WorldWideScience

Sample records for field jc estimation

  1. High transport Jc in magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

    Science.gov (United States)

    Gao, Zhaoshun; Togano, Kazumasa; Matsumoto, Akiyoshi; Kumakura, Hiroaki

    2015-01-01

    The recently discovered iron-based superconductors with very high upper critical field (Hc2) and small anisotropy have been regarded as a potential candidate material for high field applications. However, enhancements of superconducting properties are still needed to boost the successful use of iron-based superconductors in such applications. Here, we propose a new sheath architecture of stainless steel (SS)/Ag double sheath and investigate its influence on the microstructures and Jc-H property. We found that the transport Jc-H curves for rolled and pressed tapes both show extremely small magnetic field dependence and exceed 3 × 104 A cm-2 under 28 T, which are much higher than those of low-temperature superconductors. More interestingly, 12 cm long rolled tape shows very high homogeneity and sustains Jc as high as 7.7 × 104 A cm-2 at 10 T. These are the highest values reported so far for iron-based superconducting wires fabricated by scalable rolling process. The microstructure investigations indicate that such high Jc was achieved by higher density of the core and uniform deformation resulting better texturing. These results indicate that our process is very promising for fabricating long Ba122 wires for high field magnet, i.e. above 20 T.

  2. LINEAR MODEL ALTERNATIVE TO ESTIMATE THE GREEN BIOMASS OF THE Bambusa vulgaris SCHRAD. EX J.C. WENDL.WITHIN THE APPEARANCE OF MULTICOLLINEARITY

    Directory of Open Access Journals (Sweden)

    Adriano Victor Lopes da Silva

    2009-09-01

    Full Text Available The objective of this work was to use a multivariate statistical method as an alternative to estimate the green biomass of the main bamboo rod, Bambusa vulgaris Schrad. i.e.: J.C. Wendl., in the presence of multicollinearity. The data came from an experiment carried out for the Agroindustrial Excelsior S. A. (Agrimex company located in the city of Goiana – PE. Quantified by their green biomass weight, 450 bamboo rods were used and 4 independent variables measured in the rod. Initially, the presence of the multicollinearity could be verified through the correlation matrix of the independent variables and the varience inflation factors, the alternative used was the regression of the principal components based on the covariate matrix. The result indicates that, when there is an interpretation to the main components, the model shows a satisfactory data adjust, and it could be used to estimate the green biomass of the main bamboo rod.

  3. The effects of graphene doping on the in-field Jc of MgB2 wires.

    Science.gov (United States)

    Xu, X; Li, W X; Zhang, Y; De Silva, K S B; Kim, J H; Choi, S

    2012-02-01

    The field and temperature dependence of the critical current density Jct were measured for both un-doped and graphene doped MgB2/Fe wires manufactured by 99.999% Crystalline Boron and 10% excess Magnesium (99%, 325 mesh). At 4.2 K and 10 T, Jct was estimated to be for the wire sintered at 800 degrees C for 30 minutes, the doped sample is almost improved as one order, compared with the best un-doped sample. At the same time, the temperature dependence of the upper critical field (Hc2) and the irreversibility field (Hirr) for the samples will also be included from the resistance (R)-temperature (T). A significant increase in the upper critical field is the main cause of the enhancement of the critical current density, Jct, in the high field region. The calculated active cross-sectional area fraction (A(F)) represents the connectivity factor between adjacent grains. This value is decreased with wire samples, which is why the improvement of transport Jct is lower than the improvement of magnetic Jcm in diffusion bulk sample.

  4. J.C. Christensen

    DEFF Research Database (Denmark)

    Duedahl, Poul

    J.C. Christensen var kun regeringsleder i tre år, men i en lille menneskealder kunne stort set intet ske i dansk politik uden om ham. I et kvart århundrede var han et magtcentrum. Centralt i J.C. Christensens politiske virke i årene 1890-1924 stod kampen for det parlamentariske folkestyre....... Parlamentarismen har lige siden udgjort fundamentet for vores styreform, og dens fortsatte betydning og grundlovsfæstede status gør den til den betydeligste arv, J.C. Christensen har efterladt sig. Men hvem var J.C. Christensen egentlig? Han satte sit afgørende fingeraftryk på indførelsen af kvindelig valgret......, stiftelsen af Det Radikale Venstre og Venstre, tilblivelsen af det norske kongehus, Albertiaffæren, salget af De Vestindiske Øer, Påskekrisen og genforeningen med Sønderjylland. Nu har J.C. Christensens efterkommere for første gang givet adgang til hans efterladte dagbøger og breve. Det har gjort det muligt...

  5. An alternative to estimate the atmospheric carbon sequestration by Bambusa vulgaris var. vulgaris Schrad. ex J.C. Wendl.

    Directory of Open Access Journals (Sweden)

    Alicia Mercadet

    2011-07-01

    Full Text Available The estimation of atmospheric carbon sequestration by a woody plant has two alternatives for implementation: by identifying the average annual increase in volume or by determining the appropriate method for calculating the volume stand. The aim of this work was to obtain a reliable and simple method for estimating the carbon in plants and culms of bamboo (Bambusa vulgaris var. vulgaris existing in a territory. Single samples were taken without replacement in different areas and each culm was measured in total length, outside diameter and wall thickness every two meters from the base to the segment in the upper left to present an interior cavity identifiable, in which the remaining length to the top was measured. Graphical analyses were conducted with the data collected of trends in relations between the variables considered along the culm. By regression analysis with different models and the use of determination coefficient (R2 as an adjustment indicator, we selected those that best allow estimating the solid volume of the culm. After obtaining the calibration models and their results, we prepared a spreadsheet that facilitates to take down the values of the different variables by culm and scion as well as the characterization of the scion average culm. The results are a first attempt to develop a method for estimating the carbon sequestered by the bamboo culm at both as scion and territory to include this element among the criteria for the management plans of this non-wood forest resource. Key words: allometric models, bamboo, regression analysis

  6. J.C. Christensen

    DEFF Research Database (Denmark)

    Duedahl, Poul

    I mange år var det en almindelig antagelse, at statsminister J.C. Christensens dagbøger var blevet brændt efter hans død. Nu er hans dagbøger fra årene 1900-09 imidlertid dukket op, og de giver et indblik i dansk politik i årene omkring Systemskiftet. Dagbøgerne dækker den periode, hvor J.C...... af justitsminister P.A. Albertis bedragerier og optakten til en rigsretssag. De tyve små dagbøger indeholder optegnelser om stort og småt fra perioden. De tjente som et sted, hvor den normalt tillukkede J.C. Christensen fik luft for private og ikke mindst politiske bekymringer, og mange af aktørerne...... i det politiske liv blev i dagbøgerne udsat for skarpe bemærkninger. J.C. Christensens dagbøger giver et enestående indblik i et stykke Danmarkshistorie set fra første række....

  7. Estimator for Random Fields

    Directory of Open Access Journals (Sweden)

    Sidi Ali Ould Abdi

    2011-01-01

    Full Text Available Given a stationary multidimensional spatial process (i=(i,i∈ℝ×ℝ,i∈ℤ, we investigate a kernel estimate of the spatial conditional quantile function of the response variable i given the explicative variable i. Asymptotic normality of the kernel estimate is obtained when the sample considered is an -mixing sequence.

  8. Estimation of Motion Vector Fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1993-01-01

    This paper presents an approach to the estimation of 2-D motion vector fields from time varying image sequences. We use a piecewise smooth model based on coupled vector/binary Markov random fields. We find the maximum a posteriori solution by simulated annealing. The algorithm generate sample...

  9. Entropy estimates for simple random fields

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Justesen, Jørn

    1995-01-01

    We consider the problem of determining the maximum entropy of a discrete random field on a lattice subject to certain local constraints on symbol configurations. The results are expected to be of interest in the analysis of digitized images and two dimensional codes. We shall present some examples...... of binary and ternary fields with simple constraints. Exact results on the entropies are known only in a few cases, but we shall present close bounds and estimates that are computationally efficient...

  10. 磁场、温度对Bi-2223/Ag多芯带Jc的影响%Influences of Temperature and Field on Jc of Bi-2223/Ag Multifilamentary Tapes

    Institute of Scientific and Technical Information of China (English)

    滕鑫康; 吴欢; 应诗臣; 冯勇; 张平祥; 周廉

    2001-01-01

    介绍了一套液氮温区Jc(B,T)测量系统,该系统用增大液氮的饱和蒸气压来达到提高液氮温度的目的。用该系统研究了磁场和温度(测量范围分别为0.1 T~0.8 T和77 K~90 K)对Bi-2223/Ag多芯带材(19芯和37芯)临界电流的影响。

  11. Bayesian parameter estimation for effective field theories

    CERN Document Server

    Wesolowski, S; Furnstahl, R J; Phillips, D R; Thapaliya, A

    2015-01-01

    We present procedures based on Bayesian statistics for effective field theory (EFT) parameter estimation from data. The extraction of low-energy constants (LECs) is guided by theoretical expectations that supplement such information in a quantifiable way through the specification of Bayesian priors. A prior for natural-sized LECs reduces the possibility of overfitting, and leads to a consistent accounting of different sources of uncertainty. A set of diagnostic tools are developed that analyze the fit and ensure that the priors do not bias the EFT parameter estimation. The procedures are illustrated using representative model problems and the extraction of LECs for the nucleon mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  12. Bayesian parameter estimation for effective field theories

    Science.gov (United States)

    Wesolowski, S.; Klco, N.; Furnstahl, R. J.; Phillips, D. R.; Thapaliya, A.

    2016-07-01

    We present procedures based on Bayesian statistics for estimating, from data, the parameters of effective field theories (EFTs). The extraction of low-energy constants (LECs) is guided by theoretical expectations in a quantifiable way through the specification of Bayesian priors. A prior for natural-sized LECs reduces the possibility of overfitting, and leads to a consistent accounting of different sources of uncertainty. A set of diagnostic tools is developed that analyzes the fit and ensures that the priors do not bias the EFT parameter estimation. The procedures are illustrated using representative model problems, including the extraction of LECs for the nucleon-mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  13. Aquaporin JcPIP2 is involved in drought responses in Jatropha curcas.

    Science.gov (United States)

    Zhang, Ying; Wang, Yunxiao; Jiang, Luding; Xu, Ying; Wang, Yingchun; Lu, Daihua; Chen, Fang

    2007-10-01

    Water channel proteins, aquaporins, play fundamental roles in transmembrane water movements in plants. A new full-length cDNA encoding aquaporin was isolated from the seedlings of Jatropha curcas. The gene of the plasma membrane intrinsic protein (PIP) from J. curcas (JcPIP2) contained an 843 bp open reading frame encoding a protein of 280 amino acids. The amino acid sequence showed 94% identity with Ricinus communis PIP. Injection of JcPIP2 complementary RNA into Xenopus oocytes increased 10-fold the osmotic water permeability of the oocytes. Immunodetection of JcPIP2 with anti-JcPIP2 antibody indicated that this protein is ubiquitously located in all tested tissues of the plant. To investigate the relationship between aquaporins and drought resistance in J. curcas, the abundance of JcPIP2 was examined in seedlings of two J. curcas populations, GaoYou CSC63 and YanBian S1, under water deficit with PEG6000. Under field conditions, those two populations, GaoYou CSC63 was resistant to water deficit, but YanBian S1 was sensitive to water deprivation. With the increasing degree of drought stress, JcPIP2 level increased in seedlings of GaoYou CSC63, whereas there was no significant change in seedlings of YanBian S1. Compared with YanBian S1, GaoYou CSC63 also showed higher root hydraulic conductivity and lower decreasing trend in the seedlings under water deficit. These results indicated that JcPIP2 probably played a role in drought resistance in J. curcas.

  14. Aquaporin JcPIP2 is Involved in Drought Responses in Jatropha curcas

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Yunxiao WANG; Luding JIANG; Ying XU; Yingchun WANG; Daihua LU; Fang CHEN

    2007-01-01

    Water channel proteins, aquaporins, play fundamental roles in transmembrane water movements in plants. A new full-length cDNA encoding aquaporin was isolated from the seedlings of Jatropha curcas.The gene of the plasma membrane intrinsic protein (PIP) from J. curcas (JcPIP2) contained an 843 bp open reading frame encoding a protein of 280 amino acids. The amino acid sequence showed 94% identity with Ricinus communis PIP. Injection of JcPIP2 complementary RNA into Xenopus oocytes increased 10-fold the osmotic water permeability of the oocytes. Immunodetection of JcPIP2 with anti-JcPIP2 antibody indicated that this protein is ubiquitously located in all tested tissues of the plant. To investigate the relationship between aquaporins and drought resistance in J. curcas, the abundance of JcPIP2 was examined in seedlings of two J. curcas populations, Gao You CSC63 and YanBian S1, under water deficit with PEG6000. Under field conditions, those two populations, Gao You CSC63 was resistant to water deficit, but YanBian S1 was sensitive to water deprivation. With the increasing degree of drought stress, JcPIP2 level increased in seedlings of Gao You CSC63, whereas there was no significant change in seedlings of YanBian S1. Compared with YanBian S1, GaoYou CSC63 also showed higher root hydraulic conductivity and lower decreasing trend in the seedlings under water deficit. These results indicated that JcPIP2 probably played a role in drought resistance in J. curcas.

  15. Random field estimation approach to robot dynamics

    Science.gov (United States)

    Rodriguez, Guillermo

    1990-01-01

    The difference equations of Kalman filtering and smoothing recursively factor and invert the covariance of the output of a linear state-space system driven by a white-noise process. Here it is shown that similar recursive techniques factor and invert the inertia matrix of a multibody robot system. The random field models are based on the assumption that all of the inertial (D'Alembert) forces in the system are represented by a spatially distributed white-noise model. They are easier to describe than the models based on classical mechanics, which typically require extensive derivation and manipulation of equations of motion for complex mechanical systems. With the spatially random models, more primitive locally specified computations result in a global collective system behavior equivalent to that obtained with deterministic models. The primary goal of applying random field estimation is to provide a concise analytical foundation for solving robot control and motion planning problems.

  16. Geostatistical Estimations of Regional Hydraulic Conductivity Fields

    Science.gov (United States)

    Patriarche, D.; Castro, M. C.; Goovaerts, P.

    2004-12-01

    Direct and indirect measurements of hydraulic conductivity (K) are commonly performed, providing information on the magnitude of this parameter at the local scale (tens of centimeters to hundreds of meters) and at shallow depths. By contrast, field information on hydraulic conductivities at regional scales of tens to hundreds of kilometers and at greater depths is relatively scarce. Geostatistical methods allow for sparsely sampled observations of a variable (primary information) to be complemented by a more densely sampled secondary attribute. Geostatistical estimations of the hydraulic conductivity field in the Carrizo aquifer, a major groundwater flow system extending along Texas, are performed using available primary (e.g., transmissivity, hydraulic conductivity) and secondary (specific capacity) information, for depths up to 2.2 km, and over three regional domains of increasing extent: 1) the domain corresponding to a three-dimensional groundwater flow model previously built (model domain); 2) the area corresponding to the ten counties encompassing the model domain (County domain), and; 3) the full extension of the Carrizo aquifer within Texas (Texas domain). Two different approaches are used: 1) an indirect approach are transmissivity (T) is estimated first and (K) is retrieved through division of the T estimate by the screening length of the wells, and; 2) a direct approach where K data are kriged directly. Prediction performances of the tested geostatistical procedures (kriging combined with linear regression, kriging with known local means, kriging of residuals, and cokriging) are evaluated through cross validation for both log-transformed variables and back-transformed ones. For the indirect approach, kriging of log T residuals yields the best estimates for both log-transformed and back-transformed variables in the model domain. For larger regional scales (County and Texas domains), cokriging performs generally better than univariate kriging procedures

  17. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    1998-01-01

    The estimation of flow fields from time sequences of satellite imagery has a number of important applications. For visualisation of cloud or sea ice movements in sequences of crude temporal sampling a satisfactory non-blurred temporal interpolation can be performed only when the flow field...... images. The estimated flow fields are used in a temporal interpolation scheme....

  18. Restriction estimates for the paraboloid over finite fields

    CERN Document Server

    Lewko, Allison

    2010-01-01

    We prove certain endpoint restriction estimates for the paraboloid over finite fields in three and higher dimensions. Working in the bilinear setting, we are able to pass from estimates for characteristic functions to estimates for general functions while avoiding the extra logarithmic power of the field size which is introduced by the dyadic pigeonhole approach. This allows us to remove logarithmic factors from the estimates obtained by Mockenhaupt and Tao in three dimensions and those obtained by Iosevich and Koh in higher dimensions.

  19. Uncertainty principle estimates for vector fields

    OpenAIRE

    Pérez Moreno, Carlos; Wheeden, Richard L.

    2001-01-01

    We derive weighted norm estimates for integral operators of potential type and for their related maximal operators. These operators are generalizations of the classical fractional integrals and fractional maximal functions. The norm estimates are derived in the context of a space of homogeneous type. The conditions required of the weight functions involve generalizations of the Fefferman-Phong "r-bump" condition. The results improve some earlier ones of the same kind, and they also extend to ...

  20. Auditory Perception in Open Field: Distance Estimation

    Science.gov (United States)

    2013-07-01

    the distance and spaciousness estimation cues can be ambiguous (e.g., sound intensity, sound spectrum) or are fairly weak (e.g., binaural cues...Invariance in Sound Perception. Acta Psychologica Fennica 1951, 1, 9–20. Florentine, M.; Epstein, M. Ecological Loudness. Binaural Loudness Constancy...8, 145–149. 50 Lu, Y-Ch.; Cooke, M. Binaural Estimation of Sound Source Distance via the Direct-to- Reverberant Energy Ratio for Static and Moving

  1. Rad51 activates polyomavirus JC early transcription.

    Directory of Open Access Journals (Sweden)

    Martyn K White

    Full Text Available The human neurotropic polyomavirus JC (JCV causes the fatal CNS demyelinating disease progressive multifocal leukoencephalopathy (PML. JCV infection is very common and after primary infection, the virus is able to persist in an asymptomatic state. Rarely, and usually only under conditions of immune impairment, JCV re-emerges to actively replicate in the astrocytes and oligodendrocytes of the brain causing PML. The regulatory events involved in the reactivation of active viral replication in PML are not well understood but previous studies have implicated the transcription factor NF-κB acting at a well-characterized site in the JCV noncoding control region (NCCR. NF-κB in turn is regulated in a number of ways including activation by cytokines such as TNF-α, interactions with other transcription factors and epigenetic events involving protein acetylation--all of which can regulate the transcriptional activity of JCV. Active JCV infection is marked by the occurrence of rapid and extensive DNA damage in the host cell and the induction of the expression of cellular proteins involved in DNA repair including Rad51, a major component of the homologous recombination-directed double-strand break DNA repair machinery. Here we show that increased Rad51 expression activates the JCV early promoter. This activation is co-operative with the stimulation caused by NF-κB p65, abrogated by mutation of the NF-κB binding site or siRNA to NFκB p65 and enhanced by the histone deacetylase inhibitor sodium butyrate. These data indicate that the induction of Rad51 resulting from infection with JCV acts through NF-κB via its binding site to stimulate JCV early transcription. We suggest that this provides a novel positive feedback mechanism to enhance viral gene expression during the early stage of JCV infection.

  2. Parameter estimation of hidden periodic model in random fields

    Institute of Scientific and Technical Information of China (English)

    何书元

    1999-01-01

    Two-dimensional hidden periodic model is an important model in random fields. The model is used in the field of two-dimensional signal processing, prediction and spectral analysis. A method of estimating the parameters for the model is designed. The strong consistency of the estimators is proved.

  3. Variational multi-valued velocity field estimation for transparent sequences

    DEFF Research Database (Denmark)

    Ramirez-Manzanares, Alonso; Rivera, Mariano; Kornprobst, Pierre;

    2011-01-01

    Motion estimation in sequences with transparencies is an important problem in robotics and medical imaging applications. In this work we propose a variational approach for estimating multi-valued velocity fields in transparent sequences. Starting from existing local motion estimators, we derive a...

  4. Estimating thermal performance curves from repeated field observations

    Science.gov (United States)

    Childress, Evan; Letcher, Benjamin H.

    2017-01-01

    Estimating thermal performance of organisms is critical for understanding population distributions and dynamics and predicting responses to climate change. Typically, performance curves are estimated using laboratory studies to isolate temperature effects, but other abiotic and biotic factors influence temperature-performance relationships in nature reducing these models' predictive ability. We present a model for estimating thermal performance curves from repeated field observations that includes environmental and individual variation. We fit the model in a Bayesian framework using MCMC sampling, which allowed for estimation of unobserved latent growth while propagating uncertainty. Fitting the model to simulated data varying in sampling design and parameter values demonstrated that the parameter estimates were accurate, precise, and unbiased. Fitting the model to individual growth data from wild trout revealed high out-of-sample predictive ability relative to laboratory-derived models, which produced more biased predictions for field performance. The field-based estimates of thermal maxima were lower than those based on laboratory studies. Under warming temperature scenarios, field-derived performance models predicted stronger declines in body size than laboratory-derived models, suggesting that laboratory-based models may underestimate climate change effects. The presented model estimates true, realized field performance, avoiding assumptions required for applying laboratory-based models to field performance, which should improve estimates of performance under climate change and advance thermal ecology.

  5. Estimating thermal performance curves from repeated field observations.

    Science.gov (United States)

    Childress, Evan S; Letcher, Benjamin H

    2017-03-08

    Estimating thermal performance of organisms is critical for understanding population distributions and dynamics and predicting responses to climate change. Typically, performance curves are estimated using laboratory studies to isolate temperature effects, but other abiotic and biotic factors influence temperature-performance relationships in nature reducing these models' predictive ability. We present a model for estimating thermal performance curves from repeated field observations that includes environmental and individual variation. We fit the model in a Bayesian framework using MCMC sampling, which allowed for estimation of unobserved latent growth while propagating uncertainty. Fitting the model to simulated data varying in sampling design and parameter values demonstrated that the parameter estimates were accurate, precise, and unbiased. Fitting the model to individual growth data from wild trout revealed high out-of-sample predictive ability relative to laboratory-derived models, which produced more biased predictions for field performance. The field-based estimates of thermal maxima were lower than those based on laboratory studies. Under warming temperature scenarios, field-derived performance models predicted stronger declines in body size than laboratory-derived models, suggesting that laboratory-based models may underestimate climate change effects. The presented model estimates true, realized field performance, avoiding assumptions required for applying laboratory-based models to field performance, which should improve estimates of performance under climate change and advance thermal ecology. This article is protected by copyright. All rights reserved.

  6. TEM study of layered defects in high J_c MTG-YBCO

    Institute of Scientific and Technical Information of China (English)

    王葛亚; 施天生; 傅耀先; 蔡传兵; 杨宏川

    1995-01-01

    The microstructure and defects in melt-textured growth (MTG) YBa2Cu3O7-x (YBCO) bulk material have been studied systematically using high resolution transmission electron microscopy (HREM), and the relationship between the anisotropic critical current density Jc and the microstructure has been explored. The results indicate that there are numerous dense and nonunifonnly-distributed intergrowth-type layered defects orienting parallel to the ab plane in MTG-YBCO. These defects may serve as effective flux pinning centres for H//ab. The layered defects parallel to the ab plane together with the {110} twin boundaries are probably responsible for the anisotiopic behaviour of Jc depending upon the orientation of the external magnetic field.

  7. Moment analysis of the Delaunay tessellation field estimator

    NARCIS (Netherlands)

    Lieshout, M.N.M. van

    2009-01-01

    The Campbell-Mecke theorem is used to derive explicit expressions for the mean and variance of Schaap and Van de Weygaert's Delaunay tessellation field estimator. Special attention is paid to Poisson processes.

  8. Lipschitz estimates for convex functions with respect to vector fields

    Directory of Open Access Journals (Sweden)

    Valentino Magnani

    2012-12-01

    Full Text Available We present Lipschitz continuity estimates for a class of convex functions with respect to Hörmander vector fields. These results have been recently obtained in collaboration with M. Scienza, [22].

  9. Far-field DOA estimation and near-field localization for multipath signals

    Science.gov (United States)

    Elbir, Ahmet M.; Tuncer, T. Engin

    2014-09-01

    In direction finding and localization applications, multipath signals are important sources of error for parameter estimation. When the antenna array receives multipath reflections which are coherent with the far-field line-of-sight signal, estimating the far- and near-field components becomes an important problem. In this paper, a new method is proposed to estimate the direction-of-arrival (DOA) of the far-field source and to localize its near-field multipaths. Far-field source DOA is estimated using calibration of the antenna array. A near-to-far transformation is proposed for the estimation of the near-field source DOA angles. In order to estimate the near-field range parameters, a compressive sensing approach is presented where a dictionary with near-field sources with different ranges is employed. As a result, the proposed method estimates the far-field and near-field source DOAs as well as the range and the signal amplitudes of the near-field sources. This method is evaluated using close-to-real world data generated by a numerical electromagnetic tool, where the array and transmitter are placed in an irregular terrain and array data are generated using full 3-D propagation model. It is shown that unknown source parameters can be estimated effectively showing the potential of the proposed approach in applications involving high-frequency direction finding and indoor localization.

  10. Attitude and Trajectory Estimation Using Earth Magnetic Field Data

    Science.gov (United States)

    Deutschmann, Julie; Bar-Itzhack, Itzhack Y.

    1996-01-01

    The magnetometer has long been a reliable, inexpensive sensor used in spacecraft momentum management and attitude estimation. Recent studies show an increased accuracy potential for magnetometer-only attitude estimation systems. Since the Earth's magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computer and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both the spacecraft trajectory and attitude errors. Therefore, these errors can be used to estimate both trajectory and attitude. Traditionally, satellite attitude and trajectory have been estimated with completely separate system, using different measurement data. Recently, trajectory estimation for low earth orbit satellites was successfully demonstrated in ground software using only magnetometer data. This work proposes a single augmented extended Kalman Filter to simultaneously and autonomously estimate both spacecraft trajectory and attitude with data from a magnetometer and either dynamically determined rates or gyro-measured body rates.

  11. Influence of twisting and bending on the Jc and n-value of multifilamentary MgB2 strands

    Science.gov (United States)

    Yang, Y.; Li, G.; Susner, M.; Sumption, M. D.; Rindfleisch, M.; Tomsic, M.; Collings, E. W.

    2015-12-01

    The influences of strand twisting and bending (applied at room temperature) on the critical current densities, Jc, and n-values of MgB2 multifilamentary strands were evaluated at 4.2 K as function of applied field strength, B. Three types of MgB2 strand were evaluated: (i) advanced internal magnesium infiltration (AIMI)-processed strands with 18 filaments (AIMI-18), (ii) powder-in-tube (PIT) strands processed using a continuous tube forming and filling (CTFF) technique with 36 filaments (PIT-36) and (iii) CTFF processed PIT strands with 54 filaments (PIT-54). Transport measurements of Jc(B) and n-value at 4.2 K in fields of up to 10 T were made on: (i) PIT-54 after it was twisted (at room temperature) to twist pitch values, Lp, of 10-100 mm. Transport measurements of Jc(B) and n-value were performed at 4.2 K; (ii) PIT-36 and AIMI-18 after applying bending strains up to 0.6% at room temperature. PIT-54 twisted to pitches of 100 mm down to 10 mm exhibited no degradation in Jc(B) and only small changes in n-value. Both the Jc(B) and n-value of PIT-36 were seen to be tolerant to bending strain of up to 0.4%. On the other hand, AIMI-18 showed ±10% changes in Jc(B) and significant scatter in n-value over the bending strain range of 0-0.6%.

  12. J.C. Christensens ministermødereferater

    DEFF Research Database (Denmark)

    Duedahl, Poul

    J.C. Christensen (1856-1930) var i mere end et kvart århundrede en af Danmarks ledende politikere. Dette kildeskrift indeholder hans private ministermødeprotokol for de år, hvor han sad som kontrolminister i den radikale C.Th. Zahles regering. På væsentlige punkter supplerer og korrigerer...... protokollen de hidtidige kendte officielle referater, ligesom den indeholder skildringer af statsrådsmøder og nogle private samtaler, J.C. Christensen førte med Christian 10. Protokollen rummer væsentlige detaljer om den vanskelige tid under 1. verdenskrig og om J.C. Christensen som politiker, særlig om hans...

  13. Estimation of fluid flow fields and their stagnation points

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    Given a temporal sequence of images of fluids we will use local polynomials to regularise obser-vations of normal flows into smooth flow fields. This technique furthermore allows us to give a qualitative local description of the flow field and to estimate the position of stagnation points...

  14. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    The estimation of flow fields from time sequences of satellite imagery has a number of important applications. For visualization of cloud or sea ice movements in sequences of crude temporal sampling a satisfactory non blurred temporal interpolation can be performed only when the flow field...... interpolation scheme....

  15. JC virus detection and JC virus-specific immunity in natalizumab-treated Multiple Sclerosis patients

    Directory of Open Access Journals (Sweden)

    Mancuso Roberta

    2012-12-01

    Full Text Available Abstract Background The use of natalizumab in multiple sclerosis (MS may favour JC virus reactivation; this phenomenon is usually asymptomatic but can, albeit rarely, evolve into frank progressive multifocal leucoencephalopathy (PML. Methods JCV-specific CD8+ T lymphocytes were evaluated by flow cytometry over a 24-month period in 24 natalizumab-treated MS patients in whom JCV DNA was or was not detected in blood using quantitative real-time polymerase chain reaction; all these cases were asymptomatic. Results Perforin- and grazymes-containing VP-1-specific CD8+ T lymphocytes were reduced whereas CD107a-expressing cells were increased in JCV positive patients, suggesting an active degranulation of these cells; naïve CD8+ T lymphocytes were also decreased whereas memory cells were increased in patients in whom JCV reactivation was observed. Conclusion The presence of a CD8+ T lymphocyte-mediated effector immune response offers a greater insight into reactivation of JCV and its clinical sequelae, and may help the monitoring of patients on natalizumab therapy.

  16. Reverberant shear wave fields and estimation of tissue properties

    Science.gov (United States)

    Parker, Kevin J.; Ormachea, Juvenal; Zvietcovich, Fernando; Castaneda, Benjamin

    2017-02-01

    The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave behavior is assumed with a known direction of propagation. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space. Thus, we explore the mathematics of multiple component shear wave fields and derive the basic properties, from which efficient estimators can be obtained. We approach this problem from the historic perspective of reverberant fields, a conceptual framework used in architectural acoustics and related fields. The framework can be recast for the alternative case of shear waves in a bounded elastic media, and the expected value of displacement patterns in shear reverberant fields are derived, along with some practical estimators of shear wave speed. These are applied to finite element models and phantoms to illustrate the characteristics of reverberant fields and provide preliminary confirmation of the overall framework.

  17. Analytical maximum likelihood estimation of stellar magnetic fields

    CERN Document Server

    González, M J Martínez; Ramos, A Asensio; Belluzzi, L

    2011-01-01

    The polarised spectrum of stellar radiation encodes valuable information on the conditions of stellar atmospheres and the magnetic fields that permeate them. In this paper, we give explicit expressions to estimate the magnetic field vector and its associated error from the observed Stokes parameters. We study the solar case where specific intensities are observed and then the stellar case, where we receive the polarised flux. In this second case, we concentrate on the explicit expression for the case of a slow rotator with a dipolar magnetic field geometry. Moreover, we also give explicit formulae to retrieve the magnetic field vector from the LSD profiles without assuming mean values for the LSD artificial spectral line. The formulae have been obtained assuming that the spectral lines can be described in the weak field regime and using a maximum likelihood approach. The errors are recovered by means of the hermitian matrix. The bias of the estimators are analysed in depth.

  18. Estimation of Centers and Stagnation points in optical flow fields

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    1997-01-01

    In a topological sense fluid flows are characterised by their stagnation points. Given a temporal sequence of images of fluids we will consider the application of local polynomials to the estimation of smooth fluid flow fields. The normal flow at intensity contours is estimated from the local...... distribution of spatio-temporal energy, which is sampled using a set of spatio-temporal quadrature filters. These observations of normal flows are then integrated into smooth flow fields by locally approximating first order polynomials in the spatial coordinates to the flow vectors. This technique furthermore...... allows us to give a qualitative local description of the flow field and to estimate the position of stagnation points (e.g. nodes, saddles, and centers). We will apply the algorithm to two data sets. The first sequence consists of infrared images from the meteorological satellite Meteosat. Here...

  19. Distributed estimation of a parametric field with random sensor placements

    Science.gov (United States)

    Alkhweldi, Marwan; Cao, Zhicheng; Schmid, Natalia A.

    2015-05-01

    This paper considers a problem of distributed function estimation in the case when sensor locations are modeled as Gaussian random variables. We consider a scenario where sensors are deployed in clusters with cluster centers known a priori (or estimated by a high performance GPS) and the average quadratic spread of sensors around the cluster center also known. Distributed sensors make noisy observations about an unknown parametric field generated by a physical object of interest (for example, magnetic field generated by a ferrous object and sensed by a network of magnetometers). Each sensor then performs local signal processing of its noisy observation and sends it to a central processor (called fusion center) in the wireless sensor network over parallel channels corrupted by fading and additive noise. The central processor combines the set of received signals to form an estimate of the unknown parametric field. In our numerical analysis, we involve a field shaped as a Gaussian bell. We experiment with the size of sensor clusters and with their number. A mean square error between the estimated parameters of the field and the true parameters used in simulations is involved as a performance measure. It can be shown that a relatively good estimate of the field can be obtained with only a small number of clusters. As the number of clusters increases, the estimation performance steadily improves. The results also indicate that, on the average, the number of clusters has more impact on the performance than the number of sensors per cluster, given the same size of the total network.

  20. Fuzzy logic based ELF magnetic field estimation in substations.

    Science.gov (United States)

    Kosalay, Ilhan

    2008-01-01

    This paper examines estimation of the extremely low frequency magnetic fields (MF) in the power substation. First, the results of the previous relevant research studies and the MF measurements in a sample power substation are presented. Then, a fuzzy logic model based on the geometric definitions in order to estimate the MF distribution is explained. Visual software, which has a three-dimensional screening unit, based on the fuzzy logic technique, has been developed.

  1. Determination of the true (or potential) transport- Jc of a multifilamentary Bi:HTSC/Ag strand in the presence of bridging and generalized sausaging

    Science.gov (United States)

    Sumption, M. D.; Motowidlo, L. R.; Collings, E. W.

    1997-12-01

    In generally well-connected high-temperature superconducting strands the overall measured transport critical current density (CCD), JcT,meas (`averaged' over grains and grain boundaries) is suppressed (or `throttled') to less than its maximum possible value, here referred to as the intrinsic CCD, JcT,intr, as a result, for example, of filament-diameter undulations (sausaging), path constrictions due to non-superconducting inclusions, cracking, and in extreme cases filament breakage. A realizable goal in the form of an estimated JcT,intr is a valuable adjunct to process optimization activities. It is shown that in fine-filament monocore or multifilamentary (MF) strands the magnetically measured CCD, Jc,mag, although not necessarily equal to JcT,intr provides a useful lower limit to it. By the same token, in bridged MF strands the saturated bridged magnetization, Δ Mbr,sat, under ideal conditions could yield an actual value for JcT,intr, and in general will provide a lower limit. Based on these principles, analysis of the bridged magnetizations of a group of round MF Bi:2212/Ag strands yielded Jct,intr (4.2 K) lower limits of 3˜7×10 5 A/cm 2.

  2. Measurement of electric fields and estimation of dielectric susceptibility

    Science.gov (United States)

    Nogi, Yasuyuki; Suzuki, Kiyomitsu; Ohkuma, Yasunori

    2013-05-01

    We describe a method of measuring the spatial structures of electric fields produced by charge distributions such as those on strip electrodes, small disk electrodes, and long double-plate electrodes. An electric-field sensor with high sensitivity to ac fields is fabricated for the measurement using a thin copper sheet. The reliability of the sensor is confirmed using a parallel-plate capacitor. The electric fields are oscillated at a frequency of 300 kHz to operate the electric-field sensor successfully. The structures of the measured fields coincide well with those of theoretical fields derived from Coulomb's law. When a dielectric is inserted in an electric field, polarization charges appear on the surface of the dielectric and modify the electric field in empty space. We measure the modified field and confirm the well-known linear relation between the polarization of a dielectric and the electric field. Dielectric susceptibilities are estimated from the linear relation for four types of dielectric.

  3. Estimating neuronal connectivity from axonal and dendritic density fields

    Science.gov (United States)

    van Pelt, Jaap; van Ooyen, Arjen

    2013-01-01

    Neurons innervate space by extending axonal and dendritic arborizations. When axons and dendrites come in close proximity of each other, synapses between neurons can be formed. Neurons vary greatly in their morphologies and synaptic connections with other neurons. The size and shape of the arborizations determine the way neurons innervate space. A neuron may therefore be characterized by the spatial distribution of its axonal and dendritic “mass.” A population mean “mass” density field of a particular neuron type can be obtained by averaging over the individual variations in neuron geometries. Connectivity in terms of candidate synaptic contacts between neurons can be determined directly on the basis of their arborizations but also indirectly on the basis of their density fields. To decide when a candidate synapse can be formed, we previously developed a criterion defining that axonal and dendritic line pieces should cross in 3D and have an orthogonal distance less than a threshold value. In this paper, we developed new methodology for applying this criterion to density fields. We show that estimates of the number of contacts between neuron pairs calculated from their density fields are fully consistent with the number of contacts calculated from the actual arborizations. However, the estimation of the connection probability and the expected number of contacts per connection cannot be calculated directly from density fields, because density fields do not carry anymore the correlative structure in the spatial distribution of synaptic contacts. Alternatively, these two connectivity measures can be estimated from the expected number of contacts by using empirical mapping functions. The neurons used for the validation studies were generated by our neuron simulator NETMORPH. An example is given of the estimation of average connectivity and Euclidean pre- and postsynaptic distance distributions in a network of neurons represented by their population mean density

  4. Volumetric breast density estimation from full-field digital mammograms.

    NARCIS (Netherlands)

    Engeland, S. van; Snoeren, P.R.; Huisman, H.J.; Boetes, C.; Karssemeijer, N.

    2006-01-01

    A method is presented for estimation of dense breast tissue volume from mammograms obtained with full-field digital mammography (FFDM). The thickness of dense tissue mapping to a pixel is determined by using a physical model of image acquisition. This model is based on the assumption that the breast

  5. Precise numerical estimation of the magnetic field generated around recombination

    Science.gov (United States)

    Fidler, Christian; Pettinari, Guido; Pitrou, Cyril

    2016-05-01

    We investigate the generation of magnetic fields from nonlinear effects around recombination. As tight-coupling is gradually lost when approaching z ≃1100 , the velocity difference between photons and baryons starts to increase, leading to an increasing Compton drag of the photons on the electrons. The protons are then forced to follow the electrons due to the electric field created by the charge displacement; the same field, following Maxwell's laws, eventually induces a magnetic field on cosmological scales. Since scalar perturbations do not generate any magnetic field as they are curl-free, one has to resort to second-order perturbation theory to compute the magnetic field generated by this effect. We reinvestigate this problem numerically using the powerful second-order Boltzmann code SONG. We show that: (i) all previous studies do not have a high enough angular resolution to reach a precise and consistent estimation of the magnetic field spectrum; (ii) the magnetic field is generated up to z ≃10 ; (iii) it is in practice impossible to compute the magnetic field with a Boltzmann code for scales smaller than 1 Mpc. Finally we confirm that for scales of a few Mpc, this magnetic field is of order 2 ×10-29 G , many orders of magnitude smaller than what is currently observed on intergalactic scales.

  6. High resolution, large dynamic range field map estimation

    Science.gov (United States)

    Dagher, Joseph; Reese, Timothy; Bilgin, Ali

    2013-01-01

    Purpose We present a theory and a corresponding method to compute high resolution field maps over a large dynamic range. Theory and Methods We derive a closed-form expression for the error in the field map value when computed from two echoes. We formulate an optimization problem to choose three echo times which result in a pair of maximally distinct error distributions. We use standard field mapping sequences at the prescribed echo times. We then design a corresponding estimation algorithm which takes advantage of the optimized echo times to disambiguate the field offset value. Results We validate our method using high resolution images of a phantom at 7T. The resulting field maps demonstrate robust mapping over both a large dynamic range, and in low SNR regions. We also present high resolution offset maps in vivo using both, GRE and MEGE sequences. Even though the proposed echo time spacings are larger than the well known phase aliasing cutoff, the resulting field maps exhibit a large dynamic range without the use of phase unwrapping or spatial regularization techniques. Conclusion We demonstrate a novel 3-echo field map estimation method which overcomes the traditional noise-dynamic range trade-off. PMID:23401245

  7. Topographical estimation of visual population receptive fields by FMRI.

    Science.gov (United States)

    Lee, Sangkyun; Papanikolaou, Amalia; Keliris, Georgios A; Smirnakis, Stelios M

    2015-02-03

    Visual cortex is retinotopically organized so that neighboring populations of cells map to neighboring parts of the visual field. Functional magnetic resonance imaging allows us to estimate voxel-based population receptive fields (pRF), i.e., the part of the visual field that activates the cells within each voxel. Prior, direct, pRF estimation methods(1) suffer from certain limitations: 1) the pRF model is chosen a-priori and may not fully capture the actual pRF shape, and 2) pRF centers are prone to mislocalization near the border of the stimulus space. Here a new topographical pRF estimation method(2) is proposed that largely circumvents these limitations. A linear model is used to predict the Blood Oxygen Level-Dependent (BOLD) signal by convolving the linear response of the pRF to the visual stimulus with the canonical hemodynamic response function. PRF topography is represented as a weight vector whose components represent the strength of the aggregate response of voxel neurons to stimuli presented at different visual field locations. The resulting linear equations can be solved for the pRF weight vector using ridge regression(3), yielding the pRF topography. A pRF model that is matched to the estimated topography can then be chosen post-hoc, thereby improving the estimates of pRF parameters such as pRF-center location, pRF orientation, size, etc. Having the pRF topography available also allows the visual verification of pRF parameter estimates allowing the extraction of various pRF properties without having to make a-priori assumptions about the pRF structure. This approach promises to be particularly useful for investigating the pRF organization of patients with disorders of the visual system.

  8. Analytical estimation of the Earth's magnetic field scale

    CERN Document Server

    Bologna, Mauro

    2012-01-01

    In this paper we analytically estimate the magnetic field scale of planets with physical core conditions similar to that of Earth from a statistical point of view. We evaluate the magnetic field on the basis of the physical parameters of the center of the planet, such as density, temperature, and core size. We look at the contribution of the Peltier-Seebeck effect on the magnetic field, showing that an electrical thermal current can exist in a rotating fluid sphere. Finally, we apply our calculations to Earth and Jupiter. In each case we show that the thermal generation of currents leads to a magnetic field scale comparable to the observed fields of the two planets.

  9. Estimate of Coronal Magnetic Field Strength Using Plasmoid Acceleration Measurement

    Science.gov (United States)

    Choe, G.; Lee, K.; Jang, M.

    2010-12-01

    A method of estimating the lower bound of coronal magnetic field strength in the neighborhood of an ejecting plasmoid is presented. Based on the assumption that the plasma ejecta is within a magnetic island, an analytical expression for the force acting on the ejecta is derived. A rather simple calculation shows that the vertical force acting on a cylinder-like volume, whose lateral surface is a flux surface and whose magnetic axis is parallel to the horizontal, is just the difference in total pressure (magnetic pressure plus plasma pressure) below and above the volume. The method is applied to a limb coronal mass ejection event, and a lower bound of the magnetic field strength just below the CME core is estimated. The method is expected to provide useful information on the strength of reconnecting magnetic field if applied to X-ray plasma ejecta.

  10. Inhibitory Interactions between BK and JC Virus among Kidney Transplant Recipients

    Science.gov (United States)

    Cheng, Xingxing S.; Bohl, Daniel L.; Storch, Gregory A.; Ryschkewitsch, Caroline; Gaudreault-Keener, Monique; Major, Eugene O.; Randhawa, Parmjeet; Hardinger, Karen L.

    2011-01-01

    BK and JC polyomaviruses can reactivate after transplantation, causing renal dysfunction and graft loss. The incidence of JC reactivation after renal transplant is not well understood. Here, we characterized JC reactivation using samples collected during the first year after transplantation from 200 kidney recipients. We detected BK and JC viruses in the urine of 35 and 16% of transplant recipients, respectively. The median viral load in the urine was 400 times higher for BK virus than JC virus. The presence of BK viruria made concurrent JC viruria less likely: JC viruria was detected in 22% of non-BK viruric recipients compared with 4% of BK viruric recipients (P = 0.001). The co-detection rate was 1.5%, which is less than the expected 5.6% if reactivation of each virus was independent (P = 0.001). We did not observe JC viremia, JC nephropathy, or progressive multifocal leukoencephalopathy. The onset of JC viruria was associated with donor, but not recipient, JC-specific antibody in a titer-dependent fashion and inversely associated with donor and recipient BK-specific antibody. Donor and recipient JC seropositivity did not predict BK viruria or viremia. In conclusion, among renal transplant recipients, infection with one polyomavirus inversely associates with infection with the other. PMID:21511831

  11. JC Polyomavirus (JCV and Monoclonal Antibodies: Friends or Potential Foes?

    Directory of Open Access Journals (Sweden)

    Roberta Antonia Diotti

    2013-01-01

    Full Text Available Progressive multifocal leukoencephalopathy (PML is a demyelinating disease of the central nervous system (CNS, observed in immunodeficient patients and caused by JC virus ((JCV, also called JC polyomavirus (JCPyV. After the HIV pandemic and the introduction of immunomodulatory therapy, the PML incidence significantly increased. The correlation between the use of natalizumab, a drug used in multiple sclerosis (MS, and the PML development of particular relevance. The high incidence of PML in natalizumab-treated patients has highlighted the importance of two factors: the need of PML risk stratification among natalizumab-treated patients and the need of effective therapeutic options. In this review, we discuss these two needs under the light of the major viral models of PML etiopathogenesis.

  12. A Comprehensive Method of Estimating Electric Fields from Vector Magnetic Field and Doppler Measurements

    CERN Document Server

    Kazachenko, Maria D; Welsch, Brian T

    2014-01-01

    Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal (PTD) decomposition of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the "{\\bf P}TD-{\\bf D}oppler-{\\bf F}LCT {\\bf I}deal" (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the \\texttt{FISHPACK} software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (\\te...

  13. Challenges in estimating insecticide selection pressures from mosquito field data.

    Directory of Open Access Journals (Sweden)

    Susana Barbosa

    2011-11-01

    Full Text Available Insecticide resistance has the potential to compromise the enormous effort put into the control of dengue and malaria vector populations. It is therefore important to quantify the amount of selection acting on resistance alleles, their contributions to fitness in heterozygotes (dominance and their initial frequencies, as a means to predict the rate of spread of resistance in natural populations. We investigate practical problems of obtaining such estimates, with particular emphasis on Mexican populations of the dengue vector Aedes aegypti. Selection and dominance coefficients can be estimated by fitting genetic models to field data using maximum likelihood (ML methodology. This methodology, although widely used, makes many assumptions so we investigated how well such models perform when data are sparse or when spatial and temporal heterogeneity occur. As expected, ML methodologies reliably estimated selection and dominance coefficients under idealised conditions but it was difficult to recover the true values when datasets were sparse during the time that resistance alleles increased in frequency, or when spatial and temporal heterogeneity occurred. We analysed published data on pyrethroid resistance in Mexico that consists of the frequency of a Ile1,016 mutation. The estimates for selection coefficient and initial allele frequency on the field dataset were in the expected range, dominance coefficient points to incomplete dominance as observed in the laboratory, although these estimates are accompanied by strong caveats about possible impact of spatial and temporal heterogeneity in selection.

  14. Time Series Vegetation Aerodynamic Roughness Fields Estimated from MODIS Observations

    Science.gov (United States)

    Borak, Jordan S.; Jasinski, Michael F.; Crago, Richard D.

    2005-01-01

    Most land surface models used today require estimates of aerodynamic roughness length in order to characterize momentum transfer between the surface and atmosphere. The most common method of prescribing roughness is through the use of empirical look-up tables based solely on land cover class. Theoretical approaches that employ satellite-based estimates of canopy density present an attractive alternative to current look-up table approaches based on vegetation cover type that do not account for within-class variability and are oftentimes simplistic with respect to temporal variability. The current research applies Raupach s formulation of momentum aerodynamic roughness to MODIS data on a regional scale in order to estimate seasonally variable roughness and zero-plane displacement height fields using bulk land cover parameters estimated by [Jasinski, M.F., Borak, J., Crago, R., 2005. Bulk surface momentum parameters for satellite-derived vegetation fields. Agric. For. Meteorol. 133, 55-68]. Results indicate promising advances over look-up approaches with respect to characterization of vegetation roughness variability in land surface and atmospheric circulation models.

  15. Estimating Canopy Nitrogen Concentration in Sugarcane Using Field Imaging Spectroscopy

    Directory of Open Access Journals (Sweden)

    Marc Souris

    2012-06-01

    Full Text Available The retrieval of nutrient concentration in sugarcane through hyperspectral remote sensing is widely known to be affected by canopy architecture. The goal of this research was to develop an estimation model that could explain the nitrogen variations in sugarcane with combined cultivars. Reflectance spectra were measured over the sugarcane canopy using a field spectroradiometer. The models were calibrated by a vegetation index and multiple linear regression. The original reflectance was transformed into a First-Derivative Spectrum (FDS and two absorption features. The results indicated that the sensitive spectral wavelengths for quantifying nitrogen content existed mainly in the visible, red edge and far near-infrared regions of the electromagnetic spectrum. Normalized Differential Index (NDI based on FDS(750/700 and Ratio Spectral Index (RVI based on FDS(724/700 are best suited for characterizing the nitrogen concentration. The modified estimation model, generated by the Stepwise Multiple Linear Regression (SMLR technique from FDS centered at 410, 426, 720, 754, and 1,216 nm, yielded the highest correlation coefficient value of 0.86 and Root Mean Square Error of the Estimate (RMSE value of 0.033%N (n = 90 with nitrogen concentration in sugarcane. The results of this research demonstrated that the estimation model developed by SMLR yielded a higher correlation coefficient with nitrogen content than the model computed by narrow vegetation indices. The strong correlation between measured and estimated nitrogen concentration indicated that the methods proposed in this study could be used for the reliable diagnosis of nitrogen quantity in sugarcane. Finally, the success of the field spectroscopy used for estimating the nutrient quality of sugarcane allowed an additional experiment using the polar orbiting hyperspectral data for the timely determination of crop nutrient status in rangelands without any requirement of prior

  16. Cortico-Cortical Receptive Field Estimates in Human Visual Cortex

    Directory of Open Access Journals (Sweden)

    Koen V Haak

    2012-05-01

    Full Text Available Human visual cortex comprises many visual areas that contain a map of the visual field (Wandell et al 2007, Neuron 56, 366–383. These visual field maps can be identified readily in individual subjects with functional magnetic resonance imaging (fMRI during experimental sessions that last less than an hour (Wandell and Winawer 2011, Vis Res 718–737. Hence, visual field mapping with fMRI has been, and still is, a heavily used technique to examine the organisation of both normal and abnormal human visual cortex (Haak et al 2011, ACNR, 11(3, 20–21. However, visual field mapping cannot reveal every aspect of human visual cortex organisation. For example, the information processed within a visual field map arrives from somewhere and is sent to somewhere, and visual field mapping does not derive these input/output relationships. Here, we describe a new, model-based analysis for estimating the dependence between signals in distinct cortical regions using functional magnetic resonance imaging (fMRI data. Just as a stimulus-referred receptive field predicts the neural response as a function of the stimulus contrast, the neural-referred receptive field predicts the neural response as a function of responses elsewhere in the nervous system. When applied to two cortical regions, this function can be called the cortico-cortical receptive field (CCRF. We model the CCRF as a Gaussian-weighted region on the cortical surface and apply the model to data from both stimulus-driven and resting-state experimental conditions in visual cortex.

  17. Estimating signal loss in regularized GRACE gravity field solutions

    Science.gov (United States)

    Swenson, S. C.; Wahr, J. M.

    2011-05-01

    Gravity field solutions produced using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are subject to errors that increase as a function of increasing spatial resolution. Two commonly used techniques to improve the signal-to-noise ratio in the gravity field solutions are post-processing, via spectral filters, and regularization, which occurs within the least-squares inversion process used to create the solutions. One advantage of post-processing methods is the ability to easily estimate the signal loss resulting from the application of the spectral filter by applying the filter to synthetic gravity field coefficients derived from models of mass variation. This is a critical step in the construction of an accurate error budget. Estimating the amount of signal loss due to regularization, however, requires the execution of the full gravity field determination process to create synthetic instrument data; this leads to a significant cost in computation and expertise relative to post-processing techniques, and inhibits the rapid development of optimal regularization weighting schemes. Thus, while a number of studies have quantified the effects of spectral filtering, signal modification in regularized GRACE gravity field solutions has not yet been estimated. In this study, we examine the effect of one regularization method. First, we demonstrate that regularization can in fact be performed as a post-processing step if the solution covariance matrix is available. Regularization then is applied as a post-processing step to unconstrained solutions from the Center for Space Research (CSR), using weights reported by the Centre National d'Etudes Spatiales/Groupe de Recherches de geodesie spatiale (CNES/GRGS). After regularization, the power spectra of the CSR solutions agree well with those of the CNES/GRGS solutions. Finally, regularization is performed on synthetic gravity field solutions derived from a land surface model, revealing that in

  18. The Development and Application of the JC - 15D Direct Drive Drawworks%JC-15D直驱绞车的研制及应用

    Institute of Scientific and Technical Information of China (English)

    杨元东; 马树学; 安青龙; 张国良

    2012-01-01

    The JC -15D drawworks developed mainly consists of jack frame, drum shaft, 320 kW motor, hydraulic disc brake, electric control system and lubrication system. The motor transmits power to the drum shaft through the coupling in a synchronous way. The overall variable speed process of the drawworks is completely achieved by the AC variable frequency control system. The advanced low-speed high-torque permanent magnet motor is adopted to drive the drum shaft directly. As a result, the drawworks structure is simplified remarkably and its mass is reduced, the transmission efficiency is improved, and the precise control of super-low speed continuously variable transmission is achieved. The field application has reached desirable efthcts.%研制的JC-15D绞车主要由绞车架、滚筒轴、320kW电动机、液压盘式刹车、电气控制系统和润滑系统等组成。该绞车采用主电动机直接驱动滚筒轴,整个变速过程完全由主电动机交流变频控制系统操作实现,具有提升和下放钻具、取心和处理事故等功能;主电机还可实现恒钻速或恒钻压自动送钻,主刹车采用主电动机能耗制动,辅助刹车采用液压盘式刹车。试验情况表明,在井架上段的起升和下放及正常钻井过程中绞车运行平稳,润滑充分,密封及连接可靠;主电动机连续调速、能耗制动减速及零速悬停功能良好,主电动机恒钻压(恒钻速)自动送钻速度和扭矩能满足钻井工艺要求;滚筒缠绳整齐有序;液压辅助刹车灵敏可靠。截止到2011年7月5日,JC-15D绞车已无故障累计运行700h。

  19. Bayesian parameter estimation for chiral effective field theory

    Science.gov (United States)

    Wesolowski, Sarah; Furnstahl, Richard; Phillips, Daniel; Klco, Natalie

    2016-09-01

    The low-energy constants (LECs) of a chiral effective field theory (EFT) interaction in the two-body sector are fit to observable data using a Bayesian parameter estimation framework. By using Bayesian prior probability distributions (pdfs), we quantify relevant physical expectations such as LEC naturalness and include them in the parameter estimation procedure. The final result is a posterior pdf for the LECs, which can be used to propagate uncertainty resulting from the fit to data to the final observable predictions. The posterior pdf also allows an empirical test of operator redundancy and other features of the potential. We compare results of our framework with other fitting procedures, interpreting the underlying assumptions in Bayesian probabilistic language. We also compare results from fitting all partial waves of the interaction simultaneously to cross section data compared to fitting to extracted phase shifts, appropriately accounting for correlations in the data. Supported in part by the NSF and DOE.

  20. Revisiting Boltzmann learning: parameter estimation in Markov random fields

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Andersen, Lars Nonboe; Kjems, Ulrik

    1996-01-01

    This article presents a generalization of the Boltzmann machine that allows us to use the learning rule for a much wider class of maximum likelihood and maximum a posteriori problems, including both supervised and unsupervised learning. Furthermore, the approach allows us to discuss regularization...... and generalization in the context of Boltzmann machines. We provide an illustrative example concerning parameter estimation in an inhomogeneous Markov field. The regularized adaptation produces a parameter set that closely resembles the “teacher” parameters, hence, will produce segmentations that closely reproduce...

  1. Two Field Techniques for Estimating Relative Abundance of Galliformes

    Institute of Scientific and Technical Information of China (English)

    LuXin; CangjueZhuoma; SuolongCiren; ZhengGuang-mei

    2003-01-01

    Galliformes are often difficult to count adequately in their natural habitats due to low detectability of them. In the present study, we confirm availability of feather-count and feces-count as two useful field techniques to estimate the relative abundance of eared pheasants (Crossoptilon spp. ). The former is suitable to forest environments during the post-incubation period, whereas the latter is best in areas with dry climate conditions during the fall winter season. With the advantages of reduced survey effort and high repeatability, the two techniques are potentially applicable to other Galliform species in habitat selection studies and long-term population monitoring.

  2. Estimation of probability densities using scale-free field theories.

    Science.gov (United States)

    Kinney, Justin B

    2014-07-01

    The question of how best to estimate a continuous probability density from finite data is an intriguing open problem at the interface of statistics and physics. Previous work has argued that this problem can be addressed in a natural way using methods from statistical field theory. Here I describe results that allow this field-theoretic approach to be rapidly and deterministically computed in low dimensions, making it practical for use in day-to-day data analysis. Importantly, this approach does not impose a privileged length scale for smoothness of the inferred probability density, but rather learns a natural length scale from the data due to the tradeoff between goodness of fit and an Occam factor. Open source software implementing this method in one and two dimensions is provided.

  3. Estimate of the maximum induced magnetic field in relativistic shocks

    Science.gov (United States)

    Ghorbanalilu, M.; Sadegzadeh, S.

    2017-01-01

    The proton-driven Weibel instability is a crucial process for amplifying the generated magnetic fields in gamma-ray bursts. An expression for the saturation level of magnetic fields is estimated in a relativistic shock consisting of electron-proton plasmas. Within the shock transition layer, the plasma is modelled with the waterbag and Maxwell-Jüttner distribution functions for asymmetric counter-propagating proton beams and isotropic background electrons, respectively. The proton-driven Weibel-type instability in the linear phase is investigated thoroughly and then the instability conditions and the stabilization mechanisms are considered in details just after the shutdown of the electron Weibel instability. The growth rate of the instability and the saturated magnetic field strength are obtained in terms of the effective proton beam Mach number, asymmetry parameter, and the background electron temperature. In this paper, fully relativistic kinetic treatment is used to formulate the dispersion relation for the proton Weibel-type instability. Then, by using the magnetic trapping criteria, the saturated magnetic field strength is computed. In the present scenario, the instability includes two stages: in the first stage the electron Weibel instability evolves very rapidly, but in the second one because of the free energy stored in the slow counter-propagating proton beams, the instability is further amplified in the context of electrons with an isotropic distribution function. Increment of the growth rate and saturated magnetic field by increasing (decreasing) the effective proton beam Mach number (the asymmetry parameter) is deduced from the results. It is shown that at the temperatures around 108 K a maximum magnetic field up to around 56 G can be detected by this mechanism after the saturation time.

  4. Homomorphisms between JC*-algebras and Lie C*-algebras

    Institute of Scientific and Technical Information of China (English)

    Chun Gil PARK; Jin Chuan HOU; Sei Qwon OH

    2005-01-01

    It is shown that every almost *-homomorphism h: A → B of a unital JC*-algebra A to a unital JC*-algebra B is a *-homomorphism when h(rx) = rh(x) (r > 1) for all x ∈ A, and that every almost linear mapping h: A → B is a *-homomorphism when h(2nu o y) = h(2nu) o h(y),h(3nu o y) = h(3nu) o h(y) or h(qnu o y) = h(qnu) o h(y) for all unitaries u ∈ A, all y ∈ A, and n = 0, 1, Here the numbers 2, 3, q depend on the functional equations given in the almost linear mappings.We prove that every almost *-homomorphism h: A → B of a unital Lie C*-algebra A to a unital Lie C*-algebra B is a *-homomorphism when h(rx) = rh(x) (r > 1) for all x ∈ A.

  5. Quantum Galileo's experiments and mass estimation in a gravitational field

    CERN Document Server

    Seveso, Luigi; Paris, Matteo G A

    2016-01-01

    We address the problem of estimating the mass of a (quantum) particle interacting with a classical gravitational field. In particular, we analyze in details the ultimate bounds to precision imposed by quantum mechanics and study the effects of gravity in a variety of settings. Our results show that the presence of a gravitational field generally leads to a precision gain, which can be significant in a regime half-way between the quantum and classical domains. We also address quantum enhancement to precision, i.e. the advantages coming from taking into account the quantum nature of the probe particle, and show that non-classicality is indeed a relevant resource for mass estimation. In particular, we suggest schemes for mass-sensing measurements using quantum probes and show that upon employing non-classical states like quantum coherent superpositions one may improve precisions by orders of magnitude. In addition, we discuss the compatibility of the weak equivalence principle (WEP) within the quantum regime usi...

  6. Estimation of field capacity from ring infiltrometer-drainage data

    Directory of Open Access Journals (Sweden)

    Theophilo Benedicto Ottoni Filho

    2014-12-01

    Full Text Available Field capacity (FC is a parameter widely used in applied soil science. However, its in situ method of determination may be difficult to apply, generally because of the need of large supplies of water at the test sites. Ottoni Filho et al. (2014 proposed a standardized procedure for field determination of FC and showed that such in situ FC can be estimated by a linear pedotransfer function (PTF based on volumetric soil water content at the matric potential of -6 kPa [θ(6] for the same soils used in the present study. The objective of this study was to use soil moisture data below a double ring infiltrometer measured 48 h after the end of the infiltration test in order to develop PTFs for standard in situ FC. We found that such ring FC data were an average of 0.03 m³ m- 3 greater than standard FC values. The linear PTF that was developed for the ring FC data based only on θ(6 was nearly as accurate as the equivalent PTF reported by Ottoni Filho et al. (2014, which was developed for the standard FC data. The root mean squared residues of FC determined from both PTFs were about 0.02 m³ m- 3. The proposed method has the advantage of estimating the soil in situ FC using the water applied in the infiltration test.

  7. Improving the estimation of complete field soil water characteristic curves through field monitoring data

    Science.gov (United States)

    Bordoni, M.; Bittelli, M.; Valentino, R.; Chersich, S.; Meisina, C.

    2017-09-01

    In this work, Soil Water Characteristic Curves (SWCCs) were reconstructed through simultaneous field measurements of soil pore water pressure and water content. The objective was to evaluate whether field-based monitoring can allow for the improvement of the accuracy in SWCCs estimation with respect to the use of laboratory techniques. Moreover, field assessment of SWCCs allowed to: a) quantify the hydrological hysteresis affecting SWCCs through field data; b) analyze the effect of different temporal resolution of field measures; c) highlight the differences in SWCCs reconstructed for a particular soil during different hydrological years; d) evaluate the reliability of field reconstructed SWCCs, by the comparison between assessed and measured trends of a component of the soil water balance. These aspects were fundamental for assessing the reliability of the field reconstructed SWCCs. Field data at two Italian test-sites were measured. These test-sites were used to evaluate the goodness of field reconstructed SWCCs for soils characterized by different geomorphological, geological, physical and pedological features. Field measured or laboratory measured SWCCs data of 5 soil horizons (3 in a predominantly silty soil, 2 in a predominantly clayey one) were fitted by Van Genuchten model. Different field drying and wetting periods were identified, based on monthly meteorological conditions, in terms of rainfall and evapotranspiration amounts, of different cycles. This method allowed for a correct discrimination of the main drying and the main wetting paths from field data related and for a more reliable quantification of soil hydrological properties with respect to laboratory methodologies. Particular patterns of changes in SWCCs forms along depth could be also identified. Field SWCCs estimation is not affected by the temporal resolution of the acquisition (hours or days), as testified by similar values of Van Genuchten equation fitting parameters. Instead, hourly data

  8. A comprehensive method of estimating electric fields from vector magnetic field and Doppler measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T., E-mail: kazachenko@ssl.berkeley.edu [Space Sciences Laboratory, UC Berkeley, CA 94720 (United States)

    2014-11-01

    Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal decomposition (PTD) of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the 'PTD-Doppler-FLCT Ideal' (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the FISHPACK software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (ANMHD) simulations, which have been used in similar tests in the past. We find that the PDFI method has less than 1% error in the total Poynting flux and a 10% error in the helicity flux rate at a normal viewing angle (θ = 0) and less than 25% and 10% errors, respectively, at large viewing angles (θ < 60°). We compare our results with other inversion methods at zero viewing angle and find that our method's estimates of the fluxes of magnetic energy and helicity are comparable to or more accurate than other methods. We also discuss the limitations of the PDFI method and its uncertainties.

  9. Two Field Techniques for Estimating Relative Abundance of Galliformes

    Institute of Scientific and Technical Information of China (English)

    Lu Xin; Cangjue Zhuoma; Suolong Ciren; Zheng Guang-mei

    2003-01-01

    Galliformes are often difficult to count adequate-ly in their natural habitats due to low detectability of them. In the present study, we confirm availability of feather-count and feces-count as two useful field techniques to estimate the rela-tive abundance of eared-pheasants (Crossoptilon spp. ). The former is suitable to forest environments during the post-incu-bation period, whereas the latter is best in areas with dry cli-mate conditions during the fall-winter season. With the ad-vantages of reduced survey effort and high repeatability, the two techniques are potentially applicable to other Galliform species in habitat selection studies and long-term population monitoring.

  10. Comparison of two field tests to estimate maximum aerobic speed.

    Science.gov (United States)

    Berthoin, S; Gerbeaux, M; Turpin, E; Guerrin, F; Lensel-Corbeil, G; Vandendorpe, F

    1994-08-01

    The measurement of maximal aerobic speed (MAS) and the prediction of maximal oxygen uptake (VO2 max) by means of field tests were carried out on 17 students studying physical education. The subjects underwent a continuous multi-stage track test (Léger and Boucher, 1980), shuttle test (Léger et al., 1984) and VO2 max measurement on a treadmill. The VO2 max values estimated using the track test (56.8 +/- 5.8 ml kg-1 min-1) were not significantly different from the values measured in the treadmill test (56.8 +/- 7.1 ml kg-1 min-1), but were higher than those estimated using the shuttle test (51.1 +/- 5.9 ml kg-1 min-1). The maximal nature of the tests was checked by measurement of heart rate and lactate concentration, taken within 2 min post-test. The means of the MAS observed in the track test (15.8 +/- 1.9 km h-1) and in the treadmill test (15.9 +/- 2.6 km h-1) were not significantly different (P > 0.10). The mean of the shuttle test MAS (13.1 +/- 1 km h-1) was significantly lower (P < 0.01) than those of the other tests. However, the MAS of the shuttle test and track test are linked. The equation for linear regression between MAS values in these two tests is MAStrack = 1.81 x MASshuttle -7.86 (r = 0.91), allowing estimation of one of these MAS values when the other is known. Thus these values may be used within diversified training.

  11. Pharmacological cdk inhibitor R-Roscovitine suppresses JC virus proliferation.

    Science.gov (United States)

    Orba, Yasuko; Sunden, Yuji; Suzuki, Tadaki; Nagashima, Kazuo; Kimura, Takashi; Tanaka, Shinya; Sawa, Hirofumi

    2008-01-05

    The human Polyomavirus JC virus (JCV) utilizes cellular proteins for viral replication and transcription in the host cell nucleus. These cellular proteins represent potential targets for antiviral drugs against the JCV. In this study, we examined the antiviral effects of the pharmacological cyclin-dependent kinase (cdk) inhibitor R-Roscovitine, which has been shown to have antiviral activity against other viruses. We found that Roscovitine significantly inhibited the viral production and cytopathic effects of the JCV in a JCV-infected cell line. Roscovitine attenuated the transcriptional activity of JCV late genes, but not early genes, and also prevented viral replication via inhibiting phosphorylation of the viral early protein, large T antigen. These data suggest that the JCV requires cdks to transcribe late genes and to replicate its own DNA. That Roscovitine exhibited antiviral activity in JCV-infected cells suggests that Roscovitine might have therapeutic utility in the treatment of progressive multifocal leukoencephalopathy (PML).

  12. Magnetic Field Feature Extraction and Selection for Indoor Location Estimation

    Directory of Open Access Journals (Sweden)

    Carlos E. Galván-Tejada

    2014-06-01

    Full Text Available User indoor positioning has been under constant improvement especially with the availability of new sensors integrated into the modern mobile devices, which allows us to exploit not only infrastructures made for everyday use, such as WiFi, but also natural infrastructure, as is the case of natural magnetic field. In this paper we present an extension and improvement of our current indoor localization model based on the feature extraction of 46 magnetic field signal features. The extension adds a feature selection phase to our methodology, which is performed through Genetic Algorithm (GA with the aim of optimizing the fitness of our current model. In addition, we present an evaluation of the final model in two different scenarios: home and office building. The results indicate that performing a feature selection process allows us to reduce the number of signal features of the model from 46 to 5 regardless the scenario and room location distribution. Further, we verified that reducing the number of features increases the probability of our estimator correctly detecting the user’s location (sensitivity and its capacity to detect false positives (specificity in both scenarios.

  13. Nanorod Self-Assembly in High Jc YBa2Cu3O7−x Films with Ru-Based Double Perovskites

    Directory of Open Access Journals (Sweden)

    Javier F. Baca

    2011-11-01

    Full Text Available Many second phase additions to YBa2Cu3O7−x (YBCO films, in particular those that self-assemble into aligned nanorod and nanoparticle structures, enhance performance in self and applied fields. Of particular interest for additions are Ba-containing perovskites that are compatible with YBCO. In this report, we discuss the addition of Ba2YRuO6 to bulk and thick-film YBCO. Sub-micron, randomly oriented particles of this phase were found to form around grain boundaries and within YBCO grains in bulk sintered pellets. Within the limits of EDS, no Ru substitution into the YBCO was observed. Thick YBCO films were grown by pulsed laser deposition from a target consisting of YBa2Cu3Oy with 5 and 2.5 mole percent additions of Ba2YRuO6 and Y2O3, respectively. Films with enhanced in-field performance contained aligned, self-assembled Ba2YRuO6 nanorods and strained Y2O3 nanoparticle layers. A 0.9 µm thick film was found to have a self-field critical current density (Jc of 5.1 MA/cm2 with minimum Jc(Q, H=1T of 0.75 MA/cm2. Conversely, Jc characteristics were similar to YBCO films without additions when these secondary phases formed as large, disordered phases within the film. A 2.3 µm thick film with such a distribution of secondary phases was found to have reduced self-field Jc values of 3.4 MA/cm2 at 75.5 K and Jc(min, Q, 1T of 0.4 MA/cm2.

  14. Hot pressing to enhance the transport Jc of Sr0.6K0.4Fe2As2 superconducting tapes

    Science.gov (United States)

    Lin, He; Yao, Chao; Zhang, Xianping; Dong, Chiheng; Zhang, Haitao; Wang, Dongliang; Zhang, Qianjun; Ma, Yanwei; Awaji, Satoshi; Watanabe, Kazuo; Tian, Huanfang; Li, Jianqi

    2014-01-01

    High-performance Sr0.6K0.4Fe2As2 (Sr-122) tapes have been successfully fabricated using hot pressing (HP) process. The effect of HP temperatures (850–925°C) on the c-axis texture, resistivity, Vickers micro-hardness, microstructure and critical current properties has been systematically studied. Taking advantage of high degree of c-axis texture, well grain connectivity and large concentration of strong-pinning defects, we are able to obtain an excellent Jc of 1.2 × 105 A/cm2 at 4.2 K and 10 T for Sr-122 tapes. More importantly, the field dependence of Jc turns out to be very weak, such that in 14 T the Jc still remains ~ 1.0 × 105 A/cm2. These Jc values are the highest ever reported so far for iron-pnictide wires and tapes, achieving the level desired for practical applications. Our results clearly strengthen the position of iron-pnictide conductors as a competitor to the conventional and MgB2 superconductors for high field applications. PMID:25374068

  15. Estimating magnetic field power spectrum using CRRES magnetometer data

    Science.gov (United States)

    Ali, A.; Elkington, S. R.

    2013-05-01

    Radial diffusion is one of the acceleration mechanisms responsible for populating and depleting the Van Allen radiation belts with high energy charged particles. We use the magnetometer data from the Combined Release and Radiation Effects Satellite (CRRES) to estimate the power spectral density in the compressional component of the geomagnetic field in the frequency range of 0.8mHz-16.3mHz. We see a clear dependence of power spectral density on radial distance L, measure of geomagnetic disturbance Kp, and magnetic local time. Comparing total integrated power, the noon sector contains more power with no significant difference between other sectors during periods of low activity. During high activity the dusk sector has significantly more power than dawn sector with the difference sometimes being an order of magnitude higher with power increasing slightly as we move radially outward to higher L-shells. We then recompute the power spectral density without local time dependence and compute the electromagnetic part of the radial diffusion coefficient. The electromagnetic diffusion coefficients are then compared with the electrostatic coefficients computed by Brautigam et al. (2005). The dependence of the diffusion coefficients is then studied on parameters of L, Kp, and the first invariant. For a fixed first invariant the diffusion coefficient can be up to two orders of magnitude higher as we move from the inner magnetosphere (L=3.5) to the outer magnetosphere (L=6.5). During high activity, radial diffusion is also significantly faster than at quiet times.

  16. Comparison of thermal aftereffect models for estimating the fluctuation field

    Energy Technology Data Exchange (ETDEWEB)

    Della Torre, E. [George Washington University, Washington, DC 20052 (United States)], E-mail: edt@gwu.edu; Bennett, L.H.; Korman, C.E. [George Washington University, Washington, DC 20052 (United States)

    2008-02-01

    The sigmoidal decay of the magnetization in log time, which is geometrically similar to the major loop, starts at the major loop and decays to the anhysteretic magnetization for a given holding field. The linear displacement of these curves after normalization with holding field can be used to compute the fluctuation field. This paper discusses the errors in computing this field.

  17. Estimating the plasmonic field enhancement using high-order harmonic generation: The role of inhomogeneity of the fields

    CERN Document Server

    Shaaran, T; Lewenstein, M

    2012-01-01

    In strong field laser physics it is a common practice to use the high-order harmonic cutoff to estimate the laser intensity of the pulse that generates the harmonic radiation. Based on the semiclassical arguments it is possible to find a direct relationship between the maximum value of the photon energy and the laser intensity. This approach is only valid if the electric field driving HHG is spatially homogenous. In laser-matter processes driven by plasmonics fields, the enhanced fields present a spatial dependence that strongly modifies the electron motion and consequently the laser driven phenomena. As a result, this method should be revised in order to more realistically estimate the field. In this work, we demonstrate how the inhomogeneity of the fields will effect this estimation. Furthermore, by employing both quantum mechanical and classical calculations, we show how one can obtain a better estimation for the intensity of the enhanced field in plasmonic nanostructure.

  18. JC polyomavirus mutants escape antibody-mediated neutralization.

    Science.gov (United States)

    Ray, Upasana; Cinque, Paola; Gerevini, Simonetta; Longo, Valeria; Lazzarin, Adriano; Schippling, Sven; Martin, Roland; Buck, Christopher B; Pastrana, Diana V

    2015-09-23

    JC polyomavirus (JCV) persistently infects the urinary tract of most adults. Under conditions of immune impairment, JCV causes an opportunistic brain disease, progressive multifocal leukoencephalopathy (PML). JCV strains found in the cerebrospinal fluid of PML patients contain distinctive mutations in surface loops of the major capsid protein, VP1. We hypothesized that VP1 mutations might allow the virus to evade antibody-mediated neutralization. Consistent with this hypothesis, neutralization serology revealed that plasma samples from PML patients neutralized wild-type JCV strains but failed to neutralize patient-cognate PML-mutant JCV strains. This contrasted with serological results for healthy individuals, most of whom robustly cross-neutralized all tested JCV variants. Mice administered a JCV virus-like particle (VLP) vaccine initially showed neutralizing "blind spots" (akin to those observed in PML patients) that closed after booster immunization. A PML patient administered an experimental JCV VLP vaccine likewise showed markedly increased neutralizing titer against her cognate PML-mutant JCV. The results indicate that deficient humoral immunity is a common aspect of PML pathogenesis and that vaccination may overcome this humoral deficiency. Thus, vaccination with JCV VLPs might prevent the development of PML.

  19. Receptive field organization across multiple electrosensory maps. I. Columnar organization and estimation of receptive field size.

    Science.gov (United States)

    Maler, Leonard

    2009-10-10

    The electric fish Apteronotus leptorhynchus emits a high-frequency electric organ discharge (EOD) sensed by specialized electroreceptors (P-units). Amplitude modulations (AMs) of the EOD are caused by objects such as prey as well as by social interactions with conspecifics. The firing rate of P-units is modulated by the AMs due to both objects and communication signals. P-units trifurcate as they enter the medulla; they terminate topographically with three maps of the electrosensory lateral line lobe (ELL): the centromedial (CMS), centrolateral (CLS), and lateral (LS) segments. Within each map P-units terminate onto the basal dendrites of pyramidal cells. Anterograde filling of P-units and retrograde filling of the basal bushes of pyramidal cells were used to estimate their respective spreads and spacing in the three maps. These estimates were used to compute the receptive field structure of the pyramidal cells: receptive fields were small in CMS and very large in LS with intermediate values in CLS. There are several classes of pyramidal cells defined by morphological and functional criteria; these cells are organized into columns such that each column contains one member of each class and all cells within a column receive the same P-unit input.

  20. An M-antibody capture radioimmunoassay (MACRIA) for detection of JC virus-specific IgM.

    Science.gov (United States)

    Knowles, W A; Gibson, P E; Hand, J F; Brown, D W

    1992-10-01

    A solid-phase M-antibody capture radioimmunoassay (MACRIA) for detecting JC-specific IgM is described. The assay is based on a JC-specific monoclonal antibody (17.7.6) and Nonidet P40-treated, glycine-extracted antigen. MACRIA is more sensitive for JC IgM detection than haemagglutination inhibition (HI) following serum fractionation on a sucrose density gradient, and can be applied to large numbers of sera. The specificity of the assay was confirmed by examining sera from several acute virus infections and also those containing rheumatoid factor. Sera collected from renal transplant recipients with known active JC virus infection were found to contain more than 5 units of JC IgM. In this group of patients JC IgM represents either primary or reactivated JC infection. JC IgM was detected by MACRIA in 15 of 100 unselected blood donors, indicating that JC IgM is frequently produced in healthy seropositive individuals. Thirteen of the 15 sera positive from blood donors contained only low levels of JC IgM (< 5 units), but the specificity of all these results was confirmed in a blocking assay. It is suggested that these low levels of JC IgM may occur in up to 28% of seropositive individuals and result from active JC antigenic stimulation in healthy immunocompetent adults.

  1. Estimation of Korean paddy field soil properties using optical reflectance

    Science.gov (United States)

    An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applie...

  2. Estimating the diffuseness of sound fields: A wavenumber analysis method

    DEFF Research Database (Denmark)

    Nolan, Melanie; Davy, John L.; Brunskog, Jonas

    2017-01-01

    The concept of a diffuse sound field is widely used in the analysis of sound in enclosures. The diffuse sound field is generally described as composed of plane waves with random phases, which wave number vectors are uniformly distributed over all angles of incidence. In this study......, an interpretation in the spatial frequency domain is discussed, with the prospect of evaluating the diffuse field conditions in non-anechoic enclosures. This work examines how theoretical considerations compare with experimental results obtained in rooms with various diffuse field conditions. In addition, the paper...

  3. Methods of gas hydrate concentration estimation with field examples

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, D.; Dash, R.; Dewangan, P.

    different methods of gas hydrate concentration estimation that make use of data from the measurements of the seismic properties, electrical resistivity, chlorinity, porosity, density, and temperature are summarized in this paper. We demonstrate the methods...

  4. Velocity field statistics and tessellation techniques : Unbiased estimators of Omega

    NARCIS (Netherlands)

    Van de Weygaert, R; Bernardeau, F; Muller,; Gottlober, S; Mucket, JP; Wambsganss, J

    1998-01-01

    We describe two new - stochastic-geometrical - methods to obtain reliable velocity field statistics from N-body simulations and from any general density and velocity fluctuation field sampled at a discrete set of locations. These methods, the Voronoi tessellation method and Delaunay tessellation met

  5. Estimating of pulsed electric fields using optical measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Timothy McGuire; Chantler, Gary.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  6. Adaptive mutations in the JC virus protein capsid are associated with progressive multifocal leukoencephalopathy (PML.

    Directory of Open Access Journals (Sweden)

    Shamil R Sunyaev

    2009-02-01

    Full Text Available PML is a progressive and mostly fatal demyelinating disease caused by JC virus infection and destruction of infected oligodendrocytes in multiple brain foci of susceptible individuals. While JC virus is highly prevalent in the human population, PML is a rare disease that exclusively afflicts only a small percentage of immunocompromised individuals including those affected by HIV (AIDS or immunosuppressive drugs. Viral- and/or host-specific factors, and not simply immune status, must be at play to account for the very large discrepancy between viral prevalence and low disease incidence. Here, we show that several amino acids on the surface of the JC virus capsid protein VP1 display accelerated evolution in viral sequences isolated from PML patients but not in sequences isolated from healthy subjects. We provide strong evidence that at least some of these mutations are involved in binding of sialic acid, a known receptor for the JC virus. Using statistical methods of molecular evolution, we performed a comprehensive analysis of JC virus VP1 sequences isolated from 55 PML patients and 253 sequences isolated from the urine of healthy individuals and found that a subset of amino acids found exclusively among PML VP1 sequences is acquired via adaptive evolution. By modeling of the 3-D structure of the JC virus capsid, we showed that these residues are located within the sialic acid binding site, a JC virus receptor for cell infection. Finally, we go on to demonstrate the involvement of some of these sites in receptor binding by demonstrating a profound reduction in hemagglutination properties of viral-like particles made of the VP1 protein carrying these mutations. Collectively, these results suggest that a more virulent PML causing phenotype of JC virus is acquired via adaptive evolution that changes viral specificity for its cellular receptor(s.

  7. Pinning features of the magnetic flux trapped by YBCO single crystals in weak constant magnetic fields

    Science.gov (United States)

    Monarkha, V. Yu.; Paschenko, V. A.; Timofeev, V. P.

    2013-02-01

    The dynamics of Abrikosov vortices and their bundles was experimentally investigated in weak constant magnetic fields, in the range of Earth's magnetic field. Characteristics of the isothermal magnetization relaxation in YBCO single-crystal samples with strong pinning centers were studied for different sample-field orientation. The obtained values of normalized relaxation rate S allowed us to estimate the effective pinning potential U in the bulk of the YBCO sample and its temperature dependence, as well as the critical current density Jc. A comparison between the data obtained and the results of similar measurements in significantly higher magnetic fields was performed. To compare different techniques for evaluation of Jc, the magnetization loop measurements M(H), which relate the loop width to the critical current, were carried out. These measurements provided important parameters of the samples under study (penetration field Hp and first critical field Hc1), which involve the geometrical configuration of the samples.

  8. Estimating relic magnetic fields from CMB temperature correlations

    CERN Document Server

    Giovannini, Massimo

    2009-01-01

    The temperature and polarization inhomogeneities of the Cosmic Microwave Background might bear the mark of pre-decoupling magnetism. The parameters of a putative magnetized background are hereby estimated from the observed temperature autocorrelation as well as from the measured temperature-polarization cross-correlation.

  9. Automatic Pain Intensity Estimation using Heteroscedastic Conditional Ordinal Random Fields

    NARCIS (Netherlands)

    Rudovic, Ognjen; Pavlovic, Vladimir; Pantic, Maja

    2013-01-01

    Automatic pain intensity estimation from facial images is challenging mainly because of high variability in subject-specific pain expressiveness. This heterogeneity in the subjects causes their facial appearance to vary significantly when experiencing the same pain level. The standard classification

  10. Neural Conditional Ordinal Random Fields for Agreement Level Estimation

    NARCIS (Netherlands)

    Rakicevic, Nemanja; Rudovic, Ognjen; Petridis, Stavros; Rakicevic, N.; Rudovic, O.; Petrids, S.; Pantic, Maja

    2015-01-01

    We present a novel approach to automated estimation of agreement intensity levels from facial images. To this end, we employ the MAHNOB Mimicry database of subjects recorded during dyadic interactions, where the facial images are annotated in terms of agreement intensity levels using the Likert scal

  11. Automatic Pain Intensity Estimation using Heteroscedastic Conditional Ordinal Random Fields

    NARCIS (Netherlands)

    Rudovic, Ognjen; Pavlovic, Vladimir; Pantic, Maja

    Automatic pain intensity estimation from facial images is challenging mainly because of high variability in subject-specific pain expressiveness. This heterogeneity in the subjects causes their facial appearance to vary significantly when experiencing the same pain level. The standard classification

  12. Effect of Visual Field Presentation on Action Planning (Estimating Reach) in Children

    Science.gov (United States)

    Gabbard, Carl; Cordova, Alberto

    2012-01-01

    In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all…

  13. Theorems on Estimating Perturbative Coefficients in Quantum Field Theory and Statistical Physics

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Mark

    2003-06-25

    The authors present rigorous proofs for several theorems on using Pade approximants to estimate coefficients in Perturbative Quantum Field Theory and Statistical Physics. As a result, they find new trigonometric and other identities where the estimates based on this approach are exact. They discuss hypergeometric functions, as well as series from both Perturbative Quantum Field Theory and Statistical Physics.

  14. The DTFE public software: The Delaunay Tessellation Field Estimator code

    NARCIS (Netherlands)

    Cautun, Marius C.; van de Weygaert, Rien

    2011-01-01

    We present the DTFE public software, a code for reconstructing fields from a discrete set of samples/measurements using the maximum of information contained in the point distribution. The code is written in C++ using the CGAL library and is parallelized using OpenMP. The software was designed for th

  15. The DTFE public software : The Delaunay Tessellation Field Estimator code

    NARCIS (Netherlands)

    Cautun, Marius C.; van de Weygaert, Rien

    2011-01-01

    We present the DTFE public software, a code for reconstructing fields from a discrete set of samples/measurements using the maximum of information contained in the point distribution. The code is written in C++ using the CGAL library and is parallelized using OpenMP. The software was designed for th

  16. Closed form maximum likelihood estimator of conditional random fields

    NARCIS (Netherlands)

    Zhu, Zhemin; Hiemstra, Djoerd; Apers, Peter M.G.; Wombacher, Andreas

    2013-01-01

    Training Conditional Random Fields (CRFs) can be very slow for big data. In this paper, we present a new training method for CRFs called {\\em Empirical Training} which is motivated by the concept of co-occurrence rate. We show that the standard training (unregularized) can have many maximum likeliho

  17. Direct magnetic field estimation based on echo planar raw data.

    Science.gov (United States)

    Testud, Frederik; Splitthoff, Daniel Nicolas; Speck, Oliver; Hennig, Jürgen; Zaitsev, Maxim

    2010-07-01

    Gradient recalled echo echo planar imaging is widely used in functional magnetic resonance imaging. The fast data acquisition is, however, very sensitive to field inhomogeneities which manifest themselves as artifacts in the images. Typically used correction methods have the common deficit that the data for the correction are acquired only once at the beginning of the experiment, assuming the field inhomogeneity distribution B(0) does not change over the course of the experiment. In this paper, methods to extract the magnetic field distribution from the acquired k-space data or from the reconstructed phase image of a gradient echo planar sequence are compared and extended. A common derivation for the presented approaches provides a solid theoretical basis, enables a fair comparison and demonstrates the equivalence of the k-space and the image phase based approaches. The image phase analysis is extended here to calculate the local gradient in the readout direction and improvements are introduced to the echo shift analysis, referred to here as "k-space filtering analysis." The described methods are compared to experimentally acquired B(0) maps in phantoms and in vivo. The k-space filtering analysis presented in this work demonstrated to be the most sensitive method to detect field inhomogeneities.

  18. Developing and evaluating rapid field methods to estimate peat carbon

    Science.gov (United States)

    Rodney A. Chimner; Cassandra A. Ott; Charles H. Perry; Randall K. Kolka

    2014-01-01

    Many international protocols (e.g., REDD+) are developing inventories of ecosystem carbon stocks and fluxes at country and regional scales, which can include peatlands. As the only nationally implemented field inventory and remeasurement of forest soils in the US, the USDA Forest Service Forest Inventory and Analysis Program (FIA) samples the top 20 cm of organic soils...

  19. Information channel capacity in the field theory estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sładkowski, J., E-mail: jan.sladkowski@us.edu.pl [Department of Astrophysics and Cosmology, Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Syska, J., E-mail: jacek.syska@us.edu.pl [Department of Field Theory and Particle Physics, Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)

    2012-12-03

    The construction of the information capacity for the vector position parameter in the Minkowskian space–time is presented. This lays the statistical foundations of the kinematical term of the Lagrangian of the physical action for many field theory models, derived by the extremal physical information method of Frieden and Soffer.

  20. An objective estimation of impurities in oil field stagnant waters

    Energy Technology Data Exchange (ETDEWEB)

    Abashev, R.G.; Runets, S.A.

    1984-01-01

    Studies and an analysis of published materials are used to establish the predominant role of the mechanical impurities of various origins covered by layers of the heavy components of petroleum products in reducing the injectivity of injection wells for injecting stagnant waters containing concretions. A method is proposed for determining the impurities in the oil field stagnant waters used for flooding; this method makes it possible to obtain more reliable results on the concentration of the concretions responsible in such conditions for the drop in the injectivity of the formation reservoirs. A comparative evaluation of the results from an analysis of the impurities determined by the existing method and the proposed method is given. This method is useful in oil field laboratories in the systematic quality control over injected waters.

  1. Recursion and growth estimates in renormalizable quantum field theory

    CERN Document Server

    Kreimer, D; Kreimer, Dirk; Yeats, Karen

    2006-01-01

    In this paper we show that there is a Lipatov bound for the radius of convergence for superficially divergent one-particle irreducible Green functions in a renormalizable quantum field theory if there is such a bound for the superficially convergent ones. The radius of convergence turns out to be ${\\rm min}\\{\\rho,1/b_1\\}$, where $\\rho$ is the bound on the convergent ones, the instanton radius, and $b_1$ the first coefficient of the $\\beta$-function.

  2. Estimation of Temperature Fields in Local Tissues During Intracavitary Hyperthermia

    Institute of Scientific and Technical Information of China (English)

    NanQun; HuZhengjun; 等

    1999-01-01

    This paper presents a heat transfer model for the hyperthermia treatment of cervix cancer using a intracavitary microwave applicator and based on which the 3-D finite element simulation of the temperature fields have done,Before then the specific absorption rate(SAR) distribution for the transvaginal probe have been measured in a phantom.The variations of the parameters have been investigated.Too,for optimization.At last,the rsults of simulation are compared to that measured in the phantom and some instructive conclusions are presented for critical application.

  3. ESTIMATION OF THE CONCRETE PAVEMENT TEMPERATURE FIELDS AND THEIR GRADIENTS

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2015-01-01

    Full Text Available The heat fluxes impact on the road-dressing concrete surfacing under different regions climatic conditions of the construction and maintenance dramatically degrades their solidity, corroding-, shiftingand frost-resistance, and ultimately – the service durability. The source of deformation processes is the character of the gradient temperature fields in the road dressing materials developing with both protracted (static and short run (dynamic heat-and-mass impacts that forward destruction of the pavement surface layers being in contact with free air. In addition, pulsating hydrodynamic pressures appear in the pores of moisture-laden pavement as a result of the vehicular traffic that foster material structure disruption of the surface layers leading to irreversible deformation incipiency (cracks etc.. The authors report of developing a С++ computer program for temperature and gradient fields engineering evaluations of the road dressings made of materials with various surfacing and free-air thermophysical characteristics in line with boundary conditions of the 3rd kind for semi-bounded body. The paper presents the evaluation results in form of graphical curves of the temperature allocation along the surfacing thickness as function of its initial temperature and thermophysical characteristics of the concrete. 

  4. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Vignola, Frank; Peterson, Josh; Kessler, Rich; Mavromatakis, Fotis; Dooraghi, Mike; Sengupta, Manajit

    2016-08-01

    This paper describes a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

  5. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field

    Energy Technology Data Exchange (ETDEWEB)

    Vignola, Frank; Peterson, Josh; Kessler, Rich; Mavromatakis, Fotis; Dooraghi, Mike; Sengupta, Manajit

    2016-06-05

    This poster provides an overview of a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

  6. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field

    Energy Technology Data Exchange (ETDEWEB)

    Vignola, Frank; Peterson, Josh; Kessler, Rich; Mavromatakis, Fotis; Dooraghi, Mike; Sengupta, Manajit

    2016-11-21

    Methodology is described that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is discussed. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

  7. Estimating Jupiter’s Gravity Field Using Juno Measurements, Trajectory Estimation Analysis, and a Flow Model Optimization

    Science.gov (United States)

    Galanti, Eli; Durante, Daniele; Finocchiaro, Stefano; Iess, Luciano; Kaspi, Yohai

    2017-07-01

    The upcoming Juno spacecraft measurements have the potential of improving our knowledge of Jupiter’s gravity field. The analysis of the Juno Doppler data will provide a very accurate reconstruction of spatial gravity variations, but these measurements will be very accurate only over a limited latitudinal range. In order to deduce the full gravity field of Jupiter, additional information needs to be incorporated into the analysis, especially regarding the Jovian flow structure and its depth, which can influence the measured gravity field. In this study we propose a new iterative method for the estimation of the Jupiter gravity field, using a simulated Juno trajectory, a trajectory estimation model, and an adjoint-based inverse model for the flow dynamics. We test this method both for zonal harmonics only and with a full gravity field including tesseral harmonics. The results show that this method can fit some of the gravitational harmonics better to the “measured” harmonics, mainly because of the added information from the dynamical model, which includes the flow structure. Thus, it is suggested that the method presented here has the potential of improving the accuracy of the expected gravity harmonics estimated from the Juno and Cassini radio science experiments.

  8. A rapid estimation of near field tsunami run-up

    Science.gov (United States)

    Riqueime, Sebastian; Fuentes, Mauricio; Hayes, Gavin; Campos, Jamie

    2015-01-01

    Many efforts have been made to quickly estimate the maximum run-up height of tsunamis associated with large earthquakes. This is a difficult task, because of the time it takes to construct a tsunami model using real time data from the source. It is possible to construct a database of potential seismic sources and their corresponding tsunami a priori.However, such models are generally based on uniform slip distributions and thus oversimplify the knowledge of the earthquake source. Here, we show how to predict tsunami run-up from any seismic source model using an analytic solution, that was specifically designed for subduction zones with a well defined geometry, i.e., Chile, Japan, Nicaragua, Alaska. The main idea of this work is to provide a tool for emergency response, trading off accuracy for speed. The solutions we present for large earthquakes appear promising. Here, run-up models are computed for: The 1992 Mw 7.7 Nicaragua Earthquake, the 2001 Mw 8.4 Perú Earthquake, the 2003Mw 8.3 Hokkaido Earthquake, the 2007 Mw 8.1 Perú Earthquake, the 2010 Mw 8.8 Maule Earthquake, the 2011 Mw 9.0 Tohoku Earthquake and the recent 2014 Mw 8.2 Iquique Earthquake. The maximum run-up estimations are consistent with measurements made inland after each event, with a peak of 9 m for Nicaragua, 8 m for Perú (2001), 32 m for Maule, 41 m for Tohoku, and 4.1 m for Iquique. Considering recent advances made in the analysis of real time GPS data and the ability to rapidly resolve the finiteness of a large earthquake close to existing GPS networks, it will be possible in the near future to perform these calculations within the first minutes after the occurrence of similar events. Thus, such calculations will provide faster run-up information than is available from existing uniform-slip seismic source databases or past events of pre-modeled seismic sources.

  9. Large transport Jc in Sn-added SmFeAsO1-xFx tapes prepared by an ex situ PIT method

    Science.gov (United States)

    Wang, Chunlei; Yao, Chao; Lin, He; Zhang, Xianping; Zhang, Qianjun; Wang, Dongliang; Ma, Yanwei; Awaji, S.; Watanabe, K.; Tsuchiya, Y.; Sun, Y.; Tamegai, T.

    2013-07-01

    SmFeAsO1-xFx possesses the highest superconducting transition temperature (Tc) among the iron-based superconductors, with a very high upper critical field and critical current density (Jc). All these are desirable for practical applications. Although tremendous progress has been made in improving the Jc values for Sr(Ba)-122 tapes or wires [1-3], the transport Jc of Sm1111 tapes or wires is still very low. Here we report on large transport critical current densities observed in Sn-added SmFeAsO1-xFx/Fe tapes produced by an ex situ powder-in-tube (PIT) method. It was found that the loss of fluorine was reduced and the intergranular coupling was enhanced in the Sn-added samples. As a result, the onset and offset Tc values for 10 wt%, 20 wt% and 30 wt% Sn-added samples were 52 K and 35 K, 53 K and 39 K, and 54 K and 41.5 K, respectively. In particular, a transport Jc as large as 22 000 A cm-2 (Ic = 160 A) at 4.2 K under self-field was achieved in 30 wt% Sn-added specimens, which is the highest value reported so far for SmFeAsO1-xFx wires and tapes. Magneto-optical imaging further showed that there were large global currents over the whole sample, which is consistent with the results obtained by the four-probe method.

  10. Non-invasively measured cardiac magnetic field maps improve the estimation of the current distribution

    OpenAIRE

    Kosch, Olaf; Steinhoff, Uwe; Trahms, Lutz; Trontelj, Zvonko; Jazbinšek, Vojko

    2015-01-01

    Comprehensive body surface potential mapping (BSPM) and magnetic field mapping (MFM) measurements have been carried out in order to improve the estimation of the current distribution generated by the human heart. Electric and magnetic fields and also the planar gradient of the magnetic field during the QRS complex were imaged as a time series of field maps. A model of the current distribution should explain the features of both BSPM and MFM. Simulated maps generated by a single dipole or a st...

  11. A method for the estimate of the wall diffusion for non-axisymmetric fields using rotating external fields

    Science.gov (United States)

    Frassinetti, L.; Olofsson, K. E. J.; Fridström, R.; Setiadi, A. C.; Brunsell, P. R.; Volpe, F. A.; Drake, J.

    2013-08-01

    A new method for the estimate of the wall diffusion time of non-axisymmetric fields is developed. The method based on rotating external fields and on the measurement of the wall frequency response is developed and tested in EXTRAP T2R. The method allows the experimental estimate of the wall diffusion time for each Fourier harmonic and the estimate of the wall diffusion toroidal asymmetries. The method intrinsically considers the effects of three-dimensional structures and of the shell gaps. Far from the gaps, experimental results are in good agreement with the diffusion time estimated with a simple cylindrical model that assumes a homogeneous wall. The method is also applied with non-standard configurations of the coil array, in order to mimic tokamak-relevant settings with a partial wall coverage and active coils of large toroidal extent. The comparison with the full coverage results shows good agreement if the effects of the relevant sidebands are considered.

  12. Quasispecies analysis of JC virus DNA present in urine of healthy subjects.

    Science.gov (United States)

    Van Loy, Tom; Thys, Kim; Tritsmans, Luc; Stuyver, Lieven J

    2013-01-01

    JC virus is a human polyomavirus that infects the majority of people without apparent symptoms in healthy subjects and it is the causative agent of progressive multifocal leucoencephalopathy (PML), a disorder following lytic infection of oligodendrocytes that mainly manifests itself under immunosuppressive conditions. A hallmark for JC virus isolated from PML-brain is the presence of rearrangements in the non-coding control region (NCCR) interspersed between the early and late genes on the viral genome. Such rearrangements are believed to originate from the archetype JC virus which is shed in urine by healthy subjects and PML patients. We applied next generation sequencing to explore the non-coding control region variability in urine of healthy subjects in search for JC virus quasispecies and rearrangements reminiscent of PML. For 61 viral shedders (out of a total of 254 healthy subjects) non-coding control region DNA and VP1 (major capsid protein) coding sequences were initially obtained by Sanger sequencing. Deletions between 1 and 28 nucleotides long appeared in ∼24.5% of the NCCR sequences while insertions were only detected in ∼3.3% of the samples. 454 pyrosequencing was applied on a subset of 54 urine samples demonstrating the existence of JC virus quasispecies in four subjects (∼7.4%). Hence, our results indicate that JC virus DNA in urine is not always restricted to one unique virus variant, but can be a mixture of naturally occurring variants (quasispecies) reflecting the susceptibility of the non-coding control region for genomic rearrangements in healthy individuals. Our findings pave the way to explore the presence of viral quasispecies and the altered viral tropism that might go along with it as a potential risk factor for opportunistic secondary infections such as PML.

  13. Estimation of random fields from network observations. Technical report No. 26

    Energy Technology Data Exchange (ETDEWEB)

    Cabannes, A F

    1979-06-01

    When one has observed a random field Z at some points and recorded its values (network observations), a natural problem is to estimate Z at points where there are no observations. This dissertation deals first with this problem in an abstract setting, in m dimensions; later, it considers the estimation of a spatial two-dimensional random field. The problem then is one of constructing an estimated map of Z over a geographic area. For a given network of stations the quality of a map depends on the method of estimation. But for the given method of estimation the quality of a map depends on the choice of locations for the stations. This is the problem of network design. Both the study of methods of estimation and the problem of network design are addressed. 16 figures. (RWR)

  14. Anti-JC virus antibody prevalence in a multinational multiple sclerosis cohort

    DEFF Research Database (Denmark)

    Olsson, Tomas; Achiron, Anat; Alfredsson, Lars;

    2013-01-01

    JC virus (JCV) is an opportunistic virus known to cause progressive multifocal leukoencephalopathy. Anti-JC virus (Anti-JCV) antibody prevalence in a large, geographically diverse, multi-national multiple sclerosis (MS) cohort was compared in a cross-sectional study. Overall, anti-JCV antibody...... prevalence was 57.6%. Anti-JCV antibody prevalence in MS patients ranged from approximately 47% to 68% across these countries: Norway, 47.4%; Denmark, 52.6%; Israel, 56.6%; France, 57.6%; Italy, 58.3%; Sweden, 59.0%; Germany, 59.1%; Austria, 66.7% and Turkey, 67.7%. Prevalence increased with age (from 49...

  15. Estimation of the magnetic field gradient tensor using the Swarm constellation

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Finlay, Chris; Olsen, Nils

    2014-01-01

    For the first time, part of the magnetic field gradient tensor is estimated in space by the Swarm mission. We investigate the possibility of a more complete estimation of the gradient tensor exploiting the Swarm constellation. The East-West gradients can be approximated by observations from...

  16. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, Jordy; Kokkeler, André B.J.; Smit, Gerard J.M.

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The syste

  17. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The

  18. Large transport Jc in Cu-sheathed Sr0.6K0.4Fe2As2 superconducting tape conductors

    Science.gov (United States)

    Lin, He; Yao, Chao; Zhang, Haitao; Zhang, Xianping; Zhang, Qianjun; Dong, Chiheng; Wang, Dongliang; Ma, Yanwei

    2015-01-01

    Copper sheath is the first choice for manufacturing high-Tc superconducting wires and tapes because of its high electrical and thermal conductivities, low-cost and good mechanical properties. However, Cu can easily react with superconducting cores, such as BSCCO, MgB2 and pnictides, and therefore drastically decrease the transport Jc. Here, we report the fabrication of Cu-sheathed Sr1−xKxFe2As2 tapes with superior Jc performance using a simple hot pressing method that is capable of eliminating the lengthy high-temperature sintering. We obtained high-quality Sr1−xKxFe2As2 tapes with processing at 800 oC for 30 minutes and measured high Tc and sharp transition. By this rapid fabrication, Cu sheath does not give rise to apparent reaction layer, and only slightly diffuses into Sr-122 core. As a consequence, we achieved high transport Jc of 3.1 × 104 A/cm2 in 10 T and 2.7 × 104 A/cm2 in 14 T at 4.2 K. The in-field Jc performance is by far the highest reported for Cu-sheathed high-Tc conductors. More importantly, Cu-sheathed Sr-122 tapes also showed a high Je value of 1.0 × 104 A/cm2 in 10 T at 4.2 K, which has reached the widely accepted practical level for applications. These results demonstrate that Cu is a very promising sheath for the practical application of pnictide conductors. PMID:26122741

  19. A SO(3)-invariant variational method for depth field estimation based on inertial and camera data

    CERN Document Server

    Zarrouati, Nadege; Rouchon, Pierre

    2011-01-01

    In this paper, we use known camera motion associated to a video sequence of a static scene in order to estimate and incrementally refine the surrounding depth field. We exploit the SO(3)-invariance of brightness and depth fields dynamics to customize standard image processing techniques. Inspired by the Horn-Schunck method, we propose a SO(3)-invariant cost minimized by the depth field. For each time, this provides a diffusion equation on the unit Riemannian sphere that characterizes the estimated depth field. Written in pinhole coordinates, this scalar diffusion equation is numerically solved to provide in real time a depth field estimation of the entire field of view. On synthetic data, quantitative comparison with asymptotic observers merging direct optical flow estimation (by Horn-Schunck and TV-L1 methods) and camera motion illustrate the performance of the proposed method. Implementation on a real sequence of images shows that these estimations are accurate in regions where the depth field is continuous...

  20. A phase field method for joint denoising, edge detection, and motion estimation in image sequence processing

    NARCIS (Netherlands)

    Preusser, T.; Droske, M.; Garbe, C. S.; Telea, A.; Rumpf, M.

    2007-01-01

    The estimation of optical flow fields from image sequences is incorporated in a Mumford-Shah approach for image denoising and edge detection. Possibly noisy image sequences are considered as input and a piecewise smooth image intensity, a piecewise smooth motion field, and a joint discontinuity set

  1. Artificial force fields for multi-agent simulations of maritime traffic and risk estimation

    NARCIS (Netherlands)

    Xiao, F.; Ligteringen, H.; Van Gulijk, C.; Ale, B.J.M.

    2012-01-01

    A probabilistic risk model is designed to estimate probabilities of collisions for shipping accidents in busy waterways. We propose a method based on multi-agent simulation that uses an artificial force field to model ship maneuvers. The artificial force field is calibrated by AIS data (Automatic Id

  2. Sensor selection for parameterized random field estimation in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    We consider the random field estimation problem with parametric trend in wireless sensor networks where the field can be described by unknown parameters to be estimated. Due to the limited resources, the network selects only a subset of the sensors to perform the estimation task with a desired performance under the D-optimal criterion. We propose a greedy sampling scheme to select the sensor nodes according to the information gain of the sensors. A distributed algorithm is also developed by consensus-based ...

  3. Estimating urban roadside emissions with an atmospheric dispersion model based on in-field measurements.

    Science.gov (United States)

    Pu, Yichao; Yang, Chao

    2014-09-01

    Urban vehicle emission models have been utilized to calculate pollutant concentrations at both microscopic and macroscopic levels based on vehicle emission rates which few researches have been able to validate. The objective of our research is to estimate urban roadside emissions and calibrate it with in-field measurement data. We calculated the vehicle emissions based on localized emission rates, and used an atmospheric dispersion model to estimate roadside emissions. A non-linear regression model was applied to calibrate the localized emission rates using in-field measurement data. With the calibrated emission rates, emissions on urban roadside can be estimated with a high accuracy.

  4. A sparse reconstruction method for the estimation of multiresolution emission fields via atmospheric inversion

    Directory of Open Access Journals (Sweden)

    J. Ray

    2014-08-01

    Full Text Available We present a sparse reconstruction scheme that can also be used to ensure non-negativity when fitting wavelet-based random field models to limited observations in non-rectangular geometries. The method is relevant when multiresolution fields are estimated using linear inverse problems. Examples include the estimation of emission fields for many anthropogenic pollutants using atmospheric inversion or hydraulic conductivity in aquifers from flow measurements. The scheme is based on three new developments. Firstly, we extend an existing sparse reconstruction method, Stagewise Orthogonal Matching Pursuit (StOMP, to incorporate prior information on the target field. Secondly, we develop an iterative method that uses StOMP to impose non-negativity on the estimated field. Finally, we devise a method, based on compressive sensing, to limit the estimated field within an irregularly shaped domain. We demonstrate the method on the estimation of fossil-fuel CO2 (ffCO2 emissions in the lower 48 states of the US. The application uses a recently developed multiresolution random field model and synthetic observations of ffCO2 concentrations from a limited set of measurement sites. We find that our method for limiting the estimated field within an irregularly shaped region is about a factor of 10 faster than conventional approaches. It also reduces the overall computational cost by a factor of two. Further, the sparse reconstruction scheme imposes non-negativity without introducing strong nonlinearities, such as those introduced by employing log-transformed fields, and thus reaps the benefits of simplicity and computational speed that are characteristic of linear inverse problems.

  5. On Non-Parametric Field Estimation using Randomly Deployed, Noisy, Binary Sensors

    CERN Document Server

    Wang, Ye

    2007-01-01

    We consider the problem of reconstructing a deterministic data field from binary quantized noisy observations of sensors randomly deployed over the field domain. Our focus is on the extremes of lack of control in the sensor deployment, arbitrariness and lack of knowledge of the noise distribution, and low-precision and unreliability in the sensors. These adverse conditions are motivated by possible real-world scenarios where a large collection of low-cost, crudely manufactured sensors are mass-deployed in an environment where little can be assumed about the ambient noise. We propose a simple estimator that reconstructs the entire data field from these unreliable, binary quantized, noisy observations. Under the assumption of a bounded amplitude field, we prove almost sure and mean-square convergence of the estimator to the actual field as the number of sensors tends to infinity. For fields with bounded-variation, Sobolev differentiable, or finite-dimensionality properties, we derive specific mean squared error...

  6. Heat kernel estimates and spectral properties of a pseudorelativistic operator with magnetic field

    Science.gov (United States)

    Jakubassa-Amundsen, D. H.

    2008-03-01

    Based on the Mehler heat kernel of the Schrödinger operator for a free electron in a constant magnetic field, an estimate for the kernel of EA=∣α(p-eA)+βm∣ is derived, where EA represents the kinetic energy of a Dirac electron within the pseudorelativistic no-pair Brown-Ravenhall model. This estimate is used to provide the bottom of the essential spectrum for the two-particle Brown-Ravenhall operator, describing the motion of the electrons in a central Coulomb field and a constant magnetic field, if the central charge is restricted to Z ⩽86.

  7. Topographical Estimation of Visual Population Receptive Fields by fMRI

    OpenAIRE

    Lee, Sangkyun; Papanikolaou, Amalia; Keliris, Georgios A.; Smirnakis, Stelios M.

    2015-01-01

    Visual cortex is retinotopically organized so that neighboring populations of cells map to neighboring parts of the visual field. Functional magnetic resonance imaging allows us to estimate voxel-based population receptive fields (pRF), i.e., the part of the visual field that activates the cells within each voxel. Prior, direct, pRF estimation methods1 suffer from certain limitations: 1) the pRF model is chosen a-priori and may not fully capture the actual pRF shape, and 2) pRF centers are pr...

  8. Estimation of soil moisture in paddy field using Artificial Neural Networks

    CERN Document Server

    Arif, Chusnul; Setiawan, Budi Indra; Doi, Ryoichi

    2013-01-01

    In paddy field, monitoring soil moisture is required for irrigation scheduling and water resource allocation, management and planning. The current study proposes an Artificial Neural Networks (ANN) model to estimate soil moisture in paddy field with limited meteorological data. Dynamic of ANN model was adopted to estimate soil moisture with the inputs of reference evapotranspiration (ETo) and precipitation. ETo was firstly estimated using the maximum, average and minimum values of air temperature as the inputs of model. The models were performed under different weather conditions between the two paddy cultivation periods. Training process of model was carried out using the observation data in the first period, while validation process was conducted based on the observation data in the second period. Dynamic of ANN model estimated soil moisture with R2 values of 0.80 and 0.73 for training and validation processes, respectively, indicated that tight linear correlations between observed and estimated values of s...

  9. A more realistic estimate of the variances and systematic errors in spherical harmonic geomagnetic field models

    DEFF Research Database (Denmark)

    Lowes, F.J.; Olsen, Nils

    2004-01-01

    Most modern spherical harmonic geomagnetic models based on satellite data include estimates of the variances of the spherical harmonic coefficients of the model; these estimates are based on the geometry of the data and the fitting functions, and on the magnitude of the residuals. However......, led to quite inaccurate variance estimates. We estimate correction factors which range from 1/4 to 20, with the largest increases being for the zonal, m = 0, and sectorial, m = n, terms. With no correction, the OSVM variances give a mean-square vector field error of prediction over the Earth's surface...

  10. Spendere meno, spendere meglio: una proposta panottica di J.-C. Guédon

    Directory of Open Access Journals (Sweden)

    Maria Chiara Pievatolo

    2013-06-01

    Full Text Available J.-C. Guédon ha commentato la nostra campagna di crowdsourcing in merito alle spese delle biblioteche sulla mailing list Nexa. Offriamo, qui di seguito, la versione italiana delle sue osservazioni – che presuppongono un mondo accademico molto diverso da quello impostoci...

  11. Sudden birth of entanglement between two atoms in a double JC model

    Institute of Scientific and Technical Information of China (English)

    Mingdi Du; Maofa Fang; Xiang Liu

    2009-01-01

    Sudden birth of entanglement between two initially separate atoms interacting with two entangled photons in a double JC model is investigated,arid the influences of different atomic initial states on entanglement among atoms are discussed.The results show that sudden birth of entanglement can occur when the two atoms are initially in excited states.

  12. J.C. Nalle Community School: A Study of a School Turnaround Effort. Publication #2015-14

    Science.gov (United States)

    Redd, Zakia; Princiotta, Daniel; Stratford, Brandon; Caal, Selma; Li, Weilin; Murphy, Kelly; Coffey, Amelia; Carrington, Nicholas; Carney, Rachel; Oster, Maryjo; Horton, Susannah

    2015-01-01

    J.C. Nalle is a Community School located in the Marshall Heights neighborhood of Ward 7 in Washington, D.C. The community in which J.C. Nalle is located, historically one of the more economically disadvantaged areas of the city, has experienced a number of changes in recent years. This report of evaluation findings begins with an introduction to…

  13. J.C. Nalle Community School: A Study of a School Turnaround Effort. Publication #2015-14

    Science.gov (United States)

    Redd, Zakia; Princiotta, Daniel; Stratford, Brandon; Caal, Selma; Li, Weilin; Murphy, Kelly; Coffey, Amelia; Carrington, Nicholas; Carney, Rachel; Oster, Maryjo; Horton, Susannah

    2015-01-01

    J.C. Nalle is a Community School located in the Marshall Heights neighborhood of Ward 7 in Washington, D.C. The community in which J.C. Nalle is located, historically one of the more economically disadvantaged areas of the city, has experienced a number of changes in recent years. This report of evaluation findings begins with an introduction to…

  14. Ectopic expression of Jatropha curcas APETALA1 (JcAP1 caused early flowering in Arabidopsis, but not in Jatropha

    Directory of Open Access Journals (Sweden)

    Mingyong Tang

    2016-04-01

    Full Text Available Jatropha curcas is a promising feedstock for biofuel production because Jatropha oil is highly suitable for the production of biodiesel and bio-jet fuels. However, Jatropha exhibits a low seed yield as a result of unreliable and poor flowering. APETALA1 (AP1 is a floral meristem and organ identity gene in higher plants. The flower meristem identity genes of Jatropha have not yet been identified or characterized. To better understand the genetic control of flowering in Jatropha, an AP1 homolog (JcAP1 was isolated from Jatropha. An amino acid sequence analysis of JcAP1 revealed a high similarity to the AP1 proteins of other perennial plants. JcAP1 was expressed in inflorescence buds, flower buds, sepals and petals. The highest expression level was observed during the early developmental stage of the flower buds. The overexpression of JcAP1 using the cauliflower mosaic virus (CaMV 35S promoter resulted in extremely early flowering and abnormal flowers in transgenic Arabidopsis plants. Several flowering genes downstream of AP1 were up-regulated in the JcAP1-overexpressing transgenic plant lines. Furthermore, JcAP1 overexpression rescued the phenotype caused by the Arabidopsis AP1 loss-of-function mutant ap1-11. Therefore, JcAP1 is an ortholog of AtAP1, which plays a similar role in the regulation of flowering in Arabidopsis. However, the overexpression of JcAP1 in Jatropha using the same promoter resulted in little variation in the flowering time and floral organs, indicating that JcAP1 may be insufficient to regulate flowering by itself in Jatropha. This study helps to elucidate the function of JcAP1 and contributes to the understanding of the molecular mechanisms of flower development in Jatropha.

  15. Rock property estimates using multiple seismic attributes and neural networks; Pegasus Field, West Texas

    Energy Technology Data Exchange (ETDEWEB)

    Schuelke, J.S.; Quirein, J.A.; Sarg, J.F.

    1998-12-31

    This case study shows the benefit of using multiple seismic trace attributes and the pattern recognition capabilities of neural networks to predict reservoir architecture and porosity distribution in the Pegasus Field, West Texas. The study used the power of neural networks to integrate geologic, borehole and seismic data. Illustrated are the improvements between the new neural network approach and the more traditional method of seismic trace inversion for porosity estimation. Comprehensive statistical methods and interpretational/subjective measures are used in the prediction of porosity from seismic attributes. A 3-D volume of seismic derived porosity estimates for the Devonian reservoir provide a very detailed estimate of porosity, both spatially and vertically, for the field. The additional reservoir porosity detail provided, between the well control, allows for optimal placement of horizontal wells and improved field development. 6 refs., 2 figs.

  16. Selecting a spatial resolution for estimation of per-field green leaf area index

    Science.gov (United States)

    Curran, Paul J.; Williamson, H. Dawn

    1988-01-01

    For any application of multispectral scanner (MSS) data, a user is faced with a number of choices concerning the characteristics of the data; one of these is their spatial resolution. A pilot study was undertaken to determine the spatial resolution that would be optimal for the per-field estimation of green leaf area index (GLAI) in grassland. By reference to empirically-derived data from three areas of grassland, the suitable spatial resolution was hypothesized to lie in the lower portion of a 2-18 m range. To estimate per-field GLAI, airborne MSS data were collected at spatial resolutions of 2 m, 5 m and 10 m. The highest accuracies of per-field GLAI estimation were achieved using MSS data with spatial resolutions of 2 m and 5 m.

  17. Optimization by Estimation of Distribution with DEUM Framework Based on Markov Random Fields

    Institute of Scientific and Technical Information of China (English)

    Siddhartha Shakya; John McCall

    2007-01-01

    This paper presents a Markov random field (MRP) approach to estimating and sampling the probability distribution in populations of solutions. The approach is used to define a class of algorithms under the general heading distribution estimation using Markov random fields (DEUM). DEUM is a subclass of estimation of distribution algorithms (EDAs) where interaction between solution variables is represented as an undirected graph and the joint probability of a solution is factorized as a Gibbs distribution derived from the structure of the graph. The focus of this paper will be on describing the three main characteristics of DEUM framework, which distinguishes it from the traditional EDA. They are: 1) use of MRF models, 2) fitness modeling approach to estimating the parameter of the model and 3) Monte Carlo approach to sampling from the model.

  18. Field Evaluation of the System Identification Approach for Tension Estimation of External Tendons

    Directory of Open Access Journals (Sweden)

    Myung-Hyun Noh

    2015-01-01

    Full Text Available Various types of external tendons are considered to verify the applicability of tension estimation method based on the finite element model with system identification technique. The proposed method is applied to estimate the tension of benchmark numerical example, model structure, and field structure. The numerical and experimental results show that the existing methods such as taut string theory and linear regression method show large error in the estimated tension when the condition of external tendon is different with the basic assumption used during the derivation of relationship between tension and natural frequency. However, the proposed method gives reasonable results for all of the considered external tendons in this study. Furthermore, the proposed method can evaluate the accuracy of estimated tension indirectly by comparing the measured and calculated natural frequencies. Therefore, the proposed method can be effectively used for field application of various types of external tendons.

  19. Delay Kalman Filter to Estimate the Attitude of a Mobile Object with Indoor Magnetic Field Gradients

    Directory of Open Access Journals (Sweden)

    Christophe Combettes

    2016-05-01

    Full Text Available More and more services are based on knowing the location of pedestrians equipped with connected objects (smartphones, smartwatches, etc.. One part of the location estimation process is attitude estimation. Many algorithms have been proposed but they principally target open space areas where the local magnetic field equals the Earth’s field. Unfortunately, this approach is impossible indoors, where the use of magnetometer arrays or magnetic field gradients has been proposed. However, current approaches omit the impact of past state estimates on the current orientation estimate, especially when a reference field is computed over a sliding window. A novel Delay Kalman filter is proposed in this paper to integrate this time correlation: the Delay MAGYQ. Experimental assessment, conducted in a motion lab with a handheld inertial and magnetic mobile unit, shows that the novel filter better estimates the Euler angles of the handheld device with an 11.7° mean error on the yaw angle as compared to 16.4° with a common Additive Extended Kalman filter.

  20. Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data

    Science.gov (United States)

    Deutschmann, Julie; Bar-Itzhack, Itzhack

    1997-01-01

    A single, augmented extended Kalman filter (EKF) which simultaneously and autonomously estimates spacecraft attitude and orbit was developed and tested with simulated and real magnetometer and rate data. Since the earth's magnetic field is a function of time and position, and since time is accurately known, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft's orbit, are a function of orbit and attitude errors. These differences can be used to estimate the orbit and attitude. The test results of the EKF with magnetometer and gyro data from three NASA satellites are presented and evaluated.

  1. Estimation of a planetary magnetic field using a reduced magnetohydrodynamic model

    Science.gov (United States)

    Nabert, Christian; Heyner, Daniel; Glassmeier, Karl-Heinz

    2017-03-01

    Knowledge of planetary magnetic fields provides deep insights into the structure and dynamics of planets. Due to the interaction of a planet with the solar wind plasma, a rather complex magnetic environment is generated. The situation at planet Mercury is an example of the complexities occurring as this planet's field is rather weak and the magnetosphere rather small. New methods are presented to separate interior and exterior magnetic field contributions which are based on a dynamic inversion approach using a reduced magnetohydrodynamic (MHD) model and time-varying spacecraft observations. The methods select different data such as bow shock location information or magnetosheath magnetic field data. Our investigations are carried out in preparation for the upcoming dual-spacecraft BepiColombo mission set out to precisely estimate Mercury's intrinsic magnetic field. To validate our new approaches, we use THEMIS magnetosheath observations to estimate the known terrestrial dipole moment. The terrestrial magnetosheath provides observations from a strongly disturbed magnetic environment, comparable to the situation at Mercury. Statistical and systematic errors are considered and their dependence on the selected data sets are examined. Including time-dependent upstream solar wind variations rather than averaged conditions significantly reduces the statistical error of the estimation. Taking the entire magnetosheath data along the spacecraft's trajectory instead of only the bow shock location into account further improves accuracy of the estimated dipole moment.

  2. A new estimate of average dipole field strength for the last five million years

    Science.gov (United States)

    Cromwell, G.; Tauxe, L.; Halldorsson, S. A.

    2013-12-01

    The Earth's ancient magnetic field can be approximated by a geocentric axial dipole (GAD) where the average field intensity is twice as strong at the poles than at the equator. The present day geomagnetic field, and some global paleointensity datasets, support the GAD hypothesis with a virtual axial dipole moment (VADM) of about 80 ZAm2. Significant departures from GAD for 0-5 Ma are found in Antarctica and Iceland where paleointensity experiments on massive flows (Antarctica) (1) and volcanic glasses (Iceland) produce average VADM estimates of 41.4 ZAm2 and 59.5 ZAm2, respectively. These combined intensities are much closer to a lower estimate for long-term dipole field strength, 50 ZAm2 (2), and some other estimates of average VADM based on paleointensities strictly from volcanic glasses. Proposed explanations for the observed non-GAD behavior, from otherwise high-quality paleointensity results, include incomplete temporal sampling, effects from the tangent cylinder, and hemispheric asymmetry. Differences in estimates of average magnetic field strength likely arise from inconsistent selection protocols and experiment methodologies. We address these possible biases and estimate the average dipole field strength for the last five million years by compiling measurement level data of IZZI-modified paleointensity experiments from lava flows around the globe (including new results from Iceland and the HSDP-2 Hawaii drill core). We use the Thellier Gui paleointensity interpreter (3) in order to apply objective criteria to all specimens, ensuring consistency between sites. Specimen level selection criteria are determined from a recent paleointensity investigation of modern Hawaiian lava flows where the expected magnetic field strength was accurately recovered when following certain selection parameters. Our new estimate of average dipole field strength for the last five million years incorporates multiple paleointensity studies on lava flows with diverse global and

  3. An efficient anti-occlusion depth estimation using generalized EPI representation in light field

    Science.gov (United States)

    Zhu, Hao; Wang, Qing

    2016-10-01

    Light field cameras have been rapidly developed and are likely to appear in mobile devices in near future. It is essential to develop efficient and robust depth estimation algorithm for mobile applications. However, existing methods are either slow or lack of adaptability to occlusion such that they are not suitable to mobile computing platform. In this paper, we present the generalized EPI representation in light field and formulate it using two linear functions. By combining it with the light field occlusion theory, a highly efficient and anti-occlusion depth estimation algorithm is proposed. Our algorithm outperforms the previous local method, especially in occlusion areas. Experimental results on public light field datasets have demonstrated the effectiveness and efficiency of the proposed algorithm.

  4. Recursive Estimation of Gauss-Markov Random Fields Indexed over 1-D Space

    CERN Document Server

    Vats, Divyanshu

    2009-01-01

    This paper presents optimal recursive estimators for vector valued Gauss-Markov random \\emph{fields} taking values in $\\R^M$ and indexed by (intervals of) $\\R$ or $\\Z$. These 1-D fields are often called reciprocal processes. They correspond to two point boundary value fields, i.e., they have boundary conditions given at the end points of the indexing interval. To obtain the recursive estimators, we derive two classes of recursive representations for reciprocal processes. The first class transforms the Gaussian reciprocal process into a Gauss-Markov \\emph{process}, from which we derive forward and backwards recursive representations. The second representation folds the index set and transforms the original \\emph{field} taking values in $\\R^M$ into a Markov \\emph{process} taking values in $\\R^{2M}$. The folding corresponds to recursing the reciprocal process from the boundary points and telescoping inwards. From these recursive representations, Kalman filters and recursive smoothers are promptly derived.

  5. Optimal heat kernel estimates for Schroedinger operators with magnetic fields in two dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Loss, M. [Georgia Inst. of Tech., Atlanta (United States). School of Mathematics; Thaller, B. [Institut fuer Mathematik, Universitaet Graz, A-8010 Graz (Austria)

    1997-06-01

    Sharp smoothing estimates are proven for magnetic Schroedinger semigroups in two dimensions under the assumption that the magnetic field is bounded below by some positive constant B{sub 0}. As a consequence the L{sup {infinity}} norm of the associated integral kernel is bounded by the L{sup {infinity}} norm of the Mehler kernel of the Schroedinger semigroup with the constant magnetic field B{sub 0}. (orig.)

  6. Estimating magnetic fields of homes near transmission lines in the California Power Line Study.

    Science.gov (United States)

    Vergara, Ximena P; Kavet, Robert; Crespi, Catherine M; Hooper, Chris; Silva, J Michael; Kheifets, Leeka

    2015-07-01

    The California Power Line Study is a case-control study investigating the relation between residences near transmission lines and risk of childhood leukemia. It includes 5788 childhood leukemia cases and 5788 matched primary controls born between 1986 and 2007. We describe the methodology for estimating magnetic fields at study residences as well as for characterizing sources of uncertainty in these estimates. Birth residences of study subjects were geocoded and their distances to transmission lines were ascertained. 302 residences were deemed sufficiently close to transmission lines to have non-zero magnetic fields attributable to the lines. These residences were visited and detailed data, describing the physical configuration and dimensions of the lines contributing to the magnetic field at the residence, were collected. Phasing, loading, and directional load flow data for years of birth and diagnosis for each subject as well as for the day of site visit were obtained from utilities when available; when yearly average load for a particular year was not available, extrapolated values based on expert knowledge and prediction models were obtained. These data were used to estimate the magnetic fields at the center, closest and farthest point of each residence. We found good correlation between calculated fields and spot measurements of fields taken on site during visits. Our modeling strategies yielded similar calculated field estimates, and they were in high agreement with utility extrapolations. Phasing was known for over 90% of the lines. Important sources of uncertainty included a lack of information on the precise location of residences located within apartment buildings or other complexes. Our findings suggest that we were able to achieve high specificity in exposure assessment, which is essential for examining the association between distance to or magnetic fields from power lines and childhood leukemia risk.

  7. Simplified Atmospheric Dispersion Model andModel Based Real Field Estimation System ofAir Pollution

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The atmospheric dispersion model has been well developed and applied in pollution emergency and prediction. Based on thesophisticated air diffusion model, this paper proposes a simplified model and some optimization about meteorological andgeological conditions. The model is suitable for what is proposed as Real Field Monitor and Estimation system. The principle ofsimplified diffusion model and its optimization is studied. The design of Real Field Monitor system based on this model and itsfundamental implementations are introduced.

  8. A priori estimates for nonvariational operators modeled on Hörmander's vector fields with drift

    Directory of Open Access Journals (Sweden)

    Marco Bramanti

    2013-12-01

    Full Text Available For a nonvariational operator structured on Hörmander's vector fields with drift, where the matrix of coffiecients is real, symmetric and uniformly positive, we prove local a priori estimates on the second order derivatives with respect to the vector fields, in Hölder spaces if the coecients are Holder continuous, in Lp spaces if the coefficients are bounded, measurable and locally VMO.

  9. A priori estimates for nonvariational operators modeled on Hörmander's vector fields with drift

    OpenAIRE

    Marco Bramanti

    2013-01-01

    For a nonvariational operator structured on Hörmander's vector fields with drift, where the matrix of coffiecients is real, symmetric and uniformly positive, we prove local a priori estimates on the second order derivatives with respect to the vector fields, in Hölder spaces if the coecients are Holder continuous, in Lp spaces if the coefficients are bounded, measurable and locally VMO.

  10. Laboratory and field verification of a method to estimate the extent of petroleum biodegradation in soil.

    Science.gov (United States)

    Douglas, Gregory S; Hardenstine, Jeffery H; Liu, Bo; Uhler, Allen D

    2012-08-07

    We describe a new and rapid quantitative approach to assess the extent of aerobic biodegradation of volatile and semivolatile hydrocarbons in crude oil, using Shushufindi oil from Ecuador as an example. Volatile hydrocarbon biodegradation was both rapid and complete-100% of the benzene, toluene, xylenes (BTEX) and 98% of the gasoline-range organics (GRO) were biodegraded in less than 2 days. Severe biodegradation of the semivolatile hydrocarbons occurred in the inoculated samples with 67% and 87% loss of the diesel-range hydrocarbons (DRO) in 3 and 20 weeks, respectively. One-hundred percent of the naphthalene, fluorene, and phenanthrene, and 46% of the chrysene in the oil were biodegraded within 3 weeks. Percent depletion estimates based on C(30) 17α,21β(H)-hopane (hopane) underestimated the diesel-range organics (DRO) and USEPA 16 priority pollutant PAH losses in the most severely biodegraded samples. The C(28) 20S-triaromatic steroid (TAS) was found to yield more accurate depletion estimates, and a new hopane stability ratio (HSR = hopane/(hopane + TAS)) was developed to monitor hopane degradation in field samples. Oil degradation within field soil samples impacted with Shushufindi crude oil was 83% and 98% for DRO and PAH, respectively. The gas chromatograms and percent depletion estimates indicated that similar levels of petroleum degradation occurred in both the field and laboratory samples, but hopane degradation was substantially less in the field samples. We conclude that cometabolism of hopane may be a factor during rapid biodegradation of petroleum in the laboratory and may not occur to a great extent during biodegradation in the field. We recommend that the hopane stability ratio be monitored in future field studies. If hopane degradation is observed, then the TAS percent depletion estimate should be computed to correct for any bias that may result in petroleum depletion estimates based on hopane.

  11. The electrical conductivity of the upper mantle as estimated from satellite magnetic field data

    Science.gov (United States)

    Didwall, E. M.

    1984-01-01

    The electrical conductivity of the upper mantle is estimated from low-latitude magnetic field variations caused by large fluctuations in the equatorial ring current. The data base is derived from magnetic field magnitude data measured by satellites OGO 2, 4, and 6, which offer better global coverage than land-based observatories. The procedures of analysis consist of: (1) separation of the disturbance field into internal and external parts relative to the surface of the earth, (2) estimation of an electromagnetic response function Q(omega) which relates the internally generated magnetic field variations to the external variations due to the ring current, and (3) interpretation of the estimated response function using theoretical response functions for assumed conductivity profiles. Special consideration is given to possible oceanic and ionospheric effects. Best estimates of the geomagnetic response function Q(omega) for 0.2 to 2.0 cpd indicate an upper mantle conductivity of the order of 0.01 S/m.

  12. New a priori estimates for mean-field games with congestion

    KAUST Repository

    Evangelista, David

    2016-01-06

    We present recent developments in crowd dynamics models (e.g. pedestrian flow problems). Our formulation is given by a mean-field game (MFG) with congestion. We start by reviewing earlier models and results. Next, we develop our model. We establish new a priori estimates that give partial regularity of the solutions. Finally, we discuss numerical results.

  13. Estimating adhesive seed-dispersal distances : field experiments and correlated random walks

    NARCIS (Netherlands)

    Mouissie, AM; Lengkeek, W; van Diggelen, R

    1. In this study we aimed to estimate distance distributions of adhesively dispersed seeds and the factors that determine them. 2. Seed attachment and detachment were studied using field experiments with a real sheep, a sheep dummy and a cattle dummy. Seed-retention data were used in correlated

  14. The electrical conductivity of the upper mantle as estimated from satellite magnetic field data

    Science.gov (United States)

    Didwall, E. M.

    1984-01-01

    The electrical conductivity of the upper mantle is estimated from low-latitude magnetic field variations caused by large fluctuations in the equatorial ring current. The data base is derived from magnetic field magnitude data measured by satellites OGO 2, 4, and 6, which offer better global coverage than land-based observatories. The procedures of analysis consist of: (1) separation of the disturbance field into internal and external parts relative to the surface of the earth, (2) estimation of an electromagnetic response function Q(omega) which relates the internally generated magnetic field variations to the external variations due to the ring current, and (3) interpretation of the estimated response function using theoretical response functions for assumed conductivity profiles. Special consideration is given to possible oceanic and ionospheric effects. Best estimates of the geomagnetic response function Q(omega) for 0.2 to 2.0 cpd indicate an upper mantle conductivity of the order of 0.01 S/m.

  15. Effects of the near field on source-independent q estimation

    NARCIS (Netherlands)

    Shigapov, R.; Kashtan, B.; Droujinine, A.; Mulder, W.A.

    2013-01-01

    We consider the problem of Q estimation from microseismic and from perforation shot data. Assuming that the source wavelet is not well known, we focused on the spectral ratio method and on source-independent viscoelastic full waveform inversion. We derived 3-D near-field approximations of monopole a

  16. Comprehensive Evaluation of Attitude and Orbit Estimation Using Actual Earth Magnetic Field Data

    Science.gov (United States)

    Deutschmann, Julie K.; Bar-Itzhack, Itzhack Y.

    2000-01-01

    A single, augmented Extended Kalman Filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit has been developed and successfully tested with real magnetometer and gyro data only. Because the earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude; an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center (GSFC) Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only.

  17. Optimization of Camera Arrangement Using Correspondence Field to Improve Depth Estimation.

    Science.gov (United States)

    Fu, Shichao; Safaei, Farzad; Li, Wanqing

    2017-04-18

    Stereo matching algorithms attempt to estimate depth from the images obtained by two cameras. In most cases, the arrangement of cameras (their locations and orientations with respect to the scene) are determined based on human experience. In this paper, it is shown that the camera arrangement can be optimized using the concept of correspondence field (CF) for better acquisition of depth. Specifically, the paper demonstrates the relationship between the correspondence field of a pair of cameras and depth estimation accuracy and presents a method to optimize their arrangement based on the gradient of CF. The experimental results show that a pair of cameras optimized by the proposed method can improve the accuracy of depth estimation by as much as 30% compared to the conventional camera arrangements.

  18. Estimation of GNSS Multiscale Strain Field and Detection of Regional Crustal Deformation

    Directory of Open Access Journals (Sweden)

    XU Keke

    2016-08-01

    Full Text Available Using GNSS data,the estimation model for GNSS multiscale strain field was established based on spherical wavelet. The key technologies for wavelet center location, wavelet scale choices and regularization parameter calculation were discussed in detail. For further testing the correctness of the model, the simulated data in locked fault areas was generated according to negative dislocation theory. With spherical wavelet model, the strain field in locked strike-slip fault areas was estimated,and the results agreed well with the characteristics of actual crustal deformation. Meanwhile, the experiments on crustal deformation anomaly detection with multiscale strain field were completed. The results showed that the small fault deformation of 50 km appeared obviously in the small scale(8th scale stain field, but there wasn't signals in the large scale (4 to 7 scale. The large fault deformation of 150 km only showed a part of information in the small scale (8th scale stain field, but showed more completely and clearly in the large scale(4 to 7 scale.So it's concluded that crustal deformation of different spatial coverage scope embody in the different scales strain field, and the small scale strain field have the ability to detect regional deformation anomaly.

  19. Maximum-entropy expectation-maximization algorithm for image reconstruction and sensor field estimation.

    Science.gov (United States)

    Hong, Hunsop; Schonfeld, Dan

    2008-06-01

    In this paper, we propose a maximum-entropy expectation-maximization (MEEM) algorithm. We use the proposed algorithm for density estimation. The maximum-entropy constraint is imposed for smoothness of the estimated density function. The derivation of the MEEM algorithm requires determination of the covariance matrix in the framework of the maximum-entropy likelihood function, which is difficult to solve analytically. We, therefore, derive the MEEM algorithm by optimizing a lower-bound of the maximum-entropy likelihood function. We note that the classical expectation-maximization (EM) algorithm has been employed previously for 2-D density estimation. We propose to extend the use of the classical EM algorithm for image recovery from randomly sampled data and sensor field estimation from randomly scattered sensor networks. We further propose to use our approach in density estimation, image recovery and sensor field estimation. Computer simulation experiments are used to demonstrate the superior performance of the proposed MEEM algorithm in comparison to existing methods.

  20. Stationary variational estimates for the effective response and field fluctuations in nonlinear composites

    Science.gov (United States)

    Ponte Castañeda, Pedro

    2016-11-01

    This paper presents a variational method for estimating the effective constitutive response of composite materials with nonlinear constitutive behavior. The method is based on a stationary variational principle for the macroscopic potential in terms of the corresponding potential of a linear comparison composite (LCC) whose properties are the trial fields in the variational principle. When used in combination with estimates for the LCC that are exact to second order in the heterogeneity contrast, the resulting estimates for the nonlinear composite are also guaranteed to be exact to second-order in the contrast. In addition, the new method allows full optimization with respect to the properties of the LCC, leading to estimates that are fully stationary and exhibit no duality gaps. As a result, the effective response and field statistics of the nonlinear composite can be estimated directly from the appropriately optimized linear comparison composite. By way of illustration, the method is applied to a porous, isotropic, power-law material, and the results are found to compare favorably with earlier bounds and estimates. However, the basic ideas of the method are expected to work for broad classes of composites materials, whose effective response can be given appropriate variational representations, including more general elasto-plastic and soft hyperelastic composites and polycrystals.

  1. Estimation of soil moisture in paddy field using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Chusnul Arif

    2012-04-01

    Full Text Available In paddy field, monitoring soil moisture is required for irrigation scheduling and water resource allocation, management and planning. The current study proposes an Artificial Neural Networks (ANN model to estimate soil moisture in paddy field with limited meteorological data. Dynamic of ANN model was adopted to estimate soil moisture with the inputs of reference evapotranspiration (ETo and precipitation. ETo was firstly estimated using the maximum, average and minimum values of air temperature as the inputs of model. The models were performed under different weather conditions between the two paddy cultivation periods. Training process of model was carried out using the observation data in the first period, while validation process was conducted based on the observation data in the second period. Dynamic of ANN model estimated soil moisture with R2 values of 0.80 and 0.73 for training and validation processes, respectively, indicated that tight linear correlations between observed and estimated values of soil moisture were observed. Thus, the ANN model reliably estimates soil moisture with limited meteorological data.

  2. Estimating a planetary magnetic field with time-dependent global MHD simulations using an adjoint approach

    Science.gov (United States)

    Nabert, Christian; Othmer, Carsten; Glassmeier, Karl-Heinz

    2017-05-01

    The interaction of the solar wind with a planetary magnetic field causes electrical currents that modify the magnetic field distribution around the planet. We present an approach to estimating the planetary magnetic field from in situ spacecraft data using a magnetohydrodynamic (MHD) simulation approach. The method is developed with respect to the upcoming BepiColombo mission to planet Mercury aimed at determining the planet's magnetic field and its interior electrical conductivity distribution. In contrast to the widely used empirical models, global MHD simulations allow the calculation of the strongly time-dependent interaction process of the solar wind with the planet. As a first approach, we use a simple MHD simulation code that includes time-dependent solar wind and magnetic field parameters. The planetary parameters are estimated by minimizing the misfit of spacecraft data and simulation results with a gradient-based optimization. As the calculation of gradients with respect to many parameters is usually very time-consuming, we investigate the application of an adjoint MHD model. This adjoint MHD model is generated by an automatic differentiation tool to compute the gradients efficiently. The computational cost for determining the gradient with an adjoint approach is nearly independent of the number of parameters. Our method is validated by application to THEMIS (Time History of Events and Macroscale Interactions during Substorms) magnetosheath data to estimate Earth's dipole moment.

  3. Estimating field scale root zone soil moisture using the cosmic-ray neutron probe

    Science.gov (United States)

    Peterson, A. M.; Helgason, W. D.; Ireson, A. M.

    2015-12-01

    Many practical hydrological, meteorological and agricultural management problems require estimates of soil moisture with an areal footprint equivalent to "field scale", integrated over the entire root zone. The cosmic-ray neutron probe is a promising instrument to provide field scale areal coverage, but these observations are shallow and require depth scaling in order to be considered representative of the entire root zone. A study to identify appropriate depth-scaling techniques was conducted at a grazing pasture site in central Saskatchewan, Canada over a two year period. Area-averaged soil moisture was assessed using a cosmic-ray neutron probe. Root zone soil moisture was measured at 21 locations within the 5002 m2 area, using a down-hole neutron probe. The cosmic-ray neutron probe was found to provide accurate estimates of field scale surface soil moisture, but accounted for less than 40 % of the seasonal change in root zone storage due to its shallow measurement depth. The root zone estimation methods evaluated were: (1) the coupling of the cosmic-ray neutron probe with a time stable neutron probe monitoring location, (2) coupling the cosmic-ray neutron probe with a representative landscape unit monitoring approach, and (3) convolution of the cosmic-ray neutron probe measurements with the exponential filter. The time stability method provided the best estimate of root zone soil moisture (RMSE = 0.004 cm3 cm-3), followed by the exponential filter (RMSE = 0.012 cm3 cm-3). The landscape unit approach, which required no calibration, had a negative bias but estimated the cumulative change in storage reasonably. The feasibility of applying these methods to field sites without existing instrumentation is discussed. It is concluded that the exponential filter method has the most potential for estimating root zone soil moisture from cosmic-ray neutron probe data.

  4. Du Pont Classification of ASASSN-16jc as a Young SN Ia

    Science.gov (United States)

    Shappee, Benjamin J.; Prieto, J. L.; Rich, J.; Seibert, M.; Madore, B.; Poetrodjojo, Henry; D'Agostino, Joshua

    2016-08-01

    We report optical spectroscopy (range 370-910 nm) of ASASSN-16jc discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014, ApJ, 788, 48) using the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory on Aug. 24 2016 UT. We performed a cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024).

  5. Quantum Information and Entropy Spueezing of a Nonlinear Multiquantum JC Model

    Institute of Scientific and Technical Information of China (English)

    Mahmoud Abdel-Aty

    2002-01-01

    We investigate the entropy squeezing of the nonlinear k-quantum JC model. A definition of squeezing is presented for this system based on the quantum information theory. The utility of the definition is illustrated by examining squeezing in the information entropy of a nonlinear k-quantum two-level atom. The influence of the atomic coherence and the detuning parameter on the properties of the information entropy and squeezing of the atomic variables is examined.

  6. Theoretical estimates of maximum fields in superconducting resonant radio frequency cavities: Stability theory, disorder, and laminates

    CERN Document Server

    Liarte, Danilo B; Transtrum, Mark K; Catelani, Gianluigi; Liepe, Matthias; Sethna, James P

    2016-01-01

    We review our work on theoretical limits to the performance of superconductors in high magnetic fields parallel to their surfaces. These limits are of key relevance to current and future accelerating cavities, especially those made of new higher-$T_c$ materials such as Nb$_3$Sn, NbN, and MgB$_2$. We summarize our calculations of the so-called superheating field $H_{\\mathrm{sh}}$, beyond which flux will spontaneously penetrate even a perfect superconducting surface and ruin the performance. We briefly discuss experimental measurements of the superheating field, comparing to our estimates. We explore the effects of materials anisotropy and disorder. Will we need to control surface orientation in the layered compound MgB$_2$? Can we estimate theoretically whether dirt and defects make these new materials fundamentally more challenging to optimize than niobium? Finally, we discuss and analyze recent proposals to use thin superconducting layers or laminates to enhance the performance of superconducting cavities. T...

  7. The limiting behavior of the estimated parameters in a misspecified random field regression model

    DEFF Research Database (Denmark)

    Dahl, Christian Møller; Qin, Yu

    convenient new uniform convergence results that we propose. This theory may have applications beyond those presented here. Our results indicate that classical statistical inference techniques, in general, works very well for random field regression models in finite samples and that these models succesfully......This paper examines the limiting properties of the estimated parameters in the random field regression model recently proposed by Hamilton (Econometrica, 2001). Though the model is parametric, it enjoys the flexibility of the nonparametric approach since it can approximate a large collection...... of nonlinear functions and it has the added advantage that there is no "curse of dimensionality."Contrary to existing literature on the asymptotic properties of the estimated parameters in random field models our results do not require that the explanatory variables are sampled on a grid. However...

  8. Thickness dependence of Jc (0) in MgB2 films

    Science.gov (United States)

    Chen, Yiling; Yang, Can; Jia, Chunyan; Feng, Qingrong; Gan, Zizhao

    2016-06-01

    MgB2 superconducting films, whose thicknesses range from 10 nm to 8 μm, have been fabricated on SiC substrates by hybrid physical-chemical vapor deposition (HPCVD) method. It is the first time that the Tc and the Jc of MgB2 films are studied on such a large scale. It is found that with the increasing of thickness, Tc elevates first and then keeps roughly stable except for some slight fluctuations, while Jc (5 K, 0 T) experiences a sharp increase followed by a relatively slow fall. The maximum Jc (5 K, 0 T) = 2.3 × 108 A cm-2 is obtained for 100 nm films, which is the experimental evidence for preparing high-quality MgB2 films by HPCVD method. Thus, this work may provide guidance on choosing the suitable thickness for applications. Meanwhile, the films prepared by us cover ultrathin films, thin films and thick films, so the study on them will bring a comprehensive understanding of MgB2 films.

  9. Isolation and application of Gordonia sp. JC11 for removal of boat lubricants.

    Science.gov (United States)

    Chanthamalee, Jirapat; Luepromchai, Ekawan

    2012-01-01

    Boat lubricants are continuously released into the marine environment and thereby cause chronic oil pollution. This study aims to isolate lubricant-degrading microorganisms from Thai coastal areas as well as to apply a selected strain for removal of boat lubricants. Ten microorganisms in the genera of Gordonia, Microbacterium, Acinetobacter, Pseudomonas, Brucella, Enterococcus and Candida were initially isolated by crude oil enrichment culture techniques. The lubricant-removal activity of these isolates was investigated with mineral-based lubricants that had been manufactured for the 4-stroke diesel engines of fishing boats. Gordonia sp. JC11, the most effective strain was able to degrade 25-55% of 1,000 mg L(-1) total hydrocarbons in six tested lubricants, while only 0-15% of the lubricants was abiotically removed. The bacterium had many characteristics that promoted lubricant degradation such as hydrocarbon utilization ability, emulsification activity and cell surface hydrophobicity. For bioaugmentation treatment of lubricant contaminated seawater, the inoculum of Gordonia sp. JC11 was prepared by immobilizing the bacterium on polyurethane foam (PUF). PUF-immobilized Gordonia sp. JC11 was able to remove 42-56% of 100-1,000 mg L(-1) waste lubricant No. 2 within 5 days. This lubricant removal efficiency was higher than those of free cells and PUF without bacterial cells. The bioaugmentation treatment significantly increased the number of lubricant-degrading microorganisms in the fishery port seawater microcosm and resulted in rapid removal of waste lubricant No. 2.

  10. Ectopic Expression of JcWRKY Transcription Factor Confers Salinity Tolerance via Salicylic Acid Signaling

    Science.gov (United States)

    Agarwal, Parinita; Dabi, Mitali; Sapara, Komal K.; Joshi, Priyanka S.; Agarwal, Pradeep K.

    2016-01-01

    Plants, being sessile, have developed intricate signaling network to specifically respond to the diverse environmental stress. The plant-specific WRKY TFs form one of the largest TF family and are involved in diverse plant processes, involving growth, development and stress signaling through auto and cross regulation with different genes and TFs. Here, we report the functional characterization of a salicylic acid -inducible JcWRKY TF. The JcWRKY overexpression confers salinity tolerance in transgenic tobacco, as was evident by increased chlorophyll content and seed germination potential. The transgenic plants showed increased soluble sugar, membrane stability, reduced electrolyte leakage and generation of reactive oxygen species (H2O2 and O2•-) as compared to the wild type. Furthermore, the low SA treatment along with salinity improved the tolerance potential of the transgenics by maintaining ROS homeostasis and high K+/Na+ ratio. The transcript expression of SA biosynthetic gene ICS1 and antioxidative enzymes (CAT and SOD) showed upregulation during stress. Thus, the present study reflects that JcWRKY is working in co-ordination with SA signaling to orchestrate the different biochemical and molecular pathways to maneuvre salt stress tolerance of the transgenic plants. PMID:27799936

  11. Considerations for estimating microbial environmental data concentrations collected from a field setting.

    Science.gov (United States)

    Silvestri, Erin E; Yund, Cynthia; Taft, Sarah; Bowling, Charlena Yoder; Chappie, Daniel; Garrahan, Kevin; Brady-Roberts, Eletha; Stone, Harry; Nichols, Tonya L

    2017-03-01

    In the event of an indoor release of an environmentally persistent microbial pathogen such as Bacillus anthracis, the potential for human exposure will be considered when remedial decisions are made. Microbial site characterization and clearance sampling data collected in the field might be used to estimate exposure. However, there are many challenges associated with estimating environmental concentrations of B. anthracis or other spore-forming organisms after such an event before being able to estimate exposure. These challenges include: (1) collecting environmental field samples that are adequate for the intended purpose, (2) conducting laboratory analyses and selecting the reporting format needed for the laboratory data, and (3) analyzing and interpreting the data using appropriate statistical techniques. This paper summarizes some key challenges faced in collecting, analyzing, and interpreting microbial field data from a contaminated site. Although the paper was written with considerations for B. anthracis contamination, it may also be applicable to other bacterial agents. It explores the implications and limitations of using field data for determining environmental concentrations both before and after decontamination. Several findings were of interest. First, to date, the only validated surface/sampling device combinations are swabs and sponge-sticks on stainless steel surfaces, thus limiting availability of quantitative analytical results which could be used for statistical analysis. Second, agreement needs to be reached with the analytical laboratory on the definition of the countable range and on reporting of data below the limit of quantitation. Finally, the distribution of the microbial field data and statistical methods needed for a particular data set could vary depending on these data that were collected, and guidance is needed on appropriate statistical software for handling microbial data. Further, research is needed to develop better methods to

  12. A comparison of instrumentation methods to estimate thoracolumbar motion in field-based occupational studies.

    Science.gov (United States)

    Schall, Mark C; Fethke, Nathan B; Chen, Howard; Gerr, Fred

    2015-05-01

    The performance of an inertial measurement unit (IMU) system for directly measuring thoracolumbar trunk motion was compared to that of the Lumbar Motion Monitor (LMM). Thirty-six male participants completed a simulated material handling task with both systems deployed simultaneously. Estimates of thoracolumbar trunk motion obtained with the IMU system were processed using five common methods for estimating trunk motion characteristics. Results of measurements obtained from IMUs secured to the sternum and pelvis had smaller root-mean-square differences and mean bias estimates in comparison to results obtained with the LMM than results of measurements obtained solely from a sternum mounted IMU. Fusion of IMU accelerometer measurements with IMU gyroscope and/or magnetometer measurements was observed to increase comparability to the LMM. Results suggest investigators should consider computing thoracolumbar trunk motion as a function of estimates from multiple IMUs using fusion algorithms rather than using a single accelerometer secured to the sternum in field-based studies.

  13. Using thermal tracers to estimate flow velocities of shallow flows: laboratory and field experiments

    Directory of Open Access Journals (Sweden)

    Lima Rui L.P. de

    2015-09-01

    Full Text Available Accurate measurement of shallow flows is important for hydraulics, hydrology and water resources management. The objective of this paper is to discuss a technique for shallow flow and overland flow velocity estimation that uses infrared thermography. Laboratory flumes and different bare, vegetated and paved field surfaces were used to test the technique. Results show that shallow flow surface velocities estimated using thermal tracers and infrared technology are similar to estimates obtained using the Acoustic Doppler Velocimeter; similar results were also obtained for overland flow velocity estimates using thermography, here comparing with the dye tracer technique. The thermographic approach revealed some potential as a flow visualization technique, and leaves space for future studies and research.

  14. Estimation of the effects of strong static magnetic fields on plants.

    Science.gov (United States)

    Kuznetsov, O.

    In our recent studies we extensively used ponderomotive magnetic forces in high gradient magnetic fields (HGMF) for displacing organelles inside plant gravity receptor cells. Such displacement is a convenient tool both for investigating plant gravity perception mechanism and for physical characterization of the cell interior, and can have future practical applications in providing a directional stimulus for plants in microgravity. This method takes advantage of the magnetic heterogeneity of the receptor cells, namely stronger diamagnetism of starch-filled amyloplasts compared to cytoplasm (? æ < 0). Such particles are repelled from the zones of stronger field in a non-uniform field. To exert a force on amyloplasts, which is comparable to the gravity force, the dynamic factor of the field grad(H2 /2) needs to be 109 - 1 01 0 Oe 2 /cm, and the field intensity in the experimental magnetic systems typically varies from 0 to 2.5-104 Oe, while the size of the area of non-uniformity is 10-2 to 1 cm. Possible effects of such static magnetic fields on plants other than magnetophoresis of amyloplasts were estimated theoretically and tested experimentally. No statistically significant differences in growth rates or rates of gravicurvature were observed in experiments with Linum, Arabidopsis, Hordeum, Avena, Ceratodon and Chara between the plants grown in uniform magnetic fields of various intensities (102 to 2.5-104 Oe) and those grown in the Earth's magnetic field. Microscopic studies also did not detect any structural differences between test and control plants. The magnitudes of possible effects of static magnetic fields on plant cells and organs (including effects on ion currents, magneto-hydrodynamic effects in moving cytoplasm, ponderomotive forces on other cellular structures, effects on some biochemical reactions and biomolecules) were estimated theoretically. The estimations have shown, that these effects are small compared to the thermodynamic noise and thus are

  15. Estimation of Near-Field and Far-Field Dilutions for Site Selection of Effluent Outfall in a Coastal Region - A Case Study

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, V.S.

    location for discharge of the effluents into the sea by using near-field and far-field models. Near-field dilutions were calculated using a buoyant jet model, whereas far-field dilutions were estimated using a two-dimensional numerical model. As a case...

  16. Class-specific weighting for Markov random field estimation: application to medical image segmentation.

    Science.gov (United States)

    Monaco, James P; Madabhushi, Anant

    2012-12-01

    Many estimation tasks require Bayesian classifiers capable of adjusting their performance (e.g. sensitivity/specificity). In situations where the optimal classification decision can be identified by an exhaustive search over all possible classes, means for adjusting classifier performance, such as probability thresholding or weighting the a posteriori probabilities, are well established. Unfortunately, analogous methods compatible with Markov random fields (i.e. large collections of dependent random variables) are noticeably absent from the literature. Consequently, most Markov random field (MRF) based classification systems typically restrict their performance to a single, static operating point (i.e. a paired sensitivity/specificity). To address this deficiency, we previously introduced an extension of maximum posterior marginals (MPM) estimation that allows certain classes to be weighted more heavily than others, thus providing a means for varying classifier performance. However, this extension is not appropriate for the more popular maximum a posteriori (MAP) estimation. Thus, a strategy for varying the performance of MAP estimators is still needed. Such a strategy is essential for several reasons: (1) the MAP cost function may be more appropriate in certain classification tasks than the MPM cost function, (2) the literature provides a surfeit of MAP estimation implementations, several of which are considerably faster than the typical Markov Chain Monte Carlo methods used for MPM, and (3) MAP estimation is used far more often than MPM. Consequently, in this paper we introduce multiplicative weighted MAP (MWMAP) estimation-achieved via the incorporation of multiplicative weights into the MAP cost function-which allows certain classes to be preferred over others. This creates a natural bias for specific classes, and consequently a means for adjusting classifier performance. Similarly, we show how this multiplicative weighting strategy can be applied to the MPM

  17. JC virus-associated central nervous system diseases in HIV-infected patients in Brazil: clinical presentations, associated factors with mortality and outcome

    Directory of Open Access Journals (Sweden)

    Felipe Piza

    Full Text Available INTRODUCTION: Several presentations of neurologic complications caused by JC virus (JCV in human immunodeficiency virus (HIV-infected patients have been described and need to be distinguished from the "classic" form of progressive multifocal leukoencephalopathy (PMl. The objectives of this study were: 1 to describe the spectrum and frequency of presentations of JCV-associated central nervous system (CNS diseases; 2 identify factors associated with in-hospital mortality of patients with JCV-associated CNS disease; and 3 to estimate the overall mortality of this population. MATERIAL AND METHODS: This was a retrospective study of HIV-infected patients admitted consecutively for JCVassociated CNS diseases in a referral teaching center in São Paulo, Brazil, from 2002 to 2007. All patients with laboratory confirmed JCV-associated CNS diseases were included using the following criteria: compatible clinical and radiological features associated with the presence of JCV DNA in the cerebrospinal fluid. JCV-associated CNS diseases were classified as follows: 1 classic PMl; 2 inflammatory PMl; and 3 JC virus granule cell neuronopathy (GCN. RESULTS: We included 47 cases. JCV-associated CNS diseases were classified as follows: 1 classic PMl: 42 (89%; 2 inflammatory PMl: three (6%; and 3 JC virus GCN: four (9%. Nosocomial pneumonia (p = 0.003, previous diagnosis of HIV infection (p = 0.03, and imaging showing cerebellar and/or brainstem involvement (p = 0.02 were associated with in-hospital mortality. overall mortality during hospitalization was 34%. CONCLUSIONS: Novel presentations of JCV-associated CNS diseases were observed in our setting; nosocomial pneumonia, previous diagnosis of HIV infection, and cerebellar and/or brainstem involvement were associated with in-hospital mortality; and overall mortality was high.

  18. Dose estimation outside radiation field using Pinpoint and Semiflex ionization chamber detectors

    Science.gov (United States)

    Abdelaal, Ahmed M.; Attalla, Ehab M.; Elshemey, Wael M.

    2017-10-01

    This work aims to provide a comparison between two important detectors (Pinpoint and Semiflex) that are frequently used in radiation dosimetery in radiotherapy. This is carried out through the employment of both detectors in a quantitative estimation of the change in out-of-field dose with important dosimetric parameters such as field size (from 5×5 cm2 to 30×30 cm2) and depth (from 1.5 cm to 30 cm) at two different energies (6 MV and 15 MV) and two different collimator angles (0-90°). The change in out-of-field dose with Source-Skin-Distance (SSD) from 80 to 115 cm is also studied using both detectors. Results show that, the Pinpoint and Semiflex detectors both reported an increase in out-of-field dose with field size, depth, energy and SSD. In almost all measurements, Pinpoint detector reported considerably higher out-of-field dose values compared to Semiflex. For 6 MV and 0° collimator angle, the out-of-field dose at field size of 30×30 cm2 and at a depth of 1.5 cm is 7.3% for Pinpoint detector compared to 4.3% for Semiflex. At collimator angle of 90°, the out-of-field dose is 6.5% for Pinpoint detector compared to 5.5% for semiflex. The out-of-field dose for a depth of 30 cm and field size of 10×10 cm is 7.9% for Pinpoint detector compared to 5.9% for Semiflex. For 15 MV and 0° collimator angle, the out-of-field dose at field size of 30×30 cm2 and at a depth of 1.5 cm is 7.5% for Pinpoint detector compared 5.1% for Semiflex. At 6 MV, field size of 10×10 cm2 and depth of 1.5 cm, the out-of-field dose at SSD 115 cm is 3.7% for Pinpoint detector compared to 3.4% for Semiflex. The considerably higher out-of-field dose values reported by Pinpoint detector compared to Semiflex may be attributed to the relatively higher sensitivity of Pinpoint detector for low doses (such as out-of-field doses). Therefore, for reliable out-of-field dose measurements a Pinpoint detector is highly recommended.

  19. Estimating parameters of aquifer heterogeneity using pumping tests - implications for field applications

    Science.gov (United States)

    Zech, Alraune; Arnold, Sven; Schneider, Christoph; Attinger, Sabine

    2015-09-01

    The knowledge of subsurface heterogeneity is a prerequisite to describe flow and transport in porous media. Of particular interest are the variance and the correlation scale of hydraulic conductivity. In this study, we present how these aquifer parameters can be inferred using empirical steady state pumping test data. We refer to a previously developed analytical solution of "effective well flow" and examine its applicability to pumping test data as under field conditions. It is examined how the accuracy and confidence of parameter estimates of variance and correlation length depend on the number and location of head measurements. Simulations of steady state pumping tests in a confined virtual aquifer are used to systematically reduce sampling size while determining the rating of the estimates at each level of data density. The method was then applied to estimate the statistical parameters of a fluvial heterogeneous aquifer at the test site Horkheimer Insel, Germany. We conclude that the "effective well flow" solution is a simple alternative to laboratory investigations to estimate the statistical heterogeneity parameter using steady state pumping tests. However, the accuracy and uncertainty of the estimates depend on the design of the field study. In this regard, our results can help to improve the conceptual design of pumping tests with regard to the parameter of interest.

  20. PSF Estimation of Space-Variant Ultra-Wide Field of View Imaging Systems

    Directory of Open Access Journals (Sweden)

    Petr Janout

    2017-02-01

    Full Text Available Ultra-wide-field of view (UWFOV imaging systems are affected by various aberrations, most of which are highly angle-dependent. A description of UWFOV imaging systems, such as microscopy optics, security camera systems and other special space-variant imaging systems, is a difficult task that can be achieved by estimating the Point Spread Function (PSF of the system. This paper proposes a novel method for modeling the space-variant PSF of an imaging system using the Zernike polynomials wavefront description. The PSF estimation algorithm is based on obtaining field-dependent expansion coefficients of the Zernike polynomials by fitting real image data of the analyzed imaging system using an iterative approach in an initial estimate of the fitting parameters to ensure convergence robustness. The method is promising as an alternative to the standard approach based on Shack–Hartmann interferometry, since the estimate of the aberration coefficients is processed directly in the image plane. This approach is tested on simulated and laboratory-acquired image data that generally show good agreement. The resulting data are compared with the results of other modeling methods. The proposed PSF estimation method provides around 5% accuracy of the optical system model.

  1. Estimates for Parameters and Characteristics of the Confining SU(3)-gluonic Field in $\\phi$-meson from Leptonic Widths

    CERN Document Server

    Goncharov, Yu P

    2014-01-01

    The paper is devoted to applying the confinement mechanism proposed earlier by one of the authors to estimate the possible parameters of the confining SU(3)-gluonic field in vector $\\phi$-meson. The estimates obtained are consistent with the leptonic widths of the given meson. The corresponding estimates of the gluon concentrations, electric and magnetic colour field strengths are also adduced for the mentioned field at the scales of the meson under consideration.

  2. Multiplicative intrinsic component optimization (MICO) for MRI bias field estimation and tissue segmentation.

    Science.gov (United States)

    Li, Chunming; Gore, John C; Davatzikos, Christos

    2014-09-01

    This paper proposes a new energy minimization method called multiplicative intrinsic component optimization (MICO) for joint bias field estimation and segmentation of magnetic resonance (MR) images. The proposed method takes full advantage of the decomposition of MR images into two multiplicative components, namely, the true image that characterizes a physical property of the tissues and the bias field that accounts for the intensity inhomogeneity, and their respective spatial properties. Bias field estimation and tissue segmentation are simultaneously achieved by an energy minimization process aimed to optimize the estimates of the two multiplicative components of an MR image. The bias field is iteratively optimized by using efficient matrix computations, which are verified to be numerically stable by matrix analysis. More importantly, the energy in our formulation is convex in each of its variables, which leads to the robustness of the proposed energy minimization algorithm. The MICO formulation can be naturally extended to 3D/4D tissue segmentation with spatial/sptatiotemporal regularization. Quantitative evaluations and comparisons with some popular softwares have demonstrated superior performance of MICO in terms of robustness and accuracy.

  3. ESTIMATE OF METHANE EMISSIONS FROM RICE FIELDS IN CHINA BY CLIMATE-BASED NET PRIMARY PRODUCTIVITY

    Institute of Scientific and Technical Information of China (English)

    KANG Guo-ding; CAI Zu-cong; ZHANG Zi-heng; XIAO Peng-feng

    2004-01-01

    Rice fields provide food for over half of the world population but are also an important source of atmospheric CH4. Using the climate-based GIS empirical model and the meteorological data collected from 600 meteorological stations in China, with county as the basic unit, the net primary productivity (NPP) of rice fields in China in 1990, 1995, 1998, and 2000 were estimated to be in the range from 202.19×1012g C in 1990 to 163.46×1012g C in 2000. From the measured data of the factors affecting CH4 emission and NPP, the conversion ratio of the NPP into CH4 emission for the rice fields of China was determined to be 1.8%. Using this ratio and estimated NPP, the CH4 emissions from rice fields of China in 1990, 1995, 1998, and 2000 were estimated to be 7.24×1012, 6.31×1012, 6.77×1012 and 5.85×1012g CH4, respectively.

  4. Estimating Field Scale Crop Evapotranspiration using Landsat and MODIS Satellite Observations

    Science.gov (United States)

    Wong, A.; Jin, Y.; Snyder, R. L.; Daniele, Z.; Gao, F.

    2016-12-01

    Irrigation accounts for 80% of human freshwater consumption, and most of it return to the atmosphere through Evapotranspiration (ET). Given the challenges of already-stressed water resources and ground water regulation in California, a cost-effective, timely, and consistent spatial estimate of crop ET, from the farm to watershed level, is becoming increasingly important. The Priestley-Taylor (PT) approach, calibrated with field data and driven by satellite observations, shows great promise for accurate ET estimates across diverse ecosystems. We here aim to improve the robustness of the PT approach in agricultural lands, to enable growers and farm managers to tailor irrigation management based on in-field spatial variability and in-season variation. We optimized the PT coefficients for each crop type with available ET measurements from eddy covariance towers and/or surface renewal stations at six crop fields (Alfalfa, Almond, Citrus, Corn, Pistachio and Rice) in California. Good agreement was found between satellite-based estimates and field measurements of net radiation, with a RMSE of less than 36 W m-2. The crop type specific optimization performed well, with a RMSE of 30 W m-2 and a correlation of 0.81 for predicted daily latent heat flux. The calibrated algorithm was used to estimate ET at 30 m resolution over the Sacramento-San Joaquin Delta region for 2015 water year. It captures well the seasonal dynamics and spatial distribution of ET in Sacramento-San Joaquin Delta. A continuous monitoring of the dynamics and spatial heterogeneity of canopy and consumptive water use at a field scale, will help the growers to be well prepared and informed to adaptively manage water, canopy, and grove density to maximize the yield with the least amount of water.

  5. A precise numerical estimation of the magnetic field generated around recombination

    CERN Document Server

    Fidler, Christian; Pitrou, Cyril

    2015-01-01

    We investigate the generation of magnetic fields from non-linear effects around recombination. As tight-coupling is gradually lost when approaching $z\\simeq 1100$, the velocity difference between photons and baryons starts to increase, leading to an increasing Compton drag of the photons on the electrons. The protons are then forced to follow the electrons due to the electric field created by the charge displacement; the same field, following Maxwell's laws, eventually induces a magnetic field on cosmological scales. Since scalar perturbations do not generate any magnetic field as they are curl-free, one has to resort to second-order perturbation theory to compute the magnetic field generated by this effect. We reinvestigate this problem numerically using the powerful second-order Boltzmann code SONG. We show that: i) all previous studies do not have a high enough angular resolution to reach a precise and consistent estimation of the magnetic field spectrum; ii) the magnetic field is generated up to $z\\simeq ...

  6. An Algorithm for Joint Estimating Range, DOA and Frequency of Near-Field Sources

    Institute of Scientific and Technical Information of China (English)

    CHENJianfeng; ZHANGXianda; WUYuntao

    2004-01-01

    Most of the existing eigen-decomposition based localization methods make the plane wave assumption in order to estimate the signal parameters of multiple sources. This paper proposes a novel joint algorithm for ranges, DOA's and frequencies of multiple narrow-band sources with the sources in the near field. This algorithm uses the Estimating signal parameters via rotational invariance technique (ESPRIT) based on cumulant-domain signal subspaces. The new algorithm does not require searching spectral peak or pairing among parameters, and has the power to resist an additive Gaussian noise due to use of the fourth-order cumulants. The performance of the new algorithm is confirmed by computer simulations.

  7. Field Oriented Control for Rotor Position Estimation of IPM Drives over a Wide Speed Range

    Directory of Open Access Journals (Sweden)

    Ekhlas Kadhum

    2013-01-01

    Full Text Available Field oriented control strategy of Interior Permanent Magnet IPM Synchronous Motor drives over a wide speed range applications is presented. Rotor position estimation using model reference adaptive system method for IPM Drive without using a mechanical sensor is illustrated considering the effects of cross-saturation between the d and q axes. The cross saturation between d and q axes has been calculated by finite-element analysis. The inductance measurement regards the cross saturation which is used to obtain the suitable id - characteristics in base and flux weakening regions. The simulation results show that rotor position estimation error accuracy was improved. Various dynamic conditions have been investigated

  8. A New Algorithm for Joint Range-DOA-Frequency Estimation of Near-Field Sources

    Directory of Open Access Journals (Sweden)

    Jian-Feng Chen

    2004-03-01

    Full Text Available This paper studies the joint estimation problem of ranges, DOAs, and frequencies of near-field narrowband sources and proposes a new computationally efficient algorithm, which employs a symmetric uniform linear array, uses eigenvalues together with the corresponding eigenvectors of two properly designed matrices to estimate signal parameters, and does not require searching for spectral peak or pairing among parameters. In addition, the proposed algorithm can be applied in arbitrary Gaussian noise environment since it is based on the fourth-order cumulants, which is verified by extensive computer simulations.

  9. Robust algorithm of direction of arrival estimation for coherent wideband sources in unknown correlated noise fields

    Institute of Scientific and Technical Information of China (English)

    TENG Pengxiao; MA Chizhou; YANG Yichun; LI Xiaodong

    2007-01-01

    A robust algorithm of direction of arrival (DOA) estimation for coherent wideband sources in unknown correlated noise fields was investigated. The noise is usually unknown and correlated among sensors in practical applications, especially for arrays with comparatively small apertures. The spatially correlated noise incurs an increase in focusing error and a severe degradation in the DOA estimation, and therefore a method of focusing transformation based on differentiating covariance matrix was proposed to eliminate noise, hence reduce the focusing error. The simulation and experimental results demonstrate the effectiveness of the proposed method.

  10. A New Method for Radar Rainfall Estimation Using Merged Radar and Gauge Derived Fields

    Science.gov (United States)

    Hasan, M. M.; Sharma, A.; Johnson, F.; Mariethoz, G.; Seed, A.

    2014-12-01

    Accurate estimation of rainfall is critical for any hydrological analysis. The advantage of radar rainfall measurements is their ability to cover large areas. However, the uncertainties in the parameters of the power law, that links reflectivity to rainfall intensity, have to date precluded the widespread use of radars for quantitative rainfall estimates for hydrological studies. There is therefore considerable interest in methods that can combine the strengths of radar and gauge measurements by merging the two data sources. In this work, we propose two new developments to advance this area of research. The first contribution is a non-parametric radar rainfall estimation method (NPZR) which is based on kernel density estimation. Instead of using a traditional Z-R relationship, the NPZR accounts for the uncertainty in the relationship between reflectivity and rainfall intensity. More importantly, this uncertainty can vary for different values of reflectivity. The NPZR method reduces the Mean Square Error (MSE) of the estimated rainfall by 16 % compared to a traditionally fitted Z-R relation. Rainfall estimates are improved at 90% of the gauge locations when the method is applied to the densely gauged Sydney Terrey Hills radar region. A copula based spatial interpolation method (SIR) is used to estimate rainfall from gauge observations at the radar pixel locations. The gauge-based SIR estimates have low uncertainty in areas with good gauge density, whilst the NPZR method provides more reliable rainfall estimates than the SIR method, particularly in the areas of low gauge density. The second contribution of the work is to merge the radar rainfall field with spatially interpolated gauge rainfall estimates. The two rainfall fields are combined using a temporally and spatially varying weighting scheme that can account for the strengths of each method. The weight for each time period at each location is calculated based on the expected estimation error of each method

  11. Experience of Controlling JC 7.3 tex Elastic Fabric Wrinkle%JC7.3tex弹力织物褶皱控制体会

    Institute of Scientific and Technical Information of China (English)

    邵利韬; 张绍森; 闫海江

    2013-01-01

    Measures of controlling fabric wrinkle on air jet loom in weaving JC 7. 3 tex elastic fabric were discussed. Causes and features of fabric wrinkle were analyzed, related processing parameters were adopted including adjustment of loom shed time,loom tension and back beam height. Steam yarn was adopted for different weft. It is pointed out the effective measures of controlling fabric wrinkles are setting weft twist,using double weft accumulator,ensuring air pressure and loom tension stable et al. Fabric wrinkles can be eliminated completely through adopting related measures from several aspects, including processing, equipment and operations when producing fine and high density elastic fabric on air jet loom.%探讨在喷气织机上织造JC 7.3 tex弹力织物时布面起皱的控制措施.分析了褶皱的外观特征和产生原因,采取了调整织机开口时间、上机张力、后梁高度等工艺参数;使用不同库存时间的纬纱,使用蒸纱定捻的纬纱等措施,指出:控制弹力织物褶皱的有效方法是对纬纱定捻、使用双储纬器、保证气压和上机张力稳定等;在喷气织机上织造细号高密弹力织物时,只要从工艺、设备、操作等方面采取措施,即可彻底杜绝弹力织物布面褶皱现象.

  12. The limiting behavior of the estimated parameters in a misspecified random field regression model

    DEFF Research Database (Denmark)

    Dahl, Christian Møller; Qin, Yu

    , as a consequence the random field model specification introduces non-stationarity and non-ergodicity in the misspecified model and it becomes non-trivial, relative to the existing literature, to establish the limiting behavior of the estimated parameters. The asymptotic results are obtained by applying some...... convenient new uniform convergence results that we propose. This theory may have applications beyond those presented here. Our results indicate that classical statistical inference techniques, in general, works very well for random field regression models in finite samples and that these models succesfully...

  13. Stochastic estimation of hydraulic transmissivity fields using flow connectivity indicator data

    Science.gov (United States)

    Freixas, G.; Fernà ndez-Garcia, D.; Sanchez-Vila, X.

    2017-01-01

    Most methods for hydraulic test interpretation rely on a number of simplified assumptions regarding the homogeneity and isotropy of the underlying porous media. This way, the actual heterogeneity of any natural parameter, such as transmissivity (T), is transferred to the corresponding estimates in a way heavily dependent on the interpretation method used. An example is a long-term pumping test interpreted by means of the Cooper-Jacob method, which implicitly assumes a homogeneous isotropic confined aquifer. The estimates obtained from this method are not local values, but still have a clear physical meaning; the estimated T represents a regional-scale effective value, while the log-ratio of the normalized estimated storage coefficient, indicated by ω', is an indicator of flow connectivity, representative of the scale given by the distance between the pumping and the observation wells. In this work we propose a methodology to use ω', together with sampled local measurements of transmissivity at selected points, to map the expected value of local T values using a technique based on cokriging. Since the interpolation involves two variables measured at different support scales, a critical point is the estimation of the covariance and crosscovariance matrices. The method is applied to a synthetic field displaying statistical anisotropy, showing that the inclusion of connectivity indicators in the estimation method provide maps that effectively display preferential flow pathways, with direct consequences in solute transport.

  14. SPECIES IDENTIFICATION - ORGANISM LENGTH, HABITAT, STOMACH CONTENTS - FULLNESS, STOMACH CONTENTS - CONTENT WEIGHT and other fish examination data collected in the Coastal Waters of SE Alaska, Gulf of Alaska and North Pacific Ocean on NOAA Ship JOHN N. COBB cruises SECM, jc0009 and others as part of the NEP project from 1997-05-21 to 2006-07-31 (NODC Accession 0115196)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115196 includes biological and fish examination data collected aboard NOAA Ship JOHN N. COBB during cruises SECM, jc0009, jc0012, jc0016, jc0018,...

  15. Sensorless Stator Field-Oriented Controlled IM Drive at Low Speed with Rr Estimator

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Pu

    2014-01-01

    Full Text Available This paper pertains to a technique of a sensorless indirect stator field-oriented induction motor control, which prevents the accumulative errors incurred by the integrator and the problem relating to the stability of the control system caused by the stator resistance susceptible to temperature variations while conducting the flux estimation directly and computing the synchronous rotary speed. The research adds an adaptive flux observer to estimate the speed of the rotor and uses the fixed trace algorithm (FTA to execute an online estimation of the slip difference, thereby improving the system of stability under the low rotary speed at regenerating mode and the influence of the rotor resistance on the slip angle. Finally, the paper conducts simulations by Simulink of MATLAB and practices to verify the correctness of the result the paper presents.

  16. Estimating the correlation between bursty spike trains and local field potentials.

    Science.gov (United States)

    Li, Zhaohui; Ouyang, Gaoxiang; Yao, Li; Li, Xiaoli

    2014-09-01

    To further understand rhythmic neuronal synchronization, an increasingly useful method is to determine the relationship between the spiking activity of individual neurons and the local field potentials (LFPs) of neural ensembles. Spike field coherence (SFC) is a widely used method for measuring the synchronization between spike trains and LFPs. However, due to the strong dependency of SFC on the burst index, it is not suitable for analyzing the relationship between bursty spike trains and LFPs, particularly in high frequency bands. To address this issue, we developed a method called weighted spike field correlation (WSFC), which uses the first spike in each burst multiple times to estimate the relationship. In the calculation, the number of times that the first spike is used is equal to the spike count per burst. The performance of this method was demonstrated using simulated bursty spike trains and LFPs, which comprised sinusoids with different frequencies, amplitudes, and phases. This method was also used to estimate the correlation between pyramidal cells in the hippocampus and gamma oscillations in rats performing behaviors. Analyses using simulated and real data demonstrated that the WSFC method is a promising measure for estimating the correlation between bursty spike trains and high frequency LFPs.

  17. Estimation of emissions from field burning of crop straw in China

    Institute of Scientific and Technical Information of China (English)

    CAO GuoLiang; ZHANG XiaoYe; WANG YaQiang; Zheng FangCheng

    2008-01-01

    Emissions resulting from crop straw field burning in China, which have caused serious environmental problems in China, are estimated in this paper. From the county-level data of crop production in 2000-2003 from the government statistics, taking into account the ratio of residue and grain, the total amount of crop straw production is estimated to be about 600 Tg per year, 76% of which are rice, wheat and corn straw. With reference to the data of living standards, the percentage of crop straw burnt in fields for counties are obtained and consequently the total amount of burnt straws is approximately 140 Tg/year. With the emission factors from literature and experiments, appropriate emission factors have been obtained. The total amounts of PM, SO2, NOx, NH3, CH4, BC, OC, VOC, CO, CO2 emissions from field burning of crop straw in China are estimated. All emissions are presented at county level. Some pollutants, such as BC, VOC, OC, CO and CO2, are contributing a major portion to the total emissions of China. This paper uses a map with resolution of 0.2°×0.2° to present the PM emissions distribution from crop straw burnt in 2003. The results show a significant regional unevenness of emissions, with larger amounts of pollutions coming from the provinces in eastern and northeast China. The regions with higher emissions per unit area are located as a belt stretching from northeast China to eastern China.

  18. Theoretical estimates of maximum fields in superconducting resonant radio frequency cavities: stability theory, disorder, and laminates

    Science.gov (United States)

    Liarte, Danilo B.; Posen, Sam; Transtrum, Mark K.; Catelani, Gianluigi; Liepe, Matthias; Sethna, James P.

    2017-03-01

    Theoretical limits to the performance of superconductors in high magnetic fields parallel to their surfaces are of key relevance to current and future accelerating cavities, especially those made of new higher-T c materials such as Nb3Sn, NbN, and MgB2. Indeed, beyond the so-called superheating field {H}{sh}, flux will spontaneously penetrate even a perfect superconducting surface and ruin the performance. We present intuitive arguments and simple estimates for {H}{sh}, and combine them with our previous rigorous calculations, which we summarize. We briefly discuss experimental measurements of the superheating field, comparing to our estimates. We explore the effects of materials anisotropy and the danger of disorder in nucleating vortex entry. Will we need to control surface orientation in the layered compound MgB2? Can we estimate theoretically whether dirt and defects make these new materials fundamentally more challenging to optimize than niobium? Finally, we discuss and analyze recent proposals to use thin superconducting layers or laminates to enhance the performance of superconducting cavities. Flux entering a laminate can lead to so-called pancake vortices; we consider the physics of the dislocation motion and potential re-annihilation or stabilization of these vortices after their entry.

  19. Distance estimation in a dynamic simulated environment: a visual field dependence problem?

    Science.gov (United States)

    Vianin, Pascal; Baumberger, Bernard; Flückiger, Michelangelo

    2004-01-01

    Egocentric distance estimation implies that the subject perceives his own location in the environment. In a simulated environment, subjects have to transpose perceptively their own observation point in order to assume their virtual body position. As only visual information specifies this position, their ability to perceive the camera viewpoint should be linked to the field dependence independence factor (FDI). Field-independent subjects underestimated the mid-distance between their own virtual body position and a far-located target; their bisection was located between the projective (2-D) and the simulated (3-D) mid-distance which indicates their difficulty in considering the in-depth simulated spatial references. High correlations between the vertical estimation in the rod-and-frame test and the egocentric-distance-estimation task (with shifted camera) suggest a similar perceptive process in both tasks. This result is confirmed by the better performances of the field-dependent subjects in this condition. In conclusion, we discuss the relationship between FDI and the sense of presence in virtual environments.

  20. Heat flux estimates from the Gakkel Ridge 85E vent field from the AGAVE 2007 expedition

    Science.gov (United States)

    Stranne, C.; Winsor, P.; Sohn, R. A.; Liljebladh, B.

    2009-04-01

    During the Arctic Gakkel Vents Expedition (AGAVE) 2007, abundant hydrothermal venting was discovered on the Gakkel Ridge at 85E. Hydrothermal vents on the sea floor give rise to buoyant plumes which, when reaching neutral buoyancy, spreads horizontally over areas with length scales on the order of several kilometres and are therefore easily detected with a CTD rosette. The detected anomalies are consistent with the findings 6 years earlier during the Arctic Mid-Ocean Ridge Expedition (AMORE) 2001. The horizontal and vertical distribution of the anomalies is considered in order to establish the number of individual plumes detected. The objective of this paper is to estimate the minimum heat input required to reproduce the observed plumes, using a turbulent entrainment model. The model was run with a large number of combinations of boundary conditions (nozzle area, vertical velocity and temperature) in order to see which combinations that give rise to the observed plume characteristics (level of neutral buoyancy and temperature anomaly). For each individual plume, we estimate the minimum heat flux required to obtain the observed temperature anomaly. Adding the minimum heat flux from each vent together, the total heat flux for the vent field is estimated to be ~ 2 GW. The estimated value is comparable or larger than any other known vent field.

  1. Flood control and loss estimation for paddy field at midstream of Chao Phraya River Basin, Thailand

    Science.gov (United States)

    Cham, T. C.; Mitani, Y.

    2015-09-01

    2011 Thailand flood has brought serious impact to downstream of Chao Phraya River Basin. The flood peak period started from August, 2011 to the end of October, 2011. This research focuses on midstream of Chao Phraya River Basin, which is Nakhon Sawan area includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. The main purpose of this research is to understand the flood generation, estimate the flood volume and loss of paddy field, also recommends applicable flood counter measurement to ease the flood condition at downstream of Chao Phraya River Basin. In order to understand the flood condition, post-analysis is conducted at Nakhon Sawan. The post-analysis consists of field survey to measure the flood marks remained and interview with residents to understand living condition during flood. The 2011 Thailand flood generation at midstream is simulated using coupling of 1D and 2D hydrodynamic model to understand the flood generation during flood peak period. It is calibrated and validated using flood marks measured and streamflow data received from Royal Irrigation Department (RID). Validation of results shows good agreement between simulated result and actual condition. Subsequently, 3 scenarios of flood control are simulated and Geographic Information System (GIS) is used to assess the spatial distribution of flood extent and reduction of loss estimation at paddy field. In addition, loss estimation for paddy field at midstream is evaluated using GIS with the calculated inundation depth. Results show the proposed flood control at midstream able to minimize 5% of the loss of paddy field in 26 provinces.

  2. Improvement in Jc performance below liquid nitrogen temperature for SmBa2Cu3Oy superconducting films with BaHfO3 nano-rods controlled by low-temperature growth

    Directory of Open Access Journals (Sweden)

    S. Miura

    2016-01-01

    Full Text Available For use in high-magnetic-field coil-based applications, the critical current density (Jc of REBa2Cu3Oy (REBCO, where RE = rare earth coated conductors must be isotropically improved, with respect to the direction of the magnetic field; these improvements must be realized at the operating conditions of these applications. In this study, improvement of the Jc for various applied directions of magnetic field was achieved by controlling the morphology of the BaHfO3 (BHO nano-rods in a SmBCO film. We fabricated the 3.0 vol. % BHO-doped SmBCO film at a low growth temperature of 720 °C, by using a seed layer technique (Ts = 720 °C film. The low-temperature growth resulted in a morphological change in the BHO nano-rods. In fact, a high number density of (3.1 ± 0.1 × 103 μm−2 of small (diameter: 4 ± 1 nm, discontinuous nano-rods that grew in various directions, was obtained. In Jc measurements, the Jc of the Ts = 720 °C film in all directions of the applied magnetic field was higher than that of the non-doped SmBCO film. The Jcmin (6.4 MA/cm2 of the former was more than 6 times higher than that (1.0 MA/cm2 of the latter at 40 K, under 3 T. The aforementioned results indicated that the discontinuous BHO nano-rods, which occurred with a high number density, exerted a 3D-like flux pinning at the measurement conditions considered. Moreover, at 4.2 K and under 17 T, a flux pinning force density of 1.6 TN/m3 was realized; this value was comparable to the highest value recorded, to date.

  3. Improvement in Jc performance below liquid nitrogen temperature for SmBa2Cu3Oy superconducting films with BaHfO3 nano-rods controlled by low-temperature growth

    Science.gov (United States)

    Miura, S.; Yoshida, Y.; Ichino, Y.; Xu, Q.; Matsumoto, K.; Ichinose, A.; Awaji, S.

    2016-01-01

    For use in high-magnetic-field coil-based applications, the critical current density (Jc) of REBa2Cu3Oy (REBCO, where RE = rare earth) coated conductors must be isotropically improved, with respect to the direction of the magnetic field; these improvements must be realized at the operating conditions of these applications. In this study, improvement of the Jc for various applied directions of magnetic field was achieved by controlling the morphology of the BaHfO3 (BHO) nano-rods in a SmBCO film. We fabricated the 3.0 vol. % BHO-doped SmBCO film at a low growth temperature of 720 °C, by using a seed layer technique (Ts = 720 °C film). The low-temperature growth resulted in a morphological change in the BHO nano-rods. In fact, a high number density of (3.1 ± 0.1) × 103 μm-2 of small (diameter: 4 ± 1 nm), discontinuous nano-rods that grew in various directions, was obtained. In Jc measurements, the Jc of the Ts = 720 °C film in all directions of the applied magnetic field was higher than that of the non-doped SmBCO film. The Jcmin (6.4 MA/cm2) of the former was more than 6 times higher than that (1.0 MA/cm2) of the latter at 40 K, under 3 T. The aforementioned results indicated that the discontinuous BHO nano-rods, which occurred with a high number density, exerted a 3D-like flux pinning at the measurement conditions considered. Moreover, at 4.2 K and under 17 T, a flux pinning force density of 1.6 TN/m3 was realized; this value was comparable to the highest value recorded, to date.

  4. Estimation of Radiated Fields of Small Horizontal Submodules Based on a Lumped-Element Model

    Directory of Open Access Journals (Sweden)

    M. Leone

    2006-12-01

    Full Text Available A novel approach to the estimation of radiated electric field of small horizontal submodules is presented. The principle idea is to describe the radiating submodule-on-motherboard structure with a lumped-element equivalent circuit which includes both the geometrical and the electrical parameters. The electromagnetic emission from the structure is approximated by the radiation characteristics of a Hertzian dipole driven by the antenna voltage resulting from the connector equivalent circuit. Therefore, no time consuming numerical field simulations are needed to evaluate the radiated electric field. Instead, a fast frequency circuit analysis with e.g. PSPICE is sufficient. Moreover, this modeling approach provides a clear insight concerning the influence of geometrical and electrical parameters with respect to radiated emissions. Finally, the computational solutions are compared with experimental results, demonstrating a good correspondence regarding engineering purposes.

  5. Estimates on Functional Integrals of Quantum Mechanics and Non-relativistic Quantum Field Theory

    Science.gov (United States)

    Bley, Gonzalo A.; Thomas, Lawrence E.

    2017-01-01

    We provide a unified method for obtaining upper bounds for certain functional integrals appearing in quantum mechanics and non-relativistic quantum field theory, functionals of the form {E[{exp}(A_T)]} , the (effective) action {A_T} being a function of particle trajectories up to time T. The estimates in turn yield rigorous lower bounds for ground state energies, via the Feynman-Kac formula. The upper bounds are obtained by writing the action for these functional integrals in terms of stochastic integrals. The method is illustrated in familiar quantum mechanical settings: for the hydrogen atom, for a Schrödinger operator with {1/|x|^2} potential with small coupling, and, with a modest adaptation of the method, for the harmonic oscillator. We then present our principal applications of the method, in the settings of non-relativistic quantum field theories for particles moving in a quantized Bose field, including the optical polaron and Nelson models.

  6. A field test of the extent of bias in selection estimates after accounting for emigration

    Science.gov (United States)

    Letcher, B.H.; Horton, G.E.; Dubreuil, T.L.; O'Donnell, M. J.

    2005-01-01

    Question: To what extent does trait-dependent emigration bias selection estimates in a natural system? Organisms: Two freshwater cohorts of Atlantic salmon (Salmo salar) juveniles. Field site: A 1 km stretch of a small stream (West Brook) in western Massachusetts. USA from which emigration could be detected continuously. Methods: Estimated viability selection differentials for body size either including or ignoring emigration (include = emigrants survived interval, ignore = emigrants did not survive interval) for 12 intervals. Results: Seasonally variable size-related emigration from our study site generated variable levels of bias in selection estimates for body size. The magnitude of this bias was closely related with the extent of size-dependent emigration during each interval. Including or ignoring the effects of emigration changed the significance of selection estimates in 5 of the 12 intervals, and changed the estimated direction of selection in 4 of the 12 intervals. These results indicate the extent to which inferences about selection in a natural system can be biased by failing to account for trait-dependent emigration. ?? 2005 Benjamin H. Letcher.

  7. Quaternionic Spatiotemporal Filtering for Dense Motion Field Estimation in Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    Adrien Marion

    2010-01-01

    Full Text Available Blood motion estimation provides fundamental clinical information to prevent and detect pathologies such as cancer. Ultrasound imaging associated with Doppler methods is often used for blood flow evaluation. However, Doppler methods suffer from shortcomings such as limited spatial resolution and the inability to estimate lateral motion. Numerous methods such as block matching and decorrelation-based techniques have been proposed to overcome these limitations. In this paper, we propose an original method to estimate dense fields of vector velocity from ultrasound image sequences. Our proposal is based on a spatiotemporal approach and considers 2D+t data as a 3D volume. Orientation of the texture within this volume is related to velocity. Thus, we designed a bank of 3D quaternionic filters to estimate local orientation and then calculate local velocities. The method was applied to a large set of experimental and simulated flow sequences with low motion (≈1 mm/s within small vessels (≈1 mm. Evaluation was conducted with several quantitative criteria such as the normalized mean error or the estimated mean velocity. The results obtained show the good behaviour of our method, characterizing the flows studied.

  8. Quaternionic Spatiotemporal Filtering for Dense Motion Field Estimation in Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    Marion Adrien

    2010-01-01

    Full Text Available Abstract Blood motion estimation provides fundamental clinical information to prevent and detect pathologies such as cancer. Ultrasound imaging associated with Doppler methods is often used for blood flow evaluation. However, Doppler methods suffer from shortcomings such as limited spatial resolution and the inability to estimate lateral motion. Numerous methods such as block matching and decorrelation-based techniques have been proposed to overcome these limitations. In this paper, we propose an original method to estimate dense fields of vector velocity from ultrasound image sequences. Our proposal is based on a spatiotemporal approach and considers 2D+t data as a 3D volume. Orientation of the texture within this volume is related to velocity. Thus, we designed a bank of 3D quaternionic filters to estimate local orientation and then calculate local velocities. The method was applied to a large set of experimental and simulated flow sequences with low motion ( 1 mm/s within small vessels ( 1 mm. Evaluation was conducted with several quantitative criteria such as the normalized mean error or the estimated mean velocity. The results obtained show the good behaviour of our method, characterizing the flows studied.

  9. ALTERNATIVA DE MODELO LINEAR PARA ESTIMAÇÃO DA BIOMASSA VERDE DE Bambusa vulgaris SCHRAD. EX J.C. WENDL NA EXISTÊNCIA DE MULTICOLINEARIDADE

    Directory of Open Access Journals (Sweden)

    Adriano Victor Lopes da Silva

    2009-01-01

    Full Text Available The objective of this work was to use a multivariate statistical method as an alternative to estimate the green biomass of the main bamboo rod, Bambusa vulgaris Schrad. i.e.: J.C. Wendl., in the presence of multicollinearity. The data came from an experiment carried out for the Agroindustrial Excelsior S. A. (Agrimex company located in the city of Goiana - PE. Quantified by their green biomass weight, 450 bamboo rods were used and 4 independent variables measured in the rod. Initially, the presence of the multicollinearity could be verified through the correlation matrix of the independent variables and the varience inflation factors, the alternative used was the regression of the principal components based on the covariate matrix. The result indicates that, when there is an interpretation to the main components, the model shows a satisfactory data adjust, and it could be used to estimate the green biomass of the main bamboo rod.

  10. Ratiometric high-resolution imaging of JC-1 fluorescence reveals the subcellular heterogeneity of astrocytic mitochondria.

    Science.gov (United States)

    Keil, Vera C; Funke, Frank; Zeug, Andre; Schild, Detlev; Müller, Michael

    2011-11-01

    Using the mitochondrial potential (ΔΨ(m)) marker JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide) and high-resolution imaging, we functionally analyzed mitochondria in cultured rat hippocampal astrocytes. Ratiometric detection of JC-1 fluorescence identified mitochondria with high and low ΔΨ(m). Mitochondrial density was highest in the perinuclear region, whereas ΔΨ(m) tended to be higher in peripheral mitochondria. Spontaneous ΔΨ(m) fluctuations, representing episodes of increased energization, appeared in individual mitochondria or synchronized in mitochondrial clusters. They continued upon withdrawal of extracellular Ca(2+), but were antagonized by dantrolene or 2-aminoethoxydiphenylborate (2-APB). Fluo-3 imaging revealed local cytosolic Ca(2+) transients with similar kinetics that also were depressed by dantrolene and 2-APB. Massive cellular Ca(2+) load or metabolic impairment abolished ΔΨ(m) fluctuations, occasionally evoking heterogeneous mitochondrial depolarizations. The detected diversity and ΔΨ(m) heterogeneity of mitochondria confirms that even in less structurally polarized cells, such as astrocytes, specialized mitochondrial subpopulations coexist. We conclude that ΔΨ(m) fluctuations are an indication of mitochondrial viability and are triggered by local Ca(2+) release from the endoplasmic reticulum. This spatially confined organelle crosstalk contributes to the functional heterogeneity of mitochondria and may serve to adapt the metabolism of glial cells to the activity and metabolic demand of complex neuronal networks. The established ratiometric JC-1 imaging-especially combined with two-photon microscopy-enables quantitative functional analyses of individual mitochondria as well as the comparison of mitochondrial heterogeneity in different preparations and/or treatment conditions.

  11. Leaf Area Index Estimation Using Chinese GF-1 Wide Field View Data in an Agriculture Region.

    Science.gov (United States)

    Wei, Xiangqin; Gu, Xingfa; Meng, Qingyan; Yu, Tao; Zhou, Xiang; Wei, Zheng; Jia, Kun; Wang, Chunmei

    2017-07-08

    Leaf area index (LAI) is an important vegetation parameter that characterizes leaf density and canopy structure, and plays an important role in global change study, land surface process simulation and agriculture monitoring. The wide field view (WFV) sensor on board the Chinese GF-1 satellite can acquire multi-spectral data with decametric spatial resolution, high temporal resolution and wide coverage, which are valuable data sources for dynamic monitoring of LAI. Therefore, an automatic LAI estimation algorithm for GF-1 WFV data was developed based on the radiative transfer model and LAI estimation accuracy of the developed algorithm was assessed in an agriculture region with maize as the dominated crop type. The radiative transfer model was firstly used to simulate the physical relationship between canopy reflectance and LAI under different soil and vegetation conditions, and then the training sample dataset was formed. Then, neural networks (NNs) were used to develop the LAI estimation algorithm using the training sample dataset. Green, red and near-infrared band reflectances of GF-1 WFV data were used as the input variables of the NNs, as well as the corresponding LAI was the output variable. The validation results using field LAI measurements in the agriculture region indicated that the LAI estimation algorithm could achieve satisfactory results (such as R² = 0.818, RMSE = 0.50). In addition, the developed LAI estimation algorithm had potential to operationally generate LAI datasets using GF-1 WFV land surface reflectance data, which could provide high spatial and temporal resolution LAI data for agriculture, ecosystem and environmental management researches.

  12. Evaluation of uncertainty in field soil moisture estimations by cosmic-ray neutron sensing

    Science.gov (United States)

    Scheiffele, Lena Maria; Baroni, Gabriele; Schrön, Martin; Ingwersen, Joachim; Oswald, Sascha E.

    2017-04-01

    Cosmic-ray neutron sensing (CRNS) has developed into a valuable, indirect and non-invasive method to estimate soil moisture at the field scale. It provides continuous temporal data (hours to days), relatively large depth (10-70 cm), and intermediate spatial scale measurements (hundreds of meters), thereby overcoming some of the limitations in point measurements (e.g., TDR/FDR) and of remote sensing products. All these characteristics make CRNS a favorable approach for soil moisture estimation, especially for applications in cropped fields and agricultural water management. Various studies compare CRNS measurements to soil sensor networks and show a good agreement. However, CRNS is sensitive to more characteristics of the land-surface, e.g. additional hydrogen pools, soil bulk density, and biomass. Prior to calibration the standard atmospheric corrections are accounting for the effects of air pressure, humidity and variations in incoming neutrons. In addition, the standard calibration approach was further extended to account for hydrogen in lattice water and soil organic material. Some corrections were also proposed to account for water in biomass. Moreover, the sensitivity of the probe was found to decrease with distance and a weighting procedure for the calibration datasets was introduced to account for the sensors' radial sensitivity. On the one hand, all the mentioned corrections showed to improve the accuracy in estimated soil moisture values. On the other hand, they require substantial additional efforts in monitoring activities and they could inherently contribute to the overall uncertainty of the CRNS product. In this study we aim (i) to quantify the uncertainty in the field soil moisture estimated by CRNS and (ii) to understand the role of the different sources of uncertainty. To this end, two experimental sites in Germany were equipped with a CRNS probe and compared to values of a soil moisture network. The agricultural fields were cropped with winter

  13. Emulating the Visual Receptive Field Properties of MST Neurons with a Template Model of Heading Estimation

    Science.gov (United States)

    Perrone, John A.; Stone, Leland S.

    1997-01-01

    We have previously proposed a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. The model detectors were designed to extract self-translation (heading), self-rotation, as well as the scene layout (relative distances) ahead of a moving observer, and are arranged in cortical-like heading maps to perform this function. Heading estimation from optic flow has been postulated by some to be implemented within the medial superior temporal (MST) area. Others have questioned whether MST neurons can fulfill this role because some of their receptive-field properties appear inconsistent with a role in heading estimation. To resolve this issue, we systematically compared MST single-unit responses with the outputs of model detectors under matched stimulus conditions. We found that the basic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support heading estimation and that the template model provides an explicit set of testable hypotheses which can guide future exploration of MST and adjacent areas within the primate superior temporal sulcus.

  14. A multimodal detection model of dolphins to estimate abundance validated by field experiments.

    Science.gov (United States)

    Akamatsu, Tomonari; Ura, Tamaki; Sugimatsu, Harumi; Bahl, Rajendar; Behera, Sandeep; Panda, Sudarsan; Khan, Muntaz; Kar, S K; Kar, C S; Kimura, Satoko; Sasaki-Yamamoto, Yukiko

    2013-09-01

    Abundance estimation of marine mammals requires matching of detection of an animal or a group of animal by two independent means. A multimodal detection model using visual and acoustic cues (surfacing and phonation) that enables abundance estimation of dolphins is proposed. The method does not require a specific time window to match the cues of both means for applying mark-recapture method. The proposed model was evaluated using data obtained in field observations of Ganges River dolphins and Irrawaddy dolphins, as examples of dispersed and condensed distributions of animals, respectively. The acoustic detection probability was approximately 80%, 20% higher than that of visual detection for both species, regardless of the distribution of the animals in present study sites. The abundance estimates of Ganges River dolphins and Irrawaddy dolphins fairly agreed with the numbers reported in previous monitoring studies. The single animal detection probability was smaller than that of larger cluster size, as predicted by the model and confirmed by field data. However, dense groups of Irrawaddy dolphins showed difference in cluster sizes observed by visual and acoustic methods. Lower detection probability of single clusters of this species seemed to be caused by the clumped distribution of this species.

  15. Comparison of Sun-Induced Chlorophyll Fluorescence Estimates Obtained from Four Portable Field Spectroradiometers

    Directory of Open Access Journals (Sweden)

    Tommaso Julitta

    2016-02-01

    Full Text Available Remote Sensing of Sun-Induced Chlorophyll Fluorescence (SIF is a research field of growing interest because it offers the potential to quantify actual photosynthesis and to monitor plant status. New satellite missions from the European Space Agency, such as the Earth Explorer 8 FLuorescence EXplorer (FLEX mission—scheduled to launch in 2022 and aiming at SIF mapping—and from the National Aeronautics and Space Administration (NASA such as the Orbiting Carbon Observatory-2 (OCO-2 sampling mission launched in July 2014, provide the capability to estimate SIF from space. The detection of the SIF signal from airborne and satellite platform is difficult and reliable ground level data are needed for calibration/validation. Several commercially available spectroradiometers are currently used to retrieve SIF in the field. This study presents a comparison exercise for evaluating the capability of four spectroradiometers to retrieve SIF. The results show that an accurate far-red SIF estimation can be achieved using spectroradiometers with an ultrafine resolution (less than 1 nm, while the red SIF estimation requires even higher spectral resolution (less than 0.5 nm. Moreover, it is shown that the Signal to Noise Ratio (SNR plays a significant role in the precision of the far-red SIF measurements.

  16. Particle tracking velocimetry applied to estimate the pressure field around a Savonius turbine

    Science.gov (United States)

    Murai, Yuichi; Nakada, Taishi; Suzuki, Takao; Yamamoto, Fujio

    2007-08-01

    Particle tracking velocimetry (PTV) is applied to flows around a Savonius turbine. The velocity vector field measured with PTV is utilized to estimate the pressure field around the turbine, as well as to evaluate the torque performance. The main objective of the work is the establishment of the pressure estimation scheme required to discuss the turbine performance. First, the PTV data are interpolated on a regular grid with a fourth-order ellipsoidal differential equation to generate velocity vectors satisfying the third-order spatio-temporal continuity both in time and space. Second, the phase-averaged velocity vector information with respect to the turbine angle is substituted into three different types of pressure-estimating equations, i.e. the Poisson equation, the Navier-Stokes equation and the sub-grid scale model of turbulence. The results obtained based on the Navier-Stokes equation are compared with those based on the Poisson equation, and have shown several merits in employing the Navier-Stokes-based method for the PTV measurement. The method is applied to a rotating turbine with the tip-speed ratio of 0.5 to find the relationship between torque behaviour and flow structure in a phase-averaged sense. We have found that a flow attached to the convex surface of the blades induces low-pressure regions to drive the turbine, namely, the lift force helps the turbine blades to rotate even when the drag force is insufficient. Secondary mechanisms of torque generation are also discussed.

  17. JcTI-I, a novel trypsin inhibitor from Jatropha curcas seed cake with potential for bacterial infection treatment

    Directory of Open Access Journals (Sweden)

    Helen Paula S Costa

    2014-01-01

    Full Text Available Jatropha curcas seed cake is a low-value by-product resulting from biodiesel production. The seed cake is highly toxic, but it has great potential for biotechnology applications as it is a repository of biomolecules that could be important in agriculture, medicine and industry. To explore this potential, a novel trypsin inhibitor called JcTI-I was purified by fractionation of the crude extract with trichloroacetic acid (2.5%, v/v followed by affinity chromatography (Trypsin-Sepharose 4B and molecular exclusion (Sephacryl S-200. Non-reducing SDS-PAGE and gel filtration showed that JcTI-I has approximately 20.0 kDa. Mass spectrometry analysis revealed that the intact molecular mass of JcTI-I is 10.252 kDa. Moreover, JcTI-I is a glycoprotein with 6.4% (m/m carbohydrates, pI of 6.6, N-terminal sequence similarity around 60% to plant albumins and high stability to heat, pH and salinity. JcTI-I presented antibacterial activity against the human pathogenic bacteria Salmonella enterica subspecies enterica serovar choleraesuis and Staphylococcus aureus, with minimum inhibitory concentration (MIC less than 5 µg/mL. Furthermore, JcTI-I did have inhibitory activity against the serine proteases from the tested bacteria. Otherwise, no hemolytic activity of human erythrocytes and signs of acute toxicity to mice were observed for JcTI-I. The results demonstrate the benefits of J. curcas seed cake as a source of trypsin inhibitor with potential for biotechnological application as a new antimicrobial agent against human pathogenic bacteria.

  18. JcCBF2 gene from Jatropha curcas improves freezing tolerance of Arabidopsis thaliana during the early stage of stress.

    Science.gov (United States)

    Wang, Linghui; Gao, Jihai; Qin, Xiaobo; Shi, Xiaodong; Luo, Lin; Zhang, Guozhen; Yu, Hongwu; Li, Chenyang; Hu, Minchao; Liu, Qifan; Xu, Ying; Chen, Fang

    2015-05-01

    High chilling-susceptibility is becoming the bottleneck for cultivation and commercialization of Jatropha curcas L. For insights to chilling resistance ability of this plant species, a cold response transcription factor, JcCBF2, was cloned and studied. It codes a 26 kDa protein, which contains all conserved motifs unique to the C-repeat binding factor (CBF) family and has high similarity to CBFs of Ricinus communis and Populus. Its transcripts express specifically in leaves of Jatropha at cold temperature. After transmitting the report vector, 35S::JcCBF2-GFP, into Arabidopsis thaliana, JcCBF2 protein is main detected in cell nucleus, being consistent to the nuclear orientation signal in its N-terminal. Compared to the control Arabidopsis, the frozen leaves of JcCBF2-overexpressed seedlings grow stronger with less malondialdehyde, smaller leaf conductivity and activer superoxide dismutase, showing their higher freezing tolerance. RT-PCR tests revealed that JcCBF2 functioned mainly at the early stage (0-6 h) of resistance events in Arabidopsis, and its transcripts reduced after 6 h. In addition, JcCBF2 could quickly regulate transcripts of some cold-responsive (COR) genes such as RD29A, COR105A and COR6.6, also during the early stage of frozen treatment. This study not only proves the chilling resistance roles of JcCBF2, but also presents a candidate gene engineering for improvement of chilling tolerance in J. curcas.

  19. JcTI-I: a novel trypsin inhibitor from Jatropha curcas seed cake with potential for bacterial infection treatment

    Science.gov (United States)

    Costa, Helen P. S.; Oliveira, Jose T. A.; Sousa, Daniele O. B.; Morais, Janne K. S.; Moreno, Frederico B.; Monteiro-Moreira, Ana Cristina O.; Viegas, Ricardo A.; Vasconcelos, Ilka M.

    2014-01-01

    Jatropha curcas seed cake is a low-value by-product resulting from biodiesel production. The seed cake is highly toxic, but it has great potential for biotechnology applications as it is a repository of biomolecules that could be important in agriculture, medicine, and industry. To explore this potential, a novel trypsin inhibitor called JcTI-I was purified by fractionation of the crude extract with trichloroacetic acid (2.5%, v/v) followed by affinity chromatography (Trypsin-Sepharose 4B) and molecular exclusion (Sephacryl S-200). Non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration showed that JcTI-I has approximately 20.0~kDa. Mass spectrometry analysis revealed that the intact molecular mass of JcTI-I is 10.252~kDa. Moreover, JcTI-I is a glycoprotein with 6.4% (m/m) carbohydrates, pI of 6.6, N-terminal sequence similarity around 60% to plant albumins and high stability to heat, pH, and salinity. JcTI-I presented antibacterial activity against the human pathogenic bacteria Salmonella enterica subspecies enterica serovar choleraesuis and Staphylococcus aureus, with minimum inhibitory concentration less than 5~μg/mL. Furthermore, JcTI-I did have inhibitory activity against the serine proteases from the tested bacteria. Otherwise, no hemolytic activity of human erythrocytes and signs of acute toxicity to mice were observed for JcTI-I. The results demonstrate the benefits of J. curcas seed cake as a source of trypsin inhibitor with potential for biotechnological application as a new antimicrobial agent against human pathogenic bacteria. PMID:24523715

  20. Method for NIR Reflectance Estimation with Visible Camera Data based on Regression for NDVI Estimation and its Application for Insect Damage Detection of Rice Paddy Fields

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2016-10-01

    Full Text Available Method for Near Infrared: NIR reflectance estimation with visible camera data based on regression for Normalized Vegetation Index: NDVI estimation is proposed together with its application for insect damage detection of rice paddy fields. Through experiments at rice paddy fields which is situated at Saga Prefectural Agriculture Research Institute SPARI in Saga city, Kyushu, Japan, it is found that there is high correlation between NIR reflectance and Green color reflectance. Therefore, it is possible to estimate NIR reflectance with visible camera data which results in possibility of estimation of NDVI with drone mounted visible camera data. As is well known that the protein content in rice crops is highly correlated with NIR intensity, or reflectance of rice leaves, it is possible to estimate rice crop quality with drone based visible camera data.

  1. Assessing the effect of vegetation in the estimation of soil properties with field VNIR radiometry

    Science.gov (United States)

    Melendez-Pastor, I.; Córdoba-Sola, P.; Navarro-Pedreño, J.; Gómez, I.; Koch, M.

    2009-04-01

    Spectroradiometric soil surveys (field radiometry) are a valuable technique for soil classification and properties estimation. Field radiometry combines -in a relatively easy-to-use procedure- a fast, accurate and non-destructive sampling method. A wide range of soil properties have been quantitatively estimated with field or laboratory radiometry. In addition, field radiometry is a basic stage in remote sensing studies. It allows the up-scaling process of soil, vegetation or water parameters from the ground level to the airborne or spaceborne sensors level. Field radiometry plays a crucial role in training and validation stages of quantitative remote sensing. A complex problem in remote sensing appears when several components are mixed within a pixel and the resulting pixel's spectrum is a combination of the individual components. This work assess the effect of vegetation in soil properties estimation with linear regression models. Field spectra were taken from soil-vegetation mixtures under natural illumination with a portable spectroradiometer in the visible and near-infrared (VNIR) spectral range. Soil and vegetation samples for each radiometric sampling point were taken and analyzed in laboratory. Soil moisture content and soil organic carbon measured by the LOI (Loss-On-Ignition) method (Konen et al. 2002) were used in this approach. A derivative analysis of field spectra was used to determine the position and magnitude of absorption bands according to the method employed by Melendez-Pastor et al. (2008). Pearson correlations between soil parameters and each spectral band were computed and correlograms for the first and second derivate were obtained. Maximum (approximates to +1) and minimum (approximates to -1) Pearson correlations were used to normalize correlograms between 0 to 1. High relatively correlated bands (with values ranging from 0 to 0.1 or from 0-9 to 1 for the normalized correlograms) were identified and used as explicative variables in the

  2. Estimation of Reserves of Tula Horizon Oil Deposits of Severo-Yurmanskoye Field, Perm Kray

    Directory of Open Access Journals (Sweden)

    V I Nabiullin

    2015-09-01

    Full Text Available This article presents an estimation of reserves of the Tula horizon oil-bearing layers Tl2-a and Tl2-b at the Severo-Yurmanskoye oil field. Research was carried out in order to prospect the unestimated oil reserves at the previously drilled but not commercially producing areas of Perm kray. The opportunity of reserve calculation for this oil field was provided by the sufficient oil encroachment rate achieved during testing of Tula horizon layers in the borehole 174, reliable mapping of oil-bearing horizons using seismic and borehole data, existence of updated stratigraphic information, results of study of uniformity of oil-bearing layers throughout the area of the Severo-Yurmanskoye oil field, reliable estimate of the position of water-oil contact, defining the effective oil-bearing thickness of oil-bearing layers using results of borehole geophysical survey, study of lithological composition and reservoir  properties, study of physical and chemical properties of oil in borehole and in laboratory, and reliability of statistical evaluation of oil recovery factor.

  3. Estimation of the Required Amount of Superconductors for High-field Accelerator Dipole Magnets

    CERN Document Server

    Schwerg, N

    2007-01-01

    The coil size and the corresponding amount of superconducting material that is used during the design process of a magnet cross-section have direct impacts on the overall magnet cost. It is therefore of interest to estimate the minimum amount of conductors needed to reach the defined field strength before a detailed design process starts. Equally, it is useful to evaluate the efficiency of a given design by calculating the amount of superconducting cables that are used to reach the envisaged main field by simple rule. To this purpose, the minimum amount of conductors for the construction of a dipole of given main field strength and aperture size is estimated taking the actual critical current density of the used strands into account. Characteristic curves applicable for the NED Nb3Sn strand specification are given and some of the recently studied different dipole configurations are compared. Based on these results, it is shown how the required amount of conductors changes due to the iron yoke contribution and...

  4. Effect of visual field presentation on action planning (estimating reach) in children.

    Science.gov (United States)

    Gabbard, Carl; Cordova, Alberto

    2012-01-01

    In this article, the authors examined the effects of target information presented in different visual fields (lower, upper, central) on estimates of reach via use of motor imagery in children (5-11 years old) and young adults. Results indicated an advantage for estimating reach movements for targets placed in lower visual field (LoVF), with all groups having greater difficulty in the upper visual field (UpVF) condition, especially 5- and 7-year-olds. Complementing these results was an overall age-related increase in accuracy. Based in part on the equivalence hypothesis suggesting that motor imagery and motor planning and execution are similar, the findings support previous work of executed behaviors showing that there is a LoVF bias for motor skill actions of the hand. Given that previous research hints that the UpVF may be bias for visuospatial (perceptual) qualities, research in that area and its association with visuomotor processing (LoVF) should be considered.

  5. Restricted maximum likelihood estimation of variance components from field data for number of pigs born alive.

    Science.gov (United States)

    See, M T; Mabry, J W; Bertrand, J K

    1993-11-01

    Variance components for number of pigs born alive (NBA) were estimated from sow productivity field records collected by purebred breed associations. Data sets analyzed were as follows: Hampshire (n = 13,537), Landrace (n = 10,822), and Spotted (n = 3,949). Variance components for service sire, sire of sow, dam of sow, and residual effects on NBA (adjusted for parity) were estimated. The single-trait model included relationships between service sires, sires of sows, and dams of sows. The model was implemented using an expectation maximization (EM) REML algorithm. A sparse-matrix solver was also used. Heritability estimates for NBA were .13, .13, and .12 for Hampshire, Spotted, and Landrace, respectively. Estimates of maternal genetic (co)variances (m2) expressed as a proportion of the phenotypic variance were .05, .01, and .03 for Hampshire, Spotted, and Landrace, respectively. Results indicated that service sires account for 1 to 2% of the total variation for NBA. Genetic effects influencing NBA seem to be small in these data sets, but selection for increased NBA should be effective.

  6. Scaling of semivariograms and the kriging estimation of field-measured properties

    Directory of Open Access Journals (Sweden)

    S. R. Vieira

    1997-12-01

    Full Text Available Two methods were evaluated for scaling a set of semivariograms into a unified function for kriging estimation of field-measured properties. Scaling is performed using sample variances and sills of individual semivariograms as scale factors. Theoretical developments show that kriging weights are independent of the scaling factor which appears simply as a constant multiplying both sides of the kriging equations. The scaling techniques were applied to four sets of semivariograms representing spatial scales of 30 x 30 m to 600 x 900 km. Experimental semivariograms in each set successfully coalesced into a single curve by variances and sills of individual semivariograms. To evaluate the scaling techniques, kriged estimates derived from scaled semivariogram models were compared with those derived from unscaled models. Differences in kriged estimates of the order of 5% were found for the cases in which the scaling technique was not successful in coalescing the individual semivariograms, which also means that the spatial variability of these properties is different. The proposed scaling techniques enhance interpretation of semivariograms when a variety of measurements are made at the same location. They also reduce computational times for kriging estimations because kriging weights only need to be calculated for one variable. Weights remain unchanged for all other variables in the data set whose semivariograms are scaled.

  7. Linear Track Estimation Using Double Pulse Sources for Near-Field Underwater Moving Target

    Institute of Scientific and Technical Information of China (English)

    Zhifei Chen; Hong Hou; Jianhua Yang; Jincai Sun; Qian Wang

    2013-01-01

    The double pulse sources (DPS) method is presented for linear track estimation in this work.In the field of noise identification of underwater moving target,the Doppler will distort the frequency and amplitude of the radiated noise.To eliminate this,the track estimation is necessary.In the DPS method,we first estimate bearings of two sinusoidal pulse sources installed in the moving target through baseline positioning method.Meanwhile,the emitted and recorded time of each pulse are also acquired.Then the linear track parameters will be achieved based on the geometry pattern with the help of double sources spacing.The simulated results confirm that the DPS improves the performance of the previous double source spacing method.The simulated experiments were carried out using a moving battery car to further evaluate its performance.When the target is 40-60m away,the experiment results show that biases of track azimuth and abeam distance of DPS are under 0.6° and 3.4m,respectively.And the average deviation of estimated velocity is around 0.25m/s.

  8. Potential-field estimation from satellite data using scalar and vector Slepian functions

    CERN Document Server

    Plattner, Alain

    2013-01-01

    In the last few decades a series of increasingly sophisticated satellite missions has brought us gravity and magnetometry data of ever improving quality. To make optimal use of this rich source of information on the structure of Earth and other celestial bodies, our computational algorithms should be well matched to the specific properties of the data. In particular, inversion methods require specialized adaptation if the data are only locally available, their quality varies spatially, or if we are interested in model recovery only for a specific spatial region. Here, we present two approaches to estimate potential fields on a spherical Earth, from gradient data collected at satellite altitude. Our context is that of the estimation of the gravitational or magnetic potential from vector-valued measurements. Both of our approaches utilize spherical Slepian functions to produce an approximation of local data at satellite altitude, which is subsequently transformed to the Earth's spherical reference surface. The ...

  9. Scene estimation from speckled synthetic aperture radar imagery: Markov-random-field approach.

    Science.gov (United States)

    Lankoande, Ousseini; Hayat, Majeed M; Santhanam, Balu

    2006-06-01

    A novel Markov-random-field model for speckled synthetic aperture radar (SAR) imagery is derived according to the physical, spatial statistical properties of speckle noise in coherent imaging. A convex Gibbs energy function for speckled images is derived and utilized to perform speckle-compensating image estimation. The image estimation is formed by computing the conditional expectation of the noisy image at each pixel given its neighbors, which is further expressed in terms of the derived Gibbs energy function. The efficacy of the proposed technique, in terms of reducing speckle noise while preserving spatial resolution, is studied by using both real and simulated SAR imagery. Using a number of commonly used metrics, the performance of the proposed technique is shown to surpass that of existing speckle-noise-filtering methods such as the Gamma MAP, the modified Lee, and the enhanced Frost.

  10. The Peculiar Type Ib Supernova 2006jc: A WC Star Explosion

    CERN Document Server

    Tominaga, N; Suzuki, T; Tanaka, M; Nomoto, K; Maeda, K; Chieffi, A; Tornambé, A; Minezaki, T; Yoshii, Y; Sakon, I; Wada, T; Ohyama, Y; Tanabé, T; Kaneda, H; Onaka, T; Nozawa, T; Kozasa, T; Kawabata, K S; Anupama, G C; Sahu, D K; Gurugubelli, U K; Prabhu, T P; Deng, J

    2007-01-01

    We present a theoretical model for Type Ib supernova (SN) 2006jc associated with a luminous blue variable (LBV)-like event. We calculate the presupernova evolution of the progenitor star, hydrodynamics and nucleosynthesis of the SN explosion, and the SN bolometric light curve (LC). The observed bolometic LC is constructed by integrating the UV, optical, near-infrared (NIR), and mid-infrared (MIR) fluxes. The progenitor is assumed to be as massive as $40\\Msun$ on the zero-age. The star undergoes extensive mass loss to reduce its mass down to as small as $6.9\\Msun$, thus becoming a WC Wolf-Rayet star at the presupernova stage. The WC star model has a thick carbon-rich layer, in which amorphous carbon grains can be formed during the explosion. This could explain the brightening in the NIR flux and the observed dust feature in MIR. The typical main-sequence mass of a WC Wolf-Rayet star and thus the progenitor of SN 2006jc is more massive than $40\\Msun$. We suggest that the explosions of stars more massive than $4...

  11. [Analysis of the cellular tropism of JC virus with archetypal regulatory region].

    Science.gov (United States)

    Hasegawa, Y

    1997-07-01

    JC virus (JCV) with an archetypal regulatory region (archetype) has been cloned from urines of a healthy individual. It has been suggested that the regulatory region of prototype JC virus (PML type) isolated from brain of PML patient was derived from that of the archetype by deletion and duplication. Biological characteristics of archetypal JCV, however, have not been fully studied. In the present study we examined the infectivity of archetypal JCV (CY), PML-type JCV (Mad-1) and Chimera JCV (Mad-1/CR-CY), in which the regulatory region is composed of CY and the other region Mad-1. DNAs from the three JCV types were transfected into COS-7 (monkey kidney cells transformed with SV40 T) and IMR-32 (human neuroblastoma cell). COS-7 was permissive for all three types, but IMR-32 was only infected with Mad-1. Infected DNAs were confirmed by Southern blotting, and the constancy of the regulatory regions before and after transmission was verified by DNA sequencing. The results showed that the viral regulatory region was related to viral cell tropism and that PML type regulatory region would be necessary for IMR-32 to propagate. The fact that COS-7 was susceptible for all three types may be explained by the function of SV40 T protein. In addition, we first succeeded in the propagation of CY in COS-7, which would provide a useful system to analyze the mechanism of persistent infection of archetypal JCV.

  12. JC polyoma virus interacts with APOL1 in African Americans with nondiabetic nephropathy.

    Science.gov (United States)

    Divers, Jasmin; Núñez, Marina; High, Kevin P; Murea, Mariana; Rocco, Michael V; Ma, Lijun; Bowden, Donald W; Hicks, Pamela J; Spainhour, Mitzie; Ornelles, David A; Kleiboeker, Steven B; Duncan, Kara; Langefeld, Carl D; Turner, Jolyn; Freedman, Barry I

    2013-12-01

    Individuals with HIV infection and two apolipoprotein L1 gene (APOL1) risk variants frequently develop nephropathy. Here we tested whether non-HIV viral infections influence nephropathy risk via interactions with APOL1 by assessing APOL1 genotypes and presence of urine JC and BK polyoma virus and plasma HHV6 and CMV by quantitative polymerase chain reaction. We analyzed 300 samples from unrelated and related first-degree relatives of African Americans with nondiabetic nephropathy using linear and nonlinear mixed models to account for familial relationships. The four groups evaluated were APOL1 zero/one versus two risk alleles, with or without nephropathy. Urine JCV and BKV were detected in 90 and 29 patients, respectively, whereas HHV6 and CMV were rare. Adjusting for family age at nephropathy, gender, and ancestry, presence of JCV genomic DNA in urine and APOL1 risk alleles were significantly negatively associated with elevated serum cystatin C, albuminuria (albumin-to-creatinine ratio over 30 mg/g), and kidney disease defined as an eGFR under 60 ml/min per 1.73 m(2) and/or albuminuria in an additive (APOL1 plus JCV) model. BK viruria was not associated with kidney disease. Thus, African Americans at increased risk for APOL1-associated nephropathy (two APOL1 risk variants) with JC viruria had a lower prevalence of kidney disease, suggesting that JCV interaction with APOL1 genotype may influence kidney disease risk.

  13. Increase Jc by Improving the Array of Nb3Sn strands for Fusion Application

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Xuan

    2012-12-17

    During Phase I, our efforts were focusing on improving the array of subelement in the tube type strands by hardening the Sn core and the subelement matrix to effectively increase the Jc of the strands. Below is a summary of the results. 1) We were unsuccessful in improving the array using a Cu-Sn matrix approach. 2) We slightly improved the array using Sn with 1.5at%Ti doped core, and a 217-subelement restacked strand was made and drawn down without any breakage. 3) We greatly improved the array using the Glidcop Al-15 to replace the pure Cu sheath in the subelement, and a 217-subelement restacked strand was made and drawn down. Both strands have very good drawability and the array showed good improvement. 4) We also improved the array using improved wire drawing techniques using Hyper Tech's new caterpillar wire drawing machines to enable straight wire drawing for the entire wire drawing process. 5) The 919-subelement restack strand shows its non-Cu Jc over 2100 A/mm2 at 12 T/4.2 K and AC loss of 508 mJ/cm3.

  14. Theory of Distribution Estimation of Hyperparameters in Markov Random Field Models

    Science.gov (United States)

    Sakamoto, Hirotaka; Nakanishi-Ohno, Yoshinori; Okada, Masato

    2016-06-01

    We investigated the performance of distribution estimation of hyperparameters in Markov random field models proposed by Nakanishi-Ohno et al., http://doi.org/10.1088/1751-8113/47/4/045001, J. Phys. A 47, 045001 (2014) when used to evaluate the confidence of data. We analytically calculated the configurational average, with respect to data, of the negative logarithm of the posterior distribution, which is called free energy based on an analogy with statistical mechanics. This configurational average of free energy shrinks as the amount of data increases. Our results theoretically confirm the numerical results from that previous study.

  15. Estimation of the rice-planting field in Bangladesh by satellite remote sensing

    Science.gov (United States)

    Furuta, E.; Suzuki, G.; Yamassaki, M.; Teraoka, T.; Fujiwara, H.; Ogino, Y.; Akashi, M.; Lahrita, L.; Naruse, N.; Takahashi, Y.

    2016-12-01

    In Bangladesh, price of rice has been unstable due to a large increase in production. To control the price can become a political issue, because rice agriculture is one of the most important industries in Bangladesh, whereas the total area of the paddy field is accurately unknown, owing to unsustainable and on-site surveys for the area (1). Satellite remote sensing is an effective solution to research the all area of domestic paddy field. Microwave satellite imaging has a large merit to be observable regardless of the weather conditions, however, research institutions have been limited to observing continuously since the cost is high for developing countries, such as Bangladesh. This study aims to establish the way to grasp the paddy field using optical satellite images for free of charge (Landsat-8). We have focused on seasonal changes in the water and the vegetation indices obtained from paddy fields. We have performed image calculations of Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) of the well-known paddy field in Bangladesh Rice Research Institute. We found that there are seasonal changes of NDVI and NDWI calculated from paddy field. The characteristics are as follows; the NDVI and the NDWI values varies by 0.17-0.25 up and 0.11-0.19 down, respectively, at the transition from the dry to the rainy season, on the other hand, the NDVI and the NDWI changes by 0.21-0.29 down and 0.09-0.17 up from the rainy to the dry season. These features make us to distinguish the paddy field from the other cultivated area. The decrease of NDVI means that rice bares, The increase of NDWI can be interpreted that the paddy field is covered with water for the preparation for planting it. Our estimated area of paddy field in Bangladesh (85,900km ) corresponds well with the previous reported value of 117,700km (1). We have established the way to grasp the paddy field using optical satellite images for free of charge, on the bases of the

  16. A new estimate of the mass of the gravitational scalar field for Dark Energy

    CERN Document Server

    Fujii, Yasunori

    2015-01-01

    A new estimate of the mass of the pseudo dilaton is offered by following the funda- mental nature that a massless Nambu-Goldstone boson, called a dilaton, in the Einstein frame acquires a nonzero mass through the loop effects which occur with the Higgs field in the relativistic quantum field theory as described by poles of D, spacetime dimensionality off the physical value D = 4. Naturally the technique of dimensional regulairzation is fully used to show this pole structure to be suppressed to be finite by what is called a Classical-Quantum-Interplay, to improve our previous attempt. Basically the same anal- ysis is extended to derive also the coupling of a pseudo dilaton to two photons.

  17. Estimation of Coal Bed Methane Potential of Coal Seams of Margherita Coal Field, Assam, India

    Directory of Open Access Journals (Sweden)

    Prasenjit Talukdar

    2015-06-01

    Full Text Available The rapid industrialization and growing energy needs have put a great stress on the conventional energy resources. This is even more concerning for a country like India which is a net importer of oil. To meet the ever increasing need for energy, it is essential that the search for unconventional energy is intensified. This paper deals with the estimation of coal bed methane potential of the Margherita Coal Field of Assam, India. For this purpose, eight coal samples were collected from Tirap O.C.P., Ledo UG Incline and Tikak O.C.P collieries of the Margherita coal field. Proximate analysis, megascopic study and finally qualitative analysis of these eight samples was undertaken. After analysis, the inferred reserves of CBM at Margherita Coalfield, was found to be in the range of 42.5-49.04 Billion Cubic Meter.

  18. Axonal and dendritic density field estimation from incomplete single-slice neuronal reconstructions

    Directory of Open Access Journals (Sweden)

    Jaap evan Pelt

    2014-06-01

    Full Text Available Neuronal information processing in cortical networks critically depends on the organization of synaptic connectivity. Synaptic connections can form when axons and dendrites come in close proximity of each other. The spatial innervation of neuronal arborizations can be described by their axonal and dendritic density fields. Recently we showed that potential locations of synapses between neurons can be estimated from their overlapping axonal and dendritic density fields. However, deriving density fields from single-slice neuronal reconstructions is hampered by incompleteness because of cut branches.Here, we describe a method for recovering the lost axonal and dendritic mass. This so-called completion method is based on an estimation of the mass inside the slice and an extrapolation to the space outside the slice, assuming axial symmetry in the mass distribution. We validated the method using a set of neurons generated with our NETMORPH simulator. The model-generated neurons were artificially sliced and subsequently recovered by the completion method. Depending on slice thickness and arbor extent, branches that have lost their outside parents (orphan branches may occur inside the slice. Not connected anymore to the contiguous structure of the sliced neuron, orphan branches result in an underestimation of neurite mass. For 300 m thick slices, however, the validation showed a full recovery of dendritic and an almost full recovery of axonal mass.The completion method was applied to three experimental data sets of reconstructed rat cortical L2/3 pyramidal neurons. The results showed that in 300 m thick slices intracortical axons lost about 50% and dendrites about 16% of their mass. The completion method can be applied to single-slice reconstructions as long as axial symmetry can be assumed in the mass distribution. This opens up the possibility of using incomplete neuronal reconstructions from open-access data bases to determine population mean

  19. Temperature and magnetic field dependence of the critical current in polycrystalline Ba2YCu3O(y)

    Science.gov (United States)

    Obara, H.; Yamasaki, H.; Kimura, Y.; Higashida, Y.; Ishihara, T.

    Temperature and magnetic field dependence on the critical current density Jc of polycrystalline high-Tc oxide superconductor, Ba2YCu3O(y), have been measured. In the low magnetic field range, 0.6 to about 7 kOe, the Jc behavior changed at around 70 K. Below 70 K, Jc showed different temperature dependence between field cooling and zero-field cooling, that is, the Jc value measured when the sample was cooled in a fixed magnetic field, was different from that measured when the sample was cooled in zero magnetic field and then a magnetic field was applied. Above 70 K, however, such different temperature dependence on Jc was not observed. These experimental results can be attributed to the effects of anisotropy. A crossover between the two- and three-dimensional superconductivity is considered to occur.

  20. A label field fusion bayesian model and its penalized maximum rand estimator for image segmentation.

    Science.gov (United States)

    Mignotte, Max

    2010-06-01

    This paper presents a novel segmentation approach based on a Markov random field (MRF) fusion model which aims at combining several segmentation results associated with simpler clustering models in order to achieve a more reliable and accurate segmentation result. The proposed fusion model is derived from the recently introduced probabilistic Rand measure for comparing one segmentation result to one or more manual segmentations of the same image. This non-parametric measure allows us to easily derive an appealing fusion model of label fields, easily expressed as a Gibbs distribution, or as a nonstationary MRF model defined on a complete graph. Concretely, this Gibbs energy model encodes the set of binary constraints, in terms of pairs of pixel labels, provided by each segmentation results to be fused. Combined with a prior distribution, this energy-based Gibbs model also allows for definition of an interesting penalized maximum probabilistic rand estimator with which the fusion of simple, quickly estimated, segmentation results appears as an interesting alternative to complex segmentation models existing in the literature. This fusion framework has been successfully applied on the Berkeley image database. The experiments reported in this paper demonstrate that the proposed method is efficient in terms of visual evaluation and quantitative performance measures and performs well compared to the best existing state-of-the-art segmentation methods recently proposed in the literature.

  1. Estimating aboveground biomass in interior Alaska with Landsat data and field measurements

    Science.gov (United States)

    Ji, Lei; Wylie, Bruce K.; Nossov, Dana R.; Peterson, Birgit E.; Waldrop, Mark P.; McFarland, Jack W.; Rover, Jennifer R.; Hollingsworth, Teresa N.

    2012-01-01

    Terrestrial plant biomass is a key biophysical parameter required for understanding ecological systems in Alaska. An accurate estimation of biomass at a regional scale provides an important data input for ecological modeling in this region. In this study, we created an aboveground biomass (AGB) map at 30-m resolution for the Yukon Flats ecoregion of interior Alaska using Landsat data and field measurements. Tree, shrub, and herbaceous AGB data in both live and dead forms were collected in summers and autumns of 2009 and 2010. Using the Landsat-derived spectral variables and the field AGB data, we generated a regression model and applied this model to map AGB for the ecoregion. A 3-fold cross-validation indicated that the AGB estimates had a mean absolute error of 21.8 Mg/ha and a mean bias error of 5.2 Mg/ha. Additionally, we validated the mapping results using an airborne lidar dataset acquired for a portion of the ecoregion. We found a significant relationship between the lidar-derived canopy height and the Landsat-derived AGB (R2 = 0.40). The AGB map showed that 90% of the ecoregion had AGB values ranging from 10 Mg/ha to 134 Mg/ha. Vegetation types and fires were the primary factors controlling the spatial AGB patterns in this ecoregion.

  2. Field Application of Cable Tension Estimation Technique Using the h-SI Method

    Directory of Open Access Journals (Sweden)

    Myung-Hyun Noh

    2015-01-01

    Full Text Available This paper investigates field applicability of a new system identification technique of estimating tensile force for a cable of long span bridges. The newly proposed h-SI method using the combination of the sensitivity updating algorithm and the advanced hybrid microgenetic algorithm can allow not only avoiding the trap of local minimum at initial searching stage but also finding the optimal solution in terms of better numerical efficiency than existing methods. First, this paper overviews the procedure of tension estimation through a theoretical formulation. Secondly, the validity of the proposed technique is numerically examined using a set of dynamic data obtained from benchmark numerical samples considering the effect of sag extensibility and bending stiffness of a sag-cable system. Finally, the feasibility of the proposed method is investigated through actual field data extracted from a cable-stayed Seohae Bridge. The test results show that the existing methods require precise initial data in advance but the proposed method is not affected by such initial information. In particular, the proposed method can improve accuracy and convergence rate toward final values. Consequently, the proposed method can be more effective than existing methods in terms of characterizing the tensile force variation for cable structures.

  3. Estimate of Methane Emission from Rice Paddy Fields in Taihu Region,China

    Institute of Scientific and Technical Information of China (English)

    CAIZU-CONG; JINJI-SHENG; 等

    1994-01-01

    Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closed chamber method in 1992 and 1993 and CH4 emission from this region (total area of paddy soils was about 1.88 million hectares,of which 0.63 million hectares are distibuted in the south of Jiangsu province) was estimated on the basis of the meam CH4 fluxes observed.The results showed that the mean CH4 flaxes from late rice and single cropping rice field were quite similar under the prevailing cultivation practices in the region,being around 5 mg CH4/m2/h(4.31-5.31mg CH4/m2/h for various cultivars of the late rice and 3.20-6.22mg CH4/m2/h for various treatments of the single cropping rice).Total CH4 emission from paddy soils in the region was estimated to e 0.185-0.359 Tg CH4 per year.Continuously flooding the soil with a water layer till ripening caused higher mean CH4 flux;and addition of nitrification inhibitor(thiourea) stimulated CH4 emission.There was no simple repationship between CH4 flux and either soil temperature or soil Eh.

  4. 复合光稳定剂JC-568在PVC-U型材中的耐候稳定作用%The weather resistance effect of composite light stabilizer JC-568 in PVC-U section materials

    Institute of Scientific and Technical Information of China (English)

    李杰; 孙书适; 陈明辉; 王存吉

    2006-01-01

    通过试验,研究了复合光稳定剂JC-568在PVC-U型材中的耐候稳定作用.结果表明,复合光稳定剂JC-568用于PVC-U型材,适用于一般加工要求,可促进塑化,表现出明显的光、氧稳定作用;PVC-U型材制品经6 000 h老化后,各项指标满足GB/T 8814-2004要求.

  5. a Method to Estimate Temporal Interaction in a Conditional Random Field Based Approach for Crop Recognition

    Science.gov (United States)

    Diaz, P. M. A.; Feitosa, R. Q.; Sanches, I. D.; Costa, G. A. O. P.

    2016-06-01

    This paper presents a method to estimate the temporal interaction in a Conditional Random Field (CRF) based approach for crop recognition from multitemporal remote sensing image sequences. This approach models the phenology of different crop types as a CRF. Interaction potentials are assumed to depend only on the class labels of an image site at two consecutive epochs. In the proposed method, the estimation of temporal interaction parameters is considered as an optimization problem, whose goal is to find the transition matrix that maximizes the CRF performance, upon a set of labelled data. The objective functions underlying the optimization procedure can be formulated in terms of different accuracy metrics, such as overall and average class accuracy per crop or phenological stages. To validate the proposed approach, experiments were carried out upon a dataset consisting of 12 co-registered LANDSAT images of a region in southeast of Brazil. Pattern Search was used as the optimization algorithm. The experimental results demonstrated that the proposed method was able to substantially outperform estimates related to joint or conditional class transition probabilities, which rely on training samples.

  6. Robust estimation of error covariance functions in GRACE gravity field determination

    Science.gov (United States)

    Behzadpour, Saniya; Mayer-Gürr, Torsten; Flury, Jakob

    2016-04-01

    The accurate modelling of the stochastic behaviour of the GRACE mission observations is an important task in the time variable gravity field determination. After fitting a model in the least-squares sense, it is necessary to determine whether all the necessary model assumptions, i.e., independence, normality, and homoscedasticity of the residuals, are valid before performing inference. Checking the model assumptions for the range rate residuals, it has been concluded that one of the major problems in the range rate observations is the outliers in the data. One way to deal with this problem is to implement a robust estimation procedure to dampen the effect of observations that would be highly influential if least squares were used. In addition to insensitivity to outliers, such a procedure tends to leave the residuals associated with outliers large, therefore making the identification of outliers much easier. Implementation of this procedure using robust error covariance functions, comparison of different robust estimators, e.g., Huber's and Tukey's estimators, and assessing the detected outliers with respect to temporal and spatial patterns are discussed.

  7. Estimation of methane and nitrous oxide emissions from rice field with rice straw management in Cambodia.

    Science.gov (United States)

    Vibol, S; Towprayoon, S

    2010-02-01

    To estimate the greenhouse gas emissions from paddy fields of Cambodia, the methodology of the Intergovernmental Panel on Climate Change (IPCC) guidelines, IPCC coefficients, and emission factors from the experiment in Thailand and another country were used. Total area under rice cultivation during the years 2005-2006 was 2,048,360 ha in the first crop season and 298,529 ha in the second crop season. The emission of methane from stubble incorporation with manure plus fertilizer application areas in the first crop season was estimated to be 192,783.74 ton higher than stubble with manure, stubble with fertilizer, and stubble without fertilizer areas. The fields with stubble burning emitted the highest emission of methane (75,771.29 ton) followed by stubble burning with manure (22,251.08 ton), stubble burning with fertilizer (13,213.27 ton), and stubble burning with fertilizer application areas (3,222.22 ton). The total emission of methane from rice field in Cambodia for the years 2005-2006 was approximately 342,649.26 ton (342.65 Gg) in the first crop season and 36,838.88 ton (36.84 Gg) in the second crop season. During the first crop season in the years 2005-2006, Battambang province emitted the highest amount of CH(4) (38,764.48 ton) and, in the second crop season during the years 2005-2006, the highest emission (8,262.34 ton) was found in Takeo province (8,262.34 ton). Nitrous oxide emission was between 2.70 and 1,047.92 ton in the first crop season and it ranged from 0 to 244.90 ton in the second crop season. Total nitrous oxide emission from paddy rice field was estimated to be 9,026.28 ton in the first crop season and 1,091.93 ton in the second crop season. Larger area under cultivation is responsible for higher emission of methane and nitrous oxide. Total emission of nitrous oxide by using IPCC default emission coefficient was approximately 2,328.85 ton. The total global warming potential of Cambodian paddy rice soil is 11,723,217.03 ton (11,723 Gg

  8. A new approach for estimating the Jupiter and Saturn gravity fields using Juno and Cassini measurements, trajectory estimation analysis, and a dynamical wind model optimization

    Science.gov (United States)

    Galanti, Eli; Durante, Daniele; Iess, Luciano; Kaspi, Yohai

    2017-04-01

    The ongoing Juno spacecraft measurements are improving our knowledge of Jupiter's gravity field. Similarly, the Cassini Grand Finale will improve the gravity estimate of Saturn. The analysis of the Juno and Cassini Doppler data will provide a very accurate reconstruction of spacial gravity variations, but these measurements will be very accurate only over a limited latitudinal range. In order to deduce the full gravity fields of Jupiter and Saturn, additional information needs to be incorporated into the analysis, especially with regards to the planets' wind structures. In this work we propose a new iterative approach for the estimation of Jupiter and Saturn gravity fields, using simulated measurements, a trajectory estimation model, and an adjoint based inverse thermal wind model. Beginning with an artificial gravitational field, the trajectory estimation model is used to obtain the gravitational moments. The solution from the trajectory model is then used as an initial guess for the thermal wind model, and together with an optimization method, the likely penetration depth of the winds is computed, and its uncertainty is evaluated. As a final step, the gravity harmonics solution from the thermal wind model is given back to the trajectory model, along with an estimate of their uncertainties, to be used as a priori for a new calculation of the gravity field. We test this method both for zonal harmonics only and with a full gravity field including tesseral harmonics. The results show that by using this method some of the gravitational moments are fitted better to the `observed' ones, mainly due to the added information from the dynamical model which includes the wind structure and its depth. Thus, it is suggested that the method presented here has the potential of improving the accuracy of the expected gravity moments estimated from the Juno and Cassini radio science experiments.

  9. A simplified sampling procedure for the estimation of methane emission in rice fields.

    Science.gov (United States)

    Khokhar, Nadar Hussain; Park, Jae-Woo

    2017-08-24

    Manual closed chamber methods are widely used for CH4 measurement from rice paddies. Despite diurnal and seasonal variations in CH4 emissions, fixed sampling times, usually during the day, are used. Here, we monitored CH4 emission from rice paddies for one complete rice-growing season. Daytime CH4 emission increased from 0800 h, and maximal emission was observed at 1200 h. Daily averaged CH4 flux increased during plant growth or fertilizer application and decreased upon drainage of plants. CH4 measurement results were linearly interpolated and matched with the daily averaged CH4 emission calculated from the measured results. The time when daily averaged emission and the interpolated CH4 curve coincided during the daytime was largely invariant within each of the five distinctive periods. One-hourly sampling during each of these five periods was utilized to estimate the emission during each period, and we found that five one-hourly samples during the season accurately reflected the CH4 emission calculated based on all 136 hourly samples. This new sampling scheme is simple and more efficient than current sampling practices. Previously reported sampling schemes yielded estimates 9 to 32% higher than the measured CH4 emission, while our suggested scheme yielded an estimate that was only 5% different from that based on all 136-h samples. The sampling scheme proposed in this study can be used in rice paddy fields in Korea and extended worldwide to countries that use similar farming practices. This sampling scheme will help in producing more accurate global methane budget from rice paddy fields.

  10. Improved Pinning Center Morphology in HTS with Order-of-Magnitude Increase in Jc and Bpin Compared to Columnar Pinning

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The motivation for continuouscolumnar pinning centers has been to provide maximum Upin. It has been assumed that this provides the best Jc and Bpin. Limitations on Jc and Bpin observed for columnar pinning have been attributed to degradation of the order parameter and Tc. We examine columnar pinning by ionic damage and conclude instead that geometrical effects of columnar pinningon percolation path and on the number of pinning centers are the dominant limitations of columnar pinning, leading to a limit of Bpin~4 T. Evidence suggests that multiple-in-line-defects (MILD) are far better suited to increase Jc and Bpin. The morphology of MILD pinning is reviewed. Ion energy loss per unit distance, Se, is found to be most promising in a regime almost diametrically opposite to that sought to maximize Upin. We expect Jc~106 A/cm2 and Bpin>40 T from MILD pinning,despite sharply decreased Upin.Experimental confirmation is proposed.

  11. Pathogenesis-related gene, JcPR-10a from Jatropha curcas exhibit RNase and antifungal activity.

    Science.gov (United States)

    Agarwal, Parinita; Bhatt, Vacha; Singh, Rekha; Das, Mamali; Sopory, Sudhir K; Chikara, Jitendra

    2013-06-01

    The pathogenesis-related proteins have a broad spectrum of roles, ranging from seed germination, development to resistance. The PR-10 is a multigene family differing from other PR proteins in being intracellular, small and acidic with similar 3D structures. We have isolated JcPR-10a cDNA with an ORF of 483 bp from J. curcas, an important biofuel crop grown in the wastelands of India. JcPR-10a gets clustered with dicots in phylogenetic tree. The genomic organisation analysis of JcPR-10a revealed the presence of an intron at conserved 185 bp position. Transcript expression of JcPR-10a was upregulated in response to different stimuli such as NaCl, salicylic acid, methyl jasmonate and M. phaseolina. In response to SA and Macrophomina the transcript was found increased at 48 h, however, in case of NaCl and MeJa a strong induction was observed at 12 h which decreased at 48 h. We first time report the transcript up regulation of PR-10 gene by Macrophomina, a pathogen causing collar rot in Jatropha. The recombinant E. coli cells showed better growth in LB medium supplemented with NaCl, whereas growth of recombinant cells was inhibited in LB medium supplemented with KCl, mannitol, sorbitol, methyl jasmonate and salicylic acid. The JcPR-10a protein was overexpressed in E. coli cells, and was purified to homogeneity, the purified protein exhibited RNase and DNase activity. Furthermore, the protein also showed antifungal activity against Macrophomina, indicating that JcPR-10a can serve as an important candidate to engineer stress tolerance in Jatropha as well as other plants susceptible to collar rot by Macrophomina.

  12. A simplified dynamic method for field capacity estimation and its parameter analysis

    Institute of Scientific and Technical Information of China (English)

    Zhen-tao CONG; Hua-fang LÜ; Guang-heng NI

    2014-01-01

    This paper presents a simplified dynamic method based on the definition of field capacity. Two soil hydraulic characteristics models, the Brooks-Corey (BC) model and the van Genuchten (vG) model, and four soil data groups were used in this study. The relative drainage rate, which is a unique parameter and independent of the soil type in the simplified dynamic method, was analyzed using the pressure-based method with a matric potential of−1/3 bar and the flux-based method with a drainage flux of 0.005 cm/d. As a result, the relative drainage rate of the simplified dynamic method was determined to be 3% per day. This was verified by the similar field capacity results estimated with the three methods for most soils suitable for cultivating plants. In addition, the drainage time calculated with the simplified dynamic method was two to three days, which agrees with the classical definition of field capacity. We recommend the simplified dynamic method with a relative drainage rate of 3% per day due to its simple application and clearly physically-based concept.

  13. JC Polyomavirus Infection Is Strongly Controlled by Human Leucocyte Antigen Class II Variants

    DEFF Research Database (Denmark)

    Sundqvist, Emilie; Buck, Dorothea; Warnke, Clemens

    2014-01-01

    JC polyomavirus (JCV) carriers with a compromised immune system, such as in HIV, or subjects on immune-modulating therapies, such as anti VLA-4 therapy may develop progressive multifocal leukoencephalopathy (PML) which is a lytic infection of oligodendrocytes in the brain. Serum antibodies to JCV...... antibody response and human leucocyte antigens supports the notion that CD4+ T cells are crucial in the immune defence to JCV and lays the ground for risk stratification for PML and development of therapy and prevention....... mark infection occur only in 50-60% of infected individuals, and high JCV-antibody titers seem to increase the risk of developing PML. We here investigated the role of human leukocyte antigen (HLA), instrumental in immune defense in JCV antibody response. Anti-JCV antibody status, as a surrogate...

  14. Analysis of JC virus DNA replication using a quantitative and high-throughput assay.

    Science.gov (United States)

    Shin, Jong; Phelan, Paul J; Chhum, Panharith; Bashkenova, Nazym; Yim, Sung; Parker, Robert; Gagnon, David; Gjoerup, Ole; Archambault, Jacques; Bullock, Peter A

    2014-11-01

    Progressive Multifocal Leukoencephalopathy (PML) is caused by lytic replication of JC virus (JCV) in specific cells of the central nervous system. Like other polyomaviruses, JCV encodes a large T-antigen helicase needed for replication of the viral DNA. Here, we report the development of a luciferase-based, quantitative and high-throughput assay of JCV DNA replication in C33A cells, which, unlike the glial cell lines Hs 683 and U87, accumulate high levels of nuclear T-ag needed for robust replication. Using this assay, we investigated the requirement for different domains of T-ag, and for specific sequences within and flanking the viral origin, in JCV DNA replication. Beyond providing validation of the assay, these studies revealed an important stimulatory role of the transcription factor NF1 in JCV DNA replication. Finally, we show that the assay can be used for inhibitor testing, highlighting its value for the identification of antiviral drugs targeting JCV DNA replication.

  15. Estimate of CH4 Emissions from Year-Round Flooded Rice Fields During Rice Growing Season in China

    Institute of Scientific and Technical Information of China (English)

    CAI Zu-Cong; KANG Guo-Ding; H. TSURUTA; A. MOSIER

    2005-01-01

    A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China.The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66Mha were estimated to be 2.44 Tg CH4 year-1. The uncertainties of these estimations are discussed as well. However,the emissions during the non-rice growing season could not be estimated because of limited available data. Nevertheless,methane emissions from rice fields that were flooded year-round could be several times higher than those from the rice fields drained in the non-rice-growing season. Thus, the classification of "continuously flooded rice fields" in the IPCC(International Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories is suggested to be revised and divided into "continuously flooded rice fields during the rice growing season" and "year-round flooded rice fields".

  16. Improved model predictive control of resistive wall modes by error field estimator in EXTRAP T2R

    Science.gov (United States)

    Setiadi, A. C.; Brunsell, P. R.; Frassinetti, L.

    2016-12-01

    Many implementations of a model-based approach for toroidal plasma have shown better control performance compared to the conventional type of feedback controller. One prerequisite of model-based control is the availability of a control oriented model. This model can be obtained empirically through a systematic procedure called system identification. Such a model is used in this work to design a model predictive controller to stabilize multiple resistive wall modes in EXTRAP T2R reversed-field pinch. Model predictive control is an advanced control method that can optimize the future behaviour of a system. Furthermore, this paper will discuss an additional use of the empirical model which is to estimate the error field in EXTRAP T2R. Two potential methods are discussed that can estimate the error field. The error field estimator is then combined with the model predictive control and yields better radial magnetic field suppression.

  17. Estimation of critical current density and grain connectivity in superconducting MgB 2 bulk using Campbell’s method

    Science.gov (United States)

    Ni, B.; Morita, Y.; Liu, Z.; Liu, C.; Himeki, K.; Otabe, E. S.; Kiuchi, M.; Matsushita, T.

    2008-09-01

    Many recent reports on the critical current density ( Jc) in superconducting MgB 2 bulks indicated that improving the grain connectivity is important, since the obtained Jc values were generally much lower than those in other metallic superconductors and it was ascribed to the poor connectivity between grains in polycrystalline MgB 2. In this study, we focused on the estimation of the global critical current density, super-current path, grain connectivity and their relationships with the faults volume fraction in the MgB 2 bulks prepared by a modified PIT (powder in tube) method. Campbell’s method was applied for the purpose of obtaining the penetrating AC flux profile and the characteristic of AC magnetic field vs. penetration depth from the sample’s surface. A computer simulation on the penetrating AC flux profile in MgB 2 bulks with randomly distributed voids, oxidized grains and other faults was also carried out. Jc obtained by Campbell’s method turned out to be smaller than that obtained from the SQUID measurement, implying that the global super-current was reduced by the existence of various faults and the lack of the electrical connectivity. It was verified that the relationship between the global critical current characteristics and the faults contained in MgB 2 samples can be quantitatively clarified by comparing the simulated critical current densities and other factors with the experimental results.

  18. Simple estimation of induced electric fields in nervous system tissues for human exposure to non-uniform electric fields at power frequency

    Science.gov (United States)

    Tarao, Hiroo; Miyamoto, Hironobu; Korpinen, Leena; Hayashi, Noriyuki; Isaka, Katsuo

    2016-06-01

    Most results regarding induced current in the human body related to electric field dosimetry have been calculated under uniform field conditions. We have found in previous work that a contact current is a more suitable way to evaluate induced electric fields, even in the case of exposure to non-uniform fields. If the relationship between induced currents and external non-uniform fields can be understood, induced electric fields in nervous system tissues may be able to be estimated from measurements of ambient non-uniform fields. In the present paper, we numerically calculated the induced electric fields and currents in a human model by considering non-uniform fields based on distortion by a cubic conductor under an unperturbed electric field of 1 kV m-1 at 60 Hz. We investigated the relationship between a non-uniform external electric field with no human present and the induced current through the neck, and the relationship between the current through the neck and the induced electric fields in nervous system tissues such as the brain, heart, and spinal cord. The results showed that the current through the neck can be formulated by means of an external electric field at the central position of the human head, and the distance between the conductor and the human model. As expected, there is a strong correlation between the current through the neck and the induced electric fields in the nervous system tissues. The combination of these relationships indicates that induced electric fields in these tissues can be estimated solely by measurements of the external field at a point and the distance from the conductor.

  19. Magnetic resonance imaging of acoustic streaming: absorption coefficient and acoustic field shape estimation.

    Science.gov (United States)

    Madelin, Guillaume; Grucker, Daniel; Franconi, Jean-Michel; Thiaudiere, Eric

    2006-07-01

    In this study, magnetic resonance imaging (MRI) is used to visualize acoustic streaming in liquids. A single-shot spin echo sequence (HASTE) with a saturation band perpendicular to the acoustic beam permits the acquisition of an instantaneous image of the flow due to the application of ultrasound. An average acoustic streaming velocity can be estimated from the MR images, from which the ultrasonic absorption coefficient and the bulk viscosity of different glycerol-water mixtures can be deduced. In the same way, this MRI method could be used to assess the acoustic field and time-average power of ultrasonic transducers in water (or other liquids with known physical properties), after calibration of a geometrical parameter that is dependent on the experimental setup.

  20. A field technique for estimating aquifer parameters using flow log data

    Science.gov (United States)

    Paillet, Frederick L.

    2000-01-01

    A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The theory shows that the amount of inflow to or outflow from the borehole under any one flow condition may not indicate relative zone transmissivity. A unique inversion for both hydraulic-head and transmissivity values is possible if flow is measured under two different conditions such as ambient and quasi-steady pumping, and if the difference in open-borehole water level between the two flow conditions is measured. The technique is shown to give useful estimates of water levels and transmissivities of two or more water-producing zones intersecting a single interval of open borehole under typical field conditions. Although the modeling technique involves some approximation, the principle limit on the accuracy of the method under field conditions is the measurement error in the flow log data. Flow measurements and pumping conditions are usually adjusted so that transmissivity estimates are most accurate for the most transmissive zones, and relative measurement error is proportionately larger for less transmissive zones. The most effective general application of the borehole-flow model results when the data are fit to models that systematically include more production zones of progressively smaller transmissivity values until model results show that all accuracy in the data set is exhausted.A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The

  1. Characterization of the Cosmic Radiation Field at Flight Altitudes and Estimation of Aircrew Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jong Ho

    2004-02-15

    Cosmic radiation field at flight altitudes was simulated using the FLUKA Monte Carlo transport code and the spectra of secondary particles were obtained from the simulation. The obtained particle spectra were converted into effective dose rates by means of appropriate sets of conversion coefficients. The result shows that higher dose rates are observed at the higher altitude than the lower, at the higher latitude than the lower, and at the solar minimum than the maximum. Also it is confirmed that CARI-6 used in the estimation of aircrew exposure along specific flights provides approximately the same doses as the results of FLUKA calculations. Accordingly, the route doses to the personnels on board due to cosmic radiation were calculated for Korean-based commercial international airline routes using CARI-6. Annual individual doses to aircrew and the collective effective dose of passengers were estimated by applying the calculated route doses to the flight schedules of aircrew and the air travel statistics of Korea. The result shows that the annual doses to aircrew exceed the annual dose limit of public and are comparable to those of the group of workers occupationally exposed. Therefore it is necessary to consider the aircrew as the occupational exposure group. Also the annual collective dose to 11 million Korean passengers in 2001 appeared to be 136 man-Sv.

  2. Structural parameter for estimating durability of composite materials with polymer components in strong electric fields

    Science.gov (United States)

    Minakova, N. N.; Ushakov, V. Ya.

    2016-11-01

    The purpose of the present work is to reveal and to substantiate the structural parameter for estimation of the durability of composite materials with polymeric components in strong electric fields. Rubbers filled with technical carbon are chosen as objects of research. They possess almost zero water absorption, resistance to aggressive media, high electrical and mechanical strengths, capability of acquiring practically any form, etc. Because of this, they are widely used in high-voltage electrophysics and electrical engineering. Composite materials are represented by an equivalent circuit of a series-parallel connection of a set of individual contacts conductive phase-dielectric-conductive phase formed by an electroconductive grid. The processes in the materials are considered on three hierarchical levels: individual contact conductive phase-dielectric-conductive phase, distribution of the set of individual contacts over their properties taking into account the dispersion of their parameters depending on the employed initial components, macrostructural level—the electricoconductive grid imbedded into a polymer matrix. As a result of our investigations, the structural parameter—the entropy of the textural parameter that can be used to estimate the durability of composite materials with polymer components in strong electric fields—has been chosen.

  3. New method for estimation of fluence complexity in IMRT fields and correlation with gamma analysis

    Science.gov (United States)

    Hanušová, T.; Vondráček, V.; Badraoui-Čuprová, K.; Horáková, I.; Koniarová, I.

    2015-01-01

    A new method for estimation of fluence complexity in Intensity Modulated Radiation Therapy (IMRT) fields is proposed. Unlike other previously published works, it is based on portal images calculated by the Portal Dose Calculation algorithm in Eclipse (version 8.6, Varian Medical Systems) in the plane of the EPID aS500 detector (Varian Medical Systems). Fluence complexity is given by the number and the amplitudes of dose gradients in these matrices. Our method is validated using a set of clinical plans where fluence has been smoothed manually so that each plan has a different level of complexity. Fluence complexity calculated with our tool is in accordance with the different levels of smoothing as well as results of gamma analysis, when calculated and measured dose matrices are compared. Thus, it is possible to estimate plan complexity before carrying out the measurement. If appropriate thresholds are determined which would distinguish between acceptably and overly modulated plans, this might save time in the re-planning and re-measuring process.

  4. An inverse method for estimation of the acoustic intensity in the focused ultrasound field

    Science.gov (United States)

    Yu, Ying; Shen, Guofeng; Chen, Yazhu

    2017-03-01

    Recently, a new method which based on infrared (IR) imaging was introduced. Authors (A. Shaw, et al and M. R. Myers, et al) have established the relationship between absorber surface temperature and incident intensity during the absorber was irradiated by the transducer. Theoretically, the shorter irradiating time makes estimation more in line with the actual results. But due to the influence of noise and performance constrains of the IR camera, it is hard to identify the difference in temperature with short heating time. An inverse technique is developed to reconstruct the incident intensity distribution using the surface temperature with shorter irradiating time. The algorithm is validated using surface temperature data generated numerically from three-layer model which was developed to calculate the acoustic field in the absorber, the absorbed acoustic energy during the irradiation, and the consequent temperature elevation. To assess the effect of noisy data on the reconstructed intensity profile, in the simulations, the different noise levels with zero mean were superposed on the exact data. Simulation results demonstrate that the inversion technique can provide fairly reliable intensity estimation with satisfactory accuracy.

  5. A generalized linear model for estimating spectrotemporal receptive fields from responses to natural sounds.

    Directory of Open Access Journals (Sweden)

    Ana Calabrese

    Full Text Available In the auditory system, the stimulus-response properties of single neurons are often described in terms of the spectrotemporal receptive field (STRF, a linear kernel relating the spectrogram of the sound stimulus to the instantaneous firing rate of the neuron. Several algorithms have been used to estimate STRFs from responses to natural stimuli; these algorithms differ in their functional models, cost functions, and regularization methods. Here, we characterize the stimulus-response function of auditory neurons using a generalized linear model (GLM. In this model, each cell's input is described by: 1 a stimulus filter (STRF; and 2 a post-spike filter, which captures dependencies on the neuron's spiking history. The output of the model is given by a series of spike trains rather than instantaneous firing rate, allowing the prediction of spike train responses to novel stimuli. We fit the model by maximum penalized likelihood to the spiking activity of zebra finch auditory midbrain neurons in response to conspecific vocalizations (songs and modulation limited (ml noise. We compare this model to normalized reverse correlation (NRC, the traditional method for STRF estimation, in terms of predictive power and the basic tuning properties of the estimated STRFs. We find that a GLM with a sparse prior predicts novel responses to both stimulus classes significantly better than NRC. Importantly, we find that STRFs from the two models derived from the same responses can differ substantially and that GLM STRFs are more consistent between stimulus classes than NRC STRFs. These results suggest that a GLM with a sparse prior provides a more accurate characterization of spectrotemporal tuning than does the NRC method when responses to complex sounds are studied in these neurons.

  6. Utilising Geological Field Measurements and Historic Eruption Volumes to Estimate the Volume of Santorini's Magma Chamber

    Science.gov (United States)

    Browning, J.; Drymoni, K.; Gudmundsson, A.

    2015-12-01

    An understanding of the amount of magma available to supply any given eruption is useful for determining the potential eruption magnitude and duration. Geodetic measurements and inversion techniques are often used to constrain volume changes within magma chambers, as well as constrain location and depth, but such models are incapable of calculating total magma storage. For example, during the 2012 unrest period at Santorini volcano, approximately 0.021 km3 of new magma entered a shallow chamber residing at around 4 km below the surface. This type of event is not unusual, and is in fact a necessary condition for the formation of a long-lived shallow chamber, of which Santorini must possess. The period of unrest ended without culminating in eruption, i.e the amount of magma which entered the chamber was insufficient to break the chamber and force magma further towards the surface. We combine previously published data on the volume of recent eruptions at Santorini together with geodetic measurements. Measurements of dykes within the caldera wall provide an estimate of the volume of magma transported during eruptions, assuming the dyke does not become arrested. When the combined volume of a dyke and eruption are known (Ve) they can be used to estimate using fracture mechanics principles and poro-elastic constraints the size of an underlying shallow magma chamber. We present field measurements of dykes within Santorini caldera and provide an analytical method to estimate the volume of magma contained underneath Santorini caldera. In addition we postulate the potential volume of magma required as input from deeper sources to switch the shallow magma chamber from an equilibrium setting to one where the pressure inside the chamber exceeds the surrounding host rocks tensile strength, a condition necessary to form a dyke and a possible eruption.

  7. Magnetization of Multifilamentary Superconductor Nb3Sn in Perpendicular Field

    Institute of Scientific and Technical Information of China (English)

    LIU Fang; WENG Peide; WU Yu; LONG Feng

    2008-01-01

    Hysteresis loss is one of the electromagnetic characteristics controlled by time evo-lution of magnetic field and current distribution inside the conductor. Brandt's method allows us to model the interaction of the conductor with an external magnetic field. Instead of the constant critical current density (Jc =CONST), the Jc scaling law from current-voltage (I-V) measurement is used to model the magnetization loop. By comparing the calculated results with the measured data, it is shown that the Jc scaling law, i.e. the deviatoric strain model, is not useful in a very low field. To solve this problem, the Kim model about Jc as a function of applied field has been applied in the low field case. This method can be used to predict the hysteresis loss of Nb3Sn filamentary strand.

  8. Estimation of the optimal wind factor of drifting objects from field experiments

    Science.gov (United States)

    Choi, Jung-Woon; Choi, Jin-Yong; Kwon, Jae-Il

    2017-04-01

    Particle tracking models (PTM) are used to calculate the trajectory of drifting objects for search and rescue in case of marine accidents. During marine accidents, the rescue team needs to predict a possible path of the objects in the ocean to implement an effective plan of dealing with the rescue. In this study, we try to improve the accuracy of PTM throughout a series of field experiments. Field experiments were conducted using drift buoys and mannequin with/without life jacket. The drift buoys and mannequin were designed to be easily influenced by wind and current in the sea. For PTM we used the module embedded on MOHID (Modelo Hidrodinâmico) and the results of WRF (Weather Research Forecasting) and MOHID are used as wind and current input data, respectively. This study aims to find the optimal wind factor according to the objects by using new method to improve the PTM accuracy. In order to estimate an optimal wind factor, we simulated iteratively on the different wind factor from 2 to 5% by increasing 0.2%. However we found the optimal wind factor varies with the wind speed. So, we divided into 16 sections from 2.5 to 10 m/s of wind speed and extracted the best accuracy at each section. Finally we made a formula with wind speed and wind factor. Using this formula, the accuracy of search and rescue was improved by about 10% compared to that in the usual method.

  9. Accurate optical flow field estimation using mechanical properties of soft tissues

    Science.gov (United States)

    Mehrabian, Hatef; Karimi, Hirad; Samani, Abbas

    2009-02-01

    A novel optical flow based technique is presented in this paper to measure the nodal displacements of soft tissue undergoing large deformations. In hyperelasticity imaging, soft tissues maybe compressed extensively [1] and the deformation may exceed the number of pixels ordinary optical flow approaches can detect. Furthermore in most biomedical applications there is a large amount of image information that represent the geometry of the tissue and the number of tissue types present in the organ of interest. Such information is often ignored in applications such as image registration. In this work we incorporate the information pertaining to soft tissue mechanical behavior (Neo-Hookean hyperelastic model is used here) in addition to the tissue geometry before compression into a hierarchical Horn-Schunck optical flow method to overcome this large deformation detection weakness. Applying the proposed method to a phantom using several compression levels proved that it yields reasonably accurate displacement fields. Estimated displacement results of this phantom study obtained for displacement fields of 85 pixels/frame and 127 pixels/frame are reported and discussed in this paper.

  10. A Five-Parameter Wind Field Estimation Method Based on Spherical Upwind Lidar Measurements

    Science.gov (United States)

    Kapp, S.; Kühn, M.

    2014-12-01

    Turbine mounted scanning lidar systems of focussed continuous-wave type are taken into consideration to sense approaching wind fields. The quality of wind information depends on the lidar technology itself but also substantially on the scanning technique and reconstruction algorithm. In this paper a five-parameter wind field model comprising mean wind speed, vertical and horizontal linear shear and homogeneous direction angles is introduced. A corresponding parameter estimation method is developed based on the assumption of upwind lidar measurements scanned over spherical segments. As a main advantage of this method all relevant parameters, in terms of wind turbine control, can be provided. Moreover, the ability to distinguish between shear and skew potentially increases the quality of the resulting feedforward pitch angles when compared to three-parameter methods. It is shown that minimal three measurements, each in turn from two independent directions are necessary for the application of the algorithm, whereas simpler measurements, each taken from only one direction, are not sufficient.

  11. Estimating sediment sources by multiple scale field measurements and fingerprinting using radionuclides

    Science.gov (United States)

    Onda, Y.; Mizugaki, S.; Nanko, K.; Asai, H.

    2006-12-01

    To study the fluvial sediment sources in forested watershed in Shikoku Island, Japan, field measurements and radionuclide analysis were conducted. The observation of erosion and runoff processes were conducted in variable scale in an unmanaged Japanese cypress (Chamaecyparis obtusa) plantation catchment with splash cup, runoff plot, Parshall flumes and integrated suspended sediment samplers for 5 months. For fingerprinting of suspended sediment, Cs-137 and Pb-210ex were determined by gamma-ray spectrometry for the potential sources as the surface soil of forest floor, stream bank and skid trail, eroded sediment by splash and runoff, and fluvial sediment. The concentrations of 1 Cs-137 and Pb-210ex of fluvial sediment are found to be varied in each sampling period. Therefore, there is temporal variation of suspended sediment sources in the watershed. The contribution of forest floor as suspended sediment source was estimated as high as -77 % by 137Cs. The results suggest that forest floor should be recognized as important source of fluvial sediment in this watershed. Based on the field measurements, splash detachment and overland flow occurred during rainfall event on the hillslope, eroded the surface soil on the forest floor, and transported fine particle downslope. Overland flow on the skid trails networks can transport the forest floor sediment into the stream channel, and can result in high contribution of forest floor soil to fluvial sediment in Japanese cypress catchment.

  12. Cyclotron Lines: From Magnetic Field Strength Estimators to Geometry Tracers in Neutron Stars

    Indian Academy of Sciences (India)

    Chandreyee Maitra

    2017-09-01

    With forty years since the discovery of the first cyclotron line in Her X-1, there have been remarkable advancements in the field related to the study of the physics of accreting neutron stars – cyclotron lines have been a major torchbearer in this regard, from being the only direct estimator of the magnetic field strength, a tracer of accretion geometry and an indicator of the emission beam in these systems. The main flurry of activities have centred around studying the harmonic separations, luminosity dependence, pulse phase dependence and more recently, the shapes of the line and the trend for long-term evolution in the line energy. This article visits the important results related to cyclotron lines since its discovery and reviews their significance. An emphasis is laid on pulse phase resolved spectroscopy and the important clues a joint timing and spectral study in this context can provide, to build a complete picture for the physics of accretion and hence X-ray emission in accreting neutron stars.

  13. Simultaneous field estimates of urea hydrolysis rates and ammonium retardation factors in a fractured rock aquifer

    Science.gov (United States)

    Smith, R. W.; Taylor, J. L.; Fujita, Y.

    2005-12-01

    Knowledge of the rates of in situ biogeochemical processes is critical to the design and implementation of active and passive environmental remediation strategies. However, often rate determinations require the collection of samples in the field followed by laboratory studies that may occur days or weeks later. Artificial laboratory conditions as well as sample storage effects can lead to erroneous conclusions regarding kinetic processes in nature. We have been investigating in field and laboratory studies the microbial hydrolysis of urea as a method to facilitate calcium carbonate precipitation and co-precipitation of divalent metal and radionuclide contaminants (such as 90Sr). In conjunction with a single well "push-pull" test conducted in a fractured basalt aquifer near the Idaho National Laboratory, in situ rates of urea hydrolysis were estimated by tracking the disappearance of urea and a conservative tracer and measuring the increase in ammonium concentration. The analysis of rates was complicated by cation exchange reactions of ammonium with the aquifer matrix. However, we were able to derive and parameterize a rate law that explicitly included a retardation factor. With this approach, we are able to characterize in situ ureolysis kinetics without resorting to laboratory studies.

  14. Precision Orbit Determination for the Lunar Reconnaissance Orbiter: orbit quality and gravity field estimation

    Science.gov (United States)

    Mazarico, E.; Rowlands, D. D.; Neumann, G. A.; Lemoine, F. G.; Torrence, M. H.; Smith, D. E.; Zuber, M. T.; Mao, D.

    2010-12-01

    We present results of the Precision Orbit Determination work undertaken by the Lunar Orbiter Laser Altimeter (LOLA) Science Team for the Lunar Reconnaissance Orbiter (LRO) mission, in order to meet the position knowledge accuracy requirements (50-m total position) and to precisely geolocate the LRO datasets. In addition to the radiometric tracking data, one-way laser ranges (LR) between Earth stations and the spacecraft are made possible by a small telescope mounted on the spacecraft high-gain antenna. The photons received from Earth are transmitted to one LOLA detector by a fiber optics bundle. The LOLA timing system enables 5-s LR normal points with precision better than 10cm. Other types of geodetic constraints are derived from the altimetric data itself. The orbit geometry can be constrained at the times of laser groundtrack intersections (crossovers). Due to the Moon's slow rotation, orbit solutions and normal equations including altimeter crossovers are processed and created in one month batches. Recent high-resolution topographic maps near the lunar poles are used to produce a new kind of geodetic constraints. Purely geometric, those do not necessitate actual groundtrack intersections. We assess the contributions of those data types, and the quality of our orbits. Solutions which use altimetric crossover meet the horizontal 50-m requirement, and perform usually better (10-20m). We also obtain gravity field solutions based on LRO and historical data. The various LRO data are accumulated into normal equations, separately for each one month batch and for each measurement type, which enables the final weights to be adjusted during the least-squares inversion step. Expansion coefficients to degree and order 150 are estimated, and a Kaula rule is still needed to stabilize the farside field. The gravity field solutions are compared to previous solutions (GLGM-3, LP150Q, SGM100h) and the geopotential predicted from the latest LOLA spherical harmonic expansion.

  15. Estimation of surface curvature from full-field shape data using principal component analysis

    Science.gov (United States)

    Sharma, Sameer; Vinuchakravarthy, S.; Subramanian, S. J.

    2017-01-01

    Three-dimensional digital image correlation (3D-DIC) is a popular image-based experimental technique for estimating surface shape, displacements and strains of deforming objects. In this technique, a calibrated stereo rig is used to obtain and stereo-match pairs of images of the object of interest from which the shapes of the imaged surface are then computed using the calibration parameters of the rig. Displacements are obtained by performing an additional temporal correlation of the shapes obtained at various stages of deformation and strains by smoothing and numerically differentiating the displacement data. Since strains are of primary importance in solid mechanics, significant efforts have been put into computation of strains from the measured displacement fields; however, much less attention has been paid to date to computation of curvature from the measured 3D surfaces. In this work, we address this gap by proposing a new method of computing curvature from full-field shape measurements using principal component analysis (PCA) along the lines of a similar work recently proposed to measure strains (Grama and Subramanian 2014 Exp. Mech. 54 913-33). PCA is a multivariate analysis tool that is widely used to reveal relationships between a large number of variables, reduce dimensionality and achieve significant denoising. This technique is applied here to identify dominant principal components in the shape fields measured by 3D-DIC and these principal components are then differentiated systematically to obtain the first and second fundamental forms used in the curvature calculation. The proposed method is first verified using synthetically generated noisy surfaces and then validated experimentally on some real world objects with known ground-truth curvatures.

  16. Incorporating denitrification-decomposition method to estimate field emissions for Life Cycle Assessment.

    Science.gov (United States)

    Deng, Yelin; Paraskevas, Dimos; Cao, Shi-Jie

    2017-09-01

    This study focuses on a detailed Life Cycle Assessment (LCA) for flax cultivation in Northern France. Nitrogen related field emissions are derived both from a process-oriented DeNitrification-DeComposition (DNDC) method and the generic Intergovernmental Panel on Climate Change (IPCC) method. Since the IPCC method is synthesised from field measurements at sites with various soil types, climate conditions, and crops, it contains significant uncertainties. In contrast, the outputs from the DNDC method are considered as more site specific as it is built according to complex models of soil science. As it is demonstrated in this paper the emission factors from the DNDC method and the recommended values from the IPCC method exhibit significant variations for the case of flax cultivation. The DNDC based emission factor for direct N2O emission, which is a strong greenhouse gas, is 0.25-0.5%, significantly lower than the recommend 1% level derived from the IPCC method. The DNDC method leads to a reduction of 17% in the impact category of climate change per kg retted flax straw production from the level obtained from the IPCC method. Much higher reductions are recorded for particulate matter formation, terrestrial acidification, and marine eutrophication impact categories. Meanwhile, based on the DNDC and IPCC methods, a comparative LCA per kg flax straw is presented. For both methods sensitivity analysis as well as comparison of uncertainties parameterisation of the N2O estimates via Monte-Carlo analysis are performed. The DNDC method incorporates more relevant field emissions from the agricultural life cycle phase, which can also improve the quality of the Life Cycle Inventory as well as allow more precise uncertainty calibration in the LCA inventory. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Leisingera sp. JC1, a Bacterial Isolate from Hawaiian Bobtail Squid Eggs, Produces Indigoidine and Differentially Inhibits Vibrios.

    Science.gov (United States)

    Gromek, Samantha M; Suria, Andrea M; Fullmer, Matthew S; Garcia, Jillian L; Gogarten, Johann Peter; Nyholm, Spencer V; Balunas, Marcy J

    2016-01-01

    Female members of many cephalopod species house a bacterial consortium in the accessory nidamental gland (ANG), part of the reproductive system. These bacteria are deposited into eggs that are then laid in the environment where they must develop unprotected from predation, pathogens, and fouling. In this study, we characterized the genome and secondary metabolite production of Leisingera sp. JC1, a member of the roseobacter clade (Rhodobacteraceae) of Alphaproteobacteria isolated from the jelly coat of eggs from the Hawaiian bobtail squid, Euprymna scolopes. Whole genome sequencing and MLSA analysis revealed that Leisingera sp. JC1 falls within a group of roseobacters associated with squid ANGs. Genome and biochemical analyses revealed the potential for and production of a number of secondary metabolites, including siderophores and acyl-homoserine lactones involved with quorum sensing. The complete biosynthetic gene cluster for the pigment indigoidine was detected in the genome and mass spectrometry confirmed the production of this compound. Furthermore, we investigated the production of indigoidine under co-culture conditions with Vibrio fischeri, the light organ symbiont of E. scolopes, and with other vibrios. Finally, both Leisingera sp. JC1 and secondary metabolite extracts of this strain had differential antimicrobial activity against a number of marine vibrios, suggesting that Leisingera sp. JC1 may play a role in host defense against other marine bacteria either in the eggs and/or ANG. These data also suggest that indigoidine may be partially, but not wholly, responsible for the antimicrobial activity of this squid-associated bacterium.

  18. Modeling of magnetic fields on a cylindrical surface and associated parameter estimation for development of a size sensor

    Science.gov (United States)

    Zhang, Song; Rajamani, Rajesh

    2016-11-01

    This paper develops analytical sensing principles for estimation of circumferential size of a cylindrical surface using magnetic sensors. An electromagnet and magnetic sensors are used on a wearable band for measurement of leg size. In order to enable robust size estimation during rough real-world use of the wearable band, three estimation algorithms are developed based on models of the magnetic field variation over a cylindrical surface. The magnetic field models developed include those for a dipole and for a uniformly magnetized cylinder. The estimation algorithms used include a linear regression equation, an extended Kalman filter and an unscented Kalman filter. Experimental laboratory tests show that the size sensor in general performs accurately, yielding sub-millimeter estimation errors. The unscented Kalman filter yields the best performance that is robust to bias and misalignment errors. The size sensor developed herein can be used for monitoring swelling due to fluid accumulation in the lower leg and a number of other biomedical applications.

  19. Molecular characterization of the Jatropha curcas JcR1MYB1 gene encoding a putative R1-MYB transcription factor

    Directory of Open Access Journals (Sweden)

    Hui-Liang Li

    2014-09-01

    Full Text Available The cDNA encoding the R1-MYB transcription factor, designated as JcR1MYB1, was isolated from Jatropha curcas using rapid amplification of cDNA ends. JcR1MYB1 contains a 951 bp open reading frame that encodes 316 amino acids. The deduced JcR1MYB1 protein was predicted to possess the conserved, 56-amino acid-long DNA-binding domain, which consists of a single helix-turn-helix module and usually occurs in R1-MYBs. JcR1MYB1 is a member of the R1-MYB transcription factor subfamily. A subcellular localization study confirmed the nuclear localization of JcR1MYB1. Expression analysis showed that JcR1MYB1 transcripts accumulated in various examined tissues, with high expression levels in the root and low levels in the stem. JcR1MYB1 transcription was up-regulated by polyethylene glycol, NaCl, and cold treatments, as well as by abscisic acid, jasmonic acid, and ethylene treatment. Analysis of transgenic tobacco plants over-expressing JcR1MYB1 indicates an inportant function for this gene in salt stress.

  20. Rapid estimation of Aedes aegypti population size using simulation modeling, with a novel approach to calibration and field validation.

    Science.gov (United States)

    Williams, Craig R; Johnson, Petrina H; Long, Sharron A; Rapley, Luke P; Ritchie, Scott A

    2008-11-01

    New approaches for control of the dengue vector Aedes aegypti (L.) are being developed, including the potential introduction of life-shortening symbiont bacteria into field populations and the release of transgenic strains with reduced vector competency. With these new approaches comes the need for rapid estimations of existing field population size. Here, we describe the use of simulation modeling with container-inhabiting mosquito simulation (CIMSiM) for estimation of Ae. aegypti pupal crop size in north Queensland, Australia. CIMSiM was calibrated for local conditions by deploying "sentinel key containers" (tire, 2-liter plastic bucket, 0.6-liter pot plant base, and tarpaulin indentation) in which water flux and pupal productivity were studied for 72 d. Iterative adjustment of CIMSiM parameters was used to fit model outputs to match that of sentinel key containers. This calibrated model was then used in a blind field validation, in which breeding container and local meteorological data were used to populate CIMSiM, and model outputs were compared with a field pupal survey. Actual pupae per ha during two 10-d periods in 2007 fell within 95% confidence intervals of simulated pupal crop estimates made by 10 replicate simulations in CIMSiM, thus providing a successful field validation. Although the stochasticity of the field environment can never be wholly simulated, CIMSiM can provide field-validated estimates of pupal crop in a timely manner by using simple container surveys.

  1. Estimating decades-long trends in petroleum field energy return on investment (EROI) with an engineering-based model.

    Science.gov (United States)

    Tripathi, Vinay S; Brandt, Adam R

    2017-01-01

    This paper estimates changes in the energy return on investment (EROI) for five large petroleum fields over time using the Oil Production Greenhouse Gas Emissions Estimator (OPGEE). The modeled fields include Cantarell (Mexico), Forties (U.K.), Midway-Sunset (U.S.), Prudhoe Bay (U.S.), and Wilmington (U.S.). Data on field properties and production/processing parameters were obtained from a combination of government and technical literature sources. Key areas of uncertainty include details of the oil and gas surface processing schemes. We aim to explore how long-term trends in depletion at major petroleum fields change the effective energetic productivity of petroleum extraction. Four EROI ratios are estimated for each field as follows: The net energy ratio (NER) and external energy ratio (EER) are calculated, each using two measures of energy outputs, (1) oil-only and (2) all energy outputs. In all cases, engineering estimates of inputs are used rather than expenditure-based estimates (including off-site indirect energy use and embodied energy). All fields display significant declines in NER over the modeling period driven by a combination of (1) reduced petroleum production and (2) increased energy expenditures on recovery methods such as the injection of water, steam, or gas. The fields studied had NER reductions ranging from 46% to 88% over the modeling periods (accounting for all energy outputs). The reasons for declines in EROI differ by field. Midway-Sunset experienced a 5-fold increase in steam injected per barrel of oil produced. In contrast, Prudhoe Bay has experienced nearly a 30-fold increase in amount of gas processed and reinjected per unit of oil produced. In contrast, EER estimates are subject to greater variability and uncertainty due to the relatively small magnitude of external energy investments in most cases.

  2. Excitability of jcBNST neurons is reduced in alcohol-dependent animals during protracted alcohol withdrawal.

    Directory of Open Access Journals (Sweden)

    Attila Szücs

    Full Text Available Alcohol dependence and withdrawal has been shown to cause neuroadaptive changes at multiple levels of the nervous system. At the neuron level, adaptations of synaptic connections have been extensively studied in a number of brain areas and accumulating evidence also shows the importance of alcohol dependence-related changes in the intrinsic cellular properties of neurons. At the same time, it is still largely unknown how such neural adaptations impact the firing and integrative properties of neurons. To address these problems, here, we analyze physiological properties of neurons in the bed nucleus of stria terminalis (jcBNST in animals with a history of alcohol dependence. As a comprehensive approach, first we measure passive and active membrane properties of neurons using conventional current clamp protocols and then analyze their firing responses under the action of simulated synaptic bombardment via dynamic clamp. We find that most physiological properties as measured by DC current injection are barely affected during protracted withdrawal. However, neuronal excitability as measured from firing responses under simulated synaptic inputs with the dynamic clamp is markedly reduced in all 3 types of jcBNST neurons. These results support the importance of studying the effects of alcohol and drugs of abuse on the firing properties of neurons with dynamic clamp protocols designed to bring the neurons into a high conductance state. Since the jcBNST integrates excitatory inputs from the basolateral amygdala (BLA and cortical inputs from the infralimbic and the insular cortices and in turn is believed to contribute to the inhibitory input to the central nucleus of the amygdala (CeA the reduced excitability of the jcBNST during protracted withdrawal in alcohol-dependent animals will likely affect ability of the jcBNST to shape the activity and output of the CeA.

  3. Reconnection electric field estimates and dynamics of high-latitude boundaries during a substorm

    Directory of Open Access Journals (Sweden)

    T. Pitkänen

    2009-05-01

    Full Text Available The dynamics of the polar cap and the auroral oval are examined in the evening sector during a substorm period on 25 November 2000 by using measurements of the EISCAT incoherent scatter radars, the north-south chain of the MIRACLE magnetometer network, and the Polar UV Imager.

    The location of the polar cap boundary (PCB is estimated from electron temperature measurements by the mainland low-elevation EISCAT VHF radar and the 42 m antenna of the EISCAT Svalbard radar. A comparison to the poleward auroral emission (PAE boundary by the Polar UV Imager shows that in this event the PAE boundary is typically located 0.7° of magnetic latitude poleward of the PCB by EISCAT. The convection reversal boundary (CRB is determined from the 2-D plasma drift velocity extracted from the dual-beam VHF data. The CRB is located 0.5–1° equatorward of the PCB indicating the existence of viscous-driven antisunward convection on closed field lines.

    East-west equivalent electrojets are calculated from the MIRACLE magnetometer data by the 1-D upward continuation method. In the substorm growth phase, electrojets together with the polar cap boundary move gradually equatorwards. During the substorm expansion phase, the Harang discontinuity (HD region expands to the MLT sector of EISCAT. In the recovery phase the PCB follows the poleward edge of the westward electrojet.

    The local ionospheric reconnection electric field is calculated by using the measured plasma velocities in the vicinity of the polar cap boundary. During the substorm growth phase, values between 0 and 10 mV/m are found. During the late expansion and recovery phase, the reconnection electric field has temporal variations with periods of 7–27 min and values from 0 to 40 mV/m. It is shown quantitatively, for the first time to our knowledge, that intensifications in the local reconnection electric field correlate with appearance of auroral poleward boundary intensifications (PBIs

  4. Examining view angle effects on leaf N estimation in wheat using field reflectance spectroscopy

    Science.gov (United States)

    Song, Xiao; Feng, Wei; He, Li; Xu, Duanyang; Zhang, Hai-Yan; Li, Xiao; Wang, Zhi-Jie; Coburn, Craig A.; Wang, Chen-Yang; Guo, Tian-Cai

    2016-12-01

    Real-time, nondestructive monitoring of crop nitrogen (N) status is a critical factor for precision N management during wheat production. Over a 3-year period, we analyzed different wheat cultivars grown under different experimental conditions in China and Canada and studied the effects of viewing angle on the relationships between various vegetation indices (VIs) and leaf nitrogen concentration (LNC) using hyperspectral data from 11 field experiments. The objective was to improve the prediction accuracy by minimizing the effects of viewing angle on LNC estimation to construct a novel vegetation index (VI) for use under different experimental conditions. We examined the stability of previously reported optimum VIs obtained from 13 traditional indices for estimating LNC at 13 viewing zenith angles (VZAs) in the solar principal plane (SPP). Backscattering direction showed better index performance than forward scattering direction. Red-edge VIs including modified normalized difference vegetation index (mND705), ratio index within the red edge region (RI-1dB) and normalized difference red edge index (NDRE) were highly correlated with LNC, as confirmed by high R2 determination coefficients. However, these common VIs tended to saturation, as the relationships strongly depended on experimental conditions. To overcome the influence of VZA on VIs, the chlorophyll- and LNC-sensitive NDRE index was divided by the floating-position water band index (FWBI) to generate the integrated narrow-band vegetation index. The highest correlation between the novel NDRE/FWBI parameter and LNC (R2 = 0.852) occurred at -10°, while the lowest correlation (R2 = 0.745) occurred at 60°. NDRE/FWBI was more highly correlated with LNC than existing commonly used VIs at an identical viewing zenith angle. Upon further analysis of angle combinations, our novel VI exhibited the best performance, with the best prediction accuracy at 0° to -20° (R2 = 0.838, RMSE = 0.360) and relatively good accuracy

  5. JC polyomavirus infection is strongly controlled by human leucocyte antigen class II variants.

    Directory of Open Access Journals (Sweden)

    Emilie Sundqvist

    2014-04-01

    Full Text Available JC polyomavirus (JCV carriers with a compromised immune system, such as in HIV, or subjects on immune-modulating therapies, such as anti VLA-4 therapy may develop progressive multifocal leukoencephalopathy (PML which is a lytic infection of oligodendrocytes in the brain. Serum antibodies to JCV mark infection occur only in 50-60% of infected individuals, and high JCV-antibody titers seem to increase the risk of developing PML. We here investigated the role of human leukocyte antigen (HLA, instrumental in immune defense in JCV antibody response. Anti-JCV antibody status, as a surrogate for JCV infection, were compared to HLA class I and II alleles in 1621 Scandinavian persons with MS and 1064 population-based Swedish controls and associations were replicated in 718 German persons with MS. HLA-alleles were determined by SNP imputation, sequence specific (SSP kits and a reverse PCR sequence-specific oligonucleotide (PCR-SSO method. An initial GWAS screen displayed a strong HLA class II region signal. The HLA-DRB1*15 haplotype was strongly negatively associated to JCV sero-status in Scandinavian MS cases (OR = 0.42, p = 7×10(-15 and controls (OR = 0.53, p = 2×10(-5. In contrast, the DQB1*06:03 haplotype was positively associated with JCV sero-status, in Scandinavian MS cases (OR = 1.63, p = 0.006, and controls (OR = 2.69, p = 1×10(-5. The German dataset confirmed these findings (OR = 0.54, p = 1×10(-4 and OR = 1.58, p = 0.03 respectively for these haplotypes. HLA class II restricted immune responses, and hence CD4+ T cell immunity is pivotal for JCV infection control. Alleles within the HLA-DR1*15 haplotype are associated with a protective effect on JCV infection. Alleles within the DQB1*06:03 haplotype show an opposite association. These associations between JC virus antibody response and human leucocyte antigens supports the notion that CD4+ T cells are crucial in the immune defence to JCV and

  6. A new method to estimate doses to the normal tissues after past extended and involved field radiotherapy for Hodgkin lymphoma

    DEFF Research Database (Denmark)

    Maraldo, Maja V; Lundemann, Michael; Vogelius, Ivan R;

    2015-01-01

    INTRODUCTION: Reconstruction of radiotherapy (RT) performed decades ago is challenging, but is necessary to address dose-response questions from epidemiological data and may be relevant in re-irradiation scenarios. Here, a novel method to reconstruct extended and involved field RT for patients...... with Hodgkin lymphoma was used. MATERIALS AND METHODS: For 46 model patients, 29 organs at risk (OARs) were contoured and seven treatment fields reconstructed (mantle, mediastinal, right/left neck, right/left axillary, and spleen field). Extended and involved field RT were simulated by generating RT plans...... by superpositions of the seven individual fields. The mean (standard deviation) of the 46 individual mean organ doses were extracted as percent of prescribed dose for each field superposition. RESULTS: The estimated mean doses to the OARs from 17 field combinations were presented. The inter-patient variability...

  7. Hyperspectral measurements for estimating biophysical parameters and CO2 exchanges in a rice field

    Science.gov (United States)

    Rossini, M.; Migliavacca, M.; Meroni, M.; Manca, G.; Cogliati, S.; Busetto, L.; Picchi, V.; Galvagno, M.; Colombo, R.; Seufert, G.

    2009-04-01

    The objective of this work was to monitor the main biophysical and structural parameters as well as the CO2 exchanges between atmosphere and a terrestrial ecosystem from remote and high spectral resolution spectroradiometric measurements. Estimation of photosynthetic rate or gross primary productivity from remotely sensed data is based on the light use efficiency model (LUE), which states that carbon exchange is a function of the photosynthetically active radiation absorbed by vegetation (APAR) and the radiation use efficiency (ɛ) which represents the conversion efficiency of energy to fixed carbon. Hyperspectral data were used in this study in order to derived both the APAR of green vegetation and the ɛ term. The experimental site was a rice paddy field in North Italy equipped with an Eddy Covariance (EC) flux measurement tower (Castellaro IES-JRC site). Intensive field campaigns were conducted during summer 2007 and 2008. In each sampling day, canopy optical properties, canopy structure, biophysical and ecophysiological parameters were measured. EC fluxes were calculated with a time step of 30 minutes according to EUROFLUX methodology. Measured half-hourly net ecosystem exchange (NEE) was partitioned to derive half hourly gross ecosystem production (GEP). Canopy reflectance spectra were collected under clear sky conditions using two portable spectrometers (HR4000, OceanOptics, USA) characterised by different spectral resolutions. A spectrometer characterised by a Full Width at Half Maximum (FWHM) of 0.13 nm was used to estimate steady-state fluorescence (F) and a second one with a FWHM of 2.8 nm was used for the computation of traditional vegetation indices (e.g. NVDI, Normalized Difference Vegetation Index and SAVI, Soil Adjusted Vegetation Index) and PRI (Photochemical Reflectance Index, Gamon et al. 1992). F was estimated by exploiting a variation of the Fraunhofer Line Depth (FLD) principle (Plascyk 1975): the spectral fitting method described in Meroni

  8. Using coronal seismology to estimate the magnetic field strength in a realistic coronal model

    CERN Document Server

    Chen, Feng

    2015-01-01

    Coronal seismology is extensively used to estimate properties of the corona, e.g. the coronal magnetic field strength are derived from oscillations observed in coronal loops. We present a three-dimensional coronal simulation including a realistic energy balance in which we observe oscillations of a loop in synthesised coronal emission. We use these results to test the inversions based on coronal seismology. From the simulation of the corona above an active region we synthesise extreme ultraviolet (EUV) emission from the model corona. From this we derive maps of line intensity and Doppler shift providing synthetic data in the same format as obtained from observations. We fit the (Doppler) oscillation of the loop in the same fashion as done for observations to derive the oscillation period and damping time. The loop oscillation seen in our model is similar to imaging and spectroscopic observations of the Sun. The velocity disturbance of the kink oscillation shows an oscillation period of 52.5s and a damping tim...

  9. An Entropy-Based Propagation Speed Estimation Method for Near-Field Subsurface Radar Imaging

    Directory of Open Access Journals (Sweden)

    Pistorius Stephen

    2010-01-01

    Full Text Available During the last forty years, Subsurface Radar (SR has been used in an increasing number of noninvasive/nondestructive imaging applications, ranging from landmine detection to breast imaging. To properly assess the dimensions and locations of the targets within the scan area, SR data sets have to be reconstructed. This process usually requires the knowledge of the propagation speed in the medium, which is usually obtained by performing an offline measurement from a representative sample of the materials that form the scan region. Nevertheless, in some novel near-field SR scenarios, such as Microwave Wood Inspection (MWI and Breast Microwave Radar (BMR, the extraction of a representative sample is not an option due to the noninvasive requirements of the application. A novel technique to determine the propagation speed of the medium based on the use of an information theory metric is proposed in this paper. The proposed method uses the Shannon entropy of the reconstructed images as the focal quality metric to generate an estimate of the propagation speed in a given scan region. The performance of the proposed algorithm was assessed using data sets collected from experimental setups that mimic the dielectric contrast found in BMI and MWI scenarios. The proposed method yielded accurate results and exhibited an execution time in the order of seconds.

  10. Porosity Estimation By Artificial Neural Networks Inversion . Application to Algerian South Field

    Science.gov (United States)

    Eladj, Said; Aliouane, Leila; Ouadfeul, Sid-Ali

    2017-04-01

    One of the main geophysicist's current challenge is the discovery and the study of stratigraphic traps, this last is a difficult task and requires a very fine analysis of the seismic data. The seismic data inversion allows obtaining lithological and stratigraphic information for the reservoir characterization . However, when solving the inverse problem we encounter difficult problems such as: Non-existence and non-uniqueness of the solution add to this the instability of the processing algorithm. Therefore, uncertainties in the data and the non-linearity of the relationship between the data and the parameters must be taken seriously. In this case, the artificial intelligence techniques such as Artificial Neural Networks(ANN) is used to resolve this ambiguity, this can be done by integrating different physical properties data which requires a supervised learning methods. In this work, we invert the acoustic impedance 3D seismic cube using the colored inversion method, then, the introduction of the acoustic impedance volume resulting from the first step as an input of based model inversion method allows to calculate the Porosity volume using the Multilayer Perceptron Artificial Neural Network. Application to an Algerian South hydrocarbon field clearly demonstrate the power of the proposed processing technique to predict the porosity for seismic data, obtained results can be used for reserves estimation, permeability prediction, recovery factor and reservoir monitoring. Keywords: Artificial Neural Networks, inversion, non-uniqueness , nonlinear, 3D porosity volume, reservoir characterization .

  11. Smoothing parameter estimation framework for Markov random field by using contextual and spectral information

    Science.gov (United States)

    Aghighi, Hossein; Trinder, John

    2013-10-01

    Markov random field (MRF) is currently the most common method to find the optimal solution for the classification of image data incorporating contextual visual information. The labeling for a site in MRF is dependent on smoothing parameters. Therefore, this paper deals with the development of a new robust two-step method to determine the smoothing parameter which balances spatial and spectral energies for the purpose of maximizing the classification accuracy. Multispectral images obtained by WorldView-2 satellite were employed in this research. In the first step, a support vector machine (SVM) was used to provide a vector of multi-class probability and a class label for each pixel. Then, the summation of the maximum probability of each pixel and its 8 neighbors is calculated for a dynamic block and this value is assigned to the central pixels of each block. The blocks of each class are sorted and an equal proportion of blocks of each class with the highest probability are selected. Then, the class codes and spectral information of the selected blocks are extracted from the classified map and multispectral image, respectively. This information is used to calculate class label co-occurrence matrices of the blocks (CLCMB), class label co-occurrence matrix (CLCM) and class separability indices. Finally, different smoothing parameters are calculated and the results show that estimated smoothing parameter can produce a more accurate map.

  12. ESTIMATION OF FAR-FIELD TSUNAMI POTENTIAL FOR THE CARIBBEAN COAST BASED ON NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Narcisse Zaibo

    2003-01-01

    Full Text Available The tsunami problem for the coast of the Caribbean basin is discussed. Briefly the historical data of tsunami in the Caribbean Sea are presented. Numerical simulation of potential tsunamis in the Caribbean Sea is performed in the framework of the nonlinear-shallow theory. The tsunami wave height distribution along the Caribbean Coast is computed. These results are used to estimate the far-field tsunami potential of various coastal locations in the Caribbean Sea. In fact, five zones with tsunami low risk are selected basing on prognostic computations, they are: the bay “Golfo de Batabano” and the coast of province “Ciego de Avila” in Cuba, the Nicaraguan Coast (between Bluefields and Puerto Cabezas, the border between Mexico and Belize, the bay “Golfo de Venezuela” in Venezuela. The analysis of historical data confirms that there was no tsunami in the selected zones. Also, the wave attenuation in the Caribbean Sea is investigated; in fact, wave amplitude decreases in an order if the tsunami source is located on the distance up to 1000 km from the coastal location. Both factors wave attenuation and wave height distribution should be taken into account in the planned warning system for the Caribbean Sea.

  13. RBE estimation of proton radiation fields using a DeltaE-E telescope.

    Science.gov (United States)

    Wroe, Andrew; Schulte, Reinhard; Fazzi, Alberto; Pola, Andrea; Agosteo, Stefano; Rosenfeld, Anatoly

    2009-10-01

    A new monolithic silicon DeltaE-E telescope was evaluated in unmodulated and modulated 100 MeV proton beams used for hadron therapy. Compared to a classical microdosimetry detector, which provides one-dimensional information on lineal energy of charged particles, this detector system provides two-dimensional information on lineal energy and particle energy based on energy depositions, collected in coincidence, within the DeltaE and E stages of the detector. The authors investigated the possibility to use the information obtained with the DeltaE-E telescope to determine the relative biological effectiveness (RBE) at defined locations within the proton Bragg peak and spread-out Bragg peak (SOBP). An RBE matrix based on the established in vitro V79 cell survival data was developed to link the output of the device directly to RBE(alpha), the RBE in the low-dose limit, at various depths in a homogeneous polystyrene phantom. In the SOBP of a 100 MeV proton beam, the RBE(alpha) increased from 4.04 proximal to the SOBP to a maximum value of 5.4 at the distal edge. The DeltaE-E telescope, with its high spatial resolution, has potential applications to biologically weighted hadron treatment planning as it provides a compact and portable means for estimating the RBE in rapidly changing hadron radiation fields within phantoms.

  14. Dust concentrations and respiratory risks in coalminers: key risk estimates from the British Pneumoconiosis Field Research

    Energy Technology Data Exchange (ETDEWEB)

    Soutar, C.A.; Hurley, J.F.; Miller, B.G.; Cowie, H.A.; Buchanan, D. [Inst. of Occupational Medicine, Edinburgh (United Kingdom)

    2004-06-01

    To help inform the setting of dust control standards in coal mines, this brief review summarises the most recent and reliable exposure-response relations, for damaging respiratory effects, derived from the Pneumoconiosis Field Research (PFR). Collecting data over 38 years in the British coal industry, this was a programme of prospective research on the respiratory health of coal miners, characterised by regular health surveys and detailed measurements of dust and silica concentrations in the workplace. Exposure-response relations are presented for coal workers' simple pneumoconiosis category II, progressive massive fibrosis, defined deficits of lung function (FEV1), and category II silicosis. This simplified overview provides a guide to the most recent and most reliable estimates from the PFR of dust-related risks of substantial pulmonary disease, and to the magnitude of the effects. Control of dust sufficient to prevent category II simple pneumoconiosis should prevent most cases of progressive massive fibrosis and most dust related large lung function deficits. Where the dust contains high proportions of silica, control to low levels is essential, and even quite brief excursions of silica to high levels must be avoided.

  15. Coastal erosion vulnerability estimations by coupling field data and hydrodynamic modeling

    Science.gov (United States)

    Finikianaki, Vasilia; Alexandrakis, George; Poulos, Serafim; Ghionis, George; Kampanis, Nikolaos

    2017-04-01

    Wind generated waves are a dominant factor of coastal zone evolution as they induce nearshore sediment movement. Significant sediment transport and the associated morphological changes of the coastal zone are related, mainly, to storm events. In this study, the effects of a severe storm event, associated with the Etesian winds, that took place from the 24th to 30th of July at Gouves beach (north coast of Crete) were monitored ([1], [2]) and subsequently simulated, with the use of the Delft3D model, in order to provide necessary data for estimating beach vulnerability. Beach vulnerability to erosion was estimated by the BVI method ([3]), which has the ability to refer to smaller sectors of an individual beach. The interaction between waves and currents, which is required for the computation of the BVI, was obtained by the coupling of two models included in Delft3D: the Delft3D - FLOW, for the hydrodynamic computations and the sediment transport processes; and the Delft3D - WAVE, for the computation of the wave field. Boundary conditions were derived from the field data, assuming a JONSWAP spectrum. Additionally, 3 observation points were used for the monitoring of the computed quantities as a function of time. Their positions coincide with those of the three Valeport Autonomous Benthic Recorders, which were deployed at water depths of 2.60m, 3.95m and 5.62m during the field measurements. The outputs of the simulation fit well with the measured data, leading to accurate forecasted results regarding the morphodynamic conditions of the study area. Bottom changes occur mainly during the first peak of the event. The model slightly overestimates the significant wave height, the current velocity in the nearshore area and the suspended sediment concentration near the bed at the observation points. Furthermore, the model predicts a shoreward increase of sediment concentration at the observation points, with the value of accumulation at the second observation point being

  16. Linking field observations, Landsat and MODIS data to estimate agricultural change in European Russia.

    Science.gov (United States)

    de Beurs, K. M.; Ioffe, G.

    2011-12-01

    Agricultural reform has been one of the most important anthropogenic change processes in European Russia that has been unfolding since the formal collapse of the Soviet Union at the end of 1991. Widespread land abandonment is perhaps the most vivid side effect of the reform, even visible in synoptic imagery. Currently, Russia is transitioning into a country with an internal "archipelago" of islands of productive agriculture around cities embedded in a matrix of unproductive, abandoned lands. This heterogeneous spatial pattern is mainly driven by depopulation of the least favorable parts of the countryside, where "least favorable" is a function of fertility, remoteness, and their interaction. In this work we provide a satellite, GIS and field based overview of the current agricultural developments in Russia and look beyond the unstable period immediately following the collapse of the Soviet Union. We apply Landsat images in one of Russia's oblasts to create a detailed land cover map. We then use a logistic model to link the Landsat land cover map with the inter-annual variability in key phenological parameters calculated from MODIS to derive the percent of cropland per 500m MODIS pixel. By evaluating the phenological characteristics of the MODIS curves for each year we determine whether a pixel was actually cropped or left fallow. A comparison of satellite-estimated cropped areas with regional statistics (by rayon) revealed that the satellite estimates are highly correlated with the regional statistics for both arable lands and successfully cropped areas. We use the crop maps to determine the number of times a particular area was cropped between 2002 and 2009 by summing all the years with crops per pixel. This variable provides a good indication about the intensification and de-intensification of the Russian croplands over the last decade. We have visited several rural areas in Russia and we link the satellite data with information acquired through field interviews

  17. Analysis of JC virus DNA replication using a quantitative and high-throughput assay

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jong; Phelan, Paul J.; Chhum, Panharith; Bashkenova, Nazym; Yim, Sung; Parker, Robert [Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111 (United States); Gagnon, David [Institut de Recherches Cliniques de Montreal (IRCM), 110 Pine Avenue West, Montreal, Quebec, Canada H2W 1R7 (Canada); Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec (Canada); Gjoerup, Ole [Molecular Oncology Research Institute, Tufts Medical Center, Boston, MA 02111 (United States); Archambault, Jacques [Institut de Recherches Cliniques de Montreal (IRCM), 110 Pine Avenue West, Montreal, Quebec, Canada H2W 1R7 (Canada); Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec (Canada); Bullock, Peter A., E-mail: Peter.Bullock@tufts.edu [Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111 (United States)

    2014-11-15

    Progressive Multifocal Leukoencephalopathy (PML) is caused by lytic replication of JC virus (JCV) in specific cells of the central nervous system. Like other polyomaviruses, JCV encodes a large T-antigen helicase needed for replication of the viral DNA. Here, we report the development of a luciferase-based, quantitative and high-throughput assay of JCV DNA replication in C33A cells, which, unlike the glial cell lines Hs 683 and U87, accumulate high levels of nuclear T-ag needed for robust replication. Using this assay, we investigated the requirement for different domains of T-ag, and for specific sequences within and flanking the viral origin, in JCV DNA replication. Beyond providing validation of the assay, these studies revealed an important stimulatory role of the transcription factor NF1 in JCV DNA replication. Finally, we show that the assay can be used for inhibitor testing, highlighting its value for the identification of antiviral drugs targeting JCV DNA replication. - Highlights: • Development of a high-throughput screening assay for JCV DNA replication using C33A cells. • Evidence that T-ag fails to accumulate in the nuclei of established glioma cell lines. • Evidence that NF-1 directly promotes JCV DNA replication in C33A cells. • Proof-of-concept that the HTS assay can be used to identify pharmacological inhibitor of JCV DNA replication.

  18. JC polyomavirus infection in candidates for kidney transplantation living in the Brazilian Amazon Region

    Directory of Open Access Journals (Sweden)

    Fernando Assis Ferreira Melo

    2013-04-01

    Full Text Available This study evaluated the relative occurrences of BK virus (BKV and JC virus (JCV infections in patients with chronic kidney disease (CKD. Urine samples were analysed from CKD patients and from 99 patients without CKD as a control. A total of 100 urine samples were analysed from the experimental (CKD patients group and 99 from the control group. Following DNA extraction, polymerase chain reaction (PCR was used to amplify a 173 bp region of the gene encoding the T antigen of the BKV and JCV. JCV and BKV infections were differentiated based on the enzymatic digestion of the amplified products using BamHI endonuclease. The results indicated that none of the patients in either group was infected with the BKV, whereas 11.1% (11/99 of the control group subjects and 4% (4/100 of the kidney patients were infected with the JCV. High levels of urea in the excreted urine, low urinary cellularity, reduced bladder washout and a delay in analysing the samples may have contributed to the low prevalence of infection. The results indicate that there is a need to increase the sensitivity of assays used to detect viruses in patients with CDK, especially given that polyomavirus infections, especially BKV, can lead to a loss of kidney function following transplantation.

  19. JC virus/human immunodeficiency virus 1 co-infection in the Brazilian Amazonian region

    Directory of Open Access Journals (Sweden)

    Izaura Maria Vieira Cayres-Vallinoto

    Full Text Available Abstract JC virus (JCV is a member of the Polyomaviridae family and is associated to a severe disease known as progressive multifocal leukoencephalopathy, PML, which is gradually increasing in incidence as an opportunistic infection among AIDS patients. The present study aimed to investigate the occurrence of JCV among HIV-1 carriers including their types and molecular subtypes and the possible association with disease. Urine samples from 66 HIV-1 infected subjects were investigated for the presence of the virus by amplifying VP1 (215 bp and IG (610 bp regions using the polymerase chain reaction. JCV was detected in 32% of the samples. The results confirmed the occurrence of type B (subtype Af2; in addition, another polyomavirus, BKV, was also detected in 1.5% of samples of the HIV-1 infected subjects. Apparently, there was no significant difference between mono- (HIV-1 only and co-infected (HIV-1/JCV subjects regarding their TCD4+/TCD8+ lymphocyte counts or HIV-1 plasma viral load. Self admitted seizures, hearing and visual loses were not significantly different between the two groups.

  20. Rearrangements of archetypal regulatory regions in JC virus genomes from urine.

    Science.gov (United States)

    Agostini, H T; Ryschkewitsch, C F; Stoner, G L

    1998-01-01

    The regulatory region of progressive multifocal leukoencephalopathy-type JC virus (JCV) is rearranged in each host by a process of deletion and duplication. Of the more than 40 that have been examined, no two regulatory regions have been rearranged identically in the brain. The substrate for this rearrangement appears to be a highly stable archetypal regulatory region excreted in the urine. Its role as the transmissible form of the virus, although inferred, has never been proven. We have now amplified by PCR and cycle-sequenced the regulatory regions from 48 urinary strains of the virus. We find that the urinary form of the regulatory region is not entirely stable. Short deletions and duplications in the range of 2-16 bp were observed in seven of these strains. One of these, an inverted repeat, is a pattern of rearrangement not yet found in the brain. Two others (#208 and 230) showed a 2-bp deletion at position nos. 221 and 222, and an unusual mutation at position no. 219. These two urines were collected in different states of the USA at different times and analysed months apart. It is very unlikely that these unusual changes represent sample contamination or that they arose independently. This finding indicates that archetypal forms of the JCV regulatory region are infectious, despite their relative inactivity in tissue culture. While changes in the archetypal structure can be found, it is clear that rearrangements in the kidney are rare or rarely infectious.

  1. Prevalence and genotype identification of human JC virus in colon cancer in Taiwan.

    Science.gov (United States)

    Lin, Paul Yann; Fung, Chiung-Yau; Chang, Fang-Pei; Huang, Wen-Shih; Chen, Wen-Cheng; Wang, Jeng-Yi; Chang, Deching

    2008-10-01

    Although JC virus (JCV), a human polyomavirus, has been detected in colon cancers, the association between JCV and colon cancer remains controversial. In Taiwan, the prevalence of JCV infection in colon cancer patients has not been reported. Thus, the purpose of this study was to investigate JCV infection in colon cancers in Taiwan. Formalin-fixed, paraffin-embedded tissues from 22 colon cancer patients were examined in this study. Nested PCR was performed to detect viral genomic DNA. The product of the nested PCR flanking the JCV regulatory region was sequenced further. Viral large tumor protein, LT, and late capsid protein, VP1, were examined by immunohistochemistry (IHC). Nested PCR revealed JCV genomic DNA in 86.4% (19/22) of the colon cancer tissue samples. Both rearranged and archetypal genotypes of JCV were identified. Expression of JCV LT was positive in 63.6% (14/22) of the examined colon cancer tissue samples but not in any adjacent normal region. Expression of viral capsid protein VP1 was not detected in any of the tissues examined. The current study demonstrates that JCV genomic DNA was present in the examined colon cancer tissues. The genotypes of JCV in colon cancer tissues were also identified. Expression of viral early protein but not structural capsid protein was detected in the examined colon cancer tissues. Furthermore, a high prevalence of JCV infection in colon cancer tissues in Taiwan was also demonstrated.

  2. The electrical conductivity of the Earth's upper mantle as estimated from satellite measured magnetic field variations. Ph.D. Thesis

    Science.gov (United States)

    Didwall, E. M.

    1981-01-01

    Low latitude magnetic field variations (magnetic storms) caused by large fluctuations in the equatorial ring current were derived from magnetic field magnitude data obtained by OGO 2, 4, and 6 satellites over an almost 5 year period. Analysis procedures consisted of (1) separating the disturbance field into internal and external parts relative to the surface of the Earth; (2) estimating the response function which related to the internally generated magnetic field variations to the external variations due to the ring current; and (3) interpreting the estimated response function using theoretical response functions for known conductivity profiles. Special consideration is given to possible ocean effects. A temperature profile is proposed using conductivity temperature data for single crystal olivine. The resulting temperature profile is reasonable for depths below 150-200 km, but is too high for shallower depths. Apparently, conductivity is not controlled solely by olivine at shallow depths.

  3. A Modified Brain MR Image Segmentation and Bias Field Estimation Model Based on Local and Global Information

    Directory of Open Access Journals (Sweden)

    Wang Cong

    2016-01-01

    Full Text Available Because of the poor radio frequency coil uniformity and gradient-driven eddy currents, there is much noise and intensity inhomogeneity (bias in brain magnetic resonance (MR image, and it severely affects the segmentation accuracy. Better segmentation results are difficult to achieve by traditional methods; therefore, in this paper, a modified brain MR image segmentation and bias field estimation model based on local and global information is proposed. We first construct local constraints including image neighborhood information in Gaussian kernel mapping space, and then the complete regularization is established by introducing nonlocal spatial information of MR image. The weighting between local and global information is automatically adjusted according to image local information. At the same time, bias field information is coupled with the model, and it makes the model reduce noise interference but also can effectively estimate the bias field information. Experimental results demonstrate that the proposed algorithm has strong robustness to noise and bias field is well corrected.

  4. Methodology for time-domain estimation of storm time geoelectric fields using the 3-D magnetotelluric response tensors

    Science.gov (United States)

    Kelbert, Anna; Balch, Christopher C.; Pulkkinen, Antti; Egbert, Gary D.; Love, Jeffrey J.; Rigler, E. Joshua; Fujii, Ikuko

    2017-07-01

    Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of robust algorithms that convolve a magnetic storm time series with a frequency domain impedance for a realistic three-dimensional (3-D) Earth, to estimate the local, storm time geoelectric field. Both frequency domain and time domain approaches are presented and validated against storm time geoelectric field data measured in Japan. The methods are then compared in the context of a real-time application.

  5. Estimating individual exposure to malaria using local prevalence of malaria infection in the field.

    Directory of Open Access Journals (Sweden)

    Ally Olotu

    Full Text Available BACKGROUND: Heterogeneity in malaria exposure complicates survival analyses of vaccine efficacy trials and confounds the association between immune correlates of protection and malaria infection in longitudinal studies. Analysis may be facilitated by taking into account the variability in individual exposure levels, but it is unclear how exposure can be estimated at an individual level. METHOD AND FINDINGS: We studied three cohorts (Chonyi, Junju and Ngerenya in Kilifi District, Kenya to assess measures of malaria exposure. Prospective data were available on malaria episodes, geospatial coordinates, proximity to infected and uninfected individuals and residence in predefined malaria hotspots for 2,425 individuals. Antibody levels to the malaria antigens AMA1 and MSP1(142 were available for 291 children from Junju. We calculated distance-weighted local prevalence of malaria infection within 1 km radius as a marker of individual's malaria exposure. We used multivariable modified Poisson regression model to assess the discriminatory power of these markers for malaria infection (i.e. asymptomatic parasitaemia or clinical malaria. The area under the receiver operating characteristic (ROC curve was used to assess the discriminatory power of the models. Local malaria prevalence within 1 km radius and AMA1 and MSP1(142 antibodies levels were independently associated with malaria infection. Weighted local malaria prevalence had an area under ROC curve of 0.72 (95%CI: 0.66-0.73, 0.71 (95%CI: 0.69-0.73 and 0.82 (95%CI: 0.80-0.83 among cohorts in Chonyi, Junju and Ngerenya respectively. In a small subset of children from Junju, a model incorporating weighted local malaria prevalence with AMA1 and MSP1(142 antibody levels provided an AUC of 0.83 (95%CI: 0.79-0.88. CONCLUSION: We have proposed an approach to estimating the intensity of an individual's malaria exposure in the field. The weighted local malaria prevalence can be used as individual marker of

  6. The gist interpret of enforceability industry standard JC 908-2002 "solid surface materials"%JC 908-2002《实体面材》强制性行业标准要点解释与说明

    Institute of Scientific and Technical Information of China (English)

    刘武强; 金福锦; 陈斌

    2003-01-01

    @@ 1 标准项目的重要性与目的 二○○二年十二月九日,中华人民共和国国家经济贸易委员会(原)以2002第93号公告,批准发布行业标准JC 908-2002,此标准为强制性标准,于2003年3月1日起实施.

  7. A new method for estimating population receptive field topography in visual cortex.

    Science.gov (United States)

    Lee, Sangkyun; Papanikolaou, Amalia; Logothetis, Nikos K; Smirnakis, Stelios M; Keliris, Georgios A

    2013-11-01

    We introduce a new method for measuring visual population receptive fields (pRF) with functional magnetic resonance imaging (fMRI). The pRF structure is modeled as a set of weights that can be estimated by solving a linear model that predicts the Blood Oxygen Level-Dependent (BOLD) signal using the stimulus protocol and the canonical hemodynamic response function. This method does not make a priori assumptions about the specific pRF shape and is therefore a useful tool for uncovering the underlying pRF structure at different spatial locations in an unbiased way. We show that our method is more accurate than a previously described method (Dumoulin and Wandell, 2008) which directly fits a 2-dimensional isotropic Gaussian pRF model to predict the fMRI time-series. We demonstrate that direct-fit models do not fully capture the actual pRF shape, and can be prone to pRF center mislocalization when the pRF is located near the border of the stimulus space. A quantitative comparison demonstrates that our method outperforms the direct-fit methods in the pRF center modeling by achieving higher explained variance of the BOLD signal. This was true for direct-fit isotropic Gaussian, anisotropic Gaussian, and difference of isotropic Gaussians model. Importantly, our model is also capable of exploring a variety of pRF properties such as surround suppression, receptive field center elongation, orientation, location and size. Additionally, the proposed method is particularly attractive for monitoring pRF properties in the visual areas of subjects with lesions of the visual pathways, where it is difficult to anticipate what shape the reorganized pRF might take. Finally, the method proposed here is more efficient in computation time than direct-fit methods, which need to search for a set of parameters in an extremely large searching space. Instead, this method uses the pRF topography to constrain the space that needs to be searched for the subsequent modeling.

  8. National-scale crop type mapping and area estimation using multi-resolution remote sensing and field survey

    Science.gov (United States)

    Song, X. P.; Potapov, P.; Adusei, B.; King, L.; Khan, A.; Krylov, A.; Di Bella, C. M.; Pickens, A. H.; Stehman, S. V.; Hansen, M.

    2016-12-01

    Reliable and timely information on agricultural production is essential for ensuring world food security. Freely available medium-resolution satellite data (e.g. Landsat, Sentinel) offer the possibility of improved global agriculture monitoring. Here we develop and test a method for estimating in-season crop acreage using a probability sample of field visits and producing wall-to-wall crop type maps at national scales. The method is first illustrated for soybean cultivated area in the US for 2015. A stratified, two-stage cluster sampling design was used to collect field data to estimate national soybean area. The field-based estimate employed historical soybean extent maps from the U.S. Department of Agriculture (USDA) Cropland Data Layer to delineate and stratify U.S. soybean growing regions. The estimated 2015 U.S. soybean cultivated area based on the field sample was 341,000 km2 with a standard error of 23,000 km2. This result is 1.0% lower than USDA's 2015 June survey estimate and 1.9% higher than USDA's 2016 January estimate. Our area estimate was derived in early September, about 2 months ahead of harvest. To map soybean cover, the Landsat image archive for the year 2015 growing season was processed using an active learning approach. Overall accuracy of the soybean map was 84%. The field-based sample estimated area was then used to calibrate the map such that the soybean acreage of the map derived through pixel counting matched the sample-based area estimate. The strength of the sample-based area estimation lies in the stratified design that takes advantage of the spatially explicit cropland layers to construct the strata. The success of the mapping was built upon an automated system which transforms Landsat images into standardized time-series metrics. The developed method produces reliable and timely information on soybean area in a cost-effective way and could be implemented in an operational mode. The approach has also been applied for other crops in

  9. Areal rainfall estimation using moving cars as rain gauges - laboratory and field experiment

    Science.gov (United States)

    Rabiei, Ehsan; Haberlandt, Uwe; Sester, Monika; Fitzner, Daniel

    2014-05-01

    Areal precipitation estimation for fine temporal and spatial resolution is still a challenging task. Beside the fact that newly developed instrumentations, e.g. weather radar, provide valuable information with high spatial and temporal resolutions, they are subject to different sources of errors. On the other hand, recording rain gauges provide accurate point rainfall depth, but are still often poor in density. Equipping a car with a GPS device as well as sensors measuring rainfall makes it possible to implement cars on the streets as the moving rain gauges. Initial results from a modeling study assuming arbitrary measurement errors have shown that implementing a reasonable large number of inaccurate measurement devices (raincars) provide more reliable areal precipitations compared to the available rain gauge network. The purpose of this study is to derive relationships between sensor readings and rain rate in a laboratory and quantify the errors. Sensor readings involve wiper frequency and optical sensors which are on the cars to automate wiper activities. Besides, the influence of car speed on the sensor readings is investigated implementing a car-speed simulator. It has been observed that the manual wiper activity adjustment, according to front visibility, shows a strong relationship between rainfall intensity and wiper speed. Two optical sensors calibrated in laboratory showed a relatively strong relationship with the rain intensity recorded by a tipping bucket. A positive relationship between the velocity and the amount of water has been observed meaning that the higher the speed of a car, the higher the amount of water hitting the car. Additionally, some preliminary results of the field experiments are discussed.

  10. Novel Approach for Estimating Nitrogen Content in Paddy Fields Using Low Altitude Remote Sensing System

    Science.gov (United States)

    Saberioon, M. M.; Gholizadeh, A.

    2016-06-01

    Concerns over the use of nitrogen have been increasing due to the high cost of fertilizers and environmental pollutions caused by excess nitrogen application in agricultural fields. Several methods are available to assess the amount of nitrogen in crops, however, they are expensive, time-consuming, inaccurate, and/or require specialists to operate the tools. Researcher recently suggested remote sensing and specifically Low Altitude Remote Sensing (LARS) system of chlorophyll content in crop canopies as a low-cost alternative to estimate plant nitrogen status. The main objective of this study was to develop and test a new Vegetation Index (VI) to determine the status of nitrogen and chlorophyll content in rice leaf by analysing and considering all Visible (Vis) bands. Besides, capability of introduced VI has compared with all known VIs in both Vis and Near Infrared (NIR) bands in canopy scale. To develop the VI, images from 6-pannel leaf colour chart were acquired using Basler Scout scA640-70fc under light-emitting diode lighting, in which principal component analysis was used to retain the lower order principal component to develop a new index called IPCA. A conventional digital camera mounted to an Unmanned Aerial Vehicle (UAV) was also used to acquire images over the rice canopy in Vis bands. Simultaneously, Tetracam agriculture digital camera was employed to acquire rice canopy image in Vis-NIR bands. The results indicated that the proposed index at canopy (r = 0.78) scale could be used as a sensor to determine the status of chlorophyll content consequently for monitoring nitrogen in rice plant through different growth stages. Moreover, results confirmed that a lowcost LARS system would be suited for high spatial and temporal resolution images and data analysis for proper assessment of key nutrients in crop farming in a fast, inexpensive and non-destructive way.

  11. Comparison of aerosol backscatter and wind field estimates from the REAL and the SAMPLE

    Science.gov (United States)

    Mayor, Shane D.; Dérian, Pierre; Mauzey, Christopher F.; Spuler, Scott M.; Ponsardin, Patrick; Pruitt, Jeff; Ramsey, Darrell; Higdon, Noah S.

    2015-09-01

    Although operating at the same near-infrared 1.5- m wavelength, the Raman-shifted Eye-safe Aerosol Lidar (REAL) and the Scanning Aerosol Micro-Pulse Lidar-Eye-safe (SAMPLE) are very different in how they generate and detect laser radiation. We present results from an experiment where the REAL and the SAMPLE were operated side-by-side in Chico, California, in March of 2015. During the non-continuous, eleven day test period, the SAMPLE instrument was operated at maximum pulse repetition frequency (15 kHz) and integrated over the interpulse period of the REAL (0.1 s). Operation at the high pulse repetition frequency resulted in second trip echoes which contaminated portions of the data. The performance of the SAMPLE instrument varied with background brightness--as expected with a photon counting receiver|--yet showed equal or larger backscatter intensity signal to noise ratio throughout the intercomparison experiment. We show that a modest low-pass filter or smooth applied to the REAL raw waveforms (that have 5x higher range resolution) results in significant increases in raw signal-to-noise ratio and image signal-to-noise ratio--a measure of coherent aerosol feature content in the images resulting from the scans. Examples of wind fields and time series of wind estimates from both systems are presented. We conclude by reviewing the advantages and disadvantages of each system and sketch a plan for future research and development activities to optimize the design of future systems.

  12. A procedure to estimate the electric field induced in human body exposed to unknown magnetic sources.

    Science.gov (United States)

    Wang, Wencui; Bottauscio, Oriano; Chiampi, Mario; Giordano, Domenico; Zilberti, Luca

    2013-04-01

    The paper proposes and discusses a boundary element procedure able to predict the distribution of the electric field induced in a human body exposed to a low-frequency magnetic field produced by unknown sources. As a first step, the magnetic field on the body surface is reconstructed starting from the magnetic field values detected on a closed surface enclosing the sources. Then, the solution of a boundary value problem provides the electric field distribution inside the human model. The procedure is tested and validated by considering different non-uniform magnetic field distributions generated by a Helmholtz coil system as well as different locations of the human model.

  13. Leisingera sp. JC1, a Bacterial Isolate from Hawaiian Bobtail Squid Eggs, Produces Indigoidine and Differentially Inhibits Vibrios

    Directory of Open Access Journals (Sweden)

    Samantha M. Gromek

    2016-09-01

    Full Text Available Female members of many cephalopod species house a bacterial consortium that is part of their reproductive system, the accessory nidamental gland (ANG. These bacteria are deposited into eggs that are then laid in the environment where they must develop unprotected from predation, pathogens and fouling. In this study, we characterized the genome and secondary metabolite production of Leisingera sp. JC1, a member of the roseobacter clade (Rhodobacteraceae of Alphaproteobacteria isolated from the jelly coat of eggs from the Hawaiian bobtail squid, Euprymna scolopes. Whole genome sequencing and MLSA analysis revealed that Leisingera sp. JC1 falls within a group of roseobacters associated with squid ANGs. Genome and biochemical analyses revealed the potential for and production of a number of secondary metabolites, including siderophores and acyl-homoserine lactones involved with quorum sensing. The complete biosynthetic gene cluster for the pigment indigoidine was detected in the genome and mass spectrometry confirmed the production of this compound. Furthermore, we investigated the production of indigoidine under co-culture conditions with Vibrio fischeri, the light organ symbiont of E. scolopes, and with other vibrios. Finally, both Leisingera sp. JC1 and secondary metabolite extracts of this strain had differential antimicrobial activity against a number of marine vibrios, suggesting that Leisingera sp. JC1 may play a role in host defense against other marine bacteria either in the eggs and/or ANG. These data also suggest that indigoidine may be partially, but not wholly, responsible for the antimicrobial activity of this squid-associated bacterium. □

  14. Lunar gravitational field estimation and the effects of mismodeling upon lunar satellite orbit prediction. M.S. Thesis

    Science.gov (United States)

    Davis, John H.

    1993-01-01

    Lunar spherical harmonic gravity coefficients are estimated from simulated observations of a near-circular low altitude polar orbiter disturbed by lunar mascons. Lunar gravity sensing missions using earth-based nearside observations with and without satellite-based far-side observations are simulated and least squares maximum likelihood estimates are developed for spherical harmonic expansion fit models. Simulations and parameter estimations are performed by a modified version of the Smithsonian Astrophysical Observatory's Planetary Ephemeris Program. Two different lunar spacecraft mission phases are simulated to evaluate the estimated fit models. Results for predicting state covariances one orbit ahead are presented along with the state errors resulting from the mismodeled gravity field. The position errors from planning a lunar landing maneuver with a mismodeled gravity field are also presented. These simulations clearly demonstrate the need to include observations of satellite motion over the far side in estimating the lunar gravity field. The simulations also illustrate that the eighth degree and order expansions used in the simulated fits were unable to adequately model lunar mascons.

  15. Model of a neural network inertial satellite navigation system capable of estimating the earth's gravitational field gradient

    Science.gov (United States)

    Devyatisil'nyi, A. S.

    2016-09-01

    A model for recognizing inertial and satellite data on an object's motion that are delivered by a set of distributed onboard sensors (newtonmeters, gyros, satellite receivers) has been described. Specifically, the model is capable of estimating the parameters of the gravitational field.

  16. Depth Estimation and Specular Removal for Glossy Surfaces Using Point and Line Consistency with Light-Field Cameras.

    Science.gov (United States)

    Tao, Michael W; Su, Jong-Chyi; Wang, Ting-Chun; Malik, Jitendra; Ramamoorthi, Ravi

    2016-06-01

    Light-field cameras have now become available in both consumer and industrial applications, and recent papers have demonstrated practical algorithms for depth recovery from a passive single-shot capture. However, current light-field depth estimation methods are designed for Lambertian objects and fail or degrade for glossy or specular surfaces. The standard Lambertian photoconsistency measure considers the variance of different views, effectively enforcing point-consistency, i.e., that all views map to the same point in RGB space. This variance or point-consistency condition is a poor metric for glossy surfaces. In this paper, we present a novel theory of the relationship between light-field data and reflectance from the dichromatic model. We present a physically-based and practical method to estimate the light source color and separate specularity. We present a new photo consistency metric, line-consistency, which represents how viewpoint changes affect specular points. We then show how the new metric can be used in combination with the standard Lambertian variance or point-consistency measure to give us results that are robust against scenes with glossy surfaces. With our analysis, we can also robustly estimate multiple light source colors and remove the specular component from glossy objects. We show that our method outperforms current state-of-the-art specular removal and depth estimation algorithms in multiple real world scenarios using the consumer Lytro and Lytro Illum light field cameras.

  17. Estimation of Evapotranspiration from Fields with and without Cover Crops Using Remote Sensing and in situ Methods

    Directory of Open Access Journals (Sweden)

    Christopher Hay

    2012-11-01

    Full Text Available Estimation of actual evapotranspiration (ETa based on remotely sensed imagery is very valuable in agricultural regions where ETa rates can vary greatly from field to field. This research utilizes the image processing model METRIC (Mapping Evapotranspiration at high Resolution with Internalized Calibration to estimate late season, post-harvest ETa rates from fields with a cover crop planted after a cash crop (in this case, a rye/radish/pea mixture planted after spring wheat. Remotely sensed EToF (unit-less fraction of grass-based reference ET, ETo maps were generated using Erdas Imagine software for a 260 km2 area in northeastern South Dakota, USA. Meteorological information was obtained from a Bowen-Ratio Energy Balance System (BREBS located within the image. Nine image dates were used for the growing season, from May through October. Five of those nine were captured during the cover crop season. METRIC was found to successfully differentiate between fields with and without cover crops. In a blind comparison, METRIC compared favorably with the estimated ETa rates found using the BREBS (ETλE, with a difference in total estimated ETa for the cover crop season of 7%.

  18. Evaluating (and Improving) Estimates of the Solar Radial Magnetic Field Component from Line-of-Sight Magnetograms

    Science.gov (United States)

    Leka, K. D.; Barnes, G.; Wagner, E. L.

    2017-02-01

    Although for many solar physics problems the desirable or meaningful boundary is the radial component of the magnetic field Br, the most readily available measurement is the component of the magnetic field along the line of sight to the observer, B_{los}. As this component is only equal to the radial component where the viewing angle is exactly zero, some approximation is required to estimate Br at all other observed locations. In this study, a common approximation known as the "μ-correction", which assumes all photospheric field to be radial, is compared to a method that invokes computing a potential field that matches the observed B_{los}, from which the potential field radial component, Br^{pot} is recovered. We demonstrate that in regions that are truly dominated by a radially oriented field at the resolution of the data employed, the μ-correction performs acceptably if not better than the potential-field approach. However, it is also shown that for any solar structure that includes horizontal fields, i.e. active regions, the potential-field method better recovers both the strength of the radial field and the location of magnetic neutral line.

  19. Estimation of the Birefringence Change in Crystals Induced by Gravitation Field

    OpenAIRE

    Vlokh R.; Kostyrko M.

    2007-01-01

    The effect of gravitation field of spherically symmetric mass on the birefringent properties of crystals has been analysed. It has been shown that the gravitation field with spherical symmetry can lead to a change of birefringence in anisotropic media.

  20. Early Formation of Dust in the Ejecta of Type Ib SN 2006jc and Temperature and Mass of the Dust

    CERN Document Server

    Nozawa, T; Tominaga, N; Sakon, I; Tanaka, M; Suzuki, T; Nomoto, K; Maeda, K; Umeda, H; Limongi, M; Onaka, T

    2008-01-01

    SN 2006jc is a peculiar supernova (SN), in which the formation of dust has been confirmed at an early epoch of ~50 days after the explosion. We investigate the possibility of such an earlier formation of dust grains in the expanding ejecta of SN 2006jc, applying the Type Ib SN model that is developed to reproduce the observed light curve. We find that the rapid decrease of the gas temperature in SN 2006jc enables the condensation of C grains in the C-rich layer at 40--60 days after the explosion, which is followed by the condensation of silicate and oxide grains until ~200 days. The average radius of each grain species is confined to be less than 0.01 micron due to the low gas density at the condensation time. The calculated total dust mass reaches to ~1.5 Msun, of which C dust shares 0.7 Msun. On the other hand, based on the calculated dust temperature, we show that the dust species and mass evaluated to reproduce the spectral energy distribution observed by AKARI and MAGNUM at day 200 are different from tho...

  1. Genetic and epigenetic characteristics of gastric cancers with JC virus T-antigen

    Institute of Scientific and Technical Information of China (English)

    Satoshi Yamaoka; Hiroyuki Yamamoto; Katsuhiko Nosho; Hiroaki Taniguchi; Yasushi Adachi; Shigeru Sasaki; Yoshiaki Arimura; Kohzoh Imai; Yasuhisa Shinomura

    2009-01-01

    AIM: To clarify the significance of JC virus (JCV) T-antigen (T-Ag) expression in human gastric cancer.METHODS: We investigated the relationship between T-Ag detected by immunohistochemistry and Epstein-Barr virus (EBV) infection, microsatellite instability (MSI), and genetic and epigenetic alterations in gastric cancers. Mutations in the p53, β-catenin, KRAS, BRAF,PIK3CA genes were analyzed by polymerase chain reaction (PCR)-single strand conformation polymorphism and DNA sequencing. Allelic losses were determined by PCR at 7 microsatellite loci. Aberrant DNA methylation was analyzed by MethyLight assay.RESULTS: JCV T-Ag protein expression was found in 49% of 90 gastric cancer tissues. T-Ag positivity was not correlated with clinicopathological characteristics.T-Ag expression was detected in a similar percentage of EBV positive cancers (4 of 9, 44%) and EBV negative cancers (35 of 73, 48%). T-Ag expression was detected in a significantly lower percentage of MSI-H cancers (14%) than in non MSI-H cancers (55%, P = 0.005).T-Ag expression was detected in a significantly higher percentage of cancers with nuclear/cytoplasmic localization of β-catenin (15 of 21, 71%) than in cancers without (42%, P = 0.018). p53 mutations were detected in a significantly lower percentage of T-Ag positive cancers (32%) than in T-Ag negative cancers (57%, P = 0.018). T-Ag positive gastric cancers showed a significant increase in the allelic losses and aberrant methylation compared with T-Ag negative gastric cancers ( P = 0.008 and P = 0.003).CONCLUSION: The results suggest that JCV T-Ag is involved in gastric carcinogenesis through multiple mechanisms of genetic and epigenetic alterations.

  2. Antiviral effects of artesunate on JC polyomavirus replication in COS-7 cells.

    Science.gov (United States)

    Sharma, Biswa Nath; Marschall, Manfred; Rinaldo, Christine Hanssen

    2014-11-01

    The human JC polyomavirus (JCPyV) causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). A growing number of patients with induced or acquired immunosuppression are at risk for infection, and no effective antiviral therapy is presently available. The widely used antimalarial drug artesunate has shown broad antiviral activity in vitro but limited clinical success. The aim of this study was to investigate the effect of artesunate on JCPyV replication in vitro. The permissivity for JCPyV MAD-4 was first compared in four cell lines, and the monkey kidney cell line COS-7 was selected. Artesunate caused a concentration-dependent decrease in the extracellular JCPyV DNA load 96 h postinfection, with a 50% effective concentration (EC50) of 2.9 μM. This effect correlated with a decreased expression of capsid protein VP1 and a reduced release of infectious viral progeny. For concentrations of <20 μM, transient reductions in cellular DNA replication and proliferation were seen, while for higher concentrations, some cytotoxicity was detected. A selective index of 16.6 was found when cytotoxicity was calculated based on cellular DNA replication in the mock-infected cells, but interestingly, cellular DNA replication in the JCPyV-infected cells was more strongly affected. In conclusion, artesunate is efficacious in inhibiting JCPyV replication at micromolar concentrations, which are achievable in plasma. The inhibition at EC50 probably reflects an effect on cellular proteins and involves transient cytostatic effects. Our results, together with the favorable distribution of the active metabolite dihydroartemisinin to the central nervous system, suggest a potential use for artesunate in patients with PML.

  3. Estimation of E-J characteristics in a YBCO coated conductor at low temperature and very high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M.; Kiss, T.; Kuga, T.; Ishimaru, M.; Takeo, M.; Matsushita, T.; Iijima, Y.; Kakimoto, K.; Saitoh, T.; Awaji, S.; Watanabe, K.; Shiohara, Y

    2003-10-15

    E-J characteristics in a YBCO coated conductor at low temperature and very high magnetic field up to 27 T have been estimated using experimental E-J characteristics below 12 T along with a scaling analysis based on the percolation model. 1 mm thick YBCO films was deposited on a biaxially aligned Y{sub 2}O{sub 3}/YSZ/Hastelloy substrate fabricated by the IBAD technique. The critical current I{sub c} for the 1 cm wide tape was 85 A at 77 K in self-field. We measured E-J characteristics in perpendicular field up to 12 T using 100 {mu}m wide and 1 mm long bridge patterned in the tape. Statistic J{sub c} distribution and pinning properties were analyzed from the E-J characteristics. Using the pinning parameters determined by the scaling analysis, we can calculate the critical current properties as a function of temperature and magnetic field. E-J characteristics at low temperature and very high magnetic field up to 27 T were estimated analytically and compared with the experimental data. Estimated value of J{sub c} and n-value, and their error analysis were also discussed.

  4. Estimates of metabolic rate and major constituents of metabolic demand in fishes under field conditions: Methods, proxies, and new perspectives.

    Science.gov (United States)

    Treberg, Jason R; Killen, Shaun S; MacCormack, Tyson J; Lamarre, Simon G; Enders, Eva C

    2016-12-01

    Metabolic costs are central to individual energy budgets, making estimates of metabolic rate vital to understanding how an organism interacts with its environment as well as the role of species in their ecosystem. Despite the ecological and commercial importance of fishes, there are currently no widely adopted means of measuring field metabolic rate in fishes. The lack of recognized methods is in part due to the logistical difficulties of measuring metabolic rates in free swimming fishes. However, further development and refinement of techniques applicable for field-based studies on free swimming animals would greatly enhance the capacity to study fish under environmentally relevant conditions. In an effort to foster discussion in this area, from field ecologists to biochemists alike, we review aspects of energy metabolism and give details on approaches that have been used to estimate energetic parameters in fishes. In some cases, the techniques have been applied to field conditions; while in others, the methods have been primarily used on laboratory held fishes but should be applicable, with validation, to fishes in their natural environment. Limitations, experimental considerations and caveats of these measurements and the study of metabolism in wild fishes in general are also discussed. Potential novel approaches to FMR estimates are also presented for consideration. The innovation of methods for measuring field metabolic rate in free-ranging wild fish would revolutionize the study of physiological ecology. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Estimation of transient creep crack-tip stress fields for SE(B) specimen under elastic-plastic-creep conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Han Sang; Je, Jin Ho; Kim, Dong Jun; Kim, Yun Jae [Dept. of Mechanical Engineering, Korea University, Seoul (Korea, Republic of)

    2015-10-15

    This paper estimates the time-dependent crack-tip stress fields under elastic-plastic-creep conditions. We perform Finite-Element (FE) transient creep analyses for a Single-Edge-notched-Bend (SEB) specimen. We investigate the effect of the initial plasticity on the transient creep by systematically varying the magnitude of the initial step-load. We consider both the same stress exponent and different stress exponent in the power-law creep and plasticity to determine the elastic-plastic-creep behaviour. To estimation of the crack-tip stress fields, we compare FE analysis results with those obtained numerically formulas. In addition, we propose a new equation to predict the crack-tip stress fields when the creep exponent is different from the plastic exponent.

  6. Computational estimation of magnetically induced electric fields in a rotating head.

    Science.gov (United States)

    Ilvonen, Sami; Laakso, Ilkka

    2009-01-21

    Change in a magnetic field, or similarly, movement in a strong static magnetic field induces electric fields in human tissues, which could potentially cause harmful effects. In this paper, the fields induced by different rotational movements of a head in a strong homogeneous magnetic field are computed numerically. Average field magnitudes near the retinas and inner ears are studied in order to gain insight into the causes of phosphenes and vertigo-like effects, which are associated with extremely low-frequency (ELF) magnetic fields. The induced electric fields are calculated in four different anatomically realistic head models using an efficient finite-element method (FEM) solver. The results are compared with basic restriction limits by IEEE and ICNIRP. Under rotational movement of the head, with a magnetic flux rate of change of 1 T s(-1), the maximum IEEE-averaged electric field and maximum ICNIRP-averaged current density were 337 mV m(-1) and 8.84 mA m(-2), respectively. The limits by IEEE seem significantly stricter than those by ICNIRP. The results show that a magnetic flux rate of change of 1 T s(-1) may induce electric field in the range of 50 mV m(-1) near retinas, and possibly even larger values near the inner ears. These results provide information for approximating the threshold electric field values of phosphenes and vertigo-like effects.

  7. System of estimations and prognostications of bodily condition of skilled sportsmen in track-and-field

    Directory of Open Access Journals (Sweden)

    Bobrovnyk V.I.

    2013-01-01

    Full Text Available The system of estimation and prognostication of bodily condition of skilled athletes is presented. The system includes the complex of pedagogical tests, evaluation tables, estimation of the functional state vegetative, nervous, cardiovascular systems, system of the external breathing. 436 sportsmen took part in research (212 women and 224 men. The analysis of electrocardiography is conducted, variability of cardiac rhythm, determination of vegetative balance, state of myocardium, violations of rhythm of heart, spirometric researches. The estimation of efficiency of activity of sportsman in extreme terms on the basis of type and properties of temperament, level of personality anxiety and estimation of psychological reliability of sportsmen is presented. The criteria of estimation of physical preparedness are certain, functional state of the basic systems of organism, influencing in a greater degree on achievement of high sporting results, psychological state of sportsmen.

  8. STELLAR LOCI II. A MODEL-FREE ESTIMATE OF THE BINARY FRACTION FOR FIELD FGK STARS

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Haibo; Liu, Xiaowei [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Xiang, Maosheng; Huang, Yang; Chen, Bingqiu [Department of Astronomy, Peking University, Beijing 100871 (China); Wu, Yue [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Hou, Yonghui; Zhang, Yong, E-mail: yuanhb4861@pku.edu.cn, E-mail: x.liu@pku.edu.cn [Nanjing Institute of Astronomical Optics and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing 210042 (China)

    2015-02-01

    We propose a stellar locus outlier (SLOT) method to determine the binary fraction of main-sequence stars statistically. The method is sensitive to neither the period nor mass ratio distributions of binaries and is able to provide model-free estimates of binary fraction for large numbers of stars of different populations in large survey volumes. We have applied the SLOT method to two samples of stars from the Sloan Digital Sky Survey (SDSS) Stripe 82, constructed by combining the recalibrated SDSS photometric data with the spectroscopic information from the SDSS and LAMOST surveys. For the SDSS spectroscopic sample, we find an average binary fraction for field FGK stars of 41% ± 2%. The fractions decrease toward late spectral types and are 44% ± 5%, 43% ± 3%, 35% ± 5%, and 28% ± 6% for stars with g – i colors in the range 0.3-0.6 mag, 0.6-0.9 mag, 0.9-1.2 mag, and 1.2-1.6 mag, respectively. A modest metallicity dependence is also found. The fraction decreases with increasing metallicity. For stars with [Fe/H] between –0.5 and 0.0 dex, –1.0 and –0.5 dex, –1.5 and –1.0 dex, and –2.0 and –1.5 dex, the inferred binary fractions are 37% ± 3%, 39% ± 3%, 50% ± 9%, and 53% ± 20%, respectively. We have further divided the sample into stars from the thin disk, the thick disk, the transition zone between them, and the halo. The results suggest that the Galactic thin and thick disks have comparable binary fractions, whereas the Galactic halo contains a significantly larger fraction of binaries. Applying the method to the LAMOST spectroscopic sample yields consistent results. Finally, other potential applications and future work with the method are discussed.

  9. Field estimates of polyurethane foam - air partition coefficients for hexachlorobenzene, alpha-hexachlorocyclohexane and bromoanisoles.

    Science.gov (United States)

    Bidleman, Terry F; Nygren, Olle; Tysklind, Mats

    2016-09-01

    Partition coefficients of gaseous semivolatile organic compounds (SVOCs) between polyurethane foam (PUF) and air (KPA) are needed in the estimation of sampling rates for PUF disk passive air samplers. We determined KPA in field experiments by conducting long-term (24-48 h) air sampling to saturate PUF traps and shorter runs (2-4 h) to measure air concentrations. Sampling events were done at daily mean temperatures ranging from 1.9 to 17.5 °C. Target compounds were hexachlorobenzene (HCB), alpha-hexachlorocyclohexane (α-HCH), 2,4-dibromoanisole (2,4-DiBA) and 2,4,6-tribromoanisole (2,4,6-TriBA). KPA (mL g(-1)) was calculated from quantities on the PUF traps at saturation (ng g(-1)) divided by air concentrations (ng mL(-1)). Enthalpies of PUF-to-air transfer (ΔHPA, kJ mol(-1)) were determined from the slopes of log KPA/mL g(-1) versus 1/T(K) for HCB and the bromoanisoles, KPA of α-HCH was measured only at 14.3 to 17.5 °C and ΔHPA was not determined. Experimental log KPA/mL g(-1) at 15 °C were HCB = 7.37; α-HCH = 8.08; 2,4-DiBA = 7.26 and 2,4,6-TriBA = 7.26. Experimental log KPA/mL g(-1) were compared with predictions based on an octanol-air partition coefficient (log KOA) model (Shoeib and Harner, 2002a) and a polyparameter linear free relationship (pp-LFER) model (Kamprad and Goss, 2007) using different sets of solute parameters. Predicted KP values varied by factors of 3 to over 30, depending on the compound and the model. Such discrepancies provide incentive for experimental measurements of KPA for other SVOCs.

  10. A Novel Field-Circuit FEM Modeling and Channel Gain Estimation for Galvanic Coupling Real IBC Measurements

    Directory of Open Access Journals (Sweden)

    Yue-Ming Gao

    2016-04-01

    Full Text Available Existing research on human channel modeling of galvanic coupling intra-body communication (IBC is primarily focused on the human body itself. Although galvanic coupling IBC is less disturbed by external influences during signal transmission, there are inevitable factors in real measurement scenarios such as the parasitic impedance of electrodes, impedance matching of the transceiver, etc. which might lead to deviations between the human model and the in vivo measurements. This paper proposes a field-circuit finite element method (FEM model of galvanic coupling IBC in a real measurement environment to estimate the human channel gain. First an anisotropic concentric cylinder model of the electric field intra-body communication for human limbs was developed based on the galvanic method. Then the electric field model was combined with several impedance elements, which were equivalent in terms of parasitic impedance of the electrodes, input and output impedance of the transceiver, establishing a field-circuit FEM model. The results indicated that a circuit module equivalent to external factors can be added to the field-circuit model, which makes this model more complete, and the estimations based on the proposed field-circuit are in better agreement with the corresponding measurement results.

  11. A Novel Field-Circuit FEM Modeling and Channel Gain Estimation for Galvanic Coupling Real IBC Measurements.

    Science.gov (United States)

    Gao, Yue-Ming; Wu, Zhu-Mei; Pun, Sio-Hang; Mak, Peng-Un; Vai, Mang-I; Du, Min

    2016-04-02

    Existing research on human channel modeling of galvanic coupling intra-body communication (IBC) is primarily focused on the human body itself. Although galvanic coupling IBC is less disturbed by external influences during signal transmission, there are inevitable factors in real measurement scenarios such as the parasitic impedance of electrodes, impedance matching of the transceiver, etc. which might lead to deviations between the human model and the in vivo measurements. This paper proposes a field-circuit finite element method (FEM) model of galvanic coupling IBC in a real measurement environment to estimate the human channel gain. First an anisotropic concentric cylinder model of the electric field intra-body communication for human limbs was developed based on the galvanic method. Then the electric field model was combined with several impedance elements, which were equivalent in terms of parasitic impedance of the electrodes, input and output impedance of the transceiver, establishing a field-circuit FEM model. The results indicated that a circuit module equivalent to external factors can be added to the field-circuit model, which makes this model more complete, and the estimations based on the proposed field-circuit are in better agreement with the corresponding measurement results.

  12. Magnetic Helicity Estimations in Models and Observations of the Solar Magnetic Field. Part I: Finite Volume Methods

    Science.gov (United States)

    Valori, Gherardo; Pariat, Etienne; Anfinogentov, Sergey; Chen, Feng; Georgoulis, Manolis K.; Guo, Yang; Liu, Yang; Moraitis, Kostas; Thalmann, Julia K.; Yang, Shangbin

    2016-11-01

    Magnetic helicity is a conserved quantity of ideal magneto-hydrodynamics characterized by an inverse turbulent cascade. Accordingly, it is often invoked as one of the basic physical quantities driving the generation and structuring of magnetic fields in a variety of astrophysical and laboratory plasmas. We provide here the first systematic comparison of six existing methods for the estimation of the helicity of magnetic fields known in a finite volume. All such methods are reviewed, benchmarked, and compared with each other, and specifically tested for accuracy and sensitivity to errors. To that purpose, we consider four groups of numerical tests, ranging from solutions of the three-dimensional, force-free equilibrium, to magneto-hydrodynamical numerical simulations. Almost all methods are found to produce the same value of magnetic helicity within few percent in all tests. In the more solar-relevant and realistic of the tests employed here, the simulation of an eruptive flux rope, the spread in the computed values obtained by all but one method is only 3 %, indicating the reliability and mutual consistency of such methods in appropriate parameter ranges. However, methods show differences in the sensitivity to numerical resolution and to errors in the solenoidal property of the input fields. In addition to finite volume methods, we also briefly discuss a method that estimates helicity from the field lines' twist, and one that exploits the field's value at one boundary and a coronal minimal connectivity instead of a pre-defined three-dimensional magnetic-field solution.

  13. A field comparison of two capture-mark-recapture estimators of small mammal populations

    Directory of Open Access Journals (Sweden)

    Rosana Gentile

    1999-01-01

    Full Text Available The results obtained by two estimators of population sizes, MNKA and Mh, were compared for four species of small mammmals - Didelphis aurita Wied, 1826, Philander frenata (Olfers, 1818, Nectomys squamipes (Brants, 1827 and Akodon cursor (Winge, 1887 - during a long-term population study. The MNKA estimator consistently underestimated the population sizes in relation to Mh. On the other, the probabilistic estimator Mh, which reduces bias through the jackknife technique, could not be used in all cases as its assumptions were not always met. Correction factors between the estimates obtained by the two methods were calculated for the last three species, for which catchability did not vary significantly in time and that presented positive correlation between the estimates by the two models. In order to combine the adavantages of both methods for small mammal population studies, is suggested the use of probabilistic closed population models and to calculate a correction factor based in another model which allow estimates in all cases, and which provides correlated estimates. This correction factors should be used in those cases where the probabilistic model cannot be used.

  14. Pollutant Flux Estimation in an Estuary Comparison between Model and Field Measurements

    Directory of Open Access Journals (Sweden)

    Yen-Chang Chen

    2014-08-01

    Full Text Available This study proposes a framework for estimating pollutant flux in an estuary. An efficient method is applied to estimate the flux of pollutants in an estuary. A gauging station network in the Danshui River estuary is established to measure the data of water quality and discharge based on the efficient method. A boat mounted with an acoustic Doppler profiler (ADP traverses the river along a preselected path that is normal to the streamflow to measure the velocities, water depths and water quality for calculating pollutant flux. To know the characteristics of the estuary and to provide the basis for the pollutant flux estimation model, data of complete tidal cycles is collected. The discharge estimation model applies the maximum velocity and water level to estimate mean velocity and cross-sectional area, respectively. Thus, the pollutant flux of the estuary can be easily computed as the product of the mean velocity, cross-sectional area and pollutant concentration. The good agreement between the observed and estimated pollutant flux of the Danshui River estuary shows that the pollutant measured by the conventional and the efficient methods are not fundamentally different. The proposed method is cost-effective and reliable. It can be used to estimate pollutant flux in an estuary accurately and efficiently.

  15. Estimation of field-scale soil hydraulic and dielectric parametersthrough joint inversion of GPR and hydrological data

    Energy Technology Data Exchange (ETDEWEB)

    Kowalsky, Michael B.; Finsterle, Stefan; Peterson, John; Hubbard,Susan; Rubin, Yoram; Majer, Ernest; Ward, Andy; Gee, Glendon

    2005-05-05

    A method is described for jointly using time-lapse multiple-offset cross-borehole ground-penetrating radar (GPR) travel time measurements and hydrological measurements to estimate field-scale soil hydraulic parameters and parameters of the petrophysical function, which relates soil porosity and water saturation to the effective dielectric constant. We build upon previous work to take advantage of a wide range of GPR data acquisition configurations and to accommodate uncertainty in the petrophysical function. Within the context of water injection experiments in the vadose zone, we test our inversion methodology with synthetic examples and apply it to field data. The synthetic examples show that while realistic errors in the petrophysical function cause substantial errors in the soil hydraulic parameter estimates,simultaneously estimating petrophysical parameters allows for these errors to be minimized. Additionally, we observe in some cases that inaccuracy in the GPR simulator causes systematic error in simulated travel times, making necessary the simultaneous estimation of a correction parameter. We also apply the method to a three-dimensional field setting using time-lapse GPR and neutron probe (NP) data sets collected during an infiltration experiment at the U.S. Department of Energy (DOE) Hanford site in Washington. We find that inclusion of GPR data in the inversion procedure allows for improved predictions of water content, compared to predictions made using NP data alone.

  16. Validation of SCS CN Method for Runoff Estimation with Field Observed Regression Analysis Results in Venna Basin, Central India.

    Science.gov (United States)

    Katpatal, Y. B.; Paranjpe, S. V.; Kadu, M.

    2014-12-01

    Effective Watershed management requires authentic data of surface runoff potential for which several methods and models are in use. Generally, non availability of field data calls for techniques based on remote observations. Soil Conservation Services Curve Number (SCS CN) method is an important method which utilizes information generated from remote sensing for estimation of runoff. Several attempts have been made to validate the runoff values generated from SCS CN method by comparing the results obtained from other methods. In the present study, runoff estimation through SCS CN method has been performed using IRS LISS IV data for the Venna Basin situated in the Central India. The field data was available for Venna Basin. The Land use/land cover and soil layers have been generated for the entire watershed using the satellite data and Geographic Information System (GIS). The Venna basin have been divided into intercepted catchment and free catchment. Run off values have been estimated using field data through regression analysis. The runoff values estimated using SCS CN method have been compared with yield values generated using data collected from the tank gauge stations and data from the discharge stations. The correlation helps in validation of the results obtained from the SCS CN method and its applicability in Indian conditions. Key Words: SCS CN Method, Regression Analysis, Land Use / Land cover, Runoff, Remote Sensing, GIS.

  17. Application of the Nordtest method for "real-time" uncertainty estimation of on-line field measurement.

    Science.gov (United States)

    Näykki, Teemu; Virtanen, Atte; Kaukonen, Lari; Magnusson, Bertil; Väisänen, Tero; Leito, Ivo

    2015-10-01

    Field sensor measurements are becoming more common for environmental monitoring. Solutions for enhancing reliability, i.e. knowledge of the measurement uncertainty of field measurements, are urgently needed. Real-time estimations of measurement uncertainty for field measurement have not previously been published, and in this paper, a novel approach to the automated turbidity measuring system with an application for "real-time" uncertainty estimation is outlined based on the Nordtest handbook's measurement uncertainty estimation principles. The term real-time is written in quotation marks, since the calculation of the uncertainty is carried out using a set of past measurement results. There are two main requirements for the estimation of real-time measurement uncertainty of online field measurement described in this paper: (1) setting up an automated measuring system that can be (preferably remotely) controlled which measures the samples (water to be investigated as well as synthetic control samples) the way the user has programmed it and stores the results in a database, (2) setting up automated data processing (software) where the measurement uncertainty is calculated from the data produced by the automated measuring system. When control samples with a known value or concentration are measured regularly, any instrumental drift can be detected. An additional benefit is that small drift can be taken into account (in real-time) as a bias value in the measurement uncertainty calculation, and if the drift is high, the measurement results of the control samples can be used for real-time recalibration of the measuring device. The procedure described in this paper is not restricted to turbidity measurements, but it will enable measurement uncertainty estimation for any kind of automated measuring system that performs sequential measurements of routine samples and control samples/reference materials in a similar way as described in this paper.

  18. Characterization of electrocaloric properties by indirect estimation and direct measurement of temperature-electric field hysteresis loops

    Science.gov (United States)

    Maiwa, Hiroshi

    2015-10-01

    The electrocaloric properties of Pb(Zr,Ti)O3(PZT)-based and Ba(Zr,Ti)O3 ceramics and Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) crystals were investigated by the indirect estimation and direct measurement of temperature-electric field (T-E) hysteresis loops. The measured T-E loops showed a similar shape to strain-electric field (s-E) loops. The adiabatic temperature change ΔT due to electrocaloric effects was estimated from the polarization change of these samples. ΔTs of 0.48 and 0.66 K were estimated for the (Pb,La)(Zr,Ti)O3 (PLZT)(9.1/65/35) ceramics and PMN-PT crystals under a field of 30 kV/cm, respectively. The measured temperature changes ΔTs in these samples upon the release of the electric field from 30 kV/cm to zero were 0.39 and 0.36 K, respectively.

  19. Estimation of visibility of phase contrast with extraction voltages for field emission gun electron microscopes.

    Science.gov (United States)

    Meng, Xing

    2017-02-01

    Estimation was made for visibility of phase contrast with varying extraction voltages. The resulting decay rates of visibility show that images with low image contrast from cryo EM will be seriously impacted with high extraction voltages.

  20. Enhanced Jc's of YBa2Cu3O7-x-Ag ex situ annealed coevaporated films on LaAlO3 (100) substrates

    DEFF Research Database (Denmark)

    Clausen, Thomas; Ejrnæs, Mikkel; Olesen, Michael Wiinberg

    1995-01-01

    A 5x increase of the critical current density (J(c)) at 77 K was obtained by coating a coevaporated 500 nm thick Y, BaF2, Cu film with 50 nm Ag prior to the ex situ annealing. J(c) increased from 0.2 for uncoated samples to 1 MA/cm(2) for the Ag-coated sample without severely affecting the zero...

  1. Estimating Parameters of Aquifer Heterogeneity Using Pumping Tests - a Paradigm for Field Applications

    Science.gov (United States)

    Zech, Alraune; Arnold, Sven; Schneider, Christoph; Attinger, Sabine

    2013-04-01

    The vast majority of natural aquifers are characterized by heterogeneity which can be statistically represented by parameters such as geometric mean, correlation lengths and variance of hydraulic conductivity. Head measurements of pumping tests are commonly used to estimate the hydraulic properties of porous media. Zech et al. 2012, WRR introduced the effective well flow method allowing a direct parameter estimation from steady state pumping test drawdowns. However, in contrast to simulated pumping tests, the number and spatial distribution of piezometers is limited for on-site pumping tests. We analyze the capability of the effective well flow method to provide accurate and confident parameter estimates of a heterogeneous aquifer under limited availability of head measurements. We use simulated pumping tests to systematically reduce sampling size while also determining the accuracy and uncertainty of estimates at each level of data availability. The same analytical solution is then applied to estimate the statistical parameters of a fluvial heterogeneous aquifer at the test site Horkheimer Insel, Germany. We thereby close the gap between theoretical and practical application of an analytical solution describing three-dimensional steady state well flow. Our findings indicate how accuracy and uncertainty of estimated parameters, like mean conductivities and correlation lengths correlate to number and spatial distribution of head measurements. The results provide valuable implications regarding the conceptual design of ground water pumping tests and the predictive power of established pumping test sites.

  2. Maximum Likelihood Estimation of Monocular Optical Flow Field for Mobile Robot Ego-motion

    Directory of Open Access Journals (Sweden)

    Huajun Liu

    2016-01-01

    Full Text Available This paper presents an optimized scheme of monocular ego-motion estimation to provide location and pose information for mobile robots with one fixed camera. First, a multi-scale hyper-complex wavelet phase-derived optical flow is applied to estimate micro motion of image blocks. Optical flow computation overcomes the difficulties of unreliable feature selection and feature matching of outdoor scenes; at the same time, the multi-scale strategy overcomes the problem of road surface self-similarity and local occlusions. Secondly, a support probability of flow vector is defined to evaluate the validity of the candidate image motions, and a Maximum Likelihood Estimation (MLE optical flow model is constructed based not only on image motion residuals but also their distribution of inliers and outliers, together with their support probabilities, to evaluate a given transform. This yields an optimized estimation of inlier parts of optical flow. Thirdly, a sampling and consensus strategy is designed to estimate the ego-motion parameters. Our model and algorithms are tested on real datasets collected from an intelligent vehicle. The experimental results demonstrate the estimated ego-motion parameters closely follow the GPS/INS ground truth in complex outdoor road scenarios.

  3. Daily SST fields produced by blending infrared and microwave radiometer estimates

    Digital Repository Service at National Institute of Oceanography (India)

    Sreejith, O.P.; Shenoi, S.S.C.

    passes) sensors to produce a daily field at a spatial resolution of 18 km. The new SST fields when compared with in situ measurements (drifting buoy SSTs) showed improvement (Root Mean Square Error of 0.659 degrees C). The corresponding root mean square...

  4. Reliability of different mark-recapture methods for population size estimation tested against reference population sizes constructed from field data.

    Directory of Open Access Journals (Sweden)

    Annegret Grimm

    evaluate the performance of mark-recapture population size estimators under field conditions, which is essential for selecting an appropriate method and obtaining reliable results in ecology and conservation biology, and thus for sound management.

  5. Symbiotic N2 fixation in pea and field bean estimated by 15N fertilizer dilution in field experiments with barley as a reference crop

    DEFF Research Database (Denmark)

    Jensen, Erik Steen

    1986-01-01

    years. At the full bloom/flat pod growth stage from 30 to 59 per cent of total N2 fixation had taken place. The proportion of total N derived from N2 fixation at maturity was higher in seeds than in vegetative plant parts and amounted to 59.5, 51.3 and 66.3 per cent of total above-ground plant N...... in the two pea cultivars and field bean, respectively (three-year means). The recovery of fertilizer N was 62.2, 70.2, 52.1, and 69.5 per cent in the two pea cultivars, field bean and barley, respectively. Growth analysis indicated that barley did not meet the claims for an ideal reference crop in the15N...... fertilizer dilution technique for estimating N2 fixation in pea and field bean. ‘Starter’-N neither increased the seed yield nor the N content of the grain legumes....

  6. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations

    Science.gov (United States)

    Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi

    2016-09-01

    Decades of exploration for venting sites along spreading ridge crests have produced global datasets that yield estimated mean site spacings of ∼ 12- 220 km. This conclusion demands that sites where hydrothermal fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) sites of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated sites discharging particle-poor plumes (25% of all sites) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent sites on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of hydrothermal discharge.

  7. A novel aldo-keto reductase from Jatropha curcas L. (JcAKR) plays a crucial role in the detoxification of methylglyoxal, a potent electrophile.

    Science.gov (United States)

    Mudalkar, Shalini; Sreeharsha, Rachapudi Venkata; Reddy, Attipalli Ramachandra

    2016-05-20

    Abiotic stress leads to the generation of reactive oxygen species (ROS) which further results in the production of reactive carbonyls (RCs) including methylglyoxal (MG). MG, an α, β-dicarbonyl aldehyde, is highly toxic to plants and the mechanism behind its detoxification is not well understood. Aldo-keto reductases (AKRs) play a role in detoxification of reactive aldehydes and ketones. In the present study, we cloned and characterised a putative AKR from Jatropha curcas (JcAKR). Phylogenetically, it forms a small clade with AKRs of Glycine max and Rauwolfia serpentina. JcAKR was heterologously expressed in Escherichia coli BL-21(DE3) cells and the identity of the purified protein was confirmed through MALDI-TOF analysis. The recombinant protein had high enzyme activity and catalytic efficiency in assays containing MG as the substrate. Protein modelling and docking studies revealed MG was efficiently bound to JcAKR. Under progressive drought and salinity stress, the enzyme and transcript levels of JcAKR were higher in leaves compared to roots. Further, the bacterial and yeast cells expressing JcAKR showed more tolerance towards PEG (5%), NaCl (200mM) and MG (5mM) treatments compared to controls. In conclusion, our results project JcAKR as a possible and potential target in crop improvement for abiotic stress tolerance.

  8. IFN-Gamma Inhibits JC Virus Replication in Glial Cells by Suppressing T-Antigen Expression.

    Directory of Open Access Journals (Sweden)

    Francesca Isabella De-Simone

    Full Text Available Patients undergoing immune modulatory therapies for the treatment of autoimmune diseases such as multiple sclerosis, and individuals with an impaired-immune system, most notably AIDS patients, are in the high risk group of developing progressive multifocal leukoencephalopathy (PML, an often lethal disease of the brain characterized by lytic infection of oligodendrocytes in the central nervous system (CNS with JC virus (JCV. The immune system plays an important regulatory role in controlling JCV reactivation from latent sites by limiting viral gene expression and replication. However, little is known regarding the molecular mechanisms responsible for this regulation.Here, we investigated the impact of soluble immune mediators secreted by activated PBMCs on viral replication and gene expression by cell culture models and molecular virology techniques. Our data revealed that viral gene expression and viral replication were suppressed by soluble immune mediators. Further studies demonstrated that soluble immune mediators secreted by activated PBMCs inhibit viral replication induced by T-antigen, the major viral regulatory protein, by suppressing its expression in glial cells. This unexpected suppression of T-antigen was mainly associated with the suppression of translational initiation. Cytokine/chemokine array studies using conditioned media from activated PBMCs revealed several candidate cytokines with possible roles in this regulation. Among them, only IFN-γ showed a robust inhibition of T-antigen expression. While potential roles for IFN-β, and to a lesser extent IFN-α have been described for JCV, IFN-γ has not been previously implicated. Further analysis of IFN-γ signaling pathway revealed a novel role of Jak1 signaling in control of viral T-antigen expression. Furthermore, IFN-γ suppressed JCV replication and viral propagation in primary human fetal glial cells, and showed a strong anti-JCV activity.Our results suggest a novel role for

  9. Características técnicas de pontas de pulverização LA-1JC e SR-1 Technical characteristics of LA-1JC and SR-1 spray nozzles

    Directory of Open Access Journals (Sweden)

    R.G. Viana

    2007-03-01

    Full Text Available Objetivou-se neste trabalho avaliar as características técnicas das pontas de pulverização tipo espuma LA-1JC e SR-1, sob diferentes pressões de trabalho e altura de barra de pulverização. Avaliaram-se, nas pressões de 100, 200 e 300 kPa, o perfil de distribuição de cada ponta, o coeficiente de variação da distribuição volumétrica, a vazão, o diâmetro da mediana volumétrica (DMV, o diâmetro da mediana numérica (DMN, o coeficiente de homogeneidade (CH, o índice de simetria das pontas e os ângulos de abertura esquerdo, direito e total. A ponta LA-1JC, em todas as pressões, e a ponta SR-1, na pressão de 100 kPa, apresentaram perfil de distribuição contínuo. Nas pressões de 200 e 300 kPa a ponta SR-1 apresentou perfil de distribuição descontínuo. Ambas as pontas apresentaram melhor perfil de distribuição com menor espaçamento entre pontas, maior pressão e maior altura da barra. Houve aumento na abertura do ângulo e vazão com incremento na pressão em ambas as pontas. O espectro de gotas obtido é adequado para aplicação de herbicidas sistêmicos em pós-emergência e para herbicidas aplicados em pré-emergência. As pontas LA-1JC, na pressão de 100 kPa, e SR-1, em todas as pressões, não devem ser utilizadas com sobreposição de jatos.This study aimed to evaluate the technical characteristics of LA-1JC and SR-1 skim nozzles, at different pressures and spray boom heights. Each nozzle distribution profile, volumetric distribution quotient in one spray boom, rate, volumetric median diameter (VMD, numeric median diameter( NMD,coefficient of homogeneity, nozzle symmetry index and left, right and total opening angles were evaluated at 100, 200, and 300 kPa. Nozzles showed continuous profile at 100 kPa for SR-1 nozzle and at all pressures for LA-1JC nozzle. The SR-1 nozzle showed discontinuous distribution profile at pressures 200 and 300 kPa. The best profile for both nozzles was verified when nozzles were smaller

  10. SUPER STRONG MAGNETIC FIELDS OF NEUTRON STARS IN BE X-RAY BINARIES ESTIMATED WITH NEW TORQUE AND MAGNETOSPHERE MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Chang-Sheng; Zhang, Shuang-Nan [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Li, Xiang-Dong, E-mail: zhangsn@ihep.ac.cn [Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093 (China)

    2015-11-10

    We re-estimate the surface magnetic fields of neutron stars (NSs) in Be X-ray binaries (BeXBs) with different models of torque, improved beyond Klus et al. In particular, a new torque model is applied to three models of magnetosphere radius. Unlike the previous models, the new torque model does not lead to divergent results for any fastness parameter. The inferred surface magnetic fields of these NSs for the two compressed magnetosphere models are much higher than that for the uncompressed magnetosphere model. The new torque model using the compressed magnetosphere radius leads to unique solutions near spin equilibrium in all cases, unlike other models that usually give two branches of solutions. Although our conclusions are still affected by the simplistic assumptions about the magnetosphere radius calculations, we show several groups of possible surface magnetic field values with our new models when the interaction between the magnetosphere and the infalling accretion plasma is considered. The estimated surface magnetic fields for NSs BeXBs in the Large Magellanic Cloud, the Small Magellanic Cloud and the Milk Way are between the quantum critical field and the maximum “virial” value by the spin equilibrium condition.

  11. A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Orsted data

    DEFF Research Database (Denmark)

    Olsen, Nils

    2002-01-01

    The availability of high-precision geomagnetic measurements from satellites such as Orsted and CHAMP opens a new era in geomagnetic field research. However, in order to take full advantage of the improved data accuracy it is necessary to refine the usual way of deriving field models from satellite...... as measured simultaneously by globally distributed geomagnetic observatories. In addition, the observatory data are used to constrain secular variation. The model is estimated using an iteratively reweighted least-squares method with Huber weights to account for the non-Gaussian data error distribution...

  12. Pair-Wise, Deformable Mirror, Image Plane-Based Diversity Electric Field Estimation for High Contrast Coronagraphy

    Science.gov (United States)

    Give'on, Amir; Kern, Brian D.; Shaklan, Stuart

    2011-01-01

    In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.

  13. Percent body fat estimations in college women using field and laboratory methods: a three-compartment model approach

    Directory of Open Access Journals (Sweden)

    Dalbo Vincent J

    2007-11-01

    Full Text Available Abstract Background Methods used to estimate percent body fat can be classified as a laboratory or field technique. However, the validity of these methods compared to multiple-compartment models has not been fully established. This investigation sought to determine the validity of field and laboratory methods for estimating percent fat (%fat in healthy college-age women compared to the Siri three-compartment model (3C. Methods Thirty Caucasian women (21.1 ± 1.5 yrs; 164.8 ± 4.7 cm; 61.2 ± 6.8 kg had their %fat estimated by BIA using the BodyGram™ computer program (BIA-AK and population-specific equation (BIA-Lohman, NIR (Futrex® 6100/XL, a quadratic (SF3JPW and linear (SF3WB skinfold equation, air-displacement plethysmography (BP, and hydrostatic weighing (HW. Results All methods produced acceptable total error (TE values compared to the 3C model. Both laboratory methods produced similar TE values (HW, TE = 2.4%fat; BP, TE = 2.3%fat when compared to the 3C model, though a significant constant error (CE was detected for HW (1.5%fat, p ≤ 0.006. The field methods produced acceptable TE values ranging from 1.8 – 3.8 %fat. BIA-AK (TE = 1.8%fat yielded the lowest TE among the field methods, while BIA-Lohman (TE = 2.1%fat and NIR (TE = 2.7%fat produced lower TE values than both skinfold equations (TE > 2.7%fat compared to the 3C model. Additionally, the SF3JPW %fat estimation equation resulted in a significant CE (2.6%fat, p ≤ 0.007. Conclusion Data suggest that the BP and HW are valid laboratory methods when compared to the 3C model to estimate %fat in college-age Caucasian women. When the use of a laboratory method is not feasible, NIR, BIA-AK, BIA-Lohman, SF3JPW, and SF3WB are acceptable field methods to estimate %fat in this population.

  14. OPTICAL FLOW APPLIED TO TIME-LAPSE IMAGE SERIES TO ESTIMATE GLACIER MOTION IN THE SOUTHERN PATAGONIA ICE FIELD

    OpenAIRE

    E. Lannutti; Lenzano, M. G.; Toth, C; L. Lenzano; Rivera, A.

    2016-01-01

    In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically complex and hard to access areas, deploying time-lapse imaging sensors, optical flow may provide an efficient solution at good spatial and te...

  15. Erratum to: Estimating the crop response to fertilizer nitrogen residues in long-continued field experiments

    DEFF Research Database (Denmark)

    Petersen, Jens; Thomsen, Ingrid Kaag; Mattson, L

    2012-01-01

    Knowledge of the cumulated effect of long-continued nitrogen (N) inputs is important for both agronomic and environmental reasons. However, only little attention has been paid to estimate the crop response to mineral fertilizer N residues. Before interpreting estimates for the crop response...... yield of spring barley decreased by an average of 5 kg DM/ha and the grain N offtake by 46 g N/ha for a decrease in the annual mineral N rate of 1 kg N/ha applied for more than three decades. Although statistically significant, the crop response to mineral fertilizer N residues was of minor importance...

  16. JC virus and tumorigenesis%JC病毒与肿瘤的研究进展

    Institute of Scientific and Technical Information of China (English)

    郑玉双; 郑华川

    2012-01-01

    目的:总结JC病毒(JCV)研究现状,深入分析JCV T抗原致癌机制及未来研究方向.方法:应用PubMed数据库检索系统,以“JC virus”或“John Cunningham virus”为关键词,检索1991-01-2012-06的相关文献,共检索到英文文献1599条.纳入标准:1)JCV的基因组结构特点 ;2)JCV编码产物的生物学功能 ;3)JCV与恶性肿瘤发生、发展的关系.根据纳入标准,符合分析的文献41篇.结果:JCV属于多瘤DNA病毒家族成员,基因组早期编码区经选择性剪接编码T抗原和t抗原,晚期编码区编码衣壳蛋白VP1、VP2、VP3及调节蛋白Agno.T抗原可与抑癌基因p53和Rb蛋白结合后导致其失活,使Wnt和IGF信号传导途径发生紊乱,影响基因组稳定性,进而参与肿瘤发生.JCV经静脉、颅内注射及转基因动物实验表明,其可引发各种神经系统肿瘤 ;体内实验结果提示,JCV T抗原DNA存在与消化道、呼吸道肿瘤以及B细胞淋巴瘤关系密切.结论:JCV基因组嵌入后正确表达与恶性肿瘤发生关系密切,运用JCVT抗原建立恶性上皮肿瘤转基因动物研究,不但可证实其与恶性上皮肿瘤的关系,也为揭示其致癌机制和上皮肿瘤的基因治疗提供重要手段.%OBJECTIVE:To summarize the study situation of John Cunningham virus (JCV)and analyze the oncogen-ic role of JCV and future aspect. METHODS: The papers were collected from PubMed database between 1991-01 and 2012-06 according to the key words:"JC virus" OR "John Cunningham virus" (n=l 599) and selected in terms of the following criteria:1) The genomic DNA of JCV; 2) The biological function of JCV encoding products; 3) The relationship between JCV and carcinogenesis(n = 41). RESULTS: JCV is a member of the family of polyoma DNA viruses. The early region of JCV genomic DNA is alternatively spliced to produce large T antigen and small t antigen. The late region encodes the caspid structural protein VP1 , VP2 and VP3 and the regulatory protein

  17. ESTIMATION OF DIRECTIONAL SPECTRUM AND REFLECTED COEFFICIENT OF INCIDENT AND REFLECTED WAVE IN PHASE-LOCKED WAVE FIELD

    Institute of Scientific and Technical Information of China (English)

    SHAO Li-min; YU Zhi-liang; YUAN Qun-zhe; YU Yu-xiu

    2005-01-01

    This paper analyses and compares the property of the Modified Bayesian Directional spectrum analysis Method (MBDM) and the Modified Maximum Likelihood Method (MMLM) that can be used to estimate directional spectrum and reflected coefficient of phase-locked wave field overlapped by multi-directional irregular incident and reflected waves.The numerical test verifies the results under different wave conditions, different measurement systems, and different reflection features.The computation speed and stability of the two methods is also compared.The analysis addresses that the MBDM is better than the MMLM for directional spectrum estimating, while the MMLM is better than the MBDM for reflected coefficient estimation and calculating speed and stability.

  18. Reproducing Electric Field Observations during Magnetic Storms by means of Rigorous 3-D Modelling and Distortion Matrix Co-estimation

    Science.gov (United States)

    Püthe, Christoph; Manoj, Chandrasekharan; Kuvshinov, Alexey

    2015-04-01

    Electric fields induced in the conducting Earth during magnetic storms drive currents in power transmission grids, telecommunication lines or buried pipelines. These geomagnetically induced currents (GIC) can cause severe service disruptions. The prediction of GIC is thus of great importance for public and industry. A key step in the prediction of the hazard to technological systems during magnetic storms is the calculation of the geoelectric field. To address this issue for mid-latitude regions, we developed a method that involves 3-D modelling of induction processes in a heterogeneous Earth and the construction of a model of the magnetospheric source. The latter is described by low-degree spherical harmonics; its temporal evolution is derived from observatory magnetic data. Time series of the electric field can be computed for every location on Earth's surface. The actual electric field however is known to be perturbed by galvanic effects, arising from very local near-surface heterogeneities or topography, which cannot be included in the conductivity model. Galvanic effects are commonly accounted for with a real-valued time-independent distortion matrix, which linearly relates measured and computed electric fields. Using data of various magnetic storms that occurred between 2000 and 2003, we estimated distortion matrices for observatory sites onshore and on the ocean bottom. Strong correlations between modellings and measurements validate our method. The distortion matrix estimates prove to be reliable, as they are accurately reproduced for different magnetic storms. We further show that 3-D modelling is crucial for a correct separation of galvanic and inductive effects and a precise prediction of electric field time series during magnetic storms. Since the required computational resources are negligible, our approach is suitable for a real-time prediction of GIC. For this purpose, a reliable forecast of the source field, e.g. based on data from satellites

  19. Field activity cost estimates for the first 3 years of the World Bank Loan Project for schistosomiasis control in China.

    Science.gov (United States)

    Guo, J; Booth, M; Jenkins, J; Wang, H; Tanner, M

    1998-12-01

    The World Bank Loan Project for schistosomiasis in China commenced field activities in 1992. In this paper, we describe disease control strategies for levels of different endemicity, and estimate unit costs and total expenditure of screening, treatment (cattle and humans) and snail control for 8 provinces where Schistosoma japonicum infection is endemic. Overall, we estimate that more than 21 million US dollars were spent on field activities during the first three years of the project. Mollusciciding (43% of the total expenditure) and screening (28% of the total) are estimated to have the most expensive field activities. However, despite the expense of screening, a simple model predicts that selective chemotherapy could have been cheaper than mass chemotherapy in areas where infection prevalence was higher than 15%, which was the threshold for mass chemotherapy intervention. It is concluded that considerable cost savings could be made in the future by narrowing the scope of snail control activities, redefining the threshold infection prevalence for mass chemotherapy, defining smaller administrative units, and developing rapid assessment tools.

  20. Estimation of Plasma Properties and Magnetic Field in a Prominence-like Structure as Observed by SDO/AIA

    CERN Document Server

    Dwivedi, Bhola N; Mohan, Anita

    2013-01-01

    We analyze a prominence-like cool plasma structure as observed by Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We perform the Differential Emission Measure (DEM) analysis using various filters of AIA, and also deduce the temperature and density structure in and around the observed flux-tube. In addition to deducing plasma parameters, we also find an evidence of multiple harmonics of fast magnetoacoustic kink waves in the observed prominence-like magnetic structure. Making use of estimated plasma parameters and observed wave parameters, under the baseline of MHD seismology, we deduce magnetic field in the flux-tube. The wave period ratio P1/P2 = 2.18 is also observed in the flux-tube, which carries the signature of magnetic field divergence where we estimate the tube expansion factor as 1.27. We discuss constraints in the estimation of plasma and magnetic field properties in such a structure in the current observational perspective, which may shed new light on the localized ...

  1. 3D Ground Penetrating Radar to Detect Tree Roots and Estimate Root Biomass in the Field

    Directory of Open Access Journals (Sweden)

    Shiping Zhu

    2014-06-01

    Full Text Available The objectives of this study were to detect coarse tree root and to estimate root biomass in the field by using an advanced 3D Ground Penetrating Radar (3D GPR system. This study obtained full-resolution 3D imaging results of tree root system using 500 MHz and 800 MHz bow-tie antennas, respectively. The measurement site included two larch trees, and one of them was excavated after GPR measurements. In this paper, a searching algorithm, based on the continuity of pixel intensity along the root in 3D space, is proposed, and two coarse roots whose diameters are more than 5 cm were detected and delineated correctly. Based on the detection results and the measured root biomass, a linear regression model is proposed to estimate the total root biomass in different depth ranges, and the total error was less than 10%. Additionally, based on the detected root samples, a new index named “magnitude width” is proposed to estimate the root diameter that has good correlation with root diameter compared with other common GPR indexes. This index also provides direct measurement of the root diameter with 13%–16% error, providing reasonable and practical root diameter estimation especially in the field.

  2. A simple temperature domain two-source model for estimating agricultural field surface energy fluxes from Landsat images

    Science.gov (United States)

    Yao, Yunjun; Liang, Shunlin; Yu, Jian; Chen, Jiquan; Liu, Shaomin; Lin, Yi; Fisher, Joshua B.; McVicar, Tim R.; Cheng, Jie; Jia, Kun; Zhang, Xiaotong; Xie, Xianhong; Jiang, Bo; Sun, Liang

    2017-05-01

    A simple and robust satellite-based method for estimating agricultural field to regional surface energy fluxes at a high spatial resolution is important for many applications. We developed a simple temperature domain two-source energy balance (TD-TSEB) model within a hybrid two-source model scheme by coupling "layer" and "patch" models to estimate surface heat fluxes from Landsat thematic mapper/Enhanced Thematic Mapper Plus (TM/ETM+) imagery. For estimating latent heat flux (LE) of full soil, we proposed a temperature domain residual of the energy balance equation based on a simplified framework of total aerodynamic resistances, which provides a key link between thermal satellite temperature and subsurface moisture status. Additionally, we used a modified Priestley-Taylor model for estimating LE of full vegetation. The proposed method was applied to TM/ETM+ imagery and was validated using the ground-measured data at five crop eddy-covariance tower sites in China. The results show that TD-TSEB yielded root-mean-square-error values between 24.9 (8.9) and 78.2 (21.4) W/m2 and squared correlation coefficient (R2) values between 0.60 (0.51) and 0.97 (0.90), for the estimated instantaneous (daily) surface net radiation, soil, latent, and sensible heat fluxes at all five sites. The TD-TSEB model shows good accuracy for partitioning LE into soil (LEsoil) and canopy (LEcanopy) components with an average bias of 11.1% for the estimated LEsoil/LE ratio at the Daman site. Importantly, the TD-TSEB model produced comparable accuracy but requires fewer forcing data (i.e., no wind speed and roughness length are needed) when compared with two other widely used surface energy balance models. Sensitivity analyses demonstrated that this accurate operational model provides an alternative method for mapping field surface heat fluxes with satisfactory performance.

  3. Insect-Inspired Self-Motion Estimation with Dense Flow Fields--An Adaptive Matched Filter Approach.

    Science.gov (United States)

    Strübbe, Simon; Stürzl, Wolfgang; Egelhaaf, Martin

    2015-01-01

    The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD) algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion.

  4. Insect-Inspired Self-Motion Estimation with Dense Flow Fields--An Adaptive Matched Filter Approach.

    Directory of Open Access Journals (Sweden)

    Simon Strübbe

    Full Text Available The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion.

  5. Estimating the Rate of Progressive Visual Field Damage in Those with Open-Angle Glaucoma, from Cross-Sectional Data

    Science.gov (United States)

    Broman, Aimee Teo; Quigley, Harry A.; West, Sheila K.; Katz, Joanne; Munoz, Beatriz; Bandeen-Roche, Karen; Tielsch, James M.; Friedman, David S.; Crowston, Jonathan; Taylor, Hugh R.; Varma, Rohit; Leske, M. Cristina; Bengtsson, Boel; Heijl, Anders; He, Mingguang; Foster, Paul J.

    2008-01-01

    Purpose To estimate the rate of visual field progression in open-angle glaucoma (OAG) subjects, by using data from population-based cross-sectional studies. Methods Subjects with OAG were identified in nine surveys of randomly sampled populations using standard criteria for glaucomatous optic neuropathy. Subjects were of European, African, Chinese, and Hispanic ethnicity. The measure of OAG damage was the mean deviation (MD) of an automated visual field test (Humphrey Field Analyzer; Carl Zeiss Meditec, Inc., Dublin, CA). The rate of progression was the mean of all subjects’ damage in the worse eye divided by an average time since onset. Time since onset was estimated from age-specific prevalence rates. Results A total of 1066 subjects with OAG contributed visual field data. The mean worsening in decibels per year was: European-derived, −1.12; Hispanic, −1.26; African-derived, −1.33; and Chinese −1.56 (difference among ethnicities, P = 0.16). The mean duration of disease was lowest among Chinese persons at 10.5 years (95% CI: 8.8–12.6) and was highest in African-derived subjects at 15.4 years (95% CI: 14.6–15.9). The progression rate was not consistently related to age or gender. By combining disease duration and progression rate, the model predicted that 15% or fewer of the worse eyes would reach the end of the field damage scale in the patient’s lifetime. Conclusions The estimates of typical worsening per year in the worse eye among subjects with OAG suggested slightly more rapid progression than in some clinic-based studies. The rate did not differ significantly by ethnicity or gender, but was worse in those with known, treated OAG and in pseudophakic subjects. PMID:18172076

  6. Adaptive Algorithm for Estimation of Two-Dimensional Autoregressive Fields from Noisy Observations

    Directory of Open Access Journals (Sweden)

    Alimorad Mahmoudi

    2014-01-01

    Full Text Available This paper deals with the problem of two-dimensional autoregressive (AR estimation from noisy observations. The Yule-Walker equations are solved using adaptive steepest descent (SD algorithm. Performance comparisons are made with other existing methods to demonstrate merits of the proposed method.

  7. Comparing alternative tree canopy cover estimates derived from digital aerial photography and field-based assessments

    Science.gov (United States)

    Tracey S. Frescino; Gretchen G. Moisen

    2012-01-01

    A spatially-explicit representation of live tree canopy cover, such as the National Land Cover Dataset (NLCD) percent tree canopy cover layer, is a valuable tool for many applications, such as defining forest land, delineating wildlife habitat, estimating carbon, and modeling fire risk and behavior. These layers are generated by predictive models wherein their accuracy...

  8. A Simplified Quaternion-Based Algorithm for Orientation Estimation From Earth Gravity and Magnetic Field Measurements

    Science.gov (United States)

    2008-03-01

    Calusdian for his technical support during the course of this project, A. Kavousanos- Kavousanakis for implementing the QUEST algorithm, and C. Aparicio for...Location Navigation Symp., San Diego, CA, Mar. 2000, pp. 185–192. [10] G. Wahba, “Problem 65-1: A least squares estimate of satellite attitude,” SIAM Rev

  9. Genetic and phenotypic parameters estimated from Nebraska specific-pathogen-free swine field records.

    Science.gov (United States)

    David, P J; Johnson, R K; Socha, T E

    1983-11-01

    Records collected during 1971 through 1979 from 101,606 hogs raised in 18 Nebraska Specific Pathogen Free herds were analyzed. Traits considered were backfat at 100 kg (BF), weight at 140 d of age (WT) and, in some analyses, number of live pigs/litter at birth (NBA). The phenotypic correlation of BF and WT, averaged across herds, was -.07. The correlations between BF and NBA and between WT and NBA were .04 and -.05, respectively. Average phenotypic standard deviations for BF, WT and NBA were 2.6 mm, 8.8 kg and 2.0 pigs. Estimates of the heritability of BF and WT were lower than most estimates reported from university research herds. Within breed, herd and sex estimates of heritability ranged from -.22 and .51 (unweighted mean = .16 +/- .025) for BF and ranged from -.28 to .49 (mean = .16 +/- .016) for WT. Estimates of the genetic correlation between BF and WT were extremely variable (mean = -.62 +/- 14.3, range = -9.42 to 1.30) among breed-herd-sex subclasses.

  10. Estimating Ambiguity Preferences and Perceptions in Multiple Prior Models: Evidence from the Field

    NARCIS (Netherlands)

    S.G. Dimmock (Stephen); R.R.P. Kouwenberg (Roy); O.S. Mitchell (Olivia); K. Peijnenburg (Kim)

    2015-01-01

    markdownabstractWe develop a tractable method to estimate multiple prior models of decision-making under ambiguity. In a representative sample of the U.S. population, we measure ambiguity attitudes in the gain and loss domains. We find that ambiguity aversion is common for uncertain events of modera

  11. Energy shift estimation of demand response activation on domestic refrigerators – A field test study

    DEFF Research Database (Denmark)

    Lakshmanan, Venkatachalam; Gudmand-Høyer, Kristian; Marinelli, Mattia;

    2014-01-01

    This paper presents a method to estimate the amount of energy that can be shifted during demand response (DR) activation on domestic refrigerator. Though there are many methods for DR activation like load reduction, load shifting and onsite generation, the method under study is load shifting. Ele...

  12. Feasibility analysis of using inverse modeling for estimating field-scale evapotranspiration in maize and soybean fields from soil water content monitoring networks

    Science.gov (United States)

    Foolad, Foad; Franz, Trenton E.; Wang, Tiejun; Gibson, Justin; Kilic, Ayse; Allen, Richard G.; Suyker, Andrew

    2017-03-01

    In this study, the feasibility of using inverse vadose zone modeling for estimating field-scale actual evapotranspiration (ETa) was explored at a long-term agricultural monitoring site in eastern Nebraska. Data from both point-scale soil water content (SWC) sensors and the area-average technique of cosmic-ray neutron probes were evaluated against independent ETa estimates from a co-located eddy covariance tower. While this methodology has been successfully used for estimates of groundwater recharge, it was essential to assess the performance of other components of the water balance such as ETa. In light of recent evaluations of land surface models (LSMs), independent estimates of hydrologic state variables and fluxes are critically needed benchmarks. The results here indicate reasonable estimates of daily and annual ETa from the point sensors, but with highly varied soil hydraulic function parameterizations due to local soil texture variability. The results of multiple soil hydraulic parameterizations leading to equally good ETa estimates is consistent with the hydrological principle of equifinality. While this study focused on one particular site, the framework can be easily applied to other SWC monitoring networks across the globe. The value-added products of groundwater recharge and ETa flux from the SWC monitoring networks will provide additional and more robust benchmarks for the validation of LSM that continues to improve their forecast skill. In addition, the value-added products of groundwater recharge and ETa often have more direct impacts on societal decision-making than SWC alone. Water flux impacts human decision-making from policies on the long-term management of groundwater resources (recharge), to yield forecasts (ETa), and to optimal irrigation scheduling (ETa). Illustrating the societal benefits of SWC monitoring is critical to insure the continued operation and expansion of these public datasets.

  13. Estimates of deep percolation beneath native vegetation, irrigated fields, and the Amargosa-River Channel, Amargosa Desert, Nye County, Nevada

    Science.gov (United States)

    Stonestrom, David A.; Prudic, David E.; Laczniak, Randell J.; Akstin, Katherine C.; Boyd, Robert A.; Henkelman, Katherine K.

    2003-01-01

    The presence and approximate rates of deep percolation beneath areas of native vegetation, irrigated fields, and the Amargosa-River channel in the Amargosa Desert of southern Nevada were evaluated using the chloride mass-balance method and inferred downward velocities of chloride and nitrate peaks. Estimates of deep-percolation rates in the Amargosa Desert are needed for the analysis of regional ground-water flow and transport. An understanding of regional flow patterns is important because ground water originating on the Nevada Test Site may pass through the area before discharging from springs at lower elevations in the Amargosa Desert and in Death Valley. Nine boreholes 10 to 16 meters deep were cored nearly continuously using a hollow-stem auger designed for gravelly sediments. Two boreholes were drilled in each of three irrigated fields in the Amargosa-Farms area, two in the Amargosa-River channel, and one in an undisturbed area of native vegetation. Data from previously cored boreholes beneath undisturbed, native vegetation were compared with the new data to further assess deep percolation under current climatic conditions and provide information on spatial variability. The profiles beneath native vegetation were characterized by large amounts of accumulated chloride just below the root zone with almost no further accumulation at greater depths. This pattern is typical of profiles beneath interfluvial areas in arid alluvial basins of the southwestern United States, where salts have been accumulating since the end of the Pleistocene. The profiles beneath irrigated fields and the Amargosa-River channel contained more than twice the volume of water compared to profiles beneath native vegetation, consistent with active deep percolation beneath these sites. Chloride profiles beneath two older fields (cultivated since the 1960?s) as well as the upstream Amargosa-River site were indicative of long-term, quasi-steady deep percolation. Chloride profiles beneath the

  14. Selecting and applying cesium-137 conversion models to estimate soil erosion rates in cultivated fields.

    Science.gov (United States)

    Li, Sheng; Lobb, David A; Tiessen, Kevin H D; McConkey, Brian G

    2010-01-01

    The fallout radionuclide cesium-137 ((137)Cs) has been successfully used in soil erosion studies worldwide. However, discrepancies often exist between the erosion rates estimated using various conversion models. As a result, there is often confusion in the use of the various models and in the interpretation of the data. Therefore, the objective of this study was to test the structural and parametrical uncertainties associated with four conversion models typically used in cultivated agricultural landscapes. For the structural uncertainties, the Soil Constituent Redistribution by Erosion Model (SCREM) was developed and used to simulate the redistribution of fallout (137)Cs due to tillage and water erosion along a simple two-dimensional (horizontal and vertical) transect. The SCREM-predicted (137)Cs inventories were then imported into the conversion models to estimate the erosion rates. The structural uncertainties of the conversion models were assessed based on the comparisons between the conversion-model-estimated erosion rates and the erosion rates determined or used in the SCREM. For the parametrical uncertainties, test runs were conducted by varying the values of the parameters used in the model, and the parametrical uncertainties were assessed based on the responsive changes of the estimated erosion rates. Our results suggest that: (i) the performance/accuracy of the conversion models was largely dependent on the relative contributions of water vs. tillage erosion; and (ii) the estimated erosion rates were highly sensitive to the input values of the reference (137)Cs level, particle size correction factors and tillage depth. Guidelines were proposed to aid researchers in selecting and applying the conversion models under various situations common to agricultural landscapes.

  15. John cunningham (JC) virus genotypes in kidney transplant recipients, rheumatoid arthritis patients and healthy individuals in Isfahan, Iran.

    Science.gov (United States)

    Atyabi, Sayyedeh Rahmaneh; Bouzari, Majid; Kardi, Mohammad Taghi

    2017-02-01

    In healthy individuals John Cunningham virus is latent without any clinical signs, but in the cases of the use of immunosuppressive drugs in graft recipients, autoimmune diseases and also increasing of age, that the immune system is suppressed it may cause disease in reactivation. Progressive multifocal leukoencephalopathy (PML) is the well-known disease caused by the virus. It has also been associated with nephropathy and tumorogensis. At present, based on vp1 capsid gene 7 genotypes have been detected. Genetic variations of JC virus in different geographical areas and the presence of different subtypes is a useful tool for reconstructing of the genetic information of JC virus and understanding of its evolution. The aim of this study was to investigate different genotypes of the JC virus in the urine of 100 kidney transplant recipients, 43 rheumatoid arthritis patients, and 100 healthy individuals as control group in Isfahan. DNA was extracted by phenol-chloroform method and subjected to a nested PCR using specific primer for vp1 capsid gene designed by Oligo 7 software. Fisher's exact test was used for statistical analyses. Using MEGA 6 software the sequences were aligned using Clustal W tool and phylogenetic trees were constructed by neighbor joining method. Thirty-one positive samples were sequenced. Genotypes 1, 3, and 4 of the virus were detected for the first time in Iran. For the first time genotype 3 was reported as the dominant genotype in Iran. For the first time in the world, genotype 4 was detected in rheumatoid arthritis patients. J. Med. Virol. 89:337-344, 2017. © 2016 Wiley Periodicals, Inc.

  16. Application of Multi-port Bidirectional DC-DC Converter to Fuel Cell Vehicle Driving in JC08 Mode

    Science.gov (United States)

    Tanaka, Katsunori; Katayama, Noboru; Kogoshi, Sumio; Fukada, Takafumi; Ogawa, Makoto

    A fuel cell-EDLC hybrid power system with a multi-port bidirectional DC-DC converter has been recently proposed for extending lifetime of a fuel cell due to smoothing the output current of the fuel cell. This paper studies the performance of the hybrid power system when a fuel cell vehicle drives in the JC08 mode using a simulation model. The simulation results indicate that even if the load current fluctuates, the output current of the fuel cell could be maintained at almost constant values with an assist from the EDLC although small spikes are observed.

  17. A Numerical Estimation of a RFID Reader Field and SAR inside a Blood Bag at UHF

    Directory of Open Access Journals (Sweden)

    Alessandro Fanti

    2016-11-01

    Full Text Available In this paper, the effects of UHF electromagnetic fields produced by a RFID reader on a blood bag are evaluated numerically in several configurations. The results of the simulation, field level and distribution, specific absorption rate (SAR, and heating time show that an exposure to a typical reader field leads to a temperature increase smaller than 0.1 C and to a SAR smaller than 1 W/kg. As a consequence, no adverse biological effects occur during a typical UHF RFID reading cycle on a blood bag. Therefore, the blood contained in a bag traced using UHF-RFID is as safe as those traced using barcodes. The proposed analysis supports the use of UHF RFID in the blood transfusion supply chain.

  18. Method for estimating the stress field from seismic moment tensor data based on the flow rule in plasticity theory

    Science.gov (United States)

    Matsumoto, S.

    2016-09-01

    The stress field is a key factor controlling earthquake occurrence and crustal evolution. In this study, we propose an approach for determining the stress field in a region using seismic moment tensors, based on the classical equation in plasticity theory. Seismic activity is a phenomenon that relaxes crustal stress and creates plastic strain in a medium because of faulting, which suggests that the medium could behave as a plastic body. Using the constitutive relation in plastic theory, the increment of the plastic strain tensor is proportional to the deviatoric stress tensor. Simple mathematical manipulation enables the development of an inversion method for estimating the stress field in a region. The method is tested on shallow earthquakes occurring on Kyushu Island, Japan.

  19. Optimization of Transverse Oscillating Fields for Vector Velocity Estimation with Convex Arrays

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2013-01-01

    ;1. lx is maintained between 1.47 and 1.70 mm from 25 mm to 70 mm and is increased to 2.8 mm at a depth of 100 mm. Parabolic profiles are estimated using 16 missions. The optimization gives a reduction in std. from 8.5% to 5.9% with a reduction in bias from 35% to 1.02% at 90 degrees (transverse flow...

  20. Estimation of the neutron field around the HERA proton beam dump

    Science.gov (United States)

    Möhring, H.-J.; Noack, K.; Zazula, J. M.

    1991-01-01

    In this article we present estimates for the neutron fluences above 0.1 MeV to be expected around the proton beam dump of the HERA machine at DESY at 1000 GeV incident energy. The most important details of the absorber and tunnel layout are approximately modeled using the Cartesian and combinatorial geometry packages. In our method a volume neutron source for MORSE Monte Carlo neutron transport calculations has been determined from star densities obtained from the FLUKA Monte Carlo hadronic shower code, combined with estimates of low-energy neutron yields based on results of intranuclear cascade calculations and of the statistical model of evaporation. The calculated neutron fluences are in reasonable agreement with results obtained by the FLUNEV version of the FLUKA code, currently developed at DESY, as well as with estimates based on empirically determined conversion factors between star density and neutron fluence. Additionally, we present neutron spectra and the corresponding dose equivalents as well as the absorbed doses in beam dump materials obtained from the FLUNEV code.

  1. Entry Debris Field Estimation Methods and Application to Compton Gamma Ray Observatory Disposal

    Science.gov (United States)

    Mrozinski, Richard B.

    2001-01-01

    For public safety reasons, the Compton Gamma Ray Observatory (CGRO) was intentionally deorbited on June 4, 2000. This deorbit was NASA's first intentional controlled deorbit of a satellite, and more will come including the eventual deorbit of the International Space Station. To maximize public safety, satellite deorbit planning requires conservative estimates of the debris footprint size and location. These estimates are needed to properly design a deorbit sequence that places the debris footprint over unpopulated areas, including protection for deorbit contingencies. This paper details a method for estimating the length (range), width (crossrange), and location of entry and breakup debris footprints. This method utilizes a three degree-of-freedom Monte Carlo simulation incorporating uncertainties in all aspects of the problem, including vehicle and environment uncertainties. The method incorporates a range of debris characteristics based on historical data in addition to any vehicle-specific debris catalog information. This paper describes the method in detail, and presents results of its application as used in planning the deorbit of the CGRO.

  2. Integrating biology, field logistics, and simulations to optimize parameter estimation for imperiled species

    Science.gov (United States)

    Lanier, Wendy E.; Bailey, Larissa L.; Muths, Erin L.

    2016-01-01

    Conservation of imperiled species often requires knowledge of vital rates and population dynamics. However, these can be difficult to estimate for rare species and small populations. This problem is further exacerbated when individuals are not available for detection during some surveys due to limited access, delaying surveys and creating mismatches between the breeding behavior and survey timing. Here we use simulations to explore the impacts of this issue using four hypothetical boreal toad (Anaxyrus boreas boreas) populations, representing combinations of logistical access (accessible, inaccessible) and breeding behavior (synchronous, asynchronous). We examine the bias and precision of survival and breeding probability estimates generated by survey designs that differ in effort and timing for these populations. Our findings indicate that the logistical access of a site and mismatch between the breeding behavior and survey design can greatly limit the ability to yield accurate and precise estimates of survival and breeding probabilities. Simulations similar to what we have performed can help researchers determine an optimal survey design(s) for their system before initiating sampling efforts.

  3. Estimating the magnitude of prediction uncertainties for field-scale P loss models

    Science.gov (United States)

    Models are often used to predict phosphorus (P) loss from agricultural fields. While it is commonly recognized that model predictions are inherently uncertain, few studies have addressed prediction uncertainties using P loss models. In this study, an uncertainty analysis for the Annual P Loss Estima...

  4. Bayesian Estimates of the Large-Scale Velocity Field in Real Space and Redshift Space

    OpenAIRE

    Stebbins, Albert

    1993-01-01

    Methods for inferring the velocity field from the peculiar velocity data are described and applied to old and newer data. Inhomogeneous Malmquist bias and ways to avoid it are discussed and utilized. We infer that these biases are probably important in interpreting the data.

  5. Face Fields and Microperimetry for Estimating the Location of Fixation in Eyes with Macular Disease

    Science.gov (United States)

    Sunness, Janet S.

    2008-01-01

    Face field evaluation provides insights into the presence and location of the preferred retinal locus, as validated by comparisons with findings from microperimetry. This technique requires no special equipment and can be used in a clinic or at a person's home by clinicians and low vision rehabilitation specialists. (Contains 2 figures and 2…

  6. Estimation of the biomass of arbuscular mycorrhizal fungi in a linseed field

    DEFF Research Database (Denmark)

    Olsson, P.A.; Thingstrup, I.; Jakobsen, I.

    1999-01-01

    Linseed was grown in field plots included in a long-term P fertilisation experiment (0, 15 or 30 kg P ha(-1) yr(-1) for 20 yr). Two months before sowing, half of each plot man applied with dazomet to prevent the formation of arbuscular mycorrhiza (AM). The biomass of different groups of micro...

  7. Gravity field estimation from future space missions - TOPEX/POSEIDON, Gravity Probe B, and ARISTOTELES

    Science.gov (United States)

    Pavlis, Erricos C.

    Accurate knowledge of the gravity field is a firm requirement in any study of Planet Earth. Space techniques have so far demonstrated their superiority in the global mapping of the gravity field based on ground tracking and altimeter data mostly. Numerical and analytical simulation studies of the upcoming geophysically relevant missions that will most likely carry GPS receivers, indicate significant improvements in the accuracy as well as the resolution of the gravity field. TOPEX will improve by some two orders of magnitude the long wavelength part (to degree about 20), while GP-B will contribute in the long as well as medium wavelength part of the spectrum (up to degree about 60). The gradiometer measurements on ARISTOTELES will contribute in the medium and short wavelength regions (from degree 30 up); GPS tracking of the spacecraft though will provide additional information for the long wavelength gravity and will help resolve it to accuracies comparable to those obtained from GP-B. With the mean rms coefficient error per degree kept below 10 exp -10, geophysical signals such as the post-glacial rebound, tidal variations, and secular and periodic variations of the zonal field rise above the noise level and become readily observable processes.

  8. Estimating GHG Emissions from the Manufacturing of Field-Applied Biochar Pellets

    Science.gov (United States)

    Richard D. Bergman; Hanwen Zhang; Karl Englund; Keith Windell; Hongmei Gu

    2016-01-01

    Biochar application to forest soils can provide direct and indirect benefits, including carbon sequestration. Biochar, the result of thermochemical conversion of biomass, can have positive environmental climate benefits and can be more stable when field-applied to forest soils than wood itself. Categorizing greenhouse gas (GHG) emissions and carbon sequestration...

  9. A story about estimation of a random field of boulders from incomplete seismic measurements

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2005-01-01

    deposits along the tunnel line. By use of this important distribution information and of the observed homogeneity of the seismic point source field together with the physical properties of diffraction it became possible to make the wanted prediction. During the excavation the found boulders were counted...

  10. Field-scale water flow and solute transport : Swap model concepts, parameter estimation and case studies

    NARCIS (Netherlands)

    Dam, van J.C.

    2000-01-01

    Water flow and solute transport in top soils are important elements in many environmental studies. The agro- and ecohydrological model SWAP (Soil-Water-Plant-Atmosphere) has been developed to simulate simultaneously water flow, solute transport, heat flow and crop growth at field scale level. The ma

  11. Field measurements give biased estimates of functional response parameters, but help explain foraging distributions

    NARCIS (Netherlands)

    Duijns, S.; Knot, I.E.; Piersma, T.; van Gils, J.A.

    2015-01-01

    1.Mechanistic insights and predictive understanding of the spatial distributions of foragers are typically derived by fitting either field measurements on intake rates and food abundance, or observations from controlled experiments, to functional response models. It has remained unclear, however, wh

  12. Analytical method of estimating a three-dimensional external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Tselikovskii, E.F.

    1977-07-01

    A primary boundary problem of magnetostatics is solved on the basis of the theory of potential. Boundary conditions are found by the conformal transfer of those conditions from the bodies for which they are known to the surface of a body whose field is computed. 5 references, 3 figures.

  13. Object-Based Flood Mapping and Affected Rice Field Estimation with Landsat 8 OLI and MODIS Data

    Directory of Open Access Journals (Sweden)

    Phuong D. Dao

    2015-04-01

    Full Text Available Cambodia is one of the most flood-prone countries in Southeast Asia. It is geographically situated in the downstream region of the Mekong River with a lowland floodplain in the middle, surrounded by plateaus and high mountains. It usually experiences devastating floods induced by an overwhelming concentration of rainfall water over the Tonle Sap Lake’s and Mekong River’s banks during monsoon seasons. Flood damage assessment in the rice ecosystem plays an important role in this region as local residents rely heavily on agricultural production. This study introduced an object-based approach to flood mapping and affected rice field estimation in central Cambodia. In this approach, image segmentation processing was conducted with optimal scale parameter estimation based on the variation of objects’ local variances. The inundated area was identified by using Landsat 8 images with an overall accuracy of higher than 95% compared to those derived from finer spatial resolution images. Moderate Resolution Imaging Spectroradiometer (MODIS vegetation index products were utilized to identify the paddy rice field based on seasonal inter-variation between vegetation and water index during the transplanting stage. The rice classification result was well correlated with the statistical data at a commune level (R2 = 0.675. The flood mapping and affected rice estimation results are useful to provide local governments with valuable information for flooding mitigation and post-flooding compensation and restoration.

  14. Regularized Positive-Definite Fourth Order Tensor Field Estimation from DW-MRI★

    Science.gov (United States)

    Barmpoutis, Angelos; Vemuri, Baba C.; Howland, Dena; Forder, John R.

    2009-01-01

    In Diffusion Weighted Magnetic Resonance Image (DW-MRI) processing, a 2nd order tensor has been commonly used to approximate the diffusivity function at each lattice point of the DW-MRI data. From this tensor approximation, one can compute useful scalar quantities (e.g. anisotropy, mean diffusivity) which have been clinically used for monitoring encephalopathy, sclerosis, ischemia and other brain disorders. It is now well known that this 2nd-order tensor approximation fails to capture complex local tissue structures, e.g. crossing fibers, and as a result, the scalar quantities derived from these tensors are grossly inaccurate at such locations. In this paper we employ a 4th order symmetric positive-definite (SPD) tensor approximation to represent the diffusivity function and present a novel technique to estimate these tensors from the DW-MRI data guaranteeing the SPD property. Several articles have been reported in literature on higher order tensor approximations of the diffusivity function but none of them guarantee the positivity of the estimates, which is a fundamental constraint since negative values of the diffusivity are not meaningful. In this paper we represent the 4th-order tensors as ternary quartics and then apply Hilbert’s theorem on ternary quartics along with the Iwasawa parametrization to guarantee an SPD 4th-order tensor approximation from the DW-MRI data. The performance of this model is depicted on synthetic data as well as real DW-MRIs from a set of excised control and injured rat spinal cords, showing accurate estimation of scalar quantities such as generalized anisotropy and trace as well as fiber orientations. PMID:19063978

  15. Regularized positive-definite fourth order tensor field estimation from DW-MRI.

    Science.gov (United States)

    Barmpoutis, Angelos; Hwang, Min Sig; Howland, Dena; Forder, John R; Vemuri, Baba C

    2009-03-01

    In Diffusion Weighted Magnetic Resonance Image (DW-MRI) processing, a 2nd order tensor has been commonly used to approximate the diffusivity function at each lattice point of the DW-MRI data. From this tensor approximation, one can compute useful scalar quantities (e.g. anisotropy, mean diffusivity) which have been clinically used for monitoring encephalopathy, sclerosis, ischemia and other brain disorders. It is now well known that this 2nd-order tensor approximation fails to capture complex local tissue structures, e.g. crossing fibers, and as a result, the scalar quantities derived from these tensors are grossly inaccurate at such locations. In this paper we employ a 4th order symmetric positive-definite (SPD) tensor approximation to represent the diffusivity function and present a novel technique to estimate these tensors from the DW-MRI data guaranteeing the SPD property. Several articles have been reported in literature on higher order tensor approximations of the diffusivity function but none of them guarantee the positivity of the estimates, which is a fundamental constraint since negative values of the diffusivity are not meaningful. In this paper we represent the 4th-order tensors as ternary quartics and then apply Hilbert's theorem on ternary quartics along with the Iwasawa parametrization to guarantee an SPD 4th-order tensor approximation from the DW-MRI data. The performance of this model is depicted on synthetic data as well as real DW-MRIs from a set of excised control and injured rat spinal cords, showing accurate estimation of scalar quantities such as generalized anisotropy and trace as well as fiber orientations.

  16. Application of the Monte Carlo Method for the Estimation of Uncertainty in Radiofrequency Field Spot Measurements

    Science.gov (United States)

    Iakovidis, S.; Apostolidis, C.; Samaras, T.

    2015-04-01

    The objective of the present work is the application of the Monte Carlo method (GUMS1) for evaluating uncertainty in electromagnetic field measurements and the comparison of the results with the ones obtained using the 'standard' method (GUM). In particular, the two methods are applied in order to evaluate the field measurement uncertainty using a frequency selective radiation meter and the Total Exposure Quotient (TEQ) uncertainty. Comparative results are presented in order to highlight cases where GUMS1 results deviate significantly from the ones obtained using GUM, such as the presence of a non-linear mathematical model connecting the inputs with the output quantity (case of the TEQ model) or the presence of a dominant nonnormal distribution of an input quantity (case of U-shaped mismatch uncertainty). The deviation of the results obtained from the two methods can even lead to different decisions regarding the conformance with the exposure reference levels.

  17. A method for estimating tokamak poloidal field coil currents which incorporates engineering constraints

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, W.A.

    1990-05-01

    This thesis describes the development of a design tool for the poloidal field magnet system of a tokamak. Specifically, an existing program for determining the poloidal field coil currents has been modified to: support the general case of asymmetric equilibria and coil sets, determine the coil currents subject to constraints on the maximum values of those currents, and determine the coil currents subject to limits on the forces those coils may carry. The equations representing the current limits and coil force limits are derived and an algorithm based on Newton's method is developed to determine a set of coil currents which satisfies those limits. The resulting program allows the designer to quickly determine whether or not a given coil set is capable of supporting a given equilibrium. 25 refs.

  18. Using aircraft as wind sensors for estimating accurate wind fields for air traffic management applications

    OpenAIRE

    Hernando Guadaño, Laura; Arnaldo Valdes, Rosa Maria; Saez Nieto, Francisco Javier

    2014-01-01

    A study which examines the use of aircraft as wind sensors in a terminal area for real-time wind estimation in order to improve aircraft trajectory prediction is presented in this paper. We describe not only different sources in the aircraft systems that provide the variables needed to derivate the wind velocity but the capabilities which allow us to present this information for ATM Applications. Based on wind speed samples from aircraft landing at Madrid-Barajas airport, a real-time wind fie...

  19. Continuos incremental field test to estimate velocity and maximal oxygen consumption in non-expert runners

    OpenAIRE

    José A. Bragada; Moreno, R; Barbosa, Tiago M

    2009-01-01

    Parameters such as a maximal oxygen uptake (VO2max) and velocity at which VO2max occurs (VelVO2max) are often used to training control purposes to enhance runner’s performance. This study had two purposes: (i) determine the relationship between VelVO2max obtained in continuous incremental filed test (CIFT) and VelVO2max determined on a treadmill in a laboratory; and (II) verify if it is possible to estimate the VO2max based on CIFT velocity

  20. [Non-thermal electromagnetic fields and estimation of the convulsive syndrome probable development].

    Science.gov (United States)

    Grigor'ev, Iu G; Sidorenko, A V

    2010-01-01

    There are cases of development of a convulsive syndrome at influence of electromagnetic field (EMF) in physiotherapy practice, and in conditions of a professional work. There is a point of view that EMF can render medical effect at treatment of a epilepsy syndrome. Some publications specify on develop of epilepsy convulsions in experiment at EMF of various frequencies exposure. Four conditions which can promote development of convulsions at EMF exposure are considered.

  1. Dust concentrations and respiratory risks in coalminers: key risk estimates from the British Pneumoconiosis Field Research

    OpenAIRE

    Soutar, C; Hurley, j; Miller, B.; Cowie, H; Buchanan, D.

    2004-01-01

    To help inform the setting of dust control standards in coalmines, this brief review summarises the most recent and reliable exposure-response relations, for damaging respiratory effects, derived from the Pneumoconiosis Field Research (PFR). Collecting data over 38 years in the British coal industry, this was a programme of prospective research on the respiratory health of coal miners, characterised by regular health surveys and detailed measurements of dust and silica concentrations in the w...

  2. Regional estimation of geomagnetically induced currents based on the local magnetic or electric field

    Directory of Open Access Journals (Sweden)

    Viljanen Ari

    2015-01-01

    Full Text Available Previous studies have demonstrated a close relationship between the time derivative of the horizontal geomagnetic field vector (dH/dt and geomagnetically induced currents (GIC at a nearby location in a power grid. Similarly, a high correlation exists between GIC and the local horizontal geoelectric field (E, typically modelled from a measured magnetic field. Considering GIC forecasting, it is not feasible to assume that detailed prediction of time series will be possible. Instead, other measures summarising the activity level over a given period are preferable. In this paper, we consider the 30-min maximum of dH/dt or E as a local activity indicator (|dH/dt|30 or |E|30. Concerning GIC, we use the sum of currents through the neutral leads at substations and apply its 30-min maximum as a regional activity measure (GIC30. We show that |dH/dt|30 at a single point yields a proxy for GIC activity in a larger region. A practical consequence is that if |dH/dt|30 can be predicted at some point then it is also possible to assess the expected GIC level in the surrounding area. As is also demonstrated, |E|30 and GIC30 depend linearly on |dH/dt|30, so there is no saturation with increasing geomagnetic activity contrary to often used activity indices.

  3. Estimating field-scale soil water dynamics at a heterogeneous site using multi-channel GPR

    Directory of Open Access Journals (Sweden)

    X. Pan

    2012-11-01

    Full Text Available We explore the feasibility to quantify the field-scale soil water dynamics through time series of GPR (ground-penetrating radar measurements, which bridge the gap between point measurements and field measurements. Working on a 40 m × 50 m area in a heterogeneous agricultural field, we obtain a time series of radargrams after a heavy rainfall event. The data are analysed to simultaneously yield (i a three-dimensional representation of the subsurface architecture and (ii the total soil water volume between the surface and a reflection boundary associated with the presence of paleo sand dunes or clay inclusions in a rather uniform sand matrix. We assess the precision and the accuracy of these quantities and conclude that the method is sensitive enough to capture the spatial structure of the changing soil water content in a three-dimensional heterogeneous soil during a short-duration infiltration event. While the sensitivity of the method needs to be improved, it already produced useful information to understand the observed patterns in crop height and it yielded insight into the dynamics of soil water content at this site including the effect of evaporation.

  4. Automatic NMO Correction and Full Common Depth Point NMO Velocity Field Estimation in Anisotropic Media

    Science.gov (United States)

    Sedek, Mohamed; Gross, Lutz; Tyson, Stephen

    2017-01-01

    We present a new computational method of automatic normal moveout (NMO) correction that not only accurately flattens and corrects the far offset data, but simultaneously provides NMO velocity (v_nmo) for each individual seismic trace. The method is based on a predefined number of NMO velocity sweeps using linear vertical interpolation of different NMO velocities at each seismic trace. At each sweep, we measure the semblance between the zero offset trace (pilot trace) and the next seismic trace using a trace-by-trace rather than sample-by-sample based semblance measure; then after all the sweeps are done, the one with the maximum semblance value is chosen, which is assumed to be the most suitable NMO velocity trace that accurately flattens seismic reflection events. Other traces follow the same process, and a final velocity field is then extracted. Isotropic, anisotropic and lateral heterogenous synthetic geological models were built to test the method. A range of synthetic background noise, ranging from 10 to 30 %, was applied to the models. In addition, the method was tested on Hess's VTI (vertical transverse isotropy) model. Furthermore, we tested our method on a real pre-stack seismic CDP gathered from a gas field in Alaska. The results from the presented examples show an excellent NMO correction and extracted a reasonably accurate NMO velocity field.

  5. A GIS-based Upscaling Estimation of Nutrient Runoff Losses from Rice Paddy Fields to a Regional Level.

    Science.gov (United States)

    Sun, Xiaoxiao; Liang, Xinqiang; Zhang, Feng; Fu, Chaodong

    2016-11-01

    Nutrient runoff losses from cropping fields can lead to nonpoint source pollution; however, the level of nutrient export is difficult to evaluate, particularly at the regional scale. This study aimed to establish a novel yet simple approach for estimating total nitrogen (TN) and total phosphorus (TP) runoff losses from regional paddy fields. In this approach, temporal changes of nutrient concentrations in floodwater were coupled with runoff-processing functions in rice ( L.) fields to calculate nutrient runoff losses for three site-specific field experiments. Validation experiments verified the accuracy of this method. The geographic information system technique was used to upscale and visualize the TN and TP runoff losses from field to regional scales. The results indicated that nutrient runoff losses had significant spatio-temporal variation characteristics during rice seasons, which were positively related to fertilizer rate and precipitation. The average runoff losses over five study seasons were 20.21 kg N ha for TN and 0.76 kg P ha for TP. Scenario analysis showed that TN and TP losses dropped by 7.64 and 3.0%, respectively, for each 10% reduction of fertilizer input. For alternate wetting and drying water management, the corresponding reduction ratio was 24.7 and 14.0% respectively. Our results suggest that, although both water and fertilizer management can mitigate nutrient runoff losses, the former is significantly more effective. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. L^p and Schauder estimates for nonvariational operators structured on H\\"ormander vector fields with drift

    CERN Document Server

    Bramanti, Marco

    2011-01-01

    We consider linear second order nonvariational partial differential operators of the kind a_{ij}X_{i}X_{j}+X_{0}, on a bounded domain of R^{n}, where the X_{i}'s (i=0,1,2,...,q, n>q+1) are real smooth vector fields satisfying H\\"ormander's condition and a_{ij} (i,j=1,2,...,q) are real valued, bounded measurable functions, such that the matrix {a_{ij}} is symmetric and uniformly positive. We prove that if the coefficients a_{ij} are H\\"older continuous with respect to the distance induced by the vector fields, then local Schauder estimates on X_{i}X_{j}u, X_{0}u hold; if the coefficients belong to the space VMO with respect to the distance induced by the vector fields, then local L^{p} estimates on X_{i}_{j}u, X_{0}u hold. The main novelty of the result is the presence of the drift term X_{0}, so that our class of operators covers, for instance, Kolmogorov-Fokker-Planck operators.

  7. Effects of Y211 phase contents on the critical current density Jc and microstructural analysis in YBCO bulk superconductors

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    YBCO bulk superconductors were prepared by the solid state reaction and top-seed-melt-textured growth (TSMTG) process. By using the AC susceptibility measurement, the critical transition temperature Tc of samples is 91.5 K for the highest value, and the transition width ?Tc is less than 1 K. The highest magnetization critical current densities Jc achieved 106 A/cm2 under 5 T at 10 K and 1.35?104 A/cm2 under 2 T at 70 K (H//c), respectively. The results combining the SEM observation indicate that doping of Y211 particles is more effective in improving the growth quality of melt-textured YBCO superconductor and in reducing the micro-cracks of specimens. Doping of Y2O3 powder forms the rod-shaped Y211 particles, but doping of Y211 particles directly to matrix materials forms the spherical Y211 particles mainly. Combining the microstructures with Jc measurements shows that the interfaces are most important on flux bundle pinning, in which the gradient of free energy is larger than that of other place between the Y211 particles and the Y123 matrix materials.

  8. Accounting for Non-Represented Heterogeneity in Soil Water Flow by Estimating Miller Scaling Fields with Ensemble Kalman Filter

    Science.gov (United States)

    Bauser, H. H.; Jaumann, S.; Roth, K.

    2015-12-01

    The Ensemble Kalman Filter (EnKF) is a widely used data assimilation method in soil hydrology to estimate states and parameters, incorporating uncertainties in measurements and all model components.Of these components not only states and parameters, but also the representation of small scale heterogeneities of different soil layers suffers from large uncertainties. This is particularly severe when measuring soil water content, which reflects the soil's local texture and is typically discontinuous across heterogeneity boundaries. To address this challenge we enhance the EnKF to simultaneously also estimate a Miller scaling field for each soil layer.The enhanced EnKF is tested with a one-dimensional water content data set based on time domain reflectometry (TDR) measurements and leads to an improved consistency of model and measurements.

  9. Low Complexity Sparse Bayesian Learning for Channel Estimation Using Generalized Mean Field

    DEFF Research Database (Denmark)

    Pedersen, Niels Lovmand; Manchón, Carles Navarro; Fleury, Bernard Henri

    2014-01-01

    constrain the auxiliary function approximating the posterior probability density function of the unknown variables to factorize over disjoint groups of contiguous entries in the sparse vector - the size of these groups dictates the degree of complexity reduction. The original high-complexity algorithms......We derive low complexity versions of a wide range of algorithms for sparse Bayesian learning (SBL) in underdetermined linear systems. The proposed algorithms are obtained by applying the generalized mean field (GMF) inference framework to a generic SBL probabilistic model. In the GMF framework, we...

  10. Class separation and parameter estimation with neural networks for the XEUS wide field imager

    Science.gov (United States)

    Zimmermann, J.; Kiesling, C.; Holl, P.

    2003-04-01

    The X-ray space telescope XEUS is the proposed follow-up project to ESA's cornerstone mission XMM-Newton which is now in orbit. To face the high data rate from the pixel detector and to improve event processing neural networks are under study to be integrated into the electronics on board (online) and to serve as analysis tool on ground (offline). For two applications results are presented. First as a typical online application, the separation of single photon events from pileup: here the unwanted event topologies are separated from useful ones belonging to a single X-ray photon. Second a typical off-line application, the estimation of the incident position of a photon: here the charge splitting (i.e. signal charges are collected by two or more adjacent pixels) can be used to determine a precise incident position of a photon. The neural network results are compared with standard methods.

  11. Simultaneous estimation of relative permeability and porosity/permeability fields by history matching production data

    Energy Technology Data Exchange (ETDEWEB)

    Eydinov, D. [Scandpower, Kjeller (Norway); Gao, G. [Chevron, San Ramon, CA (United States); Li, G.; Reynolds, A.C. [Tulsa Univ., Tulsa, OK (United States)

    2007-07-01

    Relative permeability curves are typically obtained through core flood tests. This paper provided details of a procedure that used automatic history matching of 3-phase flow production data to estimate permeability curves with grid block porosities. The method used a B-spline approximation to represent sets of permeability curves with a log transformation of parameters to ensure that curves were monotonic or convex. It was assumed that the model vector was a multivariate Gaussian distribution. The history matching problem was considered in a Bayesian framework. The method was then compared with a power law model using the same data from a synthetic reservoir model. Results showed that the B-spline model obtained more accurate permeability curves than the power law model. The randomized maximum likelihood (RML) method was used to quantify uncertainties in the model parameters. 19 refs., 17 figs.

  12. Methodologies for estimating toxicity of shoreline cleaning agents in the field

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, J.R.Jr.; Stransky, B.C.; Schwartz, M.J.; Snyder, B.J.; Lees, D.C. [Ogden Environmental and Energy Services Co., Oak Ridge, TN (United States); Michel, J. [Research Planning, Inc., Columbia, SC (United States); Reilly, T.J. [PCCI, Alexandria, VA (United States)

    1996-09-01

    Four methodologies that could be used in a portable kit to estimate quantitative and qualitative information regarding the toxicity of oil spill cleaning agents, were evaluated. Onshore cleaning agents (SCAs) are meant to enhance the removal of treated oil from shoreline surfaces, and should not increase adverse impacts to organisms in a treated area. Tests, therefore, should be performed with resident organisms likely to be impacted during the use of SCAs. The four methodologies were Microtox{sup T}M, fertilization success for echinoderm eggs, byssal thread attachment in mussels, and righting and water-escaping ability in periwinkle snails. Site specific variations in physical and chemical properties of the oil and SCAs were considered. Results were provided, showing all combinations of oils and SCAs. Evaluation showed that all four methodologies provided sufficient information to assist a user in deciding whether or not the use of an SCA was warranted. 33 refs., 7 tabs., 11 figs.

  13. Fast motion vector estimation by using spatiotemporal correlation of motion field

    Science.gov (United States)

    Kim, Sungook; Chalidabhongse, Junavit; Kuo, C.-C. Jay

    1995-04-01

    Motion vector (MV) estimation plays an important role in motion compensated video coding. In this research, we first examine a stochastic MV model which enables us to exploit the strong correlation of MVs in both spatial and temporal domains in a given image sequence. Then, a new fast stochastic block matching algorithm (SBMA) is proposed. The basic idea is to select a set of good MV candidates and choose from them the one which satisfies a certain spatio-temporal correlation rule. The proposed algorithm reduces matching operations to about 2% of that of the full block matching algorithm (FBMA) with only 2% increase of the sum of absolute difference (SAD) in motion compensated residuals. The excellent performance of the new algorithm is supported by extensive experimental results.

  14. Developing Improved Water Velocity and Flux Estimation from AUVs - Results From Recent ASTEP Field Programs

    Science.gov (United States)

    Kinsey, J. C.; Yoerger, D. R.; Camilli, R.; German, C. R.

    2010-12-01

    Water velocity measurements are crucial to quantifying fluxes and better understanding water as a fundamental transport mechanism for marine chemical and biological processes. The importance of flux to understanding these processes makes it a crucial component of astrobiological exploration to moons possessing large bodies of water, such as Europa. Present technology allows us to obtain submerged water velocity measurements from stationary platforms; rarer are measurements from submerged vehicles which possess the ability to autonomously survey tens of kilometers over extended periods. Improving this capability would also allow us to obtain co-registered water velocity and other sensor data (e.g., mass spectrometers, temperature, oxygen, etc) and significantly enhance our ability to estimate fluxes. We report results from 4 recent expeditions in which we measured water velocities from autonomous underwater vehicles (AUVs) to help quantify flux in three different oceanographic contexts: hydrothermal vent plumes; an oil spill cruise responding to the 2010 Deepwater Horizon blowout; and two expeditions investigating naturally occurring methane seeps. On all of these cruises, we directly measured the water velocities with an acoustic Doppler current profiler (ADCP) mounted on the AUV. Vehicle motion was corrected for using bottom-lock Doppler tracks when available and, in the absence of bottom-lock, estimates of vehicle velocity based on dynamic models. In addition, on the methane seep cruises, we explored the potential of using acoustic mapping sonars, such as multi-beam and sub-bottom profiling systems, to localize plumes and indirectly quantify flux. Data obtained on these expeditions enhanced our scientific investigations and provides data for future development of algorithms for autonomously processing, identifying, and classifying water velocity and flux measurements. Such technology will be crucial in future astrobiology missions where highly constrained

  15. Field-based estimates of avian mortality from West Nile virus infection.

    Science.gov (United States)

    Ward, Michael P; Beveroth, Tara A; Lampman, Richard; Raim, Arlo; Enstrom, David; Novak, Robert

    2010-11-01

    One of the unique characteristics of West Nile virus (WNV) in North America is the large number of bird species for which the virus can be fatal. WNV mortality has been documented through experimental infections of captive birds and necropsies of free-ranging birds. Investigations of WNV-related mortality in wild birds often focus on species with dramatic population declines (e.g., American Crow, Corvus brachyrhynchos); however, few studies have addressed WNV-related mortality in species not exhibiting marked population declines since the arrival of WNV. We conducted a mark-recapture study of 204 Northern Cardinals (Cardinalis cardinalis) in an area with endemic WNV activity to estimate WNV-related mortality. Previous research has shown that once a bird is infected and recovers from WNV it develops antibodies making it resistant to future infection. Assuming that mortality risks from non-WNV causes were the same for individuals with (had been exposed to WNV) and without antibodies (had not been exposed to WNV), we compared the survival rates of birds with and without WNV antibodies to estimate the impact of WNV on wild birds. An information theoretic approach was used, and the apparent survival was found to be 34.6% lower for individuals without antibodies during the period when WNV was most active (July-September). However, the apparent survival rate was 9.0% higher for individuals without antibodies over the rest of the year. These differences in apparent survival suggest that WNV increases mortality during the WNV season and that chronic effects of WNV infection may also be contributing to mortality. Although WNV appears to have increased mortality rates within the population, population trend data do not indicate declines, suggesting that some cardinal populations can compensate for WNV-related mortality.

  16. Estimation of constitutive parameters for the Belridge Diatomite, South Belridge Diatomite Field

    Energy Technology Data Exchange (ETDEWEB)

    Fossum, A.F.; Fredrich, J.T.

    1998-06-01

    A cooperative national laboratory/industry research program was initiated in 1994 that improved understanding of the geomechanical processes causing well casing damage during oil production from weak, compactible formations. The program focused on the shallow diatomaceous oil reservoirs located in California`s San Joaquin Valley, and combined analyses of historical field data, experimental determination of rock mechanical behavior, and geomechanical simulation of the reservoir and overburden response to production and injection. Sandia National Laboratories` quasi-static, large-deformation structural mechanics finite element code JAS3D was used to perform the three-dimensional geomechanical simulations. One of the material models implemented in JAS3D to simulate the time-independent inelastic (non-linear) deformation of geomaterials is a generalized version of the Sandler and Rubin cap plasticity model (Sandler and Rubin, 1979). This report documents the experimental rock mechanics data and material cap plasticity models that were derived to describe the Belridge Diatomite reservoir rock at the South Belridge Diatomite Field, Section 33.

  17. An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations

    CERN Document Server

    Raja, K Sasikumar; Hariharan, K; Kathiravan, C; Wang, T J

    2016-01-01

    We report ground based, low frequency heliograph (80 MHz), spectral (85-35 MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the `halo' coronal mass ejection (CME) that occurred in the solar atmosphere on 2013 March 15. The magnetic field strengths ($B$) near the radio source were estimated to be $B \\approx 2.2 \\pm 0.4$ G at 80 MHz and $B \\approx 1.4 \\pm 0.2$ G at 40 MHz. The corresponding radial distances ($r$) are $r \\approx 1.9~R_{\\odot}$ (80 MHz) and $r \\approx 2.2~R_{\\odot}$ (40 MHz).

  18. Magnetic helicity estimations in models and observations of the solar magnetic field. Part I: Finite volume methods

    CERN Document Server

    Valori, Gherardo; Anfinogentov, Sergey; Chen, Feng; Georgoulis, Manolis K; Guo, Yang; Liu, Yang; Moraitis, Kostas; Thalmann, Julia K; Yang, Shangbin

    2016-01-01

    Magnetic helicity is a conserved quantity of ideal magneto-hydrodynamics characterized by an inverse turbulent cascade. Accordingly, it is often invoked as one of the basic physical quantities driving the generation and structuring of magnetic fields in a variety of astrophysical and laboratory plasmas. We provide here the first systematic comparison of six existing methods for the estimation of the helicity of magnetic fields known in a finite volume. All such methods are reviewed, benchmarked, and compared with each other, and specifically tested for accuracy and sensitivity to errors. To that purpose, we consider four groups of numerical tests, ranging from solutions of the three-dimensional, force-free equilibrium, to magneto-hydrodynamical numerical simulations. Almost all methods are found to produce the same value of magnetic helicity within few percent in all tests. In the more solar-relevant and realistic of the tests employed here, the simulation of an eruptive flux rope, the spread in the computed ...

  19. Impact of Spatial Resolution on Wind Field Derived Estimates of Air Pressure Depression in the Hurricane Eye

    Directory of Open Access Journals (Sweden)

    Linwood Jones

    2010-03-01

    Full Text Available Measurements of the near surface horizontal wind field in a hurricane with spatial resolution of order 1–10 km are possible using airborne microwave radiometer imagers. An assessment is made of the information content of the measured winds as a function of the spatial resolution of the imager. An existing algorithm is used which estimates the maximum surface air pressure depression in the hurricane eye from the maximum wind speed. High resolution numerical model wind fields from Hurricane Frances 2004 are convolved with various HIRAD antenna spatial filters to observe the impact of the antenna design on the central pressure depression in the eye that can be deduced from it.

  20. Bridging Estimates of Greenness in an Arid Grassland Using Field Observations, Phenocams, and Time Series Unmanned Aerial System (UAS) Imagery

    Science.gov (United States)

    Browning, D. M.; Tweedie, C. E.; Rango, A.

    2013-12-01

    Spatially extensive grasslands and savannas in arid and semi-arid ecosystems (i.e., rangelands) require cost-effective, accurate, and consistent approaches for monitoring plant phenology. Remotely sensed imagery offers these capabilities; however contributions of exposed soil due to modest vegetation cover, susceptibility of vegetation to drought, and lack of robust scaling relationships challenge biophysical retrievals using moderate- and coarse-resolution satellite imagery. To evaluate methods for characterizing plant phenology of common rangeland species and to link field measurements to remotely sensed metrics of land surface phenology, we devised a hierarchical study spanning multiple spatial scales. We collect data using weekly standardized field observations on focal plants, daily phenocam estimates of vegetation greenness, and very high spatial resolution imagery from an Unmanned Aerial System (UAS) throughout the growing season. Field observations of phenological condition and vegetation cover serve to verify phenocam greenness indices along with indices derived from time series UAS imagery. UAS imagery is classified using object-oriented image analysis to identify species-specific image objects for which greenness indices are derived. Species-specific image objects facilitate comparisons with phenocam greenness indices and scaling spectral responses to footprints of Landsat and MODIS pixels. Phenocam greenness curves indicated rapid canopy development for the widespread deciduous shrub Prosopis glandulosa over 14 (in April 2012) to 16 (in May 2013) days. The modest peak in greenness for the dominant perennial grass Bouteloua eriopoda occurred in October 2012 following peak summer rainfall. Weekly field estimates of canopy development closely coincided with daily patterns in initial growth and senescence for both species. Field observations improve the precision of the timing of phenophase transitions relative to inflection points calculated from phenocam

  1. The Use of Satellite Imagery to Guide Field Plot Sampling Scheme for Biomass Estimation in Ghanaian Forest

    Science.gov (United States)

    Sah, B. P.; Hämäläinen, J. M.; Sah, A. K.; Honji, K.; Foli, E. G.; Awudi, C.

    2012-07-01

    Accurate and reliable estimation of biomass in tropical forest has been a challenging task because a large proportion of forests are difficult to access or inaccessible. So, for effective implementation of REDD+ and fair benefit sharing, the proper designing of field plot sampling schemes plays a significant role in achieving robust biomass estimation. The existing forest inventory protocols using various field plot sampling schemes, including FAO's regular grid concept of sampling for land cover inventory at national level, are time and human resource intensive. Wall to wall LiDAR scanning is, however, a better approach to assess biomass with high precision and spatial resolution even though this approach suffers from high costs. Considering the above, in this study a sampling design based on a LiDAR strips sampling scheme has been devised for Ghanaian forests to support field plot sampling. Using Top-of-Atmosphere (TOA) reflectance value of satellite data, Land Use classification was carried out in accordance with IPCC definitions and the resulting classes were further stratified, incorporating existing GIS data of ecological zones in the study area. Employing this result, LiDAR sampling strips were allocated using systematic sampling techniques. The resulting LiDAR strips represented all forest categories, as well as other Land Use classes, with their distribution adequately representing the areal share of each category. In this way, out of at total area of 15,153km2 of the study area, LiDAR scanning was required for only 770 km2 (sampling intensity being 5.1%). We conclude that this systematic LiDAR sampling design is likely to adequately cover variation in above-ground biomass densities and serve as sufficient a-priori data, together with the Land Use classification produced, for designing efficient field plot sampling over the seven ecological zones.

  2. An Optical Model for Estimating the Underwater Light Field from Remote Sensing

    Science.gov (United States)

    Liu, Cheng-Chien; Miller, Richard L.

    2002-01-01

    A model of the wavelength-integrated scalar irradiance for a vertically homogeneous water column is developed. It runs twenty thousand times faster than simulations obtained using full Hydrolight code and limits the percentage error to less than 3.7%. Both the distribution of incident sky radiance and a wind-roughened surface are integrated in the model. Our model removes common limitations of earlier models and can be applied to waters with any composition of the inherent optical properties. Implementation of this new model, as well as the ancillary information required for processing global-scale satellite data, is discussed. This new model is fast, accurate, and flexible and therefore provides important information of the underwater light field from remote sensing.

  3. Estimating the relevance of predictions from nuclear mean-field models

    CERN Document Server

    Reinhard, P -G

    2015-01-01

    This contribution reviews the present status of the Skyrme-Hartree-Fock (SHF) approach as one of the leading self-consistent mean-field models in the physics of atomic nuclei. It starts with a brief summary of the formalism and strategy for proper calibration of the SHF functional. The main emphasis lies on an exploration of the reliability of predictions, particularly in the regime of extrapolations. Various strategies are discussed to explore the statistical and systematic errors of SHF. The strategies are illustrated on examples from actual applications. Variations of model and fit data are used to get an idea about systematic errors. The statistical error is evaluated in straightforward manner by statistical analysis based on $\\chi^2$ fits. This also allows also to evaluate the correlations (covariances) between observables which provides useful insights into the structure of the model and of the fitting strategy.

  4. Analytical estimation on divergence and flutter vibrations of symmetrical three-phase induction stator via field-synchronous coordinates

    Science.gov (United States)

    Xia, Ying; Wang, Shiyu; Sun, Wenjia; Xiu, Jie

    2017-01-01

    The electromagnetically induced parametric vibration of the symmetrical three-phase induction stator is examined. While it can be analyzed by an approximate analytical or numerical method, more accurate and simple analytical method is desirable. This work proposes a new method based on the field-synchronous coordinates. A mechanical-electromagnetic coupling model is developed under this frame such that a time-invariant governing equation with gyroscopic term can be developed. With the general vibration theory, the eigenvalue is formulated; the transition curves between the stable and unstable regions, and response are all determined as closed-form expressions of basic mechanical-electromagnetic parameters. The dependence of these parameters on the instability behaviors is demonstrated. The results imply that the divergence and flutter instabilities can occur even for symmetrical motors with balanced, constant amplitude and sinusoidal voltage. To verify the analytical predictions, this work also builds up a time-variant model of the same system under the conventional inertial frame. The Floquét theory is employed to predict the parametric instability and the numerical integration is used to obtain the parametric response. The parametric instability and response are both well compared against those under the field-synchronous coordinates. The proposed field-synchronous coordinates allows a quick estimation on the electromagnetically induced vibration. The convenience offered by the body-fixed coordinates is discussed across various fields.

  5. Computer simulation of three-dimensional heavy ion beam trajectory imaging techniques used for magnetic field estimation.

    Science.gov (United States)

    Ling, C; Connor, K A; Demers, D R; Radke, R J; Schoch, P M

    2007-11-01

    A magnetic field mapping technique via heavy ion beam trajectory imaging is being developed on the Madison Symmetric Torus reversed field pinch. This paper describes the computational tools created to model camera images of the light emitted from a simulated ion beam, reconstruct a three-dimensional trajectory, and estimate the accuracy of the reconstruction. First, a computer model is used to create images of the torus interior from any candidate camera location. It is used to explore the visual field of the camera and thus to guide camera parameters and placement. Second, it is shown that a three-dimensional ion beam trajectory can be recovered from a pair of perspectively projected trajectory images. The reconstruction considers effects due to finite beam size, nonuniform beam current density, and image background noise. Third, it is demonstrated that the trajectory reconstructed from camera images can help compute magnetic field profiles, and might be used as an additional constraint to an equilibrium reconstruction code, such as MSTFit.

  6. Estimation of VOC emissions from produced-water treatment ponds in Uintah Basin oil and gas field using modeling techniques

    Science.gov (United States)

    Tran, H.; Mansfield, M. L.; Lyman, S. N.; O'Neil, T.; Jones, C. P.

    2015-12-01

    Emissions from produced-water treatment ponds are poorly characterized sources in oil and gas emission inventories that play a critical role in studying elevated winter ozone events in the Uintah Basin, Utah, U.S. Information gaps include un-quantified amounts and compositions of gases emitted from these facilities. The emitted gases are often known as volatile organic compounds (VOCs) which, beside nitrogen oxides (NOX), are major precursors for ozone formation in the near-surface layer. Field measurement campaigns using the flux-chamber technique have been performed to measure VOC emissions from a limited number of produced water ponds in the Uintah Basin of eastern Utah. Although the flux chamber provides accurate measurements at the point of sampling, it covers just a limited area of the ponds and is prone to altering environmental conditions (e.g., temperature, pressure). This fact raises the need to validate flux chamber measurements. In this study, we apply an inverse-dispersion modeling technique with evacuated canister sampling to validate the flux-chamber measurements. This modeling technique applies an initial and arbitrary emission rate to estimate pollutant concentrations at pre-defined receptors, and adjusts the emission rate until the estimated pollutant concentrations approximates measured concentrations at the receptors. The derived emission rates are then compared with flux-chamber measurements and differences are analyzed. Additionally, we investigate the applicability of the WATER9 wastewater emission model for the estimation of VOC emissions from produced-water ponds in the Uintah Basin. WATER9 estimates the emission of each gas based on properties of the gas, its concentration in the waste water, and the characteristics of the influent and treatment units. Results of VOC emission estimations using inverse-dispersion and WATER9 modeling techniques will be reported.

  7. Amending instruction to JC/T 533 -2004 Chromium allory grinding balls for building materials industry%关于JC/T533-2004《水泥工业用铬合金铸造磨球》标准的修订

    Institute of Scientific and Technical Information of China (English)

    郭伟; 穆惠民

    2005-01-01

    @@ 1 前言 JC/T 533-2004标准于2004年10月20日发布,2005年5月1日实施,这项标准是在原JC/T 533-1994实施的基础上,结合多年来实践经验和国外的先进产品的参数、指标进行修订的.

  8. Intercomparison of Level 3 fields estimated from OCO-2 and GOSAT-ACOSmeasurements of XCO2

    Science.gov (United States)

    Weir, B.; Chatterjee, A.; Ott, L. E.; Pawson, S.

    2016-12-01

    The GEOS-Carb modeling and assimilation system is an extension of the GEOS-5general circulation model and data assimilation system developed at NASA'sGlobal Modeling and Assimilation Office (GMAO). One of its primary functionsis to ingest observations of carbon dioxide (CO2) and produce estimates andpredictions of atmospheric mixing ratios of CO2 over the Earth. In particular,the system processes retrievals of column-average carbon dioxide (XCO2) basedon near-infrared radiance measurements from the Orbiting Carbon Observatory 2(OCO-2) and the Greenhouse Gases Observing Satellite (GOSAT). The resultingLevel 3 (L3) maps are the most complete and highest resolution assimilatedpicture of global CO2 yet. The extent of its coverage makes the L3 product apowerful tool for the evaluation of the satellite data against independentobservations. This evaluation approach does not require using coincidencecriteria and can be applied across heterogeneous observations (e.g., comparingthe assimilation of XCO2 retrievals to flask samples). This presentationdescribes the evaluation of L3 maps computed from OCO-2 and GOSAT AtmosphericCO2 Observations from Space (GOSAT-ACOS) retrievals against ground-basedmeasurements of XCO2 from the Total Column Carbon Observing Network (TCCON) andin situ measurements from flasks, towers, and aircraft taken by NOAA/ESRL. Theevaluation focuses on comparison of the bias and uncertainty of the tworetrievals and how understanding these differences can improve the use of theretrievals in assimilation systems.

  9. Morfologia da flor, fruto e plântula de Victoria amazonica (Poepp.) J.C. Sowerby (Nymphaeaceae) Morphology of flower, fruit and seedling of Victoria amazonica (Poepp.) J.C. Sowerby (Nymphaeaceae)

    OpenAIRE

    Sônia Maciel da Rosa-Osman; Robson Rodrigues; Maria Sílvia de Mendonça; Luiz Antonio de Souza; Maria Teresa Fernandez Piedade

    2011-01-01

    Victoria amazonica (Poepp.) J.C. Sowerby é uma hidrófita que ocorre nas várzeas de águas brancas e igapós da Bacia Amazônica e na Bacia do rio Paraguai. A morfologia da flor, fruto e plântula/"tirodendro" é objeto do presente trabalho. O material botânico foi coletado em Parintins e Manaus, estado do Amazonas, Brasil. A análise morfológica foi feita em material fresco e fixado em FAA 50. O desenvolvimento das plântulas foi realizado no escuro em frascos com água com teor reduzido de oxigênio....

  10. Accurate and rapid error estimation on global gravitational field from current GRACE and future GRACE Follow-On missions

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei; Hsu Hou-Tse; Zhong Min; Yun Mei-Juan

    2009-01-01

    Firstly,the new combined error model of cumulative geoid height influenced by four error sources,including the inter-satellite range-rate of an interferometric laser (K-band) ranging system,the orbital position and velocity of a global positioning system (GPS) receiver and non-conservative force of an accelerometer,is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach.Secondly,the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985×10-1 m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory (JPL),and the cumulative geoid height error is 5.825×10-2 m at degree 360 using GRACE Follow-On orbital altitude 250 km and inter-satellite range 50 km.The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward,and the dependability of the combined error model is validated.Finally,the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes.

  11. Comparison of two field methods for estimating body fat in different spanish dance disciplines.

    Science.gov (United States)

    Alvero-Cruz, José Ramón; Marfell-Jones, Mike; Alacid, Fernando; Artero Orta, Pedro; Correas-Gómez, Lorena; Santonja Medina, Fernando; Carnero, Elvis A

    2014-09-01

    The purpose of the present study was to investigate percentage body fat (%BF) differences in three Spanish dance disciplines and to compare skinfold and bioelectrical impedance predictions of body fat percentage in the same sample. Seventy-six female dancers, divided into three groups, Classical (n=23), Spanish (n=29) and Flamenco (n=24), were measured using skinfold measurements at four sites: triceps, subscapular, biceps and iliac crest, and whole body multi-frequency bioelectrical impedance (BIA). The skinfold measures were used to predict body fat percentage via Durnin and Womersley's and Segal, Sun and Yannakoulia equations by BIA. Differences in percent fat mass between groups (Classical, Spanish and Flamenco) were tested by using repeated measures analysis (ANOVA). Also, Pearson's product-moment correlations were performed on the body fat percentage values obtained using both methods. In addition, Bland-Altman plots were used to assess agreement, between anthropometric and BIA methods. Repeated measures analysis of variance did not found differences in %BF between modalities (p<0.05). Fat percentage correlations ranged from r= 0.57 to r=0.97 (all, p<0.001). Bland-Altman analysis revealed differences between BIA Yannakoulia as a reference method with BIA Segal (-0.35 ± 2.32%, 95%CI: -0.89to 0.18, p=0.38), with BIA Sun (-0.73 ± 2.3%, 95%CI: -1.27 to -0.20, p=0.014) and Durnin-Womersley (-2.65 ± 2,48%, 95%CI: -3.22 to -2.07, p<0.0001). It was concluded that body fat percentage estimates by BIA compared with skinfold method were systematically different in young adult female ballet dancers, having a tendency to produce underestimations as %BF increased with Segal and Durnin-Womersley equations compared to Yannakoulia, concluding that these methods are not interchangeable. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  12. Daily global fire radiative power fields estimation from one or two MODIS instruments

    Directory of Open Access Journals (Sweden)

    S. Remy

    2014-08-01

    Full Text Available Fires are important emitters of aerosol and trace gases and as such need to be taken into account in any atmospheric composition modeling enterprise. One method to estimate these emissions is to convert Fire Radiative Power (FRP analysis to dry matter burnt and emissions of smoke constituents using land cover dependent conversion factors. Inventories like the Global Fire Assimilation System (GFAS follow this approach by calculating daily global smoke emissions from FRP observed by the MODIS instruments on-board of the Terra and Aqua satellites. Observations with different overpass times systematically sample fires at different stages in the strong diurnal fire cycle. For some time periods, observations are available from only one instrument, which leads to a bias in the observed average FRP. We develop a method to correct this bias in daily FRP observations from any Low Earth Orbit (LEO satellite, so that the budget of daily smoke emissions remains independent of the number of satellites from which FRP observations are taken into account. This ensures the possibility of running, e.g., GFAS in case of a default of one of the MODIS instruments. It also enables the extension GFAS to 2000–2002 and the inclusion of FRP observations from upcoming satellite missions. The correction combines linear and non-linear regressions and uses an adaptive regionalization algorithm. It removes the bias in daily average FRP observations from Terra and Aqua nearly entirely. Errors are larger for Terra than for Aqua, are generally relatively small at a global scale, but can be important at a local scale. The correction algorithm is applied to Terra observations from 25 February 2000 to 31 December 2002, when Aqua observations were not available. The database of fire emissions GFASv1.0 is extended correspondingly.

  13. Comparison of two field methods for estimating body fat in different Spanish Dance disciplines

    Directory of Open Access Journals (Sweden)

    José Ramón Alvero-Cruz

    Full Text Available The purpose of the present study was to investigate percentage body fat (%BF differences in three Spanish dance disciplines and to compare skinfold and bioelectrical impedance predictions of body fat percentage in the same sample. Seventy-six female dancers, divided into three groups, Classical (n=23, Spanish (n=29 and Flamenco (n=24, were measured using skinfold measurements at four sites: triceps, subscapular, biceps and iliac crest, and whole body multi-frequency bioelectrical impedance (BIA. The skin-fold measures were used to predict body fat percentage via Durnin and Womersley's and Segal, Sun and Yannakoulia equations by BIA. Differences in percent fat mass between groups (Classical, Spanish and Flamenco were tested by using repeated measures analysis (ANOVA. Also, Pearson's product-moment correlations were performed on the body fat percentage values obtained using both methods. In addition, Bland-Altman plots were used to assess agreement, between anthropometric and BIA methods. Repeated measures analysis of variance did not found differences in %BF between modalities (p<0.05. Fat percentage correlations ranged from r= 0.57 to r=0.97 (all, p<0.001. Bland-Altman analysis revealed differences between BIA Yannakoulia as a reference method with BIA Segal (-0.35 ± 2.32%, 95%CI: -0.89to 0.18, p=0.38, with BIA Sun (-0.73 ± 2.3%, 95%CI: -1.27 to -0.20, p=0.014 and Durnin-Womersley (-2.65 ± 2,48%, 95%CI: -3.22 to -2.07, p<0.0001. It was concluded that body fat percentage estimates by BIA compared with skinfold method were systematically different in young adult female ballet dancers, having a tendency to produce underestimations as %BF increased with Segal and Durnin-Womersley equations compared to Yannakoulia, concluding that these methods are not interchangeable.

  14. A Coupled Remote Sensing and Simplified Surface Energy Balance Approach to Estimate Actual Evapotranspiration from Irrigated Fields

    Directory of Open Access Journals (Sweden)

    Assefa M. Melesse

    2007-06-01

    Full Text Available Accurate crop performance monitoring and production estimation are critical fortimely assessment of the food balance of several countries in the world. Since 2001, theFamine Early Warning Systems Network (FEWS NET has been monitoring cropperformance and relative production using satellite-derived data and simulation models inAfrica, Central America, and Afghanistan where ground-based monitoring is limitedbecause of a scarcity of weather stations. The commonly used crop monitoring models arebased on a crop water-balance algorithm with inputs from satellite-derived rainfallestimates. These models are useful to monitor rainfed agriculture, but they are ineffectivefor irrigated areas. This study focused on Afghanistan, where over 80 percent ofagricultural production comes from irrigated lands. We developed and implemented aSimplified Surface Energy Balance (SSEB model to monitor and assess the performanceof irrigated agriculture in Afghanistan using a combination of 1-km thermal data and 250-m Normalized Difference Vegetation Index (NDVI data, both from the Moderate Resolution Imaging Spectroradiometer (MODIS sensor. We estimated seasonal actual evapotranspiration (ETa over a period of six years (2000-2005 for two major irrigated river basins in Afghanistan, the Kabul and the Helmand, by analyzing up to 19 cloud-free thermal and NDVI images from each year. These seasonal ETa estimates were used as relative indicators of year-to-year production magnitude differences. The temporal water- use pattern of the two irrigated basins was indicative of the cropping patterns specific to each region. Our results were comparable to field reports and to estimates based on watershed-wide crop water-balance model results. For example, both methods found that the 2003 seasonal ETa was the highest of all six years. The method also captured water management scenarios where a unique year-to-year variability was identified in addition to water-use differences between

  15. Estimation of deepwater temperature and hydrogeochemistry of springs in the Takab geothermal field, West Azerbaijan, Iran.

    Science.gov (United States)

    Sharifi, Reza; Moore, Farid; Mohammadi, Zargham; Keshavarzi, Behnam

    2016-01-01

    Chemical analyses of water samples from 19 hot and cold springs are used to characterize Takab geothermal field, west of Iran. The springs are divided into two main groups based on temperature, host rock, total dissolved solids (TDS), and major and minor elements. TDS, electrical conductivity (EC), Cl(-), and SO4 (2-) concentrations of hot springs are all higher than in cold springs. Higher TDS in hot springs probably reflect longer circulation and residence time. The high Si, B, and Sr contents in thermal waters are probably the result of extended water-rock interaction and reflect flow paths and residence time. Binary, ternary, and Giggenbach diagrams were used to understand the deeper mixing conditions and locations of springs in the model system. It is believed that the springs are heated either by mixing of deep geothermal fluid with cold groundwater or low conductive heat flow. Mixing ratios are evaluated using Cl, Na, and B concentrations and a mass balance approach. Calculated quartz and chalcedony geothermometer give lower reservoir temperatures than cation geothermometers. The silica-enthalpy mixing model predicts a subsurface reservoir temperature between 62 and 90 °C. The δ(18)O and δD (δ(2)H) are used to trace and determine the origin and movement of water. Both hot and cold waters plot close to the local meteoric line, indicating local meteoric origin.

  16. Stability estimates for linearized near-field phase retrieval in X-ray phase contrast imaging

    CERN Document Server

    Maretzke, Simon

    2016-01-01

    Propagation-based X-ray phase contrast enables nanoscale imaging of biological tissue by probing not only the attenuation, but also the real part of the refractive index of the sample. Since only intensities of diffracted waves can be measured, the main mathematical challenge consists in a phase-retrieval problem in the near-field regime. We treat an often used linearized version of this problem known as contract transfer function model. Surprisingly, this inverse problem turns out to be well-posed assuming only a compact support of the imaged object. Moreover, we establish bounds on the Lipschitz stability constant. In general this constant grows exponentially with the Fresnel number of the imaging setup. However, both for homogeneous objects, characterized by a fixed ratio of the induced refractive phase shifts and attenuation, and in the case of measurements at two distances, a much more favorable algebraic dependence on the Fresnel number can be shown. In some cases we establish order optimality of our es...

  17. INTERRUPTED IN-SITU COMPRESSIVE DEFORMATION EXPERIMENTS ON MMC FOAMS IN AN XCT: EXPERIMENTS AND ESTIMATION OF DISPLACEMENT FIELDS

    Directory of Open Access Journals (Sweden)

    Katharina Losch

    2014-05-01

    Full Text Available The mechanical properties of a metal-matrix composite foam are investigated by interrupted in-situ compressive deformation experiments within an X-ray computed tomography device (XCT. Each in-situ experiment generates a sequence of reconstructed 3D images of the foam microstructure. From these data, the deformation field is estimated by registring the images corresponding to three consecutive steps. To this end, the generic registration framework of the itk software suite is exploited and combined with several image preprocessing steps. Both segmented (binary images having just two grey values for foreground (strut structure and background (pore space and the result of the Euclidean distance transform (EDT on pore space and solid phase are used. The estimation quality is evaluated based on a sequence of synthetic data sets, where the foam’s microstructure is modelled by a random Laguerre tessellation. For large deformations, a combination of non-rigid registration for the EDT images and partwise-rigid registration on strongly deformed regions of the binary images, yields surprisingly small estimation errors.

  18. Simultaneous soil moisture and properties estimation for a drip irrigated field by assimilating cosmic-ray neutron intensity

    Science.gov (United States)

    Han, Xujun; Hendricks Franssen, Harrie-Jan; Jiménez Bello, Miguel Ángel; Rosolem, Rafael; Bogena, Heye; Alzamora, Fernando Martínez; Chanzy, André; Vereecken, Harry

    2016-08-01

    Neutron intensity measured by the aboveground cosmic-ray neutron intensity probe (CRP) allows estimating soil moisture content at the field scale. In this work, synthetic neutron intensities were used to remove the bias of simulated soil moisture content or update soil hydraulic properties (together with soil moisture) in the Community Land Model (CLM) using the Local Ensemble Transform Kalman Filter. The cosmic-ray forward model COSMIC was used as the non-linear measurement operator which maps between neutron intensity and soil moisture. The novel aspect of this work is that synthetically measured neutron intensity was used for real time updating of soil states and soil properties (or soil moisture bias) and posterior use for the real time scheduling of irrigation (data assimilation based real-time control approach). Uncertainty of model forcing and soil properties (sand fraction, clay fraction and organic matter density) were considered in the ensemble predictions of the soil moisture profiles. Horizontal and vertical weighting of soil moisture was introduced in the data assimilation in order to handle the scale mismatch between the cosmic-ray footprint and the CLM grid cell. The approach was illustrated in a synthetic study with the real-time irrigation scheduling of fields of citrus trees. After adjusting soil moisture content by assimilating neutron intensity, the irrigation requirements were calculated based on the water deficit method. Model bias was introduced by using coarser soil texture in the data assimilation experiments than in reality. A series of experiments was done with different combinations of state, parameter and bias estimation in combination with irrigation scheduling. Assimilation of CRP neutron intensity improved soil moisture characterization. Irrigation requirement was overestimated if biased soil properties were used. The soil moisture bias was reduced by 35% after data assimilation. The scenario of joint state-parameter estimation

  19. Alternative ways of using field-based estimates to calibrate ecosystem models and their implications for carbon cycle studies

    Science.gov (United States)

    He, Yujie; Zhuang, Qianlai; McGuire, David; Liu, Yaling; Chen, Min

    2013-01-01

    Model-data fusion is a process in which field observations are used to constrain model parameters. How observations are used to constrain parameters has a direct impact on the carbon cycle dynamics simulated by ecosystem models. In this study, we present an evaluation of several options for the use of observations in modeling regional carbon dynamics and explore the implications of those options. We calibrated the Terrestrial Ecosystem Model on a hierarchy of three vegetation classification levels for the Alaskan boreal forest: species level, plant-functional-type level (PFT level), and biome level, and we examined the differences in simulated carbon dynamics. Species-specific field-based estimates were directly used to parameterize the model for species-level simulations, while weighted averages based on species percent cover were used to generate estimates for PFT- and biome-level model parameterization. We found that calibrated key ecosystem process parameters differed substantially among species and overlapped for species that are categorized into different PFTs. Our analysis of parameter sets suggests that the PFT-level parameterizations primarily reflected the dominant species and that functional information of some species were lost from the PFT-level parameterizations. The biome-level parameterization was primarily representative of the needleleaf PFT and lost information on broadleaf species or PFT function. Our results indicate that PFT-level simulations may be potentially representative of the performance of species-level simulations while biome-level simulations may result in biased estimates. Improved theoretical and empirical justifications for grouping species into PFTs or biomes are needed to adequately represent the dynamics of ecosystem functioning and structure.

  20. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land-use

    Directory of Open Access Journals (Sweden)

    S. Siltecho

    2014-06-01

    Full Text Available Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land-use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land-uses and to compare the results obtained with different measurement methods (Beerkan, Disk infiltrometer, Evaporation, pedotransfer function. The study has been realised on a tropical sandy soil in a mini watershed in NE Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n, were significantly different according to the measurement methods employed whereas location was not a significant discriminating factor when all methods were considered together. However within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a one year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modelling, any of these measurement method could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  1. Dense deformation field estimation for atlas-based segmentation of pathological MR brain images.

    Science.gov (United States)

    Bach Cuadra, M; De Craene, M; Duay, V; Macq, B; Pollo, C; Thiran, J-Ph

    2006-12-01

    Atlas registration is a recognized paradigm for the automatic segmentation of normal MR brain images. Unfortunately, atlas-based segmentation has been of limited use in presence of large space-occupying lesions. In fact, brain deformations induced by such lesions are added to normal anatomical variability and they may dramatically shift and deform anatomically or functionally important brain structures. In this work, we chose to focus on the problem of inter-subject registration of MR images with large tumors, inducing a significant shift of surrounding anatomical structures. First, a brief survey of the existing methods that have been proposed to deal with this problem is presented. This introduces the discussion about the requirements and desirable properties that we consider necessary to be fulfilled by a registration method in this context: To have a dense and smooth deformation field and a model of lesion growth, to model different deformability for some structures, to introduce more prior knowledge, and to use voxel-based features with a similarity measure robust to intensity differences. In a second part of this work, we propose a new approach that overcomes some of the main limitations of the existing techniques while complying with most of the desired requirements above. Our algorithm combines the mathematical framework for computing a variational flow proposed by Hermosillo et al. [G. Hermosillo, C. Chefd'Hotel, O. Faugeras, A variational approach to multi-modal image matching, Tech. Rep., INRIA (February 2001).] with the radial lesion growth pattern presented by Bach et al. [M. Bach Cuadra, C. Pollo, A. Bardera, O. Cuisenaire, J.-G. Villemure, J.-Ph. Thiran, Atlas-based segmentation of pathological MR brain images using a model of lesion growth, IEEE Trans. Med. Imag. 23 (10) (2004) 1301-1314.]. Results on patients with a meningioma are visually assessed and compared to those obtained with the most similar method from the state-of-the-art.

  2. Revisiting Field Capacity (FC: variation of definition of FC and its estimation from pedotransfer functions

    Directory of Open Access Journals (Sweden)

    Theophilo Benedicto Ottoni Filho

    2014-12-01

    Full Text Available Taking into account the nature of the hydrological processes involved in in situ measurement of Field Capacity (FC, this study proposes a variation of the definition of FC aiming not only at minimizing the inadequacies of its determination, but also at maintaining its original, practical meaning. Analysis of FC data for 22 Brazilian soils and additional FC data from the literature, all measured according to the proposed definition, which is based on a 48-h drainage time after infiltration by shallow ponding, indicates a weak dependency on the amount of infiltrated water, antecedent moisture level, soil morphology, and the level of the groundwater table, but a strong dependency on basic soil properties. The dependence on basic soil properties allowed determination of FC of the 22 soil profiles by pedotransfer functions (PTFs using the input variables usually adopted in prediction of soil water retention. Among the input variables, soil moisture content θ (6 kPa had the greatest impact. Indeed, a linear PTF based only on it resulted in an FC with a root mean squared residue less than 0.04 m³ m-3 for most soils individually. Such a PTF proved to be a better FC predictor than the traditional method of using moisture content at an arbitrary suction. Our FC data were compatible with an equivalent and broader USA database found in the literature, mainly for medium-texture soil samples. One reason for differences between FCs of the two data sets of fine-textured soils is due to their different drainage times. Thus, a standardized procedure for in situ determination of FC is recommended.

  3. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land uses

    Science.gov (United States)

    Siltecho, S.; Hammecker, C.; Sriboonlue, V.; Clermont-Dauphin, C.; Trelo-ges, V.; Antonino, A. C. D.; Angulo-Jaramillo, R.

    2015-03-01

    Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land uses and to compare the results obtained with different measurement methods (Beerkan, disc infiltrometer, evaporation, pedotransfer function). The study has been realized on a tropical sandy soil in a mini-watershed in northeastern Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non-parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n) were significantly different according to the measurement methods employed, whereas the land use was not a significant discriminating factor when all methods were considered together. However, within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a 1-year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modeling, any of these measurement methods could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  4. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land-use

    Science.gov (United States)

    Siltecho, S.; Hammecker, C.; Sriboonlue, V.; Clermont-Dauphin, C.; Trelo-ges, V.; Antonino, A. C. D.; Angulo-Jaramillo, R.

    2014-06-01

    Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land-use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land-uses and to compare the results obtained with different measurement methods (Beerkan, Disk infiltrometer, Evaporation, pedotransfer function). The study has been realised on a tropical sandy soil in a mini watershed in NE Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n), were significantly different according to the measurement methods employed whereas location was not a significant discriminating factor when all methods were considered together. However within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a one year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modelling, any of these measurement method could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  5. Corrections to traditional methods of verifying tangential-breast 3D monitor-unit calculations: use of an equivalent triangle to estimate effective fields.

    Science.gov (United States)

    Prado, Karl L; Kirsner, Steven M; Erice, Rolly C

    2003-01-01

    This paper describes an innovative method for correctly estimating the effective field size of tangential-breast fields. The method uses an "equivalent triangle" to verify intact breast tangential field monitor-unit settings calculated by a 3D planning system to within 2%. The effects on verification calculations of loss of full scatter due to beam oblique incidence, proximity to field boundaries, and reduced scattering volumes are handled properly. The methodology is validated by comparing calculations performed by the 3D planning system with the respective verification estimates. The accuracy of this technique is established for dose calculations both with and without heterogeneity corrections.

  6. Estimability of recharge through groundwater model calibration: Insights from a field-scale steady-state example

    Science.gov (United States)

    Knowling, Matthew J.; Werner, Adrian D.

    2016-09-01

    The ability of groundwater models to inform recharge through calibration is hampered by the correlation between recharge and aquifer parameters such as hydraulic conductivity (K), and the insufficient information content of observation datasets. These factors collectively result in non-uniqueness of parameter estimates. Previous studies that jointly estimate spatially distributed recharge and hydraulic parameters are limited to synthetic test cases and/or do not evaluate the effect of non-uniqueness. The extent to which recharge can be informed by calibration is largely unknown for practical situations, in which complexities such as parameter heterogeneities are inherent. In this study, a systematic investigation of recharge, inferred through model calibration, is undertaken using a series of numerical experiments that include varying degrees of hydraulic parameter information. The analysis involves the use of a synthetic reality, based on a regional-scale, highly parameterised, steady-state groundwater model of Uley South Basin, South Australia. Parameter identifiability is assessed to evaluate the ability of parameters to be estimated uniquely. Results show that a reasonable inference of recharge (average recharge error 100 K values across the 129 km2 study area). The introduction of pumping data into the calibration reduces error in both the average recharge and its spatial variability, whereas submarine groundwater discharge (as a calibration target) reduces average recharge error only. Nonetheless, the estimation of steady-state recharge through inverse modelling may be impractical for real-world settings, limited by the need for unrealistic amounts of hydraulic parameter and groundwater level data. This study provides a useful benchmark for evaluating the extent to which field-scale groundwater models can be used to inform recharge subject to practical data-availability limitations.

  7. Nearly one-half of Brazilian patients with multiple sclerosis using natalizumab are DNA-JC virus positive

    Directory of Open Access Journals (Sweden)

    Yara Dadalti Fragoso

    2013-10-01

    Full Text Available Objective Natalizumab is a new and efficient treatment for multiple sclerosis (MS. The risk of developing progressive multifocal leukoencephalopathy (PML during the use of this drug has created the need for better comprehension of JC virus (JCV infection. The objective of the present study was to assess the prevalence of JCV-DNA in Brazilian patients using natalizumab. Method Qualitative detection of the JCV in the serum was performed with real-time polymerase chain reaction (PCR. Results In a group of 168 patients with MS who were undergoing treatment with natalizumab, JCV-DNA was detectable in 86 (51.2% patients. Discussion Data on JCV-DNA in Brazil add to the worldwide assessment of the prevalence of the JCV in MS patients requiring treatment with natalizumab.

  8. Persistence of DNA sequences of BK virus and JC virus in normal human tissues and in diseased tissues.

    Science.gov (United States)

    Chesters, P M; Heritage, J; McCance, D J

    1983-04-01

    Available evidence suggests that BK virus (BKV) and JC virus (JCV) persist in the kidneys of healthy individuals after primary infection and may reactivate when the host's immune response is impaired. Data supporting this hypothesis are presented. A previous study had shown BKV to be present in the kidneys of eight (57%) of 14 subjects. In the present study, which extended the investigation to a total of 30 subjects, BKV DNA was found in the renal tissues of 10 (33%) subjects, and JCV DNA was found in the renal tissues of three (10%) subjects. The viral DNA detected appeared not to be integrated with host DNA and to be isolated in foci. Investigation of normal and diseased brain tissue, including tissue from six subjects with multiple sclerosis, failed to reveal the presence of either JCV DNA or BKV DNA.

  9. Near-Infrared observations of the type Ib Supernova SN2006jc: evidence of interactions with dust

    CERN Document Server

    Di Carlo, E; Arkharov, A A; Massi, F; Larionov, V M; Efimova, N V; Dolci, M; Napoleone, N; Di Paola, A

    2007-01-01

    In the framework of a program for the monitoring of Supernovae in the Near-Infrared (NIR) carried out by the Teramo, Rome and Pulkovo observatories with the AZT-24 telescope, we observed the Supernova SN2006jc in the J,H,K photometric bands during a period of 7 months, starting ~36 days after its discovery. Our observations evidence a NIR re-brightening, peaking ~70 days after discovery, along with a reddening of H-K and J-H colors until 120 days from discovery. After that date, J-H seems to evolve towards bluer colors. Our data, complemented by IR, optical, UV and X-ray observations found in the literature, show that the re-brightening is produced by hot dust surrounding the supernova, formed in the interaction of the ejecta with dense circumstellar matter.

  10. PCR detection of JC virus DNA in the brain tissue of a 9-year-old child with pleomorphic xanthoastrocytoma.

    Science.gov (United States)

    Boldorini, R; Caldarelli-Stefano, R; Monga, G; Zocchi, M; Mediati, M; Tosoni, A; Ferrante, P

    1998-04-01

    Pleomorphic xanthoastrocytoma (PXA) is a rare cerebral tumor of young adults with a slow growth and a good prognosis. Due to its peculiar histopathological findings, the tumor resemble to the lytic phase of progressive multifocal leukoencephalopathy (PML), a JC Virus (JCV) induced disease. For these reasons, the presence of JCV genoma and viral particles were searched for by means of nested polymerase chain reaction (nPCR) and electron microscopy (EM) in a 9-year-old child with PXA. Although EM did not reveal any viral particles, nPCR did reveal genomic sequences of the LT, R, and VP1 regions of JCV. Sequence analysis showed that the R region was mutated with respect to the archetypal form thus yielding the Mad 4 variant of JCV previously reported as being oncogenic in animals. We suggest that JCV may have played a role in the development of this tumor.

  11. Empirical estimates and theoretical predictions of the shorting factor for the THEMIS double-probe electric field instrument

    Science.gov (United States)

    Califf, S.; Cully, C. M.

    2016-07-01

    Double-probe electric field measurements on board spacecraft present significant technical challenges, especially in the inner magnetosphere where the ambient plasma characteristics can vary dramatically and alter the behavior of the instrument. We explore the shorting factor for the Time History of Events and Macroscale Interactions during Substorms electric field instrument, which is a scale factor error on the measured electric field due to coupling between the sensing spheres and the long wire booms, using both an empirical technique and through simulations with varying levels of fidelity. The empirical data and simulations both show that there is effectively no shorting when the spacecraft is immersed in high-density plasma deep within the plasmasphere and that shorting becomes more prominent as plasma density decreases and the Debye length increases outside the plasmasphere. However, there is a significant discrepancy between the data and theory for the shorting factor in low-density plasmas: the empirical estimate indicates ~0.7 shorting for long Debye lengths, but the simulations predict a shorting factor of ~0.94. This paper systematically steps through the empirical and modeling methods leading to the disagreement with the intention of motivating further study on the topic.

  12. Field Estimates of Attraction of Ceratitis capitata to Trimedlure and Bactrocera dorsalis (Diptera: Tephritidae) to Methyl Eugenol in Varying Environments.

    Science.gov (United States)

    Manoukis, Nicholas C; Siderhurst, Matthew; Jang, Eric B

    2015-06-01

    Measuring and modeling the attractiveness of semiochemical-baited traps is of significant importance to detection, delimitation, and control of invasive pests. Here, we describe the results of field mark-release-recapture experiments with Ceratitis capitata (Wiedemann) and Bactrocera dorsalis (Hendel) to estimate the relationship between distance from a trap baited with trimedlure and methyl eugenol, respectively, and probability of capture for a receptive male insect. Experiments were conducted using a grid of traps with a central release point at two sites on Hawaii Island, a Macadamia orchard on the East side of the island and a lava field on the West side. We found that for B. dorsalis and methyl eugenol there is a 65% probability of capture at ∼36 m from a single trap, regardless of habitat. For C. capitata, we found a 65% probability of capture at a distance of ∼14 m from a single trap in the orchard and 7 m in the lava field. We also present results on the spatial and temporal pattern of recaptures. The attraction data are analyzed via a hyperbolic secant-based capture probability model. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

  13. Characterization of large size YBa2Cu3O7-δ films using magnetic field penetration

    Science.gov (United States)

    Almog, B.; Azoulay, M.; Castro, H.; Deutscher, G.

    2005-11-01

    High critical current density (jc) is one of the most important properties of high Tc superconducting thin films. Determining it is difficult especially in large films (2-3 inch). We propose a non-destructive and easy technique for measuring jc. From measurements of the magnetic moment in the middle of a superconducting film as a function of the external magnetic field, we calculate the macroscopic critical current density.

  14. The key role of Satellite Laser Ranging towards the integrated estimation of geometry, rotation and gravitational field of the Earth

    Science.gov (United States)

    Blossfeld, Mathis

    2015-01-01

    In 2007, the Global Geodetic Observing System (GGOS) was installed as a full component of the International Association of Geodesy (IAG). One primary goal of GGOS is the integration of geometric and gravimetric observation techniques to estimate consistent geodetic-geophysical parameters. Thereby, GGOS is based on the data and services of the IAG. Besides the combination of different geodetic techniques, also the common estimation of the station coordinates (TRF), Earth Orientation Parameters (EOP) and coefficients of the Earth's gravitational field (Stokes coefficients) is necessary in order to reach this goal. However, the combination of all geometric and gravimetric observation techniques is not yet fully realized. A major step towards the GGOS idea of parameter integration would be the understanding of the existing correlations between the above mentioned fundamental geodetic parameter groups. This topic is the major objective of this thesis. One possibility to study the interactions is the use of Satellite Laser Ranging (SLR) in an intertechnique combination with Global Navigation Satellite Systems (GNSS) and Very Long Baseline Interferometry (VLBI) or the intra-technique combination of multiple SLR-tracked satellites. SLR plays a key role in this thesis since it is the unique technique which is sensitive to all parameter groups and allows an integrated parameter estimation with very high accuracy. The present work is based on five first-author publications which are supplemented by four co-author publications. In this framework, for the first time an extensive discussion of a refined global Terrestrial Reference Frame (TRF) estimation procedure, the estimation of so-called Epoch Reference Frames (ERFs) is presented. In contrast to the conventional linear station motion model, the ERFs provide frequently estimated station coordinates and Earth Orientation Parameters (EOP) which allow to approximate not modeled non-linear station motions very accurately

  15. Dissolved methane in rising main sewer systems: field measurements and simple model development for estimating greenhouse gas emissions.

    Science.gov (United States)

    Foley, Jeff; Yuan, Zhiguo; Lant, Paul

    2009-01-01

    At present, the potential generation of methane in wastewater collection systems is ignored under international greenhouse gas (GHG) accounting protocols, despite recent reports of substantial dissolved methane formation in sewers. This suggests that the current national GHG inventories for wastewater handling systems are likely to be underestimated for some situations. This study presents a new catalogue of field data on methane formation in rising main sewerage systems and proposes an empirically-fitted, theoretical model to predict dissolved methane concentrations, based upon the independent variables of pipeline geometry (i.e. surface area to volume ratio, A/V) and hydraulic retention time (HRT). Systems with longer HRT and/or larger A/V ratios are shown to have higher dissolved methane concentrations. This simple predictive model provides a means for water authorities to estimate the methane emissions from other pressurised sewerage systems of similar characteristics.

  16. Gaussian Light Field: Estimation of Viewpoint-Dependent Blur for Optical See-Through Head-Mounted Displays.

    Science.gov (United States)

    Itoh, Yuta; Amano, Toshiyuki; Iwai, Daisuke; Klinker, Gudrun

    2016-11-01

    We propose a method to calibrate viewpoint-dependent, channel-wise image blur of near-eye displays, especially of Optical See-Through Head-Mounted Displays (OST-HMDs). Imperfections in HMD optics cause channel-wise image shift and blur that degrade the image quality of the display at a user's viewpoint. If we can estimate such characteristics perfectly, we could mitigate the effect by applying correction techniques from the computational photography in computer vision as analogous to cameras. Unfortunately, directly applying existing calibration techniques of cameras to OST-HMDs is not a straightforward task. Unlike ordinary imaging systems, image blur in OST-HMDs is viewpoint-dependent, i.e., the optical characteristic of a display dynamically changes depending on the current viewpoint of the user. This constraint makes the problem challenging since we must measure image blur of an HMD, ideally, over the entire 3D eyebox in which a user can see an image. To overcome this problem, we model the viewpoint-dependent blur as a Gaussian Light Field (GLF) that stores spatial information of the display screen as a (4D) light field with depth information and the blur as point-spread functions in the form of Gaussian kernels, respectively. We first describe both our GLF model and a calibration procedure to learn a GLF for a given OST-HMD. We then apply our calibration method to two HMDs that use different optics: a cubic prism or holographic gratings. The results show that our method achieves significantly better accuracy in Point-Spread Function (PSF) estimations with an accuracy about 2 to 7 dB in Peak SNR.

  17. A case study on multi-lane roundabouts under congestion: Comparing software capacity and delay estimates with field data

    Directory of Open Access Journals (Sweden)

    Xuanwu Chen

    2016-04-01

    Full Text Available Existing studies on modern roundabouts performance are mostly based on data from singe lane roundabouts that are not heavily congested. For planners and designers interested in building multilane roundabouts for intersections with potential growth in future traffic, there has been a lack of existing studies with field data that provide reference values in terms of capacity and delay measurements. With the intent of providing such reference values, a case study was conducted by using the East Dowling Road Roundabouts in Anchorage, Alaska, which are currently operating with extensive queues during the evening peak hours. This research used multiple video camcorders to capture vehicle turning movements at the roundabouts as well as the progression of vehicle queues at the roundabout entrance approaches. With these video records, the number of vehicles in the queues can be accurately counted in any single minute during the peak hours. This study shows that unbalanced entrance flow patterns (i.e., one entrance has significant higher flow than others can intensify the queue and delay for the overall roundabouts. Then various software packages including RODEL, SIDRA and VISSIM were used to estimate several performance measurements, such as capacity, queue length, and delay, compared with the collected field data. With the comparison, it is found that all the three software packages overestimate multi-lane roundabout capacity before calibration. With default parameters, SIDRA and VISSIM tend to underestimate delays and queue lengths for the multi-lane roundabouts under congestion, while RODEL results in higher delay and queue length estimations at most of the entrance approaches.

  18. Magnetic, Acceleration Fields and Gyroscope Quaternion (MAGYQ-Based Attitude Estimation with Smartphone Sensors for Indoor Pedestrian Navigation

    Directory of Open Access Journals (Sweden)

    Valérie Renaudin

    2014-12-01

    Full Text Available The dependence of proposed pedestrian navigation solutions on a dedicated infrastructure is a limiting factor to the deployment of location based services. Consequently self-contained Pedestrian Dead-Reckoning (PDR approaches are gaining interest for autonomous navigation. Even if the quality of low cost inertial sensors and magnetometers has strongly improved, processing noisy sensor signals combined with high hand dynamics remains a challenge. Estimating accurate attitude angles for achieving long term positioning accuracy is targeted in this work. A new Magnetic, Acceleration fields and GYroscope Quaternion (MAGYQ-based attitude angles estimation filter is proposed and demonstrated with handheld sensors. It benefits from a gyroscope signal modelling in the quaternion set and two new opportunistic updates: magnetic angular rate update (MARU and acceleration gradient update (AGU. MAGYQ filter performances are assessed indoors, outdoors, with dynamic and static motion conditions. The heading error, using only the inertial solution, is found to be less than 10° after 1.5 km walking. The performance is also evaluated in the positioning domain with trajectories computed following a PDR strategy.

  19. The Application of Stem Analysis Methods to Estimate Carbon Sequestration in Arboreal Shrubs from a Single Measurement of Field Plots

    Directory of Open Access Journals (Sweden)

    Peter N. Beets

    2014-05-01

    Full Text Available Repeated measurements of plots are usually made to directly determine carbon stock changes over time. However, it is sometimes only practical or feasible to inventory plots at the end of a period of interest, and stock changes need to be predicted retrospectively from supplementary information on growth rate. This situation applied to the natural stratum of post-1989 forest in New Zealand, for which carbon sequestration over Commitment Period 1 (2008–2012 of the Kyoto Protocol needed to be estimated from inventory data acquired in 2012. A pilot study was undertaken to test and refine methods that could be applied in the national inventory, utilizing plots that had been installed in eligible post-1989 natural forest in 2008. The plots had actual measurements and shrub biomass sampling to directly estimate carbon stocks in 2008. These plots were re-measured and sampled in 2012, and basal disc samples from plants growing adjacent to each plot collected to provide data to model stem annual increment in diameter and height of shrubs growing on the plot. We present the results of this test of methods, and discuss refinements to field procedures and calculation methods to be applied in the national inventory of this stratum of post-1989 forest in 2012.

  20. Phase-Based Adaptive Estimation of Magnitude-Squared Coherence Between Turbofan Internal Sensors and Far-Field Microphone Signals

    Science.gov (United States)

    Miles, Jeffrey Hilton

    2015-01-01

    A cross-power spectrum phase based adaptive technique is discussed which iteratively determines the time delay between two digitized signals that are coherent. The adaptive delay algorithm belongs to a class of algorithms that identifies a minimum of a pattern matching function. The algorithm uses a gradient technique to find the value of the adaptive delay that minimizes a cost function based in part on the slope of a linear function that fits the measured cross power spectrum phase and in part on the standard error of the curve fit. This procedure is applied to data from a Honeywell TECH977 static-engine test. Data was obtained using a combustor probe, two turbine exit probes, and far-field microphones. Signals from this instrumentation are used estimate the post-combustion residence time in the combustor. Comparison with previous studies of the post-combustion residence time validates this approach. In addition, the procedure removes the bias due to misalignment of signals in the calculation of coherence which is a first step in applying array processing methods to the magnitude squared coherence data. The procedure also provides an estimate of the cross-spectrum phase-offset.

  1. Magnetic, Acceleration Fields and Gyroscope Quaternion (MAGYQ)-based attitude estimation with smartphone sensors for indoor pedestrian navigation.

    Science.gov (United States)

    Renaudin, Valérie; Combettes, Christophe

    2014-12-02

    The dependence of proposed pedestrian navigation solutions on a dedicated infrastructure is a limiting factor to the deployment of location based services. Consequently self-contained Pedestrian Dead-Reckoning (PDR) approaches are gaining interest for autonomous navigation. Even if the quality of low cost inertial sensors and magnetometers has strongly improved, processing noisy sensor signals combined with high hand dynamics remains a challenge. Estimating accurate attitude angles for achieving long term positioning accuracy is targeted in this work. A new Magnetic, Acceleration fields and GYroscope Quaternion (MAGYQ)-based attitude angles estimation filter is proposed and demonstrated with handheld sensors. It benefits from a gyroscope signal modelling in the quaternion set and two new opportunistic updates: magnetic angular rate update (MARU) and acceleration gradient update (AGU). MAGYQ filter performances are assessed indoors, outdoors, with dynamic and static motion conditions. The heading error, using only the inertial solution, is found to be less than 10° after 1.5 km walking. The performance is also evaluated in the positioning domain with trajectories computed following a PDR strategy.

  2. Investigation of Jc-Suppressing Factors in Flat-Rolled Sr0.6K0.4Fe2As2Fe Tapes Via Microstructure Analysis

    KAUST Repository

    Zhang, Xianping

    2015-01-13

    Pnictide superconductors will be very promising for applications if wires with high critical current density Jc can allow reel-to-reel large-scale fabrication at low costs. To understand the mechanism(s) that limited Jc in flat-rolled Sr0.6K0.4Fe2As2(Sr122) tapes, microstructure analysis has been considered the most direct and efficient way. Here, we report on high-resolution microstructure imaging and analysis on Fe-sheathed flat-rolled Sr122 tapes, which have a Jc as high as 2.3 × 104 A/cm2 at 10 T and 4.2 K. The overlapping nature of the Sr122 plates was clearly observed. Transmission electron microscopy/scanning transmission electron microscopy analysis showed that, besides the cracks formed during the fabrication process, the SrO2 phase and cavities caused by the inhomogeneously dispersed Sr and K are the other important factors suppressing Jc. The wetting phase FeAs at the grain boundaries can be partially substituted by Sn in Sn-added samples. Our findings provide insights that pave the way to further enhance the critical current of the rolled 122 tapes up to the practical level.

  3. High transport Jc in stainless steel/Ag-Sn double sheathed Ba122 tapes

    Science.gov (United States)

    Gao, Zhaoshun; Togano, Kazumasa; Zhang, Yunchao; Matsumoto, Akiyoshi; Kikuchi, Akihiro; Kumakura, Hiroaki

    2017-09-01

    In this study, we report that the transport critical current density J c of Ba122 tapes can be significantly enhanced by using the harder stainless steel (SS)/Ag-Sn double sheath. A high J c value of 1.4 × 105 A cm-2 (at 4.2 K and 10 T) was achieved in SS/Ag-Sn alloyed double sheathed tapes by cold pressing. Even for as-rolled tapes, the J c exceeds the practical level of 105 A cm-2 in magnetic fields up to 10 T. More interestingly, a high J c value of 5.5 × 104 A cm-2 at 10 T was obtained by a heat treatment with a very low temperature of 550 °C. The microstructure investigations reveal that the higher core density of the Ba122 tapes with uniform deformation and better grain alignment are responsible for the superior J c -field performance.

  4. Estimation of the frequency and magnetic field dependence of the skin depth in Co-rich magnetic microwires from GMI experiments

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2016-09-01

    Full Text Available We studied giant magnetoimpedance (GMI effect in magnetically soft amorphous Co-rich microwires in the extended frequency range. From obtained experimentally dependences of the GMI ratio on magnetic field at different frequencies we estimated the penetration depth and its dependence on applied magnetic field and frequency.

  5. Measurement of transverse Jc profiles of coated conductors using a magnetic knife of permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Haenisch, J [Los Alamos National Laboratory; Mueller, F M [Los Alamos National Laboratory; Ashworth, S P [Los Alamos National Laboratory; Coulter, J Y [Los Alamos National Laboratory; Matias, Vlad [Los Alamos National Laboratory

    2008-01-01

    The transverse J{sub c} distribution in YBCO coated conductors was measured non-destructively with high resolution using a 'magnetic knife' made of permanent magnets. The method utilizes the strong depression of J{sub c} in applied magnetic fields. A narrow region of low (including zero) magnetic field, in a surrounding higher field, is moved transversely across the sample in order to reveal the critical-current density distribution. The net resolution of this device is approximately 65 {micro}m, and the J{sub c} resolution is better than 0.5%. A Fourier series inversion process was used to determine the transverse J{sub c} distribution in the sample. The J{sub c} profile was correlated with other sample properties of coated conductors prepared by pulsed laser deposition. Because of its straight-forward and inexpensive design, this J{sub c} imaging technique can be a powerful tool for quality control in coated-conductor production.

  6. Measurement Of Transverse Jc Profiles Of Coated Conductors Using A Magnetic Knife Of Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Hanisch, J [Los Alamos National Laboratory; Mueller, F M [Los Alamos National Laboratory; Ashworth, S P [Los Alamos National Laboratory; Coulter, J Y [Los Alamos National Laboratory; Matias, Vlad [Los Alamos National Laboratory

    2008-01-01

    The transverse J{sub c} distribution in YBCO coated conductors was measured nondestructively with high resolution using a 'magnetic knife' made of permanent magnets. The method utilizes the strong depression of J{sub c} in applied magnetic fields. A narrow region of low (including zero) magnetic field, in a surrounding higher field, is moved transversely across the sample in order to reveal the critical-current density distribution. The net resolution of this device is approximately 65 {mu}m, and the J{sub c} resolution is better than 0.5%. A Fourier series inversion process was used to determine the transverse J{sub c} distribution in the sample. The J{sub c} profile was correlated with other sample properties of coated conductors prepared by pulsed laser deposition. Because of its straight-forward and inexpensive design, this J{sub c} imaging technique can be a powerful tool for quality control in coated-conductor production.

  7. MR image segmentation and bias field estimation based on coherent local intensity clustering with total variation regularization.

    Science.gov (United States)

    Tu, Xiaoguang; Gao, Jingjing; Zhu, Chongjing; Cheng, Jie-Zhi; Ma, Zheng; Dai, Xin; Xie, Mei

    2016-12-01

    Though numerous segmentation algorithms have been proposed to segment brain tissue from magnetic resonance (MR) images, few of them consider combining the tissue segmentation and bias field correction into a unified framework while simultaneously removing the noise. In this paper, we present a new unified MR image segmentation algorithm whereby tissue segmentation, bias correction and noise reduction are integrated within the same energy model. Our method is presented by a total variation term introduced to the coherent local intensity clustering criterion function. To solve the nonconvex problem with respect to membership functions, we add auxiliary variables in the energy function such as Chambolle's fast dual projection method can be used and the optimal segmentation and bias field estimation can be achieved simultaneously throughout the reciprocal iteration. Experimental results show that the proposed method has a salient advantage over the other three baseline methods on either tissue segmentation or bias correction, and the noise is significantly reduced via its applications on highly noise-corrupted images. Moreover, benefiting from the fast convergence of the proposed solution, our method is less time-consuming and robust to parameter setting.

  8. The iron $K_\\alpha$ lines as a tool for magnetic field estimations in non-flat accretion flows

    CERN Document Server

    Zakharov, A F; Bao, Y

    2004-01-01

    Observations of AGNs and microquasars by ASCA, RXTE, Chandra and XMM-Newton indicate the existence of broad X-ray emission lines of ionized heavy elements in their spectra. Such spectral lines were discovered also in X-ray spectra of neutron stars and X-ray afterglows of GRBs. Recently, Zakharov et al. (MNRAS, 2003, 342, 1325) described a procedure to estimate an upper limit of the magnetic fields in regions from which X-ray photons are emitted. The authors simulated typical profiles of the iron $K_\\alpha$ line in the presence of magnetic field and compared them with observational data in the framework of the widely accepted accretion disk model. Here we further consider typical Zeeman splitting in the framework of a model of non-flat accretion flows, which is a generalization of previous consideration into non-equatorial plane motion of particles emitting X-ray photons. Using perspective facilities of space borne instruments (e.g. Constellation-X mission) a better resolution of the blue peak structure of iro...

  9. Estimation of Emissions from Sugarcane Field Burning in Thailand Using Bottom-Up Country-Specific Activity Data

    Directory of Open Access Journals (Sweden)

    Wilaiwan Sornpoon

    2014-09-01

    Full Text Available Open burning in sugarcane fields is recognized as a major source of air pollution. However, the assessment of its emission intensity in many regions of the world still lacks information, especially regarding country-specific activity data including biomass fuel load and combustion factor. A site survey was conducted covering 13 sugarcane plantations subject to different farm management practices and climatic conditions. The results showed that pre-harvest and post-harvest burnings are the two main practices followed in Thailand. In 2012, the total production of sugarcane biomass fuel, i.e., dead, dry and fresh leaves, amounted to 10.15 million tonnes, which is equivalent to a fuel density of 0.79 kg∙m−2. The average combustion factor for the pre-harvest and post-harvest burning systems was determined to be 0.64 and 0.83, respectively. Emissions from sugarcane field burning were estimated using the bottom-up country-specific values from the site survey of this study and the results compared with those obtained using default values from the 2006 IPCC Guidelines. The comparison showed that the use of default values lead to underestimating the overall emissions by up to 30% as emissions from post-harvest burning are not accounted for, but it is the second most common practice followed in Thailand.

  10. Optical Flow Applied to Time-Lapse Image Series to Estimate Glacier Motion in the Southern Patagonia Ice Field

    Science.gov (United States)

    Lannutti, E.; Lenzano, M. G.; Toth, C.; Lenzano, L.; Rivera, A.

    2016-06-01

    In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically complex and hard to access areas, deploying time-lapse imaging sensors, optical flow may provide an efficient solution at good spatial and temporal resolution to describe mass motion. Several studies in computer vision and image processing community have used this method to detect large displacements. Therefore, we carried out a test of the proposed Large Displacement Optical Flow method at the Viedma Glacier, located at South Patagonia Icefield, Argentina. We collected monoscopic terrestrial time-lapse imagery, acquired by a calibrated camera at every 24 hour from April 2014 until April 2015. A filter based on temporal correlation and RGB color discretization between the images was applied to minimize errors related to changes in lighting, shadows, clouds and snow. This selection allowed discarding images that do not follow a sequence of similarity. Our results show a flow field in the direction of the glacier movement with acceleration in the terminus. We analyzed the errors between image pairs, and the matching generally appears to be adequate, although some areas show random gross errors related to the presence of changes in lighting. The proposed technique allowed the determination of glacier motion during one year, providing accurate and reliable motion data for subsequent analysis.

  11. Practical estimates of field-saturated hydraulic conductivity of bedrock outcrops using a modified bottomless bucket method

    Science.gov (United States)

    Mirus, Benjamin B.; Perkins, Kim S.

    2012-01-01

    The bottomless bucket (BB) approach (Nimmo et al., 2009a) is a cost-effective method for rapidly characterizing field-saturated hydraulic conductivity Kfs of soils and alluvial deposits. This practical approach is of particular value for quantifying infiltration rates in remote areas with limited accessibility. A similar approach for bedrock outcrops is also of great value for improving quantitative understanding of infiltration and recharge in rugged terrain. We develop a simple modification to the BB method for application to bedrock outcrops, which uses a non-toxic, quick-drying silicone gel to seal the BB to the bedrock. These modifications to the field method require only minor changes to the analytical solution for calculating Kfs on soils. We investigate the reproducibility of the method with laboratory experiments on a previously studied calcarenite rock and conduct a sensitivity analysis to quantify uncertainty in our predictions. We apply the BB method on both bedrock and soil for sites on Pahute Mesa, which is located in a remote area of the Nevada National Security Site. The bedrock BB tests may require monitoring over several hours to days, depending on infiltration rates, which necessitates a cover to prevent evaporative losses. Our field and laboratory results compare well to Kfs values inferred from independent reports, which suggests the modified BB method can provide useful estimates and facilitate simple hypothesis testing. The ease with which the bedrock BB method can be deployed should facilitate more rapid in-situ data collection than is possible with alternative methods for quantitative characterization of infiltration into bedrock.

  12. Estimation of the Aral Sea state predictability based on the open data sources and the unique field observations

    Science.gov (United States)

    Izhitskiy, Alexander; Ayzel, Georgy; Zavialov, Peter; Kurbaniyazov, Abilgazi

    2016-04-01

    The Aral Sea, formerly one of the four largest lakes in the world, has lost over 90% of its volume during the dramatical dessication mainly caused by the severe alteration of water budget of the basin. Shrinkage of the Aral Sea resulted in profound changes of the lake's ecosystem, that became a subject for a number of publications based on a wide range of methods such as field observations, remote sensing data analysis and numerical modeling. However, by the early 21th century, the number of field studies decreased significantly due to almost complete cessation of navigation and displacement of the Aral's shoreline far away from roads and other infrastructure. Thus, only a small amount of field data (salinity, temperature, etc.) for different regions of the lake is available for the last two decades. On the other hand, a set of the open data sources (sea level variability, atmospheric reanalysis) were developed for the region. The main idea of the presented study is to estimate the possibility of prediction of the Aral Sea state using coupled system of basic geoanalysis tools, numerical modeling of hydrological cycle (both for sea and land-surface interactions with atmosphere) and state-of-art machine learning techniques. Firstly, available in situ data, obtained in the Aral Sea by Shirshov Institute and other researchers, are concerned as the "base points of state" for each year within the studied period. Secondly, consistent patterns in the interannual variability of all other available parameters, taken from the open data sources and numerical modeling predictions, are founded out. As a result, such an approach allows predicting the future state of sea basing on the possible climatic scenario.

  13. Magnetic field estimates from the synchrotron X-ray shell of 30 Dor C, the first TeV superbubble

    Science.gov (United States)

    Kavanagh, P.; Vink, J.; Sasake, M.; Maggi, P.; Haberl, F.; Filipovic, M.

    2016-06-01

    Superbubbles are powered by the stellar winds and subsequent supernovae of a massive stellar population and are often argued as strong candidates for Galactic cosmic-ray acceleration sites. The recent detection of TeV gamma-rays from 30 Dor C in the Large Magellanic Cloud by the High Energy Stereoscopic System (H.E.S.S.) has shown that superbubbles can and do accelerate particles up to very high cosmic-ray energies, and are a new and important source class in TeV astronomy. However, the dominant production mechanism (i.e., hadronic or leptonic) is still unclear. The answer to this question is locked in the unique synchrotron X-ray shell of 30 Dor C. The widths of the synchrotron emission regions are directly related to the magnetic field, which is a crucial parameter assessing dominant gamma-ray emission mechanism. In this talk we will present a study of the synchrotron emission region widths in 30 Dor C using several hundred ks of archival X-ray data from XMM-Newton. We constructed radial emission profiles from various regions of the synchrotron shell, fitted emission models to determine the widths, and derived B-field values in the downstream regions using appropriate models. The resulting low B-field estimates, of the order of a few micro G, favour a leptonic origin for the gamma-ray emission. Hadronic cosmic rays are likely to be accelerated as well, but the low density inside the bubble suppresses their emissivity.

  14. JC 型转矩转速传感器输出信号的处理方法%Processing Method of the Output Signal of JC Torque and Rotary Speed Sensor

    Institute of Scientific and Technical Information of China (English)

    张娇; 金鹏

    2014-01-01

    为从JC型传感器获得较准确的转矩转速信号,根据其工作原理寻找合理的信号处理方法,获得电信号和转矩转速信号的转换。采用PIC18F458单片机,通过对传感器输出两路正弦电信号进行放大、滤波及整形处理后并获得两个同频信号的方波,应用RS触发电路将两路正弦信号的相位差变为触发器输出脉冲的宽度。通过脉冲计数法测量方波信号的频率获得转速,利用等精度法检测RS触发器的输出脉冲宽度求取转矩,同时运用滑动平均提高信号的准确性和稳定性。实验结果表明,该方法可有效地测量转矩转速信号,且在电动汽车和机械动力装置仪器中具有实用价值。%A reasonable signal processing method for the conversion between electrical signal and torque speed signal is proposed according to the working principle of JC sensor to obtain more accurate torque and speed signal .In this experiment, PIC18F458 microcontroller is used to magnify , filter, and shape two sinusoidal electrical output signals of the JC sensor to gain two same frequency square waves , and RS flip-flop to convert the phase difference of the two sinusoidal signal into the pulse width the flip-flop's output .The pulse count method is adopted to measure the square wave signal's frequency to obtain speed , the equal precision measuring method to detect the output pulse width of the RS flip-flop to obtain torque , and the moving average is also used to improve accuracy and stability of the signal .The experimental results show that the proposed method can effectively measure the torque and rotary speed, and has practical value on the application in electric vehicles and mechanical power plant instrumentation .

  15. JC7.3tex赛络纱的纺制及质量综合评价%Spinning of JC 7.3 tex Siro Spun Yarn and Its Quality Evaluation

    Institute of Scientific and Technical Information of China (English)

    李向红; 刘阳; 蒋书侠

    2012-01-01

    探讨JC 7.3 tex赛络纱的生产工艺及成纱质量的综合评价方法.通过正确选配原料,前纺工序合理配置工艺参数,细纱工序采用赛络纺技术,并对喇叭口间距和细纱捻系数进行试验优选,同时对试验结果采用模糊决策分析法进行综合评定,最终优选出喇叭口间距2.5 mm,细纱捻系数393的纺纱工艺.认为,通过合理配置并优化有关工艺,纺制出的特细号赛络纱可以满足高档织物对喷气用纱的质量要求;在多指标试验方案中,运用加权Borda数法对纱线性能进行模糊决策分析,有助于根据纺纱用途优选出较优方案.%Spinning processing of JC 7.3 tex siro spun yarn and its quality evaluation method were discussed. Raw material was selected correctly,processing parameter in spinning was selected rationally,siro spinning technology was a-dopted,bell space and yam twist factor were optimized. Fuzzy decision analysis was adopted to assess the test result comprehensively. Finally the best bell space was selected as 2. 5 mm and yam twist factor as 393. It is considered that the spun super fine siro yarn quality can reach the demands of high grade fabric to air jet yarn according to optimizing related processing. In index test case.it is helpful to optimize the better case through applying weighed Borda method to analyzing yarn property.

  16. Morfologia da flor, fruto e plântula de Victoria amazonica (Poepp. J.C. Sowerby (Nymphaeaceae Morphology of flower, fruit and seedling of Victoria amazonica (Poepp. J.C. Sowerby (Nymphaeaceae

    Directory of Open Access Journals (Sweden)

    Sônia Maciel da Rosa-Osman

    2011-03-01

    Full Text Available Victoria amazonica (Poepp. J.C. Sowerby é uma hidrófita que ocorre nas várzeas de águas brancas e igapós da Bacia Amazônica e na Bacia do rio Paraguai. A morfologia da flor, fruto e plântula/"tirodendro" é objeto do presente trabalho. O material botânico foi coletado em Parintins e Manaus, estado do Amazonas, Brasil. A análise morfológica foi feita em material fresco e fixado em FAA 50. O desenvolvimento das plântulas foi realizado no escuro em frascos com água com teor reduzido de oxigênio. As flores possuem pedicelo longo e são hemicíclicas, diclamídeas, monoclinas e com antese vespertina. Os frutos são carnosos, indeiscentes, com pseudossincarpia. As sementes apresentam arilo que atua na dispersão pela água. As plântulas se desenvolvem em condições de hipoxia e apresentam um cotilédone exposto acicular. O "tirodendro" apresenta eofilos com heterofilia. As flores apresentam caracteres morfológicos básicos da família, a definição do tipo de fruto exige estudo ontogenético e a heterofilia é um caráter típico de plântulas/"tirodendros"de Nymphaeaceae.Victoria amazonica (Poepp. J.C. Sowerby is a hydrophyte that occurs in the white water leas and igapos of the Amazonian and Paraguay Basin. The flower, fruit and seedling/"tirodendro" morphology is the object of the present work. The botanical material was collected at Parintins and Manaus, Amazonian state, Brazil. The morphological analysis was made in both fresh and fixed material. The seedling development was accomplished in flasks with water containing little oxygen and maintained in the darkness. Flowers present long pedicel and they are hemicyclic, dichlamydeous, bisexual with vespertine anthesis. Fruits are fleshy, indehiscent with pseudo-syncarpy. Seeds present aril that acts in the water dispersion. Seedlings grow in hypoxy conditions and they present an acicular and exposed cotyledon. The "tirodendro" stage presents eophylls with heterophylly. Flowers

  17. Mean field J{sub C} estimation for levitation device simulations in the bean model using permanent magnets and YBCO superconducting blocks

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Marcelo Azevedo; Andrade Junior, Rubens de [Universidade Federal, Rio de Janeiro, RJ (Brazil). Dept. de Eletrotecnica. Lab. de Aplicacoes de Supercondutores (LASUP); Costa, Giancarlo Cordeiro da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Lab. de Metodos Computacionais em Engenharia; Pereira, Agnaldo Souza; Nicolsky, Roberto [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica

    2002-09-01

    This work presents a mean field estimation of J{sub C} as a bulk characteristic of YBCO blocks. That average J{sub C} allows a good fitting of the finite-element-method simulation of the levitation forces to experimental results. That agreement is quite enough for levitation requirements of device projects, at short gaps and zero field cooling process, within the Bean model. The physical characterization for that estimation was made measuring the interaction force between the PM and one YBCO block in 1-D and mapping the trapped magnetic field in those blocks in 2-D. (author)

  18. Estimating Attitude, Trajectory, and Gyro Biases in an Extended Kalman Filter using Earth Magnetic Field Data from the Rossi X-Ray Timing Explorer

    Science.gov (United States)

    Deutschmann, Julie; Bar-Itzhack, Itzhack

    1997-01-01

    Traditionally satellite attitude and trajectory have been estimated with completely separate systems, using different measurement data. The estimation of both trajectory and attitude for low earth orbit satellites has been successfully demonstrated in ground software using magnetometer and gyroscope data. Since the earth's magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both the spacecraft trajectory and attitude errors. Therefore, these errors can be used to estimate both trajectory and attitude. This work further tests the single augmented Extended Kalman Filter (EKF) which simultaneously and autonomously estimates spacecraft trajectory and attitude with data from the Rossi X-Ray Timing Explorer (RXTE) magnetometer and gyro-measured body rates. In addition, gyro biases are added to the state and the filter's ability to estimate them is presented.

  19. Automated Near-Field Displacement Estimates from Mobile Laser Scanning - Case Study for the Mw 6.0 August 24, 2014 Napa Earthquake

    Science.gov (United States)

    Glennie, C. L.; Kusari, A.; Brooks, B. A.; Ericksen, T.

    2016-12-01

    Quantification of near-field displacements can greatly enhance shallow fault physical investigations. However, to date, established remote sensing techniques such as InSAR and GNSS have failed to recover precise near-field displacements at the scale and resolution required for detailed near-field investigations. To overcome these limitations, we present an automated methodology to extract planar primitives from temporally spaced mobile laser scanning (MLS) point clouds, and then use common planar features in each data set coupled with a least-squares registration approach that enables a precise estimation of near-field displacement. To validate the utility of this method, we present a case study using MLS to measure afterslip immediately following the Mw 6.0 August 24, 2014 Napa earthquake, and show that the MLS estimates of displacement agree with independent alinement array estimates of afterslip at the sub-centimeter level.

  20. Comparison of Precision of Biomass Estimates in Regional Field Sample Surveys and Airborne LiDAR-Assisted Surveys in Hedmark County, Norway

    Science.gov (United States)

    Naesset, Erik; Gobakken, Terje; Bollandsas, Ole Martin; Gregoire, Timothy G.; Nelson, Ross; Stahl, Goeran

    2013-01-01

    Airborne scanning LiDAR (Light Detection and Ranging) has emerged as a promising tool to provide auxiliary data for sample surveys aiming at estimation of above-ground tree biomass (AGB), with potential applications in REDD forest monitoring. For larger geographical regions such as counties, states or nations, it is not feasible to collect airborne LiDAR data continuously ("wall-to-wall") over the entire area of interest. Two-stage cluster survey designs have therefore been demonstrated by which LiDAR data are collected along selected individual flight-lines treated as clusters and with ground plots sampled along these LiDAR swaths. Recently, analytical AGB estimators and associated variance estimators that quantify the sampling variability have been proposed. Empirical studies employing these estimators have shown a seemingly equal or even larger uncertainty of the AGB estimates obtained with extensive use of LiDAR data to support the estimation as compared to pure field-based estimates employing estimators appropriate under simple random sampling (SRS). However, comparison of uncertainty estimates under SRS and sophisticated two-stage designs is complicated by large differences in the designs and assumptions. In this study, probability-based principles to estimation and inference were followed. We assumed designs of a field sample and a LiDAR-assisted survey of Hedmark County (HC) (27,390 km2), Norway, considered to be more comparable than those assumed in previous studies. The field sample consisted of 659 systematically distributed National Forest Inventory (NFI) plots and the airborne scanning LiDAR data were collected along 53 parallel flight-lines flown over the NFI plots. We compared AGB estimates based on the field survey only assuming SRS against corresponding estimates assuming two-phase (double) sampling with LiDAR and employing model-assisted estimators. We also compared AGB estimates based on the field survey only assuming two-stage sampling (the NFI

  1. Out-of-field activity in the estimation of mean lung attenuation coefficient in PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Berker, Yannick, E-mail: yberker@ukaachen.de [Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen (Germany); Salomon, André [X-Ray Imaging Systems, Philips Research, Eindhoven (Netherlands); Kiessling, Fabian [Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen (Germany); Schulz, Volkmar [Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen (Germany); Philips Technologie GmbH Innovative Technologies, Research Laboratories, Aachen (Germany)

    2014-01-11

    In clinical PET/MR, photon attenuation is a source of potentially severe image artifacts. Correction approaches include those based on MR image segmentation, in which image voxels are classified and assigned predefined attenuation coefficients to obtain an attenuation map. In whole-body imaging, however, mean lung attenuation coefficients (LAC) can vary by a factor of 2, and the choice of inappropriate mean LAC can have significant impact on PET quantification. Previously, we proposed a method combining MR image segmentation, tissue classification and Maximum Likelihood reconstruction of Attenuation and Activity (MLAA) to estimate mean LAC values. In this work, we quantify the influence of out-of-field (OOF) accidental coincidences when acquiring data in a single bed position. We therefore carried out GATE simulations of realistic, whole-body activity and attenuation distributions derived from data of three patients. A bias of 15% was found and significantly reduced by removing OOF accidentals from our data, suggesting that OOF accidentals are the major contributor to the bias. We found approximately equal contributions from OOF scatter and OOF randoms, and present results after correction of the bias by rescaling of results. Results using temporal subsets suggest that 30-second acquisitions may be sufficient for estimation mean LAC with less than 5% uncertainty if mean bias can be corrected for. -- Highlights: • Variability of lung attenuation complicates PET attenuation correction in PET/MR. • Maximum Likelihood Reconstruction of Attenuation and Activity combined with MR image segmentation. • GATE simulations of PET acquisitions in a realistic scanner model. • Bias in full-body simulations explained by accidentals from outside the FOV.

  2. Dynamic variability of the heading-flowering stages of single rice in China based on field observations and NDVI estimations.

    Science.gov (United States)

    Zhang, Zhao; Song, Xiao; Chen, Yi; Wang, Pin; Wei, Xing; Tao, Fulu

    2015-05-01

    Although many studies have indicated the consistent impact of warming on the natural ecosystem (e.g., an early flowering and prolonged growing period), our knowledge of the impacts on agricultural systems is still poorly understood. In this study, spatiotemporal variability of the heading-flowering stages of single rice was detected and compared at three different scales using field-based methods (FBMs) and satellite-based methods (SBMs). The heading-flowering stages from 2000 to 2009 with a spatial resolution of 1 km were extracted from the SPOT/VGT NDVI time series data using the Savizky-Golay filtering method in the areas in China dominated by single rice of Northeast China (NE), the middle-lower Yangtze River Valley (YZ), the Sichuan Basin (SC), and the Yunnan-Guizhou Plateau (YG). We found that approximately 52.6 and 76.3 % of the estimated heading-flowering stages by a SBM were within ±5 and ±10 days estimation error (a root mean square error (RMSE) of 8.76 days) when compared with those determined by a FBM. Both the FBM data and the SBM data had indicated a similar spatial pattern, with the earliest annual average heading-flowering stages in SC, followed by YG, NE, and YZ, which were inconsistent with the patterns reported in natural ecosystems. Moreover, diverse temporal trends were also detected in the four regions due to different climate conditions and agronomic factors such as cultivar shifts. Nevertheless, there were no significant differences (p > 0.05) between the FBM and the SBM in both the regional average value of the phenological stages and the trends, implying the consistency and rationality of the SBM at three scales.

  3. Estimation of Land Surface Parameters by LDAS-UT: Model Development and Validation on Tanashi Field Experiment

    Science.gov (United States)

    Lu, H.; Koike, T.; Yang, K.; Li, X.; Graf, T.; Boussetta, S.; Tsutsui, H.; Kuria, D. N.

    2007-12-01

    The estimation of soil moisture and surface energy fluxes at various temporal and spatial scales remains to be an outstanding problem in hydrologic and meteorological researches. Remote sensed data retrieval algorithms, land surface models and data assimilation systems are highly expected to provide a solution to this problem. But the parameters required by those algorithms and systems, such as the soil texture, porosity, roughness parameters and so on, are highly variable or unavailable. In this study, a land data assimilation system (LDAS- UT) is employed to inversely estimate the optimal values of those land surface parameters with meteorological forcing data and remote sensed data. And a field experiment is designed to provide a well-controlled data set for the system validation. The Tanashi experiment has been in operation since November, 2006 in the farm of the University of Tokyo. Continuous ground measurements of meteorological variables, soil moisture and temperature profiles and vegetation status have been taken over a plot, in which winter wheat was planted. At the same time, the ground based microwave radiometers (GBMR) are employed to provide accurate field measurements of brightness temperature up-welling from the plot, at the frequencies of 6.925, 10.65, 18.7, 23.8, 36.5 and 89 GHz. The LDAS_UT is then run with using data obtained from this experiment to retrieval parameters for two periods. One is the period from December 2006 to February 2007, the germination period of winter wheat, and during which the vegetation effects are small. The second period is from April to May 2007, during which the winter wheat was developing rapidly. The optimize parameters were compared with the in situ observed ¡®real' ones. It found that, for the first period, the retrieved parameters are close to the ¡®real' values, while for the second period, the gap between the retrieved parameters and the ¡®real' values are much bigger. The difference between the

  4. TU-F-CAMPUS-T-05: Replacement Computational Phantoms to Estimate Dose in Out-Of-Field Organs and Tissues

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, K [Oregon State University, Corvallis, Oregon (United States); Oregon Health and Science University, Portland, Oregon (United States); Tannous, J; Nabha, R; Feghali, J; Ayoub, Z; Jalbout, W; Youssef, B [American University of Beirut Medical Center, Beirut (Lebanon); Taddei, P [American University of Beirut Medical Center, Beirut (Lebanon); The University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: To estimate the absorbed dose in organs and tissues at risk for radiogenic cancer for children receiving photon radiotherapy for localized brain tumors (LBTs) by supplementing their missing body anatomies with those of replacement computational phantoms. Applied beyond the extent of the RT Images collected by computed tomography simulation, these phantoms included RT Image and RT Structure Set objects that encompassed sufficient extents and contours for dosimetric calculations. Method: Nine children, aged 2 to 14 years, who received three-dimensional conformal radiotherapy for low-grade LBTs, were randomly selected for this study under Institutional-Review-Board protocol. Because the extents of their RT Images were cranial only, they were matched for size and sex with patients from a previous study with larger extents and for whom contours of organs at risk for radiogenic cancer had already been delineated. Rigid fusion was performed between the patients’ data and those of the replacement computational phantoms using commercial software. In-field dose was calculated with a clinically-commissioned treatment planning system, and out-of-field dose was estimated with an analytical model. Results: Averaged over all nine children and normalized for a therapeutic dose of 54 Gy prescribed to the PTV, where the PTV is the GTV, the highest mean organ doses were 3.27, 2.41, 1.07, 1.02, 0.24, and 0.24 Gy in the non-tumor remainder, red bone marrow, thyroid, skin, breasts, and lungs, respectively. The mean organ doses ranged by a factor of 3 between the smallest and largest children. Conclusion: For children receiving photon radiotherapy for LBTs, we found their doses in organs at risk for second cancer to be non-negligible, especially in the non-tumor remainder, red bone marrow, thyroid, skin, breasts, and lungs. This study demonstrated the feasibility for patient dosimetry studies to augment missing patient anatomy by applying size- and sex-matched replacement

  5. Emulating the visual receptive-field properties of MST neurons with a template model of heading estimation

    Science.gov (United States)

    Perrone, J. A.; Stone, L. S.

    1998-01-01

    We have proposed previously a computational neural-network model by which the complex patterns of retinal image motion generated during locomotion (optic flow) can be processed by specialized detectors acting as templates for specific instances of self-motion. The detectors in this template model respond to global optic flow by sampling image motion over a large portion of the visual field through networks of local motion sensors with properties similar to those of neurons found in the middle temporal (MT) area of primate extrastriate visual cortex. These detectors, arranged within cortical-like maps, were designed to extract self-translation (heading) and self-rotation, as well as the scene layout (relative distances) ahead of a moving observer. We then postulated that heading from optic flow is directly encoded by individual neurons acting as heading detectors within the medial superior temporal (MST) area. Others have questioned whether individual MST neurons can perform this function because some of their receptive-field properties seem inconsistent with this role. To resolve this issue, we systematically compared MST responses with those of detectors from two different configurations of the model under matched stimulus conditions. We found that the characteristic physiological properties of MST neurons can be explained by the template model. We conclude that MST neurons are well suited to support self-motion estimation via a direct encoding of heading and that the template model provides an explicit set of testable hypotheses that can guide future exploration of MST and adjacent areas within the superior temporal sulcus.

  6. Using the Surface Renewal Technique to Estimate CO2 Exchange from a Rice Field to the Atmosphere

    Science.gov (United States)

    Suvocarev, K.; Reba, M. L.; Runkle, B.

    2015-12-01

    Measuring CO2 emissions as surface fluxes is crucial for climate change predictions. One major set of techniques to measure surface fluxes is through continuous micrometeorological observations over different landscapes. Recent approaches of the surface renewal method (SR) are becoming important for their capacity to independently measure sensible (H) and latent heat (LE) fluxes while avoiding some of the shortcomings of the eddy covariance method (EC). Unlike EC, SR avoids orientation limitations, leveling requirements and instrumentation separation and shadowing issues. The main advantage of SR over EC method is in its applicability in both roughness and inertial sub-layers. Therefore, SR measurements can be planned in cases where fetch requirements are not adequate for EC application. We applied the recent approach as suggested by Castellvi et al. (2008) over two months (May to July, 2015) of high-frequency data collected by EC equipment from a rice field in Arkansas. The main goal was to extend this SR application to CO2 fluxes (Fc) over agricultural fields. The results show high correlation between EC and SR fluxes (H, LE and Fc) when they are compared for all atmospheric stability conditions (R2 > 0.75). Some overestimation is observed for SR with respect to EC fluxes, similar to the findings of Castellvi et al. (2008) for rangeland grass. For all the data, SR analysis results were about 11%, 18% and 17% higher than the EC results for H, LE and Fc, respectively. These higher flux estimates resulted in better energy balance closure. The root mean square error for Fc was 6.55 μmol m-2 s-1. The observed overestimation will be addressed in the future by using additional methods for the turbulent fluxes quantification.

  7. An Estimation of Hybrid Quantum Mechanical Molecular Mechanical Polarization Energies for Small Molecules Using Polarizable Force-Field Approaches.

    Science.gov (United States)

    Huang, Jing; Mei, Ye; König, Gerhard; Simmonett, Andrew C; Pickard, Frank C; Wu, Qin; Wang, Lee-Ping; MacKerell, Alexander D; Brooks, Bernard R; Shao, Yihan

    2017-02-14

    In this work, we report two polarizable molecular mechanics (polMM) force field models for estimating the polarization energy in hybrid quantum mechanical molecular mechanical (QM/MM) calculations. These two models, named the potential of atomic charges (PAC) and potential of atomic dipoles (PAD), are formulated from the ab initio quantum mechanical (QM) response kernels for the prediction of the QM density response to an external molecular mechanical (MM) environment (as described by external point charges). The PAC model is similar to fluctuating charge (FQ) models because the energy depends on external electrostatic potential values at QM atomic sites; the PAD energy depends on external electrostatic field values at QM atomic sites, resembling induced dipole (ID) models. To demonstrate their uses, we apply the PAC and PAD models to 12 small molecules, which are solvated by TIP3P water. The PAC model reproduces the QM/MM polarization energy with a R(2) value of 0.71 for aniline (in 10,000 TIP3P water configurations) and 0.87 or higher for other 11 solute molecules, while the PAD model has a much better performance with R(2) values of 0.98 or higher. The PAC model reproduces reference QM/MM hydration free energies for 12 solute molecules with a RMSD of 0.59 kcal/mol. The PAD model is even more accurate, with a much smaller RMSD of 0.12 kcal/mol, with respect to the reference. This suggests that polarization effects, including both local charge distortion and intramolecular charge transfer, can be well captured by induced dipole type models with proper parametrization.

  8. Rice Crop Field Monitoring System with Radio Controlled Helicopter Based Near Infrared Cameras Through Nitrogen Content Estimation and Its Distribution Monitoring

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-03-01

    Full Text Available Rice crop field monitoring system with radio controlled helicopter based near infrared cameras is proposed together with nitrogen content estimation method for monitoring its distribution in the field in concern. Through experiments at the Saga Prefectural Agricultural Research Institute: SPARI, it is found that the proposed system works well for monitoring nitrogen content in the rice crop which indicates quality of the rice crop and its distribution in the field in concern. Therefore, it becomes available to maintain the rice crop fields in terms of quality control.

  9. In Vivo siRNA Delivery Using JC Virus-like Particles Decreases the Expression of RANKL in Rats

    Directory of Open Access Journals (Sweden)

    Daniel B Hoffmann

    2016-01-01

    Full Text Available Bone remodeling requires a precise balance between formation and resorption. This complex process involves numerous factors that orchestrate a multitude of biochemical events. Among these factors are hormones, growth factors, vitamins, cytokines, and, most notably, osteoprotegerin (OPG and the receptor activator for nuclear factor-kappaB ligand (RANKL. Inflammatory cytokines play a major role in shifting the RANKL/OPG balance toward excessive RANKL, resulting in osteoclastogenesis, which in turn initiates bone resorption, which is frequently associated with osteoporosis. Rebalancing RANKL/OPG levels may be achieved through either upregulation of OPG or through transient silencing of RANKL by means of RNA interference. Here, we describe the utilization of a viral capsid-based delivery system for in vivo and in vitro RNAi using synthetic small interfering RNA (siRNA molecules in rat osteoblasts. Polyoma JC virus-derived virus-like particles are capable of delivering siRNAs to target RANKL in osteoblast cells both in vitro and in a rat in vivo system. Expression levels were monitored using quantitative real-time polymerase reaction and enzyme-linked immunosorbent assay after single and repeated injections over a 14-day period. Our data indicate that this is an efficient and safe route for in vivo delivery of gene modulatory tools to study important molecular factors in a rat osteoporosis model.

  10. Detection of the archetypal regulatory region of JC virus from the tonsil tissue of patients with tonsillitis and tonsilar hypertrophy.

    Science.gov (United States)

    Kato, Atsushi; Kitamura, Tadaichi; Takasaka, Tomokazu; Tominaga, Takashi; Ishikawa, Akira; Zheng, Huai-Ying; Yogo, Yoshiaki

    2004-08-01

    The regulatory regions of JC virus (JCV) DNAs in the brain of patients with progressive multifocal leukoencephalopathy (PML) (designated as PML-type regulatory regions) are hypervariable, whereas those in the urine and renal tissue of individuals without PML have the same basic structure, designated as the archetype. It is thought that JCV strains with the archetypal regulatory region circulate in the human population. Nevertheless, Monaco et al (J Virol 70: 7004-7012, 1996) reported that PML-type regulatory regions occur in human tonsil tissue. The purpose of this study is to confirm their findings. Using nested polymerase chain reaction (PCR), the authors detected the regulatory region of JCV DNA in the tonsil tissue from 14 (44%) of 32 donors with tonsillitis and tonsilar hypertrophy. Sequencing of the detected regulatory regions indicated that they were identical with the archetypal regulatory regions detected previously or, in a few cases, slightly deviated from the archetype. This finding suggests not only that tonsil tissue is the potential site of initial JCV infection but also that archetypal JCV strains circulate in the human population.

  11. Changes in JC virus-specific T cell responses during natalizumab treatment and in natalizumab-associated progressive multifocal leukoencephalopathy.

    Directory of Open Access Journals (Sweden)

    Molly R Perkins

    Full Text Available Progressive multifocal leukoencephalopathy (PML induced by JC virus (JCV is a risk for natalizumab-treated multiple sclerosis (MS patients. Here we characterize the JCV-specific T cell responses in healthy donors and natalizumab-treated MS patients to reveal functional differences that may account for the development of natalizumab-associated PML. CD4 and CD8 T cell responses specific for all JCV proteins were readily identified in MS patients and healthy volunteers. The magnitude and quality of responses to JCV and cytomegalovirus (CMV did not change from baseline through several months of natalizumab therapy. However, the frequency of T cells producing IL-10 upon mitogenic stimulation transiently increased after the first dose. In addition, MS patients with natalizumab-associated PML were distinguished from all other subjects in that they either had no detectable JCV-specific T cell response or had JCV-specific CD4 T cell responses uniquely dominated by IL-10 production. Additionally, IL-10 levels were higher in the CSF of individuals with recently diagnosed PML. Thus, natalizumab-treated MS patients with PML have absent or aberrant JCV-specific T cell responses compared with non-PML patients, and changes in T cell-mediated control of JCV replication may be a risk factor for developing PML. Our data suggest further approaches to improved monitoring, treatment and prevention of PML in natalizumab-treated patients.

  12. Stress field estimation based on focal mechanisms and back projected imaging in the Eastern Llanos Basin (Colombia)

    Science.gov (United States)

    Gómez-Alba, Sebastián; Fajardo-Zarate, Carlos Eduardo; Vargas, Carlos Alberto

    2016-11-01

    At least 156 earthquakes (Mw 2.8-4.4) were detected in Puerto Gaitán, Colombia (Eastern Llanos Basin) between April 2013 and December 2014. Out of context, this figure is not surprising. However, from its inception in 1993, the Colombian National Seismological Network (CNSN) found no evidence of significant seismic events in this region. In this study, we used CNSN data to model the rupture front and orientation of the highest-energy events. For these earthquakes, we relied on a joint inversion method to estimate focal mechanisms and, in turn, determine the area's fault trends and stress tensor. While the stress tensor defines maximum stress with normal tendency, focal mechanisms generally represent normal faults with NW orientation, an orientation which lines up with the tracking rupture achieved via Back Projection Imaging for the study area. We ought to bear in mind that this anomalous earthquake activity has taken place within oil fields. In short, the present paper argues that, based on the spatiotemporal distribution of seismic events, hydrocarbon operations may induce the study area's seismicity.

  13. First-order estimate of the Canary Islands plate-scale stress field: Implications for volcanic hazard assessment

    Science.gov (United States)

    Geyer, A.; Martí, J.; Villaseñor, A.

    2016-06-01

    In volcanic areas, the existing stress field is a key parameter controlling magma generation, location and geometry of the magmatic plumbing systems and the distribution of the resulting volcanism at surface. Therefore, knowing the stress configuration in the lithosphere at any scale (i.e. local, regional and plate-scale) is fundamental to understand the distribution of volcanism and, subsequently, to interpret volcanic unrest and potential tectonic controls of future eruptions. The objective of the present work is to provide a first-order estimate of the plate-scale tectonic stresses acting on the Canary Islands, one of the largest active intraplate volcanic regions of the World. In order to obtain the orientation of the minimum and maximum horizontal compressive stresses, we perform a series of 2D finite element models of plate scale kinematics assuming plane stress approximation. Results obtained are used to develop a regional model, which takes into account recognized archipelago-scale structural discontinuities. Maximum horizontal compressive stress directions obtained are compared with available stress, geological and geodynamic data. The methodology used may be easily applied to other active volcanic regions, where a first order approach of their plate/regional stresses can be essential information to be used as input data for volcanic hazard assessment models.

  14. Refining regional SOC estimates: Accounting for erosion induced within field variability of the vertical distribution of SOC.

    Science.gov (United States)

    Meersmans, Jeroen; Quine, Tim

    2013-04-01

    Recently, soil organic carbon (SOC) is considered as a dynamic soil property largely influencing soil quality and global C-cycling. Consequently, accurate mapping of SOC at the regional or national scale becomes an important issue in order to help policymakers in developing an appropriate soil and climate change management strategy. So far, in these studies, only factors determining the spatial and temporal distribution of SOC at the landscape scale, such as soil type, land use (change), climate and agro-management, were considered. Despite the fact that a few recent studies incorporated as well the distribution of SOC with depth, resulting in an improved representation of the 3D distribution of SOC, most studies only considers topsoil and/or are characterized by simple sampling by site at rather coarse resolution. Consequently, they omit quantification of stable subsoil carbon buried in depositional areas and does not allow to clearly identify significant differences of SOC and erosion at the within field scale. Hence, the variability of SOC at smaller scales in complex terrain driven by lateral soil transport processes (such as soil erosion), is still rather understudied and is not (well) presented in existing regional SOC estimates. Nevertheless, incorporating this smaller level of spatial detail will most probably have a major influence on SOC mapping and regional SOC stock dynamics' calculations. Consequently, there exists an urgent need in conducting an appropriate soil sampling strategy considering deeper layers and enabling us to detect significant patterns at detailed spatial levels. In this study we aim to unravel the variation of SOC depth distributions along typical hillslope transects under cropland (Devon, UK) and link these to soil redistribution rates and variations in C input, i.e. below and above ground biomass productivity. The radionuclide isotope Caesium-137 (137Cs) was used as proxy for erosion. Furthermore, a soil sampling strategy was

  15. A test of the 'one-point method' for estimating maximum carboxylation capacity from field-measured, light-saturated photosynthesis.

    Science.gov (United States)

    De Kauwe, Martin G; Lin, Yan-Shih; Wright, Ian J; Medlyn, Belinda E; Crous, Kristine Y; Ellsworth, David S; Maire, Vincent; Prentice, I Colin; Atkin, Owen K; Rogers, Alistair; Niinemets, Ülo; Serbin, Shawn P; Meir, Patrick; Uddling, Johan; Togashi, Henrique F; Tarvainen, Lasse; Weerasinghe, Lasantha K; Evans, Bradley J; Ishida, F Yoko; Domingues, Tomas F

    2016-05-01

    Simulations of photosynthesis by terrestrial biosphere models typically need a specification of the maximum carboxylation rate (Vcmax ). Estimating this parameter using A-Ci curves (net photosynthesis, A, vs intercellular CO2 concentration, Ci ) is laborious, which limits availability of Vcmax data. However, many multispecies field datasets include net photosynthetic rate at saturating irradiance and at ambient atmospheric CO2 concentration (Asat ) measurements, from which Vcmax can be extracted using a 'one-point method'. We used a global dataset of A-Ci curves (564 species from 46 field sites, covering a range of plant functional types) to test the validity of an alternative approach to estimate Vcmax from Asat via this 'one-point method'. If leaf respiration during the day (Rday ) is known exactly, Vcmax can be estimated with an r(2) value of 0.98 and a root-mean-squared error (RMSE) of 8.19 μmol m(-2) s(-1) . However, Rday typically must be estimated. Estimating Rday as 1.5% of Vcmax, we found that Vcmax could be estimated with an r(2) of 0.95 and an RMSE of 17.1 μmol m(-2) s(-1) . The one-point method provides a robust means to expand current databases of field-measured Vcmax , giving new potential to improve vegetation models and quantify the environmental drivers of Vcmax variation.

  16. The floor in the interplanetary magnetic field: Estimation on the basis of relative duration of ICME observations in solar wind during 1976-2000

    CERN Document Server

    Yermolaev, Yu I; Nikolaeva, N S; Yermolaev, M Yu

    2009-01-01

    To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use global solar parameters: we identified different large-scale types of solar wind for 1976-2000 interval, obtained a fraction of interplanetary CMEs (ICMEs) and calculated magnitude of interplanetary magnetic field B averaged over 2 Carrington rotations. The floor of magnetic field is estimated as B value at solar cycle minimum when the ICMEs were not observed and it was calculated to be 4,65 \\pm 6,0 nT. Obtained value is in a good agreement with previous results.

  17. Amino acid sequences mediating vascular cell adhesion molecule 1 binding to integrin alpha 4: homologous DSP sequence found for JC polyoma VP1 coat protein

    Directory of Open Access Journals (Sweden)

    Michael Andrew Meyer

    2013-07-01

    Full Text Available The JC polyoma viral coat protein VP1 was analyzed for amino acid sequences homologies to the IDSP sequence which mediates binding of VLA-4 (integrin alpha 4 to vascular cell adhesion molecule 1. Although the full sequence was not found, a DSP sequence was located near the critical arginine residue linked to infectivity of the virus and binding to sialic acid containing molecules such as integrins (3. For the JC polyoma virus, a DSP sequence was found at residues 70, 71 and 72 with homology also noted for the mouse polyoma virus and SV40 virus. Three dimensional modeling of the VP1 molecule suggests that the DSP loop has an accessible site for interaction from the external side of the assembled viral capsid pentamer.

  18. Amino Acid Sequences Mediating Vascular Cell Adhesion Molecule 1 Binding to Integrin Alpha 4: Homologous DSP Sequence Found for JC Polyoma VP1 Coat Protein.

    Science.gov (United States)

    Meyer, Michael Andrew

    2013-01-01

    The JC polyoma viral coat protein VP1 was analyzed for amino acid sequences homologies to the IDSP sequence which mediates binding of VLA-4 (integrin alpha 4) to vascular cell adhesion molecule 1. Although the full sequence was not found, a DSP sequence was located near the critical arginine residue linked to infectivity of the virus and binding to sialic acid containing molecules such as integrins (3). For the JC polyoma virus, a DSP sequence was found at residues 70, 71 and 72 with homology also noted for the mouse polyoma virus and SV40 virus. Three dimensional modeling of the VP1 molecule suggests that the DSP loop has an accessible site for interaction from the external side of the assembled viral capsid pentamer.

  19. Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

    Science.gov (United States)

    Yokelson, R. J.; Burling, I. R.; Gilman, J. B.; Warneke, C.; Stockwell, C. E.; de Gouw, J.; Akagi, S. K.; Urbanski, S. P.; Veres, P.; Roberts, J. M.; Kuster, W. C.; Reardon, J.; Griffith, D. W. T.; Johnson, T. J.; Hosseini, S.; Miller, J. W.; Cocker, D. R., III; Jung, H.; Weise, D. R.

    2013-01-01

    statistically different from one, on average. However, our lab EF for "smoldering compounds" emitted from the semiarid shrubland fuels should likely be increased by a factor of ~2.7 to better represent field fires. Based on the lab/field comparison, we present emission factors for 357 pyrogenic species (including unidentified species) for 4 broad fuel types: pine understory, semiarid shrublands, coniferous canopy, and organic soil. To our knowledge this is the most comprehensive measurement of biomass burning emissions to date and it should enable improved representation of smoke composition in atmospheric models. The results support a recent estimate of global NMOC emissions from biomass burning that is much higher than widely used estimates and they provide important insights into the nature of smoke. 31-72% of the mass of gas-phase NMOC species was attributed to species that we could not identify. These unidentified species are not represented in most models, but some provision should be made for the fact that they will react in the atmosphere. In addition, the total mass of gas-phase NMOC divided by the mass of co-emitted PM2.5 averaged about three (range ~2.0-8.7). About 35-64% of the NMOC were likely semivolatile or of intermediate volatility. Thus, the gas-phase NMOC represent a large reservoir of potential precursors for secondary formation of ozone and organic aerosol. For the single lab fire in organic soil about 28% of the emitted carbon was present as gas-phase NMOC and ~72% of the mass of these NMOC was unidentified, highlighting the need to learn more about the emissions from smoldering organic soils. The mass ratio of total NMOC to "NOx as NO" ranged from 11 to 267, indicating that NOx-limited O3 production would be common in evolving biomass burning plumes. The fuel consumption per unit area was 7.0 ± 2.3 Mg ha-1 and 7.7 ± 3.7 Mg ha-1 for pine-understory and semiarid shrubland prescribed fires, respectively.

  20. Coupling field and laboratory measurements to estimate the emission factors of identified and unidentified trace gases for prescribed fires

    Directory of Open Access Journals (Sweden)

    R. J. Yokelson

    2013-01-01

    the pine understory fuels was not statistically different from one, on average. However, our lab EF for "smoldering compounds" emitted from the semiarid shrubland fuels should likely be increased by a factor of ~2.7 to better represent field fires. Based on the lab/field comparison, we present emission factors for 357 pyrogenic species (including unidentified species for 4 broad fuel types: pine understory, semiarid shrublands, coniferous canopy, and organic soil.

    To our knowledge this is the most comprehensive measurement of biomass burning emissions to date and it should enable improved representation of smoke composition in atmospheric models. The results support a recent estimate of global NMOC emissions from biomass burning that is much higher than widely used estimates and they provide important insights into the nature of smoke. 31–72% of the mass of gas-phase NMOC species was attributed to species that we could not identify. These unidentified species are not represented in most models, but some provision should be made for the fact that they will react in the atmosphere. In addition, the total mass of gas-phase NMOC divided by the mass of co-emitted PM2.5 averaged about three (range ~2.0–8.7. About 35–64% of the NMOC were likely semivolatile or of intermediate volatility. Thus, the gas-phase NMOC represent a large reservoir of potential precursors for secondary formation of ozone and organic aerosol. For the single lab fire in organic soil about 28% of the emitted carbon was present as gas-phase NMOC and ~72% of the mass of these NMOC was unidentified, highlighting the need to learn more about the emissions from smoldering organic soils. The mass ratio of total NMOC to "NOx as NO" ranged from 11 to 267, indicating that NOx-limited O3 production would be common in evolving biomass burning plumes. The fuel consumption per unit area was 7.0 ± 2.3 Mg ha−1 and 7.7 ± 3.7 Mg ha−1