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Sample records for local approach methods

  1. A Local Coordinate Approach in the MLPG Method for Beam Problems

    NASA Technical Reports Server (NTRS)

    Raju, Ivatury S.; Phillips, Dawn R.

    2002-01-01

    System matrices for Euler-Bernoulli beam problems for the meshless local Petrov-Galerkin (MLPG) method deteriorate as the number of nodes in the beam models are consistently increased. The reason for this behavior is explained. To overcome this difficulty and improve the accuracy of the solutions, a local coordinate approach for the evaluation of the generalized moving least squares shape functions and their derivatives is proposed. The proposed approach retains the accuracy of the MLPG methods.

  2. Localized 2D COSY sequences: Method and experimental evaluation for a whole metabolite quantification approach

    NASA Astrophysics Data System (ADS)

    Martel, Dimitri; Tse Ve Koon, K.; Le Fur, Yann; Ratiney, Hélène

    2015-11-01

    Two-dimensional spectroscopy offers the possibility to unambiguously distinguish metabolites by spreading out the multiplet structure of J-coupled spin systems into a second dimension. Quantification methods that perform parametric fitting of the 2D MRS signal have recently been proposed for resolved PRESS (JPRESS) but not explicitly for Localized Correlation Spectroscopy (LCOSY). Here, through a whole metabolite quantification approach, correlation spectroscopy quantification performances are studied. The ability to quantify metabolite relaxation constant times is studied for three localized 2D MRS sequences (LCOSY, LCTCOSY and the JPRESS) in vitro on preclinical MR systems. The issues encountered during implementation and quantification strategies are discussed with the help of the Fisher matrix formalism. The described parameterized models enable the computation of the lower bound for error variance - generally known as the Cramér Rao bounds (CRBs), a standard of precision - on the parameters estimated from these 2D MRS signal fittings. LCOSY has a theoretical net signal loss of two per unit of acquisition time compared to JPRESS. A rapid analysis could point that the relative CRBs of LCOSY compared to JPRESS (expressed as a percentage of the concentration values) should be doubled but we show that this is not necessarily true. Finally, the LCOSY quantification procedure has been applied on data acquired in vivo on a mouse brain.

  3. A nonparametric approach to calculate critical micelle concentrations: the local polynomial regression method.

    PubMed

    López Fontán, J L; Costa, J; Ruso, J M; Prieto, G; Sarmiento, F

    2004-02-01

    The application of a statistical method, the local polynomial regression method, (LPRM), based on a nonparametric estimation of the regression function to determine the critical micelle concentration (cmc) is presented. The method is extremely flexible because it does not impose any parametric model on the subjacent structure of the data but rather allows the data to speak for themselves. Good concordance of cmc values with those obtained by other methods was found for systems in which the variation of a measured physical property with concentration showed an abrupt change. When this variation was slow, discrepancies between the values obtained by LPRM and others methods were found.

  4. An Examination of Rater Performance on a Local Oral English Proficiency Test: A Mixed-Methods Approach

    ERIC Educational Resources Information Center

    Yan, Xun

    2014-01-01

    This paper reports on a mixed-methods approach to evaluate rater performance on a local oral English proficiency test. Three types of reliability estimates were reported to examine rater performance from different perspectives. Quantitative results were also triangulated with qualitative rater comments to arrive at a more representative picture of…

  5. Efficient and accurate local approximations to coupled-electron pair approaches: An attempt to revive the pair natural orbital method

    NASA Astrophysics Data System (ADS)

    Neese, Frank; Wennmohs, Frank; Hansen, Andreas

    2009-03-01

    Coupled-electron pair approximations (CEPAs) and coupled-pair functionals (CPFs) have been popular in the 1970s and 1980s and have yielded excellent results for small molecules. Recently, interest in CEPA and CPF methods has been renewed. It has been shown that these methods lead to competitive thermochemical, kinetic, and structural predictions. They greatly surpass second order Møller-Plesset and popular density functional theory based approaches in accuracy and are intermediate in quality between CCSD and CCSD(T) in extended benchmark studies. In this work an efficient production level implementation of the closed shell CEPA and CPF methods is reported that can be applied to medium sized molecules in the range of 50-100 atoms and up to about 2000 basis functions. The internal space is spanned by localized internal orbitals. The external space is greatly compressed through the method of pair natural orbitals (PNOs) that was also introduced by the pioneers of the CEPA approaches. Our implementation also makes extended use of density fitting (or resolution of the identity) techniques in order to speed up the laborious integral transformations. The method is called local pair natural orbital CEPA (LPNO-CEPA) (LPNO-CPF). The implementation is centered around the concepts of electron pairs and matrix operations. Altogether three cutoff parameters are introduced that control the size of the significant pair list, the average number of PNOs per electron pair, and the number of contributing basis functions per PNO. With the conservatively chosen default values of these thresholds, the method recovers about 99.8% of the canonical correlation energy. This translates to absolute deviations from the canonical result of only a few kcal mol-1. Extended numerical test calculations demonstrate that LPNO-CEPA (LPNO-CPF) has essentially the same accuracy as parent CEPA (CPF) methods for thermochemistry, kinetics, weak interactions, and potential energy surfaces but is up to 500

  6. Approaches to localized NMR spectroscopy in vivo

    SciTech Connect

    Garwood, M.G.

    1985-01-01

    Nuclear magnetic resonance (NMR) techniques are developed which allow spatially localized spectra to be obtained from living tissue. The localization methods are noninvasive and exploit the enhanced sensitivity afforded by surface coil probes. Techniques are investigated by computer simulation and experimentally verified by the use of phantom samples. The feasibility and utility of the techniques developed in this research are demonstrated by /sup 31/P spatial localization experiments involving various in vivo organs. In the first part of the thesis, two feasible approaches to localized spectroscopy, which were developed by other laboratories are theoretically analyzed by computer simulation. An alternative approach is provided by the rotating frame zeugmatography experiment which affords chemical-shift spectra displayed as a function of penetration distance into the sample. The further modification of the rotating frame experiment is developed, the Fourier series window (FSW) approach, which utilizes various types of window functions to afford localization in one or a few tissue regions of interest with high sensitivity. Theoretical comparisons with depth pulse methods are also included, along with methods to refine adverse off-resonance behavior.

  7. Speeding up local correlation methods

    SciTech Connect

    Kats, Daniel

    2014-12-28

    We present two techniques that can substantially speed up the local correlation methods. The first one allows one to avoid the expensive transformation of the electron-repulsion integrals from atomic orbitals to virtual space. The second one introduces an algorithm for the residual equations in the local perturbative treatment that, in contrast to the standard scheme, does not require holding the amplitudes or residuals in memory. It is shown that even an interpreter-based implementation of the proposed algorithm in the context of local MP2 method is faster and requires less memory than the highly optimized variants of conventional algorithms.

  8. Enzyme-labeled Antigen Method: Development and Application of the Novel Approach for Identifying Plasma Cells Locally Producing Disease-specific Antibodies in Inflammatory Lesions

    PubMed Central

    Mizutani, Yasuyoshi; Shiogama, Kazuya; Onouchi, Takanori; Sakurai, Kouhei; Inada, Ken-ichi; Tsutsumi, Yutaka

    2016-01-01

    In chronic inflammatory lesions of autoimmune and infectious diseases, plasma cells are frequently observed. Antigens recognized by antibodies produced by the plasma cells mostly remain unclear. A new technique identifying these corresponding antigens may give us a breakthrough for understanding the disease from a pathophysiological viewpoint, simply because the immunocytes are seen within the lesion. We have developed an enzyme-labeled antigen method for microscopic identification of the antigen recognized by specific antibodies locally produced in plasma cells in inflammatory lesions. Firstly, target biotinylated antigens were constructed by the wheat germ cell-free protein synthesis system or through chemical biotinylation. Next, proteins reactive to antibodies in tissue extracts were screened and antibody titers were evaluated by the AlphaScreen method. Finally, with the enzyme-labeled antigen method using the biotinylated antigens as probes, plasma cells producing specific antibodies were microscopically localized in fixed frozen sections. Our novel approach visualized tissue plasma cells that produced 1) autoantibodies in rheumatoid arthritis, 2) antibodies against major antigens of Porphyromonas gingivalis in periodontitis or radicular cyst, and 3) antibodies against a carbohydrate antigen, Strep A, of Streptococcus pyogenes in recurrent tonsillitis. Evaluation of local specific antibody responses expectedly contributes to clarifying previously unknown processes in inflammatory disorders. PMID:27006517

  9. Local Health Department Factors Associated With Performance in the Successful Implementation of Community-Based Strategies: A Mixed-Methods Approach

    PubMed Central

    Gearin, Kimberly; Frauendienst, Renee; Myhre, Julie; Larson, Michelle; Riley, William

    2015-01-01

    Objectives. We examined which local health department (LHD)–level factors contributed to successful implementation of policy, systems, and environmental change strategies in Minnesota. Methods. We used a retrospective mixed-methods design to evaluate the relationship between the Statewide Health Improvement Plan (SHIP) grant initiative and key predictor variables (2009–2011). We obtained quantitative capacity data for 91 cities and counties in Minnesota; in addition, we conducted 15 key informant interviews to examine factors that facilitated and acted as barriers to LHD performance. Results. Grantee performance was distributed as follows: exceeds expectations (29.7%), meets expectations (55.0%), and is approaching expectations (15.3%). Organizational quality improvement (QI) maturity was strongly positively associated with grantee performance on SHIP. Organizations with high QI maturity, effective leadership, efficient decision-making, and successful regional or cross-jurisdictional partnerships were more likely to be rated as exceeding expectations. Conclusions. This study successfully translated practice-based research findings into tangible outcomes, including new system-level performance measures for local public health and recommendations for shaping the statewide initiative examined in this study. The approach taken in this study to systematically monitor communications, dissemination, and translation may be a model for others. PMID:25689180

  10. Local health department factors associated with performance in the successful implementation of community-based strategies: a mixed-methods approach.

    PubMed

    Gyllstrom, Elizabeth; Gearin, Kimberly; Frauendienst, Renee; Myhre, Julie; Larson, Michelle; Riley, William

    2015-04-01

    We examined which local health department (LHD)-level factors contributed to successful implementation of policy, systems, and environmental change strategies in Minnesota. We used a retrospective mixed-methods design to evaluate the relationship between the Statewide Health Improvement Plan (SHIP) grant initiative and key predictor variables (2009-2011). We obtained quantitative capacity data for 91 cities and counties in Minnesota; in addition, we conducted 15 key informant interviews to examine factors that facilitated and acted as barriers to LHD performance. Grantee performance was distributed as follows: exceeds expectations (29.7%), meets expectations (55.0%), and is approaching expectations (15.3%). Organizational quality improvement (QI) maturity was strongly positively associated with grantee performance on SHIP. Organizations with high QI maturity, effective leadership, efficient decision-making, and successful regional or cross-jurisdictional partnerships were more likely to be rated as exceeding expectations. This study successfully translated practice-based research findings into tangible outcomes, including new system-level performance measures for local public health and recommendations for shaping the statewide initiative examined in this study. The approach taken in this study to systematically monitor communications, dissemination, and translation may be a model for others.

  11. Local theory of extrapolation methods

    NASA Astrophysics Data System (ADS)

    Kulikov, Gennady

    2010-03-01

    In this paper we discuss the theory of one-step extrapolation methods applied both to ordinary differential equations and to index 1 semi-explicit differential-algebraic systems. The theoretical background of this numerical technique is the asymptotic global error expansion of numerical solutions obtained from general one-step methods. It was discovered independently by Henrici, Gragg and Stetter in 1962, 1964 and 1965, respectively. This expansion is also used in most global error estimation strategies as well. However, the asymptotic expansion of the global error of one-step methods is difficult to observe in practice. Therefore we give another substantiation of extrapolation technique that is based on the usual local error expansion in a Taylor series. We show that the Richardson extrapolation can be utilized successfully to explain how extrapolation methods perform. Additionally, we prove that the Aitken-Neville algorithm works for any one-step method of an arbitrary order s, under suitable smoothness.

  12. Time Discretization Approach to Dynamic Localization Conditions

    NASA Astrophysics Data System (ADS)

    Papp, E.

    An alternative wavefunction to the description of the dynamic localization of a charged particle moving on a one-dimensional lattice under the influence of a periodic time dependent electric field is written down. For this purpose the method of characteristics such as applied by Dunlap and Kenkre [Phys. Rev. B 34, 3625 (1986)] has been modified by using a different integration variable. Handling this wavefunction one is faced with the selection of admissible time values. This results in a conditionally exactly solvable problem, now by accounting specifically for the implementation of a time discretization working in conjunction with a related dynamic localization condition. In addition, one resorts to the strong field limit, which amounts to replace, to leading order, the large order zeros of the Bessel function J0(z), used before in connection with the cosinusoidal modulation, by integral multiples of π. Here z stands for the ratio between the field amplitude and the frequency. The modulation function of the electric field vanishes on the nodal points of the time grid, which stands for an effective field-free behavior. This opens the way to propose quickly tractable dynamic localization conditions for arbitrary periodic modulations. We have also found that the present time discretization approach produces the minimization of the mean square displacement characterizing the usual exact wavefunction. Other realizations and comparisons have also been presented.

  13. Color-based lip localization method

    NASA Astrophysics Data System (ADS)

    Hassanat, Ahmad B. A.; Jassim, Sabah

    2010-04-01

    This paper is concerned with lip localization for visual speech recognition (VSR) system. We shall present an efficient method for localization human's lips/mouth in video images. This method is based on using the YCbCr approach to find at least any part of the lip as an initial step. Then we use all the available information about the segmented lip-pixels such as r, g, b, warped hue, etc. to segment the rest of the lip. The mean is calculated for each value, then for each pixel in ROI, Euclidian distance from the mean vector is calculated. Pixels with smaller distances are further clustered as lip pixels. Thus, the rest of the pixels in ROI will be clustered (to lip/non-lip pixel) depending on their distances from the mean vector of the initial segmented lip region. The method is evaluated on a new-recorded database of 780,000 frames; the experiments show that the method localizes the lips efficiently, with high level of accuracy (91.15%) that outperforms existing lip detection approaches.

  14. Computational methods for global/local analysis

    NASA Technical Reports Server (NTRS)

    Ransom, Jonathan B.; Mccleary, Susan L.; Aminpour, Mohammad A.; Knight, Norman F., Jr.

    1992-01-01

    Computational methods for global/local analysis of structures which include both uncoupled and coupled methods are described. In addition, global/local analysis methodology for automatic refinement of incompatible global and local finite element models is developed. Representative structural analysis problems are presented to demonstrate the global/local analysis methods.

  15. A local approach for focussed Bayesian fusion

    NASA Astrophysics Data System (ADS)

    Sander, Jennifer; Heizmann, Michael; Goussev, Igor; Beyerer, Jürgen

    2009-04-01

    Local Bayesian fusion approaches aim to reduce high storage and computational costs of Bayesian fusion which is separated from fixed modeling assumptions. Using the small world formalism, we argue why this proceeding is conform with Bayesian theory. Then, we concentrate on the realization of local Bayesian fusion by focussing the fusion process solely on local regions that are task relevant with a high probability. The resulting local models correspond then to restricted versions of the original one. In a previous publication, we used bounds for the probability of misleading evidence to show the validity of the pre-evaluation of task specific knowledge and prior information which we perform to build local models. In this paper, we prove the validity of this proceeding using information theoretic arguments. For additional efficiency, local Bayesian fusion can be realized in a distributed manner. Here, several local Bayesian fusion tasks are evaluated and unified after the actual fusion process. For the practical realization of distributed local Bayesian fusion, software agents are predestinated. There is a natural analogy between the resulting agent based architecture and criminal investigations in real life. We show how this analogy can be used to improve the efficiency of distributed local Bayesian fusion additionally. Using a landscape model, we present an experimental study of distributed local Bayesian fusion in the field of reconnaissance, which highlights its high potential.

  16. A multidisciplinary approach to landslide structure characterization: integration of seismic tomography survey and high resolution LiDar data with the Sloping Local Base Level method.

    NASA Astrophysics Data System (ADS)

    Travelletti, Julien; Samyn, Kevin; Malet, Jean-Philippe; Grandjean, Gilles; Jaboyedoff, Michel

    2010-05-01

    A challenge to progress in the understanding of landslides is to precisely define their 3D geometry and structure as an input for volume estimation and further hydro-mechanical modelling. The objective of this work is to present a multidisciplinary approach to the geometrical modelling of the La Valette landslide by integrating seismic tomography survey (P and S wave) and high resolution LiDar data with the Sloping Local Base Level (SLBL) method. The La Valette landslide, triggered in March 1982, is one of the most important slope instability in the South French Alps. Its dimensions are 1380 m length and 290 m width, and the total volume is estimated at 3.5 106 m3. Since 2002, an important activity of the upper part of the landslide is observed, and consisted mainly in the retrogression of the crown through the opening of an important fracture over several meters and rotational slumps. The failed mass is currently loading the upper part of the mudslide and is a potential threat for the 170 residential communities. A seismic tomography survey combined to airborne and terrestrial LiDar data analysis have been carried out to identify the geological structures and discontinuities and characterize the stability of the failing mass. Seismic tomography allows direct and non-intrusive measurements of P and S waves velocities which are key parameters for the analysis of the mechanical properties of reworked and highly fissured masses. 4 seismic lines have been performed (3 of them in the direction of the slope and the other perpendicular). The 2 longest devices are composed of 24 geophones spaced by 5 meters and have a sufficient investigation depth for a large scale characterization of the landslide's structure with depth. The 2 shortest devices, composed of 24 geophones spaced by 2 meters bring information about the fracturing degree between the moving material of the landslide and the competent rock. 100gr of pentrite for each shot were used as seismic sources. The

  17. Auditory detection and localization of approaching vehicles.

    PubMed

    Barton, Benjamin K; Ulrich, Thomas A; Lew, Roger

    2012-11-01

    Pedestrians must use a variety of cues when making safe decisions, many of which require processing of auditory information. We examined detection and localization of approaching vehicles using auditory cues. 50 adults ages 18-49 were presented with actual sounds of vehicles approaching at 5, 12, 25, and 35 mph. Three indices were of interest: the distance at which vehicles were detected, participants' decision regarding the direction from which vehicles were approaching, and their determination of the vehicles' arrival at their location. Participants more easily detected vehicles moving at higher speeds and vehicles approaching from the right. Determination of the direction of approach reached 90% accuracy or better when vehicles were traveling at, or greater than, 12 mph, and were more approaching from the right. Determination of vehicle arrival deteriorated significantly as speeds increased. Implications of the use of auditory cues in pedestrian settings, and future directions, are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Method for localizing heating in tumor tissue

    DOEpatents

    Doss, James D.; McCabe, Charles W.

    1977-04-12

    A method for a localized tissue heating of tumors is disclosed. Localized radio frequency current fields are produced with specific electrode configurations. Several electrode configurations are disclosed, enabling variations in electrical and thermal properties of tissues to be exploited.

  19. LOCALIZING THE RANGELAND HEALTH METHOD FOR SOUTHEASTERN ARIZONA

    EPA Science Inventory

    The interagency manual Interpreting Indicators of Rangeland Health, Version 4 (Technical Reference 1734-6) provides a method for making rangeland health assessments. The manual recommends that the rangeland health assessment approach be adapted to local conditions. This technica...

  20. LOCALIZING THE RANGELAND HEALTH METHOD FOR SOUTHEASTERN ARIZONA

    EPA Science Inventory

    The interagency manual Interpreting Indicators of Rangeland Health, Version 4 (Technical Reference 1734-6) provides a method for making rangeland health assessments. The manual recommends that the rangeland health assessment approach be adapted to local conditions. This technica...

  1. Extended local equilibrium approach to stochastic thermodynamics

    NASA Astrophysics Data System (ADS)

    De Decker, Y.; Garcia Cantú Ros, A.; Nicolis, G.

    2015-07-01

    A new approach to stochastic thermodynamics is developed, in which the local equilibrium hypothesis is extended to incorporate the effect of fluctuations. A fluctuating entropy in the form of a random functional of the fluctuating state variables is introduced, whose balance equation allows to identify the stochastic entropy flux and stochastic entropy production. The statistical properties of these quantities are analyzed and illustrated on representative examples.

  2. Local electric dipole moments: A generalized approach.

    PubMed

    Groß, Lynn; Herrmann, Carmen

    2016-09-30

    We present an approach for calculating local electric dipole moments for fragments of molecular or supramolecular systems. This is important for understanding chemical gating and solvent effects in nanoelectronics, atomic force microscopy, and intensities in infrared spectroscopy. Owing to the nonzero partial charge of most fragments, "naively" defined local dipole moments are origin-dependent. Inspired by previous work based on Bader's atoms-in-molecules (AIM) partitioning, we derive a definition of fragment dipole moments which achieves origin-independence by relying on internal reference points. Instead of bond critical points (BCPs) as in existing approaches, we use as few reference points as possible, which are located between the fragment and the remainder(s) of the system and may be chosen based on chemical intuition. This allows our approach to be used with AIM implementations that circumvent the calculation of critical points for reasons of computational efficiency, for cases where no BCPs are found due to large interfragment distances, and with local partitioning schemes other than AIM which do not provide BCPs. It is applicable to both covalently and noncovalently bound systems. © 2016 Wiley Periodicals, Inc.

  3. The analysis of NMR J-couplings of saturated and unsaturated compounds by the localized second order polarization propagator approach method.

    PubMed

    Zarycz, Natalia; Aucar, Gustavo A

    2012-05-07

    Calculations of NMR J-coupling with polarization propagators are not invariant under unitary transformations at second order level of approach, second order polarization propagator approach (SOPPA). They are only invariant at first order or random phase level of approach (RPA). We performed "localized" SOPPA (Loc-SOPPA), calculations of J-couplings applying two different schemes for the localization of molecular orbitals(LMO): Foster-Boys and Pipek-Mezey. We show here that results of such Loc-SOPPA calculations are different though not much: they are less than 6% different in the worst case. Therefore it is possible to apply them with confidence in the analysis of the transmission of different coupling mechanisms within the molecule. We are able now to get reliable information on what LMOs are the most important (and so which are not important) for a given J-coupling in a molecule. This information can then be used for selecting which are the paths that should be described with the highest possible accuracy for that J-coupling calculation. A few unsaturated compounds are analyzed: ethene, trans-difluoroethene or DiF-ethene, and imine. It is shown that different lone pairs (of p(z) or p(x/y) type) are responsible for the vicinal F-F J-coupling in DiF-ethene; and also the fact that the main LP contributor is not the same for the fermi contact and the spin-dipolar mechanisms. We also studied phosphorous containing compounds such as phosphine and cis-propylene phosphine. In both cases the analysis of the main LMO contributing to one-bond P-H coupling and through-space P-C coupling were performed. The above mentioned unsaturated molecular systems have quasiinstability problems that arise at RPA level of approach. We show here that they are mostly originated in the antibonding π∗ LMO, corresponding to the C=C or C=N double bonds. We performed the analysis of the origin of quasiinstabilities for the SD mechanism. The contribution of each kind of excitation terms to

  4. Methods and strategies of object localization

    NASA Technical Reports Server (NTRS)

    Shao, Lejun; Volz, Richard A.

    1989-01-01

    An important property of an intelligent robot is to be able to determine the location of an object in 3-D space. A general object localization system structure is proposed, some important issues on localization discussed, and an overview given for current available object localization algorithms and systems. The algorithms reviewed are characterized by their feature extracting and matching strategies; the range finding methods; the types of locatable objects; and the mathematical formulating methods.

  5. New Approach for Measured Surface Localization Based on Umbilical Points

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao-Ping; Yin, Ming; Heng, Liang; Yin, Guo-Fu; Li, Zi-Sheng

    2017-09-01

    Measured surface localization (MSL) is one of the key essentials for the assessment of form error in precision manufacturing. Currently, the researches on MSL have focused on the corresponding relation search between two surfaces, the performance improvement of localization algorithms and the uncertainty analysis of localization. However, low efficiency, limitation of localization algorithms and mismatch of multiple similarities of feature points with no prior are the common disadvantages for MSL. In order to match feature points quickly and fulfill MSL efficiently, this paper presents a new localization approach for measured surfaces by extracting the generic umbilics and estimating their single complex variables, describing the match methods of ambiguous relation at umbilics, presenting the initial localization process of one pair matched points, refining MSL on the basis of obtained closet points for some measured points by the improvement directed projection method. In addition, the proposed algorithm is simulated in two different types of surfaces, two different localization types and multiple similar surfaces, also tested with the part of B-spline surface machined and bottle mould with no knowledge, finally the initial and accurate rigid body transformation matrix, localization errors between two surfaces and execution time are got. The experimental results show that the proposed method is feasible, more accurate in localization and high in efficiency. The proposed research can not only improve the accuracy and performance of form error assessment, but also provide an effective guideline for the integration of different types of measured surfaces.

  6. Support vector machine approach for protein subcellular localization prediction.

    PubMed

    Hua, S; Sun, Z

    2001-08-01

    Subcellular localization is a key functional characteristic of proteins. A fully automatic and reliable prediction system for protein subcellular localization is needed, especially for the analysis of large-scale genome sequences. In this paper, Support Vector Machine has been introduced to predict the subcellular localization of proteins from their amino acid compositions. The total prediction accuracies reach 91.4% for three subcellular locations in prokaryotic organisms and 79.4% for four locations in eukaryotic organisms. Predictions by our approach are robust to errors in the protein N-terminal sequences. This new approach provides superior prediction performance compared with existing algorithms based on amino acid composition and can be a complementary method to other existing methods based on sorting signals. A web server implementing the prediction method is available at http://www.bioinfo.tsinghua.edu.cn/SubLoc/. Supplementary material is available at http://www.bioinfo.tsinghua.edu.cn/SubLoc/.

  7. A Localization Method for Multistatic SAR Based on Convex Optimization

    PubMed Central

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function’s maximum is on the circumference of the ellipse which is the iso-range for its model function’s T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment. PMID:26566031

  8. A Localization Method for Multistatic SAR Based on Convex Optimization.

    PubMed

    Zhong, Xuqi; Wu, Junjie; Yang, Jianyu; Sun, Zhichao; Huang, Yuling; Li, Zhongyu

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function's maximum is on the circumference of the ellipse which is the iso-range for its model function's T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment.

  9. A novel eye localization method with rotation invariance.

    PubMed

    Ren, Yan; Wang, Shuang; Hou, Biao; Ma, Jingjing

    2014-01-01

    This paper presents a novel learning method for precise eye localization, a challenge to be solved in order to improve the performance of face processing algorithms. Few existing approaches can directly detect and localize eyes with arbitrary angels in predicted eye regions, face images, and original portraits at the same time. To preserve rotation invariant property throughout the entire eye localization framework, a codebook of invariant local features is proposed for the representation of eye patterns. A heat map is then generated by integrating a 2-class sparse representation classifier with a pyramid-like detecting and locating strategy to fulfill the task of discriminative classification and precise localization. Furthermore, a series of prior information is adopted to improve the localization precision and accuracy. Experimental results on three different databases show that our method is capable of effectively locating eyes in arbitrary rotation situations (360° in plane).

  10. Dynamically screened local correlation method using enveloping localized orbitals.

    PubMed

    Auer, Alexander A; Nooijen, Marcel

    2006-07-14

    In this paper we present a local coupled cluster approach based on a dynamical screening scheme, in which amplitudes are either calculated at the coupled cluster level (in this case CCSD) or at the level of perturbation theory, employing a threshold driven procedure based on MP2 energy increments. This way, controllable accuracy and smooth convergence towards the exact result are obtained in the framework of an a posteriori approximation scheme. For the representation of the occupied space a new set of local orbitals is presented with the size of a minimal basis set. This set is atom centered, is nonorthogonal, and has shapes which are fairly independent of the details of the molecular system of interest. Two slightly different versions of combined local coupled cluster and perturbation theory equations are considered. In the limit both converge to the untruncated CCSD result. Benchmark calculations for four systems (heptane, serine, water hexamer, and oxadiazole-2-oxide) are carried out, and decay of the amplitudes, truncation error, and convergence towards the exact CCSD result are analyzed.

  11. Dynamically screened local correlation method using enveloping localized orbitals

    NASA Astrophysics Data System (ADS)

    Auer, Alexander A.; Nooijen, Marcel

    2006-07-01

    In this paper we present a local coupled cluster approach based on a dynamical screening scheme, in which amplitudes are either calculated at the coupled cluster level (in this case CCSD) or at the level of perturbation theory, employing a threshold driven procedure based on MP2 energy increments. This way, controllable accuracy and smooth convergence towards the exact result are obtained in the framework of an a posteriori approximation scheme. For the representation of the occupied space a new set of local orbitals is presented with the size of a minimal basis set. This set is atom centered, is nonorthogonal, and has shapes which are fairly independent of the details of the molecular system of interest. Two slightly different versions of combined local coupled cluster and perturbation theory equations are considered. In the limit both converge to the untruncated CCSD result. Benchmark calculations for four systems (heptane, serine, water hexamer, and oxadiazole-2-oxide) are carried out, and decay of the amplitudes, truncation error, and convergence towards the exact CCSD result are analyzed.

  12. Signal localization: a new approach in signal discovery.

    PubMed

    Malov, Sergey V; Antonik, Alexey; Tang, Minzhong; Berred, Alexandre; Zeng, Yi; O'Brien, Stephen J

    2017-01-01

    A new approach for statistical association signal identification is developed in this paper. We consider a strategy for nonprecise signal identification by extending the well-known signal detection and signal identification methods applicable to the multiple testing problem. Collection of statistical instruments under the presented approach is much broader than under the traditional signal identification methods, allowing more efficient signal discovery. Further assessments of maximal value and average statistics in signal discovery are improved. While our method does not attempt to detect individual predictors, it instead detects sets of predictors that are jointly associated with the outcome. Therefore, an important application would be in genome wide association study (GWAS), where it can be used to detect genes which influence the phenotype but do not contain any individually significant single nucleotide polymorphism (SNP). We compare power of the signal identification method based on extremes of single p-values with the signal localization method based on average statistics for logarithms of p-values. A simulation analysis informs the application of signal localization using the average statistics for wide signals discovery in Gaussian white noise process. We apply average statistics and the localization method to GWAS to discover better gene influences of regulating loci in a Chinese cohort developed for risk of nasopharyngeal carcinoma (NPC). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Control methods for localization of nonlinear waves

    NASA Astrophysics Data System (ADS)

    Porubov, Alexey; Andrievsky, Boris

    2017-03-01

    A general form of a distributed feedback control algorithm based on the speed-gradient method is developed. The goal of the control is to achieve nonlinear wave localization. It is shown by example of the sine-Gordon equation that the generation and further stable propagation of a localized wave solution of a single nonlinear partial differential equation may be obtained independently of the initial conditions. The developed algorithm is extended to coupled nonlinear partial differential equations to obtain consistent localized wave solutions at rather arbitrary initial conditions. This article is part of the themed issue 'Horizons of cybernetical physics'.

  14. Control methods for localization of nonlinear waves.

    PubMed

    Porubov, Alexey; Andrievsky, Boris

    2017-03-06

    A general form of a distributed feedback control algorithm based on the speed-gradient method is developed. The goal of the control is to achieve nonlinear wave localization. It is shown by example of the sine-Gordon equation that the generation and further stable propagation of a localized wave solution of a single nonlinear partial differential equation may be obtained independently of the initial conditions. The developed algorithm is extended to coupled nonlinear partial differential equations to obtain consistent localized wave solutions at rather arbitrary initial conditions.This article is part of the themed issue 'Horizons of cybernetical physics'.

  15. Approaches to local climate action in Colorado

    NASA Astrophysics Data System (ADS)

    Huang, Y. D.

    2011-12-01

    Though climate change is a global problem, the impacts are felt on the local scale; it follows that the solutions must come at the local level. Fortunately, many cities and municipalities are implementing climate mitigation (or climate action) policies and programs. However, they face many procedural and institutional barriers to their efforts, such of lack of expertise or data, limited human and financial resources, and lack of community engagement (Krause 2011). To address the first obstacle, thirteen in-depth case studies were done of successful model practices ("best practices") of climate action programs carried out by various cities, counties, and organizations in Colorado, and one outside Colorado, and developed into "how-to guides" for other municipalities to use. Research was conducted by reading documents (e.g. annual reports, community guides, city websites), email correspondence with program managers and city officials, and via phone interviews. The information gathered was then compiled into a series of reports containing a narrative description of the initiative; an overview of the plan elements (target audience and goals); implementation strategies and any indicators of success to date (e.g. GHG emissions reductions, cost savings); and the adoption or approval process, as well as community engagement efforts and marketing or messaging strategies. The types of programs covered were energy action plans, energy efficiency programs, renewable energy programs, and transportation and land use programs. Between the thirteen case studies, there was a range of approaches to implementing local climate action programs, examined along two dimensions: focus on climate change (whether it was direct/explicit or indirect/implicit) and extent of government authority. This benchmarking exercise affirmed the conventional wisdom propounded by Pitt (2010), that peer pressure (that is, the presence of neighboring jurisdictions with climate initiatives), the level of

  16. Multivariate localization methods for ensemble Kalman filtering

    NASA Astrophysics Data System (ADS)

    Roh, S.; Jun, M.; Szunyogh, I.; Genton, M. G.

    2015-05-01

    In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (entry-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.

  17. Multivariate localization methods for ensemble Kalman filtering

    NASA Astrophysics Data System (ADS)

    Roh, S.; Jun, M.; Szunyogh, I.; Genton, M. G.

    2015-12-01

    In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (element-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables that exist at the same locations has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.

  18. Localized-overlap approach to calculations of intermolecular interactions

    NASA Astrophysics Data System (ADS)

    Rob, Fazle

    Symmetry-adapted perturbation theory (SAPT) based on the density functional theory (DFT) description of the monomers [SAPT(DFT)] is one of the most robust tools for computing intermolecular interaction energies. Currently, one can use the SAPT(DFT) method to calculate interaction energies of dimers consisting of about a hundred atoms. To remove the methodological and technical limits and extend the size of the systems that can be calculated with the method, a novel approach has been proposed that redefines the electron densities and polarizabilities in a localized way. In the new method, accurate but computationally expensive quantum-chemical calculations are only applied for the regions where it is necessary and for other regions, where overlap effects of the wave functions are negligible, inexpensive asymptotic techniques are used. Unlike other hybrid methods, this new approach is mathematically rigorous. The main benefit of this method is that with the increasing size of the system the calculation scales linearly and, therefore, this approach will be denoted as local-overlap SAPT(DFT) or LSAPT(DFT). As a byproduct of developing LSAPT(DFT), some important problems concerning distributed molecular response, in particular, the unphysical charge-flow terms were eliminated. Additionally, to illustrate the capabilities of SAPT(DFT), a potential energy function has been developed for an energetic molecular crystal of 1,1-diamino-2,2-dinitroethylene (FOX-7), where an excellent agreement with the experimental data has been found.

  19. State space approach to single molecule localization in fluorescence microscopy

    PubMed Central

    Vahid, Milad R.; Chao, Jerry; Kim, Dongyoung; Ward, E. Sally; Ober, Raimund J.

    2017-01-01

    Single molecule super-resolution microscopy enables imaging at sub-diffraction-limit resolution by producing images of subsets of stochastically photoactivated fluorophores over a sequence of frames. In each frame of the sequence, the fluorophores are accurately localized, and the estimated locations are used to construct a high-resolution image of the cellular structures labeled by the fluorophores. Many methods have been developed for localizing fluorophores from the images. The majority of these methods comprise two separate steps: detection and estimation. In the detection step, fluorophores are identified. In the estimation step, the locations of the identified fluorophores are estimated through an iterative approach. Here, we propose a non-iterative state space-based localization method which combines the detection and estimation steps. We demonstrate that the estimated locations obtained from the proposed method can be used as initial conditions in an estimation routine to potentially obtain improved location estimates. The proposed method models the given image as the frequency response of a multi-order system obtained with a balanced state space realization algorithm based on the singular value decomposition of a Hankel matrix. The locations of the poles of the resulting system determine the peak locations in the frequency domain, and the locations of the most significant peaks correspond to the single molecule locations in the original image. The performance of the method is validated using both simulated and experimental data. PMID:28663832

  20. State space approach to single molecule localization in fluorescence microscopy.

    PubMed

    Vahid, Milad R; Chao, Jerry; Kim, Dongyoung; Ward, E Sally; Ober, Raimund J

    2017-03-01

    Single molecule super-resolution microscopy enables imaging at sub-diffraction-limit resolution by producing images of subsets of stochastically photoactivated fluorophores over a sequence of frames. In each frame of the sequence, the fluorophores are accurately localized, and the estimated locations are used to construct a high-resolution image of the cellular structures labeled by the fluorophores. Many methods have been developed for localizing fluorophores from the images. The majority of these methods comprise two separate steps: detection and estimation. In the detection step, fluorophores are identified. In the estimation step, the locations of the identified fluorophores are estimated through an iterative approach. Here, we propose a non-iterative state space-based localization method which combines the detection and estimation steps. We demonstrate that the estimated locations obtained from the proposed method can be used as initial conditions in an estimation routine to potentially obtain improved location estimates. The proposed method models the given image as the frequency response of a multi-order system obtained with a balanced state space realization algorithm based on the singular value decomposition of a Hankel matrix. The locations of the poles of the resulting system determine the peak locations in the frequency domain, and the locations of the most significant peaks correspond to the single molecule locations in the original image. The performance of the method is validated using both simulated and experimental data.

  1. Enhanced Methods for Local Ancestry Assignment in Sequenced Admixed Individuals

    PubMed Central

    Brown, Robert; Pasaniuc, Bogdan

    2014-01-01

    Inferring the ancestry at each locus in the genome of recently admixed individuals (e.g., Latino Americans) plays a major role in medical and population genetic inferences, ranging from finding disease-risk loci, to inferring recombination rates, to mapping missing contigs in the human genome. Although many methods for local ancestry inference have been proposed, most are designed for use with genotyping arrays and fail to make use of the full spectrum of data available from sequencing. In addition, current haplotype-based approaches are very computationally demanding, requiring large computational time for moderately large sample sizes. Here we present new methods for local ancestry inference that leverage continent-specific variants (CSVs) to attain increased performance over existing approaches in sequenced admixed genomes. A key feature of our approach is that it incorporates the admixed genomes themselves jointly with public datasets, such as 1000 Genomes, to improve the accuracy of CSV calling. We use simulations to show that our approach attains accuracy similar to widely used computationally intensive haplotype-based approaches with large decreases in runtime. Most importantly, we show that our method recovers comparable local ancestries, as the 1000 Genomes consensus local ancestry calls in the real admixed individuals from the 1000 Genomes Project. We extend our approach to account for low-coverage sequencing and show that accurate local ancestry inference can be attained at low sequencing coverage. Finally, we generalize CSVs to sub-continental population-specific variants (sCSVs) and show that in some cases it is possible to determine the sub-continental ancestry for short chromosomal segments on the basis of sCSVs. PMID:24743331

  2. Local participation in natural resource monitoring: a characterization of approaches.

    PubMed

    Danielsen, Finn; Burgess, Neil D; Balmford, Andrew; Donald, Paul F; Funder, Mikkel; Jones, Julia P G; Alviola, Philip; Balete, Danilo S; Blomley, Tom; Brashares, Justin; Child, Brian; Enghoff, Martin; Fjeldså, Jon; Holt, Sune; Hübertz, Hanne; Jensen, Arne E; Jensen, Per M; Massao, John; Mendoza, Marlynn M; Ngaga, Yonika; Poulsen, Michael K; Rueda, Ricardo; Sam, Moses; Skielboe, Thomas; Stuart-Hill, Greg; Topp-Jørgensen, Elmer; Yonten, Deki

    2009-02-01

    The monitoring of trends in the status of species or habitats is routine in developed countries, where it is funded by the state or large nongovernmental organizations and often involves large numbers of skilled amateur volunteers. Far less monitoring of natural resources takes place in developing countries, where state agencies have small budgets, there are fewer skilled professionals or amateurs, and socioeconomic conditions prevent development of a culture of volunteerism. The resulting lack of knowledge about trends in species and habitats presents a serious challenge for detecting, understanding, and reversing declines in natural resource values. International environmental agreements require signatories undertake systematic monitoring of their natural resources, but no system exists to guide the development and expansion of monitoring schemes. To help develop such a protocol, we suggest a typology of monitoring categories, defined by their degree of local participation, ranging from no local involvement with monitoring undertaken by professional researchers to an entirely local effort with monitoring undertaken by local people. We assessed the strengths and weaknesses of each monitoring category and the potential of each to be sustainable in developed or developing countries. Locally based monitoring is particularly relevant in developing countries, where it can lead to rapid decisions to solve the key threats affecting natural resources, can empower local communities to better manage their resources, and can refine sustainable-use strategies to improve local livelihoods. Nevertheless, we recognize that the accuracy and precision of the monitoring undertaken by local communities in different situations needs further study and field protocols need to be further developed to get the best from the unrealized potential of this approach. A challenge to conservation biologists is to identify and establish the monitoring system most relevant to a particular

  3. Local control approach to ultrafast electron transfer

    NASA Astrophysics Data System (ADS)

    Vindel-Zandbergen, Patricia; Meier, Christoph; Sola, Ignacio R.

    2016-10-01

    We study ultrafast electron transfer between separated nuclei using local control theory. By imposing electron ionization and electron transport through the continuum, different local control formulations are used to increase the yield of retrapping the electron at the desired nuclei. The control mechanism is based on impulsive de-excitation. Both symmetric and asymmetric nuclear arrangements are analyzed, as well as the role of the nuclear motion.

  4. System and method for object localization

    NASA Technical Reports Server (NTRS)

    Kelly, Alonzo J. (Inventor); Zhong, Yu (Inventor)

    2005-01-01

    A computer-assisted method for localizing a rack, including sensing an image of the rack, detecting line segments in the sensed image, recognizing a candidate arrangement of line segments in the sensed image indicative of a predetermined feature of the rack, generating a matrix of correspondence between the candidate arrangement of line segments and an expected position and orientation of the predetermined feature of the rack, and estimating a position and orientation of the rack based on the matrix of correspondence.

  5. Optic disk localization by a robust fusion method

    NASA Astrophysics Data System (ADS)

    Zhang, Jielin; Yin, Fengshou; Wong, Damon W. K.; Liu, Jiang; Baskaran, Mani; Cheng, Ching-Yu; Wong, Tien Yin

    2013-02-01

    The optic disk localization plays an important role in developing computer-aided diagnosis (CAD) systems for ocular diseases such as glaucoma, diabetic retinopathy and age-related macula degeneration. In this paper, we propose an intelligent fusion of methods for the localization of the optic disk in retinal fundus images. Three different approaches are developed to detect the location of the optic disk separately. The first method is the maximum vessel crossing method, which finds the region with the most number of blood vessel crossing points. The second one is the multichannel thresholding method, targeting the area with the highest intensity. The final method searches the vertical and horizontal region-of-interest separately on the basis of blood vessel structure and neighborhood entropy profile. Finally, these three methods are combined using an intelligent fusion method to improve the overall accuracy. The proposed algorithm was tested on the STARE database and the ORIGAlight database, each consisting of images with various pathologies. The preliminary result on the STARE database can achieve 81.5%, while a higher result of 99% can be obtained for the ORIGAlight database. The proposed method outperforms each individual approach and state-of-the-art method which utilizes an intensity-based approach. The result demonstrates a high potential for this method to be used in retinal CAD systems.

  6. Source Localization using Stochastic Approximation and Least Squares Methods

    SciTech Connect

    Sahyoun, Samir S.; Djouadi, Seddik M.; Qi, Hairong; Drira, Anis

    2009-03-05

    This paper presents two approaches to locate the source of a chemical plume; Nonlinear Least Squares and Stochastic Approximation (SA) algorithms. Concentration levels of the chemical measured by special sensors are used to locate this source. Non-linear Least Squares technique is applied at different noise levels and compared with the localization using SA. For a noise corrupted data collected from a distributed set of chemical sensors, we show that SA methods are more efficient than Least Squares method. SA methods are often better at coping with noisy input information than other search methods.

  7. A sensorimotor approach to sound localization.

    PubMed

    Aytekin, Murat; Moss, Cynthia F; Simon, Jonathan Z

    2008-03-01

    Sound localization is known to be a complex phenomenon, combining multisensory information processing, experience-dependent plasticity, and movement. Here we present a sensorimotor model that addresses the question of how an organism could learn to localize sound sources without any a priori neural representation of its head-related transfer function or prior experience with auditory spatial information. We demonstrate quantitatively that the experience of the sensory consequences of its voluntary motor actions allows an organism to learn the spatial location of any sound source. Using examples from humans and echolocating bats, our model shows that a naive organism can learn the auditory space based solely on acoustic inputs and their relation to motor states.

  8. Meshless Local Petrov-Galerkin Method for Bending Problems

    NASA Technical Reports Server (NTRS)

    Phillips, Dawn R.; Raju, Ivatury S.

    2002-01-01

    Recent literature shows extensive research work on meshless or element-free methods as alternatives to the versatile Finite Element Method. One such meshless method is the Meshless Local Petrov-Galerkin (MLPG) method. In this report, the method is developed for bending of beams - C1 problems. A generalized moving least squares (GMLS) interpolation is used to construct the trial functions, and spline and power weight functions are used as the test functions. The method is applied to problems for which exact solutions are available to evaluate its effectiveness. The accuracy of the method is demonstrated for problems with load discontinuities and continuous beam problems. A Petrov-Galerkin implementation of the method is shown to greatly reduce computational time and effort and is thus preferable over the previously developed Galerkin approach. The MLPG method for beam problems yields very accurate deflections and slopes and continuous moment and shear forces without the need for elaborate post-processing techniques.

  9. Using Local Born and Local Rytov Fourier Modeling and Migration Methods for Investigation of Heterogeneous Structures

    SciTech Connect

    Fehler, M.C.; Huang, L.-J.

    1998-12-10

    During the past few years, there has been interest in developing migration and forward modeling approaches that are both fast and reliable particularly in regions that have rapid spatial variations in structure. The authors have been investigating a suite of modeling and migration methods that are implemented in the wavenumber-space domains and operate on data in the frequency domain. The best known example of these methods is the split-step Fourier method (SSF). Two of the methods that the authors have developed are the extended local Born Fourier (ELBF) approach and the extended local Rytov Fourier (ELRF) approach. Both methods are based on solutions of the scalar (constant density) wave equation, are computationally fast and can reliably model effects of both deterministic and random structures. The authors have investigated their reliability for migrating both 2D synthetic data and real 2D field data. The authors have found that the methods give images that are better than those that can be obtained using other methods like the SSF and Kirchhoff migration approaches. More recently, the authors have developed an approach for solving the acoustic (variable density) wave equation and have begun to investigate its applicability for modeling one-way wave propagation. The methods will be introduced and their ability to model seismic wave propagation and migrate seismic data will be investigated. The authors will also investigate their capability to model forward wave propagation through random media and to image zones of small scale heterogeneity such as those associated with zones of high permeability.

  10. Nonlinear damage detection and localization using a time domain approach

    NASA Astrophysics Data System (ADS)

    Boccardi, S.; Calla, D.-B.; Malfense Fierro, G.-P.; Ciampa, F.; Meo, M.

    2016-04-01

    This paper presents a damage detection and localization technique based on nonlinear elastic waves propagation in a damage composite laminate. The proposed method relies on the time of arrival estimation of the second harmonic nonlinear response obtained with second order phase symmetry analysis filtering and burst excitation. The Akaike Information Criterion approach was used to estimate the arrival times measured by six receiver transducers. Then, a combination of Newton's method and unconstrained optimization was employed to solve a system of nonlinear equations in order to obtain the material damage coordinates. To validate this methodology, experimental tests were carried out on a damaged composite plate. The results showed that the technique allows calculating the damage position with high accuracy (maximum error ~5 mm).

  11. Nonlinear modal methods for crack localization

    NASA Astrophysics Data System (ADS)

    Sutin, Alexander; Ostrovsky, Lev; Lebedev, Andrey

    2003-10-01

    A nonlinear method for locating defects in solid materials is discussed that is relevant to nonlinear modal tomography based on the signal cross-modulation. The scheme is illustrated by a theoretical model in which a thin plate or bar with a single crack is excited by a strong low-frequency wave and a high-frequency probing wave (ultrasound). A crack is considered as a small contact-type defect which does not perturb the modal structure of sound in linear approximation but creates combinational-frequency components whose amplitudes depend on their closeness to a resonance and crack position. Using different crack models, including the hysteretic ones, the nonlinear part of its volume variations under the given stress and then the combinational wave components in the bar can be determined. Evidently, their amplitude depends strongly on the crack position with respect to the peaks or nodes of the corresponding linear signals which can be used for localization of the crack position. Exciting the sample by sweeping ultrasound frequencies through several resonances (modes) reduces the ambiguity in the localization. Some aspects of inverse problem solution are also discussed, and preliminary experimental results are presented.

  12. A robust baseline removal method for guided wave damage localization

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Harley, Joel B.; Bergés, Mario; Greve, David W.; Junker, Warren R.; Oppenheim, Irving J.

    2014-04-01

    Guided waves can propagate long distances and are sensitive to subtle structural damage. Guided-wave based damage localization often requires extracting the scatter signal(s) produced by damage, which is typically obtained by subtracting an intact baseline record from a record to be tested. However, in practical applications, environmental and operational conditions (EOC) dramatically affect guided wave signals. In this case, the baseline subtraction process can no longer perfectly remove the baseline, thereby defeating localization algorithms. In previous work, we showed that singular value decomposition (SVD) can be used to detect the presence of damage under large EOC variations, because it can differentiate the trends of damage from other EOC variations. This capability of differentiation implies that SVD can also robustly extract a scatter signal, originating from damage in the structure, that is not affected by temperature variation. This process allows us to extract a scatterer signal without the challenges associated with traditional temperature compensation and baseline subtraction routines. . In this work, we use to approach to localize structural damage in large, spatially and temporally varying EOCs. We collect pitch-catch records from randomly placed PZT transducers on an aluminum plate while undergoing temperature variations. Damage is introduced to the plate during the monitoring period. We then use our SVD method to extract the scatter signal from the records, and use the scatter signal to localize damage using the delay-and-sum method. To compare results, we also apply several temperature compensation methods to the records and then perform baseline subtraction. We show that our SVD-based approach successfully localize damage while current temperature-compensated baseline subtraction methods fail.

  13. Nonlinear modal method of crack localization

    NASA Astrophysics Data System (ADS)

    Ostrovsky, Lev; Sutin, Alexander; Lebedev, Andrey

    2004-05-01

    A simple scheme for crack localization is discussed that is relevant to nonlinear modal tomography based on the cross-modulation of two signals at different frequencies. The scheme is illustrated by a theoretical model, in which a thin plate or bar with a single crack is excited by a strong low-frequency wave and a high-frequency probing wave (ultrasound). The crack is assumed to be small relative to all wavelengths. Nonlinear scattering from the crack is studied using a general matrix approach as well as simplified models allowing one to find the nonlinear part of crack volume variations under the given stress and then the combinational wave components in the tested material. The nonlinear response strongly depends on the crack position with respect to the peaks or nodes of the corresponding interacting signals which can be used for determination of the crack position. Juxtaposing various resonant modes interacting at the crack it is possible to retrieve both crack location and orientation. Some aspects of inverse problem solutions are also discussed, and preliminary experimental results are presented.

  14. A PDE-Based Fast Local Level Set Method

    NASA Astrophysics Data System (ADS)

    Peng, Danping; Merriman, Barry; Osher, Stanley; Zhao, Hongkai; Kang, Myungjoo

    1999-11-01

    We develop a fast method to localize the level set method of Osher and Sethian (1988, J. Comput. Phys.79, 12) and address two important issues that are intrinsic to the level set method: (a) how to extend a quantity that is given only on the interface to a neighborhood of the interface; (b) how to reset the level set function to be a signed distance function to the interface efficiently without appreciably moving the interface. This fast local level set method reduces the computational effort by one order of magnitude, works in as much generality as the original one, and is conceptually simple and easy to implement. Our approach differs from previous related works in that we extract all the information needed from the level set function (or functions in multiphase flow) and do not need to find explicitly the location of the interface in the space domain. The complexity of our method to do tasks such as extension and distance reinitialization is O(N), where N is the number of points in space, not O(N log N) as in works by Sethian (1996, Proc. Nat. Acad. Sci. 93, 1591) and Helmsen and co-workers (1996, SPIE Microlithography IX, p. 253). This complexity estimation is also valid for quite general geometrically based front motion for our localized method.

  15. Improving mobile robot localization: grid-based approach

    NASA Astrophysics Data System (ADS)

    Yan, Junchi

    2012-02-01

    Autonomous mobile robots have been widely studied not only as advanced facilities for industrial and daily life automation, but also as a testbed in robotics competitions for extending the frontier of current artificial intelligence. In many of such contests, the robot is supposed to navigate on the ground with a grid layout. Based on this observation, we present a localization error correction method by exploring the geometric feature of the tile patterns. On top of the classical inertia-based positioning, our approach employs three fiber-optic sensors that are assembled under the bottom of the robot, presenting an equilateral triangle layout. The sensor apparatus, together with the proposed supporting algorithm, are designed to detect a line's direction (vertical or horizontal) by monitoring the grid crossing events. As a result, the line coordinate information can be fused to rectify the cumulative localization deviation from inertia positioning. The proposed method is analyzed theoretically in terms of its error bound and also has been implemented and tested on a customary developed two-wheel autonomous mobile robot.

  16. A diagrammatic quantum field approach to localized-electron systems

    NASA Astrophysics Data System (ADS)

    Bonev, Stanimir; Ashcroft, Neil W.

    2002-03-01

    We present a diagrammatic language for the variational evaluation of the energy of systems with localized electrons. It is used to develop a convergent series expansion for the energy in powers of overlap integrals of single-particle orbitals. This method gives intuitive and practical rules for writing down the expansion to arbitrary order of overlap, and can be applied to any spin configuration, and to any dimension. Our approach extends previous work by van Dijk and Vertogen,(L. G. J. van Dijk and G. Vertogen, J. Phys.: Condens. Matter 3), 7763 (1991). Abarenkov,(I. V. Abarenkov, J. Phys.: Condens. Matter 5) 2341 (1993). and Moulopoulos and Ashcroft.(K. Moulopoulos and N. W. Ashcroft, Phys. Rev. B 48) 11646 (1993).

  17. Using the Storypath Approach to Make Local Government Understandable

    ERIC Educational Resources Information Center

    McGuire, Margit E.; Cole, Bronwyn

    2008-01-01

    Learning about local government seems boring and irrelevant to most young people, particularly to students from high-poverty backgrounds. The authors explore a promising approach for solving this problem, Storypath, which engages students in authentic learning and active citizenship. The Storypath approach is based on a narrative in which students…

  18. Field Theory Approach to Many-Body Localization

    NASA Astrophysics Data System (ADS)

    Altland, Alexander; Micklitz, Tobias

    2017-03-01

    We introduce an analytic approach to many-body localization (MBL) in random spin chains. We consider MBL within a first quantized framework where it becomes a localization phenomenon in the high-dimensional lattice defined by the Hilbert space of the clean system. Designed in analogy with the field-theory description of single particle localization, our approach describes wave package propagation on that lattice after a disorder average has been performed and the system is controlled by only a few universal parameters. We discuss the stability of an ergodic weak disorder and a localized strong disorder phase, respectively, and demonstrate that the latter is protected by mechanisms which put MBL outside the universality class of Anderson localization.

  19. Locally Compact Quantum Groups. A von Neumann Algebra Approach

    NASA Astrophysics Data System (ADS)

    Van Daele, Alfons

    2014-08-01

    In this paper, we give an alternative approach to the theory of locally compact quantum groups, as developed by Kustermans and Vaes. We start with a von Neumann algebra and a comultiplication on this von Neumann algebra. We assume that there exist faithful left and right Haar weights. Then we develop the theory within this von Neumann algebra setting. In [Math. Scand. 92 (2003), 68-92] locally compact quantum groups are also studied in the von Neumann algebraic context. This approach is independent of the original C^*-algebraic approach in the sense that the earlier results are not used. However, this paper is not really independent because for many proofs, the reader is referred to the original paper where the C^*-version is developed. In this paper, we give a completely self-contained approach. Moreover, at various points, we do things differently. We have a different treatment of the antipode. It is similar to the original treatment in [Ann. Sci. & #201;cole Norm. Sup. (4) 33 (2000), 837-934]. But together with the fact that we work in the von Neumann algebra framework, it allows us to use an idea from [Rev. Roumaine Math. Pures Appl. 21 (1976), 1411-1449] to obtain the uniqueness of the Haar weights in an early stage. We take advantage of this fact when deriving the other main results in the theory. We also give a slightly different approach to duality. Finally, we collect, in a systematic way, several important formulas. In an appendix, we indicate very briefly how the C^*-approach and the von Neumann algebra approach eventually yield the same objects. The passage from the von Neumann algebra setting to the C^*-algebra setting is more or less standard. For the other direction, we use a new method. It is based on the observation that the Haar weights on the C^*-algebra extend to weights on the double dual with central support and that all these supports are the same. Of course, we get the von Neumann algebra by cutting down the double dual with this unique

  20. Local Approximation and Hierarchical Methods for Stochastic Optimization

    NASA Astrophysics Data System (ADS)

    Cheng, Bolong

    In this thesis, we present local and hierarchical approximation methods for two classes of stochastic optimization problems: optimal learning and Markov decision processes. For the optimal learning problem class, we introduce a locally linear model with radial basis function for estimating the posterior mean of the unknown objective function. The method uses a compact representation of the function which avoids storing the entire history, as is typically required by nonparametric methods. We derive a knowledge gradient policy with the locally parametric model, which maximizes the expected value of information. We show the policy is asymptotically optimal in theory, and experimental works suggests that the method can reliably find the optimal solution on a range of test functions. For the Markov decision processes problem class, we are motivated by an application where we want to co-optimize a battery for multiple revenue, in particular energy arbitrage and frequency regulation. The nature of this problem requires the battery to make charging and discharging decisions at different time scales while accounting for the stochastic information such as load demand, electricity prices, and regulation signals. Computing the exact optimal policy becomes intractable due to the large state space and the number of time steps. We propose two methods to circumvent the computation bottleneck. First, we propose a nested MDP model that structure the co-optimization problem into smaller sub-problems with reduced state space. This new model allows us to understand how the battery behaves down to the two-second dynamics (that of the frequency regulation market). Second, we introduce a low-rank value function approximation for backward dynamic programming. This new method only requires computing the exact value function for a small subset of the state space and approximate the entire value function via low-rank matrix completion. We test these methods on historical price data from the

  1. A Tomographic Method for the Reconstruction of Local Probability Density Functions

    NASA Technical Reports Server (NTRS)

    Sivathanu, Y. R.; Gore, J. P.

    1993-01-01

    A method of obtaining the probability density function (PDF) of local properties from path integrated measurements is described. The approach uses a discrete probability function (DPF) method to infer the PDF of the local extinction coefficient from measurements of the PDFs of the path integrated transmittance. The local PDFs obtained using the method are compared with those obtained from direct intrusive measurements in propylene/air and ethylene/air diffusion flames. The results of this comparison are good.

  2. [A non-local means approach for PET image denoising].

    PubMed

    Yin, Yong; Sun, Weifeng; Lu, Jie; Liu, Tonghai

    2010-04-01

    Denoising is an important issue for medical image processing. Based on the analysis of the Non-local means algorithm recently reported by Buades A, et al. in international journals we herein propose adapting it for PET image denoising. Experimental de-noising results for real clinical PET images show that Non-local means method is superior to median filtering and wiener filtering methods and it can suppress noise in PET images effectively and preserve important details of structure for diagnosis.

  3. Performance of FFT methods in local gravity field modelling

    NASA Technical Reports Server (NTRS)

    Forsberg, Rene; Solheim, Dag

    1989-01-01

    Fast Fourier transform (FFT) methods provide a fast and efficient means of processing large amounts of gravity or geoid data in local gravity field modelling. The FFT methods, however, has a number of theoretical and practical limitations, especially the use of flat-earth approximation, and the requirements for gridded data. In spite of this the method often yields excellent results in practice when compared to other more rigorous (and computationally expensive) methods, such as least-squares collocation. The good performance of the FFT methods illustrate that the theoretical approximations are offset by the capability of taking into account more data in larger areas, especially important for geoid predictions. For best results good data gridding algorithms are essential. In practice truncated collocation approaches may be used. For large areas at high latitudes the gridding must be done using suitable map projections such as UTM, to avoid trivial errors caused by the meridian convergence. The FFT methods are compared to ground truth data in New Mexico (xi, eta from delta g), Scandinavia (N from delta g, the geoid fits to 15 cm over 2000 km), and areas of the Atlantic (delta g from satellite altimetry using Wiener filtering). In all cases the FFT methods yields results comparable or superior to other methods.

  4. Local-basis-function approach to computed tomography

    NASA Astrophysics Data System (ADS)

    Hanson, K. M.; Wecksung, G. W.

    1985-12-01

    In the local basis-function approach, a reconstruction is represented as a linear expansion of basis functions, which are arranged on a rectangular grid and possess a local region of support. The basis functions considered here are positive and may overlap. It is found that basis functions based on cubic B-splines offer significant improvements in the calculational accuracy that can be achieved with iterative tomographic reconstruction algorithms. By employing repetitive basis functions, the computational effort involved in these algorithms can be minimized through the use of tabulated values for the line or strip integrals over a single-basis function. The local nature of the basis functions reduces the difficulties associated with applying local constraints on reconstruction values, such as upper and lower limits. Since a reconstruction is specified everywhere by a set of coefficients, display of a coarsely represented image does not require an arbitrary choice of an interpolation function.

  5. Quantifying optimal accuracy of local primary sequence bioinformatics methods

    NASA Astrophysics Data System (ADS)

    Aalberts, Daniel

    2005-03-01

    Traditional bioinformatics methods scan primary sequences for local patterns. It is important to assess how accurate local primary sequence methods can be. We study the problem of donor pre-mRNA splice site recognition, where the sequence overlaps between real and decoy data sets can be quantified, exposing the intrinsic limitations of the performance of local primary sequence methods. We assess the accuracy of local primary sequence methods generally by studying how they scale with dataset size and demonstrate that our new Primary Sequence Ranking methods have superior performance. Our Primary Sequence Ranking analysis tools are available at tt http://rna.williams.edu/

  6. Composite likelihood method for inferring local pedigrees

    PubMed Central

    Nielsen, Rasmus

    2017-01-01

    Pedigrees contain information about the genealogical relationships among individuals and are of fundamental importance in many areas of genetic studies. However, pedigrees are often unknown and must be inferred from genetic data. Despite the importance of pedigree inference, existing methods are limited to inferring only close relationships or analyzing a small number of individuals or loci. We present a simulated annealing method for estimating pedigrees in large samples of otherwise seemingly unrelated individuals using genome-wide SNP data. The method supports complex pedigree structures such as polygamous families, multi-generational families, and pedigrees in which many of the member individuals are missing. Computational speed is greatly enhanced by the use of a composite likelihood function which approximates the full likelihood. We validate our method on simulated data and show that it can infer distant relatives more accurately than existing methods. Furthermore, we illustrate the utility of the method on a sample of Greenlandic Inuit. PMID:28827797

  7. Quadratic function approaching method for magnetotelluric soundingdata inversion

    SciTech Connect

    Liangjun, Yan; Wenbao, Hu; Zhang, Keni

    2004-04-05

    The quadratic function approaching method (QFAM) is introduced for magnetotelluric sounding (MT) data inversion. The method takes the advantage of that quadratic function has single extreme value, which avoids leading to an inversion solution for local minimum and ensures the solution for global minimization of an objective function. The method does not need calculation of sensitivity matrix and not require a strict initial earth model. Examples for synthetic data and field measurement data indicate that the proposed inversion method is effective.

  8. The Local Variational Multiscale Method for Turbulence Simulation.

    SciTech Connect

    Collis, Samuel Scott; Ramakrishnan, Srinivas

    2005-05-01

    Accurate and efficient turbulence simulation in complex geometries is a formidable chal-lenge. Traditional methods are often limited by low accuracy and/or restrictions to simplegeometries. We explore the merger of Discontinuous Galerkin (DG) spatial discretizationswith Variational Multi-Scale (VMS) modeling, termed Local VMS (LVMS), to overcomethese limitations. DG spatial discretizations support arbitrarily high-order accuracy on un-structured grids amenable for complex geometries. Furthermore, high-order, hierarchicalrepresentation within DG provides a natural framework fora prioriscale separation crucialfor VMS implementation. We show that the combined benefits of DG and VMS within theLVMS method leads to promising new approach to LES for use in complex geometries.The efficacy of LVMS for turbulence simulation is assessed by application to fully-developed turbulent channelflow. First, a detailed spatial resolution study is undertakento record the effects of the DG discretization on turbulence statistics. Here, the localhp[?]refinement capabilites of DG are exploited to obtain reliable low-order statistics effi-ciently. Likewise, resolution guidelines for simulating wall-bounded turbulence using DGare established. We also explore the influence of enforcing Dirichlet boundary conditionsindirectly through numericalfluxes in DG which allows the solution to jump (slip) at thechannel walls. These jumps are effective in simulating the influence of the wall commen-surate with the local resolution and this feature of DG is effective in mitigating near-wallresolution requirements. In particular, we show that by locally modifying the numericalviscousflux used at the wall, we are able to regulate the near-wall slip through a penaltythat leads to improved shear-stress predictions. This work, demonstrates the potential ofthe numerical viscousflux to act as a numerically consistent wall-model and this successwarrents future research.As in any high-order numerical method some

  9. Fourier transform methods in local gravity modeling

    NASA Technical Reports Server (NTRS)

    Harrison, J. C.; Dickinson, M.

    1989-01-01

    New algorithms were derived for computing terrain corrections, all components of the attraction of the topography at the topographic surface and the gradients of these attractions. These algoriithms utilize fast Fourier transforms, but, in contrast to methods currently in use, all divergences of the integrals are removed during the analysis. Sequential methods employing a smooth intermediate reference surface were developed to avoid the very large transforms necessary when making computations at high resolution over a wide area. A new method for the numerical solution of Molodensky's problem was developed to mitigate the convergence difficulties that occur at short wavelengths with methods based on a Taylor series expansion. A trial field on a level surface is continued analytically to the topographic surface, and compared with that predicted from gravity observations. The difference is used to compute a correction to the trial field and the process iterated. Special techniques are employed to speed convergence and prevent oscillations. Three different spectral methods for fitting a point-mass set to a gravity field given on a regular grid at constant elevation are described. Two of the methods differ in the way that the spectrum of the point-mass set, which extends to infinite wave number, is matched to that of the gravity field which is band-limited. The third method is essentially a space-domain technique in which Fourier methods are used to solve a set of simultaneous equations.

  10. A Localized Tau Method PDE Solver

    NASA Technical Reports Server (NTRS)

    Cottam, Russell

    2002-01-01

    In this paper we present a new form of the collocation method that allows one to find very accurate solutions to time marching problems without the unwelcome appearance of Gibb's phenomenon oscillations. The basic method is applicable to any partial differential equation whose solution is a continuous, albeit possibly rapidly varying function. Discontinuous functions are dealt with by replacing the function in a small neighborhood of the discontinuity with a spline that smoothly connects the function segments on either side of the discontinuity. This will be demonstrated when the solution to the inviscid Burgers equation is discussed.

  11. Dual mode stereotactic localization method and application

    DOEpatents

    Keppel, Cynthia E.; Barbosa, Fernando Jorge; Majewski, Stanislaw

    2002-01-01

    The invention described herein combines the structural digital X-ray image provided by conventional stereotactic core biopsy instruments with the additional functional metabolic gamma imaging obtained with a dedicated compact gamma imaging mini-camera. Before the procedure, the patient is injected with an appropriate radiopharmaceutical. The radiopharmaceutical uptake distribution within the breast under compression in a conventional examination table expressed by the intensity of gamma emissions is obtained for comparison (co-registration) with the digital mammography (X-ray) image. This dual modality mode of operation greatly increases the functionality of existing stereotactic biopsy devices by yielding a much smaller number of false positives than would be produced using X-ray images alone. The ability to obtain both the X-ray mammographic image and the nuclear-based medicine gamma image using a single device is made possible largely through the use of a novel, small and movable gamma imaging camera that permits its incorporation into the same table or system as that currently utilized to obtain X-ray based mammographic images for localization of lesions.

  12. Methods for spatial localization in NMR

    SciTech Connect

    Rath, A.R.

    1985-01-01

    Several unique coil configurations were developed that have applications in nuclear magnetic resonance. These include a number of designs appropriate for use as rf surface coils, and two configurations developed as NMR magnets. The magnetic field profiles were calculated for each of these designs, from which field strength and homogeneity information were obtained. The rf coil configurations modelled include the opposed loop, opposed half loop, bicycle wheel, opposed bicycle wheel, and semi-toroid. The opposed loop design was studied in detail in terms of the theoretical spatial sensitivity and selectivity it offers. A number of NMR experiments were performed to test the validity of these theoretical calculations. This configuration produces a field that is substantially reduced near the coil itself, compared with the field produced by a single loop surface coil, but that rises to a maximum along the coil axis yielding a somewhat homogeneous region that may be used to achieve a degree of spatial localization. Several comparison schemes are used to evaluate the relative advantages and disadvantages of both the single loop and the opposed loop coil. The opposed coil concept also has been applied to the design of magnets. The results of calculations on the homogeneity and field strength possible with an opposed solenoid magnet are presented.

  13. New Methods for Crafting Locally Decision-Relevant Scenarios

    NASA Astrophysics Data System (ADS)

    Lempert, R. J.

    2015-12-01

    Scenarios can play an important role in helping decision makers to imagine future worlds, both good and bad, different than the one with which we are familiar and to take concrete steps now to address the risks generated by climate change. At their best, scenarios can effectively represent deep uncertainty; integrate over multiple domains; and enable parties with different expectation and values to expand the range of futures they consider, to see the world from different points of view, and to grapple seriously with the potential implications of surprising or inconvenient futures. These attributes of scenario processes can prove crucial in helping craft effective responses to climate change. But traditional scenario methods can also fail to overcome difficulties related to choosing, communicating, and using scenarios to identify, evaluate, and reach consensus on appropriate policies. Such challenges can limit scenario's impact in broad public discourse. This talk will demonstrate how new decision support approaches can employ new quantitative tools that allow scenarios to emerge from a process of deliberation with analysis among stakeholders, rather than serve as inputs to it, thereby increasing the impacts of scenarios on decision making. This talk will demonstrate these methods in the design of a decision support tool to help residents of low lying coastal cities grapple with the long-term risks of sea level rise. In particular, this talk will show how information from the IPCC SSP's can be combined with local information to provide a rich set of locally decision-relevant information.

  14. SubCellProt: predicting protein subcellular localization using machine learning approaches.

    PubMed

    Garg, Prabha; Sharma, Virag; Chaudhari, Pradeep; Roy, Nilanjan

    2009-01-01

    High-throughput genome sequencing projects continue to churn out enormous amounts of raw sequence data. However, most of this raw sequence data is unannotated and, hence, not very useful. Among the various approaches to decipher the function of a protein, one is to determine its localization. Experimental approaches for proteome annotation including determination of a protein's subcellular localizations are very costly and labor intensive. Besides the available experimental methods, in silico methods present alternative approaches to accomplish this task. Here, we present two machine learning approaches for prediction of the subcellular localization of a protein from the primary sequence information. Two machine learning algorithms, k Nearest Neighbor (k-NN) and Probabilistic Neural Network (PNN) were used to classify an unknown protein into one of the 11 subcellular localizations. The final prediction is made on the basis of a consensus of the predictions made by two algorithms and a probability is assigned to it. The results indicate that the primary sequence derived features like amino acid composition, sequence order and physicochemical properties can be used to assign subcellular localization with a fair degree of accuracy. Moreover, with the enhanced accuracy of our approach and the definition of a prediction domain, this method can be used for proteome annotation in a high throughput manner. SubCellProt is available at www.databases.niper.ac.in/SubCellProt.

  15. Mixed Methods Approaches in Family Science Research

    ERIC Educational Resources Information Center

    Plano Clark, Vicki L.; Huddleston-Casas, Catherine A.; Churchill, Susan L.; Green, Denise O'Neil; Garrett, Amanda L.

    2008-01-01

    The complex phenomena of interest to family scientists require the use of quantitative and qualitative approaches. Researchers across the social sciences are now turning to mixed methods designs that combine these two approaches. Mixed methods research has great promise for addressing family science topics, but only if researchers understand the…

  16. Mixed Methods Approaches in Family Science Research

    ERIC Educational Resources Information Center

    Plano Clark, Vicki L.; Huddleston-Casas, Catherine A.; Churchill, Susan L.; Green, Denise O'Neil; Garrett, Amanda L.

    2008-01-01

    The complex phenomena of interest to family scientists require the use of quantitative and qualitative approaches. Researchers across the social sciences are now turning to mixed methods designs that combine these two approaches. Mixed methods research has great promise for addressing family science topics, but only if researchers understand the…

  17. Autonomous Landmark Calibration Method for Indoor Localization

    PubMed Central

    Kim, Jae-Hoon; Kim, Byoung-Seop

    2017-01-01

    Machine-generated data expansion is a global phenomenon in recent Internet services. The proliferation of mobile communication and smart devices has increased the utilization of machine-generated data significantly. One of the most promising applications of machine-generated data is the estimation of the location of smart devices. The motion sensors integrated into smart devices generate continuous data that can be used to estimate the location of pedestrians in an indoor environment. We focus on the estimation of the accurate location of smart devices by determining the landmarks appropriately for location error calibration. In the motion sensor-based location estimation, the proposed threshold control method determines valid landmarks in real time to avoid the accumulation of errors. A statistical method analyzes the acquired motion sensor data and proposes a valid landmark for every movement of the smart devices. Motion sensor data used in the testbed are collected from the actual measurements taken throughout a commercial building to demonstrate the practical usefulness of the proposed method. PMID:28837071

  18. Global/local methods research using the CSM testbed

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Ransom, Jonathan B.; Griffin, O. Hayden, Jr.; Thompson, Danniella M.

    1990-01-01

    Research activities in global/local stress analysis are described including both two- and three-dimensional analysis methods. These methods are being developed within a common structural analysis framework. Representative structural analysis problems are presented to demonstrate the global/local methodologies being developed.

  19. Global/local methods research using the CSM testbed

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Ransom, Jonathan B.; Griffin, O. Hayden, Jr.; Thompson, Danniella M.

    1990-01-01

    Research activities in global/local stress analysis are described including both two- and three-dimensional analysis methods. These methods are being developed within a common structural analysis framework. Representative structural analysis problems are presented to demonstrate the global/local methodologies being developed.

  20. Accounting for Linkage Disequilibrium in genome scans for selection without individual genotypes: the local score approach.

    PubMed

    Fariello, María Inés; Boitard, Simon; Mercier, Sabine; Robelin, David; Faraut, Thomas; Arnould, Cécile; Recoquillay, Julien; Bouchez, Olivier; Salin, Gérald; Dehais, Patrice; Gourichon, David; Leroux, Sophie; Pitel, Frédérique; Leterrier, Christine; SanCristobal, Magali

    2017-04-10

    Detecting genomic footprints of selection is an important step in the understanding of evolution. Accounting for linkage disequilibrium in genome scans increases detection power, but haplotype-based methods require individual genotypes and are not applicable on pool-sequenced samples. We propose to take advantage of the local score approach to account for linkage disequilibrium in genome scans for selection, cumulating (possibly small) signals from single markers over a genomic segment, to clearly pinpoint a selection signal. Using computer simulations, we demonstrate that this approach detects selection with higher power than several state-of-the-art single marker, windowing or haplotype-based approaches. We illustrate this on two benchmark data sets including individual genotypes, for which we obtain similar results with the local score and one haplotype-based approach. Finally, we apply the local score approach to Pool-Seq data obtained from a divergent selection experiment on behavior in quail, and obtain precise and biologically coherent selection signals: while competing methods fail to highlight any clear selection signature, our method detects several regions involving genes known to act on social responsiveness or autistic traits. Although we focus here on the detection of positive selection from multiple population data, the local score approach is general and can be applied to other genome scans for selection or other genome-wide analyses such as GWAS. This article is protected by copyright. All rights reserved.

  1. Scaling theory of Anderson localization: A renormalization-group approach

    NASA Astrophysics Data System (ADS)

    Sarker, Sanjoy; Domany, Eytan

    1981-06-01

    A position-space renormalization-group method, suitable for studying the localization properties of electrons in a disordered system, was developed. Two different approximations to a well-defined exact procedure were used. The first method is a perturbative treatment to lowest order in the intercell couplings. This yields a localization edge in three dimensions, with a fixed point at the band center (E=0) at a critical disorder σc~=7.0. In the neighborhood of the fixed point the localization length L is predicted to diverge as L~(σ-σc+βE2)-ν. In two dimensions no fixed point is found, indicating localization even for small randomness, in agreement with Abrahams, Anderson, Licciardello, and Ramakrishnan. The second method is an application of the finite-lattice approximation, in which the intercell hopping between two (or more) cells is treated to infinite order in perturbation theory. To our knowledge, this method has not been previously used for quantum systems. Calculations based on this approximation were carried out in two dimensions only, yielding results that are in agreement with those of the lowest-order approximation.

  2. A downscaling method for the assessment of local climate change

    NASA Astrophysics Data System (ADS)

    Bruno, E.; Portoghese, I.; Vurro, M.

    2009-04-01

    The use of complimentary models is necessary to study the impact of climate change scenarios on the hydrological response at different space-time scales. However, the structure of GCMs is such that their space resolution (hundreds of kilometres) is too coarse and not adequate to describe the variability of extreme events at basin scale (Burlando and Rosso, 2002). To bridge the space-time gap between the climate scenarios and the usual scale of the inputs for hydrological prediction models is a fundamental requisite for the evaluation of climate change impacts on water resources. Since models operate a simplification of a complex reality, their results cannot be expected to fit with climate observations. Identifying local climate scenarios for impact analysis implies the definition of more detailed local scenario by downscaling GCMs or RCMs results. Among the output correction methods we consider the statistical approach by Déqué (2007) reported as a ‘Variable correction method' in which the correction of model outputs is obtained by a function build with the observation dataset and operating a quantile-quantile transformation (Q-Q transform). However, in the case of daily precipitation fields the Q-Q transform is not able to correct the temporal property of the model output concerning the dry-wet lacunarity process. An alternative correction method is proposed based on a stochastic description of the arrival-duration-intensity processes in coherence with the Poissonian Rectangular Pulse scheme (PRP) (Eagleson, 1972). In this proposed approach, the Q-Q transform is applied to the PRP variables derived from the daily rainfall datasets. Consequently the corrected PRP parameters are used for the synthetic generation of statistically homogeneous rainfall time series that mimic the persistency of daily observations for the reference period. Then the PRP parameters are forced through the GCM scenarios to generate local scale rainfall records for the 21st century. The

  3. Developmental differences in auditory detection and localization of approaching vehicles.

    PubMed

    Barton, Benjamin K; Lew, Roger; Kovesdi, Casey; Cottrell, Nicholas D; Ulrich, Thomas

    2013-04-01

    Pedestrian safety is a significant problem in the United States, with thousands being injured each year. Multiple risk factors exist, but one poorly understood factor is pedestrians' ability to attend to vehicles using auditory cues. Auditory information in the pedestrian setting is increasing in importance with the growing number of quieter hybrid and all-electric vehicles on America's roadways that do not emit sound cues pedestrians expect from an approaching vehicle. Our study explored developmental differences in pedestrians' detection and localization of approaching vehicles. Fifty children ages 6-9 years, and 35 adults participated. Participants' performance varied significantly by age, and with increasing speed and direction of the vehicle's approach. Results underscore the importance of understanding children's and adults' use of auditory cues for pedestrian safety and highlight the need for further research. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Localization and cooperative communication methods for cognitive radio

    NASA Astrophysics Data System (ADS)

    Duval, Olivier

    We study localization of nearby nodes and cooperative communication for cognitive radios. Cognitive radios sensing their environment to estimate the channel gain between nodes can cooperate and adapt their transmission power to maximize the capacity of the communication between two nodes. We study the end-to-end capacity of a cooperative relaying scheme using orthogonal frequency-division modulation (OFDM) modulation, under power constraints for both the base station and the relay station. The relay uses amplify-and-forward and decode-and-forward cooperative relaying techniques to retransmit messages on a subset of the available subcarriers. The power used in the base station and the relay station transmitters is allocated to maximize the overall system capacity. The subcarrier selection and power allocation are obtained based on convex optimization formulations and an iterative algorithm. Additionally, decode-and-forward relaying schemes are allowed to pair source and relayed subcarriers to increase further the capacity of the system. The proposed techniques outperforms non-selective relaying schemes over a range of relay power budgets. Cognitive radios can be used for opportunistic access of the radio spectrum by detecting spectrum holes left unused by licensed primary users. We introduce a spectrum holes detection approach, which combines blind modulation classification, angle of arrival estimation and number of sources detection. We perform eigenspace analysis to determine the number of sources, and estimate their angles of arrival (AOA). In addition, we classify detected sources as primary or secondary users with their distinct second-orde one-conjugate cyclostationarity features. Extensive simulations carried out indicate that the proposed system identifies and locates individual sources correctly, even at -4 dB signal-to-noise ratios (SNR). In environments with a high density of scatterers, several wireless channels experience nonline-of-sight (NLOS

  5. Comparison of local grid refinement methods for MODFLOW.

    PubMed

    Mehl, Steffen; Hill, Mary C; Leake, Stanley A

    2006-01-01

    Many ground water modeling efforts use a finite-difference method to solve the ground water flow equation, and many of these models require a relatively fine-grid discretization to accurately represent the selected process in limited areas of interest. Use of a fine grid over the entire domain can be computationally prohibitive; using a variably spaced grid can lead to cells with a large aspect ratio and refinement in areas where detail is not needed. One solution is to use local-grid refinement (LGR) whereby the grid is only refined in the area of interest. This work reviews some LGR methods and identifies advantages and drawbacks in test cases using MODFLOW-2000. The first test case is two dimensional and heterogeneous; the second is three dimensional and includes interaction with a meandering river. Results include simulations using a uniform fine grid, a variably spaced grid, a traditional method of LGR without feedback, and a new shared node method with feedback. Discrepancies from the solution obtained with the uniform fine grid are investigated. For the models tested, the traditional one-way coupled approaches produced discrepancies in head up to 6.8% and discrepancies in cell-to-cell fluxes up to 7.1%, while the new method has head and cell-to-cell flux discrepancies of 0.089% and 0.14%, respectively. Additional results highlight the accuracy, flexibility, and CPU time trade-off of these methods and demonstrate how the new method can be successfully implemented to model surface water-ground water interactions.

  6. Comparison of local grid refinement methods for MODFLOW

    USGS Publications Warehouse

    Mehl, S.; Hill, M.C.; Leake, S.A.

    2006-01-01

    Many ground water modeling efforts use a finite-difference method to solve the ground water flow equation, and many of these models require a relatively fine-grid discretization to accurately represent the selected process in limited areas of interest. Use of a fine grid over the entire domain can be computationally prohibitive; using a variably spaced grid can lead to cells with a large aspect ratio and refinement in areas where detail is not needed. One solution is to use local-grid refinement (LGR) whereby the grid is only refined in the area of interest. This work reviews some LGR methods and identifies advantages and drawbacks in test cases using MODFLOW-2000. The first test case is two dimensional and heterogeneous; the second is three dimensional and includes interaction with a meandering river. Results include simulations using a uniform fine grid, a variably spaced grid, a traditional method of LGR without feedback, and a new shared node method with feedback. Discrepancies from the solution obtained with the uniform fine grid are investigated. For the models tested, the traditional one-way coupled approaches produced discrepancies in head up to 6.8% and discrepancies in cell-to-cell fluxes up to 7.1%, while the new method has head and cell-to-cell flux discrepancies of 0.089% and 0.14%, respectively. Additional results highlight the accuracy, flexibility, and CPU time trade-off of these methods and demonstrate how the new method can be successfully implemented to model surface water-ground water interactions. Copyright ?? 2006 The Author(s).

  7. An alternative subspace approach to EEG dipole source localization.

    PubMed

    Xu, Xiao-Liang; Xu, Bobby; He, Bin

    2004-01-21

    In the present study, we investigate a new approach to electroencephalography (EEG) three-dimensional (3D) dipole source localization by using a non-recursive subspace algorithm called FINES. In estimating source dipole locations, the present approach employs projections onto a subspace spanned by a small set of particular vectors (FINES vector set) in the estimated noise-only subspace instead of the entire estimated noise-only subspace in the case of classic MUSIC. The subspace spanned by this vector set is, in the sense of principal angle, closest to the subspace spanned by the array manifold associated with a particular brain region. By incorporating knowledge of the array manifold in identifying FINES vector sets in the estimated noise-only subspace for different brain regions, the present approach is able to estimate sources with enhanced accuracy and spatial resolution, thus enhancing the capability of resolving closely spaced sources and reducing estimation errors. The present computer simulations show, in EEG 3D dipole source localization, that compared to classic MUSIC, FINES has (1) better resolvability of two closely spaced dipolar sources and (2) better estimation accuracy of source locations. In comparison with RAP-MUSIC, FINES' performance is also better for the cases studied when the noise level is high and/or correlations among dipole sources exist.

  8. An alternative subspace approach to EEG dipole source localization

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Liang; Xu, Bobby; He, Bin

    2004-01-01

    In the present study, we investigate a new approach to electroencephalography (EEG) three-dimensional (3D) dipole source localization by using a non-recursive subspace algorithm called FINES. In estimating source dipole locations, the present approach employs projections onto a subspace spanned by a small set of particular vectors (FINES vector set) in the estimated noise-only subspace instead of the entire estimated noise-only subspace in the case of classic MUSIC. The subspace spanned by this vector set is, in the sense of principal angle, closest to the subspace spanned by the array manifold associated with a particular brain region. By incorporating knowledge of the array manifold in identifying FINES vector sets in the estimated noise-only subspace for different brain regions, the present approach is able to estimate sources with enhanced accuracy and spatial resolution, thus enhancing the capability of resolving closely spaced sources and reducing estimation errors. The present computer simulations show, in EEG 3D dipole source localization, that compared to classic MUSIC, FINES has (1) better resolvability of two closely spaced dipolar sources and (2) better estimation accuracy of source locations. In comparison with RAP-MUSIC, FINES' performance is also better for the cases studied when the noise level is high and/or correlations among dipole sources exist.

  9. Energy-Based Acoustic Source Localization Methods: A Survey.

    PubMed

    Meng, Wei; Xiao, Wendong

    2017-02-15

    Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions.

  10. Energy-Based Acoustic Source Localization Methods: A Survey

    PubMed Central

    Meng, Wei; Xiao, Wendong

    2017-01-01

    Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions. PMID:28212281

  11. Emission Inventory: A local agency`s approach

    SciTech Connect

    Kestler, S.L.; Bien, D.L.; Gruber, L.R.

    1996-12-31

    The Department of Environmental Services-Air Quality Management (D.O.E.S.-A.Q.M.) in southwestern Ohio has inventoried stationary sources since the mid-1970`s. That inventory has changed over the years from one of unknown data quality to one of high quality and substantial use by the public, agency personnel and industry. Since 1990, the scope of the agency`s inventory has broadened to include the compilation of a local area source inventory every three years. This presentation explores a local agency`s {open_quotes}real life{close_quotes} approach to compiling their emission inventory. We will discuss the improvements made and the pitfalls encountered in the inventory process over the years.

  12. Discontinuous Galerkin Methods and Local Time Stepping for Wave Propagation

    SciTech Connect

    Grote, M. J.; Mitkova, T.

    2010-09-30

    Locally refined meshes impose severe stability constraints on explicit time-stepping methods for the numerical simulation of time dependent wave phenomena. To overcome that stability restriction, local time-stepping methods are developed, which allow arbitrarily small time steps precisely where small elements in the mesh are located. When combined with a discontinuous Galerkin finite element discretization in space, which inherently leads to a diagonal mass matrix, the resulting numerical schemes are fully explicit. Starting from the classical Adams-Bashforth multi-step methods, local time stepping schemes of arbitrarily high accuracy are derived. Numerical experiments validate the theory and illustrate the usefulness of the proposed time integration schemes.

  13. A Locally-Exact Homogenization Approach for Periodic Heterogeneous Materials

    SciTech Connect

    Drago, Anthony S.; Pindera, Marek-Jerzy

    2008-02-15

    Elements of the homogenization theory are utilized to develop a new micromechanics approach for unit cells of periodic heterogeneous materials based on locally-exact elasticity solutions. Closed-form expressions for the homogenized moduli of unidirectionally-reinforced heterogeneous materials are obtained in terms of Hill's strain concentration matrices valid under arbitrary combined loading, which yield the homogenized Hooke's law. Results for simple unit cells with off-set fibers, which require the use of periodic boundary conditions, are compared with corresponding finite-element results demonstrating excellent correlation.

  14. Multi-scale non-local denoising method in neuroimaging.

    PubMed

    Chen, Yiping; Wang, Cheng; Wang, Liansheng

    2016-03-17

    Non-local means algorithm can remove image noise in a unique way that is contrary to traditional techniques. This is because it not only smooths the image but it also preserves the information details of the image. However, this method suffers from high computational complexity. We propose a multi-scale non-local means method in which adaptive multi-scale technique is implemented. In practice, based on each selected scale, the input image is divided into small blocks. Then, we remove the noise in the given pixel by using only one block. This can overcome the low efficiency problem caused by the original non-local means method. Our proposed method also benefits from the local average gradient orientation. In order to perform evaluation, we compared the processed images based on our technique with the ones by the original and the improved non-local means denoising method. Extensive experiments are conducted and results shows that our method is faster than the original and the improved non-local means method. It is also proven that our implemented method is robust enough to remove noise in the application of neuroimaging.

  15. Adaptive windowed range-constrained Otsu method using local information

    NASA Astrophysics Data System (ADS)

    Zheng, Jia; Zhang, Dinghua; Huang, Kuidong; Sun, Yuanxi; Tang, Shaojie

    2016-01-01

    An adaptive windowed range-constrained Otsu method using local information is proposed for improving the performance of image segmentation. First, the reason why traditional thresholding methods do not perform well in the segmentation of complicated images is analyzed. Therein, the influences of global and local thresholdings on the image segmentation are compared. Second, two methods that can adaptively change the size of the local window according to local information are proposed by us. The characteristics of the proposed methods are analyzed. Thereby, the information on the number of edge pixels in the local window of the binarized variance image is employed to adaptively change the local window size. Finally, the superiority of the proposed method over other methods such as the range-constrained Otsu, the active contour model, the double Otsu, the Bradley's, and the distance-regularized level set evolution is demonstrated. It is validated by the experiments that the proposed method can keep more details and acquire much more satisfying area overlap measure as compared with the other conventional methods.

  16. Local interactions in renormalization methods for Navier-Stokes turbulence

    NASA Technical Reports Server (NTRS)

    Zhou, YE; Vahala, George

    1992-01-01

    Two distinct renormalization-group (RG) approaches are applied to Navier-Stokes turbulence: epsilon-RG and recursive RG. Epsilon-RG takes into account only nonlocal interactions and utilizes an infinitesimal subgrid (unresolvable scale) shell limit. Recursive RG takes into account both nonlocal and local interactions and does not require an infinitesimal subgrid shell limit to be taken. The role of local interactions and the introduction of RG-induced nonlinearities are discussed and clarified.

  17. A practical approach for outdoors distributed target localization in wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Béjar, Benjamín; Zazo, Santiago

    2012-12-01

    Wireless sensor networks are posed as the new communication paradigm where the use of small, low-complexity, and low-power devices is preferred over costly centralized systems. The spectra of potential applications of sensor networks is very wide, ranging from monitoring, surveillance, and localization, among others. Localization is a key application in sensor networks and the use of simple, efficient, and distributed algorithms is of paramount practical importance. Combining convex optimization tools with consensus algorithms we propose a distributed localization algorithm for scenarios where received signal strength indicator readings are used. We approach the localization problem by formulating an alternative problem that uses distance estimates locally computed at each node. The formulated problem is solved by a relaxed version using semidefinite relaxation technique. Conditions under which the relaxed problem yields to the same solution as the original problem are given and a distributed consensus-based implementation of the algorithm is proposed based on an augmented Lagrangian approach and primal-dual decomposition methods. Although suboptimal, the proposed approach is very suitable for its implementation in real sensor networks, i.e., it is scalable, robust against node failures and requires only local communication among neighboring nodes. Simulation results show that running an additional local search around the found solution can yield performance close to the maximum likelihood estimate.

  18. Reactive Gas transport in soil: Kinetics versus Local Equilibrium Approach

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Jia, Ruijan

    2010-05-01

    Gas transport through the unsaturated soil zone was studied using an analytical solution of the gas transport model that is mathematically equivalent to the Two-Region model. The gas transport model includes diffusive and convective gas fluxes, interphase mass transfer between the gas and water phase, and biodegradation. The influence of non-equilibrium phenomena, spatially variable initial conditions, and transient boundary conditions are studied. The objective of this paper is to compare the kinetic approach for interphase mass transfer with the standard local equilibrium approach and to find conditions and time-scales under which the local equilibrium approach is justified. The time-scale of investigation was limited to the day-scale, because this is the relevant scale for understanding gas emission from the soil zone with transient water saturation. For the first time a generalized mass transfer coefficient is proposed that justifies the often used steady-state Thin-Film mass transfer coefficient for small and medium water-saturated aggregates of about 10 mm. The main conclusion from this study is that non-equilibrium mass transfer depends strongly on the temporal and small-scale spatial distribution of water within the unsaturated soil zone. For regions with low water saturation and small water-saturated aggregates (radius about 1 mm) the local equilibrium approach can be used as a first approximation for diffusive gas transport. For higher water saturation and medium radii of water-saturated aggregates (radius about 10 mm) and for convective gas transport, the non-equilibrium effect becomes more and more important if the hydraulic residence time and the Damköhler number decrease. Relative errors can range up to 100% and more. While for medium radii the local equilibrium approach describes the main features both of the spatial concentration profile and the time-dependence of the emission rate, it fails completely for larger aggregates (radius about 100 mm

  19. Managing patients with local anesthetic complications using alternative methods.

    PubMed

    Lu, Dominic P

    2002-01-01

    This article discusses various alternative methods of treating the patient who encounters problems with local anesthetics. Those alternative methods include: acupuncture, hypnosis, sedation, general anesthesia, and antihistamines as a substitute for local anesthetics with more of a focus in using antihistamines as an effective local anesthetic agent. Although not frequently encountered in the clinical setting, allergic reactions to local anesthetics do occur. Various surveys indicate the number of deaths attributed to local anesthesia range from 1:1,500,000 to 1:4,000,000, with oral surgery offices having higher mortality rates than general dentistry offices. This occurs despite clinicians' attention to patient medical histories, aspiration of the local anesthetic syringe during injections, and minimizing the dosage of local anesthetic solutions. Generally speaking, local anesthetics can be divided into two groups: ester of benzoic and aminobenzoic derivatives (cocaine, benzocaine, procaine, tetracaine, butacaine, etc.) or amide-derivatives of xylidine and toluidine groups (lidocaine, mepivacaine, prilocaine a.k.a. Citanest, etc.). Adverse effects include allergic or toxic reactions, as well as negative effects of any vasoconstrictors contained within the local anesthetic solution. This article will concentrate on how to successfully manage patients who have previously encountered allergic reactions.

  20. Local knowledge in community-based approaches to medicinal plant conservation: lessons from India

    PubMed Central

    Shukla, Shailesh; Gardner, James

    2006-01-01

    Background Community-based approaches to conservation of natural resources, in particular medicinal plants, have attracted attention of governments, non governmental organizations and international funding agencies. This paper highlights the community-based approaches used by an Indian NGO, the Rural Communes Medicinal Plant Conservation Centre (RCMPCC). The RCMPCC recognized and legitimized the role of local medicinal knowledge along with other knowledge systems to a wider audience, i.e. higher levels of government. Methods Besides a review of relevant literature, the research used a variety of qualitative techniques, such as semi-structured, in-depth interviews and participant observations in one of the project sites of RCMPCC. Results The review of local medicinal plant knowledge systems reveals that even though medicinal plants and associated knowledge systems (particularly local knowledge) are gaining wider recognition at the global level, the efforts to recognize and promote the un-codified folk systems of medicinal knowledge are still inadequate. In country like India, such neglect is evident through the lack of legal recognition and supporting policies. On the other hand, community-based approaches like local healers' workshops or village biologist programs implemented by RCMPCC are useful in combining both local (folk and codified) and formal systems of medicine. Conclusion Despite the high reliance on the local medicinal knowledge systems for health needs in India, the formal policies and national support structures are inadequate for traditional systems of medicine and almost absent for folk medicine. On the other hand, NGOs like the RCMPCC have demonstrated that community-based and local approaches such as local healer's workshops and village biologist program can synergistically forge linkages between local knowledge with the formal sciences (in this case botany and ecology) and generate positive impacts at various levels. PMID:16603082

  1. Localization Methods for a Mobile Robot in Urban Environments

    DTIC Science & Technology

    2004-10-04

    We have developed a localization system that employs two methods. The first method uses odometry, a compass and tilt sensor, and a global positioning...design, fire and police planning, historical preservation and archaeology, virtual and Scanner Network Camera PTU Sonars GPS DGPS PC Compass Fig. 1...describes the first of our localization meth- ods, based on odometry, a digital compass module and global positioning. Section IV presents our vision

  2. Modelling pathogen transmission: the interrelationship between local and global approaches.

    PubMed Central

    Turner, Joanne; Begon, Michael; Bowers, Roger G

    2003-01-01

    We describe two spatial (cellular automaton) host-pathogen models with contrasting types of transmission, where the biologically realistic transmission mechanisms are based entirely on 'local' interactions. The two models, fixed contact area (FCA) and fixed contact number (FCN), may be viewed as local 'equivalents' of commonly used global density- (and frequency-) dependent models. Their outputs are compared with each other and with the patterns generated by these global terms. In the FCN model, unoccupied cells are bypassed, but in the FCA model these impede pathogen spread, extending the period of the epidemic and reducing the prevalence of infection when the pathogen persists. Crucially, generalized linear modelling reveals that the global transmission terms betaSI and beta'SI/N are equally good at describing transmission in both the FCA and FCN models when infected individuals are homogeneously distributed and N is approximately constant, as at the quasi-equilibrium. However, when N varies, the global frequency-dependent term beta'SI/N is better than the density-dependent one, betaSI, at describing transmission in both the FCA and FCN models. Our approach may be used more generally to compare different local contact structures and select the most appropriate global transmission term. PMID:12590777

  3. Improving Empirical Approaches to Estimating Local Greenhouse Gas Emissions

    NASA Astrophysics Data System (ADS)

    Blackhurst, M.; Azevedo, I. L.; Lattanzi, A.

    2016-12-01

    Evidence increasingly indicates our changing climate will have significant global impacts on public health, economies, and ecosystems. As a result, local governments have become increasingly interested in climate change mitigation. In the U.S., cities and counties representing nearly 15% of the domestic population plan to reduce 300 million metric tons of greenhouse gases over the next 40 years (or approximately 1 ton per capita). Local governments estimate greenhouse gas emissions to establish greenhouse gas mitigation goals and select supporting mitigation measures. However, current practices produce greenhouse gas estimates - also known as a "greenhouse gas inventory " - of empirical quality often insufficient for robust mitigation decision making. Namely, current mitigation planning uses sporadic, annual, and deterministic estimates disaggregated by broad end use sector, obscuring sources of emissions uncertainty, variability, and exogeneity that influence mitigation opportunities. As part of AGU's Thriving Earth Exchange, Ari Lattanzi of City of Pittsburgh, PA recently partnered with Dr. Inez Lima Azevedo (Carnegie Mellon University) and Dr. Michael Blackhurst (University of Pittsburgh) to improve the empirical approach to characterizing Pittsburgh's greenhouse gas emissions. The project will produce first-order estimates of the underlying sources of uncertainty, variability, and exogeneity influencing Pittsburgh's greenhouse gases and discuss implications of mitigation decision making. The results of the project will enable local governments to collect more robust greenhouse gas inventories to better support their mitigation goals and improve measurement and verification efforts.

  4. Multilevel local refinement and multigrid methods for 3-D turbulent flow

    SciTech Connect

    Liao, C.; Liu, C.; Sung, C.H.; Huang, T.T.

    1996-12-31

    A numerical approach based on multigrid, multilevel local refinement, and preconditioning methods for solving incompressible Reynolds-averaged Navier-Stokes equations is presented. 3-D turbulent flow around an underwater vehicle is computed. 3 multigrid levels and 2 local refinement grid levels are used. The global grid is 24 x 8 x 12. The first patch is 40 x 16 x 20 and the second patch is 72 x 32 x 36. 4th order artificial dissipation are used for numerical stability. The conservative artificial compressibility method are used for further improvement of convergence. To improve the accuracy of coarse/fine grid interface of local refinement, flux interpolation method for refined grid boundary is used. The numerical results are in good agreement with experimental data. The local refinement can improve the prediction accuracy significantly. The flux interpolation method for local refinement can keep conservation for a composite grid, therefore further modify the prediction accuracy.

  5. Global and Local Sensitivity Analysis Methods for a Physical System

    ERIC Educational Resources Information Center

    Morio, Jerome

    2011-01-01

    Sensitivity analysis is the study of how the different input variations of a mathematical model influence the variability of its output. In this paper, we review the principle of global and local sensitivity analyses of a complex black-box system. A simulated case of application is given at the end of this paper to compare both approaches.…

  6. Global and Local Sensitivity Analysis Methods for a Physical System

    ERIC Educational Resources Information Center

    Morio, Jerome

    2011-01-01

    Sensitivity analysis is the study of how the different input variations of a mathematical model influence the variability of its output. In this paper, we review the principle of global and local sensitivity analyses of a complex black-box system. A simulated case of application is given at the end of this paper to compare both approaches.…

  7. Damping filter method for obtaining spatially localized solutions.

    PubMed

    Teramura, Toshiki; Toh, Sadayoshi

    2014-05-01

    Spatially localized structures are key components of turbulence and other spatiotemporally chaotic systems. From a dynamical systems viewpoint, it is desirable to obtain corresponding exact solutions, though their existence is not guaranteed. A damping filter method is introduced to obtain variously localized solutions and adapted in two typical cases. This method introduces a spatially selective damping effect to make a good guess at the exact solution, and we can obtain an exact solution through a continuation with the damping amplitude. The first target is a steady solution to the Swift-Hohenberg equation, which is a representative of bistable systems in which localized solutions coexist and a model for spanwise-localized cases. Not only solutions belonging to the well-known snaking branches but also those belonging to isolated branches known as "isolas" are found with continuation paths between them in phase space extended with the damping amplitude. This indicates that this spatially selective excitation mechanism has an advantage in searching spatially localized solutions. The second target is a spatially localized traveling-wave solution to the Kuramoto-Sivashinsky equation, which is a model for streamwise-localized cases. Since the spatially selective damping effect breaks Galilean and translational invariances, the propagation velocity cannot be determined uniquely while the damping is active, and a singularity arises when these invariances are recovered. We demonstrate that this singularity can be avoided by imposing a simple condition, and a localized traveling-wave solution is obtained with a specific propagation speed.

  8. Damping filter method for obtaining spatially localized solutions

    NASA Astrophysics Data System (ADS)

    Teramura, Toshiki; Toh, Sadayoshi

    2014-05-01

    Spatially localized structures are key components of turbulence and other spatiotemporally chaotic systems. From a dynamical systems viewpoint, it is desirable to obtain corresponding exact solutions, though their existence is not guaranteed. A damping filter method is introduced to obtain variously localized solutions and adapted in two typical cases. This method introduces a spatially selective damping effect to make a good guess at the exact solution, and we can obtain an exact solution through a continuation with the damping amplitude. The first target is a steady solution to the Swift-Hohenberg equation, which is a representative of bistable systems in which localized solutions coexist and a model for spanwise-localized cases. Not only solutions belonging to the well-known snaking branches but also those belonging to isolated branches known as "isolas" are found with continuation paths between them in phase space extended with the damping amplitude. This indicates that this spatially selective excitation mechanism has an advantage in searching spatially localized solutions. The second target is a spatially localized traveling-wave solution to the Kuramoto-Sivashinsky equation, which is a model for streamwise-localized cases. Since the spatially selective damping effect breaks Galilean and translational invariances, the propagation velocity cannot be determined uniquely while the damping is active, and a singularity arises when these invariances are recovered. We demonstrate that this singularity can be avoided by imposing a simple condition, and a localized traveling-wave solution is obtained with a specific propagation speed.

  9. Localization of MEG human brain responses to retinotopic visual stimuli with contrasting source reconstruction approaches.

    PubMed

    Cicmil, Nela; Bridge, Holly; Parker, Andrew J; Woolrich, Mark W; Krug, Kristine

    2014-01-01

    Magnetoencephalography (MEG) allows the physiological recording of human brain activity at high temporal resolution. However, spatial localization of the source of the MEG signal is an ill-posed problem as the signal alone cannot constrain a unique solution and additional prior assumptions must be enforced. An adequate source reconstruction method for investigating the human visual system should place the sources of early visual activity in known locations in the occipital cortex. We localized sources of retinotopic MEG signals from the human brain with contrasting reconstruction approaches (minimum norm, multiple sparse priors, and beamformer) and compared these to the visual retinotopic map obtained with fMRI in the same individuals. When reconstructing brain responses to visual stimuli that differed by angular position, we found reliable localization to the appropriate retinotopic visual field quadrant by a minimum norm approach and by beamforming. Retinotopic map eccentricity in accordance with the fMRI map could not consistently be localized using an annular stimulus with any reconstruction method, but confining eccentricity stimuli to one visual field quadrant resulted in significant improvement with the minimum norm. These results inform the application of source analysis approaches for future MEG studies of the visual system, and indicate some current limits on localization accuracy of MEG signals.

  10. Localization of MEG human brain responses to retinotopic visual stimuli with contrasting source reconstruction approaches

    PubMed Central

    Cicmil, Nela; Bridge, Holly; Parker, Andrew J.; Woolrich, Mark W.; Krug, Kristine

    2014-01-01

    Magnetoencephalography (MEG) allows the physiological recording of human brain activity at high temporal resolution. However, spatial localization of the source of the MEG signal is an ill-posed problem as the signal alone cannot constrain a unique solution and additional prior assumptions must be enforced. An adequate source reconstruction method for investigating the human visual system should place the sources of early visual activity in known locations in the occipital cortex. We localized sources of retinotopic MEG signals from the human brain with contrasting reconstruction approaches (minimum norm, multiple sparse priors, and beamformer) and compared these to the visual retinotopic map obtained with fMRI in the same individuals. When reconstructing brain responses to visual stimuli that differed by angular position, we found reliable localization to the appropriate retinotopic visual field quadrant by a minimum norm approach and by beamforming. Retinotopic map eccentricity in accordance with the fMRI map could not consistently be localized using an annular stimulus with any reconstruction method, but confining eccentricity stimuli to one visual field quadrant resulted in significant improvement with the minimum norm. These results inform the application of source analysis approaches for future MEG studies of the visual system, and indicate some current limits on localization accuracy of MEG signals. PMID:24904268

  11. Measuring Filament Orientation: A New Quantitative, Local Approach

    NASA Astrophysics Data System (ADS)

    Green, C.-E.; Dawson, J. R.; Cunningham, M. R.; Jones, P. A.; Novak, G.; Fissel, L. M.

    2017-09-01

    The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

  12. Spectral Approach to Anderson Localization in a Disordered 2D Complex Plasma Crystal

    NASA Astrophysics Data System (ADS)

    Kostadinova, Eva; Liaw, Constanze; Matthews, Lorin; Busse, Kyle; Hyde, Truell

    2016-10-01

    In condensed matter, a crystal without impurities acts like a perfect conductor for a travelling wave-particle. As the level of impurities reaches a critical value, the resistance in the crystal increases and the travelling wave-particle experiences a transition from an extended to a localized state, which is called Anderson localization. Due to its wide applicability, the subject of Anderson localization has grown into a rich field in both physics and mathematics. Here, we introduce the mathematics behind the spectral approach to localization in infinite disordered systems and provide physical interpretation in context of both quantum mechanics and classical physics. We argue that the spectral analysis is an important contribution to localization theory since it avoids issues related to the use of boundary conditions, scaling, and perturbation. To test accuracy and applicability we apply the spectral approach to the case of a 2D hexagonal complex plasma crystal used as a macroscopic analog for a graphene-like medium. Complex plasma crystals exhibit characteristic distance and time scales, which are easily observable by video microscopy. As such, these strongly coupled many-particle systems are ideal for the study of localization phenomena. The goal of this research is to both expand the spectral method into the classical regime and show the potential of complex plasma as a macroscopic tool for localization experiments. NSF / DOE funding is gratefully acknowledged - PHY1414523 & PHY1262031.

  13. Multi-Scale Jacobi Method for Anderson Localization

    NASA Astrophysics Data System (ADS)

    Imbrie, John Z.

    2015-11-01

    A new KAM-style proof of Anderson localization is obtained. A sequence of local rotations is defined, such that off-diagonal matrix elements of the Hamiltonian are driven rapidly to zero. This leads to the first proof via multi-scale analysis of exponential decay of the eigenfunction correlator (this implies strong dynamical localization). The method has been used in recent work on many-body localization (Imbrie in On many-body localization for quantum spin chains, arXiv:1403.7837 , 2014).

  14. Perturbative approach for non local and high order derivative theories

    SciTech Connect

    Avilez, Ana A.; Vergara, J. David

    2009-04-20

    We propose a reduction method of classical phase space of high order derivative theories in singular and non singular cases. The mechanism is to reduce the high order phase space by imposing suplementary constraints, such that the evolution takes place in a submanifold where high order degrees of freedom are absent. The reduced theory is ordinary and is cured of the usual high order theories diseases, it approaches well low energy dynamics.

  15. Local and Non-local Regularization Techniques in Emission (PET/SPECT) Tomographic Image Reconstruction Methods.

    PubMed

    Ahmad, Munir; Shahzad, Tasawar; Masood, Khalid; Rashid, Khalid; Tanveer, Muhammad; Iqbal, Rabail; Hussain, Nasir; Shahid, Abubakar; Fazal-E-Aleem

    2016-06-01

    Emission tomographic image reconstruction is an ill-posed problem due to limited and noisy data and various image-degrading effects affecting the data and leads to noisy reconstructions. Explicit regularization, through iterative reconstruction methods, is considered better to compensate for reconstruction-based noise. Local smoothing and edge-preserving regularization methods can reduce reconstruction-based noise. However, these methods produce overly smoothed images or blocky artefacts in the final image because they can only exploit local image properties. Recently, non-local regularization techniques have been introduced, to overcome these problems, by incorporating geometrical global continuity and connectivity present in the objective image. These techniques can overcome drawbacks of local regularization methods; however, they also have certain limitations, such as choice of the regularization function, neighbourhood size or calibration of several empirical parameters involved. This work compares different local and non-local regularization techniques used in emission tomographic imaging in general and emission computed tomography in specific for improved quality of the resultant images.

  16. Local constitutive behavior of paper determined by an inverse method

    Treesearch

    John M. Considine; C. Tim Scott; Roland Gleisner; Junyong Zhu

    2006-01-01

    The macroscopic behavior of paper is governed by small-scale behavior. Intuitively, we know that a small-scale defect with a paper sheet effectively determines the global behavior of the sheet. In this work, we describe a method to evaluate the local constitutive behavior of paper by using an inverse method.

  17. Construction of Lyapunov functions by the localization method

    NASA Astrophysics Data System (ADS)

    Krishchenko, A. P.; Kanatnikov, A. N.

    2017-07-01

    In this paper, we examine the problem of construction of Lyapunov functions for asymptotically stable equilibrium points. We exploit conditions of asymptotic stability in terms of compact invariant sets and positively invariant sets. Our results are methods of verification of these conditions and construction of Lyapunov functions by the localization method of compact invariant sets. These results are illustrated by an example.

  18. Influence of skull modeling approaches on EEG source localization.

    PubMed

    Montes-Restrepo, Victoria; van Mierlo, Pieter; Strobbe, Gregor; Staelens, Steven; Vandenberghe, Stefaan; Hallez, Hans

    2014-01-01

    Electroencephalographic source localization (ESL) relies on an accurate model representing the human head for the computation of the forward solution. In this head model, the skull is of utmost importance due to its complex geometry and low conductivity compared to the other tissues inside the head. We investigated the influence of using different skull modeling approaches on ESL. These approaches, consisting in skull conductivity and geometry modeling simplifications, make use of X-ray computed tomography (CT) and magnetic resonance (MR) images to generate seven different head models. A head model with an accurately segmented skull from CT images, including spongy and compact bone compartments as well as some air-filled cavities, was used as the reference model. EEG simulations were performed for a configuration of 32 and 128 electrodes, and for both noiseless and noisy data. The results show that skull geometry simplifications have a larger effect on ESL than those of the conductivity modeling. This suggests that accurate skull modeling is important in order to achieve reliable results for ESL that are useful in a clinical environment. We recommend the following guidelines to be taken into account for skull modeling in the generation of subject-specific head models: (i) If CT images are available, i.e., if the geometry of the skull and its different tissue types can be accurately segmented, the conductivity should be modeled as isotropic heterogeneous. The spongy bone might be segmented as an erosion of the compact bone; (ii) when only MR images are available, the skull base should be represented as accurately as possible and the conductivity can be modeled as isotropic heterogeneous, segmenting the spongy bone directly from the MR image; (iii) a large number of EEG electrodes should be used to obtain high spatial sampling, which reduces the localization errors at realistic noise levels.

  19. Localized Surface Plasmon Resonance Biosensing: Current Challenges and Approaches

    PubMed Central

    Unser, Sarah; Bruzas, Ian; He, Jie; Sagle, Laura

    2015-01-01

    Localized surface plasmon resonance (LSPR) has emerged as a leader among label-free biosensing techniques in that it offers sensitive, robust, and facile detection. Traditional LSPR-based biosensing utilizes the sensitivity of the plasmon frequency to changes in local index of refraction at the nanoparticle surface. Although surface plasmon resonance technologies are now widely used to measure biomolecular interactions, several challenges remain. In this article, we have categorized these challenges into four categories: improving sensitivity and limit of detection, selectivity in complex biological solutions, sensitive detection of membrane-associated species, and the adaptation of sensing elements for point-of-care diagnostic devices. The first section of this article will involve a conceptual discussion of surface plasmon resonance and the factors affecting changes in optical signal detected. The following sections will discuss applications of LSPR biosensing with an emphasis on recent advances and approaches to overcome the four limitations mentioned above. First, improvements in limit of detection through various amplification strategies will be highlighted. The second section will involve advances to improve selectivity in complex media through self-assembled monolayers, “plasmon ruler” devices involving plasmonic coupling, and shape complementarity on the nanoparticle surface. The following section will describe various LSPR platforms designed for the sensitive detection of membrane-associated species. Finally, recent advances towards multiplexed and microfluidic LSPR-based devices for inexpensive, rapid, point-of-care diagnostics will be discussed. PMID:26147727

  20. Fractional Burgers equation with nonlinear non-locality: Spectral vanishing viscosity and local discontinuous Galerkin methods

    NASA Astrophysics Data System (ADS)

    Mao, Zhiping; Karniadakis, George Em

    2017-05-01

    We consider the viscous Burgers equation with a fractional nonlinear term as a model involving non-local nonlinearities in conservation laws, which, surprisingly, has an analytical solution obtained by a fractional extension of the Hopf-Cole transformation. We use this model and its inviscid limit to develop stable spectral and discontinuous Galerkin spectral element methods by employing the concept of spectral vanishing viscosity (SVV). For the global spectral method, SVV is very effective and the computational cost is O (N2), which is essentially the same as for the standard Burgers equation. We also develop a local discontinuous Galerkin (LDG) spectral element method to improve the accuracy around discontinuities, and we again stabilize the LDG method with the SVV operator. Finally, we solve numerically the inviscid fractional Burgers equation both with the spectral and the spectral element LDG methods. We study systematically the stability and convergence of both methods and determine the effectiveness of each method for different parameters.

  1. Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

    NASA Astrophysics Data System (ADS)

    Mondal, Wasim Raja; Vidhyadhiraja, N. S.; Berlijn, T.; Moreno, Juana; Jarrell, M.

    2017-07-01

    The effect of disorder on lattice vibrational modes has been a topic of interest for several decades. In this work, we employ a Green's function based approach, namely, the dynamical cluster approximation (DCA), to investigate phonons in mass-disordered systems. Detailed benchmarks with previous exact calculations are used to validate the method in a wide parameter space. An extension of the method, namely, the typical medium DCA (TMDCA), is used to study Anderson localization of phonons in three dimensions. We show that, for binary isotopic disorder, lighter impurities induce localized modes beyond the bandwidth of the host system, while heavier impurities lead to a partial localization of the low-frequency acoustic modes. For a uniform (box) distribution of masses, the physical spectrum is shown to develop long tails comprising mostly localized modes. The mobility edge separating extended and localized modes, obtained through the TMDCA, agrees well with results from the transfer matrix method. A reentrance behavior of the mobility edge with increasing disorder is found that is similar to, but somewhat more pronounced than, the behavior in disordered electronic systems. Our work establishes a computational approach, which recovers the thermodynamic limit, is versatile and computationally inexpensive, to investigate lattice vibrations in disordered lattice systems.

  2. Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

    DOE PAGES

    Mondal, Wasim Raja; Vidhyadhiraja, N. S.; Berlijn, Tom; ...

    2017-07-20

    The effect of disorder on lattice vibrational modes has been a topic of interest for several decades. In this work, we employ a Green's function based approach, namely, the dynamical cluster approximation (DCA), to investigate phonons in mass-disordered systems. Detailed benchmarks with previous exact calculations are used to validate the method in a wide parameter space. An extension of the method, namely, the typical medium DCA (TMDCA), is used to study Anderson localization of phonons in three dimensions. We show that, for binary isotopic disorder, lighter impurities induce localized modes beyond the bandwidth of the host system, while heavier impuritiesmore » lead to a partial localization of the low-frequency acoustic modes. For a uniform (box) distribution of masses, the physical spectrum is shown to develop long tails comprising mostly localized modes. The mobility edge separating extended and localized modes, obtained through the TMDCA, agrees well with results from the transfer matrix method. A reentrance behavior of the mobility edge with increasing disorder is found that is similar to, but somewhat more pronounced than, the behavior in disordered electronic systems. As a result, our work establishes a computational approach, which recovers the thermodynamic limit, is versatile and computationally inexpensive, to investigate lattice vibrations in disordered lattice systems.« less

  3. Sound source localization method in an environment with flow based on Amiet-IMACS

    NASA Astrophysics Data System (ADS)

    Wei, Long; Li, Min; Qin, Sheng; Fu, Qiang; Yang, Debin

    2017-05-01

    A sound source localization method is proposed to localize and analyze the sound source in an environment with airflow. It combines the improved mapping of acoustic correlated sources (IMACS) method and Amiet's method, and is called Amiet-IMACS. It can localize uncorrelated and correlated sound sources with airflow. To implement this approach, Amiet's method is used to correct the sound propagation path in 3D, which improves the accuracy of the array manifold matrix and decreases the position error of the localized source. Then, the mapping of acoustic correlated sources (MACS) method, which is as a high-resolution sound source localization algorithm, is improved by self-adjusting the constraint parameter at each irritation process to increase convergence speed. A sound source localization experiment using a pair of loud speakers in an anechoic wind tunnel under different flow speeds is conducted. The experiment exhibits the advantage of Amiet-IMACS in localizing a more accurate sound source position compared with implementing IMACS alone in an environment with flow. Moreover, the aerodynamic noise produced by a NASA EPPLER 862 STRUT airfoil model in airflow with a velocity of 80 m/s is localized using the proposed method, which further proves its effectiveness in a flow environment. Finally, the relationship between the source position of this airfoil model and its frequency, along with its generation mechanism, is determined and interpreted.

  4. Simple Test Functions in Meshless Local Petrov-Galerkin Methods

    NASA Technical Reports Server (NTRS)

    Raju, Ivatury S.

    2016-01-01

    Two meshless local Petrov-Galerkin (MLPG) methods based on two different trial functions but that use a simple linear test function were developed for beam and column problems. These methods used generalized moving least squares (GMLS) and radial basis (RB) interpolation functions as trial functions. These two methods were tested on various patch test problems. Both methods passed the patch tests successfully. Then the methods were applied to various beam vibration problems and problems involving Euler and Beck's columns. Both methods yielded accurate solutions for all problems studied. The simple linear test function offers considerable savings in computing efforts as the domain integrals involved in the weak form are avoided. The two methods based on this simple linear test function method produced accurate results for frequencies and buckling loads. Of the two methods studied, the method with radial basis trial functions is very attractive as the method is simple, accurate, and robust.

  5. Ultrasound localization of the sacral plexus using a parasacral approach.

    PubMed

    Ben-Ari, Alon Y; Joshi, Rama; Uskova, Anna; Chelly, Jacques E

    2009-06-01

    In this report, we describe the feasibility of locating the sacral plexus nerve using a parasacral approach and an ultrasound-guided technique. The parasacral region using a curved probe (2-5 MHz) was scanned in 17 patients in search of the medial border of the ischial bone and the lateral border of the sacrum, which represent the limit of the greater sciatic foramen. In addition, attempts were made to identify the piriformis muscles and the gluteal arteries. The sacral plexus was identified at the level of the sciatic foramen as a round hyperechoic structure. The gluteal arteries were identified in 10 of 17 patients, but we failed to positively identify the piriformis muscle in any patient. To confirm localization of the sacral plexus, an insulated needle attached to a nerve stimulator was advanced and, in each case, a sacral plexus motor response was elicited (plantar flexion-12, dorsal flexion-1, hamstring muscle stimulation-3, gastrocnemius muscle stimulation-1-not recorded) at a current between 0.2 and 0.5 mA. No complications were observed. This report confirms the feasibility of using ultrasound to locate the sacral plexus using a parasacral approach.

  6. Robust Statistical Approaches for RSS-Based Floor Detection in Indoor Localization

    PubMed Central

    Razavi, Alireza; Valkama, Mikko; Lohan, Elena Simona

    2016-01-01

    Floor detection for indoor 3D localization of mobile devices is currently an important challenge in the wireless world. Many approaches currently exist, but usually the robustness of such approaches is not addressed or investigated. The goal of this paper is to show how to robustify the floor estimation when probabilistic approaches with a low number of parameters are employed. Indeed, such an approach would allow a building-independent estimation and a lower computing power at the mobile side. Four robustified algorithms are to be presented: a robust weighted centroid localization method, a robust linear trilateration method, a robust nonlinear trilateration method, and a robust deconvolution method. The proposed approaches use the received signal strengths (RSS) measured by the Mobile Station (MS) from various heard WiFi access points (APs) and provide an estimate of the vertical position of the MS, which can be used for floor detection. We will show that robustification can indeed increase the performance of the RSS-based floor detection algorithms. PMID:27258279

  7. Robust Statistical Approaches for RSS-Based Floor Detection in Indoor Localization.

    PubMed

    Razavi, Alireza; Valkama, Mikko; Lohan, Elena Simona

    2016-05-31

    Floor detection for indoor 3D localization of mobile devices is currently an important challenge in the wireless world. Many approaches currently exist, but usually the robustness of such approaches is not addressed or investigated. The goal of this paper is to show how to robustify the floor estimation when probabilistic approaches with a low number of parameters are employed. Indeed, such an approach would allow a building-independent estimation and a lower computing power at the mobile side. Four robustified algorithms are to be presented: a robust weighted centroid localization method, a robust linear trilateration method, a robust nonlinear trilateration method, and a robust deconvolution method. The proposed approaches use the received signal strengths (RSS) measured by the Mobile Station (MS) from various heard WiFi access points (APs) and provide an estimate of the vertical position of the MS, which can be used for floor detection. We will show that robustification can indeed increase the performance of the RSS-based floor detection algorithms.

  8. An FPT Approach for Predicting Protein Localization from Yeast Genomic Data

    PubMed Central

    Wang, Jin; Li, Chunhe; Wang, Erkang; Wang, Xidi

    2011-01-01

    Accurately predicting the localization of proteins is of paramount importance in the quest to determine their respective functions within the cellular compartment. Because of the continuous and rapid progress in the fields of genomics and proteomics, more data are available now than ever before. Coincidentally, data mining methods been developed and refined in order to handle this experimental windfall, thus allowing the scientific community to quantitatively address long-standing questions such as that of protein localization. Here, we develop a frequent pattern tree (FPT) approach to generate a minimum set of rules (mFPT) for predicting protein localization. We acquire a series of rules according to the features of yeast genomic data. The mFPT prediction accuracy is benchmarked against other commonly used methods such as Bayesian networks and logistic regression under various statistical measures. Our results show that mFPT gave better performance than other approaches in predicting protein localization. Meanwhile, setting 0.65 as the minimum hit-rate, we obtained 138 proteins that mFPT predicted differently than the simple naive bayesian method (SNB). In our analysis of these 138 proteins, we present novel predictions for the location for 17 proteins, which currently do not have any defined localization. These predictions can serve as putative annotations and should provide preliminary clues for experimentalists. We also compared our predictions against the eukaryotic subcellular localization database and related predictions by others on protein localization. Our method is quite generalized and can thus be applied to discover the underlying rules for protein-protein interactions, genomic interactions, and structure-function relationships, as well as those of other fields of research. PMID:21283516

  9. Community-Based Outdoor Education Using a Local Approach to Conservation

    ERIC Educational Resources Information Center

    Maeda, Kazushi

    2005-01-01

    Local people of a community interact with nature in a way that is mediated by their local cultures and shape their own environment. We need a local approach to conservation for the local environment adding to the political or technological approaches for global environmental problems such as the destruction of the ozone layer or global warming.…

  10. Community-Based Outdoor Education Using a Local Approach to Conservation

    ERIC Educational Resources Information Center

    Maeda, Kazushi

    2005-01-01

    Local people of a community interact with nature in a way that is mediated by their local cultures and shape their own environment. We need a local approach to conservation for the local environment adding to the political or technological approaches for global environmental problems such as the destruction of the ozone layer or global warming.…

  11. The Case Method Approach in Reading Education.

    ERIC Educational Resources Information Center

    Rasinski, Timothy V.

    A new approach to the teaching of reading education is needed which is not focused totally on method but (1) is sensitive to the situations and contexts in which methodologies are to be applied; (2) encourages the active participation of students and values their views about reading pedagogy; and (3) creates a forum in which ideas grounded in the…

  12. Slope failure analysis using local minimum factor-of-safety approach

    SciTech Connect

    Huang, S.L.; Yamasaki, Kenji

    1993-12-01

    An approach using the minimum factors of safety against local failures is presented. The state of the effective stresses in a slope is calculated by the finite element method with the Drucker-Prager nonlinear stress-strain relationship. The shear strength of soil is estimated based on the Mohr-Coulomb failure criterion. A critical slip surface is defined by connecting those local failure points in a slope along their directions of slippage. The factor of safety obtained by the proposed method is in good agreement with that determined by Bishop`s and Sarma`s methods. The locations of the critical slip surfaces, however, deviate slightly from Bishop`s method due possibly to the assumptions made in the formulation of each method.

  13. Inverse-problem approach for particle digital holography: accurate location based on local optimization.

    PubMed

    Soulez, Ferréol; Denis, Loïc; Fournier, Corinne; Thiébaut, Eric; Goepfert, Charles

    2007-04-01

    We propose a microparticle localization scheme in digital holography. Most conventional digital holography methods are based on Fresnel transform and present several problems such as twin-image noise, border effects, and other effects. To avoid these difficulties, we propose an inverse-problem approach, which yields the optimal particle set that best models the observed hologram image. We resolve this global optimization problem by conventional particle detection followed by a local refinement for each particle. Results for both simulated and real digital holograms show strong improvement in the localization of the particles, particularly along the depth dimension. In our simulations, the position precision is > or =1 microm rms. Our results also show that the localization precision does not deteriorate for particles near the edge of the field of view.

  14. Local weak form meshless techniques based on the radial point interpolation (RPI) method and local boundary integral equation (LBIE) method to evaluate European and American options

    NASA Astrophysics Data System (ADS)

    Rad, Jamal Amani; Parand, Kourosh; Abbasbandy, Saeid

    2015-05-01

    For the first time in mathematical finance field, we propose the local weak form meshless methods for option pricing; especially in this paper we select and analysis two schemes of them named local boundary integral equation method (LBIE) based on moving least squares approximation (MLS) and local radial point interpolation (LRPI) based on Wu's compactly supported radial basis functions (WCS-RBFs). LBIE and LRPI schemes are the truly meshless methods, because, a traditional non-overlapping, continuous mesh is not required, either for the construction of the shape functions, or for the integration of the local sub-domains. In this work, the American option which is a free boundary problem, is reduced to a problem with fixed boundary using a Richardson extrapolation technique. Then the θ -weighted scheme is employed for the time derivative. Stability analysis of the methods is analyzed and performed by the matrix method. In fact, based on an analysis carried out in the present paper, the methods are unconditionally stable for implicit Euler (θ = 0) and Crank-Nicolson (θ = 0.5) schemes. It should be noted that LBIE and LRPI schemes lead to banded and sparse system matrices. Therefore, we use a powerful iterative algorithm named the Bi-conjugate gradient stabilized method (BCGSTAB) to get rid of this system. Numerical experiments are presented showing that the LBIE and LRPI approaches are extremely accurate and fast.

  15. Local discretization method for overdamped Brownian motion on a potential with multiple deep wells

    NASA Astrophysics Data System (ADS)

    Nguyen, P. T. T.; Challis, K. J.; Jack, M. W.

    2016-11-01

    We present a general method for transforming the continuous diffusion equation describing overdamped Brownian motion on a time-independent potential with multiple deep wells to a discrete master equation. The method is based on an expansion in localized basis states of local metastable potentials that match the full potential in the region of each potential well. Unlike previous basis methods for discretizing Brownian motion on a potential, this approach is valid for periodic potentials with varying multiple deep wells per period and can also be applied to nonperiodic systems. We apply the method to a range of potentials and find that potential wells that are deep compared to five times the thermal energy can be associated with a discrete localized state while shallower wells are better incorporated into the local metastable potentials of neighboring deep potential wells.

  16. Local discretization method for overdamped Brownian motion on a potential with multiple deep wells.

    PubMed

    Nguyen, P T T; Challis, K J; Jack, M W

    2016-11-01

    We present a general method for transforming the continuous diffusion equation describing overdamped Brownian motion on a time-independent potential with multiple deep wells to a discrete master equation. The method is based on an expansion in localized basis states of local metastable potentials that match the full potential in the region of each potential well. Unlike previous basis methods for discretizing Brownian motion on a potential, this approach is valid for periodic potentials with varying multiple deep wells per period and can also be applied to nonperiodic systems. We apply the method to a range of potentials and find that potential wells that are deep compared to five times the thermal energy can be associated with a discrete localized state while shallower wells are better incorporated into the local metastable potentials of neighboring deep potential wells.

  17. A method of periodic pattern localization on document images

    NASA Astrophysics Data System (ADS)

    Chernov, Timofey S.; Nikolaev, Dmitry P.; Kliatskine, Vitali M.

    2015-12-01

    Periodic patterns often present on document images as holograms, watermarks or guilloche elements which are mostly used for fraud protection. Localization of such patterns lets an embedded OCR system to vary its settings depending on pattern presence in particular image regions and improves the precision of pattern removal to preserve as much useful data as possible. Many document images' noise detection and removal methods deal with unstructured noise or clutter on documents with simple background. In this paper we propose a method of periodic pattern localization on document images which uses discrete Fourier transform that works well on documents with complex background.

  18. Galaxy formation with local photoionization feedback - I. Methods

    NASA Astrophysics Data System (ADS)

    Kannan, R.; Stinson, G. S.; Macciò, A. V.; Hennawi, J. F.; Woods, R.; Wadsley, J.; Shen, S.; Robitaille, T.; Cantalupo, S.; Quinn, T. R.; Christensen, C.

    2014-01-01

    We present a first study of the effect of local photoionizing radiation on gas cooling in smoothed particle hydrodynamics simulations of galaxy formation. We explore the combined effect of ionizing radiation from young and old stellar populations. The method computes the effect of multiple radiative sources using the same tree algorithm as used for gravity, so it is computationally efficient and well resolved. The method foregoes calculating absorption and scattering in favour of a constant escape fraction for young stars to keep the calculation efficient enough to simulate the entire evolution of a galaxy in a cosmological context to the present day. This allows us to quantify the effect of the local photoionization feedback through the whole history of a galaxy's formation. The simulation of a Milky Way-like galaxy using the local photoionization model forms ˜40 per cent less stars than a simulation that only includes a standard uniform background UV field. The local photoionization model decreases star formation by increasing the cooling time of the gas in the halo and increasing the equilibrium temperature of dense gas in the disc. Coupling the local radiation field to gas cooling from the halo provides a preventive feedback mechanism which keeps the central disc light and produces slowly rising rotation curves without resorting to extreme feedback mechanisms. These preliminary results indicate that the effect of local photoionizing sources is significant and should not be ignored in models of galaxy formation.

  19. Hierarchy-Direction Selective Approach for Locally Adaptive Sparse Grids

    SciTech Connect

    Stoyanov, Miroslav K

    2013-09-01

    We consider the problem of multidimensional adaptive hierarchical interpolation. We use sparse grids points and functions that are induced from a one dimensional hierarchical rule via tensor products. The classical locally adaptive sparse grid algorithm uses an isotropic refinement from the coarser to the denser levels of the hierarchy. However, the multidimensional hierarchy provides a more complex structure that allows for various anisotropic and hierarchy selective refinement techniques. We consider the more advanced refinement techniques and apply them to a number of simple test functions chosen to demonstrate the various advantages and disadvantages of each method. While there is no refinement scheme that is optimal for all functions, the fully adaptive family-direction-selective technique is usually more stable and requires fewer samples.

  20. A novel local learning based approach with application to breast cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Xu, Songhua; Tourassi, Georgia

    2012-03-01

    In this paper, we introduce a new local learning based approach and apply it for the well-studied problem of breast cancer diagnosis using BIRADS-based mammographic features. To learn from our clinical dataset the latent relationship between these features and the breast biopsy result, our method first dynamically partitions the whole sample population into multiple sub-population groups through stochastically searching the sample population clustering space. Each encountered clustering scheme in our online searching process is then used to create a certain sample population partition plan. For every resultant sub-population group identified according to a partition plan, our method then trains a dedicated local learner to capture the underlying data relationship. In our study, we adopt the linear logistic regression model as our local learning method's base learner. Such a choice is made both due to the well-understood linear nature of the problem, which is compellingly revealed by a rich body of prior studies, and the computational efficiency of linear logistic regression--the latter feature allows our local learning method to more effectively perform its search in the sample population clustering space. Using a database of 850 biopsy-proven cases, we compared the performance of our method with a large collection of publicly available state-of-the-art machine learning methods and successfully demonstrated its performance advantage with statistical significance.

  1. Data Processing Approach for Localizing Bio-magnetic Sources in the Brain

    NASA Astrophysics Data System (ADS)

    Pai, Hung-I.; Tseng, Chih-Yuan; Lee, H. C.

    2007-07-01

    Magnetoencephalography (MEG) provides dynamic spatial-temporal insight for neural activities in the cortex. Because the possible number of sources is far greater than the number of MEG detectors, the proposition to localize sources directly from MEG data is ill-posed. Here we develop a novel approach based on a sequence of data processing procedures that includes a clustering process, an intersection analysis, and an application of the maximum entropy method. We examine the performance of our method and compare it with the minimum-norm least-square inverse method using an artificial noisy MEG data.

  2. An efficient local cascade defense method in complex networks

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Yuan; Ma, Jian-Feng

    Cascading failures in networked systems often lead to catastrophic consequence. Defending cascading failure propagation by employing local load redistribution method is an efficient way. Given initial load of every node, the key of improving network robustness against cascading failures is to maximally defend cascade propagation with minimum total extra capacity of all nodes. With finite total extra capacity of all nodes, we first discuss three general extra capacity distributions including degree-based distribution (DD), average distribution (AD) and random distribution (RD). To sufficiently use the total spare capacity (SC) of all neighboring nodes of a failed node, then we propose a novel SC-based local load redistribution mechanism to improve the cascade defense ability of network. We investigate the network robustness against cascading failures induced by a single node failure under the three extra capacity distributions in both scale-free networks and random networks. Compared with the degree-based (DB) local load redistribution method, our SC method achieves higher robustness under all of the three extra capacity distributions. The extensive simulation results can well confirm the effectiveness of the SC local load redistribution method.

  3. Globalizing Education, Educating the Local: How Method Made Us Mad

    ERIC Educational Resources Information Center

    Edwards, Richard; Carney, Stephen; Ambrosius, Ulla; Lauder, Hugh

    2012-01-01

    This article presents the authors' review of "Globalizing education, educating the local: how method made us mad," by Ian Stronach. In the opening chapter of their highly influential 1997 book "Education Research Undone: The Postmodern Embrace," Ian Stronach and Maggie MacLure draw upon the work of Derrida to argue for…

  4. A special purpose knowledge-based face localization method

    NASA Astrophysics Data System (ADS)

    Hassanat, Ahmad; Jassim, Sabah

    2008-04-01

    This paper is concerned with face localization for visual speech recognition (VSR) system. Face detection and localization have got a great deal of attention in the last few years, because it is an essential pre-processing step in many techniques that handle or deal with faces, (e.g. age, face, gender, race and visual speech recognition). We shall present an efficient method for localization human's faces in video images captured on mobile constrained devices, under a wide variation in lighting conditions. We use a multiphase method that may include all or some of the following steps starting with image pre-processing, followed by a special purpose edge detection, then an image refinement step. The output image will be passed through a discrete wavelet decomposition procedure, and the computed LL sub-band at a certain level will be transformed into a binary image that will be scanned by using a special template to select a number of possible candidate locations. Finally, we fuse the scores from the wavelet step with scores determined by color information for the candidate location and employ a form of fuzzy logic to distinguish face from non-face locations. We shall present results of large number of experiments to demonstrate that the proposed face localization method is efficient and achieve high level of accuracy that outperforms existing general-purpose face detection methods.

  5. LOCALI: Calibration-Free Systematic Localization Approach for Indoor Positioning

    PubMed Central

    Ali, Muhammad Usman; Hur, Soojung; Park, Yongwan

    2017-01-01

    Recent advancements in indoor positioning systems are based on infrastructure-free solutions, aimed at improving the location accuracy in complex indoor environments without the use of specialized resources. A popular infrastructure-free solution for indoor positioning is a calibration-based positioning, commonly known as fingerprinting. Fingerprinting solutions require extensive and error-free surveys of environments to build radio-map databases, which play a key role in position estimation. Fingerprinting also requires random updates of the database, when there are significant changes in the environment or a decrease in the accuracy. The calibration of the fingerprinting database is a time-consuming and laborious effort that prevents the extensive adoption of this technique. In this paper, we present a systematic LOCALIzation approach, “LOCALI”, for indoor positioning, which does not require a calibration database and extensive updates. The LOCALI exploits the floor plan/wall map of the environment to estimate the target position by generating radio maps by integrating path-losses over certain trajectories in complex indoor environments, where triangulation using time information or the received signal strength level is highly erroneous due to the fading effects caused by multi-path propagation or absorption by environmental elements or varying antenna alignment. Experimental results demonstrate that by using the map information and environmental parameters, a significant level of accuracy in indoor positioning can be achieved. Moreover, this process requires considerably lesser effort compared to the calibration-based techniques. PMID:28587088

  6. Intelligent Resource Management for Local Area Networks: Approach and Evolution

    NASA Technical Reports Server (NTRS)

    Meike, Roger

    1988-01-01

    The Data Management System network is a complex and important part of manned space platforms. Its efficient operation is vital to crew, subsystems and experiments. AI is being considered to aid in the initial design of the network and to augment the management of its operation. The Intelligent Resource Management for Local Area Networks (IRMA-LAN) project is concerned with the application of AI techniques to network configuration and management. A network simulation was constructed employing real time process scheduling for realistic loads, and utilizing the IEEE 802.4 token passing scheme. This simulation is an integral part of the construction of the IRMA-LAN system. From it, a causal model is being constructed for use in prediction and deep reasoning about the system configuration. An AI network design advisor is being added to help in the design of an efficient network. The AI portion of the system is planned to evolve into a dynamic network management aid. The approach, the integrated simulation, project evolution, and some initial results are described.

  7. Optoelectronic scanning system upgrade by energy center localization methods

    NASA Astrophysics Data System (ADS)

    Flores-Fuentes, W.; Sergiyenko, O.; Rodriguez-Quiñonez, J. C.; Rivas-López, M.; Hernández-Balbuena, D.; Básaca-Preciado, L. C.; Lindner, L.; González-Navarro, F. F.

    2016-11-01

    A problem of upgrading an optoelectronic scanning system with digital post-processing of the signal based on adequate methods of energy center localization is considered. An improved dynamic triangulation analysis technique is proposed by an example of industrial infrastructure damage detection. A modification of our previously published method aimed at searching for the energy center of an optoelectronic signal is described. Application of the artificial intelligence algorithm of compensation for the error of determining the angular coordinate in calculating the spatial coordinate through dynamic triangulation is demonstrated. Five energy center localization methods are developed and tested to select the best method. After implementation of these methods, digital compensation for the measurement error, and statistical data analysis, a non-parametric behavior of the data is identified. The Wilcoxon signed rank test is applied to improve the result further. For optical scanning systems, it is necessary to detect a light emitter mounted on the infrastructure being investigated to calculate its spatial coordinate by the energy center localization method.

  8. Automatic localization of pupil using eccentricity and iris using gradient based method

    NASA Astrophysics Data System (ADS)

    Khan, Tariq M.; Aurangzeb Khan, M.; Malik, Shahzad A.; Khan, Shahid A.; Bashir, Tariq; Dar, Amir H.

    2011-02-01

    This paper presents a novel approach for the automatic localization of pupil and iris. Pupil and iris are nearly circular regions, which are surrounded by sclera, eyelids and eyelashes. The localization of both pupil and iris is extremely important in any iris recognition system. In the proposed algorithm pupil is localized using Eccentricity based Bisection method which looks for the region that has the highest probability of having pupil. While iris localization is carried out in two steps. In the first step, iris image is directionally segmented and a noise free region (region of interest) is extracted. In the second step, angular lines in the region of interest are extracted and the edge points of iris outer boundary are found through the gradient of these lines. The proposed method is tested on CASIA ver 1.0 and MMU Iris databases. Experimental results show that this method is comparatively accurate.

  9. A Local Incident Flux Response Expansion Transport Method for Coupling to the Diffusion Method in Cylindrical Geometry

    SciTech Connect

    Dingkang Zhang; Farzad Rahnema; Abderrafi M. Ougouag

    2013-09-01

    A local incident flux response expansion transport method is developed to generate transport solutions for coupling to diffusion theory codes regardless of their solution method (e.g., fine mesh, nodal, response based, finite element, etc.) for reactor core calculations in both two-dimensional (2-D) and three-dimensional (3-D) cylindrical geometries. In this approach, a Monte Carlo method is first used to precompute the local transport solution (i.e., response function library) for each unique transport coarse node, in which diffusion theory is not valid due to strong transport effects. The response function library is then used to iteratively determine the albedo coefficients on the diffusion-transport interfaces, which are then used as the coupling parameters within the diffusion code. This interface coupling technique allows a seamless integration of the transport and diffusion methods. The new method retains the detailed heterogeneity of the transport nodes and naturally constructs any local solution within them by a simple superposition of local responses to all incoming fluxes from the contiguous coarse nodes. A new technique is also developed for coupling to fine-mesh diffusion methods/codes. The local transport method/module is tested in 2-D and 3-D pebble-bed reactor benchmark problems consisting of an inner reflector, an annular fuel region, and a controlled outer reflector. It is found that the results predicted by the transport module agree very well with the reference fluxes calculated directly by MCNP in both benchmark problems.

  10. Rescaled Local Interaction Simulation Approach for Shear Wave Propagation Modelling in Magnetic Resonance Elastography

    PubMed Central

    Packo, P.; Staszewski, W. J.; Uhl, T.

    2016-01-01

    Properties of soft biological tissues are increasingly used in medical diagnosis to detect various abnormalities, for example, in liver fibrosis or breast tumors. It is well known that mechanical stiffness of human organs can be obtained from organ responses to shear stress waves through Magnetic Resonance Elastography. The Local Interaction Simulation Approach is proposed for effective modelling of shear wave propagation in soft tissues. The results are validated using experimental data from Magnetic Resonance Elastography. These results show the potential of the method for shear wave propagation modelling in soft tissues. The major advantage of the proposed approach is a significant reduction of computational effort. PMID:26884808

  11. A Bayesian network approach for modeling local failure in lung cancer

    NASA Astrophysics Data System (ADS)

    Oh, Jung Hun; Craft, Jeffrey; Lozi, Rawan Al; Vaidya, Manushka; Meng, Yifan; Deasy, Joseph O.; Bradley, Jeffrey D.; El Naqa, Issam

    2011-03-01

    Locally advanced non-small cell lung cancer (NSCLC) patients suffer from a high local failure rate following radiotherapy. Despite many efforts to develop new dose-volume models for early detection of tumor local failure, there was no reported significant improvement in their application prospectively. Based on recent studies of biomarker proteins' role in hypoxia and inflammation in predicting tumor response to radiotherapy, we hypothesize that combining physical and biological factors with a suitable framework could improve the overall prediction. To test this hypothesis, we propose a graphical Bayesian network framework for predicting local failure in lung cancer. The proposed approach was tested using two different datasets of locally advanced NSCLC patients treated with radiotherapy. The first dataset was collected retrospectively, which comprises clinical and dosimetric variables only. The second dataset was collected prospectively in which in addition to clinical and dosimetric information, blood was drawn from the patients at various time points to extract candidate biomarkers as well. Our preliminary results show that the proposed method can be used as an efficient method to develop predictive models of local failure in these patients and to interpret relationships among the different variables in the models. We also demonstrate the potential use of heterogeneous physical and biological variables to improve the model prediction. With the first dataset, we achieved better performance compared with competing Bayesian-based classifiers. With the second dataset, the combined model had a slightly higher performance compared to individual physical and biological models, with the biological variables making the largest contribution. Our preliminary results highlight the potential of the proposed integrated approach for predicting post-radiotherapy local failure in NSCLC patients.

  12. A new approach to the photon localization problem

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.; Noz, Marilyn E.

    1994-01-01

    Since wavelets form a representation of the Poincare group, it is possible to construct a localized superposition of light waves with different frequencies in a Lorentz-covariant manner. This localized wavelet satisfies a Lorentz-invariant uncertainty relation, and also the Lorentz-invariant Parseval's relation. A quantitative analysis is given for the difference between photons and localized waves. It is then shown that this localized entity corresponds to a relativistic photon with a sharply defined momentum in the non-localization limit. Waves are not particles. It is confirmed that the wave-particle duality is subject to the uncertainty principle.

  13. Accurate paleointensities - the multi-method approach

    NASA Astrophysics Data System (ADS)

    de Groot, Lennart

    2016-04-01

    The accuracy of models describing rapid changes in the geomagnetic field over the past millennia critically depends on the availability of reliable paleointensity estimates. Over the past decade methods to derive paleointensities from lavas (the only recorder of the geomagnetic field that is available all over the globe and through geologic times) have seen significant improvements and various alternative techniques were proposed. The 'classical' Thellier-style approach was optimized and selection criteria were defined in the 'Standard Paleointensity Definitions' (Paterson et al, 2014). The Multispecimen approach was validated and the importance of additional tests and criteria to assess Multispecimen results must be emphasized. Recently, a non-heating, relative paleointensity technique was proposed -the pseudo-Thellier protocol- which shows great potential in both accuracy and efficiency, but currently lacks a solid theoretical underpinning. Here I present work using all three of the aforementioned paleointensity methods on suites of young lavas taken from the volcanic islands of Hawaii, La Palma, Gran Canaria, Tenerife, and Terceira. Many of the sampled cooling units are <100 years old, the actual field strength at the time of cooling is therefore reasonably well known. Rather intuitively, flows that produce coherent results from two or more different paleointensity methods yield the most accurate estimates of the paleofield. Furthermore, the results for some flows pass the selection criteria for one method, but fail in other techniques. Scrutinizing and combing all acceptable results yielded reliable paleointensity estimates for 60-70% of all sampled cooling units - an exceptionally high success rate. This 'multi-method paleointensity approach' therefore has high potential to provide the much-needed paleointensities to improve geomagnetic field models for the Holocene.

  14. A stabilized, symmetric Nitsche method for spatially localized plasticity

    NASA Astrophysics Data System (ADS)

    Truster, Timothy J.

    2016-01-01

    A heterogeneous interface method is developed for combining primal displacement and mixed displacement-pressure formulations across nonconforming finite element meshes to treat volume-preserving plastic flow. When the zone of inelastic response is localized within a larger domain, significant computational savings can be achieved by confining the mixed formulation solely to the localized region. The method's distinguishing feature is that the coupling terms for joining dissimilar element types are derived from a time-discrete free energy functional, which is based on a Lagrange multiplier formulation of the interface constraints. Incorporating residual-based stabilizing terms at the interface enables the condensation of the multiplier field, leading to a symmetric Nitsche formulation in which the interface operators respect the differing character of the governing equations in each region. In a series of numerical problems, the heterogeneous interface method achieved comparable results on coarser meshes as those obtained from applying the mixed formulation throughout the domain.

  15. The local projection in the density functional theory plus U approach: A critical assessment

    NASA Astrophysics Data System (ADS)

    Wang, Yue-Chao; Chen, Ze-Hua; Jiang, Hong

    2016-04-01

    Density-functional theory plus the Hubbard U correction (DFT + U) method is widely used in first-principles studies of strongly correlated systems, as it can give qualitatively (and sometimes, semi-quantitatively) correct description of energetic and structural properties of many strongly correlated systems with similar computational cost as local density approximation or generalized gradient approximation. On the other hand, the DFT + U approach is limited both theoretically and practically in several important aspects. In particular, the results of DFT + U often depend on the choice of local orbitals (the local projection) defining the subspace in which the Hubbard U correction is applied. In this work we have systematically investigated the issue of the local projection by considering typical transition metal oxides, β-MnO2 and MnO, and comparing the results obtained from different implementations of DFT + U. We found that the choice of the local projection has significant effects on the DFT + U results, which are more significant for systems with stronger covalent bonding (e.g., MnO2) than those with more ionic bonding (e.g., MnO). These findings can help to clarify some confusion arising from the practical use of DFT + U and may also provide insights for the development of new first-principles approaches beyond DFT + U.

  16. The local projection in the density functional theory plus U approach: A critical assessment.

    PubMed

    Wang, Yue-Chao; Chen, Ze-Hua; Jiang, Hong

    2016-04-14

    Density-functional theory plus the Hubbard U correction (DFT + U) method is widely used in first-principles studies of strongly correlated systems, as it can give qualitatively (and sometimes, semi-quantitatively) correct description of energetic and structural properties of many strongly correlated systems with similar computational cost as local density approximation or generalized gradient approximation. On the other hand, the DFT + U approach is limited both theoretically and practically in several important aspects. In particular, the results of DFT + U often depend on the choice of local orbitals (the local projection) defining the subspace in which the Hubbard U correction is applied. In this work we have systematically investigated the issue of the local projection by considering typical transition metal oxides, β-MnO2 and MnO, and comparing the results obtained from different implementations of DFT + U. We found that the choice of the local projection has significant effects on the DFT + U results, which are more significant for systems with stronger covalent bonding (e.g., MnO2) than those with more ionic bonding (e.g., MnO). These findings can help to clarify some confusion arising from the practical use of DFT + U and may also provide insights for the development of new first-principles approaches beyond DFT + U.

  17. A space–angle DGFEM approach for the Boltzmann radiation transport equation with local angular refinement

    SciTech Connect

    Kópházi, József Lathouwers, Danny

    2015-09-15

    In this paper a new method for the discretization of the radiation transport equation is presented, based on a discontinuous Galerkin method in space and angle that allows for local refinement in angle where any spatial element can support its own angular discretization. To cope with the discontinuous spatial nature of the solution, a generalized Riemann procedure is required to distinguish between incoming and outgoing contributions of the numerical fluxes. A new consistent framework is introduced that is based on the solution of a generalized eigenvalue problem. The resulting numerical fluxes for the various possible cases where neighboring elements have an equal, higher or lower level of refinement in angle are derived based on tensor algebra and the resulting expressions have a very clear physical interpretation. The choice of discontinuous trial functions not only has the advantage of easing local refinement, it also facilitates the use of efficient sweep-based solvers due to decoupling of unknowns on a large scale thereby approaching the efficiency of discrete ordinates methods with local angular resolution. The approach is illustrated by a series of numerical experiments. Results show high orders of convergence for the scalar flux on angular refinement. The generalized Riemann upwinding procedure leads to stable and consistent solutions. Further the sweep-based solver performs well when used as a preconditioner for a Krylov method.

  18. Tracking local anesthetic effects using a novel perceptual reference approach

    PubMed Central

    Ettlin, Dominik A.; Lukic, Nenad; Abazi, Jetmir; Widmayer, Sonja

    2016-01-01

    Drug effects of loco-regional anesthetics are commonly measured by unidimensional pain rating scales. These scales require subjects to transform their perceptual correlates of stimulus intensities onto a visual, verbal, or numerical construct that uses a unitless cognitive reference frame. The conceptual understanding and execution of this magnitude estimation task may vary among individuals and populations. To circumvent inherent shortcomings of conventional experimental pain scales, this study used a novel perceptual reference approach to track subjective sensory perceptions during onset of an analgesic nerve block. In 34 male subjects, nociceptive electric stimuli of 1-ms duration were repetitively applied to left (target) and right (reference) mandibular canines every 5 s for 600 s, with a side latency of 1 ms. Stimulus strength to the target canine was programmed to evoke a tolerable pain intensity perception and remained constant at this level throughout the experiment. A dose of 0.6 ml of articaine 4% was submucosally injected at the left mental foramen. Subjects then reported drug effects by adjusting the stimulus strength (in milliamperes) to the reference tooth, so that the perceived intensity in the reference tooth was equi-intense to the target tooth. Pain and stimulus perception offsets were indicated by subjects. Thus, the current approach for matching the sensory experience in one anatomic location after regional anesthesia allows detailed tracking of evolving perceptual changes in another location. This novel perceptual reference approach facilitates direct and accurate quantification of analgesic effects with high temporal resolution. We propose using this method for future experimental investigations of analgesic/anesthetic drug efficacy. PMID:26792885

  19. A method for improved clustering and classification of microscopy images using quantitative co-localization coefficients

    PubMed Central

    2012-01-01

    Background The localization of proteins to specific subcellular structures in eukaryotic cells provides important information with respect to their function. Fluorescence microscopy approaches to determine localization distribution have proved to be an essential tool in the characterization of unknown proteins, and are now particularly pertinent as a result of the wide availability of fluorescently-tagged constructs and antibodies. However, there are currently very few image analysis options able to effectively discriminate proteins with apparently similar distributions in cells, despite this information being important for protein characterization. Findings We have developed a novel method for combining two existing image analysis approaches, which results in highly efficient and accurate discrimination of proteins with seemingly similar distributions. We have combined image texture-based analysis with quantitative co-localization coefficients, a method that has traditionally only been used to study the spatial overlap between two populations of molecules. Here we describe and present a novel application for quantitative co-localization, as applied to the study of Rab family small GTP binding proteins localizing to the endomembrane system of cultured cells. Conclusions We show how quantitative co-localization can be used alongside texture feature analysis, resulting in improved clustering of microscopy images. The use of co-localization as an additional clustering parameter is non-biased and highly applicable to high-throughput image data sets. PMID:22681635

  20. [Treatment approach to localized esophageal cancer--what have we learned so far?].

    PubMed

    Brenner, Baruch; Purim, Ofer; Sulkes, Aaron

    2005-07-01

    The treatment of localized esophageal cancer (LEC) is under extensive debate. Treatment approaches include surgery or radiation alone, surgery with preoperative or postoperative radiation, preoperative or postoperative chemotherapy and definitive or preoperative chemoradiation. In fact, the type of therapy patients receive is often dependent on the actual medical field of the treating physician (surgery, oncology, etc.). The use of multiple treatment approaches toward LEC primarily reflects the scarcity of data that is derived from controlled randomized trials and the poor results of current therapies. In spite of the above, the cumulative data suggest that surgery and chemoradiation are the two treatment options in LEC and that their combined approach, i.e. preoperative chemoradiation, has not been proven to have a survival advantage over each one of these methods, and should therefore still be considered investigational. This article will review the available data on the various treatment approaches that are being used against LEC.

  1. A localized meshless method for diffusion on folded surfaces

    NASA Astrophysics Data System (ADS)

    Cheung, Ka Chun; Ling, Leevan; Ruuth, Steven J.

    2015-09-01

    Partial differential equations (PDEs) on surfaces arise in a variety of application areas including biological systems, medical imaging, fluid dynamics, mathematical physics, image processing and computer graphics. In this paper, we propose a radial basis function (RBF) discretization of the closest point method. The corresponding localized meshless method may be used to approximate diffusion on smooth or folded surfaces. Our method has the benefit of having an a priori error bound in terms of percentage of the norm of the solution. A stable solver is used to avoid the ill-conditioning that arises when the radial basis functions (RBFs) become flat.

  2. Local to global: a collaborative approach to volcanic risk assessment

    NASA Astrophysics Data System (ADS)

    Calder, Eliza; Loughlin, Sue; Barsotti, Sara; Bonadonna, Costanza; Jenkins, Susanna

    2017-04-01

    -economic conditions tending to influence longer term well-being and recovery. The volcanological community includes almost 100 Volcano Observatories worldwide, the official institutions responsible for monitoring volcanoes. They may be dedicated institutions, or operate from national institutions (geological surveys, universities, met agencies). They have a key role in early warning, forecasting and long term hazard assessment (often in the form of volcanic hazards maps). The complexity of volcanic systems means that once unrest begins there are multiple potential eruptive outcomes and short term forecasts can change rapidly. This local knowledge of individual volcanoes underpins hazard and risk assessments developed at national, regional and global scales. Combining this local expertise with the knowledge of the international research community (including interdisciplinary perspectives) creates a powerful partnership. A collaborative approach is therefore needed to develop effective volcanic risk assessments at regional to global scale. The World Organisation of Volcano Observatories is a Commission of IAVCEI, alongside other Commissions such as 'Hazard and Risk' (with an active working group on volcanic hazards maps) and the 'Cities and Volcanoes' Commission. The Global Volcano Model network is a collaborative initiative developing hazards and risk information at national to global scales, underpinned by local expertise. Partners include IAVCEI, Smithsonian Institution, International Volcanic Health Hazard Network, VHub and other initiatives and institutions.

  3. A Novel Local Learning based Approach With Application to Breast Cancer Diagnosis

    SciTech Connect

    Xu, Songhua; Tourassi, Georgia

    2012-01-01

    The purpose of this study is to develop and evaluate a novel local learning-based approach for computer-assisted diagnosis of breast cancer. Our new local learning based algorithm using the linear logistic regression method as its base learner is described. Overall, our algorithm will perform its stochastic searching process until the total allowed computing time is used up by our random walk process in identifying the most suitable population subdivision scheme and their corresponding individual base learners. The proposed local learning-based approach was applied for the prediction of breast cancer given 11 mammographic and clinical findings reported by physicians using the BI-RADS lexicon. Our database consisted of 850 patients with biopsy confirmed diagnosis (290 malignant and 560 benign). We also compared the performance of our method with a collection of publicly available state-of-the-art machine learning methods. Predictive performance for all classifiers was evaluated using 10-fold cross validation and Receiver Operating Characteristics (ROC) analysis. Figure 1 reports the performance of 54 machine learning methods implemented in the machine learning toolkit Weka (version 3.0). We introduced a novel local learning-based classifier and compared it with an extensive list of other classifiers for the problem of breast cancer diagnosis. Our experiments show that the algorithm superior prediction performance outperforming a wide range of other well established machine learning techniques. Our conclusion complements the existing understanding in the machine learning field that local learning may capture complicated, non-linear relationships exhibited by real-world datasets.

  4. Skyrmions with vector mesons in the hidden local symmetry approach

    NASA Astrophysics Data System (ADS)

    Ma, Yong-Liang; Yang, Ghil-Seok; Oh, Yongseok; Harada, Masayasu

    2013-02-01

    The roles of light ρ and ω vector mesons in the Skyrmion are investigated in a chiral Lagrangian derived from the hidden local symmetry (HLS) up to O(p4) including the homogeneous Wess-Zumino terms. We write a general “master formula” that allows us to determine the parameters of the HLS Lagrangian from a class of holographic QCD models valid at the large-Nc and -λ (’t Hooft constant) limit by integrating out the infinite towers of vector and axial-vector mesons other than the lowest ρ and ω mesons. Within this approach we find that the physical properties of the Skyrmion as the solitonic description of baryons are independent of the HLS parameter a. Therefore the only parameters of the model are the pion decay constant and the vector-meson mass. Once determined in the meson sector, we have a totally parameter-free theory that allows us to study unequivocally the role of light vector mesons in the Skyrmion structure. We find, as suggested by Sutcliffe, that the inclusion of the ρ meson reduces the soliton mass, which makes the Skyrmion come closer to the Bogomol’nyi-Prasad-Sommerfield soliton, but the role of the ω meson is found to increase the soliton mass. In stark contrast, the Δ-N mass difference, which is determined by the moment of inertia in the adiabatic collective quantization of the Skyrmion, is increased by the ρ vector meson, while it is reduced by the inclusion of the ω meson. All these observations show the importance of the ω meson in the properties of the nucleon and nuclear matter in the Skyrme model.

  5. A locally adaptive kernel regression method for facies delineation

    NASA Astrophysics Data System (ADS)

    Fernàndez-Garcia, D.; Barahona-Palomo, M.; Henri, C. V.; Sanchez-Vila, X.

    2015-12-01

    Facies delineation is defined as the separation of geological units with distinct intrinsic characteristics (grain size, hydraulic conductivity, mineralogical composition). A major challenge in this area stems from the fact that only a few scattered pieces of hydrogeological information are available to delineate geological facies. Several methods to delineate facies are available in the literature, ranging from those based only on existing hard data, to those including secondary data or external knowledge about sedimentological patterns. This paper describes a methodology to use kernel regression methods as an effective tool for facies delineation. The method uses both the spatial and the actual sampled values to produce, for each individual hard data point, a locally adaptive steering kernel function, self-adjusting the principal directions of the local anisotropic kernels to the direction of highest local spatial correlation. The method is shown to outperform the nearest neighbor classification method in a number of synthetic aquifers whenever the available number of hard data is small and randomly distributed in space. In the case of exhaustive sampling, the steering kernel regression method converges to the true solution. Simulations ran in a suite of synthetic examples are used to explore the selection of kernel parameters in typical field settings. It is shown that, in practice, a rule of thumb can be used to obtain suboptimal results. The performance of the method is demonstrated to significantly improve when external information regarding facies proportions is incorporated. Remarkably, the method allows for a reasonable reconstruction of the facies connectivity patterns, shown in terms of breakthrough curves performance.

  6. VLPs of HCV local isolates for HCV immunoassay diagnostic approach in Indonesia

    NASA Astrophysics Data System (ADS)

    Prasetyo, Afiono Agung

    2017-01-01

    Hepatitis C Virus (HCV) infection is a major global disease which often leads to morbidity and mortality. Low survival is related to the lack of adequate diagnostic because HCV infection is frequently asymptomatic and there are no specific diagnostic tests due to the fast transformation of the virus. Here, we investigated the VLPs (virus-like particles) of HCV local isolate as an immunoassay diagnostic approach to detect HCV infection, especially in Indonesia. The core, E1, and E2 of HCV local isolate genes were cloned and molecular analyzed, either as single or in recombinant-VLP form, to determine the molecular and chemical characteristics of each VLPs related to their potential use as an immunoassay detection method for HCV infection. The results indicated the molecular and chemical character of each VLPs are comparable. Conclusion: VLPs of HCV has the potential as an immunoassay diagnostic approach to detect HCV infection.

  7. Block-Localized Wavefunction (BLW) Based Two-State Approach for Charge Transfers between Phenyl Rings.

    PubMed

    Mo, Yirong; Song, Lingchun; Lin, Yuchun; Liu, Minghong; Cao, Zexing; Wu, Wei

    2012-03-13

    The block-localized wave function (BLW) method is the simplest and most efficient variant of ab initio valence bond (VB) theory which defines electron-localized resonance states following the conventional VB concepts. Here, a BLW-based two-state approach is proposed to probe the charge/hole transfer reactions within the Marcus-Hush model. With this approach, both the electronic coupling and reorganization energies can be derived at the ab initio level. Pilot applications to the electron/hole transfers between two phenyl rings are presented. Good exponential correlation between the electronic coupling energy and the donor-acceptor distance is shown, whereas the inner-sphere reorganization shows little geometric dependency. Computations also support the assumption in Marcus theory that the thermal electron transfer barrier (ΔG*), which is a sum of the reaction barrier (ΔEa) for electron/hole transfer and the coupling energy (VAB), is a quarter of the reorganization energy (λ).

  8. Density matrix modeling of quantum cascade lasers without an artificially localized basis: A generalized scattering approach

    NASA Astrophysics Data System (ADS)

    Pan, Andrew; Burnett, Benjamin A.; Chui, Chi On; Williams, Benjamin S.

    2017-08-01

    We derive a density matrix (DM) theory for quantum cascade lasers (QCLs) that describes the influence of scattering on coherences through a generalized scattering superoperator. The theory enables quantitative modeling of QCLs, including localization and tunneling effects, using the well-defined energy eigenstates rather than the ad hoc localized basis states required by most previous DM models. Our microscopic approach to scattering also eliminates the need for phenomenological transition or dephasing rates. We discuss the physical interpretation and numerical implementation of the theory, presenting sets of both energy-resolved and thermally averaged equations, which can be used for detailed or compact device modeling. We illustrate the theory's applications by simulating a high performance resonant-phonon terahertz (THz) QCL design, which cannot be easily or accurately modeled using conventional DM methods. We show that the theory's inclusion of coherences is crucial for describing localization and tunneling effects consistent with experiment.

  9. Multiple Shooting-Local Linearization method for the identification of dynamical systems

    NASA Astrophysics Data System (ADS)

    Carbonell, F.; Iturria-Medina, Y.; Jimenez, J. C.

    2016-08-01

    The combination of the multiple shooting strategy with the generalized Gauss-Newton algorithm turns out in a recognized method for estimating parameters in ordinary differential equations (ODEs) from noisy discrete observations. A key issue for an efficient implementation of this method is the accurate integration of the ODE and the evaluation of the derivatives involved in the optimization algorithm. In this paper, we study the feasibility of the Local Linearization (LL) approach for the simultaneous numerical integration of the ODE and the evaluation of such derivatives. This integration approach results in a stable method for the accurate approximation of the derivatives with no more computational cost than that involved in the integration of the ODE. The numerical simulations show that the proposed Multiple Shooting-Local Linearization method recovers the true parameters value under different scenarios of noisy data.

  10. A Retrospective Approach to Testing the DNA Barcoding Method

    PubMed Central

    Chapple, David G.; Ritchie, Peter A.

    2013-01-01

    A decade ago, DNA barcoding was proposed as a standardised method for identifying existing species and speeding the discovery of new species. Yet, despite its numerous successes across a range of taxa, its frequent failures have brought into question its accuracy as a short-cut taxonomic method. We use a retrospective approach, applying the method to the classification of New Zealand skinks as it stood in 1977 (primarily based upon morphological characters), and compare it to the current taxonomy reached using both morphological and molecular approaches. For the 1977 dataset, DNA barcoding had moderate-high success in identifying specimens (78-98%), and correctly flagging specimens that have since been confirmed as distinct taxa (77-100%). But most matching methods failed to detect the species complexes that were present in 1977. For the current dataset, there was moderate-high success in identifying specimens (53-99%). For both datasets, the capacity to discover new species was dependent on the methodological approach used. Species delimitation in New Zealand skinks was hindered by the absence of either a local or global barcoding gap, a result of recent speciation events and hybridisation. Whilst DNA barcoding is potentially useful for specimen identification and species discovery in New Zealand skinks, its error rate could hinder the progress of documenting biodiversity in this group. We suggest that integrated taxonomic approaches are more effective at discovering and describing biodiversity. PMID:24244283

  11. Machine-learning approach for local classification of crystalline structures in multiphase systems

    NASA Astrophysics Data System (ADS)

    Dietz, C.; Kretz, T.; Thoma, M. H.

    2017-07-01

    Machine learning is one of the most popular fields in computer science and has a vast number of applications. In this work we will propose a method that will use a neural network to locally identify crystal structures in a mixed phase Yukawa system consisting of fcc, hcp, and bcc clusters and disordered particles similar to plasma crystals. We compare our approach to already used methods and show that the quality of identification increases significantly. The technique works very well for highly disturbed lattices and shows a flexible and robust way to classify crystalline structures that can be used by only providing particle positions. This leads to insights into highly disturbed crystalline structures.

  12. Field theoretic approach to dynamical orbital localization in ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Thomas, Jordan W.; Iftimie, Radu; Tuckerman, Mark E.

    2004-03-01

    Techniques from gauge-field theory are employed to derive an alternative formulation of the Car-Parrinello ab initio molecular-dynamics method that allows maximally localized Wannier orbitals to be generated dynamically as the calculation proceeds. In particular, the Car-Parrinello Lagrangian is mapped onto an SU(n) non-Abelian gauge-field theory and the fictitious kinetic energy in the Car-Parrinello Lagrangian is modified to yield a fully gauge-invariant form. The Dirac gauge-fixing method is then employed to derive a set of equations of motion that automatically maintain orbital locality by restricting the orbitals to remain in the “Wannier gauge.” An approximate algorithm for integrating the equations of motion that is stable and maintains orbital locality is then developed based on the exact equations of motion. It is shown in a realistic application (64 water molecules plus one hydrogen-chloride molecule in a periodic box) that orbital locality can be maintained with only a modest increase in CPU time. The ability to keep orbitals localized in an ab initio molecular-dynamics calculation is a crucial ingredient in the development of emerging linear scaling approaches.

  13. Development of a GIS method to localize critical source areas of diffuse nitrate pollution.

    PubMed

    Orlikowski, D; Bugey, A; Périllon, C; Julich, S; Guégain, C; Soyeux, E; Matzinger, A

    2011-01-01

    The present study aimed at developing a universal method for the localization of critical source areas (CSAs) of diffuse nitrate (NO3-) pollution in rural catchments with low data availability. Based on existing methods, land use, soil, slope, riparian buffer strips and distance to surface waters were identified as the most relevant indicator parameters for diffuse agricultural NO3- pollution. The five parameters were averaged in a GIS-overlay to localize areas with low, medium and high risk of NO3- pollution. A first application of the GIS approach to the Ic catchment in France, showed that identified CSAs were in good agreement with results from river monitoring and numerical modelling. Additionally, the GIS approach showed low sensitivity to single parameters, which makes it robust to varying data availability. As a result, the tested GIS-approach provides a promising, easy-to-use CSA identification concept, applicable for a wide range of rural catchments.

  14. Method of Deployment of a Space Tethered System Aligned to the Local Vertical

    NASA Astrophysics Data System (ADS)

    Zakrzhevskii, A. E.

    2016-09-01

    The object of this research is a space tether of two bodies connected by a flexible massless string. The research objective is the development and theoretical justification of a novel approach to the solution of the problem of deployment of the space tether in a circular orbit with its alignment to the local vertical. The approach is based on use of the theorem on the angular momentum change. It allows developing the open-loop control of the tether length that provides desired change of the angular momentum of the tether under the effect of the gravitational torque to the value, which corresponds to the angular momentum of the deployed tether aligned to the local vertical. The given example of application of the approach to a case of deployment of a tether demonstrates the simplicity of use of the method in practice, and also the method of validation of the mathematical model.

  15. Teaching Local Lore in EFL Class: New Approaches

    ERIC Educational Resources Information Center

    Yarmakeev, Iskander E.; Pimenova, Tatiana S.; Zamaletdinova, Gulyusa R.

    2016-01-01

    This paper is dedicated to the up-to-date educational problem, that is, the role of local lore in teaching EFL to University students. Although many educators admit that local lore knowledge plays a great role in the development of a well-bred and well-educated personality and meets students' needs, the problem has not been thoroughly studied.…

  16. Think Locally: A Prudent Approach to Electronic Resource Management Systems

    ERIC Educational Resources Information Center

    Gustafson-Sundell, Nat

    2011-01-01

    A few articles have drawn some amount of attention specifically to the local causes of the success or failure of electronic resource management system (ERMS) implementations. In fact, it seems clear that local conditions will largely determine whether any given ERMS implementation will succeed or fail. This statement might seem obvious, but the…

  17. System and method for bullet tracking and shooter localization

    DOEpatents

    Roberts, Randy S.; Breitfeller, Eric F.

    2011-06-21

    A system and method of processing infrared imagery to determine projectile trajectories and the locations of shooters with a high degree of accuracy. The method includes image processing infrared image data to reduce noise and identify streak-shaped image features, using a Kalman filter to estimate optimal projectile trajectories, updating the Kalman filter with new image data, determining projectile source locations by solving a combinatorial least-squares solution for all optimal projectile trajectories, and displaying all of the projectile source locations. Such a shooter-localization system is of great interest for military and law enforcement applications to determine sniper locations, especially in urban combat scenarios.

  18. Nonlinear diffusion filtering methods locally adapted to data features

    NASA Astrophysics Data System (ADS)

    Kollár, Michal; Čunderlík, Róbert; Mikula, Karol

    2017-04-01

    The contribution deals with nonlinear diffusion filtering methods on a planar surface. These methods represent an extension of the simple linear diffusion filtering by the nonlinear diffusivity coefficient. This coefficient represents a function which depends on data features such as gradient and local or global extrema of data. In the case of the regularized surface Perona-Malik model, method mostly used in image processing, the diffusivity coefficient represents the edge detector function. If we use the nonlinear diffusion filtering influenced by the Laplace operator, local extrema detector function affects the diffusion process. We use a finite-volume method to approximate numerically the nonlinear parabolic partial differential equation on uniform rectangle grid and finite difference method to approximate gradients and Laplacians. Numerical experiments present nonlinear diffusion filtering of artificial data and real measurements in upcoming filtering software with real-time filtered data visualization widget. Real measurements represent GOCE satellite observations, satellite-only MDT data, and high-resolution altimetry-derived gravity data. They aim to point out the main advantage of the nonlinear diffusion models which, on the contrary to linear models, preserve important structures of processed data.

  19. Meshfree local radial basis function collocation method with image nodes

    NASA Astrophysics Data System (ADS)

    Baek, Seung Ki; Kim, Minjae

    2017-07-01

    We numerically solve two-dimensional heat diffusion problems by using a simple variant of the meshfree local radial-basis function (RBF) collocation method. The main idea is to include an additional set of sample nodes outside the problem domain, similarly to the method of images in electrostatics, to perform collocation on the domain boundaries. We can thereby take into account the temperature profile as well as its gradients specified by boundary conditions at the same time, which holds true even for a node where two or more boundaries meet with different boundary conditions. We argue that the image method is computationally efficient when combined with the local RBF collocation method, whereas the addition of image nodes becomes very costly in case of the global collocation. We apply our modified method to a benchmark test of a boundary value problem, and find that this simple modification reduces the maximum error from the analytic solution significantly. The reduction is small for an initial value problem with simpler boundary conditions. We observe increased numerical instability, which has to be compensated for by a sufficient number of sample nodes and/or more careful parameter choices for time integration.

  20. Moving sound source localization based on triangulation method

    NASA Astrophysics Data System (ADS)

    Miao, Feng; Yang, Diange; Wen, Junjie; Lian, Xiaomin

    2016-12-01

    This study develops a sound source localization method that extends traditional triangulation to moving sources. First, the possible sound source locating plane is scanned. Secondly, for each hypothetical source location in this possible plane, the Doppler effect is removed through the integration of sound pressure. Taking advantage of the de-Dopplerized signals, the moving time difference of arrival (MTDOA) is calculated, and the sound source is located based on triangulation. Thirdly, the estimated sound source location is compared to the original hypothetical location and the deviations are recorded. Because the real sound source location leads to zero deviation, the sound source can be finally located by minimizing the deviation matrix. Simulations have shown the superiority of MTDOA method over traditional triangulation in case of moving sound sources. The MTDOA method can be used to locate moving sound sources with as high resolution as DAMAS beamforming, as shown in the experiments, offering thus a new method for locating moving sound sources.

  1. The modal surface interpolation method for damage localization

    NASA Astrophysics Data System (ADS)

    Pina Limongelli, Maria

    2017-05-01

    The Interpolation Method (IM) has been previously proposed and successfully applied for damage localization in plate like structures. The method is based on the detection of localized reductions of smoothness in the Operational Deformed Shapes (ODSs) of the structure. The IM can be applied to any type of structure provided the ODSs are estimated accurately in the original and in the damaged configurations. If the latter circumstance fails to occur, for example when the structure is subjected to an unknown input(s) or if the structural responses are strongly corrupted by noise, both false and missing alarms occur when the IM is applied to localize a concentrated damage. In order to overcome these drawbacks a modification of the method is herein investigated. An ODS is the deformed shape of a structure subjected to a harmonic excitation: at resonances the ODS are dominated by the relevant mode shapes. The effect of noise at resonance is usually lower with respect to other frequency values hence the relevant ODS are estimated with higher reliability. Several methods have been proposed to reliably estimate modal shapes in case of unknown input. These two circumstances can be exploited to improve the reliability of the IM. In order to reduce or eliminate the drawbacks related to the estimation of the ODSs in case of noisy signals, in this paper is investigated a modified version of the method based on a damage feature calculated considering the interpolation error relevant only to the modal shapes and not to all the operational shapes in the significant frequency range. Herein will be reported the comparison between the results of the IM in its actual version (with the interpolation error calculated summing up the contributions of all the operational shapes) and in the new proposed version (with the estimation of the interpolation error limited to the modal shapes).

  2. Impact localization on composite structures using time difference and MUSIC approach

    NASA Astrophysics Data System (ADS)

    Zhong, Yongteng; Xiang, Jiawei

    2017-05-01

    1-D uniform linear array (ULA) has the shortcoming of the half-plane mirror effect, which does not allow discriminating between a target placed above the array and a target placed below the array. This paper presents time difference (TD) and multiple signal classification (MUSIC) based omni-directional impact localization on a large stiffened composite structure using improved linear array, which is able to perform omni-directional 360° localization. This array contains 2M+3 PZT sensors, where 2M+1 PZT sensors are arranged as a uniform linear array, and the other two PZT sensors are placed above and below the array. Firstly, the arrival times of impact signals observed by the other two sensors are determined using the wavelet transform. Compared with each other, the direction range of impact source can be decided in general, 0°to 180° or 180°to 360°. And then, two dimensional multiple signal classification (2D-MUSIC) based spatial spectrum formula using the uniform linear array is applied for impact localization by the general direction range. When the arrival times of impact signals observed by upper PZT is equal to that of lower PZT, the direction can be located in x axis (0°or 180°). And time difference based MUSIC method is present to locate impact position. To verify the proposed approach, the proposed approach is applied to a composite structure. The localization results are in good agreement with the actual impact occurring positions.

  3. Developing an Integrated Approach for Local Urban Climate Models in London from Neighbourhood to Street Scale

    NASA Astrophysics Data System (ADS)

    Bakkali, M.; Davies, M.; Steadman, J. P.

    2012-04-01

    We currently have an incomplete understanding of how weather varies across London and how the city's microclimate will intensify levels of heat, cold and air pollution in the future. There is a need to target priority areas of the city and to promote design guidance on climate change mitigation strategies. As a result of improvements in the accuracy of local weather data in London, an opportunity is emerging for designers and planners of the built environment to measure the impact of their designs on local urban climate and to enhance the designer's role in creating more informed design choices at an urban micro-scale. However, modelling the different components of the urban environment separately and then collating and comparing the results invariably leads to discrepancies in the output of local urban climate modelling tools designed to work at different scales. Of particular interest is why marked differences appear between the data extracted from local urban climate models when we change the scale of modelling from city to building scale. An example of such differences is those that have been observed in relation to the London Unified Model and London Site Specific Air Temperature model. In order to avoid these discrepancies we need a method for understanding and assessing how the urban environment impacts on local urban climate as a whole. A step to achieving this is by developing inter-linkages between assessment tools. Accurate information on the net impact of the urban environment on the local urban climate will in turn facilitate more accurate predictions of future energy demand and realistic scenarios for comfort and health. This paper will present two key topographies of London's urban environment that influence local urban climate: land use and street canyons. It will look at the possibilities for developing an integrated approach to modelling London's local urban climate from the neighbourhood to the street scale.

  4. A multiscale hypothesis testing approach to anomaly detection and localization from noisy tomographic data.

    PubMed

    Frakt, A B; Karl, W C; Willsky, A S

    1998-01-01

    In this paper, we investigate the problems of anomaly detection and localization from noisy tomographic data. These are characteristic of a class of problems that cannot be optimally solved because they involve hypothesis testing over hypothesis spaces with extremely large cardinality. Our multiscale hypothesis testing approach addresses the key issues associated with this class of problems. A multiscale hypothesis test is a hierarchical sequence of composite hypothesis tests that discards large portions of the hypothesis space with minimal computational burden and zooms in on the likely true hypothesis. For the anomaly detection and localization problems, hypothesis zooming corresponds to spatial zooming - anomalies are successively localized to finer and finer spatial scales. The key challenges we address include how to hierarchically divide a large hypothesis space and how to process the data at each stage of the hierarchy to decide which parts of the hypothesis space deserve more attention. For the latter, we pose and solve a nonlinear optimization problem for a decision statistic that maximally disambiguates composite hypotheses. With no more computational complexity, our optimized statistic shows substantial improvement over conventional approaches. We provide examples that demonstrate this and quantify how much performance is sacrificed by the use of a suboptimal method as compared to that achievable if the optimal approach were computationally feasible.

  5. Evolutionary Local Search of Fuzzy Rules through a novel Neuro-Fuzzy encoding method.

    PubMed

    Carrascal, A; Manrique, D; Ríos, J; Rossi, C

    2003-01-01

    This paper proposes a new approach for constructing fuzzy knowledge bases using evolutionary methods. We have designed a genetic algorithm that automatically builds neuro-fuzzy architectures based on a new indirect encoding method. The neuro-fuzzy architecture represents the fuzzy knowledge base that solves a given problem; the search for this architecture takes advantage of a local search procedure that improves the chromosomes at each generation. Experiments conducted both on artificially generated and real world problems confirm the effectiveness of the proposed approach.

  6. An improved method for localizing electric brain dipoles.

    PubMed

    Salu, Y; Cohen, L G; Rose, D; Sato, S; Kufta, C; Hallett, M

    1990-07-01

    Methods for localizing electrical dipolar sources in the brain differ from one another by the models they use to represent the head, the specific formulas used in the calculation of the scalp potentials, the way that the reference electrode is treated, and by the algorithm employed to find the least-squares fit between the measured and calculated EEG potentials. The model presented here is based on some of the most advanced features found in other models, and on some improvements. The head is represented by a three-layer spherical model. The potential on any point on the scalp due to any source is found by a closed formula, which is not based on matrix rotations. The formulas will accept any surface electrode as the reference electrode. The least-squares procedure is based on optimal dipoles, reducing the number of unknowns in the iterations from six to three. The new method was evaluated by localizing five implanted dipolar sources in human sensorimotor cortex. The distances between the locations of the sources as calculated by the method, and the actual locations were between 0.4 and 2.0 cm. The sensitivity of the method to uncertainties encountered whenever a real head has to be modeled by a three-layer model has also been assessed.

  7. A Robust Vehicle Localization Approach Based on GNSS/IMU/DMI/LiDAR Sensor Fusion for Autonomous Vehicles.

    PubMed

    Meng, Xiaoli; Wang, Heng; Liu, Bingbing

    2017-09-18

    Precise and robust localization in a large-scale outdoor environment is essential for an autonomous vehicle. In order to improve the performance of the fusion of GNSS (Global Navigation Satellite System)/IMU (Inertial Measurement Unit)/DMI (Distance-Measuring Instruments), a multi-constraint fault detection approach is proposed to smooth the vehicle locations in spite of GNSS jumps. Furthermore, the lateral localization error is compensated by the point cloud-based lateral localization method proposed in this paper. Experiment results have verified the algorithms proposed in this paper, which shows that the algorithms proposed in this paper are capable of providing precise and robust vehicle localization.

  8. Application of advanced reliability methods to local strain fatigue analysis

    NASA Technical Reports Server (NTRS)

    Wu, T. T.; Wirsching, P. H.

    1983-01-01

    When design factors are considered as random variables and the failure condition cannot be expressed by a closed form algebraic inequality, computations of risk (or probability of failure) might become extremely difficult or very inefficient. This study suggests using a simple, and easily constructed, second degree polynomial to approximate the complicated limit state in the neighborhood of the design point; a computer analysis relates the design variables at selected points. Then a fast probability integration technique (i.e., the Rackwitz-Fiessler algorithm) can be used to estimate risk. The capability of the proposed method is demonstrated in an example of a low cycle fatigue problem for which a computer analysis is required to perform local strain analysis to relate the design variables. A comparison of the performance of this method is made with a far more costly Monte Carlo solution. Agreement of the proposed method with Monte Carlo is considered to be good.

  9. Subjective comparison of brightness preservation methods for local backlight dimming displays

    NASA Astrophysics Data System (ADS)

    Korhonen, J.; Mantel, C.; Forchhammer, S.

    2015-01-01

    Local backlight dimming is a popular technology in high quality Liquid Crystal Displays (LCDs). In those displays, the backlight is composed of contributions from several individually adjustable backlight segments, set at different backlight luminance levels in different parts of the screen, according to the luma of the target image displayed on LCD. Typically, transmittance of the liquid crystal cells (pixels) located in the regions with dimmed backlight is increased in order to preserve their relative brightness with respect to the pixels located in the regions with bright backlight. There are different methods for brightness preservation for local backlight dimming displays, producing images with different visual characteristics. In this study, we have implemented, analyzed and evaluated several different approaches for brightness preservation, and conducted a subjective study based on rank ordering to compare the relevant methods on a real-life LCD with a local backlight dimming capability. In general, our results show that locally adapted brightness preservation methods produce more preferred visual outcome than global methods, but dependency on the content is also observed. Based on the results, guidelines for selecting the perceptually preferred brightness preservation method for local backlight dimming displays are outlined.

  10. A global/local analysis method for treating details in structural design

    NASA Technical Reports Server (NTRS)

    Aminpour, Mohammad A.; Mccleary, Susan L.; Ransom, Jonathan B.

    1993-01-01

    A method for analyzing global/local behavior of plate and shell structures is described. In this approach, a detailed finite element model of the local region is incorporated within a coarser global finite element model. The local model need not be nodally compatible (i.e., need not have a one-to-one nodal correspondence) with the global model at their common boundary; therefore, the two models may be constructed independently. The nodal incompatibility of the models is accounted for by introducing appropriate constraint conditions into the potential energy in a hybrid variational formulation. The primary advantage of this method is that the need for transition modeling between global and local models is eliminated. Eliminating transition modeling has two benefits. First, modeling efforts are reduced since tedious and complex transitioning need not be performed. Second, errors due to the mesh distortion, often unavoidable in mesh transitioning, are minimized by avoiding distorted elements beyond what is needed to represent the geometry of the component. The method is applied reduced to a plate loaded in tension and transverse bending. The plate has a central hole, and various hole sixes and shapes are studied. The method is also applied to a composite laminated fuselage panel with a crack emanating from a window in the panel. While this method is applied herein to global/local problems, it is also applicable to the coupled analysis of independently modeled components as well as adaptive refinement.

  11. Russian risk assessment methods and approaches

    SciTech Connect

    Dvorack, M.A.; Carlson, D.D.; Smith, R.E.

    1996-07-01

    One of the benefits resulting from the collapse of the Soviet Union is the increased dialogue currently taking place between American and Russian nuclear weapons scientists in various technical arenas. One of these arenas currently being investigated involves collaborative studies which illustrate how risk assessment is perceived and utilized in the Former Soviet Union (FSU). The collaborative studies indicate that, while similarities exist with respect to some methodologies, the assumptions and approaches in performing risk assessments were, and still are, somewhat different in the FSU as opposed to that in the US. The purpose of this paper is to highlight the present knowledge of risk assessment methodologies and philosophies within the two largest nuclear weapons laboratories of the Former Soviet Union, Arzamas-16 and Chelyabinsk-70. Furthermore, This paper will address the relative progress of new risk assessment methodologies, such as Fuzzy Logic, within the framework of current risk assessment methods at these two institutes.

  12. In vitro bioequivalence approach for a locally acting gastrointestinal drug: lanthanum carbonate.

    PubMed

    Yang, Yongsheng; Shah, Rakhi B; Yu, Lawrence X; Khan, Mansoor A

    2013-02-04

    A conventional human pharmacokinetic (PK) in vivo study is often considered as the "gold standard" to determine bioequivalence (BE) of drug products. However, this BE approach is not always applicable to the products not intended to be delivered into the systemic circulation. For locally acting gastrointestinal (GI) products, well designed in vitro approaches might be more practical in that they are able not only to qualitatively predict the presence of the active substance at the site of action but also to specifically assess the performance of the active substance. For example, lanthanum carbonate chewable tablet, a locally acting GI phosphate binder when orally administrated, can release free lanthanum ions in the acid environment of the upper GI tract. The lanthanum ions directly reach the site of action to bind with dietary phosphate released from food to form highly insoluble lanthanum-phosphate complexes. This prevents the absorption of phosphate consequently reducing the serum phosphate. Thus, using a conventional PK approach to demonstrate BE is meaningless since plasma levels are not relevant for local efficacy in the GI tract. Additionally the bioavailability of lanthanum carbonate is less than 0.002%, and therefore, the PK approach is not feasible. Therefore, an alternative assessment method is required. This paper presents an in vitro approach that can be used in lieu of PK or clinical studies to determine the BE of lanthanum carbonate chewable tablets. It is hoped that this information can be used to finalize an in vitro guidance for BE studies of lanthanum carbonate chewable tablets as well as to assist with "in vivo" biowaiver decision making. The scientific information might be useful to the pharmaceutical industry for the purpose of planning and designing future BE studies.

  13. Local and Global Gestalt Laws: A Neurally Based Spectral Approach.

    PubMed

    Favali, Marta; Citti, Giovanna; Sarti, Alessandro

    2017-02-01

    This letter presents a mathematical model of figure-ground articulation that takes into account both local and global gestalt laws and is compatible with the functional architecture of the primary visual cortex (V1). The local gestalt law of good continuation is described by means of suitable connectivity kernels that are derived from Lie group theory and quantitatively compared with long-range connectivity in V1. Global gestalt constraints are then introduced in terms of spectral analysis of a connectivity matrix derived from these kernels. This analysis performs grouping of local features and individuates perceptual units with the highest salience. Numerical simulations are performed, and results are obtained by applying the technique to a number of stimuli.

  14. Mapping the Similarities of Spectra: Global and Locally-biased Approaches to SDSS Galaxies

    NASA Astrophysics Data System (ADS)

    Lawlor, David; Budavári, Tamás; Mahoney, Michael W.

    2016-12-01

    We present a novel approach to studying the diversity of galaxies. It is based on a novel spectral graph technique, that of locally-biased semi-supervised eigenvectors. Our method introduces new coordinates that summarize an entire spectrum, similar to but going well beyond the widely used Principal Component Analysis (PCA). Unlike PCA, however, this technique does not assume that the Euclidean distance between galaxy spectra is a good global measure of similarity. Instead, we relax that condition to only the most similar spectra, and we show that doing so yields more reliable results for many astronomical questions of interest. The global variant of our approach can identify very finely numerous astronomical phenomena of interest. The locally-biased variants of our basic approach enable us to explore subtle trends around a set of chosen objects. The power of the method is demonstrated in the Sloan Digital Sky Survey Main Galaxy Sample, by illustrating that the derived spectral coordinates carry an unprecedented amount of information.

  15. A New Approach for Copy-Move Detection Based on Improved Weber Local Descriptor.

    PubMed

    Saadat, Shabnam; Moghaddam, Mohsen Ebrahimi; Mohammadi, Mohsen

    2015-11-01

    One of the most common image tampering techniques is copy-move; in this technique, one or more parts of the image are copied and pasted in another area of the image. Recently, various methods have been proposed for copy-move detection; however, many of these techniques are not robust to additional changes like geometric transformation, and they are failed to be useful for detecting small copied areas. In this paper, a new method based on point descriptors which are derived from the integration of textural feature-based Weber law and statistical features of the image is presented. In this proposed approach, modified multiscale version of Weber local descriptor is presented to make the method robust versus geometric transformation and detect small copied areas. The results of the experiments showed that our method can detect small copied areas and copy-move tampered images which are influenced by rotation, scaling, noise addition, compression, blurring, and mirroring.

  16. 3-D Localization Method for a Magnetically Actuated Soft Capsule Endoscope and Its Applications

    PubMed Central

    Yim, Sehyuk; Sitti, Metin

    2014-01-01

    In this paper, we present a 3-D localization method for a magnetically actuated soft capsule endoscope (MASCE). The proposed localization scheme consists of three steps. First, MASCE is oriented to be coaxially aligned with an external permanent magnet (EPM). Second, MASCE is axially contracted by the enhanced magnetic attraction of the approaching EPM. Third, MASCE recovers its initial shape by the retracting EPM as the magnetic attraction weakens. The combination of the estimated direction in the coaxial alignment step and the estimated distance in the shape deformation (recovery) step provides the position of MASCE in 3-D. It is experimentally shown that the proposed localization method could provide 2.0–3.7 mm of distance error in 3-D. This study also introduces two new applications of the proposed localization method. First, based on the trace of contact points between the MASCE and the surface of the stomach, the 3-D geometrical model of a synthetic stomach was reconstructed. Next, the relative tissue compliance at each local contact point in the stomach was characterized by measuring the local tissue deformation at each point due to the preloading force. Finally, the characterized relative tissue compliance parameter was mapped onto the geometrical model of the stomach toward future use in disease diagnosis. PMID:25383064

  17. Local Velocity Postprocessing for Multipoint Flux Methods on General Hexahedra

    SciTech Connect

    Wheeler, M. F.; Xue, G.; Yotov, I.

    2012-01-01

    The authors formulated in a multipoint flux mixed finite element method that reduces to a cell-centered pressure system on general quadrilaterals and hexahedra for elliptic equations arising in subsurface flow problems. In addition they showed that a special quadrature rule yields O(h) convergence for face fluxes on distorted hexahedra. Here a first order local velocity postprocessing procedure using these face fluxes is developed and analyzed. The algorithm involves solving a 3 × 3 system on each element and utilizes an enhanced mixed finite element space introduced by Falk, Gatto, and Monk. Computational results verifying the theory are demonstrated.

  18. Designing and Evaluating Bamboo Harvesting Methods for Local Needs: Integrating Local Ecological Knowledge and Science

    NASA Astrophysics Data System (ADS)

    Darabant, András; Rai, Prem Bahadur; Staudhammer, Christina Lynn; Dorji, Tshewang

    2016-08-01

    Dendrocalamus hamiltonii, a large, clump-forming bamboo, has great potential to contribute towards poverty alleviation efforts across its distributional range. Harvesting methods that maximize yield while they fulfill local objectives and ensure sustainability are a research priority. Documenting local ecological knowledge on the species and identifying local users' goals for its production, we defined three harvesting treatments (selective cut, horseshoe cut, clear cut) and experimentally compared them with a no-intervention control treatment in an action research framework. We implemented harvesting over three seasons and monitored annually and two years post-treatment. Even though the total number of culms positively influenced the number of shoots regenerated, a much stronger relationship was detected between the number of culms harvested and the number of shoots regenerated, indicating compensatory growth mechanisms to guide shoot regeneration. Shoot recruitment declined over time in all treatments as well as the control; however, there was no difference among harvest treatments. Culm recruitment declined with an increase in harvesting intensity. When univariately assessing the number of harvested culms and shoots, there were no differences among treatments. However, multivariate analyses simultaneously considering both variables showed that harvested output of shoots and culms was higher with clear cut and horseshoe cut as compared to selective cut. Given the ease of implementation and issues of work safety, users preferred the horseshoe cut, but the lack of sustainability of shoot production calls for investigating longer cutting cycles.

  19. Designing and Evaluating Bamboo Harvesting Methods for Local Needs: Integrating Local Ecological Knowledge and Science.

    PubMed

    Darabant, András; Rai, Prem Bahadur; Staudhammer, Christina Lynn; Dorji, Tshewang

    2016-08-01

    Dendrocalamus hamiltonii, a large, clump-forming bamboo, has great potential to contribute towards poverty alleviation efforts across its distributional range. Harvesting methods that maximize yield while they fulfill local objectives and ensure sustainability are a research priority. Documenting local ecological knowledge on the species and identifying local users' goals for its production, we defined three harvesting treatments (selective cut, horseshoe cut, clear cut) and experimentally compared them with a no-intervention control treatment in an action research framework. We implemented harvesting over three seasons and monitored annually and two years post-treatment. Even though the total number of culms positively influenced the number of shoots regenerated, a much stronger relationship was detected between the number of culms harvested and the number of shoots regenerated, indicating compensatory growth mechanisms to guide shoot regeneration. Shoot recruitment declined over time in all treatments as well as the control; however, there was no difference among harvest treatments. Culm recruitment declined with an increase in harvesting intensity. When univariately assessing the number of harvested culms and shoots, there were no differences among treatments. However, multivariate analyses simultaneously considering both variables showed that harvested output of shoots and culms was higher with clear cut and horseshoe cut as compared to selective cut. Given the ease of implementation and issues of work safety, users preferred the horseshoe cut, but the lack of sustainability of shoot production calls for investigating longer cutting cycles.

  20. Exploring Local Approaches to Communicating Global Climate Change Information

    NASA Astrophysics Data System (ADS)

    Stevermer, A. J.

    2002-12-01

    Expected future climate changes are often presented as a global problem, requiring a global solution. Although this statement is accurate, communicating climate change science and prospective solutions must begin at local levels, each with its own subset of complexities to be addressed. Scientific evaluation of local changes can be complicated by large variability occurring over small spatial scales; this variability hinders efforts both to analyze past local changes and to project future ones. The situation is further encumbered by challenges associated with scientific literacy in the U.S., as well as by pressing economic difficulties. For people facing real-life financial and other uncertainties, a projected ``1.4 to 5.8 degrees Celsius'' rise in global temperature is likely to remain only an abstract concept. Despite this lack of concreteness, recent surveys have found that most U.S. residents believe current global warming science, and an even greater number view the prospect of increased warming as at least a ``somewhat serious'' problem. People will often be able to speak of long-term climate changes in their area, whether observed changes in the amount of snow cover in winter, or in the duration of extreme heat periods in summer. This work will explore the benefits and difficulties of communicating climate change from a local, rather than global, perspective, and seek out possible strategies for making less abstract, more concrete, and most importantly, more understandable information available to the public.

  1. Locally advanced rectal cancer: The importance of a multidisciplinary approach

    PubMed Central

    Berardi, Rossana; Maccaroni, Elena; Onofri, Azzurra; Morgese, Francesca; Torniai, Mariangela; Tiberi, Michela; Ferrini, Consuelo; Cascinu, Stefano

    2014-01-01

    Rectal cancer accounts for a relevant part of colorectal cancer cases, with a mortality of 4-10/100000 per year. The development of locoregional recurrences and the occurrence of distant metastases both influences the prognosis of these patients. In the last two decades, new multimodality strategies have improved the prognosis of locally advanced rectal cancer with a significant reduction of local relapse and an increase in terms of overall survival. Radical surgery still remains the principal curative treatment and the introduction of total mesorectal excision has significantly achieved a reduction in terms of local recurrence rates. The employment of neoadjuvant treatment, delivered before surgery, also achieved an improved local control and an increased sphincter preservation rate in low-lying tumors, with an acceptable acute and late toxicity. This review describes the multidisciplinary management of rectal cancer, focusing on the effectiveness of neoadjuvant chemoradiotherapy and of post-operative adjuvant chemotherapy both in the standard combined modality treatment programs and in the ongoing research to improve these regimens. PMID:25516638

  2. Locally advanced rectal cancer: the importance of a multidisciplinary approach.

    PubMed

    Berardi, Rossana; Maccaroni, Elena; Onofri, Azzurra; Morgese, Francesca; Torniai, Mariangela; Tiberi, Michela; Ferrini, Consuelo; Cascinu, Stefano

    2014-12-14

    Rectal cancer accounts for a relevant part of colorectal cancer cases, with a mortality of 4-10/100000 per year. The development of locoregional recurrences and the occurrence of distant metastases both influences the prognosis of these patients. In the last two decades, new multimodality strategies have improved the prognosis of locally advanced rectal cancer with a significant reduction of local relapse and an increase in terms of overall survival. Radical surgery still remains the principal curative treatment and the introduction of total mesorectal excision has significantly achieved a reduction in terms of local recurrence rates. The employment of neoadjuvant treatment, delivered before surgery, also achieved an improved local control and an increased sphincter preservation rate in low-lying tumors, with an acceptable acute and late toxicity. This review describes the multidisciplinary management of rectal cancer, focusing on the effectiveness of neoadjuvant chemoradiotherapy and of post-operative adjuvant chemotherapy both in the standard combined modality treatment programs and in the ongoing research to improve these regimens.

  3. An Adaptive Unstructured Grid Method by Grid Subdivision, Local Remeshing, and Grid Movement

    NASA Technical Reports Server (NTRS)

    Pirzadeh, Shahyar Z.

    1999-01-01

    An unstructured grid adaptation technique has been developed and successfully applied to several three dimensional inviscid flow test cases. The approach is based on a combination of grid subdivision, local remeshing, and grid movement. For solution adaptive grids, the surface triangulation is locally refined by grid subdivision, and the tetrahedral grid in the field is partially remeshed at locations of dominant flow features. A grid redistribution strategy is employed for geometric adaptation of volume grids to moving or deforming surfaces. The method is automatic and fast and is designed for modular coupling with different solvers. Several steady state test cases with different inviscid flow features were tested for grid/solution adaptation. In all cases, the dominant flow features, such as shocks and vortices, were accurately and efficiently predicted with the present approach. A new and robust method of moving tetrahedral "viscous" grids is also presented and demonstrated on a three-dimensional example.

  4. Bayesian multiresolution method for local X-ray tomography in dental radiology

    NASA Astrophysics Data System (ADS)

    Niinimäki, Kati; Siltanen, Samuli; Kolehmainen, Ville

    2009-02-01

    Dental tomographic cone-beam X-ray imaging devices record truncated projections and reconstruct a region of interest (ROI) inside the head. Image reconstruction from the resulting local tomography data is an ill-posed inverse problem. A Bayesian multiresolution method is proposed for the local tomography reconstruction. The inverse problem is formulated in a well-posed statistical form where a prior model of the tissues compensates for the incomplete projection data. Tissues are represented in a reduced wavelet basis, and prior information is modeled in terms of a Besov norm penalty. The number of unknowns in the inverse problem is reduced by abandoning fine-scale wavelets outside the ROI. Compared to traditional voxel based reconstruction methods, this multiresolution approach allows significant reduction in number of unknown parameters without loss of reconstruction accuracy inside the ROI, as shown by two dimensional examples using simulated local tomography data.

  5. New orbit correction method uniting global and local orbit corrections

    NASA Astrophysics Data System (ADS)

    Nakamura, N.; Takaki, H.; Sakai, H.; Satoh, M.; Harada, K.; Kamiya, Y.

    2006-01-01

    A new orbit correction method, called the eigenvector method with constraints (EVC), is proposed and formulated to unite global and local orbit corrections for ring accelerators, especially synchrotron radiation(SR) sources. The EVC can exactly correct the beam positions at arbitrarily selected ring positions such as light source points, simultaneously reducing closed orbit distortion (COD) around the whole ring. Computer simulations clearly demonstrate these features of the EVC for both cases of the Super-SOR light source and the Advanced Light Source (ALS) that have typical structures of high-brilliance SR sources. In addition, the effects of errors in beam position monitor (BPM) reading and steering magnet setting on the orbit correction are analytically expressed and also compared with the computer simulations. Simulation results show that the EVC is very effective and useful for orbit correction and beam position stabilization in SR sources.

  6. Method for localizing and isolating an errant process step

    DOEpatents

    Tobin, Jr., Kenneth W.; Karnowski, Thomas P.; Ferrell, Regina K.

    2003-01-01

    A method for localizing and isolating an errant process includes the steps of retrieving from a defect image database a selection of images each image having image content similar to image content extracted from a query image depicting a defect, each image in the selection having corresponding defect characterization data. A conditional probability distribution of the defect having occurred in a particular process step is derived from the defect characterization data. A process step as a highest probable source of the defect according to the derived conditional probability distribution is then identified. A method for process step defect identification includes the steps of characterizing anomalies in a product, the anomalies detected by an imaging system. A query image of a product defect is then acquired. A particular characterized anomaly is then correlated with the query image. An errant process step is then associated with the correlated image.

  7. Manhole Cover Localization in Aerial Images with a Deep Learning Approach

    NASA Astrophysics Data System (ADS)

    Commandre, B.; En-Nejjary, D.; Pibre, L.; Chaumont, M.; Delenne, C.; Chahinian, N.

    2017-05-01

    Urban growth is an ongoing trend and one of its direct consequences is the development of buried utility networks. Locating these networks is becoming a challenging task. While the labeling of large objects in aerial images is extensively studied in Geosciences, the localization of small objects (smaller than a building) is in counter part less studied and very challenging due to the variance of object colors, cluttered neighborhood, non-uniform background, shadows and aspect ratios. In this paper, we put forward a method for the automatic detection and localization of manhole covers in Very High Resolution (VHR) aerial and remotely sensed images using a Convolutional Neural Network (CNN). Compared to other detection/localization methods for small objects, the proposed approach is more comprehensive as the entire image is processed without prior segmentation. The first experiments using the Prades-Le-Lez and Gigean datasets show that our method is indeed effective as more than 49% of the ground truth database is detected with a precision of 75 %. New improvement possibilities are being explored such as using information on the shape of the detected objects and increasing the types of objects to be detected, thus enabling the extraction of more object specific features.

  8. Local Authority Approaches to the School Admissions Process. LG Group Research Report

    ERIC Educational Resources Information Center

    Rudd, Peter; Gardiner, Clare; Marson-Smith, Helen

    2010-01-01

    What are the challenges, barriers and facilitating factors connected to the various school admissions approaches used by local authorities? This report gathers the views of local authority admissions officers on the strengths and weaknesses of different approaches, as well as the issues and challenges they face in this important area. It covers:…

  9. The Robin Hood method A novel numerical method for electrostatic problems based on a non-local charge transfer

    NASA Astrophysics Data System (ADS)

    Lazić, Predrag; Štefančić, Hrvoje; Abraham, Hrvoje

    2006-03-01

    We introduce a novel numerical method, named the Robin Hood method, of solving electrostatic problems. The approach of the method is closest to the boundary element methods, although significant conceptual differences exist with respect to this class of methods. The method achieves equipotentiality of conducting surfaces by iterative non-local charge transfer. For each of the conducting surfaces, non-local charge transfers are performed between surface elements, which differ the most from the targeted equipotentiality of the surface. The method is tested against analytical solutions and its wide range of application is demonstrated. The method has appealing technical characteristics. For the problem with N surface elements, the computational complexity of the method essentially scales with Nα, where α < 2, the required computer memory scales with N, while the error of the potential decreases exponentially with the number of iterations for many orders of magnitude of the error, without the presence of the Critical Slowing Down. The Robin Hood method could prove useful in other classical or even quantum problems. Some future development ideas for possible applications outside electrostatics are addressed.

  10. Jamming graphs: A local approach to global mechanical rigidity

    NASA Astrophysics Data System (ADS)

    Lopez, Jorge H.; Cao, L.; Schwarz, J. M.

    2013-12-01

    We revisit the concept of minimal rigidity as applied to frictionless, repulsive soft sphere packings in two dimensions with the introduction of the jamming graph. Minimal rigidity is a purely combinatorial property encoded via Laman's theorem in two dimensions. It constrains the global, average coordination number of the graph, for example. However, minimal rigidity does not address the geometry of local mechanical stability. The jamming graph contains both properties of global mechanical stability at the onset of jamming and local mechanical stability. We demonstrate how jamming graphs can be constructed using local moves via the Henneberg construction such that these graphs fall under the jurisdiction of correlated percolation. We then probe how jamming graphs destabilize, or become unjammed, by deleting a bond and computing the resulting rigid cluster distribution. We also study how the system restabilizes with the addition of new contacts and how a jamming graph with extra (redundant) contacts destabilizes. The latter endeavor allows us to probe a disk packing in the rigid phase and uncover a potentially new diverging length scale associated with the random deletion of contacts as compared to the study of cut-out (or frozen-in) subsystems.

  11. Approaching nanoscale oxides: models and theoretical methods.

    PubMed

    Bromley, Stefan T; Moreira, Ibério de P R; Neyman, Konstantin M; Illas, Francesc

    2009-09-01

    This tutorial review deals with the rapidly developing area of modelling oxide materials at the nanoscale. Top-down and bottom-up modelling approaches and currently used theoretical methods are discussed with the help of a selection of case studies. We show that the critical oxide nanoparticle size required to be beyond the scale where every atom counts to where structural and chemical properties are essentially bulk-like (the scalable regime) strongly depends on the structural and chemical parameters of the material under consideration. This oxide-dependent behaviour with respect to size has fundamental implications with respect to their modelling. Strongly ionic materials such as MgO and CeO(2), for example, start to exhibit scalable-to-bulk crystallite-like characteristics for nanoparticles consisting of about 100 ions. For such systems there exists an overlap in nanoparticle size where both top-down and bottom-up theoretical techniques can be applied and the main problem is the choice of the most suitable computational method. However, for more covalent systems such TiO(2) or SiO(2) the onset of the scalable regime is still unclear and for intermediate sized nanoparticles there exists a gap where neither bottom-up nor top-down modelling are fully adequate. In such difficult cases new efforts to design adequate models are required. Further exacerbating these fundamental methodological concerns are oxide nanosystems exhibiting complex electronic and magnetic behaviour. Due to the need for a simultaneous accurate treatment of the atomistic, electronic and spin degrees of freedom for such systems, the top-down vs. bottom-up separation is still large, and only few studies currently exist.

  12. Well-conditioning global-local analysis using stable generalized/extended finite element method for linear elastic fracture mechanics

    NASA Astrophysics Data System (ADS)

    Malekan, Mohammad; Barros, Felicio Bruzzi

    2016-11-01

    Using the locally-enriched strategy to enrich a small/local part of the problem by generalized/extended finite element method (G/XFEM) leads to non-optimal convergence rate and ill-conditioning system of equations due to presence of blending elements. The local enrichment can be chosen from polynomial, singular, branch or numerical types. The so-called stable version of G/XFEM method provides a well-conditioning approach when only singular functions are used in the blending elements. This paper combines numeric enrichment functions obtained from global-local G/XFEM method with the polynomial enrichment along with a well-conditioning approach, stable G/XFEM, in order to show the robustness and effectiveness of the approach. In global-local G/XFEM, the enrichment functions are constructed numerically from the solution of a local problem. Furthermore, several enrichment strategies are adopted along with the global-local enrichment. The results obtained with these enrichments strategies are discussed in detail, considering convergence rate in strain energy, growth rate of condition number, and computational processing. Numerical experiments show that using geometrical enrichment along with stable G/XFEM for global-local strategy improves the convergence rate and the conditioning of the problem. In addition, results shows that using polynomial enrichment for global problem simultaneously with global-local enrichments lead to ill-conditioned system matrices and bad convergence rate.

  13. Intraoperative methods to stage and localize pancreatic and duodenal tumors.

    PubMed

    Norton, J A

    1999-01-01

    Intraoperative methods to stage and localize tumors have dramatically improved. Advances include less invasive methods to obtain comparable results and precise localization of previously occult tumors. The use of new technology including laparoscopy and ultrasound has provided some of these advances, while improved operative techniques have provided others. Laparoscopy with ultrasound has allowed for improved staging of patients with pancreatic cancer and exclusion of patients who are not resectable for cure. We performed laparoscopy with ultrasound on 50 consecutive patients with adenocarcinoma of the pancreas or liver who appeared to have resectable tumors based on preoperative computed tomography. 22 patients (44%) were found to be unresectable because of tumor nodules on the liver and/or peritoneal surfaces or unsuspected distant nodal or liver metastases. The site of disease making the patient unresectable was confirmed by biopsy in each case. Of the 28 remaining patients in whom laparoscopic ultrasound predicted to be resectable for cure, 26 (93%) had all tumor removed. Thus laparoscopy with ultrasound was the best method to select patients for curative surgery. Intraoperative ultrasound (IOUS) has been a critical method to identify insulinomas that are not palpable. Nonpalpable tumors are most commonly in the pancreatic head. Because the pancreatic head is thick and insulinomas are small, of 9 pancreatic head insulinomas only 3 (33%) were palpable. However, IOUS precisely identified each (100%). Others have recommended blind distal pancreatectomy for individuals with insulinoma in whom no tumor can be identified. However, our data suggest that this procedure is contraindicated as these occult tumors are usually within the pancreatic head. Recent series suggest that previously missed gastrinomas are commonly in the duodenum. IOUS is not able to identify these tumors, but other methods can. Of 27 patients with 31 duodenal gastrinomas, palpation identified 19

  14. An adaptive locally linear embedding manifold learning approach for hyperspectral target detection

    NASA Astrophysics Data System (ADS)

    Ziemann, Amanda K.; Messinger, David W.

    2015-05-01

    Algorithms for spectral analysis commonly use parametric or linear models of the data. Research has shown, however, that hyperspectral data -- particularly in materially cluttered scenes -- are not always well-modeled by statistical or linear methods. Here, we propose an approach to hyperspectral target detection that is based on a graph theory model of the data and a manifold learning transformation. An adaptive nearest neighbor (ANN) graph is built on the data, and then used to implement an adaptive version of locally linear embedding (LLE). We artificially induce a target manifold and incorporate it into the adaptive LLE transformation. The artificial target manifold helps to guide the separation of the target data from the background data in the new, transformed manifold coordinates. Then, target detection is performed in the manifold space using Spectral Angle Mapper. This methodology is an improvement over previous iterations of this approach due to the incorporation of ANN, the artificial target manifold, and the choice of detector in the transformed space. We implement our approach in a spatially local way: the image is delineated into square tiles, and the detection maps are normalized across the entire image. Target detection results will be shown using laboratory-measured and scene-derived target data from the SHARE 2012 collect.

  15. An automatic locally-adaptive method to estimate heavily-tailed breakthrough curves from particle distributions

    NASA Astrophysics Data System (ADS)

    Pedretti, Daniele; Fernàndez-Garcia, Daniel

    2013-09-01

    Particle tracking methods to simulate solute transport deal with the issue of having to reconstruct smooth concentrations from a limited number of particles. This is an error-prone process that typically leads to large fluctuations in the determined late-time behavior of breakthrough curves (BTCs). Kernel density estimators (KDE) can be used to automatically reconstruct smooth BTCs from a small number of particles. The kernel approach incorporates the uncertainty associated with subsampling a large population by equipping each particle with a probability density function. Two broad classes of KDE methods can be distinguished depending on the parametrization of this function: global and adaptive methods. This paper shows that each method is likely to estimate a specific portion of the BTCs. Although global methods offer a valid approach to estimate early-time behavior and peak of BTCs, they exhibit important fluctuations at the tails where fewer particles exist. In contrast, locally adaptive methods improve tail estimation while oversmoothing both early-time and peak concentrations. Therefore a new method is proposed combining the strength of both KDE approaches. The proposed approach is universal and only needs one parameter (α) which slightly depends on the shape of the BTCs. Results show that, for the tested cases, heavily-tailed BTCs are properly reconstructed with α ≈ 0.5 .

  16. Socioeconomic determinants of geographic disparities in campylobacteriosis risk: a comparison of global and local modeling approaches

    PubMed Central

    2012-01-01

    Background Socioeconomic factors play a complex role in determining the risk of campylobacteriosis. Understanding the spatial interplay between these factors and disease risk can guide disease control programs. Historically, Poisson and negative binomial models have been used to investigate determinants of geographic disparities in risk. Spatial regression models, which allow modeling of spatial effects, have been used to improve these modeling efforts. Geographically weighted regression (GWR) takes this a step further by estimating local regression coefficients, thereby allowing estimations of associations that vary in space. These recent approaches increase our understanding of how geography influences the associations between determinants and disease. Therefore the objectives of this study were to: (i) identify socioeconomic determinants of the geographic disparities of campylobacteriosis risk (ii) investigate if regression coefficients for the associations between socioeconomic factors and campylobacteriosis risk demonstrate spatial variability and (iii) compare the performance of four modeling approaches: negative binomial, spatial lag, global and local Poisson GWR. Methods Negative binomial, spatial lag, global and local Poisson GWR modeling techniques were used to investigate associations between socioeconomic factors and geographic disparities in campylobacteriosis risk. The best fitting models were identified and compared. Results Two competing four variable models (Models 1 & 2) were identified. Significant variables included race, unemployment rate, education attainment, urbanicity, and divorce rate. Local Poisson GWR had the best fit and showed evidence of spatially varying regression coefficients. Conclusions The international significance of this work is that it highlights the inadequacy of global regression strategies that estimate one parameter per independent variable, and therefore mask the true relationships between dependent and independent

  17. Fast approach to evaluate map reconstruction for lesion detection and localization

    SciTech Connect

    Qi, Jinyi; Huesman, Ronald H.

    2004-02-01

    Lesion detection is an important task in emission tomography. Localization ROC (LROC) studies are often used to analyze the lesion detection and localization performance. Most researchers rely on Monte Carlo reconstruction samples to obtain LROC curves, which can be very time-consuming for iterative algorithms. In this paper we develop a fast approach to obtain LROC curves that does not require Monte Carlo reconstructions. We use a channelized Hotelling observer model to search for lesions, and the results can be easily extended to other numerical observers. We theoretically analyzed the mean and covariance of the observer output. Assuming the observer outputs are multivariate Gaussian random variables, an LROC curve can be directly generated by integrating the conditional probability density functions. The high-dimensional integrals are calculated using a Monte Carlo method. The proposed approach is very fast because no iterative reconstruction is involved. Computer simulations show that the results of the proposed method match well with those obtained using the tradition LROC analysis.

  18. Evaluation of geospatial methods to generate subnational HIV prevalence estimates for local level planning

    PubMed Central

    2016-01-01

    Objective: There is evidence of substantial subnational variation in the HIV epidemic. However, robust spatial HIV data are often only available at high levels of geographic aggregation and not at the finer resolution needed for decision making. Therefore, spatial analysis methods that leverage available data to provide local estimates of HIV prevalence may be useful. Such methods exist but have not been formally compared when applied to HIV. Design/methods: Six candidate methods – including those used by the Joint United Nations Programme on HIV/AIDS to generate maps and a Bayesian geostatistical approach applied to other diseases – were used to generate maps and subnational estimates of HIV prevalence across three countries using cluster level data from household surveys. Two approaches were used to assess the accuracy of predictions: internal validation, whereby a proportion of input data is held back (test dataset) to challenge predictions; and comparison with location-specific data from household surveys in earlier years. Results: Each of the methods can generate usefully accurate predictions of prevalence at unsampled locations, with the magnitude of the error in predictions similar across approaches. However, the Bayesian geostatistical approach consistently gave marginally the strongest statistical performance across countries and validation procedures. Conclusions: Available methods may be able to furnish estimates of HIV prevalence at finer spatial scales than the data currently allow. The subnational variation revealed can be integrated into planning to ensure responsiveness to the spatial features of the epidemic. The Bayesian geostatistical approach is a promising strategy for integrating HIV data to generate robust local estimates. PMID:26919737

  19. Characterization of peak flow events with local singularity method

    NASA Astrophysics Data System (ADS)

    Cheng, Q.; Li, L.; Wang, L.

    2009-07-01

    Three methods, return period, power-law frequency plot (concentration-area) and local singularity index, are introduced in the paper for characterizing peak flow events from river flow data for the past 100 years from 1900 to 2000 recorded at 25 selected gauging stations on rivers in the Oak Ridges Moraine (ORM) area, Canada. First a traditional method, return period, was applied to the maximum annual river flow data. Whereas the Pearson III distribution generally fits the values, a power-law frequency plot (C-A) on the basis of self-similarity principle provides an effective mean for distinguishing "extremely" large flow events from the regular flow events. While the latter show a power-law distribution, about 10 large flow events manifest departure from the power-law distribution and these flow events can be classified into a separate group most of which are related to flood events. It is shown that the relation between the average water releases over a time period after flow peak and the time duration may follow a power-law distribution. The exponent of the power-law or singularity index estimated from this power-law relation may be used to characterize non-linearity of peak flow recessions. Viewing large peak flow events or floods as singular processes can anticipate the application of power-law models not only for characterizing the frequency distribution of peak flow events, for example, power-law relation between the number and size of floods, but also for describing local singularity of processes such as power-law relation between the amount of water released versus releasing time. With the introduction and validation of singularity of peak flow events, alternative power-law models can be used to depict the recession property as well as other types of non-linear properties.

  20. The demonstration of a theory-based approach to the design of localized patient safety interventions

    PubMed Central

    2013-01-01

    Background There is evidence of unsafe care in healthcare systems globally. Interventions to implement recommended practice often have modest and variable effects. Ideally, selecting and adapting interventions according to local contexts should enhance effects. However, the means by which this can happen is seldom systematic, based on theory, or made transparent. This work aimed to demonstrate the applicability, feasibility, and acceptability of a theoretical domains framework implementation (TDFI) approach for co-designing patient safety interventions. Methods We worked with three hospitals to support the implementation of evidence-based guidance to reduce the risk of feeding into misplaced nasogastric feeding tubes. Our stepped process, informed by the TDF and key principles from implementation literature, entailed: involving stakeholders; identifying target behaviors; identifying local factors (barriers and levers) affecting behavior change using a TDF-based questionnaire; working with stakeholders to generate specific local strategies to address key barriers; and supporting stakeholders to implement strategies. Exit interviews and audit data collection were undertaken to assess the feasibility and acceptability of this approach. Results Following audit and discussion, implementation teams for each Trust identified the process of checking the positioning of nasogastric tubes prior to feeding as the key behavior to target. Questionnaire results indicated differences in key barriers between organizations. Focus groups generated innovative, generalizable, and adaptable strategies for overcoming barriers, such as awareness events, screensavers, equipment modifications, and interactive learning resources. Exit interviews identified themes relating to the benefits, challenges, and sustainability of this approach. Time trend audit data were collected for 301 patients over an 18-month period for one Trust, suggesting clinically significant improved use of pH and

  1. Optimizing Local Memory Allocation and Assignment through a Decoupled Approach

    NASA Astrophysics Data System (ADS)

    Diouf, Boubacar; Ozturk, Ozcan; Cohen, Albert

    Software-controlled local memories (LMs) are widely used to provide fast, scalable, power efficient and predictable access to critical data. While many studies addressed LM management, keeping hot data in the LM continues to cause major headache. This paper revisits LM management of arrays in light of recent progresses in register allocation, supporting multiple live-range splitting schemes through a generic integer linear program. These schemes differ in the grain of decision points. The model can also be extended to address fragmentation, assigning live ranges to precise offsets. We show that the links between LM management and register allocation have been underexploited, leaving much fundamental questions open and effective applications to be explored.

  2. Noninvasive localization of electromagnetic epileptic activity. I. Method descriptions and simulations.

    PubMed

    Grave de Peralta Menendez, R; Gonzalez Andino, S; Lantz, G; Michel, C M; Landis, T

    2001-01-01

    This paper considers the solution of the bioelectromagnetic inverse problem with particular emphasis on focal compact sources that are likely to arise in epileptic data. Two linear inverse methods are proposed and evaluated in simulations. The first method belongs to the class of distributed inverse solutions, capable of dealing with multiple simultaneously active sources. This solution is based on a Local Auto Regressive Average (LAURA) model. Since no assumption is made about the number of activated sources, this approach can be applied to data with multiple sources. The second method, EPIFOCUS, assumes that there is only a single focal source. However, in contrast to the single dipole model, it allows the source to have a spatial extent beyond a single point and avoids the non-linear optimization process required by dipole fitting. The performance of both methods is evaluated with synthetic data in noisy and noise free conditions. The simulation results demonstrate that LAURA and EPIFOCUS increase the number of sources retrieved with zero dipole localization error and produce lower maximum error and lower average error compared to Minimum Norm, Weighted Minimum Norm and Minimum Laplacian (LORETA). The results show that EPIFOCUS is a robust and powerful tool to localize focal sources. Alternatives to localize data generated by multiple sources are discussed. A companion paper (Lantz et al. 2001, this issue) illustrates the application of LAURA and EPIFOCUS to the analysis of interictal data in epileptic patients.

  3. Local problems; local solutions: an innovative approach to investigating and addressing causes of maternal deaths in Zambia's Copperbelt

    PubMed Central

    2011-01-01

    Background Maternal mortality in developing countries is high and international targets for reduction are unlikely to be met. Zambia's maternal mortality ratio was 591 per 100,000 live births according to survey data (2007) while routinely collected data captured only about 10% of these deaths. In one district in Zambia medical staff reviewed deaths occurring in the labour ward but no related recommendations were documented nor was there evidence of actions taken to avert further deaths. The Investigate Maternal Deaths and Act (IMDA) approach was designed to address these deficiencies and is comprised of four components; identification of maternal deaths; investigation of factors contributing to the deaths; recommendations for action drawn up by multiple stakeholders and monitoring of progress through existing systems. Methods A pilot was conducted in one district of Zambia. Maternal deaths occurring over a period of twelve months were identified and investigated. Data was collected through in-depth interviews with family, focus group discussions and hospital records. The information was summarized and presented at eleven data sharing meetings to key decision makers, during which recommendations for action were drawn up. An output indicator to monitor progress was included in the routine performance assessment tool. High impact interventions were identified using frequency analysis. Results A total of 56 maternal deaths were investigated. Poor communication, existing risk factors, a lack of resources and case management issues were the broad categories under which contributing factors were assigned. Sixty three recommendations were drawn up by key decision-makers of which two thirds were implemented by the end of the pilot period. Potential high impact actions were related to management of AIDS and pregnancy, human resources, referral mechanisms, birth planning at household level and availability of safe blood. Conclusion In resource constrained settings the IMDA

  4. RFMix: A Discriminative Modeling Approach for Rapid and Robust Local-Ancestry Inference

    PubMed Central

    Maples, Brian K.; Gravel, Simon; Kenny, Eimear E.; Bustamante, Carlos D.

    2013-01-01

    Local-ancestry inference is an important step in the genetic analysis of fully sequenced human genomes. Current methods can only detect continental-level ancestry (i.e., European versus African versus Asian) accurately even when using millions of markers. Here, we present RFMix, a powerful discriminative modeling approach that is faster (∼30×) and more accurate than existing methods. We accomplish this by using a conditional random field parameterized by random forests trained on reference panels. RFMix is capable of learning from the admixed samples themselves to boost performance and autocorrect phasing errors. RFMix shows high sensitivity and specificity in simulated Hispanics/Latinos and African Americans and admixed Europeans, Africans, and Asians. Finally, we demonstrate that African Americans in HapMap contain modest (but nonzero) levels of Native American ancestry (∼0.4%). PMID:23910464

  5. RFMix: a discriminative modeling approach for rapid and robust local-ancestry inference.

    PubMed

    Maples, Brian K; Gravel, Simon; Kenny, Eimear E; Bustamante, Carlos D

    2013-08-08

    Local-ancestry inference is an important step in the genetic analysis of fully sequenced human genomes. Current methods can only detect continental-level ancestry (i.e., European versus African versus Asian) accurately even when using millions of markers. Here, we present RFMix, a powerful discriminative modeling approach that is faster (~30×) and more accurate than existing methods. We accomplish this by using a conditional random field parameterized by random forests trained on reference panels. RFMix is capable of learning from the admixed samples themselves to boost performance and autocorrect phasing errors. RFMix shows high sensitivity and specificity in simulated Hispanics/Latinos and African Americans and admixed Europeans, Africans, and Asians. Finally, we demonstrate that African Americans in HapMap contain modest (but nonzero) levels of Native American ancestry (~0.4%).

  6. Periodic local MP2 method employing orbital specific virtuals

    NASA Astrophysics Data System (ADS)

    Usvyat, Denis; Maschio, Lorenzo; Schütz, Martin

    2015-09-01

    We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not

  7. Periodic local MP2 method employing orbital specific virtuals

    SciTech Connect

    Usvyat, Denis Schütz, Martin; Maschio, Lorenzo

    2015-09-14

    We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not

  8. [Contemporary methods of treatment in local advanced prostate cancer].

    PubMed

    Brzozowska, Anna; Mazurkiewicz, Maria; Starosławska, Elzbieta; Stasiewicz, Dominika; Mocarska, Agnieszka; Burdan, Franciszek

    2012-10-01

    The prostate cancer is one of the most often cancers amongst males. Its frequency is increasing with age. Thanks to widespread of screening denomination of specific prostate specific antigen (PSA), ultrasonography including the one in transrectal (TRUS), computed tomography, magnetic resonance and especially the awareness of society, the number of patients with low local advance of illness is increasing. The basic method of treatment in such cases is still the surgical removal of prostate with seminal bladder or radiotherapy. To this purpose tele-(IMRT, VMAT) or brachytherapy (J125, Ir192, Pa103) is used. In patients with higher risk of progression the radiotherapy may be associated with hormonotherapy (total androgen blockage-LH-RH analog and androgen). Despite numerous clinical researches conducted there is still no selection of optimal sequence of particular methods. Moreover, no explicit effectiveness was determined. The general rule of treatment in patients suffering from prostate cancer still remains individual selection of therapeutic treatment depending on the age of a patient, general condition and especially patient's general preferences. In case of elderly patients and patients with low risk of progression, recommendation of direct observation including systematical PSA denomination, clinical transrectal examination, TRUS, MR of smaller pelvis or scintigraphy of the whole skeleton may be considered.

  9. Exploring many-body localization and thermalization using semiclassical methods

    NASA Astrophysics Data System (ADS)

    Acevedo, O. L.; Safavi-Naini, A.; Schachenmayer, J.; Wall, M. L.; Nandkishore, R.; Rey, A. M.

    2017-09-01

    The discrete truncated Wigner approximation (DTWA) is a semiclassical phase-space method useful for the exploration of many-body quantum dynamics. In this work we investigate many-body localization (MBL) and thermalization using DTWA and compare its performance to exact numerical solutions. By taking as a benchmark case a one-dimensional random field Heisenberg spin chain with short-range interactions, and by comparing to numerically exact techniques, we show that DTWA is able to reproduce dynamical signatures that characterize both the thermal and the MBL phases. It exhibits the best quantitative agreement at short times deep in each of the phases and larger mismatches close to the phase transition. The DTWA captures the logarithmic growth of entanglement in the MBL phase, even though a pure classical mean-field analysis would lead to no dynamics at all. Our results suggest the DTWA can become a useful method to investigate MBL and thermalization in experimentally relevant settings intractable with exact numerical techniques, such as systems with long-range interactions and/or systems in higher dimensions.

  10. A Piecewise Local Partial Least Squares (PLS) Method for the Quantitative Analysis of Plutonium Nitrate Solutions.

    PubMed

    Lascola, Robert; O'Rourke, Patrick E; Kyser, Edward A

    2017-01-01

    We have developed a piecewise local (PL) partial least squares (PLS) analysis method for total plutonium measurements by absorption spectroscopy in nitric acid-based nuclear material processing streams. Instead of using a single PLS model that covers all expected solution conditions, the method selects one of several local models based on an assessment of solution absorbance, acidity, and Pu oxidation state distribution. The local models match the global model for accuracy against the calibration set, but were observed in several instances to be more robust to variations associated with measurements in the process. The improvements are attributed to the relative parsimony of the local models. Not all of the sources of spectral variation are uniformly present at each part of the calibration range. Thus, the global model is locally overfitting and susceptible to increased variance when presented with new samples. A second set of models quantifies the relative concentrations of Pu(III), (IV), and (VI). Standards containing a mixture of these species were not at equilibrium due to a disproportionation reaction. Therefore, a separate principal component analysis is used to estimate of the concentrations of the individual oxidation states in these standards in the absence of independent confirmatory analysis. The PL analysis approach is generalizable to other systems where the analysis of chemically complicated systems can be aided by rational division of the overall range of solution conditions into simpler sub-regions.

  11. Nonlinear optical methods for cellular imaging and localization.

    PubMed

    McVey, A; Crain, J

    2014-07-01

    Of all the ways in which complex materials (including many biological systems) can be explored, imaging is perhaps the most powerful because delivering high information content directly. This is particular relevant in aspects of cellular localization where the physical proximity of molecules is crucial in biochemical processes. A great deal of effort in imaging has been spent on enabling chemically selective imaging so that only specific features are revealed. This is almost always achieved by adding fluorescent chemical labels to specific molecules. Under appropriate illumination conditions only the molecules (via their labels) will be visible. The technique is simple and elegant but does suffer from fundamental limitations: (1) the fluorescent labels may fade when illuminated (a phenomenon called photobleaching) thereby constantly decreasing signal contrast over the course of image acquisition. To combat photobleaching one must reduce observation times or apply unfavourably low excitation levels all of which reduce the information content of images; (2) the fluorescent species may be deactivated by various environmental factors (the general term is fluorescence quenching); (3) the presence of fluorescent labels may introduce unexpected complications or may interfere with processes of interest (4) Some molecules of interest cannot be labelled. In these circumstances we require a fundamentally different strategy. One of the most promising alternative is based on a technique called Coherent Anti-Stokes Raman scattering (CARS). CARS is a fundamentally more complex process than is fluorescence and the experimental procedures and optical systems required to deliver high quality CARS images are intricate. However, the rewards are correspondingly very high: CARS probes the chemically distinct vibrations of the constituent molecules in a complex system and is therefore also chemically selective as are fluorescence-based methods. Moreover,the potentially severe problems of

  12. Biclustering as a method for RNA local multiple sequence alignment.

    PubMed

    Wang, Shu; Gutell, Robin R; Miranker, Daniel P

    2007-12-15

    Biclustering is a clustering method that simultaneously clusters both the domain and range of a relation. A challenge in multiple sequence alignment (MSA) is that the alignment of sequences is often intended to reveal groups of conserved functional subsequences. Simultaneously, the grouping of the sequences can impact the alignment; precisely the kind of dual situation biclustering is intended to address. We define a representation of the MSA problem enabling the application of biclustering algorithms. We develop a computer program for local MSA, BlockMSA, that combines biclustering with divide-and-conquer. BlockMSA simultaneously finds groups of similar sequences and locally aligns subsequences within them. Further alignment is accomplished by dividing both the set of sequences and their contents. The net result is both a multiple sequence alignment and a hierarchical clustering of the sequences. BlockMSA was tested on the subsets of the BRAliBase 2.1 benchmark suite that display high variability and on an extension to that suite to larger problem sizes. Also, alignments were evaluated of two large datasets of current biological interest, T box sequences and Group IC1 Introns. The results were compared with alignments computed by ClustalW, MAFFT, MUCLE and PROBCONS alignment programs using Sum of Pairs (SPS) and Consensus Count. Results for the benchmark suite are sensitive to problem size. On problems of 15 or greater sequences, BlockMSA is consistently the best. On none of the problems in the test suite are there appreciable differences in scores among BlockMSA, MAFFT and PROBCONS. On the T box sequences, BlockMSA does the most faithful job of reproducing known annotations. MAFFT and PROBCONS do not. On the Intron sequences, BlockMSA, MAFFT and MUSCLE are comparable at identifying conserved regions. BlockMSA is implemented in Java. Source code and supplementary datasets are available at http://aug.csres.utexas.edu/msa/

  13. An efficient implementation of the localized operator partitioning method for electronic energy transfer

    NASA Astrophysics Data System (ADS)

    Nagesh, Jayashree; Izmaylov, Artur F.; Brumer, Paul

    2015-02-01

    The localized operator partitioning method [Y. Khan and P. Brumer, J. Chem. Phys. 137, 194112 (2012)] rigorously defines the electronic energy on any subsystem within a molecule and gives a precise meaning to the subsystem ground and excited electronic energies, which is crucial for investigating electronic energy transfer from first principles. However, an efficient implementation of this approach has been hindered by complicated one- and two-electron integrals arising in its formulation. Using a resolution of the identity in the definition of partitioning, we reformulate the method in a computationally efficient manner that involves standard one- and two-electron integrals. We apply the developed algorithm to the 9 - ((1 - naphthyl) - methyl) - anthracene (A1N) molecule by partitioning A1N into anthracenyl and CH2 - naphthyl groups as subsystems and examine their electronic energies and populations for several excited states using configuration interaction singles method. The implemented approach shows a wide variety of different behaviors amongst the excited electronic states.

  14. Local Analysis Approach for Short Wavelength Geopotential Variations

    NASA Astrophysics Data System (ADS)

    Bender, P. L.

    2009-12-01

    The value of global spherical harmonic analyses for determining 15 day to 30 day changes in the Earth's gravity field has been demonstrated extensively using data from the GRACE mission and previous missions. However, additional useful information appears to be obtainable from local analyses of the data. A number of such analyses have been carried out by various groups. In the energy approximation, the changes in the height of the satellite altitude geopotential can be determined from the post-fit changes in the satellite separation during individual one-revolution arcs of data from a GRACE-type pair of satellites in a given orbit. For a particular region, it is assumed that short wavelength spatial variations for the arcs crossing that region during a time T of interest would be used to determine corrections to the spherical harmonic results. The main issue in considering higher measurement accuracy in future missions is how much improvement in spatial resolution can be achieved. For this, the shortest wavelengths that can be determined are the most important. And, while the longer wavelength variations are affected by mass distribution changes over much of the globe, the shorter wavelength ones hopefully will be determined mainly by more local changes in the mass distribution. Future missions are expected to have much higher accuracy for measuring changes in the satellite separation than GRACE. However, how large an improvement in the derived results in hydrology will be achieved is still very much a matter of study, particularly because of the effects of uncertainty in the time variations in the atmospheric and oceanic mass distributions. To be specific, it will be assumed that improving the spatial resolution in continental regions away from the coastlines is the objective, and that the satellite altitude is in the range of roughly 290 to 360 km made possible for long missions by drag-free operation. The advantages of putting together the short wavelength

  15. Local and global approaches to the problem of Poincaré recurrences. Applications in nonlinear dynamics

    NASA Astrophysics Data System (ADS)

    Anishchenko, V. S.; Boev, Ya. I.; Semenova, N. I.; Strelkova, G. I.

    2015-07-01

    We review rigorous and numerical results on the statistics of Poincaré recurrences which are related to the modern development of the Poincaré recurrence problem. We analyze and describe the rigorous results which are achieved both in the classical (local) approach and in the recently developed global approach. These results are illustrated by numerical simulation data for simple chaotic and ergodic systems. It is shown that the basic theoretical laws can be applied to noisy systems if the probability measure is ergodic and stationary. Poincaré recurrences are studied numerically in nonautonomous systems. Statistical characteristics of recurrences are analyzed in the framework of the global approach for the cases of positive and zero topological entropy. We show that for the positive entropy, there is a relationship between the Afraimovich-Pesin dimension, Lyapunov exponents and the Kolmogorov-Sinai entropy either without and in the presence of external noise. The case of zero topological entropy is exemplified by numerical results for the Poincare recurrence statistics in the circle map. We show and prove that the dependence of minimal recurrence times on the return region size demonstrates universal properties for the golden and the silver ratio. The behavior of Poincaré recurrences is analyzed at the critical point of Feigenbaum attractor birth. We explore Poincaré recurrences for an ergodic set which is generated in the stroboscopic section of a nonautonomous oscillator and is similar to a circle shift. Based on the obtained results we show how the Poincaré recurrence statistics can be applied for solving a number of nonlinear dynamics issues. We propose and illustrate alternative methods for diagnosing effects of external and mutual synchronization of chaotic systems in the context of the local and global approaches. The properties of the recurrence time probability density can be used to detect the stochastic resonance phenomenon. We also discuss how

  16. Local Bathymetry Estimation Using Variational Inverse Modeling: A Nested Approach

    NASA Astrophysics Data System (ADS)

    Almeida, T. G.; Walker, D. T.; Farquharson, G.

    2014-12-01

    Estimation of subreach river bathymetry from remotely-sensed surface velocity data is presented using variational inverse modeling applied to the 2D depth-averaged, shallow-water equations (SWEs). A nested approach is adopted to focus on obtaining an accurate estimate of bathymetry over a small region of interest within a larger complex hydrodynamic system. This approach reduces computational cost significantly. We begin by constructing a minimization problem with a cost function defined by the error between observed and estimated surface velocities, and then apply the SWEs as a constraint on the velocity field. An adjoint SWE model is developed through the use of Lagrange multipliers, converting the unconstrained minimization problem into a constrained one. The adjoint model solution is used to calculate the gradient of the cost function with respect to bathymetry. The gradient is used in a descent algorithm to determine the bathymetry that yields a surface velocity field that is a best-fit to the observational data. In this application of the algorithm, the 2D depth-averaged flow is computed within a nested framework using Delft3D-FLOW as the forward computational model. First, an outer simulation is generated using discharge rate and other measurements from USGS and NOAA, assuming a uniform bottom-friction coefficient. Then a nested, higher resolution inner model is constructed using open boundary condition data interpolated from the outer model (see figure). Riemann boundary conditions with specified tangential velocities are utilized to ensure a near seamless transition between outer and inner model results. The initial guess bathymetry matches the outer model bathymetry, and the iterative assimilation procedure is used to adjust the bathymetry only for the inner model. The observation data was collected during the ONR Rivet II field exercise for the mouth of the Columbia River near Hammond, OR. A dual beam squinted along-track-interferometric, synthetic

  17. A Challenging Surgical Approach to Locally Advanced Primary Urethral Carcinoma

    PubMed Central

    Lucarelli, Giuseppe; Spilotros, Marco; Vavallo, Antonio; Palazzo, Silvano; Miacola, Carlos; Forte, Saverio; Matera, Matteo; Campagna, Marcello; Colamonico, Ottavio; Schiralli, Francesco; Sebastiani, Francesco; Di Cosmo, Federica; Bettocchi, Carlo; Di Lorenzo, Giuseppe; Buonerba, Carlo; Vincenti, Leonardo; Ludovico, Giuseppe; Ditonno, Pasquale; Battaglia, Michele

    2016-01-01

    Abstract Primary urethral carcinoma (PUC) is a rare and aggressive cancer, often underdetected and consequently unsatisfactorily treated. We report a case of advanced PUC, surgically treated with combined approaches. A 47-year-old man underwent transurethral resection of a urethral lesion with histological evidence of a poorly differentiated squamous cancer of the bulbomembranous urethra. Computed tomography (CT) and bone scans excluded metastatic spread of the disease but showed involvement of both corpora cavernosa (cT3N0M0). A radical surgical approach was advised, but the patient refused this and opted for chemotherapy. After 17 months the patient was referred to our department due to the evidence of a fistula in the scrotal area. CT scan showed bilateral metastatic disease in the inguinal, external iliac, and obturator lymph nodes as well as the involvement of both corpora cavernosa. Additionally, a fistula originating from the right corpus cavernosum extended to the scrotal skin. At this stage, the patient accepted the surgical treatment, consisting of different phases. Phase I: Radical extraperitoneal cystoprostatectomy with iliac-obturator lymph nodes dissection. Phase II: Creation of a urinary diversion through a Bricker ileal conduit. Phase III: Repositioning of the patient in lithotomic position for an overturned Y skin incision, total penectomy, fistula excision, and “en bloc” removal of surgical specimens including the bladder, through the perineal breach. Phase IV: Right inguinal lymphadenectomy. The procedure lasted 9-and-a-half hours, was complication-free, and intraoperative blood loss was 600 mL. The patient was discharged 8 days after surgery. Pathological examination documented a T4N2M0 tumor. The clinical situation was stable during the first 3 months postoperatively but then metastatic spread occurred, not responsive to adjuvant chemotherapy, which led to the patient's death 6 months after surgery. Patients with advanced stage tumors of

  18. A hybrid approach to protein folding problem integrating constraint programming with local search

    PubMed Central

    2010-01-01

    Background The protein folding problem remains one of the most challenging open problems in computational biology. Simplified models in terms of lattice structure and energy function have been proposed to ease the computational hardness of this optimization problem. Heuristic search algorithms and constraint programming are two common techniques to approach this problem. The present study introduces a novel hybrid approach to simulate the protein folding problem using constraint programming technique integrated within local search. Results Using the face-centered-cubic lattice model and 20 amino acid pairwise interactions energy function for the protein folding problem, a constraint programming technique has been applied to generate the neighbourhood conformations that are to be used in generic local search procedure. Experiments have been conducted for a few small and medium sized proteins. Results have been compared with both pure constraint programming approach and local search using well-established local move set. Substantial improvements have been observed in terms of final energy values within acceptable runtime using the hybrid approach. Conclusion Constraint programming approaches usually provide optimal results but become slow as the problem size grows. Local search approaches are usually faster but do not guarantee optimal solutions and tend to stuck in local minima. The encouraging results obtained on the small proteins show that these two approaches can be combined efficiently to obtain better quality solutions within acceptable time. It also encourages future researchers on adopting hybrid techniques to solve other hard optimization problems. PMID:20122212

  19. Qualitative Approaches to Mixed Methods Practice

    ERIC Educational Resources Information Center

    Hesse-Biber, Sharlene

    2010-01-01

    This article discusses how methodological practices can shape and limit how mixed methods is practiced and makes visible the current methodological assumptions embedded in mixed methods practice that can shut down a range of social inquiry. The article argues that there is a "methodological orthodoxy" in how mixed methods is practiced…

  20. Qualitative Approaches to Mixed Methods Practice

    ERIC Educational Resources Information Center

    Hesse-Biber, Sharlene

    2010-01-01

    This article discusses how methodological practices can shape and limit how mixed methods is practiced and makes visible the current methodological assumptions embedded in mixed methods practice that can shut down a range of social inquiry. The article argues that there is a "methodological orthodoxy" in how mixed methods is practiced…

  1. An Integrated Approach to Indoor and Outdoor Localization

    DTIC Science & Technology

    2017-04-17

    SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) AF Office of Scientific Research 875 N. Randolph St. Room 3112 Arlington, VA 22203 10. SPONSOR/MONITOR’S...spaces. Several systems have been able to demonstrate room level accuracy e.g. approximately 5 to 10m using this method. At the Microsoft Indoor...and change in orientation. b) The state of particles prior to a step update. c) The state of the particles after a step update. 7a the red arrow

  2. Jacobian-Based Iterative Method for Magnetic Localization in Robotic Capsule Endoscopy.

    PubMed

    Di Natali, Christian; Beccani, Marco; Simaan, Nabil; Valdastri, Pietro

    2016-04-01

    The purpose of this study is to validate a Jacobian-based iterative method for real-time localization of magnetically controlled endoscopic capsules. The proposed approach applies finite-element solutions to the magnetic field problem and least-squares interpolations to obtain closed-form and fast estimates of the magnetic field. By defining a closed-form expression for the Jacobian of the magnetic field relative to changes in the capsule pose, we are able to obtain an iterative localization at a faster computational time when compared with prior works, without suffering from the inaccuracies stemming from dipole assumptions. This new algorithm can be used in conjunction with an absolute localization technique that provides initialization values at a slower refresh rate. The proposed approach was assessed via simulation and experimental trials, adopting a wireless capsule equipped with a permanent magnet, six magnetic field sensors, and an inertial measurement unit. The overall refresh rate, including sensor data acquisition and wireless communication was 7 ms, thus enabling closed-loop control strategies for magnetic manipulation running faster than 100 Hz. The average localization error, expressed in cylindrical coordinates was below 7 mm in both the radial and axial components and 5° in the azimuthal component. The average error for the capsule orientation angles, obtained by fusing gyroscope and inclinometer measurements, was below 5°.

  3. Jacobian-Based Iterative Method for Magnetic Localization in Robotic Capsule Endoscopy

    PubMed Central

    Di Natali, Christian; Beccani, Marco; Simaan, Nabil; Valdastri, Pietro

    2016-01-01

    The purpose of this study is to validate a Jacobian-based iterative method for real-time localization of magnetically controlled endoscopic capsules. The proposed approach applies finite-element solutions to the magnetic field problem and least-squares interpolations to obtain closed-form and fast estimates of the magnetic field. By defining a closed-form expression for the Jacobian of the magnetic field relative to changes in the capsule pose, we are able to obtain an iterative localization at a faster computational time when compared with prior works, without suffering from the inaccuracies stemming from dipole assumptions. This new algorithm can be used in conjunction with an absolute localization technique that provides initialization values at a slower refresh rate. The proposed approach was assessed via simulation and experimental trials, adopting a wireless capsule equipped with a permanent magnet, six magnetic field sensors, and an inertial measurement unit. The overall refresh rate, including sensor data acquisition and wireless communication was 7 ms, thus enabling closed-loop control strategies for magnetic manipulation running faster than 100 Hz. The average localization error, expressed in cylindrical coordinates was below 7 mm in both the radial and axial components and 5° in the azimuthal component. The average error for the capsule orientation angles, obtained by fusing gyroscope and inclinometer measurements, was below 5°. PMID:27087799

  4. Integrated approach to improving local CD uniformity in EUV patterning

    NASA Astrophysics Data System (ADS)

    Liang, Andrew; Hermans, Jan; Tran, Timothy; Viatkina, Katja; Liang, Chen-Wei; Ward, Brandon; Chuang, Steven; Yu, Jengyi; Harm, Greg; Vandereyken, Jelle; Rio, David; Kubis, Michael; Tan, Samantha; Dusa, Mircea; Singhal, Akhil; van Schravendijk, Bart; Dixit, Girish; Shamma, Nader

    2017-03-01

    Extreme ultraviolet (EUV) lithography is crucial to enabling technology scaling in pitch and critical dimension (CD). Currently, one of the key challenges of introducing EUV lithography to high volume manufacturing (HVM) is throughput, which requires high source power and high sensitivity chemically amplified photoresists. Important limiters of high sensitivity chemically amplified resists (CAR) are the effects of photon shot noise and resist blur on the number of photons received and of photoacids generated per feature, especially at the pitches required for 7 nm and 5 nm advanced technology nodes. These stochastic effects are reflected in via structures as hole-to-hole CD variation or local CD uniformity (LCDU). Here, we demonstrate a synergy of film stack deposition, EUV lithography, and plasma etch techniques to improve LCDU, which allows the use of high sensitivity resists required for the introduction of EUV HVM. Thus, to improve LCDU to a level required by 5 nm node and beyond, film stack deposition, EUV lithography, and plasma etch processes were combined and co-optimized to enhance LCDU reduction from synergies. Test wafers were created by depositing a pattern transfer stack on a substrate representative of a 5 nm node target layer. The pattern transfer stack consisted of an atomically smooth adhesion layer and two hardmasks and was deposited using the Lam VECTOR PECVD product family. These layers were designed to mitigate hole roughness, absorb out-of-band radiation, and provide additional outlets for etch to improve LCDU and control hole CD. These wafers were then exposed through an ASML NXE3350B EUV scanner using a variety of advanced positive tone EUV CAR. They were finally etched to the target substrate using Lam Flex dielectric etch and Kiyo conductor etch systems. Metrology methodologies to assess dimensional metrics as well as chip performance and defectivity were investigated to enable repeatable patterning process development. Illumination

  5. Training NOAA Staff on Effective Communication Methods with Local Climate Users

    NASA Astrophysics Data System (ADS)

    Timofeyeva, M. M.; Mayes, B.

    2011-12-01

    Since 2002 NOAA National Weather Service (NWS) Climate Services Division (CSD) offered training opportunities to NWS staff. As a result of eight-year-long development of the training program, NWS offers three training courses and about 25 online distance learning modules covering various climate topics: climate data and observations, climate variability and change, NWS national and local climate products, their tools, skill, and interpretation. Leveraging climate information and expertise available at all NOAA line offices and partners allows delivery of the most advanced knowledge and is a very critical aspect of the training program. NWS challenges in providing local climate services includes effective communication techniques on provide highly technical scientific information to local users. Addressing this challenge requires well trained, climate-literate workforce at local level capable of communicating the NOAA climate products and services as well as provide climate-sensitive decision support. Trained NWS climate service personnel use proactive and reactive approaches and professional education methods in communicating climate variability and change information to local users. Both scientifically-unimpaired messages and amiable communication techniques such as story telling approach are important in developing an engaged dialog between the climate service providers and users. Several pilot projects NWS CSD conducted in the past year applied the NWS climate services training program to training events for NOAA technical user groups. The technical user groups included natural resources managers, engineers, hydrologists, and planners for transportation infrastructure. Training of professional user groups required tailoring the instructions to the potential applications of each group of users. Training technical user identified the following critical issues: (1) Knowledge of target audience expectations, initial knowledge status, and potential use of climate

  6. Epilesional scarification. Preliminary report of a new approach to local immunotherapy with BCG.

    PubMed

    Richman, S P; Mavligit, G M; Wolk, R; Gutterman, J U; Hersh, E M

    1975-12-22

    Because of the serious toxicity of intralesionally injected BCG, including high fever, local ulceration, chronic drainage, and disseminated BCG disease, 13 patients received local BCG immunotherapy by the new approach of epilesional scarification. Three patients had complete responses, four had partial responses, and six had no response. Toxic reactions were minimal compared to those reported for intralesionally given BCG.

  7. Comparing passive source localization and tracking approaches with a towed horizontal receiver array in an ocean waveguide.

    PubMed

    Gong, Zheng; Tran, Duong D; Ratilal, Purnima

    2013-11-01

    Approaches for instantaneous passive source localization using a towed horizontal receiver array in a random range-dependent ocean waveguide are examined. They include: (1) Moving array triangulation, (2) array invariant, (3) bearings-only target motion analysis in modified polar coordinates via the extended Kalman filter, and (4) bearings-migration minimum mean-square error. These methods are applied to localize and track a vertical source array deployed in the far-field of a towed horizontal receiver array during the Gulf of Maine 2006 Experiment. The source transmitted intermittent broadband pulses in the 300 to 1200 Hz frequency range. A nonlinear matched-filter kernel designed to replicate the acoustic signal measured by the receiver array is applied to enhance the signal-to-noise ratio. The source localization accuracy is found to be highly dependent on source-receiver geometry and the localization approach. For a relatively stationary source drifting at speeds much slower than the receiver array tow-speed, the mean source position can be estimated by moving array triangulation with less than 3% error near broadside direction. For a moving source, the Kalman filter method gives the best performance with 5.5% error. The array invariant is the best approach for localizing sources within the endfire beam of the receiver array with 7% error.

  8. Approach of high density coal preparation method

    SciTech Connect

    Yang, Y.; Chen, Q.

    1996-12-31

    Density difference of aged anthracite coal of high density and discard is less than that of general coal and discard; conventional separation methods are difficult to be used. For the special coal, coal dry beneficiation technology with air-dense medium fluidized bed has obvious superiority over other separation methods.

  9. A simple and effective semi-invasive method for inducing local hypothermia in rat spinal cord.

    PubMed

    Bazley, Faith A; Pashai, Nikta; Kerr, Candace; Thakor, Nitish; All, Angelo H

    2013-01-01

    Hypothermia has been shown to be an effective treatment for spinal cord injury. Local hypothermia is advantageous because it avoids inducing systemic side effects of general hypothermia while providing the opportunity for greater temperature reduction at the site of injury, which may contribute to increased neuroprotection. We report a new semi-invasive method for inducing local hypothermia in rats' spinal cords. Our method does not require laminectomy or penetration of the dura and is more effective at cooling the cord than transcutaneous approaches. We show that we were successfully able to cool the spinal cord to 30.2 ± 0.3°C for 2 hours with rectal temperature maintained at 37.3 ± 0.3°C after a spinal cord contusion injury. We also validated our method in control rats that received only a laminectomy. Furthermore, this method was able to reliably cool and rewarm the cord at a steady rate (Δ5.5°C in 30 min, or 0.2°C/min). Future work will include validating long-term functional improvements of injured rats after treatment and to apply local cooling to other spinal cord injury models, such as compression injuries.

  10. A generalized finite element method with global-local enrichment functions for confined plasticity problems

    NASA Astrophysics Data System (ADS)

    Kim, D.-J.; Duarte, C. A.; Proenca, S. P.

    2012-11-01

    The main feature of partition of unity methods such as the generalized or extended finite element method is their ability of utilizing a priori knowledge about the solution of a problem in the form of enrichment functions. However, analytical derivation of enrichment functions with good approximation properties is mostly limited to two-dimensional linear problems. This paper presents a procedure to numerically generate proper enrichment functions for three-dimensional problems with confined plasticity where plastic evolution is gradual. This procedure involves the solution of boundary value problems around local regions exhibiting nonlinear behavior and the enrichment of the global solution space with the local solutions through the partition of unity method framework. This approach can produce accurate nonlinear solutions with a reduced computational cost compared to standard finite element methods since computationally intensive nonlinear iterations can be performed on coarse global meshes after the creation of enrichment functions properly describing localized nonlinear behavior. Several three-dimensional nonlinear problems based on the rate-independent J 2 plasticity theory with isotropic hardening are solved using the proposed procedure to demonstrate its robustness, accuracy and computational efficiency.

  11. An MRI denoising method using image data redundancy and local SNR estimation.

    PubMed

    Golshan, Hosein M; Hasanzadeh, Reza P R; Yousefzadeh, Shahrokh C

    2013-09-01

    This paper presents an LMMSE-based method for the three-dimensional (3D) denoising of MR images assuming a Rician noise model. Conventionally, the LMMSE method estimates the noise-less signal values using the observed MR data samples within local neighborhoods. This is not an efficient procedure to deal with this issue while the 3D MR data intrinsically includes many similar samples that can be used to improve the estimation results. To overcome this problem, we model MR data as random fields and establish a principled way which is capable of choosing the samples not only from a local neighborhood but also from a large portion of the given data. To follow the similar samples within the MR data, an effective similarity measure based on the local statistical moments of images is presented. The parameters of the proposed filter are automatically chosen from the estimated local signal-to-noise ratio. To further enhance the denoising performance, a recursive version of the introduced approach is also addressed. The proposed filter is compared with related state-of-the-art filters using both synthetic and real MR datasets. The experimental results demonstrate the superior performance of our proposal in removing the noise and preserving the anatomical structures of MR images.

  12. A new heuristic method for approximating the number of local minima in partial RNA energy landscapes.

    PubMed

    Albrecht, Andreas A; Day, Luke; Abdelhadi Ep Souki, Ouala; Steinhöfel, Kathleen

    2016-02-01

    The analysis of energy landscapes plays an important role in mathematical modelling, simulation and optimisation. Among the main features of interest are the number and distribution of local minima within the energy landscape. Granier and Kallel proposed in 2002 a new sampling procedure for estimating the number of local minima. In the present paper, we focus on improved heuristic implementations of the general framework devised by Granier and Kallel with regard to run-time behaviour and accuracy of predictions. The new heuristic method is demonstrated for the case of partial energy landscapes induced by RNA secondary structures. While the computation of minimum free energy RNA secondary structures has been studied for a long time, the analysis of folding landscapes has gained momentum over the past years in the context of co-transcriptional folding and deeper insights into cell processes. The new approach has been applied to ten RNA instances of length between 99 nt and 504 nt and their respective partial energy landscapes defined by secondary structures within an energy offset ΔE above the minimum free energy conformation. The number of local minima within the partial energy landscapes ranges from 1440 to 3441. Our heuristic method produces for the best approximations on average a deviation below 3.0% from the true number of local minima.

  13. Optogenetics in the cerebellum: Purkinje cell-specific approaches for understanding local cerebellar functions.

    PubMed

    Tsubota, Tadashi; Ohashi, Yohei; Tamura, Keita

    2013-10-15

    The cerebellum consists of the cerebellar cortex and the cerebellar nuclei. Although the basic neuronal circuitry of the cerebellar cortex is uniform everywhere, anatomical data demonstrate that the input and output relationships of the cortex are spatially segregated between different cortical areas, which suggests that there are functional distinctions between these different areas. Perturbation of cerebellar cortical functions in a spatially restricted fashion is thus essential for investigating the distinctions among different cortical areas. In the cerebellar cortex, Purkinje cells are the sole output neurons that send information to downstream cerebellar and vestibular nuclei. Therefore, selective manipulation of Purkinje cell activities, without disturbing other neuronal types and passing fibers within the cortex, is a direct approach to spatially restrict the effects of perturbations. Although this type of approach has for many years been technically difficult, recent advances in optogenetics now enable selective activation or inhibition of Purkinje cell activities, with high temporal resolution. Here we discuss the effectiveness of using Purkinje cell-specific optogenetic approaches to elucidate the functions of local cerebellar cortex regions. We also discuss what improvements to current methods are necessary for future investigations of cerebellar functions to provide further advances. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. In situ localization of epidermal stem cells using a novel multi epitope ligand cartography approach.

    PubMed

    Ruetze, Martin; Gallinat, Stefan; Wenck, Horst; Deppert, Wolfgang; Knott, Anja

    2010-06-01

    Precise knowledge of the frequency and localization of epidermal stem cells within skin tissue would further our understanding of their role in maintaining skin homeostasis. As a novel approach we used the recently developed method of multi epitope ligand cartography, applying a set of described putative epidermal stem cell markers. Bioinformatic evaluation of the data led to the identification of several discrete basal keratinocyte populations, but none of them displayed the complete stem cell marker set. The distribution of the keratinocyte populations within the tissue was remarkably heterogeneous, but determination of distance relationships revealed a population of quiescent cells highly expressing p63 and the integrins alpha(6)/beta(1) that represent origins of a gradual differentiation lineage. This population comprises about 6% of all basal cells, shows a scattered distribution pattern and could also be found in keratinocyte holoclone colonies. The data suggest that this population identifies interfollicular epidermal stem cells.

  15. Improved cluster-in-molecule local correlation approach for electron correlation calculation of large systems.

    PubMed

    Guo, Yang; Li, Wei; Li, Shuhua

    2014-10-02

    An improved cluster-in-molecule (CIM) local correlation approach is developed to allow electron correlation calculations of large systems more accurate and faster. We have proposed a refined strategy of constructing virtual LMOs of various clusters, which is suitable for basis sets of various types. To recover medium-range electron correlation, which is important for quantitative descriptions of large systems, we find that a larger distance threshold (ξ) is necessary for highly accurate results. Our illustrative calculations show that the present CIM-MP2 (second-order Møller-Plesser perturbation theory, MP2) or CIM-CCSD (coupled cluster singles and doubles, CCSD) scheme with a suitable ξ value is capable of recovering more than 99.8% correlation energies for a wide range of systems at different basis sets. Furthermore, the present CIM-MP2 scheme can provide reliable relative energy differences as the conventional MP2 method for secondary structures of polypeptides.

  16. Systematic and general method for quantifying localization in microscopy images

    PubMed Central

    Sheng, Huanjie; Stauffer, Weston

    2016-01-01

    ABSTRACT Quantifying the localization of molecules with respect to other molecules, cell structures and intracellular regions is essential to understanding their regulation and actions. However, measuring localization from microscopy images is often difficult with existing metrics. Here, we evaluate a metric for quantifying localization termed the threshold overlap score (TOS), and show it is simple to calculate, easy to interpret, able to be used to systematically characterize localization patterns, and generally applicable. TOS is calculated by: (i) measuring the overlap of pixels that are above the intensity thresholds for two signals; (ii) determining whether the overlap is more, less, or the same as expected by chance, i.e. colocalization, anti-colocalization, or non-colocalization; and (iii) rescaling to allow comparison at different thresholds. The above is repeated at multiple threshold combinations to generate a TOS matrix to systematically characterize the relationship between localization and signal intensities. TOS matrices were used to identify and distinguish localization patterns of different proteins in various simulations, cell types and organisms with greater specificity and sensitivity than common metrics. For all the above reasons, TOS is an excellent first line metric, particularly for cells with mixed localization patterns. PMID:27979831

  17. Local Table Condensation in Rough Set Approach for Jumping Emerging Pattern Induction

    NASA Astrophysics Data System (ADS)

    Terlecki, Pawel; Walczak, Krzysztof

    This paper extends the rough set approach for JEP induction based on the notion of a condensed decision table. The original transaction database is transformed to a relational form and patterns are induced by means of local reducts. The transformation employs an item aggregation obtained by coloring a graph that re0ects con0icts among items. For e±ciency reasons we propose to perform this preprocessing locally, i.e. at the transaction level, to achieve a higher dimensionality gain. Special maintenance strategy is also used to avoid graph rebuilds. Both global and local approach have been tested and discussed for dense and synthetically generated sparse datasets.

  18. Strategy for the Development of a DNB Local Predictive Approach Based on Neptune CFD Software

    SciTech Connect

    Haynes, Pierre-Antoine; Peturaud, Pierre; Montout, Michael; Hervieu, Eric

    2006-07-01

    The NEPTUNE project constitutes the thermal-hydraulics part of a long-term joint development program for the next generation of nuclear reactor simulation tools. This project is being carried through by EDF (Electricite de France) and CEA (Commissariat a l'Energie Atomique), with the co-sponsorship of IRSN (Institut de Radioprotection et de Surete Nucleaire) and AREVA NP. NEPTUNE is a multi-phase flow software platform that includes advanced physical models and numerical methods for each simulation scale (CFD, component, system). NEPTUNE also provides new multi-scale and multi-disciplinary coupling functionalities. This new generation of two-phase flow simulation tools aims at meeting major industrial needs. DNB (Departure from Nucleate Boiling) prediction in PWRs is one of the high priority needs, and this paper focuses on its anticipated improvement by means of a so-called 'Local Predictive Approach' using the NEPTUNE CFD code. We firstly present the ambitious 'Local Predictive Approach' anticipated for a better prediction of DNB, i.e. an approach that intends to result in CHF correlations based on relevant local parameters as provided by the CFD modeling. The associated requirements for the two-phase flow modeling are underlined as well as those for the good level of performance of the NEPTUNE CFD code; hence, the code validation strategy based on different experimental data base types (including separated effect and integral-type tests data) is depicted. Secondly, we present comparisons between low pressure adiabatic bubbly flow experimental data obtained on the DEDALE experiment and the associated numerical simulation results. This study anew shows the high potential of NEPTUNE CFD code, even if, with respect to the aforementioned DNB-related aim, there is still a need for some modeling improvements involving new validation data obtained in thermal-hydraulics conditions representative of PWR ones. Finally, we deal with one of these new experimental data needs

  19. The active titration method for measuring local hydroxyl radical concentration

    NASA Technical Reports Server (NTRS)

    Sprengnether, Michele; Prinn, Ronald G.

    1994-01-01

    We are developing a method for measuring ambient OH by monitoring its rate of reaction with a chemical species. Our technique involves the local, instantaneous release of a mixture of saturated cyclic hydrocarbons (titrants) and perfluorocarbons (dispersants). These species must not normally be present in ambient air above the part per trillion concentration. We then track the mixture downwind using a real-time portable ECD tracer instrument. We collect air samples in canisters every few minutes for roughly one hour. We then return to the laboratory and analyze our air samples to determine the ratios of the titrant to dispersant concentrations. The trends in these ratios give us the ambient OH concentration from the relation: dlnR/dt = -k(OH). A successful measurement of OH requires that the trends in these ratios be measureable. We must not perturb ambient OH concentrations. The titrant to dispersant ratio must be spatially invariant. Finally, heterogeneous reactions of our titrant and dispersant species must be negligible relative to the titrant reaction with OH. We have conducted laboratory studies of our ability to measure the titrant to dispersant ratios as a function of concentration down to the few part per trillion concentration. We have subsequently used these results in a gaussian puff model to estimate our expected uncertainty in a field measurement of OH. Our results indicate that under a range of atmospheric conditions we expect to be able to measure OH with a sensitivity of 3x10(exp 5) cm(exp -3). In our most optimistic scenarios, we obtain a sensitivity of 1x10(exp 5) cm(exp -3). These sensitivity values reflect our anticipated ability to measure the ratio trends. However, because we are also using a rate constant to obtain our (OH) from this ratio trend, our accuracy cannot be better than that of the rate constant, which we expect to be about 20 percent.

  20. The active titration method for measuring local hydroxyl radical concentration

    NASA Technical Reports Server (NTRS)

    Sprengnether, Michele; Prinn, Ronald G.

    1994-01-01

    We are developing a method for measuring ambient OH by monitoring its rate of reaction with a chemical species. Our technique involves the local, instantaneous release of a mixture of saturated cyclic hydrocarbons (titrants) and perfluorocarbons (dispersants). These species must not normally be present in ambient air above the part per trillion concentration. We then track the mixture downwind using a real-time portable ECD tracer instrument. We collect air samples in canisters every few minutes for roughly one hour. We then return to the laboratory and analyze our air samples to determine the ratios of the titrant to dispersant concentrations. The trends in these ratios give us the ambient OH concentration from the relation: dlnR/dt = -k(OH). A successful measurement of OH requires that the trends in these ratios be measureable. We must not perturb ambient OH concentrations. The titrant to dispersant ratio must be spatially invariant. Finally, heterogeneous reactions of our titrant and dispersant species must be negligible relative to the titrant reaction with OH. We have conducted laboratory studies of our ability to measure the titrant to dispersant ratios as a function of concentration down to the few part per trillion concentration. We have subsequently used these results in a gaussian puff model to estimate our expected uncertainty in a field measurement of OH. Our results indicate that under a range of atmospheric conditions we expect to be able to measure OH with a sensitivity of 3x10(exp 5) cm(exp -3). In our most optimistic scenarios, we obtain a sensitivity of 1x10(exp 5) cm(exp -3). These sensitivity values reflect our anticipated ability to measure the ratio trends. However, because we are also using a rate constant to obtain our (OH) from this ratio trend, our accuracy cannot be better than that of the rate constant, which we expect to be about 20 percent.

  1. Metal-insulator transition and local moment formation: A spin-density functional approach

    NASA Astrophysics Data System (ADS)

    Ghazali, A.; Leroux-Hugon, P.

    1980-01-01

    A more thorough description of the metal-insulator transition in correlated systems including local moment formation may be achieved through the spin-density functional method when compared to the Hubbard model. We have applied this method to doped semiconductors and found a transition between an insulating phase with local moments and a metallic one without moments.

  2. LocalAli: an evolutionary-based local alignment approach to identify functionally conserved modules in multiple networks.

    PubMed

    Hu, Jialu; Reinert, Knut

    2015-02-01

    Sequences and protein interaction data are of significance to understand the underlying molecular mechanism of organisms. Local network alignment is one of key systematic ways for predicting protein functions, identifying functional modules and understanding the phylogeny from these data. Most of currently existing tools, however, encounter their limitations, which are mainly concerned with scoring scheme, speed and scalability. Therefore, there are growing demands for sophisticated network evolution models and efficient local alignment algorithms. We developed a fast and scalable local network alignment tool called LocalAli for the identification of functionally conserved modules in multiple networks. In this algorithm, we firstly proposed a new framework to reconstruct the evolution history of conserved modules based on a maximum-parsimony evolutionary model. By relying on this model, LocalAli facilitates interpretation of resulting local alignments in terms of conserved modules, which have been evolved from a common ancestral module through a series of evolutionary events. A meta-heuristic method simulated annealing was used to search for the optimal or near-optimal inner nodes (i.e. ancestral modules) of the evolutionary tree. To evaluate the performance and the statistical significance, LocalAli were tested on 26 real datasets and 1040 randomly generated datasets. The results suggest that LocalAli outperforms all existing algorithms in terms of coverage, consistency and scalability, meanwhile retains a high precision in the identification of functionally coherent subnetworks. The source code and test datasets are freely available for download under the GNU GPL v3 license at https://code.google.com/p/localali/. jialu.hu@fu-berlin.de or knut.reinert@fu-berlin.de. Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. Kerfdr: a semi-parametric kernel-based approach to local false discovery rate estimation

    PubMed Central

    Guedj, Mickael; Robin, Stephane; Celisse, Alain; Nuel, Gregory

    2009-01-01

    Background The use of current high-throughput genetic, genomic and post-genomic data leads to the simultaneous evaluation of a large number of statistical hypothesis and, at the same time, to the multiple-testing problem. As an alternative to the too conservative Family-Wise Error-Rate (FWER), the False Discovery Rate (FDR) has appeared for the last ten years as more appropriate to handle this problem. However one drawback of FDR is related to a given rejection region for the considered statistics, attributing the same value to those that are close to the boundary and those that are not. As a result, the local FDR has been recently proposed to quantify the specific probability for a given null hypothesis to be true. Results In this context we present a semi-parametric approach based on kernel estimators which is applied to different high-throughput biological data such as patterns in DNA sequences, genes expression and genome-wide association studies. Conclusion The proposed method has the practical advantages, over existing approaches, to consider complex heterogeneities in the alternative hypothesis, to take into account prior information (from an expert judgment or previous studies) by allowing a semi-supervised mode, and to deal with truncated distributions such as those obtained in Monte-Carlo simulations. This method has been implemented and is available through the R package kerfdr via the CRAN or at . PMID:19291295

  4. Slant-hole collimator, dual mode sterotactic localization method

    DOEpatents

    Weisenberger, Andrew G.

    2002-01-01

    The use of a slant-hole collimator in the gamma camera of dual mode stereotactic localization apparatus allows the acquisition of a stereo pair of scintimammographic images without repositioning of the gamma camera between image acquisitions.

  5. A Self-Adaptive Model-Based Wi-Fi Indoor Localization Method

    PubMed Central

    Tuta, Jure; Juric, Matjaz B.

    2016-01-01

    This paper presents a novel method for indoor localization, developed with the main aim of making it useful for real-world deployments. Many indoor localization methods exist, yet they have several disadvantages in real-world deployments—some are static, which is not suitable for long-term usage; some require costly human recalibration procedures; and others require special hardware such as Wi-Fi anchors and transponders. Our method is self-calibrating and self-adaptive thus maintenance free and based on Wi-Fi only. We have employed two well-known propagation models—free space path loss and ITU models—which we have extended with additional parameters for better propagation simulation. Our self-calibrating procedure utilizes one propagation model to infer parameters of the space and the other to simulate the propagation of the signal without requiring any additional hardware beside Wi-Fi access points, which is suitable for real-world usage. Our method is also one of the few model-based Wi-Fi only self-adaptive approaches that do not require the mobile terminal to be in the access-point mode. The only input requirements of the method are Wi-Fi access point positions, and positions and properties of the walls. Our method has been evaluated in single- and multi-room environments, with measured mean error of 2–3 and 3–4 m, respectively, which is similar to existing methods. The evaluation has proven that usable localization accuracy can be achieved in real-world environments solely by the proposed Wi-Fi method that relies on simple hardware and software requirements. PMID:27929453

  6. A Self-Adaptive Model-Based Wi-Fi Indoor Localization Method.

    PubMed

    Tuta, Jure; Juric, Matjaz B

    2016-12-06

    This paper presents a novel method for indoor localization, developed with the main aim of making it useful for real-world deployments. Many indoor localization methods exist, yet they have several disadvantages in real-world deployments-some are static, which is not suitable for long-term usage; some require costly human recalibration procedures; and others require special hardware such as Wi-Fi anchors and transponders. Our method is self-calibrating and self-adaptive thus maintenance free and based on Wi-Fi only. We have employed two well-known propagation models-free space path loss and ITU models-which we have extended with additional parameters for better propagation simulation. Our self-calibrating procedure utilizes one propagation model to infer parameters of the space and the other to simulate the propagation of the signal without requiring any additional hardware beside Wi-Fi access points, which is suitable for real-world usage. Our method is also one of the few model-based Wi-Fi only self-adaptive approaches that do not require the mobile terminal to be in the access-point mode. The only input requirements of the method are Wi-Fi access point positions, and positions and properties of the walls. Our method has been evaluated in single- and multi-room environments, with measured mean error of 2-3 and 3-4 m, respectively, which is similar to existing methods. The evaluation has proven that usable localization accuracy can be achieved in real-world environments solely by the proposed Wi-Fi method that relies on simple hardware and software requirements.

  7. A method for localized computation of Pulse Wave Velocity in carotid structure.

    PubMed

    Patil, Ravindra B; Krishnamoorthy, P; Sethuraman, Shriram

    2015-01-01

    Pulse Wave Velocity (PWV) promises to be a useful clinical marker for noninvasive diagnosis of atherosclerosis. This work demonstrates the ability to perform localized carotid PWV measurements from the distention waveform derived from the Radio Frequency (RF) ultrasound signal using a carotid phantom setup. The proposed system consists of low cost custom-built ultrasound probe and algorithms for envelope detection, arterial wall identification, echo tracking, distension waveform computation and PWV estimation. The method is proposed on a phantom data acquired using custom-built prototype non-imaging probe. The proposed approach is non-image based and can be seamlessly integrated into existing clinical ultrasound scanners.

  8. An Observationally-Centred Method to Quantify the Changing Shape of Local Temperature Distributions

    NASA Astrophysics Data System (ADS)

    Chapman, S. C.; Stainforth, D. A.; Watkins, N. W.

    2014-12-01

    For climate sensitive decisions and adaptation planning, guidance on how local climate is changing is needed at the specific thresholds relevant to particular impacts or policy endeavours. This requires the quantification of how the distributions of variables, such as daily temperature, are changing at specific quantiles. These temperature distributions are non-normal and vary both geographically and in time. We present a method[1,2] for analysing local climatic time series data to assess which quantiles of the local climatic distribution show the greatest and most robust changes. We have demonstrated this approach using the E-OBS gridded dataset[3] which consists of time series of local daily temperature across Europe over the last 60 years. Our method extracts the changing cumulative distribution function over time and uses a simple mathematical deconstruction of how the difference between two observations from two different time periods can be assigned to the combination of natural statistical variability and/or the consequences of secular climate change. The change in temperature can be tracked at a temperature threshold, at a likelihood, or at a given return time, independently for each geographical location. Geographical correlations are thus an output of our method and reflect both climatic properties (local and synoptic), and spatial correlations inherent in the observation methodology. We find as an output many regionally consistent patterns of response of potential value in adaptation planning. For instance, in a band from Northern France to Denmark the hottest days in the summer temperature distribution have seen changes of at least 2°C over a 43 year period; over four times the global mean change over the same period. We discuss methods to quantify the robustness of these observed sensitivities and their statistical likelihood. This approach also quantifies the level of detail at which one might wish to see agreement between climate models and

  9. OCT-based approach to local relaxations discrimination from translational relaxation motions

    NASA Astrophysics Data System (ADS)

    Matveev, Lev A.; Matveyev, Alexandr L.; Gubarkova, Ekaterina V.; Gelikonov, Grigory V.; Sirotkina, Marina A.; Kiseleva, Elena B.; Gelikonov, Valentin M.; Gladkova, Natalia D.; Vitkin, Alex; Zaitsev, Vladimir Y.

    2016-04-01

    Multimodal optical coherence tomography (OCT) is an emerging tool for tissue state characterization. Optical coherence elastography (OCE) is an approach to mapping mechanical properties of tissue based on OCT. One of challenging problems in OCE is elimination of the influence of residual local tissue relaxation that complicates obtaining information on elastic properties of the tissue. Alternatively, parameters of local relaxation itself can be used as an additional informative characteristic for distinguishing the tissue in normal and pathological states over the OCT image area. Here we briefly present an OCT-based approach to evaluation of local relaxation processes in the tissue bulk after sudden unloading of its initial pre-compression. For extracting the local relaxation rate we evaluate temporal dependence of local strains that are mapped using our recently developed hybrid phase resolved/displacement-tracking (HPRDT) approach. This approach allows one to subtract the contribution of global displacements of scatterers in OCT scans and separate the temporal evolution of local strains. Using a sample excised from of a coronary arteria, we demonstrate that the observed relaxation of local strains can be reasonably fitted by an exponential law, which opens the possibility to characterize the tissue by a single relaxation time. The estimated local relaxation times are assumed to be related to local biologically-relevant processes inside the tissue, such as diffusion, leaking/draining of the fluids, local folding/unfolding of the fibers, etc. In general, studies of evolution of such features can provide new metrics for biologically-relevant changes in tissue, e.g., in the problems of treatment monitoring.

  10. LOCAL ORTHOGONAL CUTTING METHOD FOR COMPUTING MEDIAL CURVES AND ITS BIOMEDICAL APPLICATIONS

    PubMed Central

    Einstein, Daniel R.; Dyedov, Vladimir

    2010-01-01

    Medial curves have a wide range of applications in geometric modeling and analysis (such as shape matching) and biomedical engineering (such as morphometry and computer assisted surgery). The computation of medial curves poses significant challenges, both in terms of theoretical analysis and practical efficiency and reliability. In this paper, we propose a definition and analysis of medial curves and also describe an efficient and robust method called local orthogonal cutting (LOC) for computing medial curves. Our approach is based on three key concepts: a local orthogonal decomposition of objects into substructures, a differential geometry concept called the interior center of curvature (ICC), and integrated stability and consistency tests. These concepts lend themselves to robust numerical techniques and result in an algorithm that is efficient and noise resistant. We illustrate the effectiveness and robustness of our approach with some highly complex, large-scale, noisy biomedical geometries derived from medical images, including lung airways and blood vessels. We also present comparisons of our method with some existing methods. PMID:20628546

  11. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism.

    PubMed

    Nagesh, Jayashree; Frisch, Michael J; Brumer, Paul; Izmaylov, Artur F

    2016-12-28

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A. F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Becke's atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1- naphthyl)- methyl)- anthracene and 4-((2- naphthyl)- methyl)- benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that is not accessible using a simple density difference analysis.

  12. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism

    NASA Astrophysics Data System (ADS)

    Nagesh, Jayashree; Frisch, Michael J.; Brumer, Paul; Izmaylov, Artur F.

    2016-12-01

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A. F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Becke's atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1- naphthyl)- methyl)- anthracene and 4-((2- naphthyl)- methyl)- benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that is not accessible using a simple density difference analysis.

  13. DNA methods: critical review of innovative approaches.

    PubMed

    Kok, Esther J; Aarts, Henk J M; Van Hoef, A M Angeline; Kuiper, Harry A

    2002-01-01

    The presence of ingredients derived from genetically modified organisms (GMOs) in food products in the market place is subject to a number of European regulations that stipulate which product consisting of or containing GMO-derived ingredients should be labeled as such. In order to maintain these labeling requirements, a variety of different GMO detection methods have been developed to screen for either the presence of DNA or protein derived from (approved) GM varieties. Recent incidents where unapproved GM varieties entered the European market show that more powerful GMO detection and identification methods will be needed to maintain European labeling requirements in an adequate, efficient, and cost-effective way. This report discusses the current state-of-the-art as well as future developments in GMO detection.

  14. High-resolution MEG source imaging approach to accurately localize Broca's area in patients with brain tumor or epilepsy.

    PubMed

    Huang, Charles W; Huang, Ming-Xiong; Ji, Zhengwei; Swan, Ashley Robb; Angeles, Anne Marie; Song, Tao; Huang, Jeffrey W; Lee, Roland R

    2016-05-01

    Localizing expressive language function has been challenging using the conventional magnetoencephalography (MEG) source modeling methods. The present MEG study presents a new accurate and precise approach in localizing the language areas using a high-resolution MEG source imaging method. In 32 patients with brain tumors and/or epilepsies, an object-naming task was used to evoke MEG responses. Our Fast-VESTAL source imaging method was then applied to the MEG data in order to localize the brain areas evoked by the object-naming task. The Fast-VESTAL results showed that Broca's area was accurately localized to the pars opercularis (BA 44) and/or the pars triangularis (BA 45) in all patients. Fast-VESTAL also accurately localized Wernicke's area to the posterior aspect of the superior temporal gyri in BA 22, as well as several additional brain areas. Furthermore, we found that the latency of the main peak of the response in Wernicke's area was significantly earlier than that of Broca's area. In all patients, Fast-VESTAL analysis established accurate and precise localizations of Broca's area, as well as other language areas. The responses in Wernicke's area were also shown to significantly precede those of Broca's area. The present study demonstrates that using Fast-VESTAL, MEG can serve as an accurate and reliable functional imaging tool for presurgical mapping of language functions in patients with brain tumors and/or epilepsies. Published by Elsevier Ireland Ltd.

  15. A new method of automatic landmark tagging for shape model construction via local curvature scale

    NASA Astrophysics Data System (ADS)

    Rueda, Sylvia; Udupa, Jayaram K.; Bai, Li

    2008-03-01

    Segmentation of organs in medical images is a difficult task requiring very often the use of model-based approaches. To build the model, we need an annotated training set of shape examples with correspondences indicated among shapes. Manual positioning of landmarks is a tedious, time-consuming, and error prone task, and almost impossible in the 3D space. To overcome some of these drawbacks, we devised an automatic method based on the notion of c-scale, a new local scale concept. For each boundary element b, the arc length of the largest homogeneous curvature region connected to b is estimated as well as the orientation of the tangent at b. With this shape description method, we can automatically locate mathematical landmarks selected at different levels of detail. The method avoids the use of landmarks for the generation of the mean shape. The selection of landmarks on the mean shape is done automatically using the c-scale method. Then, these landmarks are propagated to each shape in the training set, defining this way the correspondences among the shapes. Altogether 12 strategies are described along these lines. The methods are evaluated on 40 MRI foot data sets, the object of interest being the talus bone. The results show that, for the same number of landmarks, the proposed methods are more compact than manual and equally spaced annotations. The approach is applicable to spaces of any dimensionality, although we have focused in this paper on 2D shapes.

  16. [Spiritual themes in mental pathology. Methodical approach].

    PubMed

    Marchais, P; Randrup, A

    1994-10-01

    The meaning of the themes with spiritual connotations poses complex problems for psychiatry, because these themes induce the observer to project his own convictions and frames of references on his investigations. A double detachment (objectivation) concerning both the object of study and the observer is implied. This makes it possible to study these phenomena by a more rigorous method, to investigate the conditions of their formation and to demonstrate objectifiable correlates (experienced space and time, the various levels of psychic experience, factors in the environment...). In consequence the appropriate medical behaviour can be more precisely delineated.

  17. A local pseudo arc-length method for hyperbolic conservation laws

    NASA Astrophysics Data System (ADS)

    Wang, Xing; Ma, Tian-Bao; Ren, Hui-Lan; Ning, Jian-Guo

    2014-12-01

    A local pseudo arc-length method (LPALM) for solving hyperbolic conservation laws is presented in this paper. The key idea of this method comes from the original arc-length method, through which the critical points are bypassed by transforming the computational space. The method is based on local changes of physical variables to choose the discontinuous stencil and introduce the pseudo arc-length parameter, and then transform the governing equations from physical space to arc-length space. In order to solve these equations in arc-length coordinate, it is necessary to combine the velocity of mesh points in the moving mesh method, and then convert the physical variable in arclength space back to physical space. Numerical examples have proved the effectiveness and generality of the new approach for linear equation, nonlinear equation and system of equations with discontinuous initial values. Non-oscillation solution can be obtained by adjusting the parameter and the mesh refinement number for problems containing both shock and rarefaction waves.

  18. A new approach for beam hardening correction based on the local spectrum distributions

    NASA Astrophysics Data System (ADS)

    Rasoulpour, Naser; Kamali-Asl, Alireza; Hemmati, Hamidreza

    2015-09-01

    Energy dependence of material absorption and polychromatic nature of x-ray beams in the Computed Tomography (CT) causes a phenomenon which called ;beam hardening;. The purpose of this study is to provide a novel approach for Beam Hardening (BH) correction. This approach is based on the linear attenuation coefficients of Local Spectrum Distributions (LSDs) in the various depths of a phantom. The proposed method includes two steps. Firstly, the hardened spectra in various depths of the phantom (or LSDs) are estimated based on the Expectation Maximization (EM) algorithm for arbitrary thickness interval of known materials in the phantom. The performance of LSD estimation technique is evaluated by applying random Gaussian noise to transmission data. Then, the linear attenuation coefficients with regarding to the mean energy of LSDs are obtained. Secondly, a correction function based on the calculated attenuation coefficients is derived in order to correct polychromatic raw data. Since a correction function has been used for the conversion of the polychromatic data to the monochromatic data, the effect of BH in proposed reconstruction must be reduced in comparison with polychromatic reconstruction. The proposed approach has been assessed in the phantoms which involve less than two materials, but the correction function has been extended for using in the constructed phantoms with more than two materials. The relative mean energy difference in the LSDs estimations based on the noise-free transmission data was less than 1.5%. Also, it shows an acceptable value when a random Gaussian noise is applied to the transmission data. The amount of cupping artifact in the proposed reconstruction method has been effectively reduced and proposed reconstruction profile is uniform more than polychromatic reconstruction profile.

  19. Communication: Improved pair approximations in local coupled-cluster methods

    NASA Astrophysics Data System (ADS)

    Schwilk, Max; Usvyat, Denis; Werner, Hans-Joachim

    2015-03-01

    In local coupled cluster treatments the electron pairs can be classified according to the magnitude of their energy contributions or distances into strong, close, weak, and distant pairs. Different approximations are introduced for the latter three classes. In this communication, an improved simplified treatment of close and weak pairs is proposed, which is based on long-range cancellations of individually slowly decaying contributions in the amplitude equations. Benchmark calculations for correlation, reaction, and activation energies demonstrate that these approximations work extremely well, while pair approximations based on local second-order Møller-Plesset theory can lead to errors that are 1-2 orders of magnitude larger.

  20. Improved variation calling via an iterative backbone remapping and local assembly method for bacterial genomes

    PubMed Central

    Tae, Hongseok; Settlage, Robert E.; Shallom, Shamira; Bavarva, Jasmin H.; Preston, Dale; Hawkins, Gregory N.; Adams, L. Garry; Garner, Harold R.

    2012-01-01

    Sequencing data analysis remains limiting and problematic, especially for low complexity repeat sequences and transposon elements due to inherent sequencing errors and short sequence read lengths. We have developed a program, ReviSeq, which uses a hybrid method comprised of iterative remapping and local assembly upon a bacterial sequence backbone. Application of this method to six Brucella suis field isolates compared to the newly revised Brucella suis 1330 reference genome identified on average 13, 15, 19 and 9 more variants per sample than STAMPY/SAMtools, BWA/SAMtools, iCORN and BWA/PINDEL pipelines, and excluded on average 4, 2, 3 and 19 variants per sample, respectively. In total, using this iterative approach, we identified on average 87 variants including SNVs, short INDELs and long INDELs per strain when compared to the reference. Our program outperforms other methods especially for long INDEL calling. The program is available at http://reviseq.sourceforge.net. PMID:22967795

  1. Analysis of the Heliospheric Current Sheet local inclination using three different methods: Preliminary results.

    NASA Astrophysics Data System (ADS)

    Blanco, Juan Jose; Hidalgo, Miguel Angel; Rodriguez-Pacheco, Javier; Medina, Jose

    There exist different methods for determining the Heliospheric Current Sheet (HCS) orientation. The most widely used is the well known Minimum Variance Analysis (MVA) based on the covariance matrix diagonalization and on the assumption that the minimum variance eigenvector marks the HCS plane normal. In a similar form, the Coplanarity Variance Analysis (CVA) is able to estimate the vector normal to a discontinuity plane but from the maximum variance eigenvector. A different approach to this problem is giving by the HYTARO method. It assumes a magnetic topology based on Harris field and fits in situ magnetometer measurements. Moreover, it is able to estimate not only the HCS local orientation but others HCS physical parameters. In this work, we compared these three methods when are applied to a set of HCS crossings along the solar minimum.

  2. Measuring Local Strain Rates In Ductile Shear Zones: A New Approach From Deformed Syntectonic Dykes

    NASA Astrophysics Data System (ADS)

    Sassier, C.; Leloup, P.; Rubatto, D.; Galland, O.; Yue, Y.; Ding, L.

    2006-12-01

    previous methods. From the less to the most deformed dykes, minimum γ values vary between 0.2 to ~10, respectively. Second, we determined the ages of emplacement of each dyke by ion microprobe U-Pb dating of monazites. We obtained three groups of ages at 22Ma, 24-26Ma and 30Ma. Our geochronological data are in good agreement with our structural data, the most deformed dykes being the oldest. The strain rates deduced from these measurements are on the order of 10^{-14}s-1, that is slower than values previously deduced from indirect methods. However, this value only corresponds to a minimum local strain rate. That new method developed to estimate local minimum strain rates in a major ductile shear zone seems to be reliable and could be applied to other shear zones. Such an approach applied at several locations along a single shear zone could also provide new opportunities to understand the evolution of a whole shear system.

  3. Local knowledge in community-based approaches to medicinal plant conservation: lessons from India.

    PubMed

    Shukla, Shailesh; Gardner, James

    2006-04-07

    Community-based approaches to conservation of natural resources, in particular medicinal plants, have attracted attention of governments, non governmental organizations and international funding agencies. This paper highlights the community-based approaches used by an Indian NGO, the Rural Communes Medicinal Plant Conservation Centre (RCMPCC). The RCMPCC recognized and legitimized the role of local medicinal knowledge along with other knowledge systems to a wider audience, i.e. higher levels of government. Besides a review of relevant literature, the research used a variety of qualitative techniques, such as semi-structured, in-depth interviews and participant observations in one of the project sites of RCMPCC. The review of local medicinal plant knowledge systems reveals that even though medicinal plants and associated knowledge systems (particularly local knowledge) are gaining wider recognition at the global level, the efforts to recognize and promote the un-codified folk systems of medicinal knowledge are still inadequate. In country like India, such neglect is evident through the lack of legal recognition and supporting policies. On the other hand, community-based approaches like local healers' workshops or village biologist programs implemented by RCMPCC are useful in combining both local (folk and codified) and formal systems of medicine. Despite the high reliance on the local medicinal knowledge systems for health needs in India, the formal policies and national support structures are inadequate for traditional systems of medicine and almost absent for folk medicine. On the other hand, NGOs like the RCMPCC have demonstrated that community-based and local approaches such as local healer's workshops and village biologist program can synergistically forge linkages between local knowledge with the formal sciences (in this case botany and ecology) and generate positive impacts at various levels.

  4. Approaches to Mixed Methods Dissemination and Implementation Research: Methods, Strengths, Caveats, and Opportunities

    PubMed Central

    Green, Carla A.; Duan, Naihua; Gibbons, Robert D.; Hoagwood, Kimberly E.; Palinkas, Lawrence A.; Wisdom, Jennifer P.

    2015-01-01

    Limited translation of research into practice has prompted study of diffusion and implementation, and development of effective methods of encouraging adoption, dissemination and implementation. Mixed methods techniques offer approaches for assessing and addressing processes affecting implementation of evidence-based interventions. We describe common mixed methods approaches used in dissemination and implementation research, discuss strengths and limitations of mixed methods approaches to data collection, and suggest promising methods not yet widely used in implementation research. We review qualitative, quantitative, and hybrid approaches to mixed methods dissemination and implementation studies, and describe methods for integrating multiple methods to increase depth of understanding while improving reliability and validity of findings. PMID:24722814

  5. Approaches to Mixed Methods Dissemination and Implementation Research: Methods, Strengths, Caveats, and Opportunities.

    PubMed

    Green, Carla A; Duan, Naihua; Gibbons, Robert D; Hoagwood, Kimberly E; Palinkas, Lawrence A; Wisdom, Jennifer P

    2015-09-01

    Limited translation of research into practice has prompted study of diffusion and implementation, and development of effective methods of encouraging adoption, dissemination and implementation. Mixed methods techniques offer approaches for assessing and addressing processes affecting implementation of evidence-based interventions. We describe common mixed methods approaches used in dissemination and implementation research, discuss strengths and limitations of mixed methods approaches to data collection, and suggest promising methods not yet widely used in implementation research. We review qualitative, quantitative, and hybrid approaches to mixed methods dissemination and implementation studies, and describe methods for integrating multiple methods to increase depth of understanding while improving reliability and validity of findings.

  6. Green technology approach towards herbal extraction method

    NASA Astrophysics Data System (ADS)

    Mutalib, Tengku Nur Atiqah Tengku Ab; Hamzah, Zainab; Hashim, Othman; Mat, Hishamudin Che

    2015-05-01

    The aim of present study was to compare maceration method of selected herbs using green and non-green solvents. Water and d-limonene are a type of green solvents while non-green solvents are chloroform and ethanol. The selected herbs were Clinacanthus nutans leaf and stem, Orthosiphon stamineus leaf and stem, Sesbania grandiflora leaf, Pluchea indica leaf, Morinda citrifolia leaf and Citrus hystrix leaf. The extracts were compared with the determination of total phenolic content. Total phenols were analyzed using a spectrophotometric technique, based on Follin-ciocalteau reagent. Gallic acid was used as standard compound and the total phenols were expressed as mg/g gallic acid equivalent (GAE). The most suitable and effective solvent is water which produced highest total phenol contents compared to other solvents. Among the selected herbs, Orthosiphon stamineus leaves contain high total phenols at 9.087mg/g.

  7. A Local DCT-II Feature Extraction Approach for Personal Identification Based on Palmprint

    NASA Astrophysics Data System (ADS)

    Choge, H. Kipsang; Oyama, Tadahiro; Karungaru, Stephen; Tsuge, Satoru; Fukumi, Minoru

    Biometric applications based on the palmprint have recently attracted increased attention from various researchers. In this paper, a method is presented that differs from the commonly used global statistical and structural techniques by extracting and using local features instead. The middle palm area is extracted after preprocessing for rotation, position and illumination normalization. The segmented region of interest is then divided into blocks of either 8×8 or 16×16 pixels in size. The type-II Discrete Cosine Transform (DCT) is applied to transform the blocks into DCT space. A subset of coefficients that encode the low to medium frequency components is selected using the JPEG-style zigzag scanning method. Features from each block are subsequently concatenated into a compact feature vector and used in palmprint verification experiments with palmprints from the PolyU Palmprint Database. Results indicate that this approach achieves better results than many conventional transform-based methods, with an excellent recognition accuracy above 99% and an Equal Error Rate (EER) of less than 1.2% in palmprint verification.

  8. General Approach to Quantum Channel Impossibility by Local Operations and Classical Communication.

    PubMed

    Cohen, Scott M

    2017-01-13

    We describe a general approach to proving the impossibility of implementing a quantum channel by local operations and classical communication (LOCC), even with an infinite number of rounds, and find that this can often be demonstrated by solving a set of linear equations. The method also allows one to design a LOCC protocol to implement the channel whenever such a protocol exists in any finite number of rounds. Perhaps surprisingly, the computational expense for analyzing LOCC channels is not much greater than that for LOCC measurements. We apply the method to several examples, two of which provide numerical evidence that the set of quantum channels that are not LOCC is not closed and that there exist channels that can be implemented by LOCC either in one round or in three rounds that are on the boundary of the set of all LOCC channels. Although every LOCC protocol must implement a separable quantum channel, it is a very difficult task to determine whether or not a given channel is separable. Fortunately, prior knowledge that the channel is separable is not required for application of our method.

  9. General Approach to Quantum Channel Impossibility by Local Operations and Classical Communication

    NASA Astrophysics Data System (ADS)

    Cohen, Scott M.

    2017-01-01

    We describe a general approach to proving the impossibility of implementing a quantum channel by local operations and classical communication (LOCC), even with an infinite number of rounds, and find that this can often be demonstrated by solving a set of linear equations. The method also allows one to design a LOCC protocol to implement the channel whenever such a protocol exists in any finite number of rounds. Perhaps surprisingly, the computational expense for analyzing LOCC channels is not much greater than that for LOCC measurements. We apply the method to several examples, two of which provide numerical evidence that the set of quantum channels that are not LOCC is not closed and that there exist channels that can be implemented by LOCC either in one round or in three rounds that are on the boundary of the set of all LOCC channels. Although every LOCC protocol must implement a separable quantum channel, it is a very difficult task to determine whether or not a given channel is separable. Fortunately, prior knowledge that the channel is separable is not required for application of our method.

  10. Modeling of fatigue crack induced nonlinear ultrasonics using a highly parallelized explicit local interaction simulation approach

    NASA Astrophysics Data System (ADS)

    Shen, Yanfeng; Cesnik, Carlos E. S.

    2016-04-01

    This paper presents a parallelized modeling technique for the efficient simulation of nonlinear ultrasonics introduced by the wave interaction with fatigue cracks. The elastodynamic wave equations with contact effects are formulated using an explicit Local Interaction Simulation Approach (LISA). The LISA formulation is extended to capture the contact-impact phenomena during the wave damage interaction based on the penalty method. A Coulomb friction model is integrated into the computation procedure to capture the stick-slip contact shear motion. The LISA procedure is coded using the Compute Unified Device Architecture (CUDA), which enables the highly parallelized supercomputing on powerful graphic cards. Both the explicit contact formulation and the parallel feature facilitates LISA's superb computational efficiency over the conventional finite element method (FEM). The theoretical formulations based on the penalty method is introduced and a guideline for the proper choice of the contact stiffness is given. The convergence behavior of the solution under various contact stiffness values is examined. A numerical benchmark problem is used to investigate the new LISA formulation and results are compared with a conventional contact finite element solution. Various nonlinear ultrasonic phenomena are successfully captured using this contact LISA formulation, including the generation of nonlinear higher harmonic responses. Nonlinear mode conversion of guided waves at fatigue cracks is also studied.

  11. First-principles modeling of localized d states with the GW@LDA+U approach

    NASA Astrophysics Data System (ADS)

    Jiang, Hong; Gomez-Abal, Ricardo I.; Rinke, Patrick; Scheffler, Matthias

    2010-07-01

    First-principles modeling of systems with localized d states is currently a great challenge in condensed-matter physics. Density-functional theory in the standard local-density approximation (LDA) proves to be problematic. This can be partly overcome by including local Hubbard U corrections (LDA+U) but itinerant states are still treated on the LDA level. Many-body perturbation theory in the GW approach offers both a quasiparticle perspective (appropriate for itinerant states) and an exact treatment of exchange (appropriate for localized states), and is therefore promising for these systems. LDA+U has previously been viewed as an approximate GW scheme. We present here a derivation that is simpler and more general, starting from the static Coulomb-hole and screened exchange approximation to the GW self-energy. Following our previous work for f -electron systems [H. Jiang, R. I. Gomez-Abal, P. Rinke, and M. Scheffler, Phys. Rev. Lett. 102, 126403 (2009)10.1103/PhysRevLett.102.126403] we conduct a systematic investigation of the GW method based on LDA+U(GW@LDA+U) , as implemented in our recently developed all-electron GW code FHI-gap (Green’s function with augmented plane waves) for a series of prototypical d -electron systems: (1) ScN with empty d states, (2) ZnS with semicore d states, and (3) late transition-metal oxides (MnO, FeO, CoO, and NiO) with partially occupied d states. We show that for ZnS and ScN, the GW band gaps only weakly depend on U but for the other transition-metal oxides the dependence on U is as strong as in LDA+U . These different trends can be understood in terms of changes in the hybridization and screening. Our work demonstrates that GW@LDA+U with “physical” values of U provides a balanced and accurate description of both localized and itinerant states.

  12. Communication: Multipole approximations of distant pair energies in local correlation methods with pair natural orbitals

    NASA Astrophysics Data System (ADS)

    Werner, Hans-Joachim

    2016-11-01

    The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.

  13. Communication: Multipole approximations of distant pair energies in local correlation methods with pair natural orbitals.

    PubMed

    Werner, Hans-Joachim

    2016-11-28

    The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.

  14. Local generalised method of moments: an application to point process-based rainfall models.

    PubMed

    Kaczmarska, Jo M; Isham, Valerie S; Northrop, Paul

    2015-06-01

    Long series of simulated rainfall are required at point locations for a range of applications, including hydrological studies. Clustered point process-based rainfall models have been used for generating such simulations for many decades. These models suffer from a major limitation, however: their stationarity. Although seasonality can be allowed by fitting separate models for each calendar month or season, the models are unsuitable in their basic form for climate impact studies. In this paper, we develop new methodology to address this limitation. We extend the current fitting approach by allowing the discrete covariate, calendar month, to be replaced or supplemented with continuous covariates that are more directly related to the incidence and nature of rainfall. The covariate-dependent model parameters are estimated for each time interval using a kernel-based nonparametric approach within a generalised method-of-moments framework. An empirical study demonstrates the new methodology using a time series of 5-min rainfall data. The study considers both local mean and local linear approaches. While asymptotic results are included, the focus is on developing useable methodology for a complex model that can only be solved numerically. Issues including the choice of weighting matrix, estimation of parameter uncertainty and bandwidth and model selection are considered from this perspective. © 2015 The Authors. Environmetrics Published by John Wiley & Sons Ltd.

  15. Locally conservative groundwater flow in the continuous Galerkin method using 3-D prismatic patches

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Zhao, Yingwang; Lin, Yu-Feng F.; Xu, Hua

    2016-11-01

    A new procedure has been developed to improve the velocity field computed by the continuous Galerkin finite element method (CG). It enables extending the postprocessing algorithm proposed by Cordes and Kinzelbach (1992) to three-dimensional (3-D) models by using prismatic patches for saturated groundwater flow. This approach leverages a dual mesh to preserve local mass conservation and provides interpolated velocities based on consistent fluxes. To develop this 3-D approach, a triangular conservative patch is introduced by computing not only advection fluxes, but also vertical infiltrations, storage changes, and other sink or source terms. This triangular patch is then used to develop a prismatic patch, which consists of subprisms in two layers. By dividing a single two-layer patch into two separate one-layer patches, two dimensional (2-D) algorithms can be applied to compute velocities. As a consequence, each subelement is able to preserve local mass conservation. A hypothetical 3-D model is used to evaluate the precision of streamlines and flow rates generated by this approach and the FEFLOW simulation program.

  16. Antimicrobial stewardship in the Federal Bureau of Prisons: Approaches from the national and local levels.

    PubMed

    Long, Michael J; LaPlant, Brian N; McCormick, Justin C

    To determine the impact of national and local antimicrobial stewardship measures on overall antibiotic prescribing in the Federal Bureau of Prisons (BOP). Care was delivered to more than 160,000 inmates in 122 BOP facilities in the United States and Puerto Rico. Medical centers and health services clinics staffed by in-house medical staff, consultants, and specialists. Staffs include a variety of disciplines, including physicians, pharmacists, dentists, nurses, infection control personnel, therapists, health services administrators, and institution executive staff. Innovations occurred on 2 levels: local components were used to reinforce national initiatives. Local institutions used a multidisciplinary team approach including education and focused evaluations of all antibiotic prescriptions before dispensing. National initiatives included the development of a closed formulary, clinical practice guidelines, an antimicrobial stewardship group led by pharmacy, development of tools and strategies for institutions, inclusion in the BOP strategic plan, and a drug utilization evaluation. This was a study of antimicrobial stewardship within BOP and the resultant impact on antibiotic prescriptions. In addition, one institution's antimicrobial stewardship methods were reviewed to determine the impact on antibiotic prescribing practices. The total number of antibiotic prescriptions in BOP-managed institutions in fiscal year (FY) 2010 (October 2009 to September 2010) was 142,907 and progressively decreased to 105,832 in FY2015. The number of antibiotic prescriptions per 1000 inmates correspondingly decreased from 829 in FY2010 to 625 in FY2015. The overall number of antibiotic prescriptions as a percentage of total prescriptions decreased from 7.64% in FY2010 to 5.84% in FY2015. A robust multidisciplinary antimicrobial stewardship program has likely contributed to a decrease in both the total number and the rate of antibiotic prescriptions on a per-1000-patient basis in BOP

  17. Groundwater abstraction management in Sana'a Basin, Yemen: a local community approach

    NASA Astrophysics Data System (ADS)

    Taher, Taha M.

    2016-09-01

    Overexploitation of groundwater resources in Sana'a Basin, Yemen, is causing severe water shortages associated water quality degradation. Groundwater abstraction is five times higher than natural recharge and the water-level decline is about 4-8 m/year. About 90 % of the groundwater resource is used for agricultural activities. The situation is further aggravated by the absence of a proper water-management approach for the Basin. Water scarcity in the Wadi As-Ssirr catchment, the study area, is the most severe and this area has the highest well density (average 6.8 wells/km2) compared with other wadi catchments. A local scheme of groundwater abstraction redistribution is proposed, involving the retirement of a substantial number of wells. The scheme encourages participation of the local community via collective actions to reduce the groundwater overexploitation, and ultimately leads to a locally acceptable, manageable groundwater abstraction pattern. The proposed method suggests using 587 wells rather than 1,359, thus reducing the well density to 2.9 wells/km2. Three scenarios are suggested, involving different reductions to the well yields and/or the number of pumping hours for both dry and wet seasons. The third scenario is selected as a first trial for the communities to action; the resulting predicted reduction, by 2,371,999 m3, is about 6 % of the estimated annual demand. Initially, the groundwater abstraction volume should not be changed significantly until there are protective measures in place, such as improved irrigation efficiency, with the aim of increasing the income of farmers and reducing water use.

  18. Block-localized wavefunction (BLW) method at the density functional theory (DFT) level.

    PubMed

    Mo, Yirong; Song, Lingchun; Lin, Yuchun

    2007-08-30

    The block-localized wavefunction (BLW) approach is an ab initio valence bond (VB) method incorporating the efficiency of molecular orbital (MO) theory. It can generate the wavefunction for a resonance structure or diabatic state self-consistently by partitioning the overall electrons and primitive orbitals into several subgroups and expanding each block-localized molecular orbital in only one subspace. Although block-localized molecular orbitals in the same subspace are constrained to be orthogonal (a feature of MO theory), orbitals between different subspaces are generally nonorthogonal (a feature of VB theory). The BLW method is particularly useful in the quantification of the electron delocalization (resonance) effect within a molecule and the charge-transfer effect between molecules. In this paper, we extend the BLW method to the density functional theory (DFT) level and implement the BLW-DFT method to the quantum mechanical software GAMESS. Test applications to the pi conjugation in the planar allyl radical and ions with the basis sets of 6-31G(d), 6-31+G(d), 6-311+G(d,p), and cc-pVTZ show that the basis set dependency is insignificant. In addition, the BLW-DFT method can also be used to elucidate the nature of intermolecular interactions. Examples of pi-cation interactions and solute-solvent interactions will be presented and discussed. By expressing each diabatic state with one BLW, the BLW method can be further used to study chemical reactions and electron-transfer processes whose potential energy surfaces are typically described by two or more diabatic states.

  19. Combining local scaling and global methods to detect soil pore space

    NASA Astrophysics Data System (ADS)

    Martin-Sotoca, Juan Jose; Saa-Requejo, Antonio; Grau, Juan B.; Tarquis, Ana M.

    2017-04-01

    The characterization of the spatial distribution of soil pore structures is essential to obtain different parameters that will influence in several models related to water flow and/or microbial growth processes. The first step in pore structure characterization is obtaining soil images that best approximate reality. Over the last decade, major technological advances in X-ray computed tomography (CT) have allowed for the investigation and reconstruction of natural porous media architectures at very fine scales. The subsequent step is delimiting the pore structure (pore space) from the CT soil images applying a thresholding. Many times we could find CT-scan images that show low contrast at the solid-void interface that difficult this step. Different delimitation methods can result in different spatial distributions of pores influencing the parameters used in the models. Recently, new local segmentation method using local greyscale value (GV) concentration variabilities, based on fractal concepts, has been presented. This method creates singularity maps to measure the GV concentration at each point. The C-A method was combined with the singularity map approach (Singularity-CA method) to define local thresholds that can be applied to binarize CT images. Comparing this method with classical methods, such as Otsu and Maximum Entropy, we observed that more pores can be detected mainly due to its ability to amplify anomalous concentrations. However, it delineated many small pores that were incorrect. In this work, we present an improve version of Singularity-CA method that avoid this problem basically combining it with the global classical methods. References Martín-Sotoca, J.J., A. Saa-Requejo, J.B. Grau, A.M. Tarquis. New segmentation method based on fractal properties using singularity maps. Geoderma, 287, 40-53, 2017. Martín-Sotoca, J.J, A. Saa-Requejo, J.B. Grau, A.M. Tarquis. Local 3D segmentation of soil pore space based on fractal properties using singularity

  20. Use of the Support Group Method to Tackle Bullying, and Evaluation from Schools and Local Authorities in England

    ERIC Educational Resources Information Center

    Smith, Peter K.; Howard, Sharon; Thompson, Fran

    2007-01-01

    The Support Group Method (SGM), formerly the No Blame Approach, is widely used as an anti-bullying intervention in schools, but has aroused some controversy. There is little evidence from users regarding its effectiveness. We aimed to ascertain the use of and support for the SGM in Local Authorities (LAs) and schools; and obtain ratings of…

  1. An ESPRIT-Based Approach for 2-D Localization of Incoherently Distributed Sources in Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Hu, Anzhong; Lv, Tiejun; Gao, Hui; Zhang, Zhang; Yang, Shaoshi

    2014-10-01

    In this paper, an approach of estimating signal parameters via rotational invariance technique (ESPRIT) is proposed for two-dimensional (2-D) localization of incoherently distributed (ID) sources in large-scale/massive multiple-input multiple-output (MIMO) systems. The traditional ESPRIT-based methods are valid only for one-dimensional (1-D) localization of the ID sources. By contrast, in the proposed approach the signal subspace is constructed for estimating the nominal azimuth and elevation direction-of-arrivals and the angular spreads. The proposed estimator enjoys closed-form expressions and hence it bypasses the searching over the entire feasible field. Therefore, it imposes significantly lower computational complexity than the conventional 2-D estimation approaches. Our analysis shows that the estimation performance of the proposed approach improves when the large-scale/massive MIMO systems are employed. The approximate Cram\\'{e}r-Rao bound of the proposed estimator for the 2-D localization is also derived. Numerical results demonstrate that albeit the proposed estimation method is comparable with the traditional 2-D estimators in terms of performance, it benefits from a remarkably lower computational complexity.

  2. Guided wave interaction with hole damage using the local interaction simulation approach

    NASA Astrophysics Data System (ADS)

    Obenchain, Matthew B.; Cesnik, Carlos E. S.

    2014-12-01

    This paper considers the effects of hole damage on guided wave propagation in isotropic and composite plates using both the local interaction simulation approach (LISA) and experimental methods. Guided wave generation from piezoceramic wafers is modeled using the recently developed LISA hybrid approach. First, holes in isotropic plates are simulated to establish LISA's ability to capture the guided wave scattering effects of various hole sizes. Experimental results are compared with the simulations to aid in evaluating the LISA model. Next, hole damage in cross-ply composite laminates is modeled and compared with experimental results. Various hole sizes and azimuthal locations are simulated to determine the effects of varying those parameters. Results from both the isotropic and composite damage studies clearly display the ability of LISA to model hole damage. Both the simulation and experimental results illustrate the advantages and disadvantages of various sensor locations relative to the actuator and damage locations. Finally, the study shows the ability of the LISA model to capture mode conversions resulting from partial thickness holes.

  3. Semantic and Communicative Translation: Two Approaches, One Method.

    ERIC Educational Resources Information Center

    Viaggio, Sergio

    In a sequel to a review of the translation theory of Peter Newmark, it is argued that there is a single best method of translating regardless of whether the translator takes a semantic, communicative, or other approach. Methods of translating and approaches to extracting the sense of the text are clearly distinguished. Newmark is criticized for…

  4. Finding fossils in new ways: an artificial neural network approach to predicting the location of productive fossil localities.

    PubMed

    Anemone, Robert; Emerson, Charles; Conroy, Glenn

    2011-01-01

    Chance and serendipity have long played a role in the location of productive fossil localities by vertebrate paleontologists and paleoanthropologists. We offer an alternative approach, informed by methods borrowed from the geographic information sciences and using recent advances in computer science, to more efficiently predict where fossil localities might be found. Our model uses an artificial neural network (ANN) that is trained to recognize the spectral characteristics of known productive localities and other land cover classes, such as forest, wetlands, and scrubland, within a study area based on the analysis of remotely sensed (RS) imagery. Using these spectral signatures, the model then classifies other pixels throughout the study area. The results of the neural network classification can be examined and further manipulated within a geographic information systems (GIS) software package. While we have developed and tested this model on fossil mammal localities in deposits of Paleocene and Eocene age in the Great Divide Basin of southwestern Wyoming, a similar analytical approach can be easily applied to fossil-bearing sedimentary deposits of any age in any part of the world. We suggest that new analytical tools and methods of the geographic sciences, including remote sensing and geographic information systems, are poised to greatly enrich paleoanthropological investigations, and that these new methods should be embraced by field workers in the search for, and geospatial analysis of, fossil primates and hominins. Copyright © 2011 Wiley-Liss, Inc.

  5. Reduced conductivity dependence method for increase of dipole localization accuracy in the EEG inverse problem.

    PubMed

    Yitembe, Bertrand Russel; Crevecoeur, Guillaume; Van Keer, Roger; Dupre, Luc

    2011-05-01

    The EEG is a neurological diagnostic tool with high temporal resolution. However, when solving the EEG inverse problem, its localization accuracy is limited because of noise in measurements and available uncertainties of the conductivity value in the forward model evaluations. This paper proposes the reduced conductivity dependence (RCD) method for decreasing the localization error in EEG source analysis by limiting the propagation of the uncertain conductivity values to the solutions of the inverse problem. We redefine the traditional EEG cost function, and in contrast to previous approaches, we introduce a selection procedure of the EEG potentials. The selected potentials are, as low as possible, affected by the uncertainties of the conductivity when solving the inverse problem. We validate the methodology on the widely used three-shell spherical head model with a single electrical dipole and multiple dipoles as source model. The proposed RCD method enhances the source localization accuracy with a factor ranging between 2 and 4, dependent on the dipole location and the noise in measurements. © 2011 IEEE

  6. A quasi-local method for instantaneous frequency estimation with application to structural magnetic resonance images.

    PubMed

    Ulloa, Alvaro; Rodriguez, Paul; Liu, Jingyu; Calhoun, Vince; Pattichis, Marios

    2014-01-01

    Spatially-varying signal content can be effectively modeled using amplitude modulation-frequency modulation (AM-FM) representations. The AM-FM representation allow us to extract instantaneous amplitude (IA) and instantaneous frequency (IF) components that can be used to measure non-stationary content in biomedical images and videos. This paper introduces a new method for estimating the IA and the IF based on a quasi-local method (QLM). We provide an extensive comparison of AM-FM demodulation approaches based on QLM and a quasi-eigenfunction approximation method using three different filter-banks: (i) a separable, equiripple design, (ii) a Gabor filter bank, and (iii) a directional filter bank approach based on the Contourlet transform. The results document that the use of the new QLM method with an equiripple filter bank design gave the best IF magnitude estimates for a synthetic image. The new QLM method is then applied to a multi-site schizophrenia dataset (N=307). The dataset included structure magnetic resonance images from healthy controls and patients diagnosed with schizophrenia. The IF magnitude is shown to be less sensitive to variations across sites as opposed to the standard use of SMRI images that suffered from significant dependency on the scanner configurations on different collection sites. Furthermore, the regions of interest identified through the use of the IF magnitude are in agreement with previous studies.

  7. Correlation between variability of hand-outlined segmentation drawn by experts and local features of underlying image: a neuronal approach

    NASA Astrophysics Data System (ADS)

    Brahmi, Djamel; Cassoux, Nathalie; Serruys, Camille; Giron, Alain; Lehoang, Phuc; Fertil, Bernard

    1999-03-01

    Detection of contours in biomedical imags is quite often an a priori step to quantification. Using computer facilities, it is now straightforward for a medical expert to draw boundaries around regions of interest. However, accuracy of drawing is an issue, which is rarely addressed although it may be a crucial point when for example one looks for local evolution of boundaries on a series of images. The aim of our study is to correlate the local accuracy of experts' outlines with local features of the underlying image to allow meaningful comparisons of boundaries. Local variability of experts' outlines has been characterized by deriving a set of distances between outlines repeatedly drawn on the same image. Local features of underlying images were extracted from 64 by 64 pixel windows. We have used a two-stage neural network approach in order to deal with complexity of data within windows and to correlate their features with local variability of outlines. Our method has been applied to the quantification of the progression of the Cytomegalovirus infection as observed from a series of retinal angiograms in patients with AIDS. Reconstruction of new windows from the set of primitives obtained from the GHA network shows that the method preserves desired features. Accuracy of the border of infection is properly predicted and allows to generate confidence envelope around every hand-outlined.

  8. Bridging multi-scale approach to consider the effects of local deformations in the analysis of thin-walled members

    NASA Astrophysics Data System (ADS)

    Erkmen, R. Emre

    2013-07-01

    Thin-walled members that have one dimension relatively large in comparison to the cross-sectional dimensions are usually modelled by using beam-type one-dimensional finite elements. Beam-type elements, however, are based on the assumption of rigid cross-section, thus they only allow considerations associated with the beam axis behaviour such as flexural-, torsional- or lateral-buckling and cannot consider the effects of local deformations such as flange local buckling or distortional buckling. In order to capture the local effects of this type shell-type finite element models can be used. Based on the Bridging multi-scale approach, this study proposes a numerical technique that is able to split the global analysis, which is performed by using simple beam-type elements, from the local analysis which is based on more sophisticated shell-type elements. As a result, the proposed multi-scale method allows the usage of shell elements in a local region to incorporate the local deformation effects on the overall behaviour of thin-walled members without necessitating a shell-type model for the whole member. Comparisons with full shell-type analysis are provided in order to illustrate the efficiency of the method developed herein.

  9. The role of local observations as evidence to inform effective mitigation methods for flood risk management

    NASA Astrophysics Data System (ADS)

    Quinn, Paul; ODonnell, Greg; Owen, Gareth

    2014-05-01

    This poster presents a case study that highlights two crucial aspects of a catchment-based flood management project that were used to encourage uptake of an effective flood management strategy. Specifically, (1) the role of detailed local scale observations and (2) a modelling method informed by these observations. Within a 6km2 study catchment, Belford UK, a number of Runoff Attenuation Features (RAFs) have been constructed (including ponds, wetlands and woody debris structures) to address flooding issues in the downstream village. The storage capacity of the RAFs is typically small (200 to 500m3), hence there was skepticism as to whether they would work during large flood events. Monitoring was performed using a dense network of water level recorders installed both within the RAFs and within the stream network. Using adjacent upstream and downstream water levels in the stream network and observations within the actual ponds, a detailed understanding of the local performance of the RAFs was gained. However, despite understanding the local impacts of the features, the impact on the downstream hydrograph at the catchment scale could still not be ascertained with any certainty. The local observations revealed that the RAFs typically filled on the rising limb of the hydrograph; hence there was no available storage at the time of arrival of a large flow peak. However, it was also clear that an impact on the rising limb of the hydrograph was being observed. This knowledge of the functioning of individual features was used to create a catchment model, in which a network of RAFs could then be configured to examine the aggregated impacts. This Pond Network Model (PNM) was based on the observed local physical relationships and allowed a user specified sequence of ponds to be configured into a cascade structure. It was found that there was a minimum number of RAFs needed before an impact on peak flow was achieved for a large flood event. The number of RAFs required in the

  10. Iterative normalization method for improved prostate cancer localization with multispectral magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Samil Yetik, Imam

    2012-04-01

    Use of multispectral magnetic resonance imaging has received a great interest for prostate cancer localization in research and clinical studies. Manual extraction of prostate tumors from multispectral magnetic resonance imaging is inefficient and subjective, while automated segmentation is objective and reproducible. For supervised, automated segmentation approaches, learning is essential to obtain the information from training dataset. However, in this procedure, all patients are assumed to have similar properties for the tumor and normal tissues, and the segmentation performance suffers since the variations across patients are ignored. To conquer this difficulty, we propose a new iterative normalization method based on relative intensity values of tumor and normal tissues to normalize multispectral magnetic resonance images and improve segmentation performance. The idea of relative intensity mimics the manual segmentation performed by human readers, who compare the contrast between regions without knowing the actual intensity values. We compare the segmentation performance of the proposed method with that of z-score normalization followed by support vector machine, local active contours, and fuzzy Markov random field. Our experimental results demonstrate that our method outperforms the three other state-of-the-art algorithms, and was found to have specificity of 0.73, sensitivity of 0.69, and accuracy of 0.79, significantly better than alternative methods.

  11. SuBSENSE: a universal change detection method with local adaptive sensitivity.

    PubMed

    St-Charles, Pierre-Luc; Bilodeau, Guillaume-Alexandre; Bergevin, Robert

    2015-01-01

    Foreground/background segmentation via change detection in video sequences is often used as a stepping stone in high-level analytics and applications. Despite the wide variety of methods that have been proposed for this problem, none has been able to fully address the complex nature of dynamic scenes in real surveillance tasks. In this paper, we present a universal pixel-level segmentation method that relies on spatiotemporal binary features as well as color information to detect changes. This allows camouflaged foreground objects to be detected more easily while most illumination variations are ignored. Besides, instead of using manually set, frame-wide constants to dictate model sensitivity and adaptation speed, we use pixel-level feedback loops to dynamically adjust our method's internal parameters without user intervention. These adjustments are based on the continuous monitoring of model fidelity and local segmentation noise levels. This new approach enables us to outperform all 32 previously tested state-of-the-art methods on the 2012 and 2014 versions of the ChangeDetection.net dataset in terms of overall F-Measure. The use of local binary image descriptors for pixel-level modeling also facilitates high-speed parallel implementations: our own version, which used no low-level or architecture-specific instruction, reached real-time processing speed on a midlevel desktop CPU. A complete C++ implementation based on OpenCV is available online.

  12. A novel local-phase method of automatic atlas construction in fetal ultrasound

    NASA Astrophysics Data System (ADS)

    Fathima, Sana; Rueda, Sylvia; Papageorghiou, Aris; Noble, J. Alison

    2011-03-01

    In recent years, fetal diagnostics have relied heavily on clinical assessment and biometric analysis of manually acquired ultrasound images. There is a profound need for automated and standardized evaluation tools to characterize fetal growth and development. This work addresses this need through the novel use of feature-based techniques to develop evaluators of fetal brain gestation. The methodology is comprised of an automated database-driven 2D/3D image atlas construction method, which includes several iterative processes. A unique database was designed to store fetal image data acquired as part of the Intergrowth-21st study. This database drives the proposed automated atlas construction methodology using local phase information to perform affine registration with normalized mutual information as the similarity parameter, followed by wavelet-based image fusion and averaging. The unique feature-based application of local phase and wavelet fusion towards creating the atlas reduces the intensity dependence and difficulties in registering ultrasound images. The method is evaluated on fetal transthalamic head ultrasound images of 20 weeks gestation. The results show that the proposed method is more robust to intensity variations than standard intensity-based methods. Results also suggest that the feature-based approach improves the registration accuracy needed in creating a clinically valid ultrasound image atlas.

  13. DYNAMO: concurrent dynamic multi-model source localization method for EEG and/or MEG.

    PubMed

    Antelis, Javier M; Minguez, Javier

    2013-01-15

    This work presents a new dipolar method to estimate the neural sources from separate or combined EEG and MEG data. The novelty lies in the simultaneous estimation and integration of neural sources from different dynamic models with different parameters, leading to a dynamic multi-model solution for the EEG/MEG source localization problem. The first key aspect of this method is defining the source model as a dipolar dynamic system, which allows for the estimation of the probability distribution of the sources within the Bayesian filter estimation framework. A second important aspect is the consideration of several banks of filters that simultaneously estimate and integrate the neural sources of different models. A third relevant aspect is that the final probability estimate is a result of the probabilistic integration of the neural sources of numerous models. Such characteristics lead to a new approach that does not require a prior definition neither of the number of sources or of the underlying temporal dynamics, allowing for the specification of multiple initial prior estimates. The method was validated by three sensor modalities with simulated data designed to impose difficult estimation situations, and with real EEG data recorded in a feedback error-related potential paradigm. On the basis of these evaluations, the method was able to localize the sources with high accuracy. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Damage localization in a residential-sized wind turbine blade by use of the SDDLV method

    NASA Astrophysics Data System (ADS)

    Johansen, R. J.; Hansen, L. M.; Ulriksen, M. D.; Tcherniak, D.; Damkilde, L.

    2015-07-01

    The stochastic dynamic damage location vector (SDDLV) method has previously proved to facilitate effective damage localization in truss- and plate-like structures. The method is based on interrogating damage-induced changes in transfer function matrices in cases where these matrices cannot be derived explicitly due to unknown input. Instead, vectors from the kernel of the transfer function matrix change are utilized; vectors which are derived on the basis of the system and state-to-output mapping matrices from output-only state-space realizations. The idea is then to convert the kernel vectors associated with the lowest singular values into static pseudo-loads and apply these alternately to an undamaged reference model with known stiffness matrix. By doing so, the stresses in the potentially damaged elements will, theoretically, approach zero. The present paper demonstrates an application of the SDDLV method for localization of structural damages in a cantilevered residential-sized wind turbine blade. The blade was excited by an unmeasured multi-impulse load and the resulting dynamic response was captured through accelerometers mounted along the blade. The static pseudo-loads were applied to a finite element (FE) blade model, which was tuned against the modal parameters of the actual blade. In the experiments, an undamaged blade configuration was analysed along with different damage scenarios, hereby testing the applicability of the SDDLV method.

  15. Testing the local spacetime dynamics by heliospheric radiocommunication methods

    NASA Astrophysics Data System (ADS)

    Fahr, H.-J.; Siewert, M.

    2008-05-01

    According to general relativistic theories, cosmological spacetime is dynamic. This prediction is in excellent agreement with the huge majority of astronomical observations on large cosmic scales, especially the observations of cosmological redshifts of distant galaxies. However, on scales of heliospheric distances, verifications of general relativistic effects are based on Schwarzschild metric tests or kinetical corrections, such as the perihelion motion of Mercury, photon deflection at the Sun and gravitational photon redshifts in central gravity fields. As we will show in this paper, there is, however, a chance to detect new cosmologically relevant features on heliospheric scales by careful study of photon propagations in the local spacetime metrics, based on red- or blueshifts as a clear, but up to now overlooked, signature of the local spacetime dynamics. Thus, we propose the challenging possibility of carrying out experiments of cosmological relevance by simply using high-precision radio tracking of heliospheric spaceprobes, as already practised in cases like Pioneer-10/11, Galileo and Ulysses.

  16. Locally Conservative, Stabilized Finite Element Methods for Variably Saturated Flow

    DTIC Science & Technology

    2007-11-06

    mixed methods for Richards’ equation. The effectiveness of the multiscale stabilization strategy varied somewhat. For a steady-state, variably...Arbogast, Z. Chen, On the implementation of mixed methods as non- conforming methods for second order elliptic problems, Mathematics of Computation 64...211) (1995) 943–972. [53] Z. Chen, Equivalence between and multigrid algorithms for nonconform- ing and mixed methods for second order elliptic

  17. Insight-Based Approach for the Design of Integrated Local Food-Energy-Water Systems.

    PubMed

    Leung Pah Hang, Melissa Yuling; Martinez-Hernandez, Elias; Leach, Matthew; Yang, Aidong

    2017-08-01

    Society currently relies heavily on centralized production and large scale distribution infrastructures to meet growing demands for goods and services, which causes socioeconomic and environmental issues, particularly unsustainable resource supply. Considering local production systems as a more sustainable alternative, this paper presents an insight-based approach to the integrated design of local systems providing food, energy, and water to meet local demands. The approach offers a new hierarchical and iterative decision and analysis procedure incorporating design principles and ability to examine design decisions, in both synthesis of individual yet interconnected subsystems and integrated design of resource reuse across the entire system. The approach was applied to a case study on design of food-energy-water system for a locale in the U.K.; resulting in a design which significantly reduced resource consumption compared to importing goods from centralized production. The design process produced insights into the impact of one decision on other parts of the problem, either within or across different subsystems. The result was also compared to the mathematical programming approach for whole system optimization from previous work. It was demonstrated that the new approach could produce a comparable design while offering more valuable insights for decision makers.

  18. Grid-Search Location Methods for Ground-Truth Collection From Local and Regional Seismic Networks

    SciTech Connect

    William Rodi; Craig A. Schultz; Gardar Johannesson; Stephen C. Myers

    2005-05-13

    This project investigated new techniques for improving seismic event locations derived from regional and local networks. The technqiues include a new approach to empirical travel-time calibration that simultaneously fits data from multiple stations and events, using a generalization of the kriging method, and predicts travel-time corrections for arbitrary event-station paths. We combined this calibration approach with grid-search event location to produce a prototype new multiple-event location method that allows the use of spatially well-distributed events and takes into account correlations between the travel-time corrections from proximate event-station paths. Preliminary tests with a high quality data set from Nevada Test Site explosions indicated that our new calibration/location method offers improvement over the conventional multiple-event location methods now in common use, and is applicable to more general event-station geometries than the conventional methods. The tests were limited, however, and further research is needed to fully evaluate, and improve, the approach. Our project also demonstrated the importance of using a realistic model for observational errors in an event location procedure. We took the initial steps in developing a new error model based on mixture-of-Gaussians probability distributions, which possess the properties necessary to characterize the complex arrival time error processes that can occur when picking low signal-to-noise arrivals. We investigated various inference methods for fitting these distributions to observed travel-time residuals, including a Markov Chain Monte Carlo technique for computing Bayesian estimates of the distribution parameters.

  19. Modeling of nonlinear interactions between guided waves and fatigue cracks using local interaction simulation approach.

    PubMed

    Shen, Yanfeng; Cesnik, Carlos E S

    2017-02-01

    This article presents a parallel algorithm to model the nonlinear dynamic interactions between ultrasonic guided waves and fatigue cracks. The Local Interaction Simulation Approach (LISA) is further developed to capture the contact-impact clapping phenomena during the wave crack interactions based on the penalty method. Initial opening and closure distributions are considered to approximate the 3-D rough crack microscopic features. A Coulomb friction model is integrated to capture the stick-slip contact motions between the crack surfaces. The LISA procedure is parallelized via the Compute Unified Device Architecture (CUDA), which enables parallel computing on powerful graphic cards. The explicit contact formulation, the parallel algorithm, as well as the GPU-based implementation facilitate LISA's high computational efficiency over the conventional finite element method (FEM). This article starts with the theoretical formulation and numerical implementation of the proposed algorithm, followed by the solution behavior study and numerical verification against a commercial finite element code. Numerical case studies are conducted on Lamb wave interactions with fatigue cracks. Several nonlinear ultrasonic phenomena are addressed. The classical nonlinear higher harmonic and DC response are successfully captured. The nonlinear mode conversion at a through-thickness and a half-thickness fatigue crack is investigated. Threshold behaviors, induced by initial openings and closures of rough crack surfaces, are depicted by the proposed contact LISA model.

  20. Energy decomposition analysis of intermolecular interactions using a block-localized wave function approach

    NASA Astrophysics Data System (ADS)

    Mo, Yirong; Gao, Jiali; Peyerimhoff, Sigrid D.

    2000-04-01

    An energy decomposition scheme based on the block-localized wave function (BLW) method is proposed. The key of this scheme is the definition and the full optimization of the diabatic state wave function, where the charge transfer among interacting molecules is deactivated. The present energy decomposition (ED), BLW-ED, method is similar to the Morokuma decomposition scheme in definition of the energy terms, but differs in implementation and the computational algorithm. In addition, in the BLW-ED approach, the basis set superposition error is fully taken into account. The application of this scheme to the water dimer and the lithium cation-water clusters reveals that there is minimal charge transfer effect in hydrogen-bonded complexes. At the HF/aug-cc-PVTZ level, the electrostatic, polarization, and charge-transfer effects contribute 65%, 24%, and 11%, respectively, to the total bonding energy (-3.84 kcal/mol) in the water dimer. On the other hand, charge transfer effects are shown to be significant in Lewis acid-base complexes such as H3NSO3 and H3NBH3. In this work, the effect of basis sets used on the energy decomposition analysis is addressed and the results manifest that the present energy decomposition scheme is stable with a modest size of basis functions.

  1. A local crack-tracking strategy to model three-dimensional crack propagation with embedded methods

    DOE PAGES

    Annavarapu, Chandrasekhar; Settgast, Randolph R.; Vitali, Efrem; ...

    2016-09-29

    We develop a local, implicit crack tracking approach to propagate embedded failure surfaces in three-dimensions. We build on the global crack-tracking strategy of Oliver et al. (Int J. Numer. Anal. Meth. Geomech., 2004; 28:609–632) that tracks all potential failure surfaces in a problem at once by solving a Laplace equation with anisotropic conductivity. We discuss important modifications to this algorithm with a particular emphasis on the effect of the Dirichlet boundary conditions for the Laplace equation on the resultant crack path. Algorithmic and implementational details of the proposed method are provided. Finally, several three-dimensional benchmark problems are studied and resultsmore » are compared with available literature. Lastly, the results indicate that the proposed method addresses pathological cases, exhibits better behavior in the presence of closely interacting fractures, and provides a viable strategy to robustly evolve embedded failure surfaces in 3D.« less

  2. A local crack-tracking strategy to model three-dimensional crack propagation with embedded methods

    SciTech Connect

    Annavarapu, Chandrasekhar; Settgast, Randolph R.; Vitali, Efrem; Morris, Joseph P.

    2016-09-29

    We develop a local, implicit crack tracking approach to propagate embedded failure surfaces in three-dimensions. We build on the global crack-tracking strategy of Oliver et al. (Int J. Numer. Anal. Meth. Geomech., 2004; 28:609–632) that tracks all potential failure surfaces in a problem at once by solving a Laplace equation with anisotropic conductivity. We discuss important modifications to this algorithm with a particular emphasis on the effect of the Dirichlet boundary conditions for the Laplace equation on the resultant crack path. Algorithmic and implementational details of the proposed method are provided. Finally, several three-dimensional benchmark problems are studied and results are compared with available literature. Lastly, the results indicate that the proposed method addresses pathological cases, exhibits better behavior in the presence of closely interacting fractures, and provides a viable strategy to robustly evolve embedded failure surfaces in 3D.

  3. A method to compute treatment suggestions from local order entry data.

    PubMed

    Klann, Jeffrey; Schadow, Gunther; Downs, Stephen M

    2010-11-13

    Although clinical decision support systems can reduce costs and improve care, the challenges associated with manually maintaining content has led to low utilization. Here we pilot an alternative, more automatic approach to decision support content generation. We use local order entry data and Bayesian networks to automatically find multivariate associations and suggest treatments. We evaluated this on 5044 hospitalizations of pregnant women, choosing 70 frequent order and treatment variables comprising 20 treatable conditions. The method produced treatment suggestion lists for 15 of these conditions. The lists captured accurate and non-trivial clinical knowledge, and all contained the key treatment for the condition, often as the first suggestion (71% overall, 90% non-labor-related). Additionally, when run on a test set of patient data, it very accurately predicted treatments (average AUC .873) and predicted pregnancy-specific treatments with even higher accuracy (AUC above .9). This method is a starting point for harnessing the wisdom-of-the-crowd for decision support.

  4. Method for rapid localization of seafloor petroleum contamination using concurrent mass spectrometry and acoustic positioning.

    PubMed

    Camilli, R; Bingham, B; Reddy, C M; Nelson, R K; Duryea, A N

    2009-10-01

    Locating areas of seafloor contamination caused by heavy oil spills is challenging, in large part because of observational limitations in aquatic subsurface environments. Accepted methods for surveying and locating sunken oil are generally slow, labor intensive and spatially imprecise. This paper describes a method to locate seafloor contamination caused by heavy oil fractions using in situ mass spectrometry and concurrent acoustic navigation. We present results of laboratory sensitivity tests and proof-of-concept evaluations conducted at the US Coast Guard OHMSETT national oil spill response test facility. Preliminary results from a robotic seafloor contamination survey conducted in deep water using the mass spectrometer and a geo-referenced acoustic navigation system are also described. Results indicate that this technological approach can accurately localize seafloor oil contamination in real-time at spatial resolutions better than a decimeter.

  5. A local crack-tracking strategy to model three-dimensional crack propagation with embedded methods

    SciTech Connect

    Annavarapu, Chandrasekhar; Settgast, Randolph R.; Vitali, Efrem; Morris, Joseph P.

    2016-09-29

    We develop a local, implicit crack tracking approach to propagate embedded failure surfaces in three-dimensions. We build on the global crack-tracking strategy of Oliver et al. (Int J. Numer. Anal. Meth. Geomech., 2004; 28:609–632) that tracks all potential failure surfaces in a problem at once by solving a Laplace equation with anisotropic conductivity. We discuss important modifications to this algorithm with a particular emphasis on the effect of the Dirichlet boundary conditions for the Laplace equation on the resultant crack path. Algorithmic and implementational details of the proposed method are provided. Finally, several three-dimensional benchmark problems are studied and results are compared with available literature. Lastly, the results indicate that the proposed method addresses pathological cases, exhibits better behavior in the presence of closely interacting fractures, and provides a viable strategy to robustly evolve embedded failure surfaces in 3D.

  6. A Local Parabolic Method for Long Distance Wave Propagation

    DTIC Science & Technology

    2005-09-21

    centroid motion and total integrated amplitude at each point along the pulse surface. The main issue in computing these cases is that conventional...This is necessary because the Lattice Confinement terms should not depend on the scale of the quantity being confined. Another important point is that...4,VD2 2+ E5,VD xb where b is a local harmonic mean of 3 at each grid point : B~f FI N’ where 6, and VD denote discrete operators and Eqn. 1.2 was

  7. A locally implicit method for fluid flow problems

    NASA Technical Reports Server (NTRS)

    Reddy, K. C.

    1986-01-01

    The fluid flow inside the space shuttle main engine (SSME) traverses through a complex geometrical configuration. The flow is compressible, viscous, and turbulent with pockets of separated regions. Several computer codes are being developed to solve three dimensional Navier-Stokes equations with different turbulence models for analyzing the SSME internal flow. The locally implicit scheme is a computationally efficient scheme which converges rapidly in multi-grid modes for elliptic problems. It has the promise of providing a rapidly converging algorithm for steady-state viscous flow problems.

  8. A global-local approach to solving vibration of large truss structures

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Liebbe, S. W.

    1986-01-01

    A global-local approach was proposed to solve dynamic problems involving truss beams. A continuum Timoshenko beam was used to model sections of truss beams wherever possible and accurate. Near applied loads the continuum model was not adequate and detailed truss finite elements (discrete model) were employed. This approach was also proven efficient for an odd-shaped truss structure connected to a truss beam. Between the continuum model and the discrete model, compatibility conditions were derived.

  9. Novel fluorescence-based approaches for the study of biogenic amine transporter localization, activity, and regulation.

    PubMed

    Mason, J N; Farmer, H; Tomlinson, I D; Schwartz, J W; Savchenko, V; DeFelice, L J; Rosenthal, S J; Blakely, R D

    2005-04-15

    Pre-synaptic norepinephrine (NE) and dopamine (DA) transporters (NET and DAT) terminate catecholamine synaptic transmission through reuptake of released neurotransmitter. Recent studies reveal that NET and DAT are tightly regulated by receptor and second messenger-linked signaling pathways. Common approaches for studying these transporters involve use of radiolabeled substrates or antagonists, methods possessing limited spatial resolution and that bear limited opportunities for repeated monitoring of living preparations. To circumvent these issues, we have explored two novel assay platforms that permit temporally resolved quantitation of transport activity and transporter protein localization. To monitor the binding and transport function of NET and DAT in real-time, we have investigated the uptake of the fluorescent organic compound 4-(4-diethylaminostyryl)-N-methylpyridinium iodide (ASP+). We have extended our previous single cell level application of this substrate to monitor transport activity via high-throughput assay platforms. Compared to radiotracer uptake methods, acquisition of ASP+ fluorescence is non-isotopic and allows for continuous, repeated transport measurements on both transfected and native preparations. Secondly, we have extended our application of small-molecule-conjugated fluorescent CdSe/ZnS nanocrystals, or quantum dots (Qdots), to utilize antibody and peptide ligands that can identify surface expressed transporters, receptors and other membrane proteins in living cell systems. Unlike typical organic fluorophores, Qdots are highly resistant to bleaching and can be conjugated to multiple ligands. They can also be illuminated by conventional light sources, yet produce narrow, gaussian emission spectra compatible with multiple target visualization (multiplexing). Together, these approaches offer novel opportunities to investigate changes in transporter function and distribution in real-time with superior spatial and temporal resolution.

  10. An observationally centred method to quantify local climate change as a distribution

    NASA Astrophysics Data System (ADS)

    Stainforth, David; Chapman, Sandra; Watkins, Nicholas

    2013-04-01

    For planning and adaptation, guidance on trends in local climate is needed at the specific thresholds relevant to particular impact or policy endeavours. This requires quantifying trends at specific quantiles in distributions of variables such as daily temperature or precipitation. These non-normal distributions vary both geographically and in time. The trends in the relevant quantiles may not simply follow the trend in the distribution mean. We present a method[1] for analysing local climatic timeseries data to assess which quantiles of the local climatic distribution show the greatest and most robust trends. We demonstrate this approach using E-OBS gridded data[2] timeseries of local daily temperature from specific locations across Europe over the last 60 years. Our method extracts the changing cumulative distribution function over time and uses a simple mathematical deconstruction of how the difference between two observations from two different time periods can be assigned to the combination of natural statistical variability and/or the consequences of secular climate change. This deconstruction facilitates an assessment of the sensitivity of different quantiles of the distributions to changing climate. Geographical location and temperature are treated as independent variables, we thus obtain as outputs how the trend or sensitivity varies with temperature (or occurrence likelihood), and with geographical location. These sensitivities are found to be geographically varying across Europe; as one would expect given the different influences on local climate between, say, Western Scotland and central Italy. We find as an output many regionally consistent patterns of response of potential value in adaptation planning. We discuss methods to quantify the robustness of these observed sensitivities and their statistical likelihood. This also quantifies the level of detail needed from climate models if they are to be used as tools to assess climate change impact. [1] S C

  11. A localized re-initialization equation for the conservative level set method

    NASA Astrophysics Data System (ADS)

    McCaslin, Jeremy O.; Desjardins, Olivier

    2014-04-01

    The conservative level set methodology for interface transport is modified to allow for localized level set re-initialization. This approach is suitable to applications in which there is a significant amount of spatial variability in level set transport. The steady-state solution of the modified re-initialization equation matches that of the original conservative level set provided an additional Eikonal equation is solved, which can be done efficiently through a fast marching method (FMM). Implemented within the context of the accurate conservative level set method (ACLS) (Desjardins et al., 2008, [6]), the FMM solution of this Eikonal equation comes at no additional cost. A metric for the appropriate amount of local re-initialization is proposed based on estimates of local flow deformation and numerical diffusion. The method is compared to standard global re-initialization for two test cases, yielding the expected results that minor differences are observed for Zalesak's disk, and improvements in both mass conservation and interface topology are seen for a drop deforming in a vortex. Finally, the method is applied to simulation of a viscously damped standing wave and a three-dimensional drop impacting on a shallow pool. Negligible differences are observed for the standing wave, as expected. For the last case, results suggest that spatially varying re-initialization provides a reduction in spurious interfacial corrugations, improvements in the prediction of radial growth of the splashing lamella, and a reduction in conservation errors, as well as a reduction in overall computational cost that comes from improved conditioning of the pressure Poisson equation due to the removal of spurious corrugations.

  12. Locally-calibrated light transmission visualization methods to quantify nonaqueous phase liquid mass in porous media

    NASA Astrophysics Data System (ADS)

    Wang, Huaguo; Chen, Xiaosong; Jawitz, James W.

    2008-11-01

    Five locally-calibrated light transmission visualization (LTV) methods were tested to quantify nonaqueous phase liquid (NAPL) mass and mass reduction in porous media. Tetrachloroethylene (PCE) was released into a two-dimensional laboratory flow chamber packed with water-saturated sand which was then flushed with a surfactant solution (2% Tween 80) until all of the PCE had been dissolved. In all the LTV methods employed here, the water phase was dyed, rather than the more common approach of dyeing the NAPL phase, such that the light adsorption characteristics of NAPL did not change as dissolution progressed. Also, none of the methods used here required the use of external calibration chambers. The five visualization approaches evaluated included three methods developed from previously published models, a binary method, and a novel multiple wavelength method that has the advantage of not requiring any assumptions about the intra-pore interface structure between the various phases (sand/water/NAPL). The new multiple wavelength method is also expected to be applicable to any translucent porous media containing two immiscible fluids (e.g., water-air, water-NAPL). Results from the sand-water-PCE system evaluated here showed that the model that assumes wetting media of uniform pore size (Model C of Niemet and Selker, 2001) and the multiple wavelength model with no interface structure assumptions were able to accurately quantify PCE mass reduction during surfactant flushing. The average mass recoveries from these two imaging methods were greater than 95% for domain-average NAPL saturations of approximately 2.6 × 10 - 2 , and were approximately 90% during seven cycles of surfactant flushing that sequentially reduced the average NAPL saturation to 7.5 × 10 - 4 .

  13. Local Hamiltonians for quantitative Green's function embedding methods

    NASA Astrophysics Data System (ADS)

    Rusakov, Alexander A.; Phillips, Jordan J.; Zgid, Dominika

    2014-11-01

    Embedding calculations that find approximate solutions to the Schrödinger equation for large molecules and realistic solids are performed commonly in a three step procedure involving (i) construction of a model system with effective interactions approximating the low energy physics of the initial realistic system, (ii) mapping the model system onto an impurity Hamiltonian, and (iii) solving the impurity problem. We have developed a novel procedure for parametrizing the impurity Hamiltonian that avoids the mathematically uncontrolled step of constructing the low energy model system. Instead, the impurity Hamiltonian is immediately parametrized to recover the self-energy of the realistic system in the limit of high frequencies or short time. The effective interactions parametrizing the fictitious impurity Hamiltonian are local to the embedded regions, and include all the non-local interactions present in the original realistic Hamiltonian in an implicit way. We show that this impurity Hamiltonian can lead to excellent total energies and self-energies that approximate the quantities of the initial realistic system very well. Moreover, we show that as long as the effective impurity Hamiltonian parametrization is designed to recover the self-energy of the initial realistic system for high frequencies, we can expect a good total energy and self-energy. Finally, we propose two practical ways of evaluating effective integrals for parametrizing impurity models.

  14. An Improved Local Search Learning Method for Multiple-Valued Logic Network Minimization with Bi-objectives

    NASA Astrophysics Data System (ADS)

    Gao, Shangce; Cao, Qiping; Vairappan, Catherine; Zhang, Jianchen; Tang, Zheng

    This paper describes an improved local search method for synthesizing arbitrary Multiple-Valued Logic (MVL) function. In our approach, the MVL function is mapped from its algebraic presentation (sum-of-products form) on a multiple-layered network based on the functional completeness property. The output of the network is evaluated based on two metrics of correctness and optimality. A local search embedded with chaotic dynamics is utilized to train the network in order to minimize the MVL functions. With the characteristics of pseudo-randomness, ergodicity and irregularity, both the search sequence and solution neighbourhood generated by chaotic variables enables the system to avoid local minimum settling and improves the solution quality. Simulation results based on 2-variable 4-valued MVL functions and some other large instances also show that the improved local search learning algorithm outperforms the traditional methods in terms of the correctness and the average number of product terms required to realize a given MVL function.

  15. Local Strategy Combined with a Wavelength Selection Method for Multivariate Calibration

    PubMed Central

    Chang, Haitao; Zhu, Lianqing; Lou, Xiaoping; Meng, Xiaochen; Guo, Yangkuan; Wang, Zhongyu

    2016-01-01

    One of the essential factors influencing the prediction accuracy of multivariate calibration models is the quality of the calibration data. A local regression strategy, together with a wavelength selection approach, is proposed to build the multivariate calibration models based on partial least squares regression. The local algorithm is applied to create a calibration set of spectra similar to the spectrum of an unknown sample; the synthetic degree of grey relation coefficient is used to evaluate the similarity. A wavelength selection method based on simple-to-use interactive self-modeling mixture analysis minimizes the influence of noisy variables, and the most informative variables of the most similar samples are selected to build the multivariate calibration model based on partial least squares regression. To validate the performance of the proposed method, ultraviolet-visible absorbance spectra of mixed solutions of food coloring analytes in a concentration range of 20–200 µg/mL is measured. Experimental results show that the proposed method can not only enhance the prediction accuracy of the calibration model, but also greatly reduce its complexity. PMID:27271636

  16. Locating Damage Using Integrated Global-Local Approach with Wireless Sensing System and Single-Chip Impedance Measurement Device

    PubMed Central

    Hung, Shih-Lin

    2014-01-01

    This study developed an integrated global-local approach for locating damage on building structures. A damage detection approach with a novel embedded frequency response function damage index (NEFDI) was proposed and embedded in the Imote2.NET-based wireless structural health monitoring (SHM) system to locate global damage. Local damage is then identified using an electromechanical impedance- (EMI-) based damage detection method. The electromechanical impedance was measured using a single-chip impedance measurement device which has the advantages of small size, low cost, and portability. The feasibility of the proposed damage detection scheme was studied with reference to a numerical example of a six-storey shear plane frame structure and a small-scale experimental steel frame. Numerical and experimental analysis using the integrated global-local SHM approach reveals that, after NEFDI indicates the approximate location of a damaged area, the EMI-based damage detection approach can then identify the detailed damage location in the structure of the building. PMID:24672359

  17. Problems d'elaboration d'une methode locale: la methode "Paris-Khartoum" (Problems in Implementing a Local Method: the Paris-Khartoum Method)

    ERIC Educational Resources Information Center

    Penhoat, Loick; Sakow, Kostia

    1978-01-01

    A description of the development and implementation of a method introduced in the Sudan that attempts to relate to Sudanese culture and to motivate students. The relationship between language teaching methods and the total educational system is discussed. (AMH)

  18. A Modified Magnetic Gradient Contraction Based Method for Ferromagnetic Target Localization

    PubMed Central

    Wang, Chen; Zhang, Xiaojuan; Qu, Xiaodong; Pan, Xiao; Fang, Guangyou; Chen, Luzhao

    2016-01-01

    The Scalar Triangulation and Ranging (STAR) method, which is based upon the unique properties of magnetic gradient contraction, is a high real-time ferromagnetic target localization method. Only one measurement point is required in the STAR method and it is not sensitive to changes in sensing platform orientation. However, the localization accuracy of the method is limited by the asphericity errors and the inaccurate value of position leads to larger errors in the estimation of magnetic moment. To improve the localization accuracy, a modified STAR method is proposed. In the proposed method, the asphericity errors of the traditional STAR method are compensated with an iterative algorithm. The proposed method has a fast convergence rate which meets the requirement of high real-time localization. Simulations and field experiments have been done to evaluate the performance of the proposed method. The results indicate that target parameters estimated by the modified STAR method are more accurate than the traditional STAR method. PMID:27999322

  19. Simplified approaches to some nonoverlapping domain decomposition methods

    SciTech Connect

    Xu, Jinchao

    1996-12-31

    An attempt will be made in this talk to present various domain decomposition methods in a way that is intuitively clear and technically coherent and concise. The basic framework used for analysis is the {open_quotes}parallel subspace correction{close_quotes} or {open_quotes}additive Schwarz{close_quotes} method, and other simple technical tools include {open_quotes}local-global{close_quotes} and {open_quotes}global-local{close_quotes} techniques, the formal one is for constructing subspace preconditioner based on a preconditioner on the whole space whereas the later one for constructing preconditioner on the whole space based on a subspace preconditioner. The domain decomposition methods discussed in this talk fall into two major categories: one, based on local Dirichlet problems, is related to the {open_quotes}substructuring method{close_quotes} and the other, based on local Neumann problems, is related to the {open_quotes}Neumann-Neumann method{close_quotes} and {open_quotes}balancing method{close_quotes}. All these methods will be presented in a systematic and coherent manner and the analysis for both two and three dimensional cases are carried out simultaneously. In particular, some intimate relationship between these algorithms are observed and some new variants of the algorithms are obtained.

  20. A hybrid passive localization method under strong interference with a preliminary experimental demonstration

    NASA Astrophysics Data System (ADS)

    Lei, Bo; Yang, Yixin; Yang, Kunde; Wang, Yong; Shi, Yang

    2016-12-01

    Strong interference exists in many passive localization problems and may lead to the inefficacy of traditional localization methods. In this study, a hybrid passive localization method is proposed to address strong interference. This method combines generalized cross-correlation and interference cancellation for time-difference-of-arrival (TDOA) measurement, followed by a time-delay-based iterative localization method. The proposed method is applied to a preliminary experiment using three hydrophones. The TDOAs estimated by the proposed method are compared with those obtained by the particle filtering method. Results show that the positions are in agreement when the TDOAs are accurately obtained. Furthermore, the proposed method is more capable of localization in the presence of a strong moving jamming source.

  1. A novel evolutionary approach to image enhancement filter design: method and applications.

    PubMed

    Hong, Jin-Hyuk; Cho, Sung-Bae; Cho, Ung-Keun

    2009-12-01

    Image enhancement is an important issue in digital image processing. Various approaches have been developed to solve image enhancement problems, but most of them require deep expert knowledge to design appropriate image filters. To automatically design a filter, we propose a novel approach based on the genetic algorithm that optimizes a set of standard filters by determining their types and order. Moreover, the proposed method is able to manage various types of noise factors. We applied the proposed method to local and global image enhancement problems such as impulsive noise reduction, interpolation, and orientation enhancement. In terms of subjective and objective evaluations, the results show the superiority of the proposed method.

  2. Local Recurrence After Primary Proton Beam Therapy in Uveal Melanoma: Risk Factors, Retreatment Approaches, and Outcome.

    PubMed

    Seibel, Ira; Cordini, Dino; Rehak, Matus; Hager, Annette; Riechardt, Aline I; Böker, Alexander; Heufelder, Jens; Weber, Andreas; Gollrad, Johannes; Besserer, Angela; Joussen, Antonia M

    2015-10-01

    To evaluate the risk factors, recurrence rates, retreatments, and long-term patient outcomes following proton beam therapy for uveal melanoma. Retrospective interventional case series. All patients treated with primary proton beam therapy for uveal melanoma at the oncology service at Charité-Berlin and Helmholtz-Zentrum-Berlin between May 1998 and December 2008 were reviewed for local recurrence. Of 982 patients, 982 eyes matched the inclusion criteria. The data were obtained from electronic health records, operative reports, discharge letters, and radiation planning. Comparisons of fundus photographs and ultrasound measurements were performed to assess the growth pattern of the tumor and to determine the success of retreatment, in the case that a globe-retaining therapy was undertaken. Of 982 patients, 35 patients (3.6%) developed local recurrence. The median follow-up was 60.7 months (6.0-170.4 months). Local control rate was 96.4% and the overall eye retention rate was 95.0% in this cohort. Local recurrence was correlated with a higher risk for metastasis and reduced survival. Largest tumor diameter was identified as the sole statistically significant risk factor for local recurrence (P = .00001). All globe-retaining retreatment approaches for local recurrence, including proton beam therapy, brachytherapy, and transpupillary thermotherapy used for recurrences at the tumor margins, showed good local tumor control and similar metastasis-free survivals. This study showed that each globe-retaining retreatment approach can result in satisfying local tumor control. In case of early detection of local recurrence, preservation of the globe can be warranted. Therefore, regularly performed follow-ups should be ensured. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Factors influencing local communities' satisfaction levels with different forest management approaches of Kakamega forest, Kenya.

    PubMed

    Guthiga, Paul M; Mburu, John; Holm-Mueller, Karin

    2008-05-01

    Satisfaction of communities living close to forests with forest management authorities is essential for ensuring continued support for conservation efforts. However, more often than not, community satisfaction is not systematically elicited, analyzed, and incorporated in conservation decisions. This study attempts to elicit levels of community satisfaction with three management approaches of Kakamega forest in Kenya and analyze factors influencing them. Three distinct management approaches are applied by three different authorities: an incentive-based approach of the Forest Department (FD), a protectionist approach of the Kenya Wildlife Service (KWS), and a quasi-private incentive-based approach of Quakers Church Mission (QCM). Data was obtained from a random sample of about 360 households living within a 10-km radius around the forest margin. The protectionist approach was ranked highest overall for its performance in forest management. Results indicate that households are influenced by different factors in their ranking of management approaches. Educated households and those located far from market centers are likely to be dissatisfied with all the three management approaches. The location of the households from the forest margin influences negatively the satisfaction with the protectionist approach, whereas land size, a proxy for durable assets, has a similar effect on the private incentive based approach of the QCM. In conclusion, this article indicates a number of policy implications that can enable the different authorities and their management approaches to gain approval of the local communities.

  4. Factors Influencing Local Communities' Satisfaction Levels with Different Forest Management Approaches of Kakamega Forest, Kenya

    NASA Astrophysics Data System (ADS)

    Guthiga, Paul M.; Mburu, John; Holm-Mueller, Karin

    2008-05-01

    Satisfaction of communities living close to forests with forest management authorities is essential for ensuring continued support for conservation efforts. However, more often than not, community satisfaction is not systematically elicited, analyzed, and incorporated in conservation decisions. This study attempts to elicit levels of community satisfaction with three management approaches of Kakamega forest in Kenya and analyze factors influencing them. Three distinct management approaches are applied by three different authorities: an incentive-based approach of the Forest Department (FD), a protectionist approach of the Kenya Wildlife Service (KWS), and a quasi-private incentive-based approach of Quakers Church Mission (QCM). Data was obtained from a random sample of about 360 households living within a 10-km radius around the forest margin. The protectionist approach was ranked highest overall for its performance in forest management. Results indicate that households are influenced by different factors in their ranking of management approaches. Educated households and those located far from market centers are likely to be dissatisfied with all the three management approaches. The location of the households from the forest margin influences negatively the satisfaction with the protectionist approach, whereas land size, a proxy for durable assets, has a similar effect on the private incentive based approach of the QCM. In conclusion, this article indicates a number of policy implications that can enable the different authorities and their management approaches to gain approval of the local communities.

  5. A tracking approach to localization and synchronization in mobile ad-hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Bidigare, Patrick; Kreucher, Chris; Conti, Ralph

    2006-05-01

    Self localization is a term used to describe the ability of a network to automatically determine the location of its nodes, given little or no external information. Self localization is an enabling technology for many future capabilities; specifically those that rely on a large number of sensors that self organize to form a coherent system. Most prior work in this area focuses on centralized computation with stationary nodes and synchronized clocks. We report on preliminary results for a setting that is more general in three ways. First, nodes in the network are moving. This implies the pair-wise distances between nodes are not fixed and therefore an iterative tracking procedure is needed to estimate the time varying node positions. Second, we do not assume synchronization between clocks on different nodes. In fact, we allow the clocks to have both an unknown offset and to be running at differing rates (i.e., a drift). Third, our method is decentralized, so there is no need for a single entity withfaccess to all measurements. In this setup, each node in the network is responsible for estimating its state. The method is based on repeated pair-wise communication between nodes. We focus on two types of observables in this paper. First, we use the time between when a message was sent from one node and when it was received by another node. In the case of synchronized clocks and stationary nodes, this observable provides information about the distance between the nodes. In the more general case with non-synchronized clocks, this observable is coupled to the clock offsets and drifts as well as the distance between nodes. Second, we use the Doppler stretch observed by the receiving node. In the case of synchronized clocks, this observable provides information about the line of sight velocity between the nodes. In the case of non-synchronized clocks, this observable is coupled to the clock drift as well as the line of sight velocity. We develop a sophisticated mathematical

  6. An improved method for Daugman's iris localization algorithm.

    PubMed

    Ren, Xinying; Peng, Zhiyong; Zeng, Qingning; Peng, Chaonan; Zhang, Jianhua; Wu, Shuicai; Zeng, Yanjun

    2008-01-01

    Computer-based automatic recognition of persons for security reasons is highly desirable. Iris patterns provide an opportunity for separation of individuals to an extent that would avoid false positives and negatives. The current standard for this science is Daugman's iris localization algorithm. Part of the time required for analysis and comparison with other images relates to eyelid and eyelash positioning and length. We sought to remove the upper and lower eyelids and eyelashes to determine if separation of individuals could still be attained. Our experiments suggest separation can be achieved as effectively and more quickly by removing distracting and variable features while retaining enough stable factors in the iris to enable accurate identification.

  7. International Students' Motivation and Learning Approach: A Comparison with Local Students

    ERIC Educational Resources Information Center

    Chue, Kah Loong; Nie, Youyan

    2016-01-01

    Psychological factors contribute to motivation and learning for international students as much as teaching strategies. 254 international students and 144 local students enrolled in a private education institute were surveyed regarding their perception of psychological needs support, their motivation and learning approach. The results from this…

  8. New hidden beauty molecules predicted by the local hidden gauge approach and heavy quark spin symmetry

    NASA Astrophysics Data System (ADS)

    Xiao, C. W.; Ozpineci, A.; Oset, E.

    2015-10-01

    Using a coupled channel unitary approach, combining the heavy quark spin symmetry and the dynamics of the local hidden gauge, we investigate the meson-meson interaction with hidden beauty. We obtain several new states of isospin I = 0: six bound states, and weakly bound six more possible states which depend on the influence of the coupled channel effects.

  9. A Discourse Based Approach to the Language Documentation of Local Ecological Knowledge

    ERIC Educational Resources Information Center

    Odango, Emerson Lopez

    2016-01-01

    This paper proposes a discourse-based approach to the language documentation of local ecological knowledge (LEK). The knowledge, skills, beliefs, cultural worldviews, and ideologies that shape the way a community interacts with its environment can be examined through the discourse in which LEK emerges. 'Discourse-based' refers to two components:…

  10. A Discourse Based Approach to the Language Documentation of Local Ecological Knowledge

    ERIC Educational Resources Information Center

    Odango, Emerson Lopez

    2016-01-01

    This paper proposes a discourse-based approach to the language documentation of local ecological knowledge (LEK). The knowledge, skills, beliefs, cultural worldviews, and ideologies that shape the way a community interacts with its environment can be examined through the discourse in which LEK emerges. 'Discourse-based' refers to two components:…

  11. The Diverse Forms of Tech-Prep: Implementation Approaches in Ten Local Consortia.

    ERIC Educational Resources Information Center

    Hershey, Alan; And Others

    This document profiles the diverse approaches to tech-prep taken by 10 local districts across the United States. The tech-prep programs in the following cities are profiled: Dayton, Ohio; Dothan, Alabama; East Peoria, Illinois; Fresno, California; Gainesville, Florida; Hartford, Connecticut; Logan, West Virginia; Salem, Oregon; Springdale,…

  12. Localized surface plasmon resonance mercury detection system and methods

    DOEpatents

    James, Jay; Lucas, Donald; Crosby, Jeffrey Scott; Koshland, Catherine P.

    2016-03-22

    A mercury detection system that includes a flow cell having a mercury sensor, a light source and a light detector is provided. The mercury sensor includes a transparent substrate and a submonolayer of mercury absorbing nanoparticles, e.g., gold nanoparticles, on a surface of the substrate. Methods of determining whether mercury is present in a sample using the mercury sensors are also provided. The subject mercury detection systems and methods find use in a variety of different applications, including mercury detecting applications.

  13. Joint motion model for local stereo video-matching method

    NASA Astrophysics Data System (ADS)

    Zhang, Jinglin; Bai, Cong; Nezan, Jean-Francois; Cousin, Jean-Gabriel

    2015-12-01

    As one branch of stereo matching, video stereo matching becomes more and more significant in computer vision applications. The conventional stereo matching methods for static images would cause flicker-frames and worse matching results. We propose a joint motion-based square step (JMSS) method for stereo video matching. The motion vector is introduced as one component in the support region building for the raw cost aggregation. Then we aggregate the raw cost along two directions in the support region. Finally, the winner-take-all strategy determines the best disparity under our hypothesis. Experimental results show that the JMSS method not only outperforms other state-of-the-art stereo matching methods on test sequences with abundant movements, but also performs well in some real-world scenes with fixed and moving stereo cameras, respectively, in particular under some extreme conditions of real stereo visions. Additionally, the proposed JMSS method can be implemented in real time, which is superior to other state-of-the-art methods. The time efficiency is also a very important consideration in our algorithm design.

  14. Method for optical coherence tomography image classification using local features and earth mover's distance

    NASA Astrophysics Data System (ADS)

    Sun, Yankui; Lei, Ming

    2009-09-01

    Optical coherence tomography (OCT) is a recent imaging method that allows high-resolution, cross-sectional imaging through tissues and materials. Over the past 18 years, OCT has been successfully used in disease diagnosis, biomedical research, material evaluation, and many other domains. As OCT is a recent imaging method, until now surgeons have limited experience using it. In addition, the number of images obtained from the imaging device is too large, so we need an automated method to analyze them. We propose a novel method for automated classification of OCT images based on local features and earth mover's distance (EMD). We evaluated our algorithm using an OCT image set which contains two kinds of skin images, normal skin and nevus flammeus. Experimental results demonstrate the effectiveness of our method, which achieved classification accuracy of 0.97 for an EMD+KNN scheme and 0.99 for an EMD+SVM (support vector machine) scheme, much higher than the previous method. Our approach is especially suitable for nonhomogeneous images and could be applied to a wide range of OCT images.

  15. Water-sanitation-hygiene mapping: an improved approach for data collection at local level.

    PubMed

    Giné-Garriga, Ricard; de Palencia, Alejandro Jiménez-Fernández; Pérez-Foguet, Agustí

    2013-10-01

    Strategic planning and appropriate development and management of water and sanitation services are strongly supported by accurate and accessible data. If adequately exploited, these data might assist water managers with performance monitoring, benchmarking comparisons, policy progress evaluation, resources allocation, and decision making. A variety of tools and techniques are in place to collect such information. However, some methodological weaknesses arise when developing an instrument for routine data collection, particularly at local level: i) comparability problems due to heterogeneity of indicators, ii) poor reliability of collected data, iii) inadequate combination of different information sources, and iv) statistical validity of produced estimates when disaggregated into small geographic subareas. This study proposes an improved approach for water, sanitation and hygiene (WASH) data collection at decentralised level in low income settings, as an attempt to overcome previous shortcomings. The ultimate aim is to provide local policymakers with strong evidences to inform their planning decisions. The survey design takes the Water Point Mapping (WPM) as a starting point to record all available water sources at a particular location. This information is then linked to data produced by a household survey. Different survey instruments are implemented to collect reliable data by employing a variety of techniques, such as structured questionnaires, direct observation and water quality testing. The collected data is finally validated through simple statistical analysis, which in turn produces valuable outputs that might feed into the decision-making process. In order to demonstrate the applicability of the method, outcomes produced from three different case studies (Homa Bay District-Kenya-; Kibondo District-Tanzania-; and Municipality of Manhiça-Mozambique-) are presented. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Grid-Search Location Methods for Ground-Truth Collection from Local and Regional Seismic Networks

    SciTech Connect

    Schultz, C A; Rodi, W; Myers, S C

    2003-07-24

    The objective of this project is to develop improved seismic event location techniques that can be used to generate more and better quality reference events using data from local and regional seismic networks. Their approach is to extend existing methods of multiple-event location with more general models of the errors affecting seismic arrival time data, including picking errors and errors in model-based travel-times (path corrections). Toward this end, they are integrating a grid-search based algorithm for multiple-event location (GMEL) with a new parameterization of travel-time corrections and new kriging method for estimating the correction parameters from observed travel-time residuals. Like several other multiple-event location algorithms, GMEL currently assumes event-independent path corrections and is thus restricted to small event clusters. The new parameterization assumes that travel-time corrections are a function of both the event and station location, and builds in source-receiver reciprocity and correlation between the corrections from proximate paths as constraints. The new kriging method simultaneously interpolates travel-time residuals from multiple stations and events to estimate the correction parameters as functions of position. They are currently developing the algorithmic extensions to GMEL needed to combine the new parameterization and kriging method with the simultaneous location of events. The result will be a multiple-event location method which is applicable to non-clustered, spatially well-distributed events. They are applying the existing components of the new multiple-event location method to a data set of regional and local arrival times from Nevada Test Site (NTS) explosions with known origin parameters. Preliminary results show the feasibility and potential benefits of combining the location and kriging techniques. They also show some preliminary work on generalizing of the error model used in GMEL with the use of mixture

  17. Local Orthogonal Cutting Method for Computing Medial Curves and Its Biomedical Applications

    SciTech Connect

    Jiao, Xiangmin; Einstein, Daniel R.; Dyedov, Volodymyr

    2010-03-24

    Medial curves have a wide range of applications in geometric modeling and analysis (such as shape matching) and biomedical engineering (such as morphometry and computer assisted surgery). The computation of medial curves poses significant challenges, both in terms of theoretical analysis and practical efficiency and reliability. In this paper, we propose a definition and analysis of medial curves and also describe an efficient and robust method for computing medial curves. Our approach is based on three key concepts: a local orthogonal decomposition of objects into substructures, a differential geometry concept called the interior center of curvature (ICC), and integrated stability and consistency tests. These concepts lend themselves to robust numerical techniques including eigenvalue analysis, weighted least squares approximations, and numerical minimization, resulting in an algorithm that is efficient and noise resistant. We illustrate the effectiveness and robustness of our approach with some highly complex, large-scale, noisy biomedical geometries derived from medical images, including lung airways and blood vessels. We also present comparisons of our method with some existing methods.

  18. An efficient implementation of the localized operator partitioning method for electronic energy transfer

    SciTech Connect

    Nagesh, Jayashree; Brumer, Paul; Izmaylov, Artur F.

    2015-02-28

    The localized operator partitioning method [Y. Khan and P. Brumer, J. Chem. Phys. 137, 194112 (2012)] rigorously defines the electronic energy on any subsystem within a molecule and gives a precise meaning to the subsystem ground and excited electronic energies, which is crucial for investigating electronic energy transfer from first principles. However, an efficient implementation of this approach has been hindered by complicated one- and two-electron integrals arising in its formulation. Using a resolution of the identity in the definition of partitioning, we reformulate the method in a computationally efficient manner that involves standard one- and two-electron integrals. We apply the developed algorithm to the 9 − ((1 − naphthyl) − methyl) − anthracene (A1N) molecule by partitioning A1N into anthracenyl and CH{sub 2} − naphthyl groups as subsystems and examine their electronic energies and populations for several excited states using configuration interaction singles method. The implemented approach shows a wide variety of different behaviors amongst the excited electronic states.

  19. An Evaluation of the New Approach Method--Final Report.

    ERIC Educational Resources Information Center

    Powers, Donald E.

    The New Approach Method (NAM) is an innovative reading program relying heavily on a phonics approach. The mode of presentation is a cassette tape recorder, which the child is taught to operate at the beginning of the program. The NAM lessons were administered to children at four NAM mini centers; a group of parents administered the NAM lessons to…

  20. Continuous probabilistic approach to species dynamics in Hubbell's zero-sum local community

    NASA Astrophysics Data System (ADS)

    Babak, Petro

    2006-08-01

    In this paper a continuous probabilistic approach formulated using Kolmogorov-Fokker-Planck forward and backward models is applied to Hubbell’s zero-sum neutral theory for species dynamics in local community. Using this technique the probability density of species abundance, distribution of the first passage time to extinction or fixation and probability of extinction are defined. The resulting values for the distribution of the first passage time to extinction are verified by the simulation study of Hubbell’s zero-sum neutral model for the local community. Based on the sensitivity analysis for the continuous probabilistic models, the realistic classification of local communities subject to their diversity and species dynamics is proposed with respect to the immigration probability, the species metacommunity relative abundance, and the size of local community.

  1. An Improved Otsu Threshold Segmentation Method for Underwater Simultaneous Localization and Mapping-Based Navigation

    PubMed Central

    Yuan, Xin; Martínez, José-Fernán; Eckert, Martina; López-Santidrián, Lourdes

    2016-01-01

    The main focus of this paper is on extracting features with SOund Navigation And Ranging (SONAR) sensing for further underwater landmark-based Simultaneous Localization and Mapping (SLAM). According to the characteristics of sonar images, in this paper, an improved Otsu threshold segmentation method (TSM) has been developed for feature detection. In combination with a contour detection algorithm, the foreground objects, although presenting different feature shapes, are separated much faster and more precisely than by other segmentation methods. Tests have been made with side-scan sonar (SSS) and forward-looking sonar (FLS) images in comparison with other four TSMs, namely the traditional Otsu method, the local TSM, the iterative TSM and the maximum entropy TSM. For all the sonar images presented in this work, the computational time of the improved Otsu TSM is much lower than that of the maximum entropy TSM, which achieves the highest segmentation precision among the four above mentioned TSMs. As a result of the segmentations, the centroids of the main extracted regions have been computed to represent point landmarks which can be used for navigation, e.g., with the help of an Augmented Extended Kalman Filter (AEKF)-based SLAM algorithm. The AEKF-SLAM approach is a recursive and iterative estimation-update process, which besides a prediction and an update stage (as in classical Extended Kalman Filter (EKF)), includes an augmentation stage. During navigation, the robot localizes the centroids of different segments of features in sonar images, which are detected by our improved Otsu TSM, as point landmarks. Using them with the AEKF achieves more accurate and robust estimations of the robot pose and the landmark positions, than with those detected by the maximum entropy TSM. Together with the landmarks identified by the proposed segmentation algorithm, the AEKF-SLAM has achieved reliable detection of cycles in the map and consistent map update on loop closure, which is

  2. An Improved Otsu Threshold Segmentation Method for Underwater Simultaneous Localization and Mapping-Based Navigation.

    PubMed

    Yuan, Xin; Martínez, José-Fernán; Eckert, Martina; López-Santidrián, Lourdes

    2016-07-22

    The main focus of this paper is on extracting features with SOund Navigation And Ranging (SONAR) sensing for further underwater landmark-based Simultaneous Localization and Mapping (SLAM). According to the characteristics of sonar images, in this paper, an improved Otsu threshold segmentation method (TSM) has been developed for feature detection. In combination with a contour detection algorithm, the foreground objects, although presenting different feature shapes, are separated much faster and more precisely than by other segmentation methods. Tests have been made with side-scan sonar (SSS) and forward-looking sonar (FLS) images in comparison with other four TSMs, namely the traditional Otsu method, the local TSM, the iterative TSM and the maximum entropy TSM. For all the sonar images presented in this work, the computational time of the improved Otsu TSM is much lower than that of the maximum entropy TSM, which achieves the highest segmentation precision among the four above mentioned TSMs. As a result of the segmentations, the centroids of the main extracted regions have been computed to represent point landmarks which can be used for navigation, e.g., with the help of an Augmented Extended Kalman Filter (AEKF)-based SLAM algorithm. The AEKF-SLAM approach is a recursive and iterative estimation-update process, which besides a prediction and an update stage (as in classical Extended Kalman Filter (EKF)), includes an augmentation stage. During navigation, the robot localizes the centroids of different segments of features in sonar images, which are detected by our improved Otsu TSM, as point landmarks. Using them with the AEKF achieves more accurate and robust estimations of the robot pose and the landmark positions, than with those detected by the maximum entropy TSM. Together with the landmarks identified by the proposed segmentation algorithm, the AEKF-SLAM has achieved reliable detection of cycles in the map and consistent map update on loop closure, which is

  3. An Ensemble Method for Predicting Subnuclear Localizations from Primary Protein Structures

    PubMed Central

    Han, Guo Sheng; Yu, Zu Guo; Anh, Vo; Krishnajith, Anaththa P. D.; Tian, Yu-Chu

    2013-01-01

    Background Predicting protein subnuclear localization is a challenging problem. Some previous works based on non-sequence information including Gene Ontology annotations and kernel fusion have respective limitations. The aim of this work is twofold: one is to propose a novel individual feature extraction method; another is to develop an ensemble method to improve prediction performance using comprehensive information represented in the form of high dimensional feature vector obtained by 11 feature extraction methods. Methodology/Principal Findings A novel two-stage multiclass support vector machine is proposed to predict protein subnuclear localizations. It only considers those feature extraction methods based on amino acid classifications and physicochemical properties. In order to speed up our system, an automatic search method for the kernel parameter is used. The prediction performance of our method is evaluated on four datasets: Lei dataset, multi-localization dataset, SNL9 dataset and a new independent dataset. The overall accuracy of prediction for 6 localizations on Lei dataset is 75.2% and that for 9 localizations on SNL9 dataset is 72.1% in the leave-one-out cross validation, 71.7% for the multi-localization dataset and 69.8% for the new independent dataset, respectively. Comparisons with those existing methods show that our method performs better for both single-localization and multi-localization proteins and achieves more balanced sensitivities and specificities on large-size and small-size subcellular localizations. The overall accuracy improvements are 4.0% and 4.7% for single-localization proteins and 6.5% for multi-localization proteins. The reliability and stability of our classification model are further confirmed by permutation analysis. Conclusions It can be concluded that our method is effective and valuable for predicting protein subnuclear localizations. A web server has been designed to implement the proposed method. It is freely available

  4. Development of acoustic sniper localization methods and models

    NASA Astrophysics Data System (ADS)

    Grasing, David; Ellwood, Benjamin

    2010-04-01

    A novel examination of a method capable of providing situational awareness of sniper fire from small arms fire is presented. Situational Awareness (SA) information is extracted by exploiting two distinct sounds created by small arms discharge: the muzzle blast (created when the bullet leaves the barrel of the gun) and the shockwave (sound created by a supersonic bullet). The direction of arrival associated with the muzzle blast will always point in the direction of the shooter. Range can be estimated from the muzzle blast alone, however at greater distances geometric dilution of precision will make obtaining accurate range estimates difficult. To address this issue, additional information obtained from the shockwave is utilized in order to estimate range to shooter. The focus of the paper is the development of a shockwave propagation model, the development of ballistics models (based off empirical measurements), and the subsequent application towards methods of determining shooter position. Knowledge of the rounds ballistics is required to estimate range to shooter. Many existing methods rely on extracting information from the shockwave in an attempt to identify the round type and thus the ballistic model to use ([1]). It has been our experience that this information becomes unreliable at greater distances or in high noise environments. Our method differs from existing solutions in that classification of the round type is not required, thus making the proposed solution more robust. Additionally, we demonstrate that sufficient accuracy can be achieved without the need to classify the round.

  5. Gaussian Process Regression Plus Method for Localization Reliability Improvement

    PubMed Central

    Liu, Kehan; Meng, Zhaopeng; Own, Chung-Ming

    2016-01-01

    Location data are among the most widely used context data in context-aware and ubiquitous computing applications. Many systems with distinct deployment costs and positioning accuracies have been developed over the past decade for indoor positioning. The most useful method is focused on the received signal strength and provides a set of signal transmission access points. However, compiling a manual measuring Received Signal Strength (RSS) fingerprint database involves high costs and thus is impractical in an online prediction environment. The system used in this study relied on the Gaussian process method, which is a nonparametric model that can be characterized completely by using the mean function and the covariance matrix. In addition, the Naive Bayes method was used to verify and simplify the computation of precise predictions. The authors conducted several experiments on simulated and real environments at Tianjin University. The experiments examined distinct data size, different kernels, and accuracy. The results showed that the proposed method not only can retain positioning accuracy but also can save computation time in location predictions. PMID:27483276

  6. Gaussian Process Regression Plus Method for Localization Reliability Improvement.

    PubMed

    Liu, Kehan; Meng, Zhaopeng; Own, Chung-Ming

    2016-07-29

    Location data are among the most widely used context data in context-aware and ubiquitous computing applications. Many systems with distinct deployment costs and positioning accuracies have been developed over the past decade for indoor positioning. The most useful method is focused on the received signal strength and provides a set of signal transmission access points. However, compiling a manual measuring Received Signal Strength (RSS) fingerprint database involves high costs and thus is impractical in an online prediction environment. The system used in this study relied on the Gaussian process method, which is a nonparametric model that can be characterized completely by using the mean function and the covariance matrix. In addition, the Naive Bayes method was used to verify and simplify the computation of precise predictions. The authors conducted several experiments on simulated and real environments at Tianjin University. The experiments examined distinct data size, different kernels, and accuracy. The results showed that the proposed method not only can retain positioning accuracy but also can save computation time in location predictions.

  7. An integrated lean-methods approach to hospital facilities redesign.

    PubMed

    Nicholas, John

    2012-01-01

    Lean production methods for eliminating waste and improving processes in manufacturing are now being applied in healthcare. As the author shows, the methods are appropriate for redesigning hospital facilities. When used in an integrated manner and employing teams of mostly clinicians, the methods produce facility designs that are custom-fit to patient needs and caregiver work processes, and reduce operational costs. The author reviews lean methods and an approach for integrating them in the redesign of hospital facilities. A case example of the redesign of an emergency department shows the feasibility and benefits of the approach.

  8. The local maxima method for enhancement of time-frequency map and its application to local damage detection in rotating machines

    NASA Astrophysics Data System (ADS)

    Obuchowski, Jakub; Wyłomańska, Agnieszka; Zimroz, Radosław

    2014-06-01

    In this paper a new method of fault detection in rotating machinery is presented. It is based on a vibration time series analysis in time-frequency domain. A raw vibration signal is decomposed via the short-time Fourier transform (STFT). The time-frequency map is considered as matrix (M×N) with N sub-signals with length M. Each sub-signal is considered as a time series and might be interpreted as energy variation for narrow frequency bins. Each sub-signal is processed using a novel approach called the local maxima method. Basically, we search for local maxima because they should appear in the signal if local damage in bearings or gearbox exists. Finally, information for all sub-signals is combined in order to validate impulsive behavior of energy. Due to random character of the obtained time series, each maximum occurrence has to be checked for its significance. If there are time points for which the average number of local maxima for all sub-signals is significantly higher than for the other time instances, then location of these maxima is “weighted” as more important (at this time instance local maxima create for a set of Δf a pattern on the time-frequency map). This information, called vector of weights, is used for enhancement of spectrogram. When vector of weights is applied for spectrogram, non-informative energy is suppressed while informative features on spectrogram are enhanced. If the distribution of local maxima on spectrogram creates a pattern of wide-band cyclic energy growth, the machine is suspected of being damaged. For healthy condition, the vector of the average number of maxima for each time point should not have outliers, aggregation of information from all sub-signals is rather random and does not create any pattern. The method is illustrated by analysis of very noisy both real and simulated signals.

  9. Novel approach for talc pleurodesis by dedicated catheter through flexi-rigid thoracoscope under local anesthesia.

    PubMed

    Ishida, Atsuko; Nakamura, Miho; Miyazawa, Teruomi; Astoul, Philippe

    2011-05-01

    For pleurodesis, talc administered by poudrage is usually insufflated blindly from a single port of entry using the standard method with a small-diameter rigid thoracoscope. In order to visually perform talc poudrage from a single port, we introduced a catheter technique through a flexi-rigid thoracoscope. Patients with uncontrolled and symptomatic pleural effusion requiring pleurodesis underwent flexi-rigid thoracoscopy under local anesthesia for talc poudrage. A dedicated catheter with 2.1-mm inner diameter was connected to a talc atomizer and inserted through the working channel of the flexi-rigid thoracoscope to insufflate talc into the pleural cavity under visualization. Nine patients were included in this study. Three patients were >75 years old, and two were Karnofsky performance status 50. Three patients received propofol for sedation and six were not sedated. Mean operative time was 30.8 min for all patients, and 21.3 min for cases without sedation. All procedures were performed easily under clear visualization with no major complications or catheter obstructions. This novel approach for talc pleurodesis using a catheter was well-tolerated and seems feasible for patients with uncontrolled pleural effusion. We consider this technique useful even for difficult cases, such as elderly patients or those with relatively low performance status.

  10. Typicality approach to the optical conductivity in thermal and many-body localized phases

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Herbrych, Jacek; Pollmann, Frank; Brenig, Wolfram

    2016-11-01

    We study the frequency dependence of the optical conductivity Reσ (ω ) of the Heisenberg spin-1/2 chain in the thermal and near the transition to the many-body localized phase induced by the strength of a random z -directed magnetic field. Using the method of dynamical quantum typicality, we calculate the real-time dynamics of the spin-current autocorrelation function and obtain the Fourier transform Reσ (ω ) for system sizes much larger than accessible to standard exact-diagonalization approaches. We find that the low-frequency behavior of Reσ (ω ) is well described by Reσ (ω ) ≈σdc+a |ω| α , with α ≈1 in a wide range within the thermal phase and close to the transition. We particularly detail the decrease of σdc in the thermal phase as a function of increasing disorder for strong exchange anisotropies. We further find that the temperature dependence of σdc is consistent with the existence of a mobility edge.

  11. The relative power of genome scans to detect local adaptation depends on sampling design and statistical method.

    PubMed

    Lotterhos, Katie E; Whitlock, Michael C

    2015-03-01

    Although genome scans have become a popular approach towards understanding the genetic basis of local adaptation, the field still does not have a firm grasp on how sampling design and demographic history affect the performance of genome scans on complex landscapes. To explore these issues, we compared 20 different sampling designs in equilibrium (i.e. island model and isolation by distance) and nonequilibrium (i.e. range expansion from one or two refugia) demographic histories in spatially heterogeneous environments. We simulated spatially complex landscapes, which allowed us to exploit local maxima and minima in the environment in 'pair' and 'transect' sampling strategies. We compared F(ST) outlier and genetic-environment association (GEA) methods for each of two approaches that control for population structure: with a covariance matrix or with latent factors. We show that while the relative power of two methods in the same category (F(ST) or GEA) depended largely on the number of individuals sampled, overall GEA tests had higher power in the island model and F(ST) had higher power under isolation by distance. In the refugia models, however, these methods varied in their power to detect local adaptation at weakly selected loci. At weakly selected loci, paired sampling designs had equal or higher power than transect or random designs to detect local adaptation. Our results can inform sampling designs for studies of local adaptation and have important implications for the interpretation of genome scans based on landscape data. © 2015 John Wiley & Sons Ltd.

  12. Small-tip-angle spokes pulse design using interleaved greedy and local optimization methods.

    PubMed

    Grissom, William A; Khalighi, Mohammad-Mehdi; Sacolick, Laura I; Rutt, Brian K; Vogel, Mika W

    2012-11-01

    Current spokes pulse design methods can be grouped into methods based either on sparse approximation or on iterative local (gradient descent-based) optimization of the transverse-plane spatial frequency locations visited by the spokes. These two classes of methods have complementary strengths and weaknesses: sparse approximation-based methods perform an efficient search over a large swath of candidate spatial frequency locations but most are incompatible with off-resonance compensation, multifrequency designs, and target phase relaxation, while local methods can accommodate off-resonance and target phase relaxation but are sensitive to initialization and suboptimal local cost function minima. This article introduces a method that interleaves local iterations, which optimize the radiofrequency pulses, target phase patterns, and spatial frequency locations, with a greedy method to choose new locations. Simulations and experiments at 3 and 7 T show that the method consistently produces single- and multifrequency spokes pulses with lower flip angle inhomogeneity compared to current methods.

  13. A Multi-Modal Face Recognition Method Using Complete Local Derivative Patterns and Depth Maps

    PubMed Central

    Yin, Shouyi; Dai, Xu; Ouyang, Peng; Liu, Leibo; Wei, Shaojun

    2014-01-01

    In this paper, we propose a multi-modal 2D + 3D face recognition method for a smart city application based on a Wireless Sensor Network (WSN) and various kinds of sensors. Depth maps are exploited for the 3D face representation. As for feature extraction, we propose a new feature called Complete Local Derivative Pattern (CLDP). It adopts the idea of layering and has four layers. In the whole system, we apply CLDP separately on Gabor features extracted from a 2D image and depth map. Then, we obtain two features: CLDP-Gabor and CLDP-Depth. The two features weighted by the corresponding coefficients are combined together in the decision level to compute the total classification distance. At last, the probe face is assigned the identity with the smallest classification distance. Extensive experiments are conducted on three different databases. The results demonstrate the robustness and superiority of the new approach. The experimental results also prove that the proposed multi-modal 2D + 3D method is superior to other multi-modal ones and CLDP performs better than other Local Binary Pattern (LBP) based features. PMID:25333290

  14. A multi-modal face recognition method using complete local derivative patterns and depth maps.

    PubMed

    Yin, Shouyi; Dai, Xu; Ouyang, Peng; Liu, Leibo; Wei, Shaojun

    2014-10-20

    In this paper, we propose a multi-modal 2D + 3D face recognition method for a smart city application based on a Wireless Sensor Network (WSN) and various kinds of sensors. Depth maps are exploited for the 3D face representation. As for feature extraction, we propose a new feature called Complete Local Derivative Pattern (CLDP). It adopts the idea of layering and has four layers. In the whole system, we apply CLDP separately on Gabor features extracted from a 2D image and depth map. Then, we obtain two features: CLDP-Gabor and CLDP-Depth. The two features weighted by the corresponding coefficients are combined together in the decision level to compute the total classification distance. At last, the probe face is assigned the identity with the smallest classification distance. Extensive experiments are conducted on three different databases. The results demonstrate the robustness and superiority of the new approach. The experimental results also prove that the proposed multi-modal 2D + 3D method is superior to other multi-modal ones and CLDP performs better than other Local Binary Pattern (LBP) based features.

  15. Approach-Method Interaction: The role of teaching method on the effect of context-based approach in physics instruction

    NASA Astrophysics Data System (ADS)

    Peşman, Haki; Faruk Özdemir, Ömer

    2012-09-01

    The purpose of this study is to explore not only the effect of context-based physics instruction on students' achievement and motivation in physics, but also how the use of different teaching methods influences it (interaction effect). Therefore, two two-level-independent variables were defined, teaching approach (contextual and non-contextual approaches) and teaching method (traditional and learning cycle methods). Thus, a 2 × 2 factorial design was performed with four treatment groups, including 131 11th-grade students: (1) a traditional method with the non-contextual approach group, (2) a traditional method with the contextual approach group, (3) a learning cycle with the non-contextual approach group, and (4) a learning cycle with the contextual approach group. Prior to and just after the treatments, which took 5 weeks, pre-tests and post-tests on student achievement and motivation were administered. For the analysis of data, multivariate analysis of covariance, simple regressions and follow-up analysis of covariances were performed. Consequently, it was found that the effect of context-based approach on physics achievement is dependent upon the teaching method implemented. That is, the traditional method was observed to increase the effect of the contextual approach while the learning cycle decreased it. Related to the effects on motivation in physics, no evidence was found to claim a significant difference. Based on the findings of this study, further research is suggested for determining which teaching methods are more effective with the context-based approach on students' achievement and motivation in physics.

  16. Orthogonal grid generation of an irregular region using a local polynomial collocation method

    NASA Astrophysics Data System (ADS)

    Wu, Nan-Jing; Tsay, Ting-Kuei; Yang, Tun-Chi; Chang, Hung-Yuan

    2013-06-01

    In this study, a 2-D orthogonal grid generation model is developed by solving the governing equations of coordinate transformation with a local polynomial collocation method accompanied with the moving least squares (MLS) approach. This method was developed in a way that on the boundaries both the governing equation and boundary condition are satisfied, so it is more robust and accurate than conventional collocation methods. Though the method used to solve the coordinate transforming equations is meshless, it does not deteriorate the value of present work, because most numerical models in modern use are grid-dependent, and grid generation of service to these models is still strongly desired, particularly for finite difference models in irregular domains. Before applying to grid generation problems, the performance of present method is tested by a bench mark potential flow problem. Additional to two basic grid generation problems, a bottleneck problem of previous works, which contains zero-degree corners in the domain, is carried out. Finally, the model is applied to the orthogonal grid generation in a multi-connected domain. The correctness is testified by checking the orthogonality of the generated results.

  17. Practical approaches for assessing local land use change and conservation priorities in the tropics

    NASA Astrophysics Data System (ADS)

    Rivas, Cassandra J.

    Tropical areas typically support high biological diversity; however, many are experiencing rapid land-use change. The resulting loss, fragmentation, and degradation of habitats place biodiversity at risk. For these reasons, the tropics are frequently identified as global conservation hotspots. Safeguarding tropical biodiversity necessitates successful and efficient conservation planning and implementation at local scales, where land use decisions are made and enforced. Yet, despite considerable agreement on the need for improved practices, planning may be difficult due to limited resources, such as funding, data, and expertise, especially for small conservation organizations in tropical developing countries. My thesis aims to assist small, non-governmental organizations (NGOs), operating in tropical developing countries, in overcoming resource limitations by providing recommendations for improved conservation planning. Following a brief introduction in Chapter 1, I present a literature review of systematic conservation planning (SCP) projects in the developing tropics. Although SCP is considered an efficient, effective approach, it requires substantial data and expertise to conduct the analysis and may present challenges for implementation. I reviewed and synthesized the methods and results of 14 case studies to identify practical ways to implement and overcome limitations for employing SCP. I found that SCP studies in the peer-reviewed literature were primarily implemented by researchers in large organizations or institutions, as opposed to on-the-ground conservation planners. A variety of data types were used in the SCP analyses, many of which data are freely available. Few case studies involved stakeholders and intended to implement the assessment; instead, the case studies were carried out in the context of research and development, limiting local involvement and implementation. Nonetheless, the studies provided valuable strategies for employing each step of

  18. MEG source localization of spatially extended generators of epileptic activity: comparing entropic and hierarchical bayesian approaches.

    PubMed

    Chowdhury, Rasheda Arman; Lina, Jean Marc; Kobayashi, Eliane; Grova, Christophe

    2013-01-01

    Localizing the generators of epileptic activity in the brain using Electro-EncephaloGraphy (EEG) or Magneto-EncephaloGraphy (MEG) signals is of particular interest during the pre-surgical investigation of epilepsy. Epileptic discharges can be detectable from background brain activity, provided they are associated with spatially extended generators. Using realistic simulations of epileptic activity, this study evaluates the ability of distributed source localization methods to accurately estimate the location of the generators and their sensitivity to the spatial extent of such generators when using MEG data. Source localization methods based on two types of realistic models have been investigated: (i) brain activity may be modeled using cortical parcels and (ii) brain activity is assumed to be locally smooth within each parcel. A Data Driven Parcellization (DDP) method was used to segment the cortical surface into non-overlapping parcels and diffusion-based spatial priors were used to model local spatial smoothness within parcels. These models were implemented within the Maximum Entropy on the Mean (MEM) and the Hierarchical Bayesian (HB) source localization frameworks. We proposed new methods in this context and compared them with other standard ones using Monte Carlo simulations of realistic MEG data involving sources of several spatial extents and depths. Detection accuracy of each method was quantified using Receiver Operating Characteristic (ROC) analysis and localization error metrics. Our results showed that methods implemented within the MEM framework were sensitive to all spatial extents of the sources ranging from 3 cm(2) to 30 cm(2), whatever were the number and size of the parcels defining the model. To reach a similar level of accuracy within the HB framework, a model using parcels larger than the size of the sources should be considered.

  19. MEG Source Localization of Spatially Extended Generators of Epileptic Activity: Comparing Entropic and Hierarchical Bayesian Approaches

    PubMed Central

    Chowdhury, Rasheda Arman; Lina, Jean Marc; Kobayashi, Eliane; Grova, Christophe

    2013-01-01

    Localizing the generators of epileptic activity in the brain using Electro-EncephaloGraphy (EEG) or Magneto-EncephaloGraphy (MEG) signals is of particular interest during the pre-surgical investigation of epilepsy. Epileptic discharges can be detectable from background brain activity, provided they are associated with spatially extended generators. Using realistic simulations of epileptic activity, this study evaluates the ability of distributed source localization methods to accurately estimate the location of the generators and their sensitivity to the spatial extent of such generators when using MEG data. Source localization methods based on two types of realistic models have been investigated: (i) brain activity may be modeled using cortical parcels and (ii) brain activity is assumed to be locally smooth within each parcel. A Data Driven Parcellization (DDP) method was used to segment the cortical surface into non-overlapping parcels and diffusion-based spatial priors were used to model local spatial smoothness within parcels. These models were implemented within the Maximum Entropy on the Mean (MEM) and the Hierarchical Bayesian (HB) source localization frameworks. We proposed new methods in this context and compared them with other standard ones using Monte Carlo simulations of realistic MEG data involving sources of several spatial extents and depths. Detection accuracy of each method was quantified using Receiver Operating Characteristic (ROC) analysis and localization error metrics. Our results showed that methods implemented within the MEM framework were sensitive to all spatial extents of the sources ranging from 3 cm2 to 30 cm2, whatever were the number and size of the parcels defining the model. To reach a similar level of accuracy within the HB framework, a model using parcels larger than the size of the sources should be considered. PMID:23418485

  20. New Methods for Large Scale Local and Global Optimization

    DTIC Science & Technology

    1994-07-08

    investigators together with Jorge Nocedal of Northwestern University was completed during this research period has been accepted for publication by...easier to implement for a particular application. We have written a paper based on this work with Jorge Nocedal . In addition we have developed and...Liu, D., and J. Nocedal , "On the behavior of Broyden’s class of quasi-Newton methods," SlAM Journal on Optimization 2, 1992, pp. 533-557. (2) R. H

  1. Novel methods of local anesthetic delivery in the perioperative and postoperative setting-potential for fibrin hydrogel delivery.

    PubMed

    Kearney, Laura; Whelan, Derek; O'Donnell, Brian D; Clover, Anthony J P

    2016-12-01

    The benefits of high-quality postoperative analgesia are well documented and include earlier mobilization, fewer respiratory and cardiovascular complications, and shorter hospital stay. Local anesthesia-based acute pain regimens are at worst equal to and at best superior to opiate-based regimens from the perspective of analgesia. A multimodal approach limiting opioids by combining with local anesthetics has additional beneficial effect on outcomes such as nausea and vomiting, pruritus, gastrointestinal function, respiratory complications, and neutrophil function. Wound catheters providing continuous infiltration of local anesthetics offer a rational approach to effective perioperative analgesia, but their use is limited by a short duration of action. There is an identified need for further methods to optimize longer-acting delivery of these agents. This article reviews current and evolving longer-acting techniques and their limitations with particular focus on the potential advantages of a fibrin hydrogel-based system. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Analysis on accuracy improvement of rotor-stator rubbing localization based on acoustic emission beamforming method.

    PubMed

    He, Tian; Xiao, Denghong; Pan, Qiang; Liu, Xiandong; Shan, Yingchun

    2014-01-01

    This paper attempts to introduce an improved acoustic emission (AE) beamforming method to localize rotor-stator rubbing fault in rotating machinery. To investigate the propagation characteristics of acoustic emission signals in casing shell plate of rotating machinery, the plate wave theory is used in a thin plate. A simulation is conducted and its result shows the localization accuracy of beamforming depends on multi-mode, dispersion, velocity and array dimension. In order to reduce the effect of propagation characteristics on the source localization, an AE signal pre-process method is introduced by combining plate wave theory and wavelet packet transform. And the revised localization velocity to reduce effect of array size is presented. The accuracy of rubbing localization based on beamforming and the improved method of present paper are compared by the rubbing test carried on a test table of rotating machinery. The results indicate that the improved method can localize rub fault effectively.

  3. How Nectar-Feeding Bats Localize their Food: Echolocation Behavior of Leptonycteris yerbabuenae Approaching Cactus Flowers

    PubMed Central

    Koblitz, Jens C.; Fleming, Theodore H.; Medellín, Rodrigo A.; Kalko, Elisabeth K. V.; Schnitzler, Hans-Ulrich; Tschapka, Marco

    2016-01-01

    Nectar-feeding bats show morphological, physiological, and behavioral adaptations for feeding on nectar. How they find and localize flowers is still poorly understood. While scent cues alone allow no precise localization of a floral target, the spatial properties of flower echoes are very precise and could play a major role, particularly at close range. The aim of this study is to understand the role of echolocation for classification and localization of flowers. We compared the approach behavior of Leptonycteris yerbabuenae to flowers of a columnar cactus, Pachycereus pringlei, to that to an acrylic hollow hemisphere that is acoustically conspicuous to bats, but has different acoustic properties and, contrary to the cactus flower, present no scent. For recording the flight and echolocation behaviour we used two infrared video cameras under stroboscopic illumination synchronized with ultrasound recordings. During search flights all individuals identified both targets as a possible food source and initiated an approach flight; however, they visited only the cactus flower. In experiments with the acrylic hemisphere bats aborted the approach at ca. 40–50 cm. In the last instant before the flower visit the bats emitted a long terminal group of 10–20 calls. This is the first report of this behaviour for a nectar-feeding bat. Our findings suggest that L. yerbabuenae use echolocation for classification and localization of cactus flowers and that the echo-acoustic characteristics of the flower guide the bats directly to the flower opening. PMID:27684373

  4. 3D handheld laser scanner based approach for automatic identification and localization of EEG sensors.

    PubMed

    Koessler, Laurent; Cecchin, Thierry; Ternisien, Eric; Maillard, Louis

    2010-01-01

    This paper describes and assesses for the first time the use of a handheld 3D laser scanner for scalp EEG sensor localization and co-registration with magnetic resonance images. Study on five subjects showed that the scanner had an equivalent accuracy, a better repeatability, and was faster than the reference electromagnetic digitizer. According to electrical source imaging, somatosensory evoked potentials experiments validated its ability to give precise sensor localization. With our automatic labeling method, the data provided by the scanner could be directly introduced in the source localization studies.

  5. Local treatment of electron excitations in the EOM-CCSD method

    NASA Astrophysics Data System (ADS)

    Korona, Tatiana; Werner, Hans-Joachim

    2003-02-01

    The Equation-of-Motion coupled cluster method restricted to single and double excitations (EOM-CCSD) and singlet excited states is formulated in a basis of nonorthogonal local orbitals. In the calculation of excited states only electron promotions from localized molecular orbitals into subspaces (excitation domains) of the local basis are allowed, which strongly reduces the number of EOM-CCSD amplitudes to be optimized. Furthermore, double excitations are neglected unless the excitation domains of the corresponding localized occupied orbitals are close to each other. Unlike in the local methods for the ground state, the excitation domains cannot be simply restricted to the atomic orbitals that are spatially close to the localized occupied orbitals. In the present paper the choice of the excitation domains is based on the analysis of wave functions computed by more approximate (and cheaper) methods like, e.g., configuration-interaction singles. The effect of various local approximations is investigated in detail, and it is found that a balanced description of the local configuration spaces describing the ground and excited states is essential to obtain accurate results. Using a single set of parameters for a given basis set, test calculations with the local EOM-CCSD method were performed for 14 molecules and 49 electronically excited states. The excitation energies computed by the local EOM-CCSD method reproduce the conventional EOM-CCSD excitation energies with an average error of 0.06 eV.

  6. Local search methods based on variable focusing for random K -satisfiability

    NASA Astrophysics Data System (ADS)

    Lemoy, Rémi; Alava, Mikko; Aurell, Erik

    2015-01-01

    We introduce variable focused local search algorithms for satisfiabiliity problems. Usual approaches focus uniformly on unsatisfied clauses. The methods described here work by focusing on random variables in unsatisfied clauses. Variants are considered where variables are selected uniformly and randomly or by introducing a bias towards picking variables participating in several unsatistified clauses. These are studied in the case of the random 3-SAT problem, together with an alternative energy definition, the number of variables in unsatisfied constraints. The variable-based focused Metropolis search (V-FMS) is found to be quite close in performance to the standard clause-based FMS at optimal noise. At infinite noise, instead, the threshold for the linearity of solution times with instance size is improved by picking preferably variables in several UNSAT clauses. Consequences for algorithmic design are discussed.

  7. Total System Performance Assessment - License Application Methods and Approach

    SciTech Connect

    J. McNeish

    2003-12-08

    ''Total System Performance Assessment-License Application (TSPA-LA) Methods and Approach'' provides the top-level method and approach for conducting the TSPA-LA model development and analyses. The method and approach is responsive to the criteria set forth in Total System Performance Assessment Integration (TSPAI) Key Technical Issues (KTIs) identified in agreements with the U.S. Nuclear Regulatory Commission, the ''Yucca Mountain Review Plan'' (YMRP), ''Final Report'' (NRC 2003 [163274]), and the NRC final rule 10 CFR Part 63 (NRC 2002 [156605]). This introductory section provides an overview of the TSPA-LA, the projected TSPA-LA documentation structure, and the goals of the document. It also provides a brief discussion of the regulatory framework, the approach to risk management of the development and analysis of the model, and the overall organization of the document. The section closes with some important conventions that are used in this document.

  8. Total System Performance Assessment-License Application Methods and Approach

    SciTech Connect

    J. McNeish

    2002-09-13

    ''Total System Performance Assessment-License Application (TSPA-LA) Methods and Approach'' provides the top-level method and approach for conducting the TSPA-LA model development and analyses. The method and approach is responsive to the criteria set forth in Total System Performance Assessment Integration (TSPAI) Key Technical Issue (KTI) agreements, the ''Yucca Mountain Review Plan'' (CNWRA 2002 [158449]), and 10 CFR Part 63. This introductory section provides an overview of the TSPA-LA, the projected TSPA-LA documentation structure, and the goals of the document. It also provides a brief discussion of the regulatory framework, the approach to risk management of the development and analysis of the model, and the overall organization of the document. The section closes with some important conventions that are utilized in this document.

  9. Efficient local-orbitals based method for ultrafast dynamics

    NASA Astrophysics Data System (ADS)

    Boleininger, Max; Horsfield, Andrew P.

    2017-07-01

    Computer simulations are invaluable for the study of ultrafast phenomena, as they allow us to directly access the electron dynamics. We present an efficient method for simulating the evolution of electrons in molecules under the influence of time-dependent electric fields, based on the Gaussian tight binding model. This model improves upon standard self-charge-consistent tight binding by the inclusion of polarizable orbitals and a self-consistent description of charge multipoles. Using the examples of bithiophene, terthiophene, and tetrathiophene, we show that this model produces electrostatic, electrodynamic, and explicitly time-dependent properties in strong agreement with density-functional theory, but at a small fraction of the cost.

  10. Domain decomposition methods in FVM approach to gravity field modelling.

    NASA Astrophysics Data System (ADS)

    Macák, Marek

    2017-04-01

    The finite volume method (FVM) as a numerical method can be straightforwardly implemented for global or local gravity field modelling. This discretization method solves the geodetic boundary value problems in a space domain. In order to obtain precise numerical solutions, it usually requires very refined discretization leading to large-scale parallel computations. To optimize such computations, we present a special class of numerical techniques that are based on a physical decomposition of the global solution domain. The domain decomposition (DD) methods like the Multiplicative Schwarz Method and Additive Schwarz Method are very efficient methods for solving partial differential equations. We briefly present their mathematical formulations and we test their efficiency. Presented numerical experiments are dealing with gravity field modelling. Since there is no need to solve special interface problems between neighbouring subdomains, in our applications we use the overlapping DD methods.

  11. Global/local methods research using a common structural analysis framework

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Ransom, Jonathan B.; Griffin, O. H., Jr.; Thompson, Danniella M.

    1991-01-01

    Methodologies for global/local stress analysis are described including both two- and three-dimensional analysis methods. These methods are being developed within a common structural analysis framework. Representative structural analysis problems are presented to demonstrate the global/local methodologies being developed.

  12. Global/local methods research using a common structural analysis framework

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Ransom, Jonathan B.; Griffin, O. H., Jr.; Thompson, Danniella M.

    1991-01-01

    Methodologies for global/local stress analysis are described including both two- and three-dimensional analysis methods. These methods are being developed within a common structural analysis framework. Representative structural analysis problems are presented to demonstrate the global/local methodologies being developed.

  13. A Local Discontinuous Galerkin Method for KdV-type Equations

    DTIC Science & Technology

    2001-06-01

    convection alone. This is a big advantage of the scheme over the traditional \\ mixed methods ", and it is the reason that the scheme is termed local...same order of accuracy, thus matching the advantage of traditional \\ mixed methods " on this. The purpose of this paper is to develop a similar local

  14. A novel approach to decoy set generation: designing a physical energy function having local minima with native structure characteristics.

    PubMed

    Keasar, Chen; Levitt, Michael

    2003-05-23

    We suggest a new approach to the generation of candidate structures (decoys) for ab initio prediction of protein structures. Our method is based on random sampling of conformation space and subsequent local energy minimization. At the core of this approach lies the design of a novel type of energy function. This energy function has local minima with native structure characteristics and wide basins of attraction. The current work presents our motivation for deriving such an energy function and also tests the derived energy function. Our approach is novel in that it takes advantage of the inherently rough energy landscape of proteins, which is generally considered a major obstacle for protein structure prediction. When local minima have wide basins of attraction, the protein's conformation space can be greatly reduced by the convergence of large regions of the space into single points, namely the local minima corresponding to these funnels. We have implemented this concept by an iterative process. The potential is first used to generate decoy sets and then we study these sets of decoys to guide further development of the potential. A key feature of our potential is the use of cooperative multi-body interactions that mimic the role of the entropic and solvent contributions to the free energy. The validity and value of our approach is demonstrated by applying it to 14 diverse, small proteins. We show that, for these proteins, the size of conformation space is considerably reduced by the new energy function. In fact, the reduction is so substantial as to allow efficient conformational sampling. As a result we are able to find a significant number of near-native conformations in random searches performed with limited computational resources.

  15. Potential energy surface fitting by a statistically localized, permutationally invariant, local interpolating moving least squares method for the many-body potential: Method and application to N{sub 4}

    SciTech Connect

    Bender, Jason D.; Doraiswamy, Sriram; Candler, Graham V. E-mail: candler@aem.umn.edu; Truhlar, Donald G. E-mail: candler@aem.umn.edu

    2014-02-07

    Fitting potential energy surfaces to analytic forms is an important first step for efficient molecular dynamics simulations. Here, we present an improved version of the local interpolating moving least squares method (L-IMLS) for such fitting. Our method has three key improvements. First, pairwise interactions are modeled separately from many-body interactions. Second, permutational invariance is incorporated in the basis functions, using permutationally invariant polynomials in Morse variables, and in the weight functions. Third, computational cost is reduced by statistical localization, in which we statistically correlate the cutoff radius with data point density. We motivate our discussion in this paper with a review of global and local least-squares-based fitting methods in one dimension. Then, we develop our method in six dimensions, and we note that it allows the analytic evaluation of gradients, a feature that is important for molecular dynamics. The approach, which we call statistically localized, permutationally invariant, local interpolating moving least squares fitting of the many-body potential (SL-PI-L-IMLS-MP, or, more simply, L-IMLS-G2), is used to fit a potential energy surface to an electronic structure dataset for N{sub 4}. We discuss its performance on the dataset and give directions for further research, including applications to trajectory calculations.

  16. Automated delineation and characterization of drumlins using a localized contour tree approach

    NASA Astrophysics Data System (ADS)

    Wang, Shujie; Wu, Qiusheng; Ward, Dylan

    2017-10-01

    Drumlins are ubiquitous landforms in previously glaciated regions, formed through a series of complex subglacial processes operating underneath the paleo-ice sheets. Accurate delineation and characterization of drumlins are essential for understanding the formation mechanism of drumlins as well as the flow behaviors and basal conditions of paleo-ice sheets. Automated mapping of drumlins is particularly important for examining the distribution patterns of drumlins across large spatial scales. This paper presents an automated vector-based approach to mapping drumlins from high-resolution light detection and ranging (LiDAR) data. The rationale is to extract a set of concentric contours by building localized contour trees and establishing topological relationships. This automated method can overcome the shortcomings of previously manual and automated methods for mapping drumlins, for instance, the azimuthal biases during the generation of shaded relief images. A case study was carried out over a portion of the New York Drumlin Field. Overall 1181 drumlins were identified from the LiDAR-derived DEM across the study region, which had been underestimated in previous literature. The delineation results were visually and statistically compared to the manual digitization results. The morphology of drumlins was characterized by quantifying the length, width, elongation ratio, height, area, and volume. Statistical and spatial analyses were conducted to examine the distribution pattern and spatial variability of drumlin size and form. The drumlins and the morphologic characteristics exhibit significant spatial clustering rather than randomly distributed patterns. The form of drumlins varies from ovoid to spindle shapes towards the downstream direction of paleo ice flows, along with the decrease in width, area, and volume. This observation is in line with previous studies, which may be explained by the variations in sediment thickness and/or the velocity increases of ice flows

  17. Lagrangian Particle Method for Local Scale Dispersion Modeling

    NASA Astrophysics Data System (ADS)

    Sunarko; ZakiSu'ud

    2016-08-01

    A deterministic model is developed for radioactive dispersion analysis based on random-walk Lagrangian Particle Dispersion Method (LPDM). A diagnostic 3dimensional mass-consistent wind-field with a capability to handle complex topography can be used to provide input for particle advection. Turbulent diffusion process of particles is determined based on empirical lateral and linear vertical relationships. Surface-level concentration is calculated for constant unit release from elevated point source. A series of 60-second segmented groups of particles are released in 3600 seconds total duration. Averaged surface-level concentration within a 5 meter surface layer is obtained and compared with available analytical solution. Results from LPDM shows good agreement with the analytical result for vertically constant and varying wind field with the same atmospheric stability.

  18. Exploration of barriers and facilitators to publishing local public health findings: A mixed methods protocol

    PubMed Central

    Smith, Selina A.; Webb, Nancy C.; Blumenthal, Daniel S.; Willcox, Bobbie; Ballance, Darra; Kinard, Faith; Gates, Madison L.

    2016-01-01

    Background Worldwide, the US accounts for a large proportion of journals related to public health. Although the American Public Health Association (APHA) includes 54 affiliated regional and state associations, little is known about their capacity to support public health scholarship. The aim of this study is to assess barriers and facilitators to operation of state journals for the dissemination of local public health research and practices. Methods A mixed methods approach will be used to complete the 12-month study. Affiliate websites will be accessed through the APHA membership portal to evaluate organizational infrastructure and ascertain the presence/absence of a journal. The leader of each affiliate will be contacted via email containing a link to a 12-question on-line survey to collect his/her perceptions of scholarly journals and the publication of local health data. To determine barriers and facilitators to publication of local public health findings, 30-minute semi-structured telephone interviews will focus on the infrastructure of the association, perceptions of the leader about the journal (if in place), and its operation. Anticipated Results We anticipate that 54 affiliate websites will be reviewed to complete the extraction checklist, that 74% of affiliate leaders will respond to the survey, and that 11 semi-structured interviews will be conducted. A limited number of state/regional public health associations will operate journals and a small percentage of those without journals may express an interest in implementing them. Barriers to operation of journals may include lack of resources (i.e., personnel, funding), and low prioritization of publication of state and local public health findings. Facilitators may include strong affiliate-academic relationships, affiliate leadership with experience in publications, and affiliate relationships with state and local departments of health. Conclusions The research proposed in this protocol may stimulate other

  19. A field theoretical approach to the quasi-continuum method

    NASA Astrophysics Data System (ADS)

    Iyer, Mrinal; Gavini, Vikram

    2011-08-01

    The quasi-continuum method has provided many insights into the behavior of lattice defects in the past decade. However, recent numerical analysis suggests that the approximations introduced in various formulations of the quasi-continuum method lead to inconsistencies—namely, appearance of ghost forces or residual forces, non-conservative nature of approximate forces, etc.—which affect the numerical accuracy and stability of the method. In this work, we identify the source of these errors to be the incompatibility of using quadrature rules, which is a local notion, on a non-local representation of energy. We eliminate these errors by first reformulating the extended interatomic interactions into a local variational problem that describes the energy of a system via potential fields. We subsequently introduce the quasi-continuum reduction of these potential fields using an adaptive finite-element discretization of the formulation. We demonstrate that the present formulation resolves the inconsistencies present in previous formulations of the quasi-continuum method, and show using numerical examples the remarkable improvement in the accuracy of solutions. Further, this field theoretic formulation of quasi-continuum method makes mathematical analysis of the method more amenable using functional analysis and homogenization theories.

  20. Localizing true brain interactions from EEG and MEG data with subspace methods and modified beamformers.

    PubMed

    Shahbazi Avarvand, Forooz; Ewald, Arne; Nolte, Guido

    2012-01-01

    To address the problem of mixing in EEG or MEG connectivity analysis we exploit that noninteracting brain sources do not contribute systematically to the imaginary part of the cross-spectrum. Firstly, we propose to apply the existing subspace method "RAP-MUSIC" to the subspace found from the dominant singular vectors of the imaginary part of the cross-spectrum rather than to the conventionally used covariance matrix. Secondly, to estimate the specific sources interacting with each other, we use a modified LCMV-beamformer approach in which the source direction for each voxel was determined by maximizing the imaginary coherence with respect to a given reference. These two methods are applicable in this form only if the number of interacting sources is even, because odd-dimensional subspaces collapse to even-dimensional ones. Simulations show that (a) RAP-MUSIC based on the imaginary part of the cross-spectrum accurately finds the correct source locations, that (b) conventional RAP-MUSIC fails to do so since it is highly influenced by noninteracting sources, and that (c) the second method correctly identifies those sources which are interacting with the reference. The methods are also applied to real data for a motor paradigm, resulting in the localization of four interacting sources presumably in sensory-motor areas.

  1. Mixed meshless local Petrov-Galerkin collocation method for modeling of material discontinuity

    NASA Astrophysics Data System (ADS)

    Jalušić, Boris; Sorić, Jurica; Jarak, Tomislav

    2017-01-01

    A mixed meshless local Petrov-Galerkin (MLPG) collocation method is proposed for solving the two-dimensional boundary value problem of heterogeneous structures. The heterogeneous structures are defined by partitioning the total material domain into subdomains with different linear-elastic isotropic properties which define homogeneous materials. The discretization and approximation of unknown field variables is done for each homogeneous material independently, therein the interface of the homogeneous materials is discretized with overlapping nodes. For the approximation, the moving least square method with the imposed interpolation condition is utilized. The solution for the entire heterogeneous structure is obtained by enforcing displacement continuity and traction reciprocity conditions at the nodes representing the interface boundary. The accuracy and numerical efficiency of the proposed mixed MLPG collocation method is demonstrated by numerical examples. The obtained results are compared with a standard fully displacement (primal) meshless approach as well as with available analytical and numerical solutions. Excellent agreement of the solutions is exhibited and a more robust, superior and stable modeling of material discontinuity is achieved using the mixed method.

  2. A Novel Partial Discharge Localization Method in Substation Based on a Wireless UHF Sensor Array

    PubMed Central

    Li, Zhen; Luo, Lingen; Zhou, Nan; Sheng, Gehao; Jiang, Xiuchen

    2017-01-01

    Effective Partial Discharge (PD) localization can detect the insulation problems of the power equipment in a substation and improve the reliability of power systems. Typical Ultra-High Frequency (UHF) PD localization methods are mainly based on time difference information, which need a high sampling rate system. This paper proposes a novel PD localization method based on a received signal strength indicator (RSSI) fingerprint to quickly locate the power equipment with potential insulation defects. The proposed method consists of two stages. In the offline stage, the RSSI fingerprint data of the detection area is measured by a wireless UHF sensor array and processed by a clustering algorithm to reduce the PD interference and abnormal RSSI values. In the online stage, when PD happens, the RSSI fingerprint of PD is measured via the input of pattern recognition for PD localization. To achieve an accurate localization, the pattern recognition process is divided into two steps: a preliminary localization is implemented by cluster recognition to reduce the localization region, and the compressed sensing algorithm is used for accurate PD localization. A field test in a substation indicates that the mean localization error of the proposed method is 1.25 m, and 89.6% localization errors are less than 3 m. PMID:28820444

  3. A Novel Partial Discharge Localization Method in Substation Based on a Wireless UHF Sensor Array.

    PubMed

    Li, Zhen; Luo, Lingen; Zhou, Nan; Sheng, Gehao; Jiang, Xiuchen

    2017-08-18

    Effective Partial Discharge (PD) localization can detect the insulation problems of the power equipment in a substation and improve the reliability of power systems. Typical Ultra-High Frequency (UHF) PD localization methods are mainly based on time difference information, which need a high sampling rate system. This paper proposes a novel PD localization method based on a received signal strength indicator (RSSI) fingerprint to quickly locate the power equipment with potential insulation defects. The proposed method consists of two stages. In the offline stage, the RSSI fingerprint data of the detection area is measured by a wireless UHF sensor array and processed by a clustering algorithm to reduce the PD interference and abnormal RSSI values. In the online stage, when PD happens, the RSSI fingerprint of PD is measured via the input of pattern recognition for PD localization. To achieve an accurate localization, the pattern recognition process is divided into two steps: a preliminary localization is implemented by cluster recognition to reduce the localization region, and the compressed sensing algorithm is used for accurate PD localization. A field test in a substation indicates that the mean localization error of the proposed method is 1.25 m, and 89.6% localization errors are less than 3 m.

  4. Percutaneous Irreversible Electroporation of Locally Advanced Pancreatic Carcinoma Using the Dorsal Approach: A Case Report

    SciTech Connect

    Scheffer, Hester J. Melenhorst, Marleen C. A. M.; Vogel, Jantien A.; Tilborg, Aukje A. J. M. van; Nielsen, Karin Kazemier, Geert; Meijerink, Martijn R.

    2015-06-15

    Irreversible electroporation (IRE) is a novel image-guided ablation technique that is increasingly used to treat locally advanced pancreatic carcinoma (LAPC). We describe a 67-year-old male patient with a 5 cm stage III pancreatic tumor who was referred for IRE. Because the ventral approach for electrode placement was considered dangerous due to vicinity of the tumor to collateral vessels and duodenum, the dorsal approach was chosen. Under CT-guidance, six electrodes were advanced in the tumor, approaching paravertebrally alongside the aorta and inferior vena cava. Ablation was performed without complications. This case describes that when ventral electrode placement for pancreatic IRE is impaired, the dorsal approach could be considered alternatively.

  5. A Cross-Layer User Centric Vertical Handover Decision Approach Based on MIH Local Triggers

    NASA Astrophysics Data System (ADS)

    Rehan, Maaz; Yousaf, Muhammad; Qayyum, Amir; Malik, Shahzad

    Vertical handover decision algorithm that is based on user preferences and coupled with Media Independent Handover (MIH) local triggers have not been explored much in the literature. We have developed a comprehensive cross-layer solution, called Vertical Handover Decision (VHOD) approach, which consists of three parts viz. mechanism for collecting and storing user preferences, Vertical Handover Decision (VHOD) algorithm and the MIH Function (MIHF). MIHF triggers the VHOD algorithm which operates on user preferences to issue handover commands to mobility management protocol. VHOD algorithm is an MIH User and therefore needs to subscribe events and configure thresholds for receiving triggers from MIHF. In this regard, we have performed experiments in WLAN to suggest thresholds for Link Going Down trigger. We have also critically evaluated the handover decision process, proposed Just-in-time interface activation technique, compared our proposed approach with prominent user centric approaches and analyzed our approach from different aspects.

  6. A Novel Method of Localization for Moving Objects with an Alternating Magnetic Field.

    PubMed

    Gao, Xiang; Yan, Shenggang; Li, Bin

    2017-04-21

    Magnetic detection technology has wide applications in the fields of geological exploration, biomedical treatment, wreck removal and localization of unexploded ordinance. A large number of methods have been developed to locate targets with static magnetic fields, however, the relation between the problem of localization of moving objectives with alternating magnetic fields and the localization with a static magnetic field is rarely studied. A novel method of target localization based on coherent demodulation was proposed in this paper. The problem of localization of moving objects with an alternating magnetic field was transformed into the localization with a static magnetic field. The Levenberg-Marquardt (L-M) algorithm was applied to calculate the position of the target with magnetic field data measured by a single three-component magnetic sensor. Theoretical simulation and experimental results demonstrate the effectiveness of the proposed method.

  7. A Novel Method of Localization for Moving Objects with an Alternating Magnetic Field

    PubMed Central

    Gao, Xiang; Yan, Shenggang; Li, Bin

    2017-01-01

    Magnetic detection technology has wide applications in the fields of geological exploration, biomedical treatment, wreck removal and localization of unexploded ordinance. A large number of methods have been developed to locate targets with static magnetic fields, however, the relation between the problem of localization of moving objectives with alternating magnetic fields and the localization with a static magnetic field is rarely studied. A novel method of target localization based on coherent demodulation was proposed in this paper. The problem of localization of moving objects with an alternating magnetic field was transformed into the localization with a static magnetic field. The Levenberg-Marquardt (L-M) algorithm was applied to calculate the position of the target with magnetic field data measured by a single three-component magnetic sensor. Theoretical simulation and experimental results demonstrate the effectiveness of the proposed method. PMID:28430153

  8. A RF time domain approach for electric arcs detection and localization systems

    NASA Astrophysics Data System (ADS)

    Deacu, Daniela; Tamas, Razvan; Petrescu, Teodor; Paun, Mirel; Anchidin, Liliana; Algiu, Madalina

    2016-12-01

    In this paper we propose a new method for detection and localization of electric arcs by using two ultra-wide band (UWB) antennas together with data processing in the time-domain. The source of electric arcs is localized by computing an average on the inter-correlation functions of the signals received on two channels. By calculating the path length difference to the antennas, the direction of the electric arcs is then found. The novelty of the method consists in the spatial averaging in order to reduce the incertitude caused by the finite sampling rate.

  9. Localized dynamic light scattering: a new approach to dynamic measurements in optical microscopy.

    PubMed

    Meller, A; Bar-Ziv, R; Tlusty, T; Moses, E; Stavans, J; Safran, S A

    1998-03-01

    We present a new approach to probing single-particle dynamics that uses dynamic light scattering from a localized region. By scattering a focused laser beam from a micron-size particle, we measure its spatial fluctuations via the temporal autocorrelation of the scattered intensity. We demonstrate the applicability of this approach by measuring the three-dimensional force constants of a single bead and a pair of beads trapped by laser tweezers. The scattering equations that relate the scattered intensity autocorrelation to the particle position correlation function are derived. This technique has potential applications for measurement of biomolecular force constants and probing viscoelastic properties of complex media.

  10. Multidimensional Programming Methods for Energy Facility Siting: Alternative Approaches

    NASA Technical Reports Server (NTRS)

    Solomon, B. D.; Haynes, K. E.

    1982-01-01

    The use of multidimensional optimization methods in solving power plant siting problems, which are characterized by several conflicting, noncommensurable objectives is addressed. After a discussion of data requirements and exclusionary site screening methods for bounding the decision space, classes of multiobjective and goal programming models are discussed in the context of finite site selection. Advantages and limitations of these approaches are highlighted and the linkage of multidimensional methods with the subjective, behavioral components of the power plant siting process is emphasized.

  11. A transfer matrix approach to vibration localization in mistuned blade assemblies

    NASA Technical Reports Server (NTRS)

    Ottarson, Gisli; Pierre, Chritophe

    1993-01-01

    A study of mode localization in mistuned bladed disks is performed using transfer matrices. The transfer matrix approach yields the free response of a general, mono-coupled, perfectly cyclic assembly in closed form. A mistuned structure is represented by random transfer matrices, and the expansion of these matrices in terms of the small mistuning parameter leads to the definition of a measure of sensitivity to mistuning. An approximation of the localization factor, the spatially averaged rate of exponential attenuation per blade-disk sector, is obtained through perturbation techniques in the limits of high and low sensitivity. The methodology is applied to a common model of a bladed disk and the results verified by Monte Carlo simulations. The easily calculated sensitivity measure may prove to be a valuable design tool due to its system-independent quantification of mistuning effects such as mode localization.

  12. Flow equation approach to one-body and many-body localization

    NASA Astrophysics Data System (ADS)

    Quito, Victor; Bhattacharjee, Paraj; Pekker, David; Refael, Gil

    2014-03-01

    We study one-body and many-body localization using the flow equation technique applied to spin-1/2 Hamiltonians. This technique, first introduced by Wegner, allows us to exact diagonalize interacting systems by solving a set of first-order differential equations for coupling constants. Besides, by the flow of individual operators we also compute physical properties, such as correlation and localization lengths, by looking at the flow of probability distributions of couplings in the Hilbert space. As a first example, we analyze the one-body localization problem written in terms of spins, the disordered XY model with a random transverse field. We compare the results obtained in the flow equation approach with the diagonalization in the fermionic language. For the many-body problem, we investigate the physical properties of the disordered XXZ Hamiltonian with a random transverse field in the z-direction.

  13. The Local Integrity Approach for Urban Contexts: Definition and Vehicular Experimental Assessment

    PubMed Central

    Margaria, Davide; Falletti, Emanuela

    2016-01-01

    A novel cooperative integrity monitoring concept, called “local integrity”, suitable to automotive applications in urban scenarios, is discussed in this paper. The idea is to take advantage of a collaborative Vehicular Ad hoc NETwork (VANET) architecture in order to perform a spatial/temporal characterization of possible degradations of Global Navigation Satellite System (GNSS) signals. Such characterization enables the computation of the so-called “Local Protection Levels”, taking into account local impairments to the received signals. Starting from theoretical concepts, this paper describes the experimental validation by means of a measurement campaign and the real-time implementation of the algorithm on a vehicular prototype. A live demonstration in a real scenario has been successfully carried out, highlighting effectiveness and performance of the proposed approach. PMID:26821028

  14. The Local Integrity Approach for Urban Contexts: Definition and Vehicular Experimental Assessment.

    PubMed

    Margaria, Davide; Falletti, Emanuela

    2016-01-26

    A novel cooperative integrity monitoring concept, called "local integrity", suitable to automotive applications in urban scenarios, is discussed in this paper. The idea is to take advantage of a collaborative Vehicular Ad hoc NETwork (VANET) architecture in order to perform a spatial/temporal characterization of possible degradations of Global Navigation Satellite System (GNSS) signals. Such characterization enables the computation of the so-called "Local Protection Levels", taking into account local impairments to the received signals. Starting from theoretical concepts, this paper describes the experimental validation by means of a measurement campaign and the real-time implementation of the algorithm on a vehicular prototype. A live demonstration in a real scenario has been successfully carried out, highlighting effectiveness and performance of the proposed approach.

  15. Experiences of using a participatory action research approach to strengthen district local capacity in Eastern Uganda.

    PubMed

    Tetui, Moses; Coe, Anna-Britt; Hurtig, Anna-Karin; Ekirapa-Kiracho, Elizabeth; Kiwanuka, Suzanne N

    2017-08-01

    To achieve a sustained improvement in health outcomes, the way health interventions are designed and implemented is critical. A participatory action research approach is applauded for building local capacity such as health management. Thereby increasing the chances of sustaining health interventions. This study explored stakeholder experiences of using PAR to implement an intervention meant to strengthen the local district capacity. This was a qualitative study featuring 18 informant interviews and a focus group discussion. Respondents included politicians, administrators, health managers and external researchers in three rural districts of eastern Uganda where PAR was used. Qualitative content analysis was used to explore stakeholders' experiences. 'Being awakened' emerged as an overarching category capturing stakeholder experiences of using PAR. This was described in four interrelated and sequential categories, which included: stakeholder involvement, being invigorated, the risk of wide stakeholder engagement and balancing the risk of wide stakeholder engagement. In terms of involvement, the stakeholders felt engaged, a sense of ownership, felt valued and responsible during the implementation of the project. Being invigorated meant being awakened, inspired and supported. On the other hand, risks such as conflict, stress and uncertainty were reported, and finally these risks were balanced through tolerance, risk-awareness and collaboration. The PAR approach was desirable because it created opportunities for building local capacity and enhancing continuity of interventions. Stakeholders were awakened by the approach, as it made them more responsive to systems challenges and possible local solutions. Nonetheless, the use of PAR should be considered in full knowledge of the undesirable and complex experiences, such as uncertainty, conflict and stress. This will enable adequate preparation and management of stakeholder expectations to maximize the benefits of the

  16. Explaining Andean Potato Weevils in Relation to Local and Landscape Features: A Facilitated Ecoinformatics Approach

    PubMed Central

    Parsa, Soroush; Ccanto, Raúl; Olivera, Edgar; Scurrah, María; Alcázar, Jesús; Rosenheim, Jay A.

    2012-01-01

    Background Pest impact on an agricultural field is jointly influenced by local and landscape features. Rarely, however, are these features studied together. The present study applies a “facilitated ecoinformatics” approach to jointly screen many local and landscape features of suspected importance to Andean potato weevils (Premnotrypes spp.), the most serious pests of potatoes in the high Andes. Methodology/Principal Findings We generated a comprehensive list of predictors of weevil damage, including both local and landscape features deemed important by farmers and researchers. To test their importance, we assembled an observational dataset measuring these features across 138 randomly-selected potato fields in Huancavelica, Peru. Data for local features were generated primarily by participating farmers who were trained to maintain records of their management operations. An information theoretic approach to modeling the data resulted in 131,071 models, the best of which explained 40.2–46.4% of the observed variance in infestations. The best model considering both local and landscape features strongly outperformed the best models considering them in isolation. Multi-model inferences confirmed many, but not all of the expected patterns, and suggested gaps in local knowledge for Andean potato weevils. The most important predictors were the field's perimeter-to-area ratio, the number of nearby potato storage units, the amount of potatoes planted in close proximity to the field, and the number of insecticide treatments made early in the season. Conclusions/Significance Results underscored the need to refine the timing of insecticide applications and to explore adjustments in potato hilling as potential control tactics for Andean weevils. We believe our study illustrates the potential of ecoinformatics research to help streamline IPM learning in agricultural learning collaboratives. PMID:22693551

  17. Deep Voting: A Robust Approach Toward Nucleus Localization in Microscopy Images.

    PubMed

    Xie, Yuanpu; Kong, Xiangfei; Xing, Fuyong; Liu, Fujun; Su, Hai; Yang, Lin

    2015-10-01

    Robust and accurate nuclei localization in microscopy image can provide crucial clues for accurate computer-aid diagnosis. In this paper, we propose a convolutional neural network (CNN) based hough voting method to localize nucleus centroids with heavy cluttering and morphologic variations in microscopy images. Our method, which we name as deep voting, mainly consists of two steps. (1) Given an input image, our method assigns each local patch several pairs of voting offset vectors which indicate the positions it votes to, and the corresponding voting confidence (used to weight each votes), our model can be viewed as an implicit hough-voting codebook. (2) We collect the weighted votes from all the testing patches and compute the final voting density map in a way similar to Parzen-window estimation. The final nucleus positions are identified by searching the local maxima of the density map. Our method only requires a few annotation efforts (just one click near the nucleus center). Experiment results on Neuroendocrine Tumor (NET) microscopy images proves the proposed method to be state-of-the-art.

  18. Immuno- and correlative light microscopy-electron tomography methods for 3D protein localization in yeast.

    PubMed

    Mari, Muriel; Geerts, Willie J C; Reggiori, Fulvio

    2014-10-01

    Compartmentalization of eukaryotic cells is created and maintained through membrane rearrangements that include membrane transport and organelle biogenesis. Three-dimensional reconstructions with nanoscale resolution in combination with protein localization are essential for an accurate molecular dissection of these processes. The yeast Saccharomyces cerevisiae is a key model system for identifying genes and characterizing pathways essential for the organization of cellular ultrastructures. Electron microscopy studies of yeast, however, have been hampered by the presence of a cell wall that obstructs penetration of resins and cryoprotectants, and by the protein dense cytoplasm, which obscures the membrane details. Here we present an immuno-electron tomography (IET) method, which allows the determination of protein distribution patterns on reconstructed organelles from yeast. In addition, we extend this IET approach into a correlative light microscopy-electron tomography procedure where structures positive for a specific protein localized through a fluorescent signal are resolved in 3D. These new investigative tools for yeast will help to advance our understanding of the endomembrane system organization in eukaryotic cells.

  19. Body image score following anterior and lateral approaches to wide local excision for early breast cancer.

    PubMed

    Lee, Menelik; Patel, Mitesh; Cresswell, Adrian B; Bentley, Phillip G

    2007-01-01

    Breast cancer surgery is an emotive topic and rather than just simple cosmetic issues, the final appearance of the operated breast has been shown to have a significant impact on psychologic well-being and overall quality of life. Wide local excision (WLE) is a popular conservative approach to small tumors, which do not involve the nipple-areolar complex. This study compares WLE via an anterior and lateral approach. A retrospective survey of patient satisfaction was performed using a recognized and validated Body Image Score (BIS), which was sent to a total of 267 patients who had undergone WLE by either the anterior or lateral approach. The response rate was 57%, of which 89 women had undergone surgery via the anterior and 80 by the lateral approach. There was no significant difference in BIS when comparing the anterior and lateral approaches, despite concerns regarding the physical appearance of the scar and postoperative breast expressed by patients. Generally, surgery on the upper part of the breast was associated with less satisfaction than the lower, but "hiding" the scar with a lateral approach did not improve satisfaction. Surgeons should be reassured that the approach to WLE of early breast cancers has no impact on the patients overall body image and that the choice of technique should be based on the patient's personal preference and the surgeons experience and skill.

  20. A new optimization approach for the calibration of an ultrasound probe using a 3D optical localizer.

    PubMed

    Dardenne, G; Cano, J D Gil; Hamitouche, C; Stindel, E; Roux, C

    2007-01-01

    This paper describes a fast procedure for the calibration of an ultrasound (US) probe using a 3D optical localizer. This calibration step allows us to obtain the 3D position of any point located on the 2D ultrasonic (US) image. To carry out correctly this procedure, a phantom of known geometric properties is probed and these geometries are found in the US images. A segmentation step is applied in order to obtain automatically the needed information in the US images and then, an optimization approach is performed to find the optimal calibration parameters. A new optimization method to estimate the calibration parameters for an ultrasound (US) probe is developed.

  1. Fast 3d Hybrid Seismic Modeling: Ray-fd Approach For Elastic Models With Locally Complex Structures

    NASA Astrophysics Data System (ADS)

    Oprsal, I.; Brokesova, J.; Faeh, D.; Giardini, D.

    Hybrid approaches may find broad applications wherever full source, path,and site effects modeling methods are too expensive. A new efficient hybrid method allowing to compute seismic wavefield in large 3D elastic models containing a complex local structure embedded in a large, but considerably simpler, structure is designed. This hybrid method combines the ray approach in the large simple structure with the finite difference (FD) approach in the local complex structure. The hybrid method is based on two successive steps. In the 1st one, the source and path information is carried by wavefield propagating in the large simple structure. This wavefield, calculated by the ray method, is incident at the points along a two-fold formal boundary (excitation box, EB) surrounding that part of the model which is to be replaced by the complex medium in the 2nd step. 3D rays are necessary due to ar- bitrary source-EB configuration, even in case the 1st step structure is less dimensional (2D, 1D, homogeneous). Along EB, the ray endpoints may be distributed sparsely thanks to relative simplicity of the structure. This reduces computer time requirements and also the size of the excitation file saved on the disk. The ray wavefield along EB provides (after interpolation in space and time) the input for the second step consisting in calculating the complete wavefield by the 3D FD method on irregular grids. The FD computational domain contains the EB and its close vicinity. The 2nd step model differs from the 1st step model only inside the EB where the local complex structure is inserted. To verify the consistency between the 1st and the 2nd step binding, the 2nd step computation can be performed on (unchanged) 1st step model ('replication test'). This should give the same wavefield as the 1st step inside, and zero wavefield outside the EB. The EB remains fully permeable for all waves propagating within the FD domain. Provided the 1st step structure does not contain too many layers

  2. Assessment of Social Vulnerability Identification at Local Level around Merapi Volcano - A Self Organizing Map Approach

    NASA Astrophysics Data System (ADS)

    Lee, S.; Maharani, Y. N.; Ki, S. J.

    2015-12-01

    The application of Self-Organizing Map (SOM) to analyze social vulnerability to recognize the resilience within sites is a challenging tasks. The aim of this study is to propose a computational method to identify the sites according to their similarity and to determine the most relevant variables to characterize the social vulnerability in each cluster. For this purposes, SOM is considered as an effective platform for analysis of high dimensional data. By considering the cluster structure, the characteristic of social vulnerability of the sites identification can be fully understand. In this study, the social vulnerability variable is constructed from 17 variables, i.e. 12 independent variables which represent the socio-economic concepts and 5 dependent variables which represent the damage and losses due to Merapi eruption in 2010. These variables collectively represent the local situation of the study area, based on conducted fieldwork on September 2013. By using both independent and dependent variables, we can identify if the social vulnerability is reflected onto the actual situation, in this case, Merapi eruption 2010. However, social vulnerability analysis in the local communities consists of a number of variables that represent their socio-economic condition. Some of variables employed in this study might be more or less redundant. Therefore, SOM is used to reduce the redundant variable(s) by selecting the representative variables using the component planes and correlation coefficient between variables in order to find the effective sample size. Then, the selected dataset was effectively clustered according to their similarities. Finally, this approach can produce reliable estimates of clustering, recognize the most significant variables and could be useful for social vulnerability assessment, especially for the stakeholder as decision maker. This research was supported by a grant 'Development of Advanced Volcanic Disaster Response System considering

  3. Methods for measuring denitrification: Diverse approaches to a difficult problem

    USGS Publications Warehouse

    Groffman, Peter M; Altabet, Mary A.; Böhlke, J.K.; Butterbach-Bahl, Klaus; David, Mary B.; Firestone, Mary K.; Giblin, Anne E.; Kana, Todd M.; Nielsen , Lars Peter; Voytek, Mary A.

    2006-01-01

    Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3−) and nitrite (NO2−), to the gases nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2), is important to primary production, water quality, and the chemistry and physics of the atmosphere at ecosystem, landscape, regional, and global scales. Unfortunately, this process is very difficult to measure, and existing methods are problematic for different reasons in different places at different times. In this paper, we review the major approaches that have been taken to measure denitrification in terrestrial and aquatic environments and discuss the strengths, weaknesses, and future prospects for the different methods. Methodological approaches covered include (1) acetylene-based methods, (2) 15N tracers, (3) direct N2 quantification, (4) N2:Ar ratio quantification, (5) mass balance approaches, (6) stoichiometric approaches, (7) methods based on stable isotopes, (8) in situ gradients with atmospheric environmental tracers, and (9) molecular approaches. Our review makes it clear that the prospects for improved quantification of denitrification vary greatly in different environments and at different scales. While current methodology allows for the production of accurate estimates of denitrification at scales relevant to water and air quality and ecosystem fertility questions in some systems (e.g., aquatic sediments, well-defined aquifers), methodology for other systems, especially upland terrestrial areas, still needs development. Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in denitrification methods over the next few years.

  4. A Coproduction Community Based Approach to Reducing Smoking Prevalence in a Local Community Setting

    PubMed Central

    McGeechan, G. J.; Woodall, D.; Anderson, L.; Wilson, L.; O'Neill, G.; Newbury-Birch, D.

    2016-01-01

    Research highlights that asset-based community development where local residents become equal partners in service development may help promote health and well-being. This paper outlines baseline results of a coproduction evaluation of an asset-based approach to improving health and well-being within a small community through promoting tobacco control. Local residents were recruited and trained as community researchers to deliver a smoking prevalence survey within their local community and became local health champions, promoting health and well-being. The results of the survey will be used to inform health promotion activities within the community. The local smoking prevalence was higher than the regional and national averages. Half of the households surveyed had at least one smoker, and 63.1% of children lived in a smoking household. Nonsmokers reported higher well-being than smokers; however, the differences were not significant. Whilst the community has a high smoking prevalence, more than half of the smokers surveyed would consider quitting. Providing smoking cessation advice in GP surgeries may help reduce smoking prevalence in this community. Work in the area could be done to reduce children's exposure to smoking in the home. PMID:27446219

  5. The regional approach and regional studies method in the process of geography teaching

    NASA Astrophysics Data System (ADS)

    Dermendzhieva, Stela; Doikov, Martin

    2017-03-01

    We define the regional approach as a manner of relations among the global trends of development of the "Society-man-nature" system and the local differentiating level of knowledge. Conditionally, interactions interlace under the influence of the character of Geography as a science, education, approaches, goals and teaching methods. Global, national and local development differentiates in three concentric circles at the level of knowledge. It is determined as a conception of modern, complex and effective mechanism for young people, through which knowledge develops in regional historical and cultural perspective; self-consciousness for socio-economic and cultural integration is formed as a part of the. historical-geographical image of the native land. This way an attitude to the. native land is formed as a connecting construct between patriotism to the motherland and the same in global aspect. The possibility for integration and cooperation of the educative geographical content with all the local historical-geographical, regional, profession orientating, artistic, municipal and district institutions, is outlined. Contemporary geographical education appears to be a powerful and indispensable mechanism for organization of human sciences, while the regional approach and the application of the regional studies method stimulate and motivate the development and realization of optimal capacities for direct connection with the local structures and environments.

  6. Fourth order exponential time differencing method with local discontinuous Galerkin approximation for coupled nonlinear Schrodinger equations

    DOE PAGES

    Liang, Xiao; Khaliq, Abdul Q. M.; Xing, Yulong

    2015-01-23

    In this paper, we study a local discontinuous Galerkin method combined with fourth order exponential time differencing Runge-Kutta time discretization and a fourth order conservative method for solving the nonlinear Schrödinger equations. Based on different choices of numerical fluxes, we propose both energy-conserving and energy-dissipative local discontinuous Galerkin methods, and have proven the error estimates for the semi-discrete methods applied to linear Schrödinger equation. The numerical methods are proven to be highly efficient and stable for long-range soliton computations. Finally, extensive numerical examples are provided to illustrate the accuracy, efficiency and reliability of the proposed methods.

  7. A new approach to study medicinal plants with tannins and flavonoids contents from the local knowledge.

    PubMed

    de Sousa Araújo, Thiago Antônio; Alencar, Nelson Leal; de Amorim, Elba Lúcia Cavalcanti; de Albuquerque, Ulysses Paulino

    2008-10-30

    The present work tested the power of different methodological strategies for identifying plants that could be interesting in terms of their phenolic compounds (especially flavonoids and tannins) by comparing a new index in which priority-determining criteria are based on the free-listing technique as well as on two randomized methods for choosing plants within an ethnodirected based approach. The present study was undertaken in the rural area of the municipality of Altinho located in the central region of Pernambuco State, northeastern Brazil. The ethnobotanical survey was divided into three different stages. The first stage was a general survey of 101 individuals on the use and knowledge of medicinal plants within the community. During the second stage local specialists were selected on the basis of the quality and quantity of information they offered during the initial phase of the investigation. The third stage consisted of returning to the specialists a final time in order to apply the free-listing technique. We also assumed that a plant could demonstrate anti-inflammatory and healing effects even without the presence of the compounds of interest of this study. There is a strong association between tannin content and the effects popularly attributed to wound-healing and anti-inflammatory plants. No relationships were observed between plants used by the community to treat inflammation or healing with their flavonoid contents. Thus, identifying Caatinga medicinal plants known with anti-inflammatory activity and healing capacities is a good criterion for identifying species with high levels of tannins, although these same criteria are not useful for identifying plants with high flavonoid contents.

  8. Model-independent mean-field theory as a local method for approximate propagation of information.

    PubMed

    Haft, M; Hofmann, R; Tresp, V

    1999-02-01

    We present a systematic approach to mean-field theory (MFT) in a general probabilistic setting without assuming a particular model. The mean-field equations derived here may serve as a local, and thus very simple, method for approximate inference in probabilistic models such as Boltzmann machines or Bayesian networks. Our approach is 'model-independent' in the sense that we do not assume a particular type of dependences; in a Bayesian network, for example, we allow arbitrary tables to specify conditional dependences. In general, there are multiple solutions to the mean-field equations. We show that improved estimates can be obtained by forming a weighted mixture of the multiple mean-field solutions. Simple approximate expressions for the mixture weights are given. The general formalism derived so far is evaluated for the special case of Bayesian networks. The benefits of taking into account multiple solutions are demonstrated by using MFT for inference in a small and in a very large Bayesian network. The results are compared with the exact results.

  9. Various contact approaches for the finite cell method

    NASA Astrophysics Data System (ADS)

    Konyukhov, Alexander; Lorenz, Christian; Schweizerhof, Karl

    2015-08-01

    The finite cell method (FCM) provides a method for the computation of structures which can be described as a mixture of high-order FEM and a special integration technique. The method is one of the novel computational methods and is highly developed within the last decade. One of the major problems of FCM is the description of boundary conditions inside cells as well as in sub-cells. And a completely open problem is the description of contact. Therefore, the motivation of the current work is to develop a set of computational contact mechanics approaches which will be effective for the finite element cell method. Thus, for the FCM method we are developing and testing hereby focusing on the Hertz problem the following algorithms: direct integration in the cell method, allowing the fastest implementation, but suffering from numerical artifacts such as the "stamp effect"; the most efficient scheme concerning approximation properties the cell-surface-to-analytical-surface contact element designed for contact with rigid bodies leading to cell-wisely contact elements; and finally the discrete-cell-to-cell contact approach based on the finite discrete method. All developed methods are carefully verified with the analytical Hertz solution. The cell subdivisions, the order of the shape functions as well as the selection of the classes for shape functions are investigated for all developed contact approaches. This analysis allows to choose the most robust approach depending on the needs of the user such as correct representation of the stresses, or only satisfaction of geometrical non-penetration conditions.

  10. A finite Reynolds number approach for the prediction of boundary layer receptivity in localized regions

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan; Street, Craig L.

    1991-01-01

    Previous theoretical work on the boundary layer receptivity problem has utilized large Reynolds number asymptotic theories, thus being limited to a narrow part of the frequency - Reynolds number domain. An alternative approach is presented for the prediction of localized instability generation which has a general applicability, and also accounts for finite Reynolds number effects. This approach is illustrated for the case of Tollmien-Schlichting wave generation in a Blasius boundary layer due to the interaction of a free stream acoustic wave with a region of short scale variation in the surface boundary condition. The specific types of wall inhomogeneities studied are: regions of short scale variations in wall suction, wall admittance, and wall geometry (roughness). Extensive comparison is made between the results of the finite Reynolds number approach and previous asymptotic predictions, which also suggests an alternative way of using the latter at Reynolds numbers of interest in practice.

  11. Localization Framework for Real-Time UAV Autonomous Landing: An On-Ground Deployed Visual Approach

    PubMed Central

    Kong, Weiwei; Hu, Tianjiang; Zhang, Daibing; Shen, Lincheng; Zhang, Jianwei

    2017-01-01

    One of the greatest challenges for fixed-wing unmanned aircraft vehicles (UAVs) is safe landing. Hereafter, an on-ground deployed visual approach is developed in this paper. This approach is definitely suitable for landing within the global navigation satellite system (GNSS)-denied environments. As for applications, the deployed guidance system makes full use of the ground computing resource and feedbacks the aircraft’s real-time localization to its on-board autopilot. Under such circumstances, a separate long baseline stereo architecture is proposed to possess an extendable baseline and wide-angle field of view (FOV) against the traditional fixed baseline schemes. Furthermore, accuracy evaluation of the new type of architecture is conducted by theoretical modeling and computational analysis. Dataset-driven experimental results demonstrate the feasibility and effectiveness of the developed approach. PMID:28629189

  12. Localization Framework for Real-Time UAV Autonomous Landing: An On-Ground Deployed Visual Approach.

    PubMed

    Kong, Weiwei; Hu, Tianjiang; Zhang, Daibing; Shen, Lincheng; Zhang, Jianwei

    2017-06-19

    [-5]One of the greatest challenges for fixed-wing unmanned aircraft vehicles (UAVs) is safe landing. Hereafter, an on-ground deployed visual approach is developed in this paper. This approach is definitely suitable for landing within the global navigation satellite system (GNSS)-denied environments. As for applications, the deployed guidance system makes full use of the ground computing resource and feedbacks the aircraft's real-time localization to its on-board autopilot. Under such circumstances, a separate long baseline stereo architecture is proposed to possess an extendable baseline and wide-angle field of view (FOV) against the traditional fixed baseline schemes. Furthermore, accuracy evaluation of the new type of architecture is conducted by theoretical modeling and computational analysis. Dataset-driven experimental results demonstrate the feasibility and effectiveness of the developed approach.

  13. Stellar mass functions: methods, systematics and results for the local Universe

    NASA Astrophysics Data System (ADS)

    Weigel, Anna K.; Schawinski, Kevin; Bruderer, Claudio

    2016-06-01

    We present a comprehensive method for determining stellar mass functions, and apply it to samples in the local Universe. We combine the classical 1/Vmax approach with STY, a parametric maximum likelihood method and step-wise maximum likelihood, a non-parametric maximum likelihood technique. In the parametric approach, we are assuming that the stellar mass function can be modelled by either a single or a double Schechter function and we use a likelihood ratio test to determine which model provides a better fit to the data. We discuss how the stellar mass completeness as a function of z biases the three estimators and how it can affect, especially the low-mass end of the stellar mass function. We apply our method to Sloan Digital Sky Survey DR7 data in the redshift range from 0.02 to 0.06. We find that the entire galaxy sample is best described by a double Schechter function with the following parameters: log (M*/M⊙) = 10.79 ± 0.01, log (Φ ^{{ast }}_1/h^3 Mpc^{-3}) = -3.31 ± 0.20, α1 = -1.69 ± 0.10, log (Φ ^{{ast }}_2/h^3 Mpc^{-3}) = -2.01 ± 0.28 and α2 = -0.79 ± 0.04. We also use morphological classifications from Galaxy Zoo and halo mass, overdensity, central/satellite, colour and specific star formation rate measurements to split the galaxy sample into over 130 subsamples. We determine and present the stellar mass functions and the best-fitting Schechter function parameters for each of these subsamples.

  14. Anchor-free localization method for mobile targets in coal mine wireless sensor networks.

    PubMed

    Pei, Zhongmin; Deng, Zhidong; Xu, Shuo; Xu, Xiao

    2009-01-01

    Severe natural conditions and complex terrain make it difficult to apply precise localization in underground mines. In this paper, an anchor-free localization method for mobile targets is proposed based on non-metric multi-dimensional scaling (Multi-dimensional Scaling: MDS) and rank sequence. Firstly, a coal mine wireless sensor network is constructed in underground mines based on the ZigBee technology. Then a non-metric MDS algorithm is imported to estimate the reference nodes' location. Finally, an improved sequence-based localization algorithm is presented to complete precise localization for mobile targets. The proposed method is tested through simulations with 100 nodes, outdoor experiments with 15 ZigBee physical nodes, and the experiments in the mine gas explosion laboratory with 12 ZigBee nodes. Experimental results show that our method has better localization accuracy and is more robust in underground mines.

  15. Anchor-Free Localization Method for Mobile Targets in Coal Mine Wireless Sensor Networks

    PubMed Central

    Pei, Zhongmin; Deng, Zhidong; Xu, Shuo; Xu, Xiao

    2009-01-01

    Severe natural conditions and complex terrain make it difficult to apply precise localization in underground mines. In this paper, an anchor-free localization method for mobile targets is proposed based on non-metric multi-dimensional scaling (Multi-dimensional Scaling: MDS) and rank sequence. Firstly, a coal mine wireless sensor network is constructed in underground mines based on the ZigBee technology. Then a non-metric MDS algorithm is imported to estimate the reference nodes’ location. Finally, an improved sequence-based localization algorithm is presented to complete precise localization for mobile targets. The proposed method is tested through simulations with 100 nodes, outdoor experiments with 15 ZigBee physical nodes, and the experiments in the mine gas explosion laboratory with 12 ZigBee nodes. Experimental results show that our method has better localization accuracy and is more robust in underground mines. PMID:22574048

  16. The Health Role of Local Area Coordinators in Scotland: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Brown, Michael; Karatzias, Thanos; O'Leary, Lisa

    2013-01-01

    The study set out to explore whether local area coordinators (LACs) and their managers view the health role of LACs as an essential component of their work and identify the health-related activities undertaken by LACs in Scotland. A mixed methods cross-sectional phenomenological study involving local authority service managers (n = 25) and LACs (n…

  17. The Health Role of Local Area Coordinators in Scotland: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Brown, Michael; Karatzias, Thanos; O'Leary, Lisa

    2013-01-01

    The study set out to explore whether local area coordinators (LACs) and their managers view the health role of LACs as an essential component of their work and identify the health-related activities undertaken by LACs in Scotland. A mixed methods cross-sectional phenomenological study involving local authority service managers (n = 25) and LACs (n…

  18. Millimeter-Wave Localizers for Aircraft-to-Aircraft Approach Navigation

    NASA Technical Reports Server (NTRS)

    Tang, Adrian J.

    2013-01-01

    Aerial refueling technology for both manned and unmanned aircraft is critical for operations where extended aircraft flight time is required. Existing refueling assets are typically manned aircraft, which couple to a second aircraft through the use of a refueling boom. Alignment and mating of the two aircraft continues to rely on human control with use of high-resolution cameras. With the recent advances in unmanned aircraft, it would be highly advantageous to remove/reduce human control from the refueling process, simplifying the amount of remote mission management and enabling new operational scenarios. Existing aerial refueling uses a camera, making it non-autonomous and prone to human error. Existing commercial localizer technology has proven robust and reliable, but not suited for aircraft-to-aircraft approaches like in aerial refueling scenarios since the resolution is too coarse (approximately one meter). A localizer approach system for aircraft-to-aircraft docking can be constructed using the same modulation with a millimeterwave carrier to provide high resolution. One technology used to remotely align commercial aircraft on approach to a runway are ILS (instrument landing systems). ILS have been in service within the U.S. for almost 50 years. In a commercial ILS, two partially overlapping beams of UHF (109 to 126 MHz) are broadcast from an antenna array so that their overlapping region defines the centerline of the runway. This is called a localizer system and is responsible for horizontal alignment of the approach. One beam is modulated with a 150-Hz tone, while the other with a 90-Hz tone. Through comparison of the modulation depths of both tones, an autopilot system aligns the approaching aircraft with the runway centerline. A similar system called a glide-slope (GS) exists in the 320-to-330MHz band for vertical alignment of the approach. While this technology has been proven reliable for millions of commercial flights annually, its UHF nature limits

  19. A hybrid approach for efficient anomaly detection using metaheuristic methods.

    PubMed

    Ghanem, Tamer F; Elkilani, Wail S; Abdul-Kader, Hatem M

    2015-07-01

    Network intrusion detection based on anomaly detection techniques has a significant role in protecting networks and systems against harmful activities. Different metaheuristic techniques have been used for anomaly detector generation. Yet, reported literature has not studied the use of the multi-start metaheuristic method for detector generation. This paper proposes a hybrid approach for anomaly detection in large scale datasets using detectors generated based on multi-start metaheuristic method and genetic algorithms. The proposed approach has taken some inspiration of negative selection-based detector generation. The evaluation of this approach is performed using NSL-KDD dataset which is a modified version of the widely used KDD CUP 99 dataset. The results show its effectiveness in generating a suitable number of detectors with an accuracy of 96.1% compared to other competitors of machine learning algorithms.

  20. A hybrid approach for efficient anomaly detection using metaheuristic methods

    PubMed Central

    Ghanem, Tamer F.; Elkilani, Wail S.; Abdul-kader, Hatem M.

    2014-01-01

    Network intrusion detection based on anomaly detection techniques has a significant role in protecting networks and systems against harmful activities. Different metaheuristic techniques have been used for anomaly detector generation. Yet, reported literature has not studied the use of the multi-start metaheuristic method for detector generation. This paper proposes a hybrid approach for anomaly detection in large scale datasets using detectors generated based on multi-start metaheuristic method and genetic algorithms. The proposed approach has taken some inspiration of negative selection-based detector generation. The evaluation of this approach is performed using NSL-KDD dataset which is a modified version of the widely used KDD CUP 99 dataset. The results show its effectiveness in generating a suitable number of detectors with an accuracy of 96.1% compared to other competitors of machine learning algorithms. PMID:26199752

  1. Exact method for numerically analyzing a model of local denaturation in superhelically stressed DNA

    NASA Astrophysics Data System (ADS)

    Fye, Richard M.; Benham, Craig J.

    1999-03-01

    Local denaturation, the separation at specific sites of the two strands comprising the DNA double helix, is one of the most fundamental processes in biology, required to allow the base sequence to be read both in DNA transcription and in replication. In living organisms this process can be mediated by enzymes which regulate the amount of superhelical stress imposed on the DNA. We present a numerically exact technique for analyzing a model of denaturation in superhelically stressed DNA. This approach is capable of predicting the locations and extents of transition in circular superhelical DNA molecules of kilobase lengths and specified base pair sequences. It can also be used for closed loops of DNA which are typically found in vivo to be kilobases long. The analytic method consists of an integration over the DNA twist degrees of freedom followed by the introduction of auxiliary variables to decouple the remaining degrees of freedom, which allows the use of the transfer matrix method. The algorithm implementing our technique requires O(N2) operations and O(N) memory to analyze a DNA domain containing N base pairs. However, to analyze kilobase length DNA molecules it must be implemented in high precision floating point arithmetic. An accelerated algorithm is constructed by imposing an upper bound M on the number of base pairs that can simultaneously denature in a state. This accelerated algorithm requires O(MN) operations, and has an analytically bounded error. Sample calculations show that it achieves high accuracy (greater than 15 decimal digits) with relatively small values of M (M<0.05N) for kilobase length molecules under physiologically relevant conditions. Calculations are performed on the superhelical pBR322 DNA sequence to test the accuracy of the method. With no free parameters in the model, the locations and extents of local denaturation predicted by this analysis are in quantitatively precise agreement with in vitro experimental measurements. Calculations

  2. The Feldenkrais Method: A Dynamic Approach to Changing Motor Behavior.

    ERIC Educational Resources Information Center

    Buchanan, Patricia A.; Ulrich, Beverly D.

    2001-01-01

    Describes the Feldenkrais Method of somatic education, noting parallels with a dynamic systems theory (DST) approach to motor behavior. Feldenkrais uses movement and perception to foster individualized improvement in function. DST explains that a human-environment system continually adapts to changing conditions and assembles behaviors…

  3. Mentorship in Practice: A Multi-Method Approach.

    ERIC Educational Resources Information Center

    Schreck, Timothy J.; And Others

    This study was conducted to evaluate a field-based mentorship program using a multi-method approach. It explored the use of mentorship as practiced in the Florida Compact, a business education partnership established in Florida in 1987. The study was designed to identify differences between mentors and mentorees, as well as differences within…

  4. Major Approaches to Music Education: An Account of Method.

    ERIC Educational Resources Information Center

    Shehan, Patricia K.

    1986-01-01

    In a continuing effort to improve the music education of students in beginning stages, there is a need for the review of teaching techniques that motivate student learning behaviors. Historically, music methods actively engaged students in the music-making process. The approaches of Dalcroze, Orff, Suzuki, Kodaly, and Gordon continue that…

  5. New approaches for automatic threedimensional source localization of acoustic emissions--Applications to concrete specimens.

    PubMed

    Kurz, Jochen H

    2015-12-01

    The task of locating a source in space by measuring travel time differences of elastic or electromagnetic waves from the source to several sensors is evident in varying fields. The new concepts of automatic acoustic emission localization presented in this article are based on developments from geodesy and seismology. A detailed description of source location determination in space is given with the focus on acoustic emission data from concrete specimens. Direct and iterative solvers are compared. A concept based on direct solvers from geodesy extended by a statistical approach is described which allows a stable source location determination even for partly erroneous onset times. The developed approach is validated with acoustic emission data from a large specimen leading to travel paths up to 1m and therefore to noisy data with errors in the determined onsets. The adaption of the algorithms from geodesy to the localization procedure of sources of elastic waves offers new possibilities concerning stability, automation and performance of localization results. Fracture processes can be assessed more accurately. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Brain networks, structural realism, and local approaches to the scientific realism debate.

    PubMed

    Yan, Karen; Hricko, Jonathon

    2017-08-01

    We examine recent work in cognitive neuroscience that investigates brain networks. Brain networks are characterized by the ways in which brain regions are functionally and anatomically connected to one another. Cognitive neuroscientists use various noninvasive techniques (e.g., fMRI) to investigate these networks. They represent them formally as graphs. And they use various graph theoretic techniques to analyze them further. We distinguish between knowledge of the graph theoretic structure of such networks (structural knowledge) and knowledge of what instantiates that structure (nonstructural knowledge). And we argue that this work provides structural knowledge of brain networks. We explore the significance of this conclusion for the scientific realism debate. We argue that our conclusion should not be understood as an instance of a global structural realist claim regarding the structure of the unobservable part of the world, but instead, as a local structural realist attitude towards brain networks in particular. And we argue that various local approaches to the realism debate, i.e., approaches that restrict realist commitments to particular theories and/or entities, are problematic insofar as they don't allow for the possibility of such a local structural realist attitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A refined cluster-in-molecule local correlation approach for predicting the relative energies of large systems.

    PubMed

    Li, Wei; Guo, Yang; Li, Shuhua

    2012-06-07

    A refined cluster-in-molecule (CIM) method for local correlation calculations of large molecules is presented. In the present work, two new strategies are introduced to further improve the CIM approach: (1) Some medium-range electron correlation energies, which are neglected in the previous CIM approach, are taken into account. (2) A much simpler procedure using only a distance threshold is used to construct various clusters. To cover the medium-range correlation effect as much as possible, some two-atom-centered clusters are built, in addition to one-atom-centered clusters. Our test calculations at the second order perturbation theory (MP2) level show that the refined CIM method can recover about 99.9% of the conventional MP2 correlation energy using an appropriate distance threshold. The accuracy of the present CIM method is capable of providing reliable relative energies of medium-sized systems such as polyalanines with 10 residues, and water molecules with 50 water molecules. For polyalanines with up to 30 residues, we have demonstrated that the computational cost of the CIM-MP2 calculation increases linearly with the molecular size, but the required memory and disc-space do not need to increase for large systems. The improved CIM method has been used to compute the relative energy of ice-like (H(2)O)(96) clusters (with 2400 basis functions) and to predict the dimerization energy of a double-helical foldamer (with 2330 basis functions). The present CIM method is expected to be a practical local correlation method for describing the relative energies of large systems.

  8. Mapping Patterns of Local Recurrence After Pancreaticoduodenectomy for Pancreatic Adenocarcinoma: A New Approach to Adjuvant Radiation Field Design

    SciTech Connect

    Dholakia, Avani S.; Kumar, Rachit; Raman, Siva P.; Moore, Joseph A.; Ellsworth, Susannah; McNutt, Todd; Laheru, Daniel A.; Jaffee, Elizabeth; Cameron, John L.; Tran, Phuoc T.; Hobbs, Robert F.; Wolfgang, Christopher L.; and others

    2013-12-01

    Purpose: To generate a map of local recurrences after pancreaticoduodenectomy (PD) for patients with resectable pancreatic ductal adenocarcinoma (PDA) and to model an adjuvant radiation therapy planning treatment volume (PTV) that encompasses a majority of local recurrences. Methods and Materials: Consecutive patients with resectable PDA undergoing PD and 1 or more computed tomography (CT) scans more than 60 days after PD at our institution were reviewed. Patients were divided into 3 groups: no adjuvant treatment (NA), chemotherapy alone (CTA), or chemoradiation (CRT). Cross-sectional scans were centrally reviewed, and local recurrences were plotted to scale with respect to the celiac axis (CA), superior mesenteric artery (SMA), and renal veins on 1 CT scan of a template post-PD patient. An adjuvant clinical treatment volume comprising 90% of local failures based on standard expansions of the CA and SMA was created and simulated on 3 post-PD CT scans to assess the feasibility of this planning approach. Results: Of the 202 patients in the study, 40 (20%), 34 (17%), and 128 (63%) received NA, CTA, and CRT adjuvant therapy, respectively. The rate of margin-positive resections was greater in CRT patients than in CTA patients (28% vs 9%, P=.023). Local recurrence occurred in 90 of the 202 patients overall (45%) and in 19 (48%), 22 (65%), and 49 (38%) in the NA, CTA, and CRT groups, respectively. Ninety percent of recurrences were within a 3.0-cm right-lateral, 2.0-cm left-lateral, 1.5-cm anterior, 1.0-cm posterior, 1.0-cm superior, and 2.0-cm inferior expansion of the combined CA and SMA contours. Three simulated radiation treatment plans using these expansions with adjustments to avoid nearby structures were created to demonstrate the use of this treatment volume. Conclusions: Modified PTVs targeting high-risk areas may improve local control while minimizing toxicities, allowing dose escalation with intensity-modulated or stereotactic body radiation therapy.

  9. Overview of mobile localization techniques and performances of a novel fingerprinting-based method

    NASA Astrophysics Data System (ADS)

    Vin, Isabelle; Gaillot, Davy P.; Laly, Pierre; Liénard, Martine; Degauque, Pierre

    2015-11-01

    Mobile localization techniques in outdoor environment have been widely studied. In this paper, we consider a specific application related to search and rescue activities or electronic surveillance in urban areas. In this case, the localization must be of high accuracy, on the order of 10 m, despite other constraints related, among others, to non-line-of-sight conditions and non-cooperation with other nearby mobiles or cellular base stations. A brief survey of RF-based localization techniques shows that none of them fully satisfy the desired specifications. A novel approach combining fingerprinting and polarization diversity is then described, its performance being assessed from on-site measurements.

  10. New approaches for the calibration of exchange-energy densities in local hybrid functionals.

    PubMed

    Maier, Toni M; Haasler, Matthias; Arbuznikov, Alexei V; Kaupp, Martin

    2016-08-21

    The ambiguity of exchange-energy densities is a fundamental challenge for the development of local hybrid functionals, or of other functionals based on a local mixing of exchange-energy densities. In this work, a systematic construction of semi-local calibration functions (CFs) for adjusting the exchange-energy densities in local hybrid functionals is provided, which directly links a given CF to an underlying semi-local exchange functional, as well as to the second-order gradient expansion of the exchange hole. Using successive steps of integration by parts allows the derivation of correction terms of increasing order, resulting in more and more complicated but also more flexible CFs. We derive explicit first- and second-order CFs (pig1 and pig2) based on B88 generalized-gradient approximation (GGA) exchange, and a first-order CF (tpig1) based on τ-dependent B98 meta-GGA exchange. We combine these CFs with different long-range damping functions and evaluate them for calibration of LDA, B88 GGA, and TPSS meta-GGA exchange-energy densities. Based on a minimization of unphysical nondynamical correlation contributions in three noble-gas dimer potential-energy curves, free parameters in the CFs are optimized, and performance of various approaches in the calibration of different exchange-energy densities is compared. Most notably, the second-order pig2 CF provides the largest flexibility with respect to the diffuseness of the damping function. This suggests that higher-order CFs based on the present integration-by-parts scheme may be particularly suitable for the flexible construction of local hybrid functionals.

  11. Service Areas of Local Urban Green Spaces: AN Explorative Approach in Arroios, Lisbon

    NASA Astrophysics Data System (ADS)

    Figueiredo, R.; Gonçalves, A. B.; Ramos, I. L.

    2016-09-01

    The identification of service areas of urban green spaces and areas with lack of these is increasingly necessary within city planning and management, as it translates into important indicators for the assessment of quality of life. In this setting, it is important to evaluate the attractiveness and accessibility dynamics through a set of attributes, taking into account the local reality of the territory under study. This work presents an operational methodology associated with these dynamics in local urban green spaces, assisting in the planning and management of this type of facilities. The methodology is supported firstly on questionnaire surveys and then on network analysis, processing spatial data in a Geographic Information Systems (GIS) environment. In the case study, two local green spaces in Lisbon were selected, on a local perspective explorative approach. Through field data, it was possible to identify service areas for both spaces, and compare the results with references in the literature. It was also possible to recognise areas with lack of these spaces. The difficulty to evaluate the dynamics of real individuals in their choices of urban green spaces and the respective route is a major challenge to the application of the methodology. In this sense it becomes imperative to develop different instruments and adapt them to other types of urban green spaces.

  12. Global, national, and local approaches to mental health: examples from India.

    PubMed

    Weiss, M G; Isaac, M; Parkar, S R; Chowdhury, A N; Raguram, R

    2001-01-01

    Neuropsychiatric disorders and suicide amount to 12.7% of the global burden of disease and related conditions (GBD) according to World Health Organization (WHO) estimates for 1999, and recognition of the enormous component of mental illness in the GBD has attracted unprecedented attention in the field of international health. Focusing on low- and middle-income countries with high adult mortality, this article discusses essential functions of international agencies concerned with mental health. A review of the history and development of national mental health policy in India follows, and local case studies consider the approach to planning in a rural mental health programme in West Bengal and the experience in an established urban mental health programme in a low-income community of Mumbai. Local programmes must be attentive to the needs of the communities they serve, and they require the support of global and national policy for resources and the conceptual tools to formulate strategies to meet those needs. National programmes retain major responsibilities for the health of their country's population: they are the portals through which global and local interests, ideas, and policies formally interact. International priorities should be responsive to a wide range of national interests, which in turn should be sensitive to diverse local experiences. Mental health actions thereby benefit from the synergy of informed and effective policy at each level.

  13. Does super-resolution fluorescence microscopy obsolete previous microscopic approaches to protein co-localization?

    PubMed

    MacDonald, Laura; Baldini, Giulia; Storrie, Brian

    2015-01-01

    Conventional microscopy techniques, namely, the confocal microscope or deconvolution processes, are resolution limited to approximately 200-250 nm by the diffraction properties of light as developed by Ernst Abbe in 1873. This diffraction limit is appreciably above the size of most multi-protein complexes, which are typically 20-50 nm in diameter. In the mid-2000s, biophysicists moved beyond the diffraction barrier by structuring the illumination pattern and then applying mathematical principles and algorithms to allow a resolution of approximately 100 nm, sufficient to address protein subcellular co-localization questions. This "breaking" of the diffraction barrier, affording resolution beyond 200 nm, is termed super-resolution microscopy. More recent approaches include single-molecule localization (such as photoactivated localization microscopy (PALM)/stochastic optical reconstruction microscopy (STORM)) and point spread function engineering (such as stimulated emission depletion (STED) microscopy). In this review, we explain basic principles behind currently commercialized super-resolution setups and address advantages and considerations in applying these techniques to protein co-localization in biological systems.

  14. Combined modalities approach for localized adult extremity soft-tissue sarcoma.

    PubMed

    Gronchi, Alessandro; Olmi, Patrizia; Casali, Paolo Giovanni

    2007-08-01

    Extremity soft-tissue sarcomas are a heterogeneous group of rare neoplasms, characterized by a broad spectrum of biological aggressiveness and a uniform tendency for local failure if not adequately treated. Surgery is the mainstay of therapy, and the availability of multidisciplinary surgical skills allows adequate margins with acceptable morbidity to be obtained. Local therapies, such as radiation therapy or isolated limb perfusion, alone or in combination with systemic agents, may help to further improve local control, especially in difficult presentations. The possible impact of systemic treatment on survival is still a matter of debate, and the agents used so far have not provided a major breakthrough, even in selected populations at high risk of disease spread. Nevertheless, soft-tissue sarcomas are no longer considered a unique disease. More than 50 different histotypes can now be well recognized, with distinct biological and molecular characteristics, which lead to different clinical behavior and a potentially different sensitivity to targeted agents. Therefore, it is more essential than ever for treatment of these patients to be delivered in referral centers, where a dedicated multidisciplinary team is able to administer histology and clinically driven approaches. The employment of combined modalities will be able to maximize the chance of local cure even in difficult presentations, and possibly improve survival, especially in high-risk disease.

  15. A local quasicontinuum method for 3D multilattice crystalline materials: Application to shape-memory alloys

    NASA Astrophysics Data System (ADS)

    Sorkin, V.; Elliott, R. S.; Tadmor, E. B.

    2014-07-01

    The quasicontinuum (QC) method, in its local (continuum) limit, is applied to materials with a multilattice crystal structure. Cauchy-Born (CB) kinematics, which accounts for the shifts of the crystal motif, is used to relate atomic motions to continuum deformation gradients. To avoid failures of CB kinematics, QC is augmented with a phonon stability analysis that detects lattice period extensions and identifies the minimum required periodic cell size. This approach is referred to as Cascading Cauchy-Born kinematics (CCB). In this paper, the method is described and developed. It is then used, along with an effective interaction potential (EIP) model for shape-memory alloys, to simulate the shape-memory effect and pseudoelasticity in a finite specimen. The results of these simulations show that (i) the CCB methodology is an essential tool that is required in order for QC-type simulations to correctly capture the first-order phase transitions responsible for these material behaviors, and (ii) that the EIP model adopted in this work coupled with the QC/CCB methodology is capable of predicting the characteristic behavior found in shape-memory alloys.

  16. Modified approach for extraperitoneal laparoscopic staging for locally advanced cervical cancer.

    PubMed

    Gil-Moreno, A; Maffuz, A; Díaz-Feijoo, B; Puig, O; Martínez-Palones, J M; Pérez, A; García, A; Xercavins, J

    2007-12-01

    Describe a modified approach to the technique for staging laparoscopic extraperitoneal aortic and common iliac lymph node dissection for locally advanced cervical cancer.Retrospective, nonrandomized clinical study. (Canadian Task Force classification II-2), setting in an acute-care, teaching hospital. Thirty-six patients with locally advanced cervical cancer underwent laparoscopic surgical staging via extraperitoneal approach with the conventional or the modified technique from August 2001 through September 2004. Clinical outcomes in 23 patients who were operated on with the conventional technique using index finger for first trocar entrance; 12 patients with the modified technique using direct trocar entrance, were compared. One patient was excluded due to peritoneal carcinomatosis. Technique, baseline characteristics, histopathologic variables and surgical outcome were measured. There were no significant differences in patients basal characteristics on comparative analysis between conventional and modified technique. With our proposed modified technique, we obtained a reduced surgical procedure duration and blood loss. The proposed modified surgical technique offers some advantages, is an easier approach because the parietal pelvic peritoneum is elastic and this helps to avoid its disruption at time of trocar insertion, size of incision is shorter, we achieved no CO2 leak through the trocar orifice, and wound suture is fast and simple.

  17. U.S. air quality management: local, regional and global approaches.

    PubMed

    Cote, Ila; Samet, Jonathan; Vandenberg, John J

    2008-01-01

    The purpose of this article is to review approaches to air quality management (AQM) in the United States. To characterize AQM in the United States, four examples that addressed local, regional, and global scale air pollution are described. These examples include: (1) the Hazardous Air Pollutants (HAPs) program, (2) National Ambient Air Quality Standards (NAAQS) program, (3) "Cap & Trade" programs, and (4) U.S. global pollution control efforts. These four examples were chosen because each presents a different approach to AQM. This was not intended to be a comprehensive description of U.S. AQM programs, but rather representative of selected examples that highlight the themes of this program. Some general principles that are illustrated in the article and are considered important characteristics of U.S. AQM are: Ensure open access to information and transparency in decision making. Develop and sustain a well-trained workforce. Facilitate training, networking, and technology transfer among air quality managers. Integrate planning and coordination of efforts across jurisdictions (across federal, state, and local agencies). Educate and encourage participation of stakeholders. Balance of societal benefits and costs. Apply innovative approaches, where possible. Fund research to improve the scientific basis for problem identification and effective AQM strategy development.

  18. Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing

    NASA Astrophysics Data System (ADS)

    Burkhardt, Anke; Geissler, Stefan; Koch, Edmund

    2010-04-01

    In most industrial states a huge amount of newly hatched male layer chickens are usually killed immediately after hatching by maceration or gassing. The reason for killing most of the male chickens of egg producing races is their slow growth rate compared to races specialized on meat production. When the egg has been laid, the egg contains already a small disc of cells on the surface of the yolk known as the blastoderm. This region is about 4 - 5 mm in diameter and contains the information whether the chick becomes male or female and hence allows sexing of the chicks by spectroscopy and other methods in the unincubated state. Different imaging methods like sonography, 3D-X-ray micro computed tomography and magnetic resonance imaging were used for localization of the blastoderm until now, but found to be impractical for different reasons. Optical coherence tomography (OCT) enables micrometer-scale, subsurface imaging of biological tissue and could therefore be a suitable technique for an accurate localization. The intention of this study is to prove if OCT can be an appropriate approach for the precise in ovo localization.

  19. Vibration localization in mono- and bi-coupled bladed disks - A transfer matrix approach

    NASA Technical Reports Server (NTRS)

    Ottarsson, Gisli; Pierre, Christophe

    1993-01-01

    A transfer matrix approach to the analysis of the dynamics of mistuned bladed disks is presented. The study focuses on mono-coupled systems, in which each blade is coupled to its two neighboring blades, and bi-coupled systems, where each blade is coupled to its four nearest neighbors. Transfer matrices yield the free dynamics, both the characteristic free wave and the normal modes - in closed form for the tuned assemblies. Mistuned assemblies are represented by random transfer matrices and an examination of the effect of mistuning on harmonic wave propagation yields the localization factor - the average rate of spatial wave amplitude decay per blade - in the mono-coupled assembly. Based on a comparison of the wave propagation characteristics of the mono- and bi-coupled assemblies, important conclusions are drawn about the effect of the additional coupling coordinate on the sensitivity to mistuning and the strength of mode localization predicted by a mono-coupled analysis.

  20. Stress and strain localization in stretched collagenous tissues via a multiscale modelling approach.

    PubMed

    Marino, Michele; Vairo, Giuseppe

    2014-01-01

    Mechanobiology of cells in soft collagenous tissues is highly affected by both tissue response at the macroscale and stress/strain localization mechanisms due to features at lower scales. In this paper, the macroscale mechanical behaviour of soft collagenous tissues is modelled by a three-level multiscale approach, based on a multi-step homogenisation technique from nanoscale up to the macroscale. Nanoscale effects, related to both intermolecular cross-links and collagen mechanics, are accounted for, together with geometric nonlinearities at the microscale. Moreover, an effective submodelling procedure is conceived in order to evaluate the local stress and strain fields at the microscale, which is around and within cells. Numerical results, obtained by using an incremental finite element formulation and addressing stretched tendinous tissues, prove consistency and accuracy of the model at both macroscale and microscale, confirming also the effectiveness of the multiscale modelling concept for successfully analysing physiopathological processes in biological tissues.

  1. A state space based approach to localizing single molecules from multi-emitter images.

    PubMed

    Vahid, Milad R; Chao, Jerry; Ward, E Sally; Ober, Raimund J

    2017-01-28

    Single molecule super-resolution microscopy is a powerful tool that enables imaging at sub-diffraction-limit resolution. In this technique, subsets of stochastically photoactivated fluorophores are imaged over a sequence of frames and accurately localized, and the estimated locations are used to construct a high-resolution image of the cellular structures labeled by the fluorophores. Available localization methods typically first determine the regions of the image that contain emitting fluorophores through a process referred to as detection. Then, the locations of the fluorophores are estimated accurately in an estimation step. We propose a novel localization method which combines the detection and estimation steps. The method models the given image as the frequency response of a multi-order system obtained with a balanced state space realization algorithm based on the singular value decomposition of a Hankel matrix, and determines the locations of intensity peaks in the image as the pole locations of the resulting system. The locations of the most significant peaks correspond to the locations of single molecules in the original image. Although the accuracy of the location estimates is reasonably good, we demonstrate that, by using the estimates as the initial conditions for a maximum likelihood estimator, refined estimates can be obtained that have a standard deviation close to the Cramér-Rao lower bound-based limit of accuracy. We validate our method using both simulated and experimental multi-emitter images.

  2. A state space based approach to localizing single molecules from multi-emitter images

    NASA Astrophysics Data System (ADS)

    Vahid, Milad R.; Chao, Jerry; Ward, E. Sally; Ober, Raimund J.

    2017-02-01

    Single molecule super-resolution microscopy is a powerful tool that enables imaging at sub-diffraction-limit resolution. In this technique, subsets of stochastically photoactivated fluorophores are imaged over a sequence of frames and accurately localized, and the estimated locations are used to construct a high-resolution image of the cellular structures labeled by the fluorophores. Available localization methods typically first determine the regions of the image that contain emitting fluorophores through a process referred to as detection. Then, the locations of the fluorophores are estimated accurately in an estimation step. We propose a novel localization method which combines the detection and estimation steps. The method models the given image as the frequency response of a multi-order system obtained with a balanced state space realization algorithm based on the singular value decomposition of a Hankel matrix, and determines the locations of intensity peaks in the image as the pole locations of the resulting system. The locations of the most significant peaks correspond to the locations of single molecules in the original image. Although the accuracy of the location estimates is reasonably good, we demonstrate that, by using the estimates as the initial conditions for a maximum likelihood estimator, refined estimates can be obtained that have a standard deviation close to the Cramér-Rao lower bound-based limit of accuracy. We validate our method using both simulated and experimental multi-emitter images.

  3. Non-local and nonlinear background suppression method controlled by multi-scale clutter metric

    NASA Astrophysics Data System (ADS)

    Gong, Jinnan; Hou, Qingyu; Zhang, Wei; Zhi, Xiyang

    2015-07-01

    To improve the detection performance for non-morphological multi-scale target in IR image containing complex cloud clutter, on basis of cloud scenario self-similarity feature, a non-local and nonlinear background suppression algorithm controlled by multi-scale clutter metric is presented. According to the classical achievements on cloud structure, self-similarity and relativity of cloud clutter on image for target detection is deeply analyzed by classical indicators firstly. Then we establish multi-scale clutter metric method based on LoG operator to describe scenes feature for controlled suppression method. After that, non-local means based on optimal strength similarity metric as non-local processing, and multi-scale median filter and on minimum gradient direction as local processing are set up. Finally linear fusing principle adopting clutter metric for local and non-local processing is put forward. Experimental results by two kinds of infrared imageries show that compared with classical and similar methods, the proposed method solves the existing problems of targets energy attenuation and suppression degradation in strongly evolving regions in previous methods. By evaluating indicators, the proposed method has a superior background suppression performance by increasing the BSF and ISCR 2 times at least.

  4. Advanced numerical methods and software approaches for semiconductor device simulation

    SciTech Connect

    CAREY,GRAHAM F.; PARDHANANI,A.L.; BOVA,STEVEN W.

    2000-03-23

    In this article the authors concisely present several modern strategies that are applicable to drift-dominated carrier transport in higher-order deterministic models such as the drift-diffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of upwind and artificial dissipation schemes, generalization of the traditional Scharfetter-Gummel approach, Petrov-Galerkin and streamline-upwind Petrov Galerkin (SUPG), entropy variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of the methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. They have included numerical examples from the recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and they emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, they briefly consider some aspects of software frameworks. These include dial-an-operator approaches such as that used in the industrial simulator PROPHET, and object-oriented software support such as those in the SANDIA National Laboratory framework SIERRA.

  5. Advanced Numerical Methods and Software Approaches for Semiconductor Device Simulation

    DOE PAGES

    Carey, Graham F.; Pardhanani, A. L.; Bova, S. W.

    2000-01-01

    In this article we concisely present several modern strategies that are applicable to driftdominated carrier transport in higher-order deterministic models such as the driftdiffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of “upwind” and artificial dissipation schemes, generalization of the traditional Scharfetter – Gummel approach, Petrov – Galerkin and streamline-upwind Petrov Galerkin (SUPG), “entropy” variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of themore » methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. We have included numerical examples from our recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and we emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, we briefly consider some aspects of software frameworks. These include dial-an-operator approaches such as that used in the industrial simulator PROPHET, and object-oriented software support such as those in the SANDIA National Laboratory framework SIERRA.« less

  6. A comparison of locally adaptive multigrid methods: LDC, FAC and FIC

    NASA Technical Reports Server (NTRS)

    Khadra, Khodor; Angot, Philippe; Caltagirone, Jean-Paul

    1993-01-01

    This study is devoted to a comparative analysis of three 'Adaptive ZOOM' (ZOom Overlapping Multi-level) methods based on similar concepts of hierarchical multigrid local refinement: LDC (Local Defect Correction), FAC (Fast Adaptive Composite), and FIC (Flux Interface Correction)--which we proposed recently. These methods are tested on two examples of a bidimensional elliptic problem. We compare, for V-cycle procedures, the asymptotic evolution of the global error evaluated by discrete norms, the corresponding local errors, and the convergence rates of these algorithms.

  7. Detection of Localized Heat Damage in a Polymer Matrix Composite by Thermo-Elastic Method (Preprint)

    DTIC Science & Technology

    2007-02-01

    AFRL-ML-WP-TP-2007-437 DETECTION OF LOCALIZED HEAT DAMAGE IN A POLYMER MATRIX COMPOSITE BY THERMO-ELASTIC METHOD (PREPRINT) John Welter...GRANT NUMBER 4. TITLE AND SUBTITLE DETECTION OF LOCALIZED HEAT DAMAGE IN A POLYMER MATRIX COMPOSITE BY THERMO-ELASTIC METHOD (PREPRINT) 5c...Include Area Code) N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18 1 DETECTION OF LOCALIZED HEAT DAMAGE IN A POLYMER MATRIX COMPOSITE BY

  8. Omni-Directional Scanning Localization Method of a Mobile Robot Based on Ultrasonic Sensors.

    PubMed

    Mu, Wei-Yi; Zhang, Guang-Peng; Huang, Yu-Mei; Yang, Xin-Gang; Liu, Hong-Yan; Yan, Wen

    2016-12-20

    Improved ranging accuracy is obtained by the development of a novel ultrasonic sensor ranging algorithm, unlike the conventional ranging algorithm, which considers the divergence angle and the incidence angle of the ultrasonic sensor synchronously. An ultrasonic sensor scanning method is developed based on this algorithm for the recognition of an inclined plate and to obtain the localization of the ultrasonic sensor relative to the inclined plate reference frame. The ultrasonic sensor scanning method is then leveraged for the omni-directional localization of a mobile robot, where the ultrasonic sensors are installed on a mobile robot and follow the spin of the robot, the inclined plate is recognized and the position and posture of the robot are acquired with respect to the coordinate system of the inclined plate, realizing the localization of the robot. Finally, the localization method is implemented into an omni-directional scanning localization experiment with the independently researched and developed mobile robot. Localization accuracies of up to ±3.33 mm for the front, up to ±6.21 for the lateral and up to ±0.20° for the posture are obtained, verifying the correctness and effectiveness of the proposed localization method.

  9. Omni-Directional Scanning Localization Method of a Mobile Robot Based on Ultrasonic Sensors

    PubMed Central

    Mu, Wei-Yi; Zhang, Guang-Peng; Huang, Yu-Mei; Yang, Xin-Gang; Liu, Hong-Yan; Yan, Wen

    2016-01-01

    Improved ranging accuracy is obtained by the development of a novel ultrasonic sensor ranging algorithm, unlike the conventional ranging algorithm, which considers the divergence angle and the incidence angle of the ultrasonic sensor synchronously. An ultrasonic sensor scanning method is developed based on this algorithm for the recognition of an inclined plate and to obtain the localization of the ultrasonic sensor relative to the inclined plate reference frame. The ultrasonic sensor scanning method is then leveraged for the omni-directional localization of a mobile robot, where the ultrasonic sensors are installed on a mobile robot and follow the spin of the robot, the inclined plate is recognized and the position and posture of the robot are acquired with respect to the coordinate system of the inclined plate, realizing the localization of the robot. Finally, the localization method is implemented into an omni-directional scanning localization experiment with the independently researched and developed mobile robot. Localization accuracies of up to ±3.33 mm for the front, up to ±6.21 for the lateral and up to ±0.20° for the posture are obtained, verifying the correctness and effectiveness of the proposed localization method. PMID:27999396

  10. An automated local and regional seismic event location method based on waveform stacking

    NASA Astrophysics Data System (ADS)

    Grigoli, F.; Cesca, S.; Dahm, T.

    2013-12-01

    Seismic event location using automated procedures is a very important task in microseismic monitoring as well as within early warning applications. Increasingly large datasets recorded by dense network has recently favoured the development of different automated location methods. These methods are requested to be noise robust, since microseismic records are often characterized by a low signal-to-noise ratios. Most of the aforementioned standard automated location routines rely on automated phase picking and seismic phases identification (generally only P and S) and are generally based on the minimization of the residuals between the theoretical and observed arrival times of the main seismic phases. While different developed approaches allow to accurately pick P onsets, the automatic picking of the S onsets is still challenging, and posing a significant limit to the location performance. We present here a picking free location method based on the use of different characteristic functions, able to identify P and S phases. Both characteristic functions are based on the Short-Term-Average/Long-Term-Average (STA/LTA) traces. For P phases, we use as characteristic function the STA/LTA trace of the vertical energy function, whereas for the S phases we use the STA/LTA traces of a function obtained using the Principal Component Analysis (PCA) technique. In order to locate a seismic event, the space of possible locations is scanned and both P and S characteristic functions are stacked along travel time surfaces corresponding to the selected hypocenter. Iterating this procedure on a three-dimensional grid we retrieve a multidimensional matrix whose absolute maximum corresponds tot he coordinates of the seismic event. We show the performance of our method with different applications, at different scales: 1) s set of low magnitude events recorded by a local network in southern Italy and 2) a set of seismic events recorded by a regional seismic network in Turkey. This work has

  11. [Liver abcess and biliary fistula as local complications of acute pancreatitis: approach and treatment].

    PubMed

    Quintas Lorenzo, Paola; Cubiella Fernández, Joaquín; Trillo Lista, Manuel; Fernández-Carrera Soler, Jose Manuel; Froján Parga, Purificación; Fernández Seara, Javier

    2009-01-01

    Acute pancreatitis is frequently associated with the development of local complications: collections, necrosis, pseudocysts and abdominal abscesses. Although the development of liver abscesses has been linked to bile duct obstruction or abdominal surgery in patients with chronic pancreatitis, there are few descriptions of liver abscesses associated with an episode of acute pancreatitis. We report the case of a 45-year-old man with a first episode of severe acute alcoholic pancreatitis, complicated with thrombosis of the right portal branch, liver abscess and intrahepatic biliary fistula. The approach and treatment are described.

  12. Kinetically reduced local Navier-Stokes equations: an alternative approach to hydrodynamics.

    PubMed

    Karlin, Iliya V; Tomboulides, Ananias G; Frouzakis, Christos E; Ansumali, Santosh

    2006-09-01

    An alternative approach, the kinetically reduced local Navier-Stokes (KRLNS) equations for the grand potential and the momentum, is proposed for the simulation of low Mach number flows. The Taylor-Green vortex flow is considered in the KRLNS framework, and compared to the results of the direct numerical simulation of the incompressible Navier-Stokes equations. The excellent agreement between the KRLNS equations and the incompressible nonlocal Navier-Stokes equations for this nontrivial time-dependent flow indicates that the former is a viable alternative for computational fluid dynamics at low Mach numbers.

  13. Approach-Method Interaction: The Role of Teaching Method on the Effect of Context-Based Approach in Physics Instruction

    ERIC Educational Resources Information Center

    Pesman, Haki; Ozdemir, Omer Faruk

    2012-01-01

    The purpose of this study is to explore not only the effect of context-based physics instruction on students' achievement and motivation in physics, but also how the use of different teaching methods influences it (interaction effect). Therefore, two two-level-independent variables were defined, teaching approach (contextual and non-contextual…

  14. Approach-Method Interaction: The Role of Teaching Method on the Effect of Context-Based Approach in Physics Instruction

    ERIC Educational Resources Information Center

    Pesman, Haki; Ozdemir, Omer Faruk

    2012-01-01

    The purpose of this study is to explore not only the effect of context-based physics instruction on students' achievement and motivation in physics, but also how the use of different teaching methods influences it (interaction effect). Therefore, two two-level-independent variables were defined, teaching approach (contextual and non-contextual…

  15. A FINITE ELEMENT METHOD FOR ELASTICITY INTERFACE PROBLEMS WITH LOCALLY MODIFIED TRIANGULATIONS

    PubMed Central

    XIE, HUI; LI, ZHILIN; QIAO, ZHONGHUA

    2013-01-01

    A finite element method for elasticity systems with discontinuities in the coefficients and the flux across an arbitrary interface is proposed in this paper. The method is based on a Cartesian mesh with local modifications to the mesh. The total degrees of the freedom of the finite element method remains the same as that of the Cartesian mesh. The local modifications lead to a quasi-uniform body-fitted mesh from the original Cartesian mesh. The standard finite element theory and implementation are applicable. Numerical examples that involve discontinuous material coefficients and non-homogeneous jump in the flux across the interface demonstrate the efficiency of the proposed method. PMID:24058368

  16. Assessing and evaluating multidisciplinary translational teams: a mixed methods approach.

    PubMed

    Wooten, Kevin C; Rose, Robert M; Ostir, Glenn V; Calhoun, William J; Ameredes, Bill T; Brasier, Allan R

    2014-03-01

    A case report illustrates how multidisciplinary translational teams can be assessed using outcome, process, and developmental types of evaluation using a mixed-methods approach. Types of evaluation appropriate for teams are considered in relation to relevant research questions and assessment methods. Logic models are applied to scientific projects and team development to inform choices between methods within a mixed-methods design. Use of an expert panel is reviewed, culminating in consensus ratings of 11 multidisciplinary teams and a final evaluation within a team-type taxonomy. Based on team maturation and scientific progress, teams were designated as (a) early in development, (b) traditional, (c) process focused, or (d) exemplary. Lessons learned from data reduction, use of mixed methods, and use of expert panels are explored.

  17. Local ab initio methods for calculating optical bandgaps in periodic systems. II. Periodic density fitted local configuration interaction singles method for solids.

    PubMed

    Lorenz, Marco; Maschio, Lorenzo; Schütz, Martin; Usvyat, Denis

    2012-11-28

    We present a density fitted local configuration interaction singles (CIS) method for calculating optical bandgaps in 3D-periodic systems. We employ an Ewald technique to carry out infinite lattice summations for the exciton-exciton interaction, and robust product-density specific local density fitting in direct space for the electron-hole interaction. Moreover, we propose an alternative to the usual cyclic model with Born-von Karman periodic boundary conditions, the so called Wigner-Seitz supercell truncated infinite model, which exhibits much improved convergence of the CIS excitation energy with respect to the size of the supercell. Test calculations on a series of prototypical systems demonstrate that the method at the present stage can be used to calculate the excitonic bandgaps of 3D periodic systems with up to a dozen atoms in the unit cell, ranging from wide-gap insulators to semiconductors.

  18. Adhesive restorations, centric relation, and the Dahl principle: minimally invasive approaches to localized anterior tooth erosion.

    PubMed

    Magne, Pascal; Magne, Michel; Belser, Urs C

    2007-01-01

    The purpose of this article is to review biomechanical and occlusal principles that could help optimize the conservative treatment of severely eroded and worn anterior dentition using adhesive restorations. It appears that enamel and dentin bonding, through the combined use of resin composites (on the palatal surface) and indirect porcelain veneers (on the facial/incisal surfaces) can lead to an optimal result from both esthetic and functional/biomechanical aspects. Cases of deep bite combined with palatal erosion and wear can be particularly challenging. A simplified approach is proposed through the use of an occlusal therapy combining centric relation and the Dahl principle to create anterior interocclusal space to reduce the need for more invasive palatal reduction. This approach allows the ultraconservative treatment of localized anterior tooth erosion and wear.

  19. Frequency-domain localization of alpha rhythm in humans via a maximum entropy approach

    NASA Astrophysics Data System (ADS)

    Patel, Pankaj; Khosla, Deepak; Al-Dayeh, Louai; Singh, Manbir

    1997-05-01

    Generators of spontaneous human brain activity such as alpha rhythm may be easier and more accurate to localize in frequency-domain than in time-domain since these generators are characterized by a specific frequency range. We carried out a frequency-domain analysis of synchronous alpha sources by generating equivalent potential maps using the Fourier transform of each channel of electro-encephalographic (EEG) recordings. SInce the alpha rhythm recorded by EEG scalp measurements is probably produced by several independent generators, a distributed source imaging approach was considered more appropriate than a model based on a single equivalent current dipole. We used an imaging approach based on a Bayesian maximum entropy technique. Reconstructed sources were superposed on corresponding anatomy form magnetic resonance imaging. Results from human studies suggest that reconstructed sources responsible for alpha rhythm are mainly located in the occipital and parieto- occipital lobes.

  20. An approach for drag correction based on the local heterogeneity for gas-solid flows

    SciTech Connect

    Li, Tingwen; Wang, Limin; Rogers, William; Zhou, Guofeng; Ge, Wei

    2016-09-22

    The drag models typically used for gas-solids interaction are mainly developed based on homogeneous systems of flow passing fixed particle assembly. It has been shown that the heterogeneous structures, i.e., clusters and bubbles in fluidized beds, need to be resolved to account for their effect in the numerical simulations. Since the heterogeneity is essentially captured through the local concentration gradient in the computational cells, this study proposes a simple approach to account for the non-uniformity of solids spatial distribution inside a computational cell and its effect on the interaction between gas and solid phases. Finally, to validate this approach, the predicted drag coefficient has been compared to the results from direct numerical simulations. In addition, the need to account for this type of heterogeneity is discussed for a periodic riser flow simulation with highly resolved numerical grids and the impact of the proposed correction for drag is demonstrated.

  1. An approach for drag correction based on the local heterogeneity for gas-solid flows

    DOE PAGES

    Li, Tingwen; Wang, Limin; Rogers, William; ...

    2016-09-22

    The drag models typically used for gas-solids interaction are mainly developed based on homogeneous systems of flow passing fixed particle assembly. It has been shown that the heterogeneous structures, i.e., clusters and bubbles in fluidized beds, need to be resolved to account for their effect in the numerical simulations. Since the heterogeneity is essentially captured through the local concentration gradient in the computational cells, this study proposes a simple approach to account for the non-uniformity of solids spatial distribution inside a computational cell and its effect on the interaction between gas and solid phases. Finally, to validate this approach, themore » predicted drag coefficient has been compared to the results from direct numerical simulations. In addition, the need to account for this type of heterogeneity is discussed for a periodic riser flow simulation with highly resolved numerical grids and the impact of the proposed correction for drag is demonstrated.« less

  2. [Communicative approach of Situational Strategic Planning at the local level: health and equity in Venezuela].

    PubMed

    Heredia-Martínez, Henny Luz; Artmann, Elizabeth; Porto, Silvia Marta

    2010-06-01

    The article discusses the results of operationalizing Situational Strategic Planning adapted to the local level in health, considering the communicative approach and equity in a parish in Venezuela. Two innovative criteria were used: estimated health needs and analysis of the actors' potential for participation. The problems identified were compared to the corresponding article on rights in the Venezuelan Constitution. The study measured inequalities using health indicators associated with the selected problems; equity criteria were incorporated into the action proposals and communicative elements. Priority was assigned to the problem of "low case-resolving capacity in the health services network", and five critical points were selected for the action plan, which finally consisted of 6 operations and 21 actions. The article concludes that the combination of epidemiology and planning expands the situational explanation. Incorporation of the communicative approach and the equity dimension into Situational Strategic Planning allows empowering health management and helps decrease the gaps from inequality.

  3. Meshless Local Petrov-Galerkin Euler-Bernoulli Beam Problems: A Radial Basis Function Approach

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Phillips, D. R.; Krishnamurthy, T.

    2003-01-01

    A radial basis function implementation of the meshless local Petrov-Galerkin (MLPG) method is presented to study Euler-Bernoulli beam problems. Radial basis functions, rather than generalized moving least squares (GMLS) interpolations, are used to develop the trial functions. This choice yields a computationally simpler method as fewer matrix inversions and multiplications are required than when GMLS interpolations are used. Test functions are chosen as simple weight functions as in the conventional MLPG method. Compactly and noncompactly supported radial basis functions are considered. The non-compactly supported cubic radial basis function is found to perform very well. Results obtained from the radial basis MLPG method are comparable to those obtained using the conventional MLPG method for mixed boundary value problems and problems with discontinuous loading conditions.

  4. Roundness deviation evaluation method based on statistical analysis of local least square circles

    NASA Astrophysics Data System (ADS)

    Zhi-min, Cao; Yun, Wu; Jian, Han

    2017-10-01

    Today, the quantitative evaluation of the quality of circular or cylindrical workpieces is becoming increasingly important for the relevant industrial production sectors. Although there are already some roundness deviation evaluation algorithms available to accomplish this task, these methods are always done in a holistic way. In many industrial scenarios, however, fine evaluation of the roundness variation of local segments is often more practical than the global assessment. By performing a fine evaluation of roundness variation of local segments, crucial information that can reveal intrinsic quality characteristics of both the workpiece and the production machine can be retrieved. However, this important issue has not been well studied. To deal with this problem, a roundness deviation evaluation method based on statistical analysis of local least square circles was proposed. Experimental results illustrated that the proposed method can stably and reliably evaluate the local and global roundness deviations effectively.

  5. Estimation of local scale dispersion from local breakthrough curves during a tracer test in a heterogeneous aquifer: the Lagrangian approach.

    PubMed

    Vanderborght, Jan; Vereecken, Harry

    2002-01-01

    The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.

  6. Global vs. Localized Search: A Comparison of Database Selection Methods in a Hierarchical Environment.

    ERIC Educational Resources Information Center

    Conrad, Jack G.; Claussen, Joanne Smestad; Yang, Changwen

    2002-01-01

    Compares standard global information retrieval searching with more localized techniques to address the database selection problem that users often have when searching for the most relevant database, based on experiences with the Westlaw Directory. Findings indicate that a browse plus search approach in a hierarchical environment produces the most…

  7. A Local Region of Interest Imaging Method for Electrical Impedance Tomography with Internal Electrodes

    PubMed Central

    Kwon, Hyeuknam; McEwan, Alistair L.; Oh, Tong In; Farooq, Adnan; Woo, Eung Je

    2013-01-01

    Electrical Impedance Tomography (EIT) is a very attractive functional imaging method despite the low sensitivity and resolution. The use of internal electrodes with the conventional reconstruction algorithms was not enough to enhance image resolution and accuracy in the region of interest (ROI). We propose a local ROI imaging method with internal electrodes developed from careful analysis of the sensitivity matrix that is designed to reduce the sensitivity of the voxels outside the local region and optimize the sensitivity of the voxel inside the local region. We perform numerical simulations and physical measurements to demonstrate the localized EIT imaging method. In preliminary results with multiple objects we show the benefits of using an internal electrode and the improved resolution due to the local ROI image reconstruction method. The sensitivity is further increased by allowing the surface electrodes to be unevenly spaced with a higher density of surface electrodes near the ROI. Also, we analyse how much the image quality is improved using several performance parameters for comparison. While these have not yet been studied in depth, it convincingly shows an improvement in local sensitivity in images obtained with an internal electrode in comparison to a standard reconstruction method. PMID:23935705

  8. A mixed-methods approach to systematic reviews.

    PubMed

    Pearson, Alan; White, Heath; Bath-Hextall, Fiona; Salmond, Susan; Apostolo, Joao; Kirkpatrick, Pamela

    2015-09-01

    There are an increasing number of published single-method systematic reviews that focus on different types of evidence related to a particular topic. As policy makers and practitioners seek clear directions for decision-making from systematic reviews, it is likely that it will be increasingly difficult for them to identify 'what to do' if they are required to find and understand a plethora of syntheses related to a particular topic.Mixed-methods systematic reviews are designed to address this issue and have the potential to produce systematic reviews of direct relevance to policy makers and practitioners.On the basis of the recommendations of the Joanna Briggs Institute International Mixed Methods Reviews Methodology Group in 2012, the Institute adopted a segregated approach to mixed-methods synthesis as described by Sandelowski et al., which consists of separate syntheses of each component method of the review. Joanna Briggs Institute's mixed-methods synthesis of the findings of the separate syntheses uses a Bayesian approach to translate the findings of the initial quantitative synthesis into qualitative themes and pooling these with the findings of the initial qualitative synthesis.

  9. Robust extraction of local structures by the minimum beta-divergence method.

    PubMed

    Mollah, Md Nurul Haque; Sultana, Nayeema; Minami, Mihoko; Eguchi, Shinto

    2010-03-01

    This paper discusses a new highly robust learning algorithm for exploring local principal component analysis (PCA) structures in which an observed data follow one of several heterogeneous PCA models. The proposed method is formulated by minimizing beta-divergence. It searches a local PCA structure based on an initial location of the shifting parameter and a value for the tuning parameter beta. If the initial choice of the shifting parameter belongs to a data cluster, then the proposed method detects the local PCA structure of that data cluster, ignoring data in other clusters as outliers. We discuss the selection procedures for the tuning parameter beta and the initial value of the shifting parameter mu in this article. We demonstrate the performance of the proposed method by simulation. Finally, we compare the proposed method with a method based on a finite mixture model.

  10. Localization of causal locus in the genome of the brown macroalga Ectocarpus: NGS-based mapping and positional cloning approaches.

    PubMed

    Billoud, Bernard; Jouanno, Émilie; Nehr, Zofia; Carton, Baptiste; Rolland, Élodie; Chenivesse, Sabine; Charrier, Bénédicte

    2015-01-01

    Mutagenesis is the only process by which unpredicted biological gene function can be identified. Despite that several macroalgal developmental mutants have been generated, their causal mutation was never identified, because experimental conditions were not gathered at that time. Today, progresses in macroalgal genomics and judicious choices of suitable genetic models make mutated gene identification possible. This article presents a comparative study of two methods aiming at identifying a genetic locus in the brown alga Ectocarpus siliculosus: positional cloning and Next-Generation Sequencing (NGS)-based mapping. Once necessary preliminary experimental tools were gathered, we tested both analyses on an Ectocarpus morphogenetic mutant. We show how a narrower