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Sample records for additive model results

  1. Comparing GWAS Results of Complex Traits Using Full Genetic Model and Additive Models for Revealing Genetic Architecture

    PubMed Central

    Monir, Md. Mamun; Zhu, Jun

    2017-01-01

    Most of the genome-wide association studies (GWASs) for human complex diseases have ignored dominance, epistasis and ethnic interactions. We conducted comparative GWASs for total cholesterol using full model and additive models, which illustrate the impacts of the ignoring genetic variants on analysis results and demonstrate how genetic effects of multiple loci could differ across different ethnic groups. There were 15 quantitative trait loci with 13 individual loci and 3 pairs of epistasis loci identified by full model, whereas only 14 loci (9 common loci and 5 different loci) identified by multi-loci additive model. Again, 4 full model detected loci were not detected using multi-loci additive model. PLINK-analysis identified two loci and GCTA-analysis detected only one locus with genome-wide significance. Full model identified three previously reported genes as well as several new genes. Bioinformatics analysis showed some new genes are related with cholesterol related chemicals and/or diseases. Analyses of cholesterol data and simulation studies revealed that the full model performs were better than the additive-model performs in terms of detecting power and unbiased estimations of genetic variants of complex traits. PMID:28079101

  2. Model assessment of additional contamination of water bodies as a result of wildfires in the Chernobyl exclusion zone.

    PubMed

    Bondar, Yu I; Navumau, A D; Nikitin, A N; Brown, J; Dowdall, M

    2014-12-01

    Forest fires and wild fires are recognized as a possible cause of resuspension and redistribution of radioactive substances when occurring on lands contaminated with such materials, and as such are a matter of concern within the regions of Belarus and the Ukraine which were contaminated by the Chernobyl accident in 1986. Modelling the effects of such fires on radioactive contaminants is a complex matter given the number of variables involved. In this paper, a probabilistic model was developed using empirical data drawn from the Polessie State Radiation-Ecological Reserve (PSRER), Belarus, and the Maximum Entropy Method. Using the model, it was possible to derive estimates of the contribution of fire events to overall variability in the levels of (137)Cs and (239,240)Pu in ground air as well as estimates of the deposition of these radionuclides to specific water bodies within the contaminated areas of Belarus. Results indicate that fire events are potentially significant redistributors of radioactive contaminants within the study area and may result in additional contamination being introduced to water bodies.

  3. Group Sparse Additive Models

    PubMed Central

    Yin, Junming; Chen, Xi; Xing, Eric P.

    2016-01-01

    We consider the problem of sparse variable selection in nonparametric additive models, with the prior knowledge of the structure among the covariates to encourage those variables within a group to be selected jointly. Previous works either study the group sparsity in the parametric setting (e.g., group lasso), or address the problem in the nonparametric setting without exploiting the structural information (e.g., sparse additive models). In this paper, we present a new method, called group sparse additive models (GroupSpAM), which can handle group sparsity in additive models. We generalize the ℓ1/ℓ2 norm to Hilbert spaces as the sparsity-inducing penalty in GroupSpAM. Moreover, we derive a novel thresholding condition for identifying the functional sparsity at the group level, and propose an efficient block coordinate descent algorithm for constructing the estimate. We demonstrate by simulation that GroupSpAM substantially outperforms the competing methods in terms of support recovery and prediction accuracy in additive models, and also conduct a comparative experiment on a real breast cancer dataset.

  4. Functional Generalized Additive Models.

    PubMed

    McLean, Mathew W; Hooker, Giles; Staicu, Ana-Maria; Scheipl, Fabian; Ruppert, David

    2014-01-01

    We introduce the functional generalized additive model (FGAM), a novel regression model for association studies between a scalar response and a functional predictor. We model the link-transformed mean response as the integral with respect to t of F{X(t), t} where F(·,·) is an unknown regression function and X(t) is a functional covariate. Rather than having an additive model in a finite number of principal components as in Müller and Yao (2008), our model incorporates the functional predictor directly and thus our model can be viewed as the natural functional extension of generalized additive models. We estimate F(·,·) using tensor-product B-splines with roughness penalties. A pointwise quantile transformation of the functional predictor is also considered to ensure each tensor-product B-spline has observed data on its support. The methods are evaluated using simulated data and their predictive performance is compared with other competing scalar-on-function regression alternatives. We illustrate the usefulness of our approach through an application to brain tractography, where X(t) is a signal from diffusion tensor imaging at position, t, along a tract in the brain. In one example, the response is disease-status (case or control) and in a second example, it is the score on a cognitive test. R code for performing the simulations and fitting the FGAM can be found in supplemental materials available online.

  5. Fused Lasso Additive Model

    PubMed Central

    Petersen, Ashley; Witten, Daniela; Simon, Noah

    2016-01-01

    We consider the problem of predicting an outcome variable using p covariates that are measured on n independent observations, in a setting in which additive, flexible, and interpretable fits are desired. We propose the fused lasso additive model (FLAM), in which each additive function is estimated to be piecewise constant with a small number of adaptively-chosen knots. FLAM is the solution to a convex optimization problem, for which a simple algorithm with guaranteed convergence to a global optimum is provided. FLAM is shown to be consistent in high dimensions, and an unbiased estimator of its degrees of freedom is proposed. We evaluate the performance of FLAM in a simulation study and on two data sets. Supplemental materials are available online, and the R package flam is available on CRAN. PMID:28239246

  6. Additive reductions in zebrafish PRPS1 activity result in a spectrum of deficiencies modeling several human PRPS1-associated diseases

    PubMed Central

    Pei, Wuhong; Xu, Lisha; Varshney, Gaurav K.; Carrington, Blake; Bishop, Kevin; Jones, MaryPat; Huang, Sunny C.; Idol, Jennifer; Pretorius, Pamela R.; Beirl, Alisha; Schimmenti, Lisa A.; Kindt, Katie S.; Sood, Raman; Burgess, Shawn M.

    2016-01-01

    Phosphoribosyl pyrophosphate synthetase-1 (PRPS1) is a key enzyme in nucleotide biosynthesis, and mutations in PRPS1 are found in several human diseases including nonsyndromic sensorineural deafness, Charcot-Marie-Tooth disease-5, and Arts Syndrome. We utilized zebrafish as a model to confirm that mutations in PRPS1 result in phenotypic deficiencies in zebrafish similar to those in the associated human diseases. We found two paralogs in zebrafish, prps1a and prps1b and characterized each paralogous mutant individually as well as the double mutant fish. Zebrafish prps1a mutants and prps1a;prps1b double mutants showed similar morphological phenotypes with increasingly severe phenotypes as the number of mutant alleles increased. Phenotypes included smaller eyes and reduced hair cell numbers, consistent with the optic atrophy and hearing impairment observed in human patients. The double mutant also showed abnormal development of primary motor neurons, hair cell innervation, and reduced leukocytes, consistent with the neuropathy and recurrent infection of the human patients possessing the most severe reductions of PRPS1 activity. Further analyses indicated the phenotypes were associated with a prolonged cell cycle likely resulting from reduced nucleotide synthesis and energy production in the mutant embryos. We further demonstrated the phenotypes were caused by delays in the tissues most highly expressing the prps1 genes. PMID:27425195

  7. Computational Process Modeling for Additive Manufacturing

    NASA Technical Reports Server (NTRS)

    Bagg, Stacey; Zhang, Wei

    2014-01-01

    Computational Process and Material Modeling of Powder Bed additive manufacturing of IN 718. Optimize material build parameters with reduced time and cost through modeling. Increase understanding of build properties. Increase reliability of builds. Decrease time to adoption of process for critical hardware. Potential to decrease post-build heat treatments. Conduct single-track and coupon builds at various build parameters. Record build parameter information and QM Meltpool data. Refine Applied Optimization powder bed AM process model using data. Report thermal modeling results. Conduct metallography of build samples. Calibrate STK models using metallography findings. Run STK models using AO thermal profiles and report STK modeling results. Validate modeling with additional build. Photodiode Intensity measurements highly linear with power input. Melt Pool Intensity highly correlated to Melt Pool Size. Melt Pool size and intensity increase with power. Applied Optimization will use data to develop powder bed additive manufacturing process model.

  8. Health effects models for nuclear power plant accident consequence analysis. Modification of models resulting from addition of effects of exposure to alpha-emitting radionuclides: Revision 1, Part 2, Scientific bases for health effects models, Addendum 2

    SciTech Connect

    Abrahamson, S.; Bender, M.A.; Boecker, B.B.; Scott, B.R.; Gilbert, E.S.

    1993-05-01

    The Nuclear Regulatory Commission (NRC) has sponsored several studies to identify and quantify, through the use of models, the potential health effects of accidental releases of radionuclides from nuclear power plants. The Reactor Safety Study provided the basis for most of the earlier estimates related to these health effects. Subsequent efforts by NRC-supported groups resulted in improved health effects models that were published in the report entitled {open_quotes}Health Effects Models for Nuclear Power Plant Consequence Analysis{close_quotes}, NUREG/CR-4214, 1985 and revised further in the 1989 report NUREG/CR-4214, Rev. 1, Part 2. The health effects models presented in the 1989 NUREG/CR-4214 report were developed for exposure to low-linear energy transfer (LET) (beta and gamma) radiation based on the best scientific information available at that time. Since the 1989 report was published, two addenda to that report have been prepared to (1) incorporate other scientific information related to low-LET health effects models and (2) extend the models to consider the possible health consequences of the addition of alpha-emitting radionuclides to the exposure source term. The first addendum report, entitled {open_quotes}Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting from Recent Reports on Health Effects of Ionizing Radiation, Low LET Radiation, Part 2: Scientific Bases for Health Effects Models,{close_quotes} was published in 1991 as NUREG/CR-4214, Rev. 1, Part 2, Addendum 1. This second addendum addresses the possibility that some fraction of the accident source term from an operating nuclear power plant comprises alpha-emitting radionuclides. Consideration of chronic high-LET exposure from alpha radiation as well as acute and chronic exposure to low-LET beta and gamma radiations is a reasonable extension of the health effects model.

  9. Does early intensive multifactorial therapy reduce modelled cardiovascular risk in individuals with screen-detected diabetes? Results from the ADDITION-Europe cluster randomized trial

    PubMed Central

    Black, J A; Sharp, S J; Wareham, N J; Sandbæk, A; Rutten, G E H M; Lauritzen, T; Khunti, K; Davies, M J; Borch-Johnsen, K; Griffin, S J; Simmons, R K

    2014-01-01

    Aims Little is known about the long-term effects of intensive multifactorial treatment early in the diabetes disease trajectory. In the absence of long-term data on hard outcomes, we described change in 10-year modelled cardiovascular risk in the 5 years following diagnosis, and quantified the impact of intensive treatment on 10-year modelled cardiovascular risk at 5 years. Methods In a pragmatic, cluster-randomized, parallel-group trial in Denmark, the Netherlands and the UK, 3057 people with screen-detected Type 2 diabetes were randomized by general practice to receive (1) routine care of diabetes according to national guidelines (1379 patients) or (2) intensive multifactorial target-driven management (1678 patients). Ten-year modelled cardiovascular disease risk was calculated at baseline and 5 years using the UK Prospective Diabetes Study Risk Engine (version 3β). Results Among 2101 individuals with complete data at follow up (73.4%), 10-year modelled cardiovascular disease risk was 27.3% (sd 13.9) at baseline and 21.3% (sd 13.8) at 5-year follow-up (intensive treatment group difference –6.9, sd 9.0; routine care group difference –5.0, sd 12.2). Modelled 10-year cardiovascular disease risk was lower in the intensive treatment group compared with the routine care group at 5 years, after adjustment for baseline cardiovascular disease risk and clustering (–2.0; 95% CI –3.1 to –0.9). Conclusions Despite increasing age and diabetes duration, there was a decline in modelled cardiovascular disease risk in the 5 years following diagnosis. Compared with routine care, 10-year modelled cardiovascular disease risk was lower in the intensive treatment group at 5 years. Our results suggest that patients benefit from intensive treatment early in the diabetes disease trajectory, where the rate of cardiovascular disease risk progression may be slowed. PMID:24533664

  10. Additional Results of Ice-Accretion Scaling at SLD Conditions

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H. (Technical Monitor); Anderson, David N.; Tsao, Jen-Ching

    2005-01-01

    To determine scale velocity an additional similarity parameter is needed to supplement the Ruff scaling method. A Weber number based on water droplet MVD has been included in several studies because the effect of droplet splashing on ice accretion was believed to be important, particularly for SLD conditions. In the present study, ice shapes recorded at Appendix-C conditions and recent results at SLD conditions are reviewed to show that droplet diameter cannot be important to main ice shape, and for low airspeeds splashing does not appear to affect SLD ice shapes. Evidence is presented to show that while a supplementary similarity parameter probably has the form of a Weber number, it must be based on a length proportional to model size rather than MVD. Scaling comparisons were made between SLD reference conditions and Appendix-C scale conditions using this Weber number. Scale-to-reference model size ratios were 1:1.7 and 1:3.4. The reference tests used a 91-cm-chord NACA 0012 model with a velocity of approximately 50 m/s and an MVD of 160 m. Freezing fractions of 0.3, 0.4, and 0.5 were included in the study.

  11. Mars-GRAM 2010: Additions and Resulting Improvements

    NASA Technical Reports Server (NTRS)

    Justh, Hilary L.; Burns, K. Lee

    2013-01-01

    The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM has been utilized during previous aerobraking operations in the atmosphere of Mars. Mars-GRAM has also been used in the prediction and validation of Mars Pathfinder hypersonic aerodynamics, the aerothermodynamic and entry dynamics studies for Mars Polar Lander, the landing site selection process for the Mars Science Laboratory (MSL), the Mars Aerocapture System Study (MASS) as well as the Aerocapture Technology Assessment Group (TAG). Most recently, Mars-GRAM 2010 was used to develop the onboard atmospheric density estimator that is part of the Autonomous Aerobraking Development Plan. The most recent release of Mars-GRAM 2010 contains several changes including an update to Fortran 90/95 and the addition of adjustment factors. Following the completion of a comparison analysis between Mars-GRAM, Thermal Emission Spectrometer (TES), as well as Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) aerobraking density data, adjustment factors were added to Mars-GRAM 2010 that alter the input data from National Aeronautics and Space Administration (NASA) Ames Mars General Circulation Model (MGCM) and the University of Michigan Mars Thermospheric General Circulation Model (MTGCM) for the mapping year 0 user-controlled dust case. The addition of adjustment factors resolved the issue of previous versions of Mars-GRAM being less than realistic when used for sensitivity studies for mapping year 0 and large optical depth values, such as tau equal to 3. Mars-GRAM was evaluated at locations and times of TES limb observations and adjustment factors were determined. For altitudes above 80 km and below 135 km, Mars-GRAM (MTGCM) densities were compared to aerobraking densities measured by Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) to determine the adjustment

  12. Network Reconstruction Using Nonparametric Additive ODE Models

    PubMed Central

    Henderson, James; Michailidis, George

    2014-01-01

    Network representations of biological systems are widespread and reconstructing unknown networks from data is a focal problem for computational biologists. For example, the series of biochemical reactions in a metabolic pathway can be represented as a network, with nodes corresponding to metabolites and edges linking reactants to products. In a different context, regulatory relationships among genes are commonly represented as directed networks with edges pointing from influential genes to their targets. Reconstructing such networks from data is a challenging problem receiving much attention in the literature. There is a particular need for approaches tailored to time-series data and not reliant on direct intervention experiments, as the former are often more readily available. In this paper, we introduce an approach to reconstructing directed networks based on dynamic systems models. Our approach generalizes commonly used ODE models based on linear or nonlinear dynamics by extending the functional class for the functions involved from parametric to nonparametric models. Concomitantly we limit the complexity by imposing an additive structure on the estimated slope functions. Thus the submodel associated with each node is a sum of univariate functions. These univariate component functions form the basis for a novel coupling metric that we define in order to quantify the strength of proposed relationships and hence rank potential edges. We show the utility of the method by reconstructing networks using simulated data from computational models for the glycolytic pathway of Lactocaccus Lactis and a gene network regulating the pluripotency of mouse embryonic stem cells. For purposes of comparison, we also assess reconstruction performance using gene networks from the DREAM challenges. We compare our method to those that similarly rely on dynamic systems models and use the results to attempt to disentangle the distinct roles of linearity, sparsity, and derivative

  13. Additional Results of Glaze Icing Scaling in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2016-01-01

    New guidance of acceptable means of compliance with the super-cooled large drops (SLD) conditions has been issued by the U.S. Department of Transportation's Federal Aviation Administration (FAA) in its Advisory Circular AC 25-28 in November 2014. The Part 25, Appendix O is developed to define a representative icing environment for super-cooled large drops. Super-cooled large drops, which include freezing drizzle and freezing rain conditions, are not included in Appendix C. This paper reports results from recent glaze icing scaling tests conducted in NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the scaling methods recommended for Appendix C conditions might apply to SLD conditions. The models were straight NACA 0012 wing sections. The reference model had a chord of 72 in. and the scale model had a chord of 21 in. Reference tests were run with airspeeds of 100 and 130.3 kn and with MVD's of 85 and 170 micron. Two scaling methods were considered. One was based on the modified Ruff method with scale velocity found by matching the Weber number WeL. The other was proposed and developed by Feo specifically for strong glaze icing conditions, in which the scale liquid water content and velocity were found by matching reference and scale values of the nondimensional water-film thickness expression and the film Weber number Wef. All tests were conducted at 0 deg AOA. Results will be presented for stagnation freezing fractions of 0.2 and 0.3. For nondimensional reference and scale ice shape comparison, a new post-scanning ice shape digitization procedure was developed for extracting 2-D ice shape profiles at any selected span-wise location from the high fidelity 3-D scanned ice shapes obtained in the IRT.

  14. Additional Results of Glaze Icing Scaling in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2016-01-01

    New guidance of acceptable means of compliance with the super-cooled large drops (SLD) conditions has been issued by the U.S. Department of Transportation's Federal Aviation Administration (FAA) in its Advisory Circular AC 25-28 in November 2014. The Part 25, Appendix O is developed to define a representative icing environment for super-cooled large drops. Super-cooled large drops, which include freezing drizzle and freezing rain conditions, are not included in Appendix C. This paper reports results from recent glaze icing scaling tests conducted in NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the scaling methods recommended for Appendix C conditions might apply to SLD conditions. The models were straight NACA 0012 wing sections. The reference model had a chord of 72 inches and the scale model had a chord of 21 inches. Reference tests were run with airspeeds of 100 and 130.3 knots and with MVD's of 85 and 170 microns. Two scaling methods were considered. One was based on the modified Ruff method with scale velocity found by matching the Weber number W (sub eL). The other was proposed and developed by Feo specifically for strong glaze icing conditions, in which the scale liquid water content and velocity were found by matching reference and scale values of the non-dimensional water-film thickness expression and the film Weber number W (sub ef). All tests were conducted at 0 degrees angle of arrival. Results will be presented for stagnation freezing fractions of 0.2 and 0.3. For non-dimensional reference and scale ice shape comparison, a new post-scanning ice shape digitization procedure was developed for extracting 2-dimensional ice shape profiles at any selected span-wise location from the high fidelity 3-dimensional scanned ice shapes obtained in the IRT.

  15. Health Effects Models for Nuclear Power Plant Accident Consequence Analysis. Modification of Models Resulting from Addition of Effects of Exposure to Alpha-Emitting Radionuclides. Part 2. Scientific Bases for Health Effects Models. Revision 1. Addendum 2.

    DTIC Science & Technology

    1993-05-01

    been Sponsored by the Nuclear Regulatory Commission. Report NUREG /CR-2l4, Rev. 1, Part II (NRC, 1989a) describes in detail the most recent health...that address early-occurring and continuing effects, late somatic effects, and genetic effects. These results should be used with the basic NUREG

  16. Dimensional changes in stone models simulating full crown preparations with adjacent teeth resulting from long-term immersion of medium-viscosity addition-type silicone rubber impressions in disinfectant solutions.

    PubMed

    Hiraguchi, Hisako; Iwasaki, Yukiko; Iwasaki, Eriko; Kikuchi, Hisaji; Hirose, Hideharu; Yoneyama, Takayuki

    2015-01-01

    If impression materials could be immersed in disinfectant solutions for a longer period, then this form of disinfection would be easier to incorporate into dental preparation procedures. This study investigated the dimensional changes in stone models resulting from immersion of medium-viscosity hydrophilic addition-type silicone rubber impression material in disinfectant solutions for 30 min and 24 h. Impressions of a master die designed to simulate a full crown preparation with adjacent teeth were immersed in 2% glutaraldehyde and 0.55% ortho-phthalaldehyde solutions. The dimensional changes in the mesiodistal and buccolingual dimensions in the stone models were then measured using a three-dimensional coordinate system. It was found that the dimensional changes in the stone models caused by immersion of the impression materials were less than 15 μm. Immersion in 2% glutaraldehyde or 0.55% ortho-phthalaldehyde for 24 h was as clinically acceptable for medium-viscosity hydrophilic addition-type silicone rubber impressions as immersion for 30 min.

  17. Computational Process Modeling for Additive Manufacturing (OSU)

    NASA Technical Reports Server (NTRS)

    Bagg, Stacey; Zhang, Wei

    2015-01-01

    Powder-Bed Additive Manufacturing (AM) through Direct Metal Laser Sintering (DMLS) or Selective Laser Melting (SLM) is being used by NASA and the Aerospace industry to "print" parts that traditionally are very complex, high cost, or long schedule lead items. The process spreads a thin layer of metal powder over a build platform, then melts the powder in a series of welds in a desired shape. The next layer of powder is applied, and the process is repeated until layer-by-layer, a very complex part can be built. This reduces cost and schedule by eliminating very complex tooling and processes traditionally used in aerospace component manufacturing. To use the process to print end-use items, NASA seeks to understand SLM material well enough to develop a method of qualifying parts for space flight operation. Traditionally, a new material process takes many years and high investment to generate statistical databases and experiential knowledge, but computational modeling can truncate the schedule and cost -many experiments can be run quickly in a model, which would take years and a high material cost to run empirically. This project seeks to optimize material build parameters with reduced time and cost through modeling.

  18. Additional Results of Glaze Icing Scaling in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2016-01-01

    This presentation reports results from recent icing scaling tests in NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the scaling method recommended for Appendix C conditions might apply to SLD conditions.

  19. CREATION OF THE MODEL ADDITIONAL PROTOCOL

    SciTech Connect

    Houck, F.; Rosenthal, M.; Wulf, N.

    2010-05-25

    In 1991, the international nuclear nonproliferation community was dismayed to discover that the implementation of safeguards by the International Atomic Energy Agency (IAEA) under its NPT INFCIRC/153 safeguards agreement with Iraq had failed to detect Iraq's nuclear weapon program. It was now clear that ensuring that states were fulfilling their obligations under the NPT would require not just detecting diversion but also the ability to detect undeclared materials and activities. To achieve this, the IAEA initiated what would turn out to be a five-year effort to reappraise the NPT safeguards system. The effort engaged the IAEA and its Member States and led to agreement in 1997 on a new safeguards agreement, the Model Protocol Additional to the Agreement(s) between States and the International Atomic Energy Agency for the Application of Safeguards. The Model Protocol makes explicit that one IAEA goal is to provide assurance of the absence of undeclared nuclear material and activities. The Model Protocol requires an expanded declaration that identifies a State's nuclear potential, empowers the IAEA to raise questions about the correctness and completeness of the State's declaration, and, if needed, allows IAEA access to locations. The information required and the locations available for access are much broader than those provided for under INFCIRC/153. The negotiation was completed in quite a short time because it started with a relatively complete draft of an agreement prepared by the IAEA Secretariat. This paper describes how the Model Protocol was constructed and reviews key decisions that were made both during the five-year period and in the actual negotiation.

  20. Small-Scale Spray Releases: Additional Aerosol Test Results

    SciTech Connect

    Schonewill, Philip P.; Gauglitz, Phillip A.; Kimura, Marcia L.; Brown, G. N.; Mahoney, Lenna A.; Tran, Diana N.; Burns, Carolyn A.; Kurath, Dean E.

    2013-08-01

    One of the events postulated in the hazard analysis at the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids with Newtonian fluid behavior. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and across processing facilities in the DOE complex. To expand the data set upon which the WTP accident and safety analyses were based, an aerosol spray leak testing program was conducted by Pacific Northwest National Laboratory (PNNL). PNNL’s test program addressed two key technical areas to improve the WTP methodology (Larson and Allen 2010). The first technical area was to quantify the role of slurry particles in small breaches where slurry particles may plug the hole and prevent high-pressure sprays. The results from an effort to address this first technical area can be found in Mahoney et al. (2012a). The second technical area was to determine aerosol droplet size distribution and total droplet volume from prototypic breaches and fluids, including sprays from larger breaches and sprays of slurries for which literature data are largely absent. To address the second technical area, the testing program collected aerosol generation data at two scales, commonly referred to as small-scale and large-scale. The small-scale testing and resultant data are described in Mahoney et al. (2012b) and the large-scale testing and resultant data are presented in Schonewill et al. (2012). In tests at both scales, simulants were used to mimic the

  1. Large-Scale Spray Releases: Additional Aerosol Test Results

    SciTech Connect

    Daniel, Richard C.; Gauglitz, Phillip A.; Burns, Carolyn A.; Fountain, Matthew S.; Shimskey, Rick W.; Billing, Justin M.; Bontha, Jagannadha R.; Kurath, Dean E.; Jenks, Jeromy WJ; MacFarlan, Paul J.; Mahoney, Lenna A.

    2013-08-01

    One of the events postulated in the hazard analysis for the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak event involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids that behave as a Newtonian fluid. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and in processing facilities across the DOE complex. To expand the data set upon which the WTP accident and safety analyses were based, an aerosol spray leak testing program was conducted by Pacific Northwest National Laboratory (PNNL). PNNL’s test program addressed two key technical areas to improve the WTP methodology (Larson and Allen 2010). The first technical area was to quantify the role of slurry particles in small breaches where slurry particles may plug the hole and prevent high-pressure sprays. The results from an effort to address this first technical area can be found in Mahoney et al. (2012a). The second technical area was to determine aerosol droplet size distribution and total droplet volume from prototypic breaches and fluids, including sprays from larger breaches and sprays of slurries for which literature data are mostly absent. To address the second technical area, the testing program collected aerosol generation data at two scales, commonly referred to as small-scale and large-scale testing. The small-scale testing and resultant data are described in Mahoney et al. (2012b), and the large-scale testing and resultant data are presented in Schonewill et al. (2012). In tests at both scales, simulants were used

  2. Complex Modelling Scheme Of An Additive Manufacturing Centre

    NASA Astrophysics Data System (ADS)

    Popescu, Liliana Georgeta

    2015-09-01

    This paper presents a modelling scheme sustaining the development of an additive manufacturing research centre model and its processes. This modelling is performed using IDEF0, the resulting model process representing the basic processes required in developing such a centre in any university. While the activities presented in this study are those recommended in general, changes may occur in specific existing situations in a research centre.

  3. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  4. An Additional Symmetry in the Weinberg-Salam Model

    SciTech Connect

    Bakker, B.L.G.; Veselov, A.I.; Zubkov, M.A.

    2005-06-01

    An additional Z{sub 6} symmetry hidden in the fermion and Higgs sectors of the Standard Model has been found recently. It has a singular nature and is connected to the centers of the SU(3) and SU(2) subgroups of the gauge group. A lattice regularization of the Standard Model was constructed that possesses this symmetry. In this paper, we report our results on the numerical simulation of its electroweak sector.

  5. Development of Additional Hazard Assessment Models

    DTIC Science & Technology

    1977-03-01

    the case of continuous release of liquid, the pool teaches a maximum radius for constant liquid regression rate. Therefore, when a fire results on an...Propylene", Ind. J. Tech 5, 81 (1967). 11. Kobe, K. A. and Long, E. G., " Thermochemistry for the Petrochemical Industry, Part III - Monoolefinic

  6. Geophysical Model Research and Results

    SciTech Connect

    Pasyanos, M; Walter, W; Tkalcic, H; Franz, G; Flanagan, M

    2004-07-07

    Geophysical models constitute an important component of calibration for nuclear explosion monitoring. We will focus on four major topics: (1) a priori geophysical models, (2) surface wave models, (3) receiver function derived profiles, and (4) stochastic geophysical models. The first, a priori models, can be used to predict a host of geophysical measurements, such as body wave travel times, and can be derived from direct regional studies or even by geophysical analogy. Use of these models is particularly important in aseismic regions or regions without seismic stations, where data of direct measurements might not exist. Lawrence Livermore National Laboratory (LLNL) has developed the Western Eurasia and North Africa (WENA) model which has been evaluated using a number of data sets, including travel times, surface waves, receiver functions, and waveform analysis (Pasyanos et al., 2004). We have joined this model with our Yellow Sea - Korean Peninsula (YSKP) model and the Los Alamos National Laboratory (LANL) East Asia model to construct a model for all of Eurasia and North Africa. Secondly, we continue to improve upon our surface wave model by adding more paths. This has allowed us to expand the region to all of Eurasia and into Africa, increase the resolution of our model, and extend results to even shorter periods (7 sec). High-resolution models exist for the Middle East and the YSKP region. The surface wave results can be inverted either alone, or in conjunction with other data, to derive models of the crust and upper mantle structure. We are also using receiver functions, in joint inversions with the surface waves, to produce profiles directly under seismic stations throughout the region. In a collaborative project with Ammon, et al., they have been focusing on stations throughout western Eurasia and North Africa, while we have been focusing on LLNL deployments in the Middle East, including Kuwait, Jordan, and the United Arab Emirates. Finally, we have been

  7. Modeling Errors in Daily Precipitation Measurements: Additive or Multiplicative?

    NASA Technical Reports Server (NTRS)

    Tian, Yudong; Huffman, George J.; Adler, Robert F.; Tang, Ling; Sapiano, Matthew; Maggioni, Viviana; Wu, Huan

    2013-01-01

    The definition and quantification of uncertainty depend on the error model used. For uncertainties in precipitation measurements, two types of error models have been widely adopted: the additive error model and the multiplicative error model. This leads to incompatible specifications of uncertainties and impedes intercomparison and application.In this letter, we assess the suitability of both models for satellite-based daily precipitation measurements in an effort to clarify the uncertainty representation. Three criteria were employed to evaluate the applicability of either model: (1) better separation of the systematic and random errors; (2) applicability to the large range of variability in daily precipitation; and (3) better predictive skills. It is found that the multiplicative error model is a much better choice under all three criteria. It extracted the systematic errors more cleanly, was more consistent with the large variability of precipitation measurements, and produced superior predictions of the error characteristics. The additive error model had several weaknesses, such as non constant variance resulting from systematic errors leaking into random errors, and the lack of prediction capability. Therefore, the multiplicative error model is a better choice.

  8. Generalised additive modelling approach to the fermentation process of glutamate.

    PubMed

    Liu, Chun-Bo; Li, Yun; Pan, Feng; Shi, Zhong-Ping

    2011-03-01

    In this work, generalised additive models (GAMs) were used for the first time to model the fermentation of glutamate (Glu). It was found that three fermentation parameters fermentation time (T), dissolved oxygen (DO) and oxygen uptake rate (OUR) could capture 97% variance of the production of Glu during the fermentation process through a GAM model calibrated using online data from 15 fermentation experiments. This model was applied to investigate the individual and combined effects of T, DO and OUR on the production of Glu. The conditions to optimize the fermentation process were proposed based on the simulation study from this model. Results suggested that the production of Glu can reach a high level by controlling concentration levels of DO and OUR to the proposed optimization conditions during the fermentation process. The GAM approach therefore provides an alternative way to model and optimize the fermentation process of Glu.

  9. Modeling uranium transport in acidic contaminated groundwater with base addition.

    PubMed

    Zhang, Fan; Luo, Wensui; Parker, Jack C; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

    2011-06-15

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO(3)(-), SO(4)(2-), U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  10. Influence of dispersing additive on asphaltenes aggregation in model system

    NASA Astrophysics Data System (ADS)

    Gorshkov, A. M.; Shishmina, L. V.; Tukhvatullina, A. Z.; Ismailov, Yu R.; Ges, G. A.

    2016-09-01

    The work is devoted to investigation of the dispersing additive influence on asphaltenes aggregation in the asphaltenes-toluene-heptane model system by photon correlation spectroscopy method. The experimental relationship between the onset point of asphaltenes and their concentration in toluene has been obtained. The influence of model system composition on asphaltenes aggregation has been researched. The estimation of aggregative and sedimentation stability of asphaltenes in model system and system with addition of dispersing additive has been given.

  11. Rates of False-Positive Classification Resulting From the Analysis of Additional Embedded Performance Validity Measures.

    PubMed

    Silk-Eglit, Graham M; Stenclik, Jessica H; Miele, Andrea S; Lynch, Julie K; McCaffrey, Robert J

    2015-01-01

    Several studies have documented improvements in the classification accuracy of performance validity tests (PVTs) when they are combined to form aggregated models. Fewer studies have evaluated the impact of aggregating additional PVTs and changing the classification threshold within these models. A recent Monte Carlo simulation demonstrated that to maintain a false-positive rate (FPR) of ≤.10, only 1, 4, 8, 10, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. The current study sought to evaluate these findings with embedded PVTs in a sample of real-life litigants and to highlight a potential danger in analytic flexibility with embedded PVTs. Results demonstrated that to maintain an FPR of ≤.10, only 3, 7, 10, 14, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. Analyzing more than these numbers of PVTs resulted in a dramatic increase in the FPR. In addition, in the most extreme case, flexibility in analyzing and reporting embedded PVTs increased the FPR by 67%. Given these findings, a more objective approach to analyzing and reporting embedded PVTs should be introduced.

  12. Multiscale and Multiphysics Modeling of Additive Manufacturing of Advanced Materials

    NASA Technical Reports Server (NTRS)

    Liou, Frank; Newkirk, Joseph; Fan, Zhiqiang; Sparks, Todd; Chen, Xueyang; Fletcher, Kenneth; Zhang, Jingwei; Zhang, Yunlu; Kumar, Kannan Suresh; Karnati, Sreekar

    2015-01-01

    The objective of this proposed project is to research and develop a prediction tool for advanced additive manufacturing (AAM) processes for advanced materials and develop experimental methods to provide fundamental properties and establish validation data. Aircraft structures and engines demand materials that are stronger, useable at much higher temperatures, provide less acoustic transmission, and enable more aeroelastic tailoring than those currently used. Significant improvements in properties can only be achieved by processing the materials under nonequilibrium conditions, such as AAM processes. AAM processes encompass a class of processes that use a focused heat source to create a melt pool on a substrate. Examples include Electron Beam Freeform Fabrication and Direct Metal Deposition. These types of additive processes enable fabrication of parts directly from CAD drawings. To achieve the desired material properties and geometries of the final structure, assessing the impact of process parameters and predicting optimized conditions with numerical modeling as an effective prediction tool is necessary. The targets for the processing are multiple and at different spatial scales, and the physical phenomena associated occur in multiphysics and multiscale. In this project, the research work has been developed to model AAM processes in a multiscale and multiphysics approach. A macroscale model was developed to investigate the residual stresses and distortion in AAM processes. A sequentially coupled, thermomechanical, finite element model was developed and validated experimentally. The results showed the temperature distribution, residual stress, and deformation within the formed deposits and substrates. A mesoscale model was developed to include heat transfer, phase change with mushy zone, incompressible free surface flow, solute redistribution, and surface tension. Because of excessive computing time needed, a parallel computing approach was also tested. In addition

  13. Multiscale Modeling of Powder Bed-Based Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Markl, Matthias; Körner, Carolin

    2016-07-01

    Powder bed fusion processes are additive manufacturing technologies that are expected to induce the third industrial revolution. Components are built up layer by layer in a powder bed by selectively melting confined areas, according to sliced 3D model data. This technique allows for manufacturing of highly complex geometries hardly machinable with conventional technologies. However, the underlying physical phenomena are sparsely understood and difficult to observe during processing. Therefore, an intensive and expensive trial-and-error principle is applied to produce components with the desired dimensional accuracy, material characteristics, and mechanical properties. This review presents numerical modeling approaches on multiple length scales and timescales to describe different aspects of powder bed fusion processes. In combination with tailored experiments, the numerical results enlarge the process understanding of the underlying physical mechanisms and support the development of suitable process strategies and component topologies.

  14. Sensitivity analysis of geometric errors in additive manufacturing medical models.

    PubMed

    Pinto, Jose Miguel; Arrieta, Cristobal; Andia, Marcelo E; Uribe, Sergio; Ramos-Grez, Jorge; Vargas, Alex; Irarrazaval, Pablo; Tejos, Cristian

    2015-03-01

    Additive manufacturing (AM) models are used in medical applications for surgical planning, prosthesis design and teaching. For these applications, the accuracy of the AM models is essential. Unfortunately, this accuracy is compromised due to errors introduced by each of the building steps: image acquisition, segmentation, triangulation, printing and infiltration. However, the contribution of each step to the final error remains unclear. We performed a sensitivity analysis comparing errors obtained from a reference with those obtained modifying parameters of each building step. Our analysis considered global indexes to evaluate the overall error, and local indexes to show how this error is distributed along the surface of the AM models. Our results show that the standard building process tends to overestimate the AM models, i.e. models are larger than the original structures. They also show that the triangulation resolution and the segmentation threshold are critical factors, and that the errors are concentrated at regions with high curvatures. Errors could be reduced choosing better triangulation and printing resolutions, but there is an important need for modifying some of the standard building processes, particularly the segmentation algorithms.

  15. [Critical of the additive model of the randomized controlled trial].

    PubMed

    Boussageon, Rémy; Gueyffier, François; Bejan-Angoulvant, Theodora; Felden-Dominiak, Géraldine

    2008-01-01

    Randomized, double-blind, placebo-controlled clinical trials are currently the best way to demonstrate the clinical effectiveness of drugs. Its methodology relies on the method of difference (John Stuart Mill), through which the observed difference between two groups (drug vs placebo) can be attributed to the pharmacological effect of the drug being tested. However, this additive model can be questioned in the event of statistical interactions between the pharmacological and the placebo effects. Evidence in different domains has shown that the placebo effect can influence the effect of the active principle. This article evaluates the methodological, clinical and epistemological consequences of this phenomenon. Topics treated include extrapolating results, accounting for heterogeneous results, demonstrating the existence of several factors in the placebo effect, the necessity to take these factors into account for given symptoms or pathologies, as well as the problem of the "specific" effect.

  16. Additive and subtractive scrambling in optional randomized response modeling.

    PubMed

    Hussain, Zawar; Al-Sobhi, Mashail M; Al-Zahrani, Bander

    2014-01-01

    This article considers unbiased estimation of mean, variance and sensitivity level of a sensitive variable via scrambled response modeling. In particular, we focus on estimation of the mean. The idea of using additive and subtractive scrambling has been suggested under a recent scrambled response model. Whether it is estimation of mean, variance or sensitivity level, the proposed scheme of estimation is shown relatively more efficient than that recent model. As far as the estimation of mean is concerned, the proposed estimators perform relatively better than the estimators based on recent additive scrambling models. Relative efficiency comparisons are also made in order to highlight the performance of proposed estimators under suggested scrambling technique.

  17. Additive Functions in Boolean Models of Gene Regulatory Network Modules

    PubMed Central

    Darabos, Christian; Di Cunto, Ferdinando; Tomassini, Marco; Moore, Jason H.; Provero, Paolo; Giacobini, Mario

    2011-01-01

    Gene-on-gene regulations are key components of every living organism. Dynamical abstract models of genetic regulatory networks help explain the genome's evolvability and robustness. These properties can be attributed to the structural topology of the graph formed by genes, as vertices, and regulatory interactions, as edges. Moreover, the actual gene interaction of each gene is believed to play a key role in the stability of the structure. With advances in biology, some effort was deployed to develop update functions in Boolean models that include recent knowledge. We combine real-life gene interaction networks with novel update functions in a Boolean model. We use two sub-networks of biological organisms, the yeast cell-cycle and the mouse embryonic stem cell, as topological support for our system. On these structures, we substitute the original random update functions by a novel threshold-based dynamic function in which the promoting and repressing effect of each interaction is considered. We use a third real-life regulatory network, along with its inferred Boolean update functions to validate the proposed update function. Results of this validation hint to increased biological plausibility of the threshold-based function. To investigate the dynamical behavior of this new model, we visualized the phase transition between order and chaos into the critical regime using Derrida plots. We complement the qualitative nature of Derrida plots with an alternative measure, the criticality distance, that also allows to discriminate between regimes in a quantitative way. Simulation on both real-life genetic regulatory networks show that there exists a set of parameters that allows the systems to operate in the critical region. This new model includes experimentally derived biological information and recent discoveries, which makes it potentially useful to guide experimental research. The update function confers additional realism to the model, while reducing the complexity

  18. Additive functions in boolean models of gene regulatory network modules.

    PubMed

    Darabos, Christian; Di Cunto, Ferdinando; Tomassini, Marco; Moore, Jason H; Provero, Paolo; Giacobini, Mario

    2011-01-01

    Gene-on-gene regulations are key components of every living organism. Dynamical abstract models of genetic regulatory networks help explain the genome's evolvability and robustness. These properties can be attributed to the structural topology of the graph formed by genes, as vertices, and regulatory interactions, as edges. Moreover, the actual gene interaction of each gene is believed to play a key role in the stability of the structure. With advances in biology, some effort was deployed to develop update functions in boolean models that include recent knowledge. We combine real-life gene interaction networks with novel update functions in a boolean model. We use two sub-networks of biological organisms, the yeast cell-cycle and the mouse embryonic stem cell, as topological support for our system. On these structures, we substitute the original random update functions by a novel threshold-based dynamic function in which the promoting and repressing effect of each interaction is considered. We use a third real-life regulatory network, along with its inferred boolean update functions to validate the proposed update function. Results of this validation hint to increased biological plausibility of the threshold-based function. To investigate the dynamical behavior of this new model, we visualized the phase transition between order and chaos into the critical regime using Derrida plots. We complement the qualitative nature of Derrida plots with an alternative measure, the criticality distance, that also allows to discriminate between regimes in a quantitative way. Simulation on both real-life genetic regulatory networks show that there exists a set of parameters that allows the systems to operate in the critical region. This new model includes experimentally derived biological information and recent discoveries, which makes it potentially useful to guide experimental research. The update function confers additional realism to the model, while reducing the complexity

  19. WATEQ3 geochemical model: thermodynamic data for several additional solids

    SciTech Connect

    Krupka, K.M.; Jenne, E.A.

    1982-09-01

    Geochemical models such as WATEQ3 can be used to model the concentrations of water-soluble pollutants that may result from the disposal of nuclear waste and retorted oil shale. However, for a model to competently deal with these water-soluble pollutants, an adequate thermodynamic data base must be provided that includes elements identified as important in modeling these pollutants. To this end, several minerals and related solid phases were identified that were absent from the thermodynamic data base of WATEQ3. In this study, the thermodynamic data for the identified solids were compiled and selected from several published tabulations of thermodynamic data. For these solids, an accepted Gibbs free energy of formation, ..delta..G/sup 0//sub f,298/, was selected for each solid phase based on the recentness of the tabulated data and on considerations of internal consistency with respect to both the published tabulations and the existing data in WATEQ3. For those solids not included in these published tabulations, Gibbs free energies of formation were calculated from published solubility data (e.g., lepidocrocite), or were estimated (e.g., nontronite) using a free-energy summation method described by Mattigod and Sposito (1978). The accepted or estimated free energies were then combined with internally consistent, ancillary thermodynamic data to calculate equilibrium constants for the hydrolysis reactions of these minerals and related solid phases. Including these values in the WATEQ3 data base increased the competency of this geochemical model in applications associated with the disposal of nuclear waste and retorted oil shale. Additional minerals and related solid phases that need to be added to the solubility submodel will be identified as modeling applications continue in these two programs.

  20. Comprehensive European dietary exposure model (CEDEM) for food additives.

    PubMed

    Tennant, David R

    2016-05-01

    European methods for assessing dietary exposures to nutrients, additives and other substances in food are limited by the availability of detailed food consumption data for all member states. A proposed comprehensive European dietary exposure model (CEDEM) applies summary data published by the European Food Safety Authority (EFSA) in a deterministic model based on an algorithm from the EFSA intake method for food additives. The proposed approach can predict estimates of food additive exposure provided in previous EFSA scientific opinions that were based on the full European food consumption database.

  1. Estimation of propensity scores using generalized additive models.

    PubMed

    Woo, Mi-Ja; Reiter, Jerome P; Karr, Alan F

    2008-08-30

    Propensity score matching is often used in observational studies to create treatment and control groups with similar distributions of observed covariates. Typically, propensity scores are estimated using logistic regressions that assume linearity between the logistic link and the predictors. We evaluate the use of generalized additive models (GAMs) for estimating propensity scores. We compare logistic regressions and GAMs in terms of balancing covariates using simulation studies with artificial and genuine data. We find that, when the distributions of covariates in the treatment and control groups overlap sufficiently, using GAMs can improve overall covariate balance, especially for higher-order moments of distributions. When the distributions in the two groups overlap insufficiently, GAM more clearly reveals this fact than logistic regression does. We also demonstrate via simulation that matching with GAMs can result in larger reductions in bias when estimating treatment effects than matching with logistic regression.

  2. Hyperbolic value addition and general models of animal choice.

    PubMed

    Mazur, J E

    2001-01-01

    Three mathematical models of choice--the contextual-choice model (R. Grace, 1994), delay-reduction theory (N. Squires & E. Fantino, 1971), and a new model called the hyperbolic value-added model--were compared in their ability to predict the results from a wide variety of experiments with animal subjects. When supplied with 2 or 3 free parameters, all 3 models made fairly accurate predictions for a large set of experiments that used concurrent-chain procedures. One advantage of the hyperbolic value-added model is that it is derived from a simpler model that makes accurate predictions for many experiments using discrete-trial adjusting-delay procedures. Some results favor the hyperbolic value-added model and delay-reduction theory over the contextual-choice model, but more data are needed from choice situations for which the models make distinctly different predictions.

  3. Electroacoustics modeling of piezoelectric welders for ultrasonic additive manufacturing processes

    NASA Astrophysics Data System (ADS)

    Hehr, Adam; Dapino, Marcelo J.

    2016-04-01

    Ultrasonic additive manufacturing (UAM) is a recent 3D metal printing technology which utilizes ultrasonic vibrations from high power piezoelectric transducers to additively weld similar and dissimilar metal foils. CNC machining is used intermittent of welding to create internal channels, embed temperature sensitive components, sensors, and materials, and for net shaping parts. Structural dynamics of the welder and work piece influence the performance of the welder and part quality. To understand the impact of structural dynamics on UAM, a linear time-invariant model is used to relate system shear force and electric current inputs to the system outputs of welder velocity and voltage. Frequency response measurements are combined with in-situ operating measurements of the welder to identify model parameters and to verify model assumptions. The proposed LTI model can enhance process consistency, performance, and guide the development of improved quality monitoring and control strategies.

  4. The Modern U.S. High School Astronomy Course, Its Status and Makeup II: Additional Results

    ERIC Educational Resources Information Center

    Krumenaker, Larry

    2009-01-01

    A postal survey of high school astronomy teachers strongly confirms many results of an earlier electronic survey. Additional and new results include a measure of the level of inquiry (more structured inquiry and teacher-led) in the classroom as well as data showing that more emphasis is given to traditional topics than to contemporary astronomy…

  5. Anisotropic halo model: implementation and numerical results

    NASA Astrophysics Data System (ADS)

    Sgró, Mario A.; Paz, Dante J.; Merchán, Manuel

    2013-07-01

    In the present work, we extend the classic halo model for the large-scale matter distribution including a triaxial model for the halo profiles and their alignments. In particular, we derive general expressions for the halo-matter cross-correlation function. In addition, by numerical integration, we obtain instances of the cross-correlation function depending on the directions given by halo shape axes. These functions are called anisotropic cross-correlations. With the aim of comparing our theoretical results with the simulations, we compute averaged anisotropic correlations in cones with their symmetry axis along each shape direction of the centre halo. From these comparisons we characterize and quantify the alignment of dark matter haloes on the Λcold dark matter context by means of the presented anisotropic halo model. Since our model requires multidimensional integral computation we implement a Monte Carlo method on GPU hardware which allows us to increase the precision of the results and it improves the performance of the computation.

  6. Validation of transport models using additive flux minimization technique

    NASA Astrophysics Data System (ADS)

    Pankin, A. Y.; Kruger, S. E.; Groebner, R. J.; Hakim, A.; Kritz, A. H.; Rafiq, T.

    2013-10-01

    A new additive flux minimization technique is proposed for carrying out the verification and validation (V&V) of anomalous transport models. In this approach, the plasma profiles are computed in time dependent predictive simulations in which an additional effective diffusivity is varied. The goal is to obtain an optimal match between the computed and experimental profile. This new technique has several advantages over traditional V&V methods for transport models in tokamaks and takes advantage of uncertainty quantification methods developed by the applied math community. As a demonstration of its efficiency, the technique is applied to the hypothesis that the paleoclassical density transport dominates in the plasma edge region in DIII-D tokamak discharges. A simplified version of the paleoclassical model that utilizes the Spitzer resistivity for the parallel neoclassical resistivity and neglects the trapped particle effects is tested in this paper. It is shown that a contribution to density transport, in addition to the paleoclassical density transport, is needed in order to describe the experimental profiles. It is found that more additional diffusivity is needed at the top of the H-mode pedestal, and almost no additional diffusivity is needed at the pedestal bottom. The implementation of this V&V technique uses the FACETS::Core transport solver and the DAKOTA toolkit for design optimization and uncertainty quantification. The FACETS::Core solver is used for advancing the plasma density profiles. The DAKOTA toolkit is used for the optimization of plasma profiles and the computation of the additional diffusivity that is required for the predicted density profile to match the experimental profile.

  7. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Pilot-Scale Test Results

    SciTech Connect

    Gary M. Blythe

    2006-03-01

    Texas Lignite Flue Gas; Task 3 - Full-scale FGD Additive Testing in High Sulfur Eastern Bituminous Flue Gas; Task 4 - Pilot Wet Scrubber Additive Tests at Yates; and Task 5 - Full-scale Additive Tests at Plant Yates. This topical report presents the results from the Task 2 and Task 4 pilot-scale additive tests. The Task 3 and Task 5 full-scale additive tests will be conducted later in calendar year 2006.

  8. Additional results on space environmental effects on polymer matrix composites: Experiment A0180

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.

    1992-01-01

    Additional experimental results on the atomic oxygen erosion of boron, Kevlar, and graphite fiber reinforced epoxy matrix composites are presented. Damage of composite laminates due to micrometeoroid/debris impacts is also examined with particular emphasis on the relationship between damage area and actual hole size due to particle penetration. Special attention is given to one micrometeoroid impact on an aluminum base plate which resulted in ejecta visible on an adjoining vertical flange structure.

  9. Emulating AOGCM results using simple climate models

    NASA Astrophysics Data System (ADS)

    Olivié, Dirk; Stuber, Nicola

    2010-12-01

    Three simple climate models (SCMs) are calibrated using simulations from atmosphere ocean general circulation models (AOGCMs). In addition to using two conventional SCMs, results from a third simpler model developed specifically for this study are obtained. An easy to implement and comprehensive iterative procedure is applied that optimises the SCM emulation of global-mean surface temperature and total ocean heat content, and, if available in the SCM, of surface temperature over land, over the ocean and in both hemispheres, and of the global-mean ocean temperature profile. The method gives best-fit estimates as well as uncertainty intervals for the different SCM parameters. For the calibration, AOGCM simulations with two different types of forcing scenarios are used: pulse forcing simulations performed with 2 AOGCMs and gradually changing forcing simulations from 15 AOGCMs obtained within the framework of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The method is found to work well. For all possible combinations of SCMs and AOGCMs the emulation of AOGCM results could be improved. The obtained SCM parameters depend both on the AOGCM data and the type of forcing scenario. SCMs with a poor representation of the atmosphere thermal inertia are better able to emulate AOGCM results from gradually changing forcing than from pulse forcing simulations. Correct simultaneous emulation of both atmospheric temperatures and the ocean temperature profile by the SCMs strongly depends on the representation of the temperature gradient between the atmosphere and the mixed layer. Introducing climate sensitivities that are dependent on the forcing mechanism in the SCMs allows the emulation of AOGCM responses to carbon dioxide and solar insolation forcings equally well. Also, some SCM parameters are found to be very insensitive to the fitting, and the reduction of their uncertainty through the fitting procedure is only marginal, while other parameters

  10. Transferability of regional permafrost disturbance susceptibility modelling using generalized linear and generalized additive models

    NASA Astrophysics Data System (ADS)

    Rudy, Ashley C. A.; Lamoureux, Scott F.; Treitz, Paul; van Ewijk, Karin Y.

    2016-07-01

    To effectively assess and mitigate risk of permafrost disturbance, disturbance-prone areas can be predicted through the application of susceptibility models. In this study we developed regional susceptibility models for permafrost disturbances using a field disturbance inventory to test the transferability of the model to a broader region in the Canadian High Arctic. Resulting maps of susceptibility were then used to explore the effect of terrain variables on the occurrence of disturbances within this region. To account for a large range of landscape characteristics, the model was calibrated using two locations: Sabine Peninsula, Melville Island, NU, and Fosheim Peninsula, Ellesmere Island, NU. Spatial patterns of disturbance were predicted with a generalized linear model (GLM) and generalized additive model (GAM), each calibrated using disturbed and randomized undisturbed locations from both locations and GIS-derived terrain predictor variables including slope, potential incoming solar radiation, wetness index, topographic position index, elevation, and distance to water. Each model was validated for the Sabine and Fosheim Peninsulas using independent data sets while the transferability of the model to an independent site was assessed at Cape Bounty, Melville Island, NU. The regional GLM and GAM validated well for both calibration sites (Sabine and Fosheim) with the area under the receiver operating curves (AUROC) > 0.79. Both models were applied directly to Cape Bounty without calibration and validated equally with AUROC's of 0.76; however, each model predicted disturbed and undisturbed samples differently. Additionally, the sensitivity of the transferred model was assessed using data sets with different sample sizes. Results indicated that models based on larger sample sizes transferred more consistently and captured the variability within the terrain attributes in the respective study areas. Terrain attributes associated with the initiation of disturbances were

  11. Addition Table of Colours: Additive and Subtractive Mixtures Described Using a Single Reasoning Model

    ERIC Educational Resources Information Center

    Mota, A. R.; Lopes dos Santos, J. M. B.

    2014-01-01

    Students' misconceptions concerning colour phenomena and the apparent complexity of the underlying concepts--due to the different domains of knowledge involved--make its teaching very difficult. We have developed and tested a teaching device, the addition table of colours (ATC), that encompasses additive and subtractive mixtures in a single…

  12. Additive Manufacturing of Medical Models--Applications in Rhinology.

    PubMed

    Raos, Pero; Klapan, Ivica; Galeta, Tomislav

    2015-09-01

    In the paper we are introducing guidelines and suggestions for use of 3D image processing SW in head pathology diagnostic and procedures for obtaining physical medical model by additive manufacturing/rapid prototyping techniques, bearing in mind the improvement of surgery performance, its maximum security and faster postoperative recovery of patients. This approach has been verified in two case reports. In the treatment we used intelligent classifier-schemes for abnormal patterns using computer-based system for 3D-virtual and endoscopic assistance in rhinology, with appropriate visualization of anatomy and pathology within the nose, paranasal sinuses, and scull base area.

  13. Revisiting Runoff Model Calibration: Airborne Snow Observatory Results Allow Improved Modeling Results

    NASA Astrophysics Data System (ADS)

    McGurk, B. J.; Painter, T. H.

    2014-12-01

    Deterministic snow accumulation and ablation simulation models are widely used by runoff managers throughout the world to predict runoff quantities and timing. Model fitting is typically based on matching modeled runoff volumes and timing with observed flow time series at a few points in the basin. In recent decades, sparse networks of point measurements of the mountain snowpacks have been available to compare with modeled snowpack, but the comparability of results from a snow sensor or course to model polygons of 5 to 50 sq. km is suspect. However, snowpack extent, depth, and derived snow water equivalent have been produced by the NASA/JPL Airborne Snow Observatory (ASO) mission for spring of 20013 and 2014 in the Tuolumne River basin above Hetch Hetchy Reservoir. These high-resolution snowpack data have exposed the weakness in a model calibration based on runoff alone. The U.S. Geological Survey's Precipitation Runoff Modeling System (PRMS) calibration that was based on 30-years of inflow to Hetch Hetchy produces reasonable inflow results, but modeled spatial snowpack location and water quantity diverged significantly from the weekly measurements made by ASO during the two ablation seasons. The reason is that the PRMS model has many flow paths, storages, and water transfer equations, and a calibrated outflow time series can be right for many wrong reasons. The addition of a detailed knowledge of snow extent and water content constrains the model so that it is a better representation of the actual watershed hydrology. The mechanics of recalibrating PRMS to the ASO measurements will be described, and comparisons in observed versus modeled flow for both a small subbasin and the entire Hetch Hetchy basin will be shown. The recalibrated model provided a bitter fit to the snowmelt recession, a key factor for water managers as they balance declining inflows with demand for power generation and ecosystem releases during the final months of snow melt runoff.

  14. Additive Manufacturing of Anatomical Models from Computed Tomography Scan Data.

    PubMed

    Gür, Y

    2014-12-01

    The purpose of the study presented here was to investigate the manufacturability of human anatomical models from Computed Tomography (CT) scan data via a 3D desktop printer which uses fused deposition modelling (FDM) technology. First, Digital Imaging and Communications in Medicine (DICOM) CT scan data were converted to 3D Standard Triangle Language (STL) format by using In Vaselius digital imaging program. Once this STL file is obtained, a 3D physical version of the anatomical model can be fabricated by a desktop 3D FDM printer. As a case study, a patient's skull CT scan data was considered, and a tangible version of the skull was manufactured by a 3D FDM desktop printer. During the 3D printing process, the skull was built using acrylonitrile-butadiene-styrene (ABS) co-polymer plastic. The printed model showed that the 3D FDM printing technology is able to fabricate anatomical models with high accuracy. As a result, the skull model can be used for preoperative surgical planning, medical training activities, implant design and simulation to show the potential of the FDM technology in medical field. It will also improve communication between medical stuff and patients. Current result indicates that a 3D desktop printer which uses FDM technology can be used to obtain accurate anatomical models.

  15. Effect of product form upon fatigue-crack growth behavior in Alloy 718: additional results

    SciTech Connect

    James, L A

    1980-08-01

    A previous study had characterized the fatigue-crack growth behavior of four wrought product forms (sheet, plate, bar and forging) from a single heat of Alloy 718 and concluded that there were no consistent trends in the crack growth rate results that could be attributed to product form variability. The present study adds one additional product form (gas-tungsten-arc weldments) from the same heat, and compares the behavior to that exhibited by the wrought product forms. Two different precipitation heat-treatments were employed at each of five test temperatures (24, 316, 427, 538, and 649{sup 0}C).

  16. The effect of product form upon fatigue-crack growth behavior in Alloy 718: Additional results

    SciTech Connect

    James, L.A.

    1980-08-01

    A previous study had characterized the fatigue-crack growth behavior of four wrought product forms (sheet, plate, bar and forging) from a single heat of Alloy 718 and concluded that there were no consistent trends in the crack growth rate results that could be attributed to product form variability. The present study adds one additional product form (gas-tungsten-arc weldments) from the same heat, and compares the behavior to that exhibited by the wrought product forms. Two different precipitation heat-treatments were employed at each of five test temperatures. 11 refs., 5 figs., 3 tabs.

  17. Results of investigations of Ethernet network fault-tolerance parameters by using additional analysis subsystem

    NASA Astrophysics Data System (ADS)

    Sultanov, Albert H.; Gayfulin, Renat R.; Vinogradova, Irina L.

    2008-04-01

    Fiber optic telecommunication systems with duplex data transmitting over single fiber require reflection minimization. Moreover reflections may be so high that causes system deactivating by misoperation of conventional alarm, and system can not automatically adjudge the collision, so operator manual control is required. In this paper we proposed technical solution of mentioned problem based on additional analysis subsystem, realized on the installed Ufa-city fiber optic CTV system "Crystal". Experience of it's maintenance and results of investigations of the fault tolerance parameters are represented

  18. Response to selection in finite locus models with non-additive effects.

    PubMed

    Esfandyari, Hadi; Henryon, Mark; Berg, Peer; Thomasen, Jorn Rind; Bijma, Piter; Sørensen, Anders Christian

    2017-01-12

    Under the finite-locus model in the absence of mutation, the additive genetic variation is expected to decrease when directional selection is acting on a population, according to quantitative-genetic theory. However, some theoretical studies of selection suggest that the level of additive variance can be sustained or even increased when non-additive genetic effects are present. We tested the hypothesis that finite-locus models with both additive and non-additive genetic effects maintain more additive genetic variance (V_A) and realize larger medium-to-long term genetic gains than models with only additive effects when the trait under selection is subject to truncation selection. Four genetic models that included additive, dominance, and additive-by-additive epistatic effects were simulated. The simulated genome for individuals consisted of 25 chromosomes, each with a length of 1M. One hundred bi-allelic QTL, four on each chromosome, were considered. In each generation, 100 sires and 100 dams were mated, producing five progeny per mating. The population was selected for a single trait (h(2)=0.1) for 100 discrete generations with selection on phenotype or BLUP-EBV. V_A decreased with directional truncation selection even in presence of non-additive genetic effects. Non-additive effects influenced long-term response to selection and among genetic models additive gene action had highest response to selection. In addition, in all genetic models, BLUP-EBV resulted in a greater fixation of favourable and unfavourable alleles and higher response than phenotypic selection. In conclusion, for the schemes we simulated, the presence of non-additive genetic effects had little effect in changes of additive variance and V_A decreased by directional selection.

  19. Key Results of Interaction Models with Centering

    ERIC Educational Resources Information Center

    Afshartous, David; Preston, Richard A.

    2011-01-01

    We consider the effect on estimation of simultaneous variable centering and interaction effects in linear regression. We technically define, review, and amplify many of the statistical issues for interaction models with centering in order to create a useful and compact reference for teachers, students, and applied researchers. In addition, we…

  20. Addition of a Hydrological Cycle to the EPIC Jupiter Model

    NASA Astrophysics Data System (ADS)

    Dowling, T. E.; Palotai, C. J.

    2002-09-01

    We present a progress report on the development of the EPIC atmospheric model to include clouds, moist convection, and precipitation. Two major goals are: i) to study the influence that convective water clouds have on Jupiter's jets and vortices, such as those to the northwest of the Great Red Spot, and ii) to predict ammonia-cloud evolution for direct comparison to visual images (instead of relying on surrogates for clouds like potential vorticity). Data structures in the model are now set up to handle the vapor, liquid, and solid phases of the most common chemical species in planetary atmospheres. We have adapted the Prather conservation of second-order moments advection scheme to the model, which yields high accuracy for dealing with cloud edges. In collaboration with computer scientists H. Dietz and T. Mattox at the U. Kentucky, we have built a dedicated 40-node parallel computer that achieves 34 Gflops (double precision) at 74 cents per Mflop, and have updated the EPIC-model code to use cache-aware memory layouts and other modern optimizations. The latest test-case results of cloud evolution in the model will be presented. This research is funded by NASA's Planetary Atmospheres and EPSCoR programs.

  1. Technical Work Plan for: Additional Multoscale Thermohydrologic Modeling

    SciTech Connect

    B. Kirstein

    2006-08-24

    The primary objective of Revision 04 of the MSTHM report is to provide TSPA with revised repository-wide MSTHM analyses that incorporate updated percolation flux distributions, revised hydrologic properties, updated IEDs, and information pertaining to the emplacement of transport, aging, and disposal (TAD) canisters. The updated design information is primarily related to the incorporation of TAD canisters, but also includes updates related to superseded IEDs describing emplacement drift cross-sectional geometry and layout. The intended use of the results of Revision 04 of the MSTHM report, as described in this TWP, is to predict the evolution of TH conditions (temperature, relative humidity, liquid-phase saturation, and liquid-phase flux) at specified locations within emplacement drifts and in the adjoining near-field host rock along all emplacement drifts throughout the repository. This information directly supports the TSPA for the nominal and seismic scenarios. The revised repository-wide analyses are required to incorporate updated parameters and design information and to extend those analyses out to 1,000,000 years. Note that the previous MSTHM analyses reported in Revision 03 of Multiscale Thermohydrologic Model (BSC 2005 [DIRS 173944]) only extend out to 20,000 years. The updated parameters are the percolation flux distributions, including incorporation of post-10,000-year distributions, and updated calibrated hydrologic property values for the host-rock units. The applied calibrated hydrologic properties will be an updated version of those available in Calibrated Properties Model (BSC 2004 [DIRS 169857]). These updated properties will be documented in an Appendix of Revision 03 of UZ Flow Models and Submodels (BSC 2004 [DIRS 169861]). The updated calibrated properties are applied because they represent the latest available information. The reasonableness of applying the updated calibrated' properties to the prediction of near-fieldin-drift TH conditions

  2. Bragg's rule of stopping power additivity: a compilation and summary of results

    SciTech Connect

    Thwaites, D.I.

    1983-09-01

    Stopping power additivity, as expressed by Bragg's rule, is an important concept in many practical situations involving charged particles. Its validity has been investigated in a large number of studies and the wide range of data is confusing and at times conflicting. No previous comprehensive survey of the data has been undertaken. Thus a compilation is attempted here of a hundred or so papers which have included tests of Bragg's rule. Their main results are indicated and a summary is given of the effects of chemical binding and phase on the stopping power of heavy charged particles. Such effects are confirmed on the evidence available. Chemical binding effects become more significant for materials containing low-Z constituents and as energy falls into and through the transition region. Deviations of up to 50% have been observed in atomic stopping cross sections extracted from measurements on hydrocarbons. There is still some conflicting evidence appearing on phase effects. However, in general a broad consensus is emerging indicating significant differences in H/sub 2/O and organic and similar materials. Stopping cross sections in the vapor phase are greater by up to approx. 5 or 10% at energies around those of the stopping power maximum for protons and He ions. The effects decrease as energy increases.

  3. New results on standard solar models

    NASA Astrophysics Data System (ADS)

    Serenelli, Aldo M.

    2010-07-01

    We describe the current status of solar modeling and focus on the problems originating with the introduction of solar abundance determinations with low CNO abundance values. We use models computed with solar abundance compilations obtained during the last decade, including the newest published abundances by Asplund and collaborators. The results presented here focus on both helioseismic properties and models as well as neutrino flux predictions. We also discuss changes in radiative opacities to restore agreement between helioseismology, solar models, and solar abundances and show the effect of such modifications on solar neutrino fluxes.

  4. Engineering Glass Passivation Layers -Model Results

    SciTech Connect

    Skorski, Daniel C.; Ryan, Joseph V.; Strachan, Denis M.; Lepry, William C.

    2011-08-08

    The immobilization of radioactive waste into glass waste forms is a baseline process of nuclear waste management not only in the United States, but worldwide. The rate of radionuclide release from these glasses is a critical measure of the quality of the waste form. Over long-term tests and using extrapolations of ancient analogues, it has been shown that well designed glasses exhibit a dissolution rate that quickly decreases to a slow residual rate for the lifetime of the glass. The mechanistic cause of this decreased corrosion rate is a subject of debate, with one of the major theories suggesting that the decrease is caused by the formation of corrosion products in such a manner as to present a diffusion barrier on the surface of the glass. Although there is much evidence of this type of mechanism, there has been no attempt to engineer the effect to maximize the passivating qualities of the corrosion products. This study represents the first attempt to engineer the creation of passivating phases on the surface of glasses. Our approach utilizes interactions between the dissolving glass and elements from the disposal environment to create impermeable capping layers. By drawing from other corrosion studies in areas where passivation layers have been successfully engineered to protect the bulk material, we present here a report on mineral phases that are likely have a morphological tendency to encrust the surface of the glass. Our modeling has focused on using the AFCI glass system in a carbonate, sulfate, and phosphate rich environment. We evaluate the minerals predicted to form to determine the likelihood of the formation of a protective layer on the surface of the glass. We have also modeled individual ions in solutions vs. pH and the addition of aluminum and silicon. These results allow us to understand the pH and ion concentration dependence of mineral formation. We have determined that iron minerals are likely to form a complete incrustation layer and we plan

  5. Percolation model with an additional source of disorder

    NASA Astrophysics Data System (ADS)

    Kundu, Sumanta; Manna, S. S.

    2016-06-01

    The ranges of transmission of the mobiles in a mobile ad hoc network are not uniform in reality. They are affected by the temperature fluctuation in air, obstruction due to the solid objects, even the humidity difference in the environment, etc. How the varying range of transmission of the individual active elements affects the global connectivity in the network may be an important practical question to ask. Here a model of percolation phenomena, with an additional source of disorder, is introduced for a theoretical understanding of this problem. As in ordinary percolation, sites of a square lattice are occupied randomly with probability p . Each occupied site is then assigned a circular disk of random value R for its radius. A bond is defined to be occupied if and only if the radii R1 and R2 of the disks centered at the ends satisfy a certain predefined condition. In a very general formulation, one divides the R1-R2 plane into two regions by an arbitrary closed curve. One defines a point within one region as representing an occupied bond; otherwise it is a vacant bond. The study of three different rules under this general formulation indicates that the percolation threshold always varies continuously. This threshold has two limiting values, one is pc(sq) , the percolation threshold for the ordinary site percolation on the square lattice, and the other is unity. The approach of the percolation threshold to its limiting values are characterized by two exponents. In a special case, all lattice sites are occupied by disks of random radii R ∈{0 ,R0} and a percolation transition is observed with R0 as the control variable, similar to the site occupation probability.

  6. Effects of additional food in a delayed predator-prey model.

    PubMed

    Sahoo, Banshidhar; Poria, Swarup

    2015-03-01

    We examine the effects of supplying additional food to predator in a gestation delay induced predator-prey system with habitat complexity. Additional food works in favor of predator growth in our model. Presence of additional food reduces the predatory attack rate to prey in the model. Supplying additional food we can control predator population. Taking time delay as bifurcation parameter the stability of the coexisting equilibrium point is analyzed. Hopf bifurcation analysis is done with respect to time delay in presence of additional food. The direction of Hopf bifurcations and the stability of bifurcated periodic solutions are determined by applying the normal form theory and the center manifold theorem. The qualitative dynamical behavior of the model is simulated using experimental parameter values. It is observed that fluctuations of the population size can be controlled either by supplying additional food suitably or by increasing the degree of habitat complexity. It is pointed out that Hopf bifurcation occurs in the system when the delay crosses some critical value. This critical value of delay strongly depends on quality and quantity of supplied additional food. Therefore, the variation of predator population significantly effects the dynamics of the model. Model results are compared with experimental results and biological implications of the analytical findings are discussed in the conclusion section.

  7. Software reliability: Additional investigations into modeling with replicated experiments

    NASA Technical Reports Server (NTRS)

    Nagel, P. M.; Schotz, F. M.; Skirvan, J. A.

    1984-01-01

    The effects of programmer experience level, different program usage distributions, and programming languages are explored. All these factors affect performance, and some tentative relational hypotheses are presented. An analytic framework for replicated and non-replicated (traditional) software experiments is presented. A method of obtaining an upper bound on the error rate of the next error is proposed. The method was validated empirically by comparing forecasts with actual data. In all 14 cases the bound exceeded the observed parameter, albeit somewhat conservatively. Two other forecasting methods are proposed and compared to observed results. Although demonstrated relative to this framework that stages are neither independent nor exponentially distributed, empirical estimates show that the exponential assumption is nearly valid for all but the extreme tails of the distribution. Except for the dependence in the stage probabilities, Cox's model approximates to a degree what is being observed.

  8. EPA Update on Gold King Mine Response: Additional Data Results and Public Records

    EPA Pesticide Factsheets

    WASHINGTON - Today the U.S. Environmental Protection Agency (EPA) released an update on water quality and sediment data for the Animas and San Juan Rivers, as well as additional public records on the Gold King Mine response.

  9. Atom-probe tomography of tribological boundary films resulting from boron-based oil additives

    SciTech Connect

    Kim, Yoon-Jun; Baik, Sung-Il; Bertolucci-Coelho, Leonardo; Mazzaferro, Lucca; Ramirez, Giovanni; Erdemir, Ali; Seidman, D K

    2016-01-15

    Correlative characterization using atom-probe tomography (APT) and transmission electron microscopy (TEM) was performed on a tribofilm formed during sliding frictional testing with a fully formulated engine oil, which also contains a boron-based additive. The tribofilm formed is ~15 nm thick and consists of oxides of iron and compounds of B, Ca, P, and S, which are present in the additive. This study provides strong evidence for boron being embedded in the tribofilm, which effectively reduces friction and wear losses.

  10. Product versus additive threshold models for analysis of reproduction outcomes in animal genetics.

    PubMed

    David, I; Bodin, L; Gianola, D; Legarra, A; Manfredi, E; Robert-Granié, C

    2009-08-01

    The phenotypic observation of some reproduction traits (e.g., insemination success, interval from lambing to insemination) is the result of environmental and genetic factors acting on 2 individuals: the male and female involved in a mating couple. In animal genetics, the main approach (called additive model) proposed for studying such traits assumes that the phenotype is linked to a purely additive combination, either on the observed scale for continuous traits or on some underlying scale for discrete traits, of environmental and genetic effects affecting the 2 individuals. Statistical models proposed for studying human fecundability generally consider reproduction outcomes as the product of hypothetical unobservable variables. Taking inspiration from these works, we propose a model (product threshold model) for studying a binary reproduction trait that supposes that the observed phenotype is the product of 2 unobserved phenotypes, 1 for each individual. We developed a Gibbs sampling algorithm for fitting a Bayesian product threshold model including additive genetic effects and showed by simulation that it is feasible and that it provides good estimates of the parameters. We showed that fitting an additive threshold model to data that are simulated under a product threshold model provides biased estimates, especially for individuals with high breeding values. A main advantage of the product threshold model is that, in contrast to the additive model, it provides distinct estimates of fixed effects affecting each of the 2 unobserved phenotypes.

  11. Plant interspecific differences in arbuscular mycorrhizal colonization as a result of soil carbon addition.

    PubMed

    Eschen, René; Müller-Schärer, Heinz; Schaffner, Urs

    2013-01-01

    Soil nutrient availability and colonization by arbuscular mycorrhizal fungi are important and potentially interacting factors shaping vegetation composition and succession. We investigated the effect of carbon (C) addition, aimed at reducing soil nutrient availability, on arbuscular mycorrhizal colonization. Seedlings of 27 plant species with different sets of life-history traits (functional group affiliation, life history strategy and nitrophilic status) were grown in pots filled with soil from a nutrient-rich set-aside field and amended with different amounts of C. Mycorrhizal colonization was progressively reduced along the gradient of increasing C addition in 17 out of 27 species, but not in the remaining species. Grasses had lower colonization levels than forbs and legumes and the decline in AM fungal colonization was more pronounced in legumes than in other forbs and grasses. Mycorrhizal colonization did not differ between annual and perennial species, but decreased more rapidly along the gradient of increasing C addition in plants with high Ellenberg N values than in plants with low Ellenberg N values. Soil C addition not only limits plant growth through a reduction in available nutrients, but also reduces mycorrhizal colonization of plant roots. The effect of C addition on mycorrhizal colonization varies among plant functional groups, with legumes experiencing an overproportional reduction in AM fungal colonization along the gradient of increasing C addition. We therefore propose that for a better understanding of vegetation succession on set-aside fields one may consider the interrelationship between plant growth, soil nutrient availability and mycorrhizal colonization of plant roots.

  12. TANK 40 FINAL SB5 CHEMICAL CHARACTERIZATION RESULTS PRIOR TO NP ADDITION

    SciTech Connect

    Bannochie, C.; Click, D.

    2010-01-06

    A sample of Sludge Batch 5 (SB5) was pulled from Tank 40 in order to obtain radionuclide inventory analyses necessary for compliance with the Waste Acceptance Product Specifications (WAPS). This sample was also analyzed for chemical composition including noble metals. Prior to radionuclide inventory analyses, a final sample of the H-canyon Np stream will be added to bound the Np addition anticipated for Tank 40. These analyses along with the WAPS radionuclide analyses will help define the composition of the sludge in Tank 40 that is currently being fed to DWPF as SB5. At the Savannah River National Laboratory (SRNL) the 3-L Tank 40 SB5 sample was transferred from the shipping container into a 4-L high density polyethylene vessel and solids allowed to settle overnight. Supernate was then siphoned off and circulated through the shipping container to complete the transfer of the sample. Following thorough mixing of the 3-L sample, a 239 g sub-sample was removed. This sub-sample was then utilized for all subsequent analytical samples. Eight separate aliquots of the slurry were digested, four with HNO{sub 3}/HCl (aqua regia) in sealed Teflon{reg_sign} vessels and four in Na{sub 2}O{sub 2} (alkali or peroxide fusion) using Zr crucibles. Due to the use of Zr crucibles and Na in the peroxide fusions, Na and Zr cannot be determined from this preparation. Additionally, other alkali metals, such as Li and K that may be contaminants in the Na{sub 2}O{sub 2} are not determined from this preparation. Three Analytical Reference Glass - 14 (ARG-1) standards were digested along with a blank for each preparation. The ARG-1 glass allows for an assessment of the completeness of each digestion. Each aqua regia digestion and blank was diluted to 1:100 mL with deionized water and submitted to Analytical Development (AD) for inductively coupled plasma - atomic emission spectroscopy (ICPAES) analysis, inductively coupled plasma - mass spectrometry (ICP-MS) analysis of masses 81-209 and 230

  13. Performance results of HESP physical model

    NASA Astrophysics Data System (ADS)

    Chanumolu, Anantha; Thirupathi, Sivarani; Jones, Damien; Giridhar, Sunetra; Grobler, Deon; Jakobsson, Robert

    2017-02-01

    As a continuation to the published work on model based calibration technique with HESP(Hanle Echelle Spectrograph) as a case study, in this paper we present the performance results of the technique. We also describe how the open parameters were chosen in the model for optimization, the glass data accuracy and handling the discrepancies. It is observed through simulations that the discrepancies in glass data can be identified but not quantifiable. So having an accurate glass data is important which is possible to obtain from the glass manufacturers. The model's performance in various aspects is presented using the ThAr calibration frames from HESP during its pre-shipment tests. Accuracy of model predictions and its wave length calibration comparison with conventional empirical fitting, the behaviour of open parameters in optimization, model's ability to track instrumental drifts in the spectrum and the double fibres performance were discussed. It is observed that the optimized model is able to predict to a high accuracy the drifts in the spectrum from environmental fluctuations. It is also observed that the pattern in the spectral drifts across the 2D spectrum which vary from image to image is predictable with the optimized model. We will also discuss the possible science cases where the model can contribute.

  14. Addition of prothrombin to plasma can result in a paradoxical increase in activated partial thromboplastin time.

    PubMed

    Hansson, Kenny M; Björkqvist, Jenny; Deinum, Johanna

    2014-12-01

    In the activated partial thromboplastin time (APTT) assay, a variety of nonphysiological reagents is used to induce contact activation. The sensitivity of the APTT response for different thrombin inhibitors has previously been found to be dependent on the used reagent. Recently, infusion of prothrombin (FII) has been used in in-vivo coagulopathy models and its effect has been analyzed in different assays. Therefore, we investigated whether the FII plasma concentration might affect APTT using different commercial reagents, applying both turbidimetry and viscometry. We compared both plasma-derived human FII (pd-hFII) and recombinant human FII (r-hFII). Similar results were found for pd-hFII and r-hFII with different APTT reagents. As expected, no effect on APTT was found by increasing the plasma concentration of FII using APTT reagents consisting of ellagic acid (Actin FS or Actin). Although with Pathromtin SL, consisting of SiO2, only a slight increase was found, with most other commercial APTT reagents, consisting of SiO2 or kaolin, APTT dose-dependently increased by increasing concentration of FII. Therefore, both Pathromtin SL and Actin FS were used to compare r-hFII and pd-hFII by determining the KM at 37C using FII-depleted plasma, providing values of 6 ± 0.3 nmol/l FII for both. Thus, at normal plasma concentrations of FII, the maximal initial thrombin generation rate should be reached and no effect on the coagulation time is expected at higher FII concentrations. To completely avoid the paradoxical effect in the APTT assay at FII concentrations higher than normal, Actin or Actin FS is the preferable reagent.

  15. Performance on Addition and Subtraction Problems: Results from Individual Interviews - Sandy Bay Study.

    ERIC Educational Resources Information Center

    Romberg, Thomas A.; And Others

    The purpose of this study was to relate children's cognitive processing capabilities and their grade level to their performance and to the strategies they used when working addition and subtraction problems. From two sets of data which assessed memory capacity and cognitive processing capacities, six groups of children with different cognitive…

  16. 21 CFR 570.14 - Indirect food additives resulting from packaging materials for animal feed and pet food.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Indirect food additives resulting from packaging..., DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES General Provisions § 570.14 Indirect food additives resulting from packaging materials for animal feed...

  17. 21 CFR 570.14 - Indirect food additives resulting from packaging materials for animal feed and pet food.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Indirect food additives resulting from packaging..., DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES General Provisions § 570.14 Indirect food additives resulting from packaging materials for animal feed...

  18. 21 CFR 570.13 - Indirect food additives resulting from packaging materials prior sanctioned for animal feed and...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Indirect food additives resulting from packaging materials prior sanctioned for animal feed and pet food. 570.13 Section 570.13 Food and Drugs FOOD AND DRUG... FOOD ADDITIVES General Provisions § 570.13 Indirect food additives resulting from packaging...

  19. 21 CFR 570.14 - Indirect food additives resulting from packaging materials for animal feed and pet food.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Indirect food additives resulting from packaging..., DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES General Provisions § 570.14 Indirect food additives resulting from packaging materials for animal feed...

  20. 21 CFR 570.13 - Indirect food additives resulting from packaging materials prior sanctioned for animal feed and...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Indirect food additives resulting from packaging materials prior sanctioned for animal feed and pet food. 570.13 Section 570.13 Food and Drugs FOOD AND DRUG... FOOD ADDITIVES General Provisions § 570.13 Indirect food additives resulting from packaging...

  1. 21 CFR 570.13 - Indirect food additives resulting from packaging materials prior sanctioned for animal feed and...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Indirect food additives resulting from packaging materials prior sanctioned for animal feed and pet food. 570.13 Section 570.13 Food and Drugs FOOD AND DRUG... FOOD ADDITIVES General Provisions § 570.13 Indirect food additives resulting from packaging...

  2. Preliminary result on the enhancement of Ufer electrodes using recycle additives materials

    NASA Astrophysics Data System (ADS)

    Zulkifli, Muhammad Haziq Aniq Bin; Ahmad, Hussein Bin

    2016-11-01

    Ground building pillars is to be used as ground rod. The pillars are design, fabricated, and formulated with new ground fillers. The additives will be used from recycle waste materials mainly from the palm oil plant process. Micro scale building pillars will be fabricated and install in the test ground at all of the location. Earth tester meter are used to measure and collect the data of the soil resistivity when the research is conducted. In collecting these data, 3-terminal methods are used to carry the measurements. This experiment will be conducted for 30 weeks and regular measurements at the test ground copper grids will be conducted to measure the ground electrode resistance. The study will mainly base on IEC 62503-3. The used of reinforcing rods and mixture of recycle additives could produce a better grounding system that are suitable and can be used in all kind of soil condition and large industries.

  3. Using Generalized Additive Models to Analyze Single-Case Designs

    ERIC Educational Resources Information Center

    Shadish, William; Sullivan, Kristynn

    2013-01-01

    Many analyses for single-case designs (SCDs)--including nearly all the effect size indicators-- currently assume no trend in the data. Regression and multilevel models allow for trend, but usually test only linear trend and have no principled way of knowing if higher order trends should be represented in the model. This paper shows how Generalized…

  4. Spinel dissolution via addition of glass forming chemicals. Results of preliminary experiments

    SciTech Connect

    Fox, K. M.; Johnson, F. C.

    2015-11-01

    Increased loading of high level waste in glass can lead to crystallization within the glass. Some crystalline species, such as spinel, have no practical impact on the chemical durability of the glass, and therefore may be acceptable from both a processing and a product performance standpoint. In order to operate a melter with a controlled amount of crystallization, options must be developed for remediating an unacceptable accumulation of crystals. This report describes preliminary experiments designed to evaluate the ability to dissolve spinel crystals in simulated waste glass melts via the addition of glass forming chemicals (GFCs).

  5. An original traffic additional emission model and numerical simulation on a signalized road

    NASA Astrophysics Data System (ADS)

    Zhu, Wen-Xing; Zhang, Jing-Yu

    2017-02-01

    Based on VSP (Vehicle Specific Power) model traffic real emissions were theoretically classified into two parts: basic emission and additional emission. An original additional emission model was presented to calculate the vehicle's emission due to the signal control effects. Car-following model was developed and used to describe the traffic behavior including cruising, accelerating, decelerating and idling at a signalized intersection. Simulations were conducted under two situations: single intersection and two adjacent intersections with their respective control policy. Results are in good agreement with the theoretical analysis. It is also proved that additional emission model may be used to design the signal control policy in our modern traffic system to solve the serious environmental problems.

  6. Non-additive model for specific heat of electrons

    NASA Astrophysics Data System (ADS)

    Anselmo, D. H. A. L.; Vasconcelos, M. S.; Silva, R.; Mello, V. D.

    2016-10-01

    By using non-additive Tsallis entropy we demonstrate numerically that one-dimensional quasicrystals, whose energy spectra are multifractal Cantor sets, are characterized by an entropic parameter, and calculate the electronic specific heat, where we consider a non-additive entropy Sq. In our method we consider an energy spectra calculated using the one-dimensional tight binding Schrödinger equation, and their bands (or levels) are scaled onto the [ 0 , 1 ] interval. The Tsallis' formalism is applied to the energy spectra of Fibonacci and double-period one-dimensional quasiperiodic lattices. We analytically obtain an expression for the specific heat that we consider to be more appropriate to calculate this quantity in those quasiperiodic structures.

  7. Modeling of additive manufacturing processes for metals: Challenges and opportunities

    DOE PAGES

    Francois, Marianne M.; Sun, Amy; King, Wayne E.; ...

    2017-01-09

    Here, with the technology being developed to manufacture metallic parts using increasingly advanced additive manufacturing processes, a new era has opened up for designing novel structural materials, from designing shapes and complex geometries to controlling the microstructure (alloy composition and morphology). The material properties used within specific structural components are also designable in order to meet specific performance requirements that are not imaginable with traditional metal forming and machining (subtractive) techniques.

  8. Additional Research Needs to Support the GENII Biosphere Models

    SciTech Connect

    Napier, Bruce A.; Snyder, Sandra F.; Arimescu, Carmen

    2013-11-30

    In the course of evaluating the current parameter needs for the GENII Version 2 code (Snyder et al. 2013), areas of possible improvement for both the data and the underlying models have been identified. As the data review was implemented, PNNL staff identified areas where the models can be improved both to accommodate the locally significant pathways identified and also to incorporate newer models. The areas are general data needs for the existing models and improved formulations for the pathway models. It is recommended that priorities be set by NRC staff to guide selection of the most useful improvements in a cost-effective manner. Suggestions are made based on relatively easy and inexpensive changes, and longer-term more costly studies. In the short term, there are several improved model formulations that could be applied to the GENII suite of codes to make them more generally useful. • Implementation of the separation of the translocation and weathering processes • Implementation of an improved model for carbon-14 from non-atmospheric sources • Implementation of radon exposure pathways models • Development of a KML processor for the output report generator module data that are calculated on a grid that could be superimposed upon digital maps for easier presentation and display • Implementation of marine mammal models (manatees, seals, walrus, whales, etc.). Data needs in the longer term require extensive (and potentially expensive) research. Before picking any one radionuclide or food type, NRC staff should perform an in-house review of current and anticipated environmental analyses to select “dominant” radionuclides of interest to allow setting of cost-effective priorities for radionuclide- and pathway-specific research. These include • soil-to-plant uptake studies for oranges and other citrus fruits, and • Development of models for evaluation of radionuclide concentration in highly-processed foods such as oils and sugars. Finally, renewed

  9. Generalized Additive Models, Cubic Splines and Penalized Likelihood.

    DTIC Science & Technology

    1987-05-22

    in case control studies ). All models in the table include dummy variable to account for the matching. The first 3 lines of the table indicate that OA...Ausoc. Breslow, N. and Day, N. (1980). Statistical methods in cancer research, volume 1- the analysis of case - control studies . International agency

  10. Concentration Addition, Independent Action and Generalized Concentration Addition Models for Mixture Effect Prediction of Sex Hormone Synthesis In Vitro

    PubMed Central

    Hadrup, Niels; Taxvig, Camilla; Pedersen, Mikael; Nellemann, Christine; Hass, Ulla; Vinggaard, Anne Marie

    2013-01-01

    Humans are concomitantly exposed to numerous chemicals. An infinite number of combinations and doses thereof can be imagined. For toxicological risk assessment the mathematical prediction of mixture effects, using knowledge on single chemicals, is therefore desirable. We investigated pros and cons of the concentration addition (CA), independent action (IA) and generalized concentration addition (GCA) models. First we measured effects of single chemicals and mixtures thereof on steroid synthesis in H295R cells. Then single chemical data were applied to the models; predictions of mixture effects were calculated and compared to the experimental mixture data. Mixture 1 contained environmental chemicals adjusted in ratio according to human exposure levels. Mixture 2 was a potency adjusted mixture containing five pesticides. Prediction of testosterone effects coincided with the experimental Mixture 1 data. In contrast, antagonism was observed for effects of Mixture 2 on this hormone. The mixtures contained chemicals exerting only limited maximal effects. This hampered prediction by the CA and IA models, whereas the GCA model could be used to predict a full dose response curve. Regarding effects on progesterone and estradiol, some chemicals were having stimulatory effects whereas others had inhibitory effects. The three models were not applicable in this situation and no predictions could be performed. Finally, the expected contributions of single chemicals to the mixture effects were calculated. Prochloraz was the predominant but not sole driver of the mixtures, suggesting that one chemical alone was not responsible for the mixture effects. In conclusion, the GCA model seemed to be superior to the CA and IA models for the prediction of testosterone effects. A situation with chemicals exerting opposing effects, for which the models could not be applied, was identified. In addition, the data indicate that in non-potency adjusted mixtures the effects cannot always be

  11. Analysis of error-prone survival data under additive hazards models: measurement error effects and adjustments.

    PubMed

    Yan, Ying; Yi, Grace Y

    2016-07-01

    Covariate measurement error occurs commonly in survival analysis. Under the proportional hazards model, measurement error effects have been well studied, and various inference methods have been developed to correct for error effects under such a model. In contrast, error-contaminated survival data under the additive hazards model have received relatively less attention. In this paper, we investigate this problem by exploring measurement error effects on parameter estimation and the change of the hazard function. New insights of measurement error effects are revealed, as opposed to well-documented results for the Cox proportional hazards model. We propose a class of bias correction estimators that embraces certain existing estimators as special cases. In addition, we exploit the regression calibration method to reduce measurement error effects. Theoretical results for the developed methods are established, and numerical assessments are conducted to illustrate the finite sample performance of our methods.

  12. Additional results on 'Reducing geometric dilution of precision using ridge regression'

    NASA Astrophysics Data System (ADS)

    Kelly, Robert J.

    1990-07-01

    Kelly (1990) presented preliminary results on the feasibility of using ridge regression (RR) to reduce the effects of geometric dilution of precision (GDOP) error inflation in position-fix navigation systems. Recent results indicate that RR will not reduce GDOP bias inflation when biaslike measurement errors last much longer than the aircraft guidance-loop response time. This conclusion precludes the use of RR on navigation systems whose dominant error sources are biaslike; e.g., the GPS selective-availability error source. The simulation results given by Kelly are, however, valid for the conditions defined. Although RR has not yielded a satisfactory solution to the general GDOP problem, it has illuminated the role that multicollinearity plays in navigation signal processors such as the Kalman filter. Bias inflation, initial position guess errors, ridge-parameter selection methodology, and the recursive ridge filter are discussed.

  13. Additional results for 'Sequential design approaches for bioequivalence studies with crossover designs'.

    PubMed

    Montague, Timothy H; Potvin, Diane; Diliberti, Charles E; Hauck, Walter W; Parr, Alan F; Schuirmann, Donald J

    2012-01-01

    In 2008, this group published a paper on approaches for two-stage crossover bioequivalence (BE) studies that allowed for the reestimation of the second-stage sample size based on the variance estimated from the first-stage results. The sequential methods considered used an assumed GMR of 0.95 as part of the method for determining power and sample size. This note adds results for an assumed GMR = 0.90. Two of the methods recommended for GMR = 0.95 in the earlier paper have some unacceptable increases in Type I error rate when the GMR is changed to 0.90. If a sponsor wants to assume 0.90 for the GMR, Method D is recommended. Copyright © 2011 John Wiley & Sons, Ltd.

  14. An introduction to modeling longitudinal data with generalized additive models: applications to single-case designs.

    PubMed

    Sullivan, Kristynn J; Shadish, William R; Steiner, Peter M

    2015-03-01

    Single-case designs (SCDs) are short time series that assess intervention effects by measuring units repeatedly over time in both the presence and absence of treatment. This article introduces a statistical technique for analyzing SCD data that has not been much used in psychological and educational research: generalized additive models (GAMs). In parametric regression, the researcher must choose a functional form to impose on the data, for example, that trend over time is linear. GAMs reverse this process by letting the data inform the choice of functional form. In this article we review the problem that trend poses in SCDs, discuss how current SCD analytic methods approach trend, describe GAMs as a possible solution, suggest a GAM model testing procedure for examining the presence of trend in SCDs, present a small simulation to show the statistical properties of GAMs, and illustrate the procedure on 3 examples of different lengths. Results suggest that GAMs may be very useful both as a form of sensitivity analysis for checking the plausibility of assumptions about trend and as a primary data analysis strategy for testing treatment effects. We conclude with a discussion of some problems with GAMs and some future directions for research on the application of GAMs to SCDs.

  15. First Results from the Asteroseismic Modeling Portal

    NASA Astrophysics Data System (ADS)

    Metcalfe, T. S.; Mathur, S.; Doğan, G.; Woitaszek, M.

    2012-09-01

    Asteroseismology will soon place our understanding of the Sun into a broader context by providing structural information for hundreds of solar-type stars. In the past, ground-based data on solar-like oscillations have emerged slowly enough that we could try to model one star at a time. NASA's Kepler mission is now producing asteroseismic data for hundreds of stars every few months, so a hands-on approach is a luxury we can no longer afford. We have developed a stellar model-fitting pipeline, which employs a parallel genetic algorithm to match observations from the Kepler mission. We have validated the method using Sun-as-a-star observations as well as data from a wide variety of solar-type stars. The pipeline is now available through the Asteroseismic Modeling Portal (AMP), a Science Gateway website tied to supercomputing resources on the TeraGrid. In this talk, I provided an overview of AMP and presented some of the first results from its automated analysis of both ground-based and space-based asteroseismic data sets.

  16. Additional Developments in Atmosphere Revitalization Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Coker, Robert F.; Knox, James C.; Cummings, Ramona; Brooks, Thomas; Schunk, Richard G.; Gomez, Carlos

    2013-01-01

    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project within the AES program.

  17. Additional Developments in Atmosphere Revitalization Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Coker, Robert F.; Knox, James C.; Cummings, Ramona; Brooks, Thomas; Schunk, Richard G.

    2013-01-01

    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM)

  18. Flue gas conditioning for improved particle collection in electrostatic precipitators. First topical report, Results of laboratory screening of additives

    SciTech Connect

    Durham, M.D.

    1993-04-16

    Several tasks have been completed in a program to evaluate additives to improve fine particle collection in electrostatic precipitators. Screening tests and laboratory evaluations of additives are summarized in this report. Over 20 additives were evaluated; four were found to improve flyash precipitation rates. The Insitec particle analyzer was also evaluated; test results show that the analyzer will provide accurate sizing and counting information for particles in the size range of {le} 10 {mu}m dia.

  19. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Kenny, R. Jeremy; Vargas, Magda B.

    2013-01-01

    Subscale rocket acoustic data is used to predict acoustic environments for full scale rockets. Over the last several years acoustic data has been collected during horizontal tests of solid rocket motors. Space Launch System (SLS) Scale Model Acoustic Test (SMAT) was designed to evaluate the acoustics of the SLS vehicle including the liquid engines and solid rocket boosters. SMAT is comprised of liquid thrusters scalable to the Space Shuttle Main engines (SSME) and Rocket Assisted Take Off (RATO) motors scalable to the 5-segment Reusable Solid Rocket Motor (RSTMV). Horizontal testing of the liquid thrusters provided an opportunity to collect acoustic data from liquid thrusters to characterize the acoustic environments. Acoustic data was collected during the horizontal firings of a single thruster and a 4-thruster (Quad) configuration. Presentation scope. Discuss the results of the single and 4-thruster acoustic measurements. Compare the measured acoustic levels of the liquid thrusters to the Solid Rocket Test Motor V - Nozzle 2 (SRTMV-N2).

  20. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Vargas, Magda; Kenny, R. Jeremy

    2013-01-01

    The Space Launch System (SLS) Scale Model Acoustic Test (SMAT) is a 5% scale representation of the SLS vehicle, mobile launcher, tower, and launch pad trench. The SLS launch propulsion system will be comprised of the Rocket Assisted Take-Off (RATO) motors representing the solid boosters and 4 Gas Hydrogen (GH2) thrusters representing the core engines. The GH2 thrusters were tested in a horizontal configuration in order to characterize their performance. In Phase 1, a single thruster was fired to determine the engine performance parameters necessary for scaling a single engine. A cluster configuration, consisting of the 4 thrusters, was tested in Phase 2 to integrate the system and determine their combined performance. Acoustic and overpressure data was collected during both test phases in order to characterize the system's acoustic performance. The results from the single thruster and 4- thuster system are discussed and compared.

  1. Modelling Extortion Racket Systems: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Nardin, Luis G.; Andrighetto, Giulia; Székely, Áron; Conte, Rosaria

    Mafias are highly powerful and deeply entrenched organised criminal groups that cause both economic and social damage. Overcoming, or at least limiting, their harmful effects is a societally beneficial objective, which renders its dynamics understanding an objective of both scientific and political interests. We propose an agent-based simulation model aimed at understanding how independent and combined effects of legal and social norm-based processes help to counter mafias. Our results show that legal processes are effective in directly countering mafias by reducing their activities and changing the behaviour of the rest of population, yet they are not able to change people's mind-set that renders the change fragile. When combined with social norm-based processes, however, people's mind-set shifts towards a culture of legality rendering the observed behaviour resilient to change.

  2. The effect of tailor-made additives on crystal growth of methyl paraben: Experiments and modelling

    NASA Astrophysics Data System (ADS)

    Cai, Zhihui; Liu, Yong; Song, Yang; Guan, Guoqiang; Jiang, Yanbin

    2017-03-01

    In this study, methyl paraben (MP) was selected as the model component, and acetaminophen (APAP), p-methyl acetanilide (PMAA) and acetanilide (ACET), which share the similar molecular structure as MP, were selected as the three tailor-made additives to study the effect of tailor-made additives on the crystal growth of MP. HPLC results indicated that the MP crystals induced by the three additives contained MP only. Photographs of the single crystals prepared indicated that the morphology of the MP crystals was greatly changed by the additives, but PXRD and single crystal diffraction results illustrated that the MP crystals were the same polymorph only with different crystal habits, and no new crystal form was found compared with other references. To investigate the effect of the additives on the crystal growth, the interaction between additives and facets was discussed in detail using the DFT methods and MD simulations. The results showed that APAP, PMAA and ACET would be selectively adsorbed on the growth surfaces of the crystal facets, which induced the change in MP crystal habits.

  3. Streaming Limit: New Observations and Model Results

    NASA Astrophysics Data System (ADS)

    Ng, C. K.; Reames, D. V.; Tylka, A. J.

    2010-12-01

    Solar energetic particle intensities at 1 AU often show an early temporal plateau where the intensity is limited. This early intensity limit may provide a valuable time window for astronauts to seek shelter before large shock-associated intensity increase (if any). The Ng and Reames (1994) time-dependent model of SEP transport through self-amplified Alfvén waves predicts a maximum proton intensity of ~ 250 particles /(cm^2 s str MeV) at ~ 1 MeV, in agreement within a factor of 2 with the observational survey by Reames and Ng (1998). In fact, streaming-limited intensity is implicit in the steady-state shock-acceleration solution of Bell (1978) and Lee (1983). Further studies on the effect of self-amplified waves on SEP intensity spectra have been made by Ng, Reames and Tylka (2003), Vanio (2003), and Lee (2005). Intensities exceeding the Ng and Reames (1994) limit have been reported (e.g., Lario et al. 2009). We present new observations of multi-species SEP spectra at the temporal intensity plateau. We also present new theoretical results on how the streaming limit depends on ion species and energy, ambient wave intensity spectrum, Alfvén speed, solar-wind speed, shock speed, and the presence of interplanetary shocks and interaction regions. Among the new interesting observations is the strong suppression of ion intensities near 1 MeV/amu in events that have high 10-100 MeV proton intensity. New modeling results confirm that this is due to these low-energy ions being strongly scattered at small pitch angles by waves amplified by 10-100 MeV protons at large pitch angles. As the high-energy protons travel upstream and scatter from small to large pitch-angles, they simultaneously amplify waves en route over a range of wavenumbers, including those that are resonant with low-energy protons. Thus, wave amplification by streaming protons and the pitch-angle dependence of the wave-particle resonance condition are essential factors in understanding the limiting behavior

  4. Modeling the cardiovascular system using a nonlinear additive autoregressive model with exogenous input

    NASA Astrophysics Data System (ADS)

    Riedl, M.; Suhrbier, A.; Malberg, H.; Penzel, T.; Bretthauer, G.; Kurths, J.; Wessel, N.

    2008-07-01

    The parameters of heart rate variability and blood pressure variability have proved to be useful analytical tools in cardiovascular physics and medicine. Model-based analysis of these variabilities additionally leads to new prognostic information about mechanisms behind regulations in the cardiovascular system. In this paper, we analyze the complex interaction between heart rate, systolic blood pressure, and respiration by nonparametric fitted nonlinear additive autoregressive models with external inputs. Therefore, we consider measurements of healthy persons and patients suffering from obstructive sleep apnea syndrome (OSAS), with and without hypertension. It is shown that the proposed nonlinear models are capable of describing short-term fluctuations in heart rate as well as systolic blood pressure significantly better than similar linear ones, which confirms the assumption of nonlinear controlled heart rate and blood pressure. Furthermore, the comparison of the nonlinear and linear approaches reveals that the heart rate and blood pressure variability in healthy subjects is caused by a higher level of noise as well as nonlinearity than in patients suffering from OSAS. The residue analysis points at a further source of heart rate and blood pressure variability in healthy subjects, in addition to heart rate, systolic blood pressure, and respiration. Comparison of the nonlinear models within and among the different groups of subjects suggests the ability to discriminate the cohorts that could lead to a stratification of hypertension risk in OSAS patients.

  5. NB-PLC channel modelling with cyclostationary noise addition & OFDM implementation for smart grid

    NASA Astrophysics Data System (ADS)

    Thomas, Togis; Gupta, K. K.

    2016-03-01

    Power line communication (PLC) technology can be a viable solution for the future ubiquitous networks because it provides a cheaper alternative to other wired technology currently being used for communication. In smart grid Power Line Communication (PLC) is used to support communication with low rate on low voltage (LV) distribution network. In this paper, we propose the channel modelling of narrowband (NB) PLC in the frequency range 5 KHz to 500 KHz by using ABCD parameter with cyclostationary noise addition. Behaviour of the channel was studied by the addition of 11KV/230V transformer, by varying load location and load. Bit error rate (BER) Vs signal to noise ratio SNR) was plotted for the proposed model by employing OFDM. Our simulation results based on the proposed channel model show an acceptable performance in terms of bit error rate versus signal to noise ratio, which enables communication required for smart grid applications.

  6. COMPARING MODEL RESULTS TO NATIONAL CLIMATE POLICY GOALS: RESULTS FROM THE ASIA MODELING EXERCISE

    SciTech Connect

    Calvin, Katherine V.; Fawcett, Allen A.; Jiang, Kejun

    2012-12-01

    While the world has yet to adopt a single unified policy to limit climate change, many countries and regions have adopted energy and climate policies that have implications for global emissions. In this paper, we discuss a few key policies and how they are included in a set of 24 energy and integrated assessment models that participated in the Asia Modeling Exercise. We also compare results from these models for a small set of stylized scenarios to the pledges made as part of the Copenhagen Accord and the goals stated by the Major Economies Forum. We find that the targets outlined by the United States, the European Union, Japan, and Korea require significant policy action in most of the models analyzed. For most of the models in the study, however, the goals outlined by India are met without any climate policy. The stringency of climate policy required to meet China’s Copenhagen pledges varies across models and accounting methodologies.

  7. Linkage of PRA models. Phase 1, Results

    SciTech Connect

    Smith, C.L.; Knudsen, J.K.; Kelly, D.L.

    1995-12-01

    The goal of the Phase I work of the ``Linkage of PRA Models`` project was to postulate methods of providing guidance for US Nuclear Regulator Commission (NRC) personnel on the selection and usage of probabilistic risk assessment (PRA) models that are best suited to the analysis they are performing. In particular, methods and associated features are provided for (a) the selection of an appropriate PRA model for a particular analysis, (b) complementary evaluation tools for the analysis, and (c) a PRA model cross-referencing method. As part of this work, three areas adjoining ``linking`` analyses to PRA models were investigated: (a) the PRA models that are currently available, (b) the various types of analyses that are performed within the NRC, and (c) the difficulty in trying to provide a ``generic`` classification scheme to groups plants based upon a particular plant attribute.

  8. Does the model of additive effect in placebo research still hold true? A narrative review

    PubMed Central

    Berger, Bettina; Weger, Ulrich; Heusser, Peter

    2017-01-01

    Personalised and contextualised care has been turned into a major demand by people involved in healthcare suggesting to move toward person-centred medicine. The assessment of person-centred medicine can be most effectively achieved if treatments are investigated using ‘with versus without’ person-centredness or integrative study designs. However, this assumes that the components of an integrative or person-centred intervention have an additive relationship to produce the total effect. Beecher’s model of additivity assumes an additive relation between placebo and drug effects and is thus presenting an arithmetic summation. So far, no review has been carried out assessing the validity of the additive model, which is to be questioned and more closely investigated in this review. Initial searches for primary studies were undertaken in July 2016 using Pubmed and Google Scholar. In order to find matching publications of similar magnitude for the comparison part of this review, corresponding matches for all included reviews were sought. A total of 22 reviews and 3 clinical and experimental studies fulfilled the inclusion criteria. The results pointed to the following factors actively questioning the additive model: interactions of various effects, trial design, conditioning, context effects and factors, neurobiological factors, mechanism of action, statistical factors, intervention-specific factors (alcohol, caffeine), side-effects and type of intervention. All but one of the closely assessed publications was questioning the additive model. A closer examination of study design is necessary. An attempt in a more systematic approach geared towards solutions could be a suggestion for future research in this field. PMID:28321318

  9. Analytical results on the Beauchemin model of lymphocyte migration

    PubMed Central

    2013-01-01

    The Beauchemin model is a simple particle-based description of stochastic lymphocyte migration in tissue, which has been successfully applied to studying immunological questions. In addition to being easy to implement, the model is also to a large extent mathematically tractable. This article provides a comprehensive overview of both existing and new analytical results on the Beauchemin model within a common mathematical framework. Specifically, we derive the motility coefficient, the mean square displacement, and the confinement ratio, and discuss four different methods for simulating biased migration of pre-defined speed. The results provide new insight into published studies and a reference point for future research based on this simple and popular lymphocyte migration model. PMID:23734948

  10. Use of anatomical and kinetic models in the evaluation of human food additive safety.

    PubMed

    Roth, William L

    2005-09-22

    Toxicological testing in animals is relied upon as a surrogate for clinical testing of most food additives. Both animal and human clinical test results are generally available for direct additives when high levels of exposure are expected. Limited animal studies or in vitro test results may be the only sources of toxicological data available when low levels of exposure (microg/person/day) are expected and where no effects of the additive on the food itself are desired. Safety assessment of such materials for humans requires mathematical extrapolation from any effects observed in test animals to arrive at acceptable daily intakes (ADIs) for humans. Models of anatomy may be used to estimate tissue and organ weights where that information is missing and necessary for evaluation of a data set. The effect of growth on target tissue exposure during critical phases of organ development can be more accurately assessed when models of growth and known physiological changes are combined with pharmacokinetic results for test species. Kinetic models, when combined with limited chemical property, kinetic, and distribution data, can often be used to predict steady-state plasma and tissue levels of a test material over the range of doses employed in chronic studies to aid in interpretation of effects that are often nonlinear with respect to delivered dose. A better understanding of the reasons for nonlinearity of effects in animals improves our confidence in extrapolation to humans.

  11. Can ligand addition to soil enhance Cd phytoextraction? A mechanistic model study.

    PubMed

    Lin, Zhongbing; Schneider, André; Nguyen, Christophe; Sterckeman, Thibault

    2014-11-01

    Phytoextraction is a potential method for cleaning Cd-polluted soils. Ligand addition to soil is expected to enhance Cd phytoextraction. However, experimental results show that this addition has contradictory effects on plant Cd uptake. A mechanistic model simulating the reaction kinetics (adsorption on solid phase, complexation in solution), transport (convection, diffusion) and root absorption (symplastic, apoplastic) of Cd and its complexes in soil was developed. This was used to calculate plant Cd uptake with and without ligand addition in a great number of combinations of soil, ligand and plant characteristics, varying the parameters within defined domains. Ligand addition generally strongly reduced hydrated Cd (Cd(2+)) concentration in soil solution through Cd complexation. Dissociation of Cd complex ([Formula: see text]) could not compensate for this reduction, which greatly lowered Cd(2+) symplastic uptake by roots. The apoplastic uptake of [Formula: see text] was not sufficient to compensate for the decrease in symplastic uptake. This explained why in the majority of the cases, ligand addition resulted in the reduction of the simulated Cd phytoextraction. A few results showed an enhanced phytoextraction in very particular conditions (strong plant transpiration with high apoplastic Cd uptake capacity), but this enhancement was very limited, making chelant-enhanced phytoextraction poorly efficient for Cd.

  12. Patient-specific in vitro models for hemodynamic analysis of congenital heart disease - Additive manufacturing approach.

    PubMed

    Medero, Rafael; García-Rodríguez, Sylvana; François, Christopher J; Roldán-Alzate, Alejandro

    2017-03-21

    Non-invasive hemodynamic assessment of total cavopulmonary connection (TCPC) is challenging due to the complex anatomy. Additive manufacturing (AM) is a suitable alternative for creating patient-specific in vitro models for flow measurements using four-dimensional (4D) Flow MRI. These in vitro systems have the potential to serve as validation for computational fluid dynamics (CFD), simulating different physiological conditions. This study investigated three different AM technologies, stereolithography (SLA), selective laser sintering (SLS) and fused deposition modeling (FDM), to determine differences in hemodynamics when measuring flow using 4D Flow MRI. The models were created using patient-specific MRI data from an extracardiac TCPC. These models were connected to a perfusion pump circulating water at three different flow rates. Data was processed for visualization and quantification of velocity, flow distribution, vorticity and kinetic energy. These results were compared between each model. In addition, the flow distribution obtained in vitro was compared to in vivo. The results showed significant difference in velocities measured at the outlets of the models that required internal support material when printing. Furthermore, an ultrasound flow sensor was used to validate flow measurements at the inlets and outlets of the in vitro models. These results were highly correlated to those measured with 4D Flow MRI. This study showed that commercially available AM technologies can be used to create patient-specific vascular models for in vitro hemodynamic studies at reasonable costs. However, technologies that do not require internal supports during manufacturing allow smoother internal surfaces, which makes them better suited for flow analyses.

  13. Quantitative magnetospheric models: results and perspectives.

    NASA Astrophysics Data System (ADS)

    Kuznetsova, M.; Hesse, M.; Gombosi, T.; Csem Team

    Global magnetospheric models are indispensable tool that allow multi-point measurements to be put into global context Significant progress is achieved in global MHD modeling of magnetosphere structure and dynamics Medium resolution simulations confirm general topological pictures suggested by Dungey State of the art global models with adaptive grids allow performing simulations with highly resolved magnetopause and magnetotail current sheet Advanced high-resolution models are capable to reproduced transient phenomena such as FTEs associated with formation of flux ropes or plasma bubbles embedded into magnetopause and demonstrate generation of vortices at magnetospheric flanks On the other hand there is still controversy about the global state of the magnetosphere predicted by MHD models to the point of questioning the length of the magnetotail and the location of the reconnection sites within it For example for steady southwards IMF driving condition resistive MHD simulations produce steady configuration with almost stationary near-earth neutral line While there are plenty of observational evidences of periodic loading unloading cycle during long periods of southward IMF Successes and challenges in global modeling of magnetispheric dynamics will be addessed One of the major challenges is to quantify the interaction between large-scale global magnetospheric dynamics and microphysical processes in diffusion regions near reconnection sites Possible solutions to controversies will be discussed

  14. Predicting the occurrence of wildfires with binary structured additive regression models.

    PubMed

    Ríos-Pena, Laura; Kneib, Thomas; Cadarso-Suárez, Carmen; Marey-Pérez, Manuel

    2017-02-01

    Wildfires are one of the main environmental problems facing societies today, and in the case of Galicia (north-west Spain), they are the main cause of forest destruction. This paper used binary structured additive regression (STAR) for modelling the occurrence of wildfires in Galicia. Binary STAR models are a recent contribution to the classical logistic regression and binary generalized additive models. Their main advantage lies in their flexibility for modelling non-linear effects, while simultaneously incorporating spatial and temporal variables directly, thereby making it possible to reveal possible relationships among the variables considered. The results showed that the occurrence of wildfires depends on many covariates which display variable behaviour across space and time, and which largely determine the likelihood of ignition of a fire. The joint possibility of working on spatial scales with a resolution of 1 × 1 km cells and mapping predictions in a colour range makes STAR models a useful tool for plotting and predicting wildfire occurrence. Lastly, it will facilitate the development of fire behaviour models, which can be invaluable when it comes to drawing up fire-prevention and firefighting plans.

  15. Test of the Additivity Principle for Current Fluctuations in a Model of Heat Conduction

    NASA Astrophysics Data System (ADS)

    Hurtado, Pablo I.; Garrido, Pedro L.

    2009-06-01

    The additivity principle allows to compute the current distribution in many one-dimensional (1D) nonequilibrium systems. Using simulations, we confirm this conjecture in the 1D Kipnis-Marchioro-Presutti model of heat conduction for a wide current interval. The current distribution shows both Gaussian and non-Gaussian regimes, and obeys the Gallavotti-Cohen fluctuation theorem. We verify the existence of a well-defined temperature profile associated to a given current fluctuation. This profile is independent of the sign of the current, and this symmetry extends to higher-order profiles and spatial correlations. We also show that finite-time joint fluctuations of the current and the profile are described by the additivity functional. These results suggest the additivity hypothesis as a general and powerful tool to compute current distributions in many nonequilibrium systems.

  16. Test of the additivity principle for current fluctuations in a model of heat conduction.

    PubMed

    Hurtado, Pablo I; Garrido, Pedro L

    2009-06-26

    The additivity principle allows to compute the current distribution in many one-dimensional (1D) nonequilibrium systems. Using simulations, we confirm this conjecture in the 1D Kipnis-Marchioro-Presutti model of heat conduction for a wide current interval. The current distribution shows both Gaussian and non-Gaussian regimes, and obeys the Gallavotti-Cohen fluctuation theorem. We verify the existence of a well-defined temperature profile associated to a given current fluctuation. This profile is independent of the sign of the current, and this symmetry extends to higher-order profiles and spatial correlations. We also show that finite-time joint fluctuations of the current and the profile are described by the additivity functional. These results suggest the additivity hypothesis as a general and powerful tool to compute current distributions in many nonequilibrium systems.

  17. Regulatory network reconstruction using an integral additive model with flexible kernel functions

    PubMed Central

    Novikov, Eugene; Barillot, Emmanuel

    2008-01-01

    Background Reconstruction of regulatory networks is one of the most challenging tasks of systems biology. A limited amount of experimental data and little prior knowledge make the problem difficult to solve. Although models that are currently used for inferring regulatory networks are sometimes able to make useful predictions about the structures and mechanisms of molecular interactions, there is still a strong demand to develop increasingly universal and accurate approaches for network reconstruction. Results The additive regulation model is represented by a set of differential equations and is frequently used for network inference from time series data. Here we generalize this model by converting differential equations into integral equations with adjustable kernel functions. These kernel functions can be selected based on prior knowledge or defined through iterative improvement in data analysis. This makes the integral model very flexible and thus capable of covering a broad range of biological systems more adequately and specifically than previous models. Conclusion We reconstructed network structures from artificial and real experimental data using differential and integral inference models. The artificial data were simulated using mathematical models implemented in JDesigner. The real data were publicly available yeast cell cycle microarray time series. The integral model outperformed the differential one for all cases. In the integral model, we tested the zero-degree polynomial and single exponential kernels. Further improvements could be expected if the kernel were selected more specifically depending on the system. PMID:18218091

  18. Use of additive technologies for practical working with complex models for foundry technologies

    NASA Astrophysics Data System (ADS)

    Olkhovik, E.; Butsanets, A. A.; Ageeva, A. A.

    2016-07-01

    The article presents the results of research of additive technology (3D printing) application for developing a geometrically complex model of castings parts. Investment casting is well known and widely used technology for the production of complex parts. The work proposes the use of a 3D printing technology for manufacturing models parts, which are removed by thermal destruction. Traditional methods of equipment production for investment casting involve the use of manual labor which has problems with dimensional accuracy, and CNC technology which is less used. Such scheme is low productive and demands considerable time. We have offered an alternative method which consists in printing the main knots using a 3D printer (PLA and ABS) with a subsequent production of castings models from them. In this article, the main technological methods are considered and their problems are discussed. The dimensional accuracy of models in comparison with investment casting technology is considered as the main aspect.

  19. Evidence of thermal additivity during short laser pulses in an in vitro retinal model

    NASA Astrophysics Data System (ADS)

    Denton, Michael L.; Tijerina, Amanda J.; Dyer, Phillip N.; Oian, Chad A.; Noojin, Gary D.; Rickman, John M.; Shingledecker, Aurora D.; Clark, Clifton D.; Castellanos, Cherry C.; Thomas, Robert J.; Rockwell, Benjamin A.

    2015-03-01

    Laser damage thresholds were determined for exposure to 2.5-ms 532-nm pulses in an established in vitro retinal model. Single and multiple pulses (10, 100, 1000) were delivered to the cultured cells at three different pulse repetition frequency (PRF) values, and overt damage (membrane breach) was scored 1 hr post laser exposure. Trends in the damage data within and across the PRF range identified significant thermal additivity as PRF was increased, as evidenced by drastically reduced threshold values (< 40% of single-pulse value). Microthermography data that were collected in real time during each exposure also provided evidence of thermal additivity between successive laser pulses. Using thermal profiles simulated at high temporal resolution, damage threshold values were predicted by an in-house computational model. Our simulated ED50 value for a single 2.5-ms pulse was in very good agreement with experimental results, but ED50 predictions for multiple-pulse trains will require more refinement.

  20. AERMOD: MODEL FORMULATION AND EVALUATION RESULTS

    EPA Science Inventory

    AERMOD is an advanced plume model that incorporates updated treatments of the boundary layer theory, understanding of turbulence and dispersion, and includes handling of terrain interactions. This paper presents an overview of AERMOD's features relative to ISCST3.

    AERM...

  1. Testing Numerical Dynamo Models Against Experimental Results

    NASA Astrophysics Data System (ADS)

    Gissinger, C. J.; Fauve, S.; Dormy, E.

    2007-12-01

    Significant progress has been achieved over the past few years in describing the geomagnetic field using computer models for dynamo action. Such models are so far limited to parameter regimes which are very remote from actual values relevant to the Earth core or any liquid metal (the magnetic Prandtl number is always over estimated by a factor at least 104). While existing models successfully reproduce many of the magnetic observations, it is difficult to assert their validity. The recent success of an experimental homogeneous unconstrained dynamo (VKS) provides a new way to investigate dynamo action in turbulent conducting flows, but it also offers a chance to test the validity of exisiting numerical models. We use a code originaly written for the Geodynamo (Parody) and apply it to the experimental configuration. The direct comparison of simulations and experiments is of great interest to test the predictive value of numerical simulations for dynamo action. These turbulent simulations allow us to approach issues which are very relevant for geophysical dynamos, especially the competition between different magnetic modes and the dynamics of reversals.

  2. SOURCE APPORTIONMENT RESULTS, UNCERTAINTIES, AND MODELING TOOLS

    EPA Science Inventory

    Advanced multivariate receptor modeling tools are available from the U.S. Environmental Protection Agency (EPA) that use only speciated sample data to identify and quantify sources of air pollution. EPA has developed both EPA Unmix and EPA Positive Matrix Factorization (PMF) and ...

  3. Model for energy transfer in the solar wind: Model results

    NASA Technical Reports Server (NTRS)

    Barnes, A. A., Jr.; Hartle, R. E.

    1972-01-01

    A description is given of the results of solar wind flow in which the heating is due to (1) propagation and dissipation of hydromagnetic waves generated near the base of the wind, and (2) thermal conduction. A series of models is generated for fixed values of density, electron and proton temperature, and magnetic field at the base by varying the wave intensity at the base of the model. This series of models predicts the observed correlation between flow speed and proton temperature for a large range of velocities. The wave heating takes place in a shell about the sun greater than or approximately equal to 10 R thick. We conclude that large-scale variations observed in the solar wind are probably due mainly to variation in the hydromagnetic wave flux near the sun.

  4. First Results From a Dynamic Fog Climatology Modeling System

    NASA Astrophysics Data System (ADS)

    O'Brien, T. A.; Sloan, L.; Chuang, P. Y.; Faloona, I. C.; Snyder, M. A.; Rossiter, D. L.

    2010-12-01

    We have coupled a new boundary layer model to a regional climate model (RegCM4) in order to dynamically (as opposed to empirically) simulate marine stratocumulus and coastal fog. We drive the coupled RCM with NCEP's new 20th Century reanalysis dataset in order to simulate a 120 year climatology of coastal fog. Even at relatively coarse resolution (50 km) this fog modeling system exhibits significant skill in simulating the interannual variability and long-term trends that have been observed in summertime fog on California's coast. In agreement with results from Johnstone and Dawson (2010), we simulate a high correlation between fog variability in Monterey and Arcata (in addition to other locations along California's coast), which indicates that interannual fog variability is driven by large-scale forcing. Preliminary results suggest that a trend in this same large-scale forcing is also responsible for the century-long decline of summertime coastal fog.

  5. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Task 3 Full-scale Test Results

    SciTech Connect

    Gary Blythe

    2007-05-01

    in Texas Lignite Flue Gas; Task 3 - Full-scale FGD Additive Testing in High-sulfur Eastern Bituminous Flue Gas; Task 4 - Pilot Wet Scrubber Additive Tests at Plant Yates; and Task 5 - Full-scale Additive Tests at Plant Yates. The pilot-scale tests were completed in 2005 and have been previously reported. This topical report presents the results from the Task 3 full-scale additive tests, conducted at IPL's Petersburg Station Unit 2. The Task 5 full-scale additive tests will be conducted later in calendar year 2007.

  6. Flying Training Capacity Model: Initial Results

    DTIC Science & Technology

    2005-06-21

    numbers by base • FTRAP model is not versatile • Excel spreadsheets based on corporate knowledge • Requires flying training subject matter expert ( SME ... IFR & VFR operations • Capacity given in terms of runway operations per year • AETC Capacity Metrics - Graduates • Based on sortie generation • Consider...Pilots (IPs) from each course • Airspace capacities from base operations SMEs • Runway capacities • Military Operating Area capacities (including aux

  7. Boosted structured additive regression for Escherichia coli fed-batch fermentation modeling.

    PubMed

    Melcher, Michael; Scharl, Theresa; Luchner, Markus; Striedner, Gerald; Leisch, Friedrich

    2017-02-01

    The quality of biopharmaceuticals and patients' safety are of highest priority and there are tremendous efforts to replace empirical production process designs by knowledge-based approaches. Main challenge in this context is that real-time access to process variables related to product quality and quantity is severely limited. To date comprehensive on- and offline monitoring platforms are used to generate process data sets that allow for development of mechanistic and/or data driven models for real-time prediction of these important quantities. Ultimate goal is to implement model based feed-back control loops that facilitate online control of product quality. In this contribution, we explore structured additive regression (STAR) models in combination with boosting as a variable selection tool for modeling the cell dry mass, product concentration, and optical density on the basis of online available process variables and two-dimensional fluorescence spectroscopic data. STAR models are powerful extensions of linear models allowing for inclusion of smooth effects or interactions between predictors. Boosting constructs the final model in a stepwise manner and provides a variable importance measure via predictor selection frequencies. Our results show that the cell dry mass can be modeled with a relative error of about ±3%, the optical density with ±6%, the soluble protein with ±16%, and the insoluble product with an accuracy of ±12%. Biotechnol. Bioeng. 2017;114: 321-334. © 2016 Wiley Periodicals, Inc.

  8. Model for Assembly Line Re-Balancing Considering Additional Capacity and Outsourcing to Face Demand Fluctuations

    NASA Astrophysics Data System (ADS)

    Samadhi, TMAA; Sumihartati, Atin

    2016-02-01

    The most critical stage in a garment industry is sewing process, because generally, it consists of a number of operations and a large number of sewing machines for each operation. Therefore, it requires a balancing method that can assign task to work station with balance workloads. Many studies on assembly line balancing assume a new assembly line, but in reality, due to demand fluctuation and demand increased a re-balancing is needed. To cope with those fluctuating demand changes, additional capacity can be carried out by investing in spare sewing machine and paying for sewing service through outsourcing. This study develops an assembly line balancing (ALB) model on existing line to cope with fluctuating demand change. Capacity redesign is decided if the fluctuation demand exceeds the available capacity through a combination of making investment on new machines and outsourcing while considering for minimizing the cost of idle capacity in the future. The objective of the model is to minimize the total cost of the line assembly that consists of operating costs, machine cost, adding capacity cost, losses cost due to idle capacity and outsourcing costs. The model develop is based on an integer programming model. The model is tested for a set of data of one year demand with the existing number of sewing machines of 41 units. The result shows that additional maximum capacity up to 76 units of machine required when there is an increase of 60% of the average demand, at the equal cost parameters..

  9. GPM Microwave Imager Engineering Model Results

    NASA Technical Reports Server (NTRS)

    Newell, David; Krimchansky, Sergey

    2010-01-01

    The Global Precipitation Measurement (GPM) Microwave Imager (GMI) Instrument is being developed by Ball Aerospace and Technology Corporation (BATC) for the GPM program at NASA Goddard. The Global Precipitation Measurement (GPM) mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and more frequent precipitation measurements. The GPM Microwave Imager (GMI) will be used to make calibrated, radiometric measurements from space at multiple microwave frequencies and polarizations. GMI will be placed on the GPM Core Spacecraft together with the Dualfrequency Precipitation Radar (DPR). The DPR is two-frequency precipitation measurement radar, which will operate in the Ku-band and Ka-band of the microwave spectrum. The Core Spacecraft will make radiometric and radar measurements of clouds and precipitation and will be the central element ofGPM's space segment. The data products from GPM will provide information concerning global precipitation on a frequent, near-global basis to meteorologists and scientists making weather forecasts and performing research on the global energy and water cycle, precipitation, hydrology, and related disciplines. In addition, radiometric measurements from GMI and radar measurements from the DPR will be used together to develop a retrieval transfer standard for the purpose of calibrating precipitation retrieval algorithms. This calibration standard will establish a reference against which other retrieval algorithms using only microwave radiometers (and without the benefit of the DPR) on other satellites in the GPM constellation will be compared.

  10. New results in fault latency modelling

    NASA Technical Reports Server (NTRS)

    Mcgough, J. G.; Swern, F. L.; Bavuso, S.

    1983-01-01

    Studies carried out by McGough and Swern (1981, 1983) are summarized. In these studies, an avionics processor was simulated and a series of fault injection experiments was carried out to determine the degree of fault latency in a redundant flight control system that employed comparison monitoring as the exclusive means of failure detection. A determination was also made of the fault coverage of a typical self-test program. The summary presented stresses that a self-test program should be designed to capitalize on the hardware mechanization of the processor. If this is not done, subtests tend to repeatedly exercise the same hardware components while neglecting to exercise a substantial proportion of the remainder. It is also pointed out that fault latency is relatively independent of both the length and instruction mix of a program. A significant difference is found in fault coverage assessed using pin-level and gate-level fault models.

  11. Additive Manufacturing Modeling and Simulation A Literature Review for Electron Beam Free Form Fabrication

    NASA Technical Reports Server (NTRS)

    Seufzer, William J.

    2014-01-01

    Additive manufacturing is coming into industrial use and has several desirable attributes. Control of the deposition remains a complex challenge, and so this literature review was initiated to capture current modeling efforts in the field of additive manufacturing. This paper summarizes about 10 years of modeling and simulation related to both welding and additive manufacturing. The goals were to learn who is doing what in modeling and simulation, to summarize various approaches taken to create models, and to identify research gaps. Later sections in the report summarize implications for closed-loop-control of the process, implications for local research efforts, and implications for local modeling efforts.

  12. MODIS Solar Diffuser Attenuation Screen Modeling Results

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xuong, Xiaoxiong; Guenther, Bruce; Barnes, William

    2004-01-01

    On-orbit calibration of the reflected solar bands on the EOS Moderate Resolution Imaging Spectroradiometer (MODIS) is accomplished by have the instrument view a high reflectance diffuse surface illuminated by the sun. For some of the spectral bands this proves to be much too bright a signal that results in the saturation of detectors designed for measuring low reflectance (ocean) surfaces signals. A mechanical attenuation device in the form of a pin hole screen is used to reduce the signals to calibrate these bands. The sensor response to solar illumination of the SD with and without the attenuation screen in place will be presented. The MODIS detector response to the solar diffuser is smooth when the attenuation screen is absent, but has structures up to a few percent when the attenuation screen is present. This structure corresponds to non-uniform illumination from the solar diffuser. Each pin hole produces a pin-hole image of the sun on the solar diffuser, and there are very many pin hole images of the sun on the solar diffuser for each MODIS detector. Even though there are very many pin-hole images of the sun on the solar diffuser, it is no longer perfectly uniformly illuminated. This non-uniformly illuminated solar diffuser produces intensity variation on the focal planes. The results of a very detailed simulation will be discussed which show how the illumination of the focal plane changes as a result of the attenuation, and the impacts on the calibration will be discussed.

  13. Recent results from strangeness in transport models

    NASA Astrophysics Data System (ADS)

    Steinheimer, J.; Botvina, A. S.; Bleicher, M.

    2016-01-01

    In these proceedings we discuss recent developments in the microscopic description of strange particle production in nuclear collisions. We put a special emphasis on the production of hypernuclei at the upcoming FAIR and NICA facilities as well as the deep sub threshold, ϕ and Ξ- production yields measured with the HADES experiment. Employing new resonance decay channels we obtain a satisfactory description of ϕ and Ξ- production in deep sub threshold Ar+KCl reactions. Our results implicate that no new medium effects are required to describe the rare strange particle production data from low energy nuclear collisions.

  14. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Task 5 Full-Scale Test Results

    SciTech Connect

    Gary Blythe; MariJon Owens

    2007-12-01

    and reporting. The other four tasks involve field testing on FGD systems, either at pilot or full scale. The four tasks include: Task 2 - Pilot Additive Testing in Texas Lignite Flue Gas; Task 3 - Full-scale FGD Additive Testing in High-sulfur Eastern Bituminous Flue Gas; Task 4 - Pilot Wet Scrubber Additive Tests at Plant Yates; and Task 5 - Full-scale Additive Tests at Plant Yates. The pilot-scale tests and the full-scale test using high-sulfur coal were completed in 2005 and 2006 and have been previously reported. This topical report presents the results from the Task 5 full-scale additive tests, conducted at Southern Company's Plant Yates Unit 1. Both additives were tested there.

  15. Effect of lime addition during sewage sludge treatment on characteristics of resulting SSA when it is used in cementitious materials.

    PubMed

    Vouk, D; Nakic, D; Štirmer, N; Baricevic, A

    2017-02-01

    Final disposal of sewage sludge is important not only in terms of satisfying the regulations, but the aspect of choosing the optimal wastewater treatment technology, including the sludge treatment. In most EU countries, significant amounts of stabilized and dewatered sludge are incinerated, and sewage sludge ash (SSA) is generated as a by product. At the same time, lime is one of the commonly used additives in the sewage sludge treatment primarily to stabilize the sludge. In doing so, the question arose how desirable is such addition of lime if the sludge is subsequently incinerated, and the generated ash is further used in the production of cementitious materials. A series of mortars were prepared where 10-20% of the cement fraction was replaced by SSA. Since all three types of analyzed SSA (without lime, with lime added during sludge stabilization and with extra lime added during sludge incineration) yielded nearly same results, it can be concluded that if sludge incineration is accepted solution, lime addition during sludge treatment is unnecessary even from the standpoint of preserving the pozzolanic properties of the resulting SSA. Results of the research carried out on cement mortars point to the great possibilities of using SSA in concrete industry.

  16. Preliminary results of steel containment vessel model test

    SciTech Connect

    Luk, V.K.; Hessheimer, M.F.; Matsumoto, T.; Komine, K.; Arai, S.; Costello, J.F.

    1998-04-01

    A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11--12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented.

  17. Assessment of Galileo modal test results for mathematical model verification

    NASA Technical Reports Server (NTRS)

    Trubert, M.

    1984-01-01

    The modal test program for the Galileo Spacecraft was completed at the Jet Propulsion Laboratory in the summer of 1983. The multiple sine dwell method was used for the baseline test. The Galileo Spacecraft is a rather complex 2433 kg structure made of a central core on which seven major appendages representing 30 percent of the total mass are attached, resulting in a high modal density structure. The test revealed a strong nonlinearity in several major modes. This nonlinearity discovered in the course of the test necessitated running additional tests at the unusually high response levels of up to about 21 g. The high levels of response were required to obtain a model verification valid at the level of loads for which the spacecraft was designed. Because of the high modal density and the nonlinearity, correlation between the dynamic mathematical model and the test results becomes a difficult task. Significant changes in the pre-test analytical model are necessary to establish confidence in the upgraded analytical model used for the final load verification. This verification, using a test verified model, is required by NASA to fly the Galileo Spacecraft on the Shuttle/Centaur launch vehicle in 1986.

  18. Grain-Size Based Additivity Models for Scaling Multi-rate Uranyl Surface Complexation in Subsurface Sediments

    SciTech Connect

    Zhang, Xiaoying; Liu, Chongxuan; Hu, Bill X.; Hu, Qinhong

    2015-09-28

    This study statistically analyzed a grain-size based additivity model that has been proposed to scale reaction rates and parameters from laboratory to field. The additivity model assumed that reaction properties in a sediment including surface area, reactive site concentration, reaction rate, and extent can be predicted from field-scale grain size distribution by linearly adding reaction properties for individual grain size fractions. This study focused on the statistical analysis of the additivity model with respect to reaction rate constants using multi-rate uranyl (U(VI)) surface complexation reactions in a contaminated sediment as an example. Experimental data of rate-limited U(VI) desorption in a stirred flow-cell reactor were used to estimate the statistical properties of multi-rate parameters for individual grain size fractions. The statistical properties of the rate constants for the individual grain size fractions were then used to analyze the statistical properties of the additivity model to predict rate-limited U(VI) desorption in the composite sediment, and to evaluate the relative importance of individual grain size fractions to the overall U(VI) desorption. The result indicated that the additivity model provided a good prediction of the U(VI) desorption in the composite sediment. However, the rate constants were not directly scalable using the additivity model, and U(VI) desorption in individual grain size fractions have to be simulated in order to apply the additivity model. An approximate additivity model for directly scaling rate constants was subsequently proposed and evaluated. The result found that the approximate model provided a good prediction of the experimental results within statistical uncertainty. This study also found that a gravel size fraction (2-8mm), which is often ignored in modeling U(VI) sorption and desorption, is statistically significant to the U(VI) desorption in the sediment.

  19. Addition of sargramostim (GM-CSF) to imatinib results in major cytogenetic response in a patient with chronic myeloid leukemia.

    PubMed

    Connor, Rebecca F; Hurd, David; Pettenati, Mark J; Koty, Patrick; Molnár, István

    2006-10-01

    Imatinib mesylate, an inhibitor of BCR/ABL tyrosine kinase, has remarkable activity in chronic myeloid leukemia resulting in an 87% major cytogenetic response. We describe a woman who failed to achieve any cytogenetic response after 2.5 years of imatinib, 400mg daily. When daily sargramostim (GM-CSF) 100 microg/m2 was added, cytogenetic studies revealed a gradual increase in percentage of normal cells from start, 4, 9, and 15 months at 0%, 10%, 55%, and 85%, respectively. She became transfusion independent after starting GM-CSF. The addition of GM-CSF to imatinib resulted in a clinical benefit and a major cytogenetic response in this patient.

  20. [Postoperative results under the new stage classification of lung cancer: the additional reports for those of JACS in 1996].

    PubMed

    Shirakusa, T

    2000-10-01

    This time, in 3008 lung cancer patients, the postoperative results were analyzed under the new stage grouping of TNM classification. All of those patients underwent the operation in 1989, and the 5 year-survival rates had beeb surveyed in 1996 by JACS (The Japanese Association for Chest Surgery). Under the new TNM classification established in 1996 worldwidey, T3N0M0 was transferred from IIIA to IIB. This report is the additional one in the focus of the results accompanied with the change of TNM classification.

  1. Comparison of prosthetic models produced by traditional and additive manufacturing methods

    PubMed Central

    Park, Jin-Young; Kim, Hae-Young; Kim, Ji-Hwan; Kim, Jae-Hong

    2015-01-01

    PURPOSE The purpose of this study was to verify the clinical-feasibility of additive manufacturing by comparing the accuracy of four different manufacturing methods for metal coping: the conventional lost wax technique (CLWT); subtractive methods with wax blank milling (WBM); and two additive methods, multi jet modeling (MJM), and micro-stereolithography (Micro-SLA). MATERIALS AND METHODS Thirty study models were created using an acrylic model with the maxillary upper right canine, first premolar, and first molar teeth. Based on the scan files from a non-contact blue light scanner (Identica; Medit Co. Ltd., Seoul, Korea), thirty cores were produced using the WBM, MJM, and Micro-SLA methods, respectively, and another thirty frameworks were produced using the CLWT method. To measure the marginal and internal gap, the silicone replica method was adopted, and the silicone images obtained were evaluated using a digital microscope (KH-7700; Hirox, Tokyo, Japan) at 140X magnification. Analyses were performed using two-way analysis of variance (ANOVA) and Tukey post hoc test (α=.05). RESULTS The mean marginal gaps and internal gaps showed significant differences according to tooth type (P<.001 and P<.001, respectively) and manufacturing method (P<.037 and P<.001, respectively). Micro-SLA did not show any significant difference from CLWT regarding mean marginal gap compared to the WBM and MJM methods. CONCLUSION The mean values of gaps resulting from the four different manufacturing methods were within a clinically allowable range, and, thus, the clinical use of additive manufacturing methods is acceptable as an alternative to the traditional lost wax-technique and subtractive manufacturing. PMID:26330976

  2. Revisiting automated G-protein coupled receptor modeling: the benefit of additional template structures for a neurokinin-1 receptor model.

    PubMed

    Kneissl, Benny; Leonhardt, Bettina; Hildebrandt, Andreas; Tautermann, Christofer S

    2009-05-28

    The feasibility of automated procedures for the modeling of G-protein coupled receptors (GPCR) is investigated on the example of the human neurokinin-1 (NK1) receptor. We use a combined method of homology modeling and molecular docking and analyze the information content of the resulting docking complexes regarding the binding mode for further refinements. Moreover, we explore the impact of different template structures, the bovine rhodopsin structure, the human beta(2) adrenergic receptor, and in particular a combination of both templates to include backbone flexibility in the target conformational space. Our results for NK1 modeling demonstrate that model selection from a set of decoys can in general not solely rely on docking experiments but still requires additional mutagenesis data. However, an enrichment factor of 2.6 in a nearly fully automated approach indicates that reasonable models can be created automatically if both available templates are used for model construction. Thus, the recently resolved GPCR structures open new ways to improve the model building fundamentally.

  3. Generalized Additive Models Used to Predict Species Abundance in the Gulf of Mexico: An Ecosystem Modeling Tool

    PubMed Central

    Drexler, Michael; Ainsworth, Cameron H.

    2013-01-01

    Spatially explicit ecosystem models of all types require an initial allocation of biomass, often in areas where fisheries independent abundance estimates do not exist. A generalized additive modelling (GAM) approach is used to describe the abundance of 40 species groups (i.e. functional groups) across the Gulf of Mexico (GoM) using a large fisheries independent data set (SEAMAP) and climate scale oceanographic conditions. Predictor variables included in the model are chlorophyll a, sediment type, dissolved oxygen, temperature, and depth. Despite the presence of a large number of zeros in the data, a single GAM using a negative binomial distribution was suitable to make predictions of abundance for multiple functional groups. We present an example case study using pink shrimp (Farfantepenaeus duroarum) and compare the results to known distributions. The model successfully predicts the known areas of high abundance in the GoM, including those areas where no data was inputted into the model fitting. Overall, the model reliably captures areas of high and low abundance for the large majority of functional groups observed in SEAMAP. The result of this method allows for the objective setting of spatial distributions for numerous functional groups across a modeling domain, even where abundance data may not exist. PMID:23691223

  4. Marginal regression approach for additive hazards models with clustered current status data.

    PubMed

    Su, Pei-Fang; Chi, Yunchan

    2014-01-15

    Current status data arise naturally from tumorigenicity experiments, epidemiology studies, biomedicine, econometrics and demographic and sociology studies. Moreover, clustered current status data may occur with animals from the same litter in tumorigenicity experiments or with subjects from the same family in epidemiology studies. Because the only information extracted from current status data is whether the survival times are before or after the monitoring or censoring times, the nonparametric maximum likelihood estimator of survival function converges at a rate of n(1/3) to a complicated limiting distribution. Hence, semiparametric regression models such as the additive hazards model have been extended for independent current status data to derive the test statistics, whose distributions converge at a rate of n(1/2) , for testing the regression parameters. However, a straightforward application of these statistical methods to clustered current status data is not appropriate because intracluster correlation needs to be taken into account. Therefore, this paper proposes two estimating functions for estimating the parameters in the additive hazards model for clustered current status data. The comparative results from simulation studies are presented, and the application of the proposed estimating functions to one real data set is illustrated.

  5. Phase-Field Modeling of Microstructure Evolution in Electron Beam Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Gong, Xibing; Chou, Kevin

    2015-05-01

    In this study, the microstructure evolution in the powder-bed electron beam additive manufacturing (EBAM) process is studied using phase-field modeling. In essence, EBAM involves a rapid solidification process and the properties of a build partly depend on the solidification behavior as well as the microstructure of the build material. Thus, the prediction of microstructure evolution in EBAM is of importance for its process optimization. Phase-field modeling was applied to study the microstructure evolution and solute concentration of the Ti-6Al-4V alloy in the EBAM process. The effect of undercooling was investigated through the simulations; the greater the undercooling, the faster the dendrite grows. The microstructure simulations show multiple columnar-grain growths, comparable with experimental results for the tested range.

  6. Improving the predictive accuracy of hurricane power outage forecasts using generalized additive models.

    PubMed

    Han, Seung-Ryong; Guikema, Seth D; Quiring, Steven M

    2009-10-01

    Electric power is a critical infrastructure service after hurricanes, and rapid restoration of electric power is important in order to minimize losses in the impacted areas. However, rapid restoration of electric power after a hurricane depends on obtaining the necessary resources, primarily repair crews and materials, before the hurricane makes landfall and then appropriately deploying these resources as soon as possible after the hurricane. This, in turn, depends on having sound estimates of both the overall severity of the storm and the relative risk of power outages in different areas. Past studies have developed statistical, regression-based approaches for estimating the number of power outages in advance of an approaching hurricane. However, these approaches have either not been applicable for future events or have had lower predictive accuracy than desired. This article shows that a different type of regression model, a generalized additive model (GAM), can outperform the types of models used previously. This is done by developing and validating a GAM based on power outage data during past hurricanes in the Gulf Coast region and comparing the results from this model to the previously used generalized linear models.

  7. Analysis of Time to Event Outcomes in Randomized Controlled Trials by Generalized Additive Models

    PubMed Central

    Argyropoulos, Christos; Unruh, Mark L.

    2015-01-01

    Background Randomized Controlled Trials almost invariably utilize the hazard ratio calculated with a Cox proportional hazard model as a treatment efficacy measure. Despite the widespread adoption of HRs, these provide a limited understanding of the treatment effect and may even provide a biased estimate when the assumption of proportional hazards in the Cox model is not verified by the trial data. Additional treatment effect measures on the survival probability or the time scale may be used to supplement HRs but a framework for the simultaneous generation of these measures is lacking. Methods By splitting follow-up time at the nodes of a Gauss Lobatto numerical quadrature rule, techniques for Poisson Generalized Additive Models (PGAM) can be adopted for flexible hazard modeling. Straightforward simulation post-estimation transforms PGAM estimates for the log hazard into estimates of the survival function. These in turn were used to calculate relative and absolute risks or even differences in restricted mean survival time between treatment arms. We illustrate our approach with extensive simulations and in two trials: IPASS (in which the proportionality of hazards was violated) and HEMO a long duration study conducted under evolving standards of care on a heterogeneous patient population. Findings PGAM can generate estimates of the survival function and the hazard ratio that are essentially identical to those obtained by Kaplan Meier curve analysis and the Cox model. PGAMs can simultaneously provide multiple measures of treatment efficacy after a single data pass. Furthermore, supported unadjusted (overall treatment effect) but also subgroup and adjusted analyses, while incorporating multiple time scales and accounting for non-proportional hazards in survival data. Conclusions By augmenting the HR conventionally reported, PGAMs have the potential to support the inferential goals of multiple stakeholders involved in the evaluation and appraisal of clinical trial

  8. Predicting the Survival Time for Bladder Cancer Using an Additive Hazards Model in Microarray Data

    PubMed Central

    TAPAK, Leili; MAHJUB, Hossein; SADEGHIFAR, Majid; SAIDIJAM, Massoud; POOROLAJAL, Jalal

    2016-01-01

    Background: One substantial part of microarray studies is to predict patients’ survival based on their gene expression profile. Variable selection techniques are powerful tools to handle high dimensionality in analysis of microarray data. However, these techniques have not been investigated in competing risks setting. This study aimed to investigate the performance of four sparse variable selection methods in estimating the survival time. Methods: The data included 1381 gene expression measurements and clinical information from 301 patients with bladder cancer operated in the years 1987 to 2000 in hospitals in Denmark, Sweden, Spain, France, and England. Four methods of the least absolute shrinkage and selection operator, smoothly clipped absolute deviation, the smooth integration of counting and absolute deviation and elastic net were utilized for simultaneous variable selection and estimation under an additive hazards model. The criteria of area under ROC curve, Brier score and c-index were used to compare the methods. Results: The median follow-up time for all patients was 47 months. The elastic net approach was indicated to outperform other methods. The elastic net had the lowest integrated Brier score (0.137±0.07) and the greatest median of the over-time AUC and C-index (0.803±0.06 and 0.779±0.13, respectively). Five out of 19 selected genes by the elastic net were significant (P<0.05) under an additive hazards model. It was indicated that the expression of RTN4, SON, IGF1R and CDC20 decrease the survival time, while the expression of SMARCAD1 increase it. Conclusion: The elastic net had higher capability than the other methods for the prediction of survival time in patients with bladder cancer in the presence of competing risks base on additive hazards model. PMID:27114989

  9. Topsoil organic carbon content of Europe, a new map based on a generalised additive model

    NASA Astrophysics Data System (ADS)

    de Brogniez, Delphine; Ballabio, Cristiano; Stevens, Antoine; Jones, Robert J. A.; Montanarella, Luca; van Wesemael, Bas

    2014-05-01

    There is an increasing demand for up-to-date spatially continuous organic carbon (OC) data for global environment and climatic modeling. Whilst the current map of topsoil organic carbon content for Europe (Jones et al., 2005) was produced by applying expert-knowledge based pedo-transfer rules on large soil mapping units, the aim of this study was to replace it by applying digital soil mapping techniques on the first European harmonised geo-referenced topsoil (0-20 cm) database, which arises from the LUCAS (land use/cover area frame statistical survey) survey. A generalized additive model (GAM) was calibrated on 85% of the dataset (ca. 17 000 soil samples) and a backward stepwise approach selected slope, land cover, temperature, net primary productivity, latitude and longitude as environmental covariates (500 m resolution). The validation of the model (applied on 15% of the dataset), gave an R2 of 0.27. We observed that most organic soils were under-predicted by the model and that soils of Scandinavia were also poorly predicted. The model showed an RMSE of 42 g kg-1 for mineral soils and of 287 g kg-1 for organic soils. The map of predicted OC content showed the lowest values in Mediterranean countries and in croplands across Europe, whereas highest OC content were predicted in wetlands, woodlands and in mountainous areas. The map of standard error of the OC model predictions showed high values in northern latitudes, wetlands, moors and heathlands, whereas low uncertainty was mostly found in croplands. A comparison of our results with the map of Jones et al. (2005) showed a general agreement on the prediction of mineral soils' OC content, most probably because the models use some common covariates, namely land cover and temperature. Our model however failed to predict values of OC content greater than 200 g kg-1, which we explain by the imposed unimodal distribution of our model, whose mean is tilted towards the majority of soils, which are mineral. Finally, average

  10. Grain-Size Based Additivity Models for Scaling Multi-rate Uranyl Surface Complexation in Subsurface Sediments

    SciTech Connect

    Zhang, Xiaoying; Liu, Chongxuan; Hu, Bill X.; Hu, Qinhong

    2015-09-28

    The additivity model assumed that field-scale reaction properties in a sediment including surface area, reactive site concentration, and reaction rate can be predicted from field-scale grain-size distribution by linearly adding reaction properties estimated in laboratory for individual grain-size fractions. This study evaluated the additivity model in scaling mass transfer-limited, multi-rate uranyl (U(VI)) surface complexation reactions in a contaminated sediment. Experimental data of rate-limited U(VI) desorption in a stirred flow-cell reactor were used to estimate the statistical properties of the rate constants for individual grain-size fractions, which were then used to predict rate-limited U(VI) desorption in the composite sediment. The result indicated that the additivity model with respect to the rate of U(VI) desorption provided a good prediction of U(VI) desorption in the composite sediment. However, the rate constants were not directly scalable using the additivity model. An approximate additivity model for directly scaling rate constants was subsequently proposed and evaluated. The result found that the approximate model provided a good prediction of the experimental results within statistical uncertainty. This study also found that a gravel-size fraction (2 to 8 mm), which is often ignored in modeling U(VI) sorption and desorption, is statistically significant to the U(VI) desorption in the sediment.

  11. Results of a sub-scale model rotor icing test

    NASA Technical Reports Server (NTRS)

    Flemming, Robert J.; Bond, Thomas H.; Britton, Randall K.

    1991-01-01

    A heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA Lewis Research Center Icing Research Tunnel (IRT) in September and November 1989. The four-bladed main rotor had a diameter of 1.83 m (6.00 ft) and the 0.124 m (4.9 in) chord rotor blades were specially fabricated for this experiment. The instrumented rotor was mounted on a Sikorsky Aircraft Powered Force Model, which enclosed a rotor balance and other measurement systems. The model rotor was exposed to a range of icing conditions that included variations in temperature, liquid water content, and median droplet diameter, and was operated over ranges of advance ratio, shaft angle, tip Mach number (rotor speed) and weight coefficient to determine the effect of these parameters on ice accretion. In addition to strain gage and balance data, the test was documented with still, video, and high speed photography, ice profile tracings, and ice molds. The sensitivity of the model rotor to the test parameters, is given, and the result to theoretical predictions are compared. Test data quality was excellent, and ice accretion prediction methods and rotor performance prediction methods (using published icing lift and drag relationships) reproduced the performance trends observed in the test. Adjustments to the correlation coefficients to improve the level of correlation are suggested.

  12. A habitat suitability model for Chinese sturgeon determined using the generalized additive method

    NASA Astrophysics Data System (ADS)

    Yi, Yujun; Sun, Jie; Zhang, Shanghong

    2016-03-01

    The Chinese sturgeon is a type of large anadromous fish that migrates between the ocean and rivers. Because of the construction of dams, this sturgeon's migration path has been cut off, and this species currently is on the verge of extinction. Simulating suitable environmental conditions for spawning followed by repairing or rebuilding its spawning grounds are effective ways to protect this species. Various habitat suitability models based on expert knowledge have been used to evaluate the suitability of spawning habitat. In this study, a two-dimensional hydraulic simulation is used to inform a habitat suitability model based on the generalized additive method (GAM). The GAM is based on real data. The values of water depth and velocity are calculated first via the hydrodynamic model and later applied in the GAM. The final habitat suitability model is validated using the catch per unit effort (CPUEd) data of 1999 and 2003. The model results show that a velocity of 1.06-1.56 m/s and a depth of 13.33-20.33 m are highly suitable ranges for the Chinese sturgeon to spawn. The hydraulic habitat suitability indexes (HHSI) for seven discharges (4000; 9000; 12,000; 16,000; 20,000; 30,000; and 40,000 m3/s) are calculated to evaluate integrated habitat suitability. The results show that the integrated habitat suitability reaches its highest value at a discharge of 16,000 m3/s. This study is the first to apply a GAM to evaluate the suitability of spawning grounds for the Chinese sturgeon. The study provides a reference for the identification of potential spawning grounds in the entire basin.

  13. Regression mixture models: Does modeling the covariance between independent variables and latent classes improve the results?

    PubMed Central

    Lamont, Andrea E.; Vermunt, Jeroen K.; Van Horn, M. Lee

    2016-01-01

    Regression mixture models are increasingly used as an exploratory approach to identify heterogeneity in the effects of a predictor on an outcome. In this simulation study, we test the effects of violating an implicit assumption often made in these models – i.e., independent variables in the model are not directly related to latent classes. Results indicated that the major risk of failing to model the relationship between predictor and latent class was an increase in the probability of selecting additional latent classes and biased class proportions. Additionally, this study tests whether regression mixture models can detect a piecewise relationship between a predictor and outcome. Results suggest that these models are able to detect piecewise relations, but only when the relationship between the latent class and the predictor is included in model estimation. We illustrate the implications of making this assumption through a re-analysis of applied data examining heterogeneity in the effects of family resources on academic achievement. We compare previous results (which assumed no relation between independent variables and latent class) to the model where this assumption is lifted. Implications and analytic suggestions for conducting regression mixture based on these findings are noted. PMID:26881956

  14. Regression Mixture Models: Does Modeling the Covariance Between Independent Variables and Latent Classes Improve the Results?

    PubMed

    Lamont, Andrea E; Vermunt, Jeroen K; Van Horn, M Lee

    2016-01-01

    Regression mixture models are increasingly used as an exploratory approach to identify heterogeneity in the effects of a predictor on an outcome. In this simulation study, we tested the effects of violating an implicit assumption often made in these models; that is, independent variables in the model are not directly related to latent classes. Results indicate that the major risk of failing to model the relationship between predictor and latent class was an increase in the probability of selecting additional latent classes and biased class proportions. In addition, we tested whether regression mixture models can detect a piecewise relationship between a predictor and outcome. Results suggest that these models are able to detect piecewise relations but only when the relationship between the latent class and the predictor is included in model estimation. We illustrate the implications of making this assumption through a reanalysis of applied data examining heterogeneity in the effects of family resources on academic achievement. We compare previous results (which assumed no relation between independent variables and latent class) to the model where this assumption is lifted. Implications and analytic suggestions for conducting regression mixture based on these findings are noted.

  15. Modeling the flux of metabolites in the juvenile hormone biosynthesis pathway using generalized additive models and ordinary differential equations.

    PubMed

    Martínez-Rincón, Raúl O; Rivera-Pérez, Crisalejandra; Diambra, Luis; Noriega, Fernando G

    2017-01-01

    Juvenile hormone (JH) regulates development and reproductive maturation in insects. The corpora allata (CA) from female adult mosquitoes synthesize fluctuating levels of JH, which have been linked to the ovarian development and are influenced by nutritional signals. The rate of JH biosynthesis is controlled by the rate of flux of isoprenoids in the pathway, which is the outcome of a complex interplay of changes in precursor pools and enzyme levels. A comprehensive study of the changes in enzymatic activities and precursor pool sizes have been previously reported for the mosquito Aedes aegypti JH biosynthesis pathway. In the present studies, we used two different quantitative approaches to describe and predict how changes in the individual metabolic reactions in the pathway affect JH synthesis. First, we constructed generalized additive models (GAMs) that described the association between changes in specific metabolite concentrations with changes in enzymatic activities and substrate concentrations. Changes in substrate concentrations explained 50% or more of the model deviances in 7 of the 13 metabolic steps analyzed. Addition of information on enzymatic activities almost always improved the fitness of GAMs built solely based on substrate concentrations. GAMs were validated using experimental data that were not included when the model was built. In addition, a system of ordinary differential equations (ODE) was developed to describe the instantaneous changes in metabolites as a function of the levels of enzymatic catalytic activities. The results demonstrated the ability of the models to predict changes in the flux of metabolites in the JH pathway, and can be used in the future to design and validate experimental manipulations of JH synthesis.

  16. Modeling the flux of metabolites in the juvenile hormone biosynthesis pathway using generalized additive models and ordinary differential equations

    PubMed Central

    Martínez-Rincón, Raúl O.; Rivera-Pérez, Crisalejandra; Diambra, Luis; Noriega, Fernando G.

    2017-01-01

    Juvenile hormone (JH) regulates development and reproductive maturation in insects. The corpora allata (CA) from female adult mosquitoes synthesize fluctuating levels of JH, which have been linked to the ovarian development and are influenced by nutritional signals. The rate of JH biosynthesis is controlled by the rate of flux of isoprenoids in the pathway, which is the outcome of a complex interplay of changes in precursor pools and enzyme levels. A comprehensive study of the changes in enzymatic activities and precursor pool sizes have been previously reported for the mosquito Aedes aegypti JH biosynthesis pathway. In the present studies, we used two different quantitative approaches to describe and predict how changes in the individual metabolic reactions in the pathway affect JH synthesis. First, we constructed generalized additive models (GAMs) that described the association between changes in specific metabolite concentrations with changes in enzymatic activities and substrate concentrations. Changes in substrate concentrations explained 50% or more of the model deviances in 7 of the 13 metabolic steps analyzed. Addition of information on enzymatic activities almost always improved the fitness of GAMs built solely based on substrate concentrations. GAMs were validated using experimental data that were not included when the model was built. In addition, a system of ordinary differential equations (ODE) was developed to describe the instantaneous changes in metabolites as a function of the levels of enzymatic catalytic activities. The results demonstrated the ability of the models to predict changes in the flux of metabolites in the JH pathway, and can be used in the future to design and validate experimental manipulations of JH synthesis. PMID:28158248

  17. Modeling external carbon addition in biological nutrient removal processes with an extension of the international water association activated sludge model.

    PubMed

    Swinarski, M; Makinia, J; Stensel, H D; Czerwionka, K; Drewnowski, J

    2012-08-01

    The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to account for a newly defined readily biodegradable substrate that can be consumed by polyphosphate-accumulating organisms (PAOs) under anoxic and aerobic conditions, but not under anaerobic conditions. The model change was to add a new substrate component and process terms for its use by PAOs and other heterotrophic bacteria under anoxic and aerobic conditions. The Gdansk (Poland) wastewater treatment plant (WWTP), which has a modified University of Cape Town (MUCT) process for nutrient removal, provided field data and mixed liquor for batch tests for model evaluation. The original ASM2d was first calibrated under dynamic conditions with the results of batch tests with settled wastewater and mixed liquor, in which nitrate-uptake rates, phosphorus-release rates, and anoxic phosphorus uptake rates were followed. Model validation was conducted with data from a 96-hour measurement campaign in the full-scale WWTP. The results of similar batch tests with ethanol and fusel oil as the external carbon sources were used to adjust kinetic and stoichiometric coefficients in the expanded ASM2d. Both models were compared based on their predictions of the effect of adding supplemental carbon to the anoxic zone of an MUCT process. In comparison with the ASM2d, the new model better predicted the anoxic behaviors of carbonaceous oxygen demand, nitrate-nitrogen (NO3-N), and phosphorous (PO4-P) in batch experiments with ethanol and fusel oil. However, when simulating ethanol addition to the anoxic zone of a full-scale biological nutrient removal facility, both models predicted similar effluent NO3-N concentrations (6.6 to 6.9 g N/m3). For the particular application, effective enhanced biological phosphorus removal was predicted by both models with external carbon addition but, for the new model, the effluent PO4-P concentration was approximately one-half of that found from

  18. Testing a Gender Additive Model: The Role of Body Image in Adolescent Depression

    ERIC Educational Resources Information Center

    Bearman, Sarah Kate; Stice, Eric

    2008-01-01

    Despite consistent evidence that adolescent girls are at greater risk of developing depression than adolescent boys, risk factor models that account for this difference have been elusive. The objective of this research was to examine risk factors proposed by the "gender additive" model of depression that attempts to partially explain the increased…

  19. Modeling particulate matter concentrations measured through mobile monitoring in a deletion/substitution/addition approach

    NASA Astrophysics Data System (ADS)

    Su, Jason G.; Hopke, Philip K.; Tian, Yilin; Baldwin, Nichole; Thurston, Sally W.; Evans, Kristin; Rich, David Q.

    2015-12-01

    Land use regression modeling (LUR) through local scale circular modeling domains has been used to predict traffic-related air pollution such as nitrogen oxides (NOX). LUR modeling for fine particulate matters (PM), which generally have smaller spatial gradients than NOX, has been typically applied for studies involving multiple study regions. To increase the spatial coverage for fine PM and key constituent concentrations, we designed a mobile monitoring network in Monroe County, New York to measure pollutant concentrations of black carbon (BC, wavelength at 880 nm), ultraviolet black carbon (UVBC, wavelength at 3700 nm) and Delta-C (the difference between the UVBC and BC concentrations) using the Clarkson University Mobile Air Pollution Monitoring Laboratory (MAPL). A Deletion/Substitution/Addition (D/S/A) algorithm was conducted, which used circular buffers as a basis for statistics. The algorithm maximizes the prediction accuracy for locations without measurements using the V-fold cross-validation technique, and it reduces overfitting compared to other approaches. We found that the D/S/A LUR modeling approach could achieve good results, with prediction powers of 60%, 63%, and 61%, respectively, for BC, UVBC, and Delta-C. The advantage of mobile monitoring is that it can monitor pollutant concentrations at hundreds of spatial points in a region, rather than the typical less than 100 points from a fixed site saturation monitoring network. This research indicates that a mobile saturation sampling network, when combined with proper modeling techniques, can uncover small area variations (e.g., 10 m) in particulate matter concentrations.

  20. Can homeopathy bring additional benefits to thalassemic patients on hydroxyurea therapy? Encouraging results of a preliminary study.

    PubMed

    Banerjee, Antara; Chakrabarty, Sudipa Basu; Karmakar, Susanta Roy; Chakrabarty, Amit; Biswas, Surjyo Jyoti; Haque, Saiful; Das, Debarsi; Paul, Saili; Mandal, Biswapati; Naoual, Boujedaini; Belon, Philippe; Khuda-Bukhsh, Anisur Rahman

    2010-03-01

    Several homeopathic remedies, namely, Pulsatilla Nigricans (30th potency), Ceanothus Americanus (both mother tincture and 6th potency) and Ferrum Metallicum (30th potency) selected as per similia principles were administered to 38 thalassemic patients receiving Hydroxyurea (HU) therapy for a varying period of time. Levels of serum ferritin (SF), fetal hemoglobin (HbF), hemoglobin (Hb), platelet count (PC), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), white blood cell (WBC) count, bilirubin content, alanine amino transferase (ALT), aspartate amino transferase (AST) and serum total protein content of patients were determined before and 3 months after administration of the homeopathic remedies in combination with HU to evaluate additional benefits, if any, derived by the homeopathic remedies, by comparing the data with those of 38 subjects receiving only HU therapy. Preliminary results indicated that there was a significant decrease in the SF and increase in HbF levels in the combined, treated subjects. Although the changes in other parameters were not so significant, there was a significant decrease in size of spleen in most patients with spleenomegaly and improvement in general health conditions along with an increased gap between transfusions in most patients receiving the combined homeopathic treatment. The homeopathic remedies being inexpensive and without any known side-effects seem to have great potentials in bringing additional benefits to thalassemic patients; particularly in the developing world where blood transfusions suffer from inadequate screening and fall short of the stringent safety standards followed in the developed countries. Further independent studies are encouraged.

  1. Additive surface complexation modeling of uranium(VI) adsorption onto quartz-sand dominated sediments.

    PubMed

    Dong, Wenming; Wan, Jiamin

    2014-06-17

    Many aquifers contaminated by U(VI)-containing acidic plumes are composed predominantly of quartz-sand sediments. The F-Area of the Savannah River Site (SRS) in South Carolina (USA) is an example. To predict U(VI) mobility and natural attenuation, we conducted U(VI) adsorption experiments using the F-Area plume sediments and reference quartz, goethite, and kaolinite. The sediments are composed of ∼96% quartz-sand and 3-4% fine fractions of kaolinite and goethite. We developed a new humic acid adsorption method for determining the relative surface area abundances of goethite and kaolinite in the fine fractions. This method is expected to be applicable to many other binary mineral pairs, and allows successful application of the component additivity (CA) approach based surface complexation modeling (SCM) at the SRS F-Area and other similar aquifers. Our experimental results indicate that quartz has stronger U(VI) adsorption ability per unit surface area than goethite and kaolinite at pH ≤ 4.0. Our modeling results indicate that the binary (goethite/kaolinite) CA-SCM under-predicts U(VI) adsorption to the quartz-sand dominated sediments at pH ≤ 4.0. The new ternary (quartz/goethite/kaolinite) CA-SCM provides excellent predictions. The contributions of quartz-sand, kaolinite, and goethite to U(VI) adsorption and the potential influences of dissolved Al, Si, and Fe are also discussed.

  2. Estimate of influenza cases using generalized linear, additive and mixed models.

    PubMed

    Oviedo, Manuel; Domínguez, Ángela; Pilar Muñoz, M

    2015-01-01

    We investigated the relationship between reported cases of influenza in Catalonia (Spain). Covariates analyzed were: population, age, data of report of influenza, and health region during 2010-2014 using data obtained from the SISAP program (Institut Catala de la Salut - Generalitat of Catalonia). Reported cases were related with the study of covariates using a descriptive analysis. Generalized Linear Models, Generalized Additive Models and Generalized Additive Mixed Models were used to estimate the evolution of the transmission of influenza. Additive models can estimate non-linear effects of the covariates by smooth functions; and mixed models can estimate data dependence and variability in factor variables using correlations structures and random effects, respectively. The incidence rate of influenza was calculated as the incidence per 100 000 people. The mean rate was 13.75 (range 0-27.5) in the winter months (December, January, February) and 3.38 (range 0-12.57) in the remaining months. Statistical analysis showed that Generalized Additive Mixed Models were better adapted to the temporal evolution of influenza (serial correlation 0.59) than classical linear models.

  3. Results of Satellite Brightness Modeling Using Kringing Optimized Interpolation

    NASA Astrophysics Data System (ADS)

    Weeden, C.; Hejduk, M.

    At the 2005 AMOS conference, Kriging Optimized Interpolation (KOI) was presented as a tool to model satellite brightness as a function of phase angle and solar declination angle (J.M Okada and M.D. Hejduk). Since November 2005, this method has been used to support the tasking algorithm for all optical sensors in the Space Surveillance Network (SSN). The satellite brightness maps generated by the KOI program are compared to each sensor's ability to detect an object as a function of the brightness of the background sky and angular rate of the object. This will determine if the sensor can technically detect an object based on an explicit calculation of the object's probability of detection. In addition, recent upgrades at Ground-Based Electro Optical Deep Space Surveillance Sites (GEODSS) sites have increased the amount and quality of brightness data collected and therefore available for analysis. This in turn has provided enough data to study the modeling process in more detail in order to obtain the most accurate brightness prediction of satellites. Analysis of two years of brightness data gathered from optical sensors and modeled via KOI solutions are outlined in this paper. By comparison, geo-stationary objects (GEO) were tracked less than non-GEO objects but had higher density tracking in phase angle due to artifices of scheduling. A statistically-significant fit to a deterministic model was possible less than half the time in both GEO and non-GEO tracks, showing that a stochastic model must often be used alone to produce brightness results, but such results are nonetheless serviceable. Within the Kriging solution, the exponential variogram model was the most frequently employed in both GEO and non-GEO tracks, indicating that monotonic brightness variation with both phase and solar declination angle is common and testifying to the suitability to the application of regionalized variable theory to this particular problem. Finally, the average nugget value, or

  4. Impact of an additional chronic BDNF reduction on learning performance in an Alzheimer mouse model

    PubMed Central

    Psotta, Laura; Rockahr, Carolin; Gruss, Michael; Kirches, Elmar; Braun, Katharina; Lessmann, Volkmar; Bock, Jörg; Endres, Thomas

    2015-01-01

    There is increasing evidence that brain-derived neurotrophic factor (BDNF) plays a crucial role in Alzheimer’s disease (AD) pathology. A number of studies demonstrated that AD patients exhibit reduced BDNF levels in the brain and the blood serum, and in addition, several animal-based studies indicated a potential protective effect of BDNF against Aβ-induced neurotoxicity. In order to further investigate the role of BDNF in the etiology of AD, we created a novel mouse model by crossing a well-established AD mouse model (APP/PS1) with a mouse exhibiting a chronic BDNF deficiency (BDNF+/−). This new triple transgenic mouse model enabled us to further analyze the role of BDNF in AD in vivo. We reasoned that in case BDNF has a protective effect against AD pathology, an AD-like phenotype in our new mouse model should occur earlier and/or in more severity than in the APP/PS1-mice. Indeed, the behavioral analysis revealed that the APP/PS1-BDNF+/−-mice show an earlier onset of learning impairments in a two-way active avoidance task in comparison to APP/PS1- and BDNF+/−-mice. However in the Morris water maze (MWM) test, we could not observe an overall aggrevated impairment in spatial learning and also short-term memory in an object recognition task remained intact in all tested mouse lines. In addition to the behavioral experiments, we analyzed the amyloid plaque pathology in the APP/PS1 and APP/PS1-BDNF+/−-mice and observed a comparable plaque density in the two genotypes. Moreover, our results revealed a higher plaque density in prefrontal cortical compared to hippocampal brain regions. Our data reveal that higher cognitive tasks requiring the recruitment of cortical networks appear to be more severely affected in our new mouse model than learning tasks requiring mainly sub-cortical networks. Furthermore, our observations of an accelerated impairment in active avoidance learning in APP/PS1-BDNF+/−-mice further supports the hypothesis that BDNF deficiency

  5. Accuracy and Precision in the Southern Hemisphere Additional Ozonesondes (SHADOZ) Dataset in Light of the JOSIE-2000 Results

    NASA Technical Reports Server (NTRS)

    Witte, Jacquelyn C.; Thompson, Anne M.; Schmidlin, F. J.; Oltmans, S. J.; Smit, H. G. J.

    2004-01-01

    Since 1998 the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has provided over 2000 ozone profiles over eleven southern hemisphere tropical and subtropical stations. Balloon-borne electrochemical concentration cell (ECC) ozonesondes are used to measure ozone. The data are archived at: &ttp://croc.gsfc.nasa.gov/shadoz>. In analysis of ozonesonde imprecision within the SHADOZ dataset, Thompson et al. [JGR, 108,8238,20031 we pointed out that variations in ozonesonde technique (sensor solution strength, instrument manufacturer, data processing) could lead to station-to-station biases within the SHADOZ dataset. Imprecisions and accuracy in the SHADOZ dataset are examined in light of new data. First, SHADOZ total ozone column amounts are compared to version 8 TOMS (2004 release). As for TOMS version 7, satellite total ozone is usually higher than the integrated column amount from the sounding. Discrepancies between the sonde and satellite datasets decline two percentage points on average, compared to version 7 TOMS offsets. Second, the SHADOZ station data are compared to results of chamber simulations (JOSE-2000, Juelich Ozonesonde Intercomparison Experiment) in which the various SHADOZ techniques were evaluated. The range of JOSE column deviations from a standard instrument (-10%) in the chamber resembles that of the SHADOZ station data. It appears that some systematic variations in the SHADOZ ozone record are accounted for by differences in solution strength, data processing and instrument type (manufacturer).

  6. Inclusion of Additional Plant Species and Trait Information in Dynamic Vegetation Modeling of Arctic Tundra and Boreal Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Euskirchen, E. S.; Patil, V.; Roach, J.; Griffith, B.; McGuire, A. D.

    2015-12-01

    Dynamic vegetation models (DVMs) have been developed to model the ecophysiological characteristics of plant functional types in terrestrial ecosystems. They have frequently been used to answer questions pertaining to processes such as disturbance, plant succession, and community composition under historical and future climate scenarios. While DVMs have proved useful in these types of applications, it has often been questioned if additional detail, such as including plant dynamics at the species-level and/or including species-specific traits would make these models more accurate and/or broadly applicable. A sub-question associated with this issue is, 'How many species, or what degree of functional diversity, should we incorporate to sustain ecosystem function in modeled ecosystems?' Here, we focus on how the inclusion of additional plant species and trait information may strengthen dynamic vegetation modeling in applications pertaining to: (1) forage for caribou in northern Alaska, (2) above- and belowground carbon storage in the boreal forest and lake margin wetlands of interior Alaska, and (3) arctic tundra and boreal forest leaf phenology. While the inclusion of additional information generally proved valuable in these three applications, this additional detail depends on field data that may not always be available and may also result in increased computational complexity. Therefore, it is important to assess these possible limitations against the perceived need for additional plant species and trait information in the development and application of dynamic vegetation models.

  7. Results of EPRI/ANL DCH investigations and model development

    SciTech Connect

    Spencer, B.W.; Sienicki, J.J.; Sehgal, B.R.; Merilo, M.

    1988-01-01

    The results of a series of five experiments are described addressing the severity and mitigation of direct containment heating. The tests were performed in a 1:30 linear scale mockup of the Zion PWR containment system using a reactor-material corium melt consisting of 60% UO/sub 2/, 16% ZrO/sub 2/, 24% SSt at nominally 2800C initial temperature. A ''worst-case'' type test involving unimpeded corium dispersal through an air atmosphere in a closed vessel produced an atmosphere heatup of 323K, equivalent to a DCH efficiency of 62%. With the addition of structural features which impeded the corium dispersal, representative of dispersal pathway features at Zion, the DCH efficiency was reduced to 1--5%. (This important result is scale dependent and requires larger scale tests such as the SURTSEY program at SNL plus mechanistic modeling for application to the reactor system.) With the addition of water in the cavity region, there was no measurable heatup of the atmosphere. This was attributable to the vigorous codispersal of water with corium which prevented the temperature of the atmosphere from significantly exceeding T/sub sat/. In this case the DCH load was replaced by the more benign ''steam spike'' from corium quench. Significant oxidation of the corium constituents occurred in the tests, adding chemical energy to the system and producing hydrogen. Overall, the results suggest that with consideration of realistic, plant specific, mitigating features, DCH may be no worse and possibly far less severe than the previously examined steam spike. Implications for accident management are addressed. 17 refs., 7 figs., 4 tabs.

  8. Subsea Permafrost Climate Modeling - Challenges and First Results

    NASA Astrophysics Data System (ADS)

    Rodehacke, C. B.; Stendel, M.; Marchenko, S. S.; Christensen, J. H.; Romanovsky, V. E.; Nicolsky, D.

    2015-12-01

    Recent observations indicate that the East Siberian Arctic Shelf (ESAS) releases methane, which stems from shallow hydrate seabed reservoirs. The total amount of carbon within the ESAS is so large that release of only a small fraction, for example via taliks, which are columns of unfrozen sediment within the permafrost, could impact distinctly the global climate. Therefore it is crucial to simulate the future fate of ESAS' subsea permafrost with regard to changing atmospheric and oceanic conditions. However only very few attempts to address the vulnerability of subsea permafrost have been made, instead most studies have focused on the evolution of permafrost since the Late Pleistocene ocean transgression, approximately 14000 years ago.In contrast to land permafrost modeling, any attempt to model the future fate of subsea permafrost needs to consider several additional factors, in particular the dependence of freezing temperature on water depth and salt content and the differences in ground heat flux depending on the seabed properties. Also the amount of unfrozen water in the sediment needs to be taken into account. Using a system of coupled ocean, atmosphere and permafrost models will allow us to capture the complexity of the different parts of the system and evaluate the relative importance of different processes. Here we present the first results of a novel approach by means of dedicated permafrost model simulations. These have been driven by conditions of the Laptev Sea region in East Siberia. By exploiting the ensemble approach, we will show how uncertainties in boundary conditions and applied forcing scenarios control the future fate of the sub sea permafrost.

  9. Use of generalised additive models to categorise continuous variables in clinical prediction

    PubMed Central

    2013-01-01

    Background In medical practice many, essentially continuous, clinical parameters tend to be categorised by physicians for ease of decision-making. Indeed, categorisation is a common practice both in medical research and in the development of clinical prediction rules, particularly where the ensuing models are to be applied in daily clinical practice to support clinicians in the decision-making process. Since the number of categories into which a continuous predictor must be categorised depends partly on the relationship between the predictor and the outcome, the need for more than two categories must be borne in mind. Methods We propose a categorisation methodology for clinical-prediction models, using Generalised Additive Models (GAMs) with P-spline smoothers to determine the relationship between the continuous predictor and the outcome. The proposed method consists of creating at least one average-risk category along with high- and low-risk categories based on the GAM smooth function. We applied this methodology to a prospective cohort of patients with exacerbated chronic obstructive pulmonary disease. The predictors selected were respiratory rate and partial pressure of carbon dioxide in the blood (PCO2), and the response variable was poor evolution. An additive logistic regression model was used to show the relationship between the covariates and the dichotomous response variable. The proposed categorisation was compared to the continuous predictor as the best option, using the AIC and AUC evaluation parameters. The sample was divided into a derivation (60%) and validation (40%) samples. The first was used to obtain the cut points while the second was used to validate the proposed methodology. Results The three-category proposal for the respiratory rate was ≤ 20;(20,24];> 24, for which the following values were obtained: AIC=314.5 and AUC=0.638. The respective values for the continuous predictor were AIC=317.1 and AUC=0.634, with no statistically

  10. Collaborations Resulting in New Leadership Model Operationalization with Disadvantaged Students

    ERIC Educational Resources Information Center

    Nikodym, Jacqueline Z.; Tejeda, Armando R.; Moffett, David W.

    2015-01-01

    A new leadership model is needed in all organizations. In response, The Affect-Centered Transformational Leadership Model came about. The new model resulted from a doctoral student's participation in a leadership course, and continued dialogue with its professor. Ultimately, the new model reached the stage of needing to be operationalized. A…

  11. Modeling and additive manufacturing of bio-inspired composites with tunable fracture mechanical properties.

    PubMed

    Dimas, Leon S; Buehler, Markus J

    2014-07-07

    Flaws, imperfections and cracks are ubiquitous in material systems and are commonly the catalysts of catastrophic material failure. As stresses and strains tend to concentrate around cracks and imperfections, structures tend to fail far before large regions of material have ever been subjected to significant loading. Therefore, a major challenge in material design is to engineer systems that perform on par with pristine structures despite the presence of imperfections. In this work we integrate knowledge of biological systems with computational modeling and state of the art additive manufacturing to synthesize advanced composites with tunable fracture mechanical properties. Supported by extensive mesoscale computer simulations, we demonstrate the design and manufacturing of composites that exhibit deformation mechanisms characteristic of pristine systems, featuring flaw-tolerant properties. We analyze the results by directly comparing strain fields for the synthesized composites, obtained through digital image correlation (DIC), and the computationally tested composites. Moreover, we plot Ashby diagrams for the range of simulated and experimental composites. Our findings show good agreement between simulation and experiment, confirming that the proposed mechanisms have a significant potential for vastly improving the fracture response of composite materials. We elucidate the role of stiffness ratio variations of composite constituents as an important feature in determining the composite properties. Moreover, our work validates the predictive ability of our models, presenting them as useful tools for guiding further material design. This work enables the tailored design and manufacturing of composites assembled from inferior building blocks, that obtain optimal combinations of stiffness and toughness.

  12. Evaluation of the performance of smoothing functions in generalized additive models for spatial variation in disease.

    PubMed

    Siangphoe, Umaporn; Wheeler, David C

    2015-01-01

    Generalized additive models (GAMs) with bivariate smoothing functions have been applied to estimate spatial variation in risk for many types of cancers. Only a handful of studies have evaluated the performance of smoothing functions applied in GAMs with regard to different geographical areas of elevated risk and different risk levels. This study evaluates the ability of different smoothing functions to detect overall spatial variation of risk and elevated risk in diverse geographical areas at various risk levels using a simulation study. We created five scenarios with different true risk area shapes (circle, triangle, linear) in a square study region. We applied four different smoothing functions in the GAMs, including two types of thin plate regression splines (TPRS) and two versions of locally weighted scatterplot smoothing (loess). We tested the null hypothesis of constant risk and detected areas of elevated risk using analysis of deviance with permutation methods and assessed the performance of the smoothing methods based on the spatial detection rate, sensitivity, accuracy, precision, power, and false-positive rate. The results showed that all methods had a higher sensitivity and a consistently moderate-to-high accuracy rate when the true disease risk was higher. The models generally performed better in detecting elevated risk areas than detecting overall spatial variation. One of the loess methods had the highest precision in detecting overall spatial variation across scenarios and outperformed the other methods in detecting a linear elevated risk area. The TPRS methods outperformed loess in detecting elevated risk in two circular areas.

  13. Evaluation of the Performance of Smoothing Functions in Generalized Additive Models for Spatial Variation in Disease

    PubMed Central

    Siangphoe, Umaporn; Wheeler, David C.

    2015-01-01

    Generalized additive models (GAMs) with bivariate smoothing functions have been applied to estimate spatial variation in risk for many types of cancers. Only a handful of studies have evaluated the performance of smoothing functions applied in GAMs with regard to different geographical areas of elevated risk and different risk levels. This study evaluates the ability of different smoothing functions to detect overall spatial variation of risk and elevated risk in diverse geographical areas at various risk levels using a simulation study. We created five scenarios with different true risk area shapes (circle, triangle, linear) in a square study region. We applied four different smoothing functions in the GAMs, including two types of thin plate regression splines (TPRS) and two versions of locally weighted scatterplot smoothing (loess). We tested the null hypothesis of constant risk and detected areas of elevated risk using analysis of deviance with permutation methods and assessed the performance of the smoothing methods based on the spatial detection rate, sensitivity, accuracy, precision, power, and false-positive rate. The results showed that all methods had a higher sensitivity and a consistently moderate-to-high accuracy rate when the true disease risk was higher. The models generally performed better in detecting elevated risk areas than detecting overall spatial variation. One of the loess methods had the highest precision in detecting overall spatial variation across scenarios and outperformed the other methods in detecting a linear elevated risk area. The TPRS methods outperformed loess in detecting elevated risk in two circular areas. PMID:25983545

  14. Enhanced coding in a cochlear-implant model using additive noise: Aperiodic stochastic resonance with tuning

    NASA Astrophysics Data System (ADS)

    Morse, Robert P.; Roper, Peter

    2000-05-01

    Analog electrical stimulation of the cochlear nerve (the nerve of hearing) by a cochlear implant is an effective method of providing functional hearing to profoundly deaf people. Recent physiological and computational experiments have shown that analog cochlear implants are unlikely to convey certain speech cues by the temporal pattern of evoked nerve discharges. However, these experiments have also shown that the optimal addition of noise to cochlear implant signals can enhance the temporal representation of speech cues [R. P. Morse and E. F. Evans, Nature Medicine 2, 928 (1996)]. We present a simple model to explain this enhancement of temporal representation. Our model derives from a rate equation for the mean threshold-crossing rate of an infinite set of parallel discriminators (level-crossing detectors); a system that well describes the time coding of information by a set of nerve fibers. Our results show that the optimal transfer of information occurs when the threshold level of each discriminator is equal to the root-mean-square noise level. The optimal transfer of information by a cochlear implant is therefore expected to occur when the internal root-mean-square noise level of each stimulated fiber is approximately equal to the nerve threshold. When interpreted within the framework of aperiodic stochastic resonance, our results indicate therefore that for an infinite array of discriminators, a tuning of the noise is still necessary for optimal performance. This is in contrast to previous results [Collins, Chow, and Imhoff, Nature 376, 236 (1995); Chialvo, Longtin, and Müller-Gerking, Phys. Rev. E 55, 1798 (1997)] on arrays of FitzHugh-Nagumo neurons.

  15. MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS

    SciTech Connect

    Nash, C.; Hang, T.; Aleman, S.

    2011-01-03

    Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.

  16. Integrated reservoir characterization: Improvement in heterogeneities stochastic modelling by integration of additional external constraints

    SciTech Connect

    Doligez, B.; Eschard, R.; Geffroy, F.

    1997-08-01

    The classical approach to construct reservoir models is to start with a fine scale geological model which is informed with petrophysical properties. Then scaling-up techniques allow to obtain a reservoir model which is compatible with the fluid flow simulators. Geostatistical modelling techniques are widely used to build the geological models before scaling-up. These methods provide equiprobable images of the area under investigation, which honor the well data, and which variability is the same than the variability computed from the data. At an appraisal phase, when few data are available, or when the wells are insufficient to describe all the heterogeneities and the behavior of the field, additional constraints are needed to obtain a more realistic geological model. For example, seismic data or stratigraphic models can provide average reservoir information with an excellent areal coverage, but with a poor vertical resolution. New advances in modelisation techniques allow now to integrate this type of additional external information in order to constrain the simulations. In particular, 2D or 3D seismic derived information grids, or sand-shale ratios maps coming from stratigraphic models can be used as external drifts to compute the geological image of the reservoir at the fine scale. Examples are presented to illustrate the use of these new tools, their impact on the final reservoir model, and their sensitivity to some key parameters.

  17. Inhibition of Ostwald ripening in model beverage emulsions by addition of poorly water soluble triglyceride oils.

    PubMed

    McClements, David Julian; Henson, Lulu; Popplewell, L Michael; Decker, Eric Andrew; Choi, Seung Jun

    2012-01-01

    Beverage emulsions containing flavor oils that have a relatively high water-solubility are unstable to droplet growth due to Ostwald ripening. The aim of this study was to improve the stability of model beverage emulsions to this kind of droplet growth by incorporating poorly water-soluble triglyceride oils. High pressure homogenization was used to prepare a series of 5 wt% oil-in-water emulsions stabilized by modified starch that had different lipid phase compositions (orange oil : corn oil). Emulsions prepared using only orange oil as the lipid phase were highly unstable to droplet growth during storage, which was attributed to Ostwald ripening resulting from the relatively high water-solubility of orange oil. Droplet growth could be effectively inhibited by incorporating ≥ 10% corn oil into the lipid phase prior to homogenization. In addition, creaming was also retarded because the lipid phase density was closer to that of the aqueous phase density. These results illustrate a simple method of improving the physical stability of orange oil emulsions for utilization in the food, beverage, and fragrance industries.

  18. Ultra high molecular weight polyethylene (UHMWPE) model can provide results comparable to cadaveric models.

    PubMed

    Haher, Thomas R; Ottaviano, Danielle; DeFrancis, Jason G; Merola, Andrew; Valdevit, Antonio

    2004-01-01

    The in vitro biomechanical models using a cadaveric spine specimen have long been used in understanding normal and abnormal functions of spines as well as for strength and stability testing of the spine specimen or spinal construct. Little effort has been made to describe the similarities or differences between UHMWPE and cadaveric models. Eight cadaveric lumbar spines were harvested generating six FSU and three corpectomy models. Six UHMWPE blocks were fabricated to form FSU and corpectomy models. All were tested intact, with posterior instrumentation, and with anterior instrumentation consisting of Moss-Miami 4.0 mm stainless steel rods, uni-axial stainless steel screws and DePuy Harm's cages. All models were tested in axial compression. The cadaveric model and UHMPWE model yielded axial stiffness values of comparable magnitude with respect to instrumentation applied using the posterior approach (P>0.05). Under an FSU configuration, only in the case of anterior instrumentation without the addition of a Harm's cage did both the cadaveric and UHMPWE models provide comparable axial stiffness results (P>0.05). While in vitro cadaveric models are considered the gold standard for biomechanical testing of the spine, the data suggests that under specific approaches and surgical models UHMWPE can be used to infer mechanical performance of instrumentation in cadaveric material.

  19. Sparse Additive Ordinary Differential Equations for Dynamic Gene Regulatory Network Modeling.

    PubMed

    Wu, Hulin; Lu, Tao; Xue, Hongqi; Liang, Hua

    2014-04-02

    The gene regulation network (GRN) is a high-dimensional complex system, which can be represented by various mathematical or statistical models. The ordinary differential equation (ODE) model is one of the popular dynamic GRN models. High-dimensional linear ODE models have been proposed to identify GRNs, but with a limitation of the linear regulation effect assumption. In this article, we propose a sparse additive ODE (SA-ODE) model, coupled with ODE estimation methods and adaptive group LASSO techniques, to model dynamic GRNs that could flexibly deal with nonlinear regulation effects. The asymptotic properties of the proposed method are established and simulation studies are performed to validate the proposed approach. An application example for identifying the nonlinear dynamic GRN of T-cell activation is used to illustrate the usefulness of the proposed method.

  20. Sparse Additive Ordinary Differential Equations for Dynamic Gene Regulatory Network Modeling

    PubMed Central

    Wu, Hulin; Lu, Tao; Xue, Hongqi; Liang, Hua

    2014-01-01

    Summary The gene regulation network (GRN) is a high-dimensional complex system, which can be represented by various mathematical or statistical models. The ordinary differential equation (ODE) model is one of the popular dynamic GRN models. High-dimensional linear ODE models have been proposed to identify GRNs, but with a limitation of the linear regulation effect assumption. In this article, we propose a sparse additive ODE (SA-ODE) model, coupled with ODE estimation methods and adaptive group LASSO techniques, to model dynamic GRNs that could flexibly deal with nonlinear regulation effects. The asymptotic properties of the proposed method are established and simulation studies are performed to validate the proposed approach. An application example for identifying the nonlinear dynamic GRN of T-cell activation is used to illustrate the usefulness of the proposed method. PMID:25061254

  1. Assessment of Chinese sturgeon habitat suitability in the Yangtze River (China): Comparison of generalized additive model, data-driven fuzzy logic model, and preference curve model

    NASA Astrophysics Data System (ADS)

    Yi, Yujun; Sun, Jie; Zhang, Shanghong; Yang, Zhifeng

    2016-05-01

    To date, a wide range of models have been applied to evaluate aquatic habitat suitability. In this study, three models, including the expert knowledge-based preference curve model (PCM), data-driven fuzzy logic model (DDFL), and generalized additive model (GAM), are used on a common data set to compare their effectiveness and accuracy. The true skill statistic (TSS) and the area under the receiver operating characteristics curve (AUC) are used to evaluate the accuracy of the three models. The results indicate that the two data-based methods (DDFL and GAM) yield better accuracy than the expert knowledge-based PCM, and the GAM yields the best accuracy. There are minor differences in the suitable ranges of the physical habitat variables obtained from the three models. The hydraulic habitat suitability index (HHSI) calculated by the PCM is the largest, followed by the DDFL and then the GAM. The results illustrate that data-based models can describe habitat suitability more objectively and accurately when there are sufficient data. When field data are lacking, combining expertise with data-based models is recommended. When field data are difficult to obtain, an expert knowledge-based model can be used as a replacement for the data-based methods.

  2. V and V Efforts of Auroral Precipitation Models: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua; Kuznetsova, Masha; Rastaetter, Lutz; Hesse, Michael

    2011-01-01

    Auroral precipitation models have been valuable both in terms of space weather applications and space science research. Yet very limited testing has been performed regarding model performance. A variety of auroral models are available, including empirical models that are parameterized by geomagnetic indices or upstream solar wind conditions, now casting models that are based on satellite observations, or those derived from physics-based, coupled global models. In this presentation, we will show our preliminary results regarding V&V efforts of some of the models.

  3. Parametrically Guided Generalized Additive Models with Application to Mergers and Acquisitions Data.

    PubMed

    Fan, Jianqing; Maity, Arnab; Wang, Yihui; Wu, Yichao

    2013-01-01

    Generalized nonparametric additive models present a flexible way to evaluate the effects of several covariates on a general outcome of interest via a link function. In this modeling framework, one assumes that the effect of each of the covariates is nonparametric and additive. However, in practice, often there is prior information available about the shape of the regression functions, possibly from pilot studies or exploratory analysis. In this paper, we consider such situations and propose an estimation procedure where the prior information is used as a parametric guide to fit the additive model. Specifically, we first posit a parametric family for each of the regression functions using the prior information (parametric guides). After removing these parametric trends, we then estimate the remainder of the nonparametric functions using a nonparametric generalized additive model, and form the final estimates by adding back the parametric trend. We investigate the asymptotic properties of the estimates and show that when a good guide is chosen, the asymptotic variance of the estimates can be reduced significantly while keeping the asymptotic variance same as the unguided estimator. We observe the performance of our method via a simulation study and demonstrate our method by applying to a real data set on mergers and acquisitions.

  4. Representational Flexibility and Problem-Solving Ability in Fraction and Decimal Number Addition: A Structural Model

    ERIC Educational Resources Information Center

    Deliyianni, Eleni; Gagatsis, Athanasios; Elia, Iliada; Panaoura, Areti

    2016-01-01

    The aim of this study was to propose and validate a structural model in fraction and decimal number addition, which is founded primarily on a synthesis of major theoretical approaches in the field of representations in Mathematics and also on previous research on the learning of fractions and decimals. The study was conducted among 1,701 primary…

  5. Measuring Children's Proportional Reasoning, The "Tendency" for an Additive Strategy and The Effect of Models

    ERIC Educational Resources Information Center

    Misailadou, Christina; Williams, Julian

    2003-01-01

    We report a study of 10-14 year old children's use of additive strategies while solving ratio and proportion tasks. Rasch methodology was used to develop a diagnostic instrument that reveals children's misconceptions. Two versions of this instrument, one with "models" thought to facilitate proportional reasoning and one without were…

  6. Parametrically Guided Generalized Additive Models with Application to Mergers and Acquisitions Data

    PubMed Central

    Fan, Jianqing; Maity, Arnab; Wang, Yihui; Wu, Yichao

    2012-01-01

    Generalized nonparametric additive models present a flexible way to evaluate the effects of several covariates on a general outcome of interest via a link function. In this modeling framework, one assumes that the effect of each of the covariates is nonparametric and additive. However, in practice, often there is prior information available about the shape of the regression functions, possibly from pilot studies or exploratory analysis. In this paper, we consider such situations and propose an estimation procedure where the prior information is used as a parametric guide to fit the additive model. Specifically, we first posit a parametric family for each of the regression functions using the prior information (parametric guides). After removing these parametric trends, we then estimate the remainder of the nonparametric functions using a nonparametric generalized additive model, and form the final estimates by adding back the parametric trend. We investigate the asymptotic properties of the estimates and show that when a good guide is chosen, the asymptotic variance of the estimates can be reduced significantly while keeping the asymptotic variance same as the unguided estimator. We observe the performance of our method via a simulation study and demonstrate our method by applying to a real data set on mergers and acquisitions. PMID:23645976

  7. Strengthen forensic entomology in court--the need for data exploration and the validation of a generalised additive mixed model.

    PubMed

    Baqué, Michèle; Amendt, Jens

    2013-01-01

    Developmental data of juvenile blow flies (Diptera: Calliphoridae) are typically used to calculate the age of immature stages found on or around a corpse and thus to estimate a minimum post-mortem interval (PMI(min)). However, many of those data sets don't take into account that immature blow flies grow in a non-linear fashion. Linear models do not supply a sufficient reliability on age estimates and may even lead to an erroneous determination of the PMI(min). According to the Daubert standard and the need for improvements in forensic science, new statistic tools like smoothing methods and mixed models allow the modelling of non-linear relationships and expand the field of statistical analyses. The present study introduces into the background and application of these statistical techniques by analysing a model which describes the development of the forensically important blow fly Calliphora vicina at different temperatures. The comparison of three statistical methods (linear regression, generalised additive modelling and generalised additive mixed modelling) clearly demonstrates that only the latter provided regression parameters that reflect the data adequately. We focus explicitly on both the exploration of the data--to assure their quality and to show the importance of checking it carefully prior to conducting the statistical tests--and the validation of the resulting models. Hence, we present a common method for evaluating and testing forensic entomological data sets by using for the first time generalised additive mixed models.

  8. Numerical Results of 3-D Modeling of Moon Accumulation

    NASA Astrophysics Data System (ADS)

    Khachay, Yurie; Anfilogov, Vsevolod; Antipin, Alexandr

    2014-05-01

    For the last time for the model of the Moon usually had been used the model of mega impact in which the forming of the Earth and its sputnik had been the consequence of the Earth's collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,2] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al26,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone and additionally change the content of Moon forming to silicates. Only after the increasing of the gravitational radius of the Earth, the growing area of the future Earth's core can save also the silicate envelope fragments [3]. For understanding the further system Earth-Moon evolution it is significant to trace the origin and evolution of heterogeneities, which occur on its accumulation stage.In that paper we are modeling the changing of temperature,pressure,velocity of matter flowing in a block of 3d spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach.The numerical algorithm of the problem solution in velocity

  9. Formation and reduction of carcinogenic furan in various model systems containing food additives.

    PubMed

    Kim, Jin-Sil; Her, Jae-Young; Lee, Kwang-Geun

    2015-12-15

    The aim of this study was to analyse and reduce furan in various model systems. Furan model systems consisting of monosaccharides (0.5M glucose and ribose), amino acids (0.5M alanine and serine) and/or 1.0M ascorbic acid were heated at 121°C for 25 min. The effects of food additives (each 0.1M) such as metal ions (iron sulphate, magnesium sulphate, zinc sulphate and calcium sulphate), antioxidants (BHT and BHA), and sodium sulphite on the formation of furan were measured. The level of furan formed in the model systems was 6.8-527.3 ng/ml. The level of furan in the model systems of glucose/serine and glucose/alanine increased 7-674% when food additives were added. In contrast, the level of furan decreased by 18-51% in the Maillard reaction model systems that included ribose and alanine/serine with food additives except zinc sulphate.

  10. Modeling Longitudinal Data with Generalized Additive Models: Applications to Single-Case Designs

    ERIC Educational Resources Information Center

    Sullivan, Kristynn J.; Shadish, William R.

    2013-01-01

    Single case designs (SCDs) are short time series that assess intervention effects by measuring units repeatedly over time both in the presence and absence of treatment. For a variety of reasons, interest in the statistical analysis and meta-analysis of these designs has been growing in recent years. This paper proposes modeling SCD data with…

  11. Methods of experimentation with models and utilization of results

    NASA Technical Reports Server (NTRS)

    Robert,

    1924-01-01

    The present report treats the subject of testing small models in a wind tunnel and of the methods employed for rendering the results constant, accurate and comparable with one another. Detailed experimental results are given.

  12. Using additive modelling to quantify the effect of chemicals on phytoplankton diversity and biomass.

    PubMed

    Viaene, K P J; De Laender, F; Van den Brink, P J; Janssen, C R

    2013-04-01

    Environmental authorities require the protection of biodiversity and other ecosystem properties such as biomass production. However, the endpoints listed in available ecotoxicological datasets generally do not contain these two ecosystem descriptors. Inferring the effects of chemicals on such descriptors from micro- or mesocosm experiments is often hampered by inherent differences in the initial biodiversity levels between experimental units or by delayed community responses. Here we introduce additive modelling to establish the effects of a chronic application of the herbicide linuron on 10 biodiversity indices and phytoplankton biomass in microcosms. We found that communities with a low (high) initial biodiversity subsequently became more (less) diverse, indicating an equilibrium biodiversity status in the communities considered here. Linuron adversely affected richness and evenness while dominance increased but no biodiversity indices were different from the control treatment at linuron concentrations below 2.4 μg/L. Richness-related indices changed at lower linuron concentrations (effects noticeable from 2.4 μg/L) than other biodiversity indices (effects noticeable from 14.4 μg/L) and, in contrast to the other indices, showed no signs of recovery following chronic exposure. Phytoplankton biomass was unaffected by linuron due to functional redundancy within the phytoplankton community. Comparing thresholds for biodiversity with conventional toxicity test results showed that standard ecological risk assessments also protect biodiversity in the case of linuron.

  13. Influence of the heterogeneous reaction HCl + HOCl on an ozone hole model with hydrocarbon additions

    NASA Astrophysics Data System (ADS)

    Elliott, Scott; Cicerone, Ralph J.; Turco, Richard P.; Drdla, Katja; Tabazadeh, Azadeh

    1994-02-01

    Injection of ethane or propane has been suggested as a means for reducing ozone loss within the Antarctic vortex because alkanes can convert active chlorine radicals into hydrochloric acid. In kinetic models of vortex chemistry including as heterogeneous processes only the hydrolysis and HCl reactions of ClONO2 and N2O5, parts per billion by volume levels of the light alkanes counteract ozone depletion by sequestering chlorine atoms. Introduction of the surface reaction of HCl with HOCl causes ethane to deepen baseline ozone holes and generally works to impede any mitigation by hydrocarbons. The increased depletion occurs because HCl + HOCl can be driven by HOx radicals released during organic oxidation. Following initial hydrogen abstraction by chlorine, alkane breakdown leads to a net hydrochloric acid activation as the remaining hydrogen atoms enter the photochemical system. Lowering the rate constant for reactions of organic peroxy radicals with ClO to 10-13 cm3 molecule-1 s-1 does not alter results, and the major conclusions are insensitive to the timing of the ethane additions. Ignoring the organic peroxy radical plus ClO reactions entirely restores remediation capabilities by allowing HOx removal independent of HCl. Remediation also returns if early evaporation of polar stratospheric clouds leaves hydrogen atoms trapped in aldehyde intermediates, but real ozone losses are small in such cases.

  14. Regression analysis of mixed recurrent-event and panel-count data with additive rate models.

    PubMed

    Zhu, Liang; Zhao, Hui; Sun, Jianguo; Leisenring, Wendy; Robison, Leslie L

    2015-03-01

    Event-history studies of recurrent events are often conducted in fields such as demography, epidemiology, medicine, and social sciences (Cook and Lawless, 2007, The Statistical Analysis of Recurrent Events. New York: Springer-Verlag; Zhao et al., 2011, Test 20, 1-42). For such analysis, two types of data have been extensively investigated: recurrent-event data and panel-count data. However, in practice, one may face a third type of data, mixed recurrent-event and panel-count data or mixed event-history data. Such data occur if some study subjects are monitored or observed continuously and thus provide recurrent-event data, while the others are observed only at discrete times and hence give only panel-count data. A more general situation is that each subject is observed continuously over certain time periods but only at discrete times over other time periods. There exists little literature on the analysis of such mixed data except that published by Zhu et al. (2013, Statistics in Medicine 32, 1954-1963). In this article, we consider the regression analysis of mixed data using the additive rate model and develop some estimating equation-based approaches to estimate the regression parameters of interest. Both finite sample and asymptotic properties of the resulting estimators are established, and the numerical studies suggest that the proposed methodology works well for practical situations. The approach is applied to a Childhood Cancer Survivor Study that motivated this study.

  15. Enhancement of colour stability of anthocyanins in model beverages by gum arabic addition.

    PubMed

    Chung, Cheryl; Rojanasasithara, Thananunt; Mutilangi, William; McClements, David Julian

    2016-06-15

    This study investigated the potential of gum arabic to improve the stability of anthocyanins that are used in commercial beverages as natural colourants. The degradation of purple carrot anthocyanin in model beverage systems (pH 3.0) containing L-ascorbic acid proceeded with a first-order reaction rate during storage (40 °C for 5 days in light). The addition of gum arabic (0.05-5.0%) significantly enhanced the colour stability of anthocyanin, with the most stable systems observed at intermediate levels (1.5%). A further increase in concentration (>1.5%) reduced its efficacy due to a change in the conformation of the gum arabic molecules that hindered their exposure to the anthocyanins. Fluorescence quenching measurements showed that the anthocyanin could have interacted with the glycoprotein fractions of the gum arabic through hydrogen bonding, resulting in enhanced stability. Overall, this study provides valuable information about enhancing the stability of anthocyanins in beverage systems using natural ingredients.

  16. The Effect of Bathymetric Filtering on Nearshore Process Model Results

    DTIC Science & Technology

    2009-01-01

    Filtering on Nearshore Process Model Results 6. AUTHOR(S) Nathaniel Plant, Kacey L. Edwards, James M. Kaihatu, Jayaram Veeramony, Yuan-Huang L. Hsu...filtering on nearshore process model results Nathaniel G. Plant **, Kacey L Edwardsb, James M. Kaihatuc, Jayaram Veeramony b, Larry Hsu’’, K. Todd Holland...assimilation efforts that require this information. Published by Elsevier B.V. 1. Introduction Nearshore process models are capable of predicting

  17. Goodness-of-fit methods for additive-risk models in tumorigenicity experiments.

    PubMed

    Ghosh, Debashis

    2003-09-01

    In tumorigenicity experiments, a complication is that the time to event is generally not observed, so that the time to tumor is subject to interval censoring. One of the goals in these studies is to properly model the effect of dose on risk. Thus, it is important to have goodness of fit procedures available for assessing the model fit. While several estimation procedures have been developed for current-status data, relatively little work has been done on model-checking techniques. In this article, we propose numerical and graphical methods for the analysis of current-status data using the additive-risk model, primarily focusing on the situation where the monitoring times are dependent. The finite-sample properties of the proposed methodology are examined through numerical studies. The methods are then illustrated with data from a tumorigenicity experiment.

  18. Generalized Additive Mixed-Models for Pharmacology Using Integrated Discrete Multiple Organ Co-Culture.

    PubMed

    Ingersoll, Thomas; Cole, Stephanie; Madren-Whalley, Janna; Booker, Lamont; Dorsey, Russell; Li, Albert; Salem, Harry

    2016-01-01

    Integrated Discrete Multiple Organ Co-culture (IDMOC) is emerging as an in-vitro alternative to in-vivo animal models for pharmacology studies. IDMOC allows dose-response relationships to be investigated at the tissue and organoid levels, yet, these relationships often exhibit responses that are far more complex than the binary responses often measured in whole animals. To accommodate departure from binary endpoints, IDMOC requires an expansion of analytic techniques beyond simple linear probit and logistic models familiar in toxicology. IDMOC dose-responses may be measured at continuous scales, exhibit significant non-linearity such as local maxima or minima, and may include non-independent measures. Generalized additive mixed-modeling (GAMM) provides an alternative description of dose-response that relaxes assumptions of independence and linearity. We compared GAMMs to traditional linear models for describing dose-response in IDMOC pharmacology studies.

  19. Generalized Additive Mixed-Models for Pharmacology Using Integrated Discrete Multiple Organ Co-Culture

    PubMed Central

    Ingersoll, Thomas; Cole, Stephanie; Madren-Whalley, Janna; Booker, Lamont; Dorsey, Russell; Li, Albert; Salem, Harry

    2016-01-01

    Integrated Discrete Multiple Organ Co-culture (IDMOC) is emerging as an in-vitro alternative to in-vivo animal models for pharmacology studies. IDMOC allows dose-response relationships to be investigated at the tissue and organoid levels, yet, these relationships often exhibit responses that are far more complex than the binary responses often measured in whole animals. To accommodate departure from binary endpoints, IDMOC requires an expansion of analytic techniques beyond simple linear probit and logistic models familiar in toxicology. IDMOC dose-responses may be measured at continuous scales, exhibit significant non-linearity such as local maxima or minima, and may include non-independent measures. Generalized additive mixed-modeling (GAMM) provides an alternative description of dose-response that relaxes assumptions of independence and linearity. We compared GAMMs to traditional linear models for describing dose-response in IDMOC pharmacology studies. PMID:27110941

  20. Identifiability Results for Several Classes of Linear Compartment Models.

    PubMed

    Meshkat, Nicolette; Sullivant, Seth; Eisenberg, Marisa

    2015-08-01

    Identifiability concerns finding which unknown parameters of a model can be estimated, uniquely or otherwise, from given input-output data. If some subset of the parameters of a model cannot be determined given input-output data, then we say the model is unidentifiable. In this work, we study linear compartment models, which are a class of biological models commonly used in pharmacokinetics, physiology, and ecology. In past work, we used commutative algebra and graph theory to identify a class of linear compartment models that we call identifiable cycle models, which are unidentifiable but have the simplest possible identifiable functions (so-called monomial cycles). Here we show how to modify identifiable cycle models by adding inputs, adding outputs, or removing leaks, in such a way that we obtain an identifiable model. We also prove a constructive result on how to combine identifiable models, each corresponding to strongly connected graphs, into a larger identifiable model. We apply these theoretical results to several real-world biological models from physiology, cell biology, and ecology.

  1. Describing long-term trends in precipitation using generalized additive models

    NASA Astrophysics Data System (ADS)

    Underwood, Fiona M.

    2009-01-01

    SummaryWith the current concern over climate change, descriptions of how rainfall patterns are changing over time can be useful. Observations of daily rainfall data over the last few decades provide information on these trends. Generalized linear models are typically used to model patterns in the occurrence and intensity of rainfall. These models describe rainfall patterns for an average year but are more limited when describing long-term trends, particularly when these are potentially non-linear. Generalized additive models (GAMs) provide a framework for modelling non-linear relationships by fitting smooth functions to the data. This paper describes how GAMs can extend the flexibility of models to describe seasonal patterns and long-term trends in the occurrence and intensity of daily rainfall using data from Mauritius from 1962 to 2001. Smoothed estimates from the models provide useful graphical descriptions of changing rainfall patterns over the last 40 years at this location. GAMs are particularly helpful when exploring non-linear relationships in the data. Care is needed to ensure the choice of smooth functions is appropriate for the data and modelling objectives.

  2. Multi-spectroscopic and molecular modeling studies of bovine serum albumin interaction with sodium acetate food additive.

    PubMed

    Mohammadzadeh-Aghdash, Hossein; Ezzati Nazhad Dolatabadi, Jafar; Dehghan, Parvin; Panahi-Azar, Vahid; Barzegar, Abolfazl

    2017-08-01

    Sodium acetate (SA) has been used as a highly effective protectant in food industry and the possible effect of this additive on the binding to albumin should be taken into consideration. Therefore, for the first time, the mechanism of SA interaction with bovine serum albumin (BSA) has been investigated by multi-spectroscopic and molecular modeling methods under physiological conditions. Stern-Volmer fluorescence quenching analysis showed an increase in the fluorescence intensity of BSA upon increasing the amounts of SA. The high affinity of SA to BSA was demonstrated by a binding constant value (1.09×10(3) at 310°K). The thermodynamic parameters indicated that hydrophobic binding plays a main role in the binding of SA to Albumin. Furthermore, the results of UV-vis spectra confirmed the interaction of this additive to BSA. In addition, molecular modeling study demonstrated that A binding sites of BSA play the main role in the interaction with acetate.

  3. Addition of a 5/cm Spectral Resolution Band Model Option to LOWTRAN5.

    DTIC Science & Technology

    1980-10-01

    FORM I. REPORT NUMBER .GOVT ACCESSION NO. 3 . RECIPIENT’S CATALCI UMISER ARI-RR-232 -9 1 0. T Ct IIIM INNY S TYPE OF REPORT & PERIOD COVERED I ddition of...5r/TPAN (2) the addition of temperature dependent ecular absorption coefficients,’ and ( 3 ) the use of a multi-parameter, Dp 71pForentz band model for...LOWTRA.I5 and LOWTRAN5(IMOD) ..... 2-10 2.8 Comparison of LOWTRAN5 Models to Measurements 2-16 3 . MODIFICATIONS TO LOWTRAN5

  4. Results from a new Cocks-Ashby style porosity model

    NASA Astrophysics Data System (ADS)

    Barton, Nathan

    2017-01-01

    A new porosity evolution model is described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution are shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations.

  5. Tree Biomass Allocation and Its Model Additivity for Casuarina equisetifolia in a Tropical Forest of Hainan Island, China

    PubMed Central

    Xue, Yang; Yang, Zhongyang; Wang, Xiaoyan; Lin, Zhipan; Li, Dunxi; Su, Shaofeng

    2016-01-01

    Casuarina equisetifolia is commonly planted and used in the construction of coastal shelterbelt protection in Hainan Island. Thus, it is critical to accurately estimate the tree biomass of Casuarina equisetifolia L. for forest managers to evaluate the biomass stock in Hainan. The data for this work consisted of 72 trees, which were divided into three age groups: young forest, middle-aged forest, and mature forest. The proportion of biomass from the trunk significantly increased with age (P<0.05). However, the biomass of the branch and leaf decreased, and the biomass of the root did not change. To test whether the crown radius (CR) can improve biomass estimates of C. equisetifolia, we introduced CR into the biomass models. Here, six models were used to estimate the biomass of each component, including the trunk, the branch, the leaf, and the root. In each group, we selected one model among these six models for each component. The results showed that including the CR greatly improved the model performance and reduced the error, especially for the young and mature forests. In addition, to ensure biomass additivity, the selected equation for each component was fitted as a system of equations using seemingly unrelated regression (SUR). The SUR method not only gave efficient and accurate estimates but also achieved the logical additivity. The results in this study provide a robust estimation of tree biomass components and total biomass over three groups of C. equisetifolia. PMID:27002822

  6. Tree Biomass Allocation and Its Model Additivity for Casuarina equisetifolia in a Tropical Forest of Hainan Island, China.

    PubMed

    Xue, Yang; Yang, Zhongyang; Wang, Xiaoyan; Lin, Zhipan; Li, Dunxi; Su, Shaofeng

    2016-01-01

    Casuarina equisetifolia is commonly planted and used in the construction of coastal shelterbelt protection in Hainan Island. Thus, it is critical to accurately estimate the tree biomass of Casuarina equisetifolia L. for forest managers to evaluate the biomass stock in Hainan. The data for this work consisted of 72 trees, which were divided into three age groups: young forest, middle-aged forest, and mature forest. The proportion of biomass from the trunk significantly increased with age (P<0.05). However, the biomass of the branch and leaf decreased, and the biomass of the root did not change. To test whether the crown radius (CR) can improve biomass estimates of C. equisetifolia, we introduced CR into the biomass models. Here, six models were used to estimate the biomass of each component, including the trunk, the branch, the leaf, and the root. In each group, we selected one model among these six models for each component. The results showed that including the CR greatly improved the model performance and reduced the error, especially for the young and mature forests. In addition, to ensure biomass additivity, the selected equation for each component was fitted as a system of equations using seemingly unrelated regression (SUR). The SUR method not only gave efficient and accurate estimates but also achieved the logical additivity. The results in this study provide a robust estimation of tree biomass components and total biomass over three groups of C. equisetifolia.

  7. Argonne Fuel Cycle Facility ventilation system -- modeling and results

    SciTech Connect

    Mohr, D.; Feldman, E.E.; Danielson, W.F.

    1995-02-01

    This paper describes an integrated study of the Argonne-West Fuel Cycle Facility (FCF) interconnected ventilation systems during various operations. Analyses and test results include first a nominal condition reflecting balanced pressures and flows followed by several infrequent and off-normal scenarios. This effort is the first study of the FCF ventilation systems as an integrated network wherein the hydraulic effects of all major air systems have been analyzed and tested. The FCF building consists of many interconnected regions in which nuclear fuel is handled, transported and reprocessed. The ventilation systems comprise a large number of ducts, fans, dampers, and filters which together must provide clean, properly conditioned air to the worker occupied spaces of the facility while preventing the spread of airborne radioactive materials to clean am-as or the atmosphere. This objective is achieved by keeping the FCF building at a partial vacuum in which the contaminated areas are kept at lower pressures than the other worker occupied spaces. The ventilation systems of FCF and the EBR-II reactor are analyzed as an integrated totality, as demonstrated. We then developed the network model shown in Fig. 2 for the TORAC code. The scope of this study was to assess the measured results from the acceptance/flow balancing testing and to predict the effects of power failures, hatch and door openings, single-failure faulted conditions, EBR-II isolation, and other infrequent operations. The studies show that the FCF ventilation systems am very controllable and remain stable following off-normal events. In addition, the FCF ventilation system complex is essentially immune to reverse flows and spread of contamination to clean areas during normal and off-normal operation.

  8. Rain water transport and storage in a model sandy soil with hydrogel particle additives.

    PubMed

    Wei, Y; Durian, D J

    2014-10-01

    We study rain water infiltration and drainage in a dry model sandy soil with superabsorbent hydrogel particle additives by measuring the mass of retained water for non-ponding rainfall using a self-built 3D laboratory set-up. In the pure model sandy soil, the retained water curve measurements indicate that instead of a stable horizontal wetting front that grows downward uniformly, a narrow fingered flow forms under the top layer of water-saturated soil. This rain water channelization phenomenon not only further reduces the available rain water in the plant root zone, but also affects the efficiency of soil additives, such as superabsorbent hydrogel particles. Our studies show that the shape of the retained water curve for a soil packing with hydrogel particle additives strongly depends on the location and the concentration of the hydrogel particles in the model sandy soil. By carefully choosing the particle size and distribution methods, we may use the swollen hydrogel particles to modify the soil pore structure, to clog or extend the water channels in sandy soils, or to build water reservoirs in the plant root zone.

  9. Effect of Hydrogen Addition on Methane HCCI Engine Ignition Timing and Emissions Using a Multi-zone Model

    NASA Astrophysics Data System (ADS)

    Wang, Zi-han; Wang, Chun-mei; Tang, Hua-xin; Zuo, Cheng-ji; Xu, Hong-ming

    2009-06-01

    Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition timing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its application, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NOx while decreasing HC and CO emissions. Exhaust gas recirculation (EGR) also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NOx is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.

  10. Cryptosporidium Infection Risk: Results of New Dose-Response Modeling.

    PubMed

    Messner, Michael J; Berger, Philip

    2016-10-01

    Cryptosporidium human dose-response data from seven species/isolates are used to investigate six models of varying complexity that estimate infection probability as a function of dose. Previous models attempt to explicitly account for virulence differences among C. parvum isolates, using three or six species/isolates. Four (two new) models assume species/isolate differences are insignificant and three of these (all but exponential) allow for variable human susceptibility. These three human-focused models (fractional Poisson, exponential with immunity and beta-Poisson) are relatively simple yet fit the data significantly better than the more complex isolate-focused models. Among these three, the one-parameter fractional Poisson model is the simplest but assumes that all Cryptosporidium oocysts used in the studies were capable of initiating infection. The exponential with immunity model does not require such an assumption and includes the fractional Poisson as a special case. The fractional Poisson model is an upper bound of the exponential with immunity model and applies when all oocysts are capable of initiating infection. The beta Poisson model does not allow an immune human subpopulation; thus infection probability approaches 100% as dose becomes huge. All three of these models predict significantly (>10x) greater risk at the low doses that consumers might receive if exposed through drinking water or other environmental exposure (e.g., 72% vs. 4% infection probability for a one oocyst dose) than previously predicted. This new insight into Cryptosporidium risk suggests additional inactivation and removal via treatment may be needed to meet any specified risk target, such as a suggested 10(-4) annual risk of Cryptosporidium infection.

  11. Spectral prediction model for color prints on paper with fluorescent additives.

    PubMed

    Hersch, Roger David

    2008-12-20

    I propose a model for predicting the total reflectance of color halftones printed on paper incorporating fluorescent brighteners. The total reflectance is modeled as the additive superposition of the relative fluorescent emission and the pure reflectance of the color print. The fluorescent emission prediction model accounts for both the attenuation of light by the halftone within the excitation wavelength range and for the attenuation of the fluorescent emission by the same halftone within the emission wavelength range. The model's calibration relies on reflectance measurements of the optically brightened paper and of the solid colorant patches with two illuminants, one including and one excluding the UV components. The part of the model predicting the pure reflectance relies on an ink-spreading extended Clapper-Yule model. On uniformly distributed surface coverages of cyan, magenta, and yellow halftone patches, the proposed model predicts the relative fluorescent emission with a high accuracy (mean DeltaE(94)=0.42 under a D65 standard illuminant). For optically brightened paper exhibiting a moderate fluorescence, the total reflectance prediction improves the spectral reflectance prediction mainly for highlight color halftones, comprising a proportion of paper white above 12%. Applications include the creation of improved printer characterization tables for color management purposes and the prediction of color gamuts for new combinations of optically brightened papers and inks.

  12. Generalized linear and generalized additive models in studies of species distributions: Setting the scene

    USGS Publications Warehouse

    Guisan, A.; Edwards, T.C.; Hastie, T.

    2002-01-01

    An important statistical development of the last 30 years has been the advance in regression analysis provided by generalized linear models (GLMs) and generalized additive models (GAMs). Here we introduce a series of papers prepared within the framework of an international workshop entitled: Advances in GLMs/GAMs modeling: from species distribution to environmental management, held in Riederalp, Switzerland, 6-11 August 2001. We first discuss some general uses of statistical models in ecology, as well as provide a short review of several key examples of the use of GLMs and GAMs in ecological modeling efforts. We next present an overview of GLMs and GAMs, and discuss some of their related statistics used for predictor selection, model diagnostics, and evaluation. Included is a discussion of several new approaches applicable to GLMs and GAMs, such as ridge regression, an alternative to stepwise selection of predictors, and methods for the identification of interactions by a combined use of regression trees and several other approaches. We close with an overview of the papers and how we feel they advance our understanding of their application to ecological modeling. ?? 2002 Elsevier Science B.V. All rights reserved.

  13. Model NbTi Helical Solenoid Fabrication and Test Results

    SciTech Connect

    Andreev, N.; Barzi, E.; Chlachidze, G.; Evbota, D.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Makarov, A.; Novitski, I.; Orris, D.F.; Tartaglia, M.A.; /Fermilab

    2011-09-01

    A program to develop model magnets for a helical cooling channel is under way at Fermilab. In the first steps of a planned sequence of magnets, two four-coil helical solenoid models with 300 mm aperture have been fabricated and tested. These two models, HSM01 and HSM02, used insulated NbTi Rutherford cable wound onto stainless steel rings with spliceless transitions between coils. Strip heaters were included for quench protection of each coil, and the coils were epoxy-impregnated after winding inside the support structures. Based on the results of the first model the second model was made using a cable with optimized cross-section, improved winding and epoxy-impregnation procedures, enhanced ground insulation, and included heat exchange tubing for a test of conduction cooling. We report on the results and lessons learned from fabrication and tests of these two models.

  14. Family, Neighborhood, and Peer Characteristics as Predictors of Child Adjustment: A Longitudinal Analysis of Additive and Mediation Models

    PubMed Central

    2008-01-01

    The purpose of this study was to test direct, additive, and mediation models involving family, neighborhood, and peer factors in relation to emerging antisocial behavior and social skills. Neighborhood danger, maternal depressive symptoms, and supportive parenting were assessed in early childhood. Peer group acceptance was measured in middle childhood, and data on antisocial behavior and social skills were collected when boys were 11 and 12 years old. Results were consistent with an additive effects model of child antisocial behavior. In contrast, peer relationships were stronger predictors of social skills than were family factors. Support for mediation was found in models involving neighborhood danger and supportive parenting. However, only peer group acceptance predicted change in antisocial and prosocial behavior. Implications for family and peer relations as socialization contexts are discussed. PMID:20161200

  15. Updated Results for the Wake Vortex Inverse Model

    NASA Technical Reports Server (NTRS)

    Robins, Robert E.; Lai, David Y.; Delisi, Donald P.; Mellman, George R.

    2008-01-01

    NorthWest Research Associates (NWRA) has developed an Inverse Model for inverting aircraft wake vortex data. The objective of the inverse modeling is to obtain estimates of the vortex circulation decay and crosswind vertical profiles, using time history measurements of the lateral and vertical position of aircraft vortices. The Inverse Model performs iterative forward model runs using estimates of vortex parameters, vertical crosswind profiles, and vortex circulation as a function of wake age. Iterations are performed until a user-defined criterion is satisfied. Outputs from an Inverse Model run are the best estimates of the time history of the vortex circulation derived from the observed data, the vertical crosswind profile, and several vortex parameters. The forward model, named SHRAPA, used in this inverse modeling is a modified version of the Shear-APA model, and it is described in Section 2 of this document. Details of the Inverse Model are presented in Section 3. The Inverse Model was applied to lidar-observed vortex data at three airports: FAA acquired data from San Francisco International Airport (SFO) and Denver International Airport (DEN), and NASA acquired data from Memphis International Airport (MEM). The results are compared with observed data. This Inverse Model validation is documented in Section 4. A summary is given in Section 5. A user's guide for the inverse wake vortex model is presented in a separate NorthWest Research Associates technical report (Lai and Delisi, 2007a).

  16. Additional results on palaeomagnetic stratigraphy of the Koobi Fora Formation, east of Lake Turkana (Lake Rudolf), Kenya

    USGS Publications Warehouse

    Hillhouse, J.W.; Ndombi, J.W.M.; Cox, A.; Brock, A.

    1977-01-01

    The magnetostratigraphy of the hominid-bearing sediments exposed east of Lake Turkana has been strengthened by new palaeomagnetic results. Ages obtained from several tuffs by the 40Ar/39Ar method suggest an approxmate match between the observed magnetozones and the geomagnetic polarity time scale; however, the palaeomagnetic results are also compatible with a younger chronology suggested by conventional K-Ar dating of the KBS Tuff. ?? 1977 Nature Publishing Group.

  17. [Some exact results for random walk models with applications].

    PubMed

    Schwarz, W

    1989-01-01

    This article presents a random walk model that can be analyzed without recourse to Wald's (1947) approximation, which neglects the excess over the absorbing barriers. Hence, the model yields exact predictions for the absorption probabilities and all mean conditional absorption times. We derive these predictions in some detail and fit them to the extensive data of an identification experiment published by Green et al. (1983). The fit of the model seems satisfactory. The relationship of the model to existing classes of random walk models (SPRT and SSR; see Luce, 1986) is discussed; for certain combinations of its parameters, the model belongs either to the SPRT or to the SSR class, or to both. We stress the theoretical significance of the knowledge of exact results for the evaluation of Wald's approximation and general properties of the several models proposed derived from this approximation.

  18. Resources allocation in healthcare for cancer: a case study using generalised additive mixed models.

    PubMed

    Musio, Monica; Sauleau, Erik A; Augustin, Nicole H

    2012-11-01

    Our aim is to develop a method for helping resources re-allocation in healthcare linked to cancer, in order to replan the allocation of providers. Ageing of the population has a considerable impact on the use of health resources because aged people require more specialised medical care due notably to cancer. We propose a method useful to monitor changes of cancer incidence in space and time taking into account two age categories, according to healthcar general organisation. We use generalised additive mixed models with a Poisson response, according to the methodology presented in Wood, Generalised additive models: an introduction with R. Chapman and Hall/CRC, 2006. Besides one-dimensional smooth functions accounting for non-linear effects of covariates, the space-time interaction can be modelled using scale invariant smoothers. Incidence data collected by a general cancer registry between 1992 and 2007 in a specific area of France is studied. Our best model exhibits a strong increase of the incidence of cancer along time and an obvious spatial pattern for people more than 70 years with a higher incidence in the central band of the region. This is a strong argument for re-allocating resources for old people cancer care in this sub-region.

  19. Quantum-chemical model evaluations of thermodynamics and kinetics of oxygen atom additions to narrow nanotubes.

    PubMed

    Slanina, Zdenĕk; Stobinski, Leszek; Tomasik, Piotr; Lin, Hong-Ming; Adamowicz, Ludwik

    2003-01-01

    This paper reports a computational study of oxygen additions to narrow nanotubes, a problem frequently studied with fullerenes. In fact, fullerene oxides were the first observed fullerene derivatives, and they have naturally attracted the attention of both experiment and theory. C60O had represented a long-standing case of experiment-theory disagreement, and there has been a similar problem with C60O2. The disagreement has been explained by kinetic rather than thermodynamic control. In this paper a similar computational approach is applied to narrow nanotubes. Recently, very narrow nanotubes have been observed with a diameter of 5 A and even with a diameter of 4 A. It has been supposed that the narrow nanotubes are closed by fragments of small fullerenes like C36 or C20. In this report we perform calculations for oxygen additions to such model nanotubes capped by fragments of D2d C36, D4d C32, and Ih C20 fullerenic cages (though the computational models have to be rather short). The three models have the following carbon contents: C84, C80, and C80. Both thermodynamic enthalpy changes and kinetic activation barriers for oxygen addition to six selected bonds are computed and analyzed. The lowest isomer (thermodynamically the most stable) is never of the 6/6 type, that is, the enthalpically favored structures are produced by oxygen additions to the nanotube tips. Interestingly enough, the lowest energy isomer has, for the D2d C36 and D4d C32 cases, the lowest kinetic activation barrier as well.

  20. Effects of a Tantalum Addition on the Morphological and Compositional Evolutions of a Model Ni-AL-Cr Superalloy

    NASA Technical Reports Server (NTRS)

    Booth-Morrison, Christopher; Seidman, David N.; Noebe, Ronald D.

    2008-01-01

    The effects of a 2.0 at.% addition of Ta to a model Ni-Al-Cr superalloy aged at 1073 K are assessed using scanning electron microscopy and atom-probe tomography. The addition of Ta results in appreciable strengthening, and the morphology is found to evolve from a bimodal distribution of spheroidal precipitates, to cuboidal precipitates aligned along the elastically soft <001>-type directions. Tantalum is observed to partition preferentially to the gamma -precipitate phase and decreases the mobility of Ni in the gamma- matrix sufficiently to cause an accumulation of Ni on the gamma-matrix side of the gamma -precipitate/gamma-matrix heterophase interface.

  1. Estimation of daily aluminum intake in Japan based on food consumption inspection results: impact of food additives

    PubMed Central

    Sato, Kyoko; Suzuki, Ippei; Kubota, Hiroki; Furusho, Noriko; Inoue, Tomoyuki; Yasukouchi, Yoshikazu; Akiyama, Hiroshi

    2014-01-01

    Dietary aluminum (Al) intake by young children, children, youths, and adults in Japan was estimated using the market basket method. The Al content of food category (I–VII) samples for each age group was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The Al content in processed foods and unprocessed foods ranged from 0.40 to 21.7 mg/kg and from 0.32 to 0.54 mg/kg, respectively. For processed foods in all age groups, the Al content in food category VI samples, sugar and confections/savories, was the highest, followed by those in category II, cereals. The daily dietary Al intake from processed foods was much larger than that from unprocessed foods. The mean weekly percentages of the provisional tolerable weekly intake (PTWI, established by the joint FAO/WHO Expert Committee on Food Additives in 2011) from processed foods for all age groups are 43.1, 22.4, 17.6 and 15.1%, respectively. Only the highest consumer Al exposure value (>P95) of the young children group exceeded the PTWI. PMID:25473496

  2. Model Identification in Time-Series Analysis: Some Empirical Results.

    ERIC Educational Resources Information Center

    Padia, William L.

    Model identification of time-series data is essential to valid statistical tests of intervention effects. Model identification is, at best, inexact in the social and behavioral sciences where one is often confronted with small numbers of observations. These problems are discussed, and the results of independent identifications of 130 social and…

  3. Results from modeling and simulation of chemical downstream etch systems

    SciTech Connect

    Meeks, E.; Vosen, S.R.; Shon, J.W.; Larson, R.S.; Fox, C.A.; Buchenauer

    1996-05-01

    This report summarizes modeling work performed at Sandia in support of Chemical Downstream Etch (CDE) benchmark and tool development programs under a Cooperative Research and Development Agreement (CRADA) with SEMATECH. The Chemical Downstream Etch (CDE) Modeling Project supports SEMATECH Joint Development Projects (JDPs) with Matrix Integrated Systems, Applied Materials, and Astex Corporation in the development of new CDE reactors for wafer cleaning and stripping processes. These dry-etch reactors replace wet-etch steps in microelectronics fabrication, enabling compatibility with other process steps and reducing the use of hazardous chemicals. Models were developed at Sandia to simulate the gas flow, chemistry and transport in CDE reactors. These models address the essential components of the CDE system: a microwave source, a transport tube, a showerhead/gas inlet, and a downstream etch chamber. The models have been used in tandem to determine the evolution of reactive species throughout the system, and to make recommendations for process and tool optimization. A significant part of this task has been in the assembly of a reasonable set of chemical rate constants and species data necessary for successful use of the models. Often the kinetic parameters were uncertain or unknown. For this reason, a significant effort was placed on model validation to obtain industry confidence in the model predictions. Data for model validation were obtained from the Sandia Molecular Beam Mass Spectrometry (MBMS) experiments, from the literature, from the CDE Benchmark Project (also part of the Sandia/SEMATECH CRADA), and from the JDP partners. The validated models were used to evaluate process behavior as a function of microwave-source operating parameters, transport-tube geometry, system pressure, and downstream chamber geometry. In addition, quantitative correlations were developed between CDE tool performance and operation set points.

  4. A re-examination of paleomagnetic results from NA Jurassic sedimentary rocks: Additional evidence for proposed Jurassic MUTO?

    NASA Astrophysics Data System (ADS)

    Housen, B. A.

    2015-12-01

    Kent and Irving, 2010; and Kent et al, 2015 propose a monster shift in the position of Jurassic (160 to 145 Ma) paleopoles for North America- defined by results from igneous rocks. This monster shift is likely an unrecognized true polar wander occurrence. Although subject to inclination error, results from sedimentary rocks from North America, if corrected for these effects, can be used to supplement the available data for this time period. Steiner (2003) reported results from 48 stratigraphic horizons sampled from the Callovian Summerville Fm, from NE New Mexico. A recalculated mean of these results yields a mean direction of D = 332, I = 39, n=48, k = 15, α95 = 5.4°. These data were analyzed for possible inclination error-although the dataset is small, the E-I results yielded a corrected I = 53. This yields a corrected paleopole for NA at ~165 Ma located at 67° N and 168° E.Paleomagnetic results from the Black Hills- Kilanowski (2002) for the Callovian Hulett Mbr of the Sundance Fm, and Gregiore (2001) the Oxfordian-Tithonian Morrison Fm (Gregiore, 2001) have previously been interpreted to represent Eocene-aged remagnetizations- due to the nearly exact coincidence between the in-situ pole positions of these Jurassic units with the Eocene pole for NA. Both of the tilt-corrected results for these units have high latitude poles (Sundance Fm: 79° N, 146° E; Morrison Fm: 89° N, 165° E). An E-I analysis of these data will be presented- using a provisional inclination error of 10°, corrected paleopoles are: (Sundance Fm: 76° N, 220° E; Morrison Fm: 77° N, 266° E). The Black Hills 165 Ma (Sundance Fm) and 145 Ma (Morrison Fm) poles, provisionally corrected for 10° inclination error- occur fairly close to the NA APWP proposed by Kent et al, 2015- using an updated set of results from kimberlites- the agreement between the Sundance Fm and the Triple-B (158 Ma) pole would be nearly exact with a slightly lesser inclination error. The Summerville Fm- which is

  5. VNIR spectral modeling of Mars analogue rocks: first results

    NASA Astrophysics Data System (ADS)

    Pompilio, L.; Roush, T.; Pedrazzi, G.; Sgavetti, M.

    a study applying the Modified Gaussian Model [MGM, 13] to solid mafic rock spectral modeling. Reflectance measurements were acquired on rock slabs, rock powder, and mineral separates. The results of spectral modeling were evaluated using compositional data determined from techniques other than reflectance spectroscopy. The rocks studied, melanorite (cumulate analog) and basalt (effusive analog), have different textural characteristics. The modal composition of melanorite includes relatively high opaque content. Opaque minerals strongly affect reflectance 1 spectra of transparent minerals and the criteria for their identification from remotely acquired data are not clearly established. Detailed studies of the melanorite slab spectrum, which includes accounting for the opaque content, can be extended to the basalt spectrum, which must also account for the spectral influence of glass. The spectral analyses reveal the MGM decompositions of solid rock samples can be used to obtain qualitative estimates of the main mineral compositions, for the melanorite, but become more problematic for the basalt. Statistically objective evaluation of the spectral models is complicated by the increased observational error due to the heterogeneity of the rock surfaces relative to mixtures of powders. This suggests additional efforts are required to provide a better understanding regarding the spectral modeling of both laboratory and in-situ measurements of bulk rocks. REFERENCES - [1] Bandfield, J., P. Christensen, and V. Hamilton (2000) Science, 287, 1626-1630. [2] Christensen, P., J. Bandfield, V. Hamilton, and 23 others (2001) J. Geophys. Res.-Planets., 106 (E10), 23823-23871. [3] Wyatt, M. and H. McSween (2002) Nature, 417, 263-266. [4] Hamilton, V. and M. Minitti (2003) Geophys. Res. Lett., 30, PLA 1-1. [5] Bibring, J., Y. Langevin, A. Gendrin, and 9 others (2005) Science, 307, 1576-1581. [6] Mustard, J., F. Poulet, A. Gendrin, and 6 others (2005) Science, 307, 1594-1597. [7] Hapke

  6. Testing departure from additivity in Tukey's model using shrinkage: application to a longitudinal setting.

    PubMed

    Ko, Yi-An; Mukherjee, Bhramar; Smith, Jennifer A; Park, Sung Kyun; Kardia, Sharon L R; Allison, Matthew A; Vokonas, Pantel S; Chen, Jinbo; Diez-Roux, Ana V

    2014-12-20

    While there has been extensive research developing gene-environment interaction (GEI) methods in case-control studies, little attention has been given to sparse and efficient modeling of GEI in longitudinal studies. In a two-way table for GEI with rows and columns as categorical variables, a conventional saturated interaction model involves estimation of a specific parameter for each cell, with constraints ensuring identifiability. The estimates are unbiased but are potentially inefficient because the number of parameters to be estimated can grow quickly with increasing categories of row/column factors. On the other hand, Tukey's one-degree-of-freedom model for non-additivity treats the interaction term as a scaled product of row and column main effects. Because of the parsimonious form of interaction, the interaction estimate leads to enhanced efficiency, and the corresponding test could lead to increased power. Unfortunately, Tukey's model gives biased estimates and low power if the model is misspecified. When screening multiple GEIs where each genetic and environmental marker may exhibit a distinct interaction pattern, a robust estimator for interaction is important for GEI detection. We propose a shrinkage estimator for interaction effects that combines estimates from both Tukey's and saturated interaction models and use the corresponding Wald test for testing interaction in a longitudinal setting. The proposed estimator is robust to misspecification of interaction structure. We illustrate the proposed methods using two longitudinal studies-the Normative Aging Study and the Multi-ethnic Study of Atherosclerosis.

  7. Testing Departure from Additivity in Tukey’s Model using Shrinkage: Application to a Longitudinal Setting

    PubMed Central

    Ko, Yi-An; Mukherjee, Bhramar; Smith, Jennifer A.; Park, Sung Kyun; Kardia, Sharon L.R.; Allison, Matthew A.; Vokonas, Pantel S.; Chen, Jinbo; Diez-Roux, Ana V.

    2014-01-01

    While there has been extensive research developing gene-environment interaction (GEI) methods in case-control studies, little attention has been given to sparse and efficient modeling of GEI in longitudinal studies. In a two-way table for GEI with rows and columns as categorical variables, a conventional saturated interaction model involves estimation of a specific parameter for each cell, with constraints ensuring identifiability. The estimates are unbiased but are potentially inefficient because the number of parameters to be estimated can grow quickly with increasing categories of row/column factors. On the other hand, Tukey’s one degree of freedom (df) model for non-additivity treats the interaction term as a scaled product of row and column main effects. Due to the parsimonious form of interaction, the interaction estimate leads to enhanced efficiency and the corresponding test could lead to increased power. Unfortunately, Tukey’s model gives biased estimates and low power if the model is misspecified. When screening multiple GEIs where each genetic and environmental marker may exhibit a distinct interaction pattern, a robust estimator for interaction is important for GEI detection. We propose a shrinkage estimator for interaction effects that combines estimates from both Tukey’s and saturated interaction models and use the corresponding Wald test for testing interaction in a longitudinal setting. The proposed estimator is robust to misspecification of interaction structure. We illustrate the proposed methods using two longitudinal studies — the Normative Aging Study and the Multi-Ethnic Study of Atherosclerosis. PMID:25112650

  8. Aerosol kinetic code "AERFORM": Model, validation and simulation results

    NASA Astrophysics Data System (ADS)

    Gainullin, K. G.; Golubev, A. I.; Petrov, A. M.; Piskunov, V. N.

    2016-06-01

    The aerosol kinetic code "AERFORM" is modified to simulate droplet and ice particle formation in mixed clouds. The splitting method is used to calculate condensation and coagulation simultaneously. The method is calibrated with analytic solutions of kinetic equations. Condensation kinetic model is based on cloud particle growth equation, mass and heat balance equations. The coagulation kinetic model includes Brownian, turbulent and precipitation effects. The real values are used for condensation and coagulation growth of water droplets and ice particles. The model and the simulation results for two full-scale cloud experiments are presented. The simulation model and code may be used autonomously or as an element of another code.

  9. Reduction of carcinogenic 4(5)-methylimidazole in a caramel model system: influence of food additives.

    PubMed

    Seo, Seulgi; Ka, Mi-Hyun; Lee, Kwang-Geun

    2014-07-09

    The effect of various food additives on the formation of carcinogenic 4(5)-methylimidazole (4-MI) in a caramel model system was investigated. The relationship between the levels of 4-MI and various pyrazines was studied. When glucose and ammonium hydroxide were heated, the amount of 4-MI was 556 ± 1.3 μg/mL, which increased to 583 ± 2.6 μg/mL by the addition of 0.1 M of sodium sulfite. When various food additives, such as 0.1 M of iron sulfate, magnesium sulfate, zinc sulfate, tryptophan, and cysteine were added, the amount of 4-MI was reduced to 110 ± 0.7, 483 ± 2.0, 460 ± 2.0, 409 ± 4.4, and 397 ± 1.7 μg/mL, respectively. The greatest reduction, 80%, occurred with the addition of iron sulfate. Among the 12 pyrazines, 2-ethyl-6-methylpyrazine with 4-MI showed the highest correlation (r = -0.8239).

  10. Developing Operation Plans from HEC Prescriptive Reservoir Model Results for the Missouri River System: Preliminary Results

    DTIC Science & Technology

    1992-03-01

    reservoir simulation model was undertaken using the same initial storages and inflows employed in the 92-year HEC-PRM application. The results of this run...by HEC-PRM results is likely to be as a point of departure for more traditional and intensive reservoir simulation studies. A major contribution of...may be desirable to create an elementary reservoir simulation package incorporating a flexible set of rule forms that could employ and display the HEC

  11. A Comparison Between The NORCAT Rover Test Results and the ISRU Excavation System Model Predictions Results

    NASA Technical Reports Server (NTRS)

    Gallo, Christopher A.; Agui, Juan H.; Creager, Colin M.; Oravec, Heather A.

    2012-01-01

    An Excavation System Model has been written to simulate the collection and transportation of regolith on the moon. The calculations in this model include an estimation of the forces on the digging tool as a result of excavation into the regolith. Verification testing has been performed and the forces recorded from this testing were compared to the calculated theoretical data. The Northern Centre for Advanced Technology Inc. rovers were tested at the NASA Glenn Research Center Simulated Lunar Operations facility. This testing was in support of the In-Situ Resource Utilization program Innovative Partnership Program. Testing occurred in soils developed at the Glenn Research Center which are a mixture of different types of sands and whose soil properties have been well characterized. This testing is part of an ongoing correlation of actual field test data to the blade forces calculated by the Excavation System Model. The results from this series of tests compared reasonably with the predicted values from the code.

  12. Mechanisms and modeling of the effects of additives on the nitrogen oxides emission

    NASA Technical Reports Server (NTRS)

    Kundu, Krishna P.; Nguyen, Hung Lee; Kang, M. Paul

    1991-01-01

    A theoretical study on the emission of the oxides of nitrogen in the combustion of hydrocarbons is presented. The current understanding of the mechanisms and the rate parameters for gas phase reactions were used to calculate the NO(x) emission. The possible effects of different chemical species on thermal NO(x), on a long time scale were discussed. The mixing of these additives at various stages of combustion were considered and NO(x) concentrations were calculated; effects of temperatures were also considered. The chemicals such as hydrocarbons, H2, CH3OH, NH3, and other nitrogen species were chosen as additives in this discussion. Results of these calculations can be used to evaluate the effects of these additives on the NO(x) emission in the industrial combustion system.

  13. High SO{sub 2} removal efficiency testing: Results of DBA and sodium formate additive tests at Southwestern Electric Power company`s Pirkey Station

    SciTech Connect

    1996-05-30

    Tests were conducted at Southwestern Electric Power Company`s (SWEPCo) Henry W. Pirkey Station wet limestone flue gas desulfurization (FGD) system to evaluate options for achieving high sulfur dioxide removal efficiency. The Pirkey FGD system includes four absorber modules, each with dual slurry recirculation loops and with a perforated plate tray in the upper loop. The options tested involved the use of dibasic acid (DBA) or sodium formate as a performance additive. The effectiveness of other potential options was simulated with the Electric Power Research Institute`s (EPRI) FGD PRocess Integration and Simulation Model (FGDPRISM) after it was calibrated to the system. An economic analysis was done to determine the cost effectiveness of the high-efficiency options. Results are-summarized below.

  14. Present research results and communicate the modeling results to science community

    EPA Science Inventory

    Background/Objectives. As a result of subsurface heterogeneity, many field and laboratory studies indicate that the advection-dispersion equation (ADE) model fails to describe the frequently observed long tails of contaminant concentration versus time in a breakthrough curve. T...

  15. Perchloroethylene-contaminated drinking water and the risk of breast cancer: additional results from Cape Cod, Massachusetts, USA.

    PubMed Central

    Aschengrau, Ann; Rogers, Sarah; Ozonoff, David

    2003-01-01

    In 1998 we published the results of a study suggesting an association between breast cancer and perchloroethylene (PCE; also called tetrachloroethylene) exposure from public drinking water. The present case-control study was undertaken to evaluate this association further. The cases were composed of female residents of eight towns in the Cape Cod region of Massachusetts who had been diagnosed with breast cancer from 1987 through 1993 (n = 672). Controls were composed of demographically similar women from the same towns (n = 616). Women were exposed to PCE when it leached from the vinyl lining of water distribution pipes from the late 1960s through the early 1980s. A relative delivered dose of PCE that entered a home was estimated using an algorithm that took into account residential history, water flow, and pipe characteristics. Small to moderate elevations in risk were seen among women whose exposure levels were above the 75th and 90th percentiles when 0-15 years of latency were considered (adjusted odds ratios, 1.5-1.9 for > 75th percentile, 1.3-2.8 for > 90th percentile). When data from the present and prior studies were combined, small to moderate increases in risk were also seen among women whose exposure levels were above the 75th and 90th percentiles when 0-15 years of latency were considered (adjusted odds ratios, 1.6-1.9 for > 75th percentile, 1.3-1.9 for > 90th percentile). The results of the present study confirm those of the previous one and suggest that women with the highest PCE exposure levels have a small to moderate increased risk of breast cancer. PMID:12573900

  16. Thermodynamic network model for predicting effects of substrate addition and other perturbations on subsurface microbial communities

    SciTech Connect

    Jack Istok; Melora Park; James McKinley; Chongxuan Liu; Lee Krumholz; Anne Spain; Aaron Peacock; Brett Baldwin

    2007-04-19

    The overall goal of this project is to develop and test a thermodynamic network model for predicting the effects of substrate additions and environmental perturbations on microbial growth, community composition and system geochemistry. The hypothesis is that a thermodynamic analysis of the energy-yielding growth reactions performed by defined groups of microorganisms can be used to make quantitative and testable predictions of the change in microbial community composition that will occur when a substrate is added to the subsurface or when environmental conditions change.

  17. The effect of bathymetric filtering on nearshore process model results

    USGS Publications Warehouse

    Plant, N.G.; Edwards, K.L.; Kaihatu, J.M.; Veeramony, J.; Hsu, L.; Holland, K.T.

    2009-01-01

    Nearshore wave and flow model results are shown to exhibit a strong sensitivity to the resolution of the input bathymetry. In this analysis, bathymetric resolution was varied by applying smoothing filters to high-resolution survey data to produce a number of bathymetric grid surfaces. We demonstrate that the sensitivity of model-predicted wave height and flow to variations in bathymetric resolution had different characteristics. Wave height predictions were most sensitive to resolution of cross-shore variability associated with the structure of nearshore sandbars. Flow predictions were most sensitive to the resolution of intermediate scale alongshore variability associated with the prominent sandbar rhythmicity. Flow sensitivity increased in cases where a sandbar was closer to shore and shallower. Perhaps the most surprising implication of these results is that the interpolation and smoothing of bathymetric data could be optimized differently for the wave and flow models. We show that errors between observed and modeled flow and wave heights are well predicted by comparing model simulation results using progressively filtered bathymetry to results from the highest resolution simulation. The damage done by over smoothing or inadequate sampling can therefore be estimated using model simulations. We conclude that the ability to quantify prediction errors will be useful for supporting future data assimilation efforts that require this information.

  18. A homozygous telomerase T-motif variant resulting in markedly reduced repeat addition processivity in siblings with Hoyeraal Hreidarsson syndrome

    PubMed Central

    Gramatges, Maria M.; Qi, Xiaodong; Sasa, Ghadir S.; Chen, Julian J.-L.

    2013-01-01

    Hoyeraal Hreidarsson syndrome (HHS) is a form of dyskeratosis congenita (DC) characterized by bone marrow failure, intrauterine growth retardation, developmental delay, microcephaly, cerebellar hypoplasia, immunodeficiency, and extremely short telomeres. As with DC, mutations in genes encoding factors required for telomere maintenance, such as telomerase reverse transcriptase (TERT), have been found in patients with HHS. We describe 2 sibling HHS cases caused by a homozygous mutation (p.T567M) within the TERT T motif. This mutation resulted in a marked reduction in the capacity of telomerase to processively synthesize telomeric repeats, indicating a role for the T motif in this unique aspect of telomerase function. We support this finding by demonstrating defective processivity in the previously reported p.K570N T-motif mutation. The consanguineous, heterozygous p.T567M parents exhibited telomere lengths around the first percentile and no evidence of a DC phenotype. Although heterozygous processivity defects have been associated with familial, adult-onset pulmonary fibrosis, these cases demonstrate the severe clinical and functional impact of biallelic processivity mutations. Thus, despite retaining the capacity to add short stretches of telomeric repeats onto the shortest telomeres, sole expression of telomerase processivity mutants can lead to a profound failure of telomere maintenance and early-onset multisystem disease. PMID:23538340

  19. Experimental and modeling study of the effects of multicomponent gas additives on selective non-catalytic reduction process.

    PubMed

    Cao, Qingxi; Wu, Shaohua; Lui, Hui; Liu, Dunyu; Qiu, Penghua

    2009-08-01

    The influence of multicomponent additives on NO reduction by selective non-catalytic reduction process has been investigated experimentally in an electricity-heated tube reactor. The multicomponent additives are composed of two species of CO, CH(4) and H(2), and the molar ratio of their two components varies from 1/3 to 3/1. The results show that all the investigated additives could decrease the optimal temperature for NO reduction effectively, but the contributions of their components are different. The performance of multicomponent additive composed of CO and CH(4) depends mainly on CH(4) component. The function of CO component is shifting the temperature window for NO reduction to lower temperature slightly and narrowing the temperature window a little. The temperature window with multicomponent additive composed of H(2) and CH(4) is distinct from that with its each component, so both H(2) and CH(4) component make important contributions. While the fraction of CO is no more than that of H(2) in multicomponent additives composed of them, the performance of multicomponent additives is dominated by H(2) component; while the fraction of CO becomes larger, the influence of CO component becomes notable. Qualitatively the modeling results using a detailed chemical kinetic mechanism exhibit the same characteristics of the temperature window shift as observed experimentally. By reaction mechanism analysis, the distinct influences of CO, CH(4) or H(2) component on the property of multicomponent additive are mainly caused by the different production rates of (*)OH radical in their own oxidation process.

  20. Generalized additive models and Lucilia sericata growth: assessing confidence intervals and error rates in forensic entomology.

    PubMed

    Tarone, Aaron M; Foran, David R

    2008-07-01

    Forensic entomologists use blow fly development to estimate a postmortem interval. Although accurate, fly age estimates can be imprecise for older developmental stages and no standard means of assigning confidence intervals exists. Presented here is a method for modeling growth of the forensically important blow fly Lucilia sericata, using generalized additive models (GAMs). Eighteen GAMs were created to predict the extent of juvenile fly development, encompassing developmental stage, length, weight, strain, and temperature data, collected from 2559 individuals. All measures were informative, explaining up to 92.6% of the deviance in the data, though strain and temperature exerted negligible influences. Predictions made with an independent data set allowed for a subsequent examination of error. Estimates using length and developmental stage were within 5% of true development percent during the feeding portion of the larval life cycle, while predictions for postfeeding third instars were less precise, but within expected error.

  1. Robust estimation of mean and dispersion functions in extended generalized additive models.

    PubMed

    Croux, Christophe; Gijbels, Irène; Prosdocimi, Ilaria

    2012-03-01

    Generalized linear models are a widely used method to obtain parametric estimates for the mean function. They have been further extended to allow the relationship between the mean function and the covariates to be more flexible via generalized additive models. However, the fixed variance structure can in many cases be too restrictive. The extended quasilikelihood (EQL) framework allows for estimation of both the mean and the dispersion/variance as functions of covariates. As for other maximum likelihood methods though, EQL estimates are not resistant to outliers: we need methods to obtain robust estimates for both the mean and the dispersion function. In this article, we obtain functional estimates for the mean and the dispersion that are both robust and smooth. The performance of the proposed method is illustrated via a simulation study and some real data examples.

  2. Observations and model calculations of an additional layer in the topside ionosphere above Fortaleza, Brazil

    NASA Astrophysics Data System (ADS)

    Jenkins, B.; Bailey, G. J.; Abdu, M. A.; Batista, I. S.; Balan, N.

    1997-06-01

    Calculations using the Sheffield University plasmasphere ionosphere model have shown that under certain conditions an additional layer can form in the low latitude topside ionosphere. This layer (the F3 layer) has subsequently been observed in ionograms recorded at Fortaleza in Brazil. It has not been observed in ionograms recorded at the neighbouring station São Luis. Model calculations have shown that the F3 layer is most likely to form in summer at Fortaleza due to a combination of the neutral wind and the E×B drift acting to raise the plasma. At the location of São Luis, almost on the geomagnetic equator, the neutral wind has a smaller vertical component so the F3 layer does not form.

  3. Evidence of Rapidly Warming Rivers in the UK from an Extensive Additive Modelling Study at the National Scale Using R

    NASA Astrophysics Data System (ADS)

    Simpson, G. L.

    2011-12-01

    River water temperature data exhibit non-linear behaviour over the past 50 or so years. Standard techniques for identifying and quantifying trends have centred around the use of linear regression and Mann-Kendall and Thiel-Sen procedures. Observational data from UK rivers suggest that temperatures are far more variable then assumed under these statistical models. In a national-scale assessment of the response of riverine systems to global climatic change, an additive model framework was employed to model patterns in water temperatures from a large database of temporal observational data. Models were developed using R, which allowed for the deployment of cutting-edge additive modelling techniques to describe trends at 2773 sites across England and Wales, UK. At a subset of sites, additive models were used to model long-term trends, trends within seasons and the long-term variation in the seasonal pattern of water temperatures. Changes in water temperature have important consequences for aquatic ecology, with some species being particularly sensitive even to small shifts in temperature during some or all of their lifecycle. While there are many studies reporting increasing regional and global air temperatures, evidence for changes in river water temperature has thus far been site specific and/or from sites heavily influenced by human activities that could themselves lead to warming. Here I present selected results from a national-scale assessment of changing river water temperatures, covering the whole of England and Wales, comprising data from 2,773 locations. Positive trends in water temperature were observed at 86% of sites. At a subset of sites, seasonal trend models were developed, which showed that 90% of locations demonstrated statistically significant increases in water temperature during Autumn and Winter periods. Multivariate smoothers, that allow for within-year and longer-term trend interactions in time, suggest that periods of warmer waters now extend

  4. Results from a new Cocks-Ashby style porosity model

    NASA Astrophysics Data System (ADS)

    Barton, Nathan

    2015-06-01

    A new porosity evolution model will be described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution will be shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations - efficiency and robustness of the numerical implementation are significant issues. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-ABS-666658).

  5. Mathematical Existence Results for the Doi-Edwards Polymer Model

    NASA Astrophysics Data System (ADS)

    Chupin, Laurent

    2017-01-01

    In this paper, we present some mathematical results on the Doi-Edwards model describing the dynamics of flexible polymers in melts and concentrated solutions. This model, developed in the late 1970s, has been used and extensively tested in modeling and simulation of polymer flows. From a mathematical point of view, the Doi-Edwards model consists in a strong coupling between the Navier-Stokes equations and a highly nonlinear constitutive law. The aim of this article is to provide a rigorous proof of the well-posedness of the Doi-Edwards model, namely that it has a unique regular solution. We also prove, which is generally much more difficult for flows of viscoelastic type, that the solution is global in time in the two dimensional case, without any restriction on the smallness of the data.

  6. Exact results for models of multichannel quantum nonadiabatic transitions

    DOE PAGES

    Sinitsyn, N. A.

    2014-12-11

    We consider nonadiabatic transitions in explicitly time-dependent systems with Hamiltonians of the form Hˆ(t)=Aˆ+Bˆt+Cˆ/t, where t is time and Aˆ,Bˆ,Cˆ are Hermitian N × N matrices. We show that in any model of this type, scattering matrix elements satisfy nontrivial exact constraints that follow from the absence of the Stokes phenomenon for solutions with specific conditions at t→–∞. This allows one to continue such solutions analytically to t→+∞, and connect their asymptotic behavior at t→–∞ and t→+∞. This property becomes particularly useful when a model shows additional discrete symmetries. Specifically, we derive a number of simple exact constraints and explicitmore » expressions for scattering probabilities in such systems.« less

  7. Exact results for models of multichannel quantum nonadiabatic transitions

    SciTech Connect

    Sinitsyn, N. A.

    2014-12-11

    We consider nonadiabatic transitions in explicitly time-dependent systems with Hamiltonians of the form Hˆ(t)=Aˆ+Bˆt+Cˆ/t, where t is time and Aˆ,Bˆ,Cˆ are Hermitian N × N matrices. We show that in any model of this type, scattering matrix elements satisfy nontrivial exact constraints that follow from the absence of the Stokes phenomenon for solutions with specific conditions at t→–∞. This allows one to continue such solutions analytically to t→+∞, and connect their asymptotic behavior at t→–∞ and t→+∞. This property becomes particularly useful when a model shows additional discrete symmetries. Specifically, we derive a number of simple exact constraints and explicit expressions for scattering probabilities in such systems.

  8. Modeling Results for the ITER Cryogenic Fore Pump

    NASA Astrophysics Data System (ADS)

    Zhang, Dongsheng

    The work presented here is the analysis and modeling of the ITER-Cryogenic Fore Pump (CFP), also called Cryogenic Viscous Compressor (CVC). Unlike common cryopumps that are usually used to create and maintain vacuum, the cryogenic fore pump is designed for ITER to collect and compress hydrogen isotopes during the regeneration process of the torus cryopumps. Different from common cryopumps, the ITER-CFP works in the viscous flow regime. As a result, both adsorption boundary conditions and transport phenomena contribute unique features to the pump performance. In this report, the physical mechanisms of cryopumping are studied, especially the diffusion-adsorption process and these are coupled with the standard equations of species, momentum and energy balance, as well as the equation of state. Numerical models are developed, which include highly coupled non-linear conservation equations of species, momentum, and energy and equation of state. Thermal and kinetic properties are treated as functions of temperature, pressure, and composition of the gas fluid mixture. To solve such a set of equations, a novel numerical technique, identified as the Group-Member numerical technique is proposed. This document presents three numerical models: a transient model, a steady state model, and a hemisphere (or molecular flow) model. The first two models are developed based on analysis of the raw experimental data while the third model is developed as a preliminary study. The modeling results are compared with available experiment data for verification. The models can be used for cryopump design, and can also benefit problems, such as loss of vacuum in a cryomodule or cryogenic desublimation. The scientific and engineering investigation being done here builds connections between Mechanical Engineering and other disciplines, such as Chemical Engineering, Physics, and Chemistry.

  9. Melt coolability modeling and comparison to MACE test results

    SciTech Connect

    Farmer, M.T.; Sienicki, J.J.; Spencer, B.W.

    1992-04-01

    An important question in the assessment of severe accidents in light water nuclear reactors is the ability of water to quench a molten corium-concrete interaction and thereby terminate the accident progression. As part of the Melt Attack and Coolability Experiment (MACE) Program, phenomenological models of the corium quenching process are under development. The modeling approach considers both bulk cooldown and crust-limited heat transfer regimes, as well as criteria for the pool thermal hydraulic conditions which separate the two regimes. The model is then compared with results of the MACE experiments.

  10. Melt coolability modeling and comparison to MACE test results

    SciTech Connect

    Farmer, M.T.; Sienicki, J.J.; Spencer, B.W.

    1992-01-01

    An important question in the assessment of severe accidents in light water nuclear reactors is the ability of water to quench a molten corium-concrete interaction and thereby terminate the accident progression. As part of the Melt Attack and Coolability Experiment (MACE) Program, phenomenological models of the corium quenching process are under development. The modeling approach considers both bulk cooldown and crust-limited heat transfer regimes, as well as criteria for the pool thermal hydraulic conditions which separate the two regimes. The model is then compared with results of the MACE experiments.

  11. Analysis of the Second Model Parameter Estimation Experiment Workshop Results

    NASA Astrophysics Data System (ADS)

    Duan, Q.; Schaake, J.; Koren, V.; Mitchell, K.; Lohmann, D.

    2002-05-01

    The goal of Model Parameter Estimation Experiment (MOPEX) is to investigate techniques for the a priori parameter estimation for land surface parameterization schemes of atmospheric models and for hydrologic models. A comprehensive database has been developed which contains historical hydrometeorologic time series data and land surface characteristics data for 435 basins in the United States and many international basins. A number of international MOPEX workshops have been convened or planned for MOPEX participants to share their parameter estimation experience. The Second International MOPEX Workshop is held in Tucson, Arizona, April 8-10, 2002. This paper presents the MOPEX goal/objectives and science strategy. Results from our participation in developing and testing of the a priori parameter estimation procedures for the National Weather Service (NWS) Sacramento Soil Moisture Accounting (SAC-SMA) model, the Simple Water Balance (SWB) model, and the National Center for Environmental Prediction Center (NCEP) NOAH Land Surface Model (NOAH LSM) are highlighted. The test results will include model simulations using both a priori parameters and calibrated parameters for 12 basins selected for the Tucson MOPEX Workshop.

  12. Guarana provides additional stimulation over caffeine alone in the planarian model.

    PubMed

    Moustakas, Dimitrios; Mezzio, Michael; Rodriguez, Branden R; Constable, Mic Andre; Mulligan, Margaret E; Voura, Evelyn B

    2015-01-01

    The stimulant effect of energy drinks is primarily attributed to the caffeine they contain. Many energy drinks also contain other ingredients that might enhance the tonic effects of these caffeinated beverages. One of these additives is guarana. Guarana is a climbing plant native to the Amazon whose seeds contain approximately four times the amount of caffeine found in coffee beans. The mix of other natural chemicals contained in guarana seeds is thought to heighten the stimulant effects of guarana over caffeine alone. Yet, despite the growing use of guarana as an additive in energy drinks, and a burgeoning market for it as a nutritional supplement, the science examining guarana and how it affects other dietary ingredients is lacking. To appreciate the stimulant effects of guarana and other natural products, a straightforward model to investigate their physiological properties is needed. The planarian provides such a system. The locomotor activity and convulsive response of planarians with substance exposure has been shown to provide an excellent system to measure the effects of drug stimulation, addiction and withdrawal. To gauge the stimulant effects of guarana we studied how it altered the locomotor activity of the planarian species Dugesia tigrina. We report evidence that guarana seeds provide additional stimulation over caffeine alone, and document the changes to this stimulation in the context of both caffeine and glucose.

  13. Guarana Provides Additional Stimulation over Caffeine Alone in the Planarian Model

    PubMed Central

    Moustakas, Dimitrios; Mezzio, Michael; Rodriguez, Branden R.; Constable, Mic Andre; Mulligan, Margaret E.; Voura, Evelyn B.

    2015-01-01

    The stimulant effect of energy drinks is primarily attributed to the caffeine they contain. Many energy drinks also contain other ingredients that might enhance the tonic effects of these caffeinated beverages. One of these additives is guarana. Guarana is a climbing plant native to the Amazon whose seeds contain approximately four times the amount of caffeine found in coffee beans. The mix of other natural chemicals contained in guarana seeds is thought to heighten the stimulant effects of guarana over caffeine alone. Yet, despite the growing use of guarana as an additive in energy drinks, and a burgeoning market for it as a nutritional supplement, the science examining guarana and how it affects other dietary ingredients is lacking. To appreciate the stimulant effects of guarana and other natural products, a straightforward model to investigate their physiological properties is needed. The planarian provides such a system. The locomotor activity and convulsive response of planarians with substance exposure has been shown to provide an excellent system to measure the effects of drug stimulation, addiction and withdrawal. To gauge the stimulant effects of guarana we studied how it altered the locomotor activity of the planarian species Dugesia tigrina. We report evidence that guarana seeds provide additional stimulation over caffeine alone, and document the changes to this stimulation in the context of both caffeine and glucose. PMID:25880065

  14. Analysis and Modeling of soil hydrology under different soil additives in artificial runoff plots

    NASA Astrophysics Data System (ADS)

    Ruidisch, M.; Arnhold, S.; Kettering, J.; Huwe, B.; Kuzyakov, Y.; Ok, Y.; Tenhunen, J. D.

    2009-12-01

    The impact of monsoon events during June and July in the Korean project region Haean Basin, which is located in the northeastern part of South Korea plays a key role for erosion, leaching and groundwater pollution risk by agrochemicals. Therefore, the project investigates the main hydrological processes in agricultural soils under field and laboratory conditions on different scales (plot, hillslope and catchment). Soil hydrological parameters were analysed depending on different soil additives, which are known for prevention of soil erosion and nutrient loss as well as increasing of water infiltration, aggregate stability and soil fertility. Hence, synthetic water-soluble Polyacrylamides (PAM), Biochar (Black Carbon mixed with organic fertilizer), both PAM and Biochar were applied in runoff plots at three agricultural field sites. Additionally, as control a subplot was set up without any additives. The field sites were selected in areas with similar hillslope gradients and with emphasis on the dominant land management form of dryland farming in Haean, which is characterised by row planting and row covering by foil. Hydrological parameters like satured water conductivity, matrix potential and water content were analysed by infiltration experiments, continuous tensiometer measurements, time domain reflectometry as well as pressure plates to indentify characteristic water retention curves of each horizon. Weather data were observed by three weather stations next to the runoff plots. Measured data also provide the input data for modeling water transport in the unsatured zone in runoff plots with HYDRUS 1D/2D/3D and SWAT (Soil & Water Assessment Tool).

  15. Modeling Modern Methane Emissions from Natural Wetlands. 1; Model Description and Results

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin; Matthews, Elaine

    2001-01-01

    Methane is an important greenhouse gas which contributes about 22 percent to the present greenhouse effect. Natural wetlands currently constitute the biggest methane source and were the major source in preindustrial times. Wetland emissions depend highly on the climate, i.e., on soil temperature and water table. To investigate the response of methane emissions from natural wetlands to climate variations, a process-based model that derives methane emissions from natural wetlands as a function of soil temperature, water table, and net primary productivity is used. For its application on the global scale, global data sets for all model parameters are generated. In addition, a simple hydrologic model is developed in order to simulate the position of the water table in wetlands. The hydrologic model is tested against data from different wetland sites, and the sensitivity of the hydrologic model to changes in precipitation is examined. The global methane­ hydrology model constitutes a tool to study temporal and spatial variations in methane emissions from natural wetlands. The model is applied using high-frequency atmospheric forcing fields from European Center for Medium-range Weather Forecasts (ECMWF) re-analyses of the period from 1982 to 1993. We calculate global annual methane emissions from wetlands to be 260 teragrams per year. Twenty-five percent of these methane emissions originate from wetlands north of 30 degrees North Latitude. Only 60 percent of the produced methane is emitted, while the rest is re-oxidized. A comparison of zonal integrals of simulated global wetland emissions and results obtained by an inverse modeling approach shows good agreement. In a test with data from two wetlands the seasonality of simulated and observed methane emissions agrees well.

  16. “Skill of Generalized Additive Model to Detect PM2.5 Health ...

    EPA Pesticide Factsheets

    Summary. Measures of health outcomes are collinear with meteorology and air quality, making analysis of connections between human health and air quality difficult. The purpose of this analysis was to determine time scales and periods shared by the variables of interest (and by implication scales and periods that are not shared). Hospital admissions, meteorology (temperature and relative humidity), and air quality (PM2.5 and daily maximum ozone) for New York City during the period 2000-2006 were decomposed into temporal scales ranging from 2 days to greater than two years using a complex wavelet transform. Health effects were modeled as functions of the wavelet components of meteorology and air quality using the generalized additive model (GAM) framework. This simulation study showed that GAM is extremely successful at extracting and estimating a health effect embedded in a dataset. It also shows that, if the objective in mind is to estimate the health signal but not to fully explain this signal, a simple GAM model with a single confounder (calendar time) whose smooth representation includes a sufficient number of constraints is as good as a more complex model.Introduction. In the context of wavelet regression, confounding occurs when two or more independent variables interact with the dependent variable at the same frequency. Confounding also acts on a variety of time scales, changing the PM2.5 coefficient (magnitude and sign) and its significance ac

  17. Summary of FY15 results of benchmark modeling activities

    SciTech Connect

    Arguello, J. Guadalupe

    2015-08-01

    Sandia is participating in the third phase of an is a contributing partner to a U.S.-German "Joint Project" entitled "Comparison of current constitutive models and simulation procedures on the basis of model calculations of the thermo-mechanical behavior and healing of rock salt." The first goal of the project is to check the ability of numerical modeling tools to correctly describe the relevant deformation phenomena in rock salt under various influences. Achieving this goal will lead to increased confidence in the results of numerical simulations related to the secure storage of radioactive wastes in rock salt, thereby enhancing the acceptance of the results. These results may ultimately be used to make various assertions regarding both the stability analysis of an underground repository in salt, during the operating phase, and the long-term integrity of the geological barrier against the release of harmful substances into the biosphere, in the post-operating phase.

  18. Modelling of flame propagation in the gasoline fuelled Wankel rotary engine with hydrogen additives

    NASA Astrophysics Data System (ADS)

    Fedyanov, E. A.; Zakharov, E. A.; Prikhodkov, K. V.; Levin, Y. V.

    2017-02-01

    Recently, hydrogen has been considered as an alternative fuel for a vehicles power unit. The Wankel engine is the most suitable to be adapted to hydrogen feeding. A hydrogen additive helps to decrease incompleteness of combustion in the volumes near the apex of the rotor. Results of theoretical researches of the hydrogen additives influence on the flame propagation in the combustion chamber of the Wankel rotary engine are presented. The theoretical research shows that the blend of 70% gasoline with 30% hydrogen could accomplish combustion near the T-apex in the stoichiometric mixture and in lean one. Maps of the flame front location versus the angle of rotor rotation and hydrogen fraction are obtained. Relations of a minimum required amount of hydrogen addition versus the engine speed are shown on the engine modes close to the average city driving cycle. The amount of hydrogen addition that could be injected by the nozzle with different flow sections is calculated in order to analyze the capacity of the feed system.

  19. CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

    PubMed Central

    Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

    2015-01-01

    As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change. PMID:25608664

  20. CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems.

    PubMed

    Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

    2015-01-22

    As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change.

  1. CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

    NASA Astrophysics Data System (ADS)

    Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

    2015-01-01

    As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change.

  2. Computation of octanol-water partition coefficients by guiding an additive model with knowledge.

    PubMed

    Cheng, Tiejun; Zhao, Yuan; Li, Xun; Lin, Fu; Xu, Yong; Zhang, Xinglong; Li, Yan; Wang, Renxiao; Lai, Luhua

    2007-01-01

    We have developed a new method, i.e., XLOGP3, for logP computation. XLOGP3 predicts the logP value of a query compound by using the known logP value of a reference compound as a starting point. The difference in the logP values of the query compound and the reference compound is then estimated by an additive model. The additive model implemented in XLOGP3 uses a total of 87 atom/group types and two correction factors as descriptors. It is calibrated on a training set of 8199 organic compounds with reliable logP data through a multivariate linear regression analysis. For a given query compound, the compound showing the highest structural similarity in the training set will be selected as the reference compound. Structural similarity is quantified based on topological torsion descriptors. XLOGP3 has been tested along with its predecessor, i.e., XLOGP2, as well as several popular logP methods on two independent test sets: one contains 406 small-molecule drugs approved by the FDA and the other contains 219 oligopeptides. On both test sets, XLOGP3 produces more accurate predictions than most of the other methods with average unsigned errors of 0.24-0.51 units. Compared to conventional additive methods, XLOGP3 does not rely on an extensive classification of fragments and correction factors in order to improve accuracy. It is also able to utilize the ever-increasing experimentally measured logP data more effectively.

  3. Effects of protein and peptide addition on lipid oxidation in powder model system.

    PubMed

    Park, Eun Young; Murakami, Hiroshi; Mori, Tomohiko; Matsumura, Yasuki

    2005-01-12

    The effect of protein and peptide addition on the oxidation of eicosapentaenoic acid ethyl ester (EPE) encapsulated by maltodextrin (MD) was investigated. The encapsulated lipid (powder lipid) was prepared in two steps, i.e., mixing of EPE with MD solutions (+/- protein and peptides) to produce emulsions and freeze-drying of the resultant emulsions. EPE oxidation in MD powder progressed more rapidly in the humid state [relative humidity (RH) = 70%] than in the dry state (RH = 10%). The addition of soy protein, soy peptide, and gelatin peptides improved the oxidation stability of EPE encapsulated by MD, and the inhibition of lipid oxidation by the protein and the peptides was more dramatic in the humid state. Especially, the oxidation of EPE was almost perfectly suppressed when the lipid was encapsulated with MD + soy peptide during storage in the humid state for 7 days. Several physical properties such as the lipid particle size of the emulsions, the fraction of nonencapsulated lipids, scanning electron microscopy images of powder lipids, and the mobility of the MD matrix were investigated to find the modification of encapsulation behavior by the addition of the protein and peptides, but no significant change was observed. On the other hand, the protein and peptides exhibited a strong radical scavenging activity in the powder systems as well as in the solution systems. These results suggest that a chemical mechanism such as radical scavenging ability plays an important role in the suppression of EPE oxidation in MD powder by soy proteins, soy peptides, and gelatin peptides.

  4. Electromagnetic induction in New Zealand: analogue model and field results

    NASA Astrophysics Data System (ADS)

    Chen, J.; Dosso, H. W.; Ingham, M.

    The behaviour of electric and magnetic variations over North Island (New Zealand) is studied with the aid of a laboratory analogue model. The source field frequencies used in the analogue modelling simulate naturally occurring geomagnetic variations of 5-120 min periods. In-phase and quadrature magnetic and electric fields for a selection of traverses for the modelled region of North Island are presented. Since North Island is of a relatively narrow cross-section, the field responses, even for inland locations, are expected to show strongly the effects of the surrounding ocean. The irregular coastlines, as well as the strait between North and South Islands, lead to coastal and inland field anomalies due to induced currents being deflected and channelled to produce localized current densities. The comparison of model results with field station measurements obtained earlier individually by Ingham and by Midha for sites in the northeastern, central, and southern (near Cook Strait) regions of North Island demonstrates the large role the ocean has in the observed field responses. Differences in the model and field results at some sites are expected and should reflect the effects of the local geology and the conductive substructure related to the complex tectonics of the region not simulated in the model.

  5. Testing the Addition of Topographic Features for Field Scale Infiltration Excess Water Quality Modeling in SWAT

    NASA Astrophysics Data System (ADS)

    Collick, A.; Easton, Z. M.; Kleinman, P. J. A.; Sommerlot, A.; White, M. J.; Harmel, D.; Fuka, D.

    2014-12-01

    Watershed planners and managers need reliable tools that can capture the spatial and temporal complexity of agricultural landscapes, and water quality models are increasingly relied upon to represent P loss from agricultural watersheds. While a significant amount of modeling work has attempted to incorporate factors controlling P loss (e.g. representing solubility, manure types, timing and application type), these models still typically require significant calibration and are thus difficult to apply meaningfully in areas without copious data with which to calibrate. This is partially because these models were never really intended as field scale tools, while we are trying to use them to define different hydrologic pathways, area weighted potential energy (slopes and saturated conductivities), and the resulting lag time of P in different transport states. The movement of water within the landscape as surface (or near-surface) storm runoff and interflow is driven by gravity, topography, contributing area and soil and landuse characteristics, which play roles in concentrating water flows. Soil surveys have played a key role in the development of pedology and spatially derived pedon soil maps have become valuable datasets for natural resource management. Unfortunately, the soil surveys, commonly available at ~1:20,000 scale, are not designed to provide the high-resolution models of the soil continuum required in field scale environmental modeling applications and site specific crop and water quality management. The goal of this project is to test a methodology designed initially for representing saturation excess hydrology in the SWAT model to incorporate topographic attributes, and resulting spatially explicit soil morphology, that are missing from standard SWAT model initializations.

  6. A Cognitive Tool for Teaching the Addition/Subtraction of Common Fractions: A Model of Affordances

    ERIC Educational Resources Information Center

    Kong, Siu Cheung; Kwok, Lam For

    2005-01-01

    The aim of this research is to devise a cognitive tool for meeting the diverse needs of learners for comprehending new procedural knowledge. A model of affordances on teaching fraction equivalence for developing procedural knowledge for adding/subtracting fractions with unlike denominators was derived from the results of a case study of an initial…

  7. The biobehavioral family model: testing social support as an additional exogenous variable.

    PubMed

    Woods, Sarah B; Priest, Jacob B; Roush, Tara

    2014-12-01

    This study tests the inclusion of social support as a distinct exogenous variable in the Biobehavioral Family Model (BBFM). The BBFM is a biopsychosocial approach to health that proposes that biobehavioral reactivity (anxiety and depression) mediates the relationship between family emotional climate and disease activity. Data for this study included married, English-speaking adult participants (n = 1,321; 55% female; M age = 45.2 years) from the National Comorbidity Survey Replication, a nationally representative epidemiological study of the frequency of mental disorders in the United States. Participants reported their demographics, marital functioning, social support from friends and relatives, anxiety and depression (biobehavioral reactivity), number of chronic health conditions, and number of prescription medications. Confirmatory factor analyses supported the items used in the measures of negative marital interactions, social support, and biobehavioral reactivity, as well as the use of negative marital interactions, friends' social support, and relatives' social support as distinct factors in the model. Structural equation modeling indicated a good fit of the data to the hypothesized model (χ(2)  = 846.04, p = .000, SRMR = .039, CFI = .924, TLI = .914, RMSEA = .043). Negative marital interactions predicted biobehavioral reactivity (β = .38, p < .001), as did relatives' social support, inversely (β = -.16, p < .001). Biobehavioral reactivity predicted disease activity (β = .40, p < .001) and was demonstrated to be a significant mediator through tests of indirect effects. Findings are consistent with previous tests of the BBFM with adult samples, and suggest the important addition of family social support as a predicting factor in the model.

  8. Value of the distant future: Model-independent results

    NASA Astrophysics Data System (ADS)

    Katz, Yuri A.

    2017-01-01

    This paper shows that the model-independent account of correlations in an interest rate process or a log-consumption growth process leads to declining long-term tails of discount curves. Under the assumption of an exponentially decaying memory in fluctuations of risk-free real interest rates, I derive the analytical expression for an apt value of the long run discount factor and provide a detailed comparison of the obtained result with the outcome of the benchmark risk-free interest rate models. Utilizing the standard consumption-based model with an isoelastic power utility of the representative economic agent, I derive the non-Markovian generalization of the Ramsey discounting formula. Obtained analytical results allowing simple calibration, may augment the rigorous cost-benefit and regulatory impact analysis of long-term environmental and infrastructure projects.

  9. Artefacts or reality? Sometimes interesting modelling results should be discarded

    NASA Astrophysics Data System (ADS)

    Duclaux, Guillaume; Huismans, Ritske S.; Theunissen, Thomas

    2016-04-01

    Nowadays, forward numerical modelling is widely used in the geoscience community to investigate tectonic or surface processes in two and three dimensions. These codes implement non-linear physical laws to solve for temperature, velocity , pressure, or landscape dynamics. Of course, all of these physical laws require a complete set of input parameters, and modelling work generally starts with a phase of parameters exploration. Seemingly interesting results can emerge from this preliminary work, but it is critical to separate modelling artefacts from geological features relevant for the Earth or other natural systems. Here, we present a series of 2D and 3D experimental results forecasting interesting behaviours which are actually irrelevant for understanding geological processes, will you be able to guess what is wrong with those?

  10. Inter-species extrapolation of skin heating resulting from millimeter wave irradiation: modeling and experimental results.

    PubMed

    Nelson, D A; Walters, T J; Ryan, K L; Emerton, K B; Hurt, W D; Ziriax, J M; Johnson, L R; Mason, P A

    2003-05-01

    This study reports measurements of the skin surface temperature elevations during localized irradiation (94 GHz) of three species: rat (irradiated on lower abdomen), rhesus monkey (posterior forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high power density microwaves (HPM). Temperature histories were compared with calculations from a bio-heat transfer model. The mean peak surface temperature increase was approximately 7.0 degrees C for the short-term HPM exposures for all three species/locations, and 8.5 degrees C (monkey, human) to 10.5 degrees C (rat) for the longer-duration LPM exposures. The HPM temperature histories are in close agreement with a one-dimensional conduction heat transfer model with negligible blood flow. The LPM temperature histories were compared with calculations from the bio-heat model, evaluated for various (constant) blood flow rates. Results suggest a variable blood flow model, reflecting a dynamic thermoregulatory response, may be more suited to describing skin surface temperature response under long-duration MMW irradiation.

  11. Spectral models of additive and modulation noise in speech and phonatory excitation signals

    NASA Astrophysics Data System (ADS)

    Schoentgen, Jean

    2003-01-01

    The article presents spectral models of additive and modulation noise in speech. The purpose is to learn about the causes of noise in the spectra of normal and disordered voices and to gauge whether the spectral properties of the perturbations of the phonatory excitation signal can be inferred from the spectral properties of the speech signal. The approach to modeling consists of deducing the Fourier series of the perturbed speech, assuming that the Fourier series of the noise and of the clean monocycle-periodic excitation are known. The models explain published data, take into account the effects of supraglottal tremor, demonstrate the modulation distortion owing to vocal tract filtering, establish conditions under which noise cues of different speech signals may be compared, and predict the impossibility of inferring the spectral properties of the frequency modulating noise from the spectral properties of the frequency modulation noise (e.g., phonatory jitter and frequency tremor). The general conclusion is that only phonatory frequency modulation noise is spectrally relevant. Other types of noise in speech are either epiphenomenal, or their spectral effects are masked by the spectral effects of frequency modulation noise.

  12. Mental self-government: development of the additional democratic learning style scale using Rasch measurement models.

    PubMed

    Nielsen, Tine; Kreiner, Svend; Styles, Irene

    2007-01-01

    This paper describes the development and validation of a democratic learning style scale intended to fill a gap in Sternberg's theory of mental self-government and the associated learning style inventory (Sternberg, 1988, 1997). The scale was constructed as an 8-item scale with a 7-category response scale. The scale was developed following an adapted version of DeVellis' (2003) guidelines for scale development. The validity of the Democratic Learning Style Scale was assessed by items analysis using graphical loglinear Rasch models (Kreiner and Christensen, 2002, 2004, 2006) The item analysis confirmed that the full 8-item revised Democratic Learning Style Scale fitted a graphical loglinear Rasch model with no differential item functioning but weak to moderate uniform local dependence between two items. In addition, a reduced 6-item version of the scale fitted the pure Rasch model with a rating scale parameterization. The revised Democratic Learning Style Scale can therefore be regarded as a sound measurement scale meeting requirements of both construct validity and objectivity.

  13. A Bayesian additive model for understanding public transport usage in special events.

    PubMed

    Rodrigues, Filipe; Borysov, Stanislav; Ribeiro, Bernardete; Pereira, Francisco

    2016-12-02

    Public special events, like sports games, concerts and festivals are well known to create disruptions in transportation systems, often catching the operators by surprise. Although these are usually planned well in advance, their impact is difficult to predict, even when organisers and transportation operators coordinate. The problem highly increases when several events happen concurrently. To solve these problems, costly processes, heavily reliant on manual search and personal experience, are usual practice in large cities like Singapore, London or Tokyo. This paper presents a Bayesian additive model with Gaussian process components that combines smart card records from public transport with context information about events that is continuously mined from the Web. We develop an efficient approximate inference algorithm using expectation propagation, which allows us to predict the total number of public transportation trips to the special event areas, thereby contributing to a more adaptive transportation system. Furthermore, for multiple concurrent event scenarios, the proposed algorithm is able to disaggregate gross trip counts into their most likely components related to specific events and routine behavior. Using real data from Singapore, we show that the presented model outperforms the best baseline model by up to 26% in R2 and also has explanatory power for its individual components.

  14. Using satellite-derived backscattering coefficients in addition to chlorophyll data to constrain a simple marine biogeochemical model

    NASA Astrophysics Data System (ADS)

    Kettle, H.

    2009-08-01

    Biogeochemical models of the ocean carbon cycle are frequently validated by, or tuned to, satellite chlorophyll data. However, ocean carbon cycle models are required to accurately model the movement of carbon, not chlorophyll, and due to the high variability of the carbon to chlorophyll ratio in phytoplankton, chlorophyll is not a robust proxy for carbon. Using inherent optical property (IOP) inversion algorithms it is now possible to also derive the amount of light backscattered by the upper ocean (bb) which is related to the amount of particulate organic carbon (POC) present. Using empirical relationships between POC and bb, a 1-D marine biogeochemical model is used to simulate bb at 490 nm thereby allowing the model to be compared with both remotely-sensed chlorophyll or bb data. Here I investigate the possibility of using bb in conjunction with chlorophyll data to help constrain the parameters in a simple 1-D NPZD model. The parameters of the biogeochemical model are tuned with a genetic algorithm, so that the model is fitted to either chlorophyll data or to both chlorophyll and bb data at three sites in the Atlantic with very different characteristics. Several inherent optical property (IOP) algorithms are available for estimating bb, three of which are used here. The effect of the different bb datasets on the behaviour of the tuned model is examined to ascertain whether the uncertainty in bb is significant. The results show that the addition of bb data does not consistently alter the same model parameters at each site and in fact can lead to some parameters becoming less well constrained, implying there is still much work to be done on the mechanisms relating chlorophyll to POC and bb within the model. However, this study does indicate that including bb data has the potential to significantly effect the modelled mixed layer detritus and that uncertainties in bb due to the different IOP algorithms are not particularly significant.

  15. Modeling Results For the ITER Cryogenic Fore Pump. Final Report

    SciTech Connect

    Pfotenhauer, John M.; Zhang, Dongsheng

    2014-03-31

    A numerical model characterizing the operation of a cryogenic fore-pump (CFP) for ITER has been developed at the University of Wisconsin – Madison during the period from March 15, 2011 through June 30, 2014. The purpose of the ITER-CFP is to separate hydrogen isotopes from helium gas, both making up the exhaust components from the ITER reactor. The model explicitly determines the amount of hydrogen that is captured by the supercritical-helium-cooled pump as a function of the inlet temperature of the supercritical helium, its flow rate, and the inlet conditions of the hydrogen gas flow. Furthermore the model computes the location and amount of hydrogen captured in the pump as a function of time. Throughout the model’s development, and as a calibration check for its results, it has been extensively compared with the measurements of a CFP prototype tested at Oak Ridge National Lab. The results of the model demonstrate that the quantity of captured hydrogen is very sensitive to the inlet temperature of the helium coolant on the outside of the cryopump. Furthermore, the model can be utilized to refine those tests, and suggests methods that could be incorporated in the testing to enhance the usefulness of the measured data.

  16. Design and tuning of standard additive model based fuzzy PID controllers for multivariable process systems.

    PubMed

    Harinath, Eranda; Mann, George K I

    2008-06-01

    This paper describes a design and two-level tuning method for fuzzy proportional-integral derivative (FPID) controllers for a multivariable process where the fuzzy inference uses the inference of standard additive model. The proposed method can be used for any n x n multi-input-multi-output process and guarantees closed-loop stability. In the two-level tuning scheme, the tuning follows two steps: low-level tuning followed by high-level tuning. The low-level tuning adjusts apparent linear gains, whereas the high-level tuning changes the nonlinearity in the normalized fuzzy output. In this paper, two types of FPID configurations are considered, and their performances are evaluated by using a real-time multizone temperature control problem having a 3 x 3 process system.

  17. Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis

    NASA Astrophysics Data System (ADS)

    Gabriele, Papadia; Antonio, Del Prete; Alfredo, Anglani

    2010-06-01

    The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.

  18. Results of the eruptive column model inter-comparison study

    NASA Astrophysics Data System (ADS)

    Costa, A.; Suzuki, Y. J.; Cerminara, M.; Devenish, B. J.; Ongaro, T. Esposti; Herzog, M.; Van Eaton, A. R.; Denby, L. C.; Bursik, M.; de'Michieli Vitturi, M.; Engwell, S.; Neri, A.; Barsotti, S.; Folch, A.; Macedonio, G.; Girault, F.; Carazzo, G.; Tait, S.; Kaminski, E.; Mastin, L. G.; Woodhouse, M. J.; Phillips, J. C.; Hogg, A. J.; Degruyter, W.; Bonadonna, C.

    2016-10-01

    This study compares and evaluates one-dimensional (1D) and three-dimensional (3D) numerical models of volcanic eruption columns in a set of different inter-comparison exercises. The exercises were designed as a blind test in which a set of common input parameters was given for two reference eruptions, representing a strong and a weak eruption column under different meteorological conditions. Comparing the results of the different models allows us to evaluate their capabilities and target areas for future improvement. Despite their different formulations, the 1D and 3D models provide reasonably consistent predictions of some of the key global descriptors of the volcanic plumes. Variability in plume height, estimated from the standard deviation of model predictions, is within 20% for the weak plume and 10% for the strong plume. Predictions of neutral buoyancy level are also in reasonably good agreement among the different models, with a standard deviation ranging from 9 to 19% (the latter for the weak plume in a windy atmosphere). Overall, these discrepancies are in the range of observational uncertainty of column height. However, there are important differences amongst models in terms of local properties along the plume axis, particularly for the strong plume. Our analysis suggests that the simplified treatment of entrainment in 1D models is adequate to resolve the general behaviour of the weak plume. However, it is inadequate to capture complex features of the strong plume, such as large vortices, partial column collapse, or gravitational fountaining that strongly enhance entrainment in the lower atmosphere. We conclude that there is a need to more accurately quantify entrainment rates, improve the representation of plume radius, and incorporate the effects of column instability in future versions of 1D volcanic plume models.

  19. Spin-probe ESR and molecular modeling studies on calcium carbonate dispersions in overbased detergent additives.

    PubMed

    Montanari, Luciano; Frigerio, Francesco

    2010-08-15

    Oil-soluble calcium carbonate colloids are used as detergent additives in lubricating oils. They are colloidal dispersions of calcium carbonate particles stabilized by different surfactants; in this study alkyl-aryl-sulfonates and sulfurized alkyl-phenates, widely used in the synthesis of these additives, are considered. The physical properties of surfactant layers surrounding the surfaces of calcium carbonate particles were analyzed by using some nitroxide spin-probes (stable free radicals) and observing the corresponding ESR spectra. The spin-probe molecules contain polar groups which tend to tether them to the carbonate particle polar surface. They can reach these surfaces only if the surfactant layers are not very compact, hence the relative amounts of spin-probe molecules accessing carbonate surfaces are an index of the compactness of surfactant core. ESR signals of spin-probe molecules dissolved in oil or "locked" near the carbonate surfaces are different because of the different molecular mobility. Through deconvolution of the ESR spectra, the fraction of spin-probes penetrating surfactant shells have been calculated, and differences were observed according to the surfactant molecular structures. Moreover, by using specially labeled spin-probes based on stearic acids, functionalized at different separations from the carboxylic acid group, it was possible to interrogate the molecular physical behavior of surfactant shells at different distances from carbonate surfaces. Molecular modeling was applied to generate some three-dimensional micellar models of the colloidal stabilizations of the stabilized carbonate particles with different molecular structures of the surfactant. The diffusion of spin-probe molecules into the surfactant shells were studied by applying a starting force to push the molecules towards the carbonate surfaces and then observing the ensuing behavior. The simulations are in accordance with the ESR data and show that the geometrical

  20. Experiments to Populate and Validate a Processing Model for Polyurethane Foam: Additional Data for Structural Foams

    SciTech Connect

    Rao, Rekha R.; Celina, Mathias C.; Giron, Nicholas Henry; Long, Kevin Nicholas; Russick, Edward M.

    2015-01-01

    We are developing computational models to help understand manufacturing processes, final properties and aging of structural foam, polyurethane PMDI. Th e resulting model predictions of density and cure gradients from the manufacturing process will be used as input to foam heat transfer and mechanical models. BKC 44306 PMDI-10 and BKC 44307 PMDI-18 are the most prevalent foams used in structural parts. Experiments needed to parameterize models of the reaction kinetics and the equations of motion during the foam blowing stages were described for BKC 44306 PMDI-10 in the first of this report series (Mondy et al. 2014). BKC 44307 PMDI-18 is a new foam that will be used to make relatively dense structural supports via over packing. It uses a different catalyst than those in the BKC 44306 family of foams; hence, we expect that the reaction kineti cs models must be modified. Here we detail the experiments needed to characteriz e the reaction kinetics of BKC 44307 PMDI-18 and suggest parameters for the model based on these experiments. In additi on, the second part of this report describes data taken to provide input to the preliminary nonlinear visco elastic structural response model developed for BKC 44306 PMDI-10 foam. We show that the standard cu re schedule used by KCP does not fully cure the material, and, upon temperature elevation above 150°C, oxidation or decomposition reactions occur that alter the composition of the foam. These findings suggest that achieving a fully cured foam part with this formulation may be not be possible through therma l curing. As such, visco elastic characterization procedures developed for curing thermosets can provide only approximate material properties, since the state of the material continuously evolves during tests.

  1. Tectonics of planetary loading - A general model and results

    NASA Astrophysics Data System (ADS)

    Janes, D. M.; Melosh, H. J.

    1990-12-01

    The tectonics of planetary loading is investigated using an analytical model for determining the stresses in an arbitrarily thick spherical shell due to an idealized axisymmetric load. The model includes the flat plate and thin shell membrane approximations as end members, and makes it possible to determine the nature of the transition between them. Using this model, the stress states and the resulting tectonic patterns due to an idealized exponential load are determined as functions of five dimensionless parameters: the ratio of the lithospheric thickness to the planetary radius; the decay width of the load; the 'support parameter', which is the ratio of the buoyancy to the flexural support; the angular distance from the load center; and the normalized radial distance from the planet center.

  2. Analysis of contingency tables based on generalised median polish with power transformations and non-additive models.

    PubMed

    Klawonn, Frank; Jayaram, Balasubramaniam; Crull, Katja; Kukita, Akiko; Pessler, Frank

    2013-01-01

    Contingency tables are a very common basis for the investigation of effects of different treatments or influences on a disease or the health state of patients. Many journals put a strong emphasis on p-values to support the validity of results. Therefore, even small contingency tables are analysed by techniques like t-test or ANOVA. Both these concepts are based on normality assumptions for the underlying data. For larger data sets, this assumption is not so critical, since the underlying statistics are based on sums of (independent) random variables which can be assumed to follow approximately a normal distribution, at least for a larger number of summands. But for smaller data sets, the normality assumption can often not be justified. Robust methods like the Wilcoxon-Mann-Whitney-U test or the Kruskal-Wallis test do not lead to statistically significant p-values for small samples. Median polish is a robust alternative to analyse contingency tables providing much more insight than just a p-value. Median polish is a technique that provides more information than just a p-value. It explains the contingency table in terms of an overall effect, row and columns effects and residuals. The underlying model for median polish is an additive model which is sometimes too restrictive. In this paper, we propose two related approach to generalise median polish. A power transformation can be applied to the values in the table, so that better results for median polish can be achieved. We propose a graphical method how to find a suitable power transformation. If the original data should be preserved, one can apply other transformations - based on so-called additive generators - that have an inverse transformation. In this way, median polish can be applied to the original data, but based on a non-additive model. The non-linearity of such a model can also be visualised to better understand the joint effects of rows and columns in a contingency table.

  3. Generalized additive models reveal the intrinsic complexity of wood formation dynamics.

    PubMed

    Cuny, Henri E; Rathgeber, Cyrille B K; Kiessé, Tristan Senga; Hartmann, Felix P; Barbeito, Ignacio; Fournier, Meriem

    2013-04-01

    The intra-annual dynamics of wood formation, which involves the passage of newly produced cells through three successive differentiation phases (division, enlargement, and wall thickening) to reach the final functional mature state, has traditionally been described in conifers as three delayed bell-shaped curves followed by an S-shaped curve. Here the classical view represented by the 'Gompertz function (GF) approach' was challenged using two novel approaches based on parametric generalized linear models (GLMs) and 'data-driven' generalized additive models (GAMs). These three approaches (GFs, GLMs, and GAMs) were used to describe seasonal changes in cell numbers in each of the xylem differentiation phases and to calculate the timing of cell development in three conifer species [Picea abies (L.), Pinus sylvestris L., and Abies alba Mill.]. GAMs outperformed GFs and GLMs in describing intra-annual wood formation dynamics, showing two left-skewed bell-shaped curves for division and enlargement, and a right-skewed bimodal curve for thickening. Cell residence times progressively decreased through the season for enlargement, whilst increasing late but rapidly for thickening. These patterns match changes in cell anatomical features within a tree ring, which allows the separation of earlywood and latewood into two distinct cell populations. A novel statistical approach is presented which renews our understanding of xylogenesis, a dynamic biological process in which the rate of cell production interplays with cell residence times in each developmental phase to create complex seasonal patterns.

  4. An additional layer in the low-latitude ionosphere in Indian longitudes: Total electron content observations and modeling

    NASA Astrophysics Data System (ADS)

    Thampi, Smitha V.; Balan, N.; Ravindran, Sudha; Pant, Tarun Kumar; Devasia, C. V.; Sreelatha, P.; Sridharan, R.; Bailey, G. J.

    2007-06-01

    The paper presents the observations and modeling of an additional layer in the low-latitude ionosphere in Indian longitudes. The signatures of the additional layer are observed as ledges or humps between the equatorial ionization anomaly trough and crest (EIA) in the latitudinal profiles of total electron content (TEC), measured using a single ground-based beacon receiver located at Trivandrum (8.5°N, 77°E, dip 0.5°N) in India. The ground-based ionograms also show the presence of the so-called F3 layer for a short duration corresponding to these signatures, and the layer is found to drift upward to the topside ionosphere. The study provides first observational evidence that the so-called "humps" in the latitudinal variation of TEC are nothing but the upward propagating F3 layer. This conclusion is supported by theoretical modeling using the Sheffield University Plasmasphere Ionosphere Model. It is shown that upward ExB drift and strong equatorward neutral wind (perturbed by atmospheric waves) can produce the humps in the latitudinal variation of TEC through the reduction in the downward diffusion of ionization along geomagnetic field lines. The model results also show that the F3 layer drifts to the topside and forms topside ledges.

  5. Modeling air quality over China: Results from the Panda project

    NASA Astrophysics Data System (ADS)

    Katinka Petersen, Anna; Bouarar, Idir; Brasseur, Guy; Granier, Claire; Xie, Ying; Wang, Lili; Wang, Xuemei

    2015-04-01

    China faces strong air pollution problems related to rapid economic development in the past decade and increasing demand for energy. Air quality monitoring stations often report high levels of particle matter and ozone all over the country. Knowing its long-term health impacts, air pollution became then a pressing problem not only in China but also in other Asian countries. The PANDA project is a result of cooperation between scientists from Europe and China who joined their efforts for a better understanding of the processes controlling air pollution in China, improve methods for monitoring air quality and elaborate indicators in support of European and Chinese policies. A modeling system of air pollution is being setup within the PANDA project and include advanced global (MACC, EMEP) and regional (WRF-Chem, EMEP) meteorological and chemical models to analyze and monitor air quality in China. The poster describes the accomplishments obtained within the first year of the project. Model simulations for January and July 2010 are evaluated with satellite measurements (SCIAMACHY NO2 and MOPITT CO) and in-situ data (O3, CO, NOx, PM10 and PM2.5) observed at several surface stations in China. Using the WRF-Chem model, we investigate the sensitivity of the model performance to emissions (MACCity, HTAPv2), horizontal resolution (60km, 20km) and choice of initial and boundary conditions.

  6. Non-shock initiation model for explosive families : experimental results.

    SciTech Connect

    Anderson, Mark U.; Jensen, Charles B.; Todd, Steven N.; Hugh, Chance G.; Caipen, Terry L.

    2010-03-01

    The 'DaMaGe-Initiated-Reaction' (DMGIR) computational model has been developed to predict the response of high explosives to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of a reaction in the explosive, and its growth to detonation. Specifically designed experiments were used to study the initiation process of each explosive family with embedded shock sensors and optical diagnostics. The experimental portion of this model development began with a study of PBXN-5 to develop DMGIR model coefficients for the rigid plastic bonded family, followed by studies of the cast, and bulk-moldable explosive families. The experimental results show an initiation mechanism that is related to input energy and material damage, with well defined initiation thresholds for each explosive family. These initiation details will extend the predictive capability of the DMGIR model from the rigid family into the cast and bulk-moldable families.

  7. Delta undulator model: Magnetic field and beam test results

    NASA Astrophysics Data System (ADS)

    Temnykh, A.; Babzien, M.; Davis, D.; Fedurin, M.; Kusche, K.; Park, J.; Yakimenko, V.

    2011-09-01

    A novel type of in-vacuum Elliptical Polarization Undulator (EPU) magnet optimized for linac beam (Delta undulator) was developed at the Laboratory for Elementary-Particle Physics (LEPP) at Cornell University as part of insertion device development for the future Cornell 5 GeV Energy Recovery Source of coherent hard X-rays [1,7]. To evaluate mechanical, vacuum and magnetic properties of the magnet, a short 30 cm model with a 5 mm diameter round gap and a 2.4 cm period was built and tested in LEPP. The beam test of the Delta undulator model was conducted at Accelerator Test Facility (ATF) in BNL with ˜60 MeV linac beam. The beam testing results confirmed basic properties of the undulator magnet obtained through the magnetic field measurement. In the paper we describe the magnet design, techniques and setups used for the magnetic field measurement and the beam testing results.

  8. Multinomial additive hazard model to assess the disability burden using cross-sectional data.

    PubMed

    Yokota, Renata T C; Van Oyen, Herman; Looman, Caspar W N; Nusselder, Wilma J; Otava, Martin; Kifle, Yimer Wasihun; Molenberghs, Geert

    2017-03-23

    Population aging is accompanied by the burden of chronic diseases and disability. Chronic diseases are among the main causes of disability, which is associated with poor quality of life and high health care costs in the elderly. The identification of which chronic diseases contribute most to the disability prevalence is important to reduce the burden. Although longitudinal studies can be considered the gold standard to assess the causes of disability, they are costly and often with restricted sample size. Thus, the use of cross-sectional data under certain assumptions has become a popular alternative. Among the existing methods based on cross-sectional data, the attribution method, which was originally developed for binary disability outcomes, is an attractive option, as it enables the partition of disability into the additive contribution of chronic diseases, taking into account multimorbidity and that disability can be present even in the absence of disease. In this paper, we propose an extension of the attribution method to multinomial responses, since disability is often measured as a multicategory variable in most surveys, representing different severity levels. The R function constrOptim is used to maximize the multinomial log-likelihood function subject to a linear inequality constraint. Our simulation study indicates overall good performance of the model, without convergence problems. However, the model must be used with care for populations with low marginal disability probabilities and with high sum of conditional probabilities, especially with small sample size. For illustration, we apply the model to the data of the Belgian Health Interview Surveys.

  9. A Comparative Kirkwood-Buff Study of Aqueous Methanol Solutions Modeled by the CHARMM Additive and Drude Polarizable Force Fields

    PubMed Central

    Lin, Bin; He, Xibing; MacKerell, Alexander D.

    2013-01-01

    A comparative study on aqueous methanol solutions modeled by the CHARMM additive and Drude polarizable force fields was carried out by employing Kirkwood-Buff analysis. It was shown that both models reproduced the experimental Kirkwood-Buff integrals and excess coordination numbers adequately well over the entire concentration range. The Drude model showed significant improvement over the additive model in solution densities, partial molar volumes, excess molar volumes, concentration-dependent diffusion constants, and dielectric constants. However, the additive model performed somewhat better than the Drude model in reproducing the activity derivative, excess molar Gibbs energy and excess molar enthalpy of mixing. This is due to the additive achieving a better balance among solute-solute, solute-solvent, and solvent-solvent interactions, indicating the potential for improvements in the Drude polarizable alcohol model. PMID:23947568

  10. Analytical results for a three-phase traffic model.

    PubMed

    Huang, Ding-wei

    2003-10-01

    We study analytically a cellular automaton model, which is able to present three different traffic phases on a homogeneous highway. The characteristics displayed in the fundamental diagram can be well discerned by analyzing the evolution of density configurations. Analytical expressions for the traffic flow and shock speed are obtained. The synchronized flow in the intermediate-density region is the result of aggressive driving scheme and determined mainly by the stochastic noise.

  11. Some results on hyperscaling in the 3D Ising model

    SciTech Connect

    Baker, G.A. Jr.; Kawashima, Naoki

    1995-09-01

    The authors review exact studies on finite-sized 2 dimensional Ising models and show that the point for an infinite-sized model at the critical temperature is a point of nonuniform approach in the temperature-size plane. They also illuminate some strong effects of finite-size on quantities which do not diverge at the critical point. They then review Monte Carlo studies for 3 dimensional Ising models of various sizes (L = 2--100) at various temperatures. From these results they find that the data for the renormalized coupling constant collapses nicely when plotted against the correlation length, determined in a system of edge length L, divided by L. They also find that {zeta}{sub L}/L {ge} 0.26 is definitely too large for reliable studies of the critical value, g*, of the renormalized coupling constant. They have reasonable evidence that {zeta}{sub L}/L {approx} 0.1 is adequate for results that are within one percent of those for the infinite system size. On this basis, they have conducted a series of Monte Carlo calculations with this condition imposed. These calculations were made practical by the development of improved estimators for use in the Swendsen-Wang cluster method. The authors found from these results, coupled with a reversed limit computation (size increases with the temperature fixed at the critical temperature), that g* > 0, although there may well be a sharp downward drop in g as the critical temperature is approached in accord with the predictions of series analysis. The results support the validity of hyperscaling in the 3 dimensional Ising model.

  12. Acoustic results of the Boeing model 360 whirl tower test

    NASA Technical Reports Server (NTRS)

    Watts, Michael E.; Jordan, David

    1990-01-01

    An evaluation is presented for whirl tower test results of the Model 360 helicopter's advanced, high-performance four-bladed composite rotor system intended to facilitate over-200-knot flight. During these performance measurements, acoustic data were acquired by seven microphones. A comparison of whirl-tower tests with theory indicate that theoretical prediction accuracies vary with both microphone position and the inclusion of ground reflection. Prediction errors varied from 0 to 40 percent of the measured signal-to-peak amplitude.

  13. Exact results for the one dimensional asymmetric exclusion model

    NASA Astrophysics Data System (ADS)

    Derrida, B.; Evans, M. R.; Hakim, V.; Pasquier, V.

    1993-11-01

    The asymmetric exclusion model describes a system of particles hopping in a preferred direction with hard core repulsion. These particles can be thought of as charged particles in a field, as steps of an interface, as cars in a queue. Several exact results concerning the steady state of this system have been obtained recently. The solution consists of representing the weights of the configurations in the steady state as products of non-commuting matrices.

  14. Assessment of the improvements in accuracy of aerosol characterization resulted from additions of polarimetric measurements to intensity-only observations using GRASP algorithm (Invited)

    NASA Astrophysics Data System (ADS)

    Dubovik, O.; Litvinov, P.; Lapyonok, T.; Herman, M.; Fedorenko, A.; Lopatin, A.; Goloub, P.; Ducos, F.; Aspetsberger, M.; Planer, W.; Federspiel, C.

    2013-12-01

    During last few years we were developing GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm designed for the enhanced characterization of aerosol properties from spectral, multi-angular polarimetric remote sensing observations. The concept of GRASP essentially relies on the accumulated positive research heritage from previous remote sensing aerosol retrieval developments, in particular those from the AERONET and POLDER retrieval activities. The details of the algorithm are described by Dubovik et al. (Atmos. Meas. Tech., 4, 975-1018, 2011). The GRASP retrieves properties of both aerosol and land surface reflectance in cloud-free environments. It is based on highly advanced statistically optimized fitting and deduces nearly 50 unknowns for each observed site. The algorithm derives a similar set of aerosol parameters as AERONET including detailed particle size distribution, the spectrally dependent the complex index of refraction and the fraction of non-spherical particles. The algorithm uses detailed aerosol and surface models and fully accounts for all multiple interactions of scattered solar light with aerosol, gases and the underlying surface. All calculations are done on-line without using traditional look-up tables. In addition, the algorithm uses the new multi-pixel retrieval concept - a simultaneous fitting of a large group of pixels with additional constraints limiting the time variability of surface properties and spatial variability of aerosol properties. This principle is expected to result in higher consistency and accuracy of aerosol products compare to conventional approaches especially over bright surfaces where information content of satellite observations in respect to aerosol properties is limited. The GRASP is a highly versatile algorithm that allows input from both satellite and ground-based measurements. It also has essential flexibility in measurement processing. For example, if observation data set includes spectral

  15. Modeling the Effect of Geomorphic Change Triggered by Large Wood Addition on Salmon Habitat in a Forested Coastal Watershed

    NASA Astrophysics Data System (ADS)

    Bair, R.; Segura, C.; Lorion, C.

    2015-12-01

    Large wood (LW) additions are often part of fish habitat restorations in the PNW where historic forest clear-cutting limited natural wood recruitment. These efforts' relative successes are rarely reported in terms of ecological significance to different life stages of fish. Understanding the effectiveness of LW additions will contribute to successfully managing forest land. In this study we quantify the geomorphic change of a restoration project involving LW additions to three alluvial reaches in Mill Creek, OR. The reaches are 110-130m in plane-bed morphology and drain 2-16km2. We quantify the change in available habitat to different life stages of coho salmon in terms of velocity (v), shear stress (t), flow depth, and grain size distributions (GSD) considering existing thresholds in the literature for acceptable habitat. Flow conditions before and after LW additions are assessed using a 2D hydrodynamic model (FaSTMECH). Model inputs include detailed channel topography, discharge, and surface GSD. The spatial-temporal variability of sediment transport was also quantified based the modeled t distributions and the GSD to document changes in the overall geomorphic regime. Initial modeling results for pre wood conditions show mean t and v values ranging between 0 and 26N/m2 and between 0 and 2.4m/s, respectively for up to bankfull flow (Qbf). The distributions of both t and v become progressively wider and peak at higher values as flow increases with the notable exception at Qbf for which the area of low velocity increases noticeably. The spatial distributions of velocity results indicates that the extent of suitable habitat for adult coho decreased by 18% between flows 30 and 55% of BF. However the area of suitable habitat increased by 15% between 0.55Qbf and Qbf as the flow spreads from the channel into the floodplain. We expect the LW will enhance floodplain connectivity and thus available habitat by creating additional areas of low v during winter flows.

  16. High SO{sub 2} removal efficiency testing. Topical report - results of sodium formate additive tests at New York State Electric & Gas Corporation`s Kintigh Station

    SciTech Connect

    Murphy, J.

    1997-02-14

    Tests were conducted at New York State Gas & Electric`s (NYSEG`s) Kintigh Station to evaluate options for achieving high sulfur dioxide (SO{sub 2}) removal efficiency in the wet limestone flue gas desulfurization (FGD) system. This test program was one of six conducted by the U.S. Department of Energy to evaluate low-capital-cost upgrades to existing FGD systems as a means for utilities to comply with the requirements of the 1990 Clean Air Act Amendments. The upgrade option tested at Kintigh was sodium formate additive. Results from the tests were used to calibrate the Electric Power Research Institute`s (EPRI) FGD PRocess Integration and Simulation Model (FGDPRISM) to the Kintigh scrubber configuration. FGDPRISM was then used to predict system performance for evaluating conditions other than those tested. An economic evaluation was then done to determine the cost effectiveness of various high-efficiency upgrade options. These costs can be compared with the estimated market value of SO{sub 2} allowance or the expected costs of allowances generated by other means, such as fuel switching or new scrubbers, to arrive at the most cost-effective strategy for Clean Air Act compliance.

  17. WSA-ENLIL model results for understanding planetary system drivers

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Solomon, Sean C.; Slavin, James; Korth, Haje; Poh, GangKai; Odstrcil, Dusan; Zurbuchen, Thomas; Raines, Jim

    2012-07-01

    Analysis and interpretation of observations from planet-orbiting spacecraft often require a "solar wind forcing" index to provide appropriate inputs for magnetospheric modeling and to enable investigations that depend on the heliospheric environment of the planet. We have utilized the WSA-ENLIL solar wind modeling tool in order to calculate the values of interplanetary magnetic field (IMF) strength (B), flow velocity (V), density (N), and other derived quantities of relevance for solar wind--planetary interactions. We have, for example, taken this model output and compared upstream IMF and solar wind measurements to see how well the ENLIL model results compare with spacecraft measurements near 1 AU. We also have used the relatively high-time-resolution B-field data from MESSENGER to help estimate the strength of the product of the solar wind speed and southward IMF strength (Bs) at Mercury. This product VBs is the electric field that drives magnetospheric processes and can be compared with such phenomena as the occurrence of energetic particle bursts within the Mercury magnetosphere. This index can also be used to drive the global magnetohydrodynamic (MHD) and kinetic magnetosphere models that are being used to explore magnetospheric dynamics at Earth, Mercury, or other planets such as Mars. Moreover, this modeling is such that near-real time products can be produced in order to help assess magnetospheric behavior for planetary orbiters or other mission analysis and/or ground-based observational campaigns. We believe that this solar wind tool is a crucial step toward bringing heliospheric science expertise to bear on planetary exploration programs.

  18. Comparison of computationally frugal (linear) to expensive (nonlinear) methods for analyzing inverse modeling results

    NASA Astrophysics Data System (ADS)

    Mehl, S.; Foglia, L.; Hill, M. C.

    2009-12-01

    Methods for analyzing inverse modeling results can be separated into two categories: (1) linear methods, such as Cook’s D, which are computationally frugal and do not require additional model runs, and (2) nonlinear methods, such as cross validation, which are computationally more expensive because they generally require additional model runs. Depending on the type of nonlinear analysis performed, the additional runs can be the difference between 10’s of runs and 1000’s of runs. For example, cross-validation studies require the model to be recalibrated (the regression repeated) for each observation or set of observations analyzed. This can be computationally prohibitive if many observations or sets of observations are investigated and/or the model has many estimated parameters. A tradeoff exists between linear and nonlinear methods, with linear methods being computationally efficient, but the results being questioned when models are nonlinear. The trade offs between computational efficiency and accuracy are investigated by comparing results from several linear measures of observation importance (for example, Cook’s D, DFBETA’s) to their nonlinear counterparts based on cross validation. Examples from ground water models of the Maggia Valley in southern Switzerland are used to make comparisons. The models include representation of the stream-aquifer interaction and range from simple to complex, with associated modified Beale’s measure ranging from mildly nonlinear to highly nonlinear, respectively. These results demonstrate applicability and limitations of applying linear methods over a range of model complexity and linearity and can be used to better understand when the additional computation burden of nonlinear methods may be necessary.

  19. First Results of the Regional Earthquake Likelihood Models Experiment

    USGS Publications Warehouse

    Schorlemmer, D.; Zechar, J.D.; Werner, M.J.; Field, E.H.; Jackson, D.D.; Jordan, T.H.

    2010-01-01

    The ability to successfully predict the future behavior of a system is a strong indication that the system is well understood. Certainly many details of the earthquake system remain obscure, but several hypotheses related to earthquake occurrence and seismic hazard have been proffered, and predicting earthquake behavior is a worthy goal and demanded by society. Along these lines, one of the primary objectives of the Regional Earthquake Likelihood Models (RELM) working group was to formalize earthquake occurrence hypotheses in the form of prospective earthquake rate forecasts in California. RELM members, working in small research groups, developed more than a dozen 5-year forecasts; they also outlined a performance evaluation method and provided a conceptual description of a Testing Center in which to perform predictability experiments. Subsequently, researchers working within the Collaboratory for the Study of Earthquake Predictability (CSEP) have begun implementing Testing Centers in different locations worldwide, and the RELM predictability experiment-a truly prospective earthquake prediction effort-is underway within the U. S. branch of CSEP. The experiment, designed to compare time-invariant 5-year earthquake rate forecasts, is now approximately halfway to its completion. In this paper, we describe the models under evaluation and present, for the first time, preliminary results of this unique experiment. While these results are preliminary-the forecasts were meant for an application of 5 years-we find interesting results: most of the models are consistent with the observation and one model forecasts the distribution of earthquakes best. We discuss the observed sample of target earthquakes in the context of historical seismicity within the testing region, highlight potential pitfalls of the current tests, and suggest plans for future revisions to experiments such as this one. ?? 2010 The Author(s).

  20. Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants

    PubMed Central

    Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

    2014-01-01

    Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier–Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements. PMID:24664988

  1. Propagation modeling results for narrow-beam undersea laser communications

    NASA Astrophysics Data System (ADS)

    Fletcher, Andrew S.; Hardy, Nicholas D.; Hamilton, Scott A.

    2016-03-01

    Communication links through ocean waters are challenging due to undersea propagation physics. Undersea optical communications at blue or green wavelengths can achieve high data rates (megabit- to gigabit-per-second class links) despite the challenging undersea medium. Absorption and scattering in ocean waters attenuate optical signals and distort the waveform through dense multipath. The exponential propagation loss and the temporal spread due to multipath limit the achievable link distance and data rate. In this paper, we describe the Monte Carlo modeling of the undersea scattering and absorption channel. We model photon signal attenuation levels, spatial photon distributions, time of arrival statistics, and angle of arrival statistics for a variety of lasercom scenarios through both clear and turbid water environments. Modeling results inform the design options for an undersea optical communication system, particularly illustrating the advantages of narrow-beam lasers compared to wide beam methods (e.g. LED sources). The modeled pupil plane and focal plane photon arrival distributions enable beam tracking techniques for robust pointing solutions, even in highly scattering harbor waters. Laser communication with collimated beams maximizes the photon transfer through the scattering medium and enables spatial and temporal filters to minimize waveform distortion and background interference.

  2. Higher plant modelling for life support applications: first results of a simple mechanistic model

    NASA Astrophysics Data System (ADS)

    Hezard, Pauline; Dussap, Claude-Gilles; Sasidharan L, Swathy

    2012-07-01

    In the case of closed ecological life support systems, the air and water regeneration and food production are performed using microorganisms and higher plants. Wheat, rice, soybean, lettuce, tomato or other types of eatable annual plants produce fresh food while recycling CO2 into breathable oxygen. Additionally, they evaporate a large quantity of water, which can be condensed and used as potable water. This shows that recycling functions of air revitalization and food production are completely linked. Consequently, the control of a growth chamber for higher plant production has to be performed with efficient mechanistic models, in order to ensure a realistic prediction of plant behaviour, water and gas recycling whatever the environmental conditions. Purely mechanistic models of plant production in controlled environments are not available yet. This is the reason why new models must be developed and validated. This work concerns the design and test of a simplified version of a mathematical model coupling plant architecture and mass balance purposes in order to compare its results with available data of lettuce grown in closed and controlled chambers. The carbon exchange rate, water absorption and evaporation rate, biomass fresh weight as well as leaf surface are modelled and compared with available data. The model consists of four modules. The first one evaluates plant architecture, like total leaf surface, leaf area index and stem length data. The second one calculates the rate of matter and energy exchange depending on architectural and environmental data: light absorption in the canopy, CO2 uptake or release, water uptake and evapotranspiration. The third module evaluates which of the previous rates is limiting overall biomass growth; and the last one calculates biomass growth rate depending on matter exchange rates, using a global stoichiometric equation. All these rates are a set of differential equations, which are integrated with time in order to provide

  3. Modeling results for the ITER cryogenic fore pump

    NASA Astrophysics Data System (ADS)

    Zhang, D. S.; Miller, F. K.; Pfotenhauer, J. M.

    2014-01-01

    The cryogenic fore pump (CFP) is designed for ITER to collect and compress hydrogen isotopes during the regeneration process of torus cryopumps. Different from common cryopumps, the ITER-CFP works in the viscous flow regime. As a result, both adsorption boundary conditions and transport phenomena contribute unique features to the pump performance. In this report, the physical mechanisms of cryopumping are studied, especially the diffusion-adsorption process and these are coupled with standard equations of species, momentum and energy balance, as well as the equation of state. Numerical models are developed, which include highly coupled non-linear conservation equations of species, momentum and energy and equation of state. Thermal and kinetic properties are treated as functions of temperature, pressure, and composition. To solve such a set of equations, a novel numerical technique, identified as the Group-Member numerical technique is proposed. It is presented here a 1D numerical model. The results include comparison with the experimental data of pure hydrogen flow and a prediction for hydrogen flow with trace helium. An advanced 2D model and detailed explanation of the Group-Member technique are to be presented in following papers.

  4. Modeling extracellular electrical stimulation: II. Computational validation and numerical results.

    PubMed

    Tahayori, Bahman; Meffin, Hamish; Dokos, Socrates; Burkitt, Anthony N; Grayden, David B

    2012-12-01

    The validity of approximate equations describing the membrane potential under extracellular electrical stimulation (Meffin et al 2012 J. Neural Eng. 9 065005) is investigated through finite element analysis in this paper. To this end, the finite element method is used to simulate a cylindrical neurite under extracellular stimulation. Laplace's equations with appropriate boundary conditions are solved numerically in three dimensions and the results are compared to the approximate analytic solutions. Simulation results are in agreement with the approximate analytic expressions for longitudinal and transverse modes of stimulation. The range of validity of the equations describing the membrane potential for different values of stimulation and neurite parameters are presented as well. The results indicate that the analytic approach can be used to model extracellular electrical stimulation for realistic physiological parameters with a high level of accuracy.

  5. A novel visualization model for web search results.

    PubMed

    Nguyen, Tien N; Zhang, Jin

    2006-01-01

    This paper presents an interactive visualization system, named WebSearchViz, for visualizing the Web search results and acilitating users' navigation and exploration. The metaphor in our model is the solar system with its planets and asteroids revolving around the sun. Location, color, movement, and spatial distance of objects in the visual space are used to represent the semantic relationships between a query and relevant Web pages. Especially, the movement of objects and their speeds add a new dimension to the visual space, illustrating the degree of relevance among a query and Web search results in the context of users' subjects of interest. By interacting with the visual space, users are able to observe the semantic relevance between a query and a resulting Web page with respect to their subjects of interest, context information, or concern. Users' subjects of interest can be dynamically changed, redefined, added, or deleted from the visual space.

  6. Comparison of Blade-Strike Modeling Results with Empirical Data

    SciTech Connect

    Carlson, Thomas J.; Ploskey, Gene R.

    2004-05-06

    This study is the initial stage of further investigation into the dynamics of injury to fish during passage through a turbine runner. As part of the study, Pacific Northwest National Laboratory (PNNL) estimated the probability of blade strike, and associated injury, as a function of fish length and turbine operating geometry at two adjacent turbines in Powerhouse 1 of Bonneville Dam. Units 5 and 6 had identical intakes, stay vanes, wicket gates, and draft tubes, but Unit 6 had a new runner and curved discharge ring to minimize gaps between the runner hub and blades and between the blade tips and discharge ring. We used a mathematical model to predict blade strike associated with two Kaplan turbines and compared results with empirical data from biological tests conducted in 1999 and 2000. Blade-strike models take into consideration the geometry of the turbine blades and discharges as well as fish length, orientation, and distribution along the runner.

  7. Synthesis, Characterization, Molecular Modeling, and DNA Interaction Studies of Copper Complex Containing Food Additive Carmoisine Dye.

    PubMed

    Shahabadi, Nahid; Akbari, Alireza; Jamshidbeigi, Mina; Khodarahmi, Reza

    2016-06-02

    A copper complex of carmoisine dye; [Cu(carmoisine)2(H2O)2]; was synthesized and characterized by using physico-chemical and spectroscopic methods. The binding of this complex with calf thymus (ct) DNA was investigated by circular dichroism, absorption studies, emission spectroscopy, and viscosity measurements. UV-vis results confirmed that the Cu complex interacted with DNA to form a ground-state complex and the observed binding constant (2× 10(4) M(-1)) is more in keeping with the groove bindings with DNA. Furthermore, the viscosity measurement result showed that the addition of complex causes no significant change on DNA viscosity and it indicated that the intercalation mode is ruled out. The thermodynamic parameters are calculated by van't Hoff equation, which demonstrated that hydrogen bonds and van der Waals interactions played major roles in the reaction. The results of circular dichroism (CD) suggested that the complex can change the conformation of DNA from B-like form toward A-like conformation. The cytotoxicity studies of the carmoisine dye and its copper complex indicated that both of them had anticancer effects on HT-29 (colon cancer) cell line and they may be new candidates for treatment of the colon cancer.

  8. A Revised Sensitivity Model for Cassini INMS: Results at Titan

    NASA Astrophysics Data System (ADS)

    Teolis, B. D.; Niemann, H. B.; Waite, J. H.; Gell, D. A.; Perryman, R. S.; Kasprzak, W. T.; Mandt, K. E.; Yelle, R. V.; Lee, A. Y.; Pelletier, F. J.; Miller, G. P.; Young, D. T.; Bell, J. M.; Magee, B. A.; Patrick, E. L.; Grimes, J.; Fletcher, G. G.; Vuitton, V.

    2015-07-01

    Cassini Ion Neutral Mass Spectrometer (INMS) measurements from roughly a hundred Titan encounters over the Cassini mission yield neutral and ion densities systematically lower, by factors approximately 2 to 3, than estimates from several other spacecraft systems, including the Attitude and Articulation Control System, and Navigation system. In this paper we present a new INMS instrument sensitivity model, obtained by re-analyzing (1) the capture and transmission of neutral gas through the instrument, and (2) the detector gain reduction during pre-launch testing. By correcting for an under-estimation of gas leakage out of the instrument into space by the original calibration model, and adjusting for the gain change, the new model brings INMS densities into much closer agreement with the other Cassini systems. Accordingly, the INMS ion densities are revised upward by a constant detector sensitivity correction factor of 1.55±21 %, while the neutral sensitivities have a complex instrument pointing direction dependence, due (mostly) to the effect of the INMS vent and antechamber-to-closed source tube. In the special case of on-ram pointing the neutral densities are revised upward by a constant factor of 2.2±23 %. The corrected neutral and ion sensitivities given here are applicable to all previously published INMS results at Titan, Enceladus and elsewhere in the Saturn system. The new model gives reliable densities at high ram angles, in some cases above 90 degrees, thereby expanding the list of Titan flybys from which INMS densities may be extracted. We apply the model to obtain accurate densities from several off-ram Titan flybys which gave unusual neutral density vs. altitude profiles, or unreasonably high densities, with the original calibration.

  9. Statistical inference for the additive hazards model under outcome-dependent sampling.

    PubMed

    Yu, Jichang; Liu, Yanyan; Sandler, Dale P; Zhou, Haibo

    2015-09-01

    Cost-effective study design and proper inference procedures for data from such designs are always of particular interests to study investigators. In this article, we propose a biased sampling scheme, an outcome-dependent sampling (ODS) design for survival data with right censoring under the additive hazards model. We develop a weighted pseudo-score estimator for the regression parameters for the proposed design and derive the asymptotic properties of the proposed estimator. We also provide some suggestions for using the proposed method by evaluating the relative efficiency of the proposed method against simple random sampling design and derive the optimal allocation of the subsamples for the proposed design. Simulation studies show that the proposed ODS design is more powerful than other existing designs and the proposed estimator is more efficient than other estimators. We apply our method to analyze a cancer study conducted at NIEHS, the Cancer Incidence and Mortality of Uranium Miners Study, to study the risk of radon exposure to cancer.

  10. Statistical inference for the additive hazards model under outcome-dependent sampling

    PubMed Central

    Yu, Jichang; Liu, Yanyan; Sandler, Dale P.; Zhou, Haibo

    2015-01-01

    Cost-effective study design and proper inference procedures for data from such designs are always of particular interests to study investigators. In this article, we propose a biased sampling scheme, an outcome-dependent sampling (ODS) design for survival data with right censoring under the additive hazards model. We develop a weighted pseudo-score estimator for the regression parameters for the proposed design and derive the asymptotic properties of the proposed estimator. We also provide some suggestions for using the proposed method by evaluating the relative efficiency of the proposed method against simple random sampling design and derive the optimal allocation of the subsamples for the proposed design. Simulation studies show that the proposed ODS design is more powerful than other existing designs and the proposed estimator is more efficient than other estimators. We apply our method to analyze a cancer study conducted at NIEHS, the Cancer Incidence and Mortality of Uranium Miners Study, to study the risk of radon exposure to cancer. PMID:26379363

  11. Results.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

  12. High frequency transcutaneous electrical nerve stimulation with diphenidol administration results in an additive antiallodynic effect in rats following chronic constriction injury.

    PubMed

    Lin, Heng-Teng; Chiu, Chong-Chi; Wang, Jhi-Joung; Hung, Ching-Hsia; Chen, Yu-Wen

    2015-03-04

    The impact of coadministration of transcutaneous electrical nerve stimulation (TENS) and diphenidol is not well established. Here we estimated the effects of diphenidol in combination with TENS on mechanical allodynia and tumor necrosis factor-α (TNF-α) expression. Using an animal chronic constriction injury (CCI) model, the rat was estimated for evidence of mechanical sensitivity via von Frey hair stimulation and TNF-α expression in the sciatic nerve using the ELISA assay. High frequency (100Hz) TENS or intraperitoneal injection of diphenidol (2.0μmol/kg) was applied daily, starting on postoperative day 1 (POD1) and lasting for the next 13 days. We demonstrated that both high frequency TENS and diphenidol groups had an increase in mechanical withdrawal thresholds of 60%. Coadministration of high frequency TENS and diphenidol gives better results of paw withdrawal thresholds in comparison with high frequency TENS alone or diphenidol alone. Both diphenidol and coadministration of high frequency TENS with diphenidol groups showed a significant reduction of the TNF-α level compared with the CCI or HFS group (P<0.05) in the sciatic nerve on POD7, whereas the CCI or high frequency TENS group exhibited a higher TNF-α level than the sham group (P<0.05). Our resulting data revealed that diphenidol alone, high frequency TENS alone, and the combination produced a reduction of neuropathic allodynia. Both diphenidol and the combination of diphenidol with high frequency TENS inhibited TNF-α expression. A moderately effective dose of diphenidol appeared to have an additive effect with high frequency TENS. Therefore, multidisciplinary treatments could be considered for this kind of mechanical allodynia.

  13. A "Kane's Dynamics" Model for the Active Rack Isolation System. Part 3; Addition of Umbilicals to the Nonlinear Model

    NASA Technical Reports Server (NTRS)

    Rupert, J. K.; Hampton, R. D.; Beech, G. S.

    2005-01-01

    In the late 1980s, microgravity researchers began to voice their concern that umbilical-transmitted energy could significantly degrade the acceleration environment of microgravity space science experiments onboard manned spacecraft. Since umbilicals are necessary for many experiments, control designers began to seek ways to compensate for these "indirect" disturbances. Hampton, et al., used the Kane s method to develop a model of the active rack isolation system (ARIS) that includes (1) actuator control forces, (2) direct disturbance forces, and (3) indirect, actuator-transmitted disturbances. Their model does not, however, include the indirect, umbilical-transmitted disturbances. Since the umbilical stiffnesses are not negligible, these indirect disturbances must be included in the model. Until the umbilicals have been appropriately included, the model will be incomplete. This Technical Memorandum presents a nonlinear model of ARIS with umbilicals included. Model verification was achieved by utilizing two commercial-off-the-shelf software tools. Various forces and moments were applied to the model to yield simulated responses of the system. Plots of the simulation results show how various critical points on an ARIS-outfitted international standard payload rack behave under the application of direct disturbances, indirect disturbances, and control forces. Simulations also show system response to a variety of initial conditions.

  14. Loss of spent fuel pool cooling PRA: Model and results

    SciTech Connect

    Siu, N.; Khericha, S.; Conroy, S.; Beck, S.; Blackman, H.

    1996-09-01

    This letter report documents models for quantifying the likelihood of loss of spent fuel pool cooling; models for identifying post-boiling scenarios that lead to core damage; qualitative and quantitative results generated for a selected plant that account for plant design and operational practices; a comparison of these results and those generated from earlier studies; and a review of available data on spent fuel pool accidents. The results of this study show that for a representative two-unit boiling water reactor, the annual probability of spent fuel pool boiling is 5 {times} 10{sup {minus}5} and the annual probability of flooding associated with loss of spent fuel pool cooling scenarios is 1 {times} 10{sup {minus}3}. Qualitative arguments are provided to show that the likelihood of core damage due to spent fuel pool boiling accidents is low for most US commercial nuclear power plants. It is also shown that, depending on the design characteristics of a given plant, the likelihood of either: (a) core damage due to spent fuel pool-associated flooding, or (b) spent fuel damage due to pool dryout, may not be negligible.

  15. Geochemical controls on shale groundwaters: Results of reaction path modeling

    SciTech Connect

    Von Damm, K.L.; VandenBrook, A.J.

    1989-03-01

    The EQ3NR/EQ6 geochemical modeling code was used to simulate the reaction of several shale mineralogies with different groundwater compositions in order to elucidate changes that may occur in both the groundwater compositions, and rock mineralogies and compositions under conditions which may be encountered in a high-level radioactive waste repository. Shales with primarily illitic or smectitic compositions were the focus of this study. The reactions were run at the ambient temperatures of the groundwaters and to temperatures as high as 250/degree/C, the approximate temperature maximum expected in a repository. All modeling assumed that equilibrium was achieved and treated the rock and water assemblage as a closed system. Graphite was used as a proxy mineral for organic matter in the shales. The results show that the presence of even a very small amount of reducing mineral has a large influence on the redox state of the groundwaters, and that either pyrite or graphite provides essentially the same results, with slight differences in dissolved C, Fe and S concentrations. The thermodynamic data base is inadequate at the present time to fully evaluate the speciation of dissolved carbon, due to the paucity of thermodynamic data for organic compounds. In the illitic cases the groundwaters resulting from interaction at elevated temperatures are acid, while the smectitic cases remain alkaline, although the final equilibrium mineral assemblages are quite similar. 10 refs., 8 figs., 15 tabs.

  16. Comparison of ENDF/B-VII.1 and ENDF/B-VII.0 Results for the Expanded Criticality Validation Suite for MCNP and for Selected Additional Criticality Benchmarks

    NASA Astrophysics Data System (ADS)

    Mosteller, R.

    2014-04-01

    Results obtained with the MCNP5 Monte Carlo code and the ENDF/B-VII.1 and ENDF/B-VII.0 nuclear data libraries have been compared for the 119 benchmarks in the expanded criticality validation suite for MCNP and for 23 additional benchmarks. ENDF/B-VII.1 was found to produce improvements relative to ENDF/B-VII.0 for benchmarks that contain significant amounts of tungsten, zirconium, cadmium, or beryllium, although the results for the benchmarks with beryllium suggest that further improvement still may be needed. In addition, a number of deficiencies previously identified for ENDF/B-VII.0 still remain in ENDF/B-VII.1.

  17. Detecting Departure From Additivity Along a Fixed-Ratio Mixture Ray With a Piecewise Model for Dose and Interaction Thresholds

    PubMed Central

    Gennings, Chris; Wagner, Elizabeth D.; Simmons, Jane Ellen; Plewa, Michael J.

    2010-01-01

    For mixtures of many chemicals, a ray design based on a relevant, fixed mixing ratio is useful for detecting departure from additivity. Methods for detecting departure involve modeling the response as a function of total dose along the ray. For mixtures with many components, the interaction may be dose dependent. Therefore, we have developed the use of a three-segment model containing both a dose threshold and an interaction threshold. Prior to the dose threshold, the response is that of background; between the dose threshold and the interaction threshold, an additive relationship exists; the model allows for departure from additivity beyond the interaction threshold. With such a model, we can conduct a hypothesis test of additivity, as well as a test for a region of additivity. The methods are illustrated with cytotoxicity data that arise when Chinese hamster ovary cells are exposed to a mixture of nine haloacetic acids. PMID:21359103

  18. Additional application of the NASCAP code. Volume 2: SEPS, ion thruster neutralization and electrostatic antenna model

    NASA Technical Reports Server (NTRS)

    Katz, I.; Cassidy, J. J.; Mandell, M. J.; Parks, D. E.; Schnuelle, G. W.; Stannard, P. R.; Steen, P. G.

    1981-01-01

    The interactions of spacecraft systems with the surrounding plasma environment were studied analytically for three cases of current interest: calculating the impact of spacecraft generated plasmas on the main power system of a baseline solar electric propulsion stage (SEPS), modeling the physics of the neutralization of an ion thruster beam by a plasma bridge, and examining the physical and electrical effects of orbital ambient plasmas on the operation of an electrostatically controlled membrane mirror. In order to perform these studies, the NASA charging analyzer program (NASCAP) was used as well as several other computer models and analytical estimates. The main result of the SEPS study was to show how charge exchange ion expansion can create a conducting channel between the thrusters and the solar arrays. A fluid-like model was able to predict plasma potentials and temperatures measured near the main beam of an ion thruster and in the vicinity of a hollow cathode neutralizer. Power losses due to plasma currents were shown to be substantial for several proposed electrostatic antenna designs.

  19. SLS Scale Model Acoustic Test Liftoff Results and Comparisons

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, Douglas; Giacomoni, Clothilde

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible design phase test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments.

  20. Updated Results from the Titan Global Ionosphere-Thermosphere Model

    NASA Astrophysics Data System (ADS)

    Bell, J. M.; Waite, J. H.; Mandt, K.; Magee, B.

    2012-12-01

    We present updated results from the Titan Global Ionosphere-Thermosphere Model (T-GITM) (Bell et al. [2010a]). We use both a 1-D and 3-D version of T-GITM to address simultaneously the escape of methane and molecular hydrogen from Titan's upper atmosphere. We will compare simulated fields with Cassini Ion Neutral Mass Spectrometer (INMS) neutral and ion density data for calibration and validation. We will put our current estimates for atmospheric escape within the context of previous work (e.g. Cui et al. [2008, 2011], Strobel et al. [2010], Tucker et al. [2009], and Yelle et al. [2008]).

  1. Current results on the asymptotics of dynamo models

    NASA Astrophysics Data System (ADS)

    Popova, H. P.

    2016-06-01

    Magnetic field generation and evolution models that are capable of describing a large body of observational material are currently available for different celestial bodies. Despite recent decades of great success in numerical magnetic hydrodynamics and in detailed research into some specific problems, asymptotic methods still have to be used to clarify the magnetic field generation mechanism in dynamo theory. In this review, current asymptotic methods are presented together with the results of their application to the simulation of solar, stellar, and galactic magnetic activities.

  2. Bifurcation analysis of a population model and the resulting SIS epidemic model with delay

    NASA Astrophysics Data System (ADS)

    Wei, Junjie; Zou, Xingfu

    2006-12-01

    This paper deals with the model for matured population growth proposed in Cooke et al. [Interaction of matiration delay and nonlinear birth in population and epidemic models, J. Math. Biol. 39 (1999) 332-352] and the resulting SIS epidemic model. The dynamics of these two models are still largely undetermined, and in this paper, we perform some bifurcation analysis to the models. By applying the global bifurcation theory for functional differential equations, we are able to show that the population model allows multiple periodic solutions. For the SIS model, we obtain some local bifurcation results and derive formulas for determining the bifurcation direction and the stability of the bifurcated periodic solution.

  3. Solvation free energy of the peptide group: its model dependence and implications for the additive-transfer free-energy model of protein stability.

    PubMed

    Tomar, Dheeraj S; Asthagiri, D; Weber, Valéry

    2013-09-17

    The group-additive decomposition of the unfolding free energy of a protein in an osmolyte solution relative to that in water poses a fundamental paradox: whereas the decomposition describes the experimental results rather well, theory suggests that a group-additive decomposition of free energies is, in general, not valid. In a step toward resolving this paradox, here we study the peptide-group transfer free energy. We calculate the vacuum-to-solvent (solvation) free energies of (Gly)n and cyclic diglycine (cGG) and analyze the data according to experimental protocol. The solvation free energies of (Gly)n are linear in n, suggesting group additivity. However, the slope interpreted as the free energy of a peptide unit differs from that for cGG scaled by a factor of half, emphasizing the context dependence of solvation. However, the water-to-osmolyte transfer free energies of the peptide unit are relatively independent of the peptide model, as observed experimentally. To understand these observations, a way to assess the contribution to the solvation free energy of solvent-mediated correlation between distinct groups is developed. We show that linearity of solvation free energy with n is a consequence of uniformity of the correlation contributions, with apparent group-additive behavior in the water-to-osmolyte transfer arising due to their cancellation. Implications for inferring molecular mechanisms of solvent effects on protein stability on the basis of the group-additive transfer model are suggested.

  4. Detection of potential fishing zone for Pacific saury (Cololabis saira) using generalized additive model and remotely sensed data

    NASA Astrophysics Data System (ADS)

    Fachruddin Syah, Achmad; Saitoh, Sei-Ichi; Alabia, Irene D.; Hirawake, Toru

    2017-01-01

    To evaluate the effects of oceanographic conditions on the formation of the potential fishing zones for Pacific saury in western North Pacific, fishing locations of Pacific saury from Defense Meteorological Satellite Program/Operating Linescan System (DMSP/OLS) and satellite-based oceanographic information were used to construct species habitat models. A 2-level slicing method was used to identify the bright regions as actual fishing areas from OLS images, collected during the peak fishing season of Pacific saury in the North Pacific. Statistical metrics, including the significance of model terms, and reduction in the Akaike’s Information Criterion (AIC) were used as the bases for model selection. The selected model was then used to visualize the basin scale distributions of the Pacific saury habitat. The predicted potential fishing zones exhibited spatial correspondence with the fishing locations. The results from generalized additive model revealed that the Pacific saury habitat selection was significantly influenced by the SST ranges from 13-18°C, SSC ranges from 0.5-1.8 mg.m-3, SSHA ranges from 5-17 cm and EKE ranges from 700-1200 cm2s-2. Moreover, among the set of oceanographic factors examined, SST explained the smallest AIC and is thus, considered to be the most significant variable in the geographic distribution of Pacific saury.

  5. Quantitative results for square gradient models of fluids

    NASA Astrophysics Data System (ADS)

    Kong, Ling-Ti; Vriesinga, Dan; Denniston, Colin

    2011-03-01

    Square gradient models for fluids are extensively used because they are believed to provide a good qualitative understanding of the essential physics. However, unlike elasticity theory for solids, there are few quantitative results for specific (as opposed to generic) fluids. Indeed the only numerical value of the square gradient coefficients for specific fluids have been inferred from attempts to match macroscopic properties such as surface tensions rather than from direct measurement. We employ all-atom molecular dynamics, using the TIP3P and OPLS force fields, to directly measure the coefficients of the density gradient expansion for several real fluids. For all liquids measured, including water, we find that the square gradient coefficient is negative, suggesting the need for some regularization of a model including only the square gradient, but only at wavelengths comparable to the molecular separation of molecules. The implications for liquid-gas interfaces are also examined. Remarkably, the square gradient model is found to give a reasonably accurate description of density fluctuations in the liquid state down to wavelengths close to atomic size.

  6. Recent results and persisting problems in modeling flow induced coalescence

    SciTech Connect

    Fortelný, I. E-mail: juza@imc.cas.cz; Jza, J. E-mail: juza@imc.cas.cz

    2014-05-15

    The contribution summarizes recent results of description of the flow induced coalescence in immiscible polymer blends and addresses problems that call for which solving. The theory of coalescence based on the switch between equations for matrix drainage between spherical or deformed droplets provides a good agreement with more complicated modeling and available experimental data for probability, P{sub c}, that the collision of droplets will be followed by their fusion. A new equation for description of the matrix drainage between deformed droplets, applicable to the whole range of viscosity ratios, p, of the droplets and matrixes, is proposed. The theory facilitates to consider the effect of the matrix elasticity on coalescence. P{sub c} decreases with the matrix relaxation time but this decrease is not pronounced for relaxation times typical of most commercial polymers. Modeling of the flow induced coalescence in concentrated systems is needed for prediction of the dependence of coalescence rate on volume fraction of droplets. The effect of the droplet anisometry on P{sub c} should be studied for better understanding the coalescence in flow field with high and moderate deformation rates. A reliable description of coalescence in mixing and processing devices requires proper modeling of complex flow fields.

  7. Multi-Model Combination techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results

    SciTech Connect

    Ajami, N K; Duan, Q; Gao, X; Sorooshian, S

    2005-04-11

    This paper examines several multi-model combination techniques: the Simple Multi-model Average (SMA), the Multi-Model Super Ensemble (MMSE), Modified Multi-Model Super Ensemble (M3SE) and the Weighted Average Method (WAM). These model combination techniques were evaluated using the results from the Distributed Model Intercomparison Project (DMIP), an international project sponsored by the National Weather Service (NWS) Office of Hydrologic Development (OHD). All of the multi-model combination results were obtained using uncalibrated DMIP model outputs and were compared against the best uncalibrated as well as the best calibrated individual model results. The purpose of this study is to understand how different combination techniques affect the skill levels of the multi-model predictions. This study revealed that the multi-model predictions obtained from uncalibrated single model predictions are generally better than any single member model predictions, even the best calibrated single model predictions. Furthermore, more sophisticated multi-model combination techniques that incorporated bias correction steps work better than simple multi-model average predictions or multi-model predictions without bias correction.

  8. Solar wind forcing at Mercury: WSA-ENLIL model results

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Poh, Gangkai; Odstrcil, Dusan; Arge, C. Nick; Benna, Mehdi; Johnson, Catherine L.; Korth, Haje; Gershman, Daniel J.; Ho, George C.; McClintock, William E.; Cassidy, Timothy A.; Merkel, Aimee; Raines, Jim M.; Schriver, David; Slavin, James A.; Solomon, Sean C.; TráVníčEk, Pavel M.; Winslow, Reka M.; Zurbuchen, Thomas H.

    2013-01-01

    Analysis and interpretation of observations from the MESSENGER spacecraft in orbit about Mercury require knowledge of solar wind "forcing" parameters. We have utilized the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool in order to calculate the values of interplanetary magnetic field (IMF) strength (B), solar wind velocity (V) and density (n), ram pressure (~nV2), cross-magnetosphere electric field (V × B), Alfvén Mach number (MA), and other derived quantities of relevance for solar wind-magnetosphere interactions. We have compared upstream MESSENGER IMF and solar wind measurements to see how well the ENLIL model results compare. Such parameters as solar wind dynamic pressure are key for determining the Mercury magnetopause standoff distance, for example. We also use the relatively high-time-resolution B-field data from MESSENGER to estimate the strength of the product of the solar wind speed and southward IMF strength (Bs) at Mercury. This product VBs is the electric field that drives many magnetospheric dynamical processes and can be compared with the occurrence of energetic particle bursts within the Mercury magnetosphere. This quantity also serves as input to the global magnetohydrodynamic and kinetic magnetosphere models that are being used to explore magnetospheric and exospheric processes at Mercury. Moreover, this modeling can help assess near-real-time magnetospheric behavior for MESSENGER or other mission analysis and/or ground-based observational campaigns. We demonstrate that this solar wind forcing tool is a crucial step toward bringing heliospheric science expertise to bear on planetary exploration programs.

  9. Compressible Turbulent Channel Flows: DNS Results and Modeling

    NASA Technical Reports Server (NTRS)

    Huang, P. G.; Coleman, G. N.; Bradshaw, P.; Rai, Man Mohan (Technical Monitor)

    1994-01-01

    The present paper addresses some topical issues in modeling compressible turbulent shear flows. The work is based on direct numerical simulation of two supersonic fully developed channel flows between very cold isothermal walls. Detailed decomposition and analysis of terms appearing in the momentum and energy equations are presented. The simulation results are used to provide insights into differences between conventional time-and Favre-averaging of the mean-flow and turbulent quantities. Study of the turbulence energy budget for the two cases shows that the compressibility effects due to turbulent density and pressure fluctuations are insignificant. In particular, the dilatational dissipation and the mean product of the pressure and dilatation fluctuations are very small, contrary to the results of simulations for sheared homogeneous compressible turbulence and to recent proposals for models for general compressible turbulent flows. This provides a possible explanation of why the Van Driest density-weighted transformation is so successful in correlating compressible boundary layer data. Finally, it is found that the DNS data do not support the strong Reynolds analogy. A more general representation of the analogy is analysed and shown to match the DNS data very well.

  10. Sand transport on Mars: Preliminary results from models

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Anderson, F. S.; Blumberg, D.; Lo, E.; Xu, P.; Pollack, J.

    1993-01-01

    Most studies of active aeolian processes on Mars have focused on dust, i.e., particles approximately 1 micron in diameter that are transported in suspension by wind. The presence of sand dunes on Mars indicates that larger grains (approximately greater than 60 microns, transported primarily in saltation) are also present. Although indirect evidence suggests that some dunes may be active, definitive evidence is lacking. Nonetheless, numerous studies demonstrate that sand is substantially easier to transport by wind than dust, and it is reasonable to infer that sand transportation in saltation occurs under present Martian conditions. In order to assess potential source regions, transportation pathways, and sites of deposition for sand on Mars, an iterative sand transport algorithm was developed that is based on the Mars General Circulation Model of Pollack et al. The results of the dust transport model are then compared with observed surface features, such as dune field locations observed on images, and surficial deposits as inferred from Viking IRTM observations. Preliminary results suggest that the north polar dune fields in the vicinity of 270 degrees W, 70 degrees N originated from weathered polar layered plains centered at 280 degrees W, 85 degrees N, and that Thaumasia Fossae, southern Hellas Planitia, and the area west of Hellespontus Montes are sand depositional sites. Examples of transportation 'corridors' include a westward pathway in the latitudinal band 35 degrees N to 45 degrees N, and a pathway southward from Solis Planum to Thaumasia Fossae, among others.

  11. Longitudinal variation of the equatorial ionosphere: Modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Souza, J. R.; Asevedo, W. D.; dos Santos, P. C. P.; Petry, A.; Bailey, G. J.; Batista, I. S.; Abdu, M. A.

    2013-02-01

    We describe a new version of the Parameterized Regional Ionospheric Model (PARIM) which has been modified to include the longitudinal dependences. This model has been reconstructed using multidimensional Fourier series. To validate PARIM results, the South America maps of critical frequencies for the E (foE) and F (foF2) regions were compared with the values calculated by Sheffield Plasmasphere-Ionosphere Model (SUPIM) and IRI representations. PARIM presents very good results, the general characteristics of both regions, mainly the presence of the equatorial ionization anomaly, were well reproduced for equinoctial conditions of solar minimum and maximum. The values of foF2 and hmF2 recorded over Jicamarca (12°S; 77°W; dip lat. 1°N; mag. declination 0.3°) and sites of the conjugate point equatorial experiment (COPEX) campaign Boa Vista (2.8°N; 60.7°W; dip lat. 11.4°; mag. declination -13.1°), Cachimbo (9.5°S; 54.8°W; dip lat. -1.8°; mag. declination -15.5°), and Campo Grande (20.4°S; 54.6°W; dip lat. -11.1°; mag. declination -14.0°) have been used in this work. foF2 calculated by PARIM show good agreement with the observations, except during morning over Boa Vista and midnight-morning over Campo Grande. Some discrepancies were also found for the F-region peak height (hmF2) near the geomagnetic equator during times of F3 layer occurrences. IRI has underestimated both foF2 and hmF2 over equatorial and low latitude sectors during evening-nighttimes, except for Jicamarca where foF2 values were overestimated.

  12. Influence of binder properties, method of addition, powder type and operating conditions on fluid-bed melt granulation and resulting tablet properties.

    PubMed

    Abberger, T

    2001-12-01

    The aim of the study was to investigate melt granulation in a laboratory scale fluid-bed granulator with respect to granule growth, granule properties and resulting tablet properties. The parameters investigated were method of addition of PEG (spray-on or addition as flakes), binder concentration, PEG type (3000, 4000 and 6000, sprayed-on), size (PEG 4000, added as three different sized flakes), powder type (two different sized lactose types and corn starch) and operating conditions (volume air flow and heating temperature). Addition of binder as flakes led to layering as a growth mechanism when the size of the flakes was high. Coalescence occurred when the size was low. Coalescence also occurred when spraying was the method of addition. Due to the greater viscosity of the PEG 6000 melt it produced bigger granules than 3000 or 4000. The influence of volume air flow was moderate and the influence of heating temperature in the range of 70-90 degrees C was very low with both methods of addition. The disintegration time of tablets from granules where PEG was added as flakes was shorter than from granules where PEG was sprayed-on. The latter method of binder addition led to tablets which did not disintegrate but eroded. This was apparently caused by formation of a binder matrix, which could not be destroyed by the disintegrant.

  13. Multi-Model Combination Techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results

    SciTech Connect

    Ajami, N; Duan, Q; Gao, X; Sorooshian, S

    2006-05-08

    This paper examines several multi-model combination techniques: the Simple Multimodel Average (SMA), the Multi-Model Super Ensemble (MMSE), Modified Multi-Model Super Ensemble (M3SE) and the Weighted Average Method (WAM). These model combination techniques were evaluated using the results from the Distributed Model Intercomparison Project (DMIP), an international project sponsored by the National Weather Service (NWS) Office of Hydrologic Development (OHD). All of the multi-model combination results were obtained using uncalibrated DMIP model outputs and were compared against the best uncalibrated as well as the best calibrated individual model results. The purpose of this study is to understand how different combination techniques affect the skill levels of the multi-model predictions. This study revealed that the multi-model predictions obtained from uncalibrated single model predictions are generally better than any single member model predictions, even the best calibrated single model predictions. Furthermore, more sophisticated multi-model combination techniques that incorporated bias correction steps work better than simple multi-model average predictions or multi-model predictions without bias correction.

  14. UAS Modeling of the Communication Links Study Results

    NASA Technical Reports Server (NTRS)

    Birr, Richard B.; Girgis, Nancy; Murray, Jennifer

    2011-01-01

    The Federal Aviation Administration (FAA) is the authority that grants access into, and operations within, the National Airspace System (NAS) for all aircraft, including Unmanned Aircraft Systems (UAS). The safe operation of UAS in the NAS must be assured if the full potential of UAS is to be realized and supported by the public and Congress. This report analyzed the communication systems that are needed for the safe operations of UAS in the NAS. Safe operations can be defined as the availability of the required links to carry the information to control the UAS and the return links to allow controllers to know where the UAS is at any given moment as well as how it is performing. This report is the end result of work performed jointly between the FAA and National Aeronautics and Space Administration (NASA)/Kennedy Space Center (NASA KSC). The work was done in support of the Radio Technical Commission for Aeronautics (RTCA) Special Committee 203 (SC-203) Control and Communications Working Group. The RTCA is a federal advisory committee to the FAA. Though the work was not under the direction of the working group, a large part of the specific values used in the simulations came from the working group. Specifically, all of the radio links were modeled based on the formulation completed by the working group. This report analyzed three scenarios from RTCA SC-203 that represent how a UAS would operate in the NAS. Each scenario was created using the Satellite Tool Kit (STK) modeling and simulation tool. The flight paths of the UAS were generated and the UAS dynamics were likewise modeled. Then each communication asset such as transmitters, receivers, and antennas were modeled and placed on the appropriate UAS, satellite, or Control Station (CS). After that, the radio links were analyzed for signal strength and antenna blockage, and the overall link performance was analyzed in detail. The goal was to obtain 99.9% availability on all of the radio communication links. In order

  15. Kinetic modeling of the oxidative degradation of additive free PE in bleach disinfected water

    NASA Astrophysics Data System (ADS)

    Mikdam, Aïcha; Colin, Xavier; Billon, Noëlle; Minard, Gaëlle

    2016-05-01

    The chemical interactions between PE and bleach were studied at 60°C in immersion in bleach solutions kept at a free chlorine concentration of 100 ppm and a pH of 5 or 7.2. It was found that the polymer undergoes a severe oxidation from the earliest weeks of exposure, in a superficial layer whose thickness (of about 50-70 µm) is almost independent of the pH value, although the superficial oxidation rate is faster in acidic than in neutral medium. Oxidation leads to the formation and accumulation of a large variety of carbonyl products (mostly ketones and carboxylic acids) and, after a few weeks, to a decrease in the average molar mass due to the large predominance of chain scissions over crosslinking. A scenario was elaborated for explaining such unexpected results. According to this scenario, the non-ionic molecules (Cl2 and ClOH) formed from the disinfectant in the water phase, would migrate deeply into PE and dissociate into highly reactive radicals (Cl• and HO•) in order to initiate a radical chain oxidation. A kinetic model was derived from this scenario for predicting the general trends of the oxidation kinetics and its dependence on environmental factors such as temperature, free chlorine concentration and pH. The validity of this model was successfully checked by comparing the numerical simulations with experimental data.

  16. Modeling, Simulation, Additive Manufacturing, and Experimental Evaluation of Solid and Porous NiTi

    NASA Astrophysics Data System (ADS)

    Taheri Andani, Mohsen

    In recent years, shape memory alloys (SMAs) have entered a wide range of engineering applications in fields such as aerospace and medical applications. Nickel-titanium (NiTi) is the most commonly used SMAs due to its excellent functional characteristics (shape memory effect and superelasticity behavior). These properties are based on a solid-solid phase transformation between martensite and austenite. Beside these two characteristics, low stiffness, biocompatibility and corrosion properties of NiTi make it an attractive candidate for biomedical applications (e.g., bone plates, bone screws, and vascular stents). It is well know that manufacturing and processing of NiTi is very challenging. The functional properties of NiTi are significantly affected by the impurity level and due to the high titanium content, NiTi are highly reactive. Therefore, high temperature processed parts through methods such as melting and casting which result in increased impurity levels have inadequate structural and functional properties. Furthermore, high ductility and elasticity of NiTi, adhesion, work hardening and spring back effects make machining quite challenging. These unfavorable effects for machining cause significant tool wear along with decreasing the quality of work piece. Recently, additive manufacturing (AM) has gained significant attention for manufacturing NiTi. Since AM can create a part directly from CAD data, it is predicted that AM can overcome most of the manufacturing difficulties. This technique provides the possibility of fabricating highly complex parts, which cannot be processed by any other methods. Curved holes, designed porosity, and lattice like structures are some examples of mentioned complex parts. This work investigates manufacturing superelastic NiTi by selective laser melting (SLM) technique (using PXM by Phenix/3D Systems). An extended experimental study is conducted on the effect of subsequent heat treatments with different aging conditions on phase

  17. Comparison of blade-strike modeling results with empirical data

    SciTech Connect

    Ploskey, Gene R.; Carlson, Thomas J.

    2004-03-01

    This study is the initial stage of further investigation into the dynamics of injury to fish during passage through a turbine runner. As part of the study, Pacific Northwest National Laboratory (PNNL) estimated the probability of blade strike, and associated injury, as a function of fish length and turbine operating geometry at two adjacent turbines in Powerhouse 1 of Bonneville Dam. Units 5 and 6 had identical intakes, stay vanes, wicket gates, and draft tubes, but Unit 6 had a new runner and curved discharge ring to minimize gaps between the runner hub and blades and between the blade tips and discharge ring. We used a mathematical model to predict blade strike associated with two Kaplan turbines and compared results with empirical data from biological tests conducted in 1999 and 2000. Blade-strike models take into consideration the geometry of the turbine blades and discharges as well as fish length, orientation, and distribution along the runner. The first phase of this study included a sensitivity analysis to consider the effects of difference in geometry and operations between families of turbines on the strike probability response surface. The analysis revealed that the orientation of fish relative to the leading edge of a runner blade and the location that fish pass along the blade between the hub and blade tip are critical uncertainties in blade-strike models. Over a range of discharges, the average prediction of injury from blade strike was two to five times higher than average empirical estimates of visible injury from shear and mechanical devices. Empirical estimates of mortality may be better metrics for comparison to predicted injury rates than other injury measures for fish passing at mid-blade and blade-tip locations.

  18. Addition of Sodium Pyruvate to Stored Red Blood Cells Attenuates Liver Injury in a Murine Transfusion Model

    PubMed Central

    2016-01-01

    RBCs undergo numerous changes during storage and stored RBCs may induce adverse effects, ultimately resulting in organ injury in transfusion recipients. We tested the hypothesis that the addition of SP to stored RBCs would improve the quality of the stored RBCs and mitigate liver injury after transfusion in a murine model. RBCs were harvested from C57BL/6J mice and stored for 14 days in CPDA-1 containing either a solution of SP in saline or saline alone. Haemolysis, the 24-hour posttransfusion recovery, the oxygen-carrying capacity, and the SOD activity of stored RBCs were evaluated. The plasma biochemistry, hepatic MDA level, MPO activity, IL-6, TNF-α concentrations, and histopathology were measured two hours after the transfusion of stored RBCs. Compared with RBCs stored in CPDA-1 and saline, the addition of SP to stored RBCs restored their oxygen-carrying capacity and SOD activity, reduced the AST activity, BUN concentrations, and LDH activity in the plasma, and decreased the MDA level, MPO activity, and concentrations of IL-6 and TNF-α in the liver. These data indicate that the addition of SP to RBCs during storage has a beneficial effect on storage lesions in vitro and subsequently alleviates liver injury after the transfusion of stored RBCs in vivo. PMID:27746589

  19. Scale model test results of several STOVL ventral nozzle concepts

    NASA Technical Reports Server (NTRS)

    Meyer, B. E.; Re, R. J.; Yetter, J. A.

    1991-01-01

    Short take-off and vertical landing (STOVL) ventral nozzle concepts are investigated by means of a static cold flow scale model at a NASA facility. The internal aerodynamic performance characteristics of the cruise, transition, and vertical lift modes are considered for four ventral nozzle types. The nozzle configurations examined include those with: butterfly-type inner doors and vectoring exit vanes; circumferential inner doors and thrust vectoring vanes; a three-port segmented version with circumferential inner doors; and a two-port segmented version with cylindrical nozzle exit shells. During the testing, internal and external pressure is measured, and the thrust and flow coefficients and resultant vector angles are obtained. The inner door used for ventral nozzle flow control is found to affect performance negatively during the initial phase of transition. The best thrust performance is demonstrated by the two-port segmented ventral nozzle due to the elimination of the inner door.

  20. Sediment Pathways Across Trench Slopes: Results From Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Cormier, M. H.; Seeber, L.; McHugh, C. M.; Fujiwara, T.; Kanamatsu, T.; King, J. W.

    2015-12-01

    Until the 2011 Mw9.0 Tohoku earthquake, the role of earthquakes as agents of sediment dispersal and deposition at erosional trenches was largely under-appreciated. A series of cruises carried out after the 2011 event has revealed a variety of unsuspected sediment transport mechanisms, such as tsunami-triggered sheet turbidites, suggesting that great earthquakes may in fact be important agents for dispersing sediments across trench slopes. To complement these observational data, we have modeled the pathways of sediments across the trench slope based on bathymetric grids. Our approach assumes that transport direction is controlled by slope azimuth only, and ignores obstacles smaller than 0.6-1 km; these constraints are meant to approximate the behavior of turbidites. Results indicate that (1) most pathways issued from the upper slope terminate near the top of the small frontal wedge, and thus do not reach the trench axis; (2) in turn, sediments transported to the trench axis are likely derived from the small frontal wedge or from the subducting Pacific plate. These results are consistent with the stratigraphy imaged in seismic profiles, which reveals that the slope apron does not extend as far as the frontal wedge, and that the thickness of sediments at the trench axis is similar to that of the incoming Pacific plate. We further applied this modeling technique to the Cascadia, Nankai, Middle-America, and Sumatra trenches. Where well-defined canyons carve the trench slopes, sediments from the upper slope may routinely reach the trench axis (e.g., off Costa Rica and Cascadia). In turn, slope basins that are isolated from the canyons drainage systems must mainly accumulate locally-derived sediments. Therefore, their turbiditic infill may be diagnostic of seismic activity only - and not from storm or flood activity. If correct, this would make isolated slope basins ideal targets for paleoseismological investigation.

  1. 78 FR 32224 - Availability of Version 3.1.2 of the Connect America Fund Phase II Cost Model; Additional...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ...; Additional Discussion Topics in Connect America Cost Model Virtual Workshop AGENCY: Federal Communications... issues in the ongoing virtual workshop. DATES: Comments are due on or before June 18, 2013. If you... comments. Virtual Workshop: In addition to the usual methods for filing electronic comments, the...

  2. The design, results and future development of the National Energy Strategy Environmental Analysis Model (NESEAM)

    SciTech Connect

    Fisher, R.E.; Boyd, G.A. ); Breed, W.S. . Office of Environmental Analysis)

    1991-01-01

    The National Energy Strategy Environmental Model (NESEAM) has been developed to project emissions for the National Energy Strategy (NES). Two scenarios were evaluated for the NES, a Current Policy Base Case and a NES Action Case. The results from the NES Actions Case project much lower emissions than the Current Policy Base Case. Future enhancements to NESEAM will focus on fuel cycle analysis, including future technologies and additional pollutants to model. NESEAM's flexibility will allow it to model other future legislative issues. 7 refs., 4 figs., 2 tabs.

  3. Precise control of polymer coated nanopores by nanoparticle additives: Insights from computational modeling

    NASA Astrophysics Data System (ADS)

    Eskandari Nasrabad, Afshin; Jasnow, David; Zilman, Anton; Coalson, Rob D.

    2016-08-01

    Polymer-nanoparticle composites are a promising new class of materials for creation of controllable nano-patterned surfaces and nanopores. We use coarse-grained molecular dynamics simulations augmented with analytical theory to study the structural transitions of surface grafted polymer layers (brushes) induced by infiltration of nanoparticles that are attracted to the polymers in the layer. We systematically compare two different polymer brush geometries: one where the polymer chains are grafted to a planar surface and the other where the chains are grafted to the inside of a cylindrical nanochannel. We perform a comprehensive study of the effects of the material parameters such as the polymer chain length, chain grafting density, nanoparticle size, strength of attraction between nanoparticles and polymer monomers, and, in the case of the cylindrically grafted brush, the radius of the cylinder. We find a very general behavioral motif for all geometries and parameter values: the height of the polymer brush is non-monotonic in the nanoparticle concentration in solution. As the nanoparticle concentration increases, the brush height first decreases and after passing through a minimum value begins to increase, resulting in the swelling of the nanoparticle infused brush. These morphological features may be useful for devising tunable "smart" nano-devices whose effective dimensions can be reversibly and precisely adjusted by changing the nanoparticle concentration in solution. The results of approximate Self-Consistent Field Theory (SCFT) calculations, applicable in the regime of strong brush stretching, are compared to the simulation results. The SCFT calculations are found to be qualitatively, even semi-quantitatively, accurate when applied within their intended regime of validity, and provide a useful and efficient tool for modeling such materials.

  4. EFFECTS OF CORRELATED PROBABILISTIC EXPOSURE MODEL INPUTS ON SIMULATED RESULTS

    EPA Science Inventory

    In recent years, more probabilistic models have been developed to quantify aggregate human exposures to environmental pollutants. The impact of correlation among inputs in these models is an important issue, which has not been resolved. Obtaining correlated data and implementi...

  5. Comprehensive Electricity Competition Act: A Comparison of Model Results, The

    EIA Publications

    1999-01-01

    This report describes the Energy Information Administration's use of the National Energy Modeling System (NEMS) to evaluate the effects of the Administration's restructuring proposal using the parameter settings and assumptions from the Policy Office Electricity Modeling System (POEMS) analysis.

  6. Numerical Results of Earth's Core Accumulation 3-D Modelling

    NASA Astrophysics Data System (ADS)

    Khachay, Yurie; Anfilogov, Vsevolod

    2013-04-01

    For a long time as a most convenient had been the model of mega impact in which the early forming of the Earth's core and mantle had been the consequence of formed protoplanet collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,3] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone. Only after the increasing of the gravitational radius, the growing area of the future core can save also the silicate envelope fragments. All existing dynamical accumulation models are constructed by using a spherical-symmetrical model. Hence for understanding the further planet evolution it is significant to trace the origin and evolution of heterogeneities, which occur on the planet accumulation stage. In that paper we are modeling distributions of temperature, pressure, velocity of matter flowing in a block of 3D- spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach. The numerical algorithm of the problem solution in

  7. DAMA/LIBRA-phase1 model independent results

    NASA Astrophysics Data System (ADS)

    Bernabei, R.; Belli, P.; D'Angelo, S.; di Marco, A.; Montecchia, F.; D'Angelo, A.; Incicchitti, A.; Prosperi, D.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Dai, C. J.; He, H. L.; Kuang, H. H.; Ma, X. H.; Sheng, X. D.; Wang, R. G.; Ye, Z. P.

    2016-10-01

    Experimental observations and theoretical arguments at Galaxy and larger scales have suggested that a large fraction of the Universe is composed by Dark Matter (DM) particles. This has motivated the DAMA experimental efforts to investigate the presence of such particles in the galactic halo by exploiting a model independent signature with highly radiopure setups deep underground. In this paper, a review of the results obtained with the total exposure of 1.04 ton × yr collected by DAMA/LIBRA-phase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN during seven annual cycles is given. The DAMA/LIBRA-phase1 data give evidence for the presence of DM particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radiopure NaI(Tl) target, at 7.5σ C.L. Including also the data of the first generation DAMA/NaI experiment (cumulative exposure 1.33 ton × yr, corresponding to 14 annual cycles), the C.L. is 9.3σ and the modulation amplitude of the single-hit scintillation events in the (2-6) keV energy interval is: (0.0112 ± 0.0012) cpd/kg/keV; the measured phase is (144 ± 7) days and the measured period is (0.998 ± 0.002) yr, values well in agreement with those expected for DM particles. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade.

  8. Mouse Model of Neurological Complications Resulting from Encephalitic Alphavirus Infection

    PubMed Central

    Ronca, Shannon E.; Smith, Jeanon; Koma, Takaaki; Miller, Magda M.; Yun, Nadezhda; Dineley, Kelly T.; Paessler, Slobodan

    2017-01-01

    Long-term neurological complications, termed sequelae, can result from viral encephalitis, which are not well understood. In human survivors, alphavirus encephalitis can cause severe neurobehavioral changes, in the most extreme cases, a schizophrenic-like syndrome. In the present study, we aimed to adapt an animal model of alphavirus infection survival to study the development of these long-term neurological complications. Upon low-dose infection of wild-type C57B/6 mice, asymptomatic and symptomatic groups were established and compared to mock-infected mice to measure general health and baseline neurological function, including the acoustic startle response and prepulse inhibition paradigm. Prepulse inhibition is a robust operational measure of sensorimotor gating, a fundamental form of information processing. Deficits in prepulse inhibition manifest as the inability to filter out extraneous sensory stimuli. Sensory gating is disrupted in schizophrenia and other mental disorders, as well as neurodegenerative diseases. Symptomatic mice developed deficits in prepulse inhibition that lasted through 6 months post infection; these deficits were absent in asymptomatic or mock-infected groups. Accompanying prepulse inhibition deficits, symptomatic animals exhibited thalamus damage as visualized with H&E staining, as well as increased GFAP expression in the posterior complex of the thalamus and dentate gyrus of the hippocampus. These histological changes and increased GFAP expression were absent in the asymptomatic and mock-infected animals, indicating that glial scarring could have contributed to the prepulse inhibition phenotype observed in the symptomatic animals. This model provides a tool to test mechanisms of and treatments for the neurological sequelae of viral encephalitis and begins to delineate potential explanations for the development of such sequelae post infection. PMID:28223982

  9. Mouse Model of Neurological Complications Resulting from Encephalitic Alphavirus Infection.

    PubMed

    Ronca, Shannon E; Smith, Jeanon; Koma, Takaaki; Miller, Magda M; Yun, Nadezhda; Dineley, Kelly T; Paessler, Slobodan

    2017-01-01

    Long-term neurological complications, termed sequelae, can result from viral encephalitis, which are not well understood. In human survivors, alphavirus encephalitis can cause severe neurobehavioral changes, in the most extreme cases, a schizophrenic-like syndrome. In the present study, we aimed to adapt an animal model of alphavirus infection survival to study the development of these long-term neurological complications. Upon low-dose infection of wild-type C57B/6 mice, asymptomatic and symptomatic groups were established and compared to mock-infected mice to measure general health and baseline neurological function, including the acoustic startle response and prepulse inhibition paradigm. Prepulse inhibition is a robust operational measure of sensorimotor gating, a fundamental form of information processing. Deficits in prepulse inhibition manifest as the inability to filter out extraneous sensory stimuli. Sensory gating is disrupted in schizophrenia and other mental disorders, as well as neurodegenerative diseases. Symptomatic mice developed deficits in prepulse inhibition that lasted through 6 months post infection; these deficits were absent in asymptomatic or mock-infected groups. Accompanying prepulse inhibition deficits, symptomatic animals exhibited thalamus damage as visualized with H&E staining, as well as increased GFAP expression in the posterior complex of the thalamus and dentate gyrus of the hippocampus. These histological changes and increased GFAP expression were absent in the asymptomatic and mock-infected animals, indicating that glial scarring could have contributed to the prepulse inhibition phenotype observed in the symptomatic animals. This model provides a tool to test mechanisms of and treatments for the neurological sequelae of viral encephalitis and begins to delineate potential explanations for the development of such sequelae post infection.

  10. Modeling acute respiratory illness during the 2007 San Diego wildland fires using a coupled emissions-transport system and generalized additive modeling

    PubMed Central

    2013-01-01

    Background A study of the impacts on respiratory health of the 2007 wildland fires in and around San Diego County, California is presented. This study helps to address the impact of fire emissions on human health by modeling the exposure potential of proximate populations to atmospheric particulate matter (PM) from vegetation fires. Currently, there is no standard methodology to model and forecast the potential respiratory health effects of PM plumes from wildland fires, and in part this is due to a lack of methodology for rigorously relating the two. The contribution in this research specifically targets that absence by modeling explicitly the emission, transmission, and distribution of PM following a wildland fire in both space and time. Methods Coupled empirical and deterministic models describing particulate matter (PM) emissions and atmospheric dispersion were linked to spatially explicit syndromic surveillance health data records collected through the San Diego Aberration Detection and Incident Characterization (SDADIC) system using a Generalized Additive Modeling (GAM) statistical approach. Two levels of geographic aggregation were modeled, a county-wide regional level and division of the county into six sub regions. Selected health syndromes within SDADIC from 16 emergency departments within San Diego County relevant for respiratory health were identified for inclusion in the model. Results The model captured the variability in emergency department visits due to several factors by including nine ancillary variables in addition to wildfire PM concentration. The model coefficients and nonlinear function plots indicate that at peak fire PM concentrations the odds of a person seeking emergency care is increased by approximately 50% compared to non-fire conditions (40% for the regional case, 70% for a geographically specific case). The sub-regional analyses show that demographic variables also influence respiratory health outcomes from smoke. Conclusions The

  11. Analysis of the laser powder bed fusion additive manufacturing process through experimental measurement and finite element modeling

    NASA Astrophysics Data System (ADS)

    Dunbar, Alexander Jay

    The objective in this work is to provide rigourous experimental measurements to aid in the development of laser powder bed fusion (LPBF) additive manufacturing (AM). A specialized enclosed instrumented measurement system is designed to provide in situ experimental measurements of temperature and distortion. Experiments include comparisons of process parameters, materials and LPBF machines. In situ measurements of distortion and temperature made throughout the build process highlight inter-layer distortion effects previously undocumented for laser powder bed fusion. Results from these experiments are also be implemented in the development and validation of finite element models of the powder bed build process. Experimental analysis is extended from small-scale to larger part-scale builds where experimental post-build measurements are used in analysis of distortion profiles. Experimental results provided from this study are utilized in the validation of a finite element model capable of simulating production scale parts. The validated finite element model is then implemented in the analysis of the part to provide information regarding the distortion evolution process. A combination of experimental measurements and simulation results are used to identify the mechanism that results in the measured distortion profile for this geometry. Optimization of support structure primarily focuses on the minimization of material use and scan time, but no information regarding failure criteria for support structure is available. Tensile test samples of LPBF built support structure are designed, built, and tested to provide measurements of mechanical properties of the support structure. Experimental tests show that LPBF built support structure has only 30-40% of the ultimate tensile strength of solid material built in the same machine. Experimental measurement of LPBF built support structure provides clear failure criteria to be utilized in the future design and implementation of

  12. Infrared thermography for CFRP inspection: computational model and experimental results

    NASA Astrophysics Data System (ADS)

    Fernandes, Henrique C.; Zhang, Hai; Morioka, Karen; Ibarra-Castanedo, Clemente; López, Fernando; Maldague, Xavier P. V.; Tarpani, José R.

    2016-05-01

    Infrared Thermography (IRT) is a well-known Non-destructive Testing (NDT) technique. In the last decades, it has been widely applied in several fields including inspection of composite materials (CM), specially the fiber-reinforced polymer matrix ones. Consequently, it is important to develop and improve efficient NDT techniques to inspect and assess the quality of CM parts in order to warranty airworthiness and, at the same time, reduce costs of airline companies. In this paper, active IRT is used to inspect carbon fiber-reinforced polymer (CFRP) at laminate with artificial inserts (built-in sample) placed on different layers prior to the manufacture. Two optical active IRT are used. The first is pulsed thermography (PT) which is the most widely utilized IRT technique. The second is a line-scan thermography (LST) technique: a dynamic technique, which can be employed for the inspection of materials by heating a component, line-by-line, while acquiring a series of thermograms with an infrared camera. It is especially suitable for inspection of large parts as well as complex shaped parts. A computational model developed using COMSOL Multiphysics® was used in order to simulate the inspections. Sequences obtained from PT and LST were processed using principal component thermography (PCT) for comparison. Results showed that it is possible to detect insertions of different sizes at different depths using both PT and LST IRT techniques.

  13. Metal-ceramic composite development based on its modelling results

    NASA Astrophysics Data System (ADS)

    Dvilis, E. S.; Khasanov, O. L.; Khasanov, A. O.; Petyukevich, M. S.

    2016-02-01

    The modeling (and its experimental verification) of packing and deformation of the composites consisted of aluminum-magnesium alloy AMg6, B4C powder and W nano-powder has been performed. The powder compositions were determined using discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders. The models of maximum mixture packing densities have been rendered.

  14. The generic modeling fallacy: Average biomechanical models often produce non-average results!

    PubMed

    Cook, Douglas D; Robertson, Daniel J

    2016-11-07

    Computational biomechanics models constructed using nominal or average input parameters are often assumed to produce average results that are representative of a target population of interest. To investigate this assumption a stochastic Monte Carlo analysis of two common biomechanical models was conducted. Consistent discrepancies were found between the behavior of average models and the average behavior of the population from which the average models׳ input parameters were derived. More interestingly, broadly distributed sets of non-average input parameters were found to produce average or near average model behaviors. In other words, average models did not produce average results, and models that did produce average results possessed non-average input parameters. These findings have implications on the prevalent practice of employing average input parameters in computational models. To facilitate further discussion on the topic, the authors have termed this phenomenon the "Generic Modeling Fallacy". The mathematical explanation of the Generic Modeling Fallacy is presented and suggestions for avoiding it are provided. Analytical and empirical examples of the Generic Modeling Fallacy are also given.

  15. Waste glass corrosion modeling: Comparison with experimental results

    SciTech Connect

    Bourcier, W.L.

    1993-11-01

    A chemical model of glass corrosion will be used to predict the rates of release of radionuclides from borosilicate glass waste forms in high-level waste repositories. The model will be used both to calculate the rate of degradation of the glass, and also to predict the effects of chemical interactions between the glass and repository materials such as spent fuel, canister and container materials, backfill, cements, grouts, and others. Coupling between the degradation processes affecting all these materials is expected. Models for borosilicate glass dissolution must account for the processes of (1) kinetically-controlled network dissolution, (2) precipitation of secondary phases, (3) ion exchange, (4) rate-limiting diffusive transport of silica through a hydrous surface reaction layer, and (5) specific glass surface interactions with dissolved cations and anions. Current long-term corrosion models for borosilicate glass employ a rate equation consistent with transition state theory embodied in a geochemical reaction-path modeling program that calculates aqueous phase speciation and mineral precipitation/dissolution. These models are currently under development. Future experimental and modeling work to better quantify the rate-controlling processes and validate these models are necessary before the models can be used in repository performance assessment calculations.

  16. An Additional Measure of Overall Effect Size for Logistic Regression Models

    ERIC Educational Resources Information Center

    Allen, Jeff; Le, Huy

    2008-01-01

    Users of logistic regression models often need to describe the overall predictive strength, or effect size, of the model's predictors. Analogs of R[superscript 2] have been developed, but none of these measures are interpretable on the same scale as effects of individual predictors. Furthermore, R[superscript 2] analogs are not invariant to the…

  17. Creating a Climate for Linguistically Responsive Instruction: The Case for Additive Models

    ERIC Educational Resources Information Center

    Rao, Arthi B.; Morales, P. Zitlali

    2015-01-01

    As a state with a longstanding tradition of offering bilingual education, Illinois has a legislative requirement for native language instruction in earlier grades through a model called Transitional Bilingual Education (TBE). This model does not truly develop bilingualism, however, but rather offers native language instruction to English learners…

  18. Additive SMILES-based optimal descriptors in QSAR modelling bee toxicity: Using rare SMILES attributes to define the applicability domain.

    PubMed

    Toropov, A A; Benfenati, E

    2008-05-01

    The additive SMILES-based optimal descriptors have been used for modelling the bee toxicity. The influence of relative prevalence of the SMILES attributes in a training and test sets to the models for bee toxicity has been analysed. Avoiding the use of rare attributes improves statistical characteristics of the model on the external test set. The possibility of using the probability of the presence of SMILES attributes in training and test sets for rational definition of the applicability domain is discussed.

  19. Understanding drivers of the export of dissolved organic carbon from headwater catchments in Germany using Generalised Additive Models

    NASA Astrophysics Data System (ADS)

    Selle, Benny; Tittel, Jörg; Musolff, Andreas

    2015-04-01

    In the literature, several causes of recently increasing concentrations of dissolved organic carbon (DOC) in headwaters across eastern North America and northern and central Europe have been debated. One likely driver of the widespread increase of DOC concentrations since the early to mid 1990s are decreasing depositions of acid rain resulting in an increased solubility of organic carbon compounds including humic acids. Here, we tested the hypothesis if the reduced availability of both nitrate and sulfate stimulated the reduction of ferric iron soil minerals and the mobilisation of DOC. Decreasing depositions often resulted in a reduced availability of both nitrate and sulphate, which are preferred electron acceptors in microbial decomposition processes. As iron minerals act as efficient sorbents of organic compounds in soils its reduction may have caused a release of humic substances and hence an increasing export of DOC from headwater catchments. To test this hypothesis, time series of DOC, dissolved iron, sulfate and nitrate from several German headwater catchments were examined using Generalised Additive Models. Using this modelling technique, discharge corrected time series of concentrations were represented as a sum of a seasonal and a non-linear trend component. Both, the computed trends and seasonalities supported the redox hypothesis.

  20. A kernel-oriented model for coalition-formation in general environments: Implementation and results

    SciTech Connect

    Shehory, O.; Kraus, S.

    1996-12-31

    In this paper we present a model for coalition formation and payoff distribution in general environments. We focus on a reduced complexity kernel-oriented coalition formation model, and provide a detailed algorithm for the activity of the single rational agent. The model is partitioned into a social level and a strategic level, to distinguish between regulations that must be agreed upon and are forced by agent-designers, and strategies by which each agent acts at will. In addition, we present an implementation of the model and simulation results. From these we conclude that implementing the model for coalition formation among agents increases the benefits of the agents with reasonable time consumption. It also shows that more coalition formations yield more benefits to the agents.

  1. User's guide to Model Viewer, a program for three-dimensional visualization of ground-water model results

    USGS Publications Warehouse

    Hsieh, Paul A.; Winston, Richard B.

    2002-01-01

    Model Viewer is a computer program that displays the results of three-dimensional groundwater models. Scalar data (such as hydraulic head or solute concentration) may be displayed as a solid or a set of isosurfaces, using a red-to-blue color spectrum to represent a range of scalar values. Vector data (such as velocity or specific discharge) are represented by lines oriented to the vector direction and scaled to the vector magnitude. Model Viewer can also display pathlines, cells or nodes that represent model features such as streams and wells, and auxiliary graphic objects such as grid lines and coordinate axes. Users may crop the model grid in different orientations to examine the interior structure of the data. For transient simulations, Model Viewer can animate the time evolution of the simulated quantities. The current version (1.0) of Model Viewer runs on Microsoft Windows 95, 98, NT and 2000 operating systems, and supports the following models: MODFLOW-2000, MODFLOW-2000 with the Ground-Water Transport Process, MODFLOW-96, MOC3D (Version 3.5), MODPATH, MT3DMS, and SUTRA (Version 2D3D.1). Model Viewer is designed to directly read input and output files from these models, thus minimizing the need for additional postprocessing. This report provides an overview of Model Viewer. Complete instructions on how to use the software are provided in the on-line help pages.

  2. How to: understanding SWAT model uncertainty relative to measured results

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watershed models are being relied upon to contribute to most policy-making decisions of watershed management, and the demand for an accurate accounting of complete model uncertainty is rising. Generalized likelihood uncertainty estimation (GLUE) is a widely used method for quantifying uncertainty i...

  3. Effect of geometry of rice kernels on drying modeling results

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geometry of rice grain is commonly represented by sphere, spheroid or ellipsoid shapes in the drying models. Models using simpler shapes are easy to solve mathematically, however, deviation from the true grain shape might lead to large errors in predictions of drying characteristics such as, moistur...

  4. Non-parametric estimation of the odds ratios for continuous exposures using generalized additive models with an unknown link function.

    PubMed

    Cadarso-Suárez, Carmen; Roca-Pardiñas, Javier; Figueiras, Adolfo; González-Manteiga, Wenceslao

    2005-04-30

    The generalized additive, model (GAM) is a powerful and widely used tool that allows researchers to fit, non-parametrically, the effect of continuous predictors on a transformation of the mean response variable. Such a transformation is given by a so-called link function, and in GAMs this link function is assumed to be known. Nevertheless, if an incorrect choice is made for the link, the resulting GAM is misspecified and the results obtained may be misleading. In this paper, we propose a modified version of the local scoring algorithm that allows for the non-parametric estimation of the link function, by using local linear kernel smoothers. To better understand the effect that each covariate produces on the outcome, results are expressed in terms of the non-parametric odds ratio (OR) curves. Bootstrap techniques were used to correct the bias in the OR estimation and to construct point-wise confidence intervals. A simulation study was carried out to assess the behaviour of the resulting estimates. The proposed methodology was illustrated using data from the AIDS Register of Galicia (NW Spain), with a view to assessing the effect of the CD4 lymphocyte count on the probability of being AIDS-diagnosed via Tuberculosis (TB). This application shows how the link's flexibility makes it possible to obtain OR curve estimates that are less sensitive to the presence of outliers and unusual values that are often present in the extremes of the covariate distributions.

  5. Inter-species Extrapolation of Skin Heating Resulting from Millimeter Wave Irradiation: Modeling and Experimental Results

    DTIC Science & Technology

    2003-05-01

    forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high...temperature increase was approximately 7.0°C for the short-term HPM exposures for all three species/ locations, and 8.5°C (monkey, human) to 10.5°C (rat) for...the longer-duration LPM exposures . The HPM temperature his- tories are in close agreement with a one-dimensional conduc- tion heat transfer model with

  6. Short-term prediction of Betula airborne pollen concentration in Vigo (NW Spain) using logistic additive models and partially linear models

    NASA Astrophysics Data System (ADS)

    Cotos-Yáñez, Tomas R.; Rodríguez-Rajo, F. J.; Jato, M. V.

    Betula pollen is a common cause of pollinosis in localities in NW Spain and between 13% and 60% of individuals who are immunosensitive to pollen grains respond positively to its allergens. It is important in the case of all such people to be able to predict pollen concentrations in advance. We therefore undertook an aerobiological study in the city of Vigo (Pontevedra, Spain) from 1995 to 2001, using a Hirst active-impact pollen trap (VPPS 2000) situated in the city centre. Vigo presents a temperate maritime climate with a mean annual temperature of 14.9 °C and 1,412 mm annual total precipitation. This paper analyses two ways of quantifying the prediction of pollen concentration: first by means of a generalized additive regression model with the object of predicting whether the series of interest exceeds a certain threshold; second using a partially linear model to obtain specific prediction values for pollen grains. Both models use a self-explicative part and another formed by exogenous meteorological factors. The models were tested with data from 2001 (year in which the total precipitation registered was almost twice the climatological average overall during the flowering period), which were not used in formulating the models. A highly satisfactory classification and good forecasting results were achieved with the first and second approaches respectively. The estimated line taking into account temperature and a calm S-SW wind, corresponds to the real line recorded during 2001, which gives us an idea of the proposed model's validity.

  7. Wave-current interactions: model development and preliminary results

    NASA Astrophysics Data System (ADS)

    Mayet, Clement; Lyard, Florent; Ardhuin, Fabrice

    2013-04-01

    The coastal area concentrates many uses that require integrated management based on diagnostic and predictive tools to understand and anticipate the future of pollution from land or sea, and learn more about natural hazards at sea or activity on the coast. The realistic modelling of coastal hydrodynamics needs to take into account various processes which interact, including tides, surges, and sea state (Wolf [2008]). These processes act at different spatial scales. Unstructured-grid models have shown the ability to satisfy these needs, given that a good mesh resolution criterion is used. We worked on adding a sea state forcing in a hydrodynamic circulation model. The sea state model is the unstructured version of WAVEWATCH III c (Tolman [2008]) (which version is developed at IFREMER, Brest (Ardhuin et al. [2010]) ), and the hydrodynamic model is the 2D barotropic module of the unstructured-grid finite element model T-UGOm (Le Bars et al. [2010]). We chose to use the radiation stress approach (Longuet-Higgins and Stewart [1964]) to represent the effect of surface waves (wind waves and swell) in the barotropic model, as previously done by Mastenbroek et al. [1993]and others. We present here some validation of the model against academic cases : a 2D plane beach (Haas and Warner [2009]) and a simple bathymetric step with analytic solution for waves (Ardhuin et al. [2008]). In a second part we present realistic application in the Ushant Sea during extreme event. References Ardhuin, F., N. Rascle, and K. Belibassakis, Explicit wave-averaged primitive equations using a generalized Lagrangian mean, Ocean Modelling, 20 (1), 35-60, doi:10.1016/j.ocemod.2007.07.001, 2008. Ardhuin, F., et al., Semiempirical Dissipation Source Functions for Ocean Waves. Part I: Definition, Calibration, and Validation, J. Phys. Oceanogr., 40 (9), 1917-1941, doi:10.1175/2010JPO4324.1, 2010. Haas, K. A., and J. C. Warner, Comparing a quasi-3D to a full 3D nearshore circulation model: SHORECIRC and

  8. Possibilities of Preoperative Medical Models Made by 3D Printing or Additive Manufacturing

    PubMed Central

    2016-01-01

    Most of the 3D printing applications of preoperative models have been focused on dental and craniomaxillofacial area. The purpose of this paper is to demonstrate the possibilities in other application areas and give examples of the current possibilities. The approach was to communicate with the surgeons with different fields about their needs related preoperative models and try to produce preoperative models that satisfy those needs. Ten different kinds of examples of possibilities were selected to be shown in this paper and aspects related imaging, 3D model reconstruction, 3D modeling, and 3D printing were presented. Examples were heart, ankle, backbone, knee, and pelvis with different processes and materials. Software types required were Osirix, 3Data Expert, and Rhinoceros. Different 3D printing processes were binder jetting and material extrusion. This paper presents a wide range of possibilities related to 3D printing of preoperative models. Surgeons should be aware of the new possibilities and in most cases help from mechanical engineering side is needed. PMID:27433470

  9. Possibilities of Preoperative Medical Models Made by 3D Printing or Additive Manufacturing.

    PubMed

    Salmi, Mika

    2016-01-01

    Most of the 3D printing applications of preoperative models have been focused on dental and craniomaxillofacial area. The purpose of this paper is to demonstrate the possibilities in other application areas and give examples of the current possibilities. The approach was to communicate with the surgeons with different fields about their needs related preoperative models and try to produce preoperative models that satisfy those needs. Ten different kinds of examples of possibilities were selected to be shown in this paper and aspects related imaging, 3D model reconstruction, 3D modeling, and 3D printing were presented. Examples were heart, ankle, backbone, knee, and pelvis with different processes and materials. Software types required were Osirix, 3Data Expert, and Rhinoceros. Different 3D printing processes were binder jetting and material extrusion. This paper presents a wide range of possibilities related to 3D printing of preoperative models. Surgeons should be aware of the new possibilities and in most cases help from mechanical engineering side is needed.

  10. Review of the dWind Model Conceptual Results

    SciTech Connect

    Baring-Gould, Ian; Gleason, Michael; Preus, Robert; Sigrin, Ben

    2015-09-16

    This presentation provides an overview of the dWind model, including its purpose, background, and current status. Baring-Gould presented this material as part of the September 2015 WINDExchange webinar.

  11. Simulation of optical diagnostics for crystal growth: models and results

    NASA Astrophysics Data System (ADS)

    Banish, Michele R.; Clark, Rodney L.; Kathman, Alan D.; Lawson, Shelah M.

    1991-12-01

    A computer simulation of a two-color holographic interferometric (TCHI) optical system was performed using a physical (wave) optics model. This model accurately simulates propagation through time-varying, 2-D or 3-D concentration and temperature fields as a wave phenomenon. The model calculates wavefront deformations that can be used to generate fringe patterns. This simulation modeled a proposed TriGlycine sulphate TGS flight experiment by propagating through the simplified onion-like refractive index distribution of the growing crystal and calculating the recorded wavefront deformation. The phase of this wavefront was used to generate sample interferograms that map index of refraction variation. Two such fringe patterns, generated at different wavelengths, were used to extract the original temperature and concentration field characteristics within the growth chamber. This proves feasibility for this TCHI crystal growth diagnostic technique. This simulation provides feedback to the experimental design process.

  12. Demographic population model for American shad: will access to additional habitat upstream of dams increase population sizes?

    USGS Publications Warehouse

    Harris, Julianne E.; Hightower, Joseph E.

    2012-01-01

    American shad Alosa sapidissima are in decline in their native range, and modeling possible management scenarios could help guide their restoration. We developed a density-dependent, deterministic, stage-based matrix model to predict the population-level results of transporting American shad to suitable spawning habitat upstream of dams on the Roanoke River, North Carolina and Virginia. We used data on sonic-tagged adult American shad and oxytetracycline-marked American shad fry both above and below dams on the Roanoke River with information from other systems to estimate a starting population size and vital rates. We modeled the adult female population over 30 years under plausible scenarios of adult transport, effective fecundity (egg production), and survival of adults (i.e., to return to spawn the next year) and juveniles (from spawned egg to age 1). We also evaluated the potential effects of increased survival for adults and juveniles. The adult female population size in the Roanoke River was estimated to be 5,224. With no transport, the model predicted a slow population increase over the next 30 years. Predicted population increases were highest when survival was improved during the first year of life. Transport was predicted to benefit the population only if high rates of effective fecundity and juvenile survival could be achieved. Currently, transported adults and young are less likely to successfully out-migrate than individuals below the dams, and the estimated adult population size is much smaller than either of two assumed values of carrying capacity for the lower river; therefore, transport is not predicted to help restore the stock under present conditions. Research on survival rates, density-dependent processes, and the impacts of structures to increase out-migration success would improve evaluation of the potential benefits of access to additional spawning habitat for American shad.

  13. Construction of an extended library of adult male 3D models: rationale and results

    NASA Astrophysics Data System (ADS)

    Broggio, D.; Beurrier, J.; Bremaud, M.; Desbrée, A.; Farah, J.; Huet, C.; Franck, D.

    2011-12-01

    In order to best cover the possible extent of heights and weights of male adults the construction of 25 whole body 3D models has been undertaken. Such a library is thought to be useful to specify the uncertainties and relevance of dosimetry calculations carried out with models representing individuals of average body heights and weights. Representative 3D models of Caucasian body types are selected in a commercial database according to their height and weight, and 3D models of the skeleton and internal organs are designed using another commercial dataset. A review of the literature enabled one to fix volume or mass target values for the skeleton, soft organs, skin and fat content of the selected individuals. The composition of the remainder tissue is fixed so that the weight of the voxel models equals the weight of the selected individuals. After mesh and NURBS modelling, volume adjustment of the selected body shapes and additional voxel-based work, 25 voxel models with 109 identified organs or tissue are obtained. Radiation transport calculations are carried out with some of the developed models to illustrate potential uses. The following points are discussed throughout this paper: justification of the fixed or obtained models' features regarding available and relevant literature data; workflow and strategy for major modelling steps; advantages and drawbacks of the obtained library as compared with other works. The construction hypotheses are explained and justified in detail since future calculation results obtained with this library will depend on them.

  14. Europium anomaly in plagioclase feldspar - Experimental results and semiquantitative model.

    NASA Technical Reports Server (NTRS)

    Weill, D. F.; Drake, M. J.

    1973-01-01

    The partition of europium between plagioclase feldspar and magmatic liquid is considered in terms of the distribution coefficients for divalent and trivalent europium. A model equation is derived giving the europium anomaly in plagioclase as a function of temperature and oxygen fugacity. The model explains europium anomalies in plagioclase synthesized under controlled laboratory conditions as well as the variations of the anomaly observed in natural terrestrial and extraterrestrial igneous rocks.

  15. The Animal Model Determines the Results of Aeromonas Virulence Factors

    PubMed Central

    Romero, Alejandro; Saraceni, Paolo R.; Merino, Susana; Figueras, Antonio; Tomás, Juan M.; Novoa, Beatriz

    2016-01-01

    The selection of an experimental animal model is of great importance in the study of bacterial virulence factors. Here, a bath infection of zebrafish larvae is proposed as an alternative model to study the virulence factors of Aeromonas hydrophila. Intraperitoneal infections in mice and trout were compared with bath infections in zebrafish larvae using specific mutants. The great advantage of this model is that bath immersion mimics the natural route of infection, and injury to the tail also provides a natural portal of entry for the bacteria. The implication of T3SS in the virulence of A. hydrophila was analyzed using the AH-1::aopB mutant. This mutant was less virulent than the wild-type strain when inoculated into zebrafish larvae, as described in other vertebrates. However, the zebrafish model exhibited slight differences in mortality kinetics only observed using invertebrate models. Infections using the mutant AH-1ΔvapA lacking the gene coding for the surface S-layer suggested that this protein was not totally necessary to the bacteria once it was inside the host, but it contributed to the inflammatory response. Only when healthy zebrafish larvae were infected did the mutant produce less mortality than the wild-type. Variations between models were evidenced using the AH-1ΔrmlB, which lacks the O-antigen lipopolysaccharide (LPS), and the AH-1ΔwahD, which lacks the O-antigen LPS and part of the LPS outer-core. Both mutants showed decreased mortality in all of the animal models, but the differences between them were only observed in injured zebrafish larvae, suggesting that residues from the LPS outer core must be important for virulence. The greatest differences were observed using the AH-1ΔFlaB-J (lacking polar flagella and unable to swim) and the AH-1::motX (non-motile but producing flagella). They were as pathogenic as the wild-type strain when injected into mice and trout, but no mortalities were registered in zebrafish larvae. This study demonstrates

  16. Reducing model uncertainty effects in flexible manipulators through the addition of passive damping

    NASA Technical Reports Server (NTRS)

    Alberts, T. E.

    1987-01-01

    An important issue in the control of practical systems is the effect of model uncertainty on closed loop performance. This is of particular concern when flexible structures are to be controlled, due to the fact that states associated with higher frequency vibration modes are truncated in order to make the control problem tractable. Digital simulations of a single-link manipulator system are employed to demonstrate that passive damping added to the flexible member reduces adverse effects associated with model uncertainty. A controller was designed based on a model including only one flexible mode. This controller was applied to larger order systems to evaluate the effects of modal truncation. Simulations using a Linear Quadratic Regulator (LQR) design assuming full state feedback illustrate the effect of control spillover. Simulations of a system using output feedback illustrate the destabilizing effect of observation spillover. The simulations reveal that the system with passive damping is less susceptible to these effects than the untreated case.

  17. Understanding drivers of the export of dissolved organic carbon from a German headwater catchment using Generalised Additive Models

    NASA Astrophysics Data System (ADS)

    Selle, Benny; Musolff, Andreas; Tittel, Jörg

    2016-04-01

    In the literature, several causes of recently increasing concentrations of dissolved organic carbon (DOC) in headwaters across eastern North America and northern and central Europe have been debated. One likely driver of the widespread increase of DOC concentrations since the early 1990s are decreasing depositions of acid rain resulting in an increased solubility of organic carbon compounds including humic acids. Here, we tested the hypothesis if the reduced availability of nitrate stimulated the microbial reduction of ferric iron soil minerals and the mobilisation of DOC. Forested catchments are relatively unaffected by agricultural and urban nitrate inputs. In these catchments, decreasing depositions often resulted in a reduced availability of nitrate, which are preferred electron acceptors in microbial decomposition processes. As ferric iron minerals act as efficient sorbents of organic compounds in soils its reduction may cause a release of humic substances and hence an export of DOC. To test this hypothesis, time series of DOC, dissolved iron and nitrate from a forested headwater catchment in Germany were examined using Generalised Additive Models. We found that rising DOC concentrations most likely resulted from a reductive dissolution of iron(III) minerals in soils and the associated mobilisation of adsorbed organic carbon. Phosphate, which can trigger undesired algal growth and is also known to be adsorbed by particulate iron(III), was released as well.

  18. Preliminary results of a three-dimensional radiative transfer model

    SciTech Connect

    O`Hirok, W.

    1995-09-01

    Clouds act as the primary modulator of the Earth`s radiation at the top of the atmosphere, within the atmospheric column, and at the Earth`s surface. They interact with both shortwave and longwave radiation, but it is primarily in the case of shortwave where most of the uncertainty lies because of the difficulties in treating scattered solar radiation. To understand cloud-radiative interactions, radiative transfer models portray clouds as plane-parallel homogeneous entities to ease the computational physics. Unfortunately, clouds are far from being homogeneous, and large differences between measurement and theory point to a stronger need to understand and model cloud macrophysical properties. In an attempt to better comprehend the role of cloud morphology on the 3-dimensional radiation field, a Monte Carlo model has been developed. This model can simulate broadband shortwave radiation fluxes while incorporating all of the major atmospheric constituents. The model is used to investigate the cloud absorption anomaly where cloud absorption measurements exceed theoretical estimates and to examine the efficacy of ERBE measurements and cloud field experiments. 3 figs.

  19. Applying additive modeling and gradient boosting to assess the effects of watershed and reach characteristics on riverine assemblages

    USGS Publications Warehouse

    Maloney, Kelly O.; Schmid, Matthias; Weller, Donald E.

    2012-01-01

    Issues with ecological data (e.g. non-normality of errors, nonlinear relationships and autocorrelation of variables) and modelling (e.g. overfitting, variable selection and prediction) complicate regression analyses in ecology. Flexible models, such as generalized additive models (GAMs), can address data issues, and machine learning techniques (e.g. gradient boosting) can help resolve modelling issues. Gradient boosted GAMs do both. Here, we illustrate the advantages of this technique using data on benthic macroinvertebrates and fish from 1573 small streams in Maryland, USA.

  20. Laser ablation of a turbid medium: Modeling and experimental results

    SciTech Connect

    Brygo, F.; Semerok, A.; Weulersse, J.-M.; Thro, P.-Y.; Oltra, R.

    2006-08-01

    Q-switched Nd:YAG laser ablation of a turbid medium (paint) is studied. The optical properties (absorption coefficient, scattering coefficient, and its anisotropy) of a paint are determined with a multiple scattering model (three-flux model), and from measurements of reflection-transmission of light through thin layers. The energy deposition profiles are calculated at wavelengths of 532 nm and 1.064 {mu}m. They are different from those described by a Lambert-Beer law. In particular, the energy deposition of the laser beam is not maximum on the surface but at some depth inside the medium. The ablated rate was measured for the two wavelengths and compared with the energy deposition profile predicted by the model. This allows us to understand the evolution of the ablated depth with the wavelength: the more the scattering coefficient is higher, the more the ablated depth and the threshold fluence of ablation decrease.

  1. Additional Evidence Supporting a Model of Shallow, High-Speed Supergranulation

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Hanasoge, S. M.; Chakraborty, S.

    2014-01-01

    Recently, Duvall and Hanasoge (Solar Phys. 287, 71, 2013) found that large distance separation [delta] travel-time differences from a center to an annulus [deltat(sub oi)] implied a model of the average super granular cell that has a peak upflow of 240 ms(exp -1) at a depth of 2.3 Mm and a corresponding peak outward horizontal flow of 700 ms(exp -1) at a depth of 1.6 Mm. In the present work, this effect is further studied by measuring and modeling center-to-quadrant travel-time differences [deltat(sub qu)], which roughly agree with this model. Simulations are analyzed that show that such a model flow would lead to the expected travel-time differences. As a check for possible systematic errors, the center-to-annulus travel-time differences [deltat(sub oi)] are found not to vary with heliocentric angle. A consistency check finds an increase of deltat(sub oi) with the temporal frequency [?] by a factor of two, which is not predicted by the ray theory.

  2. 78 FR 12271 - Wireline Competition Bureau Seeks Additional Comment In Connect America Cost Model Virtual Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-22

    ... Virtual Workshop AGENCY: Federal Communications Commission. ACTION: Proposed rule. SUMMARY: In this... Site: http://fjallfoss.fcc.gov/ecfs2/ . Follow the instructions for submitting comments. Virtual...://www.fcc.gov/blog/wcb-cost-model-virtual-workshop-2012 . People with Disabilities: Contact the FCC...

  3. Results from Development of Model Specifications for Multifamily Energy Retrofits

    SciTech Connect

    Brozyna, K.

    2012-08-01

    Specifications, modeled after CSI MasterFormat, provide the trade contractors and builders with requirements and recommendations on specific building materials, components and industry practices that comply with the expectations and intent of the requirements within the various funding programs associated with a project. The goal is to create a greater level of consistency in execution of energy efficiency retrofits measures across the multiple regions a developer may work. IBACOS and Mercy Housing developed sample model specifications based on a common building construction type that Mercy Housing encounters.

  4. Results From Development of Model Specifications for Multifamily Energy Retrofits

    SciTech Connect

    Brozyna, Kevin

    2012-08-01

    Specifications, modeled after CSI MasterFormat, provide the trade contractors and builders with requirements and recommendations on specific building materials, components and industry practices that comply with the expectations and intent of the requirements within the various funding programs associated with a project. The goal is to create a greater level of consistency in execution of energy efficiency retrofits measures across the multiple regions a developer may work. IBACOS and Mercy Housing developed sample model specifications based on a common building construction type that Mercy Housing encounters.

  5. CesrTA Retarding Field Analyzer Modeling Results

    SciTech Connect

    Calvey, J.R.; Celata, C.M.; Crittenden, J.A.; Dugan, G.F.; Greenwald, S.; Leong, Z.; Livezey, J.; Palmer, M.A.; Furman, M.; Venturini, M.; Harkay, K.

    2010-05-23

    Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA itself, understanding these measurements can be nontrivial. This paper examines different methods for interpreting RFA data via cloud simulation programs. Techniques include postprocessing the output of a simulation code to predict the RFA response; and incorporating an RFA model into the cloud modeling program itself.

  6. Modeled heating and surface erosion comparing motile (gas borne) and stationary (surface coating) inert particle additives

    SciTech Connect

    Buckingham, A.C.; Siekhaus, W.J.

    1982-09-27

    The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.

  7. Environmental Model Interoperability Enabled by Open Geospatial Standards - Results of a Feasibility Study (Invited)

    NASA Astrophysics Data System (ADS)

    Benedict, K. K.; Yang, C.; Huang, Q.

    2010-12-01

    The availability of high-speed research networks such as the US National Lambda Rail and the GÉANT network, scalable on-demand commodity computing resources provided by public and private "cloud" computing systems, and increasing demand for rapid access to the products of environmental models for both research and public policy development contribute to a growing need for the evaluation and development of environmental modeling systems that distribute processing, storage, and data delivery capabilities between network connected systems. In an effort to address the feasibility of developing a standards-based distributed modeling system in which model execution systems are physically separate from data storage and delivery systems, the research project presented in this paper developed a distributed dust forecasting system in which two nested atmospheric dust models are executed at George Mason University (GMU, in Fairfax, VA) while data and model output processing services are hosted at the University of New Mexico (UNM, in Albuquerque, NM). Exchange of model initialization and boundary condition parameters between the servers at UNM and the model execution systems at GMU is accomplished through Open Geospatial Consortium (OGC) Web Coverage Services (WCS) and Web Feature Services (WFS) while model outputs are pushed from GMU systems back to UNM using a REST web service interface. In addition to OGC and non-OGC web services for exchange between UNM and GMU, the servers at UNM also provide access to the input meteorological model products, intermediate and final dust model outputs, and other products derived from model outputs through OGC WCS, WFS, and OGC Web Map Services (WMS). The performance of the nested versus non-nested models is assessed in this research, with the results of the performance analysis providing the core content of the produced feasibility study. System integration diagram illustrating the storage and service platforms hosted at the Earth Data

  8. Results of the 2013 UT modeling benchmark obtained with models implemented in CIVA

    SciTech Connect

    Toullelan, Gwénaël; Raillon, Raphaële; Chatillon, Sylvain; Lonne, Sébastien

    2014-02-18

    The 2013 Ultrasonic Testing (UT) modeling benchmark concerns direct echoes from side drilled holes (SDH), flat bottom holes (FBH) and corner echoes from backwall breaking artificial notches inspected with a matrix phased array probe. This communication presents the results obtained with the models implemented in the CIVA software: the pencilmodel is used to compute the field radiated by the probe, the Kirchhoff approximation is applied to predict the response of FBH and notches and the SOV (Separation Of Variables) model is used for the SDH responses. The comparison between simulated and experimental results are presented and discussed.

  9. Growth Model Comparison Study: A Summary of Results

    ERIC Educational Resources Information Center

    Auty, Bill; Brockmann, Frank

    2012-01-01

    School accountability is subject to considerable scrutiny. It generates sharp political debate, policy challenges, and continuous discussion. Growth models are now a part of that discussion. To many practitioners the sheer volume of "important to know" information is daunting. The members of the Technical Issues in Large Scale Assessment…

  10. Applying modeling Results in designing a global tropospheric experiment

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A set of field experiments and advanced modeling studies which provide a strategy for a program of global tropospheric experiments was identified. An expanded effort to develop space applications for trospheric air quality monitoring and studies was recommended. The tropospheric ozone, carbon, nitrogen, and sulfur cycles are addressed. Stratospheric-tropospheric exchange is discussed. Fast photochemical processes in the free troposphere are considered.

  11. New Results in Software Model Checking and Analysis

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.

    2010-01-01

    This introductory article surveys new techniques, supported by automated tools, for the analysis of software to ensure reliability and safety. Special focus is on model checking techniques. The article also introduces the five papers that are enclosed in this special journal volume.

  12. A computer model to forecast wetland vegetation changes resulting from restoration and protection in coastal Louisiana

    USGS Publications Warehouse

    Visser, Jenneke M.; Duke-Sylvester, Scott M.; Carter, Jacoby; Broussard, Whitney P.

    2013-01-01

    The coastal wetlands of Louisiana are a unique ecosystem that supports a diversity of wildlife as well as a diverse community of commercial interests of both local and national importance. The state of Louisiana has established a 5-year cycle of scientific investigation to provide up-to-date information to guide future legislation and regulation aimed at preserving this critical ecosystem. Here we report on a model that projects changes in plant community distribution and composition in response to environmental conditions. This model is linked to a suite of other models and requires input from those that simulate the hydrology and morphology of coastal Louisiana. Collectively, these models are used to assess how alternative management plans may affect the wetland ecosystem through explicit spatial modeling of the physical and biological processes affected by proposed modifications to the ecosystem. We have also taken the opportunity to advance the state-of-the-art in wetland plant community modeling by using a model that is more species-based in its description of plant communities instead of one based on aggregated community types such as brackish marsh and saline marsh. The resulting model provides an increased level of ecological detail about how wetland communities are expected to respond. In addition, the output from this model provides critical inputs for estimating the effects of management on higher trophic level species though a more complete description of the shifts in habitat.

  13. First Results from the Physics-Based Forecasting-Targeted Inner Heliosphere Model Euhforia

    NASA Astrophysics Data System (ADS)

    Pomoell, J.

    2015-12-01

    In this work, we present the first results of the new physics-based forecasting-targeted inner heliosphere model Euhforia ('European heliospheric forecasting information asset') that we are developing. Euhforia consists of a coronal model and a magnetohydrodynamic (MHD) heliosphere model with CMEs. The aim of the baseline coronal model is to produce realistic plasma conditions at the interface radius r = 0.1 AU between the two models thus providing the necessary input to the time-dependent, three-dimensional MHD heliosphere model. It uses GONG synoptic line-of-sight magnetograms as input for a potential (PFSS) field extrapolation of the low-coronal magnetic field coupled to a current sheet (CS) model of the extended coronal magnetic field. The plasma variables at the interface radius are determined by employing semi-empirical considerations based on the properties of the PFSS+CS field such as the flux tube expansion factor and distance to nearest coronal hole. The heliosphere model computes the time-dependent evolution of the MHD variables from the interface radius typically up to 2 AU. Coronal mass ejections (CMEs) are injected at the interface radius using a hydrodynamic cone-like model using parameters constrained from fits to coronal imaging observations. In order to account for the modification of the heliosphere due to the presence of earlier CMEs, the standard run scenario includes CMEs launched five days prior to the start of the forecast, while the duration of the forecast extends up to seven days. In addition to presenting results of the modeling, we will highlight our on-going efforts to advance beyond the baseline in the forecasting pipeline. In particular we discuss our path towards using magnetized CMEs, application of a time-dependent coronal model as well as modeling the transport of solar energetic particles (SEPs) in the heliosphere.

  14. Busted Butte: Achieving the Objectives and Numerical Modeling Results

    SciTech Connect

    W.E. Soll; M. Kearney; P. Stauffer; P. Tseng; H.J. Turin; Z. Lu

    2002-10-07

    The Unsaturated Zone Transport Test (UZTT) at Busted Butte is a mesoscale field/laboratory/modeling investigation designed to address uncertainties associated with flow and transport in the UZ site-process models for Yucca Mountain. The UZTT test facility is located approximately 8 km southeast of the potential Yucca Mountain repository area. The UZTT was designed in two phases, to address five specific objectives in the UZ: the effect of heterogeneities, flow and transport (F&T) behavior at permeability contrast boundaries, migration of colloids , transport models of sorbing tracers, and scaling issues in moving from laboratory scale to field scale. Phase 1A was designed to assess the influence of permeability contrast boundaries in the hydrologic Calico Hills. Visualization of fluorescein movement , mineback rock analyses, and comparison with numerical models demonstrated that F&T are capillary dominated with permeability contrast boundaries distorting the capillary flow. Phase 1B was designed to assess the influence of fractures on F&T and colloid movement. The injector in Phase 1B was located at a fracture, while the collector, 30 cm below, was placed at what was assumed to be the same fracture. Numerical simulations of nonreactive (Br) and reactive (Li) tracers show the experimental data are best explained by a combination of molecular diffusion and advective flux. For Phase 2, a numerical model with homogeneous unit descriptions was able to qualitatively capture the general characteristics of the system. Numerical simulations and field observations revealed a capillary dominated flow field. Although the tracers showed heterogeneity in the test block, simulation using heterogeneous fields did not significantly improve the data fit over homogeneous field simulations. In terms of scaling, simulations of field tracer data indicate a hydraulic conductivity two orders of magnitude higher than measured in the laboratory. Simulations of Li, a weakly sorbing tracer

  15. The Development of Mathematical Prediction Model to Predict Resilient Modulus for Natural Soil Stabilized by Pofa-Opc Additive for the Use in Unpaved Road Design

    NASA Astrophysics Data System (ADS)

    Gamil, Y. M. R.; Bakar, I. H.

    2016-07-01

    Resilient Modulus (Mr) is considered one of the most important parameters in the design of road structure. This paper describes the development of the mathematical model to predict resilient modulus of organic soil stabilized by the mix of Palm Oil Fuel Ash - Ordinary Portland Cement (POFA-OPC) soil stabilization additives. It aims to optimize the use of the use of POFA in soil stabilization. The optimization models enable to eliminate the arbitrary selection and its associated disadvantages in determination of the optimum additive proportion. The model was developed based on Scheffe regression theory. The mix proportions of the samples in the experiment were adopted from similar studies reported in the literature Twenty five samples were designed, prepared and then characterized for each mix proportion based on the MR in 28 days curing. The results are used to develop the mathematical prediction model. The model was statistically analyzed and verified for its adequacy and validity using F-test.

  16. Hoop/Column Antenna: RF Verification Model. Volume 1: Test Results

    NASA Technical Reports Server (NTRS)

    Croswell, W. F. (Editor); Vanstrum, M. D.; Schrimpf, R. J.; Taylor, R. G.; Moye, R. L.

    1984-01-01

    As part of the Large Space System Technology Program, this report, in two volumes, presents the theoretical and experimental results of the RF characteristic of a hoop/column, quad aperture antenna using an RF verification model. To satisfy the primary purposes of the model it provides experimental pattern data for the quad aperture configuration at different reflector edge illumination levels, from which the geometry and edge effects can be assessed, and provides experimental data which can be compared with calculations using various theoretical reflector scattering formulae. It also experimentally determines the effects upon secondary patterns of scale model quartz cables, as used in the hoop/column design, upon secondary patterns in order to assess the importance of developing a scattering theory to predict such effects. In addition, this report contains a comprehensive theoretical study and the experimental pattern results of quad aperture antenna feeds, a discussion of the fundamental affect of parasitic side lobes, their amplitude, and location in space.

  17. SModelS: A Tool for Making Systematic Use of Simplified Models Results

    NASA Astrophysics Data System (ADS)

    Waltenberger, Wolfgang; SModelS Group

    2016-10-01

    We present an automated software tool ”SModelS” to systematically confront theories Beyond the Standard Model (BSM) with experimental data. The tool consists of a general procedure to decompose such BSM theories into their Simplified Models Spectra (SMS). In addition, SModelS features a database containing the majority of the published SMS results of CMS and ATLAS. These results consist of the 95% confidence level upper limits on signal production cross sections. The two components together allow us to quickly confront any BSM model with LHC results. As a show-case example we will briefly discuss an application of our procedure to a specific supersymmetric model. It is one of our ongoing efforts to extend the framework to include also efficiency maps produced either by the experimental collaborations, by efforts performed within the phenomenological groups, or possibly also by ourselves. While the current implementation can handle null results only, it is our ultimate goal to build the Next Standard Model in a bottom-up fashion from both negative and positive results of several experiments. The implementation is open source, written in python, and available from http://smodels.hephy.at.

  18. Results on a binding neuron model and their implications for modified hourglass model for neuronal network.

    PubMed

    Arunachalam, Viswanathan; Akhavan-Tabatabaei, Raha; Lopez, Cristina

    2013-01-01

    The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008) in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.

  19. Hydrogen radical additions to unsaturated hydrocarbons and the reverse beta-scission reactions: modeling of activation energies and pre-exponential factors.

    PubMed

    Sabbe, Maarten K; Reyniers, Marie-Françoise; Waroquier, Michel; Marin, Guy B

    2010-01-18

    The group additivity method for Arrhenius parameters is applied to hydrogen addition to alkenes and alkynes and the reverse beta-scission reactions, an important family of reactions in thermal processes based on radical chemistry. A consistent set of group additive values for 33 groups is derived to calculate the activation energy and pre-exponential factor for a broad range of hydrogen addition reactions. The group additive values are determined from CBS-QB3 ab-initio-calculated rate coefficients. A mean factor of deviation of only two between CBS-QB3 and experimental rate coefficients for seven reactions in the range 300-1000 K is found. Tunneling coefficients for these reactions were found to be significant below 400 K and a correlation accounting for tunneling is presented. Application of the obtained group additive values to predict the kinetics for a set of 11 additions and beta-scissions yields rate coefficients within a factor of 3.5 of the CBS-QB3 results except for two beta-scissions with severe steric effects. The mean factor of deviation with respect to experimental rate coefficients of 2.0 shows that the group additive method with tunneling corrections can accurately predict the kinetics and is at least as accurate as the most commonly used density functional methods. The constructed group additive model can hence be applied to predict the kinetics of hydrogen radical additions for a broad range of unsaturated compounds.

  20. When a Model Needs a Model: Convincing Skeptics of Counterintuitive Results--An Example from Affirmative Action Modeling.

    ERIC Educational Resources Information Center

    Feinberg, William E.

    1988-01-01

    This article describes a monte carlo computer simulation of affirmative action employment policies. The counterintuitive results of the model are explained through a thought device involving urns and marbles. States that such model simulations have implications for social policy. (BSR)

  1. Thermal buoyancy on Venus: Preliminary results of finite element modeling

    NASA Technical Reports Server (NTRS)

    Burt, J. D.; Head, James W., III

    1992-01-01

    Enhanced surface temperatures and a thinner lithosphere on Venus relative to Earth have been cited as leading to increased lithospheric buoyancy. This would limit or prevent subduction on Venus and favor the construction of thickened crust through underthrusting. In order to evaluate the conditions distinguishing between underthrusting and subduction, we have modeled the thermal and buoyancy consequences of the subduction end member. This study considers the fate of a slab from the time it starts to subduct, but bypasses the question of subduction initiation. Thermal changes in slabs subducting into a mantle having a range of initial geotherms are used to predict density changes and thus their overall buoyancy. Finite element modeling is then applied in a first approximation of the assessment of the relative rates of subduction as compared to the buoyant rise of the slab through a viscous mantle.

  2. Total Sky Imager Model 880 Status and Testing Results

    SciTech Connect

    Long, CN; Slater, DW; Tooman, T

    2001-11-01

    The Total Sky Imager (TSI) is manufactured by Yankee Environmental Systems (YES) Incorporated, based in Turner Falls, Massachusetts. (For more information about YES, see http://www.yesinc.com/.) The TSI is a commercialized version of the Hemispheric Sky Imager prototype (Long et al. 1998). YES has now produced a more sophisticated (compared to the original model 440) model 880 of the TSI (see Figure 1). The first YES TSI 880 was deployed at the Blackwell Tonkawa Airport (BTA) as part of the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program 2000 Cloud intensive operational period (IOP). This TSI 880 collected data from March 2, 2000 through April 6, 2000. This report gives an assessment of the TSI based on the BTA and Southern Great Plane (SGP) Central Facility (CF) data collected to date.

  3. Modeling Results on the Seasonal Influence at the Martian Exosphere

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Dolon; Clarke, John; Bertaux, Jean-Loup; Chaufray, Jean-Yves; Mayyasi, Majd

    2015-11-01

    Analysis of HST ACS/SBC images of Mars in the far-ultraviolet taken in Oct-Nov 2007 and May-November 2014 indicate seasonal influence as a driving factor of the hydrogen corona, as has been reported earlier. To derive the changes in number density and temperature, the data must be compared to a radiative transfer model to simulate the resonantly scattered optically thick Lyman α emission from the exosphere of Mars. This work presents details on the modeling process used to analyze the data and the corresponding uncertainties. The escape flux is highly dependent on the characteristics of the martian exosphere like the exobase temperature and number density of H atoms as well as the presence or absence of a superthermal population of hydrogen atoms. Detailed studies on the workings of the radiative transfer model indicate degeneracy between temperature and number density values that can fit the data. Therefore it is difficult to accurately determine the characteristics of the martian hydrogen exosphere without independent measurement of at least one of the variables. However, HST observations have the advantage of observing a large portion of the dayside exosphere with intensity profiles extending from altitudes of 700 - 30,000 km giving a better estimate of the best-fit temperature and density values which characterize the martian exosphere under different seasonal conditions. Comparisons of the latitudinal symmetry from the HST images indicate the exosphere to be symmetric beyond 2.5 martian radii due to the broad trajectories of atoms at high altitudes.

  4. Sharing brain mapping statistical results with the neuroimaging data model

    PubMed Central

    Maumet, Camille; Auer, Tibor; Bowring, Alexander; Chen, Gang; Das, Samir; Flandin, Guillaume; Ghosh, Satrajit; Glatard, Tristan; Gorgolewski, Krzysztof J.; Helmer, Karl G.; Jenkinson, Mark; Keator, David B.; Nichols, B. Nolan; Poline, Jean-Baptiste; Reynolds, Richard; Sochat, Vanessa; Turner, Jessica; Nichols, Thomas E.

    2016-01-01

    Only a tiny fraction of the data and metadata produced by an fMRI study is finally conveyed to the community. This lack of transparency not only hinders the reproducibility of neuroimaging results but also impairs future meta-analyses. In this work we introduce NIDM-Results, a format specification providing a machine-readable description of neuroimaging statistical results along with key image data summarising the experiment. NIDM-Results provides a unified representation of mass univariate analyses including a level of detail consistent with available best practices. This standardized representation allows authors to relay methods and results in a platform-independent regularized format that is not tied to a particular neuroimaging software package. Tools are available to export NIDM-Result graphs and associated files from the widely used SPM and FSL software packages, and the NeuroVault repository can import NIDM-Results archives. The specification is publically available at: http://nidm.nidash.org/specs/nidm-results.html. PMID:27922621

  5. Sharing brain mapping statistical results with the neuroimaging data model.

    PubMed

    Maumet, Camille; Auer, Tibor; Bowring, Alexander; Chen, Gang; Das, Samir; Flandin, Guillaume; Ghosh, Satrajit; Glatard, Tristan; Gorgolewski, Krzysztof J; Helmer, Karl G; Jenkinson, Mark; Keator, David B; Nichols, B Nolan; Poline, Jean-Baptiste; Reynolds, Richard; Sochat, Vanessa; Turner, Jessica; Nichols, Thomas E

    2016-12-06

    Only a tiny fraction of the data and metadata produced by an fMRI study is finally conveyed to the community. This lack of transparency not only hinders the reproducibility of neuroimaging results but also impairs future meta-analyses. In this work we introduce NIDM-Results, a format specification providing a machine-readable description of neuroimaging statistical results along with key image data summarising the experiment. NIDM-Results provides a unified representation of mass univariate analyses including a level of detail consistent with available best practices. This standardized representation allows authors to relay methods and results in a platform-independent regularized format that is not tied to a particular neuroimaging software package. Tools are available to export NIDM-Result graphs and associated files from the widely used SPM and FSL software packages, and the NeuroVault repository can import NIDM-Results archives. The specification is publically available at: http://nidm.nidash.org/specs/nidm-results.html.

  6. Proposed Schematics and Modeling Results for a Lunar Portable Life Support System

    NASA Technical Reports Server (NTRS)

    Conger, Bruce; Chullen, Cinda

    2009-01-01

    The Constellation Space Suit Element (CSSE) is an integrated assembly made up of primarily a Pressure Garment System (PGS) and a Portable Life Support System (PLSS). The PLSS is further composed of an oxygen (O2) subsystem, a ventilation subsystem, and a thermal subsystem. This paper baselines a detailed schematic of the CSSE PLSS to provide a basis for current and future CSSE PLSS development efforts. Both context diagrams and detailed schematics describe the hardware components and overall functions for all three of the PLSS subsystems. Additionally, PLSS functions are presented for multiple operational scenarios as follows: 1) Nominal Extravehicular Activity (EVA) Mode; 2) Umbilical Modes; a) No Recharge, b) With Recharge; 3) Decompression Sickness (DCS) Treatment Mode; 4) Buddy Mode; 5) Secondary O2 Modes; a) Helmet Purge; b) Suit Purge; c) Operational; and 5) PLSS Removed Umbilical Mode. A performance modeling effort is being performed to provide a preliminary confirmation of this layout and the current state of the thermal hydraulic modeling efforts being conducted for the PLSS is presented. The goal of these efforts is to provide realistic simulations of the PLSS under various modes of operation. Modeling approaches and assumptions are discussed as well as component model descriptions. Results from the models are included that show PLSS operations at steady-state and transient conditions. Finally, conclusions and recommendations are offered that summarize results, identify PLSS design weaknesses uncovered during review of the analysis results, and propose areas for improvement to increase model fidelity and accuracy.

  7. The Job Demands-Resources Model: An Analysis of Additive and Joint Effects of Demands and Resources

    ERIC Educational Resources Information Center

    Hu, Qiao; Schaufeli, Wilmar B.; Taris, Toon W.

    2011-01-01

    The present study investigated the additive, synergistic, and moderating effects of job demands and job resources on well-being (burnout and work engagement) and organizational outcomes, as specified by the Job Demands-Resources (JD-R) model. A survey was conducted among two Chinese samples: 625 blue collar workers and 761 health professionals. A…

  8. Pulsed addition of HMF and furfural to batch-grown xylose-utilizing Saccharomyces cerevisiae results in different physiological responses in glucose and xylose consumption phase

    PubMed Central

    2013-01-01

    Background Pretreatment of lignocellulosic biomass generates a number of undesired degradation products that can inhibit microbial metabolism. Two of these compounds, the furan aldehydes 5-hydroxymethylfurfural (HMF) and 2-furaldehyde (furfural), have been shown to be an impediment for viable ethanol production. In the present study, HMF and furfural were pulse-added during either the glucose or the xylose consumption phase in order to dissect the effects of these inhibitors on energy state, redox metabolism, and gene expression of xylose-consuming Saccharomyces cerevisiae. Results Pulsed addition of 3.9 g L-1 HMF and 1.2 g L-1 furfural during either the glucose or the xylose consumption phase resulted in distinct physiological responses. Addition of furan aldehydes in the glucose consumption phase was followed by a decrease in the specific growth rate and the glycerol yield, whereas the acetate yield increased 7.3-fold, suggesting that NAD(P)H for furan aldehyde conversion was generated by acetate synthesis. No change in the intracellular levels of NAD(P)H was observed 1 hour after pulsing, whereas the intracellular concentration of ATP increased by 58%. An investigation of the response at transcriptional level revealed changes known to be correlated with perturbations in the specific growth rate, such as protein and nucleotide biosynthesis. Addition of furan aldehydes during the xylose consumption phase brought about an increase in the glycerol and acetate yields, whereas the xylitol yield was severely reduced. The intracellular concentrations of NADH and NADPH decreased by 58 and 85%, respectively, hence suggesting that HMF and furfural drained the cells of reducing power. The intracellular concentration of ATP was reduced by 42% 1 hour after pulsing of inhibitors, suggesting that energy-requiring repair or maintenance processes were activated. Transcriptome profiling showed that NADPH-requiring processes such as amino acid biosynthesis and sulfate and

  9. Longitudinal functional additive model with continuous proportional outcomes for physical activity data.

    PubMed

    Li, Haocheng; Kozey-Keadle, Sarah; Kipnis, Victor; Carroll, Raymond J

    2016-01-01

    Motivated by physical activity data obtained from the BodyMedia FIT device (www.bodymedia.com), we take a functional data approach for longitudinal studies with continuous proportional outcomes. The functional structure depends on three factors. In our three-factor model, the regression structures are specified as curves measured at various factor-points with random effects that have a correlation structure. The random curve for the continuous factor is summarized using a few important principal components. The difficulties in handling the continuous proportion variables are solved by using a quasilikelihood type approximation. We develop an efficient algorithm to fit the model, which involves the selection of the number of principal components. The method is evaluated empirically by a simulation study. This approach is applied to the BodyMedia data with 935 males and 84 consecutive days of observation, for a total of 78, 540 observations. We show that sleep efficiency increases with increasing physical activity, while its variance decreases at the same time.

  10. Modeling probability of additional cases of natalizumab-associated JCV sero-negative progressive multifocal leukoencephalopathy.

    PubMed

    Carruthers, Robert L; Chitnis, Tanuja; Healy, Brian C

    2014-05-01

    JCV serologic status is used to determine PML risk in natalizumab-treated patients. Given two cases of natalizumab-associated PML in JCV sero-negative patients and two publications that question the false negative rate of the JCV serologic test, clinicians may question whether our understanding of PML risk is adequate. Given that there is no gold standard for diagnosing previous JCV exposure, the test characteristics of the JCV serologic test are unknowable. We propose a model of PML risk in JCV sero-negative natalizumab patients. Using the numbers of JCV sero-positive and -negative patients from a study of PML risk by JCV serologic status (sero-positive: 13,950 and sero-negative: 11,414), we apply a range of sensitivities and specificities in order calculate the number of JCV-exposed but JCV sero-negative patients (false negatives). We then apply a range of rates of developing PML in sero-negative patients to calculate the expected number of PML cases. By using the binomial function, we calculate the probability of a given number of JCV sero-negative PML cases. With this model, one has a means to establish a threshold number of JCV sero-negative natalizumab-associated PML cases at which it is improbable that our understanding of PML risk in JCV sero-negative patients is adequate.

  11. Performance and modeling of active metal-matrix composites manufactured by ultrasonic additive manufacturing

    NASA Astrophysics Data System (ADS)

    Hahnlen, Ryan; Dapino, Marcelo J.

    2011-04-01

    This paper presents the development and characterization of active aluminum-matrix composites manufactured by Ultrasonic Additive Manufacturing (UAM), an emerging rapid prototyping process based on ultrasonic metal welding. The primary benefit of UAM over other metal-matrix fabrication processes is the low process temperatures, as low as 25 °C. UAM thus provides unprecedented opportunities to develop adaptive structures with seamlessly embedded smart materials and electronic components without degrading the properties that make these materials and components attractive. The objective of this research is to develop UAM composites with aluminum matrices and embedded shape memory NiTi, magnetostrictive Galfenol (FeGa), and polyvinylidene fluoride (PVDF) phases. The paper is focused on the thermally induced strain response and stiffness behavior of NiTi-Al composites, the actuation properties of FeGa-Al composites, and the embedded sensing capabilities of PVDF-Al composites. We observe up to a 10% increase over room temperature stiffness for NiTi-Al composites and a magnetomechanical response in the FeGa-Al composite up to 52.4 μɛ. The response of the PVDF-Al composite to harmonic loads is observed over a frequency range of 10 to 1000 Hz.

  12. First Results of PIC Modeling of Kinetic Alfven Wave Dissipation

    NASA Technical Reports Server (NTRS)

    Chulaki, Anna; Hesse, Michael; Zenitani, Seiji

    2007-01-01

    We present first results of an investigation of the kinetic damping of Alfven wave turbulence. The methodology is based on a fully electromagnetic, three-dimensional, particle in cell code. The calculation is initialized by an Alfven wave spectrum. Subsequently, a cascade develops, and damping by coupling to both ions and electrons is observed. We discuss results of these calculations, and present first estimates of damping rates and of the effects of energy transfer on ion and electron distributions. The results pertain to solar wind heating and acceleration.

  13. Modeling the QBO—Improvements resulting from higher-model vertical resolution

    NASA Astrophysics Data System (ADS)

    Geller, Marvin A.; Zhou, Tiehan; Shindell, D.; Ruedy, R.; Aleinov, I.; Nazarenko, L.; Tausnev, N. L.; Kelley, M.; Sun, S.; Cheng, Y.; Field, R. D.; Faluvegi, G.

    2016-09-01

    Using the NASA Goddard Institute for Space Studies (GISS) climate model, it is shown that with proper choice of the gravity wave momentum flux entering the stratosphere and relatively fine vertical layering of at least 500 m in the upper troposphere-lower stratosphere (UTLS), a realistic stratospheric quasi-biennial oscillation (QBO) is modeled with the proper period, amplitude, and structure down to tropopause levels. It is furthermore shown that the specified gravity wave momentum flux controls the QBO period whereas the width of the gravity wave momentum flux phase speed spectrum controls the QBO amplitude. Fine vertical layering is required for the proper downward extension to tropopause levels as this permits wave-mean flow interactions in the UTLS region to be resolved in the model. When vertical resolution is increased from 1000 to 500 m, the modeled QBO modulation of the tropical tropopause temperatures increasingly approach that from observations, and the "tape recorder" of stratospheric water vapor also approaches the observed. The transport characteristics of our GISS models are assessed using age-of-air and N2O diagnostics, and it is shown that some of the deficiencies in model transport that have been noted in previous GISS models are greatly improved for all of our tested model vertical resolutions. More realistic tropical-extratropical transport isolation, commonly referred to as the "tropical pipe," results from the finer vertical model layering required to generate a realistic QBO.

  14. Modeling the QBO—Improvements resulting from higher‐model vertical resolution

    PubMed Central

    Zhou, Tiehan; Shindell, D.; Ruedy, R.; Aleinov, I.; Nazarenko, L.; Tausnev, N. L.; Kelley, M.; Sun, S.; Cheng, Y.; Field, R. D.; Faluvegi, G.

    2016-01-01

    Abstract Using the NASA Goddard Institute for Space Studies (GISS) climate model, it is shown that with proper choice of the gravity wave momentum flux entering the stratosphere and relatively fine vertical layering of at least 500 m in the upper troposphere‐lower stratosphere (UTLS), a realistic stratospheric quasi‐biennial oscillation (QBO) is modeled with the proper period, amplitude, and structure down to tropopause levels. It is furthermore shown that the specified gravity wave momentum flux controls the QBO period whereas the width of the gravity wave momentum flux phase speed spectrum controls the QBO amplitude. Fine vertical layering is required for the proper downward extension to tropopause levels as this permits wave‐mean flow interactions in the UTLS region to be resolved in the model. When vertical resolution is increased from 1000 to 500 m, the modeled QBO modulation of the tropical tropopause temperatures increasingly approach that from observations, and the “tape recorder” of stratospheric water vapor also approaches the observed. The transport characteristics of our GISS models are assessed using age‐of‐air and N2O diagnostics, and it is shown that some of the deficiencies in model transport that have been noted in previous GISS models are greatly improved for all of our tested model vertical resolutions. More realistic tropical‐extratropical transport isolation, commonly referred to as the “tropical pipe,” results from the finer vertical model layering required to generate a realistic QBO. PMID:27917258

  15. Modeling the QBO-Improvements resulting from higher-model vertical resolution.

    PubMed

    Geller, Marvin A; Zhou, Tiehan; Shindell, D; Ruedy, R; Aleinov, I; Nazarenko, L; Tausnev, N L; Kelley, M; Sun, S; Cheng, Y; Field, R D; Faluvegi, G

    2016-09-01

    Using the NASA Goddard Institute for Space Studies (GISS) climate model, it is shown that with proper choice of the gravity wave momentum flux entering the stratosphere and relatively fine vertical layering of at least 500 m in the upper troposphere-lower stratosphere (UTLS), a realistic stratospheric quasi-biennial oscillation (QBO) is modeled with the proper period, amplitude, and structure down to tropopause levels. It is furthermore shown that the specified gravity wave momentum flux controls the QBO period whereas the width of the gravity wave momentum flux phase speed spectrum controls the QBO amplitude. Fine vertical layering is required for the proper downward extension to tropopause levels as this permits wave-mean flow interactions in the UTLS region to be resolved in the model. When vertical resolution is increased from 1000 to 500 m, the modeled QBO modulation of the tropical tropopause temperatures increasingly approach that from observations, and the "tape recorder" of stratospheric water vapor also approaches the observed. The transport characteristics of our GISS models are assessed using age-of-air and N2O diagnostics, and it is shown that some of the deficiencies in model transport that have been noted in previous GISS models are greatly improved for all of our tested model vertical resolutions. More realistic tropical-extratropical transport isolation, commonly referred to as the "tropical pipe," results from the finer vertical model layering required to generate a realistic QBO.

  16. NASA Air Force Cost Model (NAFCOM): Capabilities and Results

    NASA Technical Reports Server (NTRS)

    McAfee, Julie; Culver, George; Naderi, Mahmoud

    2011-01-01

    NAFCOM is a parametric estimating tool for space hardware. Uses cost estimating relationships (CERs) which correlate historical costs to mission characteristics to predict new project costs. It is based on historical NASA and Air Force space projects. It is intended to be used in the very early phases of a development project. NAFCOM can be used at the subsystem or component levels and estimates development and production costs. NAFCOM is applicable to various types of missions (crewed spacecraft, uncrewed spacecraft, and launch vehicles). There are two versions of the model: a government version that is restricted and a contractor releasable version.

  17. MCNP Modeling Results for Location of Buried TRU Waste Drums

    NASA Astrophysics Data System (ADS)

    Steinman, D. K.; Schweitzer, J. S.

    2006-05-01

    In the 1960's, fifty-five gallon drums of TRU waste were buried in shallow pits on remote U.S. Government facilities such as the Idaho National Engineering Laboratory (now split into the Idaho National Laboratory and the Idaho Completion Project [ICP]). Subsequently, it was decided to remove the drums and the material that was in them from the burial pits and send the material to the Waste Isolation Pilot Plant in New Mexico. Several technologies have been tried to locate the drums non-intrusively with enough precision to minimize the chance for material to be spread into the environment. One of these technologies is the placement of steel probe holes in the pits into which wireline logging probes can be lowered to measure properties and concentrations of material surrounding the probe holes for evidence of TRU material. There is also a concern that large quantities of volatile organic compounds (VOC) are also present that would contaminate the environment during removal. In 2001, the Idaho National Engineering and Environmental Laboratory (INEEL) built two pulsed neutron wireline logging tools to measure TRU and VOC around the probe holes. The tools are the Prompt Fission Neutron (PFN) and the Pulsed Neutron Gamma (PNG), respectively. They were tested experimentally in surrogate test holes in 2003. The work reported here estimates the performance of the tools using Monte-Carlo modelling prior to field deployment. A MCNP model was constructed by INEEL personnel. It was modified by the authors to assess the ability of the tools to predict quantitatively the position and concentration of TRU and VOC materials disposed around the probe holes. The model was used to simulate the tools scanning the probe holes vertically in five centimetre increments. A drum was included in the model that could be placed near the probe hole and at other locations out to forty-five centimetres from the probe-hole in five centimetre increments. Scans were performed with no chlorine in the

  18. Test results from a dynamic model dynaflex rotor

    NASA Technical Reports Server (NTRS)

    Niebanck, C. F.; Goodman, R. K.

    1985-01-01

    A one-fifth scale dynamic model of the Sikorsky Dynaflex rotor was tested in hover and in forward flight conditions in a wind tunnel. The Dynaflex rotor features an advanced composite structure which flexes to provide a constant speed universal joint action. Testing concentrated on confirming that the stability and dynamic response of the rotor were satisfactory. Lift conditions of up to .11 Ct/sigma and advance ratios as high as .46 were reached. Vibratory loads were compared to those of articulated rotors. The Dynaflex rotor concept appears to be a practical concept from the standpoint of dynamic response and stability.

  19. Starch plus sunflower oil addition to the diet of dry dairy cows results in a trans-11 to trans-10 shift of biohydrogenation.

    PubMed

    Zened, A; Enjalbert, F; Nicot, M C; Troegeler-Meynadier, A

    2013-01-01

    Trans fatty acids (FA), exhibit different biological properties. Among them, cis-9,trans-11 conjugated linoleic acid has some interesting putative health properties, whereas trans-10,cis-12 conjugated linoleic acid has negative effects on cow milk fat production and would negatively affect human health. In high-yielding dairy cows, a shift from trans-11 to trans-10 pathway of biohydrogenation (BH) can occur in the rumen of cows receiving high-concentrate diets, especially when the diet is supplemented with unsaturated fat sources. To study this shift, 4 rumen-fistulated nonlactating Holstein cows were assigned to a 4×4 Latin square design with 4 different diets during 4 periods. Cows received 12 kg of dry matter per day of 4 diets based on corn silage during 4 successive periods: a control diet (22% starch, <3% crude fat on DM basis), a high-starch diet supplemented with wheat plus barley (35% starch, <3% crude fat), a sunflower oil diet supplemented with 5% of sunflower oil (20% starch, 7.6% crude fat), and a high-starch plus sunflower oil diet (33% starch, 7.3% crude fat). Five hours after feeding, proportions of trans-11 BH isomers greatly increased in the rumen content with the addition of sunflower oil, without change in ruminal pH compared with the control diet. Addition of starch to the control diet had no effect on BH pathways but decreased ruminal pH. The addition of a large amount of starch in association with sunflower oil increased trans-10 FA at the expense of trans-11 FA in the rumen content, revealing a trans-11 to trans-10 shift. Interestingly, with this latter diet, ruminal pH did not change compared with a single addition of starch. This trans-11 to trans-10 shift occurred progressively, after a decrease in the proportion of trans-11 FA in the rumen, suggesting that this shift could result from a dysbiosis in the rumen in favor of trans-10-producing bacteria at the expense of those producing trans-11 or a modification of bacterial activities.

  20. Potlining Additives

    SciTech Connect

    Rudolf Keller

    2004-08-10

    In this project, a concept to improve the performance of aluminum production cells by introducing potlining additives was examined and tested. Boron oxide was added to cathode blocks, and titanium was dissolved in the metal pool; this resulted in the formation of titanium diboride and caused the molten aluminum to wet the carbonaceous cathode surface. Such wetting reportedly leads to operational improvements and extended cell life. In addition, boron oxide suppresses cyanide formation. This final report presents and discusses the results of this project. Substantial economic benefits for the practical implementation of the technology are projected, especially for modern cells with graphitized blocks. For example, with an energy savings of about 5% and an increase in pot life from 1500 to 2500 days, a cost savings of $ 0.023 per pound of aluminum produced is projected for a 200 kA pot.

  1. Cosmic-Ray Spectrum Approximation Model: Experimental Results and Comparison with Other Models

    NASA Astrophysics Data System (ADS)

    Buchvarova, M.; Draganov, D.

    2013-06-01

    We discuss a model which parameterizes the cosmic-ray (CR) spectrum at different physical conditions, which include the most important effects controlling the CR intensity, like convection-diffusion and energy losses. By a suitable choice of parameters the proposed model results in two approximations: one close to a "force-field" model (describing the energy losses of CRs in the inner heliosphere) and a "convection-diffusion" equation (giving the reduction of CR intensity in the outer heliosphere). The BESS ( Balloon-borne Experiment with Superconducting Spectrometer) experimental spectra of galactic protons and helium nuclei are fitted by the model spectra. The calculation of the unknown parameters is performed using a constrained least squares method as an alternative to the standard chi-square minimization method, because the data contain not only random errors, but also systematic ones. The CR spectrum approximation (CRSA) model is compared to the Moscow State University (MSU) model and the Badhwar and O'Neill (Badhwar and O'Neill, Adv. Space. Res. 14, 749, 1994; Adv. Space Res. 17, 7, 1994) model; we show that depending on the choice of the model parameters it can be examined in the context of one of these two models. We derive a relation between the parameters of the CRSA and MSU models for rigidities above about 10 GV (drift effects are ignored) during periods of low to approximately average levels of solar activity. The drawbacks of the proposed approximation are that: i) the model parameters do not depend on rigidity and ii) the model does not take into account general trends in the variations of the heliospheric magnetic field; thus, the influence of the drift effects on the shape of the spectral curves for different magnetic field polarity swings is ignored.

  2. Modeling Results for Proposed NSTX 28 GHz and EBWH System

    SciTech Connect

    Taylor, G; Ellis, R A; Fredd, E; Greenough, N; Hosea, J C; Wilgen, J B; Harvey, R W; Smirnov, A P; Preinhaelter, J; Urban, J; Ram, A K

    2008-03-20

    A 28 GHz electron cyclotron heating (ECH) and electron Bernstein wave heating (EBWH) system has been proposed for installation on the National Spherical Torus Experiment (NSTX). A 350 kW gyrotron connected to a fixed horn antenna is proposed for ECH-assisted solenoid-free plasma startup. Modeling predicts strong first pass on-axis EC absorption, even for low electron temperature, Te ~ 20 eV, Coaxial Helicity Injection (CHI) startup plasmas. ECH will heat the CHI plasma to Te ~ 300 eV, providing a suitable target plasma for 30 MHz high-harmonic fast wave heating. A second gyrotron and steered O-X-B mirror launcher is proposed for EBWH experiments. Radiometric measurements of thermal EBW emission detected via B-X-O coupling on NSTX support implementation of the proposed system. 80% B-X-O coupling efficiency was measured in L-mode plasmas and 60% B-X-O coupling efficiency was recently measured in H-mode plasmas conditioned with evaporated lithium. Modeling predicts local on-axis EBW heating and current drive using 28 GHz power in β ~ 20% NSTX plasmas should be possible, with current drive efficiencies ~ 40 kA/MW.

  3. First results on modeling of ITER infrared images

    NASA Astrophysics Data System (ADS)

    Kočan, M.; Reichle, R.; Aumeunier, M.-H.; Gunn, J. P.; Kajita, S.; Le Guern, F.; Lisgo, S. W.; Loarer, T.; Kukushkin, A. S.; Sashala Naik, A.; Rigollet, F.; Stratton, B.

    2016-02-01

    Infrared (IR) images of the ITER wide angle viewing system are modeled for the baseline plasma equilibrium and partially detached tungsten divertor, taking into account the three-dimensional structure of the first wall and the divertor. The modeling includes a comprehensive chain of calculations from the heat load specifications up to the synthetic, reflection-free IR images of the surface temperature, T surf. The effect of the optical blur due to finite IR detector size and diffraction/aberrations—approximated by a Gaussian filter—on the measured T surf is investigated. The optical blur characterized by σ = 0.7 pixel (approximately twice the diffraction limit) leads to underestimation of T surf,max on the inner vertical divertor target and near the upper X-point by <6% and <4%, respectively. This is within the required measurement accuracy of 10%. Larger underestimation of T surf,max (<12%) is observed on the outer vertical divertor target. The study demonstrates the importance of keeping the performance of the optical system as close as possible to the diffraction limit.

  4. Preliminary Model Results of Beach Profile Dynamics with Stratigraphy

    NASA Astrophysics Data System (ADS)

    Reniers, A. J.; Koktas, M.; Gallagher, E. L.; Wadman, H. M.; Brodie, K. L.; Johnson, B. D.; McNinch, J.

    2014-12-01

    The presence of spatial variation in grain size within the surf and swash zone is often ignored in numerical modeling whereas Upon closer inspection, a broad range of grain sizes is visible on a beach. This could potentially lead to a significant mismatch between predictions and observations of profile evolution given the strong sensitivity of sediment transport formulae to the grain size. To explore this in more detail, numerical simulations with XBeach have been performed to simulate the observations of changes in beach profile and stratigraphy within the swash zone at Duck, NC, under a range of wave and tidal conditions (see presentations by Wadman et al., and Gallagher et al. for complementary information on the observations at this conference). The research focus is to establish the morphodynamic response to the sediment dynamics at short and longer time scales in the presence of stratigraphy. A better understanding of the mechanisms and subsequently improved modeling will provide more accurate predictions of the morphodynamic response of the beach during moderate and extreme conditions. It will also help in the interpretation of sediment layering of the beach to relate to past extreme storms on geological time scales.

  5. Modeling of rock friction 1. Experimental results and constitutive equations

    USGS Publications Warehouse

    Dieterich, J.H.

    1979-01-01

    Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of ??6 MPa demonstrate that competing time, displacement, and velocity effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip is also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability. Copyright ?? 1979 by the American Geophysical Union.

  6. Effects of Rhenium Addition on the Temporal Evolution of the Nanostructure and Chemistry of a Model Ni-Cr-Al Superalloy. 2; Analysis of the Coarsening Behavior

    NASA Technical Reports Server (NTRS)

    Yoon, Kevin E.; Noebe, Ronald D.; Seidman, David N.

    2007-01-01

    The temporal evolution of the nanostructure and chemistry of a model Ni-8.5 at.% Cr-10 at.% Al alloy with the addition of 2 at.% Re was studied using transmission electron microscopy and atom-probe tomography in order to measure the number density and mean radius of the y' (LIZ) precipitates and the chemistry of the y'-precipitates and the y (fcc)-matrix. In this article, the coarsening behavior of the y'-precipitates is discussed in detail and compared with the Umantsev-Olson model for multi-component alloys. In addition, the experimental results are evaluated with PrecipiCalc(TradeMark) simulations. The results show that the diffusivities of the solute elements play a major role in the coarsening behavior of the y'-precipitates and that the addition of Re retards the coarsening kinetics and stabilizes the spheroidal morphology of the precipitates by reducing the interfacial energy.

  7. Reporting Results from Structural Equation Modeling Analyses in Archives of Scientific Psychology.

    PubMed

    Hoyle, Rick H; Isherwood, Jennifer C

    2013-02-01

    Psychological research typically involves the analysis of data (e.g., questionnaire responses, records of behavior) using statistical methods. The description of how those methods are used and the results they produce is a key component of scholarly publications. Despite their importance, these descriptions are not always complete and clear. In order to ensure the completeness and clarity of these descriptions, the Archives of Scientific Psychology requires that authors of manuscripts to be considered for publication adhere to a set of publication standards. Although the current standards cover most of the statistical methods commonly used in psychological research, they do not cover them all. In this manuscript, we propose adjustments to the current standards and the addition of additional standards for a statistical method not adequately covered in the current standards-structural equation modeling (SEM). Adherence to the standards we propose would ensure that scholarly publications that report results of data analyzed using SEM are complete and clear.

  8. Validation of NDVI/LAI Empirical Model to Force a Pasture Growth Model: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Alexandre, C.; Lajoie, G.; Tillard, E.; Salgado, P.

    2016-08-01

    Estimating forage biomass is nowadays essential for a good farm management. To answer to this problem we can use mathematic models that use meteorological, soil, grass data. However, in specifics territories as Reunion Island, they are not efficient. That is why we want to force this kind of model to improve the biomass prediction. The Leaf Area Index (LAI) is one parameter used in growth models. Estimate this parameter from satellite images could a solution to predict better the forage biomass. Preliminary results show a strong relation between LAI and NDVI (Normalized Vegetation Index).

  9. Recent Additions in the Modeling Capabilities of an Open-Source Wave Energy Converter Design Tool: Preprint

    SciTech Connect

    Tom, N.; Lawson, M.; Yu, Y. H.

    2015-04-20

    WEC-Sim is a midfidelity numerical tool for modeling wave energy conversion devices. The code uses the MATLAB SimMechanics package to solve multibody dynamics and models wave interactions using hydrodynamic coefficients derived from frequency-domain boundary-element methods. This paper presents the new modeling features introduced in the latest release of WEC-Sim. The first feature discussed conversion of the fluid memory kernel to a state-space form. This enhancement offers a substantial computational benefit after the hydrodynamic body-to-body coefficients are introduced and the number of interactions increases exponentially with each additional body. Additional features include the ability to calculate the wave-excitation forces based on the instantaneous incident wave angle, allowing the device to weathervane, as well as import a user-defined wave elevation time series. A review of the hydrodynamic theory for each feature is provided and the successful implementation is verified using test cases.

  10. Experimental results and modeling of a dynamic hohlraum on SATURN

    SciTech Connect

    Derzon, M.S.; Allshouse, G.O.; Deeney, C.; Leeper, R.J.; Nash, T.J.; Matuska, W.; Peterson, D.L.; MacFarlane, J.J.; Ryutov, D.D.

    1998-06-01

    Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--135 eV Planckian before the target shock heated, or stagnated, on-axis. Peak pinch radiation temperatures of nominally 160 eV were obtained. Measured early time x-ray emission histories and temperature estimates agree well with modeled performance in the 200--280 eV band using a 2D radiation magneto-hydrodynamics code. However, significant differences are observed in comparisons of the x-ray images and 2D simulations.

  11. Ares I Scale Model Acoustic Test Overpressure Results

    NASA Technical Reports Server (NTRS)

    Casiano, M. J.; Alvord, D. A.; McDaniels, D. M.

    2011-01-01

    A summary of the overpressure environment from the 5% Ares I Scale Model Acoustic Test (ASMAT) and the implications to the full-scale Ares I are presented in this Technical Memorandum. These include the scaled environment that would be used for assessing the full-scale Ares I configuration, observations, and team recommendations. The ignition transient is first characterized and described, the overpressure suppression system configuration is then examined, and the final environment characteristics are detailed. The recommendation for Ares I is to keep the space shuttle heritage ignition overpressure (IOP) suppression system (below-deck IOP water in the launch mount and mobile launcher and also the crest water on the main flame deflector) and the water bags.

  12. SHADOZ (Southern Hemisphere ADditional OZonesondes): An Ozonesonde Network for Satellite Validation, Climatology and Modeling

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, Jacquelyn C.; Schmidlin, Francis J.; Oltmans, Samuel J.; McPeters, Richard D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    In the past 5 years, new tropical ozone data products have been developed from TOMS and other satellites, During this period, global chemical-transport models have been used for ozone assessment studies. However, there has been a lack of independent ozone profiles in the tropics for evaluation of the data sets and models. In 1998, NASA's Goddard Space Flight Center, Wallops Flight Facility and NOAA's CMDL (Climate Monitoring and Diagnostics Lab), began a 2-year project to collect a consistent data set by augmenting ozonesonde launches at southern hemisphere tropical sites The measurements are available to the scientific community at a single electronic location - the SHADOZ website at NASA/Goddard: http://code9l6.gsfc.nasa.gov/Data services/Shadoz/shadoz hmpg2.html. Stations in SHADOZ include four islands in the Pacific: Fiji, Tahiti, San Cristobal (Galapagos) and American Samoa. Two sites are at and in the Atlantic: Natal (Brazil) and Ascension Island. Three other sites span Africa (Nairobi and Irene, South Africa) and the Indian Ocean (Reunion Island and Watukosek in Java, Indonesia). All SHADOZ sites are using ECC-type sondes, with the conversion from JMD sondes at Java in 1999, but there are variations in sonde preparation technique and data processing. During the 1998-1999 period, more than 550 sondes were incorporated into the SHADOZ data base. Examples from these measurements illustrate the tropical wave-one pattern in total ozone which is easily detectable by satellite. They also show that the wave-one pattern appears to be in the troposphere, as assumed in creating the modified-residual tropospheric ozone data product from TOMS. SHADOZ will add data from intensive field campaigns from time to time. Recent contributions to the SHADOZ archive are from the INDOEX (Indian Ocean Experiment January-March 1999)sondes at the Maldives (5N, 73E) and 27 sondes on the US NOAA oceanographic vessel, the FIN Ronald H Brown between Virginia (US) and Mauritius via Cape

  13. Circulation and effluent dilution modeling in Massachusetts Bay : model implementation, verification and results

    USGS Publications Warehouse

    Signell, Richard P.; Jenter, Harry L.; Blumberg, Alan F.

    1996-01-01

    A three-dimensional hydrodynamic model was developed as part of a cooperative U.S. Geological Survey/Massachusetts Water Resources Authority program to study contaminated sediment accumulation and transport in Massachusetts Bay. This report details the development of the model and assesses how well the model represents observed currents and water properties in the bay. It also summarizes circulation and comparative effluent dilution simulations from existing and future Boston sewage outfalls over a three-year period from October 1, 1989 to December 31, 1992. The ECOM-si model, a semi-implicit version of the Blumberg and Mellor (1987) Estuarine, Coastal and Ocean Model, is shown to reproduce many of the important hydrodynamical features of Massachusetts Bay: the seasonal evolution of the pycnocline, the mean flow pattern, and the strength of sub-tidal current fluctuations. Throughout the simulation period, during both vertically well-mixed and stratified conditions, the seasonal statistics of observed currents are well-represented by the model. The model is therefore appropriate for studying the average dilution of sewage effluent and other continuously discharged substances over seasonal time scales. The ability of the model to reproduce individual flow events varies with season and location within the bay. Flow events during unstratified conditions in western Massachusetts Bay are particularly well-represented, indicating that the model is appropriate for studying processes such as the transport of suspended material from the future outfall site due to winter storms. Individual flow events during stratified conditions and in the offshore Stellwagen Bank region, however, are less well-represented due to small length scales (caused by upwelling and river discharge events) coupled with insufficient data to specify open boundary forcing from the Gulf of Maine. Thus while the model might be used to answer issues such as the frequency with which Gulf of Maine river

  14. Sensitivity of steamflood model results to grid and timestep sizes

    SciTech Connect

    Abou-Kassem, J.H.; Aziz, K.

    1984-02-01

    Numerical simulation of complex processes in oil reservoirs has become a standard tool. The grid size and timestep sensitivity of a simulator are of prime concern in reaching the correct conclusions in any study. This paper presents an analysis of the sensitivity to timestep and grid size of a one-dimensional (1D) and twodimensional (2D) compositional multiphase steamflood model used to simulate a heavy-oil reservoir. The behavior of primary variables before breakthrough in the 1D and 2D cases is presented for clearer understanding of steamflooding heavy-oil reservoirs. The peculiar features exhibited by primary variables of the production and injection blocks for the 1D reservoir plus timestep and grid-size effects on primary variables for 2D cases studied are discussed. Sensitivity studies of grid and timestep size are meaningful only if each is carried out while the other variable has minimum truncation error. The recovery performance parameters are less sensitive to timestep size than to grid size. They are also less sensitive in the 2D runs than in the 1D runs. The time/pore-volume-injected (PVI) relationship is very sensitive to grid size, and to a lesser extent, to timestep size.

  15. Analysis of the Diversity of Substrate Utilisation of Soil Bacteria Exposed to Cd and Earthworm Activity Using Generalised Additive Models

    PubMed Central

    Muñiz, Selene; Lacarta, Juan; Pata, María P.; Jiménez, Juan José; Navarro, Enrique

    2014-01-01

    Biolog EcoPlates™ can be used to measure the carbon substrate utilisation patterns of microbial communities. This method results in a community-level physiological profile (CLPP), which yields a very large amount of data that may be difficult to interpret. In this work, we explore a combination of statistical techniques (particularly the use of generalised additive models [GAMs]) to improve the exploitation of CLPP data. The strength of GAMs lies in their ability to address highly non-linear relationships between the response and the set of explanatory variables. We studied the impact of earthworms (Aporrectodea caliginosa Savigny 1826) and cadmium (Cd) on the CLPP of soil bacteria. The results indicated that both Cd and earthworms modified the CLPP. GAMs were used to assess time-course changes in the diversity of substrate utilisation (DSU) using the Shannon-Wiener index. GAMs revealed significant differences for all treatments (compared to control -S-). The Cd exposed microbial community presented very high metabolic capacities on a few substrata, resulting in an initial acute decrease of DSU (i.e. intense utilization of a few carbon substrata). After 54 h, and over the next 43 h the increase of the DSU suggest that other taxa, less dominant, reached high numbers in the wells containing sources that are less suitable for the Cd-tolerant taxa. Earthworms were a much more determining factor in explaining time course changes in DSU than Cd. Accordingly, Ew and EwCd soils presented similar trends, regardless the presence of Cd. Moreover, both treatments presented similar number of bacteria and higher than Cd-treated soils. This experimental approach, based on the use of DSU and GAMs allowed for a global and statistically relevant interpretation of the changes in carbon source utilisation, highlighting the key role of earthworms on the protection of microbial communities against the Cd. PMID:24416339

  16. Analysis of the diversity of substrate utilisation of soil bacteria exposed to Cd and earthworm activity using generalised additive models.

    PubMed

    Muñiz, Selene; Lacarta, Juan; Pata, María P; Jiménez, Juan José; Navarro, Enrique

    2014-01-01

    Biolog EcoPlates™ can be used to measure the carbon substrate utilisation patterns of microbial communities. This method results in a community-level physiological profile (CLPP), which yields a very large amount of data that may be difficult to interpret. In this work, we explore a combination of statistical techniques (particularly the use of generalised additive models [GAMs]) to improve the exploitation of CLPP data. The strength of GAMs lies in their ability to address highly non-linear relationships between the response and the set of explanatory variables. We studied the impact of earthworms (Aporrectodea caliginosa Savigny 1826) and cadmium (Cd) on the CLPP of soil bacteria. The results indicated that both Cd and earthworms modified the CLPP. GAMs were used to assess time-course changes in the diversity of substrate utilisation (DSU) using the Shannon-Wiener index. GAMs revealed significant differences for all treatments (compared to control -S-). The Cd exposed microbial community presented very high metabolic capacities on a few substrata, resulting in an initial acute decrease of DSU (i.e. intense utilization of a few carbon substrata). After 54 h, and over the next 43 h the increase of the DSU suggest that other taxa, less dominant, reached high numbers in the wells containing sources that are less suitable for the Cd-tolerant taxa. Earthworms were a much more determining factor in explaining time course changes in DSU than Cd. Accordingly, Ew and EwCd soils presented similar trends, regardless the presence of Cd. Moreover, both treatments presented similar number of bacteria and higher than Cd-treated soils. This experimental approach, based on the use of DSU and GAMs allowed for a global and statistically relevant interpretation of the changes in carbon source utilisation, highlighting the key role of earthworms on the protection of microbial communities against the Cd.

  17. Thermal aging of traditional and additively manufactured foams: analysis by time-temperature-superposition, constitutive, and finite-element models

    SciTech Connect

    Maiti, A.; Weisgraber, T. H.; Small, W.; Lewicki, J. P.; Duoss, E. B.; Spadaccini, C. M.; Pearson, M. A.; Chinn, S. C.; Wilson, T. S.; Maxwell, R. S.

    2016-12-08

    Cellular solids or foams are a very important class of materials with diverse applications ranging from thermal insulation and shock absorbing support cushions, to light-weight structural and floatation components, and constitute crucial components in a large number of industries including automotive, aerospace, electronics, marine, biomedical, packaging, and defense. In many of these applications the foam material is subjected to long periods of continuous stress, which can, over time, lead to a permanent change in structure and a degradation in performance. In this report we summarize our modeling efforts to date on polysiloxane foam materials that form an important component in our systems. Aging of the materials was characterized by two measured quantities, i.e., compression set and load retention. Results of accelerated aging experiments were analyzed by an automated time-temperaturesuperposition (TTS) approach, which creates a master curve that can be used for long-term predictions (over decades) under ambient conditions. When comparing such master curves for traditional (stochastic) foams with those for recently 3D-printed (i.e., additively manufactured, or AM) foams, it became clear that AM foams have superior aging behavior. To gain deeper understanding, we imaged the microstructure of both foams using X-ray computed tomography, and performed finite-element analysis of the mechanical response within these microstructures. This indicates a wider stress variation in the stochastic foam with points of more extreme local stress as compared to the 3D printed material.

  18. An Alkaline Protease from Bacillus pumilus MP 27: Functional Analysis of Its Binding Model toward Its Applications As Detergent Additive

    PubMed Central

    Baweja, Mehak; Tiwari, Rameshwar; Singh, Puneet K.; Nain, Lata; Shukla, Pratyoosh

    2016-01-01

    A proteolytic strain of Bacillus pumilus MP 27 was isolated from water samples of Southern ocean produced alkaline protease. Since protease production need expensive ingredients, an economically viable process was developed by using low cost carbon source, wheat straw, supplemented with peptone. This protease was active within temperature ranges 10–70°C at pH 9. This process was optimized by response surface methodology using a Box Bekhman design by Design Expert 7.0 software that increased the protease activity to 776.5 U/ml. Moreover, the enzyme was extremely stable at a broad range of temperature and pH retaining 69% of its activity at 50°C and 70% at pH 11. The enzyme exhibited excellent compatibility with surfactants and commercial detergents, showing 87% stability with triton X-100 and 100% stability with Tide commercial detergent. The results of the wash performance analysis demonstrated considerably good de-staining at 50 and 4°C with low supplementation (109 U/ml). Molecular modeling of the protease revealed the presence of serine proteases, subtilase family and serine active site and further docking supported the association of catalytic site with the various substrates. Certainly, such protease can be considered as a good detergent additive in detergent industry with a possibility to remove the stains effectively even in a cold wash. PMID:27536284

  19. Prediction of vertical PM2.5 concentrations alongside an elevated expressway by using the neural network hybrid model and generalized additive model

    NASA Astrophysics Data System (ADS)

    Gao, Ya; Wang, Zhanyong; Lu, Qing-Chang; Liu, Chao; Peng, Zhong-Ren; Yu, Yue

    2016-10-01

    A study on vertical variation of PM2.5 concentrations was carried out in this paper. Field measurements were conducted at eight different floor heights outside a building alongside a typical elevated expressway in downtown Shanghai, China. Results show that PM2.5 concentration decreases significantly with the increase of height from the 3rd to 7th floor or the 8th to 15th floor, and increases suddenly from the 7th to 8th floor which is the same height as the elevated expressway. A non-parametric test indicates that the data of PM2.5 concentration is statistically different under the 7th floor and above the 8th floor at the 5% significance level. To investigate the relationships between PM2.5 concentration and influencing factors, the Pearson correlation analysis was performed and the results indicate that both traffic and meteorological factors have crucial impacts on the variation of PM2.5 concentration, but there is a rather large variation in correlation coefficients under the 7th floor and above the 8th floor. Furthermore, the back propagation neural network based on principal component analysis (PCA-BPNN), as well as generalized additive model (GAM), was applied to predict the vertical PM2.5 concentration and examined with the field measurement dataset. Experimental results indicated that both models can obtain accurate predictions, while PCA-BPNN model provides more reliable and accurate predictions as it can reduce the complexity and eliminate data co-linearity. These findings reveal the vertical distribution of PM2.5 concentration and the potential of the proposed model to be applicable to predict the vertical trends of air pollution in similar situations.

  20. A general model of metal underpotential deposition in the presence of thiol-based additives based on an in situ STM study.

    PubMed

    Yanson, Yuriy; Frenken, Joost W M; Rost, Marcel J

    2011-09-21

    Bis(3-sulfopropyl)disulfide (SPS) is a common additive in commercial copper electroplating baths. We have studied the influence of SPS on Cu underpotential deposition (UPD) on a Au(111) single crystal surface by means of cyclic voltammetry (CV) and electrochemical scanning tunneling microscopy (EC-STM). By combining our results with the results from the literature we propose a model that describes different stages of Cu UPD in the presence of SPS. Further analysis shows that our model is also applicable to a more general case of UPD of different metals, e.g. Cu and Ag, on a thiol-modified single-crystal surface, where the bond between the substrate and the thiol is adatom mediated. In addition, we have verified our model by in situ observation of the lifting of the Herringbone reconstruction on the Au(111) surface by Cu UPD.

  1. Thermochemical properties, rotation barriers, and group additivity for unsaturated oxygenated hydrocarbons and radicals resulting from reaction of vinyl and phenyl radical systems with O2.

    PubMed

    Sebbarand, Nadia; Bockhorn, Henning; Bozzelli, Joseph W

    2005-03-17

    Oxidation of unsaturated and aromatic hydrocarbons in atmospheric and combustion processes results in formation of linear and cyclic unsaturated, oxygenated-hydrocarbon intermediates. The thermochemical parameters delatafH degrees 298, S degrees 298, and C(p)(f298)(T) for these intermediates are needed to understand their stability and reaction paths in further oxidation. These properties are not available for a majority of these unsaturated oxy-hydrocarbons and their corresponding radicals, even via group additivity methods. Enthalpy, entropy, and heat capacity of a series of 40 oxygenated and non-oxygenated molecules, or radicals corresponding to hydrogen atom loss from the parent stable molecules are determined in this study. Enthalpy (delatafH degrees 298 in kcal mol(-1)) is derived from the density function calculations at the B3LYP/6-311g(d,p) calculated enthalpy of reaction (delatafH degrees rxn,298) and by use of isodesmic (work) reactions. Estimation of error in enthalpy delatafH degrees 298, from use of computational chemistry coupled with work reactions analysis, is presented using comparisons between the calculated and literature enthalpies of reaction. Entropies (S degrees 298) and heat capacities (C(p)(f298)(T)) were calculated using the B3LYP/6-311G(d,p) determined frequencies and geometries. Potential barriers for internal rotors in each molecule were determined and used (in place of torsion frequencies) to calculate contributions to S and C(p)(T) from the hindered rotors. Twenty-six groups for use in group additivity (GA) are also developed.

  2. Constraining performance assessment models with tracer test results: a comparison between two conceptual models

    NASA Astrophysics Data System (ADS)

    McKenna, Sean A.; Selroos, Jan-Olof

    Tracer tests are conducted to ascertain solute transport parameters of a single rock feature over a 5-m transport pathway. Two different conceptualizations of double-porosity solute transport provide estimates of the tracer breakthrough curves. One of the conceptualizations (single-rate) employs a single effective diffusion coefficient in a matrix with infinite penetration depth. However, the tracer retention between different flow paths can vary as the ratio of flow-wetted surface to flow rate differs between the path lines. The other conceptualization (multirate) employs a continuous distribution of multiple diffusion rate coefficients in a matrix with variable, yet finite, capacity. Application of these two models with the parameters estimated on the tracer test breakthrough curves produces transport results that differ by orders of magnitude in peak concentration and time to peak concentration at the performance assessment (PA) time and length scales (100,000 years and 1,000 m). These differences are examined by calculating the time limits for the diffusive capacity to act as an infinite medium. These limits are compared across both conceptual models and also against characteristic times for diffusion at both the tracer test and PA scales. Additionally, the differences between the models are examined by re-estimating parameters for the multirate model from the traditional double-porosity model results at the PA scale. Results indicate that for each model the amount of the diffusive capacity that acts as an infinite medium over the specified time scale explains the differences between the model results and that tracer tests alone cannot provide reliable estimates of transport parameters for the PA scale. Results of Monte Carlo runs of the transport models with varying travel times and path lengths show consistent results between models and suggest that the variation in flow-wetted surface to flow rate along path lines is insignificant relative to variability in

  3. Hydrogen-burn survival: preliminary thermal model and test results

    SciTech Connect

    McCulloch, W.H.; Ratzel, A.C.; Kempka, S.N.; Furgal, D.T.; Aragon, J.J.

    1982-08-01

    This report documents preliminary Hydrogen Burn Survival (HBS) Program experimental and analytical work conducted through February 1982. The effects of hydrogen deflagrations on safety-related equipment in nuclear power plant containment buildings are considered. Preliminary results from hydrogen deflagration experiments in the Sandia Variable Geometry Experimental System (VGES) are presented and analytical predictions for these tests are compared and discussed. Analytical estimates of component thermal responses to hydrogen deflagrations in the upper and lower compartments of an ice condenser, pressurized water reactor are also presented.

  4. High-energy radiation damage in zirconia: Modeling results

    SciTech Connect

    Zarkadoula, E.; Devanathan, R.; Weber, W. J.; Seaton, M. A.; Todorov, I. T.; Nordlund, K.; Dove, M. T.; Trachenko, K.

    2014-02-28

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1–0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  5. High-energy radiation damage in zirconia: modeling results

    SciTech Connect

    Zarkadoula, Evangelia; Devanathan, Ram; Weber, William J; Seaton, M; Todorov, I T; Nordlund, Kai; Dove, Martin T; Trachenko, Kostya

    2014-01-01

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with account of electronic energy losses. We nd that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  6. High-energy radiation damage in zirconia: modeling results

    SciTech Connect

    Zarkadoula, Eva; Devanathan, Ram; Weber, William J.; Seaton, Michael; Todorov, Ilian; Nordlund, Kai; Dove, Martin T.; Trachenko, Kostya

    2014-02-28

    Zirconia has been viewed as a material of exceptional resistance to amorphization by radiation damage, and was consequently proposed as a candidate to immobilize nuclear waste and serve as a nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with the account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely disjoint from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  7. High-energy radiation damage in zirconia: Modeling results

    NASA Astrophysics Data System (ADS)

    Zarkadoula, E.; Devanathan, R.; Weber, W. J.; Seaton, M. A.; Todorov, I. T.; Nordlund, K.; Dove, M. T.; Trachenko, K.

    2014-02-01

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  8. Probabilistic dose-response modeling: case study using dichloromethane PBPK model results.

    PubMed

    Marino, Dale J; Starr, Thomas B

    2007-12-01

    A revised assessment of dichloromethane (DCM) has recently been reported that examines the influence of human genetic polymorphisms on cancer risks using deterministic PBPK and dose-response modeling in the mouse combined with probabilistic PBPK modeling in humans. This assessment utilized Bayesian techniques to optimize kinetic variables in mice and humans with mean values from posterior distributions used in the deterministic modeling in the mouse. To supplement this research, a case study was undertaken to examine the potential impact of probabilistic rather than deterministic PBPK and dose-response modeling in mice on subsequent unit risk factor (URF) determinations. Four separate PBPK cases were examined based on the exposure regimen of the NTP DCM bioassay. These were (a) Same Mouse (single draw of all PBPK inputs for both treatment groups); (b) Correlated BW-Same Inputs (single draw of all PBPK inputs for both treatment groups except for bodyweights (BWs), which were entered as correlated variables); (c) Correlated BW-Different Inputs (separate draws of all PBPK inputs for both treatment groups except that BWs were entered as correlated variables); and (d) Different Mouse (separate draws of all PBPK inputs for both treatment groups). Monte Carlo PBPK inputs reflect posterior distributions from Bayesian calibration in the mouse that had been previously reported. A minimum of 12,500 PBPK iterations were undertaken, in which dose metrics, i.e., mg DCM metabolized by the GST pathway/L tissue/day for lung and liver were determined. For dose-response modeling, these metrics were combined with NTP tumor incidence data that were randomly selected from binomial distributions. Resultant potency factors (0.1/ED(10)) were coupled with probabilistic PBPK modeling in humans that incorporated genetic polymorphisms to derive URFs. Results show that there was relatively little difference, i.e., <10% in central tendency and upper percentile URFs, regardless of the case

  9. Meta-analysis of high-latitude nitrogen-addition and warming studies implies ecological mechanisms overlooked by land models

    NASA Astrophysics Data System (ADS)

    Bouskill, N. J.; Riley, W. J.; Tang, J. Y.

    2014-12-01

    Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowground respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model-observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.

  10. Integrated Assessment Modeling of Carbon Sequestration and Land Use Emissions Using Detailed Model Results and Observations

    SciTech Connect

    Dr. Atul Jain

    2005-04-17

    This report outlines the progress on the development and application of Integrated Assessment Modeling of Carbon Sequestrations and Land Use Emissions supported by the DOE Office of Biological and Environmental Research (OBER), U.S. Department of Energy, Grant No. DOE-DE-FG02-01ER63069. The overall objective of this collaborative project between the University of Illinois at Urbana-Champaign (UIUC), Oak Ridge National Laboratory (ORNL), Lawrence Livermore National Laboratory (LLNL), and Pacific Northwest National Laboratory (PNNL) was to unite the latest advances in carbon cycle research with scientifically based models and policy-related integrated assessment tools that incorporate computationally efficient representations of the latest knowledge concerning science and emission trajectories, and their policy implications. As part of this research we accomplished the following tasks that we originally proposed: (1) In coordination with LLNL and ORNL, we enhanced the Integrated Science Assessment Model's (ISAM) parametric representation of the ocean and terrestrial carbon cycles that better represent spatial and seasonal variations, which are important to study the mechanisms that influence carbon sequestration in the ocean and terrestrial ecosystems; (2) Using the MiniCAM modeling capability, we revised the SRES (IPCC Special Report on Emission Scenarios; IPCC, 2000) land use emission scenarios; and (3) On the application front, the enhanced version of ISAM modeling capability is applied to understand how short- and long-term natural carbon fluxes, carbon sequestration, and human emissions contribute to the net global emissions (concentrations) trajectories required to reach various concentration (emission) targets. Under this grant, 21 research publications were produced. In addition, this grant supported a number of graduate and undergraduate students whose fundamental research was to learn a disciplinary field in climate change (e.g., ecological dynamics and

  11. Modeling results for a linear simulator of a divertor

    SciTech Connect

    Hooper, E.B.; Brown, M.D.; Byers, J.A.; Casper, T.A.; Cohen, B.I.; Cohen, R.H.; Jackson, M.C.; Kaiser, T.B.; Molvik, A.W.; Nevins, W.M.; Nilson, D.G.; Pearlstein, L.D.; Rognlien, T.D.

    1993-06-23

    A divertor simulator, IDEAL, has been proposed by S. Cohen to study the difficult power-handling requirements of the tokamak program in general and the ITER program in particular. Projections of the power density in the ITER divertor reach {approximately} 1 Gw/m{sup 2} along the magnetic fieldlines and > 10 MW/m{sup 2} on a surface inclined at a shallow angle to the fieldlines. These power densities are substantially greater than can be handled reliably on the surface, so new techniques are required to reduce the power density to a reasonable level. Although the divertor physics must be demonstrated in tokamaks, a linear device could contribute to the development because of its flexibility, the easy access to the plasma and to tested components, and long pulse operation (essentially cw). However, a decision to build a simulator requires not just the recognition of its programmatic value, but also confidence that it can meet the required parameters at an affordable cost. Accordingly, as reported here, it was decided to examine the physics of the proposed device, including kinetic effects resulting from the intense heating required to reach the plasma parameters, and to conduct an independent cost estimate. The detailed role of the simulator in a divertor program is not explored in this report.

  12. Characterization of hourly NOx atmospheric concentrations near the Venice International Airport with additive semi-parametric statistical models

    NASA Astrophysics Data System (ADS)

    Valotto, Gabrio; Varin, Cristiano

    2016-01-01

    An additive modeling approach is employed to provide a statistical description of hourly variation in concentrations of NOx measured in proximity of the Venice "Marco Polo" International Airport, Italy. Differently from several previous studies on airport emissions based on daily time series, the paper analyzes hourly data because variations of NOx concentrations during the day are informative about the prevailing emission source. The statistical analysis is carried out using a one-year time series. Confounder effects due to seasonality, meteorology and airport traffic volume are accounted for by suitable covariates. Four different model specifications of increasing complexity are considered. The model with the aircraft source expressed as the NOx emitted near the airport is found to have the best predictive quality. Although the aircraft source is statistically significant, the comparison of model-based predictions suggests that the relative impact of aircraft emissions to ambient NOx concentrations is limited and the road traffic is the likely dominant source near the sampling point.

  13. Radiative corrections to the Higgs boson couplings in the model with an additional real singlet scalar field

    NASA Astrophysics Data System (ADS)

    Kanemura, Shinya; Kikuchi, Mariko; Yagyu, Kei

    2016-06-01

    We calculate renormalized Higgs boson couplings with gauge bosons and fermions at the one-loop level in the model with an additional isospin singlet real scalar field. These coupling constants can deviate from the predictions in the standard model due to tree-level mixing effects and one-loop contributions of the extra neutral scalar boson. We investigate how they can be significant under the theoretical constraints from perturbative unitarity and vacuum stability and also the condition of avoiding the wrong vacuum. Furthermore, comparing with the predictions in the Type I two Higgs doublet model, we numerically demonstrate how the singlet extension model can be distinguished and identified by using precision measurements of the Higgs boson couplings at future collider experiments.

  14. Use of additional fission sources or scattering sources to model inward axial leakages in fast-reactor analysis

    SciTech Connect

    Grimm, K.N.; Meneghetti, D.

    1981-10-01

    When calculations of flux are done in less than three dimensions, bucklings are normally used to model leakages (flows) in the dimensions for which the flux is not calculated. If the net leakage for a given energy group is outward (positive), the buckling is positive, and buckling methods work well. However, if the new leakage for a given energy group is inward (negative), the buckling is negative and can lead to numerical instabilities (oscillations in the iterative flux calculation). This report discusses two equivalent nonbuckling methods to model inward leakages. One method (the chi/sub g/ method) models these incoming neutrons by additional fission sources. The other method (the ..sigma../sub s/(1 ..-->.. g) method) models them by increased downscatter sources. The derivation of the two methods is shown, and the flux spectra obtained by their use are compared with those obtained from two-dimensional (RZ) calculations.

  15. SU-E-J-06: Additional Imaging Guidance Dose to Patient Organs Resulting From X-Ray Tubes Used in CyberKnife Image Guidance System

    SciTech Connect

    Sullivan, A; Ding, G

    2015-06-15

    Purpose: The use of image-guided radiation therapy (IGRT) has become increasingly common, but the additional radiation exposure resulting from repeated image guidance procedures raises concerns. Although there are many studies reporting imaging dose from different image guidance devices, imaging dose for the CyberKnife Robotic Radiosurgery System is not available. This study provides estimated organ doses resulting from image guidance procedures on the CyberKnife system. Methods: Commercially available Monte Carlo software, PCXMC, was used to calculate average organ doses resulting from x-ray tubes used in the CyberKnife system. There are seven imaging protocols with kVp ranging from 60 – 120 kV and 15 mAs for treatment sites in the Cranium, Head and Neck, Thorax, and Abdomen. The output of each image protocol was measured at treatment isocenter. For each site and protocol, Adult body sizes ranging from anorexic to extremely obese were simulated since organ dose depends on patient size. Doses for all organs within the imaging field-of-view of each site were calculated for a single image acquisition from both of the orthogonal x-ray tubes. Results: Average organ doses were <1.0 mGy for every treatment site and imaging protocol. For a given organ, dose increases as kV increases or body size decreases. Higher doses are typically reported for skeletal components, such as the skull, ribs, or clavicles, than for softtissue organs. Typical organ doses due to a single exposure are estimated as 0.23 mGy to the brain, 0.29 mGy to the heart, 0.08 mGy to the kidneys, etc., depending on the imaging protocol and site. Conclusion: The organ doses vary with treatment site, imaging protocol and patient size. Although the organ dose from a single image acquisition resulting from two orthogonal beams is generally insignificant, the sum of repeated image acquisitions (>100) could reach 10–20 cGy for a typical treatment fraction.

  16. Additive effects of LPL, APOA5 and APOE variant combinations on triglyceride levels and hypertriglyceridemia: results of the ICARIA genetic sub-study

    PubMed Central

    2010-01-01

    Background Hypertriglyceridemia (HTG) is a well-established independent risk factor for cardiovascular disease and the influence of several genetic variants in genes related with triglyceride (TG) metabolism has been described, including LPL, APOA5 and APOE. The combined analysis of these polymorphisms could produce clinically meaningful complementary information. Methods A subgroup of the ICARIA study comprising 1825 Spanish subjects (80% men, mean age 36 years) was genotyped for the LPL-HindIII (rs320), S447X (rs328), D9N (rs1801177) and N291S (rs268) polymorphisms, the APOA5-S19W (rs3135506) and -1131T/C (rs662799) variants, and the APOE polymorphism (rs429358; rs7412) using PCR and restriction analysis and TaqMan assays. We used regression analyses to examine their combined effects on TG levels (with the log-transformed variable) and the association of variant combinations with TG levels and hypertriglyceridemia (TG ≥ 1.69 mmol/L), including the covariates: gender, age, waist circumference, blood glucose, blood pressure, smoking and alcohol consumption. Results We found a significant lowering effect of the LPL-HindIII and S447X polymorphisms (p < 0.0001). In addition, the D9N, N291S, S19W and -1131T/C variants and the APOE-ε4 allele were significantly associated with an independent additive TG-raising effect (p < 0.05, p < 0.01, p < 0.001, p < 0.0001 and p < 0.001, respectively). Grouping individuals according to the presence of TG-lowering or TG-raising polymorphisms showed significant differences in TG levels (p < 0.0001), with the lowest levels exhibited by carriers of two lowering variants (10.2% reduction in TG geometric mean with respect to individuals who were homozygous for the frequent alleles of all the variants), and the highest levels in carriers of raising combinations (25.1% mean TG increase). Thus, carrying two lowering variants was protective against HTG (OR = 0.62; 95% CI, 0.39-0.98; p = 0.042) and having one single raising polymorphism (OR

  17. First results from the International Urban Energy Balance Model Comparison: Model Complexity

    NASA Astrophysics Data System (ADS)

    Blackett, M.; Grimmond, S.; Best, M.

    2009-04-01

    A great variety of urban energy balance models has been developed. These vary in complexity from simple schemes that represent the city as a slab, through those which model various facets (i.e. road, walls and roof) to more complex urban forms (including street canyons with intersections) and features (such as vegetation cover and anthropogenic heat fluxes). Some schemes also incorporate detailed representations of momentum and energy fluxes distributed throughout various layers of the urban canopy layer. The models each differ in the parameters they require to describe the site and the in demands they make on computational processing power. Many of these models have been evaluated using observational datasets but to date, no controlled comparisons have been conducted. Urban surface energy balance models provide a means to predict the energy exchange processes which influence factors such as urban temperature, humidity, atmospheric stability and winds. These all need to be modelled accurately to capture features such as the urban heat island effect and to provide key information for dispersion and air quality modelling. A comparison of the various models available will assist in improving current and future models and will assist in formulating research priorities for future observational campaigns within urban areas. In this presentation we will summarise the initial results of this international urban energy balance model comparison. In particular, the relative performance of the models involved will be compared based on their degree of complexity. These results will inform us on ways in which we can improve the modelling of air quality within, and climate impacts of, global megacities. The methodology employed in conducting this comparison followed that used in PILPS (the Project for Intercomparison of Land-Surface Parameterization Schemes) which is also endorsed by the GEWEX Global Land Atmosphere System Study (GLASS) panel. In all cases, models were run

  18. Meta-analysis of high-latitude nitrogen-addition and warming studies implies ecological mechanisms overlooked by land models

    DOE PAGES

    Bouskill, N. J.; Riley, W. J.; Tang, J. Y.

    2014-12-11

    Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the climate. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the aboveground and belowground responses to warming and nitrogen addition in high-latitude ecosystems, and identified absent or poorly parameterized mechanisms in CLM4.5. While the two model versions predicted similar soil carbon stock trajectories following both warming and nitrogen addition, other predicted variables (e.g., belowgroundmore » respiration) differed from observations in both magnitude and direction, indicating that CLM4.5 has inadequate underlying mechanisms for representing high-latitude ecosystems. On the basis of observational synthesis, we attribute the model–observation differences to missing representations of microbial dynamics, aboveground and belowground coupling, and nutrient cycling, and we use the observational meta-analysis to discuss potential approaches to improving the current models. However, we also urge caution concerning the selection of data sets and experiments for meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average = 72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which precludes a rigorous evaluation of the model responses to likely nitrogen perturbations. Overall, we demonstrate that elucidating ecological mechanisms via meta-analysis can identify deficiencies in ecosystem models and empirical experiments.« less

  19. Quantitative First-Principles Kinetic Modeling of the Aza-Michael Addition to Acrylates in Polar Aprotic Solvents.

    PubMed

    Desmet, Gilles B; D'hooge, Dagmar R; Omurtag, Pinar Sinem; Espeel, Pieter; Marin, Guy B; Du Prez, Filip E; Reyniers, Marie-Françoise

    2016-12-16

    This work presents a detailed computational study and kinetic analysis of the aza-Michael addition of primary and secondary amines to acrylates in an aprotic solvent. Accurate rate coefficients for all elementary steps in the various competing mechanisms are calculated using an ONIOM-based approach in which the full system is calculated with M06-2X/6-311+G(d,p) and the core system with CBS-QB3 corrected for solvation using COSMO-RS. Diffusional contributions are taken into account using the coupled encounter pair model with diffusion coefficients calculated based on molecular dynamics simulations. The calculated thermodynamic and kinetic parameters for all forward and reverse elementary reactions are fed to a microkinetic model giving excellent agreement with experimental data obtained using GC analysis. Rate analysis reveals that for primary and secondary amines, the aza-Michael addition to ethyl acrylate occurs preferentially according to a 1,2-addition mechanism, consisting of the pseudoequilibrated formation of a zwitterion followed by a rate controlling amine assisted proton transfer toward the singly substituted product. The alternative 1,4-addition becomes competitive if substituents are present on the amine or double bond of the acrylate. Primary amines react faster than secondary amines due to increased solvation of the zwitterionic intermediate and less sterically hindered proton transfer.

  20. Mucoid Pseudomonas aeruginosa caused by mucA mutations result in activation of TLR2 in addition to TLR5 in airway epithelial cells.

    PubMed

    Beaudoin, Trevor; Lafayette, Shantelle; Nguyen, Dao; Rousseau, Simon

    2012-11-09

    The presence of the mucoid phenotype of Pseudomonas aeruginosa is a marker of poor survival in cystic fibrosis. As CF lung disease results from chronic infection leading to airway inflammation, we determined whether the switch to a mucoid phenotype by P. aeruginosa has an impact on the inflammatory response of airway epithelial cells. Exposure of airway epithelial cells to non-mucoid and mucoid P. aeruginosa-derived material leads to p38α MAPK activation, a key protein kinase involved in transmitting inflammatory signals. However, while the non-mucoid strain PAO1 activates p38α MAPK pathway solely via TLR5, the mucoid strain PACF508 activates p38α MAPK via both TLR5 and TLR2. Inactivation of mucA (the gene responsible for the mucoid phenotype) in PAO1 leads to p38α MAPK activation by both TLR2 and TLR5, as observed in the clinical mucoid isolate PACF508. Therefore, the switch to mucoid phenotype may contribute to more inflammation via TLR2 activation in addition to TLR5. Our findings highlight an important and under recognized role for TLR2 in the response of airway epithelial cells to infection.

  1. Accuracy and Precision in the Southern Hemisphere Additional Ozonesondes (SHADOZ) Dataset 1998-2000 in Light of the JOSIE-2000 Results

    NASA Technical Reports Server (NTRS)

    Witte, J. C.; Thompson, A. M.; Schmidlin, F. J.; Oltmans, S. J.; McPeters, R. D.; Smit, H. G. J.

    2003-01-01

    A network of 12 southern hemisphere tropical and subtropical stations in the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has provided over 2000 profiles of stratospheric and tropospheric ozone since 1998. Balloon-borne electrochemical concentration cell (ECC) ozonesondes are used with standard radiosondes for pressure, temperature and relative humidity measurements. The archived data are available at:http: //croc.gsfc.nasa.gov/shadoz. In Thompson et al., accuracies and imprecisions in the SHADOZ 1998- 2000 dataset were examined using ground-based instruments and the TOMS total ozone measurement (version 7) as references. Small variations in ozonesonde technique introduced possible biases from station-to-station. SHADOZ total ozone column amounts are now compared to version 8 TOMS; discrepancies between the two datasets are reduced 2\\% on average. An evaluation of ozone variations among the stations is made using the results of a series of chamber simulations of ozone launches (JOSIE-2000, Juelich Ozonesonde Intercomparison Experiment) in which a standard reference ozone instrument was employed with the various sonde techniques used in SHADOZ. A number of variations in SHADOZ ozone data are explained when differences in solution strength, data processing and instrument type (manufacturer) are taken into account.

  2. PICASSO VISION instrument design, engineering model test results, and flight model development status

    NASA Astrophysics Data System (ADS)

    Näsilä, Antti; Holmlund, Christer; Mannila, Rami; Näkki, Ismo; Ojanen, Harri J.; Akujärvi, Altti; Saari, Heikki; Fussen, Didier; Pieroux, Didier; Demoulin, Philippe

    2016-10-01

    PICASSO - A PICo-satellite for Atmospheric and Space Science Observations is an ESA project led by the Belgian Institute for Space Aeronomy, in collaboration with VTT Technical Research Centre of Finland Ltd, Clyde Space Ltd. (UK) and Centre Spatial de Liège (BE). The test campaign for the engineering model of the PICASSO VISION instrument, a miniaturized nanosatellite spectral imager, has been successfully completed. The test results look very promising. The proto-flight model of VISION has also been successfully integrated and it is waiting for the final integration to the satellite platform.

  3. How new fault data and models affect seismic hazard results? Examples from southeast Spain

    NASA Astrophysics Data System (ADS)

    Gaspar-Escribano, Jorge M.; Belén Benito, M.; Staller, Alejandra; Ruiz Barajas, Sandra; Quirós, Ligia E.

    2016-04-01

    In this work, we study the impact of different approaches to incorporate faults in a seismic hazard assessment analysis. Firstly, we consider two different methods to distribute the seismicity of the study area into faults and area-sources, based on magnitude partitioning and on moment rate distribution. We use two recurrence models to characterize fault activity: the characteristic earthquake model and the modified Gutenberg-Richter exponential frequency-magnitude distribution. An application of the work is developed in the region of Murcia (southeastern Spain), due to the availability of fault data and because is one of the areas in Spain with higher seismic hazard. The parameters used to model fault sources are derived from paleoseismological and field studies obtained from the literature and online repositories. Additionally, for some significant faults only, geodetically-derived slip rates are used to compute recurrence periods. The results of all the seismic hazard computations carried out using different models and data are represented in maps of expected peak ground accelerations for a return period of 475 years. Maps of coefficients of variation are presented to constraint the variability of the end-results to different input models and values. Additionally, the different hazard maps obtained in this study are compared with the seismic hazard maps obtained in previous work for the entire Spanish territory and more specifically for the region of Murcia. This work is developed in the context of the MERISUR project (ref. CGL2013-40492-R), with funding from the Spanish Ministry of Economy and Competitiveness.

  4. Implementing the Simple Biosphere Model (SiB) in a general circulation model: Methodologies and results

    NASA Technical Reports Server (NTRS)

    Sato, N.; Sellers, P. J.; Randall, D. A.; Schneider, E. K.; Shukla, J.; Kinter, J. L., III; Hou, Y.-T.; Albertazzi, E.

    1989-01-01

    The Simple Biosphere MOdel (SiB) of Sellers et al., (1986) was designed to simulate the interactions between the Earth's land surface and the atmosphere by treating the vegetation explicitly and relistically, thereby incorporating biophysical controls on the exchanges of radiation, momentum, sensible and latent heat between the two systems. The steps taken to implement SiB in a modified version of the National Meteorological Center's spectral GCM are described. The coupled model (SiB-GCM) was used with a conventional hydrological model (Ctl-GCM) to produce summer and winter simulations. The same GCM was used with a conventional hydrological model (Ctl-GCM) to produce comparable 'control' summer and winter variations. It was found that SiB-GCM produced a more realistic partitioning of energy at the land surface than Ctl-GCM. Generally, SiB-GCM produced more sensible heat flux and less latent heat flux over vegetated land than did Ctl-GCM and this resulted in the development of a much deeper daytime planetary boundary and reduced precipitation rates over the continents in SiB-GCM. In the summer simulation, the 200 mb jet stream and the wind speed at 850 mb were slightly weakened in the SiB-GCM relative to the Ctl-GCM results and equivalent analyses from observations.

  5. Selectivity Guidelines and a Reductive Elimination-Based Model for Predicting the Stereochemical Course of Conjugate Addition Reactions of Organocuprates to γ-Alkoxy-α,β-Enoates

    PubMed Central

    Kireev, Artem S.; Manpadi, Madhuri; Kornienko, Alexander

    2008-01-01

    Current models used to predict the stereochemical outcome of organocopper conjugate addition processes focus on the nucleophilic addition step as stereochemistry-determining. Recent kinetic, NMR, kinetic isotope effect and theoretical density functional studies strongly support the proposal that stereochemical preferences in these processes are dictated by the reductive elimination step, transforming CuIII to CuI intermediates. A new model that considers various steric and stereoelectronic factors involved in the transition state of the reductive elimination step is proposed and then used to interpret the results of systematic studies of arylcuprate conjugate addition reactions with cis and trans γ-alkoxy-α,β-enoates. The results give rise to the following selectivity guidelines for this process. To achieve high anti-addition diastereoselectivities the use of trans esters with a bulky non-alkoxy substituent at the γ-position is recommended. While stereoelectronics disfavor syn-addition, a judicious choice of properly sized γ-substituents may lead to the predominant formation of syn-products, especially with cis enoates. However, high syn-selelectivities may be achieved by using γ-amino-α,β-enoates. PMID:16555814

  6. Selectivity guidelines and a reductive elimination-based model for predicting the stereochemical course of conjugate addition reactions of organocuprates to gamma-alkoxy-alpha,beta-enoates.

    PubMed

    Kireev, Artem S; Manpadi, Madhuri; Kornienko, Alexander

    2006-03-31

    Current models used to predict the stereochemical outcome of organocopper conjugate addition processes focus on the nucleophilic addition step as stereochemistry-determining. Recent kinetic, NMR, kinetic isotope effect, and theoretical density functional studies strongly support the proposal that stereochemical preferences in these processes are dictated by the reductive elimination step, transforming Cu(III) to Cu(I) intermediates. A new model that considers various steric and stereoelectronic factors involved in the transition state of the reductive elimination step is proposed and then used to interpret the results of systematic studies of arylcuprate conjugate addition reactions with cis and trans gamma-alkoxy-alpha,beta-enoates. The results give rise to the following selectivity guidelines for this process. To achieve high anti-addition diastereoselectivities the use of trans esters with a bulky nonalkoxy substituent at the gamma-position is recommended. While stereoelectronics disfavor syn-addition, a judicious choice of properly sized gamma-substituents may lead to the predominant formation of syn-products, especially with cis enoates. However, high syn-selectivities may be achieved by using gamma-amino-alpha,beta-enoates.

  7. "Bunched Black Swans" in Complex Geosystems: Cross-Disciplinary Approaches to the Additive and Multiplicative Modelling of Correlated Extreme Bursts

    NASA Astrophysics Data System (ADS)

    Watkins, N. W.; Rypdal, M.; Lovsletten, O.

    2012-12-01

    -stationarity explicitly built in. In record breaking statistics, a record is defined in the sense used in everyday language, to be the largest value yet recorded in a time series, for example, the 2004 Sumatran Boxing Day earthquake was at the time the largest to be digitally recorded. The third group of approaches (e.g. avalanches) are explicitly spatiotemporal and so also include spatial structure. This presentation will discuss two examples of our recent work on the burst problem. We will show numerical results extending the preliminary results presented in [Watkins et al, PRE, 2009] using a standard additive model, linear fractional stable motion (LFSM). LFSM explicitly includes both heavy tails and long range dependence, allowing us to study how these 2 effects compete in determining the burst duration and size exponent probability distributions. We will contrast these simulations with new analytical studies of bursts in a multiplicative process, the multifractal random walk (MRW). We will present an analytical derivation for the scaling of the burst durations and make a preliminary comparison with data from the AE index from solar-terrestrial physics. We believe our result is more generally applicable than the MRW model, and that it applies to a broad class of multifractal processes.

  8. Effect of Various Food Additives on the Levels of 4(5)-Methylimidazole in a Soy Sauce Model System.

    PubMed

    Lee, Sumin; Lee, Jung-Bin; Hwang, Junho; Lee, Kwang-Geun

    2016-01-01

    In this study, the effect of food additives such as iron sulfate, magnesium sulfate, zinc sulfate, citric acid, gallic acid, and ascorbic acid on the reduction of 4(5)-methylimidazole (4(5)-MI) was investigated using a soy sauce model system. The concentration of 4(5)-MI in the soy sauce model system with 5% (v/v) caramel colorant III was 1404.13 μg/L. The reduction rate of 4(5)-MI level with the addition of 0.1M additives followed in order: iron sulfate (81%) > zinc sulfate (61%) > citric acid (40%) > gallic acid (38%) > ascorbic acid (24%) > magnesium sulfate (13%). Correlations between 4(5)-MI levels and the physicochemical properties of soy sauce, including the amount of caramel colorant, pH value, and color differences, were determined. The highest correlations were found between 4(5)-MI levels and the amount of caramel colorant and pH values (r(2) = 0.9712, r(2) = 0.9378). The concentration of caramel colorants in 8 commercial soy sauces were estimated, and ranged from 0.01 to 1.34% (v/v).

  9. Spatially distributed energy balance snowmelt modelling in a mountainous river basin: estimation of meteorological inputs and verification of model results

    NASA Astrophysics Data System (ADS)

    Garen, David C.; Marks, Danny

    2005-12-01

    A spatially distributed energy balance snowmelt model has been applied to a 2150 km 2 drainage basin in the Boise River, ID, USA, to simulate the accumulation and melt of the snowpack for the years 1998-2000. The simulation was run at a 3 h time step and a spatial resolution of 250 m. Spatial field time series of meteorological input data were obtained using various spatial interpolation and simulation methods. The variables include precipitation, air temperature, dew point temperature, wind speed, and solar and thermal radiation. The goal was to use readily available data and relatively straightforward, yet physically meaningful, methods to develop the spatial fields. With these meteorological fields as input, the simulated fields of snow water equivalent, snow depth, and snow covered area reproduce observations very well. The simulated snowmelt fields are also used as input to a spatially distributed hydrologic model to estimate streamflow. This gives an additional verification of the snowmelt modelling results as well as provides a linkage of the two models to generate hydrographs for water management information. This project is a demonstration of spatially distributed energy balance snowmelt modelling in a large mountainous catchment using data from existing meteorological networks. This capability then suggests the potential for developing new spatial hydrologic informational products and the possibility of improving the accuracy of the prediction of hydrologic processes for water and natural resources management.

  10. Heating stents with radio frequency energy to prevent tumor ingrowth: modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas P.; Lawes, Kate; Goldberg, S. Nahum

    1998-04-01

    Stents are often inserted into internal orifices to treat blockage due to tumor ingrowth. Stents are favored due to their minimally invasive nature, possible avoidance of a surgical procedure, and their ability to palliate surgically non-resectable disease. Because of rapid tumor growth however, a treatment means to prevent overgrowth through the stent and resultant blockage is required. To further this goal, experiments were performed in which a stent was placed in tissue and heated with radiofrequency (RF) energy to coagulate a cylinder of tissue, thereby eradicating viable tissue in the proximity of the stent. Temperatures were measured at the central stent surface and edges over time during a 5 - 10 minute heating in phantom and in fresh tissue. In addition, a finite element model was used to simulate the electric field and temperature distribution. Blood flow was also introduced in the model by evaluating RF application to stents to determine effectiveness of the energy applications. Changing perfusion and tissue electrical conductivity as a function of temperature was applied as the tissue was heated to 100 degree(s)C. Results from the electric field model will be shown as well as the thermal distribution over time from the simulations. Lastly, results from the damage integral will be discussed.

  11. Ultrafine particle concentrations in the surroundings of an urban area: comparing downwind to upwind conditions using Generalized Additive Models (GAMs).

    PubMed

    Sartini, Claudio; Zauli Sajani, Stefano; Ricciardelli, Isabella; Delgado-Saborit, Juana Mari; Scotto, Fabiana; Trentini, Arianna; Ferrari, Silvia; Poluzzi, Vanes

    2013-10-01

    The aim of this study was to investigate the influence of an urban area on ultrafine particle (UFP) concentration in nearby surrounding areas. We assessed how downwind and upwind conditions affect the UFP concentration at a site placed a few kilometres from the city border. Secondarily, we investigated the relationship among other meteorological factors, temporal variables and UFP. Data were collected for 44 days during 2008 and 2009 at a rural site placed about 3 kilometres from Bologna, in northern Italy. Measurements were performed using a spectrometer (FMPS TSI 3091). The average UFP number concentration was 11 776 (±7836) particles per cm(3). We analysed the effect of wind direction in a multivariate Generalized Additive Model (GAM) adjusted for the principal meteorological parameters and temporal trends. An increase of about 25% in UFP levels was observed when the site was downwind of the urban area, compared with the levels observed when wind blew from rural areas. The size distribution of particles was also affected by the wind direction, showing higher concentration of small size particles when the wind blew from the urban area. The GAM showed a good fit to the data (R(2) = 0.81). Model choice was via Akaike Information Criteria (AIC). The analysis also revealed that an approach based on meteorological data plus temporal trends improved the goodness of the fit of the model. In addition, the findings contribute to evidence on effects of exposure to ultrafine particles on a population living in city surroundings.

  12. Near-road modeling and measurement of cerium-containing particles generated by nanoparticle diesel fuel additive use.

    PubMed

    Gantt, Brett; Hoque, Shamia; Willis, Robert D; Fahey, Kathleen M; Delgado-Saborit, Juana Mari; Harrison, Roy M; Erdakos, Garnet B; Bhave, Prakash V; Zhang, K Max; Kovalcik, Kasey; Pye, Havala O T

    2014-09-16

    Cerium oxide nanoparticles (nCe) are used as a fuel-borne catalyst in diesel engines to reduce particulate emissions, yet the environmental and human health impacts of the exhaust particles are not well understood. To bridge the gap between emission measurements and ambient impacts, size-resolved measurements of particle composition and mass concentration have been performed in Newcastle-upon-Tyne, United Kingdom, where buses have used an nCe additive since 2005. These observations show that the noncrustal cerium fraction thought to be associated with the use of nCe has a mass concentration ∼ 0.3 ng m(-3) with a size distribution peaking at 100-320 nm in aerodynamic diameter. Simulations with a near-roadway multicomponent sectional aerosol dynamic model predict that the use of nCe additives increases the number concentration of nuclei mode particles (<50 nm in diameter) while decreasing the total mass concentration. The near-road model predicts a downwind mass size distribution of cerium-containing particles peaking at 150 nm in aerodynamic diameter, a value similar to that measured for noncrustal cerium in Newcastle. This work shows that both the emission and atmospheric transformation of cerium-containing particles needs to be taken into account by regional modelers, exposure scientists, and policymakers when determining potential environmental and human health impacts.

  13. Real-time interferometric monitoring and measuring of photopolymerization based stereolithographic additive manufacturing process: sensor model and algorithm

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Rosen, D. W.

    2017-01-01

    As additive manufacturing is poised for growth and innovations, it faces barriers of lack of in-process metrology and control to advance into wider industry applications. The exposure controlled projection lithography (ECPL) is a layerless mask-projection stereolithographic additive manufacturing process, in which parts are fabricated from photopolymers on a stationary transparent substrate. To improve the process accuracy with closed-loop control for ECPL, this paper develops an interferometric curing monitoring and measuring (ICM&M) method which addresses the sensor modeling and algorithms issues. A physical sensor model for ICM&M is derived based on interference optics utilizing the concept of instantaneous frequency. The associated calibration procedure is outlined for ICM&M measurement accuracy. To solve the sensor model, particularly in real time, an online evolutionary parameter estimation algorithm is developed adopting moving horizon exponentially weighted Fourier curve fitting and numerical integration. As a preliminary validation, simulated real-time measurement by offline analysis of a video of interferograms acquired in the ECPL process is presented. The agreement between the cured height estimated by ICM&M and that measured by microscope indicates that the measurement principle is promising as real-time metrology for global measurement and control of the ECPL process.

  14. Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

    NASA Astrophysics Data System (ADS)

    Bouskill, N. J.; Riley, W. J.; Tang, J.

    2014-08-01

    Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differed from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.

  15. Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

    DOE PAGES

    Bouskill, N. J.; Riley, W. J.; Tang, J.

    2014-08-18

    Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differedmore » from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha-1 yr-1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.« less

  16. [Decomposition of hemoglobin UV absorption spectrum into absorption spectra of prosthetic group and apoprotein by means of an additive model].

    PubMed

    Lavrinenko, I A; Vashanov, G A; Artyukhov, V G

    2015-01-01

    The decomposition pathways of hemoglobin UV absorption spectrum into the absorption spectra of the protein and non-protein components are proposed and substantiated by means of an additive model. We have established that the heme component has an absorption band with a maximum at λ(max) = 269.2 nm (ε = 97163) and the apoprotein component has an absorption band with a maximum at λ(max) = 278.4 nm (ε = 48669) for the wavelength range from 240.0 to 320.0 nm. An integral relative proportion of absorption for the heme fraction (78.8%) and apoprotein (21.2%) in the investigating wavelength range is defined.

  17. Using a logic model to evaluate the Kids Together early education inclusion program for children with disabilities and additional needs.

    PubMed

    Clapham, Kathleen; Manning, Claire; Williams, Kathryn; O'Brien, Ginger; Sutherland, Margaret

    2017-04-01

    Despite clear evidence that learning and social opportunities for children with disabilities and special needs are more effective in inclusive not segregated settings, there are few known effective inclusion programs available to children with disabilities, their families or teachers in the early years within Australia. The Kids Together program was developed to support children with disabilities/additional needs aged 0-8 years attending mainstream early learning environments. Using a key worker transdisciplinary team model, the program aligns with the individualised package approach of the National Disability Insurance Scheme (NDIS).

  18. Scalar Field Potentials in Inflationary Cosmology: General Results and Models Using Pseudo Nambu-Goldstone Bosons.

    NASA Astrophysics Data System (ADS)

    Kinney, William H.

    1996-01-01

    Inflationary cosmology is an elegant and straightforward solution to two of the largest puzzles presented by the standard "Big Bang" cosmology: why is the universe so flat, and why is the cosmic microwave background in such excellent thermal equilibrium? However, models of inflation in particle physics typically suffer from the shortcoming that the fundamental energy scale for inflation is driven to nearly the Planck scale by observational constraints. In addition, models of inflation often require the "fine-tuning" of parameters to very small values in order to remain consistent with observation. This thesis investigates inflationary potentials in a general context, and shows that the difficulty of fundamental scales being forced to the Planck scale is in fact characteristic only of scalar field potentials V(phi) dominated near their maxima by terms of order phi^2. It is found that potentials dominated by terms of order phim with m > 2 can satisfy observational constraints at an essentially arbitrary symmetry breaking scale. Potentials characterized by m = 2 and m = 4 are illustrated in the context of several "natural inflation" models, with particular emphasis on questions of fine-tuning and fundamental scale. Natural inflation theories are a class of models in which inflation is driven by a pseudo Nambu-Goldstone boson, which acquires a mass as a result of radiative corrections. Two models characterized by m = 2 are evaluated, in which the potential for inflation is generated by loop effects from a fermion sector which explicitly breaks a global U(1) symmetry. The m = 4 case is implemented in a model with a broken SO(3) symmetry, in which the potential is generated by gauge boson loops. Constraints from the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) measurement of the temperature anisotropy of the cosmic background radiation are used to limit the parameters of the models.

  19. Food additives

    PubMed Central

    Spencer, Michael

    1974-01-01

    Food additives are discussed from the food technology point of view. The reasons for their use are summarized: (1) to protect food from chemical and microbiological attack; (2) to even out seasonal supplies; (3) to improve their eating quality; (4) to improve their nutritional value. The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified. PMID:4467857

  20. Global environmental effects of impact-generated aerosols: Results from a general circulation model

    NASA Technical Reports Server (NTRS)

    Covey, C.; Ghan, S. J.; Weissman, Paul R.

    1988-01-01

    Cooling and darkening at Earth's surface are expected to result from the interception of sunlight by the high altitude worldwide dust cloud generated by impact of a large asteroid or comet, according to the one-dimensional radioactive-convective atmospheric model (RCM) of Pollack et al. An analogous three-dimensional general circulation model (GCM) simulation obtains the same basic result as the RCM but there are important differences in detail. In the GCM simulation the heat capacity of the oceans, not included in the RCM, substantially mitigates land surface cooling. On the other hand, the GCM's low heat capacity surface allows surface temperatures to drop much more rapidly than reported by Pollack et al. These two differences between RCM and GCM simulations were noted previously in studies of nuclear winter; GCM results for comet/asteroid winter, however, are much more severe than for nuclear winter because the assumed aerosol amount is large enough to intercept all sunlight falling on Earth. In the simulation the global average of land surface temperature drops to the freezing point in just 4.5 days, one-tenth the time required in the Pollack et al. simulation. In addition to the standard case of Pollack et al., which represents the collision of a 10-km diameter asteroid with Earth, additional scenarios are considered ranging from the statistically more frequent impacts of smaller asteroids to the collision of Halley's comet with Earth. In the latter case the kinetic energy of impact is extremely large due to the head-on collision resulting from Halley's retrograde orbit.

  1. Predicting tree species presence and basal area in Utah: A comparison of stochastic gradient boosting, generalized additive models, and tree-based methods

    USGS Publications Warehouse

    Moisen, G.G.; Freeman, E.A.; Blackard, J.A.; Frescino, T.S.; Zimmermann, N.E.; Edwards, T.C.

    2006-01-01

    Many efforts are underway to produce broad-scale forest attribute maps by modelling forest class and structure variables collected in forest inventories as functions of satellite-based and biophysical information. Typically, variants of classification and regression trees implemented in Rulequest's?? See5 and Cubist (for binary and continuous responses, respectively) are the tools of choice in many of these applications. These tools are widely used in large remote sensing applications, but are not easily interpretable, do not have ties with survey estimation methods, and use proprietary unpublished algorithms. Consequently, three alternative modelling techniques were compared for mapping presence and basal area of 13 species located in the mountain ranges of Utah, USA. The modelling techniques compared included the widely used See5/Cubist, generalized additive models (GAMs), and stochastic gradient boosting (SGB). Model performance was evaluated using independent test data sets. Evaluation criteria for mapping species presence included specificity, sensitivity, Kappa, and area under the curve (AUC). Evaluation criteria for the continuous basal area variables included correlation and relative mean squared error. For predicting species presence (setting thresholds to maximize Kappa), SGB had higher values for the majority of the species for specificity and Kappa, while GAMs had higher values for the majority of the species for sensitivity. In evaluating resultant AUC values, GAM and/or SGB models had significantly better results than the See5 models where significant differences could be detected between models. For nine out of 13 species, basal area prediction results for all modelling techniques were poor (correlations less than 0.5 and relative mean squared errors greater than 0.8), but SGB provided the most stable predictions in these instances. SGB and Cubist performed equally well for modelling basal area for three species with moderate prediction success

  2. Removal of strontium and transuranics from Hanford tank waste via addition of metal cations and chemical oxidant: FY 1995 test results

    SciTech Connect

    Orth, R.J.; Zacher, A.H.; Schmidt, A.J.; Elmore, M.R.; Elliott, K.R.; Neuenschwander, G.G.; Gano, S.R.

    1995-09-01

    Chelating organics and some of their degradation products in the Hanford tank waste, such as EDTA, HEDTA, and NTA act to solubilize strontium and transuranics (TRU) in the tank waste supernatant. Displacement of strontium and TRU will facilitate the removal of these radionuclides via precipitation/filtration, ion exchange, or solvent extraction so that low-level waste feed specifications can be met. Pacific Northwest Laboratory has investigated two methods for releasing organic-complexed strontium and TRU components to allow for effective pretreatment of tank waste supernatant: metal cation addition (to promote displacement and flocculation) and chemical oxidant (pennanganate) addition (to promote chelator destruction/defunctionalization and possibly flocculation). These methods, which can be conducted at near-ambient. temperatures and pressures, could be deployed as intank processes.

  3. Toward Hydrocode Models of an Impact-Generated Martian Greenhouse: Model Validation and Initial Results

    NASA Astrophysics Data System (ADS)

    Plesko, C. S.; Wohletz, K. H.; Coker, R. F.; Asphaug, E.; Korycansky, D. G.; Gittings, M. L.

    2006-12-01

    Large impacts have been suggested by Carr (1996) and Segura et al. (2002) as a possible trigger of warm and wet climate episodes early in Martian history. Our goal is to model impacts into stratigraphically complicated media, and specifically targets containing water ice in various morphologies, in order to determine a lower bound on the energy and size scales of impact events that could trigger such a climate shift, and thus establish an upper bound on the frequency of such events. To do this, we use various analytical and numerical modeling techniques, including the RAGE hydrocode. RAGE (Baltrusaitis et al. 1996) is an Eulerian hydrocode that runs in up to three dimensions and incorporates a variety of detailed equations of state including the temperature-based SESAME tables maintained by LANL. In order to test the accuracy of RAGE predictions before applying this hydrocode to the problem of interest, we compare code results against analytical models (verification) and laboratory experiments (validation) that are related to the problem of interest. We compare RAGE against various laboratory experiments (Kato et al. 2001, Nakazawa et al. 2002, Koschny et al. 2001), and analytical crater scaling models (Housen et al. 1983, Holsapple and Schmidt 1982, Holsapple 1993, and Melosh 1989). From there, we begin to examine the potential effects of impacts on water ice in the Martian subsurface, first by examining the evolution of the temperature and pressure profiles of an impact into a geologically simple, ice-free target, and then exploring the effects of increased ice content and ice layer morphology. This effort is supported by LANL/IGPP (CSP, RFC, KHW, MLG) and by NASA PG&G (EA). LA-UR-06-6233

  4. Stability improvement of natural food colors: Impact of amino acid and peptide addition on anthocyanin stability in model beverages.

    PubMed

    Chung, Cheryl; Rojanasasithara, Thananunt; Mutilangi, William; McClements, David Julian

    2017-03-01

    Anthocyanins are prone to chemical degradation and color fading in the presence of vitamin C. The potential of three amino acids (l-phenylalanine, l-tyrosine, l-tryptophan) and a polypeptide (ε-poly-l-lysine) in prolonging the color stability of purple carrot anthocyanins (0.025%) in model beverages (0.05% l-ascorbic acid, citric acid, pH 3.0) stored at elevated temperature (40°C/7 days) was examined. In the absence of amino acids or peptides, anthocyanin degraded at first-order reaction rate. Addition of amino acids or peptide (0.1%) increased the color stability of anthocyanins, with the most significant improvement observed for l-tryptophan. The average half-life of anthocyanin color increased from 2 days to 6 days with l-tryptophan addition. Fluorescence quenching measurements revealed that the l-tryptophan interacted with anthocyanins mainly through hydrogen bonding, although some hydrophobic interaction may also have been involved. Overall, this study suggests that amino acid or peptide addition may prolong the color stability of anthocyanin in beverage products.

  5. Bayesian spatiotemporal analysis of zero-inflated biological population density data by a delta-normal spatiotemporal additive model.

    PubMed

    Arcuti, Simona; Pollice, Alessio; Ribecco, Nunziata; D'Onghia, Gianfranco

    2016-03-01

    We evaluate the spatiotemporal changes in the density of a particular species of crustacean known as deep-water rose shrimp, Parapenaeus longirostris, based on biological sample data collected during trawl surveys carried out from 1995 to 2006 as part of the international project MEDITS (MEDiterranean International Trawl Surv