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Sample records for surrogate solutions comparable

  1. 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.

  2. 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.

  3. 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....

  4. 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.

  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. 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...

  7. 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.

  8. Coastal aquifer management based on surrogate models and multi-objective optimization

    Science.gov (United States)

    Mantoglou, A.; Kourakos, G.

    2011-12-01

    The demand for fresh water in coastal areas and islands can be very high, especially in summer months, due to increased local needs and tourism. In order to satisfy demand, a combined management plan is proposed which involves: i) desalinization (if needed) of pumped water to a potable level using reverse osmosis and ii) injection of biologically treated waste water into the aquifer. The management plan is formulated into a multiobjective optimization framework, where simultaneous minimization of economic and environmental costs is desired; subject to a constraint to satisfy demand. The method requires modeling tools, which are able to predict the salinity levels of the aquifer in response to different alternative management scenarios. Variable density models can simulate the interaction between fresh and saltwater; however, they are computationally intractable when integrated in optimization algorithms. In order to alleviate this problem, a multi objective optimization algorithm is developed combining surrogate models based on Modular Neural Networks [MOSA(MNN)]. The surrogate models are trained adaptively during optimization based on a Genetic Algorithm. In the crossover step of the genetic algorithm, each pair of parents generates a pool of offspring. All offspring are evaluated based on the fast surrogate model. Then only the most promising offspring are evaluated based on the exact numerical model. This eliminates errors in Pareto solution due to imprecise predictions of the surrogate model. Three new criteria for selecting the most promising offspring were proposed, which improve the Pareto set and maintain the diversity of the optimum solutions. The method has important advancements compared to previous methods, e.g. alleviation of propagation of errors due to surrogate model approximations. The method is applied to a real coastal aquifer in the island of Santorini which is a very touristy island with high water demands. The results show that the algorithm

  9. Comparative Performance of Surrogate-Assisted MOEAs for Geometrical Design of Pin-Fin Heat Sinks

    Directory of Open Access Journals (Sweden)

    Siwadol Kanyakam

    2012-01-01

    Full Text Available This paper presents the comparative performance of several surrogate-assisted multiobjective evolutionary algorithms (MOEAs for geometrical design of a pin-fin heat sink (PFHS. The surrogate-assisted MOEAs are achieved by integrating multiobjective population-based incremental learning (PBIL with a quadratic response surface model (QRS, a radial-basis function (RBF interpolation technique, and a Kriging (KRG or Gaussian process model. The mixed integer/continuous multiobjective design problem of PFHS with the objective to minimise junction temperature and fan pumping power simultaneously is posed. The optimum results obtained from using the original multiobjective PBIL and the three versions of hybrid PBIL are compared. It is shown that the hybrid PBIL using KRG is the best performer. The hybrid PBILs require less number of function evaluations to surpass the original PBIL.

  10. 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.

  11. 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.

  12. 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.

  13. The kinetic and thermodynamic sorption and stabilization of multiwalled carbon nanotubes in natural organic matter surrogate solutions: The effect of surrogate molecular weight

    International Nuclear Information System (INIS)

    Li, Tingting; Lin, Daohui; Li, Lu; Wang, Zhengyu; Wu, Fengchang

    2014-01-01

    Styrene sulfonate (SS) and polystyrene sulfonates (PSSs) were used as surrogates of natural organic matter to study the effect of molecular weight (from 206.2 to 70,000 Da) on their sorption by a multiwalled carbon nanotube (MWCNT) and an activated carbon (AC) and on their stabilization of MWCNT suspension. Results indicate that surface-diffusion through the liquid-sorbent boundary was the rate-controlling step of the kinetic sorption of both MWCNTs and AC, and surface-occupying and pore-filling mechanisms respectively dominated the thermodynamic sorption of MWCNTs and AC. Sorption rates and capacities of MWCNTs and AC in molecular concentration of SS and PSS decreased with increasing molecular weight. The PSSs but not SS facilitated the stabilization of MWCNT suspension because of the increased electrosteric repulsion. The PSSs with more monomers had greater capabilities to stabilize the MWCNT suspension, but the capabilities were comparable after being normalized by the total monomer number. -- Highlights: • Surface-diffusion controlled the kinetic sorption of NOM surrogates to MWCNTs and AC. • Surface-occupying mechanism dominates the thermodynamic sorption of MWCNTs. • The sorption in molecular concentration decreased with increasing M w of the PSSs. • PSS but not SS stabilized MWCNT suspension through electrosteric repulsion. • Stabilization capabilities normalized by monomer number of the PSSs were comparable. -- Molecular weight of NOM influences its sorption on and stabilizing MWCNTs

  14. Do women who choose to become surrogate mothers have different psychological profiles compared to a normative female sample?

    Science.gov (United States)

    Pizitz, Todd D; McCullaugh, Joseph; Rabin, Alexa

    2013-03-01

    Surrogate mothers are routinely assessed for their suitability to function in the role of surrogacy. Such assessments often include psychological testing including the Minnesota multiphasic personality inventory-revised (MMPI-2). There has been a paucity of research detailing the personality structures of these women, especially with the MMPI-2. The current study examined the validity and clinical profiles of surrogate mothers (N=43) compared to a non-patient, normative reference sample of women (N=40) using their MMPI-2 results. This study examined between group differences among the 68 scales of the MMPI-2. Independent-sample t-tests were conducted for each of the scales, with those violating homogeneity of variance assessed with a non-parametric, Mann-Whitney U test. The findings demonstrated that surrogate mothers produce profiles with lower values than normative samples across several MMPI-2 scales. For this unique group, elevations were observed on scales that assess profile validity, views on traditional gender roles, repression, ego strength, social obligation and duties, and contained hostility, relative to the normative group. The findings provide an initial examination of the profiles of surrogate mothers on the MMPI-2. The findings revealed that the psychological suitability of surrogate mother candidates appear to be a composite of being both tough-minded and sensitive, sufficiently resilient to manage the role of surrogacy, and aware of the importance of emotional boundary-setting related to pre-natal attachment. Copyright © 2012 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  15. 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.

  16. Preparation and certification of solutions of perdeuterated polycyclic aromatic compounds intended for use as surrogate internal standards

    International Nuclear Information System (INIS)

    Quilliam, M.A.; Hardstaff, W.R.; Anacleto, J.F.; LeBlanc, M.D.; Stergiopoulos, V.; Dick, K.L.; Bowser, M.T.; Curtis, J.M.; Embree, D.J.; Sim, P.G.; Boyd, R.K.

    1994-01-01

    Two standard solutions of deuterated polycyclic aromatic compounds (PACs) have been prepared for use as surrogate internal standards. Solution DPAC-1 contains 21 deuterated PACs, and is intended for use with mass spectrometric (MS) detection. Most of the difficulties in certifying concentrations in DPAC-1 arose from the fact that none of the individual compounds was 100% deuterated, so that effects of mass spectrometric fragmentation are convoluted with those of isotopic distributions. The best methods are discussed for using such internal standards so as to minimize these problems, together with those arising from kinetic isotope effects. Solution DPAC-2 contains 6 deuterated PACs, and is primarily intended for use with reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection (FLD, dural programmed wavelength mode), in which the signals for analyte and internal standard are separated chromatographically rather than via the detector. Full details of the preparation of these solutions are described. In addition, examples of their use in the analysis of a certified coal-tar extract (NIST SRM 1597) are described briefly. In one example a novel HPLC-MS technique was employed, and in the other the HPLC-FLD technique was used. (orig.)

  17. 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

  18. 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

  19. 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

  20. A comparative research of different ensemble surrogate models based on set pair analysis for the DNAPL-contaminated aquifer remediation strategy optimization

    Science.gov (United States)

    Hou, Zeyu; Lu, Wenxi; Xue, Haibo; Lin, Jin

    2017-08-01

    Surrogate-based simulation-optimization technique is an effective approach for optimizing the surfactant enhanced aquifer remediation (SEAR) strategy for clearing DNAPLs. The performance of the surrogate model, which is used to replace the simulation model for the aim of reducing computation burden, is the key of corresponding researches. However, previous researches are generally based on a stand-alone surrogate model, and rarely make efforts to improve the approximation accuracy of the surrogate model to the simulation model sufficiently by combining various methods. In this regard, we present set pair analysis (SPA) as a new method to build ensemble surrogate (ES) model, and conducted a comparative research to select a better ES modeling pattern for the SEAR strategy optimization problems. Surrogate models were developed using radial basis function artificial neural network (RBFANN), support vector regression (SVR), and Kriging. One ES model is assembling RBFANN model, SVR model, and Kriging model using set pair weights according their performance, and the other is assembling several Kriging (the best surrogate modeling method of three) models built with different training sample datasets. Finally, an optimization model, in which the ES model was embedded, was established to obtain the optimal remediation strategy. The results showed the residuals of the outputs between the best ES model and simulation model for 100 testing samples were lower than 1.5%. Using an ES model instead of the simulation model was critical for considerably reducing the computation time of simulation-optimization process and maintaining high computation accuracy simultaneously.

  1. 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.

  2. 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.

  3. Rapid Optimization of External Quantum Efficiency of Thin Film Solar Cells Using Surrogate Modeling of Absorptivity.

    Science.gov (United States)

    Kaya, Mine; Hajimirza, Shima

    2018-05-25

    This paper uses surrogate modeling for very fast design of thin film solar cells with improved solar-to-electricity conversion efficiency. We demonstrate that the wavelength-specific optical absorptivity of a thin film multi-layered amorphous-silicon-based solar cell can be modeled accurately with Neural Networks and can be efficiently approximated as a function of cell geometry and wavelength. Consequently, the external quantum efficiency can be computed by averaging surrogate absorption and carrier recombination contributions over the entire irradiance spectrum in an efficient way. Using this framework, we optimize a multi-layer structure consisting of ITO front coating, metallic back-reflector and oxide layers for achieving maximum efficiency. Our required computation time for an entire model fitting and optimization is 5 to 20 times less than the best previous optimization results based on direct Finite Difference Time Domain (FDTD) simulations, therefore proving the value of surrogate modeling. The resulting optimization solution suggests at least 50% improvement in the external quantum efficiency compared to bare silicon, and 25% improvement compared to a random design.

  4. 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.

  5. The effect of prognostic data presentation format on perceived risk among surrogate decision makers of critically ill patients: a randomized comparative trial.

    Science.gov (United States)

    Chapman, Andy R; Litton, Edward; Chamberlain, Jenny; Ho, Kwok M

    2015-04-01

    The purpose of this study is to determine whether varying the format used to present prognostic data alters the perception of risk among surrogate decision makers in the intensive care unit (ICU). This was a prospective randomized comparative trial conducted in a 23-bed adult tertiary ICU. Enrolled surrogate decision makers were randomized to 1 of 2 questionnaires, which presented hypothetical ICU scenarios, identical other than the format in which prognostic data were presented (eg, frequencies vs percentages). Participants were asked to rate the risk associated with each prognostic statement. We enrolled 141 surrogate decision makers. The perception of risk varied significantly dependent on the presentation format. For "quantitative data," risks were consistently perceived as higher, when presented as frequencies (eg, 1 in 50) compared with equivalent percentages (eg, 2%). Framing "qualitative data" in terms of chance of "death" rather than "survival" led to a statistically significant increase in perceived risks. Framing "quantitative" data in this way did not significantly affect risk perception. Data format had a significant effect on how surrogate decision makers interpreted risk. Qualitative statements are interpreted widely and affected by framing. Where possible, multiple quantitative formats should be used for presenting prognostic information. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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) ...

  12. 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.

  13. Comparative Numerical Study of Four Biodiesel Surrogates for Application on Diesel 0D Phenomenological Modeling

    Directory of Open Access Journals (Sweden)

    Claude Valery Ngayihi Abbe

    2016-01-01

    Full Text Available To meet more stringent norms and standards concerning engine performances and emissions, engine manufacturers need to develop new technologies enhancing the nonpolluting properties of the fuels. In that sense, the testing and development of alternative fuels such as biodiesel are of great importance. Fuel testing is nowadays a matter of experimental and numerical work. Researches on diesel engine’s fuel involve the use of surrogates, for which the combustion mechanisms are well known and relatively similar to the investigated fuel. Biodiesel, due to its complex molecular configuration, is still the subject of numerous investigations in that area. This study presents the comparison of four biodiesel surrogates, methyl-butanoate, ethyl-butyrate, methyl-decanoate, and methyl-9-decenoate, in a 0D phenomenological combustion model. They were investigated for in-cylinder pressure, thermal efficiency, and NOx emissions. Experiments were performed on a six-cylinder turbocharged DI diesel engine fuelled by methyl ester (MEB and ethyl ester (EEB biodiesel from wasted frying oil. Results showed that, among the four surrogates, methyl butanoate presented better results for all the studied parameters. In-cylinder pressure and thermal efficiency were predicted with good accuracy by the four surrogates. NOx emissions were well predicted for methyl butanoate but for the other three gave approximation errors over 50%.

  14. Coastal aquifer management under parameter uncertainty: Ensemble surrogate modeling based simulation-optimization

    Science.gov (United States)

    Janardhanan, S.; Datta, B.

    2011-12-01

    saltwater intrusion are considered. The salinity levels resulting at strategic locations due to these pumping are predicted using the ensemble surrogates and are constrained to be within pre-specified levels. Different realizations of the concentration values are obtained from the ensemble predictions corresponding to each candidate solution of pumping. Reliability concept is incorporated as the percent of the total number of surrogate models which satisfy the imposed constraints. The methodology was applied to a realistic coastal aquifer system in Burdekin delta area in Australia. It was found that all optimal solutions corresponding to a reliability level of 0.99 satisfy all the constraints and as reducing reliability level decreases the constraint violation increases. Thus ensemble surrogate model based simulation-optimization was found to be useful in deriving multi-objective optimal pumping strategies for coastal aquifers under parameter uncertainty.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. Center-Within-Trial Versus Trial-Level Evaluation of Surrogate Endpoints

    Science.gov (United States)

    Renfro, Lindsay A.; Shi, Qian; Xue, Yuan; Li, Junlong; Shang, Hongwei; Sargent, Daniel J.

    2014-01-01

    Evaluation of candidate surrogate endpoints using individual patient data from multiple clinical trials is considered the gold standard approach to validate surrogates at both patient and trial levels. However, this approach assumes the availability of patient-level data from a relatively large collection of similar trials, which may not be possible to achieve for a given disease application. One common solution to the problem of too few similar trials involves performing trial-level surrogacy analyses on trial sub-units (e.g., centers within trials), thereby artificially increasing the trial-level sample size for feasibility of the multi-trial analysis. To date, the practical impact of treating trial sub-units (centers) identically to trials in multi-trial surrogacy analyses remains unexplored, and conditions under which this ad hoc solution may in fact be reasonable have not been identified. We perform a simulation study to identify such conditions, and demonstrate practical implications using a multi-trial dataset of patients with early stage colon cancer. PMID:25061255

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Surrogatvalidierung durch Korrelation und Surrogate Threshold Effect – Ergebnisse von Simulationsstudien

    Directory of Open Access Journals (Sweden)

    Gillhaus, Johanna

    2017-01-01

    appears to be rather complicated as well. We propose an alternative solution of comparing the value of STE with point estimate of the surrogate endpoint instead of its lower level of confidence interval showing low α-errors in realistic scenarios.

  9. 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.

  10. 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.

  11. Developing a particle tracking surrogate model to improve inversion of ground water - Surface water models

    Science.gov (United States)

    Cousquer, Yohann; Pryet, Alexandre; Atteia, Olivier; Ferré, Ty P. A.; Delbart, Célestine; Valois, Rémi; Dupuy, Alain

    2018-03-01

    The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective-dispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone.

  12. TU-CD-BRA-05: Atlas Selection for Multi-Atlas-Based Image Segmentation Using Surrogate Modeling

    International Nuclear Information System (INIS)

    Zhao, T; Ruan, D

    2015-01-01

    Purpose: The growing size and heterogeneity in training atlas necessitates sophisticated schemes to identify only the most relevant atlases for the specific multi-atlas-based image segmentation problem. This study aims to develop a model to infer the inaccessible oracle geometric relevance metric from surrogate image similarity metrics, and based on such model, provide guidance to atlas selection in multi-atlas-based image segmentation. Methods: We relate the oracle geometric relevance metric in label space to the surrogate metric in image space, by a monotonically non-decreasing function with additive random perturbations. Subsequently, a surrogate’s ability to prognosticate the oracle order for atlas subset selection is quantified probabilistically. Finally, important insights and guidance are provided for the design of fusion set size, balancing the competing demands to include the most relevant atlases and to exclude the most irrelevant ones. A systematic solution is derived based on an optimization framework. Model verification and performance assessment is performed based on clinical prostate MR images. Results: The proposed surrogate model was exemplified by a linear map with normally distributed perturbation, and verified with several commonly-used surrogates, including MSD, NCC and (N)MI. The derived behaviors of different surrogates in atlas selection and their corresponding performance in ultimate label estimate were validated. The performance of NCC and (N)MI was similarly superior to MSD, with a 10% higher atlas selection probability and a segmentation performance increase in DSC by 0.10 with the first and third quartiles of (0.83, 0.89), compared to (0.81, 0.89). The derived optimal fusion set size, valued at 7/8/8/7 for MSD/NCC/MI/NMI, agreed well with the appropriate range [4, 9] from empirical observation. Conclusion: This work has developed an efficacious probabilistic model to characterize the image-based surrogate metric on atlas selection

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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)

  19. Hybrid surrogate-model-based multi-fidelity efficient global optimization applied to helicopter blade design

    Science.gov (United States)

    Ariyarit, Atthaphon; Sugiura, Masahiko; Tanabe, Yasutada; Kanazaki, Masahiro

    2018-06-01

    A multi-fidelity optimization technique by an efficient global optimization process using a hybrid surrogate model is investigated for solving real-world design problems. The model constructs the local deviation using the kriging method and the global model using a radial basis function. The expected improvement is computed to decide additional samples that can improve the model. The approach was first investigated by solving mathematical test problems. The results were compared with optimization results from an ordinary kriging method and a co-kriging method, and the proposed method produced the best solution. The proposed method was also applied to aerodynamic design optimization of helicopter blades to obtain the maximum blade efficiency. The optimal shape obtained by the proposed method achieved performance almost equivalent to that obtained using the high-fidelity, evaluation-based single-fidelity optimization. Comparing all three methods, the proposed method required the lowest total number of high-fidelity evaluation runs to obtain a converged solution.

  20. A comparative study of the oxidation characteristics of two gasoline fuels and an n-heptane/iso-octane surrogate mixture

    KAUST Repository

    Javed, Tamour

    2015-01-01

    Ignition delay times and CO, H2O, OH and CO2 time-histories were measured behind reflected shock waves for two FACE (Fuels for Advanced Combustion Engines) gasolines and one PRF (Primary Reference Fuel) blend. The FACE gasolines chosen for this work are primarily paraffinic and have the same octane rating (∼RON = 84) as the PRF blend, but contain varying amounts of iso- and n-paraffins. Species time-histories and ignition delay times were measured using laser absorption methods over a temperature range of 1350-1550 K and pressures near 2 atm. Measured species time-histories and ignition delay times of the PRF blend and the two FACE fuels agreed reasonably well. However, when compared to recent gasoline surrogate mechanisms, the simulations did not capture some of the kinetic trends found in the species profiles. To our knowledge, this work provides some of the first shock tube species time-history data for gasoline fuels and PRF surrogates and should enable further improvements in detailed kinetic mechanisms of gasoline fuels.

  1. 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.

  2. Inactivation of human enteric virus surrogates by high-intensity ultrasound.

    Science.gov (United States)

    Su, Xiaowei; Zivanovic, Svetlana; D'Souza, Doris H

    2010-09-01

    Foodborne viruses, especially human noroviruses, are recognized as leading causes of nonbacterial gastroenteritis worldwide. Development of effective inactivation methods is of great importance to control their spread. In this study, the effect of high-intensity ultrasound (HIUS) on the infectivity of three foodborne virus surrogates was investigated. The three surrogates, murine norovirus (MNV-1), feline calicivirus (FCV-F9), and MS2 bacteriophage, were diluted in phosphate-buffered saline (PBS) or orange juice to a titer of approximately 6 log(10) PFU/mL or approximately 4 log(10) PFU/mL. The ultrasound treatment was performed in duplicate by immersing the HIUS probe in virus-containing solution that was cooled in ice-water and sonicated at 20 kHz for 2, 5, 10, 15, 20, and 30 min with 30 sec on and 30 sec off. The infectivity of the recovered viruses after each ultrasound treatment was evaluated in duplicate using standardized plaque assays and compared to untreated controls. The results show that HIUS effectiveness depended on the virus type, the initial titer of the viruses, and the virus suspension solution. At titers of approximately 4 log(10) PFU/mL in PBS, feline calicivirus (FCV)-F9, MS2, and murine norovirus (MNV)-1 required 5-, 10-, and 30-min treatment, respectively, for complete inactivation. At initial titers of approximately 4 log(10) PFU/mL in orange juice, FCV-F9 required a 15-min treatment for complete inactivation and only a 1.55 log(10) PFU/mL reduction was achieved for MNV-1 in orange juice after 30-min treatment. Thus, inactivation by HIUS in orange juice was much lower than in PBS. Experiments using titers of approximately 6 log(10) PFU/mL showed decreased effects compared to those using titers of approximately 4 log(10) PFU/mL. These results indicate that HIUS alone is not sufficient to inactivate virus in food. Hurdle technologies that combine HIUS with antimicrobials, heat, or pressure should be explored for viral inactivation.

  3. 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

  4. 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

  5. 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.

  6. Concentration of Melton Valley Storage Tank surrogates with a wiped film evaporator

    International Nuclear Information System (INIS)

    Boring, M.D.; Farr, L.L.; Fowler, V.L.; Hewitt, J.D.

    1994-08-01

    This report describes experiments to determine whether a wiped film evaporator (WFE) might be used to concentrate low-level liquid radioactive waste (LLLW). Solutions used in these studies were surrogates that contain no radionuclides. The compositions of the surrogates were based on one of Oak Ridge National Laboratory's (ORNL's) Melton Valley Storage Tanks (MVSTs). It was found that a WFE could be used to concentrate LLLW to varying degrees by manipulating various parameters. The parameters studied were rotor speed, process fluid feed temperature and feed rate, and evaporator temperature. Product consistency varied from an unsaturated liquid to a dry powder. Volume reductions up to 68% were achieved. System decontamination factors were consistently in the range of 10 4

  7. 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.

  8. 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.

  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. 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...

  11. 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.

  12. 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.

  13. Comparison of respiratory surrogates for gated lung radiotherapy without internal fiducials

    International Nuclear Information System (INIS)

    Korreman, S.; Mostafavi, H.; Le, Q.T.; Boyer, A.

    2006-01-01

    An investigation was carried out to compare the ability of two respiratory surrogates to mimic actual lung tumor motion during audio coaching. The investigation employed video clips acquired after patients had had fiducial markers implanted in lung tumors to be used for image-guided stereoscopic radiotherapy. The positions of the markers in the clips were measured within the video frames and used as the standard for tumor volume motion. An external marker was tracked optically during the fluoroscopic acquisitions. An image correlation technique was developed to compute a gating signal from the fluoroscopic images. The correlation gating trace was similar to the optical gating trace in the phase regions of the respiratory cycle used for gating. A cross correlation analysis and comparison of the external optical marker gating with internal fluoroscopic gating was performed. The fluoroscopic image correlation surrogate was found to be superior to the external optical surrogate in the AP-views in four out of six cases. In one of the remaining two cases, the two surrogates performed comparably, while in the last case, the external fiducial trace performed best. It was concluded that fluoroscopic gating based on correlation of native image features in the fluoroscopic images will be adequate for respiratory gating

  14. Comparison of respiratory surrogates for gated lung radiotherapy without internal fiducials

    Energy Technology Data Exchange (ETDEWEB)

    Korreman, S. [Rigshospitalet, Copenhagen (Denmark). Dept. of Radiation Oncology; Mostafavi, H. [Varian Medical Systems, Mountain View, CA (United States). Gintzon Technology Center; Le, Q.T.; Boyer, A. [Stanford Univ. School of Medicine, CA (United States). Dept. of Radiation Oncology

    2006-09-15

    An investigation was carried out to compare the ability of two respiratory surrogates to mimic actual lung tumor motion during audio coaching. The investigation employed video clips acquired after patients had had fiducial markers implanted in lung tumors to be used for image-guided stereoscopic radiotherapy. The positions of the markers in the clips were measured within the video frames and used as the standard for tumor volume motion. An external marker was tracked optically during the fluoroscopic acquisitions. An image correlation technique was developed to compute a gating signal from the fluoroscopic images. The correlation gating trace was similar to the optical gating trace in the phase regions of the respiratory cycle used for gating. A cross correlation analysis and comparison of the external optical marker gating with internal fluoroscopic gating was performed. The fluoroscopic image correlation surrogate was found to be superior to the external optical surrogate in the AP-views in four out of six cases. In one of the remaining two cases, the two surrogates performed comparably, while in the last case, the external fiducial trace performed best. It was concluded that fluoroscopic gating based on correlation of native image features in the fluoroscopic images will be adequate for respiratory gating.

  15. 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.

  16. Effects of a Mechanical Response-Contingent Surrogate on the Development of Behaviors in Nursery-Reared Rhesus Macaques (Macaca mulatta)

    Science.gov (United States)

    Brunelli, Rebecca L; Blake, Jennifer; Willits, Neil; Rommeck, Ina; McCowan, Brenda

    2014-01-01

    Nursery-reared infants have several behavioral and physiologic differences from their mother-reared counterparts. We investigated whether a response-contingent surrogate mitigated some of those differences by decreasing fearfulness and partner-clinging and increasing environmental exploration in nursery-reared infants continuously paired with a peer. Six nursery-reared infant rhesus macaques (in pairs) were given a mechanical responsive surrogate (RS), and 6 (in pairs) were given an identical but nonresponsive surrogate (NRS). The 2 treatment groups were compared and then combined into a single group of all 12 of surrogate-exposed animals (CS) that was compared with a nonsurrogate control group (NS) of 10 nursery-reared infants. Results showed significant differences between CS and NS infants but no significant differences between the RS and NRS infants. As compared with NS infants, CS infants showed less partner-clinging, less affiliation directed toward only partner, and more foraging and tactile–oral exploration of the environment. These advantageous effects support additional research to develop improved surrogate and the implementation of surrogate programs for nursery-reared infants. PMID:25255068

  17. 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...

  18. 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.

  19. 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

  20. 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

  1. 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...

  2. FENOMENA SURROGATE MOTHER (IBU PENGGANTI DALAM PERSPEKTIF ISLAM DITINJAU DARI HADIS

    Directory of Open Access Journals (Sweden)

    Nurul Alifah Rahmawati

    2018-03-01

    Full Text Available In this modern era, there is a finding in technology in the field of genetically changes which try to help the married couple with no children for a long time of marriage. This change can be seen in the existence of an infant with infitro fertilization, sperm banks, or magic box that can save sperm and ovum as they are in the real womb. As the time is gone, the practice of infant with  infitro fertilization and artificial insemination have developed in some forms of activity which are forbidden in Islam. One of the forbidden forms is infitro insemination or artificial insemination which uses the sperm and ovum from a marriage couple and put it in another woman’s womb. This practice is called as Surrogate Mother. Actually there is no verses in the al-Qur’an which strictly stated about the prohibition on the practice of infitro infant using another woman’s womb (Surrogate mother. But it does not mean that al-Qur’an does not give any solution and also guidance in solving the law of this problem. There are some syar’i theorems that can be used as references in the issue of surrogate mother, for example Q.S Maryam verse 3-5 which give us command to keep praying and trying to get descendents, Q.S al-Baqarah verse 223 which states that a wife is the best place for farming and also hadith of the prophet Muhammad SAW which forbid a man to give his sperm to another woman who is not their wife. Moreover, the practice of this surrogate mother is also contradictory with with al-maqasid al-shariah because it can cause a mixed Nasab. Based on those reasons, the writer is interested in analyzing how is the surrogate mother phenomenon in the view of hadith and its contextualization dealing with the children’s position in the law of Waris (inheritance. Based on the literature analysis done by the writer, it can be concluded that the practice of surrogate mother is forbidden according to Ulama because it gives more mudharat (negative effects than

  3. 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.

  4. 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....

  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. 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.

  7. 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)

  8. 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.

  9. 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)

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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…

  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. 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.

  17. 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

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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.

  3. Process optimization of a non-circular drawing sequence based on multi-surrogate assisted meta-heuristic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Pholdee, Nantiwat; Bureerat, Su Jin [Khon Kaen University, Khon Kaen (Thailand); Baek, Hyun Moo [DTaQ, Changwon (Korea, Republic of); Im, Yong Taek [KAIST, Daejeon (Korea, Republic of)

    2015-08-15

    Process optimization of a Non-circular drawing (NCD) sequence of a pearlitic steel wire was performed to improve the mechanical properties of a drawn wire based on surrogate assisted meta-heuristic algorithms. The objective function was introduced to minimize inhomogeneity of effective strain distribution at the cross-section of the drawn wire, which could deteriorate delamination characteristics of the drawn wires. The design variables introduced were die geometry and reduction of area of the NCD sequence. Several surrogate models and their combinations with the weighted sum technique were utilized. In the process optimization of the NCD sequence, the surrogate models were used to predict effective strain distributions at the cross-section of the drawn wire. Optimization using Differential evolution (DE) algorithm was performed, while the objective function was calculated from the predicted effective strains. The accuracy of all surrogate models was investigated, while optimum results were compared with the previous study available in the literature. It was found that hybrid surrogate models can improve prediction accuracy compared to a single surrogate model. The best result was obtained from the combination of Kriging (KG) and Support vector regression (SVR) models, while the second best was obtained from the combination of four surrogate models: Polynomial response surface (PRS), Radial basic function (RBF), KG, and SVR. The optimum results found in this study showed better effective strain homogeneity at the cross-section of the drawn wire with the same total reduction of area of the previous work available in the literature for fewer number of passes. The multi-surrogate models with the weighted sum technique were found to be powerful in improving the delamination characteristics of the drawn wire and reducing the production cost.

  4. 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

  5. Family matters: effects of birth order, culture, and family dynamics on surrogate decision-making.

    Science.gov (United States)

    Su, Christopher T; McMahan, Ryan D; Williams, Brie A; Sharma, Rashmi K; Sudore, Rebecca L

    2014-01-01

    Cultural attitudes about medical decision-making and filial expectations may lead some surrogates to experience stress and family conflict. Thirteen focus groups with racially and ethnically diverse English and Spanish speakers from county and Veterans Affairs hospitals, senior centers, and cancer support groups were conducted to describe participants' experiences making serious or end-of-life decisions for others. Filial expectations and family dynamics related to birth order and surrogate decision-making were explored using qualitative, thematic content analysis, and overarching themes from focus group transcripts were identified. The mean age of the 69 participants was 69 ± 14, and 29% were African American, 26% were white, 26% were Asian or Pacific Islander, and 19% were Latino. Seventy percent of participants engaged in unprompted discussions about birth order and family dynamics. Six subthemes were identified within three overarching categories: communication (unspoken expectations and discussion of death as taboo), emotion (emotional stress and feelings of loneliness), and conflict (family conflict and potential solutions to prevent conflict). These findings suggest that birth order and family dynamics can have profound effects on surrogate stress and coping. Clinicians should be aware of potential unspoken filial expectations for firstborns and help facilitate communication between the patient, surrogate, and extended family to reduce stress and conflict. © Published 2013. This article is a U.S. Government work and is in the public domain in the U.S.A.

  6. Family Matters: Effects of Birth Order, Culture, and Family Dynamics on Surrogate Decision Making

    Science.gov (United States)

    Su, Christopher T.; McMahan, Ryan D.; Williams, Brie A.; Sharma, Rashmi K.; Sudore, Rebecca L.

    2014-01-01

    Cultural attitudes about medical decision making and filial expectations may lead some surrogates to experience stress and family conflict. Thirteen focus groups with racially and ethnically diverse English- and Spanish-speakers from county and Veterans hospitals, senior centers, and cancer support groups were conducted to describe participants’ experiences making serious or end-of-life decisions for others. Filial expectations and family dynamics related to birth order and surrogate decision making were explored using qualitative, thematic content analysis and overarching themes from focus group transcripts were identified. The mean age of the 69 participants was 69 years ± 14 and 29% were African American, 26% were White, 26% were Asian/Pacific Islander, and 19% were Latino. Seventy percent of participants engaged in unprompted discussions about birth order and family dynamics. Six subthemes were identified within 3 overarching categories of communication, emotion, and conflict: Communication – (1) unspoken expectations and (2) discussion of death as taboo; Emotion – (3) emotional stress and (4) feelings of loneliness; and Conflict – (5) family conflict and (6) potential solutions to prevent conflict. These findings suggest that birth order and family dynamics can have profound effects on surrogate stress and coping. Clinicians should be aware of potential unspoken filial expectations for firstborns and help facilitate communication between the patient, surrogate, and extended family to reduce stress and conflict. PMID:24383459

  7. Laminar Flame Speeds of Gasoline Surrogates Measured with the Flat Flame Method

    KAUST Repository

    Liao, Y.-H.

    2016-01-27

    © 2016 American Chemical Society. The adiabatic, laminar flame speeds of gasoline surrogates at atmospheric pressure over a range of equivalence ratios of = 0.8-1.3 and unburned gas temperatures of 298-400 K are measured with the flat flame method, which produces a one-dimensional flat flame free of stretch. Surrogates used in the current work are the primary reference fuels (PRFs, mixtures of n-heptane and isooctane), the toluene reference fuels (TRFs, mixtures of toluene and PRFs), and the ethanol reference fuels (ERFs, mixtures of ethanol and PRFs). In general, there is good agreement between the present work and the literature data for single-component fuel and PRF mixtures. Surrogates of TRF mixtures are found to exhibit comparable flame speeds to a real gasoline, while there is discrepancy observed between isooctane and gasoline. Moreover, the laminar flame speeds of TRF mixtures with similar fractions of n-heptane are found to be insensitive to the quantity of toluene in the mixture. Mixtures of ERFs exhibit comparable flame speeds to those of TRFs with similar mole fractions of n-heptane and isooctane.

  8. 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.

  9. 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.

  10. 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.

  11. [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.

  12. 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

  13. Surrogate model approach for improving the performance of reactive transport simulations

    Science.gov (United States)

    Jatnieks, Janis; De Lucia, Marco; Sips, Mike; Dransch, Doris

    2016-04-01

    Reactive transport models can serve a large number of important geoscientific applications involving underground resources in industry and scientific research. It is common for simulation of reactive transport to consist of at least two coupled simulation models. First is a hydrodynamics simulator that is responsible for simulating the flow of groundwaters and transport of solutes. Hydrodynamics simulators are well established technology and can be very efficient. When hydrodynamics simulations are performed without coupled geochemistry, their spatial geometries can span millions of elements even when running on desktop workstations. Second is a geochemical simulation model that is coupled to the hydrodynamics simulator. Geochemical simulation models are much more computationally costly. This is a problem that makes reactive transport simulations spanning millions of spatial elements very difficult to achieve. To address this problem we propose to replace the coupled geochemical simulation model with a surrogate model. A surrogate is a statistical model created to include only the necessary subset of simulator complexity for a particular scenario. To demonstrate the viability of such an approach we tested it on a popular reactive transport benchmark problem that involves 1D Calcite transport. This is a published benchmark problem (Kolditz, 2012) for simulation models and for this reason we use it to test the surrogate model approach. To do this we tried a number of statistical models available through the caret and DiceEval packages for R, to be used as surrogate models. These were trained on randomly sampled subset of the input-output data from the geochemical simulation model used in the original reactive transport simulation. For validation we use the surrogate model to predict the simulator output using the part of sampled input data that was not used for training the statistical model. For this scenario we find that the multivariate adaptive regression splines

  14. 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.

  15. Is blood pressure reduction a valid surrogate endpoint for stroke prevention? an analysis incorporating a systematic review of randomised controlled trials, a by-trial weighted errors-in-variables regression, the surrogate threshold effect (STE) and the biomarker-surrogacy (BioSurrogate) evaluation schema (BSES)

    Science.gov (United States)

    2012-01-01

    Background Blood pressure is considered to be a leading example of a valid surrogate endpoint. The aims of this study were to (i) formally evaluate systolic and diastolic blood pressure reduction as a surrogate endpoint for stroke prevention and (ii) determine what blood pressure reduction would predict a stroke benefit. Methods We identified randomised trials of at least six months duration comparing any pharmacologic anti-hypertensive treatment to placebo or no treatment, and reporting baseline blood pressure, on-trial blood pressure, and fatal and non-fatal stroke. Trials with fewer than five strokes in at least one arm were excluded. Errors-in-variables weighted least squares regression modelled the reduction in stroke as a function of systolic blood pressure reduction and diastolic blood pressure reduction respectively. The lower 95% prediction band was used to determine the minimum systolic blood pressure and diastolic blood pressure difference, the surrogate threshold effect (STE), below which there would be no predicted stroke benefit. The STE was used to generate the surrogate threshold effect proportion (STEP), a surrogacy metric, which with the R-squared trial-level association was used to evaluate blood pressure as a surrogate endpoint for stroke using the Biomarker-Surrogacy Evaluation Schema (BSES3). Results In 18 qualifying trials representing all pharmacologic drug classes of antihypertensives, assuming a reliability coefficient of 0.9, the surrogate threshold effect for a stroke benefit was 7.1 mmHg for systolic blood pressure and 2.4 mmHg for diastolic blood pressure. The trial-level association was 0.41 and 0.64 and the STEP was 66% and 78% for systolic and diastolic blood pressure respectively. The STE and STEP were more robust to measurement error in the independent variable than R-squared trial-level associations. Using the BSES3, assuming a reliability coefficient of 0.9, systolic blood pressure was a B + grade and diastolic blood pressure

  16. 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

  17. 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.

  18. Robust best linear estimation for regression analysis using surrogate and instrumental variables.

    Science.gov (United States)

    Wang, C Y

    2012-04-01

    We investigate methods for regression analysis when covariates are measured with errors. In a subset of the whole cohort, a surrogate variable is available for the true unobserved exposure variable. The surrogate variable satisfies the classical measurement error model, but it may not have repeated measurements. In addition to the surrogate variables that are available among the subjects in the calibration sample, we assume that there is an instrumental variable (IV) that is available for all study subjects. An IV is correlated with the unobserved true exposure variable and hence can be useful in the estimation of the regression coefficients. We propose a robust best linear estimator that uses all the available data, which is the most efficient among a class of consistent estimators. The proposed estimator is shown to be consistent and asymptotically normal under very weak distributional assumptions. For Poisson or linear regression, the proposed estimator is consistent even if the measurement error from the surrogate or IV is heteroscedastic. Finite-sample performance of the proposed estimator is examined and compared with other estimators via intensive simulation studies. The proposed method and other methods are applied to a bladder cancer case-control study.

  19. Geometric Generalisation of Surrogate Model-Based Optimisation to Combinatorial and Program Spaces

    Directory of Open Access Journals (Sweden)

    Yong-Hyuk Kim

    2014-01-01

    Full Text Available Surrogate models (SMs can profitably be employed, often in conjunction with evolutionary algorithms, in optimisation in which it is expensive to test candidate solutions. The spatial intuition behind SMs makes them naturally suited to continuous problems, and the only combinatorial problems that have been previously addressed are those with solutions that can be encoded as integer vectors. We show how radial basis functions can provide a generalised SM for combinatorial problems which have a geometric solution representation, through the conversion of that representation to a different metric space. This approach allows an SM to be cast in a natural way for the problem at hand, without ad hoc adaptation to a specific representation. We test this adaptation process on problems involving binary strings, permutations, and tree-based genetic programs.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Drug release into hydrogel-based subcutaneous surrogates studied by UV imaging

    DEFF Research Database (Denmark)

    Ye, Fengbin; Larsen, Susan Weng; Yaghmur, Anan

    2012-01-01

    of the performance of drug delivery systems based on in vitro experiments. The objective of this study was to evaluate a UV imaging-based method for real-time characterization of the release and transport of piroxicam in hydrogel-based subcutaneous tissue mimics/surrogates. Piroxicam partitioning from medium chain...... upon the injection of aqueous or MCT solutions into an agarose-based hydrogel were investigated by UV imaging. The spatial distribution of piroxicam around the injection site in the gel matrix was monitored in real-time. The disappearance profiles of piroxicam from the injected aqueous solution were...... obtained. This study shows that the UV imaging methodology has considerable potential for characterizing transport properties in hydrogels, including monitoring the real-time spatial concentration distribution in vitro after administration by injection....

  5. 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

  6. 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

  7. Is blood pressure reduction a valid surrogate endpoint for stroke prevention? an analysis incorporating a systematic review of randomised controlled trials, a by-trial weighted errors-in-variables regression, the surrogate threshold effect (STE and the biomarker-surrogacy (BioSurrogate evaluation schema (BSES

    Directory of Open Access Journals (Sweden)

    Lassere Marissa N

    2012-03-01

    Full Text Available Abstract Background Blood pressure is considered to be a leading example of a valid surrogate endpoint. The aims of this study were to (i formally evaluate systolic and diastolic blood pressure reduction as a surrogate endpoint for stroke prevention and (ii determine what blood pressure reduction would predict a stroke benefit. Methods We identified randomised trials of at least six months duration comparing any pharmacologic anti-hypertensive treatment to placebo or no treatment, and reporting baseline blood pressure, on-trial blood pressure, and fatal and non-fatal stroke. Trials with fewer than five strokes in at least one arm were excluded. Errors-in-variables weighted least squares regression modelled the reduction in stroke as a function of systolic blood pressure reduction and diastolic blood pressure reduction respectively. The lower 95% prediction band was used to determine the minimum systolic blood pressure and diastolic blood pressure difference, the surrogate threshold effect (STE, below which there would be no predicted stroke benefit. The STE was used to generate the surrogate threshold effect proportion (STEP, a surrogacy metric, which with the R-squared trial-level association was used to evaluate blood pressure as a surrogate endpoint for stroke using the Biomarker-Surrogacy Evaluation Schema (BSES3. Results In 18 qualifying trials representing all pharmacologic drug classes of antihypertensives, assuming a reliability coefficient of 0.9, the surrogate threshold effect for a stroke benefit was 7.1 mmHg for systolic blood pressure and 2.4 mmHg for diastolic blood pressure. The trial-level association was 0.41 and 0.64 and the STEP was 66% and 78% for systolic and diastolic blood pressure respectively. The STE and STEP were more robust to measurement error in the independent variable than R-squared trial-level associations. Using the BSES3, assuming a reliability coefficient of 0.9, systolic blood pressure was a B + grade and

  8. 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

  9. 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.

  10. 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.

  11. Variable reliability of surrogate measures of insulin sensitivity after Roux-en-Y gastric bypass

    DEFF Research Database (Denmark)

    Bojsen-Møller, Kirstine N; Dirksen, Carsten; Svane, Maria Saur

    2017-01-01

    ) are frequently used, but have not been validated after RYGB. Our aim was to evaluate whether surrogate indices reliably estimate changes in insulin sensitivity after RYGB. Four fasting (inverse-HOMA-IR, HOMA2-%S, QUICKI, revised-QUICKI) and three OGTT-derived surrogates (Matsuda, Gutt, OGIS) were compared...... postoperatively. Post-RYGB changes in inverse-HOMA-IR and HOMA2-%S did not correlate with changes in Rd at any visit, but were comparable to changes in HISI at 1 week. Changes in QUICKI and revised-QUICKI correlated with Rd/I after surgery. Changes in Matsuda and Gutt did not correlate with changes in Rd/I and Rd...

  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 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.

  14. 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

  15. 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.

  16. 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...

  17. 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

  18. Surrogate mother - praiseworthy or stigmatized: a qualitative study on perceptions of surrogacy in Assam, India.

    Science.gov (United States)

    Arvidsson, Anna; Vauquline, Polly; Johnsdotter, Sara; Essén, Birgitta

    2017-01-01

    Surrogacy is a reproductive practice that has been strongly marketed in India as a solution for childless couples. As a result, the number of surrogacy clinics is increasing. Meanwhile, a global discourse on surrogacy, originating from a Western perspective, has characterized surrogacy as being exploitative of women in low-income settings, where poverty drives them to become surrogate mothers. This study explored perspectives on surrogacy from men and women in Assam, an Indian state known to be a low-income setting. Surrogacy arrangements in Assam are still uncommon. It can be expected that the dominant global discourses on surrogacy will be unfamiliar to the general population, and the objective was also to position the results within the divergent global discourses of surrogacy.  In order to explore local views on surrogacy, we conducted individual interviews and focus group discussions with people from various socioeconomic groups in Assam. Our findings reveal that people in Assam perceive surrogacy as a good option for a childless couple, as it would result in a child who is a 'blood' relation - something highly desirable for sociocultural reasons. However, the part played by the surrogate mother complicates local views on surrogacy. Most people consider payment to the surrogate mother contrary to societal norms. A surrogate mother is also often judged in a moral light, either as a 'bad mother' for selling her child, or as a 'noble woman' who has helped a childless couple and deserves payment for her services. In order to decrease the stigmatization of women, a regulatory policy is needed that will take into account the complex understandings of surrogacy and perceptions of surrogate mothers in Indian society. In policy, the possible effect of the dominant exploitation discourse needs to be modulated by local understandings of this reproduction method.

  19. 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.

  20. 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

  1. 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

  2. Audiovisual biofeedback improves the correlation between internal/external surrogate motion and lung tumor motion.

    Science.gov (United States)

    Lee, Danny; Greer, Peter B; Paganelli, Chiara; Ludbrook, Joanna Jane; Kim, Taeho; Keall, Paul

    2018-03-01

    Breathing management can reduce breath-to-breath (intrafraction) and day-by-day (interfraction) variability in breathing motion while utilizing the respiratory motion of internal and external surrogates for respiratory guidance. Audiovisual (AV) biofeedback, an interactive personalized breathing motion management system, has been developed to improve reproducibility of intra- and interfraction breathing motion. However, the assumption of the correlation of respiratory motion between surrogates and tumors is not always verified during medical imaging and radiation treatment. Therefore, the aim of the study was to test the hypothesis that the correlation of respiratory motion between surrogates and tumors is the same under free breathing without guidance (FB) and with AV biofeedback guidance for voluntary motion management. For 13 lung cancer patients receiving radiotherapy, 2D coronal and sagittal cine-MR images were acquired across two MRI sessions (pre- and mid-treatment) with two breathing conditions: (a) FB and (b) AV biofeedback, totaling 88 patient measurements. Simultaneously, the external respiratory motion of the abdomen was measured. The internal respiratory motion of the diaphragm and lung tumor was retrospectively measured from 2D coronal and sagittal cine-MR images. The correlation of respiratory motion between surrogates and tumors was calculated using Pearson's correlation coefficient for: (a) abdomen to tumor (abdomen-tumor) and (b) diaphragm to tumor (diaphragm-tumor). The correlations were compared between FB and AV biofeedback using several metrics: abdomen-tumor and diaphragm-tumor correlations with/without ≥5 mm tumor motion range and with/without adjusting for phase shifts between the signals. Compared to FB, AV biofeedback improved abdomen-tumor correlation by 11% (p = 0.12) from 0.53 to 0.59 and diaphragm-tumor correlation by 13% (p = 0.02) from 0.55 to 0.62. Compared to FB, AV biofeedback improved abdomen-tumor correlation by 17% (p = 0

  3. 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.

  4. 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...

  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. Fast and Accurate Prediction of Numerical Relativity Waveforms from Binary Black Hole Coalescences Using Surrogate Models.

    Science.gov (United States)

    Blackman, Jonathan; Field, Scott E; Galley, Chad R; Szilágyi, Béla; Scheel, Mark A; Tiglio, Manuel; Hemberger, Daniel A

    2015-09-18

    Simulating a binary black hole coalescence by solving Einstein's equations is computationally expensive, requiring days to months of supercomputing time. Using reduced order modeling techniques, we construct an accurate surrogate model, which is evaluated in a millisecond to a second, for numerical relativity (NR) waveforms from nonspinning binary black hole coalescences with mass ratios in [1, 10] and durations corresponding to about 15 orbits before merger. We assess the model's uncertainty and show that our modeling strategy predicts NR waveforms not used for the surrogate's training with errors nearly as small as the numerical error of the NR code. Our model includes all spherical-harmonic _{-2}Y_{ℓm} waveform modes resolved by the NR code up to ℓ=8. We compare our surrogate model to effective one body waveforms from 50M_{⊙} to 300M_{⊙} for advanced LIGO detectors and find that the surrogate is always more faithful (by at least an order of magnitude in most cases).

  7. A new surrogate modeling technique combining Kriging and polynomial chaos expansions – Application to uncertainty analysis in computational dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Kersaudy, Pierric, E-mail: pierric.kersaudy@orange.com [Orange Labs, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France); Whist Lab, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France); ESYCOM, Université Paris-Est Marne-la-Vallée, 5 boulevard Descartes, 77700 Marne-la-Vallée (France); Sudret, Bruno [ETH Zürich, Chair of Risk, Safety and Uncertainty Quantification, Stefano-Franscini-Platz 5, 8093 Zürich (Switzerland); Varsier, Nadège [Orange Labs, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France); Whist Lab, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France); Picon, Odile [ESYCOM, Université Paris-Est Marne-la-Vallée, 5 boulevard Descartes, 77700 Marne-la-Vallée (France); Wiart, Joe [Orange Labs, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France); Whist Lab, 38 avenue du Général Leclerc, 92130 Issy-les-Moulineaux (France)

    2015-04-01

    In numerical dosimetry, the recent advances in high performance computing led to a strong reduction of the required computational time to assess the specific absorption rate (SAR) characterizing the human exposure to electromagnetic waves. However, this procedure remains time-consuming and a single simulation can request several hours. As a consequence, the influence of uncertain input parameters on the SAR cannot be analyzed using crude Monte Carlo simulation. The solution presented here to perform such an analysis is surrogate modeling. This paper proposes a novel approach to build such a surrogate model from a design of experiments. Considering a sparse representation of the polynomial chaos expansions using least-angle regression as a selection algorithm to retain the most influential polynomials, this paper proposes to use the selected polynomials as regression functions for the universal Kriging model. The leave-one-out cross validation is used to select the optimal number of polynomials in the deterministic part of the Kriging model. The proposed approach, called LARS-Kriging-PC modeling, is applied to three benchmark examples and then to a full-scale metamodeling problem involving the exposure of a numerical fetus model to a femtocell device. The performances of the LARS-Kriging-PC are compared to an ordinary Kriging model and to a classical sparse polynomial chaos expansion. The LARS-Kriging-PC appears to have better performances than the two other approaches. A significant accuracy improvement is observed compared to the ordinary Kriging or to the sparse polynomial chaos depending on the studied case. This approach seems to be an optimal solution between the two other classical approaches. A global sensitivity analysis is finally performed on the LARS-Kriging-PC model of the fetus exposure problem.

  8. 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.

  9. 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.

  10. Surrogate mother – praiseworthy or stigmatized: a qualitative study on perceptions of surrogacy in Assam, India

    Science.gov (United States)

    Arvidsson, Anna; Vauquline, Polly; Johnsdotter, Sara; Essén, Birgitta

    2017-01-01

    ABSTRACT Background: Surrogacy is a reproductive practice that has been strongly marketed in India as a solution for childless couples. As a result, the number of surrogacy clinics is increasing. Meanwhile, a global discourse on surrogacy, originating from a Western perspective, has characterized surrogacy as being exploitative of women in low-income settings, where poverty drives them to become surrogate mothers. Objective: This study explored perspectives on surrogacy from men and women in Assam, an Indian state known to be a low-income setting. Surrogacy arrangements in Assam are still uncommon. It can be expected that the dominant global discourses on surrogacy will be unfamiliar to the general population, and the objective was also to position the results within the divergent global discourses of surrogacy. Methods: In order to explore local views on surrogacy, we conducted individual interviews and focus group discussions with people from various socioeconomic groups in Assam. Results: Our findings reveal that people in Assam perceive surrogacy as a good option for a childless couple, as it would result in a child who is a ‘blood’ relation – something highly desirable for sociocultural reasons. However, the part played by the surrogate mother complicates local views on surrogacy. Most people consider payment to the surrogate mother contrary to societal norms. A surrogate mother is also often judged in a moral light, either as a ‘bad mother’ for selling her child, or as a ‘noble woman’ who has helped a childless couple and deserves payment for her services. Conclusions: In order to decrease the stigmatization of women, a regulatory policy is needed that will take into account the complex understandings of surrogacy and perceptions of surrogate mothers in Indian society. In policy, the possible effect of the dominant exploitation discourse needs to be modulated by local understandings of this reproduction method. PMID:28604252

  11. 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

  12. 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.

  13. SU-E-I-71: Quality Assessment of Surrogate Metrics in Multi-Atlas-Based Image Segmentation

    International Nuclear Information System (INIS)

    Zhao, T; Ruan, D

    2015-01-01

    Purpose: With the ever-growing data of heterogeneous quality, relevance assessment of atlases becomes increasingly critical for multi-atlas-based image segmentation. However, there is no universally recognized best relevance metric and even a standard to compare amongst candidates remains elusive. This study, for the first time, designs a quantification to assess relevance metrics’ quality, based on a novel perspective of the metric as surrogate for inferring the inaccessible oracle geometric agreement. Methods: We first develop an inference model to relate surrogate metrics in image space to the underlying oracle relevance metric in segmentation label space, with a monotonically non-decreasing function subject to random perturbations. Subsequently, we investigate model parameters to reveal key contributing factors to surrogates’ ability in prognosticating the oracle relevance value, for the specific task of atlas selection. Finally, we design an effective contract-to-noise ratio (eCNR) to quantify surrogates’ quality based on insights from these analyses and empirical observations. Results: The inference model was specialized to a linear function with normally distributed perturbations, with surrogate metric exemplified by several widely-used image similarity metrics, i.e., MSD/NCC/(N)MI. Surrogates’ behaviors in selecting the most relevant atlases were assessed under varying eCNR, showing that surrogates with high eCNR dominated those with low eCNR in retaining the most relevant atlases. In an end-to-end validation, NCC/(N)MI with eCNR of 0.12 compared to MSD with eCNR of 0.10 resulted in statistically better segmentation with mean DSC of about 0.85 and the first and third quartiles of (0.83, 0.89), compared to MSD with mean DSC of 0.84 and the first and third quartiles of (0.81, 0.89). Conclusion: The designed eCNR is capable of characterizing surrogate metrics’ quality in prognosticating the oracle relevance value. It has been demonstrated to be

  14. Construction of accuracy-preserving surrogate for the eigenvalue radiation diffusion and/or transport problem

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.; Abdel-Khalik, H. S. [Dept. of Nuclear Engineering, North Caroline State Univ., Raleigh, NC 27695 (United States)

    2012-07-01

    The construction of surrogate models for high fidelity models is now considered an important objective in support of all engineering activities which require repeated execution of the simulation, such as verification studies, validation exercises, and uncertainty quantification. The surrogate must be computationally inexpensive to allow its repeated execution, and must be computationally accurate in order for its predictions to be credible. This manuscript introduces a new surrogate construction approach that reduces the dimensionality of the state solution via a range-finding algorithm from linear algebra. It then employs a proper orthogonal decomposition-like approach to solve for the reduced state. The algorithm provides an upper bound on the error resulting from the reduction. Different from the state-of-the-art, the new approach allows the user to define the desired accuracy a priori which controls the maximum allowable reduction. We demonstrate the utility of this approach using an eigenvalue radiation diffusion model, where the accuracy is selected to match machine precision. Results indicate that significant reduction is possible for typical reactor assembly models, which are currently considered expensive given the need to employ very fine mesh many group calculations to ensure the highest possible fidelity for the downstream core calculations. Given the potential for significant reduction in the computational cost, we believe it is possible to rethink the manner in which homogenization theory is currently employed in reactor design calculations. (authors)

  15. Effectiveness of sanitizing products on controlling selected pathogen surrogates on retail deli slicers.

    Science.gov (United States)

    Yeater, Michael C; Kirsch, Katie R; Taylor, T Matthew; Mitchell, Jeff; Osburn, Wesley N

    2015-04-01

    The objectives of this study were (i) to assess the efficacy of quaternary ammonium chloride-based wet foam (WF) and dry foam (DF) sanitizer systems (600 ppm) for reducing Listeria innocua (a nonpathogenic surrogate of Listeria monocytogenes) or a 100.0 μg/ml rifampin-resistant Salmonella Typhimurium LT2 (a nonpathogenic surrogate of Salmonella enterica serovar Typhimurium) on niche and transfer point areas of an unwashed retail deli slicer as compared with traditional chlorine (Cl(-)) treatment (200 ppm) and (ii) to compare sanitizer surface contact times (10 and 15 min) for pathogen surrogate control. Turkey frankfurter slurries inoculated with L. innocua or Salmonella Typhimurium were used to inoculate seven high-risk sites on a commercial slicer. After 30 min of bacterial attachment, slicers were dry wiped to remove excess food matter, followed by a randomly assigned sanitizer treatment. Surviving pathogen surrogate cells were enumerated on modified Oxford's agar not containing antimicrobic supplement (L. innocua) or on tryptic soy agar supplemented with 100 μg/ml rifampin (Salmonella Typhimurium LT2). Replicate-specific L. innocua and Salmonella Typhimurium reductions were calculated as log CFU per square centimeter of control minus log CFU per square centimeter of enumerated survivors for each site. For both organisms, all sanitizer treatments differed from each other, with Cl(-) producing the least reduction and WF the greatest reduction. A significant (P < 0.05) site-by-treatment interaction was observed. The results of the study indicate that quaternary ammonium chloride sanitizers (600 ppm) applied by both WF and DF were more effective at reducing L. innocua and Salmonella Typhimurium than a traditional Cl sanitizer (200 ppm) on unwashed slicer surfaces.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Surrogate Measurements of Actinide (n,2n) Cross Sections with NeutronSTARS

    Energy Technology Data Exchange (ETDEWEB)

    Casperson, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Burke, J. T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hughes, R. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Akindele, O. A. [Univ. of California, Berkeley, CA (United States); Koglin, J. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wang, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tamashiro, A. [Oregon State Univ., Corvallis, OR (United States)

    2016-09-27

    Directly measuring (n,2n) cross sections on short-lived actinides presents a number of experimental challenges. The surrogate reaction technique is an experimental method for measuring cross sections on short-­lived isotopes, and it provides a unique solution for measuring (n,2n) cross sections. This technique involves measuring a charged-­particle reaction cross section, where the reaction populates the same compound nucleus as the reaction of interest. To perform these surrogate (n,2n) cross section measurements, a silicon telescope array has been placed along a beam line at the Texas A&M University Cyclotron Institute, which is surrounded by a large tank of gadolinium-doped liquid scintillator, which acts as a neutron detector. The combination of the charge-particle and neutron-detector arrays is referred to as NeutronSTARS. In the analysis procedure for calculating the (n,2n) cross section, the neutron detection efficiency and time structure plays an important role. Due to the lack of availability of isotropic, mono-energetic neutron sources, modeling is an important component in establishing this efficiency and time structure. This report describes the NeutronSTARS array, which was designed and commissioned during this project. It also describes the surrogate reaction technique, specifically referencing a 235U(n,2n) commissioning measurement that was fielded during the past year. Advanced multiplicity analysis techniques have been developed for this work, which should allow for efficient analysis of 241Pu(n,2n) and 239Pu(n,2n) cross section measurements

  2. 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.

  3. 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.

  4. 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.

  5. Use of aerobic spores as a surrogate for cryptosporidium oocysts in drinking water supplies.

    Science.gov (United States)

    Headd, Brendan; Bradford, Scott A

    2016-03-01

    Waterborne illnesses are a growing concern among health and regulatory agencies worldwide. The United States Environmental Protection Agency has established several rules to combat the contamination of water supplies by cryptosporidium oocysts, however, the detection and study of cryptosporidium oocysts is hampered by methodological and financial constraints. As a result, numerous surrogates for cryptosporidium oocysts have been proposed by the scientific community and efforts are underway to evaluate many of the proposed surrogates. The purpose of this review is to evaluate the suitability of aerobic bacterial spores to serve as a surrogate for cryptosporidium oocysts in identifying contaminated drinking waters. To accomplish this we present a comparison of the biology and life cycles of aerobic spores and oocysts and compare their physical properties. An analysis of their surface properties is presented along with a review of the literature in regards to the transport, survival, and prevalence of aerobic spores and oocysts in the saturated subsurface environment. Aerobic spores and oocysts share many commonalities with regard to biology and survivability, and the environmental prevalence and ease of detection make aerobic spores a promising surrogate for cryptosporidium oocysts in surface and groundwater. However, the long-term transport and release of aerobic spores still needs to be further studied, and compared with available oocyst information. In addition, the surface properties and environmental interactions of spores are known to be highly dependent on the spore taxa and purification procedures, and additional research is needed to address these issues in the context of transport. Published by Elsevier Ltd.

  6. 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.

  7. Surrogate mother ? praiseworthy or stigmatized: a qualitative study on perceptions of surrogacy in Assam, India

    OpenAIRE

    Arvidsson, Anna; Vauquline, Polly; Johnsdotter, Sara; Ess?n, Birgitta

    2017-01-01

    ABSTRACT Background: Surrogacy is a reproductive practice that has been strongly marketed in India as a solution for childless couples. As a result, the number of surrogacy clinics is increasing. Meanwhile, a global discourse on surrogacy, originating from a Western perspective, has characterized surrogacy as being exploitative of women in low-income settings, where poverty drives them to become surrogate mothers. Objective: This study explored perspectives on surrogacy from men and women in ...

  8. 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.

  9. 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...

  10. 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...

  11. Comparative Analysis of the Main Business Intelligence Solutions

    OpenAIRE

    Alexandra RUSANEANU

    2013-01-01

    Nowadays, Business Intelligence solutions are the main tools for analyzing and monitoring the company’s performance at any organizational level. This paper presents a comparative analysis of the most powerful Business Intelligence solutions using a set of technical features such as infrastructure of the platform, development facilities, complex analysis tools, interactive dashboards and scorecards, mobile integration and complex implementation of performance management methodologies.

  12. 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 ...

  13. 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.

  14. 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.

  15. Oxidation of Alkane Rich Gasoline Fuels and their Surrogates in a Motored Engine

    KAUST Repository

    Shankar, Vijai S B

    2015-03-30

    The validation of surrogates formulated using a computational framework by Ahmed et al.[1]for two purely paraffinic gasoline fuels labelled FACE A and FACE C was undertaken in this study. The ability of these surrogate mixtures to be used in modelling LTC engines was accessed by comparison of their low temperature oxidation chemistry with that of the respective parent fuel as well as a PRF based on RON. This was done by testing the surrogate mixtures in a modified Cooperative Fuels Research (CFR) engine running in Controlled Autoignition Mode (CAI) mode. The engine was run at a constant speed of 600 rpm at an equivalence ratio of 0.5 with the intake temperature at 150 °C and a pressure of 98 kPa. The low temperature reactivity of the fuels were studied by varying the compression ratio of the engine from the point were very only small low temperature heat release was observed to a point beyond which auto-ignition of the fuel/air mixture occurred. The apparent heat release rates of different fuels was calculated from the pressure histories using first law analysis and the CA 50 times of the low temperature heat release (LTHR) were compared. The surrogates reproduced the cool flame behavior of the parent fuels better than the PRF across all compression ratios.

  16. Oxidation of Alkane Rich Gasoline Fuels and their Surrogates in a Motored Engine

    KAUST Repository

    Shankar, Vijai S B; Al-Qurashi, Khalid; Ahmed, Ahfaz; Atef, Nour; Chung, Suk-Ho; Roberts, William L.; Sarathy, Mani

    2015-01-01

    The validation of surrogates formulated using a computational framework by Ahmed et al.[1]for two purely paraffinic gasoline fuels labelled FACE A and FACE C was undertaken in this study. The ability of these surrogate mixtures to be used in modelling LTC engines was accessed by comparison of their low temperature oxidation chemistry with that of the respective parent fuel as well as a PRF based on RON. This was done by testing the surrogate mixtures in a modified Cooperative Fuels Research (CFR) engine running in Controlled Autoignition Mode (CAI) mode. The engine was run at a constant speed of 600 rpm at an equivalence ratio of 0.5 with the intake temperature at 150 °C and a pressure of 98 kPa. The low temperature reactivity of the fuels were studied by varying the compression ratio of the engine from the point were very only small low temperature heat release was observed to a point beyond which auto-ignition of the fuel/air mixture occurred. The apparent heat release rates of different fuels was calculated from the pressure histories using first law analysis and the CA 50 times of the low temperature heat release (LTHR) were compared. The surrogates reproduced the cool flame behavior of the parent fuels better than the PRF across all compression ratios.

  17. Development of a surrogate model for analysis of ex-vessel steam explosion in Nordic type BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Basso, Simone, E-mail: simoneb@kth.se; Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se

    2016-12-15

    Highlights: • Severe accident. • Steam explosion. • Surrogate model. • Sensitivity study. • Artificial neural networks. - Abstract: Severe accident mitigation strategy adopted in Nordic type Boiling Water Reactors (BWRs) employs ex-vessel core melt cooling in a deep pool of water below reactor vessel. Energetic fuel–coolant interaction (steam explosion) can occur during molten core release into water. Dynamic loads can threaten containment integrity increasing the risk of fission products release to the environment. Comprehensive uncertainty analysis is necessary in order to assess the risks. Computational costs of the existing fuel–coolant interaction (FCI) codes is often prohibitive for addressing the uncertainties, including the effect of stochastic triggering time. This paper discusses development of a computationally efficient surrogate model (SM) for prediction of statistical characteristics of steam explosion impulses in Nordic BWRs. The TEXAS-V code was used as the Full Model (FM) for the calculation of explosion impulses. The surrogate model was developed using artificial neural networks (ANNs) and the database of FM solutions. Statistical analysis was employed in order to treat chaotic response of steam explosion impulse to variations in the triggering time. Details of the FM and SM implementation and their verification are discussed in the paper.

  18. Fifteen years experience with an in-vitro fertilization surrogate gestational pregnancy programme.

    Science.gov (United States)

    Goldfarb, J M; Austin, C; Peskin, B; Lisbona, H; Desai, N; de Mola, J R

    2000-05-01

    The purpose of our study was to review and evaluate retrospectively the experience of an in-vitro fertilization (IVF) surrogate gestational programme in a tertiary care and academic centre. In a 15 year period from 1984 to 1999, a total of 180 cycles of IVF surrogate gestational pregnancy was started in 112 couples. On average, the women were 34.4 +/- 4.4 years of age, had 11.1 +/- 0.72 oocytes obtained per retrieval, 7.1 +/- 0.5 oocytes fertilized and 5. 8 +/- 0.4 embryos subsequently cleaved. Sixteen cycles (8.9%) were cancelled due to poor stimulation. Except for six cycles (3.3%) where there were no embryos available, an average of 3.2 +/- 0.1 embryos was transferred to each individual recipient. The overall pregnancy rate per cycle after IVF surrogacy was 24% (38 of 158), with a clinical pregnancy rate of 19% (30 of 158), and a live birth rate of 15.8% (25 of 158). When compared to patients who underwent a hysterectomy, individuals with congenital absence of the uterus had significantly more oocytes retrieved (P surrogate gestation is an established, yet still controversial, approach to the care of infertile couples. Take-home baby rates are comparable to conventional IVF over the same 15 year span in our programme. Patients with congenital absence of the uterus responded to ovulation induction better than patients who underwent a hysterectomy, perhaps due in part to ovarian compromise from previous surgical procedures.

  19. Surrogacy: outcomes for surrogate mothers, children and the resulting families-a systematic review.

    Science.gov (United States)

    Söderström-Anttila, Viveca; Wennerholm, Ulla-Britt; Loft, Anne; Pinborg, Anja; Aittomäki, Kristiina; Romundstad, Liv Bente; Bergh, Christina

    2016-01-01

    Surrogacy is a highly debated method mainly used for treating women with infertility caused by uterine factors. This systematic review summarizes current levels of knowledge of the obstetric, medical and psychological outcomes for the surrogate mothers, the intended parents and children born as a result of surrogacy. PubMed, Cochrane and Embase databases up to February 2015 were searched. Cohort studies and case series were included. Original studies published in English and the Scandinavian languages were included. In case of double publications, the latest study was included. Abstracts only and case reports were excluded. Studies with a control group and case series (more than three cases) were included. Cohort studies, but not case series, were assessed for methodological quality, in terms of risk of bias. We examined a variety of main outcomes for the surrogate mothers, children and intended mothers, including obstetric outcome, relationship between surrogate mother and intended couple, surrogate's experiences after relinquishing the child, preterm birth, low birthweight, birth defects, perinatal mortality, child psychological development, parent-child relationship, and disclosure to the child. The search returned 1795 articles of which 55 met the inclusion criteria. The medical outcome for the children was satisfactory and comparable to previous results for children conceived after fresh IVF and oocyte donation. The rate of multiple pregnancies was 2.6-75.0%. Preterm birth rate in singletons varied between 0 and 11.5% and low birthweight occurred in between 0 and 11.1% of cases. At the age of 10 years there were no major psychological differences between children born after surrogacy and children born after other types of assisted reproductive technology (ART) or after natural conception. The obstetric outcomes for the surrogate mothers were mainly reported from case series. Hypertensive disorders in pregnancy were reported in between 3.2 and 10% of cases and

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. Divergent rules for pollen and nectar foraging bumblebees--a laboratory study with artificial flowers offering diluted nectar substitute and pollen surrogate.

    Directory of Open Access Journals (Sweden)

    Sabine Konzmann

    Full Text Available Almost all bees collect nectar and pollen from flowers. Female bees collect pollen to provision their nest cells, whereas they use nectar for individual energy supply and nest cell provisioning. Bees fine-tune nectar foraging to the amount and to the concentration of nectar, but the individual bees' response to variability of amount and concentration of pollen reward has not yet been studied thoroughly in laboratory settings. We developed an experimental set-up in which bumblebees simultaneously collected sugar solution and pollen from artificial flowers; natural pollen was mixed with cellulose powder or glass powder as a pollen surrogate. Here we show that bumblebee (Bombus terrestris workers do not specialise in nectar or pollen collection, but regularly collect both rewards on the same day. When offered a fixed pollen reward and varied amounts and concentrations of sugar solution, the bumblebees fine-tuned sugar solution foraging dependent on both the volume and concentration, with strong preferences for the highest concentration and the greatest volume. In the reciprocal tests, when offered a fixed sugar reward and varied amounts and concentrations of pollen mixed with a nutrient-free pollen surrogate, the bumblebees follow more an all-or-none rule for pollen, accepting all amounts and concentrations except pure surrogate. It is discussed how the bumblebees' ability to sense sugar, and their apparent inability to sense the pollen protein content, shaped their foraging behaviour. It is argued that the rarity of nectar mimicry and the frequency of pollen mimicry in natural flowers might be interpreted in the context of divergent abilities of nectar and pollen recognition in bees.

  5. The Biomarker-Surrogacy Evaluation Schema: a review of the biomarker-surrogate literature and a proposal for a criterion-based, quantitative, multidimensional hierarchical levels of evidence schema for evaluating the status of biomarkers as surrogate endpoints.

    Science.gov (United States)

    Lassere, Marissa N

    2008-06-01

    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. Section 2 is a systematic, historical review of the biomarker-surrogate endpoint literature with special reference to the nomenclature, the systems of classification and statistical methods developed for their evaluation. In Section 3 an explicit, criterion-based, quantitative, multidimensional hierarchical levels of evidence schema - Biomarker-Surrogacy Evaluation Schema - is proposed to evaluate and co-ordinate the multiple dimensions (biological, epidemiological, statistical, clinical trial and risk-benefit evidence) of the biomarker clinical endpoint relationships. The schema systematically evaluates and ranks the surrogacy status of biomarkers and surrogate endpoints using defined levels of evidence. The schema incorporates the three independent domains: Study Design, Target Outcome and Statistical Evaluation. Each domain has items ranked from zero to five. An additional category called Penalties incorporates additional considerations of biological plausibility, risk-benefit and generalizability. The total score (0-15) determines the level of evidence, with Level 1 the strongest and Level 5 the weakest. The term ;surrogate' is restricted to markers attaining Levels 1 or 2 only. Surrogacy status of markers can then be directly compared within and across different areas of medicine to guide individual, trial-based or drug-development decisions. This schema would facilitate communication between clinical, researcher, regulatory, industry and consumer participants necessary for evaluation of the biomarker-surrogate-clinical endpoint relationship in their different settings.

  6. Racial Differences in Outcomes of an Advance Care Planning Intervention for Dialysis Patients and Their Surrogates.

    Science.gov (United States)

    Song, Mi-Kyung; Ward, Sandra E; Lin, Feng-Chang; Hamilton, Jill B; Hanson, Laura C; Hladik, Gerald A; Fine, Jason P

    2016-02-01

    African Americans' beliefs about end-of-life care may differ from those of whites, but racial differences in advance care planning (ACP) outcomes are unknown. The aim of this study was to compare the efficacy of an ACP intervention on preparation for end-of-life decision making and post-bereavement outcomes for African Americans and whites on dialysis. A secondary analysis of data from a randomized trial comparing an ACP intervention (Sharing Patient's Illness Representations to Increase Trust [SPIRIT]) with usual care was conducted. There were 420 participants, 210 patient-surrogate dyads (67.4% African Americans), recruited from 20 dialysis centers in North Carolina. The outcomes of preparation for end-of-life decision making included dyad congruence on goals of care, surrogate decision-making confidence, a composite of the two, and patient decisional conflict assessed at 2, 6, and 12 months post-intervention. Surrogate bereavement outcomes included anxiety, depression, and post-traumatic distress symptoms assessed at 2 weeks, and at 3 and 6 months after the patient's death. SPIRIT was superior to usual care in improving dyad congruence (odds ration [OR] = 2.31, p = 0.018), surrogate decision-making confidence (β = 0.18, p = 0.021), and the composite (OR = 2.19, p = 0.028) 2 months post-intervention, but only for African Americans. SPIRIT reduced patient decisional conflict at 6 months for whites and at 12 months for African Americans. Finally, SPIRIT was superior to usual care in reducing surrogates' bereavement depressive symptoms for African Americans but not for whites (β = -3.49, p = 0.003). SPIRIT was effective in improving preparation for end-of-life decision-making and post-bereavement outcomes in African Americans.

  7. 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.

  8. 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 ...

  9. 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.

  10. 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.

  11. Optimum radii and heights of U-shaped baffles in a square duct heat exchanger using surrogate-assisted optimization

    Directory of Open Access Journals (Sweden)

    Kittinan Wansasueb

    2017-06-01

    Full Text Available In this paper, optimum U-shaped baffles in a square channel heat exchanger using air as a working fluid were developed using surrogate-assisted optimization. The design problem is set to maximize heat transfer performance and simultaneously minimize pressure loss across the channel. Design variables determine the radii and heights of the baffles, whereas the optimization problem is treated as box-constrained optimization. The work in this paper is aimed at finding an appropriate surrogate model for designing such a heat exchanger system. Function evaluations are performed by means of computational fluid dynamics (CFD. The computations are based on the finite volume method and are carried out at a Reynolds number of 4000. It has been found that the use of U-shaped baffles as heat transfer enhancement devices improves the thermal performance of the heat exchanger. Comparative results reveal that the Kriging model is the most accurate surrogate model, however, the surrogate model giving the best result is support vector regression.

  12. 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.

  13. Partitioning of polychlorinated biphenyls into human cells and adipose tissues: evaluation of octanol, triolein, and liposomes as surrogates.

    Science.gov (United States)

    Quinn, Cristina L; van der Heijden, Stephan A; Wania, Frank; Jonker, Michiel T O

    2014-05-20

    Whereas octanol, triacylglycerides, and liposomes have all been proposed as surrogates for measuring the affinity of hydrophobic organic contaminants to human lipids, no comparative evaluation of their suitability exists. Here we conducted batch sorption experiments with polyoxymethylene passive samplers to determine the partition coefficients at 37 °C of 18 polychlorinated biphenyls (PCBs) from water into (i) triolein (Ktriolein/water), (ii) eight types of liposomes (Kliposome/water), (iii) human abdominal fat tissues (KAFT/water) from seven individuals, and (iv) human MCF-7 cells cultured in vitro (Kcell/water). Differences between KAFT/water among individuals and between Kliposome/water among liposome types were very small and not correlated to structural attributes of the PCBs. Similarly, the length and degree of saturation of the phospholipid carbon chains, the headgroup, and the composition of the liposome did not affect the partitioning of PCBs into the studied liposomes. Whereas Kliposome/water values were similar to literature values of Koctanol/water adjusted to 37 °C, they both were lower than KAFT/water and Kcell/water by a factor of 3 on average. Partitioning of PCBs into triolein on the other hand closely mimicked that into human lipids, for which triolein is thus a better surrogate than either octanol or liposomes. Previously published polyparameter linear free energy relationships for partitioning from water into storage lipids and liposomes predicted the measured partition coefficients with a root-mean-square error of less than 0.15 log units, if the chosen equations and solute descriptors do not allow chlorine substitution in the ortho-position to influence the prediction. By guiding the selection of (i) a surrogate for the experimental determination and (ii) a method for the prediction of partitioning into human lipids, this study contributes to a better assessment of hydrophobic organic contaminant bioaccumulation in humans.

  14. 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.

  15. 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.

  16. Quantitative GPCR and ion channel transcriptomics in primary alveolar macrophages and macrophage surrogates

    Directory of Open Access Journals (Sweden)

    Groot-Kormelink Paul J

    2012-10-01

    Full Text Available Abstract Background Alveolar macrophages are one of the first lines of defence against invading pathogens and play a central role in modulating both the innate and acquired immune systems. By responding to endogenous stimuli within the lung, alveolar macrophages contribute towards the regulation of the local inflammatory microenvironment, the initiation of wound healing and the pathogenesis of viral and bacterial infections. Despite the availability of protocols for isolating primary alveolar macrophages from the lung these cells remain recalcitrant to expansion in-vitro and therefore surrogate cell types, such as monocyte derived macrophages and phorbol ester-differentiated cell lines (e.g. U937, THP-1, HL60 are frequently used to model macrophage function. Methods The availability of high throughput gene expression technologies for accurate quantification of transcript levels enables the re-evaluation of these surrogate cell types for use as cellular models of the alveolar macrophage. Utilising high-throughput TaqMan arrays and focussing on dynamically regulated families of integral membrane proteins, we explore the similarities and differences in G-protein coupled receptor (GPCR and ion channel expression in alveolar macrophages and their widely used surrogates. Results The complete non-sensory GPCR and ion channel transcriptome is described for primary alveolar macrophages and macrophage surrogates. The expression of numerous GPCRs and ion channels whose expression were hitherto not described in human alveolar macrophages are compared across primary macrophages and commonly used macrophage cell models. Several membrane proteins known to have critical roles in regulating macrophage function, including CXCR6, CCR8 and TRPV4, were found to be highly expressed in macrophages but not expressed in PMA-differentiated surrogates. Conclusions The data described in this report provides insight into the appropriate choice of cell models for

  17. In vivo comparison of two human norovirus surrogates for testing ethanol-based handrubs: the mouse chasing the cat!

    Directory of Open Access Journals (Sweden)

    Syed A Sattar

    Full Text Available Human noroviruses (HuNoV, a major cause of acute gastroenteritis worldwide, cannot be readily cultured in the lab. Therefore, a feline calicivirus (FCV is often used as its surrogate to, among other things, test alcohol-based handrubs (ABHR. The more recent laboratory culture of a mouse norovirus (MNV provides an alternative. While MNV is closer to HuNoV in several respects, to date, no comparative testing of FCV and MNV survival and inactivation on human hands has been performed. This study was designed to address the knowledge gap. The rates of loss in viability during drying on hands were -1.91 and -1.65% per minute for FCV and MNV, respectively. When the contaminated skin was exposed for 20 s to either a commercial ABHR with 62% (v/v ethanol or to 75% (v/v ethanol in water, FCV infectivity was reduced by 3.5 log₁₀ by the commercial ABHR while 75% ethanol did not show any noticeable improvement in activity as compared to the 20 s contact. An 80% (v/v aqueous solution of ethanol gave only a 1.75 log₁₀ reduction in MNV activity after 20 s. The results show significant differences in the ethanol susceptibility of FCV and MNV in contact times relevant to field use of ABHR and also that 62% ethanol was a more effective virucide than either 75% or 80% ethanol. These findings indicate the need for a review of the continuing use of FCV as a surrogate for HuNoV.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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

  3. The Problem of Unenforceable Surrogacy Contracts: Can Unjust Enrichment Provide a Solution?

    Science.gov (United States)

    Purshouse, Craig; Bracegirdle, Kate

    2018-02-07

    The fact that surrogacy contracts are unenforceable can cause problems if a surrogate decides that she wishes to keep the child. When this happens, the intended parents cannot bring a claim in contract compelling her to give the baby up to them or even for the return of money paid to the surrogate. Intuitively, it appears unfair that the surrogate can keep the child and the money while the intended parents are left with nothing. However, enforcing such contracts could be oppressive to the surrogate and detrimental to the child's welfare. In this article, we consider whether the law unjust enrichment will allow for the return of money paid under such contracts. We argue that this branch of the law can provide a solution to the problem of unenforceable surrogacy contracts that strikes a fair balance between the interests of the surrogate and intended parents while also placing the child's lifelong welfare paramount. © The Author(s) 2018. Published by Oxford University Press; All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. 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

  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. 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...

  7. 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.

  8. 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

  9. 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.

  10. 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.)

  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. Optimal design of hydraulic excavator working device based on multiple surrogate models

    Directory of Open Access Journals (Sweden)

    Qingying Qiu

    2016-05-01

    Full Text Available The optimal design of hydraulic excavator working device is often characterized by computationally expensive analysis methods such as finite element analysis. Significant difficulties also exist when using a sensitivity-based decomposition approach to such practical engineering problems because explicit mathematical formulas between the objective function and design variables are impossible to formulate. An effective alternative is known as the surrogate model. The purpose of this article is to provide a comparative study on multiple surrogate models, including the response surface methodology, Kriging, radial basis function, and support vector machine, and select the one that best fits the optimization of the working device. In this article, a new modeling strategy based on the combination of the dimension variables between hinge joints and the forces loaded on hinge joints of the working device is proposed. In addition, the extent to which the accuracy of the surrogate models depends on different design variables is presented. The bionic intelligent optimization algorithm is then used to obtain the optimal results, which demonstrate that the maximum stresses calculated by the predicted method and finite element analysis are quite similar, but the efficiency of the former is much higher than that of the latter.

  13. Benchmarking the x-ray phase contrast imaging for ICF DT ice characterization using roughened surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Dewald, E; Kozioziemski, B; Moody, J; Koch, J; Mapoles, E; Montesanti, R; Youngblood, K; Letts, S; Nikroo, A; Sater, J; Atherton, J

    2008-06-26

    We use x-ray phase contrast imaging to characterize the inner surface roughness of DT ice layers in capsules planned for future ignition experiments. It is therefore important to quantify how well the x-ray data correlates with the actual ice roughness. We benchmarked the accuracy of our system using surrogates with fabricated roughness characterized with high precision standard techniques. Cylindrical artifacts with azimuthally uniform sinusoidal perturbations with 100 um period and 1 um amplitude demonstrated 0.02 um accuracy limited by the resolution of the imager and the source size of our phase contrast system. Spherical surrogates with random roughness close to that required for the DT ice for a successful ignition experiment were used to correlate the actual surface roughness to that obtained from the x-ray measurements. When comparing average power spectra of individual measurements, the accuracy mode number limits of the x-ray phase contrast system benchmarked against surface characterization performed by Atomic Force Microscopy are 60 and 90 for surrogates smoother and rougher than the required roughness for the ice. These agreement mode number limits are >100 when comparing matching individual measurements. We will discuss the implications for interpreting DT ice roughness data derived from phase-contrast x-ray imaging.

  14. 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."

  15. Practical surrogate marker of pulmonary dysanapsis by simple spirometry: an observational case-control study in primary care.

    Science.gov (United States)

    Shiota, Satomi; Ichikawa, Masako; Suzuki, Kazuhiro; Fukuchi, Yoshinosuke; Takahashi, Kazuhisa

    2015-03-26

    We see patients who present with spirometry airflow limitation despite their forced expiratory volume in one second (FEV1) as well as forced vital capacity (FVC) to be supernormal (FEV1/FVC spirometry conditions (results measured with spirometry) could be suitably used as a practical surrogate marker of pulmonary dysanapsis: the condition of disproportionate but physiologically normal growth between airways and lung parenchyma. We compared the conventional surrogate marker of dysanapsis, maximum mid-expiratory flow to FVC (MMF/FVC), in SUBJECTS (FEV1/FVC spirometry results with SUBJECTS) (n = 55), and in CONTROLS (age- and height- matched, normal spirometry results) (n = 25). Next we added imaging analysis to evaluate the relationship between the cross sectional airway luminal area (X-Ai) and the lung volume results among the three groups. The MMF/FVC was significantly lower in SUBJECTS and in EMPHYSEMA compared to CONTROLS. However, percent predicted peak expiratory flow (%PEFR) was significantly lower only in SUBJECTS and not in EMPHYSEMA compared to CONTROLS. The ratio of the X-Ai of the trachea and right apical bronchus to lung volume was significantly lower in SUBJECTS compared to CONTROLS. The simple spirometry conditions in SUBJECTS are highly suggestive of practical surrogate marker of pulmonary dysanapsis. Awareness of this concept would help to attenuate the risk of overdiagnosis of obstructive pulmonary disease.

  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. 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

  18. [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?

  19. 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

  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. 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.

  2. 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

  3. Real-time tumor motion estimation using respiratory surrogate via memory-based learning

    International Nuclear Information System (INIS)

    Li Ruijiang; Xing Lei; Lewis, John H; Berbeco, Ross I

    2012-01-01

    th percentile error of 3.4 mm on unseen test data. The average 3D error was further reduced to 1.4 mm when the model was tuned to its optimal setting for each respiratory trace. In one trace where a few outliers are present in the training data, the proposed method achieved an error reduction of as much as ∼50% compared with the best linear model (1.0 mm versus 2.1 mm). The memory-based learning technique is able to accurately capture the highly complex and nonlinear relations between tumor and surrogate motion in an efficient manner (a few milliseconds per estimate). Furthermore, the algorithm is particularly suitable to handle situations where the training data are contaminated by large errors or outliers. These desirable properties make it an ideal candidate for accurate and robust tumor gating/tracking using respiratory surrogates. (paper)

  4. Real-time tumor motion estimation using respiratory surrogate via memory-based learning

    Science.gov (United States)

    Li, Ruijiang; Lewis, John H.; Berbeco, Ross I.; Xing, Lei

    2012-08-01

    th percentile error of 3.4 mm on unseen test data. The average 3D error was further reduced to 1.4 mm when the model was tuned to its optimal setting for each respiratory trace. In one trace where a few outliers are present in the training data, the proposed method achieved an error reduction of as much as ∼50% compared with the best linear model (1.0 mm versus 2.1 mm). The memory-based learning technique is able to accurately capture the highly complex and nonlinear relations between tumor and surrogate motion in an efficient manner (a few milliseconds per estimate). Furthermore, the algorithm is particularly suitable to handle situations where the training data are contaminated by large errors or outliers. These desirable properties make it an ideal candidate for accurate and robust tumor gating/tracking using respiratory surrogates.

  5. Comparative solution and solid-phase glycosylations toward a disaccharide library

    DEFF Research Database (Denmark)

    Agoston, K.; Kröger, Lars; Agoston, Agnes

    2009-01-01

    A comparative study on solution-phase and solid-phase oligosaccharide synthesis was performed. A 16-member library containing all regioisomers of Glc-Glc, Glc-Gal, Gal-Glc, and Gal-Gal disaccharides was synthesized both in solution and on solid phase. The various reaction conditions for different...

  6. A Non-Parametric Surrogate-based Test of Significance for T-Wave Alternans Detection

    Science.gov (United States)

    Nemati, Shamim; Abdala, Omar; Bazán, Violeta; Yim-Yeh, Susie; Malhotra, Atul; Clifford, Gari

    2010-01-01

    We present a non-parametric adaptive surrogate test that allows for the differentiation of statistically significant T-Wave Alternans (TWA) from alternating patterns that can be solely explained by the statistics of noise. The proposed test is based on estimating the distribution of noise induced alternating patterns in a beat sequence from a set of surrogate data derived from repeated reshuffling of the original beat sequence. Thus, in assessing the significance of the observed alternating patterns in the data no assumptions are made about the underlying noise distribution. In addition, since the distribution of noise-induced alternans magnitudes is calculated separately for each sequence of beats within the analysis window, the method is robust to data non-stationarities in both noise and TWA. The proposed surrogate method for rejecting noise was compared to the standard noise rejection methods used with the Spectral Method (SM) and the Modified Moving Average (MMA) techniques. Using a previously described realistic multi-lead model of TWA, and real physiological noise, we demonstrate the proposed approach reduces false TWA detections, while maintaining a lower missed TWA detection compared with all the other methods tested. A simple averaging-based TWA estimation algorithm was coupled with the surrogate significance testing and was evaluated on three public databases; the Normal Sinus Rhythm Database (NRSDB), the Chronic Heart Failure Database (CHFDB) and the Sudden Cardiac Death Database (SCDDB). Differences in TWA amplitudes between each database were evaluated at matched heart rate (HR) intervals from 40 to 120 beats per minute (BPM). Using the two-sample Kolmogorov-Smirnov test, we found that significant differences in TWA levels exist between each patient group at all decades of heart rates. The most marked difference was generally found at higher heart rates, and the new technique resulted in a larger margin of separability between patient populations than

  7. 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...

  8. Ovulation Statuses of Surrogate Gilts Are Associated with the Efficiency of Excellent Pig Cloning.

    Science.gov (United States)

    Huan, Yanjun; Hu, Kui; Xie, Bingteng; Shi, Yongqian; Wang, Feng; Zhou, Yang; Liu, Shichao; Huang, Bo; Zhu, Jiang; Liu, Zhongfeng; He, Yilong; Li, Jingyu; Kong, Qingran; Liu, Zhonghua

    2015-01-01

    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 (Pcloning efficiency (Pcloning 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 (Pcloning efficiency of excellent pigs, and follicle puncture, not transfer position change, improved cloning efficiency. This work would have important implications in preserving and breeding excellent livestock and improving the overall cloning efficiency.

  9. Computational benefits using artificial intelligent methodologies for the solution of an environmental design problem: saltwater intrusion.

    Science.gov (United States)

    Papadopoulou, Maria P; Nikolos, Ioannis K; Karatzas, George P

    2010-01-01

    Artificial Neural Networks (ANNs) comprise a powerful tool to approximate the complicated behavior and response of physical systems allowing considerable reduction in computation time during time-consuming optimization runs. In this work, a Radial Basis Function Artificial Neural Network (RBFN) is combined with a Differential Evolution (DE) algorithm to solve a water resources management problem, using an optimization procedure. The objective of the optimization scheme is to cover the daily water demand on the coastal aquifer east of the city of Heraklion, Crete, without reducing the subsurface water quality due to seawater intrusion. The RBFN is utilized as an on-line surrogate model to approximate the behavior of the aquifer and to replace some of the costly evaluations of an accurate numerical simulation model which solves the subsurface water flow differential equations. The RBFN is used as a local approximation model in such a way as to maintain the robustness of the DE algorithm. The results of this procedure are compared to the corresponding results obtained by using the Simplex method and by using the DE procedure without the surrogate model. As it is demonstrated, the use of the surrogate model accelerates the convergence of the DE optimization procedure and additionally provides a better solution at the same number of exact evaluations, compared to the original DE algorithm.

  10. 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.

  11. 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.

  12. 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....

  13. 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

  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. Advance care planning and end-of-life decision making in dialysis: a randomized controlled trial targeting patients and their surrogates.

    Science.gov (United States)

    Song, Mi-Kyung; Ward, Sandra E; Fine, Jason P; Hanson, Laura C; Lin, Feng-Chang; Hladik, Gerald A; Hamilton, Jill B; Bridgman, Jessica C

    2015-11-01

    Few trials have examined long-term outcomes of advance care planning (ACP) interventions. We examined the efficacy of an ACP intervention on preparation for end-of-life decision making for dialysis patients and surrogates and for surrogates' bereavement outcomes. A randomized trial compared an ACP intervention (Sharing Patient's Illness Representations to Increase Trust [SPIRIT]) to usual care alone, with blinded outcome assessments. 420 participants (210 dyads of prevalent dialysis patients and their surrogates) from 20 dialysis centers. Every dyad received usual care. Those randomly assigned to SPIRIT had an in-depth ACP discussion at the center and a follow-up session at home 2 weeks later. preparation for end-of-life decision making, assessed for 12 months, included dyad congruence on goals of care at end of life, patient decisional conflict, surrogate decision-making confidence, and a composite of congruence and surrogate decision-making confidence. bereavement outcomes, assessed for 6 months, included anxiety, depression, and posttraumatic distress symptoms completed by surrogates after patient death. adjusting for time and baseline values, dyad congruence (OR, 1.89; 95% CI, 1.1-3.3), surrogate decision-making confidence (β=0.13; 95% CI, 0.01-0.24), and the composite (OR, 1.82; 95% CI, 1.0-3.2) were better in SPIRIT than controls, but patient decisional conflict did not differ between groups (β=-0.01; 95% CI, -0.12 to 0.10). 45 patients died during the study. Surrogates in SPIRIT had less anxiety (β=-1.13; 95% CI, -2.23 to -0.03), depression (β=-2.54; 95% CI, -4.34 to -0.74), and posttraumatic distress (β=-5.75; 95% CI, -10.9 to -0.64) than controls. Study was conducted in a single US region. SPIRIT was associated with improvements in dyad preparation for end-of-life decision making and surrogate bereavement outcomes. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  16. 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.

  17. Quantitative prediction of respiratory tidal volume based on the external torso volume change: a potential volumetric surrogate

    International Nuclear Information System (INIS)

    Li Guang; Arora, Naveen C; Xie Huchen; Ning, Holly; Citrin, Deborah; Kaushal, Aradhana; Zach, Leor; Camphausen, Kevin; Miller, Robert W; Lu Wei; Low, Daniel

    2009-01-01

    An external respiratory surrogate that not only highly correlates with but also quantitatively predicts internal tidal volume should be useful in guiding four-dimensional computed tomography (4DCT), as well as 4D radiation therapy (4DRT). A volumetric surrogate should have advantages over external fiducial point(s) for monitoring respiration-induced motion of the torso, which deforms in synchronization with a patient-specific breathing pattern. This study establishes a linear relationship between the external torso volume change (TVC) and lung air volume change (AVC) by validating a proposed volume conservation hypothesis (TVC = AVC) throughout the respiratory cycle using 4DCT and spirometry. Fourteen patients' torso 4DCT images and corresponding spirometric tidal volumes were acquired to examine this hypothesis. The 4DCT images were acquired using dual surrogates in cine mode and amplitude-based binning in 12 respiratory stages, minimizing residual motion artifacts. Torso and lung volumes were calculated using threshold-based segmentation algorithms and volume changes were calculated relative to the full-exhalation stage. The TVC and AVC, as functions of respiratory stages, were compared, showing a high correlation (r = 0.992 ± 0.005, p 2 = 0.980) without phase shift. The AVC was also compared to the spirometric tidal volumes, showing a similar linearity (slope = 1.030 ± 0.092, R 2 = 0.947). In contrast, the thoracic and abdominal heights measured from 4DCT showed relatively low correlation (0.28 ± 0.44 and 0.82 ± 0.30, respectively) and location-dependent phase shifts. This novel approach establishes the foundation for developing an external volumetric respiratory surrogate.

  18. 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

  19. 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.

  20. 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.

  1. Effective use of integrated hydrological models in basin-scale water resources management: surrogate modeling approaches

    Science.gov (United States)

    Zheng, Y.; Wu, B.; Wu, X.

    2015-12-01

    Integrated hydrological models (IHMs) consider surface water and subsurface water as a unified system, and have been widely adopted in basin-scale water resources studies. However, due to IHMs' mathematical complexity and high computational cost, it is difficult to implement them in an iterative model evaluation process (e.g., Monte Carlo Simulation, simulation-optimization analysis, etc.), which diminishes their applicability for supporting decision-making in real-world situations. Our studies investigated how to effectively use complex IHMs to address real-world water issues via surrogate modeling. Three surrogate modeling approaches were considered, including 1) DYCORS (DYnamic COordinate search using Response Surface models), a well-established response surface-based optimization algorithm; 2) SOIM (Surrogate-based Optimization for Integrated surface water-groundwater Modeling), a response surface-based optimization algorithm that we developed specifically for IHMs; and 3) Probabilistic Collocation Method (PCM), a stochastic response surface approach. Our investigation was based on a modeling case study in the Heihe River Basin (HRB), China's second largest endorheic river basin. The GSFLOW (Coupled Ground-Water and Surface-Water Flow Model) model was employed. Two decision problems were discussed. One is to optimize, both in time and in space, the conjunctive use of surface water and groundwater for agricultural irrigation in the middle HRB region; and the other is to cost-effectively collect hydrological data based on a data-worth evaluation. Overall, our study results highlight the value of incorporating an IHM in making decisions of water resources management and hydrological data collection. An IHM like GSFLOW can provide great flexibility to formulating proper objective functions and constraints for various optimization problems. On the other hand, it has been demonstrated that surrogate modeling approaches can pave the path for such incorporation in real

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. Unwarranted claims of drug efficacy in pharmaceutical sales visits: are drugs approved on the basis of surrogate outcomes promoted appropriately?

    Science.gov (United States)

    Habibi, Roojin; Lexchin, Joel; Mintzes, Barbara; Holbrook, Anne

    2017-11-01

    This study compares physicians' recall of the claims of benefits on cardiovascular disease and diabetes made by pharmaceutical sales representatives for drugs approved on the basis of a surrogate outcome, i.e., an off-label claim, compared with those approved on the basis of a serious morbidity or mortality (clinical) outcome. Physicians in primary care practices in Montreal, Vancouver, Sacramento and Toulouse, who saw sales representatives as part of their usual practice and served a non-referral population, were contacted in blocks of 25 from a randomized list of all physicians practising in the relevant metropolitan area. We compared how frequently physicians reported that sales reps made claims of serious morbidity or mortality (clinically meaningful) benefits for drugs approved on the basis of surrogate outcomes vs. drugs approved on the basis of clinical outcomes. There were 448 promotions for 58 unique brand name cardiovascular and diabetes drugs. Claims of clinically meaningful benefit were reported in 156 (45%) of the 347 promotions for surrogate outcome drugs, constituting unwarranted efficacy claims, i.e., off-label promotion. Claims of clinical benefit were reported in 72 of the 101 promotions (71%) for drugs approved on the basis of clinical outcomes, adjusted OR = 0.3 (95% CI 0.2, 0.6), P sales visit promotions for drugs approved only on the basis of surrogate outcomes extended beyond the regulator-approved efficacy information for the product in almost half of promotions. Unapproved claims of drug efficacy constitute a form of off-label promotion and merit greater attention from regulators. © 2017 The British Pharmacological Society.

  7. 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

  8. 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.

  9. 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)

  10. Characterization of n-heptane as a single component Diesel surrogate fuel. EHPC test set-up implementation

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, M.

    2010-06-15

    The availability of accurately measured fuel properties, during an injection event under engine relevant conditions is critical within the surrogate fuel approach. There is a need to perform in-house measurements in order to validate developed and new models. A well defined and accurately measured data-set will facilitate on-going work for sophisticated engine related in-cylinder combustion modeling. In this work pure n-heptane fuel is used as a single component surrogate fuel and is studied in a high-pressure constant volume optical test set-up. N-heptane is often used as a single component surrogate diesel fuel since it has a comparable Cetane number as European diesel. Detailed chemical-kinetic mechanisms for low-, intermediate-, and high-temperature n-heptane oxidation are available and several models exist that have sufficiently reduced dimensionality (number of species and reactions) to enable their use in CFD (Computational Fluid Mechanics) simulations. This report discusses the route and implementation to perform such an accurate and relevant n-heptane measurement series. The aim is to combine the efforts of earlier presented EHPC (Eindhoven High Pressure Cell) related work and new approaches, into the proposed surrogate fuel measurement series. The following aspects, related to the applied constant volume combustion chamber set-up, are studied and implemented: Extending the operating ranges towards relevant engine conditions; Study the accuracy and sensitivities of the different measurement steps; Implementing different optical diagnostic principles; and Implement a standardized and robust post processing routine. The different optical diagnostic principles used in this work are: high-speed Schlieren, Mie scattering and beginnings are made to implement a simultaneous LII LIF (Laser Induced Incandescence - Laser Induced Fluorescence) set-up using a new ICCD (Intensified Charge Coupled Device) camera with dual imaging feature. Combining the different

  11. Occupant kinematics of the Hybrid III, THOR-M, and postmortem human surrogates under various restraint conditions in full-scale frontal sled tests.

    Science.gov (United States)

    Albert, Devon L; Beeman, Stephanie M; Kemper, Andrew R

    2018-02-28

    The objective of this research was to compare the occupant kinematics of the Hybrid III (HIII), THOR-M, and postmortem human surrogates (PMHS) during full-scale frontal sled tests under 3 safety restraint conditions: knee bolster (KB), knee bolster and steering wheel airbag (KB/SWAB), and knee bolster airbag and steering wheel airbag (KBAB/SWAB). A total of 20 frontal sled tests were performed with at least 2 tests performed per restraint condition per surrogate. The tests were designed to match the 2012 Toyota Camry New Car Assessment Program (NCAP) full-scale crash test. Rigid polyurethane foam surrogates with compressive strength ratings of 65 and 19 psi were used to simulate the KB and KBAB, respectively. The excursions of the head, shoulders, hips, knees, and ankles were collected using motion capture. Linear acceleration and angular velocity data were also collected from the head, thorax, and pelvis of each surrogate. Time histories were compared between surrogates and restraint conditions using ISO/TS 18571. All surrogates showed some degree of sensitivity to changes in restraint condition. For example, the use of a KBAB decreased the pelvis accelerations and the forward excursions of the knees and hips for all surrogates. However, these trends were not observed for the thorax, shoulders, and head, which showed more sensitivity to the presence of a SWAB. The average scores computed using ISO/TS 18571 for the HIII/PMHS and THOR-M/PMHS comparisons were 0.527 and 0.518, respectively. The HIII had slightly higher scores than the THOR-M for the excursions (HIII average = 0.574; THOR average = 0.520). However, the THOR-M had slightly higher scores for the accelerations and angular rates (HIII average = 0.471; THOR average = 0.516). The data from the current study showed that both KBABs and SWABs affected the kinematics of all surrogates during frontal sled tests. The results of the objective rating analysis indicated that the HIII and THOR-M had comparable

  12. Quantitative prediction of respiratory tidal volume based on the external torso volume change: a potential volumetric surrogate

    Energy Technology Data Exchange (ETDEWEB)

    Li Guang; Arora, Naveen C; Xie Huchen; Ning, Holly; Citrin, Deborah; Kaushal, Aradhana; Zach, Leor; Camphausen, Kevin; Miller, Robert W [Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Lu Wei; Low, Daniel [Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO 63110 (United States)], E-mail: ligeorge@mail.nih.gov

    2009-04-07

    An external respiratory surrogate that not only highly correlates with but also quantitatively predicts internal tidal volume should be useful in guiding four-dimensional computed tomography (4DCT), as well as 4D radiation therapy (4DRT). A volumetric surrogate should have advantages over external fiducial point(s) for monitoring respiration-induced motion of the torso, which deforms in synchronization with a patient-specific breathing pattern. This study establishes a linear relationship between the external torso volume change (TVC) and lung air volume change (AVC) by validating a proposed volume conservation hypothesis (TVC = AVC) throughout the respiratory cycle using 4DCT and spirometry. Fourteen patients' torso 4DCT images and corresponding spirometric tidal volumes were acquired to examine this hypothesis. The 4DCT images were acquired using dual surrogates in cine mode and amplitude-based binning in 12 respiratory stages, minimizing residual motion artifacts. Torso and lung volumes were calculated using threshold-based segmentation algorithms and volume changes were calculated relative to the full-exhalation stage. The TVC and AVC, as functions of respiratory stages, were compared, showing a high correlation (r = 0.992 {+-} 0.005, p < 0.0001) as well as a linear relationship (slope = 1.027 {+-} 0.061, R{sup 2} = 0.980) without phase shift. The AVC was also compared to the spirometric tidal volumes, showing a similar linearity (slope = 1.030 {+-} 0.092, R{sup 2} = 0.947). In contrast, the thoracic and abdominal heights measured from 4DCT showed relatively low correlation (0.28 {+-} 0.44 and 0.82 {+-} 0.30, respectively) and location-dependent phase shifts. This novel approach establishes the foundation for developing an external volumetric respiratory surrogate.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Decomposition Technology Development of Organic Component in a Decontamination Waste Solution

    International Nuclear Information System (INIS)

    Jung, Chong Hun; Oh, W. Z.; Won, H. J.; Choi, W. K.; Kim, G. N.; Moon, J. K.

    2007-11-01

    Through the project of 'Decomposition Technology Development of Organic Component in a Decontamination Waste Solution', the followings were studied. 1. Investigation of decontamination characteristics of chemical decontamination process 2. Analysis of COD, ferrous ion concentration, hydrogen peroxide concentration 3. Decomposition tests of hardly decomposable organic compounds 4. Improvement of organic acid decomposition process by ultrasonic wave and UV light 5. Optimization of decomposition process using a surrogate decontamination waste solution

  18. 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

  19. 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...

  20. 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.

  1. 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

  2. Effects of weaning by surrogate mothers (ACI) on tumor development in SD rats treated with methylnitrosourea (MNU) and/or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).

    Science.gov (United States)

    Shiraki, Katsuhisa; Lu, Huimei; Ishimura, Yoshimasa; Kashiwabara, Shoji; Uesaka, Toshihiro; Katoh, Osamu; Watanabe, Hiromitsu

    2002-09-01

    In this experiment, methylnitrosourea (MNU) was administered, followed by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), to assess effects of surrogate mothering on tumor. One or two day old male SD pups were treated with or without 30 mg/kg body weight of MNU and nursed by SD or ACI surrogate mothers for 5 weeks. When 6-weeks-old they were then treated with 100 ppm MNNG or tap water for 16 weeks. The tumor incidence in the MNNG alone group was significantly lower than with MNU alone or MNU+MNNG (p surrogate mothers after treatment with MNU was increased as compared with the SD mother group. Cumulative development of tumors in the ACI surrogate mother group was also delayed (p mother's milk.

  3. 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.

  4. 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.

  5. The Trial of Ascertaining Individual Preferences for Loved Ones' Role in End-of-Life Decisions (TAILORED) Study: A Randomized Controlled Trial to Improve Surrogate Decision Making.

    Science.gov (United States)

    Sulmasy, Daniel P; Hughes, Mark T; Yenokyan, Gayane; Kub, Joan; Terry, Peter B; Astrow, Alan B; Johnson, Julie A; Ho, Grace; Nolan, Marie T

    2017-10-01

    Patients with terminal illnesses often require surrogate decision makers. Prior research has demonstrated high surrogate stress, and that despite standards promoting substituted judgment, most patients do not want their surrogates to make pure substituted judgments for them. It is not known how best to help loved ones fulfill the surrogate role. To test the effectiveness of an intervention to help surrogate decision makers. One hundred sixty-six patients (41% with amyotrophic lateral sclerosis and 59% with gastrointestinal cancers) and their surrogates at two university medical centers were randomized to an intensive nurse-directed discussion of the end-of-life decision control preferences of the patient (TAILORED) or a discussion of nutrition (CONTROL); 163 completed baseline interviews and underwent the intervention. Twelve patients died during follow-up and 137 dyads completed the study. Post-intervention, using all available data, TAILORED patients and surrogates became more likely to endorse mutual surrogate decision making, that is, a balance of their own wishes and what the surrogate thinks best (adjusted odds compared with baseline for patients = 1.78, P = 0.04; adjusted odds for surrogates = 2.05, P = 0.03). CONTROL patients became 40% less likely to endorse mutual surrogate decision making (P = 0.08), and CONTROL surrogates did not change significantly from baseline (adjusted odds = 1.44, P = 0.28). Stress levels decreased for TAILORED surrogates (impact of events scale = 23.1 ± 14.6 baseline, 20.8 ± 15.3 f/u, P = 0.046), but not for CONTROL (P = 0.85), and post-intervention stress was lower for TAILORED than CONTROL (P = 0.04). Surrogates' confidence was uniformly high at baseline and did not change. Caregiver burden (Zarit) increased from 12.5 ± 6.5 to 14.7 ± 8.1 for TAILORED (P decision making was higher at follow-up for TAILORED than for CONTROL (71% vs. 52%, P = 0.03). TAILORED patients and surrogates who

  6. Antiviral activity of Ecasol against feline calicivirus, a surrogate of human norovirus

    Directory of Open Access Journals (Sweden)

    Yogesh Chander

    2012-12-01

    Full Text Available Summary: Human norovirus (NoV is a major cause of acute gastroenteritis in closed settings such as hospitals, hotels and cruise ships. The virus survives on inanimate surfaces for extended periods of time, and environmental contamination has been implicated in its transmission. The disinfection of contaminated areas is important in controlling the spread of NoV infections. Neutral solutions of electrochemically activated (ECA-anolyte have been shown to be powerful disinfectants against a broad range of bacterial pathogens. The active chemical ingredient is hypochlorous acid (HOCl, which is registered as an approved food contact surface sanitizer in the United States by the Environmental Protection Agency, pursuant to 40 CFR 180.940. We evaluated the antiviral activity of Ecasol (an ECA-anolyte against feline calicivirus (FCV, a surrogate of NoV. FCV dried on plastic surfaces was exposed to Ecasol for 1, 2, or 5 min. After exposure to Ecasol, the virus titers were compared with untreated controls to determine the virus inactivation efficacy after different contact times. Ecasol was found to decrease the FCV titer by >5 log10 within 1 min of contact, indicating its suitability for inactivation of NoV on surfaces. Keywords: Ecasol, ECA-anolyte, Trustwater, Electrochemical activation, Norovirus, Feline calicivirus, Fomites

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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."

  13. 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.

  14. An alternative method for cDNA cloning from surrogate eukaryotic cells transfected with the corresponding genomic DNA.

    Science.gov (United States)

    Hu, Lin-Yong; Cui, Chen-Chen; Song, Yu-Jie; Wang, Xiang-Guo; Jin, Ya-Ping; Wang, Ai-Hua; Zhang, Yong

    2012-07-01

    cDNA is widely used in gene function elucidation and/or transgenics research but often suitable tissues or cells from which to isolate mRNA for reverse transcription are unavailable. Here, an alternative method for cDNA cloning is described and tested by cloning the cDNA of human LALBA (human alpha-lactalbumin) from genomic DNA. First, genomic DNA containing all of the coding exons was cloned from human peripheral blood and inserted into a eukaryotic expression vector. Next, by delivering the plasmids into either 293T or fibroblast cells, surrogate cells were constructed. Finally, the total RNA was extracted from the surrogate cells and cDNA was obtained by RT-PCR. The human LALBA cDNA that was obtained was compared with the corresponding mRNA published in GenBank. The comparison showed that the two sequences were identical. The novel method for cDNA cloning from surrogate eukaryotic cells described here uses well-established techniques that are feasible and simple to use. We anticipate that this alternative method will have widespread applications.

  15. First simultaneous measurement of fission and gamma probabilities of 237U and 239Np via surrogate reactions

    Directory of Open Access Journals (Sweden)

    Marini P.

    2016-01-01

    Full Text Available Fission and gamma decay probabilities of 237U and 239Np have been measured, for the first time simultaneously in dedicated experiments, via the surrogate reactions 238U(3He, 4He and 238U(3He,d, respectively. While a good agreement between our data and neutron-induced data is found for fission probabilities, gamma decay probabilities are several times higher than the corresponding neutron-induced data for each studied nucleus. We study the role of the different spin distributions populated in the surrogate and neutron-induced reactions. The compound nucleus spin distribution populated in the surrogate reaction is extracted from the measured gamma-decay probabilities, and used as input parameter in the statistical model to predict fission probabilities to be compared to our data. A strong disagreement between our data and the prediction is obtained. Preliminary results from an additional dedicated experiment confirm the observed discrepancies, indicating the need of a better understanding of the formation and decay processes of the compound nucleus.

  16. Decomposition Technology Development of Organic Component in a Decontamination Waste Solution

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chong Hun; Oh, W. Z.; Won, H. J.; Choi, W. K.; Kim, G. N.; Moon, J. K

    2007-11-15

    Through the project of 'Decomposition Technology Development of Organic Component in a Decontamination Waste Solution', the followings were studied. 1. Investigation of decontamination characteristics of chemical decontamination process 2. Analysis of COD, ferrous ion concentration, hydrogen peroxide concentration 3. Decomposition tests of hardly decomposable organic compounds 4. Improvement of organic acid decomposition process by ultrasonic wave and UV light 5. Optimization of decomposition process using a surrogate decontamination waste solution.

  17. Comparison of treatment effect sizes from pivotal and postapproval trials of novel therapeutics approved by the FDA based on surrogate markers of disease: a meta-epidemiological study.

    Science.gov (United States)

    Wallach, Joshua D; Ciani, Oriana; Pease, Alison M; Gonsalves, Gregg S; Krumholz, Harlan M; Taylor, Rod S; Ross, Joseph S

    2018-03-21

    The U.S. Food and Drug Administration (FDA) often approves new drugs based on trials that use surrogate markers for endpoints, which involve certain trade-offs and may risk making erroneous inferences about the medical product's actual clinical effect. This study aims to compare the treatment effects among pivotal trials supporting FDA approval of novel therapeutics based on surrogate markers of disease with those observed among postapproval trials for the same indication. We searched Drugs@FDA and PubMed to identify published randomized superiority design pivotal trials for all novel drugs initially approved by the FDA between 2005 and 2012 based on surrogate markers as primary endpoints and published postapproval trials using the same surrogate markers or patient-relevant outcomes as endpoints. Summary ratio of odds ratios (RORs) and difference between standardized mean differences (dSMDs) were used to quantify the average difference in treatment effects between pivotal and matched postapproval trials. Between 2005 and 2012, the FDA approved 88 novel drugs for 90 indications based on one or multiple pivotal trials using surrogate markers of disease. Of these, 27 novel drugs for 27 indications were approved based on pivotal trials using surrogate markers as primary endpoints that could be matched to at least one postapproval trial, for a total of 43 matches. For nine (75.0%) of the 12 matches using the same non-continuous surrogate markers as trial endpoints, pivotal trials had larger treatment effects than postapproval trials. On average, treatment effects were 50% higher (more beneficial) in the pivotal than the postapproval trials (ROR 1.5; 95% confidence interval CI 1.01-2.23). For 17 (54.8%) of the 31 matches using the same continuous surrogate markers as trial endpoints, pivotal trials had larger treatment effects than the postapproval trials. On average, there was no difference in treatment effects between pivotal and postapproval trials (dSMDs 0.01; 95

  18. 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.

  19. Revisiting photodynamic therapy dosimetry: reductionist & surrogate approaches to facilitate clinical success

    Science.gov (United States)

    Pogue, Brian W.; Elliott, Jonathan T.; Kanick, Stephen C.; Davis, Scott C.; Samkoe, Kimberley S.; Maytin, Edward V.; Pereira, Stephen P.; Hasan, Tayyaba

    2016-04-01

    Photodynamic therapy (PDT) can be a highly complex treatment, with many parameters influencing treatment efficacy. The extent to which dosimetry is used to monitor and standardize treatment delivery varies widely, ranging from measurement of a single surrogate marker to comprehensive approaches that aim to measure or estimate as many relevant parameters as possible. Today, most clinical PDT treatments are still administered with little more than application of a prescribed drug dose and timed light delivery, and thus the role of patient-specific dosimetry has not reached widespread clinical adoption. This disconnect is at least partly due to the inherent conflict between the need to measure and understand multiple parameters in vivo in order to optimize treatment, and the need for expedience in the clinic and in the regulatory and commercialization process. Thus, a methodical approach to selecting primary dosimetry metrics is required at each stage of translation of a treatment procedure, moving from complex measurements to understand PDT mechanisms in pre-clinical and early phase I trials, towards the identification and application of essential dose-limiting and/or surrogate measurements in phase II/III trials. If successful, identifying the essential and/or reliable surrogate dosimetry measurements should help facilitate increased adoption of clinical PDT. In this paper, examples of essential dosimetry points and surrogate dosimetry tools that may be implemented in phase II/III trials are discussed. For example, the treatment efficacy as limited by light penetration in interstitial PDT may be predicted by the amount of contrast uptake in CT, and so this could be utilized as a surrogate dosimetry measurement to prescribe light doses based upon pre-treatment contrast. Success of clinical ALA-based skin lesion treatment is predicted almost uniquely by the explicit or implicit measurements of photosensitizer and photobleaching, yet the individualization of treatment

  20. Comparison of Outcomes for Normal Saline and an Antiseptic Solution for Negative-Pressure Wound Therapy with Instillation.

    Science.gov (United States)

    Kim, Paul J; Attinger, Christopher E; Oliver, Noah; Garwood, Caitlin; Evans, Karen K; Steinberg, John S; Lavery, Larry A

    2015-11-01

    Negative-pressure wound therapy with instillation is an adjunctive treatment that uses periodic instillation of a solution and negative pressure for a wide diversity of wounds. A variety of solutions have been reported, with topical antiseptics as the most frequently chosen option. The objective of this study was to compare the outcomes of normal saline versus an antiseptic solution for negative-pressure wound therapy with instillation for the adjunctive treatment of infected wounds. This was a prospective, randomized, effectiveness study comparing 0.9% normal saline versus 0.1% polyhexanide plus 0.1% betaine for the adjunctive treatment of infected wounds that required hospital admission and operative débridement. One hundred twenty-three patients were eligible, with 100 patients randomized for the intention-to-treat analysis and 83 patients for the per-protocol analysis. The surrogate outcomes measured were number of operative visits, length of hospital stay, time to final surgical procedure, proportion of closed or covered wounds, and proportion of wounds that remained closed or covered at the 30-day follow-up. There were no statistically significant differences in the demographic profiles in the two cohorts except for a larger proportion of male patients (p = 0.004). There was no statistically significant difference in the surrogate outcomes with the exception of the time to final surgical procedure favoring normal saline (p = 0.038). The authors' results suggest that 0.9% normal saline may be as effective as an antiseptic (0.1% polyhexanide plus 0.1% betaine) for negative-pressure wound therapy with instillation for the adjunctive inpatient management of infected wounds. Therapeutic, II.

  1. I don't want to be the one saying 'we should just let him die': intrapersonal tensions experienced by surrogate decision makers in the ICU.

    Science.gov (United States)

    Schenker, Yael; Crowley-Matoka, Megan; Dohan, Daniel; Tiver, Greer A; Arnold, Robert M; White, Douglas B

    2012-12-01

    Although numerous studies have addressed external factors associated with difficulty in surrogate decision making, intrapersonal sources of tension are an important element of decision making that have received little attention. To characterize key intrapersonal tensions experienced by surrogate decision makers in the intensive care unit (ICU), and explore associated coping strategies. Qualitative interview study. Thirty surrogates from five ICUs at two hospitals in Pittsburgh, Pennsylvania, who were actively involved in making life-sustaining treatment decisions for a critically ill loved one. We conducted in-depth, semi-structured interviews with surrogates, focused on intrapersonal tensions, role challenges, and coping strategies. We analyzed transcripts using constant comparative methods. Surrogates experience significant emotional conflict between the desire to act in accordance with their loved one's values and 1) not wanting to feel responsible for a loved one's death, 2) a desire to pursue any chance of recovery, and 3) the need to preserve family well-being. Associated coping strategies included 1) recalling previous discussions with a loved one, 2) sharing decisions with family members, 3) delaying or deferring decision making, 4) spiritual/religious practices, and 5) story-telling. Surrogates' struggle to reconcile personal and family emotional needs with their loved ones' wishes, and utilize common coping strategies to combat intrapersonal tensions. These data suggest reasons surrogates may struggle to follow a strict substituted judgment standard. They also suggest ways clinicians may improve decision making, including attending to surrogates' emotions, facilitating family decision making, and eliciting potential emotional conflicts and spiritual needs.

  2. Partitioning of polychlorinated biphenyls into human cells and adipose tissues: evaluation of octanol, triolein, and liposomes as surrogates

    NARCIS (Netherlands)

    Quinn, Cristina L.; Van Der Heijden, Stephan A.; Wania, Frank; Jonker, Michiel T O

    2014-01-01

    Whereas octanol, triacylglycerides, and liposomes have all been proposed as surrogates for measuring the affinity of hydrophobic organic contaminants to human lipids, no comparative evaluation of their suitability exists. Here we conducted batch sorption experiments with polyoxymethylene passive

  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. 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.

  5. 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.

  6. 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

  7. Elevated pressure improves the extraction and identification of proteins recovered from formalin-fixed, paraffin-embedded tissue surrogates.

    Directory of Open Access Journals (Sweden)

    Carol B Fowler

    2010-12-01

    Full Text Available Proteomic studies of formalin-fixed paraffin-embedded (FFPE tissues are frustrated by the inability to extract proteins from archival tissue in a form suitable for analysis by 2-D gel electrophoresis or mass spectrometry. This inability arises from the difficulty of reversing formaldehyde-induced protein adducts and cross-links within FFPE tissues. We previously reported the use of elevated hydrostatic pressure as a method for efficient protein recovery from a hen egg-white lysozyme tissue surrogate, a model system developed to study formalin fixation and histochemical processing.In this study, we demonstrate the utility of elevated hydrostatic pressure as a method for efficient protein recovery from FFPE mouse liver tissue and a complex multi-protein FFPE tissue surrogate comprised of hen egg-white lysozyme, bovine carbonic anhydrase, bovine ribonuclease A, bovine serum albumin, and equine myoglobin (55∶15∶15∶10∶5 wt%. Mass spectrometry of the FFPE tissue surrogates retrieved under elevated pressure showed that both the low and high-abundance proteins were identified with sequence coverage comparable to that of the surrogate mixture prior to formaldehyde treatment. In contrast, non-pressure-extracted tissue surrogate samples yielded few positive and many false peptide identifications. Studies with soluble formalin-treated bovine ribonuclease A demonstrated that pressure modestly inhibited the rate of reversal (hydrolysis of formaldehyde-induced protein cross-links. Dynamic light scattering studies suggest that elevated hydrostatic pressure and heat facilitate the recovery of proteins free of formaldehyde adducts and cross-links by promoting protein unfolding and hydration with a concomitant reduction in the average size of the protein aggregates.These studies demonstrate that elevated hydrostatic pressure treatment is a promising approach for improving the recovery of proteins from FFPE tissues in a form suitable for proteomic analysis.

  8. Elevated Pressure Improves the Extraction and Identification of Proteins Recovered from Formalin-Fixed, Paraffin-Embedded Tissue Surrogates

    Science.gov (United States)

    Fowler, Carol B.; Chesnick, Ingrid E.; Moore, Cedric D.; O'Leary, Timothy J.; Mason, Jeffrey T.

    2010-01-01

    Background Proteomic studies of formalin-fixed paraffin-embedded (FFPE) tissues are frustrated by the inability to extract proteins from archival tissue in a form suitable for analysis by 2-D gel electrophoresis or mass spectrometry. This inability arises from the difficulty of reversing formaldehyde-induced protein adducts and cross-links within FFPE tissues. We previously reported the use of elevated hydrostatic pressure as a method for efficient protein recovery from a hen egg-white lysozyme tissue surrogate, a model system developed to study formalin fixation and histochemical processing. Principal Findings In this study, we demonstrate the utility of elevated hydrostatic pressure as a method for efficient protein recovery from FFPE mouse liver tissue and a complex multi-protein FFPE tissue surrogate comprised of hen egg-white lysozyme, bovine carbonic anhydrase, bovine ribonuclease A, bovine serum albumin, and equine myoglobin (55∶15∶15∶10∶5 wt%). Mass spectrometry of the FFPE tissue surrogates retrieved under elevated pressure showed that both the low and high-abundance proteins were identified with sequence coverage comparable to that of the surrogate mixture prior to formaldehyde treatment. In contrast, non-pressure-extracted tissue surrogate samples yielded few positive and many false peptide identifications. Studies with soluble formalin-treated bovine ribonuclease A demonstrated that pressure modestly inhibited the rate of reversal (hydrolysis) of formaldehyde-induced protein cross-links. Dynamic light scattering studies suggest that elevated hydrostatic pressure and heat facilitate the recovery of proteins free of formaldehyde adducts and cross-links by promoting protein unfolding and hydration with a concomitant reduction in the average size of the protein aggregates. Conclusions These studies demonstrate that elevated hydrostatic pressure treatment is a promising approach for improving the recovery of proteins from FFPE tissues in a form

  9. 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.

  10. 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.

  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. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    Science.gov (United States)

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Enhanced Removal of a Human Norovirus Surrogate from Fresh Vegetables and Fruits by a Combination of Surfactants and Sanitizers▿

    Science.gov (United States)

    Predmore, Ashley; Li, Jianrong

    2011-01-01

    Fruits and vegetables are major vehicles for transmission of food-borne enteric viruses since they are easily contaminated at pre- and postharvest stages and they undergo little or no processing. However, commonly used sanitizers are relatively ineffective for removing human norovirus surrogates from fresh produce. In this study, we systematically evaluated the effectiveness of surfactants on removal of a human norovirus surrogate, murine norovirus 1 (MNV-1), from fresh produce. We showed that a panel of surfactants, including sodium dodecyl sulfate (SDS), Nonidet P-40 (NP-40), Triton X-100, and polysorbates, significantly enhanced the removal of viruses from fresh fruits and vegetables. While tap water alone and chlorine solution (200 ppm) gave only <1.2-log reductions in virus titer in all fresh produce, a solution containing 50 ppm of surfactant was able to achieve a 3-log reduction in virus titer in strawberries and an approximately 2-log reduction in virus titer in lettuce, cabbage, and raspberries. Moreover, a reduction of approximately 3 logs was observed in all the tested fresh produce after sanitization with a solution containing a combination of 50 ppm of each surfactant and 200 ppm of chlorine. Taken together, our results demonstrate that the combination of a surfactant with a commonly used sanitizer enhanced the efficiency in removing viruses from fresh produce by approximately 100 times. Since SDS is an FDA-approved food additive and polysorbates are recognized by the FDA as GRAS (generally recognized as safe) products, implementation of this novel sanitization strategy would be a feasible approach for efficient reduction of the virus load in fresh produce. PMID:21622782

  14. Perinatal outcomes after natural conception versus in vitro fertilization (IVF) in gestational surrogates: a model to evaluate IVF treatment versus maternal effects.

    Science.gov (United States)

    Woo, Irene; Hindoyan, Rita; Landay, Melanie; Ho, Jacqueline; Ingles, Sue Ann; McGinnis, Lynda K; Paulson, Richard J; Chung, Karine

    2017-12-01

    To study the perinatal outcomes between singleton live births achieved with the use of commissioned versus spontaneously conceived embryos carried by the same gestational surrogate. Retrospective cohort study. Academic in vitro fertilization center. Gestational surrogate. None. Pregnancy outcome, gestational age at birth, birth weight, perinatal complications. We identified 124 gestational surrogates who achieved a total of 494 pregnancies. Pregnancy outcomes for surrogate and spontaneous pregnancies were significantly different (Psurrogate pregnancies more likely to result in twin pregnancies: 33% vs. 1%. Miscarriage and ectopic rates were similar. Of these pregnancies, there were 352 singleton live births: 103 achieved from commissioned embryos and 249 conceived spontaneously. Surrogate births had lower mean gestational age at delivery (38.8 ± 2.1 vs. 39.7 ± 1.4), higher rates of preterm birth (10.7% vs. 3.1%), and higher rates of low birth weight (7.8% vs. 2.4%). Neonates from surrogacy had birth weights that were, on average, 105 g lower. Surrogate births had significantly higher obstetrical complications, including gestational diabetes, hypertension, use of amniocentesis, placenta previa, antibiotic requirement during labor, and cesarean section. Neonates born from commissioned embryos and carried by gestational surrogates have increased adverse perinatal outcomes, including preterm birth, low birth weight, hypertension, maternal gestational diabetes, and placenta previa, compared with singletons conceived spontaneously and carried by the same woman. Our data suggest that assisted reproductive procedures may potentially affect embryo quality and that its negative impact can not be overcome even with a proven healthy uterine environment. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  15. 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.

  16. 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

  17. Phenotypic and genomic comparison of Mycobacterium aurum and surrogate model species to Mycobacterium tuberculosis: implications for drug discovery.

    Science.gov (United States)

    Namouchi, Amine; Cimino, Mena; Favre-Rochex, Sandrine; Charles, Patricia; Gicquel, Brigitte

    2017-07-13

    Tuberculosis (TB) is caused by Mycobacterium tuberculosis and represents one of the major challenges facing drug discovery initiatives worldwide. The considerable rise in bacterial drug resistance in recent years has led to the need of new drugs and drug regimens. Model systems are regularly used to speed-up the drug discovery process and circumvent biosafety issues associated with manipulating M. tuberculosis. These include the use of strains such as Mycobacterium smegmatis and Mycobacterium marinum that can be handled in biosafety level 2 facilities, making high-throughput screening feasible. However, each of these model species have their own limitations. We report and describe the first complete genome sequence of Mycobacterium aurum ATCC23366, an environmental mycobacterium that can also grow in the gut of humans and animals as part of the microbiota. This species shows a comparable resistance profile to that of M. tuberculosis for several anti-TB drugs. The aims of this study were to (i) determine the drug resistance profile of a recently proposed model species, Mycobacterium aurum, strain ATCC23366, for anti-TB drug discovery as well as Mycobacterium smegmatis and Mycobacterium marinum (ii) sequence and annotate the complete genome sequence of this species obtained using Pacific Bioscience technology (iii) perform comparative genomics analyses of the various surrogate strains with M. tuberculosis (iv) discuss how the choice of the surrogate model used for drug screening can affect the drug discovery process. We describe the complete genome sequence of M. aurum, a surrogate model for anti-tuberculosis drug discovery. Most of the genes already reported to be associated with drug resistance are shared between all the surrogate strains and M. tuberculosis. We consider that M. aurum might be used in high-throughput screening for tuberculosis drug discovery. We also highly recommend the use of different model species during the drug discovery screening process.

  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. 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.

  20. 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

  1. Annual sediment flux estimates in a tidal strait using surrogate measurements

    Science.gov (United States)

    Ganju, N.K.; Schoellhamer, D.H.

    2006-01-01

    Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute for tidally averaged discharge and velocity-weighted suspended-sediment concentration in the Strait, thereby providing advective flux estimates, while Stokes drift is estimated with suspended-sediment concentration alone. Dispersive flux is estimated using the product of longitudinal salinity gradient and the root-mean-square value of velocity-weighted suspended-sediment concentration as an added surrogate variable. Cross-sectional measurements validated the use of surrogates during the monitoring period. During high freshwater flow advective and dispersive flux were in the seaward direction, while landward dispersive flux dominated and advective flux approached zero during low freshwater flow. Stokes drift flux was consistently in the landward direction. Wetter than average years led to net export from Suisun Bay, while dry years led to net sediment import. Relatively low watershed sediment fluxes to Suisun Bay contribute to net export during the wet season, while gravitational circulation in Carquinez Strait and higher suspended-sediment concentrations in San Pablo Bay (seaward end of Carquinez Strait) are responsible for the net import of sediment during the dry season. Annual predictions of suspended-sediment fluxes, using these methods, will allow for a sediment budget for Suisun Bay, which has implications for marsh restoration and nutrient/contaminant transport. These methods also provide a general framework for estimating sediment fluxes in estuarine environments, where temporal and spatial variability of transport are large. ?? 2006 Elsevier Ltd. All rights

  2. Surrogate Based Uni/Multi-Objective Optimization and Distribution Estimation Methods

    Science.gov (United States)

    Gong, W.; Duan, Q.; Huo, X.

    2017-12-01

    Parameter calibration has been demonstrated as an effective way to improve the performance of dynamic models, such as hydrological models, land surface models, weather and climate models etc. Traditional optimization algorithms usually cost a huge number of model evaluations, making dynamic model calibration very difficult, or even computationally prohibitive. With the help of a serious of recently developed adaptive surrogate-modelling based optimization methods: uni-objective optimization method ASMO, multi-objective optimization method MO-ASMO, and probability distribution estimation method ASMO-PODE, the number of model evaluations can be significantly reduced to several hundreds, making it possible to calibrate very expensive dynamic models, such as regional high resolution land surface models, weather forecast models such as WRF, and intermediate complexity earth system models such as LOVECLIM. This presentation provides a brief introduction to the common framework of adaptive surrogate-based optimization algorithms of ASMO, MO-ASMO and ASMO-PODE, a case study of Common Land Model (CoLM) calibration in Heihe river basin in Northwest China, and an outlook of the potential applications of the surrogate-based optimization methods.

  3. 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)

  4. The use of surrogates for an optimal management of coupled groundwater-agriculture hydrosystems

    Science.gov (United States)

    Grundmann, J.; Schütze, N.; Brettschneider, M.; Schmitz, G. H.; Lennartz, F.

    2012-04-01

    For ensuring an optimal sustainable water resources management in arid coastal environments, we develop a new simulation based integrated water management system. It aims at achieving best possible solutions for groundwater withdrawals for agricultural and municipal water use including saline water management together with a substantial increase of the water use efficiency in irrigated agriculture. To achieve a robust and fast operation of the management system regarding water quality and water quantity we develop appropriate surrogate models by combining physically based process modelling with methods of artificial intelligence. Thereby we use an artificial neural network for modelling the aquifer response, inclusive the seawater interface, which was trained on a scenario database generated by a numerical density depended groundwater flow model. For simulating the behaviour of high productive agricultural farms crop water production functions are generated by means of soil-vegetation-atmosphere-transport (SVAT)-models, adapted to the regional climate conditions, and a novel evolutionary optimisation algorithm for optimal irrigation scheduling and control. We apply both surrogates exemplarily within a simulation based optimisation environment using the characteristics of the south Batinah region in the Sultanate of Oman which is affected by saltwater intrusion into the coastal aquifer due to excessive groundwater withdrawal for irrigated agriculture. We demonstrate the effectiveness of our methodology for the evaluation and optimisation of different irrigation practices, cropping pattern and resulting abstraction scenarios. Due to contradicting objectives like profit-oriented agriculture vs. aquifer sustainability a multi-criterial optimisation is performed.

  5. 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

  6. Limited Role for Biliary Stent as Surrogate Fiducial Marker in Pancreatic Cancer: Stent and Intratumoral Fiducials Compared

    Energy Technology Data Exchange (ETDEWEB)

    Horst, Astrid van der, E-mail: a.vanderhorst@amc.uva.nl [Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Lens, Eelco; Wognum, Silvia; Jong, Rianne de [Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Hooft, Jeanin E. van [Department of Gastroenterology and Hepatology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Tienhoven, Geertjan van; Bel, Arjan [Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands)

    2014-07-01

    Purpose: Because of low soft-tissue contrast of cone beam computed tomography (CBCT), fiducial markers are often used for radiation therapy patient setup verification. For pancreatic cancer patients, biliary stents have been suggested as surrogate fiducials. Using intratumoral fiducials as standard for tumor position, this study aims to quantify the suitability of biliary stents for measuring interfractional and respiratory-induced position variations of pancreatic tumors. Methods and Materials: Eleven pancreatic cancer patients with intratumoral fiducials and a biliary stent were included in this study. Daily CBCT scans (243 in total) were registered with a reference CT scan, based on bony anatomy, on fiducial markers, and on the biliary stent, respectively. We analyzed the differences in tumor position (ie, markers center-of-mass position) among these 3 registrations. In addition, we measured for 9 patients the magnitude of respiratory-induced motion (MM) of the markers and of the stent on 4-dimensional CT (4DCT) and determined the difference between these 2 magnitudes (ΔMM). Results: The stent indicated tumor position better than bony anatomy in 67% of fractions; the absolute difference between the markers and stent registration was >5 mm in 46% of fractions and >10 mm in 20% of fractions. Large PTV margins (superior-inferior direction, >19 mm) would be needed to account for this interfractional position variability. On 4DCT, we found in superior-inferior direction a mean ΔMM of 0.5 mm (range, –2.6 to 4.2 mm). Conclusions: For respiratory-induced motion, the mean ΔMM is small, but for individual patients the absolute difference can be >4 mm. For interfractional position variations, a stent is, on average, a better surrogate fiducial than bony anatomy, but large PTV margins would still be required. Therefore, intratumoral fiducials are recommended for online setup verification for all pancreatic patients scheduled for radiation therapy, including

  7. Optimizing water resources management in large river basins with integrated surface water-groundwater modeling: A surrogate-based approach

    Science.gov (United States)

    Wu, Bin; Zheng, Yi; Wu, Xin; Tian, Yong; Han, Feng; Liu, Jie; Zheng, Chunmiao

    2015-04-01

    Integrated surface water-groundwater modeling can provide a comprehensive and coherent understanding on basin-scale water cycle, but its high computational cost has impeded its application in real-world management. This study developed a new surrogate-based approach, SOIM (Surrogate-based Optimization for Integrated surface water-groundwater Modeling), to incorporate the integrated modeling into water management optimization. Its applicability and advantages were evaluated and validated through an optimization research on the conjunctive use of surface water (SW) and groundwater (GW) for irrigation in a semiarid region in northwest China. GSFLOW, an integrated SW-GW model developed by USGS, was employed. The study results show that, due to the strong and complicated SW-GW interactions, basin-scale water saving could be achieved by spatially optimizing the ratios of groundwater use in different irrigation districts. The water-saving potential essentially stems from the reduction of nonbeneficial evapotranspiration from the aqueduct system and shallow groundwater, and its magnitude largely depends on both water management schemes and hydrological conditions. Important implications for water resources management in general include: first, environmental flow regulation needs to take into account interannual variation of hydrological conditions, as well as spatial complexity of SW-GW interactions; and second, to resolve water use conflicts between upper stream and lower stream, a system approach is highly desired to reflect ecological, economic, and social concerns in water management decisions. Overall, this study highlights that surrogate-based approaches like SOIM represent a promising solution to filling the gap between complex environmental modeling and real-world management decision-making.

  8. Revisiting photodynamic therapy dosimetry: reductionist and surrogate approaches to facilitate clinical success

    International Nuclear Information System (INIS)

    Pogue, Brian W; Elliott, Jonathan T; Kanick, Stephen C; Davis, Scott C; Samkoe, Kimberley S; Maytin, Edward V; Pereira, Stephen P; Hasan, Tayyaba

    2016-01-01

    Photodynamic therapy (PDT) can be a highly complex treatment, with many parameters influencing treatment efficacy. The extent to which dosimetry is used to monitor and standardize treatment delivery varies widely, ranging from measurement of a single surrogate marker to comprehensive approaches that aim to measure or estimate as many relevant parameters as possible. Today, most clinical PDT treatments are still administered with little more than application of a prescribed drug dose and timed light delivery, and thus the role of patient-specific dosimetry has not reached widespread clinical adoption. This disconnect is at least partly due to the inherent conflict between the need to measure and understand multiple parameters in vivo in order to optimize treatment, and the need for expedience in the clinic and in the regulatory and commercialization process. Thus, a methodical approach to selecting primary dosimetry metrics is required at each stage of translation of a treatment procedure, moving from complex measurements to understand PDT mechanisms in pre-clinical and early phase I trials, towards the identification and application of essential dose-limiting and/or surrogate measurements in phase II/III trials. If successful, identifying the essential and/or reliable surrogate dosimetry measurements should help facilitate increased adoption of clinical PDT. In this paper, examples of essential dosimetry points and surrogate dosimetry tools that may be implemented in phase II/III trials are discussed. For example, the treatment efficacy as limited by light penetration in interstitial PDT may be predicted by the amount of contrast uptake in CT, and so this could be utilized as a surrogate dosimetry measurement to prescribe light doses based upon pre-treatment contrast. Success of clinical ALA-based skin lesion treatment is predicted almost uniquely by the explicit or implicit measurements of photosensitizer and photobleaching, yet the individualization of treatment

  9. A review on design of experiments and surrogate models in aircraft real-time and many-query aerodynamic analyses

    Science.gov (United States)

    Yondo, Raul; Andrés, Esther; Valero, Eusebio

    2018-01-01

    Full scale aerodynamic wind tunnel testing, numerical simulation of high dimensional (full-order) aerodynamic models or flight testing are some of the fundamental but complex steps in the various design phases of recent civil transport aircrafts. Current aircraft aerodynamic designs have increase in complexity (multidisciplinary, multi-objective or multi-fidelity) and need to address the challenges posed by the nonlinearity of the objective functions and constraints, uncertainty quantification in aerodynamic problems or the restrained computational budgets. With the aim to reduce the computational burden and generate low-cost but accurate models that mimic those full order models at different values of the design variables, Recent progresses have witnessed the introduction, in real-time and many-query analyses, of surrogate-based approaches as rapid and cheaper to simulate models. In this paper, a comprehensive and state-of-the art survey on common surrogate modeling techniques and surrogate-based optimization methods is given, with an emphasis on models selection and validation, dimensionality reduction, sensitivity analyses, constraints handling or infill and stopping criteria. Benefits, drawbacks and comparative discussions in applying those methods are described. Furthermore, the paper familiarizes the readers with surrogate models that have been successfully applied to the general field of fluid dynamics, but not yet in the aerospace industry. Additionally, the review revisits the most popular sampling strategies used in conducting physical and simulation-based experiments in aircraft aerodynamic design. Attractive or smart designs infrequently used in the field and discussions on advanced sampling methodologies are presented, to give a glance on the various efficient possibilities to a priori sample the parameter space. Closing remarks foster on future perspectives, challenges and shortcomings associated with the use of surrogate models by aircraft industrial

  10. 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.

  11. 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.

  12. Validity of fish, birds and mammals as surrogates for amphibians and reptiles in pesticide toxicity assessment.

    Science.gov (United States)

    Ortiz-Santaliestra, Manuel E; Maia, Joao P; Egea-Serrano, Andrés; Lopes, Isabel

    2018-02-28

    Amphibians and reptiles are the two most endangered groups of vertebrates. Environmental pollution by pesticides is recognised as one of the major factors threatening populations of these groups. However, the effects of pesticides on amphibians and reptiles have been studied for few substances, which is partly related to the fact that these animals are not included in the mandatory toxicity testing conducted as part of environmental risk assessments of pesticides. Whether risks of pesticides to amphibians and reptiles are addressed by surrogate taxa used in risk assessment is currently under debate. In order to develop a scientifically sound and robust risk assessment scheme, information needs to be gathered to examine whether fish, birds and mammals are valid surrogates for amphibians and reptiles. We updated a systematic review of scientific literature that was recently published compiling toxicity data on amphibians and reptiles. The outcome of this review was analysed with the purposes to (1) compare endpoints from amphibians and reptiles with the available information from fish, birds and mammals, and (2) develop species sensitivity distributions (SSDs) for those substances tested in at least six amphibian species (no substances were found tested in at least six reptile species) to identify a candidate amphibian model species to be used as surrogate in risk assessment. A positive correlation was found between toxicity recorded on fish and amphibians, the former revealing, in general, to be more sensitive than the latter to waterborne pollutants. In the terrestrial environment, although birds and mammals were more sensitive than amphibians and reptiles to at least 60% of tested substances, just a few weak significant correlations were observed. As a general rule, homoeothermic vertebrates are not good surrogates for reptiles and terrestrial amphibians in pesticide risk assessment. However, some chemical-dependent trends were detected, with pyrethroids and

  13. 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.

  14. SOA formation from photooxidation of naphthalene and methylnaphthalenes with m-xylene and surrogate mixtures

    Science.gov (United States)

    Chen, Chia-Li; Li, Lijie; Tang, Ping; Cocker, David R.

    2018-05-01

    SOA formation is not well predicted in current models in urban area. The interaction among multiple anthropogenic volatile organic compounds is essential for the SOA formation in the complex urban atmosphere. Secondary organic aerosol (SOA) from the photooxidation of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as well as individual polycyclic aromatic hydrocarbons (PAHs) mixed with m-xylene or an atmospheric surrogate mixture was explored in the UCR CE-CERT environmental chamber under urban relevant low NOx and extremely low NOx (H2O2) conditions. Addition of m-xylene suppressed SOA formation from the individual PAH precursor. A similar suppression effect on SOA formation was observed during the surrogate mixture photooxidation suggesting the importance of gas-phase chemical reactivity to SOA formation. The SOA growth rate for different PAH-m-xylene mixtures was strongly correlated with initial [HO2]/[RO2] ratio but negatively correlated with initial m-xylene/NO ratio. Decreasing SOA formation was observed for increasing m-xylene/PAHs ratios and increasing initial m-xylene/NO ratio. The SOA chemical composition characteristics such as f44 versus f43, H/C ratio, O/C ratio, and the oxidation state of the carbon OSbarc were consistent with a continuously aging with the SOA exhibiting characteristics of both individual precursors. SOA formation from PAHs was also suppressed within an atmospheric surrogate mixture compared to the SOA formed from individual PAHs, indicating that atmospheric reactivity directly influences SOA formation from PAHs.

  15. Using a gel/plastic surrogate to study the biomechanical response of the head under air shock loading: a combined experimental and numerical investigation.

    Science.gov (United States)

    Zhu, Feng; Wagner, Christina; Dal Cengio Leonardi, Alessandra; Jin, Xin; Vandevord, Pamela; Chou, Clifford; Yang, King H; King, Albert I

    2012-03-01

    A combined experimental and numerical study was conducted to determine a method to elucidate the biomechanical response of a head surrogate physical model under air shock loading. In the physical experiments, a gel-filled egg-shaped skull/brain surrogate was exposed to blast overpressure in a shock tube environment, and static pressures within the shock tube and the surrogate were recorded throughout the event. A numerical model of the shock tube was developed using the Eulerian approach and validated against experimental data. An arbitrary Lagrangian-Eulerian (ALE) fluid-structure coupling algorithm was then utilized to simulate the interaction of the shock wave and the head surrogate. After model validation, a comprehensive series of parametric studies was carried out on the egg-shaped surrogate FE model to assess the effect of several key factors, such as the elastic modulus of the shell, bulk modulus of the core, head orientation, and internal sensor location, on pressure and strain responses. Results indicate that increasing the elastic modulus of the shell within the range simulated in this study led to considerable rise of the overpressures. Varying the bulk modulus of the core from 0.5 to 2.0 GPa, the overpressure had an increase of 7.2%. The curvature of the surface facing the shock wave significantly affected both the peak positive and negative pressures. Simulations of the head surrogate with the blunt end facing the advancing shock front had a higher pressure compared to the simulations with the pointed end facing the shock front. The influence of an opening (possibly mimicking anatomical apertures) on the peak pressures was evaluated using a surrogate head with a hole on the shell of the blunt end. It was revealed that the presence of the opening had little influence on the positive pressures but could affect the negative pressure evidently.

  16. Surrogacy assessment using principal stratification when surrogate and outcome measures are multivariate normal.

    Science.gov (United States)

    Conlon, Anna S C; Taylor, Jeremy M G; Elliott, Michael R

    2014-04-01

    In clinical trials, a surrogate outcome variable (S) can be measured before the outcome of interest (T) and may provide early information regarding the treatment (Z) effect on T. Using the principal surrogacy framework introduced by Frangakis and Rubin (2002. Principal stratification in causal inference. Biometrics 58, 21-29), we consider an approach that has a causal interpretation and develop a Bayesian estimation strategy for surrogate validation when the joint distribution of potential surrogate and outcome measures is multivariate normal. From the joint conditional distribution of the potential outcomes of T, given the potential outcomes of S, we propose surrogacy validation measures from this model. As the model is not fully identifiable from the data, we propose some reasonable prior distributions and assumptions that can be placed on weakly identified parameters to aid in estimation. We explore the relationship between our surrogacy measures and the surrogacy measures proposed by Prentice (1989. Surrogate endpoints in clinical trials: definition and operational criteria. Statistics in Medicine 8, 431-440). The method is applied to data from a macular degeneration study and an ovarian cancer study.

  17. 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.

  18. Surrogate consent to non-beneficial research: erring on the right side when substituted judgments may be inaccurate.

    Science.gov (United States)

    Johansson, Mats; Broström, Linus

    2016-04-01

    Part of the standard protection of decisionally incapacitated research subjects is a prohibition against enrolling them unless surrogate decision makers authorize it. A common view is that surrogates primarily ought to make their decisions based on what the decisionally incapacitated subject would have wanted regarding research participation. However, empirical studies indicate that surrogate predictions about such preferences are not very accurate. The focus of this article is the significance of surrogate accuracy in the context of research that is not expected to benefit the research subject. We identify three morally relevant asymmetries between being enrolled and not being enrolled in such non-beneficial research, and conclude that when there is a non-negligible probability that surrogates' predictions are wrong, it will generally be better to err on the side of not authorizing enrollment.

  19. 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.

  20. 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

    2012-10-01

    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. 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. 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 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.

  1. 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…

  2. 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.

  3. Comparative study of presurgical hand hygiene with hydroalcoholic solution versus traditional presurgical hand hygiene.

    Science.gov (United States)

    López Martín, M Beatriz; Erice Calvo-Sotelo, Alejo

    To compare presurgical hand hygiene with hydroalcoholic solution following the WHO protocol with traditional presurgical hand hygiene. Cultures of the hands of surgeons and surgical nurses were performed before and after presurgical hand hygiene and after removing gloves at the end of surgery. Cultures were done in 2different days: the first day after traditional presurgical hand hygiene, and the second day after presurgical hand hygiene with hydroalcoholic solution following the WHO protocol. The duration of the traditional hand hygiene was measured and compared with the duration (3min) of the WHO protocol. The cost of the products used in the traditional technique was compared with the cost of the hydroalcoholic solution used. The variability of the traditional technique was determined by observation. Following presurgical hand hygiene with hydroalcoholic solution, colony-forming units (CFU) were detected in 5 (7.3%) subjects, whereas after traditional presurgical hand hygiene CFU were detected in 14 subjects (20.5%) (p < 0.05). After glove removal, the numbers of CFU were similar. The time employed in hand hygiene with hydroalcoholic solution (3min) was inferior to the time employed in the traditional technique (p < 0.05), its cost was less than half, and there was no variability. Compared with other techniques, presurgical hand hygiene with hydroalcoholic solution significantly decreases CFU, has similar latency time, a lower cost, and saves time. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  4. Ecological effects of alternative fuel-reduction treatments: highlights of the National Fire and Fire Surrogate study (FFS)

    Science.gov (United States)

    James D. McIver; Scott L. Stephens; James K. Agee; Jamie Barbour; Ralph E. J. Boerner; Carl B. Edminster; Karen L. Erickson; Kerry L. Farris; Christopher J. Fettig; Carl E. Fiedler; Sally Haase; Stephen C. Hart; Jon E. Keeley; Eric E. Knapp; John F. Lehmkuhl; Jason J. Moghaddas; William Otrosina; Kenneth W. Outcalt; Dylan W. Schwilk; Carl N. Skinner; Thomas A. Waldrop; C. Phillip Weatherspoon; Daniel A. Yaussy; Andrew Youngblood; Steve Zack

    2012-01-01

    The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments....

  5. 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

  6. Black-footed ferrets and Siberian polecats as ecological surrogates and ecological equivalents

    Science.gov (United States)

    Biggins, D.E.; Hanebury, L.R.; Miller, B.J.; Powell, R.A.

    2011-01-01

    Ecologically equivalent species serve similar functions in different communities, and an ecological surrogate species can be used as a substitute for an equivalent species in a community. Siberian polecats (Mustela eversmanii) and black-footed ferrets (M. nigripes) have long been considered ecological equivalents. Polecats also have been used as investigational surrogates for black-footed ferrets, yet the similarities and differences between the 2 species are poorly understood. We contrasted activity patterns of radiotagged polecats and ferrets released onto ferret habitat. Ferrets tended to be nocturnal and most active after midnight. Polecats were not highly selective for any period of the day or night. Ferrets and polecats moved most during brightly moonlit nights. The diel activity pattern of ferrets was consistent with avoidance of coyotes (Canis latrans) and diurnal birds of prey. Similarly, polecat activity was consistent with avoidance of red foxes (Vulpes vulpes) in their natural range. Intraguild predation (including interference competition) is inferred as a selective force influencing behaviors of these mustelines. Examination of our data suggests that black-footed ferrets and Siberian polecats might be ecological equivalents but are not perfect surrogates. Nonetheless, polecats as surrogates for black-footed ferrets have provided critical insight needed, especially related to predation, to improve the success of ferret reintroductions. ?? 2011 American Society of Mammalogists.

  7. Breast Cancer Survival Defined by the ER/PR/HER2 Subtypes and a Surrogate Classification according to Tumor Grade and Immunohistochemical Bio markers

    International Nuclear Information System (INIS)

    Parise, C. A.; Caggiano, V.

    2014-01-01

    ER, PR, and HER2 are routinely available in breast cancer specimens. The purpose of this study is to contrast breast cancer-specific survival for the eight ER/PR/HER2 subtypes with survival of an immunohistochemical surrogate for the molecular subtype based on the ER/PR/HER2 subtypes and tumor grade. Methods. We identified 123,780 cases of stages 1-3 primary female invasive breast cancer from California Cancer Registry. The surrogate classification was derived using ER/PR/HER2 and tumor grade. Kaplan-Meier survival analysis and Cox proportional hazards modeling were used to assess differences in survival and risk of mortality for the ER/PR/HER2 subtypes and surrogate classification within each stage. Results. The luminal B/HER2− surrogate classification had a higher risk of mortality than the luminal B/HER2+ for all stages of disease. There was no difference in risk of mortality between the ER+/PR+/HER2− and ER+/PR+/HER2+ in stage 3. With one exception in stage 3, the ER-negative subtypes all had an increased risk of mortality when compared with the ER-positive subtypes. Conclusions. Assessment of survival using ER/PR/HER2 illustrates the heterogeneity of HER2+ subtypes. The surrogate classification provides clear separation in survival and adjusted mortality but underestimates the wide variability within the subtypes that make up the classification.

  8. 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

  9. Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks

    Science.gov (United States)

    Chen, Mingjie; Sun, Yunwei; Fu, Pengcheng; Carrigan, Charles R.; Lu, Zhiming; Tong, Charles H.; Buscheck, Thomas A.

    2013-08-01

    Hydraulic fracturing has been used widely to stimulate production of oil, natural gas, and geothermal energy in formations with low natural permeability. Numerical optimization of fracture stimulation often requires a large number of evaluations of objective functions and constraints from forward hydraulic fracturing models, which are computationally expensive and even prohibitive in some situations. Moreover, there are a variety of uncertainties associated with the pre-existing fracture distributions and rock mechanical properties, which affect the optimized decisions for hydraulic fracturing. In this study, a surrogate-based approach is developed for efficient optimization of hydraulic fracturing well design in the presence of natural-system uncertainties. The fractal dimension is derived from the simulated fracturing network as the objective for maximizing energy recovery sweep efficiency. The surrogate model, which is constructed using training data from high-fidelity fracturing models for mapping the relationship between uncertain input parameters and the fractal dimension, provides fast approximation of the objective functions and constraints. A suite of surrogate models constructed using different fitting methods is evaluated and validated for fast predictions. Global sensitivity analysis is conducted to gain insights into the impact of the input variables on the output of interest, and further used for parameter screening. The high efficiency of the surrogate-based approach is demonstrated for three optimization scenarios with different and uncertain ambient conditions. Our results suggest the critical importance of considering uncertain pre-existing fracture networks in optimization studies of hydraulic fracturing.

  10. Incorporating surrogate species and seascape connectivity to improve marine conservation outcomes.

    Science.gov (United States)

    Olds, Andrew D; Connolly, Rod M; Pitt, Kylie A; Maxwell, Paul S; Aswani, Shankar; Albert, Simon

    2014-08-01

    Conservation focuses on maintaining biodiversity and ecosystem functioning, but gaps in our knowledge of species biology and ecological processes often impede progress. For this reason, focal species and habitats are used as surrogates for multispecies conservation, but species-based approaches are not widely adopted in marine ecosystems. Reserves in the Solomon Islands were designed on the basis of local ecological knowledge to conserve bumphead parrotfish (Bolbometopon muricatum) and to protect food security and ecosystem functioning. Bumphead parrotfish are an iconic threatened species and may be a useful surrogate for multispecies conservation. They move across tropical seascapes throughout their life history, in a pattern of habitat use that is shared with many other species. We examined their value as a conservation surrogate and assessed the importance of seascape connectivity (i.e., the physical connectedness of patches in the seascape) among reefs, mangroves, and seagrass to marine reserve performance. Reserves were designed for bumphead parrotfish, but also enhanced the abundance of other species. Integration of local ecological knowledge and seascape connectivity enhanced the abundance of 17 other harvested fish species in local reserves. This result has important implications for ecosystem functioning and local villagers because many of these species perform important ecological processes and provide the foundation for extensive subsistence fisheries. Our findings suggest greater success in maintaining and restoring marine ecosystems may be achieved when they are managed to conserve surrogate species and preserve functional seascape connections. © 2014 Society for Conservation Biology.

  11. 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.

  12. 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.

  13. Breast Cancer Survival Defined by the ER/PR/HER2 Subtypes and a Surrogate Classification according to Tumor Grade and Immunohistochemical Biomarkers

    Directory of Open Access Journals (Sweden)

    Carol A. Parise

    2014-01-01

    Full Text Available Introduction. ER, PR, and HER2 are routinely available in breast cancer specimens. The purpose of this study is to contrast breast cancer-specific survival for the eight ER/PR/HER2 subtypes with survival of an immunohistochemical surrogate for the molecular subtype based on the ER/PR/HER2 subtypes and tumor grade. Methods. We identified 123,780 cases of stages 1–3 primary female invasive breast cancer from California Cancer Registry. The surrogate classification was derived using ER/PR/HER2 and tumor grade. Kaplan-Meier survival analysis and Cox proportional hazards modeling were used to assess differences in survival and risk of mortality for the ER/PR/HER2 subtypes and surrogate classification within each stage. Results. The luminal B/HER2− surrogate classification had a higher risk of mortality than the luminal B/HER2+ for all stages of disease. There was no difference in risk of mortality between the ER+/PR+/HER2− and ER+/PR+/HER2+ in stage 3. With one exception in stage 3, the ER-negative subtypes all had an increased risk of mortality when compared with the ER-positive subtypes. Conclusions. Assessment of survival using ER/PR/HER2 illustrates the heterogeneity of HER2+ subtypes. The surrogate classification provides clear separation in survival and adjusted mortality but underestimates the wide variability within the subtypes that make up the classification.

  14. Evaluating and interpreting cross-taxon congruence: Potential pitfalls and solutions

    Science.gov (United States)

    Gioria, Margherita; Bacaro, Giovanni; Feehan, John

    2011-05-01

    Characterizing the relationship between different taxonomic groups is critical to identify potential surrogates for biodiversity. Previous studies have shown that cross-taxa relationships are generally weak and/or inconsistent. The difficulties in finding predictive patterns have often been attributed to the spatial and temporal scales of these studies and on the differences in the measure used to evaluate such relationships (species richness versus composition). However, the choice of the analytical approach used to evaluate cross-taxon congruence inevitably represents a major source of variation. Here, we described the use of a range of methods that can be used to comprehensively assess cross-taxa relationships. To do so, we used data for two taxonomic groups, wetland plants and water beetles, collected from 54 farmland ponds in Ireland. Specifically, we used the Pearson correlation and rarefaction curves to analyse patterns in species richness, while Mantel tests, Procrustes analysis, and co-correspondence analysis were used to evaluate congruence in species composition. We compared the results of these analyses and we described some of the potential pitfalls associated with the use of each of these statistical approaches. Cross-taxon congruence was moderate to strong, depending on the choice of the analytical approach, on the nature of the response variable, and on local and environmental conditions. Our findings indicate that multiple approaches and measures of community structure are required for a comprehensive assessment of cross-taxa relationships. In particular, we showed that selection of surrogate taxa in conservation planning should not be based on a single statistic expressing the degree of correlation in species richness or composition. Potential solutions to the analytical issues associated with the assessment of cross-taxon congruence are provided and the implications of our findings in the selection of surrogates for biodiversity are discussed.

  15. 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...

  16. Five criteria for using a surrogate endpoint to predict treatment effect based on data from multiple previous trials.

    Science.gov (United States)

    Baker, Stuart G

    2018-02-20

    A surrogate endpoint in a randomized clinical trial is an endpoint that occurs after randomization and before the true, clinically meaningful, endpoint that yields conclusions about the effect of treatment on true endpoint. A surrogate endpoint can accelerate the evaluation of new treatments but at the risk of misleading conclusions. Therefore, criteria are needed for deciding whether to use a surrogate endpoint in a new trial. For the meta-analytic setting of multiple previous trials, each with the same pair of surrogate and true endpoints, this article formulates 5 criteria for using a surrogate endpoint in a new trial to predict the effect of treatment on the true endpoint in the new trial. The first 2 criteria, which are easily computed from a zero-intercept linear random effects model, involve statistical considerations: an acceptable sample size multiplier and an acceptable prediction separation score. The remaining 3 criteria involve clinical and biological considerations: similarity of biological mechanisms of treatments between the new trial and previous trials, similarity of secondary treatments following the surrogate endpoint between the new trial and previous trials, and a negligible risk of harmful side effects arising after the observation of the surrogate endpoint in the new trial. These 5 criteria constitute an appropriately high bar for using a surrogate endpoint to make a definitive treatment recommendation. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  17. Voices of African American, Caucasian, and Hispanic surrogates on the burdens of end-of-life decision making.

    Science.gov (United States)

    Braun, Ursula K; Beyth, Rebecca J; Ford, Marvella E; McCullough, Laurence B

    2008-03-01

    End-of-life decisions are frequently made by patients' surrogates. Race and ethnicity may affect such decision making. Few studies have described how different racial/ethnic groups experience end-of-life surrogate decision making. To describe the self-reported experience the self-reported experience of African-American, Caucasian, and Hispanic surrogate decision makers of seriously ill patients and to examine the relationship of race, ethnicity, and culture to that experience. Purposive sample to include racial/ethnic minorities in a qualitative study using focus group interviews. The participants of the study were 44 experienced, mostly female, surrogate decision makers for older veterans. Transcripts were qualitatively analyzed to identify major themes, with particular attention to themes that might be unique to each of the three groups. The experience of burden of end-of-life decision making was similar in all three groups. This burden in its medical, personal, and familial dimensions is compounded by uncertainty about prognosis and the patient's preferences. Racial/ethnic variations of responses to this burden concerned the physician-family relationship, religion and faith, and past experiences with race/ethnicity concordant versus non-concordant physicians. Regardless of race/ethnicity, surrogates for seriously ill patients appeared to experience increased significant, multidimensional burdens of decision making under conditions of uncertainty about a patient's preferences. This aspect of the burden of surrogate decision making may not be fully appreciated by physicians. Physicians should identify and be especially attentive to strategies used by surrogates, which may vary by race/ethnicity, to reduce the uncertainty about a patient's preferences and thus the burden of surrogate decision making to assist them in this difficult process.

  18. Soil solution extraction techniques for microbial ecotoxicity testing: a comparative evaluation.

    Science.gov (United States)

    Tiensing, T; Preston, S; Strachan, N; Paton, G I

    2001-02-01

    The suitability of two different techniques (centrifugation and Rhizon sampler) for obtaining the interstitial pore water of soil (soil solution), integral to the ecotoxicity assessment of metal contaminated soil, were investigated by combining chemical analyses and a luminescence-based microbial biosensor. Two different techniques, centrifugation and Rhizon sampler, were used to extract the soil solution from Insch (a loamy sand) and Boyndie (a sandy loam) soils, which had been amended with different concentrations of Zn and Cd. The concentrations of dissolved organic carbon (DOC), major anions (F- , CI-, NO3, SO4(2-)) and major cations (K+, Mg2+, Ca2+) in the soil solutions varied depending on the extraction technique used. Overall, the concentrations of Zn and Cd were significantly higher in the soil solution extracted using the centrifugation technique compared with that extracted using the Rhizon sampler technique. Furthermore, the differences observed between the two extraction techniques depended on the type of soil from which the solution was being extracted. The luminescence-based biosensor Escherichia coli HB101 pUCD607 was shown to respond to the free metal concentrations in the soil solutions and showed that different toxicities were associated with each soil, depending on the technique used to extract the soil solution. This study highlights the need to characterise the type of extraction technique used to obtain the soil solution for ecotoxicity testing in order that a representative ecotoxicity assessment can be carried out.

  19. WE-AB-303-11: Verification of a Deformable 4DCT Motion Model for Lung Tumor Tracking Using Different Driving Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Woelfelschneider, J [University Hospital Erlangen, Erlangen, DE (Germany); Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, DE (Germany); Seregni, M; Fassi, A; Baroni, G; Riboldi, M [Politecnico di Milano, Milano (Italy); Bert, C [University Hospital Erlangen, Erlangen, DE (Germany); Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, DE (Germany); GSI - Helmholtz Centre for Heavy Ion Research, Darmstadt, DE (Germany)

    2015-06-15

    Purpose: Tumor tracking is an advanced technique to treat intra-fractionally moving tumors. The aim of this study is to validate a surrogate-driven model based on four-dimensional computed tomography (4DCT) that is able to predict CT volumes corresponding to arbitrary respiratory states. Further, the comparison of three different driving surrogates is evaluated. Methods: This study is based on multiple 4DCTs of two patients treated for bronchial carcinoma and metastasis. Analyses for 18 additional patients are currently ongoing. The motion model was estimated from the planning 4DCT through deformable image registration. To predict a certain phase of a follow-up 4DCT, the model considers for inter-fractional variations (baseline correction) and intra-fractional respiratory parameters (amplitude and phase) derived from surrogates. In this evaluation, three different approaches were used to extract the motion surrogate: for each 4DCT phase, the 3D thoraco-abdominal surface motion, the body volume and the anterior-posterior motion of a virtual single external marker defined on the sternum were investigated. The estimated volumes resulting from the model were compared to the ground-truth clinical 4DCTs using absolute HU differences in the lung volume and landmarks localized using the Scale Invariant Feature Transform (SIFT). Results: The results show absolute HU differences between estimated and ground-truth images with median values limited to 55 HU and inter-quartile ranges (IQR) lower than 100 HU. Median 3D distances between about 1500 matching landmarks are below 2 mm for 3D surface motion and body volume methods. The single marker surrogates Result in increased median distances up to 0.6 mm. Analyses for the extended database incl. 20 patients are currently in progress. Conclusion: The results depend mainly on the image quality of the initial 4DCTs and the deformable image registration. All investigated surrogates can be used to estimate follow-up 4DCT phases

  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. Economic Statistical Design of Variable Sampling Interval X¯$\\overline X $ Control Chart Based on Surrogate Variable Using Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Lee Tae-Hoon

    2016-12-01

    Full Text Available In many cases, a X¯$\\overline X $ control chart based on a performance variable is used in industrial fields. Typically, the control chart monitors the measurements of a performance variable itself. However, if the performance variable is too costly or impossible to measure, and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we present a model for the economic statistical design of a VSI (Variable Sampling Interval X¯$\\overline X $ control chart using a surrogate variable that is linearly correlated with the performance variable. We derive the total average profit model from an economic viewpoint and apply the model to a Very High Temperature Reactor (VHTR nuclear fuel measurement system and derive the optimal result using genetic algorithms. Compared with the control chart based on a performance variable, the proposed model gives a larger expected net income per unit of time in the long-run if the correlation between the performance variable and the surrogate variable is relatively high. The proposed model was confined to the sample mean control chart under the assumption that a single assignable cause occurs according to the Poisson process. However, the model may also be extended to other types of control charts using a single or multiple assignable cause assumptions such as VSS (Variable Sample Size X¯$\\overline X $ control chart, EWMA, CUSUM charts and so on.

  2. Evaluating β Diversity as a Surrogate for Species Representation at Fine Scale.

    Directory of Open Access Journals (Sweden)

    Paul Beier

    Full Text Available Species turnover or β diversity is a conceptually attractive surrogate for conservation planning. However, there has been only 1 attempt to determine how well sites selected to maximize β diversity represent species, and that test was done at a scale too coarse (2,500 km2 sites to inform most conservation decisions. We used 8 plant datasets, 3 bird datasets, and 1 mammal dataset to evaluate whether sites selected to span β diversity will efficiently represent species at finer scale (sites sizes < 1 ha to 625 km2. We used ordinations to characterize dissimilarity in species assemblages (β diversity among plots (inventory data or among grid cells (atlas data. We then selected sites to maximize β diversity and used the Species Accumulation Index, SAI, to evaluate how efficiently the surrogate (selecting sites for maximum β diversity represented species in the same taxon. Across all 12 datasets, sites selected for maximum β diversity represented species with a median efficiency of 24% (i.e., the surrogate was 24% more effective than random selection of sites, and an interquartile range of 4% to 41% efficiency. β diversity was a better surrogate for bird datasets than for plant datasets, and for atlas datasets with 10-km to 14-km grid cells than for atlas datasets with 25-km grid cells. We conclude that β diversity is more than a mere descriptor of how species are distributed on the landscape; in particular β diversity might be useful to maximize the complementarity of a set of sites. Because we tested only within-taxon surrogacy, our results do not prove that β diversity is useful for conservation planning. But our results do justify further investigation to identify the circumstances in which β diversity performs well, and to evaluate it as a cross-taxon surrogate.

  3. 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.

  4. The Use of Surrogate Data in Demographic Population Viability Analysis: A Case Study of California Sea Lions.

    Directory of Open Access Journals (Sweden)

    Claudia J Hernández-Camacho

    Full Text Available Reliable data necessary to parameterize population models are seldom available for imperiled species. As an alternative, data from populations of the same species or from ecologically similar species have been used to construct models. In this study, we evaluated the use of demographic data collected at one California sea lion colony (Los Islotes to predict the population dynamics of the same species from two other colonies (San Jorge and Granito in the Gulf of California, Mexico, for which demographic data are lacking. To do so, we developed a stochastic demographic age-structured matrix model and conducted a population viability analysis for each colony. For the Los Islotes colony we used site-specific pup, juvenile, and adult survival probabilities, as well as birth rates for older females. For the other colonies, we used site-specific pup and juvenile survival probabilities, but used surrogate data from Los Islotes for adult survival probabilities and birth rates. We assessed these models by comparing simulated retrospective population trajectories to observed population trends based on count data. The projected population trajectories approximated the observed trends when surrogate data were used for one colony but failed to match for a second colony. Our results indicate that species-specific and even region-specific surrogate data may lead to erroneous conservation decisions. These results highlight the importance of using population-specific demographic data in assessing extinction risk. When vital rates are not available and immediate management actions must be taken, in particular for imperiled species, we recommend the use of surrogate data only when the populations appear to have similar population trends.

  5. The Use of Surrogate Data in Demographic Population Viability Analysis: A Case Study of California Sea Lions

    Science.gov (United States)

    2015-01-01

    Reliable data necessary to parameterize population models are seldom available for imperiled species. As an alternative, data from populations of the same species or from ecologically similar species have been used to construct models. In this study, we evaluated the use of demographic data collected at one California sea lion colony (Los Islotes) to predict the population dynamics of the same species from two other colonies (San Jorge and Granito) in the Gulf of California, Mexico, for which demographic data are lacking. To do so, we developed a stochastic demographic age-structured matrix model and conducted a population viability analysis for each colony. For the Los Islotes colony we used site-specific pup, juvenile, and adult survival probabilities, as well as birth rates for older females. For the other colonies, we used site-specific pup and juvenile survival probabilities, but used surrogate data from Los Islotes for adult survival probabilities and birth rates. We assessed these models by comparing simulated retrospective population trajectories to observed population trends based on count data. The projected population trajectories approximated the observed trends when surrogate data were used for one colony but failed to match for a second colony. Our results indicate that species-specific and even region-specific surrogate data may lead to erroneous conservation decisions. These results highlight the importance of using population-specific demographic data in assessing extinction risk. When vital rates are not available and immediate management actions must be taken, in particular for imperiled species, we recommend the use of surrogate data only when the populations appear to have similar population trends. PMID:26413746

  6. Effectiveness of Fire and Fire Surrogate Treatments For Controlling Wildfire Behavior in Piedmont Forests: A Simulation Study

    Science.gov (United States)

    Helen H. Mohr; Thomas A. Waldrop; Sandra Rideout; Ross J. Phillips; Charles T. Flint

    2004-01-01

    The need for fuel reduction has increased in United States forests due to decades of fire exclusion. Excessive fuel buildup has led to uncharacteristically severe fires in areas with historically short-interval, low-to-moderate-intensity fire regimes. The National Fire and Fire Surrogate (NFFS) Study compared the impacts of three fuel-reduction treatments on numerous...

  7. A reduced order aerothermodynamic modeling framework for hypersonic vehicles based on surrogate and POD

    Directory of Open Access Journals (Sweden)

    Chen Xin

    2015-10-01

    Full Text Available Aerothermoelasticity is one of the key technologies for hypersonic vehicles. Accurate and efficient computation of the aerothermodynamics is one of the primary challenges for hypersonic aerothermoelastic analysis. Aimed at solving the shortcomings of engineering calculation, computation fluid dynamics (CFD and experimental investigation, a reduced order modeling (ROM framework for aerothermodynamics based on CFD predictions using an enhanced algorithm of fast maximin Latin hypercube design is developed. Both proper orthogonal decomposition (POD and surrogate are considered and compared to construct ROMs. Two surrogate approaches named Kriging and optimized radial basis function (ORBF are utilized to construct ROMs. Furthermore, an enhanced algorithm of fast maximin Latin hypercube design is proposed, which proves to be helpful to improve the precisions of ROMs. Test results for the three-dimensional aerothermodynamic over a hypersonic surface indicate that: the ROMs precision based on Kriging is better than that by ORBF, ROMs based on Kriging are marginally more accurate than ROMs based on POD-Kriging. In a word, the ROM framework for hypersonic aerothermodynamics has good precision and efficiency.

  8. SU-C-BRF-07: A Pattern Fusion Algorithm for Multi-Step Ahead Prediction of Surrogate Motion

    International Nuclear Information System (INIS)

    Zawisza, I; Yan, H; Yin, F

    2014-01-01

    Purpose: To assure that tumor motion is within the radiation field during high-dose and high-precision radiosurgery, real-time imaging and surrogate monitoring are employed. These methods are useful in providing real-time tumor/surrogate motion but no future information is available. In order to anticipate future tumor/surrogate motion and track target location precisely, an algorithm is developed and investigated for estimating surrogate motion multiple-steps ahead. Methods: The study utilized a one-dimensional surrogate motion signal divided into three components: (a) training component containing the primary data including the first frame to the beginning of the input subsequence; (b) input subsequence component of the surrogate signal used as input to the prediction algorithm: (c) output subsequence component is the remaining signal used as the known output of the prediction algorithm for validation. The prediction algorithm consists of three major steps: (1) extracting subsequences from training component which best-match the input subsequence according to given criterion; (2) calculating weighting factors from these best-matched subsequence; (3) collecting the proceeding parts of the subsequences and combining them together with assigned weighting factors to form output. The prediction algorithm was examined for several patients, and its performance is assessed based on the correlation between prediction and known output. Results: Respiratory motion data was collected for 20 patients using the RPM system. The output subsequence is the last 50 samples (∼2 seconds) of a surrogate signal, and the input subsequence was 100 (∼3 seconds) frames prior to the output subsequence. Based on the analysis of correlation coefficient between predicted and known output subsequence, the average correlation is 0.9644±0.0394 and 0.9789±0.0239 for equal-weighting and relative-weighting strategies, respectively. Conclusion: Preliminary results indicate that the prediction

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Efficient surrogate models for reliability analysis of systems with multiple failure modes

    International Nuclear Information System (INIS)

    Bichon, Barron J.; McFarland, John M.; Mahadevan, Sankaran

    2011-01-01

    Despite many advances in the field of computational reliability analysis, the efficient estimation of the reliability of a system with multiple failure modes remains a persistent challenge. Various sampling and analytical methods are available, but they typically require accepting a tradeoff between accuracy and computational efficiency. In this work, a surrogate-based approach is presented that simultaneously addresses the issues of accuracy, efficiency, and unimportant failure modes. The method is based on the creation of Gaussian process surrogate models that are required to be locally accurate only in the regions of the component limit states that contribute to system failure. This approach to constructing surrogate models is demonstrated to be both an efficient and accurate method for system-level reliability analysis. - Highlights: → Extends efficient global reliability analysis to systems with multiple failure modes. → Constructs locally accurate Gaussian process models of each response. → Highly efficient and accurate method for assessing system reliability. → Effectiveness is demonstrated on several test problems from the literature.

  14. Surrogates based multi-criteria predesign methodology of Sodium-cooled Fast Reactor cores – Application to CFV-like cores

    Energy Technology Data Exchange (ETDEWEB)

    Fabbris, Olivier [CEA DEN/DER/SESI, 13108 Saint-Paul-Lez-Durance (France); Dardour, Saied, E-mail: saied.dardour@cea.fr [CEA DEN/DER/SESI, 13108 Saint-Paul-Lez-Durance (France); Blaise, Patrick [CEA DEN/DER/SPEX, 13108 Saint-Paul-Lez-Durance (France); Ferrasse, Jean-Henry [Aix-Marseille Université, CNRS, ECM, M2P2 UMR 7340, 13451 Marseille (France); Saez, Manuel [CEA DEN/DER/SESI, 13108 Saint-Paul-Lez-Durance (France)

    2016-08-15

    degrees of freedom, such as five Pu enrichments compared to two, or different pellet diameters have been performed. Additional configurations are then found by the surrogate models, improving simultaneously all performances of the CFV-v1 configuration.

  15. 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

  16. Surrogates based multi-criteria predesign methodology of Sodium-cooled Fast Reactor cores – Application to CFV-like cores

    International Nuclear Information System (INIS)

    Fabbris, Olivier; Dardour, Saied; Blaise, Patrick; Ferrasse, Jean-Henry; Saez, Manuel

    2016-01-01

    degrees of freedom, such as five Pu enrichments compared to two, or different pellet diameters have been performed. Additional configurations are then found by the surrogate models, improving simultaneously all performances of the CFV-v1 configuration.

  17. A new formulation of physical surrogates of FACE A gasoline fuel based on heating and evaporation characteristics

    KAUST Repository

    Elwardani, Ahmed Elsaid; Sazhin, S.S.; Im, Hong G.

    2016-01-01

    The US Department of Energy has formulated various sets of gasoline fuels, called fuels for advanced combustion engines (FACE), which are consistent in composition and properties. The analysis of heating and evaporation of FACE A gasoline fuel (paraffin-rich) is studied by replacing the 66 components with 19 components to represent this fuel. The reduction in the number of components is based on merging components from the same chemical groups and having the same chemical formula, which have very close thermophysical properties; the components with the highest initial compositions are chosen to be the representative components. Modelling of heating and evaporation of FACE A gasoline fuel and various surrogates is carried out based on the effective thermal conductivity/effective diffusivity model (ETC/ED). The model takes into account the effect of finite liquid thermal conductivity, finite liquid mass diffusivity and recirculation inside the droplets due to their non-zero velocities relative to the ambient air. Four surrogates of FACE A found in the literature are used in the analysis. These surrogates include the five component surrogate chosen for its ability to match the ignition delay time of the FACE A gasoline fuel (Surr1), the primary reference fuel surrogate (PRF84) that matches the research octane number (RON) of FACE A, the one that matches hydrogen-to-carbon ratio (H/C), RON, density and distillation curve with FACE A (Surr2), and the one that matches the RON based on mole fraction linear blending (Surr3). It is shown that these surrogates cannot predict adequately the time evolution of surface temperatures and radii of FACE A droplets. New 'physical' surrogates with 8, 7 and 6 components (Surr4, Surr5, and Surr6) are introduced to match the evaporation characteristics of FACE A. It is found that Surr5 (7 components surrogate) can predict droplet lifetime and time evolution of surface temperature of a FACE A droplet with errors of up to 5% and 0

  18. A new formulation of physical surrogates of FACE A gasoline fuel based on heating and evaporation characteristics

    KAUST Repository

    Elwardani, Ahmed Elsaid

    2016-02-19

    The US Department of Energy has formulated various sets of gasoline fuels, called fuels for advanced combustion engines (FACE), which are consistent in composition and properties. The analysis of heating and evaporation of FACE A gasoline fuel (paraffin-rich) is studied by replacing the 66 components with 19 components to represent this fuel. The reduction in the number of components is based on merging components from the same chemical groups and having the same chemical formula, which have very close thermophysical properties; the components with the highest initial compositions are chosen to be the representative components. Modelling of heating and evaporation of FACE A gasoline fuel and various surrogates is carried out based on the effective thermal conductivity/effective diffusivity model (ETC/ED). The model takes into account the effect of finite liquid thermal conductivity, finite liquid mass diffusivity and recirculation inside the droplets due to their non-zero velocities relative to the ambient air. Four surrogates of FACE A found in the literature are used in the analysis. These surrogates include the five component surrogate chosen for its ability to match the ignition delay time of the FACE A gasoline fuel (Surr1), the primary reference fuel surrogate (PRF84) that matches the research octane number (RON) of FACE A, the one that matches hydrogen-to-carbon ratio (H/C), RON, density and distillation curve with FACE A (Surr2), and the one that matches the RON based on mole fraction linear blending (Surr3). It is shown that these surrogates cannot predict adequately the time evolution of surface temperatures and radii of FACE A droplets. New \\'physical\\' surrogates with 8, 7 and 6 components (Surr4, Surr5, and Surr6) are introduced to match the evaporation characteristics of FACE A. It is found that Surr5 (7 components surrogate) can predict droplet lifetime and time evolution of surface temperature of a FACE A droplet with errors of up to 5% and 0

  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. Surrogate mothers 10 years on: a longitudinal study of psychological well-being and relationships with the parents and child.

    Science.gov (United States)

    Jadva, V; Imrie, S; Golombok, S

    2015-02-01

    How do the psychological health and experiences of surrogate mothers change from 1 year to 10 years following the birth of the surrogacy child? The psychological well-being of surrogate mothers did not change 10 years following the birth, with all remaining positive about the surrogacy arrangement and the majority continuing to report good mental health. Studies have found that surrogates may find the weeks following the birth difficult, but do not experience psychological problems 6 months or 1 year later. Research has also shown that surrogates can form close relationships with the intended parents during the pregnancy which may continue after the birth. This study used a prospective longitudinal design, in which 20 surrogates were seen at two time points: 1 year following the birth of the surrogacy child and 10 years later. The 20 surrogates (representing 59% of the original sample) participated in a semi-structured interview and completed self-report questionnaires. Eleven surrogates were gestational carriers and nine surrogates had used their own oocyte (genetic surrogacy). Four were previously known to the intended parents and 16 were previously not known. Ten years following the birth of the surrogacy child, surrogate mothers scored within the normal range for self-esteem and did not show signs of depression as measured by the Beck Depression Inventory. Marital quality remained positive over time. All surrogates reported that their expectations of their relationship with the intended parents had been either met or exceeded and most reported positive feelings towards the child. In terms of expectations for the future, most surrogates reported that they would like to maintain contact or would be available to the child if the child wished to contact them. None expressed regrets about their involvement in surrogacy. The sample size of this study was small and the women may not be representative of all surrogates. Therefore the extent to which these findings can

  1. 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.

  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. 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.

  4. Comparing the creativity of children's design solutions based on expert assessment

    NARCIS (Netherlands)

    Thang, B.; Sluis - Thiescheffer, R.J.W.; Bekker, M.M.; Eggen, J.H.; Vermeeren, A.P.O.S.; Ridder, de H.

    2008-01-01

    LOBBI Netherlands Consortium Subscribe (Full Service) Register (Limited Service, Free) Login Search: The ACM Digital Library The Guide Feedback Comparing the creativity of children's design solutions based on expert assessment Full text Pdf (3.04 MB) Source Interaction Design and Children archive

  5. 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.

  6. 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 ...

  7. 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...

  8. Triazole-linked DNA as a primer surrogate in the synthesis of first-strand cDNA.

    Science.gov (United States)

    Fujino, Tomoko; Yasumoto, Ken-ichi; Yamazaki, Naomi; Hasome, Ai; Sogawa, Kazuhiro; Isobe, Hiroyuki

    2011-11-04

    A phosphate-eliminated nonnatural oligonucleotide serves as a primer surrogate in reverse transcription reaction of mRNA. Despite of the nonnatural triazole linkages in the surrogate, the reverse transcriptase effectively elongated cDNA sequences on the 3'-downstream of the primer by transcription of the complementary sequence of mRNA. A structure-activity comparison with the reference natural oligonucleotides shows the superior priming activity of the surrogate containing triazole-linkages. The nonnatural linkages also protect the transcribed cDNA from digestion reactions with 5'-exonuclease and enable us to remove noise transcripts of unknown origins. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Surrogate endpoints for overall survival in digestive oncology trials: which candidates? A questionnaires survey among clinicians and methodologists

    International Nuclear Information System (INIS)

    Methy, Nicolas; Bedenne, Laurent; Bonnetain, Franck

    2010-01-01

    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 opinion on surrogacy and quality of life (QoL). In 2007 and 2008, self administered sequential questionnaires were sent to a panel of French clinicians and methodologists involved in the conduct of cancer clinical trials. In the first questionnaire, panellists were asked to choose the most important characteristics defining a surrogate among six proposals, to give advantages and drawbacks of the surrogates, and to answer questions about their validation and use. Then they had to suggest potential surrogate endpoints for OS in each of the following tumour sites: oesophagus, stomach, liver, pancreas, biliary tract, lymphoma, colon, rectum, and anus. They finally gave their opinion on QoL as surrogate endpoint. In the second questionnaire, they had to classify the previously proposed candidate surrogates from the most (position N1) to the least relevant in their opinion. Frequency at which the endpoints were chosen as first, second or third most relevant surrogates was calculated and served as final ranking. Response rate was 30% (24/80) in the first round and 20% (16/80) in the second one. Participants highlighted key points concerning surrogacy. In particular, they reminded that a surrogate endpoint is expected to predict clinical benefit in a well-defined therapeutic situation. Half of them thought it was not relevant to study QoL as surrogate for OS. DFS, in the neoadjuvant settings or early stages, and PFS, in the non operable or metastatic settings, were ranked first, with a frequency of more than

  10. Surrogate endpoints for overall survival in digestive oncology trials: which candidates? A questionnaires survey among clinicians and methodologists.

    Science.gov (United States)

    Methy, Nicolas; Bedenne, Laurent; Bonnetain, Franck

    2010-06-10

    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 opinion on surrogacy and quality of life (QoL). In 2007 and 2008, self administered sequential questionnaires were sent to a panel of French clinicians and methodologists involved in the conduct of cancer clinical trials. In the first questionnaire, panellists were asked to choose the most important characteristics defining a surrogate among six proposals, to give advantages and drawbacks of the surrogates, and to answer questions about their validation and use. Then they had to suggest potential surrogate endpoints for OS in each of the following tumour sites: oesophagus, stomach, liver, pancreas, biliary tract, lymphoma, colon, rectum, and anus. They finally gave their opinion on QoL as surrogate endpoint. In the second questionnaire, they had to classify the previously proposed candidate surrogates from the most (position #1) to the least relevant in their opinion.Frequency at which the endpoints were chosen as first, second or third most relevant surrogates was calculated and served as final ranking. Response rate was 30% (24/80) in the first round and 20% (16/80) in the second one. Participants highlighted key points concerning surrogacy. In particular, they reminded that a surrogate endpoint is expected to predict clinical benefit in a well-defined therapeutic situation. Half of them thought it was not relevant to study QoL as surrogate for OS.DFS, in the neoadjuvant settings or early stages, and PFS, in the non operable or metastatic settings, were ranked first, with a frequency of more than 69

  11. Using surrogate biomarkers to improve measurement error models in nutritional epidemiology

    Science.gov (United States)

    Keogh, Ruth H; White, Ian R; Rodwell, Sheila A

    2013-01-01

    Nutritional epidemiology relies largely on self-reported measures of dietary intake, errors in which give biased estimated diet–disease associations. Self-reported measurements come from questionnaires and food records. Unbiased biomarkers are scarce; however, surrogate biomarkers, which are correlated with intake but not unbiased, can also be useful. It is important to quantify and correct for the effects of measurement error on diet–disease associations. Challenges arise because there is no gold standard, and errors in self-reported measurements are correlated with true intake and each other. We describe an extended model for error in questionnaire, food record, and surrogate biomarker measurements. The focus is on estimating the degree of bias in estimated diet–disease associations due to measurement error. In particular, we propose using sensitivity analyses to assess the impact of changes in values of model parameters which are usually assumed fixed. The methods are motivated by and applied to measures of fruit and vegetable intake from questionnaires, 7-day diet diaries, and surrogate biomarker (plasma vitamin C) from over 25000 participants in the Norfolk cohort of the European Prospective Investigation into Cancer and Nutrition. Our results show that the estimated effects of error in self-reported measurements are highly sensitive to model assumptions, resulting in anything from a large attenuation to a small amplification in the diet–disease association. Commonly made assumptions could result in a large overcorrection for the effects of measurement error. Increased understanding of relationships between potential surrogate biomarkers and true dietary intake is essential for obtaining good estimates of the effects of measurement error in self-reported measurements on observed diet–disease associations. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23553407

  12. 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.

  13. Iran's experience with surrogate motherhood: an Islamic view and ethical concerns.

    Science.gov (United States)

    Aramesh, K

    2009-05-01

    Gestational surrogacy as a treatment for infertility is being practised in some well-known medical institutions in Tehran and some other cities in Iran. While the majority of Muslims in the world are Sunni, the majority of Iranians are Shiite. Most Sunni scholars do not permit surrogate motherhood, since it involves introducing the sperm of a man into the uterus of a woman to whom he is not married. Most Shiite scholars, however, have issued jurisprudential decrees (fatwas) that allow surrogate motherhood as a treatment for infertility, albeit only for legal couples. They regard this practice as transferring an embryo or fetus from one womb to another, which is not forbidden in Shiite jurisprudence. Nevertheless, there are some controversies concerning some issues such as kinship and inheritance. The main ethical concern of Iran's experience with gestational surrogacy is the monetary relation between the intended couple and the surrogate mother. While monetary remuneration is practised in Iran and allowed by religious authorities, it seems to suffer from ethical problems. This article proposes that this kind of monetary relation should be modified and limited to reimbursement of normal costs. Such modification requires new legislation and religious decrees.

  14. A longitudinal pre-pregnancy to post-delivery comparison of genetic and gestational surrogate and intended mothers: confidence and genealogy.

    Science.gov (United States)

    Van Den Akker, Olga B A

    2005-12-01

    For women opting to use surrogacy to overcome subfertility, a choice can be made to have a genetically related or unrelated baby. Similarly, women opting to become surrogate mothers also have to choose to gestate and relinquish a genetically related or unrelated baby. This study explored the cognitions behind the initial choices made and determined the strength of those cognitions six months post-delivery of the surrogate baby. Surrogate and Intended mothers (N=81) undergoing Artificial Insemination (AI, genetic) or Embryo Transfer (ET, gestational) were studied separately (four groups) at the start of their surrogate arrangement and those with a positive outcome (n=34) were re-interviewed at six months post-relinquishment. There were significant differences between surrogate and intended mothers in their confidence about the arrangement. Beliefs about the importance of a genetic link were predictors of ET arrangements. Responses were consistent over a one and a half-year study period. The ethical and clinical implications of the results are discussed in relation to appropriate self-selection and confidence with the surrogate process and the importance of genetic offspring.

  15. Treatment studies of plutonium-bearing INEEL waste surrogates in a bench-scale arc furnace

    International Nuclear Information System (INIS)

    Freeman, C.J.

    1997-05-01

    Since 1989, the Subsurface Disposal Area (SDA) at the Idaho National Environmental and Engineering Laboratory (INEEL) has been included on the National Priority List for remediation. Arc- and plasma-heated furnaces are being considered for converting the radioactive mixed waste buried in the SDA to a stabilized-vitreous form. Nonradioactive, surrogate SDA wastes have been melted during tests in these types of furnaces, but data are needed on the behavior of transuranic (TRU) constituents, primarily plutonium, during thermal treatment. To begin collecting this data, plutonium-spiked SDA surrogates were processed in a bench-scale arc furnace to quantify the fate of the plutonium and other hazardous and nonhazardous metals. Test conditions included elevating the organic, lead, chloride, and sodium contents of the surrogates. Blends having higher organic contents caused furnace power levels to fluctuate. An organic content corresponding to 50% INEEL soil in a soil-waste blend was the highest achievable before power fluctuations made operating conditions unacceptable. The glass, metal, and off-gas solids produced from each surrogate blend tested were analyzed for elemental (including plutonium) content and the partitioning of each element to the corresponding phase was calculated

  16. Treatment studies of plutonium-bearing INEEL waste surrogates in a bench-scale arc furnace

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, C.J.

    1997-05-01

    Since 1989, the Subsurface Disposal Area (SDA) at the Idaho National Environmental and Engineering Laboratory (INEEL) has been included on the National Priority List for remediation. Arc- and plasma-heated furnaces are being considered for converting the radioactive mixed waste buried in the SDA to a stabilized-vitreous form. Nonradioactive, surrogate SDA wastes have been melted during tests in these types of furnaces, but data are needed on the behavior of transuranic (TRU) constituents, primarily plutonium, during thermal treatment. To begin collecting this data, plutonium-spiked SDA surrogates were processed in a bench-scale arc furnace to quantify the fate of the plutonium and other hazardous and nonhazardous metals. Test conditions included elevating the organic, lead, chloride, and sodium contents of the surrogates. Blends having higher organic contents caused furnace power levels to fluctuate. An organic content corresponding to 50% INEEL soil in a soil-waste blend was the highest achievable before power fluctuations made operating conditions unacceptable. The glass, metal, and off-gas solids produced from each surrogate blend tested were analyzed for elemental (including plutonium) content and the partitioning of each element to the corresponding phase was calculated.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. Psychological trait and state characteristics, social support and attitudes to the surrogate pregnancy and baby.

    Science.gov (United States)

    van den Akker, Olga B A

    2007-08-01

    Personality differences between surrogate mothers (SMs) who gestate and relinquish and intended mothers (IMs) who commission a genetically related or unrelated baby have been unexplored in the UK. Furthermore, the psychological effects of the arrangement have not been determined in a prospective longitudinal study, making this the first quantitative report of psychological functioning in SMs and IMs. SMs and IMs (n = 81: 61 surrogate, 20 intended) undergoing genetic or gestational surrogacy (4 groups) were assessed by postal questionnaire during the first, second and third trimesters of pregnancy. Those with a positive outcome were assessed again in the first week, at 6 weeks and 6 months post-delivery of the surrogate baby. There were no significant differences between or within SM and IM groups on personality characteristics. Social support, marital harmony and state anxiety differed significantly (to P pregnancy and the baby were also observed between groups during pregnancy (to P surrogate arrangement are notable and occur over an extended period of time. It also shows that psychological screening and support prior to, during and following surrogacy is indicated.

  2. Surrogate endpoints for overall survival in digestive oncology trials: which candidates? A questionnaires survey among clinicians and methodologists

    Directory of Open Access Journals (Sweden)

    Bonnetain Franck

    2010-06-01

    Full Text Available 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 opinion on surrogacy and quality of life (QoL. Methods In 2007 and 2008, self administered sequential questionnaires were sent to a panel of French clinicians and methodologists involved in the conduct of cancer clinical trials. In the first questionnaire, panellists were asked to choose the most important characteristics defining a surrogate among six proposals, to give advantages and drawbacks of the surrogates, and to answer questions about their validation and use. Then they had to suggest potential surrogate endpoints for OS in each of the following tumour sites: oesophagus, stomach, liver, pancreas, biliary tract, lymphoma, colon, rectum, and anus. They finally gave their opinion on QoL as surrogate endpoint. In the second questionnaire, they had to classify the previously proposed candidate surrogates from the most (position #1 to the least relevant in their opinion. Frequency at which the endpoints were chosen as first, second or third most relevant surrogates was calculated and served as final ranking. Results Response rate was 30% (24/80 in the first round and 20% (16/80 in the second one. Participants highlighted key points concerning surrogacy. In particular, they reminded that a surrogate endpoint is expected to predict clinical benefit in a well-defined therapeutic situation. Half of them thought it was not relevant to study QoL as surrogate for OS. DFS, in the neoadjuvant settings or early stages, and PFS, in the non operable or metastatic settings

  3. 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...

  4. 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

  5. Repeated use of surrogate mothers for embryo transfer in the mouse.

    Science.gov (United States)

    Kolbe, Thomas; Palme, Rupert; Touma, Chadi; Rülicke, Thomas

    2012-01-01

    Embryo transfer in mice is a crucial technique for generation of transgenic animals, rederivation of contaminated lines, and revitalization of cryopreserved strains, and it is a key component of assisted reproduction techniques. It is common practice to use females only once as surrogate mothers. However, their reuse for a second embryo transfer could provide hygienic and economic advantages and conform to the concept of the 3Rs (replace, reduce, refine). This investigation evaluated the potential for a second embryo transfer in terms of feasibility, reproductive results, and experimental burden for the animal. Virgin female ICR mice (age 8-16 wk) were used as recipients for the first embryo transfer. Immediately after weaning of the first litter, a second surgical embryo transfer was performed into the same oviduct. Virgin females of comparable age to the reused mothers served as controls and underwent the same procedure. The first surgery did not affect the success of the second embryo transfer. Histological sections showed excellent wound healing without relevant impairment of involved tissues. We observed no differences in pregnancy rates or litter sizes between the transfer groups. Most importantly, we found no change in behavior indicating reduced well-being and no increase of corticosterone metabolites in the feces of surrogate mothers reused for a second embryo transfer. We conclude that a second embryo transfer in mice is feasible with regard to reproductive and animal welfare aspects.

  6. An evaluation of culture results during treatment for tuberculosis as surrogate endpoints for treatment failure and relapse.

    Directory of Open Access Journals (Sweden)

    Patrick P J Phillips

    Full Text Available It is widely acknowledged that new regimens are urgently needed for the treatment of tuberculosis. The primary endpoint in the Phase III trials is a composite outcome of failure at the end of treatment or relapse after stopping treatment. Such trials are usually both long and expensive. Valid surrogate endpoints measured during or at the end of treatment could dramatically reduce both the time and cost of assessing the effectiveness of new regimens. The objective of this study was to evaluate sputum culture results on solid media during treatment as surrogate endpoints for poor outcome. Data were obtained from twelve randomised controlled trials conducted by the British Medical Research Council in the 1970s and 80s in East Africa and East Asia, consisting of 6974 participants and 49 different treatment regimens. The month two culture result was shown to be a poor surrogate in East Africa but a good surrogate in Hong Kong. In contrast, the month three culture was a good surrogate in trials conducted in East Africa but not in Hong Kong. As well as differences in location, ethnicity and probable strain of Mycobacteria tuberculosis, Hong Kong trials more often evaluated regimens with rifampicin throughout and intermittent regimens, and patients in East African trials more often presented with extensive cavitation and were slower to convert to culture negative during treatment. An endpoint that is a summary measure of the longitudinal profile of culture results over time or that is able to detect the presence of M. tuberculosis later in treatment is more likely to be a better endpoint for a phase II trial than a culture result at a single time point and may prove to be an acceptable surrogate. More data are needed before any endpoint can be used as a surrogate in a confirmatory phase III trial.

  7. Development of a post-intensive care unit storytelling intervention for surrogates involved in decisions to limit life-sustaining treatment.

    Science.gov (United States)

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

    2015-06-01

    Surrogates involved in decisions to limit life-sustaining treatment for a loved one in the intensive care unit (ICU) are at increased risk for adverse psychological outcomes that can last for months to years after the ICU experience. Post-ICU interventions to reduce surrogate distress have not yet been developed. We sought to (1) describe a conceptual framework underlying the beneficial mental health effects of storytelling, and (2) present formative work developing a storytelling intervention to reduce distress for recently bereaved surrogates. An interdisciplinary team conceived the idea for a storytelling intervention based on evidence from narrative theory that storytelling reduces distress from traumatic events through emotional disclosure, cognitive processing, and social connection. We developed an initial storytelling guide based on this theory and the clinical perspectives of team members. We then conducted a case series with recently bereaved surrogates to iteratively test and modify the guide. The storytelling guide covered three key domains of the surrogate's experience of the patient's illness and death: antecedents, ICU experience, and aftermath. The facilitator focused on the parts of a story that appeared to generate strong emotions and used nonjudgmental statements to attend to these emotions. Between September 2012 and May 2013, we identified 28 eligible surrogates from a medical ICU and consented 20 for medical record review and recontact; 10 became eligible, of whom 6 consented and completed the storytelling intervention. The single-session storytelling intervention lasted from 40 to 92 minutes. All storytelling participants endorsed the intervention as acceptable, and five of six reported it as helpful. Surrogate storytelling is an innovative and acceptable post-ICU intervention for recently bereaved surrogates and should be evaluated further.

  8. 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.

  9. Destruction of chemical warfare surrogates using a portable atmospheric pressure plasma jet

    Science.gov (United States)

    Škoro, Nikola; Puač, Nevena; Živković, Suzana; Krstić-Milošević, Dijana; Cvelbar, Uroš; Malović, Gordana; Petrović, Zoran Lj.

    2018-01-01

    Today's reality is connected with mitigation of threats from the new chemical and biological warfare agents. A novel investigation of cold plasmas in contact with liquids presented in this paper demonstrated that the chemically reactive environment produced by atmospheric pressure plasma jet (APPJ) is potentially capable of rapid destruction of chemical warfare agents in a broad spectrum. The decontamination of three different chemical warfare agent surrogates dissolved in liquid is investigated by using an easily transportable APPJ. The jet is powered by a kHz signal source connected to a low-voltage DC source and with He as working gas. The detailed investigation of electrical properties is performed for various plasmas at different distances from the sample. The measurements of plasma properties in situ are supported by the optical spectrometry measurements, whereas the high performance liquid chromatography measurements before and after the treatment of aqueous solutions of Malathion, Fenitrothion and Dimethyl Methylphosphonate. These solutions are used to evaluate destruction and its efficiency for specific neural agent simulants. The particular removal rates are found to be from 56% up to 96% during 10 min treatment. The data obtained provide basis to evaluate APPJ's efficiency at different operating conditions. The presented results are promising and could be improved with different operating conditions and optimization of the decontamination process.

  10. 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)

  11. Active learning surrogate models for the conception of systems with multiple failure modes

    International Nuclear Information System (INIS)

    Perrin, G.

    2016-01-01

    Due to the performance and certification criteria, complex mechanical systems have to taken into account several constraints, which can be associated with a series of performance functions. Different software are generally used to evaluate such functions, whose computational cost can vary a lot. In conception or reliability analysis, we thus are interested in the identification of the boundaries of the domain where all these constraints are satisfied, at the minimal total computational cost. To this end, the present work proposes an iterative method to maximize the knowledge about these limits while trying to minimize the required number of evaluations of each performance function. This method is based first on Gaussian process surrogate models that are defined on nested sub-spaces, and second, on an original selection criterion that takes into account the computational cost associated with each performance function. After presenting the theoretical basis of this approach, this paper compares its efficiency to alternative methods on an example. - Highlights: • An iterative method to identify the limits of a system is proposed. • The method is based on nested Gaussian process surrogate models. • A new selection criterion that is adapted to the system case is presented. • The interest of the method is illustrated on an analytical example.

  12. Spatial network surrogates for disentangling complex system structure from spatial embedding of nodes

    Science.gov (United States)

    Wiedermann, Marc; Donges, Jonathan F.; Kurths, Jürgen; Donner, Reik V.

    2016-04-01

    Networks with nodes embedded in a metric space have gained increasing interest in recent years. The effects of spatial embedding on the networks' structural characteristics, however, are rarely taken into account when studying their macroscopic properties. Here, we propose a hierarchy of null models to generate random surrogates from a given spatially embedded network that can preserve certain global and local statistics associated with the nodes' embedding in a metric space. Comparing the original network's and the resulting surrogates' global characteristics allows one to quantify to what extent these characteristics are already predetermined by the spatial embedding of the nodes and links. We apply our framework to various real-world spatial networks and show that the proposed models capture macroscopic properties of the networks under study much better than standard random network models that do not account for the nodes' spatial embedding. Depending on the actual performance of the proposed null models, the networks are categorized into different classes. Since many real-world complex networks are in fact spatial networks, the proposed approach is relevant for disentangling the underlying complex system structure from spatial embedding of nodes in many fields, ranging from social systems over infrastructure and neurophysiology to climatology.

  13. Definitions and validation criteria for biomarkers and surrogate endpoints: development and testing of a quantitative hierarchical levels of evidence schema

    DEFF Research Database (Denmark)

    Lassere, Marissa N; Johnson, Kent R; Boers, Maarten

    2007-01-01

    endpoints, and leading indicators, a quantitative surrogate validation schema was developed and subsequently evaluated at a stakeholder workshop. RESULTS: The search identified several classification schema and definitions. Components of these were incorporated into a new quantitative surrogate validation...... of the National Institutes of Health definitions of biomarker, surrogate endpoint, and clinical endpoint was useful. CONCLUSION: Further development and application of this schema provides incentives and guidance for effective biomarker and surrogate endpoint research, and more efficient drug discovery...... 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...

  14. Comparative study on heat pipe performance using aqueous solutions of alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, R.; Vaidyanathan, S.; Sivaraman, B. [Annamalai University, Department of Mechanical Engineering, Annamalai Nagar, Tamil Nadu (India)

    2012-12-15

    This paper deals with the performance characterization of heat pipes using an aqueous solution of long chain alcohols like n-Butanol, n-Pentanol, n-Hexanol and n-Heptanol as working mediums. These solutions are called as self-rewetting fluids, since these fluid mixtures possess a non-linear dependence of the surface tension with temperature. A cylindrical heat pipe made up of copper with two layers of wrapped screen is used as a wick material and partially filled with the self-rewetting fluid water mixture and tested for its heat transport capability like thermal efficiency and thermal resistance at different inclinations and input power levels. A number of tests have been performed with heat pipes, filled with various aqueous solutions of alcohols with a concentration of 2 ml/l in de-ionized water (DI water) on volume basis. The results obtained for heat pipes using self rewetting fluids show improved performances, when compared to DI water heat pipes. (orig.)

  15. 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

  16. 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.

  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. Laminar burning velocities at elevated pressures for gasoline and gasoline surrogates associated with RON

    KAUST Repository

    Mannaa, Ossama

    2015-06-01

    The development and validation of a new gasoline surrogate using laminar flame speed as a target parameter is presented. Laminar burning velocities were measured using a constant-volume spherical vessel with ignition at the center of the vessel. Tested fuels included iso-octane, n-heptane, toluene, various mixtures of primary reference fuels (PRFs) and toluene reference fuels (TRFs) and three gasoline fuels of 70, 85 and 95 RON (FACE J, C and F) at the initial temperature of 358K and pressures up to 0.6MPa in the equivalence ratio ranging from 0.8 to 1.6. Normalized laminar burning velocity data were mapped into a tri-component mixture space at different experimental conditions to allocate different gasoline surrogates for different gasoline fuels, having RON of 70, 85 and 95. The surrogates of TRF-70-4 (17.94% iso-C8H18 +42.06% n-C7H16 +40% C7H8), TRF-85-1 (77.4% iso-C8H18 +17.6% n-C7H16 +5% C7H8), and TRF-95-1 (88.47% iso-C8H18 +6.53% n-C7H16 +5% C7H8) of RON 70, 85 and 95, respectively, are shown to successfully emulate the burning rate characteristics of the gasoline fuels associated with these RONs under the various experimental conditions investigated. An empirical correlation was derived to obtain laminar burning velocities at pressures that are experimentally unattainable as high as 3.0MPa. Laminar burning velocities were comparable to the simulated values for lean and stoichiometric flames but they were relatively higher than the simulated values for rich flames. A flame instability assessment was conducted by determining Markstein length, critical Pecklet number, and critical Karlovitz number at the onset of flame instability.

  19. 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...

  20. Comparative Study of Antibacterial and Antifungal Effects of Rigid Gas Permeable Contact Lens Disinfecting Solutions

    OpenAIRE

    Kuzman, Tomislav; Barišić Kutija, Marija; Kordić, Rajko; Popović Suić, Smiljka; Jandroković, Sonja; Škegro, Ivan; Pokupec, Rajko

    2013-01-01

    The aim of this study was to compare antimicrobial efficacy of rigid contact lens disinfecting solutions. We tested five commercially available solutions: Unique pH (Alcon Laboratories), Boston Advance (Polymer Technology Corp.), Nitilens Conditioner GP (Avizor), Total Care (AMO), Boston Simplus (Bausch&Lomb). Their efficacy to disinfect saline solution experimentally contaminated with American Type Culture Collection (ATCC): Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922...

  1. 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.

  2. Surrogate in vitro fertilization outcome in typical and atypical forms of Mayer-Rokitansky-Kuster-Hauser syndrome.

    Science.gov (United States)

    Raziel, A; Friedler, S; Gidoni, Y; Ben Ami, I; Strassburger, D; Ron-El, R

    2012-01-01

    The genital malformations in Mayer-Rokitansky-Küster-Hauser syndrome (MRKH) are frequently accompanied by associated malformations whose forms were recently classified as typical (isolated uterovaginal aplasia/hypoplasia) and atypical (the addition of malformations in the ovary or renal system). The aim of this study was to compare the surrogate IVF performance of women with typical and atypical forms including their chances of achieving pregnancy. The follow-up data on a total of 102 cycles of surrogate IVF in 27 MRKH patients treated in our department between 2000 and 2010 were analysed. Twenty patients with the typical form who underwent 72 IVF cycles were compared with seven patients with the atypical form who underwent 30 IVF cycles. The various examined parameters of these intended mothers were age, hormonal profile during controlled ovarian hyperstimulation and laboratory outcome. The mean number of gonadotrophin ampoules needed for stimulation and treatment duration was significantly higher in the atypical form (3600 ± 1297IU for 13 ± 2.3 days versus 2975 ± 967 IU for 11.6 ± 1.6 days, P≤ 0.01). Serum estradiol and progesterone levels measured on the hCG administration day were similar. A significantly higher mean number of follicles 12.6 ± 6 versus 8.9 ± 5.4, P≤ 0.03, metaphase II (MII) oocytes 8.7 ± 5.1 versus 6.7 ± 4.8, P≤ 0.05, fertilizations 6 ± 3.6 versus 4.4 ± 3.3, P≤ 0.03 and cleaving embryos 5.7 ± 3.8 versus 4.1 ± 3.3, P≤ 0.01 were available in patients with the typical form compared with those with the atypical form, respectively. There was no significant difference in fertilization rate, cleavage rate or the mean number of transferred embryos. Embryo quality of the transferred ones and pregnancy rate per cycle were also similar between the two groups. Women with the typical form of MRKH needed fewer gonadotrophins and for a shorter duration for ovarian hyperstimulation. The mean number of follicles, oocytes, MII oocytes

  3. Italian gay fathers' experiences of transnational surrogacy and their relationship with the surrogate pre- and post-birth.

    Science.gov (United States)

    Carone, Nicola; Baiocco, Roberto; Lingiardi, Vittorio

    2017-02-01

    This study aims to explore the experience of transnational surrogacy and the relationship with the surrogate pre- and post-birth in Italian gay father families. Couple and individual semi-structured interviews were carried out with 30 Italian gay partnered fathers with at least one child born through gestational surrogacy in California or Canada. No couples had known their surrogates or egg donors previously. The Interpretative Phenomenological Analysis indicated that three interrelated themes could be helpful for understanding the gay fathers' experience of their geographical distance from the surrogate: the perceived loss of control over the pregnancy; the surrogate as a person who facilitates the fathers' feelings of being emotionally connected to their developing child; the surrogate as an 'aunty' who, along with her family, maintains a relationship with the fathers. None of the fathers mentioned the egg donor during the interview. The study inspires reflections in offshore fertility practitioners on how pre- and ongoing surrogacy counselling for prospective gay fathers should be tailored. It further calls for the necessity of offering psychological counselling in gay fathers' resident countries in order to promote informed decisions before starting surrogacy abroad and to elaborate on potential difficulties related to surrogacy after the child's birth. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

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

    KAUST Repository

    Yü cel, Abdulkadir C.; Bagci, Hakan; Michielssen, Eric

    2011-01-01

    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.

  6. Testing serial dependence by Random-shuffle surrogates and the Wayland method

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Yoshito [Department of Mathematical Informatics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Aihara Complexity Modelling Project, ERATO, JST (Japan); Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)], E-mail: yoshito@sat.t.u-tokyo.ac.jp; Horai, Shunsuke [Aihara Complexity Modelling Project, ERATO, JST (Japan); Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Suzuki, Hideyuki [Department of Mathematical Informatics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Aihara, Kazuyuki [Department of Mathematical Informatics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Aihara Complexity Modelling Project, ERATO, JST (Japan); Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2007-10-22

    Given time series, a primary concern is existence of serial dependence and determinism. They are often tested with Random-shuffle surrogates, which totally break serial dependence, and the Wayland method. Since the statistic of the Wayland method fundamentally shows a smaller value for a more deterministic time series, for real-world data, we usually expect that the statistic for the original data is smaller than or equal to those of Random-shuffle surrogates. However, we show herewith an opposite result with wind data in high time resolution. We argue that this puzzling phenomenon can be produced by observational or dynamical noise, both of which may be produced by a low-dimensional deterministic system. Thus the one-sided test is dangerous.

  7. Testing serial dependence by Random-shuffle surrogates and the Wayland method

    International Nuclear Information System (INIS)

    Hirata, Yoshito; Horai, Shunsuke; Suzuki, Hideyuki; Aihara, Kazuyuki

    2007-01-01

    Given time series, a primary concern is existence of serial dependence and determinism. They are often tested with Random-shuffle surrogates, which totally break serial dependence, and the Wayland method. Since the statistic of the Wayland method fundamentally shows a smaller value for a more deterministic time series, for real-world data, we usually expect that the statistic for the original data is smaller than or equal to those of Random-shuffle surrogates. However, we show herewith an opposite result with wind data in high time resolution. We argue that this puzzling phenomenon can be produced by observational or dynamical noise, both of which may be produced by a low-dimensional deterministic system. Thus the one-sided test is dangerous

  8. Impact of copula directional specification on multi-trial evaluation of surrogate endpoints

    Science.gov (United States)

    Renfro, Lindsay A.; Shang, Hongwei; Sargent, Daniel J.

    2014-01-01

    Evaluation of surrogate endpoints using patient-level data from multiple trials is the gold standard, where multi-trial copula models are used to quantify both patient-level and trial-level surrogacy. While limited consideration has been given in the literature to copula choice (e.g., Clayton), no prior consideration has been given to direction of implementation (via survival versus distribution functions). We demonstrate that evenwith the “correct” copula family, directional misspecification leads to biased estimates of patient-level and trial-level surrogacy. We illustrate with a simulation study and a re-analysis of disease-free survival as a surrogate for overall survival in early stage colon cancer. PMID:24905465

  9. 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 ...

  10. Americium Separations from High-Salt Solutions Using Anion Exchange

    International Nuclear Information System (INIS)

    Barr, Mary E.; Jarvinen, Gordon D.; Stark, Peter C.; Chamberlin, Rebecca M.; Bartsch, Richard A.; Zhang, Z.Y.; Zhao, W.

    2001-01-01

    The aging of the US nuclear stockpile presents a number of challenges, including the increasing radioactivity of plutonium residues due to the ingrowth of 241 Am from the β-decay of 241 Pu. We investigated parameters that affect the sorption of Am onto anion-exchange resins from concentrated effluents derived from nitric acid processing of plutonium residues. These postevaporator wastes are nearly saturated solutions of acidic nitrate salts, and americium removal is complicated by physical factors, such as solution viscosity and particulates, as well as by the presence of large quantities of competing metals and acid. Single- and double-contact batch distribution coefficients for americium and neodymium from simple and complex surrogate solutions are presented. Varied parameters include the nitrate salt concentration and composition and the nitric acid concentration. We find that under these extremely concentrated conditions, Am(III) removal efficiencies can surpass 50% per contact. Distribution coefficients for both neodymium and americium are insensitive to solution acidity and appear to be driven primarily by low water activities of the solutions

  11. 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 ...

  12. The effect of emotion and physician communication behaviors on surrogates' life-sustaining treatment decisions: a randomized simulation experiment.

    Science.gov (United States)

    Barnato, Amber E; Arnold, Robert M

    2013-07-01

    Surrogate decision makers for critically ill patients experience strong negative emotional states. Emotions influence risk perception, risk preferences, and decision making. We sought to explore the effect of emotional state and physician communication behaviors on surrogates' life-sustaining treatment decisions. 5 × 2 between-subject randomized factorial experiment. Web-based simulated interactive video meeting with an intensivist to discuss code status. Community-based participants 35 and older who self-identified as the surrogate for a parent or spouse recruited from eight U.S. cities through public advertisements. Block random assignment to emotion arousal manipulation and each of the four physician communication behaviors. Surrogate's code status decision (cardiopulmonary resuscitation vs do not resuscitate/allow natural death). Two hundred fifty-six of 373 respondents (69%) logged-in and were randomized: average age was 50; 70% were surrogates for a parent; 63.5% were women; 76% were white, 11% black, and 9% Asian; and 81% were college educated. When asked about code status, 56% chose cardiopulmonary resuscitation. The emotion arousal manipulation increased the score on depression-dejection scale (β = 1.76 [0.58 - 2.94]) but did not influence cardiopulmonary resuscitation choice. Physician attending to emotion and framing the decision as the patient's rather than the surrogate's did not influence cardiopulmonary resuscitation choice. Framing no cardiopulmonary resuscitation as the norm rather than cardiopulmonary resuscitation resulted in fewer surrogates choosing cardiopulmonary resuscitation (48% vs 64%, odds ratio, 0.52 [95% CI, 0.32-0.87]), as did framing the alternative to cardiopulmonary resuscitation as "allow natural death" rather than do not resuscitate (49% vs 61%, odds ratio, 0.58 [95% CI, 0.35-0.96]). Experimentally induced emotional state did not influence code status decisions, although small changes in physician communication behaviors

  13. Comparative analysis of solution methods of the punctual kinetic equations

    International Nuclear Information System (INIS)

    Hernandez S, A.

    2003-01-01

    The following one written it presents a comparative analysis among different analytical solutions for the punctual kinetics equation, which present two variables of interest: a) the temporary behavior of the neutronic population, and b) The temporary behavior of the different groups of precursors of delayed neutrons. The first solution is based on a method that solves the transfer function of the differential equation for the neutronic population, in which intends to obtain the different poles that give the stability of this transfer function. In this section it is demonstrated that the temporary variation of the reactivity of the system can be managed as it is required, since the integration time for this method doesn't affect the result. However, the second solution is based on an iterative method like that of Runge-Kutta or the Euler method where the algorithm was only used to solve first order differential equations giving this way solution to each differential equation that conforms the equations of punctual kinetics. In this section it is demonstrated that only it can obtain a correct temporary behavior of the neutronic population when it is integrated on an interval of very short time, forcing to the temporary variation of the reactivity to change very quick way without one has some control about the time. In both methods the same change is used so much in the reactivity of the system like in the integration times, giving validity to the results graph the one the temporary behavior of the neutronic population vs. time. (Author)

  14. Accurate quantification of endogenous androgenic steroids in cattle's meat by gas chromatography mass spectrometry using a surrogate analyte approach

    International Nuclear Information System (INIS)

    Ahmadkhaniha, Reza; Shafiee, Abbas; Rastkari, Noushin; Kobarfard, Farzad

    2009-01-01

    Determination of endogenous steroids in complex matrices such as cattle's meat is a challenging task. Since endogenous steroids always exist in animal tissues, no analyte-free matrices for constructing the standard calibration line will be available, which is crucial for accurate quantification specially at trace level. Although some methods have been proposed to solve the problem, none has offered a complete solution. To this aim, a new quantification strategy was developed in this study, which is named 'surrogate analyte approach' and is based on using isotope-labeled standards instead of natural form of endogenous steroids for preparing the calibration line. In comparison with the other methods, which are currently in use for the quantitation of endogenous steroids, this approach provides improved simplicity and speed for analysis on a routine basis. The accuracy of this method is better than other methods at low concentration and comparable to the standard addition at medium and high concentrations. The method was also found to be valid according to the ICH criteria for bioanalytical methods. The developed method could be a promising approach in the field of compounds residue analysis

  15. 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

  16. Americium separations from high salt solutions

    International Nuclear Information System (INIS)

    Barr, Mary E.; Jarvinen, Gordon D.; Schulte, Louis D.; Stark, Peter C.; Chamberlin, Rebecca M.; Abney, Kent D.; Ricketts, Thomas E.; Valdez, Yvette E.; Bartsch, Richard A.

    2000-01-01

    Americium (III) exhibits an unexpectedly high affinity for anion-exchange material from the high-salt evaporator bottoms solutions--an effect which has not been duplicated using simple salt solutions. Similar behavior is observed for its lanthanide homologue, Nd(III), in complex evaporator bottoms surrogate solutions. There appears to be no single controlling factor--acid concentration, total nitrate concentration or solution ionic strength--which accounts for the approximately 2-fold increase in retention of the trivalent ions from complex solutions relative to simple solutions. Calculation of species activities (i.e., water, proton and nitrate) in such concentrated mixed salt solutions is difficult and of questionable accuracy, but it is likely that the answer to forcing formation of anionic nitrate complexes of americium lies in the relative activities of water and nitrate. From a practical viewpoint, the modest americium removal needs (ca. 50--75%) from nitric acid evaporator bottoms allow sufficient latitude for the use of non-optimized conditions such as running existing columns filled with older, well-used Reillex HPQ. Newer materials, such as HPQ-100 and the experimental bifunctional resins, which exhibit higher distribution coefficients, would allow for either increased Am removal or the use of smaller columns. It is also of interest that one of the experimental neutral-donor solid-support extractants, DHDECMP, exhibits a similarly high level of americium (total alpha) removal from EV bottoms and is much less sensitive to total acid content than commercially-available material

  17. 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...

  18. Ignition of alkane-rich FACE gasoline fuels and their surrogate mixtures

    KAUST Repository

    Sarathy, Mani

    2015-01-01

    Petroleum derived gasoline is the most used transportation fuel for light-duty vehicles. In order to better understand gasoline combustion, this study investigated the ignition propensity of two alkane-rich FACE (Fuels for Advanced Combustion Engines) gasoline test fuels and their corresponding PRF (primary reference fuel) blend in fundamental combustion experiments. Shock tube ignition delay times were measured in two separate facilities at pressures of 10, 20, and 40 bar, temperatures from 715 to 1500 K, and two equivalence ratios. Rapid compression machine ignition delay times were measured for fuel/air mixtures at pressures of 20 and 40 bar, temperatures from 632 to 745 K, and two equivalence ratios. Detailed hydrocarbon analysis was also performed on the FACE gasoline fuels, and the results were used to formulate multi-component gasoline surrogate mixtures. Detailed chemical kinetic modeling results are presented herein to provide insights into the relevance of utilizing PRF and multi-component surrogate mixtures to reproduce the ignition behavior of the alkane-rich FACE gasoline fuels. The two FACE gasoline fuels and their corresponding PRF mixture displayed similar ignition behavior at intermediate and high temperatures, but differences were observed at low temperatures. These trends were mimicked by corresponding surrogate mixture models, except for the amount of heat release in the first stage of a two-stage ignition events, when observed. © 2014 The Combustion Institute.

  19. 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...

  20. 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.

  1. Pulmonary and symptom threshold effects of ozone in airline passenger and cockpit crew surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Lategola, M.T.; Melton, C.E.; Higgins, E.A.

    1980-09-01

    Previous studies showed that the ozone concentration for pulmonary and symptom threshold effects in flight attendant surrogates lies between 0.20 and 0.30 ppMv for a 3-h exposure with intermittent treadmill exercise at 1829 m (MSL) stimulated cabin altitude. In the present study of sedentary occupants of the in-flight airline cabin, the same protocol was used except for omitting all treadmill exercise. Symptoms were assessed with a standardized questionnaire. Pulmonary function was assessed using standardized quantitative spirometry. Male smoker and nonsmoker airline passenger and cockpit crew surrogates 40 to 59 years of age were used. Small but statistically significant displacements occurred in symptoms and in some spirometry parameters. In general, the younger subjects appeared more sensitive to ozone than the older subjects. No significant differences appeared between smokers' and nonsmokers' responses to ozone exposure. It is concluded that the ozone threshold of these sedentary surrogates under these experimental conditions is right at 0.30 ppMv.

  2. [The Intentions Affecting the Medical Decision-Making Behavior of Surrogate Decision Makers of Critically Ill Patients and Related Factors].

    Science.gov (United States)

    Su, Szu-Huei; Wu, Li-Min

    2018-04-01

    The severity of diseases and high mortality rates that typify the intensive care unit often make it difficult for surrogate decision makers to make decisions for critically ill patients regarding whether to continue medical treatments or to accept palliative care. To explore the behavioral intentions that underlie the medical decisions of surrogate decision makers of critically ill patients and the related factors. A cross-sectional, correlation study design was used. A total of 193 surrogate decision makers from six ICUs in a medical center in southern Taiwan were enrolled as participants. Three structured questionnaires were used, including a demographic datasheet, the Family Relationship Scale, and the Behavioral Intention of Medical Decisions Scale. Significantly positive correlations were found between the behavioral intentions underlying medical decisions and the following variables: the relationship of the participant to the patient (Eta = .343, p = .020), the age of the patient (r = .295, p medical decisions of the surrogate decision makers, explaining 13.9% of the total variance. In assessing the behavioral intentions underlying the medical decisions of surrogate decision makers, health providers should consider the relationship between critical patients and their surrogate decision makers, patient age, the length of ICU stay, and whether the patient has a pre-signed advance healthcare directive in order to maximize the effectiveness of medical care provided to critically ill patients.

  3. 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.

  4. Regression with Small Data Sets: A Case Study using Code Surrogates in Additive Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fan, Y. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-11

    There has been an increasing interest in recent years in the mining of massive data sets whose sizes are measured in terabytes. While it is easy to collect such large data sets in some application domains, there are others where collecting even a single data point can be very expensive, so the resulting data sets have only tens or hundreds of samples. For example, when complex computer simulations are used to understand a scientific phenomenon, we want to run the simulation for many different values of the input parameters and analyze the resulting output. The data set relating the simulation inputs and outputs is typically quite small, especially when each run of the simulation is expensive. However, regression techniques can still be used on such data sets to build an inexpensive \\surrogate" that could provide an approximate output for a given set of inputs. A good surrogate can be very useful in sensitivity analysis, uncertainty analysis, and in designing experiments. In this paper, we compare different regression techniques to determine how well they predict melt-pool characteristics in the problem domain of additive manufacturing. Our analysis indicates that some of the commonly used regression methods do perform quite well even on small data sets.

  5. 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.

  6. 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.

  7. Uncertainty propagation through an aeroelastic wind turbine model using polynomial surrogates

    DEFF Research Database (Denmark)

    Murcia Leon, Juan Pablo; Réthoré, Pierre-Elouan; Dimitrov, Nikolay Krasimirov

    2018-01-01

    of the uncertainty in annual energy production due to wind resource variability and/or robust wind power plant layout optimization. It can be concluded that it is possible to capture the global behavior of a modern wind turbine and its uncertainty under realistic inflow conditions using polynomial response surfaces......Polynomial surrogates are used to characterize the energy production and lifetime equivalent fatigue loads for different components of the DTU 10 MW reference wind turbine under realistic atmospheric conditions. The variability caused by different turbulent inflow fields are captured by creating......-alignment. The methodology presented extends the deterministic power and thrust coefficient curves to uncertainty models and adds new variables like damage equivalent fatigue loads in different components of the turbine. These surrogate models can then be implemented inside other work-flows such as: estimation...

  8. Laminar Burning Velocities of Fuels for Advanced Combustion Engines (FACE) Gasoline and Gasoline Surrogates with and without Ethanol Blending Associated with Octane Rating

    KAUST Repository

    Mannaa, Ossama

    2016-05-04

    Laminar burning velocities of fuels for advanced combustion engines (FACE) C gasoline and of several blends of surrogate toluene reference fuels (TRFs) (n-heptane, iso-octane, and toluene mixtures) of the same research octane number are presented. Effects of ethanol addition on laminar flame speed of FACE-C and its surrogate are addressed. Measurements were conducted using a constant volume spherical combustion vessel in the constant pressure, stable flame regime at an initial temperature of 358 K and initial pressures up to 0.6 MPa with the equivalence ratios ranging from 0.8 to 1.6. Comparable values in the laminar burning velocities were measured for the FACE-C gasoline and the proposed surrogate fuel (17.60% n-heptane + 77.40% iso-octane + 5% toluene) over the range of experimental conditions. Sensitivity of flame propagation to total stretch rate effects and thermo-diffusive instability was quantified by determining Markstein length. Two percentages of an oxygenated fuel of ethanol as an additive, namely, 60 vol% and 85 vol% were investigated. The addition of ethanol to FACE-C and its surrogate TRF-1 (17.60% n-heptane + 77.40% iso-octane + 5% toluene) resulted in a relatively similar increase in the laminar burning velocities. The high-pressure measured values of Markstein length for the studied fuels blended with ethanol showed minimal influence of ethanol addition on the flame’s response to stretch rate and thermo-diffusive instability. © 2016 Taylor & Francis.

  9. Laminar Burning Velocities of Fuels for Advanced Combustion Engines (FACE) Gasoline and Gasoline Surrogates with and without Ethanol Blending Associated with Octane Rating

    KAUST Repository

    Mannaa, Ossama; Mansour, Morkous S.; Roberts, William L.; Chung, Suk-Ho

    2016-01-01

    Laminar burning velocities of fuels for advanced combustion engines (FACE) C gasoline and of several blends of surrogate toluene reference fuels (TRFs) (n-heptane, iso-octane, and toluene mixtures) of the same research octane number are presented. Effects of ethanol addition on laminar flame speed of FACE-C and its surrogate are addressed. Measurements were conducted using a constant volume spherical combustion vessel in the constant pressure, stable flame regime at an initial temperature of 358 K and initial pressures up to 0.6 MPa with the equivalence ratios ranging from 0.8 to 1.6. Comparable values in the laminar burning velocities were measured for the FACE-C gasoline and the proposed surrogate fuel (17.60% n-heptane + 77.40% iso-octane + 5% toluene) over the range of experimental conditions. Sensitivity of flame propagation to total stretch rate effects and thermo-diffusive instability was quantified by determining Markstein length. Two percentages of an oxygenated fuel of ethanol as an additive, namely, 60 vol% and 85 vol% were investigated. The addition of ethanol to FACE-C and its surrogate TRF-1 (17.60% n-heptane + 77.40% iso-octane + 5% toluene) resulted in a relatively similar increase in the laminar burning velocities. The high-pressure measured values of Markstein length for the studied fuels blended with ethanol showed minimal influence of ethanol addition on the flame’s response to stretch rate and thermo-diffusive instability. © 2016 Taylor & Francis.

  10. Bronchography in dogs. Comparative study with two barium sulphate solutions

    International Nuclear Information System (INIS)

    Thibaut, J.; Gallardo, P.; Vargas, L.; Deppe, R.; Born, R.

    1998-01-01

    Two solutions of barium sulphate, 60 and 30% w/v, were compared with the ''overflow'' Bronchographic method. Two groups of eight healthy adult does of both sexes, weighing 7 to 18 kg were used for the study. The dogs were anaesthetised with thiopentone sodium 2% (20 mg/kg iv). After intubation, each dog received contrast medium by a catheter connected to a syringe, in a 9 mi dose. Two series of two x-rays plates were taken in left lateral recumbent, 3 and 6 min after administering the contrast medium and in ventrodorsal projection, 30 sec. later. The x-ray plates obtained were analysed and compared intra and inter group considering the advance speed of the contrast medium, the radiographic density and outlines. Adverse reactions were controlled

  11. Surrogate receptivity to participation in critical illness genetic research: aligning research oversight and stakeholder concerns.

    Science.gov (United States)

    Freeman, Bradley D; Butler, Kevin; Bolcic-Jankovic, Dragana; Clarridge, Brian R; Kennedy, Carie R; LeBlanc, Jessica; Chandros Hull, Sara

    2015-04-01

    Collection of genetic biospecimens as part of critical illness investigations is increasingly commonplace. Oversight bodies vary in restrictions imposed on genetic research, introducing inconsistencies in study design, potential for sampling bias, and the possibility of being overly prohibitive of this type of research altogether. We undertook this study to better understand whether restrictions on genetic data collection beyond those governing research on cognitively intact subjects reflect the concerns of surrogates for critically ill patients. We analyzed survey data collected from 1,176 patients in nonurgent settings and 437 surrogates representing critically ill adults. Attitudes pertaining to genetic data (familiarity, perceptions, interest in participation, concerns) and demographic information were examined using univariate and multivariate techniques. We explored differences among respondents who were receptive (1,333) and nonreceptive (280) to genetic sample collection. Whereas factors positively associated with receptivity to research participation were "complete trust" in health-care providers (OR, 2.091; 95% CI, 1.544-2.833), upper income strata (OR, 2.319; 95% CI, 1.308-4.114), viewing genetic research "very positively" (OR, 3.524; 95% CI, 2.122-5.852), and expressing "no worry at all" regarding disclosure of results (OR, 2.505; 95% CI, 1.436-4.369), black race was negatively associated with research participation (OR, 0.410; 95% CI, 0.288-0.585). We could detect no difference in receptivity to genetic sample collection comparing ambulatory patients and surrogates (OR, 0.738; 95% CI, 0.511-1.066). Expressing trust in health-care providers and viewing genetic research favorably were associated with increased willingness for study enrollment, while concern regarding breach of confidentiality and black race had the opposite effect. Study setting had no bearing on willingness to participate.

  12. A Novel Instrumented Human Head Surrogate for the Impact Evaluation of Helmets

    Directory of Open Access Journals (Sweden)

    Nicola Petrone

    2018-02-01

    Full Text Available A novel Human Head Surrogate was obtained from available MRI scans of a 50th percentile male human head. Addictive manufacturing was used to produce the skull, the brain and the skin. All original MRI geometries were partially smoothed and adjusted to provide the best biofidelity compatible with printing and molding technology. The skull was 3D-printed in ABS and ten pressure sensors were placed into it. The brain surrogate was cast from silicon rubber in the 3D-printed plastic molds. Nine tri-axial accelerometers (placed at the tops of the lobes, at the sides of the lobes, in the cerebellum and in the center of mass and a three-axis gyroscope (at the center of mass were inserted into the silicon brain during casting. The cranium, after assembly with brain, was filled with silicon oil mimicking the cerebral fluid. Silicon rubber was cast in additional 3D-printed molds to form the skin surrounding the cranium. The skull base was adapted to be compatible with the Hybrid-III neck and allow the exit of brain sensors cabling. Preliminary experiments were carried out proving the functionality of the surrogate. Results showed how multiple accelerometers and pressure sensors allowed a better comprehension of the head complex motion during impacts.

  13. Performance of surrogate high-level waste glass in the presence of iron corrosion products

    International Nuclear Information System (INIS)

    Jain, V.; Pan, Y.M.

    2004-01-01

    Radionuclide release from a waste package (WP) is a series of processes that depend upon the composition and flux of groundwater contacting the waste-forms (WF); the corrosion rate of WP containers and internal components made of Alloy 22, 316L SS, 304L SS and carbon steel; the dissolution rate of high-level radioactive waste (HLW) glass and spent nuclear fuel (SNF); the solubility of radionuclides; and the retention of radionuclides in secondary mineral phases. In this study, forward reaction rate measurements were made on a surrogate HLW glass in the presence of FeCl 3 species. Results indicate that the forward reaction rate increases with an increase in the FeCl 3 concentration. The addition of FeCl 3 causes the drop in the pH due to hydrolysis of Fe 3+ ions in the solution. Results based on the radionuclide concentrations and dissolution rates for HLW glass and SNF indicate that the contribution from glass is similar to SNF at 75 deg C. (authors)

  14. 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.

  15. 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.

  16. 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.

  17. 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.)

  18. 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.)

  19. Definitions and validation criteria for biomarkers and surrogate endpoints: development and testing of a quantitative hierarchical levels of evidence schema

    DEFF Research Database (Denmark)

    Lassere, Marissa N; Johnson, Kent R; Boers, Maarten

    2007-01-01

    endpoints, and leading indicators, a quantitative surrogate validation schema was developed and subsequently evaluated at a stakeholder workshop. RESULTS: 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...... of the National Institutes of Health definitions of biomarker, surrogate endpoint, and clinical endpoint was useful. CONCLUSION: Further development and application of this schema provides incentives and guidance for effective biomarker and surrogate endpoint research, and more efficient drug discovery...

  20. Surrogate formulations for thermal treatment of low-level mixed waste, Part II: Selected mixed waste treatment project waste streams

    Energy Technology Data Exchange (ETDEWEB)

    Bostick, W.D.; Hoffmann, D.P.; Chiang, J.M.; Hermes, W.H.; Gibson, L.V. Jr.; Richmond, A.A. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States); Mayberry, J. [Science Applications International Corp., Idaho Falls, ID (United States); Frazier, G. [Univ. of Tennessee, Knoxville, TN (United States)

    1994-01-01

    This report summarizes the formulation of surrogate waste packages, representing the major bulk constituent compositions for 12 waste stream classifications selected by the US DOE Mixed Waste Treatment Program. These waste groupings include: neutral aqueous wastes; aqueous halogenated organic liquids; ash; high organic content sludges; adsorbed aqueous and organic liquids; cement sludges, ashes, and solids; chloride; sulfate, and nitrate salts; organic matrix solids; heterogeneous debris; bulk combustibles; lab packs; and lead shapes. Insofar as possible, formulation of surrogate waste packages are referenced to authentic wastes in inventory within the DOE; however, the surrogate waste packages are intended to represent generic treatability group compositions. The intent is to specify a nonradiological synthetic mixture, with a minimal number of readily available components, that can be used to represent the significant challenges anticipated for treatment of the specified waste class. Performance testing and evaluation with use of a consistent series of surrogate wastes will provide a means for the initial assessment (and intercomparability) of candidate treatment technology applicability and performance. Originally the surrogate wastes were intended for use with emerging thermal treatment systems, but use may be extended to select nonthermal systems as well.

  1. Surrogate formulations for thermal treatment of low-level mixed waste, Part II: Selected mixed waste treatment project waste streams

    International Nuclear Information System (INIS)

    Bostick, W.D.; Hoffmann, D.P.; Chiang, J.M.; Hermes, W.H.; Gibson, L.V. Jr.; Richmond, A.A.; Mayberry, J.; Frazier, G.

    1994-01-01

    This report summarizes the formulation of surrogate waste packages, representing the major bulk constituent compositions for 12 waste stream classifications selected by the US DOE Mixed Waste Treatment Program. These waste groupings include: neutral aqueous wastes; aqueous halogenated organic liquids; ash; high organic content sludges; adsorbed aqueous and organic liquids; cement sludges, ashes, and solids; chloride; sulfate, and nitrate salts; organic matrix solids; heterogeneous debris; bulk combustibles; lab packs; and lead shapes. Insofar as possible, formulation of surrogate waste packages are referenced to authentic wastes in inventory within the DOE; however, the surrogate waste packages are intended to represent generic treatability group compositions. The intent is to specify a nonradiological synthetic mixture, with a minimal number of readily available components, that can be used to represent the significant challenges anticipated for treatment of the specified waste class. Performance testing and evaluation with use of a consistent series of surrogate wastes will provide a means for the initial assessment (and intercomparability) of candidate treatment technology applicability and performance. Originally the surrogate wastes were intended for use with emerging thermal treatment systems, but use may be extended to select nonthermal systems as well

  2. Creation of a retrospective job-exposure matrix using surrogate measures of exposure for a cohort of US career firefighters from San Francisco, Chicago and Philadelphia.

    Science.gov (United States)

    Dahm, Matthew M; Bertke, Stephen; Allee, Steve; Daniels, Robert D

    2015-09-01

    To construct a cohort-specific job-exposure matrix (JEM) using surrogate metrics of exposure for a cancer study on career firefighters from the Chicago, Philadelphia and San Francisco Fire Departments. Departmental work history records, along with data on historical annual fire-runs and hours, were collected from 1950 to 2009 and coded into separate databases. These data were used to create a JEM based on standardised job titles and fire apparatus assignments using several surrogate exposure metrics to estimate firefighters' exposure to the combustion byproducts of fire. The metrics included duration of exposure (cumulative time with a standardised exposed job title and assignment), fire-runs (cumulative events of potential fire exposure) and time at fire (cumulative hours of potential fire exposure). The JEM consisted of 2298 unique job titles alongside 16,174 fire apparatus assignments from the three departments, which were collapsed into 15 standardised job titles and 15 standardised job assignments. Correlations were found between fire-runs and time at fires (Pearson coefficient=0.92), duration of exposure and time at fires (Pearson coefficient=0.85), and duration of exposure and fire-runs (Pearson coefficient=0.82). Total misclassification rates were found to be between 16-30% when using duration of employment as an exposure surrogate, which has been traditionally used in most epidemiological studies, compared with using the duration of exposure surrogate metric. The constructed JEM successfully differentiated firefighters based on gradient levels of potential exposure to the combustion byproducts of fire using multiple surrogate exposure metrics. 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.

  3. Compositional effects on PAH and soot formation in counterflow diffusion flames of gasoline surrogate fuels

    KAUST Repository

    Park, Sungwoo

    2017-02-05

    Gasoline surrogate fuels are widely used to understand the fundamental combustion properties of complex refinery gasoline fuels. In this study, the compositional effects on polycyclic aromatic hydrocarbons (PAHs) and soot formation were investigated experimentally for gasoline surrogate mixtures comprising n-heptane, iso-octane, and toluene in counterflow diffusion flames. A comprehensive kinetic model for the gasoline surrogate mixtures was developed to accurately predict the fuel oxidation along with the formation of PAHs and soot in flames. This combined model was first tested against ignition delay times and laminar burning velocities data. The proposed model for the formation and growth of PAHs up to coronene (C24H12) was based on previous studies and was tested against existing and present new experimental data. Additionally, in the accompanied soot model, PAHs with sizes larger than (including) pyrene were used for the inception of soot particles, followed by particle coagulations and PAH condensation/chemical reactions on soot surfaces. The major pathways for the formation of PAHs were also identified for the surrogate mixtures. The model accurately captures the synergistic PAH formation characteristics observed experimentally for n-heptane/toluene and iso-octane/toluene binary mixtures. Furthermore, the present experimental and modeling results also elucidated different trends in the formation of larger PAHs and soot between binary n-heptane/iso-octane and ternary n-heptane/iso-octane/toluene mixtures. Propargyl radicals (C3H3) were shown to be important in the formation and growth of PAHs for n-heptane/iso-octane mixtures when the iso-octane concentration increased; however, reactions involving benzyl radicals (C6H5CH2) played a significant role in the formation of PAHs for n-heptane/iso-octane/toluene mixtures. These results indicated that the formation of PAHs and subsequently soot was strongly affected by the composition of gasoline surrogate mixtures.

  4. Compositional effects on PAH and soot formation in counterflow diffusion flames of gasoline surrogate fuels

    KAUST Repository

    Park, Sungwoo; Wang, Yu; Chung, Suk-Ho; Sarathy, Mani

    2017-01-01

    Gasoline surrogate fuels are widely used to understand the fundamental combustion properties of complex refinery gasoline fuels. In this study, the compositional effects on polycyclic aromatic hydrocarbons (PAHs) and soot formation were investigated experimentally for gasoline surrogate mixtures comprising n-heptane, iso-octane, and toluene in counterflow diffusion flames. A comprehensive kinetic model for the gasoline surrogate mixtures was developed to accurately predict the fuel oxidation along with the formation of PAHs and soot in flames. This combined model was first tested against ignition delay times and laminar burning velocities data. The proposed model for the formation and growth of PAHs up to coronene (C24H12) was based on previous studies and was tested against existing and present new experimental data. Additionally, in the accompanied soot model, PAHs with sizes larger than (including) pyrene were used for the inception of soot particles, followed by particle coagulations and PAH condensation/chemical reactions on soot surfaces. The major pathways for the formation of PAHs were also identified for the surrogate mixtures. The model accurately captures the synergistic PAH formation characteristics observed experimentally for n-heptane/toluene and iso-octane/toluene binary mixtures. Furthermore, the present experimental and modeling results also elucidated different trends in the formation of larger PAHs and soot between binary n-heptane/iso-octane and ternary n-heptane/iso-octane/toluene mixtures. Propargyl radicals (C3H3) were shown to be important in the formation and growth of PAHs for n-heptane/iso-octane mixtures when the iso-octane concentration increased; however, reactions involving benzyl radicals (C6H5CH2) played a significant role in the formation of PAHs for n-heptane/iso-octane/toluene mixtures. These results indicated that the formation of PAHs and subsequently soot was strongly affected by the composition of gasoline surrogate mixtures.

  5. 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

  6. A new method to measure effective soil solution concentration predicts copper availability to plants.

    Science.gov (United States)

    Zhang, H; Zhao, F J; Sun, B; Davison, W; McGrath, S P

    2001-06-15

    Risk assessments of metal contaminated soils need to address metal bioavailability. To predict the bioavailability of metals to plants, it is necessary to understand both solution and solid phase supply processes in soils. In striving to find surrogate chemical measurements, scientists have focused either on soil solution chemistry, including free ion activities, or operationally defined fractions of metals. Here we introduce the new concept of effective concentration, CE, which includes both the soil solution concentration and an additional term, expressed as a concentration, that represents metal supplied from the solid phase. CE was measured using the technique of diffusive gradients in thin films (DGT) which, like a plant, locally lowers soil solution concentrations, inducing metal supply from the solid phase, as shown by a dynamic model of the DGT-soil system. Measurements of Cu as CE, soil solution concentration, by EDTA extraction and as free Cu2+ activity in soil solution were made on 29 different soils covering a large range of copper concentrations. Theywere compared to Cu concentrations in the plant material of Lepidium heterophyllum grown on the same soils. Plant concentrations were linearly related and highly correlated with CE but were more scattered and nonlinear with respect to free Cu2+ activity, EDTA extraction, or soil solution concentrations. These results demonstrate that the dominant supply processes in these soils are diffusion and labile metal release, which the DGT-soil system mimics. The quantity CE is shown to have promise as a quantitative measure of the bioavailable metal in soils.

  7. An evaluation of data-driven motion estimation in comparison to the usage of external-surrogates in cardiac SPECT imaging

    International Nuclear Information System (INIS)

    Mukherjee, Joyeeta Mitra; Johnson, Karen L; Pretorius, P Hendrik; King, Michael A; Hutton, Brian F

    2013-01-01

    Motion estimation methods in single photon emission computed tomography (SPECT) can be classified into methods which depend on just the emission data (data-driven), or those that use some other source of information such as an external surrogate. The surrogate-based methods estimate the motion exhibited externally which may not correlate exactly with the movement of organs inside the body. The accuracy of data-driven strategies on the other hand is affected by the type and timing of motion occurrence during acquisition, the source distribution, and various degrading factors such as attenuation, scatter, and system spatial resolution. The goal of this paper is to investigate the performance of two data-driven motion estimation schemes based on the rigid-body registration of projections of motion-transformed source distributions to the acquired projection data for cardiac SPECT studies. Comparison is also made of six intensity based registration metrics to an external surrogate-based method. In the data-driven schemes, a partially reconstructed heart is used as the initial source distribution. The partially-reconstructed heart has inaccuracies due to limited angle artifacts resulting from using only a part of the SPECT projections acquired while the patient maintained the same pose. The performance of different cost functions in quantifying consistency with the SPECT projection data in the data-driven schemes was compared for clinically realistic patient motion occurring as discrete pose changes, one or two times during acquisition. The six intensity-based metrics studied were mean-squared difference, mutual information, normalized mutual information (NMI), pattern intensity (PI), normalized cross-correlation and entropy of the difference. Quantitative and qualitative analysis of the performance is reported using Monte-Carlo simulations of a realistic heart phantom including degradation factors such as attenuation, scatter and system spatial resolution. Further the

  8. Integration of computational modeling and experimental techniques to design fuel surrogates

    DEFF Research Database (Denmark)

    Choudhury, H.A.; Intikhab, S.; Kalakul, Sawitree

    2017-01-01

    performance. A simplified alternative is to develop surrogate fuels that have fewer compounds and emulate certain important desired physical properties of the target fuels. Six gasoline blends were formulated through a computer aided model based technique “Mixed Integer Non-Linear Programming” (MINLP...... Virtual Process-Product Design Laboratory (VPPD-Lab) are applied onto the defined compositions of the surrogate gasoline. The aim is to primarily verify the defined composition of gasoline by means of VPPD-Lab. ρ, η and RVP are calculated with more accuracy and constraints such as distillation curve...... and flash point on the blend design are also considered. A post-design experiment-based verification step is proposed to further improve and fine-tune the “best” selected gasoline blends following the computation work. Here, advanced experimental techniques are used to measure the RVP, ρ, η, RON...

  9. The development and experimental validation of a reduced ternary kinetic mechanism for the auto-ignition at HCCI conditions, proposing a global reaction path for ternary gasoline surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim; Cavadias, Simeon; Amouroux, Jacques [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France)

    2009-02-15

    To acquire a high amount of information of the behaviour of the Homogeneous Charge Compression Ignition (HCCI) auto-ignition process, a reduced surrogate mechanism has been composed out of reduced n-heptane, iso-octane and toluene mechanisms, containing 62 reactions and 49 species. This mechanism has been validated numerically in a 0D HCCI engine code against more detailed mechanisms (inlet temperature varying from 290 to 500 K, the equivalence ratio from 0.2 to 0.7 and the compression ratio from 8 to 18) and experimentally against experimental shock tube and rapid compression machine data from the literature at pressures between 9 and 55 bar and temperatures between 700 and 1400 K for several fuels: the pure compounds n-heptane, iso-octane and toluene as well as binary and ternary mixtures of these compounds. For this validation, stoichiometric mixtures and mixtures with an equivalence ratio of 0.5 are used. The experimental validation is extended by comparing the surrogate mechanism to experimental data from an HCCI engine. A global reaction pathway is proposed for the auto-ignition of a surrogate gasoline, using the surrogate mechanism, in order to show the interactions that the three compounds can have with one another during the auto-ignition of a ternary mixture. (author)

  10. 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.

  11. Role of pseudo-turbulent stresses in shocked particle clouds and construction of surrogate models for closure

    Science.gov (United States)

    Sen, O.; Gaul, N. J.; Davis, S.; Choi, K. K.; Jacobs, G.; Udaykumar, H. S.

    2018-05-01

    Macroscale models of shock-particle interactions require closure terms for unresolved solid-fluid momentum and energy transfer. These comprise the effects of mean as well as fluctuating fluid-phase velocity fields in the particle cloud. Mean drag and Reynolds stress equivalent terms (also known as pseudo-turbulent terms) appear in the macroscale equations. Closure laws for the pseudo-turbulent terms are constructed in this work from ensembles of high-fidelity mesoscale simulations. The computations are performed over a wide range of Mach numbers ( M) and particle volume fractions (φ ) and are used to explicitly compute the pseudo-turbulent stresses from the Favre average of the velocity fluctuations in the flow field. The computed stresses are then used as inputs to a Modified Bayesian Kriging method to generate surrogate models. The surrogates can be used as closure models for the pseudo-turbulent terms in macroscale computations of shock-particle interactions. It is found that the kinetic energy associated with the velocity fluctuations is comparable to that of the mean flow—especially for increasing M and φ . This work is a first attempt to quantify and evaluate the effect of velocity fluctuations for problems of shock-particle interactions.

  12. Adaptive Surrogate Modeling for Response Surface Approximations with Application to Bayesian Inference

    KAUST Repository

    Prudhomme, Serge

    2015-01-07

    The need for surrogate models and adaptive methods can be best appreciated if one is interested in parameter estimation using a Bayesian calibration procedure for validation purposes. We extend here our latest work on error decomposition and adaptive refinement for response surfaces to the development of surrogate models that can be substituted for the full models to estimate the parameters of Reynolds-averaged Navier-Stokes models. The error estimates and adaptive schemes are driven here by a quantity of interest and are thus based on the approximation of an adjoint problem. We will focus in particular to the accurate estimation of evidences to facilitate model selection. The methodology will be illustrated on the Spalart-Allmaras RANS model for turbulence simulation.

  13. Adaptive Surrogate Modeling for Response Surface Approximations with Application to Bayesian Inference

    KAUST Repository

    Prudhomme, Serge

    2015-01-01

    The need for surrogate models and adaptive methods can be best appreciated if one is interested in parameter estimation using a Bayesian calibration procedure for validation purposes. We extend here our latest work on error decomposition and adaptive refinement for response surfaces to the development of surrogate models that can be substituted for the full models to estimate the parameters of Reynolds-averaged Navier-Stokes models. The error estimates and adaptive schemes are driven here by a quantity of interest and are thus based on the approximation of an adjoint problem. We will focus in particular to the accurate estimation of evidences to facilitate model selection. The methodology will be illustrated on the Spalart-Allmaras RANS model for turbulence simulation.

  14. Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

    International Nuclear Information System (INIS)

    Hurwitz, Martina; Williams, Christopher L; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G; Mak, Raymond H; Lewis, John H

    2015-01-01

    Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes. (paper)

  15. Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

    Science.gov (United States)

    Hurwitz, Martina; Williams, Christopher L.; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G.; Mak, Raymond H.; Lewis, John H.

    2015-01-01

    Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes.

  16. Designing a Surrogate Fuel for Gas-to-Liquid Derived Diesel

    DEFF Research Database (Denmark)

    Choudhury, H. A.; Intikhab, S.; Kalakul, Sawitree

    2017-01-01

    loads, diesel fuel surpasses the total hydrocarbon (THC) emissions for both the surrogate and the GTL fuel. No significant variation in CO and CO2 emissions for MI-5, GTL diesel and conventional diesel is observed. Analysis of combustion as well as emission behavior of the fuels helps to understand...

  17. Fluorescent microspheres as surrogates in evaluating the efficacy of riverbank filtration for removing Cryptosporidium parvum oocysts and other pathogens

    Science.gov (United States)

    Harvey, Ronald W.; Metge, David W.; Sheets, Rodney A.; Jasperse, Jay

    2011-01-01

    A major benefit of riverbank filtration (RBF) is that it provides a relatively effective means for pathogen removal. There is a need to conduct more injection-and-recovery transport studies at operating RBF sites in order to properly assess the combined effects of the site heterogeneities and ambient physicochemical conditions, which are difficult to replicate in the lab. For field transport studies involving pathogens, there is considerable interest in using fluorescent carboxylated microspheres (FCM) as surrogates, because they are chemically inert, negatively charged, easy to detect, available in a wide variety of sizes, and have been found to be nonhazardous in tracer applications. Although there have been a number of in-situ studies comparing the subsurface transport behaviors of FCM to those of bacteria and viruses, much less is known about their suitability for investigations of protozoa. Oocysts of the intestinal protozoan pathogen Cryptosporidium spp are of particular concern for many RBF operations because of their ubiquity and persistence in rivers and high resistance to chlorine disinfection. Although microspheres often have proven to be less-than-ideal analogs for capturing the abiotic transport behavior of viruses and bacteria, there is encouraging recent evidence regarding use of FCM as surrogates for C. parvum oocysts. This chapter discusses the potential of fluorescent microspheres as safe and easy-to-detect surrogates for evaluating the efficacy of RBF operations for removing pathogens, particularly Cryptosporidium, from source waters at different points along the flow path.

  18. Inactivation kinetics and efficiencies of UV-LEDs against Pseudomonas aeruginosa, Legionella pneumophila, and surrogate microorganisms.

    Science.gov (United States)

    Rattanakul, Surapong; Oguma, Kumiko

    2018-03-01

    To demonstrate the effectiveness of UV light-emitting diodes (UV-LEDs) to disinfect water, UV-LEDs at peak emission wavelengths of 265, 280, and 300 nm were adopted to inactivate pathogenic species, including Pseudomonas aeruginosa and Legionella pneumophila, and surrogate species, including Escherichia coli, Bacillus subtilis spores, and bacteriophage Qβ in water, compared to conventional low-pressure UV lamp emitting at 254 nm. The inactivation profiles of each species showed either a linear or sigmoidal survival curve, which both fit well with the Geeraerd's model. Based on the inactivation rate constant, the 265-nm UV-LED showed most effective fluence, except for with E. coli which showed similar inactivation rates at 265 and 254 nm. Electrical energy consumption required for 3-log 10 inactivation (E E,3 ) was lowest for the 280-nm UV-LED for all microbial species tested. Taken together, the findings of this study determined the inactivation profiles and kinetics of both pathogenic bacteria and surrogate species under UV-LED exposure at different wavelengths. We also demonstrated that not only inactivation rate constants, but also energy efficiency should be considered when selecting an emission wavelength for UV-LEDs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. 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

  20. A reaction mechanism for gasoline surrogate fuels for large polycyclic aromatic hydrocarbons

    KAUST Repository

    Raj, Abhijeet

    2012-02-01

    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 surrogate fuels with the largest chemical species being pyrene (C 16H 10), this new mechanism is generated by adding PAH sub-mechanisms to account for the formation and growth of PAHs up to coronene (C 24H 12). The density functional theory (DFT) and the transition state theory (TST) have been adopted to evaluate the rate constants for several PAH reactions. The mechanism is validated in the premixed laminar flames of n-heptane, iso-octane, benzene and ethylene. The characteristics of PAH formation in the counterflow diffusion flames of iso-octane/toluene and n-heptane/toluene mixtures have also been tested for both the soot formation and soot formation/oxidation flame conditions. The predictions of the concentrations of large PAHs in the premixed flames having available experimental data are significantly improved with the new mechanism as compared to the base mechanism. The major pathways for the formation of large PAHs are identified. The test of the counterflow diffusion flames successfully predicts the PAH behavior exhibiting a synergistic effect observed experimentally for the mixture fuels, irrespective of the type of flame (soot formation flame or soot formation/oxidation flame). The reactions that lead to this synergistic effect in PAH formation are identified through the rate-of-production analysis. © 2011 The Combustion Institute.

  1. 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.

  2. Protein Comparability Assessments and Potential Applicability of High Throughput Biophysical Methods and Data Visualization Tools to Compare Physical Stability Profiles

    Directory of Open Access Journals (Sweden)

    Mohammad A. Alsenaidy

    2014-03-01

    Full Text Available In this review, some of the challenges and opportunities encountered during protein comparability assessments are summarized with an emphasis on developing new analytical approaches to better monitor higher-order protein structures. Several case studies are presented using high throughput biophysical methods to collect protein physical stability data as function of temperature, agitation, ionic strength and/or solution pH. These large data sets were then used to construct empirical phase diagrams (EPDs, radar charts, and comparative signature diagrams (CSDs for data visualization and structural comparisons between the different proteins. Protein samples with different sizes, post-translational modifications, and inherent stability are presented: acidic fibroblast growth factor (FGF-1 mutants, different glycoforms of an IgG1 mAb prepared by deglycosylation, as well as comparisons of different formulations of an IgG1 mAb and granulocyte colony stimulating factor (GCSF. Using this approach, differences in structural integrity and conformational stability profiles were detected under stress conditions that could not be resolved by using the same techniques under ambient conditions (i.e., no stress. Thus, an evaluation of conformational stability differences may serve as an effective surrogate to monitor differences in higher-order structure between protein samples. These case studies are discussed in the context of potential utility in protein comparability studies.

  3. Protein comparability assessments and potential applicability of high throughput biophysical methods and data visualization tools to compare physical stability profiles.

    Science.gov (United States)

    Alsenaidy, Mohammad A; Jain, Nishant K; Kim, Jae H; Middaugh, C Russell; Volkin, David B

    2014-01-01

    In this review, some of the challenges and opportunities encountered during protein comparability assessments are summarized with an emphasis on developing new analytical approaches to better monitor higher-order protein structures. Several case studies are presented using high throughput biophysical methods to collect protein physical stability data as function of temperature, agitation, ionic strength and/or solution pH. These large data sets were then used to construct empirical phase diagrams (EPDs), radar charts, and comparative signature diagrams (CSDs) for data visualization and structural comparisons between the different proteins. Protein samples with different sizes, post-translational modifications, and inherent stability are presented: acidic fibroblast growth factor (FGF-1) mutants, different glycoforms of an IgG1 mAb prepared by deglycosylation, as well as comparisons of different formulations of an IgG1 mAb and granulocyte colony stimulating factor (GCSF). Using this approach, differences in structural integrity and conformational stability profiles were detected under stress conditions that could not be resolved by using the same techniques under ambient conditions (i.e., no stress). Thus, an evaluation of conformational stability differences may serve as an effective surrogate to monitor differences in higher-order structure between protein samples. These case studies are discussed in the context of potential utility in protein comparability studies.

  4. Discovery of native autoantigens via antigen surrogate technology: application to type 1 diabetes.

    Science.gov (United States)

    Doran, Todd M; Simanski, Scott; Kodadek, Thomas

    2015-02-20

    A fundamental goal in understanding the mechanisms of autoimmune disease is the characterization of autoantigens that are targeted by autoreactive antibodies and T cells. Unfortunately, the identification of autoantigens is a difficult problem. We have begun to explore a novel route to the discovery of autoantibody/autoantigen pairs that involves comparative screening of combinatorial libraries of unnatural, synthetic molecules for compounds that bind antibodies present at much higher levels in the serum of individuals with a given autoimmune disease than in the serum of control individuals. We have shown that this approach can yield "antigen surrogates" capable of capturing disease-specific autoantibodies from serum. In this report, we demonstrate that the synthetic antigen surrogates can be used to affinity purify the autoantibodies from serum and that these antibodies can then be used to identify their cognate autoantigen in an appropriate tissue lysate. Specifically, we report the discovery of a peptoid able to bind autoantibodies present in about one-third of nonobese diabetic (NOD) mice. The peptoid-binding autoantibodies were highly enriched through peptoid affinity chromatography and employed to probe mouse pancreatic and brain lysates. This resulted in identification of murine GAD65 as the native autoantigen. GAD65 is a known humoral autoantigen in human type 1 diabetes mellitus (T1DM), but its existence in mice had been controversial. This study demonstrates the potential of this chemical approach for the unbiased identification of autoantigen/autoantibody complexes.

  5. Structural Damage Detection using Frequency Response Function Index and Surrogate Model Based on Optimized Extreme Learning Machine Algorithm

    Directory of Open Access Journals (Sweden)

    R. Ghiasi

    2017-09-01

    Full Text Available Utilizing surrogate models based on artificial intelligence methods for detecting structural damages has attracted the attention of many researchers in recent decades. In this study, a new kernel based on Littlewood-Paley Wavelet (LPW is proposed for Extreme Learning Machine (ELM algorithm to improve the accuracy of detecting multiple damages in structural systems.  ELM is used as metamodel (surrogate model of exact finite element analysis of structures in order to efficiently reduce the computational cost through updating process. In the proposed two-step method, first a damage index, based on Frequency Response Function (FRF of the structure, is used to identify the location of damages. In the second step, the severity of damages in identified elements is detected using ELM. In order to evaluate the efficacy of ELM, the results obtained from the proposed kernel were compared with other kernels proposed for ELM as well as Least Square Support Vector Machine algorithm. The solved numerical problems indicated that ELM algorithm accuracy in detecting structural damages is increased drastically in case of using LPW kernel.

  6. 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...

  7. Accurate quantification of endogenous androgenic steroids in cattle's meat by gas chromatography mass spectrometry using a surrogate analyte approach