparted to the black-hole remnant can reach thousands of km /s , thus ejecting black holes from their host galaxies. We exploit recent advances in gravitational waveform modeling to quickly and reliably extract recoils imparted to generic, precessing, black-hole binaries. Our procedure uses a numerical-relativity surrogate model to obtain the gravitational waveform given a set of binary parameters; then, from this waveform we directly integrate the gravitational-wave linear momentum flux. This entirely bypasses the need for fitting formulas which are typically used to model black-hole recoils in astrophysical contexts. We provide a thorough exploration of the black-hole kick phenomenology in the parameter space, summarizing and extending previous numerical results on the topic. Our extraction procedure is made publicly available as a module for the Python programming language named surrkick. Kick evaluations take ˜0.1 s on a standard off-the-shelf machine, thus making our code ideal to be ported to large-scale astrophysical studies.

  8. Utilisation of transparent synthetic soil surrogates in geotechnical physical models: A review

    Directory of Open Access Journals (Sweden)

    Abideen Adekunle Ganiyu

    2016-08-01

    Full Text Available Efforts to obtain non-intrusive measurement of deformations and spatial flow within soil mass prior to the advent of transparent soils have perceptible limitations. The transparent soil is a two-phase medium composed of both the synthetic aggregate and fluid components of identical refractive indices aiming at attaining transparency of the resulting soil. The transparency facilitates real life visualisation of soil continuum in physical models. When applied in conjunction with advanced photogrammetry and image processing techniques, transparent soils enable the quantification of the spatial deformation, displacement and multi-phase flow in physical model tests. Transparent synthetic soils have been successfully employed in geotechnical model tests as soil surrogates based on the testing results of their geotechnical properties which replicate those of natural soils. This paper presents a review on transparent synthetic soils and their numerous applications in geotechnical physical models. The properties of the aggregate materials are outlined and the features of the various transparent clays and sands available in the literature are described. The merits of transparent soil are highlighted and the need to amplify its application in geotechnical physical model researches is emphasised. This paper will serve as a concise compendium on the subject of transparent soils for future researchers in this field.

  9. Effect of Surrogate Aggregates on the Thermal Conductivity of Concrete at Ambient and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Tae Sup Yun

    2014-01-01

    Full Text Available The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100°C during heating to ~800°C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m−1 K−1. The surrogate aggregates effectively reduce the conductivity to ~1.25 W m−1 K−1 at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

  10. Preparation and characterization of the perovskite catalysts : activity studies for diesel surrogate (dodecane) reforming

    Energy Technology Data Exchange (ETDEWEB)

    Kondakindi, R.; Kundu, A.; Karan, K.; Peppley, B. [Queen' s-RMC Fuel Cell Research Centre, Kingston, ON (Canada)

    2009-07-01

    Canada's northern communities rely on diesel fuel for generating electricity. The process of converting diesel to electricity in internal combustion engines is not efficient and generates significant amounts of unwanted products. This paper presented an alternative process whereby diesel is reformed into hydrogen-rich reformate which can then be fed to a solid oxide fuel cell. This alternative process converts energy more efficiently and eliminates the formation of nitrogen oxides (NOx) and soot. This study focused on the development of LaFeO{sub 3} based perovskite catalysts for diesel reforming. The activity of the perovskite catalysts was assessed for steam reforming of dodecane, a surrogate for diesel. In order to study the effect on catalytic activity, various perovskite materials were prepared by doping the perovskite at A-site to minimize the coke deposition and at B-site to improve the activity. Preliminary results for dodecane reforming for selected perovskites were promising. Additional testing is underway regarding catalyst activity and stability studies as well carbon and sulphur poisoning.

  11. adapta~k>n -11 of the surrogate memods for linear programming ...

    African Journals Online (AJOL)

    2005-08-02

    Aug 2, 2005 ... inequality problem is made uj~ of the primal and dual optimal solutions for the given primal ... KEYWORDS: Linear Programming, Duality Theory, Surrogate Methods. ..... replaces x and the process IS repeated with the new x.

  12. Spot Sampling and Exposure Surrogate Selection as Sources of Bias in Environmental Epidemiology Studies

    Science.gov (United States)

    Spot measurements of chemical biomarkers are often used as quantitative exposure surrogates in environmental epidemiology studies. These measures can be expressed a number of different ways – for example, urinary biomarkers can be expressed in units of concentration (&micr...

  13. An improved and explicit surrogate variable analysis procedure by coefficient adjustment.

    Science.gov (United States)

    Lee, Seunggeun; Sun, Wei; Wright, Fred A; Zou, Fei

    2017-06-01

    Unobserved environmental, demographic, and technical factors can negatively affect the estimation and testing of the effects of primary variables. Surrogate variable analysis, proposed to tackle this problem, has been widely used in genomic studies. To estimate hidden factors that are correlated with the primary variables, surrogate variable analysis performs principal component analysis either on a subset of features or on all features, but weighting each differently. However, existing approaches may fail to identify hidden factors that are strongly correlated with the primary variables, and the extra step of feature selection and weight calculation makes the theoretical investigation of surrogate variable analysis challenging. In this paper, we propose an improved surrogate variable analysis using all measured features that has a natural connection with restricted least squares, which allows us to study its theoretical properties. Simulation studies and real data analysis show that the method is competitive to state-of-the-art methods.

  14. A reaction mechanism for gasoline surrogate fuels for large polycyclic aromatic hydrocarbons

    KAUST Repository

    Raj, Abhijeet; Charry Prada, Iran David; Amer, Ahmad Amer; Chung, Suk-Ho

    2012-01-01

    This work aims to develop a reaction mechanism for gasoline surrogate fuels (n-heptane, iso-octane and toluene) with an emphasis on the formation of large polycyclic aromatic hydrocarbons (PAHs). Starting from an existing base mechanism for gasoline

  15. Acylation-stimulating protein is a surrogate biomarker for acute myocardial infarction: Role of statins

    Directory of Open Access Journals (Sweden)

    Hayder M Al-Kuraishy

    2017-01-01

    Conclusion: ASP levels are elevated in patients with acute MI and regarded as surrogate biomarker for acute MI also; therapy with statins leads to significant reduction in ASP levels compared to nonstatins-treated patients that presented with acute MI.

  16. First Trimester Hemolysis, Elevated Liver Enzymes, Low Platelets Syndrome in a Surrogate Pregnancy.

    Science.gov (United States)

    Myer, Emily; Hill, James

    2015-10-01

    Background The occurrence of hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome before 20 weeks of gestation is rare. HELLP is a possible but rare syndrome in gestational surrogate pregnancies for surrogates with risk factors for development of preeclampsia. Case A 32-year-old patient with chronic hypertension and positive antinuclear antibody presented for prenatal care at 13 weeks and 1 day. She was a surrogate for the embryo of a 43-year-old couple. By 15 weeks she developed uncontrolled hypertension requiring hospitalization. She was expectantly managed until her condition deteriorated. At 16 weeks and 1 day she developed hemolysis, elevated liver enzymes, thrombocytopenia, and fetal demise. Conclusions HELLP syndrome is rare and carries a significant morbidity and mortality for the mother and fetus. Clinicians should encourage the surrogate to share her medical history with the embryo donor for appropriate counseling on pregnancy risks.

  17. Surrogate Models for Online Monitoring and Process Troubleshooting of NBR Emulsion Copolymerization

    Directory of Open Access Journals (Sweden)

    Chandra Mouli R. Madhuranthakam

    2016-03-01

    Full Text Available Chemical processes with complex reaction mechanisms generally lead to dynamic models which, while beneficial for predicting and capturing the detailed process behavior, are not readily amenable for direct use in online applications related to process operation, optimisation, control, and troubleshooting. Surrogate models can help overcome this problem. In this research article, the first part focuses on obtaining surrogate models for emulsion copolymerization of nitrile butadiene rubber (NBR, which is usually produced in a train of continuous stirred tank reactors. The predictions and/or profiles for several performance characteristics such as conversion, number of polymer particles, copolymer composition, and weight-average molecular weight, obtained using surrogate models are compared with those obtained using the detailed mechanistic model. In the second part of this article, optimal flow profiles based on dynamic optimisation using the surrogate models are obtained for the production of NBR emulsions with the objective of minimising the off-specification product generated during grade transitions.

  18. Experimental Validation of Surrogate Models for Predicting the Draping of Physical Interpolating Surfaces

    DEFF Research Database (Denmark)

    Christensen, Esben Toke; Lund, Erik; Lindgaard, Esben

    2018-01-01

    This paper concerns the experimental validation of two surrogate models through a benchmark study involving two different variable shape mould prototype systems. The surrogate models in question are different methods based on kriging and proper orthogonal decomposition (POD), which were developed...... to the performance of the studied surrogate models. By comparing surrogate model performance for the two variable shape mould systems, and through a numerical study involving simple finite element models, the underlying cause of this effect is explained. It is concluded that for a variable shape mould prototype...... hypercube approach. This sampling method allows for generating a space filling and high-quality sample plan that respects mechanical constraints of the variable shape mould systems. Through the benchmark study, it is found that mechanical freeplay in the modeled system is severely detrimental...

  19. Surrogate Plant Data Base : Volume 4. Appendix E : Medium and Heavy Truck Manufacturing

    Science.gov (United States)

    1983-05-01

    This four volume report consists of a data base describing "surrogate" automobile and truck manufacturing plants developed as part of a methodology for evaluating capital investment requirements in new manufacturing facilities to build new fleets of ...

  20. Surrogate Plant Data Base : Volume 2. Appendix C : Facilities Planning Baseline Data

    Science.gov (United States)

    1983-05-01

    This four volume report consists of a data base describing "surrogate" automobile and truck manufacturing plants developed as part of a methodology for evaluating capital investment requirements in new manufacturing facilities to build new fleets of ...

  1. An Efficient Constraint Boundary Sampling Method for Sequential RBDO Using Kriging Surrogate Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihoon; Jang, Junyong; Kim, Shinyu; Lee, Tae Hee [Hanyang Univ., Seoul (Korea, Republic of); Cho, Sugil; Kim, Hyung Woo; Hong, Sup [Korea Research Institute of Ships and Ocean Engineering, Busan (Korea, Republic of)

    2016-06-15

    Reliability-based design optimization (RBDO) requires a high computational cost owing to its reliability analysis. A surrogate model is introduced to reduce the computational cost in RBDO. The accuracy of the reliability depends on the accuracy of the surrogate model of constraint boundaries in the surrogated-model-based RBDO. In earlier researches, constraint boundary sampling (CBS) was proposed to approximate accurately the boundaries of constraints by locating sample points on the boundaries of constraints. However, because CBS uses sample points on all constraint boundaries, it creates superfluous sample points. In this paper, efficient constraint boundary sampling (ECBS) is proposed to enhance the efficiency of CBS. ECBS uses the statistical information of a kriging surrogate model to locate sample points on or near the RBDO solution. The efficiency of ECBS is verified by mathematical examples.

  2. Developing the role of the social worker as coordinator of services at the surrogate parenting center.

    Science.gov (United States)

    Gagin, Roni; Cohen, Miri; Greenblatt, Lee; Solomon, Hanah; Itskovitz-Eldor, Joseph

    2004-01-01

    A law permitting couples to conceive biological children through surrogacy was legislated in Israel in March 1996. The Rambam Medical Center has established the only nonprofit Surrogate Parenting Center at a public hospital in Israel. The multidisciplinary teamwork at the Center is case managed by a social worker. An important role of the social work intervention is consultation and support for the couple and the surrogate at all stages of the process. The case study presented in the article illustrates the need for sensitive and professional intervention due to the complexity of the surrogacy process and the crisis it involves for both the surrogate and the couple. In light of the growing parenting surrogacy cases in the United States, Europe, and Israel, a structured social work intervention model is described, which may be implemented at public or private surrogate parenting centers.

  3. Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation

    KAUST Repository

    Kadoura, Ahmad Salim; Siripatana, Adil; Sun, Shuyu; Knio, Omar; Hoteit, Ibrahim

    2016-01-01

    In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard

  4. Soot formation characteristics of gasoline surrogate fuels in counterflow diffusion flames

    KAUST Repository

    Choi, Byungchul; Choi, Sangkyu; Chung, Suk-Ho

    2011-01-01

    The characteristics of polycyclic aromatic hydrocarbon (PAH) and soot for gasoline surrogate fuels have been investigated in counterflow diffusion flames by adopting laser-induced fluorescence (LIF) and laser-induced incandescence (LII) techniques

  5. Plutonium and surrogate fission products in a composite ceramic waste form

    International Nuclear Information System (INIS)

    Esh, D. W.; Frank, S. M.; Goff, K. M.; Johnson, S. G.; Moschetti, T. L.; O'Holleran, T.

    1999-01-01

    Argonne National Laboratory is developing a ceramic waste form to immobilize salt containing fission products and transuranic elements. Preliminary results have been presented for ceramic waste forms containing surrogate fission products such as cesium and the lanthanides. In this work results from scanning electron microscopy/energy dispersive spectroscopy and x-ray diffraction are presented in greater detail for ceramic waste forms containing surrogate fission products. Additionally, results for waste forms containing plutonium and surrogate fission products are presented. Most of the surrogate fission products appear to be silicates or aluminosilicates whereas the plutonium is usually found in an oxide form. There is also evidence for the presence of plutonium within the sodalite phase although the chemical speciation of the plutonium is not known

  6. A Successful Induction of Lactation in Surrogate Pregnancy with Metoclopramide and Review of Lactation Induction

    OpenAIRE

    Elahe Mirzaaga; Arezoo Arabipoor; Mitra Frotan; Marzieh Shiva

    2010-01-01

    In surrogate pregnancies genetic parents have little opportunity for early bonding with their infants,either prenatally (in utero) or during the immediate postnatal period. Procedures commonlyused to induce lactation include both pharmacologic and nonpharmacologic methods, often incombination. Studies reporting induced lactation are sparse, due to the rarity of augmentedlactation. Here we report a case of lactation induction following a surrogate pregnancy. Othermethods that can be used to au...

  7. Induction of lactation in the intended mother of a surrogate pregnancy: case report.

    Science.gov (United States)

    Biervliet, F P; Maguiness, S D; Hay, D M; Killick, S R; Atkin, S L

    2001-03-01

    A case of a successful induction of lactation in a commissioning mother of a surrogate pregnancy is reported. Induction of lactation was achieved with oral metoclopramide which was well tolerated. Alternative methods to induce lactation are reviewed. The advantages of breast-feeding and the relative ease with which lactation can be induced after a surrogate pregnancy would suggest that this could be offered to all commissioning mothers.

  8. Using multiscale spatial models to assess potential surrogate habitat for an imperiled reptile.

    Directory of Open Access Journals (Sweden)

    Jennifer M Fill

    Full Text Available In evaluating conservation and management options for species, practitioners might consider surrogate habitats at multiple scales when estimating available habitat or modeling species' potential distributions based on suitable habitats, especially when native environments are rare. Species' dependence on surrogates likely increases as optimal habitat is degraded and lost due to anthropogenic landscape change, and thus surrogate habitats may be vital for an imperiled species' survival in highly modified landscapes. We used spatial habitat models to examine a potential surrogate habitat for an imperiled ambush predator (eastern diamondback rattlesnake, Crotalus adamanteus; EDB at two scales. The EDB is an apex predator indigenous to imperiled longleaf pine ecosystems (Pinus palustris of the southeastern United States. Loss of native open-canopy pine savannas and woodlands has been suggested as the principal cause of the species' extensive decline. We examined EDB habitat selection in the Coastal Plain tidewater region to evaluate the role of marsh as a potential surrogate habitat and to further quantify the species' habitat requirements at two scales: home range (HR and within the home range (WHR. We studied EDBs using radiotelemetry and employed an information-theoretic approach and logistic regression to model habitat selection as use vs.We failed to detect a positive association with marsh as a surrogate habitat at the HR scale; rather, EDBs exhibited significantly negative associations with all landscape patches except pine savanna. Within home range selection was characterized by a negative association with forest and a positive association with ground cover, which suggests that EDBs may use surrogate habitats of similar structure, including marsh, within their home ranges. While our HR analysis did not support tidal marsh as a surrogate habitat, marsh may still provide resources for EDBs at smaller scales.

  9. Fabrication and Characterization of Surrogate Glasses Aimed to Validate Nuclear Forensic Techniques

    Science.gov (United States)

    2017-12-01

    the glass formed during a nuclear event, trinitite [14]. The SiO2 composition is generally greater than 50% for trinitite and can vary appreciably...CHARACTERIZATION OF SURROGATE GLASSES AIMED TO VALIDATE NUCLEAR FORENSIC TECHNIQUES by Ken G. Foos December 2017 Thesis Advisor: Claudia...December 2017 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE FABRICATION AND CHARACTERIZATION OF SURROGATE GLASSES AIMED TO

  10. Engagement in Advance Care Planning and Surrogates' Knowledge of Patients' Treatment Goals.

    Science.gov (United States)

    Fried, Terri R; Zenoni, Maria; Iannone, Lynne; O'Leary, John; Fenton, Brenda T

    2017-08-01

    A key objective of advance care planning (ACP) is improving surrogates' knowledge of patients' treatment goals. Little is known about whether ACP outside of a trial accomplishes this. The objective was to examine patient and surrogate reports of ACP engagement and associations with surrogate knowledge of goals. Cohort study SETTING: Primary care in a Veterans Affairs Medical Center. 350 community-dwelling veterans age ≥55 years and the individual they would choose to make medical decisions on their behalf, interviewed separately. Treatment goals were assessed by veterans' ratings of 3 health states: severe physical disability, cognitive disability, and pain, as an acceptable or unacceptable result of treatment for severe illness. Surrogates had knowledge if they correctly predicted all 3 responses. Veterans and surrogates were asked about living will and health care proxy completion and communication about life-sustaining treatment and quality versus quantity of life (QOL). Over 40% of dyads agreed that the veteran had not completed a living will or health care proxy and that there was no QOL communication. For each activity, sizeable proportions (18-34%) disagreed about participation. In dyads who agreed QOL communication had occurred, 30% of surrogates had knowledge, compared to 21% in dyads who agreed communication had not occurred and 15% in dyads who disagreed (P = .01). This relationship persisted in multivariable analysis. Agreement about other ACP activities was not associated with knowledge. Disagreement about ACP participation was common. Agreement about communication regarding QOL was modestly associated with surrogate knowledge of treatment goals. Eliciting surrogates' perspectives is critical to ACP. Even dyads who agree about participation may need additional support for successful engagement. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

  11. Test procedures for polyester immobilized salt-containing surrogate mixed wastes

    International Nuclear Information System (INIS)

    Biyani, R.K.; Hendrickson, D.W.

    1997-01-01

    These test procedures are written to meet the procedural needs of the Test Plan for immobilization of salt containing surrogate mixed waste using polymer resins, HNF-SD-RE-TP-026 and to ensure adequacy of conduct and collection of samples and data. This testing will demonstrate the use of four different polyester vinyl ester resins in the solidification of surrogate liquid and dry wastes, similar to some mixed wastes generated by DOE operations

  12. A surrogate fuel formulation to characterize heating and evaporation of light naphtha droplets

    KAUST Repository

    Kabil, I.

    2018-03-08

    Light naphtha (LN) is gaining interest in internal combustion (IC) engine applications due to its low refining cost and higher heating values compared to commercial gasoline. To properly describe the chemical and physical behavior of the LN fuel under IC engine conditions, a systematic procedure to develop unified physical and chemical surrogates is described. The reduced component models to describe the chemical characteristics of LN are combined with the effective thermal conductivity/effective diffusivity (ETC/ED) model to represent the accurate evaporation behavior. Three surrogate fuels consisting of three to five components are presented and their performance in heating and evaporation of a single LN droplet is compared against the conventional primary reference fuel (PRF65) surrogate which is based on chemical aspects only. Unlike the previous approaches, the new surrogates also target matching the hydrogen-to-carbon ratio and research octane number in order to accurately describe the chemical behavior of the fuel. Subsequently, the performance of the surrogates in describing spray characteristics is tested by computational simulations compared with experimental measurements. The simulations were carried out using CONVERGE CFD package. The ETC/ED model was implemented into CONVERGE using user-defined functions. The predicted spray penetration length for the developed surrogates shows good agreement with the experimental data. At engine-like conditions, the ETC/ED model predicts higher vapor mass than the infinite thermal conductivity/infinite diffusivity model, hence showing the expected trend by incorporating the realistic droplet heating process.

  13. One mum too few: maternal status in host surrogate motherhood arrangements.

    Science.gov (United States)

    Oultram, Stuart

    2015-06-01

    In a host surrogate motherhood arrangement, the surrogate agrees to be implanted with, and carry to term, an embryo created from the commissioning couple's gametes. When the surrogate child is born, it is the surrogate mother who, according to UK law, holds the legal status of mother. By contrast, the commissioning mother possesses no maternal status and she can only attain it once the surrogate agrees to the completion of the arrangement. One consequence of this is that, in the event that a host arrangement fails, the commissioning mother is left without maternal status. In this paper, I argue that this denial of maternal status misrepresents the commissioning mother's role in the host arrangement and her relationship with the surrogate child. Consequently, I suggest that commissioning mothers participating in host surrogacy arrangements ought to be granted the status of mother in the event that the arrangement fails. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. Surrogate alcohol containing methanol, social deprivation and public health in Novosibirsk, Russia.

    Science.gov (United States)

    Neufeld, Maria; Lachenmeier, Dirk; Hausler, Thomas; Rehm, Jürgen

    2016-11-01

    Surrogate alcohol, i.e. alcohol not intended or not officially intended for human consumption, continues to play an important role in alcohol consumption in Russia, especially for people with alcohol dependence. Among the different types of surrogate alcohol, there are windshield washer antifreeze liquids; these products are the cheapest kinds of non-beverage alcohol available and thus likely to be used by the most deprived and marginalised groups such as homeless people with alcohol dependence. Although it is well known, that non-beverage alcohol is used for consumption by various groups in Russia, and although there are laws to prohibit the use of methanol as part of windshield washer antifreeze liquids for the very reason that such products could be used as surrogate alcohol, we detected products in retail sale which were a mix of water and methanol only. Methanol poses serious health threats including blindness and death, and there had been repeated methanol deaths from surrogate alcohol in Russia over the last years. If law-enforcement does not change for surrogate products, we can expect more methanol-resulting deaths in the most deprived and marginalized groups of people with alcohol dependence in Russia. In addition, ingredients with questionable safety profiles such as formic acid should also be prohibited in non-beverage alcohol products that are likely to be consumed as surrogate alcohol. Copyright © 2016. Published by Elsevier B.V.

  15. Concordance Between Veterans' Self-Report and Documentation of Surrogate Decision Makers: Implications for Quality Measurement.

    Science.gov (United States)

    Garner, Kimberly K; Dubbert, Patricia; Lensing, Shelly; Sullivan, Dennis H

    2017-01-01

    The Measuring What Matters initiative of the American Academy of Hospice and Palliative Medicine and the Hospice and Palliative Nurses Association identified documentation of a surrogate decision maker as one of the top 10 quality indicators in the acute hospital and hospice settings. To better understand the potential implementation of this Measuring What Matters quality measure #8, Documentation of Surrogate in outpatient primary care settings by describing primary care patients' self-reported identification and documentation of a surrogate decision maker. Examination of patient responses to self-assessment questions from advance health care planning educational groups conducted in one medical center primary care clinic and seven community-based outpatient primary care clinics. We assessed the concordance between patient reports of identifying and naming a surrogate decision maker and having completed an advance directive (AD) with presence of an AD in the electronic medical record. Of veterans without a documented AD on file, more than half (66%) reported that they had talked with someone they trusted and nearly half (52%) reported that they had named someone to communicate their preferences. Our clinical project data suggest that many more veterans may have initiated communications with surrogate decision makers than is evident in the electronic medical record. System changes are needed to close the gap between veterans' plans for a surrogate decision maker and the documentation available to acute care health care providers. Published by Elsevier Inc.

  16. Comparative study of surrogate models for groundwater contamination source identification at DNAPL-contaminated sites

    Science.gov (United States)

    Hou, Zeyu; Lu, Wenxi

    2018-05-01

    Knowledge of groundwater contamination sources is critical for effectively protecting groundwater resources, estimating risks, mitigating disaster, and designing remediation strategies. Many methods for groundwater contamination source identification (GCSI) have been developed in recent years, including the simulation-optimization technique. This study proposes utilizing a support vector regression (SVR) model and a kernel extreme learning machine (KELM) model to enrich the content of the surrogate model. The surrogate model was itself key in replacing the simulation model, reducing the huge computational burden of iterations in the simulation-optimization technique to solve GCSI problems, especially in GCSI problems of aquifers contaminated by dense nonaqueous phase liquids (DNAPLs). A comparative study between the Kriging, SVR, and KELM models is reported. Additionally, there is analysis of the influence of parameter optimization and the structure of the training sample dataset on the approximation accuracy of the surrogate model. It was found that the KELM model was the most accurate surrogate model, and its performance was significantly improved after parameter optimization. The approximation accuracy of the surrogate model to the simulation model did not always improve with increasing numbers of training samples. Using the appropriate number of training samples was critical for improving the performance of the surrogate model and avoiding unnecessary computational workload. It was concluded that the KELM model developed in this work could reasonably predict system responses in given operation conditions. Replacing the simulation model with a KELM model considerably reduced the computational burden of the simulation-optimization process and also maintained high computation accuracy.

  17. Development of an instrumented spinal cord surrogate using optical fibers: A feasibility study.

    Science.gov (United States)

    Facchinello, Yann; Wagnac, Éric; Ung, Bora; Petit, Yvan; Pradhan, Prabin; Peyrache, Louis-Marie; Mac-Thiong, Jean-Marc

    2017-10-01

    In vitro replication of traumatic spinal cord injury is necessary to understand its biomechanics and to improve animal models. During a traumatic spinal cord injury, the spinal cord withstands an impaction at high velocity. In order to fully assess the impaction, the use of spinal canal occlusion sensor is necessary. A physical spinal cord surrogate is also often used to simulate the presence of the spinal cord and its surrounding structures. In this study, an instrumented physical spinal cord surrogate is presented and validated. The sensing is based on light transmission loss observed in embedded bare optical fibers subjected to bending. The instrumented surrogate exhibits similar mechanical properties under static compression compared to fresh porcine spinal cords. The instrumented surrogate has a compression sensing threshold of 40% that matches the smallest compression values leading to neurological injuries. The signal obtained from the sensor allows calculating the compression of the spinal cord surrogate with a maximum of 5% deviation. Excellent repeatability was also observed under repetitive loading. The proposed instrumented spinal cord surrogate is promising with satisfying mechanical properties and good sensing capability. It is the first attempt at proposing a method to assess the internal loads sustained by the spinal cord during a traumatic injury. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  18. A conceptual model of the role of communication in surrogate decision making for hospitalized adults.

    Science.gov (United States)

    Torke, Alexia M; Petronio, Sandra; Sachs, Greg A; Helft, Paul R; Purnell, Christianna

    2012-04-01

    To build a conceptual model of the role of communication in decision making, based on literature from medicine, communication studies and medical ethics. We proposed a model and described each construct in detail. We review what is known about interpersonal and patient-physician communication, described literature about surrogate-clinician communication, and discussed implications for our developing model. The communication literature proposes two major elements of interpersonal communication: information processing and relationship building. These elements are composed of constructs such as information disclosure and emotional support that are likely to be relevant to decision making. We propose these elements of communication impact decision making, which in turn affects outcomes for both patients and surrogates. Decision making quality may also mediate the relationship between communication and outcomes. Although many elements of the model have been studied in relation to patient-clinician communication, there is limited data about surrogate decision making. There is evidence of high surrogate distress associated with decision making that may be alleviated by communication-focused interventions. More research is needed to test the relationships proposed in the model. Good communication with surrogates may improve both the quality of medical decisions and outcomes for the patient and surrogate. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  19. Modeling of Heating and Evaporation of FACE I Gasoline Fuel and its Surrogates

    KAUST Repository

    Elwardani, Ahmed Elsaid

    2016-04-05

    The US Department of Energy has formulated different gasoline fuels called \\'\\'Fuels for Advanced Combustion Engines (FACE)\\'\\' to standardize their compositions. FACE I is a low octane number gasoline fuel with research octane number (RON) of approximately 70. The detailed hydrocarbon analysis (DHA) of FACE I shows that it contains 33 components. This large number of components cannot be handled in fuel spray simulation where thousands of droplets are directly injected in combustion chamber. These droplets are to be heated, broken-up, collided and evaporated simultaneously. Heating and evaporation of single droplet FACE I fuel was investigated. The heating and evaporation model accounts for the effects of finite thermal conductivity, finite liquid diffusivity and recirculation inside the droplet, referred to as the effective thermal conductivity/effective diffusivity (ETC/ED) model. The temporal variations of the liquid mass fractions of the droplet components were used to characterize the evaporation process. Components with similar evaporation characteristics were merged together. A representative component was initially chosen based on the highest initial mass fraction. Three 6 components surrogates, Surrogate 1-3, that match evaporation characteristics of FACE I have been formulated without keeping same mass fractions of different hydrocarbon types. Another two surrogates (Surrogate 4 and 5) were considered keeping same hydrocarbon type concentrations. A distillation based surrogate that matches measured distillation profile was proposed. The calculated molar mass, hydrogen-to-carbon (H/C) ratio and RON of Surrogate 4 and distillation based one are close to those of FACE I.

  20. A surrogate fuel formulation to characterize heating and evaporation of light naphtha droplets

    KAUST Repository

    Kabil, I.; Sim, J.; Badra, J.A.; Eldrainy, Y.; Abdelghaffar, W.; Mubarak Ali, M. Jaasim; Ahmed, Ahfaz; Sarathy, Mani; Im, Hong G.; Elwardani, Ahmed Elsaid

    2018-01-01

    Light naphtha (LN) is gaining interest in internal combustion (IC) engine applications due to its low refining cost and higher heating values compared to commercial gasoline. To properly describe the chemical and physical behavior of the LN fuel under IC engine conditions, a systematic procedure to develop unified physical and chemical surrogates is described. The reduced component models to describe the chemical characteristics of LN are combined with the effective thermal conductivity/effective diffusivity (ETC/ED) model to represent the accurate evaporation behavior. Three surrogate fuels consisting of three to five components are presented and their performance in heating and evaporation of a single LN droplet is compared against the conventional primary reference fuel (PRF65) surrogate which is based on chemical aspects only. Unlike the previous approaches, the new surrogates also target matching the hydrogen-to-carbon ratio and research octane number in order to accurately describe the chemical behavior of the fuel. Subsequently, the performance of the surrogates in describing spray characteristics is tested by computational simulations compared with experimental measurements. The simulations were carried out using CONVERGE CFD package. The ETC/ED model was implemented into CONVERGE using user-defined functions. The predicted spray penetration length for the developed surrogates shows good agreement with the experimental data. At engine-like conditions, the ETC/ED model predicts higher vapor mass than the infinite thermal conductivity/infinite diffusivity model, hence showing the expected trend by incorporating the realistic droplet heating process.

  1. Enhancing Convective Heat Transfer over a Surrogate Photovoltaic Panel

    Science.gov (United States)

    Fouladi, Fama

    This research is particularly focused on studying heat transfer enhancement of a photovoltaic (PV) panel by putting an obstacle at the panel's windward edge. The heat transfer enhancement is performed by disturbing the airflow over the surface and increasing the heat and momentum transfer. Different objects such as triangular, square, rectangular, and discrete rectangular ribs and partial grids were applied at the leading edge of a surrogate PV panel and flow and the heat transfer of the panel are investigated experimentally. This approach was selected to expand understanding of effect of these different objects on the flow and turbulence structures over a flat surface by analyzing the flow comprehensively. It is observed that, a transverse object at the plate's leading edge would cause some flow blockage in the streamwise direction, but at the same time creates some velocity in the normal and cross stream directions. In addition to that, the obstacle generates some turbulence over the surface which persists for a long downstream distance. Also, among all studied objects, discrete rectangular ribs demonstrate the highest heat transfer rate enhancement (maximum Nu/Nu0 of 1.5). However, ribs with larger gap ratios are observed to be more effective at enhancing the heat transfer augmentation at closer distances to the rib, while at larger downstream distances from the rib, discrete ribs with smaller gap ratios are more effective. Furthermore, this work attempted to recognize the most influential flow parameters on the heat transfer enhancement of the surface. It is seen that the flow structure over a surface downstream of an object (flow separation-reattachment behaviour) has a significant effect on the heat transfer enhancement trend. Also, turbulence intensities are the most dominant parameters in enhancing the heat transfer rate from the surface; however, flow velocity (mostly normal velocity) is also an important factor.

  2. Composite Sampling Approaches for Bacillus anthracis Surrogate Extracted from Soil.

    Directory of Open Access Journals (Sweden)

    Brian France

    Full Text Available Any release of anthrax spores in the U.S. would require action to decontaminate the site and restore its use and operations as rapidly as possible. The remediation activity would require environmental sampling, both initially to determine the extent of contamination (hazard mapping and post-decon to determine that the site is free of contamination (clearance sampling. Whether the spore contamination is within a building or outdoors, collecting and analyzing what could be thousands of samples can become the factor that limits the pace of restoring operations. To address this sampling and analysis bottleneck and decrease the time needed to recover from an anthrax contamination event, this study investigates the use of composite sampling. Pooling or compositing of samples is an established technique to reduce the number of analyses required, and its use for anthrax spore sampling has recently been investigated. However, use of composite sampling in an anthrax spore remediation event will require well-documented and accepted methods. In particular, previous composite sampling studies have focused on sampling from hard surfaces; data on soil sampling are required to extend the procedure to outdoor use. Further, we must consider whether combining liquid samples, thus increasing the volume, lowers the sensitivity of detection and produces false negatives. In this study, methods to composite bacterial spore samples from soil are demonstrated. B. subtilis spore suspensions were used as a surrogate for anthrax spores. Two soils (Arizona Test Dust and sterilized potting soil were contaminated and spore recovery with composites was shown to match individual sample performance. Results show that dilution can be overcome by concentrating bacterial spores using standard filtration methods. This study shows that composite sampling can be a viable method of pooling samples to reduce the number of analysis that must be performed during anthrax spore remediation.

  3. Destruction of DOE/DP surrogate wastes with supercritical water oxidation technology

    International Nuclear Information System (INIS)

    Bramlette, T.T.; Mills, B.E.; Hencken, K.R.; Brynildson, M.E.; Johnston, S.C.; Hruby, J.M.; Freemster, H.C.; Odegard, B.C.; Modell, M.

    1990-11-01

    Surrogate wastes of specific interest to DOE/DP production facilities (Hanford and Rocky Flats), and the electronics industry have been successfully processed in a laboratory-scale, supercritical water oxidation flow reactor. In all cases, the observed destruction/reduction efficiencies for the organic components were in excess of 99.9%, limited by instrumentation detection capability. Separation of the inorganic components of the Hanford process stream was more difficult to accomplish than destruction of the organic component. Large fractions of all metals contained in this stream were found both in the solids separator effluent and in deposits removed from the reactor. Mass closure was not achieved. Of the process stream's non-metallic, inorganic components, the sulfates and phosphates precipitated, while the nitrates tended to stay in solution. The inorganic material that did precipitate from the simulated Hanford mixed waste accumulated in zones that may be associated with changes in the chemical and physical properties of the supercritical fluid. Corrosion is expected to be a significant problem. Witness wires of Inconel 625, Hastalloy C-276, and titanium placed in the preheater, reactor and cooldown exchanger indicated selective dissolution of chromium, nickel, and molybdenum for some conditions, and non-selective dissolution for others. While these results are very promising, further research is required to evaluate the scalability, reliability, and economics of SCWO reactor components and systems, particularly for mixed wastes. Future research must explore a parameter space (temperature, pressure, pH, residence time, etc.) focused on selecting conditions and materials for specific process streams

  4. Milling Behavior of Matrix Graphite Powders with Different Binder Materials in HTGR Fuel Element Fabrication: I. Variation in Particle Size Distribution

    International Nuclear Information System (INIS)

    Lee, Young Woo; Cho, Moon Sung

    2011-01-01

    The fuel element for HTGR is manufactured by mixing coated fuel particles with matrix graphite powder and forming into either pebble type or cylindrical type compacts depending on their use in different HTGR cores. The coated fuel particle, the so-called TRISO particle, consists of 500-μm spherical UO 2 particles coated with the low density buffer Pyrolytic Carbon (PyC) layer, the inner and outer high density PyC layer and SiC layer sandwiched between the two inner and outer PyC layers. The coated TRISO particles are mixed with a matrix graphite powder properly prepared and pressed into a spherical shape or a cylindrical compact finally heat-treated at about 1900 .deg. C. These fuel elements can have different sizes and forms of compact. The basic steps for manufacturing a fuel element include preparation of graphite matrix powder, overcoating the fuel particles, mixing the fuel particles with a matrix powder, carbonizing green compact, and the final high-temperature heat treatment of the carbonized fuel compact. In order to develop a fuel compact fabrication technology, it is important to develop a technology to prepare the matrix graphite powder (MGP) with proper characteristics, which has a strong influence on further steps and the material properties of fuel element. In this work, the milling behavior of matrix graphite powder mixture with different binder materials and their contents was investigated by analyzing the change in particle size distribution with different milling time

  5. Biomedically assisted reproduction and child birth: Surrogate motherhood in comparative European law and Serbia

    Directory of Open Access Journals (Sweden)

    Kovaček-Stanić Gordana

    2013-01-01

    Full Text Available Surrogate motherhood is an arrangement in which a woman agrees to carry and deliver a child for another couple who ordered the pregnancy. This procedure is applied today in Great Britain, Holland (although without legal regulations, Israel, Greece, Ukraine, Armenia, Georgia, the USA and Australia, and it is forbidden in France, Austria, Spain, Germany, Switzerland and Slovenia. There are two types of surrogacy, one when the woman gives birth to a child who is genetically her own ("partial", genetic surrogacy, and the other where the surrogate mother only carries and gives birth to a child, whereby the child is genetically from the couple that wanted the child, or the fertilized egg is from a third woman (donor, or the embryo was donated ("full", "total", gestational surrogacy. In these cases two women take part in conception and birth of the child while in the last case there is a third woman who will raise the child. Biologically observed, the woman whose egg has been fertilized may be called the genetic mother, while the woman who carried the pregnancy and gave birth to the child - the gestational carrier. Taking into consideration that the Preliminary Draft of the Serbian Civil Law anticipates the introduction of surrogate motherhood into domestic law, we believe restrictive solutions should first be taken into consideration. This would mean that only full surrogating should be allowed, namely the egg should be from the woman who wants the child and not the surrogate mother. In domestic conditions, genetic surrogation should not be allowed as it leads to confusion in family relations, and kinships still have an important social and legal significance in our country. The surrogate mother should be a woman who has already given birth, because in that way any possible shocks which might arise after birth when the woman who has to handover the child to the intended couple would be avoided. The next condition would be that persons involved in this

  6. Coastal aquifer management under parameter uncertainty: Ensemble surrogate modeling based simulation-optimization

    Science.gov (United States)

    Janardhanan, S.; Datta, B.

    2011-12-01

    Surrogate models are widely used to develop computationally efficient simulation-optimization models to solve complex groundwater management problems. Artificial intelligence based models are most often used for this purpose where they are trained using predictor-predictand data obtained from a numerical simulation model. Most often this is implemented with the assumption that the parameters and boundary conditions used in the numerical simulation model are perfectly known. However, in most practical situations these values are uncertain. Under these circumstances the application of such approximation surrogates becomes limited. In our study we develop a surrogate model based coupled simulation optimization methodology for determining optimal pumping strategies for coastal aquifers considering parameter uncertainty. An ensemble surrogate modeling approach is used along with multiple realization optimization. The methodology is used to solve a multi-objective coastal aquifer management problem considering two conflicting objectives. Hydraulic conductivity and the aquifer recharge are considered as uncertain values. Three dimensional coupled flow and transport simulation model FEMWATER is used to simulate the aquifer responses for a number of scenarios corresponding to Latin hypercube samples of pumping and uncertain parameters to generate input-output patterns for training the surrogate models. Non-parametric bootstrap sampling of this original data set is used to generate multiple data sets which belong to different regions in the multi-dimensional decision and parameter space. These data sets are used to train and test multiple surrogate models based on genetic programming. The ensemble of surrogate models is then linked to a multi-objective genetic algorithm to solve the pumping optimization problem. Two conflicting objectives, viz, maximizing total pumping from beneficial wells and minimizing the total pumping from barrier wells for hydraulic control of

  7. Observation of Burial and Migration of Instrumented Surrogate Munitions Deployed in the Swash Zone

    Science.gov (United States)

    Cristaudo, D.; Puleo, J. A.; Bruder, B. L.

    2017-12-01

    Munitions (also known as unexploded ordnance; UXO) in the nearshore environment due to past military activities, may be found on the beach, constituting a risk for beach users. Munitions may be transported from offshore to shallower water and/or migrate along the coast. In addition, munitions may bury in place or be exhumed due to hydrodynamic forcing. Observations on munitions mobility have generally been collected offshore, while observations in the swash zone are scarce. The swash zone is the region of the beach alternately covered by wave runup where hydrodynamic processes may be intense. Studies of munitions mobility require the use of realistic surrogates to quantify mobility/burial and hydrodynamic forcing conditions. Four surrogates (BLU-61 Cluster Bomb, 81 mm Mortar, M151-70 Hydra Rocket and M107 155 mm High Explosive Howitzer) were developed and tested during large-scale laboratory and field studies. Surrogates house sensors that measure different components of motion. Errors between real munitions and surrogate parameters (mass, center of gravity and axial moment of inertia) are all within an absolute error of 20%. Internal munitions sensors consist of inertial motion units (for acceleration and angular velocity in and around the three directions and orientation), pressure transducers (for water depth above surrogate), shock recorders (for high frequency acceleration to detect wave impact on the surrogate), and an in-house designed array of optical sensors (for burial/exposure and rolling). An in situ array of sensors to measure hydrodynamics, bed morphology and sediment concentrations, was deployed in the swash zone, aligned with the surrogate deployment. Data collected during the studies will be shown highlighting surrogate sensor capabilities. Sensors response will be compared with GPS measurements and imagery from cameras overlooking the study sites of surrogate position as a function of time. Examples of burial/exposure and migration of surrogates

  8. The Proposed Use of Unmanned Aerial System Surrogate Research Aircraft for National Airspace System Integration Research

    Science.gov (United States)

    Howell, Charles T., III

    2011-01-01

    Research is needed to determine what procedures, aircraft sensors and other systems will be required to allow Unmanned Aerial Systems (UAS) to safely operate with manned aircraft in the National Airspace System (NAS). This paper explores the use of Unmanned Aerial System (UAS) Surrogate research aircraft to serve as platforms for UAS systems research, development, and flight testing. These aircraft would be manned with safety pilots and researchers that would allow for flight operations almost anywhere in the NAS without the need for a Federal Aviation Administration (FAA) Certificate of Authorization (COA). With pilot override capability, these UAS Surrogate aircraft would be controlled from ground stations like true UAS s. It would be possible to file and fly these UAS Surrogate aircraft in the NAS with normal traffic and they would be better platforms for real world UAS research and development over existing vehicles flying in restricted ranges or other sterilized airspace. These UAS surrogate aircraft could be outfitted with research systems as required such as computers, state sensors, video recording, data acquisition, data link, telemetry, instrumentation, and Automatic Dependent Surveillance-Broadcast (ADS-B). These surrogate aircraft could also be linked to onboard or ground based simulation facilities to further extend UAS research capabilities. Potential areas for UAS Surrogate research include the development, flight test and evaluation of sensors to aide in the process of air traffic "see-and-avoid". These and other sensors could be evaluated in real-time and compared with onboard human evaluation pilots. This paper examines the feasibility of using UAS Surrogate research aircraft as test platforms for a variety of UAS related research.

  9. Robust estimation of the proportion of treatment effect explained by surrogate marker information.

    Science.gov (United States)

    Parast, Layla; McDermott, Mary M; Tian, Lu

    2016-05-10

    In randomized treatment studies where the primary outcome requires long follow-up of patients and/or expensive or invasive obtainment procedures, the availability of a surrogate marker that could be used to estimate the treatment effect and could potentially be observed earlier than the primary outcome would allow researchers to make conclusions regarding the treatment effect with less required follow-up time and resources. The Prentice criterion for a valid surrogate marker requires that a test for treatment effect on the surrogate marker also be a valid test for treatment effect on the primary outcome of interest. Based on this criterion, methods have been developed to define and estimate the proportion of treatment effect on the primary outcome that is explained by the treatment effect on the surrogate marker. These methods aim to identify useful statistical surrogates that capture a large proportion of the treatment effect. However, current methods to estimate this proportion usually require restrictive model assumptions that may not hold in practice and thus may lead to biased estimates of this quantity. In this paper, we propose a nonparametric procedure to estimate the proportion of treatment effect on the primary outcome that is explained by the treatment effect on a potential surrogate marker and extend this procedure to a setting with multiple surrogate markers. We compare our approach with previously proposed model-based approaches and propose a variance estimation procedure based on a perturbation-resampling method. Simulation studies demonstrate that the procedure performs well in finite samples and outperforms model-based procedures when the specified models are not correct. We illustrate our proposed procedure using a data set from a randomized study investigating a group-mediated cognitive behavioral intervention for peripheral artery disease participants. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Ovulation Statuses of Surrogate Gilts Are Associated with the Efficiency of Excellent Pig Cloning.

    Directory of Open Access Journals (Sweden)

    Yanjun Huan

    Full Text Available Somatic cell nuclear transfer (SCNT is an assisted reproductive technique that can produce multiple copies of excellent livestock. However, low cloning efficiency limits the application of SCNT. In this study, we systematically investigated the major influencing factors related to the overall cloning efficiency in pigs. Here, 13620 cloned embryos derived from excellent pigs were transferred into 79 surrogate gilts, and 119 live cloned piglets were eventually generated. During cloning, group of cloned embryos derived from excellent Landrace or Large white pigs presented no significant differences of cleavage and blastocyst rates, blastocyst cell numbers, surrogate pregnancy and delivery rates, average numbers of piglets born and alive and cloning efficiencies, and group of 101-150, 151-200 or 201-250 cloned embryos transferred per surrogate also displayed a similar developmental efficiency. When estrus stage of surrogate gilts was compared, group of embryo transfer on Day 2 of estrus showed significantly higher pregnancy rate, delivery rate, average number of piglets born, average alive piglet number or cloning efficiency than group on Day 1, Day 3, Day 4 or Day 5, respectively (P<0.05. And, in comparison with the preovulation and postovulation groups, group of surrogate gilts during periovulation displayed a significantly higher overall cloning efficiency (P<0.05. Further investigation of surrogate estrus stage and ovulation status displayed that ovulation status was the real factor underlying estrus stage to determine the overall cloning efficiency. And more, follicle puncture for preovulation, not transfer position shallowed for preovulation or deepened for postovulation, significantly improved the average number of piglets alive and cloning efficiency (P<0.05. In conclusion, our results demonstrated that ovulation status of surrogate gilts was the fundamental factor determining the overall cloning efficiency of excellent pigs, and follicle

  11. Real-time characterization of partially observed epidemics using surrogate models.

    Energy Technology Data Exchange (ETDEWEB)

    Safta, Cosmin; Ray, Jaideep; Lefantzi, Sophia; Crary, David (Applied Research Associates, Arlington, VA); Sargsyan, Khachik; Cheng, Karen (Applied Research Associates, Arlington, VA)

    2011-09-01

    We present a statistical method, predicated on the use of surrogate models, for the 'real-time' characterization of partially observed epidemics. Observations consist of counts of symptomatic patients, diagnosed with the disease, that may be available in the early epoch of an ongoing outbreak. Characterization, in this context, refers to estimation of epidemiological parameters that can be used to provide short-term forecasts of the ongoing epidemic, as well as to provide gross information on the dynamics of the etiologic agent in the affected population e.g., the time-dependent infection rate. The characterization problem is formulated as a Bayesian inverse problem, and epidemiological parameters are estimated as distributions using a Markov chain Monte Carlo (MCMC) method, thus quantifying the uncertainty in the estimates. In some cases, the inverse problem can be computationally expensive, primarily due to the epidemic simulator used inside the inversion algorithm. We present a method, based on replacing the epidemiological model with computationally inexpensive surrogates, that can reduce the computational time to minutes, without a significant loss of accuracy. The surrogates are created by projecting the output of an epidemiological model on a set of polynomial chaos bases; thereafter, computations involving the surrogate model reduce to evaluations of a polynomial. We find that the epidemic characterizations obtained with the surrogate models is very close to that obtained with the original model. We also find that the number of projections required to construct a surrogate model is O(10)-O(10{sup 2}) less than the number of samples required by the MCMC to construct a stationary posterior distribution; thus, depending upon the epidemiological models in question, it may be possible to omit the offline creation and caching of surrogate models, prior to their use in an inverse problem. The technique is demonstrated on synthetic data as well as

  12. Primary Reference Fuels (PRFs) as Surrogates for Low Sensitivity Gasoline Fuels

    KAUST Repository

    Bhavani Shankar, Vijai Shankar

    2016-04-05

    Primary Reference Fuels (PRFs) - binary mixtures of n-heptane and iso-octane based on Research Octane Number (RON) - are popular gasoline surrogates for modeling combustion in spark ignition engines. The use of these two component surrogates to represent real gasoline fuels for simulations of HCCI/PCCI engines needs further consideration, as the mode of combustion is very different in these engines (i.e. the combustion process is mainly controlled by the reactivity of the fuel). This study presents an experimental evaluation of PRF surrogates for four real gasoline fuels termed FACE (Fuels for Advanced Combustion Engines) A, C, I, and J in a motored CFR (Cooperative Fuels Research) engine. This approach enables the surrogate mixtures to be evaluated purely from a chemical kinetic perspective. The gasoline fuels considered in this study have very low sensitivities, S (RON-MON), and also exhibit two-stage ignition behavior. The first stage heat release, which is termed Low Temperature Heat Release (LTHR), controls the combustion phasing in this operating mode. As a result, the performance of the PRF surrogates was evaluated by its ability to mimic the low temperature chemical reactivity of the real gasoline fuels. This was achieved by comparing the LTHR from the engine pressure histories. The PRF surrogates were able to consistently reproduce the amount of LTHR, closely match the phasing of LTHR, and the compression ratio for the start of hot ignition of the real gasoline fuels. This suggests that the octane quality of a surrogate fuel is a good indicator of the fuel’s reactivity across low (LTC), negative temperature coefficient (NTC), and high temperature chemical (HTC) reactivity regimes.

  13. Advance directives and outcomes of surrogate decision making before death.

    Science.gov (United States)

    Silveira, Maria J; Kim, Scott Y H; Langa, Kenneth M

    2010-04-01

    Recent discussions about health care reform have raised questions regarding the value of advance directives. We used data from survey proxies in the Health and Retirement Study involving adults 60 years of age or older who had died between 2000 and 2006 to determine the prevalence of the need for decision making and lost decision-making capacity and to test the association between preferences documented in advance directives and outcomes of surrogate decision making. Of 3746 subjects, 42.5% required decision making, of whom 70.3% lacked decision-making capacity and 67.6% of those subjects, in turn, had advance directives. Subjects who had living wills were more likely to want limited care (92.7%) or comfort care (96.2%) than all care possible (1.9%); 83.2% of subjects who requested limited care and 97.1% of subjects who requested comfort care received care consistent with their preferences. Among the 10 subjects who requested all care possible, only 5 received it; however, subjects who requested all care possible were far more likely to receive aggressive care as compared with those who did not request it (adjusted odds ratio, 22.62; 95% confidence interval [CI], 4.45 to 115.00). Subjects with living wills were less likely to receive all care possible (adjusted odds ratio, 0.33; 95% CI, 0.19 to 0.56) than were subjects without living wills. Subjects who had assigned a durable power of attorney for health care were less likely to die in a hospital (adjusted odds ratio, 0.72; 95% CI, 0.55 to 0.93) or receive all care possible (adjusted odds ratio, 0.54; 95% CI, 0.34 to 0.86) than were subjects who had not assigned a durable power of attorney for health care. Between 2000 and 2006, many elderly Americans needed decision making near the end of life at a time when most lacked the capacity to make decisions. Patients who had prepared advance directives received care that was strongly associated with their preferences. These findings support the continued use of advance

  14. Comparison of false-negative rates and limits of detection following macrofoam-swab sampling of Bacillus anthracis surrogates via Rapid Viability PCR and plate culture.

    Science.gov (United States)

    Hutchison, J R; Piepel, G F; Amidan, B G; Hess, B M; Sydor, M A; Deatherage Kaiser, B L

    2018-05-01

    We evaluated the effects of Bacillus anthracis surrogates, low surface concentrations, surface materials and assay methods on false-negative rate (FNR) and limit of detection (LOD 95 ) for recovering Bacillus spores using a macrofoam-swab sampling procedure. Bacillus anthracis Sterne or Bacillus atrophaeus Nakamura spores were deposited over a range of low target concentrations (2-500 per coupon) onto glass, stainless steel, vinyl tile and plastic. Samples were assayed using a modified Rapid Viability-PCR (mRV-PCR) method and the traditional plate culture method to obtain FNR and LOD 95 results. Mean FNRs tended to be lower for mRV-PCR compared to culturing, and increased as spore concentration decreased for all surface materials. Surface material, but not B. anthracis surrogate, influenced FNRs with the mRV-PCR method. The mRV-PCR LOD 95 was lowest for glass and highest for vinyl tile. LOD 95 values overall were lower for mRV-PCR than for the culture method. This study adds to the limited data on FNR and LOD 95 for mRV-PCR and culturing methods with low concentrations of B. anthracis sampled from various surface materials by the CDC macrofoam-swab method. These are key inputs for planning characterization and clearance studies for low contamination levels of B. anthracis. © 2018 The Society for Applied Microbiology.

  15. Surrogate mothers, surrogate mistresses, and surrogate memories : a comparative study of the re-presentation of the feminine possessed in “The Bear” by William Faulkner and Borderline by Janette Turner Hospital

    OpenAIRE

    Heggelund, Marte

    2008-01-01

    The thesis aims to investigate the feminine surrogates in the worlds of Ike McCaslin (“The Bear”) and Jean-Marc Seymour (Borderline). Thematically speaking, the main problems facing the protagonists of ”The Bear” and Borderline revolve around their constant struggle for self-definition. The lack of strong mother figures in childhood creates obvious and deep problems for both protagonists’ attempts to construct a self, a foundation from which to interpret their surroundings. They hence constru...

  16. Surrogate mothers 10 years on: A longitudinal study of psychological wellbeing and relationships with the parents and child

    OpenAIRE

    Jadva, Vasanti Harish; Imrie, S; Golombok, Susan Esther

    2014-01-01

    Study Question: How do surrogates psychological health and experiences of surrogacy change from one year to ten years following the birth of the surrogacy child? Summary answer: Surrogates’ psychological well-being did not change ten years following the birth, with the majority continuing to report good mental health andall surrogates remained positive about the surrogacy arrangement. What is known already: Studies have found that surrogates may find the weeks following the birth difficu...

  17. Surrogate endpoints for overall survival in digestive oncology trials: which candidates? A questionnaires survey among clinicians and methodologists

    OpenAIRE

    Bonnetain Franck; Bedenne Laurent; Methy Nicolas

    2010-01-01

    Abstract Background Overall survival (OS) is the gold standard for the demonstration of a clinical benefit in cancer trials. Replacement of OS by a surrogate endpoint allows to reduce trial duration. To date, few surrogate endpoints have been validated in digestive oncology. The aim of this study was to draw up an ordered list of potential surrogate endpoints for OS in digestive cancer trials, by way of a survey among clinicians and methodologists. Secondary objective was to obtain their opin...

  18. Failed surrogate conceptions: social and ethical aspects of preconception disruptions during commercial surrogacy in India.

    Science.gov (United States)

    Mitra, Sayani; Schicktanz, Silke

    2016-09-19

    During a commercial surrogacy arrangement, the event of embryo transfer can be seen as the formal starting point of the arrangement. However, it is common for surrogates to undergo a failed attempt at pregnancy conception or missed conception after an embryo transfer. This paper attempts to argue that such failed attempts can be understood as a loss. It aims to reconstruct the experiences of loss and grief of the surrogates and the intended parents as a consequence of their collective failure to conceive a surrogate pregnancy. Drawing on a qualitative study conducted over a period of eight months between 2014 and 2015 at two fertility clinics in Delhi and two in Kolkata, India, this paper examines the experiences of the surrogates and the intended parents when faced with missed conceptions or failed conceptions during a surrogacy arrangement. We argue that while the surrogate grieves the non-arrival of a 'good news' as an uncertain loss, the intended parents experience yet another, failure in addition to the losses they might have incurred during their previous fertility treatments. The body of the surrogate becomes a site of 'a lost opportunity'. The surrogate embodies a loss in her quest to achieve social mobility and the intended parents experience a disembodied pregnancy loss. This very emotional experience stands in stark contrast to the conceptualisation of such failed attempts as non-events within the discourse of the surrogacy industry. The experience of loss of the intended parents is recognised but their grief is given no space. We argue that such ambiguity around the nature of losses resulting out of a missed or failed conception during surrogacy is an outcome of lack of interpersonal relationship between the surrogate and the intended parents. Since commercial surrogacy is a relational process, the only way in which the experiences of losses and failures of the actors at the preconception stage can be better addressed is through developing close

  19. Gallium-cladding compatibility testing plan: Phase 3: Test plan for centrally heated surrogate rodlet test. Revision 2

    International Nuclear Information System (INIS)

    Morris, R.N.; Baldwin, C.A.; Wilson, D.F.

    1998-07-01

    The Fissile Materials Disposition Program (FMDP) is investigating the use of weapons grade plutonium in mixed oxide (MOX) fuel for light-water reactors (LWR). Commercial MOX fuel has been successfully used in overseas reactors for many years; however, weapons derived fuel may differ from the previous commercial fuels because of small amounts of gallium impurities. A concern presently exists that the gallium may migrate out of the fuel, react with and weaken the clad, and thereby promote loss of fuel pin integrity. Phases 1 and 2 of the gallium task are presently underway to investigate the types of reactions that occur between gallium and clad materials. This is a Level-2 document as defined in the Fissile Materials Disposition Program Light-Water Reactor Mixed-Oxide Fuel Irradiation Test Project Plan. This Plan summarizes the projected Phase 3 Gallium-Cladding compatibility heating test and the follow-on post test examination (PTE). This work will be performed using centrally-heated surrogate pellets, to avoid unnecessary complexities and costs associated with working with plutonium and an irradiation environment. Two sets of rodlets containing pellets prepared by two different methods will be heated. Both sets will have an initial bulk gallium content of approximately 10 ppm. The major emphasis of the PTE task will be to examine the material interactions, particularly indications of gallium transport from the pellets to the clad

  20. Patient Preferences and Surrogate Decision Making in Neuroscience Intensive Care Units

    Science.gov (United States)

    Cai, Xuemei; Robinson, Jennifer; Muehlschlegel, Susanne; White, Douglas B.; Holloway, Robert G.; Sheth, Kevin N.; Fraenkel, Liana; Hwang, David Y.

    2016-01-01

    In the neuroscience intensive care unit (NICU), most patients lack the capacity to make their own preferences known. This fact leads to situations where surrogate decision makers must fill the role of the patient in terms of making preference-based treatment decisions, oftentimes in challenging situations where prognosis is uncertain. The neurointensivist has a large responsibility and role to play in this shared decision making process. This review covers how NICU patient preferences are determined through existing advance care documentation or surrogate decision makers and how the optimum roles of the physician and surrogate decision maker are addressed. We outline the process of reaching a shared decision between family and care team and describe a practice for conducting optimum family meetings based on studies of ICU families in crisis. We review challenges in the decision making process between surrogate decision makers and medical teams in neurocritical care settings, as well as methods to ameliorate conflicts. Ultimately, the goal of shared decision making is to increase knowledge amongst surrogates and care providers, decrease decisional conflict, promote realistic expectations and preference-centered treatment strategies, and lift the emotional burden on families of neurocritical care patients. PMID:25990137

  1. Surrogate utility estimation by long-term partners and unfamiliar dyads.

    Science.gov (United States)

    Tunney, Richard J; Ziegler, Fenja V

    2015-01-01

    To what extent are people able to make predictions about other people's preferences and values?We report two experiments that present a novel method assessing some of the basic processes in surrogate decision-making, namely surrogate-utility estimation. In each experiment participants formed dyads who were asked to assign utilities to health related items and commodity items, and to predict their partner's utility judgments for the same items. In experiment one we showed that older adults in long-term relationships were able to accurately predict their partner's wishes. In experiment two we showed that younger adults who were relatively unfamiliar with one another were also able to predict other people's wishes. Crucially we demonstrated that these judgments were accurate even after partialling out each participant's own preferences indicating that in order to make surrogate utility estimations people engage in perspective-taking rather than simple anchoring and adjustment, suggesting that utility estimation is not the cause of inaccuracy in surrogate decision-making. The data and implications are discussed with respect to theories of surrogate decision-making.

  2. Surrogate utility estimation by long-term partners and unfamiliar dyads

    Directory of Open Access Journals (Sweden)

    Richard J Tunney

    2015-03-01

    Full Text Available To what extent are people able to make predictions about other people’s preferences and values? We report two experiments that present a novel method assessing some of the basic processes in surrogate decision-making, namely surrogate-utility estimation. In each experiment participants formed dyads who were asked to assign utilities to health related items and commodity items, and to predict their partner’s utility judgments for the same items. In experiment one we showed that older adults in long-term relationships were able to accurately predict their partner’s wishes. In experiment two we showed that younger adults who were relatively unfamiliar with one another were also able to predict other people’s wishes. Crucially we demonstrated that these judgments were accurate even after partialling out each participant’s own preferences indicating that in order to make surrogate utility estimations people engage in perspective-taking rather than simple anchoring and adjustment, suggesting that utility estimation is not the cause of inaccuracy in surrogate decision-making. The data and implications are discussed with respect to theories of surrogate decision-making.

  3. Gay father surrogacy families: relationships with surrogates and egg donors and parental disclosure of children's origins.

    Science.gov (United States)

    Blake, Lucy; Carone, Nicola; Slutsky, Jenna; Raffanello, Elizabeth; Ehrhardt, Anke A; Golombok, Susan

    2016-11-01

    To study the nature and quality of relationships between gay father families and their surrogates and egg donors and parental disclosure of children's origins. Cross-sectional study. Family homes. Parents in 40 gay father families with 3-9-year-old children born through surrogacy. Administration of a semistructured interview. Relationships between parents, children, surrogates, and egg donors and parental disclosure of children's origins were examined using a semistructured interview. The majority of fathers were content with the level of contact they had with the surrogate, with those who were discontent wanting more contact. Fathers were more likely to maintain relationships with surrogates than egg donors, and almost all families had started the process of talking to their children about their origins, with the level of detail and children's understanding increasing with the age of the child. In gay father surrogacy families with young children, relationships between parents, children, surrogates, and egg donors are generally positive. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Combining endangered plants and animals as surrogates to identify priority conservation areas in Yunnan, China

    Science.gov (United States)

    Yang, Feiling; Hu, Jinming; Wu, Ruidong

    2016-08-01

    Suitable surrogates are critical for identifying optimal priority conservation areas (PCAs) to protect regional biodiversity. This study explored the efficiency of using endangered plants and animals as surrogates for identifying PCAs at the county level in Yunnan, southwest China. We ran the Dobson algorithm under three surrogate scenarios at 75% and 100% conservation levels and identified four types of PCAs. Assessment of the protection efficiencies of the four types of PCAs showed that endangered plants had higher surrogacy values than endangered animals but that the two were not substitutable; coupled endangered plants and animals as surrogates yielded a higher surrogacy value than endangered plants or animals as surrogates; the plant-animal priority areas (PAPAs) was the optimal among the four types of PCAs for conserving both endangered plants and animals in Yunnan. PAPAs could well represent overall species diversity distribution patterns and overlap with critical biogeographical regions in Yunnan. Fourteen priority units in PAPAs should be urgently considered as optimizing Yunnan’s protected area system. The spatial pattern of PAPAs at the 100% conservation level could be conceptualized into three connected conservation belts, providing a valuable reference for optimizing the layout of the in situ protected area system in Yunnan.

  5. Accelerated Monte Carlo system reliability analysis through machine-learning-based surrogate models of network connectivity

    International Nuclear Information System (INIS)

    Stern, R.E.; Song, J.; Work, D.B.

    2017-01-01

    The two-terminal reliability problem in system reliability analysis is known to be computationally intractable for large infrastructure graphs. Monte Carlo techniques can estimate the probability of a disconnection between two points in a network by selecting a representative sample of network component failure realizations and determining the source-terminal connectivity of each realization. To reduce the runtime required for the Monte Carlo approximation, this article proposes an approximate framework in which the connectivity check of each sample is estimated using a machine-learning-based classifier. The framework is implemented using both a support vector machine (SVM) and a logistic regression based surrogate model. Numerical experiments are performed on the California gas distribution network using the epicenter and magnitude of the 1989 Loma Prieta earthquake as well as randomly-generated earthquakes. It is shown that the SVM and logistic regression surrogate models are able to predict network connectivity with accuracies of 99% for both methods, and are 1–2 orders of magnitude faster than using a Monte Carlo method with an exact connectivity check. - Highlights: • Surrogate models of network connectivity are developed by machine-learning algorithms. • Developed surrogate models can reduce the runtime required for Monte Carlo simulations. • Support vector machine and logistic regressions are employed to develop surrogate models. • Numerical example of California gas distribution network demonstrate the proposed approach. • The developed models have accuracies 99%, and are 1–2 orders of magnitude faster than MCS.

  6. Surrogate screening models for the low physical activity criterion of frailty.

    Science.gov (United States)

    Eckel, Sandrah P; Bandeen-Roche, Karen; Chaves, Paulo H M; Fried, Linda P; Louis, Thomas A

    2011-06-01

    Low physical activity, one of five criteria in a validated clinical phenotype of frailty, is assessed by a standardized, semiquantitative questionnaire on up to 20 leisure time activities. Because of the time demanded to collect the interview data, it has been challenging to translate to studies other than the Cardiovascular Health Study (CHS), for which it was developed. Considering subsets of activities, we identified and evaluated streamlined surrogate assessment methods and compared them to one implemented in the Women's Health and Aging Study (WHAS). Using data on men and women ages 65 and older from the CHS, we applied logistic regression models to rank activities by "relative influence" in predicting low physical activity.We considered subsets of the most influential activities as inputs to potential surrogate models (logistic regressions). We evaluated predictive accuracy and predictive validity using the area under receiver operating characteristic curves and assessed criterion validity using proportional hazards models relating frailty status (defined using the surrogate) to mortality. Walking for exercise and moderately strenuous household chores were highly influential for both genders. Women required fewer activities than men for accurate classification. The WHAS model (8 CHS activities) was an effective surrogate, but a surrogate using 6 activities (walking, chores, gardening, general exercise, mowing and golfing) was also highly predictive. We recommend a 6 activity questionnaire to assess physical activity for men and women. If efficiency is essential and the study involves only women, fewer activities can be included.

  7. The effect of framing on surrogate optimism bias: A simulation study.

    Science.gov (United States)

    Patel, Dev; Cohen, Elan D; Barnato, Amber E

    2016-04-01

    To explore the effect of emotion priming and physician communication behaviors on optimism bias. We conducted a 5 × 2 between-subject randomized factorial experiment using a Web-based interactive video designed to simulate a family meeting for a critically ill spouse/parent. Eligibility included age at least 35 years and self-identifying as the surrogate for a spouse/parent. The primary outcome was the surrogate's election of code status. We defined optimism bias as the surrogate's estimate of prognosis with cardiopulmonary resuscitation (CPR) > their recollection of the physician's estimate. Of 373 respondents, 256 (69%) logged in and were randomized and 220 (86%) had nonmissing data for prognosis. Sixty-seven (30%) of 220 overall and 56 of (32%) 173 with an accurate recollection of the physician's estimate had optimism bias. Optimism bias correlated with choosing CPR (P optimism bias. Framing the decision as the patient's vs the surrogate's (25% vs 36%, P = .066) and describing the alternative to CPR as "allow natural death" instead of "do not resuscitate" (25% vs 37%, P = .035) decreased optimism bias. Framing of CPR choice during code status conversations may influence surrogates' optimism bias. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. A rapid situation assessment of the market for surrogate and illegal alcohols in Tallinn, Estonia.

    Science.gov (United States)

    Pärna, Kersti; Lang, Katrin; Raju, Kadi; Väli, Marika; McKee, Martin

    2007-01-01

    To understand the phenomenon of consumption of surrogate and illegal alcohols in Tallinn, capital of Estonia. This study, conducted in Tallinn in May 2006, used rapid situation assessment. Interviews with key informants in relevant settings such as emergency departments of hospitals, accommodation for the homeless, police etc. (n = 22), with alcohol abusers (n = 33), natural observations of surrogate sale and consumption venues (n = 46), and tracking of trade data were carried out. Key informants confirmed that consumption of illegal and surrogate alcohols are widely used by alcohol abusers, a finding confirmed by the alcohol abusers. Availability of surrogates varied by area of the city, mainly sold from street kiosks. Illegally produced spirits were also easily available. Sales of surrogates appear to have increased in recent years. A range of alcohol-containing substances that appear to be easily available at low cost, and that have high concentration of ethanol or contaminants known to be toxic, were identified in Tallinn. Alcohol policies in Estonia should address the consumption and availability of these substances.

  9. Laboratory stabilization/solidification of surrogate and actual mixed-waste sludge in glass and grout

    International Nuclear Information System (INIS)

    Spence, R.D.; Gilliam, T.M.; Mattus, C.H.; Mattus, A.J.

    1998-01-01

    Grouting and vitrification are currently the most likely stabilization/solidification technologies for mixed wastes. Grouting has been used to stabilize and solidify hazardous and low-level waste for decades. Vitrification has long been developed as a high-level-waste alternative and has been under development recently as an alternative treatment technology for low-level mixed waste. Laboratory testing has been performed to develop grout and vitrification formulas for mixed-waste sludges currently stored in underground tanks at Oak Ridge National Laboratory (ORNL) and to compare these waste forms. Envelopes, or operating windows, for both grout and soda-lime-silica glass formulations for a surrogate sludge were developed. One formulation within each envelope was selected for testing the sensitivity of performance to variations (±10 wt%) in the waste form composition and variations in the surrogate sludge composition over the range previously characterized in the sludges. In addition, one sludge sample of an actual mixed-waste tank was obtained, a surrogate was developed for this sludge sample, and grout and glass samples were prepared and tested in the laboratory using both surrogate and the actual sludge. The sensitivity testing of a surrogate tank sludge in selected glass and grout formulations is discussed in this paper, along with the hot-cell testing of an actual tank sludge sample

  10. Primary Reference Fuels (PRFs) as Surrogates for Low Sensitivity Gasoline Fuels

    KAUST Repository

    Bhavani Shankar, Vijai Shankar; Sajid, Muhammad Bilal; Al-Qurashi, Khalid; Atef, Nour; Al Khesho, Issam; Ahmed, Ahfaz; Chung, Suk-Ho; Roberts, William L.; Morganti, Kai; Sarathy, Mani

    2016-01-01

    This study presents an experimental evaluation of PRF surrogates for four real gasoline fuels termed FACE (Fuels for Advanced Combustion Engines) A, C, I, and J in a motored CFR (Cooperative Fuels Research) engine. This approach enables the surrogate mixtures to be evaluated purely from a chemical kinetic perspective. The gasoline fuels considered in this study have very low sensitivities, S (RON-MON), and also exhibit two-stage ignition behavior. The first stage heat release, which is termed Low Temperature Heat Release (LTHR), controls the combustion phasing in this operating mode. As a result, the performance of the PRF surrogates was evaluated by its ability to mimic the low temperature chemical reactivity of the real gasoline fuels. This was achieved by comparing the LTHR from the engine pressure histories. The PRF surrogates were able to consistently reproduce the amount of LTHR, closely match the phasing of LTHR, and the compression ratio for the start of hot ignition of the real gasoline fuels. This suggests that the octane quality of a surrogate fuel is a good indicator of the fuel’s reactivity across low (LTC), negative temperature coefficient (NTC), and high temperature chemical (HTC) reactivity regimes.

  11. Nuclear Fuels & Materials Spotlight Volume 4

    Energy Technology Data Exchange (ETDEWEB)

    I. J. van Rooyen,; T. M. Lillo; Y. Q. WU; P.A. Demkowicz; L. Scott; D.M. Scates; E. L. Reber; J. H. Jackson; J. A. Smith; D.L. Cottle; B.H. Rabin; M.R. Tonks; S.B. Biner; Y. Zhang; R.L. Williamson; S.R. Novascone; B.W. Spencer; J.D. Hales; D.R. Gaston; C.J. Permann; D. Anders; S.L. Hayes; P.C. Millett; D. Andersson; C. Stanek; R. Ali; S.L. Garrett; J.E. Daw; J.L. Rempe; J. Palmer; B. Tittmann; B. Reinhardt; G. Kohse; P. Ramuhali; H.T. Chien; T. Unruh; B.M. Chase; D.W. Nigg; G. Imel; J. T. Harris

    2014-04-01

    As the nation's nuclear energy laboratory, Idaho National Laboratory brings together talented people and specialized nuclear research capability to accomplish our mission. This edition of the Nuclear Fuels and Materials Division Spotlight provides an overview of some of our recent accomplishments in research and capability development. These accomplishments include: • The first identification of silver and palladium migrating through the SiC layer in TRISO fuel • A description of irradiation assisted stress corrosion testing capabilities that support commercial light water reactor life extension • Results of high-temperature safety testing on coated particle fuels irradiated in the ATR • New methods for testing the integrity of irradiated plate-type reactor fuel • Description of a 'Smart Fuel' concept that wirelessly provides real time information about changes in nuclear fuel properties and operating conditions • Development and testing of ultrasonic transducers and real-time flux sensors for use inside reactor cores, and • An example of a capsule irradiation test. Throughout Spotlight, you'll find examples of productive partnerships with academia, industry, and government agencies that deliver high-impact outcomes. The work conducted at Idaho National Laboratory helps to spur innovation in nuclear energy applications that drive economic growth and energy security. We appreciate your interest in our work here at INL, and hope that you find this issue informative.

  12. The long-term experiences of surrogates: relationships and contact with surrogacy families in genetic and gestational surrogacy arrangements.

    Science.gov (United States)

    Imrie, Susan; Jadva, Vasanti

    2014-10-01

    This study examined the contact arrangements and relationships between surrogates and surrogacy families and whether these outcomes differed according to the type of surrogacy undertaken. Surrogates' motivations for carrying out multiple surrogacy arrangements were also examined, and surrogates' psychological health was assessed. Semi-structured interviews were administered to 34 women who had given birth to a child conceived through surrogacy approximately 7 years prior to interview. Some surrogates had carried out multiple surrogacy arrangements, and data were collected on the frequency, type of contact, and surrogate's feelings about the level of contact in each surrogacy arrangement, the surrogate's relationship with each child and parent, and her experience of, and motivation for, each surrogacy. Questionnaire measures of psychological health were administered. Surrogates had completed a total of 102 surrogacy arrangements and remained in contact with the majority of families, and reported positive relationships in most cases. Surrogates were happy with their level of contact in the majority of arrangements and most were viewed as positive experiences. Few differences were found according to surrogacy type. The primary motivation given for multiple surrogacy arrangements was to help couples have a sibling for an existing child. Most surrogates showed no psychological health problems at the time of data collection. Copyright © 2014 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  13. Time-varying surrogate data to assess nonlinearity in nonstationary time series: application to heart rate variability.

    Science.gov (United States)

    Faes, Luca; Zhao, He; Chon, Ki H; Nollo, Giandomenico

    2009-03-01

    We propose a method to extend to time-varying (TV) systems the procedure for generating typical surrogate time series, in order to test the presence of nonlinear dynamics in potentially nonstationary signals. The method is based on fitting a TV autoregressive (AR) model to the original series and then regressing the model coefficients with random replacements of the model residuals to generate TV AR surrogate series. The proposed surrogate series were used in combination with a TV sample entropy (SE) discriminating statistic to assess nonlinearity in both simulated and experimental time series, in comparison with traditional time-invariant (TIV) surrogates combined with the TIV SE discriminating statistic. Analysis of simulated time series showed that using TIV surrogates, linear nonstationary time series may be erroneously regarded as nonlinear and weak TV nonlinearities may remain unrevealed, while the use of TV AR surrogates markedly increases the probability of a correct interpretation. Application to short (500 beats) heart rate variability (HRV) time series recorded at rest (R), after head-up tilt (T), and during paced breathing (PB) showed: 1) modifications of the SE statistic that were well interpretable with the known cardiovascular physiology; 2) significant contribution of nonlinear dynamics to HRV in all conditions, with significant increase during PB at 0.2 Hz respiration rate; and 3) a disagreement between TV AR surrogates and TIV surrogates in about a quarter of the series, suggesting that nonstationarity may affect HRV recordings and bias the outcome of the traditional surrogate-based nonlinearity test.

  14. Definitions and validation criteria for biomarkers and surrogate endpoints: development and testing of a quantitative hierarchical levels of evidence schema.

    Science.gov (United States)

    Lassere, Marissa N; Johnson, Kent R; Boers, Maarten; Tugwell, Peter; Brooks, Peter; Simon, Lee; Strand, Vibeke; Conaghan, Philip G; Ostergaard, Mikkel; Maksymowych, Walter P; Landewe, Robert; Bresnihan, Barry; Tak, Paul-Peter; Wakefield, Richard; Mease, Philip; Bingham, Clifton O; Hughes, Michael; Altman, Doug; Buyse, Marc; Galbraith, Sally; Wells, George

    2007-03-01

    There are clear advantages to using biomarkers and surrogate endpoints, but concerns about clinical and statistical validity and systematic methods to evaluate these aspects hinder their efficient application. Our objective was to review the literature on biomarkers and surrogates to develop a hierarchical schema that systematically evaluates and ranks the surrogacy status of biomarkers and surrogates; and to obtain feedback from stakeholders. After a systematic search of Medline and Embase on biomarkers, surrogate (outcomes, endpoints, markers, indicators), intermediate endpoints, and leading indicators, a quantitative surrogate validation schema was developed and subsequently evaluated at a stakeholder workshop. The search identified several classification schema and definitions. Components of these were incorporated into a new quantitative surrogate validation level of evidence schema that evaluates biomarkers along 4 domains: Target, Study Design, Statistical Strength, and Penalties. Scores derived from 3 domains the Target that the marker is being substituted for, the Design of the (best) evidence, and the Statistical strength are additive. Penalties are then applied if there is serious counterevidence. A total score (0 to 15) determines the level of evidence, with Level 1 the strongest and Level 5 the weakest. It was proposed that the term "surrogate" be restricted to markers attaining Levels 1 or 2 only. Most stakeholders agreed that this operationalization of the National Institutes of Health definitions of biomarker, surrogate endpoint, and clinical endpoint was useful. Further development and application of this schema provides incentives and guidance for effective biomarker and surrogate endpoint research, and more efficient drug discovery, development, and approval.

  15. Fungal-Transformation of Surrogate Sulphides and Carbonaceous ...

    African Journals Online (AJOL)

    user

    boundaries or fractures of sulphides, typically pyrite and arsenopyrite. ... phur in the residual sulphidic materials, and by determining the preg-robbing effect of the treated CM. Within 21 ..... The forms of sulphur in sulphur compounds are gen-.

  16. A Radiation-Induced Hippocampal Vascular Injury Surrogate Marker Predicts Late Neurocognitive Dysfunction

    Energy Technology Data Exchange (ETDEWEB)

    Farjam, Reza [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Pramanik, Priyanka; Aryal, Madhava P. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Srinivasan, Ashok [Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Chapman, Christopher H. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Tsien, Christina I. [Department of Radiation Oncology, Washington University in St. Louis, St. Louis, Missouri (United States); Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cao, Yue, E-mail: yuecao@umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan (United States)

    2015-11-15

    Purpose: We aimed to develop a hippocampal vascular injury surrogate marker for early prediction of late neurocognitive dysfunction in patients receiving brain radiation therapy (RT). Methods and Materials: Twenty-seven patients (17 males and 10 females, 31-80 years of age) were enrolled in an institutional review board-approved prospective longitudinal study. Patients received diagnoses of low-grade glioma or benign tumor and were treated by (3D) conformal or intensity-modulated RT with a median dose of 54 Gy (50.4-59.4 Gy in 1.8-Gy fractions). Six dynamic-contrast enhanced MRI scans were performed from pre-RT to 18-month post-RT, and quantified for vascular parameters related to blood-brain barrier permeability, K{sup trans}, and the fraction of blood plasma volume, V{sub p}. The temporal changes in the means of hippocampal transfer constant K{sup trans} and V{sub p} after starting RT were modeled by integrating the dose effects with age, sex, hippocampal laterality, and presence of tumor or edema near a hippocampus. Finally, the early vascular dose response in hippocampi was correlated with neurocognitive dysfunction at 6 and 18 months post-RT. Results: The mean K{sup trans} Increased significantly from pre-RT to 1-month post-RT (P<.0004), which significantly depended on sex (P<.0007) and age (P<.00004), with the dose response more pronounced in older females. Also, the vascular dose response in the left hippocampus of females correlated significantly with changes in memory function at 6 (r=−0.95, P<.0006) and 18-months (r=−0.88, P<.02) post-RT. Conclusions: The early hippocampal vascular dose response could be a predictor of late neurocognitive dysfunction. A personalized hippocampus sparing strategy may be considered in the future.

  17. Potassium ferrate [Fe(VI] does not mediate self-sterilization of a surrogate mars soil

    Directory of Open Access Journals (Sweden)

    Paszczynski Andrzej

    2003-03-01

    Full Text Available Abstract Background Martian soil is thought to be enriched with strong oxidants such as peroxides and/or iron in high oxidation states that might destroy biological materials. There is also a high flux of ultraviolet radiation at the surface of Mars. Thus, Mars may be inhospitable to life as we know it on Earth. We examined the hypothesis that if the soil of Mars contains ferrates [Fe(VI], the strongest of the proposed oxidizing species, and also is exposed to high fluxes of UV radiation, it will be self-sterilizing. Results Under ambient conditions (25°C, oxygen and water present K2FeO4 mixed into sand mineralized some reactive organic molecules to CO2, while less reactive compounds were not degraded. Dried endospores of Bacillus subtilis incubated in a Mars surrogate soil comprised of dry silica sand containing 20% by weight K2FeO4 and under conditions similar to those now on Mars (extreme desiccation, cold, and a CO2-dominated atmosphere were resistant to killing by the ferrate-enriched sand. Similar results were observed with permanganate. Spores in oxidant-enriched sand exposed to high fluxes of UV light were protected from the sporocidal activity of the radiation below about 5 mm depths. Conclusion Based on our data and previously published descriptions of ancient but dormant life forms on Earth, we suggest that if entities resembling bacterial endospores were produced at some point by life forms on Mars, they might still be present and viable, given appropriate germination conditions. Endospores delivered to Mars on spacecraft would possibly survive and potentially compromise life detection experiments.

  18. A Radiation-Induced Hippocampal Vascular Injury Surrogate Marker Predicts Late Neurocognitive Dysfunction

    International Nuclear Information System (INIS)

    Farjam, Reza; Pramanik, Priyanka; Aryal, Madhava P.; Srinivasan, Ashok; Chapman, Christopher H.; Tsien, Christina I.; Lawrence, Theodore S.; Cao, Yue

    2015-01-01

    Purpose: We aimed to develop a hippocampal vascular injury surrogate marker for early prediction of late neurocognitive dysfunction in patients receiving brain radiation therapy (RT). Methods and Materials: Twenty-seven patients (17 males and 10 females, 31-80 years of age) were enrolled in an institutional review board-approved prospective longitudinal study. Patients received diagnoses of low-grade glioma or benign tumor and were treated by (3D) conformal or intensity-modulated RT with a median dose of 54 Gy (50.4-59.4 Gy in 1.8-Gy fractions). Six dynamic-contrast enhanced MRI scans were performed from pre-RT to 18-month post-RT, and quantified for vascular parameters related to blood-brain barrier permeability, K"t"r"a"n"s, and the fraction of blood plasma volume, V_p. The temporal changes in the means of hippocampal transfer constant K"t"r"a"n"s and V_p after starting RT were modeled by integrating the dose effects with age, sex, hippocampal laterality, and presence of tumor or edema near a hippocampus. Finally, the early vascular dose response in hippocampi was correlated with neurocognitive dysfunction at 6 and 18 months post-RT. Results: The mean K"t"r"a"n"s Increased significantly from pre-RT to 1-month post-RT (P<.0004), which significantly depended on sex (P<.0007) and age (P<.00004), with the dose response more pronounced in older females. Also, the vascular dose response in the left hippocampus of females correlated significantly with changes in memory function at 6 (r=−0.95, P<.0006) and 18-months (r=−0.88, P<.02) post-RT. Conclusions: The early hippocampal vascular dose response could be a predictor of late neurocognitive dysfunction. A personalized hippocampus sparing strategy may be considered in the future.

  19. Gravidez de substituição Surrogate pregnancy

    Directory of Open Access Journals (Sweden)

    Otávio Marambaia dos Santos

    2010-12-01

    Full Text Available A tecnologia e a ciência médica aplicada tem criado as condições para tornar possível que casais inférteis, antes condenados a não ter filhos pelos meios biológicos usuais, hoje alcancem este objetivo. Os formidáveis progressos científicos com a reprodução medicamente assistida, num primeiro momento, permitiram superar a infertilidade causada por ovulação insuficiente ou um número pequeno de espermatozóides com a fertilização in vitro. Num segundo momento, depois de gerado o embrião, implanta-lo no útero materno e, finalmente, conseguir a sua implantação em outro útero que não o da dona do embrião gerado em laboratório. Neste estágio - a gravidez de substituição - tem gerado inúmeros questionamentos de ordem ética e religiosa e jurídica. Se de um lado a lei já tem uma visão relativamente pacificada - dentro da ótica da estrutura familiar vigente - e os fóruns éticos já tenham definido deontologicamente os passos deste processo, o campo religioso continua postando-se de maneira contrária e com uma abertura muito estreita para discussões sobre o tema. No maior país católico do mundo, no entanto, muitos casais - mesmo sabendo estar contrariando normas explicitadas por documentos eclesiásticos - têm buscado, cada vez mais, este recurso que a ciência lhes põe a disposição.Applied medical science and technology have now created the conditions where it is possible for infertile couples, who would previously have been condemned not to have children by the usual biological means, to achieve this objective. First, stunning scientific advances in medically assisted reproduction have made it possible to overcome infertility arising from insufficient ovulation or low sperm-count by way of in vitro fertilization. Secondly, the embryo thus produced can now be implanted in another woman´s uterus. This surrogate pregnancy has given rise to a number of ethical, religious and legal questions. On the one hand, the

  20. Surrogate fuel formulation for light naphtha combustion in advanced combustion engines

    KAUST Repository

    Ahmed, Ahfaz

    2015-03-30

    Crude oil once recovered is further separated in to several distinct fractions to produce a range of energy and chemical products. One of the less processed fractions is light naphtha (LN), hence they are more economical to produce than their gasoline and diesel counterparts. Recent efforts have demonstrated usage of LN as transportation fuel for internal combustion engines with slight modifications. In this study, a multicomponent surrogate fuel has been developed for light naphtha fuel using a multi-variable nonlinear constrained optimization scheme. The surrogate, consisting of palette species n-pentane, 2-methylhexane, 2-methylbutane, n-heptane and toluene, was validated against the LN using ignition quality tester following ASTM D6890 methodology. Comparison of LN and the surrogate fuel demonstrated satisfactory agreement.

  1. Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Mahir S. [DCTA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, C. P. 72012, Sao Paulo, SP (Brazil); Universidade de Sao Paulo, Instituto de Fisica, C. P. 66318, Sao Paulo, SP (Brazil)

    2017-05-15

    In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB) Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d, p) reaction is predominantly a compound-nucleus one, the Trojan Horse Method assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how these seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory. (orig.)

  2. Neutron-induced capture cross sections via the surrogate reaction method

    International Nuclear Information System (INIS)

    Boutoux, G.; Jurado, B.; Aiche, M.; Barreau, G.; Capellan, N.; Companis, I.; Czajkowski, S.; Dassie, D.; Haas, B.; Mathieu, L.; Meot, V.; Bail, A.; Bauge, E.; Daugas, J. M.; Faul, T.; Gaudefroy, L.; Morel, P.; Pillet, N.; Roig, O.; Romain, P.; Taieb, J.; Theroine, C.; Burke, J.T.; Companis, I.; Derkx, X.; Gunsing, F.; Matea, I.; Tassan-Got, L.; Porquet, M.G.; Serot, O.

    2011-01-01

    The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This technique enables neutron-induced cross sections to be extracted for nuclear reactions on short-lived unstable nuclei that otherwise can not be measured. This technique has been successfully applied to determine the neutron-induced fission cross sections of several short-lived nuclei. In this work, we investigate whether this powerful technique can also be used to determine of neutron-induced capture cross sections. For this purpose we use the surrogate reaction 174 Yb( 3 He, pγ) 176 Lu to infer the well known 175 Lu(n, γ) cross section and compare the results with the directly measured neutron-induced data. This surrogate experiment has been performed in March 2010. The experimental technique used and the first preliminary results will be presented. (authors)

  3. Reduced Gasoline Surrogate (Toluene/n-Heptane/iso-Octane) Chemical Kinetic Model for Compression Ignition Simulations

    KAUST Repository

    Sarathy, Mani

    2018-04-03

    Toluene primary reference fuel (TPRF) (mixture of toluene, iso-octane and heptane) is a suitable surrogate to represent a wide spectrum of real fuels with varying octane sensitivity. Investigating different surrogates in engine simulations is a prerequisite to identify the best matching mixture. However, running 3D engine simulations using detailed models is currently impossible and reduction of detailed models is essential. This work presents an AramcoMech reduced kinetic model developed at King Abdullah University of Science and Technology (KAUST) for simulating complex TPRF surrogate blends. A semi-decoupling approach was used together with species and reaction lumping to obtain a reduced kinetic model. The model was widely validated against experimental data including shock tube ignition delay times and premixed laminar flame speeds. Finally, the model was utilized to simulate the combustion of a low reactivity gasoline fuel under partially premixed combustion conditions.

  4. Validating (d,pγ) as a surrogate for neutron capture

    International Nuclear Information System (INIS)

    Ratkiewicz, A.; Cizewski, J. A.; Pain, S. D.; Adekola, A. S.; Burke, J. T.; Casperson, R. J.; Fotiadis, Nikolaos; McCleskey, M.; Burcher, S.; Shand, C. M; Austin, R. A. E.; Baugher, T.; Carpenter, M. P.; Devlin, Matthew James; Escher, J. E.; Hardy, S.; Hatarik, R.; Howard, M. E.; Hughes, R. O.; Jones, K. L.; Kozub, R. L.; Lister, C. J.; Manning, B.; O'Donnell, John M.; Peters, W. A.; Ross, T. J.; Scielzo, N. D.; Seweryniak, D.; Zhu, S.

    2015-01-01

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate for (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions.

  5. Long-term follow-up after cervical cancer treatment and subsequent successful surrogate pregnancy.

    Science.gov (United States)

    Agorastos, T; Zafrakas, M; Mastrominas, M

    2009-08-01

    Preservation of fertility is a major concern for premenopausal women after diagnosis of cervical cancer. Successful surrogate pregnancy after treatment for cervical cancer has very rarely been reported. In the present report, a case of successful surrogate pregnancy after radical hysterectomy, lymphadenectomy and ovarian transposition for cervical cancer, followed by radiation therapy, is presented. After stimulation of the transposed ovaries using the short gonadotrophin-releasing hormone (GnRH) analogue protocol, four oocytes were retrieved transabdominally from the genetic mother. IVF followed and two embryos were transferred to the surrogate mother, leading to an uneventful singleton pregnancy, and ultimately normal vaginal delivery of a healthy female infant at term. The unique aspect in this case is the long-lasting favourable outcome for both genetic mother and child, observed during 8.5 years of follow-up, the longest follow-up period reported to date in such cases.

  6. The ethics of commercial surrogate mothering: a response to Casey Humbyrd.

    Science.gov (United States)

    Omonzejele, Peter F

    2011-01-01

    This article critically examines the argument advanced by Casey Humbyrd in support of international commercial surrogate mothering. It finds her arguments unconvincing especially at the point of implementation. This is because the author was unable to demonstrate how regulation and her notion offair compensation would not lead to undue inducement and exploitation in resource-poor settings where urgent needs often exist. In fact, the argument advanced in this article is that commercial surrogate mothering cannot but be exploitative in so far as urgent and compelling needs exist. To logically drive home this point, the elements of exploitation were discussed in order to show that regulation and fair compensation cannot prevent exploitative transaction in commercial surrogate mothering arrangements. This may happen in the same way as regulation and compensation framework have not been successful in preventing the allegations of exploitation in the research context especially where studies are conducted in resource-poor countries.

  7. Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

    International Nuclear Information System (INIS)

    Hussein, Mahir S.

    2017-01-01

    In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB) Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d, p) reaction is predominantly a compound-nucleus one, the Trojan Horse Method assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how these seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory. (orig.)

  8. Adaptive surrogate modeling for response surface approximations with application to bayesian inference

    KAUST Repository

    Prudhomme, Serge; Bryant, Corey M.

    2015-01-01

    Parameter estimation for complex models using Bayesian inference is usually a very costly process as it requires a large number of solves of the forward problem. We show here how the construction of adaptive surrogate models using a posteriori error estimates for quantities of interest can significantly reduce the computational cost in problems of statistical inference. As surrogate models provide only approximations of the true solutions of the forward problem, it is nevertheless necessary to control these errors in order to construct an accurate reduced model with respect to the observables utilized in the identification of the model parameters. Effectiveness of the proposed approach is demonstrated on a numerical example dealing with the Spalart–Allmaras model for the simulation of turbulent channel flows. In particular, we illustrate how Bayesian model selection using the adapted surrogate model in place of solving the coupled nonlinear equations leads to the same quality of results while requiring fewer nonlinear PDE solves.

  9. Validating (d,p gamma) as a Surrogate for Neutron Capture

    Energy Technology Data Exchange (ETDEWEB)

    Ratkiewicz, A. [Rutgers University; Cizewski, J. A. [Rutgers University; Pain, S. [Oak Ridge National Laboratory (ORNL); Adekola, A. S. [Rutgers University; Burke, J. T. [Lawrence Livermore National Laboratory (LLNL); Casperson, R.J. [Lawrence Livermore National Laboratory (LLNL); Fotiades, N. [Los Alamos National Laboratory (LANL); McCleskey, M. [Texas A& M University; Burcher, S. [Rutgers University; Shand, C. M. [Rutgers Univ./Univ. of Surrey, UK; Austin, R. A. E. [Saint Mary’s University, Halifa, Canada; Baugher, T. [Rutgers University; Carpenter, M. P. [Argonne National Laboratory (ANL); Devlin, M. [Los Alamos National Laboratory (LANL); Escher, J. E. [Lawrence Livermore National Laboratory (LLNL); Hardy, S. [Rutgers Univ./Univ. of Surrey, UK; Hatarik, R. [Lawrence Livermore National Laboratory (LLNL); Howard, M. [Rutgers University; Hughes, R. [University of Richmond, VA; Jones, K. L. [University of Tennessee, Knoxville (UTK); Kozub, R. L. [Tennessee Technological University (TTU); Lister, C. J. [University of Massachusetts, Lowell; Manning, B. [Rutgers University; O' Donnell, J. M. [Los Alamos National Laboratory (LANL); Peters, W. A. [Oak Ridge Associated Universities (ORAU); Ross, T.J. [University of Richmond, VA; Scielzo, N.D. [Lawrence Livermore National Laboratory (LLNL); Seweryniak, D. [Argonne National Laboratory (ANL); Zhu, S. [Argonne National Laboratory (ANL)

    2015-01-01

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the rprocess may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,py) reaction at low energies was identified as a promising surrogate for the (n,y) reaction, as both reactions share many characteristics. We report on a program to validate (d,py) as a surrogate for (n,y) using 95Mo as a target. The experimental campaign includes direct measurements of the y-ray intensities from the decay of excited states populated in the 95Mo(n,y) and 95Mo(d,py) reactions.

  10. Reduced Gasoline Surrogate (Toluene/n-Heptane/iso-Octane) Chemical Kinetic Model for Compression Ignition Simulations

    KAUST Repository

    Sarathy, Mani; Atef, Nour; Alfazazi, Adamu; Badra, Jihad; Zhang, Yu; Tzanetakis, Tom; Pei, Yuanjiang

    2018-01-01

    Toluene primary reference fuel (TPRF) (mixture of toluene, iso-octane and heptane) is a suitable surrogate to represent a wide spectrum of real fuels with varying octane sensitivity. Investigating different surrogates in engine simulations is a prerequisite to identify the best matching mixture. However, running 3D engine simulations using detailed models is currently impossible and reduction of detailed models is essential. This work presents an AramcoMech reduced kinetic model developed at King Abdullah University of Science and Technology (KAUST) for simulating complex TPRF surrogate blends. A semi-decoupling approach was used together with species and reaction lumping to obtain a reduced kinetic model. The model was widely validated against experimental data including shock tube ignition delay times and premixed laminar flame speeds. Finally, the model was utilized to simulate the combustion of a low reactivity gasoline fuel under partially premixed combustion conditions.

  11. Neutron-induced cross sections of actinides via the surrogate-reaction method

    Directory of Open Access Journals (Sweden)

    Ducasse Q.

    2013-12-01

    Full Text Available The surrogate-reaction method is an indirect way of determining cross sections for reactions that proceed through a compound nucleus. This technique may enable neutron-induced cross sections to be extracted for short-lived nuclei that otherwise cannot be measured. However, the validity of the surrogate method has to be investigated. In particular, the absence of a compound nucleus formation and the Jπ dependence of the decay probabilities may question the method. In this work we study the reactions 238U(d,p239U, 238U(3He,t238Np, 238U(3He,4He237U as surrogates for neutron-induced reactions on 238U, 237Np and 236U, respectively, for which good quality data exist. The experimental set-up enabled the measurement of fission and gamma-decay probabilities. The first results are hereby presented.

  12. Adaptive surrogate modeling for response surface approximations with application to bayesian inference

    KAUST Repository

    Prudhomme, Serge

    2015-09-17

    Parameter estimation for complex models using Bayesian inference is usually a very costly process as it requires a large number of solves of the forward problem. We show here how the construction of adaptive surrogate models using a posteriori error estimates for quantities of interest can significantly reduce the computational cost in problems of statistical inference. As surrogate models provide only approximations of the true solutions of the forward problem, it is nevertheless necessary to control these errors in order to construct an accurate reduced model with respect to the observables utilized in the identification of the model parameters. Effectiveness of the proposed approach is demonstrated on a numerical example dealing with the Spalart–Allmaras model for the simulation of turbulent channel flows. In particular, we illustrate how Bayesian model selection using the adapted surrogate model in place of solving the coupled nonlinear equations leads to the same quality of results while requiring fewer nonlinear PDE solves.

  13. Fog Density Estimation and Image Defogging Based on Surrogate Modeling for Optical Depth.

    Science.gov (United States)

    Jiang, Yutong; Sun, Changming; Zhao, Yu; Yang, Li

    2017-05-03

    In order to estimate fog density correctly and to remove fog from foggy images appropriately, a surrogate model for optical depth is presented in this paper. We comprehensively investigate various fog-relevant features and propose a novel feature based on the hue, saturation, and value color space which correlate well with the perception of fog density. We use a surrogate-based method to learn a refined polynomial regression model for optical depth with informative fog-relevant features such as dark-channel, saturation-value, and chroma which are selected on the basis of sensitivity analysis. Based on the obtained accurate surrogate model for optical depth, an effective method for fog density estimation and image defogging is proposed. The effectiveness of our proposed method is verified quantitatively and qualitatively by the experimental results on both synthetic and real-world foggy images.

  14. Methodology and application of surrogate plant PRA analysis to the Rancho Seco Power Plant: Final report

    International Nuclear Information System (INIS)

    Gore, B.F.; Huenefeld, J.C.

    1987-07-01

    This report presents the development and the first application of generic probabilistic risk assessment (PRA) information for identifying systems and components important to public risk at nuclear power plants lacking plant-specific PRAs. A methodology is presented for using the results of PRAs for similar (surrogate) plants, along with plant-specific information about the plant of interest and the surrogate plants, to infer important failure modes for systems of the plant of interest. This methodology, and the rationale on which it is based, is presented in the context of its application to the Rancho Seco plant. The Rancho Seco plant has been analyzed using PRA information from two surrogate plants. This analysis has been used to guide development of considerable plant-specific information about Rancho Seco systems and components important to minimizing public risk, which is also presented herein

  15. Application of proximal surrogate indicators for safety evaluation: A review of recent developments and research needs

    Directory of Open Access Journals (Sweden)

    S.M. Sohel Mahmud

    2017-12-01

    Full Text Available Although there have been a number of recent reviews on the use of traffic conflict techniques (TCTs, none have focused on the use of proximal surrogate indicators. This paper comprehensively reviews the development and application of proximal surrogate safety indicators to address this gap. There is a particular focus on more recent advancements in the application of such indicators. For each of the main indicators reviewed, the paper provides a synthesis of the main guiding principles, as well as the most prominent features, including critical or threshold values used in the past. In addition, the main advantages and disadvantages of the reviewed indicators are highlighted. Finally, a number of research gaps are identified together with recommendations for potentially useful avenues of future research. Keywords: Safety evaluation, Traffic conflict, Surrogate, Proximal, Indicators

  16. Higher taxa as surrogates of species richness of spiders in insect-resistant transgenic rice

    Institute of Scientific and Technical Information of China (English)

    Sheng Lin; Min-Sheng You; Liette Vasseur; Guang Yang; Feng-Jing Liu; Feng Guo

    2012-01-01

    Biodiversity assessments can often be time- and resource-consuming.Several alternative approaches have been proposed to reduce sampling efforts,including indicator taxa and surrogates.In this study,we examine the reliability of higher taxon surrogates to predict species richness in two experimental rice fields of Fujian Province,southeastern China during 2005 and 2009.Spider samples in transgenic and nontransgenic plots were collected using a suction sampler.Both the genus and family surrogates had significant and positive linear relationships with species richness in the transgenic and nontransgenic rice fields.The rice varieties did not significantly influence the linear relationships.Our findings suggest that higher-taxon surrogacy could be a useful alternative to complete species inventory for risk assessments of transgenic rice.

  17. Evaluation and Development of Chemical Kinetic Mechanism Reduction Scheme for Biodiesel and Diesel Fuel Surrogates

    DEFF Research Database (Denmark)

    Poon, Hiew Mun; Ng, Hoon Kiat; Gan, Suyin

    2013-01-01

    The aim of this study is to evaluate the existing chemical kinetic mechanism reduction techniques. From here, an appropriate reduction scheme was developed to create compact yet comprehensive surrogate models for both diesel and biodiesel fuels for diesel engine applications. The reduction...... techniques applied here were Directed Relation Graph (DRG), DRG with Error Propagation, DRG-aided Sensitivity Analysis, and DRG with Error Propagation and Sensitivity Analysis. Nonetheless, the reduced mechanisms generated via these techniques were not sufficiently small for application in multi......-dimensional computational fluid dynamics (CFD) study. A new reduction scheme was therefore formulated. A 68-species mechanism for biodiesel surrogate and a 49-species mechanism for diesel surrogate were successfully derived from the respective detailed mechanisms. An overall 97% reduction in species number...

  18. Neutron-induced cross sections of actinides via the surrogate-reaction method

    Directory of Open Access Journals (Sweden)

    Tveten G. M.

    2013-03-01

    Full Text Available The surrogate-reaction method is an indirect way of determining cross sections for reactions that proceed through a compound nucleus. This technique may enable neutron-induced cross sections to be extracted for short-lived nuclei that otherwise cannot be measured. However, the validity of the surrogate method for extracting capture cross sections has to be investigated. In this work we study the reactions 238U(d,p239U, 238U(3He,t238Np, 238U(3He,4He237U as surrogates for neutroninduced reactions on 238U, 237Np and 236U, respectively, for which good quality data exist. The experimental set-up enabled the measurement of fission and gamma-decay probabilities. First results are presented and discussed.

  19. An empirical assessment and comparison of species-based and habitat-based surrogates: a case study of forest vertebrates and large old trees.

    Science.gov (United States)

    Lindenmayer, David B; Barton, Philip S; Lane, Peter W; Westgate, Martin J; McBurney, Lachlan; Blair, David; Gibbons, Philip; Likens, Gene E

    2014-01-01

    A holy grail of conservation is to find simple but reliable measures of environmental change to guide management. For example, particular species or particular habitat attributes are often used as proxies for the abundance or diversity of a subset of other taxa. However, the efficacy of such kinds of species-based surrogates and habitat-based surrogates is rarely assessed, nor are different kinds of surrogates compared in terms of their relative effectiveness. We use 30-year datasets on arboreal marsupials and vegetation structure to quantify the effectiveness of: (1) the abundance of a particular species of arboreal marsupial as a species-based surrogate for other arboreal marsupial taxa, (2) hollow-bearing tree abundance as a habitat-based surrogate for arboreal marsupial abundance, and (3) a combination of species- and habitat-based surrogates. We also quantify the robustness of species-based and habitat-based surrogates over time. We then use the same approach to model overall species richness of arboreal marsupials. We show that a species-based surrogate can appear to be a valid surrogate until a habitat-based surrogate is co-examined, after which the effectiveness of the former is lost. The addition of a species-based surrogate to a habitat-based surrogate made little difference in explaining arboreal marsupial abundance, but altered the co-occurrence relationship between species. Hence, there was limited value in simultaneously using a combination of kinds of surrogates. The habitat-based surrogate also generally performed significantly better and was easier and less costly to gather than the species-based surrogate. We found that over 30 years of study, the relationships which underpinned the habitat-based surrogate generally remained positive but variable over time. Our work highlights why it is important to compare the effectiveness of different broad classes of surrogates and identify situations when either species- or habitat-based surrogates are likely

  20. Characterization of Pancreatic Tumor Motion Using Cine MRI: Surrogates for Tumor Position Should Be Used With Caution

    International Nuclear Information System (INIS)

    Feng, Mary; Balter, James M.; Normolle, Daniel; Adusumilli, Saroja; Cao Yue; Chenevert, Thomas L.; Ben-Josef, Edgar

    2009-01-01

    Purpose: Our current understanding of intrafraction pancreatic tumor motion due to respiration is limited. In this study, we characterized pancreatic tumor motion and evaluated the application of several radiotherapy motion management strategies. Methods and Materials: Seventeen patients with unresectable pancreatic cancer were enrolled in a prospective internal review board-approved study and imaged during shallow free-breathing using cine MRI on a 3T scanner. Tumor borders were agreed on by a radiation oncologist and an abdominal MRI radiologist. Tumor motion and correlation with the potential surrogates of the diaphragm and abdominal wall were assessed. These data were also used to evaluate planning target volume margin construction, respiratory gating, and four-dimensional treatment planning for pancreatic tumors. Results: Tumor borders moved much more than expected. To provide 99% geometric coverage, margins of 20 mm inferiorly, 10 mm anteriorly, 7 mm superiorly, and 4 mm posteriorly are required. Tumor position correlated poorly with diaphragm and abdominal wall position, with patient-level Pearson correlation coefficients of -0.18-0.43. Sensitivity and specificity of gating with these surrogates was also poor, at 53%-68%, with overall error of 35%-38%, suggesting that the tumor may be underdosed and normal tissues overdosed. Conclusions: Motion of pancreatic tumor borders is highly variable between patients and larger than expected. There is substantial deformation with breathing, and tumor border position does not correlate well with abdominal wall or diaphragmatic position. Current motion management strategies may not account fully for tumor motion and should be used with caution.

  1. Integrating surrogate models into subsurface simulation framework allows computation of complex reactive transport scenarios

    Science.gov (United States)

    De Lucia, Marco; Kempka, Thomas; Jatnieks, Janis; Kühn, Michael

    2017-04-01

    Reactive transport simulations - where geochemical reactions are coupled with hydrodynamic transport of reactants - are extremely time consuming and suffer from significant numerical issues. Given the high uncertainties inherently associated with the geochemical models, which also constitute the major computational bottleneck, such requirements may seem inappropriate and probably constitute the main limitation for their wide application. A promising way to ease and speed-up such coupled simulations is achievable employing statistical surrogates instead of "full-physics" geochemical models [1]. Data-driven surrogates are reduced models obtained on a set of pre-calculated "full physics" simulations, capturing their principal features while being extremely fast to compute. Model reduction of course comes at price of a precision loss; however, this appears justified in presence of large uncertainties regarding the parametrization of geochemical processes. This contribution illustrates the integration of surrogates into the flexible simulation framework currently being developed by the authors' research group [2]. The high level language of choice for obtaining and dealing with surrogate models is R, which profits from state-of-the-art methods for statistical analysis of large simulations ensembles. A stand-alone advective mass transport module was furthermore developed in order to add such capability to any multiphase finite volume hydrodynamic simulator within the simulation framework. We present 2D and 3D case studies benchmarking the performance of surrogates and "full physics" chemistry in scenarios pertaining the assessment of geological subsurface utilization. [1] Jatnieks, J., De Lucia, M., Dransch, D., Sips, M.: "Data-driven surrogate model approach for improving the performance of reactive transport simulations.", Energy Procedia 97, 2016, p. 447-453. [2] Kempka, T., Nakaten, B., De Lucia, M., Nakaten, N., Otto, C., Pohl, M., Chabab [Tillner], E., Kühn, M

  2. Simultaneous tumor and surrogate motion tracking with dynamic MRI for radiation therapy planning

    Science.gov (United States)

    Park, Seyoun; Farah, Rana; Shea, Steven M.; Tryggestad, Erik; Hales, Russell; Lee, Junghoon

    2018-01-01

    Respiration-induced tumor motion is a major obstacle for achieving high-precision radiotherapy of cancers in the thoracic and abdominal regions. Surrogate-based estimation and tracking methods are commonly used in radiotherapy, but with limited understanding of quantified correlation to tumor motion. In this study, we propose a method to simultaneously track the lung tumor and external surrogates to evaluate their spatial correlation in a quantitative way using dynamic MRI, which allows real-time acquisition without ionizing radiation exposure. To capture the lung and whole tumor, four MRI-compatible fiducials are placed on the patient’s chest and upper abdomen. Two different types of acquisitions are performed in the sagittal orientation including multi-slice 2D cine MRIs to reconstruct 4D-MRI and two-slice 2D cine MRIs to simultaneously track the tumor and fiducials. A phase-binned 4D-MRI is first reconstructed from multi-slice MR images using body area as a respiratory surrogate and groupwise registration. The 4D-MRI provides 3D template volumes for different breathing phases. 3D tumor position is calculated by 3D-2D template matching in which 3D tumor templates in the 4D-MRI reconstruction and the 2D cine MRIs from the two-slice tracking dataset are registered. 3D trajectories of the external surrogates are derived via matching a 3D geometrical model of the fiducials to their segmentations on the 2D cine MRIs. We tested our method on ten lung cancer patients. Using a correlation analysis, the 3D tumor trajectory demonstrates a noticeable phase mismatch and significant cycle-to-cycle motion variation, while the external surrogate was not sensitive enough to capture such variations. Additionally, there was significant phase mismatch between surrogate signals obtained from the fiducials at different locations.

  3. Development and pilot testing of a decision aid for surrogates of patients with prolonged mechanical ventilation

    Science.gov (United States)

    Cox, Christopher E.; Lewis, Carmen L.; Hanson, Laura C.; Hough, Catherine L.; Kahn, Jeremy M.; White, Douglas B.; Song, Mi-Kyung; Tulsky, James A.; Carson, Shannon S.

    2013-01-01

    Objective Shared decision making is inadequate in intensive care units (ICUs). Decision aids can improve decision making quality, though their role in an ICU setting is unclear. We aimed to develop and pilot test a decision aid for shared decision makers of patients undergoing prolonged mechanical ventilation. Setting ICUs at three medical centers. Subjects 53 surrogate decision makers and 58 physicians. Design and interventions We developed the decision aid using defined methodological guidelines. After an iterative revision process, formative cognitive testing was performed among surrogate-physician dyads. Next, we compared the decision aid to usual care control in a prospective, before/after design study. Measurements and main results Primary outcomes were physician-surrogate discordance for expected patient survival, comprehension of relevant medical information, and the quality of communication. Compared to control, the intervention group had lower surrogate-physician discordance (7 [10] vs 43 [21]), greater comprehension (11.4 [0.7] vs 6.1 [3.7]), and improved quality of communication (8.7 [1.3] vs 8.4 [1.3]) (all ppost-intervention. Hospital costs were lower in the intervention group ($110,609 vs $178,618; p=0.044); mortality did not differ by group (38% vs 50%, p=0.95). 94% of surrogates and 100% of physicians reported that the decision aid was useful in decision making. Conclusion We developed a prolonged mechanical ventilation decision aid that is feasible, acceptable, and associated with both improved decision making quality and less resource utilization. Further evaluation using a randomized controlled trial design is needed to evaluate the decision aid's effect on long-term patient and surrogate outcomes. PMID:22635048

  4. How taxonomic diversity, community structure, and sample size determine the reliability of higher taxon surrogates.

    Science.gov (United States)

    Neeson, Thomas M; Van Rijn, Itai; Mandelik, Yael

    2013-07-01

    Ecologists and paleontologists often rely on higher taxon surrogates instead of complete inventories of biological diversity. Despite their intrinsic appeal, the performance of these surrogates has been markedly inconsistent across empirical studies, to the extent that there is no consensus on appropriate taxonomic resolution (i.e., whether genus- or family-level categories are more appropriate) or their overall usefulness. A framework linking the reliability of higher taxon surrogates to biogeographic setting would allow for the interpretation of previously published work and provide some needed guidance regarding the actual application of these surrogates in biodiversity assessments, conservation planning, and the interpretation of the fossil record. We developed a mathematical model to show how taxonomic diversity, community structure, and sampling effort together affect three measures of higher taxon performance: the correlation between species and higher taxon richness, the relative shapes and asymptotes of species and higher taxon accumulation curves, and the efficiency of higher taxa in a complementarity-based reserve-selection algorithm. In our model, higher taxon surrogates performed well in communities in which a few common species were most abundant, and less well in communities with many equally abundant species. Furthermore, higher taxon surrogates performed well when there was a small mean and variance in the number of species per higher taxa. We also show that empirically measured species-higher-taxon correlations can be partly spurious (i.e., a mathematical artifact), except when the species accumulation curve has reached an asymptote. This particular result is of considerable practical interest given the widespread use of rapid survey methods in biodiversity assessment and the application of higher taxon methods to taxa in which species accumulation curves rarely reach an asymptote, e.g., insects.

  5. Critical review of norovirus surrogates in food safety research: rationale for considering volunteer studies.

    Science.gov (United States)

    Richards, Gary P

    2012-03-01

    The inability to propagate human norovirus (NoV) or to clearly differentiate infectious from noninfectious virus particles has led to the use of surrogate viruses, like feline calicivirus (FCV) and murine norovirus-1 (MNV), which are propagatable in cell culture. The use of surrogates is predicated on the assumption that they generally mimic the viruses they represent; however, studies are proving this concept invalid. In direct comparisons between FCV and MNV, their susceptibility to temperatures, environmental and food processing conditions, and disinfectants are dramatically different. Differences have also been noted between the inactivation of NoV and its surrogates, thus questioning the validity of surrogates. Considerable research funding is provided globally each year to conduct surrogate studies on NoVs; however, there is little demonstrated benefit derived from these studies in regard to the development of virus inactivation techniques or food processing strategies. Human challenge studies are needed to determine which processing techniques are effective in reducing NoVs in foods. A major obstacle to clinical trials on NoVs is the perception that such trials are too costly and risky, but in reality, there is far more cost and risk in allowing millions of unsuspecting consumers to contract NoV illness each year, when practical interventions are only a few volunteer studies away. A number of clinical trials have been conducted, providing important insights into NoV inactivation. A shift in research priorities from surrogate research to volunteer studies is essential if we are to identify realistic, practical, and scientifically valid processing approaches to improve food safety.

  6. Committee-Based Active Learning for Surrogate-Assisted Particle Swarm Optimization of Expensive Problems.

    Science.gov (United States)

    Wang, Handing; Jin, Yaochu; Doherty, John

    2017-09-01

    Function evaluations (FEs) of many real-world optimization problems are time or resource consuming, posing a serious challenge to the application of evolutionary algorithms (EAs) to solve these problems. To address this challenge, the research on surrogate-assisted EAs has attracted increasing attention from both academia and industry over the past decades. However, most existing surrogate-assisted EAs (SAEAs) either still require thousands of expensive FEs to obtain acceptable solutions, or are only applied to very low-dimensional problems. In this paper, a novel surrogate-assisted particle swarm optimization (PSO) inspired from committee-based active learning (CAL) is proposed. In the proposed algorithm, a global model management strategy inspired from CAL is developed, which searches for the best and most uncertain solutions according to a surrogate ensemble using a PSO algorithm and evaluates these solutions using the expensive objective function. In addition, a local surrogate model is built around the best solution obtained so far. Then, a PSO algorithm searches on the local surrogate to find its optimum and evaluates it. The evolutionary search using the global model management strategy switches to the local search once no further improvement can be observed, and vice versa. This iterative search process continues until the computational budget is exhausted. Experimental results comparing the proposed algorithm with a few state-of-the-art SAEAs on both benchmark problems up to 30 decision variables as well as an airfoil design problem demonstrate that the proposed algorithm is able to achieve better or competitive solutions with a limited budget of hundreds of exact FEs.

  7. Surrogate analysis and index developer (SAID) tool and real-time data dissemination utilities

    Science.gov (United States)

    Domanski, Marian M.; Straub, Timothy D.; Wood, Molly S.; Landers, Mark N.; Wall, Gary R.; Brady, Steven J.

    2015-01-01

    The use of acoustic and other parameters as surrogates for suspended-sediment concentrations (SSC) in rivers has been successful in multiple applications across the Nation. Critical to advancing the operational use of surrogates are tools to process and evaluate the data along with the subsequent development of regression models from which real-time sediment concentrations can be made available to the public. Recent developments in both areas are having an immediate impact on surrogate research, and on surrogate monitoring sites currently in operation. The Surrogate Analysis and Index Developer (SAID) standalone tool, under development by the U.S. Geological Survey (USGS), assists in the creation of regression models that relate response and explanatory variables by providing visual and quantitative diagnostics to the user. SAID also processes acoustic parameters to be used as explanatory variables for suspended-sediment concentrations. The sediment acoustic method utilizes acoustic parameters from fixed-mount stationary equipment. The background theory and method used by the tool have been described in recent publications, and the tool also serves to support sediment-acoustic-index methods being drafted by the multi-agency Sediment Acoustic Leadership Team (SALT), and other surrogate guidelines like USGS Techniques and Methods 3-C4 for turbidity and SSC. The regression models in SAID can be used in utilities that have been developed to work with the USGS National Water Information System (NWIS) and for the USGS National Real-Time Water Quality (NRTWQ) Web site. The real-time dissemination of predicted SSC and prediction intervals for each time step has substantial potential to improve understanding of sediment-related water-quality and associated engineering and ecological management decisions.

  8. Calibration of an agricultural-hydrological model (RZWQM2) using surrogate global optimization

    Science.gov (United States)

    Xi, Maolong; Lu, Dan; Gui, Dongwei; Qi, Zhiming; Zhang, Guannan

    2017-01-01

    Robust calibration of an agricultural-hydrological model is critical for simulating crop yield and water quality and making reasonable agricultural management. However, calibration of the agricultural-hydrological system models is challenging because of model complexity, the existence of strong parameter correlation, and significant computational requirements. Therefore, only a limited number of simulations can be allowed in any attempt to find a near-optimal solution within an affordable time, which greatly restricts the successful application of the model. The goal of this study is to locate the optimal solution of the Root Zone Water Quality Model (RZWQM2) given a limited simulation time, so as to improve the model simulation and help make rational and effective agricultural-hydrological decisions. To this end, we propose a computationally efficient global optimization procedure using sparse-grid based surrogates. We first used advanced sparse grid (SG) interpolation to construct a surrogate system of the actual RZWQM2, and then we calibrate the surrogate model using the global optimization algorithm, Quantum-behaved Particle Swarm Optimization (QPSO). As the surrogate model is a polynomial with fast evaluation, it can be efficiently evaluated with a sufficiently large number of times during the optimization, which facilitates the global search. We calibrate seven model parameters against five years of yield, drain flow, and NO3-N loss data from a subsurface-drained corn-soybean field in Iowa. Results indicate that an accurate surrogate model can be created for the RZWQM2 with a relatively small number of SG points (i.e., RZWQM2 runs). Compared to the conventional QPSO algorithm, our surrogate-based optimization method can achieve a smaller objective function value and better calibration performance using a fewer number of expensive RZWQM2 executions, which greatly improves computational efficiency.

  9. Surrogacy families 10 years on: relationship with the surrogate, decisions over disclosure and children's understanding of their surrogacy origins

    Science.gov (United States)

    Jadva, V.; Blake, L.; Casey, P.; Golombok, S.

    2012-01-01

    BACKGROUND This study aimed to prospectively examine families created using surrogacy over a 10-year period in the UK with respect to intending parents' and children's relationship with the surrogate mother, parents' decisions over disclosure and children's understanding of the nature of their conception. METHODS Semi-structured interviews were administered by trained researchers to intending mothers, intending fathers and children on four occasions over a 10-year period. Forty-two families (19 with a genetic surrogate mother) participated when the child was 1-year old and by age 10 years, 33 families remained in the study. Data were collected on the frequency of contact with the surrogate mother, relationship with the surrogate, disclosure of surrogacy to the child and the child's understanding of their surrogacy birth. RESULTS Frequency of contact between surrogacy families and their surrogate mother decreased over time, particularly for families whose surrogate was a previously unknown genetic carrier (P surrogate mother's egg was used to conceive the child). Most families reported harmonious relationships with their surrogate mother. At age 10 years, 19 (90%) children who had been informed of the nature of their conception had a good understanding of this and 13 of the 14 children who were in contact with their surrogate reported that they liked her. CONCLUSIONS Surrogacy families maintained good relationships with the surrogate mother over time. Children felt positive about their surrogate mother and their surrogacy birth. The sample size of this study was small and further, larger investigations are needed before firm conclusions can be drawn. PMID:22814484

  10. Identifying deterministic signals in simulated gravitational wave data: algorithmic complexity and the surrogate data method

    International Nuclear Information System (INIS)

    Zhao Yi; Small, Michael; Coward, David; Howell, Eric; Zhao Chunnong; Ju Li; Blair, David

    2006-01-01

    We describe the application of complexity estimation and the surrogate data method to identify deterministic dynamics in simulated gravitational wave (GW) data contaminated with white and coloured noises. The surrogate method uses algorithmic complexity as a discriminating statistic to decide if noisy data contain a statistically significant level of deterministic dynamics (the GW signal). The results illustrate that the complexity method is sensitive to a small amplitude simulated GW background (SNR down to 0.08 for white noise and 0.05 for coloured noise) and is also more robust than commonly used linear methods (autocorrelation or Fourier analysis)

  11. A Successful Induction of Lactation in Surrogate Pregnancy with Metoclopramide and Review of Lactation Induction

    Directory of Open Access Journals (Sweden)

    Elahe Mirzaaga

    2010-01-01

    Full Text Available In surrogate pregnancies genetic parents have little opportunity for early bonding with their infants,either prenatally (in utero or during the immediate postnatal period. Procedures commonlyused to induce lactation include both pharmacologic and nonpharmacologic methods, often incombination. Studies reporting induced lactation are sparse, due to the rarity of augmentedlactation. Here we report a case of lactation induction following a surrogate pregnancy. Othermethods that can be used to augment lactation are described below. We used metoclopramide inthis case due to the success rates reported in previous studies and case reports. Additionally, itis a well tolerated and safe agent.

  12. Surrogate pregnancy in a patient who underwent radical hysterectomy and bilateral transposition of ovaries.

    Science.gov (United States)

    Azem, Foad; Yovel, Israel; Wagman, Israel; Kapostiansky, Rita; Lessing, Joseph B; Amit, Ami

    2003-05-01

    To evaluate IVF-surrogate pregnancy in a patient with ovarian transposition after radical hysterectomy for carcinoma of the cervix. Case report. A maternity hospital in Tel Aviv that is a major tertiary care and referral center. A 29-year-old woman who underwent Wertheim's hysterectomy for carcinoma of the uterine cervix and ovarian transposition before total pelvic irradiation. Standard IVF treatment, transabdominal oocyte retrieval, and transfer to surrogate mother. Outcome of IVF cycle. A twin pregnancy in the first cycle. This is the second reported case of controlled ovarian stimulation and oocyte retrieval performed on a transposed ovary.

  13. Decision conflict and regret among surrogate decision makers in the medical intensive care unit.

    Science.gov (United States)

    Miller, Jesse J; Morris, Peter; Files, D Clark; Gower, Emily; Young, Michael

    2016-04-01

    Family members of critically ill patients in the intensive care unit face significant morbidity. It may be the decision-making process that plays a significant role in the psychological morbidity associated with being a surrogate in the ICU. We hypothesize that family members facing end-of-life decisions will have more decisional conflict and decisional regret than those facing non-end-of-life decisions. We enrolled a sample of adult patients and their surrogates in a tertiary care, academic medical intensive care unit. We queried the surrogates regarding decisions they had made on behalf of the patient and assessed decision conflict. We then contacted the family member again to assess decision regret. Forty (95%) of 42 surrogates were able to identify at least 1 decision they had made on behalf of the patient. End-of-life decisions (defined as do not resuscitate [DNR]/do not intubate [DNI] or continuation of life support) accounted for 19 of 40 decisions (47.5%). Overall, the average Decision Conflict Scale (DCS) score was 21.9 of 100 (range 0-100, with 0 being little decisional conflict and 100 being great decisional conflict). The average DCS score for families facing end-of-life decisions was 25.5 compared with 18.7 for all other decisions. Those facing end-of-life decisions scored higher on the uncertainty subscale (subset of DCS questions that indicates level of certainty regarding decision) with a mean score of 43.4 compared with all other decisions with a mean score of 27.0. Overall, very few surrogates experienced decisional regret with an average DRS score of 13.4 of 100. Nearly all surrogates enrolled were faced with decision-making responsibilities on behalf of his or her critically ill family member. In our small pilot study, we found more decisional conflict in those surrogates facing end-of-life decisions, specifically on the subset of questions dealing with uncertainty. Surrogates report low levels of decisional regret. Copyright © 2015 Elsevier

  14. Effectiveness of external respiratory surrogates for in vivo liver motion estimation

    International Nuclear Information System (INIS)

    Chang, Kai-Hsiang; Ho, Ming-Chih; Yeh, Chi-Chuan; Chen, Yu-Chien; Lian, Feng-Li; Lin, Win-Li; Yen, Jia-Yush; Chen, Yung-Yaw

    2012-01-01

    Purpose: Due to low frame rate of MRI and high radiation damage from fluoroscopy and CT, liver motion estimation using external respiratory surrogate signals seems to be a better approach to track liver motion in real-time for liver tumor treatments in radiotherapy and thermotherapy. This work proposes a liver motion estimation method based on external respiratory surrogate signals. Animal experiments are also conducted to investigate related issues, such as the sensor arrangement, multisensor fusion, and the effective time period. Methods: Liver motion and abdominal motion are both induced by respiration and are proved to be highly correlated. Contrary to the difficult direct measurement of the liver motion, the abdominal motion can be easily accessed. Based on this idea, our study is split into the model-fitting stage and the motion estimation stage. In the first stage, the correlation between the surrogates and the liver motion is studied and established via linear regression method. In the second stage, the liver motion is estimated by the surrogate signals with the correlation model. Animal experiments on cases of single surrogate signal, multisurrogate signals, and long-term surrogate signals are conducted and discussed to verify the practical use of this approach. Results: The results show that the best single sensor location is at the middle of the upper abdomen, while multisurrogate models are generally better than the single ones. The estimation error is reduced from 0.6 mm for the single surrogate models to 0.4 mm for the multisurrogate models. The long-term validity of the estimation models is quite satisfactory within the period of 10 min with the estimation error less than 1.4 mm. Conclusions: External respiratory surrogate signals from the abdomen motion produces good performance for liver motion estimation in real-time. Multisurrogate signals enhance estimation accuracy, and the estimation model can maintain its accuracy for at least 10 min. This

  15. Nuclear Fuels & Materials Spotlight Volume 5

    International Nuclear Information System (INIS)

    Petti, David Andrew

    2016-01-01

    As the nation's nuclear energy laboratory, Idaho National Laboratory brings together talented people and specialized nuclear research capability to accomplish our mission. This edition of the Nuclear Fuels and Materials Division Spotlight provides an overview of some of our recent accomplishments in research and capability development. These accomplishments include: • Evaluation and modeling of light water reactor accident tolerant fuel concepts • Status and results of recent TRISO-coated particle fuel irradiations, post-irradiation examinations, high-temperature safety testing to demonstrate the accident performance of this fuel system, and advanced microscopy to improve the understanding of fission product transport in this fuel system. • Improvements in and applications of meso and engineering scale modeling of light water reactor fuel behavior under a range of operating conditions and postulated accidents (e.g., power ramping, loss of coolant accident, and reactivity initiated accidents) using the MARMOT and BISON codes. • Novel measurements of the properties of nuclear (actinide) materials under extreme conditions, (e.g. high pressure, low/high temperatures, high magnetic field) to improve the scientific understanding of these materials. • Modeling reactor pressure vessel behavior using the GRIZZLY code. • New methods using sound to sense temperature inside a reactor core. • Improved experimental capabilities to study the response of fusion reactor materials to a tritium plasma. Throughout Spotlight, you'll find examples of productive partnerships with academia, industry, and government agencies that deliver high-impact outcomes. The work conducted at Idaho National Laboratory helps spur innovation in nuclear energy applications that drive economic growth and energy security. We appreciate your interest in our work here at Idaho National Laboratory, and hope that you find this issue informative.

  16. Nuclear Fuels & Materials Spotlight Volume 5

    Energy Technology Data Exchange (ETDEWEB)

    Petti, David Andrew [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-10-01

    As the nation's nuclear energy laboratory, Idaho National Laboratory brings together talented people and specialized nuclear research capability to accomplish our mission. This edition of the Nuclear Fuels and Materials Division Spotlight provides an overview of some of our recent accomplishments in research and capability development. These accomplishments include: • Evaluation and modeling of light water reactor accident tolerant fuel concepts • Status and results of recent TRISO-coated particle fuel irradiations, post-irradiation examinations, high-temperature safety testing to demonstrate the accident performance of this fuel system, and advanced microscopy to improve the understanding of fission product transport in this fuel system. • Improvements in and applications of meso and engineering scale modeling of light water reactor fuel behavior under a range of operating conditions and postulated accidents (e.g., power ramping, loss of coolant accident, and reactivity initiated accidents) using the MARMOT and BISON codes. • Novel measurements of the properties of nuclear (actinide) materials under extreme conditions, (e.g. high pressure, low/high temperatures, high magnetic field) to improve the scientific understanding of these materials. • Modeling reactor pressure vessel behavior using the GRIZZLY code. • New methods using sound to sense temperature inside a reactor core. • Improved experimental capabilities to study the response of fusion reactor materials to a tritium plasma. Throughout Spotlight, you'll find examples of productive partnerships with academia, industry, and government agencies that deliver high-impact outcomes. The work conducted at Idaho National Laboratory helps spur innovation in nuclear energy applications that drive economic growth and energy security. We appreciate your interest in our work here at Idaho National Laboratory, and hope that you find this issue informative.

  17. Differences in behaviour and physiology between adult surrogate-reared and mother-reared Cynomolgous monkeys (Macaca fascicularis)

    NARCIS (Netherlands)

    Luijk, I.A.F. van; Timmermans, P.J.A.; Sweep, C.G.J.; Willems, J.; Vossen, J.M.H.

    2000-01-01

    Previous studies of the effects of rearing conditions on exploratory behaviour revealed that 80% of monkeys reared in peer groups with surrogate mothers developed neophobia, whereas only 15 % of mother-reared monkeys did. Young surrogate-reared and, especially, isolated rhesus monkeys are known to

  18. Application of computational fluid dynamics and surrogate-coupled evolutionary computing to enhance centrifugal-pump performance

    Directory of Open Access Journals (Sweden)

    Sayed Ahmed Imran Bellary

    2016-01-01

    Full Text Available To reduce the total design and optimization time, numerical analysis with surrogate-based approaches is being used in turbomachinery optimization. In this work, multiple surrogates are coupled with an evolutionary genetic algorithm to find the Pareto optimal fronts (PoFs of two centrifugal pumps with different specifications in order to enhance their performance. The two pumps were used a centrifugal pump commonly used in industry (Case I and an electrical submersible pump used in the petroleum industry (Case II. The objectives are to enhance head and efficiency of the pumps at specific flow rates. Surrogates such as response surface approximation (RSA, Kriging (KRG, neural networks and weighted-average surrogates (WASs were used to determine the PoFs. To obtain the objective functions’ values and to understand the flow physics, Reynolds-averaged Navier–Stokes equations were solved. It is found that the WAS performs better for both the objectives than any other individual surrogate. The best individual surrogates or the best predicted error sum of squares (PRESS surrogate (BPS obtained from cross-validation (CV error estimations produced better PoFs but was still unable to compete with the WAS. The high CV error-producing surrogate produced the worst PoFs. The performance improvement in this study is due to the change in flow pattern in the passage of the impeller of the pumps.

  19. Ecological consequences of alternative fuel reduction treatments in seasonally dry forests: the national fire and fire surrogate study

    Science.gov (United States)

    J.D. McIver; C.J. Fettig

    2010-01-01

    This special issue of Forest Science features the national Fire and Fire Surrogate study (FFS), a niultisite, multivariate research project that evaluates the ecological consequences of prescribed fire and its mechanical surrogates in seasonally dry forests of the United States. The need for a comprehensive national FFS study stemmed from concern that information on...

  20. Surrogacy families 10 years on: relationship with the surrogate, decisions over disclosure and child