WorldWideScience
1

Adaptive centroid-finding algorithm for freeform surface measurements.  

Science.gov (United States)

Wavefront sensing systems measure the slope or curvature of a surface by calculating the centroid displacement of two focal spot images. Accurately finding the centroid of each focal spot determines the measurement results. This paper studied several widely used centroid-finding techniques and observed that thresholding is the most critical factor affecting the centroid-finding accuracy. Since the focal spot image of a freeform surface usually suffers from various types of image degradation, it is difficult and sometimes impossible to set a best threshold value for the whole image. We propose an adaptive centroid-finding algorithm to tackle this problem and have experimentally proven its effectiveness in measuring freeform surfaces. PMID:23545985

Guo, Wenjiang; Zhao, Liping; Tong, Chin Shi; I-Ming, Chen; Joshi, Sunil Chandrakant

2013-04-01

2

Immune Centroids Oversampling Method for Binary Classification  

Science.gov (United States)

To improve the classification performance of imbalanced learning, a novel oversampling method, immune centroids oversampling technique (ICOTE) based on an immune network, is proposed. ICOTE generates a set of immune centroids to broaden the decision regions of the minority class space. The representative immune centroids are regarded as synthetic examples in order to resolve the imbalance problem. We utilize an artificial immune network to generate synthetic examples on clusters with high data densities, which can address the problem of synthetic minority oversampling technique (SMOTE), which lacks reflection on groups of training examples. Meanwhile, we further improve the performance of ICOTE via integrating ENN with ICOTE, that is, ICOTE + ENN. ENN disposes the majority class examples that invade the minority class space, so ICOTE + ENN favors the separation of both classes. Our comprehensive experimental results show that two proposed oversampling methods can achieve better performance than the renowned resampling methods. PMID:25834570

Ai, Xusheng; Wu, Jian; Cui, Zhiming

2015-01-01

3

Enhancing K-Means Algorithm with Semi-Unsupervised Centroid Selection Method  

OpenAIRE

The k-means algorithm is one of the frequently used clustering methods in data mining, due to its performance in clustering massive data sets. The final clustering result of the kmeans clustering algorithm is based on the correctness of the initial centroids, which are selected randomly. The original k-means algorithm converges to local minimum, not the global optimum. The k-means clustering performance can be enhanced if the initial cluster centers are found. To find the initial cluster cent...

Shanmugasundaram, R.; Sukumaran, S.

2010-01-01

4

Expand the measurement range of a critical angle refractometer by a centroid method for transparent fluids  

Science.gov (United States)

A simple approach to expand the measurement range of a critical angle refractometer (CAR) is demonstrated. Our method is based on measuring the centroid point of the angular reflective ratio of the CAR. According to the Snell's reflective law, the CAR with a divergent beam source has a limited measurement range. When the refractive index (RI) is higher than the upper limit, the reflective ratio curve is gradual changing without cutoff edge between the total internal reflection (TIR) and non-TIR. We find that the centroid point of the gradual changing curve is associated with the RI value of a liquid. Theorectical analysis and experimental results on sugar solutions with RI that varying from 1.359 to 1.3766 show that this method is effective and accurate to expand the measurement range.

Ye, Junwei; Yang, Kecheng; Liu, Hao; Dai, Jie; Guo, Wenping; Li, Wei; Xia, Min

2015-01-01

5

A Method for Analog Implementation of Centroid Tracking Algorithm in a Video Signal  

Directory of Open Access Journals (Sweden)

Full Text Available The main goal of a video tracking algorithm is finding the location of a predefined target in successive video frames. Centroid pointing is one of the most efficient methods in the target tracking. This method can be simply implemented by a digital video processing system that includes a video memory and a powerful digital processor. Usually, the cost and the complexity of the digital video processor is high and in some applications, using analog video processor that includes only electronic devices like OPAMP, diodes, transistors, resistors and capacitors has lower cost, more efficient and more reliable. Implementing of the centroid in an analog video processor is not as simple as digital one, therefore in this paper, we introduce a novel formulation of the centroid that can be implemented in an analog video processor. We simulate the proposed method by MatLab simulink and compare the results with the area-based tracking that is usually used in analog video processors. The simulation results show that the proposed method is more reliable and accurate.

Payman Moallem

2007-06-01

6

Alteração no método centroide de avaliação da adaptabilidade genotípica Alteration of the centroid method to evaluate genotypic adaptability  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste trabalho foi alterar o método centroide de avaliação da adaptabilidade e estabilidade fenotípica de genótipos, para deixá-lo com maior sentido biológico e melhorar aspectos quantitativos e qualitativos de sua análise. A alteração se deu pela adição de mais três ideótipos, definidos de acordo com valores médios dos genótipos nos ambientes. Foram utilizados dados provenientes de um experimento sobre produção de matéria seca de 92 genótipos de alfafa (Medicago sativa realizado em blocos ao acaso, com duas repetições. Os genótipos foram submetidos a 20 cortes, no período de novembro de 2004 a junho de 2006. Cada corte foi considerado um ambiente. A inclusão dos ideótipos de maior sentido biológico (valores médios nos ambientes resultou em uma dispersão gráfica em forma de uma seta voltada para a direita, na qual os genótipos mais produtivos ficaram próximos à ponta da seta. Com a alteração, apenas cinco genótipos foram classificados nas mesmas classes do método centroide original. A figura em forma de seta proporciona uma comparação direta dos genótipos, por meio da formação de um gradiente de produtividade. A alteração no método mantém a facilidade de interpretação dos resultados para a recomendação dos genótipos presente no método original e não permite duplicidade de interpretação dos resultados.ABSTRACT The objective of this work was to modify the centroid method of evaluation of phenotypic adaptability and the phenotype stability of genotypes in order for the method to make greater biological sense and improve its quantitative and qualitative performance. The method was modified by means of the inclusion of three additional ideotypes defined in accordance with the genotypes' average yield in the environments tested. The alfalfa (Medicago sativa L. forage yield of 92 genotypes was used. The trial had a randomized block design, with two replicates, and the data were used to test the method. The genotypes underwent 20 cuts, from November 2004 to June 2006. Each cut was considered an environment. The inclusion of ideotypes of greater biological average production in the environments produced an arrow-shaped graphical dispersion directed to the right in which the most productive genotypes were placed near the tip of the arrow. With the alteration only five genotypes were classified into the former classes of the original centroid method. The arrow-shaped figure allowed a direct comparison of genotypes throughout the productivity gradient. The alteration performed in the method preserved the easy interpretation of results for genotype recommendations of the original method, and does leaves no room for ambiguity in interpretation of the results.

Moysés Nascimento

2009-03-01

7

Alteração no método centroide de avaliação da adaptabilidade genotípica / Alteration of the centroid method to evaluate genotypic adaptability  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi alterar o método centroide de avaliação da adaptabilidade e estabilidade fenotípica de genótipos, para deixá-lo com maior sentido biológico e melhorar aspectos quantitativos e qualitativos de sua análise. A alteração se deu pela adição de mais três ideótipos, definidos [...] de acordo com valores médios dos genótipos nos ambientes. Foram utilizados dados provenientes de um experimento sobre produção de matéria seca de 92 genótipos de alfafa (Medicago sativa) realizado em blocos ao acaso, com duas repetições. Os genótipos foram submetidos a 20 cortes, no período de novembro de 2004 a junho de 2006. Cada corte foi considerado um ambiente. A inclusão dos ideótipos de maior sentido biológico (valores médios nos ambientes) resultou em uma dispersão gráfica em forma de uma seta voltada para a direita, na qual os genótipos mais produtivos ficaram próximos à ponta da seta. Com a alteração, apenas cinco genótipos foram classificados nas mesmas classes do método centroide original. A figura em forma de seta proporciona uma comparação direta dos genótipos, por meio da formação de um gradiente de produtividade. A alteração no método mantém a facilidade de interpretação dos resultados para a recomendação dos genótipos presente no método original e não permite duplicidade de interpretação dos resultados. Abstract in english ABSTRACT The objective of this work was to modify the centroid method of evaluation of phenotypic adaptability and the phenotype stability of genotypes in order for the method to make greater biological sense and improve its quantitative and qualitative performance. The method was modified by means [...] of the inclusion of three additional ideotypes defined in accordance with the genotypes' average yield in the environments tested. The alfalfa (Medicago sativa L.) forage yield of 92 genotypes was used. The trial had a randomized block design, with two replicates, and the data were used to test the method. The genotypes underwent 20 cuts, from November 2004 to June 2006. Each cut was considered an environment. The inclusion of ideotypes of greater biological average production in the environments produced an arrow-shaped graphical dispersion directed to the right in which the most productive genotypes were placed near the tip of the arrow. With the alteration only five genotypes were classified into the former classes of the original centroid method. The arrow-shaped figure allowed a direct comparison of genotypes throughout the productivity gradient. The alteration performed in the method preserved the easy interpretation of results for genotype recommendations of the original method, and does leaves no room for ambiguity in interpretation of the results.

Moysés, Nascimento; Cosme Damião, Cruz; Ana Carolina Mota, Campana; Rafael Simões, Tomaz; Caio Césio, Salgado; Reinaldo de Paula, Ferreira.

2009-03-01

8

A further investigation of the centroid-to-centroid method for stereotactic lung radiotherapy: A phantom study  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Our previous study [B. Lu et al., “A patient alignment solution for lung SBRT setups based on a deformable registration technique,” Med. Phys. 39(12), 7379–7389 (2012)] proposed a deformable-registration-based patient setup strategy called the centroid-to-centroid (CTC) method, which can perform an accurate alignment of internal-target-volume (ITV) centroids between averaged four-dimensional computed tomography and cone-beam computed tomography (CBCT) images. Scenarios with variations between CBCT and simulation CT caused by irregular breathing and/or tumor change were not specifically considered in the patient study [B. Lu et al., “A patient alignment solution for lung SBRT setups based on a deformable registration technique,” Med. Phys. 39(12), 7379–7389 (2012)] due to the lack of both a sufficiently large patient data sample and a method of tumor tracking. The aim of this study is to thoroughly investigate and compare the impacts of breathing pattern and tumor change on both the CTC and the translation-only (T-only) gray-value mode strategies by employing a four-dimensional (4D) lung phantom.Methods: A sophisticated anthropomorphic 4D phantom (CIRS Dynamic Thorax Phantom model 008) was employed to simulate all desired respiratory variations. The variation scenarios were classified into four groups: inspiration to expiration ratio (IE ratio) change, tumor trajectory change, tumor position change, tumor size change, and the combination of these changes. For each category the authors designed several scenarios to demonstrate the effects of different levels of breathing variation on both of the T-only and the CTC methods. Each scenario utilized 4DCT and CBCT scans. The ITV centroid alignment discrepancies for CTC and T-only were evaluated. The dose-volume-histograms (DVHs) of ITVs for two extreme cases were analyzed.Results: Except for some extreme cases in the combined group, the accuracy of the CTC registration was about 2 mm for all cases for both the single and the combined scenarios. The performance of the CTC method was insensitive to region-of-registration (ROR) size selections, as suggested by the comparable accuracy between 1 and 2 cm expansions of the ROR selections for the method. The T-only method was suitable for some single scenarios, such as trajectory variation, position variation, and size variation. However, for combined scenarios and/or a large variation in the IE ratio, the T-only method failed to produce reasonable registration results (within 3 mm). The discrepancy was close to, or even greater than, 1 cm. In addition, unlike the CTC method, the T-only method was sensitive to the ROR size selection. The DVH analysis suggested that a large ITV to PTV margin should be considered if a breathing pattern variation is observed.Conclusions: The phantom study demonstrated that the CTC method was reliable for scenarios in which breathing pattern variation was involved. The T-only gray value method worked for some scenarios, but not for scenarios that involved an IE ratio variation. For scenarios involving position variation, the T-only method worked only with a careful selection of the ROR, whereas the CTC method was independent of ROR size as long as the ITVs were included in the ROR. One indication of the dose consequence analysis was that a large ITV to PTV margin should be considered if a breathing pattern variation is observed.

Lu, Bo; Samant, Sanjiv; Mittauer, Kathryn; Lee, Soyoung; Huang, Yin; Li, Jonathan; Kahler, Darren; Liu, Chihray [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32610 (United States)

2013-10-15

9

A further investigation of the centroid-to-centroid method for stereotactic lung radiotherapy: A phantom study  

International Nuclear Information System (INIS)

Purpose: Our previous study [B. Lu et al., “A patient alignment solution for lung SBRT setups based on a deformable registration technique,” Med. Phys. 39(12), 7379–7389 (2012)] proposed a deformable-registration-based patient setup strategy called the centroid-to-centroid (CTC) method, which can perform an accurate alignment of internal-target-volume (ITV) centroids between averaged four-dimensional computed tomography and cone-beam computed tomography (CBCT) images. Scenarios with variations between CBCT and simulation CT caused by irregular breathing and/or tumor change were not specifically considered in the patient study [B. Lu et al., “A patient alignment solution for lung SBRT setups based on a deformable registration technique,” Med. Phys. 39(12), 7379–7389 (2012)] due to the lack of both a sufficiently large patient data sample and a method of tumor tracking. The aim of this study is to thoroughly investigate and compare the impacts of breathing pattern and tumor change on both the CTC and the translation-only (T-only) gray-value mode strategies by employing a four-dimensional (4D) lung phantom.Methods: A sophisticated anthropomorphic 4D phantom (CIRS Dynamic Thorax Phantom model 008) was employed to simulate all desired respiratory variations. The variation scenarios were classified into four groups: inspiration to expiration ratio (IE ratio) change, tumor trajectory change, tumor position change, tumor size change, and the combination of these changes. For each category the authors designed several scenarios to demonstrate the effects of different levels of breathing variation on both of the T-only and the CTC methods. Each scenario utilized 4DCT and CBCT scans. The ITV centroid alignment discrepancies for CTC and T-only were evaluated. The dose-volume-histograms (DVHs) of ITVs for two extreme cases were analyzed.Results: Except for some extreme cases in the combined group, the accuracy of the CTC registration was about 2 mm for all cases for both the single and the combined scenarios. The performance of the CTC method was insensitive to region-of-registration (ROR) size selections, as suggested by the comparable accuracy between 1 and 2 cm expansions of the ROR selections for the method. The T-only method was suitable for some single scenarios, such as trajectory variation, position variation, and size variation. However, for combined scenarios and/or a large variation in the IE ratio, the T-only method failed to produce reasonable registration results (within 3 mm). The discrepancy was close to, or even greater than, 1 cm. In addition, unlike the CTC method, the T-only method was sensitive to the ROR size selection. The DVH analysis suggested that a large ITV to PTV margin should be considered if a breathing pattern variation is observed.Conclusions: The phantom study demonstrated that the CTC method was reliable for scenarios in which breathing pattern variation was involved. The T-only gray value method worked for some scenarios, but not for scenarios that involved an IE ratio variation. For scenarios involving position variation, the T-only method worked only with a careful selection of the ROR, whereas the CTC method was independent of ROR size as long as the ITVs were included in the ROR. One indication of the dose consequence analysis was that a large ITV to PTV margin should be considered if a breathing pattern variation is observed

10

Star sub-pixel centroid calculation based on multi-step minimum energy difference method  

Science.gov (United States)

The star's centroid plays a vital role in celestial navigation, star images which be gotten during daytime, due to the strong sky background, have a low SNR, and the star objectives are nearly submerged in the background, takes a great trouble to the centroid localization. Traditional methods, such as a moment method, weighted centroid calculation method is simple but has a big error, especially in the condition of a low SNR. Gaussian method has a high positioning accuracy, but the computational complexity. Analysis of the energy distribution in star image, a location method for star target centroids based on multi-step minimum energy difference is proposed. This method uses the linear superposition to narrow the centroid area, in the certain narrow area uses a certain number of interpolation to pixels for the pixels' segmentation, and then using the symmetry of the stellar energy distribution, tentatively to get the centroid position: assume that the current pixel is the star centroid position, and then calculates and gets the difference of the sum of the energy which in the symmetric direction(in this paper we take the two directions of transverse and longitudinal) and the equal step length(which can be decided through different conditions, the paper takes 9 as the step length) of the current pixel, and obtain the centroid position in this direction when the minimum difference appears, and so do the other directions, then the validation comparison of simulated star images, and compare with several traditional methods, experiments shows that the positioning accuracy of the method up to 0.001 pixel, has good effect to calculate the centroid of low SNR conditions; at the same time, uses this method on a star map which got at the fixed observation site during daytime in near-infrared band, compare the results of the paper's method with the position messages which were known of the star, it shows that :the multi-step minimum energy difference method achieves a better effect.

Wang, Duo; Han, YanLi; Sun, Tengfei

2013-09-01

11

Statistical analysis of x-ray stress measurement by centroid method  

International Nuclear Information System (INIS)

The X-ray technique allows a nondestructive and rapid measurement of residual stresses in metallic materials. The centroid method has an advantage over other X-ray methods in that it can determine the angular position of a diffraction line, from which the stress is calculated, even with an asymmetrical line profile. An equation for the standard deviation of the angular position of a diffraction line, ?sub(p), caused by statistical fluctuation was derived, which is a fundamental source of scatter in X-ray stress measurements. This equation shows that an increase of X-ray counts by a factor of k results in a decrease of ?sub(p) by a factor of 1/?k. It also shows that ?sub(p) increases rapidly as the angular range used in calculating the centroid increases. It is therefore important to calculate the centroid using the narrow angular range between the two ends of the diffraction line where it starts to deviate from the straight background line. By using quenched structural steels JIS S35C and S45C, the residual stresses and their standard deviations were calculated by the centroid, parabola, Gaussian curve, and half-width methods, and the results were compared. The centroid of a diffraction line was affected greatly by the background line used. The standard deviation of the stress measured by the centroid method was found to be the largest among the four methods. (author)

12

Optimal Citing Of Distribution Generation Units In Distribution Networks Based On Load Centroid Method  

OpenAIRE

The Distribution System Load Flow (DSLF) methods take special care to overcome the ill- conditioned nature arising due to high R/X ratios of the feeders, which makes the fast decoupled Newton method often not valid. The DSLF methods also exploit the radial nature of the distribution networks. Centroid method of Distribution Load Flow Extensive research has been conducted to identify optimal DG allocation. Almost All known methods model the task as an optimization problem based on certain obje...

Prema Kumar, N.; Rosalina, K. M.

2013-01-01

13

Noninvasive measurement of cardiopulmonary blood volume: evaluation of the centroid method  

International Nuclear Information System (INIS)

Cardiopulmonary blood volume (CPV) and mean pulmonary transit time (MTT) determined by radionuclide measurements (Tc-99m HSA) were compared with values obtained from simultaneous dye-dilution (DD) studies (indocyanine green). The mean transit time was obtained from radionuclide curves by two methods: the peak-to-peak time and the interval between the two centroids determined from the right and left-ventricular time-concentration curves. Correlation of dye-dilution MTT and peak-to-peak time was significant (r = 0.79, p < 0.001), but its correlation with centroid-derived values was better (r = 0.86, p < 0.001). CPV values (using the centroid method for radionuclide technique) correlated significantly with values derived from dye-dilution curves (r = 0.74, p < 0.001). Discrepancies between the two were greater the more rapid the circulation (r = 0.61, p < 0.01), suggesting that minor inaccuracies of dye-dilution methods, due to positioning or delay of the system, can become magnified in hyperkinetic conditions. The radionuclide method is simple, repeatable, and noninvasive, and it provides simultaneous evaluation of pulmonary and systemic hemodynamics. Further, calculation of the ratio of cardiopulmonary to total blood volume can be used as an index of overall venous distensibility and relocation of intravascular blood volume

14

Noninvasive measurement of cardiopulmonary blood volume: evaluation of the centroid method  

Energy Technology Data Exchange (ETDEWEB)

Cardiopulmonary blood volume (CPV) and mean pulmonary transit time (MTT) determined by radionuclide measurements (Tc-99m HSA) were compared with values obtained from simultaneous dye-dilution (DD) studies (indocyanine green). The mean transit time was obtained from radionuclide curves by two methods: the peak-to-peak time and the interval between the two centroids determined from the right and left-ventricular time-concentration curves. Correlation of dye-dilution MTT and peak-to-peak time was significant (r = 0.79, p < 0.001), but its correlation with centroid-derived values was better (r = 0.86, p < 0.001). CPV values (using the centroid method for radionuclide technique) correlated significantly with values derived from dye-dilution curves (r = 0.74, p < 0.001). Discrepancies between the two were greater the more rapid the circulation (r = 0.61, p < 0.01), suggesting that minor inaccuracies of dye-dilution methods, due to positioning or delay of the system, can become magnified in hyperkinetic conditions. The radionuclide method is simple, repeatable, and noninvasive, and it provides simultaneous evaluation of pulmonary and systemic hemodynamics. Further, calculation of the ratio of cardiopulmonary to total blood volume can be used as an index of overall venous distensibility and relocation of intravascular blood volume.

Fouad, F.M.; MacIntyre, W.J.; Tarazi, R.C.

1981-03-01

15

Shack-Hartmann centroid detection method based on high dynamic range imaging and normalization techniques  

International Nuclear Information System (INIS)

In the optical quality measuring process of an optical system, including diamond-turning components, the use of a laser light source can produce an undesirable speckle effect in a Shack-Hartmann (SH) CCD sensor. This speckle noise can deteriorate the precision and accuracy of the wavefront sensor measurement. Here we present a SH centroid detection method founded on computer-based techniques and capable of measurement in the presence of strong speckle noise. The method extends the dynamic range imaging capabilities of the SH sensor through the use of a set of different CCD integration times. The resultant extended range spot map is normalized to accurately obtain the spot centroids. The proposed method has been applied to measure the optical quality of the main optical system (MOS) of the mid-infrared instrument telescope smulator. The wavefront at the exit of this optical system is affected by speckle noise when it is illuminated by a laser source and by air turbulence because it has a long back focal length (3017 mm). Using the proposed technique, the MOS wavefront error was measured and satisfactory results were obtained.

16

A multi-resolution method for climate system modeling: application of Spherical Centroidal A multi-resolution method for climate system modeling: Application of Spherical Centroidal Voroni Tessellations  

Energy Technology Data Exchange (ETDEWEB)

During the next decade and beyond, climate system models will be challenged to resolve scales and processes that are far beyond their current scope. Each climate system component has its prototypical example of an unresolved process that may strongly influence the global climate system, ranging from eddy activity within ocean models, to ice streams within ice sheet models, to surface hydrological processes within land system models, to cloud processes within atmosphere models. These new demands will almost certainly result in the develop of multi-resolution schemes that are able, at least regional to faithfully simulate these fine-scale processes. Spherical Centroidal Voronoi Tessellations (SCVTs) offer one potential path toward the development of robust, multi-resolution climate system component models, SCVTs allow for the generation of high quality Voronoi diagrams and Delaunay triangulations through the use of an intuitive, user-defined density function, each of the examples provided, this method results in high-quality meshes where the quality measures are guaranteed to improve as the number of nodes is increased. Real-world examples are developed for the Greenland ice sheet and the North Atlantic ocean. Idealized examples are developed for ocean-ice shelf interaction and for regional atmospheric modeling. In addition to defining, developing and exhibiting SCVTs, we pair this mesh generation technique with a previously developed finite-volume method. Our numerical example is based on the nonlinear shallow-water equations spanning the entire surface of the sphere. This example is used to elucidate both the potential benefits of this multi-resolution method and the challenges ahead.

Ringler, Todd D [Los Alamos National Laboratory; Gunzburger, Max [FLORIDA STATE UNIV; Ju, Lili [UNIV OF SOUTH CAROLINA

2008-01-01

17

Localization Methods of Weighted Centroid of dBZ on Weather-Radar Echo Maps in Vector Format  

OpenAIRE

Fast generation of weather-radar echo maps in vector format and accurate localization of weighted centroid of dBZ (dBZ stands for decibels of reflectivity of a radar signal reflected off a remote object) are the basis of studying the characteristic tracking algorithms which are based on the vector echoes. The authors principally studied the approach to generating the vector echo map, and discussed the localization methods of weighted centroid of dBZ on vector echo maps. First, based on the tr...

Xue-tao Yu; Xiao-ping Rui; Feng Li

2013-01-01

18

Comparison of pure and 'Latinized' centroidal Voronoi tessellation against various other statistical sampling methods  

International Nuclear Information System (INIS)

A recently developed centroidal Voronoi tessellation (CVT) sampling method is investigated here to assess its suitability for use in statistical sampling applications. CVT efficiently generates a highly uniform distribution of sample points over arbitrarily shaped M-dimensional parameter spaces. On several 2-D test problems CVT has recently been found to provide exceedingly effective and efficient point distributions for response surface generation. Additionally, for statistical function integration and estimation of response statistics associated with uniformly distributed random-variable inputs (uncorrelated), CVT has been found in initial investigations to provide superior points sets when compared against latin-hypercube and simple-random Monte Carlo methods and Halton and Hammersley quasi-random sequence methods. In this paper, the performance of all these sampling methods and a new variant ('Latinized' CVT) are further compared for non-uniform input distributions. Specifically, given uncorrelated normal inputs in a 2-D test problem, statistical sampling efficiencies are compared for resolving various statistics of response: mean, variance, and exceedence probabilities

19

Localization Methods of Weighted Centroid of dBZ on Weather-Radar Echo Maps in Vector Format  

Directory of Open Access Journals (Sweden)

Full Text Available Fast generation of weather-radar echo maps in vector format and accurate localization of weighted centroid of dBZ (dBZ stands for decibels of reflectivity of a radar signal reflected off a remote object are the basis of studying the characteristic tracking algorithms which are based on the vector echoes. The authors principally studied the approach to generating the vector echo map, and discussed the localization methods of weighted centroid of dBZ on vector echo maps. First, based on the traditional calculation method on raster echo data, some new localization methods of weighted centroid of dBZ on vector echo data were proposed by considering the weights of features’ area and distance from their location to radar center. Second, taking the base reflectivity products of CINRAD/SA weather radar in Meizhou city of China as data sources, they illustrated the storage structure of this type of echo data and studied the drawing mode of changing this type of data into vector format files under the polar coordinate system in detail. Third, using the same vector echo maps created by the above method, the weighted centroid of the same area was calculated by the above localization methods. In the end, Compared with the calculated value of the same area by traditional method which is based on raster echo maps, the three new calculated results and the sources of error were analyzed in detail and two conclusions were drawn: the echo’s precision in vector format is much higher than that in raster format and it is more accurate to take the features’ area and distance to radar center as weights during the calculation of weighted centroid of dBZ on echo maps in vector format.

Xue-tao Yu

2013-02-01

20

A walk-free centroid method for lifetime measurements with pulsed beams  

International Nuclear Information System (INIS)

A delayed-coincidence lifetime measurement method based on a comparison of walk-free centroids of time spectra is presented. The time is measured between the cyclotron RF signal and the pulse from a plastic scintillation detector followed by a fixed energy selection. The events to be time-analyzed are selected from the associated charge-particle spectrum of a silicon detector which is operated in coincidence with the scintillator, i.e., independently of the formation of the signal containing the time information. With this technique, with the micropulse FWHM of typically 500 to 700 ps, half-lives down to the 10 ps region can be measured. The following half-lives are obtained with the new method: 160+-6 ps for the 2032 keV level in 209Pb; 45+-10 ps and 160+-20 ps for the 1756.8 keV (02+) and 2027.3 keV (03+) levels in 116Sn, respectively. (author)

21

A multi-resolution method for climate system modeling: application of spherical centroidal Voronoi tessellations  

Energy Technology Data Exchange (ETDEWEB)

During the next decade and beyond, climate system models will be challenged to resolve scales and processes that are far beyond their current scope. Each climate system component has its prototypical example of an unresolved process that may strongly influence the global climate system, ranging from eddy activity within ocean models, to ice streams within ice sheet models, to surface hydrological processes within land system models, to cloud processes within atmosphere models. These new demands will almost certainly result in the develop of multiresolution schemes that are able, at least regionally, to faithfully simulate these fine-scale processes. Spherical centroidal Voronoi tessellations (SCVTs) offer one potential path toward the development of a robust, multiresolution climate system model components. SCVTs allow for the generation of high quality Voronoi diagrams and Delaunay triangulations through the use of an intuitive, user-defined density function. In each of the examples provided, this method results in high-quality meshes where the quality measures are guaranteed to improve as the number of nodes is increased. Real-world examples are developed for the Greenland ice sheet and the North Atlantic ocean. Idealized examples are developed for ocean–ice shelf interaction and for regional atmospheric modeling. In addition to defining, developing, and exhibiting SCVTs, we pair this mesh generation technique with a previously developed finite-volume method. Our numerical example is based on the nonlinear, shallow water equations spanning the entire surface of the sphere. This example is used to elucidate both the potential benefits of this multiresolution method and the challenges ahead.

Ringler, Todd [Los Alamos National Laboratory; Ju, Lili [University of South Carolina; Gunzburger, Max [Florida State University

2008-01-01

22

Measurement Precision and Accuracy of the Centre Location of AN Ellipse by Weighted Centroid Method  

Science.gov (United States)

Circular targets are often utilized in photogrammetry, and a circle on a plane is projected as an ellipse onto an oblique image. This paper reports an analysis conducted in order to investigate the measurement precision and accuracy of the centre location of an ellipse on a digital image by an intensity-weighted centroid method. An ellipse with a semi-major axis a, a semi-minor axis b, and a rotation angle ? of the major axis is investigated. In the study an equivalent radius r = (a2cos2? + b2sin2?)1/2 is adopted as a measure of the dimension of an ellipse. First an analytical expression representing a measurement error (ϵx, ϵy,) is obtained. Then variances Vx of ϵx are obtained at 1/256 pixel intervals from 0.5 to 100 pixels in r by numerical integration, because a formula representing Vx is unable to be obtained analytically when r > 0.5. The results of the numerical integration indicate that Vxwould oscillate in a 0.5 pixel cycle in r and Vx excluding the oscillation component would be inversely proportional to the cube of r. Finally an effective approximate formula of Vx from 0.5 to 100 pixels in r is obtained by least squares adjustment. The obtained formula is a fractional expression of which numerator is a fifth-degree polynomial of {r-0.5×int(2r)} expressing the oscillation component and denominator is the cube of r. Here int(x) is the function to return the integer part of the value x. Coefficients of the fifth-degree polynomial of the numerator can be expressed by a quadratic polynomial of {0.5×int(2r)+0.25}.

Matsuoka, R.

2015-03-01

23

New method for the centroid-shift analysis of picosecond lifetime measurements using BaF2 scintillators  

International Nuclear Information System (INIS)

A new method of analyzing delayed coincidence spectra has been developed. The values of centroid shift deduced from the data obtained with BaF2 scintillators are usually mixtures of many lifetimes because of their poor energy resolution. By a systematic analysis of the components of the mixtures, the relation of the measured centroid shifts and the lifetimes has been reduced to a set of simultaneous linear equations, and the lifetimes are obtained as their solutions. A test measurement using the decay of 152Eu has proved that this method is very efficient even in the case of nuclei of which the decay schemes are very complex. The values of the half-life in the picosecond region, thus determined, are in good agreement with those determined with other techniques. (orig.)

24

Characterizing charge centroids from lightning using a slow antenna network and the Levenberg-Marquardt inverse method  

Science.gov (United States)

Researchers have long studied the copious and complex electric field waveforms caused by lightning. By combining electric-field measurements taken at many different locations on the ground simultaneously [Krehbiel et al., 1979], we hope to learn more about charge sources for lightning flashes. The Langmuir Electric Field Array (LEFA) is a network of nine field-change measurement stations (slow-antennas) arranged around Langmuir Laboratory near Magdalena, New Mexico. Using a mathematical method called the Levenberg-Marquardt (LM) method, we can invert the electric field data to determine the magnitude and position of the charge centroid removed from the cloud. We analyzed three return strokes (RS) following a dart-leader from a storm occurring on October 21st 2011. RS 'A' occurred at 07:17:00.63 UT. The altitude of the charge centroid was estimated to be 5 km via LMA data. Because the LM method requires a prediction, the code was run with a wide range of values to verify the robustness of the method. Predictions varied from ±3 C for the charge magnitude and ±20 km N-S and E-W for the position (with the coordinate origin being the Langmuir Laboratory Annex). The LM method converged to a charge magnitude of -5.5 C and a centroid position of 3.3 km E-W and 12 km, N-S for that RS. RS 'B' occurred at 07:20:05.9 UT. With an altitude of 4 km, the predictions were again varied; ±3 C, ±15 km N-S and E-W. Most runs converged to -27.5 C, 4 km E-W, and 10.9 km N-S. Finally, while results seem best for events right over the array, success was had locating more distant events. RS 'C' occurred at 02:42:46.8 UT. Assuming an altitude of 5 km and varying the predictions as with RS 'A', the results converged to -9.2 C, 35.5 km E-W, and 9 km N-S. All of these results are broadly consistent with the LMA and the NLDN. By continuing this type of analysis, we hope to learn more about how lightning channels propagate and how the charges in the cloud respond to the sudden change in charge distribution after a CG flash. Reference Krehbiel, P.R., M. Brook, and R. A. McCrory (1979), An analysis of the charge structure of lightning discharges to ground, J. Geophys. Res., 84(C5), 2432-2456. We gratefully acknowledge support from the National Science Foundation Grant No. 0724771.

Lapierre, J. L.; Sonnenfeld, R. G.; Hager, W. W.; Morris, K.

2011-12-01

25

A novel, view-independent method for strain mapping in myocardial elastography: eliminating angle and centroid dependence  

International Nuclear Information System (INIS)

Robust indices of regional and global cardiac function are a key factor in detection and treatment of heart disease as well as understanding of the fundamental mechanisms of a healthy heart. Myocardial elastography provides a noninvasive method for imaging and measuring displacement and strain of the myocardium for the early detection of cardiovascular disease. However, two-dimensional in-plane axial and lateral strains measured depend on the sonographic view used. This becomes especially critical in a clinical setting and may induce large variations in the measured strains, potentially leading to false diagnoses. A novel method in myocardial elastography is proposed for eliminating this view dependence by deriving the polar, principal and classified principal strains. The performance of the proposed methodology is assessed by employing 3D finite-element left-ventricular models of a control and an ischemic canine heart. Although polar strains are angle-independent, they are sensitive to the selected reference coordinate system, which requires the definition of a centroid of the left ventricle (LV). In contrast, principal strains derived through eigenvalue decomposition exhibit the inherent characteristic of coordinate system independence, offering view (i.e., angle and centroid)-independent strain measurements. Classified principal strains are obtained by assigning the principal components in the physical ventricular coordinate system. An extensive strain analysis ille system. An extensive strain analysis illustrates the improvement in interpretation and visualization of the full-field myocardial deformation by using the classified principal strains, clearly depicting the ischemic and non-ischemic regions. Strain maps, independent of sonographic views and imaging planes, that can be used to accurately detect regional contractile dysfunction are demonstrated

26

Selection of Initial Centroids for k-Means Algorithm?  

OpenAIRE

Clustering is one of the important data mining techniques. k-Means [1] is one of the mostimportant algorithm for Clustering. Traditional k-Means algorithm selects initial centroids randomly and ink-Means algorithm result of clustering highly depends on selection of initial centroids. k-Means algorithm issensitive to initial centroids so proper selection of initial centroids is necessary. This paper introduces anefficient method to start the k-Means with good initial centroids. Good initial ce...

Baswade, Anand M.; Nalwade?, Prakash S.

2013-01-01

27

Geogebra: Calculation of Centroid  

Directory of Open Access Journals (Sweden)

Full Text Available Our paper is result of the research done in a special direction for solving problems of physics by using GeoGebra programme: calculation of centroid. Lots of simulations of physical phenomena from the class of Mechanics can be performed and computational problems can be solved with GeoGebra. GeoGebra offers many commands and one of them is the command “centroid” to calculate the coordinates of the centroid of a polygon but, we have created a new tool to calculate the coordinates of the centroid of a plane region bounded by curves. Our work is part of the passionate work of many GeoGebra users which will result with a very rich fund of GeoGebra virtual tools, examples and experiences that will be worldwidely available for many teachers and practioners.

Qamil Kllogjeri

2012-09-01

28

Application example: Preliminary Results of ISOLA use to find moment tensor solutions and centroid depth applied to aftershocks of Mw=8.8 February 27 2010, Maule Earthquake  

Science.gov (United States)

We selected seven aftershocks from Maule earthquake between 33.5°S to 35°S from May to September to find single source inversion. The data were provided by XY Chile Ramp Experiment* which was deployed after great Maule earthquake. Waveform data are from 13 broad band stations chosen from the 58 broad band stations deployed by IRIS-PASCAL from April to September 2010. Stations are placed above the normal subduction section south of ~33.5°S. Events were located with an iterative software called Hypocenter using one dimensional local model, obtained above for the forearc region between 33°S to 35°S. We used ISOLA which is a fortran code with a Matlab interface to obtain moment tensors solutions, optimum position and time of the subevents. Values depth obtained by a grid search of centroid position show range values which are compatibles with the interplate seismogenic zone. Double-Couple focal mechanism solutions (Figure 1) show 4 thrust events which can be associated with that zone. However, only one of them has strike, dip and rake of 358°, 27° and 101 respectively, appropriate to be expected for interplate seismogenic zone. On the other hand, the other 3 events show strike and normal double-couple focal mechanism solutions (Figure 1). This last topic makes association to those events to the contact of the Nazca and South American plate difficult. Nevertheless, in a first stage, their depths may allow possibility of an origin there. * The facilities of the IRIS Data Management System, and specifically the IRIS Data Management Center, were used for access to waveform, metadata or products required in this study. The IRIS DMS is funded through the National Science Foundation and specifically the GEO Directorate through the Instrumentation and Facilities Program of the National Science Foundation under Cooperative Agreement EAR-0552316. Some activities of are supported by the National Science Foundation EarthScope Program under Cooperative Agreement EAR-0733069. Figure 1. Doble-Couple focal mechanisms solutions from Moment Tensor Inversion using ISOLA. Triangles show broad band stations used in this work from IRIS-PASSCAL.

Nacif, S. V.; Sanchez, M. A.

2013-05-01

29

Centroid Based Text Clustering  

Directory of Open Access Journals (Sweden)

Full Text Available Web mining is a burgeoning new field that attempts to glean meaningful information from natural language text. Web mining refers generally to the process of extracting interesting information and knowledge from unstructured text. Text clustering is one of the important Web mining functionalities. Text clustering is the task in which texts are classified into groups of similar objects based on their contents. Current research in the area of Web mining is tacklesproblems of text data representation, classification, clustering, information extraction or the search for and modeling of hidden patterns. In this paper we propose for mining large document collections it is necessary to pre-process the web documents and store the information in a data structure, which is more appropriate for further processing than a plain web file. In this paper we developed a php-mySql based utility to convert unstructured web documents into structured tabular representation by preprocessing, indexing .We apply centroid based web clustering method on preprocessed data. We apply three methods for clustering. Finally we proposed a method that can increase accuracy based on clustering ofdocuments.

Priti Maheshwari

2010-09-01

30

A Robust Front-End Processor combining Mel Frequency Cepstral Coefficient and Sub-band Spectral Centroid Histogram methods for Automatic Speech Recognition  

Directory of Open Access Journals (Sweden)

Full Text Available Environmental robustness is an important area of research in speech recognition. Mismatch between trained speech models and actual speech to be recognized is due to factors like background noise. It can cause severe degradation in the accuracy of recognizers whichare based on commonly used features like mel-frequency cepstral co-efficient (MFCC and linear predictive coding (LPC. It is well understood that all previous auditory based feature extraction methods perform extremely well in terms of robustness due to the dominantfrequency information present in them. But these methods suffer from high computational cost. Another method called sub-band spectral centroid histograms (SSCH integrates dominant-frequency information with sub-band power information. This method is based onsub-band spectral centroids (SSC which are closely related to spectral peaks for both clean and noisy speech. Since SSC can be computed efficiently from short-term speech power spectrum estimate, SSCH method is quite robust to background additive noise at a lowercomputational cost. It has been noted that MFCC method outperforms SSCH method in the case of clean speech. However in the case of speech with additive noise, MFCC method degrades substantially. In this paper, both MFCC and SSCH feature extraction have beenimplemented in Carnegie Melon University (CMU Sphinx 4.0 and trained and tested on AN4 database for clean and noisy speech. Finally, a robust speech recognizer which automatically employs either MFCC or SSCH feature extraction methods based on the variance of shortterm power of the input utterance is suggested.

R. Thangarajan

2009-06-01

31

The generalized centroid difference method for picosecond sensitive determination of lifetimes of nuclear excited states using large fast-timing arrays  

Energy Technology Data Exchange (ETDEWEB)

A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via ?–? coincidences using an array equipped with N?N equally shaped very fast high-resolution LaBr{sub 3}(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N?1)?–? time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific ?–? cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean ?–? time-walk characteristics can be determined for 40keVmethod over the total dynamic range is mainly determined by the statistics. The setup of an N=4 detector fast-timing array delivered an absolute time resolving power of 3 ps for 10 000 ?–? events per total fast timing array start and stop time spectrum. The new method is tested over the total dynamic range by the measurements of known picosecond lifetimes in standard ?-ray sources.

Régis, J.-M., E-mail: regis@ikp.uni-koeln.de [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Mach, H. [Departamento de Física Atómica y Nuclear, Universidad Complutense, 28040 Madrid (Spain); Simpson, G.S. [Laboratoire de Physique Subatomique et de Cosmologie Grenoble, 53, rue des Martyrs, 38026 Grenoble Cedex (France); Jolie, J.; Pascovici, G.; Saed-Samii, N.; Warr, N. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Bruce, A. [School of Computing, Engineering and Mathematics, University of Brighton, Lewes Road, Brighton BN2 4GJ (United Kingdom); Degenkolb, J. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Fraile, L.M. [Departamento de Física Atómica y Nuclear, Universidad Complutense, 28040 Madrid (Spain); Fransen, C. [Institut für Kernphysik der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany); Ghita, D.G. [Horia Hulubei National Institute for Physics and Nuclear Engineering, 77125 Bucharest (Romania); and others

2013-10-21

32

A quantum generalization of intrinsic reaction coordinate using path integral centroid coordinates  

International Nuclear Information System (INIS)

We propose a generalization of the intrinsic reaction coordinate (IRC) for quantum many-body systems described in terms of the mass-weighted ring polymer centroids in the imaginary-time path integral theory. This novel kind of reaction coordinate, which may be called the ''centroid IRC,'' corresponds to the minimum free energy path connecting reactant and product states with a least amount of reversible work applied to the center of masses of the quantum nuclei, i.e., the centroids. We provide a numerical procedure to obtain the centroid IRC based on first principles by combining ab initio path integral simulation with the string method. This approach is applied to NH3 molecule and N2H5- ion as well as their deuterated isotopomers to study the importance of nuclear quantum effects in the intramolecular and intermolecular proton transfer reactions. We find that, in the intramolecular proton transfer (inversion) of NH3, the free energy barrier for the centroid variables decreases with an amount of about 20% compared to the classical one at the room temperature. In the intermolecular proton transfer of N2H5-, the centroid IRC is largely deviated from the ''classical'' IRC, and the free energy barrier is reduced by the quantum effects even more drastically.

33

A quantum generalization of intrinsic reaction coordinate using path integral centroid coordinates  

Science.gov (United States)

We propose a generalization of the intrinsic reaction coordinate (IRC) for quantum many-body systems described in terms of the mass-weighted ring polymer centroids in the imaginary-time path integral theory. This novel kind of reaction coordinate, which may be called the "centroid IRC," corresponds to the minimum free energy path connecting reactant and product states with a least amount of reversible work applied to the center of masses of the quantum nuclei, i.e., the centroids. We provide a numerical procedure to obtain the centroid IRC based on first principles by combining ab initio path integral simulation with the string method. This approach is applied to NH3 molecule and N2H_5^- ion as well as their deuterated isotopomers to study the importance of nuclear quantum effects in the intramolecular and intermolecular proton transfer reactions. We find that, in the intramolecular proton transfer (inversion) of NH3, the free energy barrier for the centroid variables decreases with an amount of about 20% compared to the classical one at the room temperature. In the intermolecular proton transfer of N2H_5^-, the centroid IRC is largely deviated from the "classical" IRC, and the free energy barrier is reduced by the quantum effects even more drastically.

Shiga, Motoyuki; Fujisaki, Hiroshi

2012-05-01

34

Noise in position measurement by centroid calculation  

International Nuclear Information System (INIS)

The position of a particle trajectory in a gaseous (or semiconductor) detector can be measured by calculating the centroid of the induced charge on the cathode plane. The charge amplifiers attached to each cathode strip introduce noise which is added to the signal. This noise broadens the position resolution line. Our article gives an analytical tool to estimate the resolution broadening due to the noise per strip and the number of strips involved in the centroid calculation. It is shown that the position resolution increases faster than the square root of the number of strips involved. We also consider the consequence of added interstrip capacitors, intended to diminish the differential nonlinearity. It is shown that the position error increases slower than linearly with the interstrip capacities, due to the cancellation of correlated noise. The estimation we give, can be applied to calculations of position broadening other than the centroid finding. (orig.)

35

Weighted Centroid Correction Localization in Cellular Systems  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: There is a large demand for wireless Location-Based Service (LBS and it is provided by many wireless cellular systems. In process of positioning a Mobile Station (MS, the computing speed is as important as the positioning accuracy and the algorithm should also be resistant to environmental influences. Approach: A new positioning method based on Weighted Centroid Correction Localization (WCCL for wireless cellular systems is introduced in this article. Firstly, referring to the receiving-state of an MS in cellular systems, it computes a weighted centroid of surrounding Base Stations (BSs as a rough approximate position of the MS. Then, according to the distances between the MS and the BSs being less or bigger than the computed distances between the BSs and the weighted centroid, it corrects the coordinate of the weighted centroid towards the directions of the BSs by moving it closer or farther in turn. Results: According to our experiments, WCCL improves the positioning accuracy, as well as to provide a better resistance to environmental influences. Conclusion: As a modified centroid-based localization algorithm, WCCL obtains weighting factors from the receiving-state of MS in multi-cells structured cellular systems and obtains a better positioning result in cellular systems without updating the network equipment. Therefore, for the cellular positioning problem, WCCL algorithm can be an alternate solution.

Rong-Zheng Li

2011-01-01

36

Evidence for subduction beneath Gibraltar Arc and Andean regions from k-means earthquake centroids  

Science.gov (United States)

k-Means algorithms are widely used for determining clusters in broad types of datasets. Since zones of high seismic activity as plate boundary present diffuse seismicity patterns, the use of k-algorithm is a way to classify earthquakes in terms of centroids. Mapping centroids improves seismic visibility for further tectonic interpretation. We used selected datasets of earthquakes and determined the number of clusters or values of k by introducing the silhouette index method to check the validity of cluster numbers. By introducing magnitude size in the vectorial attributes, k-means algorithm provides a map of centroids that represents the location of high seismic energy, which is useful in seismic risk assessment. By including the depth of seismic events as the main attribute, we obtained spatiotemporal variations of centroids, which improve the image resolution of seismicity at depth to find out the underlying dynamic process. This has been achieved in subduction zone of Chile where the presence of slab is reflected by centroid distribution. The method is particularly relevant to complex seismic zones where controversial geodynamic models are reported such as the Gibraltar Arc. Resulting model supports W-oriented subduction underlying many parts of the Gibraltar zone.

Ramdani, Faiçal; Kettani, Omar; Tadili, Benaissa

2015-01-01

37

CHARGE CENTROID DETERMINATION IN FIELD-EFFECT EXPERIMENTS  

OpenAIRE

This paper presents a new method for making field-effect measurements in low-conductivity materials. The method complements conventional field effect methods by providing for the determination of the charge centroid of the field-induced charge.

Senturia, S.; Rubinstein, J.; Azoury, S.; Adler, D.

1981-01-01

38

Micro-pixel accuracy centroid displacement estimation and detector calibration  

CERN Document Server

Precise centroid estimation plays a critical role in accurate astrometry using telescope images. Conventional centroid estimation fits a template point spread function (PSF) to the image data. Because the PSF is typically not known to high accuracy due to wavefront aberrations and uncertainties in optical system, a simple Gaussian function is commonly used. PSF knowledge error leads to systematic errors in the conventional centroid estimation. In this paper, we present an accurate centroid estimation algorithm by reconstructing the PSF from well sampled (above Nyquist frequency) pixelated images. In the limit of an ideal focal plane array whose pixels have identical response function (no inter-pixel variation), this method can estimate centroid displacement between two 32$\\times$32 images to sub-micropixel accuracy. Inter-pixel response variations exist in real detectors, {\\it e.g.}~CCDs, which we can calibrate by measuring the pixel response of each pixel in Fourier space. The Fourier transforms of the inter...

Zhai, Chengxing; Goullioud, Renaud; Nemati, Bijan

2011-01-01

39

STATISTICS OF CENTROIDS OF VELOCITY  

OpenAIRE

We review the use of velocity centroids statistics to recover information of interstellar turbulence from observations. Velocity centroids have been used for a long time now to retrieve information about the scaling properties of the turbulent velocity field in the interstellar medium. We show that, while they are useful to study subsonic turbulence, they do not trace the statistics of velocity in supersonic turbulence, because they are highly influenced by fluctuations of d...

Esquivel, A.; Lazarian, A.

2009-01-01

40

Halftoning with Weighted Centroidal Voronoi Tessellations  

Science.gov (United States)

We propose a method for halftoning grayscale images by drawing weighted centroidal Voronoi tessellations (WCVTs) with black lines on white image planes. Based on the fact that CVT approaches a uniform hexagonal lattice asymptotically, we derive a relationship of darkness between input grayscale images and the corresponding halftone images. Then the derived relationship is used for adjusting the contrast of the halftone images. Experimental results show that the generated halftone images can reproduce the original tone in the input images faithfully.

Inoue, Kohei; Urahama, Kiichi

41

Weighted Centroid Correction Localization in Cellular Systems  

OpenAIRE

Problem statement: There is a large demand for wireless Location-Based Service (LBS) and it is provided by many wireless cellular systems. In process of positioning a Mobile Station (MS), the computing speed is as important as the positioning accuracy and the algorithm should also be resistant to environmental influences. Approach: A new positioning method based on Weighted Centroid Correction Localization (WCCL) for wireless cellular systems is introduced in this article. Firstly, referring ...

Rong-Zheng Li; Xin-Long Luo; Jia-Ru Lin

2011-01-01

42

Centroid Bodies and the Logarithmic Laplace Transform - A Unified Approach  

CERN Document Server

We unify and slightly improve several bounds on the isotropic constant of high-dimensional convex bodies; in particular, a linear dependence on the body's psi-2 constant is obtained. Along the way, we present some new bounds on the volume of L_p-centroid bodies and yet another equivalent formulation of Bourgain's hyperplane conjecture. Our method is a combination of the L_p-centroid body technique of Paouris and the logarithmic Laplace transform technique of the first named author.

Klartag, Bo'az

2011-01-01

43

Optimization methods for finding minimum energy paths  

Science.gov (United States)

A comparison of chain-of-states based methods for finding minimum energy pathways (MEPs) is presented. In each method, a set of images along an initial pathway between two local minima is relaxed to find a MEP. We compare the nudged elastic band (NEB), doubly nudged elastic band, string, and simplified string methods, each with a set of commonly used optimizers. Our results show that the NEB and string methods are essentially equivalent and the most efficient methods for finding MEPs when coupled with a suitable optimizer. The most efficient optimizer was found to be a form of the limited-memory Broyden-Fletcher-Goldfarb-Shanno method in which the approximate inverse Hessian is constructed globally for all images along the path. The use of a climbing-image allows for finding the saddle point while representing the MEP with as few images as possible. If a highly accurate MEP is desired, it is found to be more efficient to descend from the saddle to the minima than to use a chain-of-states method with many images. Our results are based on a pairwise Morse potential to model rearrangements of a heptamer island on Pt(111), and plane-wave based density functional theory to model a rollover diffusion mechanism of a Pd tetramer on MgO(100) and dissociative adsorption and diffusion of oxygen on Au(111).

Sheppard, Daniel; Terrell, Rye; Henkelman, Graeme

2008-04-01

44

Point estimation of root finding methods  

CERN Document Server

This book sets out to state computationally verifiable initial conditions for predicting the immediate appearance of the guaranteed and fast convergence of iterative root finding methods. Attention is paid to iterative methods for simultaneous determination of polynomial zeros in the spirit of Smale's point estimation theory, introduced in 1986. Some basic concepts and Smale's theory for Newton's method, together with its modifications and higher-order methods, are presented in the first two chapters. The remaining chapters contain the recent author's results on initial conditions guaranteing convergence of a wide class of iterative methods for solving algebraic equations. These conditions are of practical interest since they depend only on available data, the information of a function whose zeros are sought and initial approximations. The convergence approach presented can be applied in designing a package for the simultaneous approximation of polynomial zeros.

2008-01-01

45

Maser Source Finding Methods in HOPS  

CERN Document Server

The {\\bf H}$_2${\\bf O} Southern Galactic {\\bf P}lane {\\bf S}urvey (HOPS) has observed 100 square degrees of the Galactic plane, using the Mopra radio telescope to search for emission from multiple spectral lines in the 12\\,mm band (19.5\\,--\\,27.5\\,GHz). Perhaps the most important of these spectral lines is the 22.2\\,GHz water maser transition. We describe the methods used to identify water maser candidates and subsequent confirmation of the sources. Our methods involve a simple determination of likely candidates by searching peak emission maps, utilising the intrinsic nature of water maser emission - spatially unresolved and spectrally narrow-lined. We estimate completeness limits and compare our method with results from the {\\sc Duchamp} source finder. We find that the two methods perform similarly. We conclude that the similarity in performance is due to the intrinsic limitation of the noise characteristics of the data. The advantages of our method are that it is slightly more efficient in eliminating spuri...

Walsh, Andrew J; Longmore, Steven; Jordan, Christopher H; Lowe, Vicki

2011-01-01

46

Intelligent systems for analyzing soccer games: The weighted centroid  

Directory of Open Access Journals (Sweden)

Full Text Available New, intelligent systems have been developed recently to improve the quality of match analysis. These systems analyze the tactical behavior of the teams. However, the existing methods leave room for improvement. Thus, the main goal of this study is to refine the team centroid metric by considering all of the players on the team and the ball position. Furthermore, this study analyzes the relation-ship between the centroids of the two opposing teams. One 11-on-11 soccer match was analyzed to test the new centroid algorithm. The results provided strong evidence of the positive relation between the centroids of the two teams over time in the x-axis (rs= 0.781 and the x-axis (rs= 0.707. This study confirmed the results of previous studies that analyzed the relationship between team centroids. Furthermore, it was possible to prove the effectiveness of the new tactical metric and its relevance for adding information during a match.

Filipe Manuel Clemente

2014-11-01

47

FINGERPRINT MATCHING BASED ON PORE CENTROIDS  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years there has been exponential growth in the use of bio- metrics for user authentication applications. Automated Fingerprint Identification systems have become popular tool in many security and law enforcement applications. Most of these systems rely on minutiae (ridge ending and bifurcation features. With the advancement in sensor technology, high resolution fingerprint images (1000 dpi pro- vide micro level of features (pores that have proven to be useful fea- tures for identification. In this paper, we propose a new strategy for fingerprint matching based on pores by reliably extracting the pore features The extraction of pores is done by Marker Controlled Wa- tershed segmentation method and the centroids of each pore are con- sidered as feature vectors for matching of two fingerprint images. Experimental results shows that the proposed method has better per- formance with lower false rates and higher accuracy.

S. Malathi

2011-05-01

48

Estimating the Doppler centroid of SAR data  

DEFF Research Database (Denmark)

After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ?E estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found that the nonlinear SDE algorithm, which estimates the Doppler-shift on the basis of data signs alone, gives superior performance

Madsen, SØren NØrvang

1989-01-01

49

Spherical Layout Implementation using Centroidal Voronoi Tessellations  

CERN Document Server

The 3D tree visualization faces multiple challenges: the election of an appropriate layout, the use of the interactions that make the data exploration easier and a metaphor that helps in the process of information understanding. A good combination of these elements will result in a visualization that effectively conveys the key features of a complex structure or system to a wide range of users and permits the analytical reasoning process. In previous works we presented the Spherical Layout, a technique for 3D tree visualization that provides an excellent base to achieve those key features. The layout was implemented using the TriSphere algorithm, a method that discretized the spheres's surfaces with triangles to achieve a uniform distribution of the nodes. The goal of this work was centered in a new algorithm for the implementation of the Spherical layout; we called it the Weighted Spherical Centroidal Voronoi Tessellations (WSCVT). In this paper we present a detailed description of this new implementation an...

Larrea, Martin; Martig, Sergio; Castro, Silvia

2009-01-01

50

Centroid–moment tensor inversions using high-rate GPS waveforms  

OpenAIRE

Displacement time-series recorded by Global Positioning System (GPS) receivers are a new type of near-field waveform observation of the seismic source. We have developed an inversion method which enables the recovery of an earthquake's mechanism and centroid coordinates from such data. Our approach is identical to that of the 'classical' Centroid-Moment Tensor (CMT) algorithm, except that we forward model the seismic wavefield using a method that is amenable to the efficient computation of sy...

O Toole, Tb; Valentine, Ap; Woodhouse, Jh

2012-01-01

51

Improving the Initial Centroids of k-means Clustering Algorithm to Generalize its Applicability  

Science.gov (United States)

k-means is one of the most widely used partition based clustering algorithm. But the initial centroids generated randomly by the k-means algorithm cause the algorithm to converge at the local optimum. So to make k-means algorithm globally optimum, the initial centroids must be selected carefully rather than randomly. Though many researchers have already been carried out for the enhancement of k-means algorithm, they have their own limitations. In this paper a new method to formulate the initial centroids is proposed which results in better clusters equally for uniform and non-uniform data sets.

Goyal, M.; Kumar, S.

2014-12-01

52

Evaluation of centroiding algorithm error for Nano-JASMINE  

Science.gov (United States)

The Nano-JASMINE mission has been designed to perform absolute astrometric measurements with unprecedented accuracy; the end-of-mission parallax standard error is required to be of the order of 3 milli arc seconds for stars brighter than 7.5 mag in the zw-band(0.6?m-1.0?m) .These requirements set a stringent constraint on the accuracy of the estimation of the location of the stellar image on the CCD for each observation. However each stellar images have individual shape depend on the spectral energy distribution of the star, the CCD properties, and the optics and its associated wave front errors. So it is necessity that the centroiding algorithm performs a high accuracy in any observables. Referring to the study of Gaia, we use LSF fitting method for centroiding algorithm, and investigate systematic error of the algorithm for Nano-JASMINE. Furthermore, we found to improve the algorithm by restricting sample LSF when we use a Principle Component Analysis. We show that centroiding algorithm error decrease after adapted the method.

Hara, Takuji; Gouda, Naoteru; Yano, Taihei; Yamada, Yoshiyuki

2014-08-01

53

Foot Bone in Vivo: Its Center of Mass and Centroid of Shape  

CERN Document Server

This paper studies foot bone geometrical shape and its mass distribution and establishes an assessment method of bone strength. Using spiral CT scanning, with an accuracy of sub-millimeter, we analyze the data of 384 pieces of foot bones in vivo and investigate the relationship between the bone's external shape and internal structure. This analysis is explored on the bases of the bone's center of mass and its centroid of shape. We observe the phenomenon of superposition of center of mass and centroid of shape fairly precisely, indicating a possible appearance of biomechanical organism. We investigate two aspects of the geometrical shape, (i) distance between compact bone's centroid of shape and that of the bone and (ii) the mean radius of the same density bone issue relative to the bone's centroid of shape. These quantities are used to interpret the influence of different physical exercises imposed on bone strength, thereby contributing to an alternate assessment technique to bone strength.

Fan, Yifang; Fan, Yubo; Lin, Zhiyu; Lv, Changsheng

2010-01-01

54

Radiographic measures of thoracic kyphosis in osteoporosis: Cobb and vertebral centroid angles  

International Nuclear Information System (INIS)

Several measures can quantify thoracic kyphosis from radiographs, yet their suitability for people with osteoporosis remains uncertain. The aim of this study was to examine the validity and reliability of the vertebral centroid and Cobb angles in people with osteoporosis. Lateral radiographs of the thoracic spine were captured in 31 elderly women with osteoporosis. Thoracic kyphosis was measured globally (T1-T12) and regionally (T4-T9) using Cobb and vertebral centroid angles. Multisegmental curvature was also measured by fitting polynomial functions to the thoracic curvature profile. Canonical and Pearson correlations were used to examine correspondence; agreement between measures was examined with linear regression. Moderate to high intra- and inter-rater reliability was achieved (SEM = 0.9-4.0 ). Concurrent validity of the simple measures was established against multisegmental curvature (r = 0.88-0.98). Strong association was observed between the Cobb and centroid angles globally (r = 0.84) and regionally (r 0.83). Correspondence between measures was moderate for the Cobb method (r 0.72), yet stronger for the centroid method (r = 0.80). The Cobb angle was 20% greater for regional measures due to the influence of endplate tilt. Regional Cobb and centroid angles are valid and reliable measures of thoracic kyphosis in people with osteoporosis. However, the Cobb angle is biased by endplate tilt, suggesting that the centroid angle is more appropriate for this populationle is more appropriate for this population. (orig.)

55

Consolidating boundary methods for finding the eigenstates of billiards  

International Nuclear Information System (INIS)

The plane-wave decomposition method, a widely used means of numerically finding eigenstates of the Helmholtz equation in billiard systems is described as a variant of the mathematically well-established boundary integral method (BIM). A new unified framework encompassing the two methods is discussed. Furthermore, a third numerical method, which we call the gauge freedom method is derived from the BIM equations. This opens the way to further improvements in eigenstate search techniques

56

Comparing the performance of open loop centroiding techniques in the Raven MOAO system  

Science.gov (United States)

Raven is a multi-object adaptive optics (MOAO) demonstrator that will be mounted on the NIR Nasmyth platform of the Subaru telescope in May, 2014. Raven can use three open-loop NGS WFSs and an on-axis LGS WFS to control DMs in two separate science pick-off arms. Centroiding in open loop AO systems like Raven is more difficult than in closed loop AO systems because the Shack-Hartmann spots will not be driven to the same spot on a detector. Rather the spots can fall on any combination of pixels because the WFSs need to have sufficient dynamic range to measure the full turbulence. In this paper, we compare correlation and thresholded center of gravity (tCOG) centroiding methods in simulation, with Raven using its calibration unit, and on-sky. Each method has its own advantages. Correlation centroiding is superior to tCOG centroiding for faint NGSs and for extended sources (Raven open loop WFSs do not contain ADCs so spots will become elongated). We expect that correlation centroiding will push the limiting magnitude of Raven NGSs fainter by roughly one magnitude. Correlation centroiding is computationally more intensive, however, and actually will limit Raven's sampling rate for shorter integrations. Therefore, for bright stars with sufficiently high signal-to-noise, Raven can be run significantly faster and with superior performance using the tCOG method. Here we quantify both the performance and timing differences of these two centroiding methods in simulation, in the lab and on sky using Raven.

Andersen, David R.; Bradley, Colin; Gamroth, Darryl; Kerley, Dan; Lardière, Olivier; Véran, Jean-Pierre

2014-08-01

57

GPU-assisted computation of centroidal Voronoi tessellation.  

Science.gov (United States)

Centroidal Voronoi tessellations (CVT) are widely used in computational science and engineering. The most commonly used method is Lloyd's method, and recently the L-BFGS method is shown to be faster than Lloyd's method for computing the CVT. However, these methods run on the CPU and are still too slow for many practical applications. We present techniques to implement these methods on the GPU for computing the CVT on 2D planes and on surfaces, and demonstrate significant speedup of these GPU-based methods over their CPU counterparts. For CVT computation on a surface, we use a geometry image stored in the GPU to represent the surface for computing the Voronoi diagram on it. In our implementation a new technique is proposed for parallel regional reduction on the GPU for evaluating integrals over Voronoi cells. PMID:21233516

Rong, Guodong; Liu, Yang; Wang, Wenping; Yin, Xiaotian; Gu, Xianfeng David; Guo, Xiaohu

2011-03-01

58

Conjugate gradient method for finding fundamental solitary waves  

OpenAIRE

The Conjugate Gradient method (CGM) is known to be the fastest generic iterative method for solving linear systems with symmetric sign definite matrices. In this paper, we modify this method so that it could find fundamental solitary waves of nonlinear Hamiltonian equations. The main obstacle that such a modified CGM overcomes is that the operator of the equation linearized about a solitary wave is not sign definite. Instead, it has a finite number of eigenvalues on the oppo...

Lakoba, Taras I.

2009-01-01

59

Path-integral centroid dynamics for general initial conditions: a nonequilibrium projection operator formulation.  

Science.gov (United States)

The formulation of path-integral centroid dynamics is extended to the quantum dynamics of density operators evolving from general initial states by means of the nonequilibrium projection operator technique. It is shown that the new formulation provides a basis for applying the method of centroid dynamics to nonequilibrium situations and that it allows the derivation of new formal relations, which can be useful in improving current equilibrium centroid dynamics methods. A simple approximation of uniform relaxation for the unprojected portion of the Liouville space propagator leads to a class of practically solvable equations of motion for the centroid variables, but with an undetermined parameter of relaxation. This new class of equations encompasses the centroid molecular-dynamics (CMD) method as a limiting case, and can be applied to both equilibrium and nonequilibrium situations. Tests for the equilibrium dynamics of one-dimensional model systems demonstrate that the new equations with appropriate choice of the relaxation parameter are comparable to the CMD method. PMID:16483196

Jang, Seogjoo

2006-02-14

60

ASTROMETRIC IMAGE CENTROID DISPLACEMENTS DUE TO GRAVITATIONAL MICROLENSING BY THE ELLIS WORMHOLE  

International Nuclear Information System (INIS)

Continuing work initiated in an earlier publication, we study the gravitational microlensing effects of the Ellis wormhole in the weak-field limit. First, we find a suitable coordinate transformation, such that the lens equation and analytic expressions of the lensed image positions can become much simpler. Second, we prove that two images always appear for the weak-field lens by the Ellis wormhole. By using these analytic results, we discuss astrometric image centroid displacements due to gravitational microlensing by the Ellis wormhole. The astrometric image centroid trajectory by the Ellis wormhole is different from the standard one by a spherical lensing object that is expressed by the Schwarzschild metric. The anomalous shift of the image centroid by the Ellis wormhole lens is smaller than that by the Schwarzschild lens, provided that the impact parameter and the Einstein ring radius are the same. Therefore, the lensed image centroid by the Ellis wormhole moves slower. Such a difference, although it is very small, will be, in principle, applicable for detecting or constraining the Ellis wormhole by using future high-precision astrometry observations. In particular, the image centroid position gives us additional information, so that the parameter degeneracy existing in photometric microlensing can be partially broken. The anomalous shift reaches the order of a few micro arcseconds, if our galaxy hosts a wormhole with throat radius larger than 105 km. Wat radius larger than 105 km. When the source moves tangentially to the Einstein ring, for instance, the maximum position shift of the image centroid by the Ellis wormhole is 0.18 normalized by the Einstein ring radius. For the same source trajectory, the maximum difference between the centroid displacement by the Ellis wormhole lens and that by the Schwarzschild one with the same Einstein ring radius is -0.16 in the units of the Einstein radius, where the negative means that the astrometric displacement by the Ellis wormhole lens is smaller than that by the Schwarzschild one.

61

A new method for finding vacua in string phenomenology  

Energy Technology Data Exchange (ETDEWEB)

One of the central problems of string-phenomenology is to find stable vacua in the four dimensional effective theories which result from compactification. We present an algorithmic method to find all of the vacua of any given string-phenomenological system in a huge class. In particular, this paper reviews and then extends hep-th/0606122 to include various nonperturbative effects. These include gaugino condensation and instantonic contributions to the superpotential. (authors)

Gray, James [Institut d' Astrophysique de Paris and APC, Universite de Paris 7, 98 bis, Bd. Arago 75014, Paris (France); He, Yang-Hui [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)]|[Merton College, Oxford, OX1 4JD and Mathematical Institute, Oxford University, Oxford (United Kingdom); Ilderton, Anton [School of Mathematics and Statistics, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Lukas, Andre [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

2007-05-15

62

Centroid velocity statistics of molecular clouds  

Science.gov (United States)

We compute structure functions and Fourier spectra of 2D centroid velocity maps in order to study the gas dynamics of typical molecular clouds in numerical simulations. We account for a simplified treatment of time-dependent chemistry and the non-isothermal nature of the gas and use a 3D radiative transfer tool to model the CO line emission in a post-processing step. We perform simulations using three different initial mean number densities of n0 = 30, 100 and 300 cm-3 to span a range of typical values for dense gas clouds in the solar neighbourhood. We compute slopes of the centroid velocity increment structure functions (CVISF) and of Fourier spectra for different chemical components: the total density, H2 number density, 12CO number density as well as the integrated intensity of 12CO (J = 1 ? 0) and 13CO (J = 1 ? 0). We show that optical depth effects can significantly affect the slopes derived for the CVISF, which also leads to different scaling properties for the Fourier spectra. The slopes of CVISF and Fourier spectra for H2 are significantly steeper than those for the different CO tracers, independent of the density and the numerical resolution. This is due to the larger space-filling factor of H2 as it is better able to self-shield in diffuse regions, leading to a larger fractal co-dimension compared to CO.

Bertram, Erik; Konstandin, Lukas; Shetty, Rahul; Glover, Simon C. O.; Klessen, Ralf S.

2015-02-01

63

Optimization strategies for rapid centroid estimation.  

Science.gov (United States)

Particle swarm algorithm has been extensively utilized as a tool to solve optimization problems. Recently proposed particle swarm±based clustering algorithm called the Rapid Centroid Estimation (RCE) is a lightweight alteration to Particle Swarm Clustering (PSC). The RCE in its standard form is shown to be superior to conventional PSC algorithm. We have observed some limitations in RCE including the possibility to stagnate at a local minimum combination and the restriction in swarm size. We propose strategies to optimize RCE further by introducing RCE+ and swarm RCE+. Five benchmark datasets from UCI machine learning database are used to test the performance of these new strategies. In Glass dataset swarm RCE+ is able to achieve highest purity centroid combinations with less iteration (90.3%±1.1% in 9±5 iterations) followed by RCE+ (89%±3.5% in 65±62 iterations) and RCE (87%±5.9% in 54±44). Similar quality is also reflected in other benchmark datasets including Iris, Wine, Breast Cancer, and Diabetes. PMID:23367348

Yuwono, Mitchell; Su, Steven W; Moulton, Bruce D; Nguyen, Hung T

2012-01-01

64

Interstellar cloud structure: The statistics of centroid velocities  

CERN Document Server

The investigation of the statistical properties of maps of line centroids has been used for almost 50 years, but there is still no general agreement on their interpretation. We try to quantify which properties of underlying turbulent velocity fields can be derived from centroid velocity maps, and we test conditions under which the scaling behaviour of the centroid velocities matches the scaling of the three-dimensional velocity field. Using fractal cloud models we study systematically the relation between three-dimensional density and velocity fields and the statistical properties of the produced line centroid maps. We put special attention to cases with large density fluctuations resembling supersonic interstellar turbulence. Starting from the Delta-variance analysis we derive a new tool to compute the scaling behaviour of the three-dimensional velocity field from observed intensity and centroid velocity maps. We provide two criteria to decide whether the information from the centroid velocities directly ref...

Ossenkopf, V; Lazarian, A; Stutzki, J

2006-01-01

65

Accurate Alignment of Plasma Channels Based on Laser Centroid Oscillations  

International Nuclear Information System (INIS)

A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the shift in laser centroid and angle at the channel outptut. If only the shift in centroid or angle is measured, then accurate alignment is provided by minimizing laser centroid motion at the channel exit as the channel properties are scanned. The improvement in alignment accuracy provided by this technique is important for minimizing electron beam pointing errors in laser plasma accelerators.

66

Computed tomographic methods and findings in adenomyomatosis of the gallbladder  

International Nuclear Information System (INIS)

Objective: To describe the characteristic CT imaging of adenomyomatosis of gallbladder and to improve the diagnostic knowledge of the disease. Methods: Eleven (5 males and 6 females, mean age = 43 years) patients with adenomyomatosis of gallbladder (4 diffuse, 2 segmental, and 5 fundal) confirmed by histopathology and performed by CT examination including plain, dynamic or multiphase enhancement and/or oral chole-graphic agent were reviewed. Results: Correct diagnosis was made in 7 of 11 patients (3 diffuse, 1 segmental, and 3 fundal). CT findings included segmental or diffuse gallbladder wall thickening in the involved area, associated with well defined and regular borders at both of the inner and outer layers. Significant CT findings of this entity were marked enhancement of wall layers during triphase contrast CT scanning, especially at delayed scans. Rokitansky-Aschoff sinuses were clearly shown by CT, Presenting as characteristic 'aureola' sign, when performed with application of a chole-graphic agent. Conclusion: Understanding the CT findings and using the optimal methods, the authors can use CT scan as a valuable method to help make the diagnosis in most cases of adenomyomatosis

67

Basin constrained ?-dimer method for saddle point finding  

Science.gov (United States)

Within the harmonic approximation to transition state theory, the rate of escape from a reactant is calculated from local information at saddle points on the boundary of the state. The dimer minimum-mode following method can be used to find such saddle points. But as we show, dimer searches that are initiated from a reactant state of interest can converge to saddles that are not on the boundary of the reactant state. These disconnected saddles are not directly useful for calculating the escape rate. Additionally, the ratio of disconnected saddles can be large, especially when the dimer searches are initiated far from the reactant minimum. The reason that the method finds disconnected saddles is a result of the fact that the dimer method tracks local ridges, defined as the set of points where the force is perpendicular to the negative curvature mode, and not the true ridge, defined as the boundary of the set of points which minimize to the reactant. The local ridges tend to deviate from the true ridge away from saddle points. Furthermore, the local ridge can be discontinuous and have holes which allow the dimer to cross the true ridge and escape the initial state. To solve this problem, we employ an alternative definition of a local ridge based upon the minimum directional curvature of the isopotential hyperplane, ?, which provides additional local information to tune the dimer dynamics. We find that hyperplanes of ? = 0 pass through all saddle points but rarely intersect with the true ridge elsewhere. By restraining the dimer within the ? disconnected saddles is significantly reduced and the efficiency of finding connected saddles is increased.

Xiao, Penghao; Wu, Qiliang; Henkelman, Graeme

2014-10-01

68

A method for finding three-dimensional magnetic skeletons  

International Nuclear Information System (INIS)

Magnetic fields are an essential component of a plasma. In many astrophysical, solar, magnetospheric, and laboratory situations the magnetic field in the plasma can be very dynamic and form highly complex structures. One approach to unraveling these structures is to determine the magnetic skeleton of the field, a set of topological features that divide the magnetic field into topologically distinct domains. In general, the features of the magnetic skeleton are difficult to locate, in particular those given by numerical experiments. In this paper, we propose a new set of tools to find the skeleton of general magnetic fields including null points, spines, separatrix surfaces, and separators. This set of tools is found to be considerably better at finding the skeleton than the currently favored methods used in magnetohydrodynamics.

69

Energy Centroids in the presence of random interactions  

CERN Document Server

In this paper we study energy centroids such as those with fixed spin and isospin, those with fixed irreducible representations for bosons, in the presence of random two-body and/or three-body interactions. Our results show that regularities of energy centroids of fixed spin states reported in earlier works are more robust than expected.

Zhao, Y M; Yoshida, N; Ogawa, K; Yoshinaga, N; Kota, V K B

2005-01-01

70

Velocity centroids as tracers of the turbulent velocity statistics  

CERN Document Server

We use the results of magnetohydrodynamic (MHD) simulations to emulate spectroscopic observations, and produce maps of variations of velocity centroids to study their scaling properties. We compare them with those of the underlying velocity field, and analytic predictions presented in a previous paper (Lazarian & Esquivel 2003). We tested, with success, a criteria for recovering velocity statistics from velocity centroids derived in our previous work. That is, if >> (where S is a 2D map of ``unnormalized'', v velocity, and I integrated intensity map -column density-), then the structure function of the centroids is dominated by the structure function of velocity. We show that it is possible to extract the velocity statistics using centroids for subsonic and mildly supersonic turbulence (e.g. Mach numbers ~2.5). While, towards higher Mach numbers other effects could affect significantly the statistics of centroids.

Lazarian, A E A

2004-01-01

71

Feature selection and nearest centroid classification for protein mass spectrometry  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The use of mass spectrometry as a proteomics tool is poised to revolutionize early disease diagnosis and biomarker identification. Unfortunately, before standard supervised classification algorithms can be employed, the "curse of dimensionality" needs to be solved. Due to the sheer amount of information contained within the mass spectra, most standard machine learning techniques cannot be directly applied. Instead, feature selection techniques are used to first reduce the dimensionality of the input space and thus enable the subsequent use of classification algorithms. This paper examines feature selection techniques for proteomic mass spectrometry. Results This study examines the performance of the nearest centroid classifier coupled with the following feature selection algorithms. Student-t test, Kolmogorov-Smirnov test, and the P-test are univariate statistics used for filter-based feature ranking. From the wrapper approaches we tested sequential forward selection and a modified version of sequential backward selection. Embedded approaches included shrunken nearest centroid and a novel version of boosting based feature selection we developed. In addition, we tested several dimensionality reduction approaches, namely principal component analysis and principal component analysis coupled with linear discriminant analysis. To fairly assess each algorithm, evaluation was done using stratified cross validation with an internal leave-one-out cross-validation loop for automated feature selection. Comprehensive experiments, conducted on five popular cancer data sets, revealed that the less advocated sequential forward selection and boosted feature selection algorithms produce the most consistent results across all data sets. In contrast, the state-of-the-art performance reported on isolated data sets for several of the studied algorithms, does not hold across all data sets. Conclusion This study tested a number of popular feature selection methods using the nearest centroid classifier and found that several reportedly state-of-the-art algorithms in fact perform rather poorly when tested via stratified cross-validation. The revealed inconsistencies provide clear evidence that algorithm evaluation should be performed on several data sets using a consistent (i.e., non-randomized, stratified cross-validation procedure in order for the conclusions to be statistically sound.

Levner Ilya

2005-03-01

72

A doubly nudged elastic band method for finding transition states  

Science.gov (United States)

A modification of the nudged elastic band (NEB) method is presented that enables stable optimizations to be run using both the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) quasi-Newton and slow-response quenched velocity Verlet minimizers. The performance of this new "doubly nudged" DNEB method is analyzed in conjunction with both minimizers and compared with previous NEB formulations. We find that the fastest DNEB approach (DNEB/L-BFGS) can be quicker by up to 2 orders of magnitude. Applications to permutational rearrangements of the seven-atom Lennard-Jones cluster (LJ7) and highly cooperative rearrangements of LJ38 and LJ75 are presented. We also outline an updated algorithm for constructing complicated multi-step pathways using successive DNEB runs.

Trygubenko, Semen A.; Wales, David J.

2004-02-01

73

A doubly nudged elastic band method for finding transition states.  

Science.gov (United States)

A modification of the nudged elastic band (NEB) method is presented that enables stable optimizations to be run using both the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) quasi-Newton and slow-response quenched velocity Verlet minimizers. The performance of this new "doubly nudged" DNEB method is analyzed in conjunction with both minimizers and compared with previous NEB formulations. We find that the fastest DNEB approach (DNEB/L-BFGS) can be quicker by up to 2 orders of magnitude. Applications to permutational rearrangements of the seven-atom Lennard-Jones cluster (LJ7) and highly cooperative rearrangements of LJ38 and LJ75 are presented. We also outline an updated algorithm for constructing complicated multi-step pathways using successive DNEB runs. PMID:15268346

Trygubenko, Semen A; Wales, David J

2004-02-01

74

A Doubly Nudged Elastic Band Method for Finding Transition States  

CERN Document Server

A modification of the nudged elastic band (NEB) method is presented that enables stable optimisations to be run using both the limited-memory quasi-Newton (L-BFGS) and slow-response quenched velocity Verlet (SQVV) minimisers. The performance of this new `doubly nudged' DNEB method is analysed in conjunction with both minimisers and compared with previous NEB formulations. We find that the fastest DNEB approach (DNEB/L-BFGS) can be quicker by up to two orders of magnitude. Applications to permutational rearrangements of the seven-atom Lennard-Jones cluster (LJ7) and highly cooperative rearrangements of LJ38 and LJ75 are presented. We also outline an updated algorithm for constructing complicated multi-step pathways using successive DNEB runs.

Trygubenko, S A; Trygubenko, Semen A.; Wales, David J.

2004-01-01

75

Method of finding the direction in a reactor vessel  

International Nuclear Information System (INIS)

Purpose: To enable a worker to find the direction in a reactor container with ease. Method: A magnetic field is formed within a reactor container. A worker carries a magnetic compass and goes around in a reactor container while observing the indicator of the compass. For constituting the magnetic field, a semi-circular iron core is disposed around the outer circumference at the lower part of the reactor container and coils are wound around the middle portion of the core and supplied with electric current. In this way, the iron core serves as an electromagnet to produce the magnetic field. The magnetic field can, alternately, be formed by disposing permanent magnets at several positions in the reactor container. (Ikeda, J.)

76

A study on the uncertainties of the centroid depth of the 2013 Lushan earthquake from teleseimic body wave data  

Science.gov (United States)

Centroid depth of earthquakes is essential for seismic hazard mitigation. But, various studies provided different solutions for the centroid depth of the damaging 2013 Lushan earthquake, thus hindering further studies of the earthquake processes. To resolve its centroid depth and assess the uncertainties, we apply the teleseismic cut and paste method to invert for centroid depth with teleseismic body waves in the epicentral distance of 30°-90°. We performed the inversion for P waves only as well the case of both P and SH waves and found that both cases lead to depth solutions with difference less than 0.5 km. We also investigated the effects on depth inversion from azimuth gap of seismic stations, source duration, and corner frequency of filter. These various tests show that even azimuthal distribution of seismic stations is helpful for accurate depth inversion. It is also found that estimate of centroid depth is sensitive to source duration. Moreover, the depth is biased to larger values when corner frequency of low-pass filter is very low. The uncertainty in the velocity model can also generate some error in the depth estimation (~1.0 km).With all the above factors considered, the centroid depth of Lushan earthquake is proposed to be around 12 km, with uncertainty about 2 km.

Chen, Weiwen; Wang, Decai; Wei, Shengji

2013-08-01

77

Automatic extraction of nuclei centroids of mouse embryonic cells from fluorescence microscopy images.  

Science.gov (United States)

Accurate identification of cell nuclei and their tracking using three dimensional (3D) microscopic images is a demanding task in many biological studies. Manual identification of nuclei centroids from images is an error-prone task, sometimes impossible to accomplish due to low contrast and the presence of noise. Nonetheless, only a few methods are available for 3D bioimaging applications, which sharply contrast with 2D analysis, where many methods already exist. In addition, most methods essentially adopt segmentation for which a reliable solution is still unknown, especially for 3D bio-images having juxtaposed cells. In this work, we propose a new method that can directly extract nuclei centroids from fluorescence microscopy images. This method involves three steps: (i) Pre-processing, (ii) Local enhancement, and (iii) Centroid extraction. The first step includes two variations: first variation (Variant-1) uses the whole 3D pre-processed image, whereas the second one (Variant-2) modifies the preprocessed image to the candidate regions or the candidate hybrid image for further processing. At the second step, a multiscale cube filtering is employed in order to locally enhance the pre-processed image. Centroid extraction in the third step consists of three stages. In Stage-1, we compute a local characteristic ratio at every voxel and extract local maxima regions as candidate centroids using a ratio threshold. Stage-2 processing removes spurious centroids from Stage-1 results by analyzing shapes of intensity profiles from the enhanced image. An iterative procedure based on the nearest neighborhood principle is then proposed to combine if there are fragmented nuclei. Both qualitative and quantitative analyses on a set of 100 images of 3D mouse embryo are performed. Investigations reveal a promising achievement of the technique presented in terms of average sensitivity and precision (i.e., 88.04% and 91.30% for Variant-1; 86.19% and 95.00% for Variant-2), when compared with an existing method (86.06% and 90.11%), originally developed for analyzing C. elegans images. PMID:22590505

Bashar, Md Khayrul; Komatsu, Koji; Fujimori, Toshihiko; Kobayashi, Tetsuya J

2012-01-01

78

Global slab deformation and centroid moment tensor constraints on viscosity  

Science.gov (United States)

We analyze moment tensor solutions from deep subduction zone earthquakes to determine global slab deformation patterns. Inferred strain rates are compared to predicted deformation patterns from fluid models to help constrain the first-order radial and lateral viscosity structure of the Earth. While all slabs that reach the lower mantle are compressed at their tip, intermediate depth patterns are more complex. We compute 3-D spherical flow with various slab rheologies and compare the angular misfit between the compressive eigenvectors of the resultant stress field and global centroid moment tensor (gCMT) solutions. We find that upper mantle slab viscosities of ˜10-100 and lower mantle viscosities of ˜30-100 times the upper mantle produce the best match to gCMTs. A 0.1 viscosity reduction in the asthenosphere seems preferred. Slab geometry and lower mantle viscosity exert significant control on deformation. Inclusion of the phase changes at 410 km and 660 km increases extensional deformation at intermediate depth and compressional deformation at the lower mantle, improving the match to gCMTs for strong slabs. Our conclusions are fairly insensitive to surface boundary conditions. However, models which include net rotations of the surface with respect to the lower mantle produce compression at intermediate depths for west directed slabs and extension for east directed slabs. Without allowing for regional variations, these models yield the best match to gCMTs. While significant deviations between model and seismicity remain, our results show that seismicity provides an underutilized constraint for slab dynamics.

Alpert, L. A.; Becker, T. W.; Bailey, I. W.

2010-12-01

79

An Adaptive Polygonal Centroidal Voronoi Tessellation Algorithm for Segmentation of Noisy SAR Images  

Science.gov (United States)

In this research, a fast, adaptive and user friendly segmentation methodology is developed for highly speckled SAR images. The developed region based centroidal Voronoi tessellation (R-BCVT) algorithm is a kind of polygon-based clustering approach in which the algorithm attempts to (1) split the image domain into j numbers of centroidal Voronoi polygons (2) assign each polygon a label randomly, then (3) classify the image into k cluster iteratively to satisfy optimum segmentation, and finally a k-mean clustering method refine the detected boundaries of homogeneous regions. The advantages of the novel method arise from adaptively, simplicity and rapidity as well as low sensitivity of the model to speckle noise.

Askari, G.; Li, Y.; MoezziNasab, R.

2014-10-01

80

Bias in the centroid moment tensor for central Asian earthquakes: Evidence from regional surface wave data  

International Nuclear Information System (INIS)

Surface waves recorded on the Chinese Digital Seismic Network (CDSN) station Urumqi (WMQ) are analyzed for 26 centroid moment tensor (CMT) earthquakes located within an epicentral distance of 1300 km. Applying a simple grid search method for source parameter retrieval, I obtain revised estimates of the focal depth, fault strike, and seismic moment (M0) from amplitude spectra of Love and Rayleigh waves and compare these estimates with the CMT best double-couple solutions. The comparisons show that residuals are unbiased for focal depth and fault strike, where population spreads are ±13 km and ±17 degree, respectively. On the other hand, M0 estimates are found to be biased, with CMT M0 larger than regional estimates by an average of 0.27±0.04 log units. The results for focal depth and strike are consistent with previous global and regional studies comparing independent estimates with CMT results. Recent full-waveform modeling studies for central Asian earthquakes support the findings of bias in M0 estimates. I suggest that causes for M0 bias may be related to great thicknesses of continental crust in Hindu Kush and Tien Shan regions and to data censoring practices at small magnitudes. M0:mb scaling relationships for central Asian earthquakes show better agreement with western U.S. scaling when M0 estimates determined in this study are used. copyright 1998 American Geophysical Unioopyright 1998 American Geophysical Union

81

Robust of Doppler Centroid for Mapping Sea Surface Current by Using Radar Satellite Data  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Sea surface current retrieving from Synthetic Aperture Radar (SAR is required standard methods due to the complexity of sea surface ocean imaging in SAR data. In this context, various analytical models have been developed which describe overall effects of sea surface roughness on the Doppler signal mechanisms. Nevertheless, such models are limited in the complexity of the sea surface current estimation that can be used. In fact, the resolution of the sea surface Doppler velocity in azimuth direction is typically coarser as compared to the normalized radar cross section image. Approach: This study introduced a new method to retrieve sea surface current from RADARSAT-1 SAR Standard beam mode (S2 data. The method was based on the utilization of the Wavelength Diversity Ambiguity Resolving (WDAR and Multi Look beat Frequency (MLBF algorithms to remove Doppler centroid (fDC ambiguity. Results: The result showed that the proposed methods are able to correct Doppler centroid (fDC ambiguity and produced fine spatial sea surface current variations in S2 mode data. The current velocities were ranged between 0.18 and 0.78 m sec-1 with standard error of 0.11 m sec-1. Conclusion: In conclusion, RADARSAT-1 SAR standard beam mode (S2 data can be utilized to retrieve real time sea surface current. Both WDAR and MLBF algorithms are able to provide accurately information on Doppler Centroid (fDC in which accurately real time sea surface current can be retrieved from SAR data.

Mazlan Hashim

2009-01-01

82

Interfractional Variations of Tumor Centroid Position and Tumor Regression during Stereotactic Body Radiotherapy for Lung Tumor  

OpenAIRE

Purpose. To determine interfractional changes of lung tumor centroid position and tumor regression during stereotactic body radiation therapy (SBRT). Methods and Materials. 34 patients were treated by SBRT in 4-5 fractions to a median dose of 50?Gy. The CT scans acquired for verification were registered with simulation CT scans. The gross target volume (GTV) was contoured on all verification CT scans and compared to the initial GTV in treatment plan system. Results. The mean (±standard dev...

Yanan Sun; Yufei Lu; Siguo Cheng; Wei Guo; Ke Ye; Huiyun Zhao; Xiaoli Zheng; Dingjie Li; Shujuan Wang; Chengliang Yang; Hong Ge

2014-01-01

83

Extracting Ocean Surface Currents from SAR: MCC and Doppler Centroid Tracking  

Science.gov (United States)

SAR backscatter from the ocean is reduced by biogenic surface slicks and repeat observations of these slicks from spaceborne SAR instruments offers a method for studying submeso- to mesoscale ocean surface current features by observing slick advection. The Maximum Cross-Correlation (MCC) method has been used to derive ocean surface currents from tracking thermal infra-red and ocean color features in satellite imagery. In this study, the MCC algorithm is applied to a series of Envisat & ERS2 SAR 30-minute lag image pairs over the US West Coast, and results are compared with HF radar currents. One sample SAR pair processed to generate currents is shown in Fig. 1. The dark linear features are surface slicks, and their spatial shift is clear in the change detection image. Comparison with the current field from HF radar shows good overall agreement. Further Envisat-ERS2 SAR pairs over the West Coast are being processed for years 2008 and 2009 and quantitative statistical comparison of MCC SAR currents with HF radar currents will be discussed. SAR Doppler centroid tracking can estimate surface currents, though only in the across-track (XT) radial direction. Removal of satellite platform contributions from the measured Doppler spectrum results in "Doppler centroid anomaly", which is the Doppler shift due to geophysical processes: wind, waves, surface currents. Modeling is used to remove the undesired geophysical components and get an estimate of radial currents. Envisat Wide Swath Mode (WSM) intensity images are delivered with a low-resolution (~10 km) Doppler centroid grid; this grid is processed to generate radial currents, and the radials can be used to study currents at the meso- and synoptic scales. A sample comparison of Doppler centroid radials with HF radar current radials (rotated in XT-direction) over the US East Coast are shown in Fig. 2. The large scale features in both current fields are similar, but smaller-scale features in HF radar radials are not apparent in Doppler radials; this is expected, because the Doppler centroid radials have much lower resolution than the HF radar radials. More Envisat WSM Doppler radials are being processed, and they will be compared with HF radar, and with MCC SAR currents where available. Quantitative statistical comparisons of these current fields will be further discussed.; MCC SAR currents from an Envisat-ERS2 30-minute lag image pair ; Doppler centroid radial currents from an Envisat WSM Doppler centorid grid

Qazi, W. A.; Emery, W. J.; Hansen, M. W.

2012-12-01

84

A Statistical Study of Beam Centroid Oscillations in a Solenoid Transport Channel  

Energy Technology Data Exchange (ETDEWEB)

A recent theory of transverse centroid oscillations in solenoidally focused beam transport lattices presented in Ref. [1] is applied to statistically analyze properties of the centroid orbit in the Neutralized Drift Compression Experiment (NDCX) at the Lawrence Berkeley National Laboratory. Contributions to the amplitude of the centroid oscillations from mechanical misalignments and initial centroid errors exiting the injector are analyzed. Measured values of the centroid appear consistent with expected alignment tolerances. Correction of these errors is discussed.

Lund, S; Wootton, C; Coleman, J; Lidia, S; Seidl, P

2009-05-07

85

Methods to Find the Number of Latent Skills  

Science.gov (United States)

Identifying the skills that determine the success or failure to exercises and question items is a difficult task. Multiple skills may be involved at various degree of importance, and skills may overlap and correlate. In an effort towards the goal of finding the skills behind a set of items, we investigate two techniques to determine the number of…

Beheshti, Behzad; Desmarais, Michel C.; Naceur, Rhouma

2012-01-01

86

Optimal properties of centroid-based classifiers for very high-dimensional data  

CERN Document Server

We show that scale-adjusted versions of the centroid-based classifier enjoys optimal properties when used to discriminate between two very high-dimensional populations where the principal differences are in location. The scale adjustment removes the tendency of scale differences to confound differences in means. Certain other distance-based methods, for example, those founded on nearest-neighbor distance, do not have optimal performance in the sense that we propose. Our results permit varying degrees of sparsity and signal strength to be treated, and require only mild conditions on dependence of vector components. Additionally, we permit the marginal distributions of vector components to vary extensively. In addition to providing theory we explore numerical properties of a centroid-based classifier, and show that these features reflect theoretical accounts of performance.

Hall, Peter; 10.1214/09-AOS736

2010-01-01

87

A method for finding communities of related genes  

OpenAIRE

We present a method for creating a network of gene co-occurrences from the literature and partitioning it into communities of related genes. The way in which our method identifies communities makes it likely that the component genes of each community will be related by their function. The method processes a large database of article abstracts, synthesizing information from many sources to shed light on groups of genes that have been shown to interact. It is a tool to be used by researchers in...

Wilkinson, Dennis M.; Huberman, Bernardo A.

2004-01-01

88

Modified string method for finding minimum energy path  

OpenAIRE

We present an efficient algorithm for calculating the minimum energy path (MEP) and energy barriers between local minima on a multidimensional potential energy surface (PES). Such paths play a central role in the understanding of transition pathways between metastable states. Our method relies on the original formulation of the string method [Phys. Rev. B ${\\bf 66}$, 052301 (2002)], i.e. to evolve a smooth curve along a direction normal to the curve. The algorithm works by p...

Samanta, Amit; E, Weinan

2010-01-01

89

Class hierarchy method to find Change-Proneness  

Directory of Open Access Journals (Sweden)

Full Text Available Finding Proneness of software is necessary to identify fault prone and change prone classes at earlier stages of development, so that those classes can be given special attention. Also to improves the quality and reliability of the software. For corrective and adaptive maintenance we require to make changes during the software evolution.As such changes cluster around number of key components in software, it is important to analyze the frequency of changes in individual classes and also to identify and show related changes in multiple classes. Early detection of fault prone and change prone classes can enables the developers and experts to spend their valuable time and resources on these areas of software. Prediction of change-prone and fault prone classes of a software is an active topic in the area of software engineering. Such prediction can be used to predict changes to different classes of a system from one release of software to the next release. Identifying the change-prone and fault prone classes in advance can helps to focus attention on these classes.In this paper we are focusing on finding dependency of software that can be chieved by estimating the proneness of Object Oriented Software. Two main types of proneness are associated with OO software. Fault Proneness and Change Proneness.

Malan V.Gaikwad

2011-01-01

90

Recent findings with computerized methods for scalp hair growth measurements.  

Science.gov (United States)

Sensitive tools have been developed in order to monitor hair loss and treatment responses. Recently the Tricho-Scan was presented (by RH) as such a method which combines epiluminescence microscopy (ELM) with automatic digital image analysis. Herewith new TrichoScan data obtained from 10 women and 21 men with androgenetic hair loss after 6 mo of treatment with 5%-minoxidil are presented. Even in this small cohort of patients, we noticed a significant increase of hair density, cumulative hair thickness and terminal hair counts. Alternative methods were developed during a human alopecia investigation and research technology (HAIR Technology) programme at Skinterface. This involves contrast-enhancement, image acquisition, and processing by qualified technicians followed by computer-assisted image analysis. The specific identification of exogen hair, further adds to this very refined non-invasive investigative method for hair follicle function investigation. Regional variations of hair growth dynamics do exist in the human scalp such as in female patients complaining of hair loss, scalp hair density and growth on top of the head differs significantly from the occipital site. Finally, from transversal studies and from detailed monitoring of subsequent hair cycles during longitudinal studies, data were obtained that support the fact that shortening of hair cycle, slowing down of growth rates and thinning of hair shafts are heralding hair miniaturisation. In the workshop the TrichoScan, the method of Canfield and Skinterface have been shown. PMID:16382682

Hoffmann, Rolf; Van Neste, Dominique

2005-12-01

91

Finding Methods for Innovative Packaging Development: The Card Approach  

OpenAIRE

Innovation strategies are crucial for corporate success and should be a top priority for packaging companies. However, to improve the innovativeness of packaging manufacturers, there is a need to increase the integration of product and packaging development and collaboration within the supply chain. New methods for innovative packaging development are needed. Packaging plays a valuable role in the marketing and distribution of products, and can thus add great value for actors in the supply...

Magnusson, Amanda; Olander, Malin; Olsson, Annika

2013-01-01

92

Real-time centroid moment tensor determination for large earthquakes from local and regional displacement records  

Science.gov (United States)

We present an algorithm to rapidly determine the moment tensor and centroid location for large earthquakes employing local and regional real-time high-rate displacement records from GPS. The algorithm extracts the coseismic offset from the displacement waveforms and uses the information to invert for the moment tensor. The Green's functions for a layered earth are obtained numerically from open source code EDGRN. To determine the centroid, multiple inversions are simultaneously performed within a grid of inversion nodes, and the node with the smallest misfit is then assigned the centroid location. We show results for two large earthquakes replayed in simulated real-time mode using recorded 1 Hz GPS displacements: the 2003 Mw 8.3 Tokachi-oki and the 2010 Mw 7.2 El Mayor-Cucapah earthquakes. We demonstrate that it is feasible to obtain accurate CMT solutions within the first 2-3 min after rupture initiation without any prior assumptions on fault characteristics, demonstrating an order of magnitude improvement in latency compared to existing seismic methods for the two earthquakes studied. This methodology is useful for rapid earthquake response, tsunami prediction and as a starting point for rapid finite fault modelling.

Melgar, Diego; Bock, Yehuda; Crowell, Brendan W.

2012-02-01

93

Centroid based Categorization Approach for Extraction of Body Sensor Network Data  

Directory of Open Access Journals (Sweden)

Full Text Available Monitoring human activities using wearable wireless sensor nodes has the potential to enable many useful applications for everyday situations. The long-term lifestyle categorization can greatly improve healthcare by gathering information about quality of life; aiding the diagnosis and tracking of certain diseases. The deployment of an automatic and computationally-efficient algorithm reduces the complexities involved in the detection and recognition of human activities in a distributed on Body sensor network server. Directory service is a useful aid human looking for information on Network Data. A directory services is a pre-categorized list of topics containing many links for each topic. However, most directory services are maintained manually now and face many drawbacks. Therefore the task of automatic categorization of new data into the topics of directory services becomes very necessary. BSN data categorization is more difficult due to a large variation of noisy information embedded in Sensor network data. This paper suggests a new Centroid based approach for Categorization for BSN data. We further introduce a new algorithm through centroid based approach for extraction of BSN data categorization and show that it achieves about more improvement over other BSN data categorization methods. Experimental results show that our proposed Centroid-based BSN data categorization algorithm achieves an approximately 13.8% improvement for BSN data categorization algorithm.

Setu Ku. Chaturvedi

2010-01-01

94

Metrology calibration and very high accuracy centroiding with the NEAT testbed  

CERN Document Server

NEAT is an astrometric mission proposed to ESA with the objectives of detecting Earth-like exoplanets in the habitable zone of nearby solar-type stars. NEAT requires the capability to measure stellar centroids at the precision of 5e-6 pixel. Current state-of-the-art methods for centroid estimation have reached a precision of about 2e-5 pixel at two times Nyquist sampling, this was shown at the JPL by the VESTA experiment. A metrology system was used to calibrate intra and inter pixel quantum efficiency variations in order to correct pixelation errors. The European part of the NEAT consortium is building a testbed in vacuum in order to achieve 5e-6 pixel precision for the centroid estimation. The goal is to provide a proof of concept for the precision requirement of the NEAT spacecraft. The testbed consists of two main sub-systems. The first one produces pseudo stars: a blackbody source is fed into a large core fiber and lights-up a pinhole mask in the object plane, which is imaged by a mirror on the CCD. The ...

Crouzier, A; Preis, O; Henault, F; Kern, P; Martin, G; Feautrier, P; Stadler, E; Lafrasse, S; Delboulbe, A; Behar, E; Saint-Pe, M; Dupont, J; Potin, S; Cara, C; Donati, M; Doumayrou, E; Lagage, P O; Léger, A; LeDuigou, J M; Shao, M; Goullioud, R

2014-01-01

95

A global root-finding method for high dimensional problems  

OpenAIRE

A method to solve the problem f(x) = 0 efficiently on any n-dimensional domain Omega under very broad hypoteses is proposed. The position of the root of f, assumed unique, is found by computing the center of mass of an Omega-shaped object having a singular mass density. It is shown that although the mass of the object is infinite, the position of its center of mass can be computed exactly and corresponds to the solution of the problem. The exact analytical result is implemen...

Castellano, Fabrizio

2009-01-01

96

Findings from analysing and quantifying human error using current methods  

International Nuclear Information System (INIS)

In human reliability analysis (HRA), the scarcity of data means that, at best, judgement must be applied to transfer to the domain of the analysis what data are available for similar tasks. In particular for the quantification of tasks involving decisions, the analyst has to choose among quantification approaches that all depend to a significant degree on expert judgement. The use of expert judgement can be made more reliable by eliciting relative judgements rather than absolute judgements. These approaches, which are based on multiple criterion decision theory, focus on ranking the tasks to be analysed by difficulty. While these approaches remedy at least partially the poor performance of experts in the estimation of probabilities, they nevertheless require the calibration of the relative scale on which the actions are ranked in order to obtain the probabilities of interest. This paper presents some results from a comparison of some current HRA methods performed in the frame of a study of SLIM calibration options. The HRA quantification methods THERP, HEART, and INTENT were applied to derive calibration human error probabilities for two groups of operator actions. (author)

97

Finding the dominant risk: A review of the ATHEANA method  

International Nuclear Information System (INIS)

A new human reliability analysis (HRA) method called ATHEANA, open-quotes A Technique for Human Error Analysisclose quotes as described in NUREG/CR-6350, is being developed for the U.S. Nuclear Regulatory Commission (NRC). The contribution of human errors to nuclear plant risk has long been recognized by the probabilistic risk assessment (PRA) community. Of particular concern are open-quotes errors of commissionclose quotes (EOC), which NUREG/CR-6350 describes as open-quotes errors that are associated with inappropriate interventions by operators with operating systems.close quotes When completed, ATHEANA is expected to provide guidance on identifying and quantifying the likelihood of commission errors, thus allowing the risks associated with such errors to be integrated within PRA studies. This paper provides an initial review of ATHEANA, with emphasis on the quantitative trial demonstration of the method provided in NUREG/CR-6350. The importance of HRA research to PRA is discussed in this paper in light of its regulatory impact

98

Real time quantum dynamics preaveraged over imaginary time path integral: A formal basis for both Centroid Molecular Dynamics and Ring Polymer Molecular Dynamics  

OpenAIRE

An exact real time quantum dynamics preaveraged over imaginary time path integral is formulated for general condensed phase equilibrium ensemble. This formulation results in the well-known centroid dynamics approach upon filtering of centroid constraint, and provides a rigorous framework to understand and analyze a related quantum dynamics approximation method called ring polymer molecular dynamics. The formulation also serves as the basis for developing new kinds of quantum...

Jang, Seogjoo

2013-01-01

99

A evolutionary method for finding communities in bipartite networks  

CERN Document Server

Common practice in community structure detection is to develop different methods for different classes of networks. Here, we first show that unipartite networks and directed networks can be uniformly represented as bipartite networks, and their modularity completely consist with that for bipartite networks. To optimize the bipartite modularity, we then present a modified adaptive genetic algorithm, called as MMOGA, which is especially suited for community structure detection. In MMOGA, we introduce a new measure for the informativeness of a locus instead of the standard deviation, which can exactly determine those loci to mutate. This measure is the bias between the distribution of a locus over the current population and the uniform distribution of the locus, i.e., Kull-back Divergence between them. Moreover, we develop a reassignment technique for differentiating the informative state a locus has attained from the random state at initial phase. Also we present a modified mutation rule which incorporating rel...

WeiHua, Zhan; Jihong, Guan; Shuigeng, Zhou

2010-01-01

100

A Bayesian method for finding regulatory segments in DNA.  

Science.gov (United States)

A goal of the human genome project is to determine the entire sequence of DNA (3 x 10(9) base pairs) found in chromosomes. The massive amounts of data produced by this project require interpretation. A Bayesian model is developed for locating regulatory regions in a DNA sequence. Regulatory regions are areas of DNA to which specific proteins bind and control whether or not a gene is transcribed to produce templates for protein synthesis. Each human cell contains the same DNA sequence. Thus the particular function of different cells is determined by the genes that are transcribed in that cell. A Hidden Markov chain is used to model whether a small interval of the DNA is in a regulatory region or not. This can be regarded as a changepoint problem where the changepoints are the start of a regulatory or nonregulatory region. The data consists of protein-binding elements, which are short subsequences, or "words," in the DNA sequence. Although these words can occur anywhere in the sequence, a larger number are expected in regulatory regions. Therefore, regulatory regions are detected by locating clusters of words. For a particular DNA sequence, the model automatically selects those words that best predict regions of interest. Markov chain Monte Carlo methods are used to explore the posterior distribution of the Hidden Markov chain. The model is tested by means of simulations, and applied to several DNA sequences. PMID:11093115

Crowley, E M

2001-02-01

101

The RPC space resolution with the charge centroid method  

Science.gov (United States)

RPC detectors were originally developed to exploit the very good intrinsic time resolution of the plane geometry and have been used as muon trigger in most of their high energy physics applications, disregarding the detector space resolution. Due to the high luminosity of future colliders, new experiments will be very demanding in terms of momentum selection of the muon spectrometer. For this reason, trigger detectors will be required to have a sub-millimeter space resolution as well as a sub-nanosecond time resolution. RPCs are good candidates for these applications, as it can be shown that they have excellent intrinsic space resolution, while the actual results depend mostly on the front-end electronics performance. Here we present a beam test carried out on a small size RPC. The results are consistent with a space resolution of ~ 130 ?m.

Aielli, G.; Cardarelli, R.; Di Stante, L.; Liberti, B.; Paolozzi, L.; Pastori, E.; Santonico, R.

2014-09-01

102

Centroid Detection by Gaussian Pattern Matching in Adaptive Optics  

CERN Document Server

Shack Hartmann wavefront sensor is a two dimensional array of lenslets which is used to detect the incoming phase distorted wavefront through local tilt measurements made by recording the spot pattern near the focal plane. Wavefront reconstruction is performed in two stages - (a) image centroiding to calculate local slopes, (b) formation of the wavefront shape from local slope measurement. Centroiding accuracy contributes to most of the wavefront reconstruction error in Shack Hartmann sensor based adaptive optics system with readout and background noise. It becomes even more difficult in atmospheric adaptive optics case, where scintillation effects may also occur. In this paper we used a denoising technique based on thresholded Zernike reconstructor to minimize the effects due to readout and background noise. At low signal to noise ratio, this denoising technique can be improved further by taking the advantage of the shape of the spot. Assuming a Gaussian pattern for individual spots, it is shown that the cen...

Vyas, Akondi; Prasad, B Raghavendra

2009-01-01

103

Fixed J spectral distributions in large shell model spaces. III. Fixed J quasiparticle centroids and widths  

International Nuclear Information System (INIS)

A method is developed to exactly calculate the fixed J quasiparticle centroid energies and partial widths. Some results obtained in the even-mass lead isotopes with various interactions are analysed. Fixed J quasi-particle distributions are used to predict an upper limit for the deviations between the quasiparticle approximation and the shell model results for the low-energy levels. The influence of the states with a high quasiparticle number in the low-energy region is seen to strongly depend upon the interaction. The importance of the dimensionalities and the internal widths in explaining the admixtures is stressed

104

A centroid molecular dynamics study of liquid para-hydrogen and ortho-deuterium.  

Science.gov (United States)

Centroid molecular dynamics (CMD) is applied to the study of collective and single-particle dynamics in liquid para-hydrogen at two state points and liquid ortho-deuterium at one state point. The CMD results are compared with the results of classical molecular dynamics, quantum mode coupling theory, a maximum entropy analytic continuation approach, pair-product forward- backward semiclassical dynamics, and available experimental results. The self-diffusion constants are in excellent agreement with the experimental measurements for all systems studied. Furthermore, it is shown that the method is able to adequately describe both the single-particle and collective dynamics of quantum liquids. PMID:15446940

Hone, Tyler D; Voth, Gregory A

2004-10-01

105

Quantum effects on virial coefficients: A numerical approach using centroids  

Science.gov (United States)

We develop a numerical methodology to calculate quantum corrected virial coefficients using the centroid approximation of the exact path-integral expression. This approach naturally takes into account any form of the many-body non-additive interaction potentials, and - in the case of helium - is shown to have an accuracy better than 1% for temperatures larger than 100 K. We apply it to the ab initio calculation of the fourth virial coefficient of 4He, using state-of-the-art pair and three-body potentials. Our results are an improvement with respect to the classical calculation and almost agree within mutual uncertainty with the latest experimental data.

Garberoglio, Giovanni

2012-02-01

106

A method for finding single-nucleotide polymorphisms with allele frequencies in sequences of deep coverage  

OpenAIRE

Abstract Background The allele frequencies of single-nucleotide polymorphisms (SNPs) are needed to select an optimal subset of common SNPs for use in association studies. Sequence-based methods for finding SNPs with allele frequencies may need to handle thousands of sequences from the same genome location (sequences of deep coverage). Results We describe a computational method for finding common SNPs with allele frequencies in single-pass sequences of deep coverage. The method enhances a wide...

Huang Xiaoqiu; Wang Jianmin

2005-01-01

107

A fast algorithm to compute precise type-2 centroids for real-time control applications.  

Science.gov (United States)

An interval type-2 fuzzy set (IT2 FS) is characterized by its upper and lower membership functions containing all possible embedded fuzzy sets, which together is referred to as the footprint of uncertainty (FOU). The FOU results in a span of uncertainty measured in the defuzzified space and is determined by the positional difference of the centroids of all the embedded fuzzy sets taken together. This paper provides a closed-form formula to evaluate the span of uncertainty of an IT2 FS. The closed-form formula offers a precise measurement of the degree of uncertainty in an IT2 FS with a runtime complexity less than that of the classical iterative Karnik-Mendel algorithm and other formulations employing the iterative Newton-Raphson algorithm. This paper also demonstrates a real-time control application using the proposed closed-form formula of centroids with reduced root mean square error and computational overhead than those of the existing methods. Computer simulations for this real-time control application indicate that parallel realization of the IT2 defuzzification outperforms its competitors with respect to maximum overshoot even at high sampling rates. Furthermore, in the presence of measurement noise in system (plant) states, the proposed IT2 FS based scheme outperforms its type-1 counterpart with respect to peak overshoot and root mean square error in plant response. PMID:24691554

Chakraborty, Sumantra; Konar, Amit; Ralescu, Anca; Pal, Nikhil R

2015-02-01

108

A trilinear method for finding null points in a 3D vector space  

OpenAIRE

Null points are important locations in vector fields, such as a magnetic field. A new technique (a trilinear method for finding null points) is presented for finding null points over a large grid of points, such as those derived from a numerical experiment. The method was designed so that the null points found would agree with any fieldlines traced using the commonly used trilinear interpolation. It is split into three parts: reduction, analysis and positioning, which, when ...

Haynes, Andrew L.; Parnell, Clare E.

2007-01-01

109

Minima Hopping Guided Path Search: An Efficient Method for Finding Complex Chemical Reaction Pathways  

OpenAIRE

The Minima Hopping global optimization method uses physically realizable molecular dynamics moves in combination with an energy feedback that guarantees the escape from any potential energy funnel. For the purpose of finding reactions pathways, we argue that Minima Hopping is particularly suitable as a guide through the potential energy landscape and as a generator for pairs of minima that can be used as input structures for methods capable of finding transition states betwe...

Schaefer, Bastian; Mohr, Stephan; Amsler, Maximilian; Goedecker, Stefan

2014-01-01

110

Quantum effects in light and heavy liquid water: A rigid-body centroid molecular dynamics study.  

Science.gov (United States)

The centroid molecular dynamics (CMD) method is applied to the study of liquid water in the context of the rigid-body approximation. This rigid-body CMD technique, which is significantly more efficient than the standard CMD method, is implemented on the TIP4P model for water and used to examine isotopic effects in the equilibrium and dynamical properties of liquid H(2)O and D(2)O. The results obtained with this approach compare remarkably well with those determined previously with path integrals simulations as well as those obtained from the standard CMD method employing flexible models. In addition, an examination of the impact of quantization on the rotational and librational motion of the water molecule is also reported. PMID:15367027

Hernández de la Peña, L; Kusalik, P G

2004-09-22

111

Finding-equal regression method and its application in predication of U resources  

International Nuclear Information System (INIS)

The commonly adopted deposit model method in mineral resources predication has two main part: one is model data that show up geological mineralization law for deposit, the other is statistics predication method that accords with characters of the data namely pretty regression method. This kind of regression method may be called finding-equal regression, which is made of the linear regression and distribution finding-equal method. Because distribution finding-equal method is a data pretreatment which accords with advanced mathematical precondition for the linear regression namely equal distribution theory, and this kind of data pretreatment is possible of realization. Therefore finding-equal regression not only can overcome nonlinear limitations, that are commonly occurred in traditional linear regression or other regression and always have no solution, but also can distinguish outliers and eliminate its weak influence, which would usually appeared when Robust regression possesses outlier in independent variables. Thus this newly finding-equal regression stands the best status in all kind of regression methods. Finally, two good examples of U resource quantitative predication are provided

112

Unified framework for finding eigenstates of Helmholtz equation using boundary methods  

CERN Document Server

The powerful plane-wave decomposition method (PWDM) for finding eigenstates of Helmholtz equation can be regarded as a variant of the mathematically well-established boundary integral method (BIM). The capabilities of the BIM and the PWDM are discussed using a unified framework. This opens the way to further improvements.

Cohen, D; Heller, E J; Cohen, Doron; Lepore, Natasha; Heller, Eric J.

2001-01-01

113

Visualising Pipeline Sensor Datasets with Modified Incremental Orthogonal Centroid Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available Each year, millions of people suffer from after-effects of pipeline leakages, spills, and eruptions. Leakages Detection Systems (LDS are often used to understand and analyse these phenomena but unfortunately could not offer complete solution to reducing the scale of the problem. One recent approach was to collect datasets from these pipeline sensors and analyse offline, the approach yielded questionable results due to vast nature of the datasets. These datasets together with the necessity for powerful exploration tools made most pipelines operating companies "data rich but information poor". Researchers have therefore identified problem of dimensional reduction for pipeline sensor datasets as a major research issue. Hence, systematic gap filling data mining development approaches are required to transform data "tombs" into "golden nuggets" of knowledge. This paper proposes an algorithm for this purpose based on the Incremental Orthogonal Centroid (IOC. Search time for specific data patterns may be enhanced using this algorithm.

Folorunso Olufemi Ayinde

2011-09-01

114

Reducing noise in moving-grid codes with strongly-centroidal Lloyd mesh regularization  

CERN Document Server

A method for improving the accuracy of hydrodynamical codes that use a moving Voronoi mesh is described. Our scheme is based on a new regularization scheme that constrains the mesh to be centroidal to high precision while still allowing the cells to move approximately with the local fluid velocity, thereby retaining the quasi-Lagrangian nature of the approach. Our regularization technique significantly reduces mesh noise that is attributed to changes in mesh topology and deviations from mesh regularity. We demonstrate the advantages of our method on various test problems, and note in particular improvements obtained in handling shear instabilities, mixing, and in angular momentum conservation. Calculations of adiabatic jets in which shear excites Kelvin Helmholtz instability show reduction of mesh noise and entropy generation. In contrast, simulations of the collapse and formation of an isolated disc galaxy are nearly unaffected, showing that numerical errors due to the choice of regularization do not impact ...

Mocz, Philip; Pakmor, Rudiger; Genel, Shy; Springel, Volker; Hernquist, Lars

2015-01-01

115

Nonlinear force density method for the form-finding of minimal surface membrane structures  

Science.gov (United States)

We develop an alternative approach for the form-finding of the minimal surface membranes (including cable membranes) using discrete models and nonlinear force density method. Two directed weighted graphs with 3 and 4-sided regional cycles, corresponding to triangular and quadrilateral finite element meshes are introduced as computational models for the form-finding problem. The triangular graph model is closely related to the triangular computational models available in the literature whilst the quadrilateral graph uses a novel averaging approach for the form-finding of membrane structures within the context of nonlinear force density method. The viability of the mentioned discrete models for form-finding are studied through two solution methods including a fixed-point iteration method and the Newton-Raphson method with backtracking. We suggest a hybrid version of these methods as an effective solution strategy. Examples of the formation of certain well-known minimal surfaces are presented whilst the results obtained are compared and contrasted with analytical solutions in order to verify the accuracy and viability of the suggested methods.

Koohestani, K.

2014-06-01

116

Level set methods for finding critical points of mountain pass type  

CERN Document Server

Computing mountain passes is a standard way of finding critical points. We describe a numerical method for finding critical points that is convergent in the nonsmooth case and locally superlinearly convergent in the smooth finite dimensional case. We apply these techniques to describe a strategy for the Wilkinson problem of calculating the distance of a matrix to a closest matrix with repeated eigenvalues. Finally, we relate critical points of mountain pass type to nonsmooth and metric critical point theory.

Lewis, Adrian S

2009-01-01

117

Study of clustering methods to improve primary vertex finding for collider detectors  

International Nuclear Information System (INIS)

Primary vertex finding for collider experiments is studied with the aim to detect all primary interactions. The efficiency and precision of finding interaction vertices can be improved by advanced clustering and classification methods, such as agglomerative clustering with fast pairwise nearest neighbor search, followed by Gaussian mixture model or k-means clustering. The results have been obtained with simplified simulation and Gaussian smearing, but insights on sensitivity to backgrounds are also given.

118

A trilinear method for finding null points in a 3D vector space  

CERN Document Server

Null points are important locations in vector fields, such as a magnetic field. A new technique (a trilinear method for finding null points) is presented for finding null points over a large grid of points, such as those derived from a numerical experiment. The method was designed so that the null points found would agree with any fieldlines traced using the commonly used trilinear interpolation. It is split into three parts: reduction, analysis and positioning, which, when combined, provide an efficient means of locating null points to a user-defined sub-grid accuracy. We compare the results of the trilinear method with that of a method based on the Poincare index, and discuss the accuracy and limitations of both methods.

Haynes, Andrew L

2007-01-01

119

A trilinear method for finding null points in a three-dimensional vector space  

International Nuclear Information System (INIS)

Null points are important locations in vector fields, such as a magnetic field. A new technique (a trilinear method for finding null points) is presented for finding null points over a large grid of points, such as those derived from a numerical experiment. The method was designed so that the null points found would agree with any field lines traced using the commonly used trilinear interpolation. It is split into three parts: reduction, analysis, and positioning, which, when combined, provide an efficient means of locating null points to a user-defined subgrid accuracy. We compare the results of the trilinear method with that of a method based on the Poincare index, and discuss the accuracy and limitations of both methods

120

Influence of anteroposterior shifting of trunk mass centroid on vibrational configuration of human spine.  

Science.gov (United States)

This study attempts to determine the influence of anteroposterior (A-P) shifting of trunk mass from the upright sedentary posture on dynamic characteristics of the human lumbar spine. A three-dimensional finite element (FE) model comprising of the T12-Pelvis spine unit was used to mimic the human spine system. It is not clear how the A-P shifting of the upper part of human upper body affect on vibrational modality of the human lumbar spine under whole body vibration. Five trunk mass point locations were assumed by 2.0cm anterior, 1.0cm anterior, 1.0cm posterior and 2.0cm posterior to the upright sedentary posture including no shifting posture. FE modal analysis was used to extract the resonant frequencies and vibration modes of the human spine. The analytical results indicate that trunk mass centroid shifting onwards or rearwards may result in a reduction of vertical resonant frequency of the human spine. The human spine has the highest vertical resonant frequency at the normal upright sedentary posture with the trunk mass locating around 1.0cm anterior to the L3-L4 vertebral centroid. Larger A-P deformations and rotational deformations were also found at the spine motion segments L3-L4 and L4-L5, which imply higher compressive stress and shear stress at the disc annulus of those spinal motion segments. The findings in this study may explain why long-term whole body vibration might induce the degeneration of human spine at the relevant spinal motion segments. PMID:17931615

Guo, Li-Xin; Zhang, Ming; Wang, Zhao-Wen; Zhang, Yi-Min; Wen, Bang-Chun; Li, Jin-Li

2008-01-01

121

Franck–Condon factors and r-centroids for the diatomic fluorides of germanium and silicon  

Directory of Open Access Journals (Sweden)

Full Text Available A suitable potential energy function was found by analysing the potential functions proposed by Morse, Mohammad and Rafi et al. for the A2?+–X2?3/2 and B2?+–X2?3/2 band systems of GeF and the 1?–1? band system of SiF. It was found that the potential proposed by Rafi et al. is in close agreement with the Rydberg–Klein–Rees (R–K–R potential. Using this potential, the wave functions were evaluated by the Wentzel–Kramer–Brillouin (W–K–B method. The Franck–Condon factors and r-centroids were computed by a numerical integration technique. The results are compared with available theoretical values. The intensities of the various bands were investigated.

S. KANAGAPRABHA

2008-05-01

122

A New Method for Finding the Thevenin and Norton Equivalent Circuits  

OpenAIRE

The paper presents a new pedagogical method for finding the Thevenin and Norton equivalent circuits of a linear electric circuit (LEC) at the n-different pairs of terminals simultaneously, regardless of the circuit topology and complexity. The proposed method is appropriate for undergraduate electrical and electronic engineering students leading to straightforward solutions, mostly arrived at by inspection, so that it can be regarded as a simple and innovative calculation tool for Thevenin eq...

Chatzarakis, George E.

2010-01-01

123

Nudged-elastic band method with two climbing images: finding transition states in complex energy landscapes  

CERN Document Server

The nudged-elastic band (NEB) method is modified with concomitant two climbing images (C2-NEB) to find a transition state (TS) in complex energy landscapes, such as those with serpentine minimal energy path (MEP). If a single climbing image (C1-NEB) successfully finds the TS, C2-NEB finds it with higher stability and accuracy. However, C2-NEB is suitable for more complex cases, where C1-NEB misses the TS because the MEP and NEB directions near the saddle point are different. Generally, C2-NEB not only finds the TS but guarantees that the climbing images approach it from the opposite sides along the MEP, and it estimates accuracy from the three images: the highest-energy one and its climbing neighbors. C2-NEB is suitable for fixed-cell NEB and the generalized solid-state NEB (SS-NEB).

Zarkevich, Nikolai A

2014-01-01

124

Error-finding and error-correcting methods for the start-up of the SLC  

International Nuclear Information System (INIS)

During the commissioning of an accelerator, storage ring, or beam transfer line, one of the important tasks of an accelerator physicist is to check the first-order optics of the beam line and to look for errors in the system. Conceptually, it is important to distinguish between techniques for finding the machine errors that are the cause of the problem and techniques for correcting the beam errors that are the result of the machine errors. In this paper the authors limit their presentation to certain applications of these two methods for finding or correcting beam-focus errors and beam-kick errors that affect the profile and trajectory of the beam respectively. Many of these methods have been used successfully in the commissioning of SLC systems. In order not to waste expensive beam time they have developed and used a beam-line simulator to test the ideas that have not been tested experimentally. To save valuable physicist's time they have further automated the beam-kick error-finding procedures by adopting methods from the field of artificial intelligence to develop a prototype expert system. The authors' experience with this prototype has demonstrated the usefulness of expert systems in solving accelerator control problems. The expert system is able to find the same solutions as an expert physicist but in a more systematic fashion. The methods used in these procedures and some of the recent applications are described in this paper paper

125

Observations of sensor bias dependent cluster centroid shifts in a prototype sensor for the LHCb Vertex Locator detector  

CERN Document Server

We present results from a recent beam test of a prototype sensor for the LHCb Vertex Locator detector, read out with the Beetle 1.3 front-end chip. We have studied the effect of the sensor bias voltage on the reconstructed cluster positions in a sensor placed in a 120GeV pion beam at a 10° incidence angle. We find an unexplained sysematic shift in the reconstructed cluster centroid when increasing the bias voltage on an already overdepleted sensor. The shift is independent of strip pitch and sensor thickness.

Papadelis, Aras

2006-01-01

126

Neutron radiography with sub-15 ?m resolution through event centroiding  

International Nuclear Information System (INIS)

Conversion of thermal and cold neutrons into a strong ?1 ns electron pulse with an absolute neutron detection efficiency as high as 50–70% makes detectors with 10B-doped Microchannel Plates (MCPs) very attractive for neutron radiography and microtomography applications. The subsequent signal amplification preserves the location of the event within the MCP pore (typically 6–10 ?m in diameter), providing the possibility to perform neutron counting with high spatial resolution. Different event centroiding techniques of the charge landing on a patterned anode enable accurate reconstruction of the neutron position, provided the charge footprints do not overlap within the time required for event processing. The new fast 2×2 Timepix readout with >1.2 kHz frame rates provides the unique possibility to detect neutrons with sub-15 ?m resolution at several MHz/cm2 counting rates. The results of high resolution neutron radiography experiments presented in this paper, demonstrate the sub-15 ?m resolution capability of our detection system. The high degree of collimation and cold spectrum of ICON and BOA beamlines combined with the high spatial resolution and detection efficiency of MCP-Timepix detectors are crucial for high contrast neutron radiography and microtomography with high spatial resolution. The next generation of Timepix electronics with sparsified readout should enable counting rates in excess of 107 n/cm2/s taking full advantage of high beam intensity of present brightest neutron imaging facilities.

127

Progressive track finding coupled with track fitting by the Kalman filtering method  

International Nuclear Information System (INIS)

A progressive track finding algorithm based on the Kalman filtering method has been proposed and tested for the track reconstruction in high energy physics experiment. The algorithm starts from small track segments with fitted track parameters and weight matrices or from fitted tracks of a neighboring detector, then extends the candidate tracks by adding measured points one by one. The track parametes and weight matrices of the candidate tracks are updated at the same time of each point addition. Therefore at the end of the track finding, the track fitting is accomplished simultaneously. The main procedures and its advantages of the algorithm are presented. Its performance is briefed

128

Optimization of the fermentation media for sophorolipid production from Candida bombicola ATCC 22214 using a simplex centroid design.  

Science.gov (United States)

This article describes the use of a simplex centroid mixture experimental design to optimize the fermentation medium in the production of sophorolipids (SLs) using Candida bombicola. In the first stage, 16 media ingredients were screened for the ones that have the most positive influence on the SL production. The sixteen ingredients that were chosen are five different carbohydrates (fructose, glucose, glycerol, lactose, and sucrose), five different nitrogen sources (malt extract, peptone extract, soytone, urea, and yeast extract), two lipid sources (mineral oil and oleic acid), two phosphorus sources (K(2)HPO(4) and KH(2)PO(4)), MgSO(4), and CaCl(2). Multiple regression analysis and centroid effect analysis were carried out to find the sugar, lipid, nitrogen source, phosphorus source, and metals having the most positive influence. Sucrose, malt extract, oleic acid, K(2)HPO(4), and CaCl(2) were selected for the second stage of experiments. An augmented simplex centroid design for five ingredients requiring 16 experiments was used for the optimization stage. This produced a quadratic model developed to help understand the interaction amongst the ingredients and find the optimal media concentrations. In addition, the top three results from the optimization experiments were used to obtain constraints that identify an optimal region. The model together with the optimal region constraints predicts the maximum production of SLs when the fermentation media is composed of sucrose, 125 g/L; malt extract, 25 g/L; oleic acid, 166.67 g/L; K(2)HPO(4), 1.5 g/L; and CaCl(2), 2.5 g/L. The optimal media was validated experimentally and a yield of 177 g/L was obtained. PMID:20205261

Rispoli, Fred J; Badia, Daniel; Shah, Vishal

2010-01-01

129

Combined node and link partitions method for finding overlapping communities in complex networks.  

Science.gov (United States)

Community detection in complex networks is a fundamental data analysis task in various domains, and how to effectively find overlapping communities in real applications is still a challenge. In this work, we propose a new unified model and method for finding the best overlapping communities on the basis of the associated node and link partitions derived from the same framework. Specifically, we first describe a unified model that accommodates node and link communities (partitions) together, and then present a nonnegative matrix factorization method to learn the parameters of the model. Thereafter, we infer the overlapping communities based on the derived node and link communities, i.e., determine each overlapped community between the corresponding node and link community with a greedy optimization of a local community function conductance. Finally, we introduce a model selection method based on consensus clustering to determine the number of communities. We have evaluated our method on both synthetic and real-world networks with ground-truths, and compared it with seven state-of-the-art methods. The experimental results demonstrate the superior performance of our method over the competing ones in detecting overlapping communities for all analysed data sets. Improved performance is particularly pronounced in cases of more complicated networked community structures. PMID:25715829

Jin, Di; Gabrys, Bogdan; Dang, Jianwu

2015-01-01

130

Combined node and link partitions method for finding overlapping communities in complex networks  

Science.gov (United States)

Community detection in complex networks is a fundamental data analysis task in various domains, and how to effectively find overlapping communities in real applications is still a challenge. In this work, we propose a new unified model and method for finding the best overlapping communities on the basis of the associated node and link partitions derived from the same framework. Specifically, we first describe a unified model that accommodates node and link communities (partitions) together, and then present a nonnegative matrix factorization method to learn the parameters of the model. Thereafter, we infer the overlapping communities based on the derived node and link communities, i.e., determine each overlapped community between the corresponding node and link community with a greedy optimization of a local community function conductance. Finally, we introduce a model selection method based on consensus clustering to determine the number of communities. We have evaluated our method on both synthetic and real-world networks with ground-truths, and compared it with seven state-of-the-art methods. The experimental results demonstrate the superior performance of our method over the competing ones in detecting overlapping communities for all analysed data sets. Improved performance is particularly pronounced in cases of more complicated networked community structures. PMID:25715829

Jin, Di; Gabrys, Bogdan; Dang, Jianwu

2015-01-01

131

Combined node and link partitions method for finding overlapping communities in complex networks  

Science.gov (United States)

Community detection in complex networks is a fundamental data analysis task in various domains, and how to effectively find overlapping communities in real applications is still a challenge. In this work, we propose a new unified model and method for finding the best overlapping communities on the basis of the associated node and link partitions derived from the same framework. Specifically, we first describe a unified model that accommodates node and link communities (partitions) together, and then present a nonnegative matrix factorization method to learn the parameters of the model. Thereafter, we infer the overlapping communities based on the derived node and link communities, i.e., determine each overlapped community between the corresponding node and link community with a greedy optimization of a local community function conductance. Finally, we introduce a model selection method based on consensus clustering to determine the number of communities. We have evaluated our method on both synthetic and real-world networks with ground-truths, and compared it with seven state-of-the-art methods. The experimental results demonstrate the superior performance of our method over the competing ones in detecting overlapping communities for all analysed data sets. Improved performance is particularly pronounced in cases of more complicated networked community structures.

Jin, Di; Gabrys, Bogdan; Dang, Jianwu

2015-02-01

132

Single-ended transition state finding with the growing string method.  

Science.gov (United States)

Reaction path finding and transition state (TS) searching are important tasks in computational chemistry. Methods that seek to optimize an evenly distributed set of structures to represent a chemical reaction path are known as double-ended string methods. Such methods can be highly reliable because the endpoints of the string are fixed, which effectively lowers the dimensionality of the reaction path search. String methods, however, require that the reactant and product structures are known beforehand, which limits their ability for systematic exploration of reactive steps. In this article, a single-ended growing string method (GSM) is introduced which allows for reaction path searches starting from a single structure. The method works by sequentially adding nodes along coordinates that drive bonds, angles, and/or torsions to a desired reactive outcome. After the string is grown and an approximate reaction path through the TS is found, string optimization commences and the exact TS is located along with the reaction path. Fast convergence of the string is achieved through use of internal coordinates and eigenvector optimization schemes combined with Hessian estimates. Comparison to the double-ended GSM shows that single-ended method can be even more computationally efficient than the already rapid double-ended method. Examples, including transition metal reactivity and a systematic, automated search for unknown reactivity, demonstrate the efficacy of the new method. This automated reaction search is able to find 165 reaction paths from 333 searches for the reaction of NH3 BH3 and (LiH)4 , all without guidance from user intuition. © 2015 Wiley Periodicals, Inc. PMID:25581279

Zimmerman, Paul M

2015-04-15

133

Finite difference method to find period-one gait cycles of simple passive walkers  

Science.gov (United States)

Passive dynamic walking refers to a class of bipedal robots that can walk down an incline with no actuation or control input. These bipeds are sensitive to initial conditions due to their style of walking. According to small basin of attraction of passive limit cycles, it is important to start with an initial condition in the basin of attraction of stable walking (limit cycle). This paper presents a study of the simplest passive walker with point and curved feet. A new approach is proposed to find proper initial conditions for a pair of stable and unstable period-one gait limit cycles. This methodology is based on finite difference method which can solve the nonlinear differential equations of motion on a discrete time. Also, to investigate the physical configurations of the walkers and the environmental influence such as the slope angle, the parameter analysis is applied. Numerical simulations reveal the performance of the presented method in finding two stable and unstable gait patterns.

Dardel, Morteza; Safartoobi, Masoumeh; Pashaei, Mohammad Hadi; Ghasemi, Mohammad Hassan; Navaei, Mostafa Kazemi

2015-01-01

134

High-speed on-chip windowed centroiding using photodiode-based CMOS imager  

Science.gov (United States)

A centroid computation system is disclosed. The system has an imager array, a switching network, computation elements, and a divider circuit. The imager array has columns and rows of pixels. The switching network is adapted to receive pixel signals from the image array. The plurality of computation elements operates to compute inner products for at least x and y centroids. The plurality of computation elements has only passive elements to provide inner products of pixel signals the switching network. The divider circuit is adapted to receive the inner products and compute the x and y centroids.

Pain, Bedabrata (Inventor); Sun, Chao (Inventor); Yang, Guang (Inventor); Cunningham, Thomas J. (Inventor); Hancock, Bruce (Inventor)

2003-01-01

135

Methods in finding the Q2-dependent nucleon parton distribution functions in the constituent quark model  

International Nuclear Information System (INIS)

The deconvolution problem of the Constituent Quark Model (CQM) in finding the parton distribution function in valon at Q02 is reduced to an optimum problem and solved successfully with Newton-Raphson method. Moreover, by discretizing the QCD evolution equations into ordinary simultaneous differential equations, the author obtained the parton distribution functions in valon at arbitrary Q2>Q02, and thus, through convolution, finally found the Q2-dependent nucleon parton distribution functions in CQM picture

136

Monte Carlo evaluation of a new track-finding method for the VENUS muon detector  

International Nuclear Information System (INIS)

A new method of finding a track is devised for the VENUS muon detector composed of eight-cell drift-tube modules, each cell having a rectangular cross section of 5 x 7 cm2. The new method, in which fourth-order equations are solved by the Ferarri-Cardano method, is especially powerful for a track having a large incident angle with respect to the line normal to the anode-wire plane of a drift tube, compared to the presently used method in which a track is determined by the intersecting points of an equi-drift-distance circle and the anode-wire plane. Cosmic-ray test data for the forward-backward part muon detector support these simulation results. (author)

137

Dilation method for finding close roots of polynomials based on constrained learning neural networks  

International Nuclear Information System (INIS)

In finding roots of polynomials, often two or more roots that are close together in solution space are very difficult to be resolved by a root-finder. To solve this problem, this Letter proposes a dilation method to transform the positions of roots in space so that all roots in space are pulled further apart. As a result, those close (including complex) roots can be readily resolved efficiently by a root-finder. In addition, in this Letter a complex version of constrained learning algorithm is derived. Moreover, our previously proposing feedforward neural network (FNN) root-finder is adopted to address the root finding issue. Finally, some satisfactory results that support our approach are presented

138

Dilation method for finding close roots of polynomials based on constrained learning neural networks  

Energy Technology Data Exchange (ETDEWEB)

In finding roots of polynomials, often two or more roots that are close together in solution space are very difficult to be resolved by a root-finder. To solve this problem, this Letter proposes a dilation method to transform the positions of roots in space so that all roots in space are pulled further apart. As a result, those close (including complex) roots can be readily resolved efficiently by a root-finder. In addition, in this Letter a complex version of constrained learning algorithm is derived. Moreover, our previously proposing feedforward neural network (FNN) root-finder is adopted to address the root finding issue. Finally, some satisfactory results that support our approach are presented.

Huang, D.-S.; Ip, Horace H.S.; Chi Zheru; Wong, H.S

2003-03-31

139

A method for finding the ridge between saddle points applied to rare event rate estimates  

DEFF Research Database (Denmark)

A method is presented for finding the ridge between first order saddle points on a multidimensional surface. For atomic scale systems, such saddle points on the energy surface correspond to atomic rearrangement mechanisms. Information about the ridge can be used to test the validity of the harmonic approximation to transition state theory, in particular to verify that second order saddle points—maxima along the ridge—are high enough compared to the first order saddle points. New minima along the ridge can also be identified during the path optimisation, thereby revealing additional transition mechanisms. The method is based on a string of discretisation points along a path between the first order saddle points and using an iterative optimisation which requires only the force acting on the atoms. At each iteration during the optimisation, the force is inverted along an unstable eigenmode perpendicular to the path. The method is applied to Al adatom diffusion on the Al(100) surface to find the ridge between 2-,3- and 4-atom concerted displacements and hop mechanisms. A correction to the harmonic approximation of transition state theory was estimated by direct evaluation of the configuration integral along the ridge.

Maronsson, Jon Bergmann; Jónsson, Hannes

2012-01-01

140

Minima hopping guided path search: an efficient method for finding complex chemical reaction pathways.  

Science.gov (United States)

The Minima Hopping global optimization method uses physically realizable molecular dynamics moves in combination with an energy feedback that guarantees the escape from any potential energy funnel. For the purpose of finding reaction pathways, we argue that Minima Hopping is particularly suitable as a guide through the potential energy landscape and as a generator for pairs of minima that can be used as input structures for methods capable of finding transition states between two minima. For Lennard-Jones benchmark systems we compared this Minima Hopping guided path search method to a known approach for the exploration of potential energy landscapes that is based on deterministic mode-following. Although we used a stabilized mode-following technique that reliably allows to follow distinct directions when escaping from a local minimum, we observed that Minima Hopping guided path search is far superior in finding lowest-barrier reaction pathways. We, therefore, suggest that Minima Hopping guided path search can be used as a simple and efficient way to identify energetically low-lying chemical reaction pathways. Finally, we applied the Minima Hopping guided path search approach to 75-atom and 102-atom Lennard-Jones systems. For the 75-atom system we found pathways whose highest energies are significantly lower than the highest energy along the previously published lowest-barrier pathway. Furthermore, many of these pathways contain a smaller number of intermediate transition states than the previously publish lowest-barrier pathway. In case of the 102-atom system Minima Hopping guided path search found a previously unknown and energetically low-lying funnel. PMID:24907985

Schaefer, Bastian; Mohr, Stephan; Amsler, Maximilian; Goedecker, Stefan

2014-06-01

141

A compilation of jet finding algorithms  

International Nuclear Information System (INIS)

Technical descriptions of jet finding algorithms currently in use in p anti p collider experiments (CDF, UA1, UA2), e+e- experiments and Monte-Carlo event generators (LUND programs, ISAJET) have been collected. For the hadron collider experiments, the clustering methods fall into two categories: cone algorithms and nearest-neighbor algorithms. In addition, UA2 has employed a combination of both methods for some analysis. While there are clearly differences between the cone and nearest-neighbor algorithms, the authors have found that there are also differences among the cone algorithms in the details of how the centroid of a cone cluster is located and how the ET and PT of the jet are defined. The most commonly used jet algorithm in electron-positron experiments is the JADE-type cluster algorithm. Five various incarnations of this approach have been described

142

Novas abordagens da avaliação do comportamento tático no futebol: análise do centroid e índice de dispersão / Towards a new evaluation of the football' tactical behaviour: analysis of the centroid and stretch index  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A tendência evolutiva do futebol determina as necessidades de produzir ferramentas inovadoras que aumentem substancialmente a eficiência da análise de jogo. Considerando os métodos tradicionais notacionais como limitados para a interpretação dos processos de jogo, a investigação carece de novos méto [...] dos nos quais prevaleça a análise do processo. Dessa forma, o presente trabalho propõe-se a analisar novas métricas quantitativas e automáticas de avaliação tática no futebol, nomeadamente o centroid de equipe e o índice de dispersão. Abstract in english The evolutionary tendency of the football game determines the conception of the new tools that increase the efficiency of the match analysis. The traditional notational analysis, actually, are limited to understand the true dynamic of the football match, thus the investigation lacks by new methods t [...] o understand the process and not just the product. Therefore, this work aims analyze new automatically tactical metrics, specifically the centroid and the stretch index method.

Rui Manuel, Mendes; Filipe Manuel, Clemente; Micael Santos, Couceiro; Fernando Manuel Lourenço, Martins.

2013-12-01

143

Application of a Bayesian method to absorption spectral-line finding in simulated ASKAP data  

CERN Document Server

The large spectral bandwidth and wide field-of-view of the Australian SKA Pathfinder radio telescope will open up a completely new parameter space for large extragalactic HI surveys. Here we focus on identifying and parametrising HI absorption-lines which occur in the line of sight towards strong radio continuum sources. We have developed a method for simultaneously finding and fitting HI absorption-lines in radio data by using multi-nested sampling, a Bayesian Monte-arlo algorithm. The method is tested on a simulated ASKAP data cube, and is shown to be reliable at detecting absorption-lines in low signal-to-noise data without the need to smooth or alter the data. Estimation of the local Bayesian evidence statistic provides a quantitative criterion for assigning significance to a detection and selecting between competing analytical line-profile models.

Allison, J R; Whiting, M T

2011-01-01

144

A new method of finding all Roots of simple quaternionic polynomials  

CERN Document Server

In this paper, we provide a new method to find all zeros of polynomials with quaternionic coefficients located on only one side of the powers of the variable (these polynomials are called simple polynomials). This method is much more efficient and much simpler than the known one in [D. Janovska and G. Opfer, A note on the computation of all zeros of simple quaternionic polynomials, SIAM J. Numer. Anal., 48(1)(2010), pp. 244-256]. We recover several known results, and deduce several interesting consequences concerning solving equations with all real coefficients or complex coefficients which do not seem to be deduced easily from the results in [D. Janovska and G. Opfer, A note on the computation of all zeros of simple quaternionic polynomials, SIAM J. Numer. Anal., 48(1)(2010), pp. 244-256]. We also give a necessary and sufficient condition for a simple quaternionic polynomials to have finitely many solutions (only isolated solutions).

Feng, Lianggui

2011-01-01

145

A measure of variable planar locations anchored on the centroid of the vowel space : A sociophonetic research tool  

DEFF Research Database (Denmark)

This paper presents part of an ongoing research program which aims to apply mathematical and geometrical analytic methods to vowel formant data to enable the quantification of parameters of variation of interest to sociophoneticians. We open with an overview of recent research working towards a set of desiderata for choice of normalization algorithm(s) based on replicable procedures. We then present the principles of centroid-based normalization and account for its performance in recent road tests. In sections 4 and 5 we introduce a method that utilizes the centroid of the speaker’s vowel space as an anchor point or vertex for calculation of planar locations on formant plots, permitting quantification of the distribution of vowel tokens within the space. This information, along with details such as Euclidean distances, can then be used to precisely pinpoint the trajectories of diachronic change, for instance over a set of speakers in different age groups within a defined speech community. This has the advantage of mathematical reproducibility, and reduces the level of subjectivity in visual analyses of formant plots used in investigations of vowel variability and change in progress.

Watt, Dominic; Fabricius, Anne

2011-01-01

146

A method for automatic matching of multi-timepoint findings for enhanced clinical workflow  

Science.gov (United States)

Non-interventional diagnostics (CT or MR) enables early identification of diseases like cancer. Often, lesion growth assessment done during follow-up is used to distinguish between benign and malignant ones. Thus correspondences need to be found for lesions localized at each time point. Manually matching the radiological findings can be time consuming as well as tedious due to possible differences in orientation and position between scans. Also, the complicated nature of the disease makes the physicians to rely on multiple modalities (PETCT, PET-MR) where it is even more challenging. Here, we propose an automatic feature-based matching that is robust to change in organ volume, subpar or no registration that can be done with very less computations. Traditional matching methods rely mostly on accurate image registration and applying the resulting deformation map on the findings coordinates. This has disadvantages when accurate registration is time-consuming or may not be possible due to vast organ volume differences between scans. Our novel matching proposes supervised learning by taking advantage of the underlying CAD features that are already present and considering the matching as a classification problem. In addition, the matching can be done extremely fast and at reasonable accuracy even when the image registration fails for some reason. Experimental results? on real-world multi-time point thoracic CT data showed an accuracy of above 90% with negligible false positives on a variety of registration scenarios.

Raghupathi, Laks; Dinesh, MS; Devarakota, Pandu R.; Valadez, Gerardo Hermosillo; Wolf, Matthias

2013-03-01

147

ISAR imaging of maneuvering targets based on the range centroid Doppler technique.  

Science.gov (United States)

A new inverse synthetic aperture radar (ISAR) imaging approach is presented for application in situations where the maneuverability of noncooperative target is not too severe and the Doppler variation of subechoes from scatterers can be approximated as a first-order polynomial. The proposed algorithm is referred to as the range centroid Doppler (RCD) ISAR imaging technique and is based on the stretch Keystone-Wigner transform (SKWT). The SKWT introduces a stretch weight factor containing a range of chirp rate into the autocorrelation function of each cross-range profile and uses a 1-D interpolation of the phase history which we call stretch keystone formatting. The processing simultaneously eliminates the effects of linear frequency migration for all signal components regardless of their unknown chirp rate in time-frequency plane, but not for the noise or for the cross terms. By utilizing this novel technique, clear ISAR imaging can be achieved for maneuvering targets without an exhaustive search procedure for the motion parameters. Performance comparison is carried out to evaluate the improvement of the RCD technique versus other methods such as the conventional range Doppler (RD) technique, the range instantaneous Doppler (RID) technique, and adaptive joint time-frequency (AJTF) technique. Examples provided demonstrate the effectiveness of the RCD technique with both simulated and experimental ISAR data. PMID:19775968

Lv, Xiaolei; Xing, Mengdao; Wan, Chunru; Zhang, Shouhong

2010-01-01

148

Detection of a surface breaking crack by using the centroid variations of laser ultrasonic spectrums  

International Nuclear Information System (INIS)

A laser ultrasonic system is a non-contact inspection device with a wide-band spectrum and a high spatial resolution. It provides absolute measurements of the moving distance and it can be applied to hard-to-access locations including curved or rough surfaces like in a nuclear power plant. In this paper, we have investigated the detection methods of the depth of a surface-breaking crack by using the surface wave of a laser ultrasound. The filtering function of a surface-breaking crack is a kind of a low-pass filter. The higher frequency components are more highly decreased in proportion to the crack depth. Also, the center frequency value of each ultrasound spectrum is decreased in proportion to the crack depth. We extracted the depth information of a surface-breaking crack by observing the centroid variation of the frequency spectrum. We describe the experimental results to detect the crack depth information by using the peak-to-valley values in the time domain and the center frequency values in the frequency domain.

149

New algorithm for centroiding in elongated spots for Shack-Hartmann wavefront sensors using artificial neural networks  

Science.gov (United States)

To recover the resolution lost in a ground-based telescopes due to the atmospheric turbulence, it is necessary to use a technique known as Adaptive Optics (AO). The next generation of telescopes will have primary mirrors of more than 30 meter in diameter and will require AO systems from the ground up (Nelson et al. 2006). There are a number of challenges to implement an AO system at these scales. One of these challenges is the accurate measurement of the aberrated wavefronts using a laser guide star and a Shack-Hartmann wavefront sensor. Due to the diameter of the telescope and the use of the sodium layer in the upper atmosphere as photon return for the laser guide stars, the image of the guide star will appear elongated in the wavefront sensor. Typical centroiding algorithms such as Center of Gravity do not perform well under these conditions (Thomas et al. 2008). We present a new technique based on artificial neural networks for measuring the spot position with better accuracy than existing methods. Simulation results confirms that the new algorithm incurs in smaller errors with respect to other centroiding techniques in use.

Mello, A. T.; Kanaan, A.; Guzmán, D.

2014-10-01

150

School Locations and Traffic Emissions — Environmental (InJustice Findings Using a New Screening Method  

Directory of Open Access Journals (Sweden)

Full Text Available It has been shown that the location of schools near heavily trafficked roads can have detrimental effects on the health of children attending those schools. It is therefore desirable to screen both existing school locations and potential new school sites to assess either the need for remedial measures or suitability for the intended use. Current screening tools and public guidance on school siting are either too coarse in their spatial resolution for assessing individual sites or are highly resource intensive in their execution (e.g., through dispersion modeling. We propose a new method to help bridge the gap between these two approaches. Using this method, we also examine the public K-12 schools in the Sacramento Area Council of Governments Region, California (USA from an environmental justice perspective. We find that PM2.5 emissions from road traffic affecting a school site are significantly positively correlated with the following metrics: percent share of Black, Hispanic and multi-ethnic students, percent share of students eligible for subsidized meals. The emissions metric correlates negatively with the schools’ Academic Performance Index, the share of White students and average parental education levels. Our PM2.5 metric also correlates with the traffic related, census tract level screening indicators from the California Communities Environmental Health Screening Tool and the tool’s tract level rate of asthma related emergency department visits.

Philine Gaffron

2015-02-01

151

School locations and traffic emissions—environmental (in)justice findings using a new screening method.  

Science.gov (United States)

It has been shown that the location of schools near heavily trafficked roads can have detrimental effects on the health of children attending those schools. It is therefore desirable to screen both existing school locations and potential new school sites to assess either the need for remedial measures or suitability for the intended use. Current screening tools and public guidance on school siting are either too coarse in their spatial resolution for assessing individual sites or are highly resource intensive in their execution (e.g., through dispersion modeling). We propose a new method to help bridge the gap between these two approaches. Using this method, we also examine the public K-12 schools in the Sacramento Area Council of Governments Region, California (USA) from an environmental justice perspective. We find that PM2.5 emissions from road traffic affecting a school site are significantly positively correlated with the following metrics: percent share of Black, Hispanic and multi-ethnic students, percent share of students eligible for subsidized meals. The emissions metric correlates negatively with the schools' Academic Performance Index, the share of White students and average parental education levels. Our PM2.5 metric also correlates with the traffic related, census tract level screening indicators from the California Communities Environmental Health Screening Tool and the tool's tract level rate of asthma related emergency department visits. PMID:25679341

Gaffron, Philine; Niemeier, Deb

2015-02-01

152

Old Wine in New Skins: The Sensitivity of Established Findings to New Methods  

Science.gov (United States)

Findings from an evaluation of a model system for delivering mental health services to youth were reassessed to determine the robustness of key findings to the use of methodologies unavailable to the original analysts. These analyses address a key concern about earlier findings--that the quasi-experimental design involved the comparison of two…

Foster, E. Michael; Wiley-Exley, Elizabeth; Bickman, Leonard

2009-01-01

153

Analytic expressions for energy centroids and widths in the microscopic collective model  

International Nuclear Information System (INIS)

Analytic formulae are given for the U(3) centroids of the collective Bohr-Mottelson potential in the microscopic collective model. In particular, formulae are reported for the centroids of the quadratic [QxQ proportional ?2] and cubic [Qx(Q x Q) proportional ?3cos3?] rotational scalars in the microscopic quadrupole operator. Favorable comparisons for ground-state intensities are achieved between shell-model diagonalizations and statistical predictions based upon the gaussian approximation to the energy density. These results suggest that statistical measures can be used reliably for truncation of the infinite-dimensional representation spaces of the microscopic symplectic collective theory. (orig.)

154

Performance of centroiding algorithms at low light level conditions in adaptive optics  

CERN Document Server

The performance metrics of different centroiding algorithms at low light level conditions were optimized in the case of a Shack Hartmann Sensor (SHS) for efficient performance of the adaptive optics system. For short exposures and low photon flux, the Hartmann spot does not have a Gaussian shape due to the photon noise which follows Poissonian statistics. The centroiding estimation error was calculated at different photon levels in the case of changing spot size and shift in the spot using Monte Carlo simulations. This analysis also proves to be helpful in optimizing the SHS specifications at low light levels.

Vyas, Akondi; Prasad, B Raghavendra; 10.1109/ARTCom.2009.30

2010-01-01

155

Quantum Imaging beyond the Diffraction Limit by Optical Centroid Measurements  

OpenAIRE

I propose a quantum imaging method that can beat the Rayleigh-Abbe diffraction limit and achieve de Broglie resolution without requiring a multi-photon absorber or coincidence detection. Using the same non-classical states of light as those for quantum lithography, the proposed method requires only optical intensity measurements, followed by image post-processing, to produce the same complex quantum interference patterns as those in quantum lithography. The method is expected to b...

Tsang, Mankei

2009-01-01

156

Case-finding for hepatitis C in primary care: a mixed-methods service evaluation  

Science.gov (United States)

Background Hepatitis C is often asymptomatic, presenting with liver failure and cancer decades after infection. People who inject drugs (PWID) and immigrant populations from countries with a moderate-to-high prevalence of hepatitis C virus (HCV) are the main risk groups. Deaths and hospital admissions due to HCV cirrhosis tripled between 1998 and 2010, but the majority of people with chronic HCV are unaware of it. Aim To identify patients at risk of developing hepatitis C using routine GP data, to determine the proportion not tested, and to explore GPs’ views regarding testing. Design and setting Mixed-methods service evaluation (density-based selection of PWID) in six NHS practices in Bristol. Method Patients at risk of HCV were identified. The Health Protection Agency laboratory (now part of Public Health England) provided test results. Semi-structured interviews with 17 GPs were audiorecorded and thematic analyses conducted on anonymised transcripts. Results Of 3765 patients identified as being at risk of developing hepatitis C, 3051 (81%) had no test result, including 53% of PWID and 93% of the ‘ethnicity’ group. All GPs said they usually test PWID. Most GPs test for HIV and hepatitis B in immigrants more often than they test for HCV. Barriers to testing included not questioning patients about risk factors, competing priorities, the chaotic lifestyle of PWID, difficulty extracting information from computerised records, and forgetting to address HCV. Conclusion Computer prompts and GP education on whom to test are warranted. Ensuring that country of origin and drug use is included on the new-patient questionnaire might also aid case-finding for HCV. PMID:24567619

Datta, Shivani; Horwood, Jeremy; Hickman, Matthew; Sharp, Debbie

2014-01-01

157

Research on the effect of noise at different times of day: Models, methods and findings  

Science.gov (United States)

Social surveys of residents' responses to noise at different times of day are reviewed. Some of the discrepancies in published reports about the importance of noise at different times of day are reduced when the research findings are classified according to the type of time of day reaction model, the type of time of day weight calculated and the method which is used to estimate the weight. When the estimates of nighttime weights from 12 studies are normalized, it is found that they still disagree, but do not support stronger nighttime weights than those used in existing noise indices. Challenges to common assumptions in nighttime response models are evaluated. Two of these challenges receive enough support to warrant further investigation: the impact of changes in numbers of noise events may be less at night than in the day and nighttime annoyance may be affected by noise levels in other periods. All existing social survey results in which averages of nighttime responses were plotted by nighttime noise levels are reproduced.

Fields, J. M.

1985-01-01

158

Transition state-finding strategies for use with the growing string method  

Science.gov (United States)

Efficient identification of transition states is important for understanding reaction mechanisms. Most transition state search algorithms require long computational times and a good estimate of the transition state structure in order to converge, particularly for complex reaction systems. The growing string method (GSM) [B. Peters et al., J. Chem. Phys. 120, 7877 (2004)] does not require an initial guess of the transition state; however, the calculation is still computationally intensive due to repeated calls to the quantum mechanics code. Recent modifications to the GSM [A. Goodrow et al., J. Chem. Phys. 129, 174109 (2008)] have reduced the total computational time for converging to a transition state by a factor of 2 to 3. In this work, three transition state-finding strategies have been developed to complement the speedup of the modified-GSM: (1) a hybrid strategy, (2) an energy-weighted strategy, and (3) a substring strategy. The hybrid strategy initiates the string calculation at a low level of theory (HF/STO-3G), which is then refined at a higher level of theory (B3LYP/6-31G?). The energy-weighted strategy spaces points along the reaction pathway based on the energy at those points, leading to a higher density of points where the energy is highest and finer resolution of the transition state. The substring strategy is similar to the hybrid strategy, but only a portion of the low-level string is refined using a higher level of theory. These three strategies have been used with the modified-GSM and are compared in three reactions: alanine dipeptide isomerization, H-abstraction in methanol oxidation on VOx/SiO2 catalysts, and C-H bond activation in the oxidative carbonylation of toluene to p-toluic acid on Rh(CO)2(TFA)3 catalysts. In each of these examples, the substring strategy was proved most effective by obtaining a better estimate of the transition state structure and reducing the total computational time by a factor of 2 to 3 compared to the modified-GSM. The applicability of the substring strategy has been extended to three additional examples: cyclopropane rearrangement to propylene, isomerization of methylcyclopropane to four different stereoisomers, and the bimolecular Diels-Alder condensation of 1,3-butadiene and ethylene to cyclohexene. Thus, the substring strategy used in combination with the modified-GSM has been demonstrated to be an efficient transition state-finding strategy for a wide range of types of reactions.

Goodrow, Anthony; Bell, Alexis T.; Head-Gordon, Martin

2009-06-01

159

Infant feeding experiences among teen mothers in North Carolina: Findings from a mixed-methods study  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Adolescent mothers in the U.S. are much less likely to initiate breastfeeding than older mothers, and teens who do initiate breastfeeding tend to breastfeed for shorter durations. The purpose of this mixed-methods study is to investigate breastfeeding practices, barriers and facilitators among adolescent mothers ages 17 and younger. Methods Quantitative descriptive analyses are conducted using data from the North Carolina Pregnancy Risk Assessment Monitoring System (PRAMS. The population-based sample comprises 389 teens ages 13-17 giving birth to a live born infant in North Carolina in 2000 - 2005 and in 2007. Qualitative analyses are based on in-depth interviews with 22 Black, White and Hispanic teen mothers residing in rural and urban areas of North Carolina conducted between November 2007 and February 2009. Results In quantitative analyses, 52% (196 of 389 of North Carolina teen mothers initiated breastfeeding, but half of those who initiated breastfeeding (92/196 stopped within the first month postpartum. Hispanic teens (44/52 or 89% were much more likely than Black (61/159 or 41% or White teens (87/164 or 52% to initiate breastfeeding and to continue for a longer duration. Nearly sixty two percent (29/52 of Hispanic respondents breastfed for greater than four weeks as compared to 16% (29/159 of Black respondents and 26% (39/164 of White respondents. Common barriers to breastfeeding initiation and continuation included not liking breastfeeding, returning to school, nipple pain, and insufficient milk. Qualitative data provided context for the quantitative findings, elucidating the barriers and facilitators to breastfeeding from the teens' perspective and insight into the ways in which breastfeeding support to teens could be enhanced. Conclusions The large number of adolescents ceasing breastfeeding within the first month points to the need for more individualized follow-up after hospital discharge in the first few days postpartum, to address common technical challenges and to provide assistance managing the transition back to school. Provision of an extra home visit or outpatient visit for teens within the first few days following hospital discharge, and advocacy to make schools more compatible with breastfeeding, could potentially help teens who desire to breastfeed to successfully continue. These interventions warrant further research to test their effectiveness among adolescents.

Samandari Ghazaleh

2011-09-01

160

A general centroid determination methodology, with application to multilayer dielectric structures and thermally stimulated current measurements  

Science.gov (United States)

A general methodology is developed to experimentally characterize the spatial distribution of occupied traps in dielectric films on a semiconductor. The effects of parasitics such as leakage, charge transport through more than one interface, and interface trap charge are quantitatively addressed. Charge transport with contributions from multiple charge species is rigorously treated. The methodology is independent of the charge transport mechanism(s), and is directly applicable to multilayer dielectric structures. The centroid capacitance, rather than the centroid itself, is introduced as the fundamental quantity that permits the generic analysis of multilayer structures. In particular, the form of many equations describing stacked dielectric structures becomes independent of the number of layers comprising the stack if they are expressed in terms of the centroid capacitance and/or the flatband voltage. The experimental methodology is illustrated with an application using thermally stimulated current (TSC) measurements. The centroid of changes (via thermal emission) in the amount of trapped charge was determined for two different samples of a triple-layer dielectric structure. A direct consequence of the TSC analyses is the rigorous proof that changes in interface trap charge can contribute, though typically not significantly, to thermally stimulated current.

Miller, S. L.; Fleetwood, D. M.; McWhorter, P. J.; Reber, R. A., Jr.; Murray, J. R.

1993-10-01

161

Finger vein identification using fuzzy-based k-nearest centroid neighbor classifier  

Science.gov (United States)

In this paper, a new approach for personal identification using finger vein image is presented. Finger vein is an emerging type of biometrics that attracts attention of researchers in biometrics area. As compared to other biometric traits such as face, fingerprint and iris, finger vein is more secured and hard to counterfeit since the features are inside the human body. So far, most of the researchers focus on how to extract robust features from the captured vein images. Not much research was conducted on the classification of the extracted features. In this paper, a new classifier called fuzzy-based k-nearest centroid neighbor (FkNCN) is applied to classify the finger vein image. The proposed FkNCN employs a surrounding rule to obtain the k-nearest centroid neighbors based on the spatial distributions of the training images and their distance to the test image. Then, the fuzzy membership function is utilized to assign the test image to the class which is frequently represented by the k-nearest centroid neighbors. Experimental evaluation using our own database which was collected from 492 fingers shows that the proposed FkNCN has better performance than the k-nearest neighbor, k-nearest-centroid neighbor and fuzzy-based-k-nearest neighbor classifiers. This shows that the proposed classifier is able to identify the finger vein image effectively.

Rosdi, Bakhtiar Affendi; Jaafar, Haryati; Ramli, Dzati Athiar

2015-02-01

162

Sum rules for isospin centroids in pick-up reactions on general multishell target states  

CERN Document Server

Sum Rules equations for pick-up reactions are presented for the first time for the energy centroids of states both for the isospin T_, which, at the present moment, are difficult to handle analytically. These terms are managed by combining these equations with the known stripping reactions equations. Sample applications of these equations to experimental data are presented.

Bansal, R K; Kumar, A; Kumar, Ashwani

1996-01-01

163

High-sensitivity fiber Bragg grating transverse force sensor based on centroid measurement of polarization-dependent loss  

Science.gov (United States)

The transverse force measurement by virtue of 'stress-induced birefringence effects' of a fiber Bragg grating (FBG) written in a standard telecom single-mode fiber is attractive in the field of internal strain sensing in materials and structures. However, the measurement suffers from the drawback of low transverse force sensitivity of the FBG. In this paper, we propose utilizing the centroid information of the polarization-dependent loss (PDL) evolution of FBG for transverse force measurements. The evolution of the PDL with wavelength for the transmitted signals with respect to transverse force was analyzed and numerically simulated. Experiments were carried out to verify the reasonability and feasibility of the measurement method. Good agreement between experimental results and numerical simulations has been obtained.

Wang, Yiping; Wang, Ming; Huang, Xiaoqin

2010-06-01

164

High-sensitivity fiber Bragg grating transverse force sensor based on centroid measurement of polarization-dependent loss  

International Nuclear Information System (INIS)

The transverse force measurement by virtue of 'stress-induced birefringence effects' of a fiber Bragg grating (FBG) written in a standard telecom single-mode fiber is attractive in the field of internal strain sensing in materials and structures. However, the measurement suffers from the drawback of low transverse force sensitivity of the FBG. In this paper, we propose utilizing the centroid information of the polarization-dependent loss (PDL) evolution of FBG for transverse force measurements. The evolution of the PDL with wavelength for the transmitted signals with respect to transverse force was analyzed and numerically simulated. Experiments were carried out to verify the reasonability and feasibility of the measurement method. Good agreement between experimental results and numerical simulations has been obtained

165

Heap Base Coordinator Finding with Fault Tolerant Method in Distributed Systems  

Directory of Open Access Journals (Sweden)

Full Text Available Coordinator finding in wireless networks is a very important problem, and this problem is solved by suitable algorithms. The main goals of coordinator finding are synchronizing the processes at optimal using of the resources. Many different algorithms have been presented for coordinator finding. The most important leader election algorithms are the Bully and Ring algorithms. In this paper we analyze and compare these algorithms with together and we propose new approach with fault tolerant mechanisms base on heap for coordinator finding in wireless environment. Our algorithm's running time and message complexity compare favorably with existing algorithms. Our work involves substantial modifications of an existing algorithm and its proof, and we adapt the existing algorithms to the noisy environment base on fault tolerant mechanisms

Mehdi EffatParvar

2011-07-01

166

Moving Domestic Robotics Control Method Based on Creating and Sharing Maps with Shortest Path Findings and Obstacle Avoidance  

Directory of Open Access Journals (Sweden)

Full Text Available Control method for moving robotics in closed areas based on creation and sharing maps through shortest path findings and obstacle avoidance is proposed. Through simulation study, a validity of the proposed method is confirmed. Furthermore, the effect of map sharing among robotics is also confirmed together with obstacle avoidance with cameras and ultrasonic sensors.

Kohei Arai

2013-02-01

167

Alternatives for implementing methods for finding agents in a Multi-Agent Systems  

OpenAIRE

Interaction is an essential characteristic of Multi- Agent Systems (MASs). Agents that are part of a MAS usually interact by exchanging messages accord- ing to some conversation policy. Therefore, the ability to find other agents and exchange messages with them are features that need to be implemented in agents that are part of a MAS. Finding an agent means been aware of it existence and obtaining the information needed to send to it a message. There exists different alternatives of implement...

Tucat, Mariano; Garci?a, Alejandro Javier

2006-01-01

168

CT findings of pancreatic carcinoma. Evaluation with the combined method of early enhancement CT and high dose enhancement CT  

Energy Technology Data Exchange (ETDEWEB)

Computed tomographic (CT) findings of pancreatic ductal adenocarcinoma were studied with the combined method of early enhancement CT and high dose enhancement CT in 72 carcinomas. Common Findings were change in pancreatic contour, abnormal attenuation in a tumor and dilatation of the main pancreatic duct. The incidence of abnormal attenuation and dilatation of the main pancreatic duct and bile duct was constant regardless of tumor size. The finding of hypoattenuation at early enhancement CT was most useful for demonstrating a carcinoma. However, this finding was negative in ten cases, five of which showed inhomogenous hyperattenuation at high dose enhancement CT. The detection of change in pancreatic contour and dilatation of the main pancreatic duct was most frequent at high dose enhancement CT. The finding of change in pancreatic contour and/or abnormal attenuation in a tumor could be detected in 47 cases at plain CT, 66 at early enhancement CT and 65 at high dose enhancement CT. Since the four cases in which neither finding was detected by any CT method showed dilatated main pancreatic duct, there was no case without abnormal CT findings. This combined CT method will be a reliable diagnostic technique in the imaging of pancreatic carcinoma. (author).

Itoh, Shigeki; Endo, Tokiko; Isomura, Takayuki; Ishigaki, Takeo [Nagoya Univ. (Japan). School of Medicine; Ikeda, Mitsuru; Senda, Kouhei

1995-06-01

169

CT findings of pancreatic carcinoma. Evaluation with the combined method of early enhancement CT and high dose enhancement CT  

International Nuclear Information System (INIS)

Computed tomographic (CT) findings of pancreatic ductal adenocarcinoma were studied with the combined method of early enhancement CT and high dose enhancement CT in 72 carcinomas. Common Findings were change in pancreatic contour, abnormal attenuation in a tumor and dilatation of the main pancreatic duct. The incidence of abnormal attenuation and dilatation of the main pancreatic duct and bile duct was constant regardless of tumor size. The finding of hypoattenuation at early enhancement CT was most useful for demonstrating a carcinoma. However, this finding was negative in ten cases, five of which showed inhomogenous hyperattenuation at high dose enhancement CT. The detection of change in pancreatic contour and dilatation of the main pancreatic duct was most frequent at high dose enhancement CT. The finding of change in pancreatic contour and/or abnormal attenuation in a tumor could be detected in 47 cases at plain CT, 66 at early enhancement CT and 65 at high dose enhancement CT. Since the four cases in which neither finding was detected by any CT method showed dilatated main pancreatic duct, there was no case without abnormal CT findings. This combined CT method will be a reliable diagnostic technique in the imaging of pancreatic carcinoma. (author)

170

4D tumor centroid tracking using orthogonal 2D dynamic MRI: Implications for radiotherapy planning  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Current pretreatment, 4D imaging techniques are suboptimal in that they sample breathing motion over a very limited “snapshot” in time. Heretofore, long-duration, 4D motion characterization for radiotherapy planning, margin optimization, and validation have been impractical for safety reasons, requiring invasive markers imaged under x-ray fluoroscopy. To characterize 3D tumor motion and associated variability over durations more consistent with treatments, the authors have developed a practical dynamic MRI (dMRI) technique employing two orthogonal planes acquired in a continuous, interleaved fashion.Methods: 2D balanced steady-state free precession MRI was acquired continuously over 9–14 min at approximately 4 Hz in three healthy volunteers using a commercial 1.5 T system; alternating orthogonal imaging planes (sagittal, coronal, sagittal, etc.) were employed. The 2D in-plane pixel resolution was 2 × 2 mm{sup 2} with a 5 mm slice profile. Simultaneous with image acquisition, the authors monitored a 1D surrogate respiratory signal using a device available with the MRI system. 2D template matching-based anatomic feature registration, or tracking, was performed independently in each orientation. 4D feature tracking at the raw frame rate was derived using spline interpolation.Results: Tracking vascular features in the lung for two volunteers and pancreatic features in one volunteer, the authors have successfully demonstrated this method. Registration error, defined here as the difference between the sagittal and coronal tracking result in the SI direction, ranged from 0.7 to 1.6 mm (1?) which was less than the acquired image resolution. Although the healthy volunteers were instructed to relax and breathe normally, significantly variable respiration was observed. To demonstrate potential applications of this technique, the authors subsequently explored the intrafraction stability of hypothetical tumoral internal target volumes and 3D spatial probability distribution functions. The surrogate respiratory information allowed the authors to show how this technique can be used to study correlations between internal and external (surrogate) information over these prolonged durations. However, compared against the gold standard of the time stamps in the dMRI frames, the temporal synchronization of the surrogate 1D respiratory information was shown to be likely unreliable.Conclusions: The authors have established viability of a novel and practical pretreatment, 4D tumor centroid tracking method employing a commercially available dynamic MRI sequence. Further developments from the vendor are likely needed to provide a reliably synchronized surrogate 1D respiratory signal, which will likely broaden the utility of this method in the pretreatment radiotherapy planning context.

Tryggestad, Erik [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Flammang, Aaron; Shea, Steven M. [Center for Applied Medical Imaging, Siemens Corporation, Corporate Technology, Baltimore, Maryland 21205 (United States); Hales, Russell; Herman, Joseph; Lee, Junghoon; McNutt, Todd; Roland, Teboh; Wong, John [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States)

2013-09-15

171

4D tumor centroid tracking using orthogonal 2D dynamic MRI: Implications for radiotherapy planning  

International Nuclear Information System (INIS)

Purpose: Current pretreatment, 4D imaging techniques are suboptimal in that they sample breathing motion over a very limited “snapshot” in time. Heretofore, long-duration, 4D motion characterization for radiotherapy planning, margin optimization, and validation have been impractical for safety reasons, requiring invasive markers imaged under x-ray fluoroscopy. To characterize 3D tumor motion and associated variability over durations more consistent with treatments, the authors have developed a practical dynamic MRI (dMRI) technique employing two orthogonal planes acquired in a continuous, interleaved fashion.Methods: 2D balanced steady-state free precession MRI was acquired continuously over 9–14 min at approximately 4 Hz in three healthy volunteers using a commercial 1.5 T system; alternating orthogonal imaging planes (sagittal, coronal, sagittal, etc.) were employed. The 2D in-plane pixel resolution was 2 × 2 mm2 with a 5 mm slice profile. Simultaneous with image acquisition, the authors monitored a 1D surrogate respiratory signal using a device available with the MRI system. 2D template matching-based anatomic feature registration, or tracking, was performed independently in each orientation. 4D feature tracking at the raw frame rate was derived using spline interpolation.Results: Tracking vascular features in the lung for two volunteers and pancreatic features in one volunteer, the authors have successfully demonstrated this method. Registration error, defined here as the difference between the sagittal and coronal tracking result in the SI direction, ranged from 0.7 to 1.6 mm (1?) which was less than the acquired image resolution. Although the healthy volunteers were instructed to relax and breathe normally, significantly variable respiration was observed. To demonstrate potential applications of this technique, the authors subsequently explored the intrafraction stability of hypothetical tumoral internal target volumes and 3D spatial probability distribution functions. The surrogate respiratory information allowed the authors to show how this technique can be used to study correlations between internal and external (surrogate) information over these prolonged durations. However, compared against the gold standard of the time stamps in the dMRI frames, the temporal synchronization of the surrogate 1D respiratory information was shown to be likely unreliable.Conclusions: The authors have established viability of a novel and practical pretreatment, 4D tumor centroid tracking method employing a commercially available dynamic MRI sequence. Further developments from the vendor are likely needed to provide a reliably synchronized surrogate 1D respiratory signal, which will likely broaden the utility of this method in the pretreatment radiotherapy planning context

172

Finding out the most used booking methods and targeting marketing channels at specific customer segments : Case: Kemi Tourism Ltd.  

OpenAIRE

This study is assigned by Kemi Tourism Ltd. The objective of this thesis research is to find out the most frequently used booking methods used by the customers in different countries and target the assignor’s marketing channels at specific customer segments. The methods used are both quantitative and qualitative research, but the main focus is on the quantitative method. We utilized the Travius booking system when collecting the required information and statistics. We have used literat...

Tyta?rniemi, Niina; Hiltunen, Emma-lotta

2014-01-01

173

A computer method of finding valuations forcing validity of LC formulae  

Science.gov (United States)

The purpose of this paper is to present the computer implementation of a system known as LC temporal logic [1]. Firstly, to become familiar with some theoretical issues, a short introduction to this logic is discussed. The algorithms allowing a deep analysis of the formulae of LC logic are considered. In particular we discuss how to determine if a formula is a tautology, contrtautology or it is satisfable. Next, we show how to find all valuations to satisfy the formula. Finally, we consider finding histories generated by the formula and transforming these histories into the state machine. Moreover, a description of the experiments that verify the implementation are briefly presented.

Godlewski, ?ukasz; ?wietorzecka, Kordula; Mulawka, Jan

2014-11-01

174

A METHOD TO FIND SHORTEST RELIABLE PATH BY HARDWARE TESTING AND SOFTWARE IMPLEMENTATION  

Directory of Open Access Journals (Sweden)

Full Text Available This research paper is about shortest reliable path algorithms of routing in transportation networks. Efficient management of networks requires that the shortest route from one point (node to another is known. It is often necessary to be able to determine alternative routes through the network, in case any part of the shortest path isdamaged or busy which the computation of shortest paths is one of the most fundamental problems. It also focuses in finding the shortest reliable path algorithm. We need to find the path distance from the source to destination which is reliable and found in an optimized way considering the network constraints.

Mr. GHOLAMREZA KAKAMANSHADI

2011-07-01

175

The Exploration of the Artistic Methods and Significances of Cartoonised Characters of A Good Man Is Hard to Find  

Directory of Open Access Journals (Sweden)

Full Text Available Flannery O’Connor is one of the 20th Century Southern American writers, whose usual theme of absurdity and alienation is well embodied in her classic short story A Good Man Is Hard to Find. This paper mainly deals with the cartoonised characters, especially the granny. The artistic methods used to describe the characters are closely related to the following: realistic method, exaggerative method, metaphorical method, and symbolic method. This article attempts to explore the artistic methods used to describe the characters and their significances and also their contributions to the theme of absurdity and alienation.
Key words: A Good Man Is Hard to Find, cartoonised character, absurdity
Résumé Flannery O’Connor est une des femmes écrivains très connues des Etats-Unis du IIe siècle. Son recueil des nouvelles « A Good Man Is Hard to Find » attire surtout plus d’attention des lecteurs. Il décris des personnages humouristiques très vives, ce qui se traduit en évidence par la grand-mère. Les méthodes de description des personnages caricaturistes( les méthodes artistiques peuvent de résumer en : méthodes réalistique, méthode exagérative, méthode métaphorique et méthode symbolique. Cette thèse part des personnages humoristiques et cherche les formes de description et les significations des personnages dans des oeuves pour dévoiler le thème d’absurdité.
Mots-clés: A Good Man Is Hard to Find, les personnages humoristiques, l’absurdité.
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Ke-ke ZHANG

2005-06-01

176

Some improvements of the ART method for finding transition pathways on potential energy surfaces  

OpenAIRE

The Activation-Relaxation Technique nouveau (ARTn) is an eigenvector following method for systematic search of saddle points and transition pathways on a given potential energy surface. We propose a variation of this method aiming at improving the efficiency of the local convergence close to the saddle point. We prove the convergence and robustness of this new algorithm. The efficiency of the method is tested in the case of point defects in body centered cubic iron.

Cance?s, E.; Legoll, F.; Marinica, M. -c; Minoukadeh, K.; Willaime, F.

2008-01-01

177

Bayesian data augmentation methods for the synthesis of qualitative and quantitative research findings  

OpenAIRE

The possible utility of Bayesian methods for the synthesis of qualitative and quantitative research has been repeatedly suggested but insufficiently investigated. In this project, we developed and used a Bayesian method for synthesis, with the goal of identifying factors that influence adherence to HIV medication regimens. We investigated the effect of 10 factors on adherence. Recognizing that not all factors were examined in all studies, we considered standard methods for dealing with missin...

Crandell, Jamie L.; Voils, Corrine I.; Chang, Yunkyung; Sandelowski, Margarete

2011-01-01

178

A METHOD TO FIND SHORTEST RELIABLE PATH BY HARDWARE TESTING AND SOFTWARE IMPLEMENTATION  

OpenAIRE

This research paper is about shortest reliable path algorithms of routing in transportation networks. Efficient management of networks requires that the shortest route from one point (node) to another is known. It is often necessary to be able to determine alternative routes through the network, in case any part of the shortest path isdamaged or busy which the computation of shortest paths is one of the most fundamental problems. It also focuses in finding the shortest reliable path algorithm...

Mr. GHOLAMREZA KAKAMANSHADI; Naveenkumar Jiu, J.; Patil, Dr Suhas H.

2011-01-01

179

Artificial neural networks for centroiding elongated spots in Shack-Hartmann wavefront sensors  

CERN Document Server

The use of Adaptive Optics in Extremely Large Telescopes brings new challenges, one of which is the treatment of Shack-Hartmann Wavefront sensors images. When using this type of sensors in conjunction with laser guide stars for sampling the pupil of telescopes with 30+ m in diameter, it is necessary to compute the centroid of elongated spots, whose elongation angle and aspect ratio are changing across the telescope pupil. Existing techniques such as Matched Filter have been considered as the best technique to compute the centroid of elongated spots, however they are not good at coping with the effect of a variation in the Sodium profile. In this work we propose a new technique using artificial neural networks, which take advantage of the neural network's ability to cope with changing conditions, outperforming existing techniques in this context. We have developed comprehensive simulations to explore this technique and compare it with existing algorithms.

Mello, A T; Guzman, D; Guesalaga, A

2014-01-01

180

Finding Y-relevant part of X by use of PCR and PLSR model reduction methods  

OpenAIRE

The paper is considering the following question: using principal component regression (PCR) or partial least squares regression (PLSR), how much data can be removed from X while retaining the original ability to predict Y? Two model reduction methods using similarity transformations are discussed, one giving projections of original loadings onto the column space of the fitted response matrix (essentially the orthogonal signal correction (OSC) methods), and one giving projections of original s...

Ergon, Rolf

2007-01-01

181

Infant feeding experiences among teen mothers in North Carolina: Findings from a mixed-methods study  

OpenAIRE

Abstract Background Adolescent mothers in the U.S. are much less likely to initiate breastfeeding than older mothers, and teens who do initiate breastfeeding tend to breastfeed for shorter durations. The purpose of this mixed-methods study is to investigate breastfeeding practices, barriers and facilitators among adolescent mothers ages 17 and younger. Methods Quantitative descriptive analyses are conducted using data from the North Carolina Pregnancy Risk Assessment Monitoring System (PRAMS)...

Samandari Ghazaleh; Wilson Ellen K; Tucker Christine M

2011-01-01

182

Finding a compromise between chemical and radiological risk assessment methods for mixed waste sites  

International Nuclear Information System (INIS)

The purpose of this paper is to (1) outline the fundamental similarities and differences between the presently accepted radiological and chemical risk assessment methods, (2) examine the significant differences in analytical results and decision making that can result if either is used to the exclusion of the other and (3) to suggest a hybrid method that utilizes the strong points of each to arrive at a balanced contaminant impact data base for decision making. The approach taken to facilitate these comparisons is to quantitatively assess the collective risk at a simplified site, contaminated with a short list of chemicals and radionuclides. The site is assessed first using exclusively the suggested Superfund toxic chemical methodology for both chemicals and radionuclides, followed by the same analysis using accepted radiological methods for both contaminant categories. Both the methods and the results of these calculations are compared and contrasted. Logical mitigation decisions that might result from each set of calculations are examined. The same site is finally analyzed using a method that incorporates the best of both of the previously used methods and the results are analyzed on the basis of the decision-making utility of the results. Conclusions are drawn relative to several topics or prime importance. These are: acceptable risk bases, key assumptions, statistical inputs, prioritizing contaminants, environmental models, cumulative risk, and risk assessments fo, cumulative risk, and risk assessments for non-human receptors

183

A Centroid Model for the Depth Assessment of Images using Rough Fuzzy Set Techniques  

OpenAIRE

Detection of affected areas in images is a crucial step in assessing the depth of the affected area for municipal operators. These affected areas in the underground images, which are line images are indicative of the condition of buried infrastructures like sewers and water mains. These images identify affected areas and extract their properties like structures from the images, whose contrast has been enhanced... A Centroid Model for the Depth Assessment of Images using Rough Fuzzy Set Techn...

Swarnalatha, P.; Tripathy, B. K.

2012-01-01

184

On the approximation of a polytope by its dual $L_{p}$-centroid bodies  

CERN Document Server

We show that the rate of convergence on the approximation of volumes of a convex symmetric polytope P in R^n by its dual L_{p$-centroid bodies is independent of the geometry of P. In particular we show that if P has volume 1, lim_{p\\rightarrow \\infty} \\frac{p}{\\log{p}} (\\frac{|Z_{p}^{\\circ}(P)|}{|P^{\\circ}|} -1) = n^{2}. We provide an application to the approximation of polytopes by uniformly convex sets.

Paouris, Grigoris

2011-01-01

185

A numerical method for finding sign-changing solutions of superlinear Dirichlet problems  

Energy Technology Data Exchange (ETDEWEB)

In a recent result it was shown via a variational argument that a class of superlinear elliptic boundary value problems has at least three nontrivial solutions, a pair of one sign and one which sign changes exactly once. These three and all other nontrivial solutions are saddle points of an action functional, and are characterized as local minima of that functional restricted to a codimension one submanifold of the Hilbert space H-0-1-2, or an appropriate higher codimension subset of that manifold. In this paper, we present a numerical Sobolev steepest descent algorithm for finding these three solutions.

Neuberger, J.M.

1996-12-31

186

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results  

OpenAIRE

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. We identify candidates in CFHT/MegaCam i' and z' images using optimised psf-fitting within Source Extractor, and follow them up with pointed near-infrared ...

Delorme, Philippe; Willott, Chris; Forveille, Thierry; Delfosse, Xavier; Reyle?, Ce?line; Bertin, Emmanuel; Albert, Loic; Artigau, Etienne; Robin, Annie; Allard, France; Doyon, Rene; Hill, Gary

2008-01-01

187

Inclusion of inversion symmetry in centroid molecular dynamics: A possible avenue to recover quantum coherence  

Science.gov (United States)

Inversion symmetry is included in the operator formulation of the centroid molecular dynamics (CMD). This work involves the development of a symmetry-adapted CMD (SA-CMD), here particularly for symmetrization and antisymmetrization projections. A symmetry-adapted quasidensity operator, as defined by Blinov and Roy [J. Chem. Phys. 115, 7822 (2001)], is employed to obtain the centroid representation of quantum mechanical operators. Numerical examples are given for a single particle confined to one-dimensional symmetric quartic and symmetric double-well potentials. Two SA-CMD simulations are performed separately for both projections, and centroid position autocorrelation functions are obtained. For each projection, the quality of the approximation as well as the accuracy are similar to those of regular CMD. It is shown that individual trajectories from two separate SA-CMD simulations can be properly combined to recover trajectories for Boltzmann statistics. Position autocorrelation functions are compared to the exact quantum mechanical ones. This explicit account of inversion symmetry provides a qualitative improvement on the conventional CMD approach and allows the recovery of some quantum coherence.

Huh, Yoonjung; Roy, Pierre-Nicholas

2006-10-01

188

DiffCoEx: a simple and sensitive method to find differentially coexpressed gene modules  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Large microarray datasets have enabled gene regulation to be studied through coexpression analysis. While numerous methods have been developed for identifying differentially expressed genes between two conditions, the field of differential coexpression analysis is still relatively new. More specifically, there is so far no sensitive and untargeted method to identify gene modules (also known as gene sets or clusters that are differentially coexpressed between two conditions. Here, sensitive and untargeted means that the method should be able to construct de novo modules by grouping genes based on shared, but subtle, differential correlation patterns. Results We present DiffCoEx, a novel method for identifying correlation pattern changes, which builds on the commonly used Weighted Gene Coexpression Network Analysis (WGCNA framework for coexpression analysis. We demonstrate its usefulness by identifying biologically relevant, differentially coexpressed modules in a rat cancer dataset. Conclusions DiffCoEx is a simple and sensitive method to identify gene coexpression differences between multiple conditions.

Breitling Rainer

2010-10-01

189

Nondestructive Testing Method for Finding out the Defects in a Composite Liner  

Directory of Open Access Journals (Sweden)

Full Text Available A composite liner of carbon phenolic has been inspected by ultrasonic, X-ray radiography andX-ray computed tomography (CT to find defects like delaminations, debonds, voids, foreign inclusions, etc.The geometry, detection of multiple defects and porosity of the liner make ultrasonic testing (pulse-echo anddrycoupling difficult for inspection. X-ray radiography being a non-contact technique finds multiple defectsbut compresses the structural information of 3-D volume into a 2-D image and interferes with overlyingand underlying areas of the object. X-ray CT generates an image of a thin and cross-sectional slice ofan object. R e linear attenuation coefficients in terms of Hounsfield values have been measured, comparedand correlated with CT images at the contrasts observed. 3-D images can be generated by stacking2-D cross-sectional images of the slices. These 3-D images can be cut at any angle of choice for mappingthe extent of delaminated/debonded areas. This type of information is difficult to obtain with conventionalnon-destructive testing techniques.

C. Muralidhar

2013-04-01

190

The Findings from the OECD/NEA/CSNI UMS (Uncertainty Method Study)  

International Nuclear Information System (INIS)

Within licensing procedures there is the incentive to replace the conservative requirements for code application by a 'best estimate' concept supplemented by an uncertainty analysis to account for predictive uncertainties of code results. Methods have been developed to quantify these uncertainties. The Uncertainty Methods Study (UMS) Group, following a mandate from CSNI (Committee on the Safety of Nuclear Installations) of OECD/NEA (Organization for Economic Cooperation and Development / Nuclear Energy Agency), has compared five methods for calculating the uncertainty in the predictions of advanced 'best estimate' thermal-hydraulic codes. Most of the methods identify and combine input uncertainties. The major differences between the predictions of the methods came from the choice of uncertain parameters and the quantification of the input uncertainties, i.e. the wideness of the uncertainty ranges. Therefore, suitable experimental and analytical information has to be selected to specify these uncertainty ranges or distributions. After the closure of the Uncertainty Method Study (UMS) and after the report was issued comparison calculations of experiment LSTF-SB-CL-18 were performed by University of Pisa using different versions of the RELAP 5 code. It turned out that the version used by two of the participants calculated a 170 K higher peak clad temperature compared with other versions using the same input deck. This may contribute to the differences of the upper limit of the uncertainty ranges. A 'bifurcation' analysis was also performed by the same research group also providing another way of interpreting the high temperature peak calculated by two of the participants. (authors)

191

Finding a needle in a haystack: toward a psychologically informed method for aviation security screening.  

Science.gov (United States)

Current aviation security systems identify behavioral indicators of deception to assess risks to flights, but they lack a strong psychological basis or empirical validation. We present a new method that tests the veracity of passenger accounts. In an in vivo double-blind randomized-control trial conducted in international airports, security agents detected 66% of deceptive passengers using the veracity test method compared with less than 5% using behavioral indicator recognition. As well as revealing advantages of veracity testing over behavioral indicator identification, the study provides the highest levels to date of deception detection in a realistic setting where the known base rate of deceptive individuals is low. PMID:25365531

Ormerod, Thomas C; Dando, Coral J

2015-02-01

192

The Dynamics of Poverty in the United States: A Review of Data, Methods, and Findings  

Science.gov (United States)

This paper reviews the literature on poverty dynamics in the U.S. It surveys the most prevalent data, theories, and methods used to answer three key questions: How likely are people to enter, exit, and reenter poverty? How long do people remain in poverty? And what events are associated with entering and exiting poverty? The paper then analyzes…

Cellini, Stephanie Riegg; McKernan, Signe-Mary; Ratcliffe, Caroline

2008-01-01

193

Centers and centroids of the cone-beam projection of a ball  

International Nuclear Information System (INIS)

In geometric calibration of cone-beam (CB) scanners, point-like marker objects such as small balls are imaged to obtain positioning information from which the unknown geometric parameters are extracted. The procedure is sensitive to errors in the positioning information, and one source of error is a small bias which can occur in estimating the detector locations of the CB projections of the centers of the balls. We call these detector locations the center projections. In general, the CB projection of a ball of uniform density onto a flat detector forms an ellipse. Inside the ellipse lie the center projection M, the ellipse center C and the centroid G of the intensity values inside the ellipse. The center projection is invariably estimated from C or G which are much easier to extract directly from the data. In this work, we quantify the errors incurred in using C or G to estimate M. We prove mathematically that the points C, G, M and O are always distinct and lie on the major axis of the ellipse, where O is the detector origin, defined as the orthogonal projection of the cone vertex onto the detector. (The ellipse can only degenerate to a circle if the ball is along the direct line of sight to O, and in this case all four points coincide.) The points always lie in the same order: O, M, G, C which establishes that the centroid has less geometric bias than the ellipse center for estimating M. However, our numerical studies indicate that the centroid bias is only 20% lesste that the centroid bias is only 20% less than the ellipse center bias so the benefit in using centroid estimates is not substantial. For the purposes of quantifying the bias in practice, we show that the ellipse center bias ||CM|| can be conveniently estimated by eA/(? f-tilde) where A is the area of the elliptical projection, e is the eccentricity of the ellipse and f-tilde is an estimate of the focal length of the system. Finally, we discuss how these results are affected by physical factors such as beam hardening, and indicate extensions to balls of non-uniform density.

194

Measurement of the LiD (A-X) transition moment from laser-excited fluorescence and test of the R-centroid approximation  

Science.gov (United States)

Improved Dunham coefficients of the X 1?+ and A 1?+ states of LiD were derived, based on the observation of vibrational levels up to v? = 26, corresponding to 96% of the ground state dissociation energy. From accurate intensity measurements over long fluorescence progressions, the electronic transition moment M was obtained as a function of the internuclear distance R. The dependence M(R) has an unusual S shape. The R-centroid method was found to be valid even in this case.

Ennen, G.; Fiedler, B.; Ottinger, Ch.

1981-07-01

195

Quantum Computational Method of Finding the Ground State Energy and Expectation Values  

CERN Document Server

We propose a new quantum computational way of obtaining a ground-state energy and expectation values of observables of interacting Hamiltonians. It is based on the combination of the adiabatic quantum evolution to project a ground state of a non-interacting Hamiltonian onto a ground state of an interacting Hamiltonian and the phase estimation algorithm to retrieve the ground-state energy. The expectation value of an observable for the ground state is obtained with the help of Hellmann-Feynman theorem. As an illustration of our method, we consider a displaced harmonic oscillator, a quartic anharmonic oscillator,and a potential scattering model. The results obtained by this method are in good agreement with the known results.

Oh, Sangchul

2007-01-01

196

Healthy Bread Initiative: Methods, Findings, and Theories—Isfahan Healthy Heart Program  

OpenAIRE

The scientific evidences show that the content, baking methods, and types of bread can make health impacts. Bread, as a major part of Iranian diet, demonstrates a significant potential to be targeted as health promotion subject. Healthy Food for Healthy Communities (HFHC) was a project of Isfahan Healthy Heart Program (IHHP), consisting of a wide variety of strategies, like Healthy Bread (HB) Initiative. The HB Initiative was designed to improve the behaviour of both producers and consumers, ...

Talaei, Mohammad; Mohammadifard, Noushin; Khaje, Mohammad-reza; Sarrafzadegan, Nizal; Sajjadi, Firoozeh; Alikhasi, Hasan; Maghroun, Maryam; Iraji, Farhad; Ehteshami, Shahram

2013-01-01

197

Paediatric cardiac CT examinations: impact of the iterative reconstruction method ASIR on image quality - preliminary findings  

Energy Technology Data Exchange (ETDEWEB)

Radiation dose exposure is of particular concern in children due to the possible harmful effects of ionizing radiation. The adaptive statistical iterative reconstruction (ASIR) method is a promising new technique that reduces image noise and produces better overall image quality compared with routine-dose contrast-enhanced methods. To assess the benefits of ASIR on the diagnostic image quality in paediatric cardiac CT examinations. Four paediatric radiologists based at two major hospitals evaluated ten low-dose paediatric cardiac examinations (80 kVp, CTDI{sub vol} 4.8-7.9 mGy, DLP 37.1-178.9 mGy.cm). The average age of the cohort studied was 2.6 years (range 1 day to 7 years). Acquisitions were performed on a 64-MDCT scanner. All images were reconstructed at various ASIR percentages (0-100%). For each examination, radiologists scored 19 anatomical structures using the relative visual grading analysis method. To estimate the potential for dose reduction, acquisitions were also performed on a Catphan phantom and a paediatric phantom. The best image quality for all clinical images was obtained with 20% and 40% ASIR (p < 0.001) whereas with ASIR above 50%, image quality significantly decreased (p < 0.001). With 100% ASIR, a strong noise-free appearance of the structures reduced image conspicuity. A potential for dose reduction of about 36% is predicted for a 2- to 3-year-old child when using 40% ASIR rather than the standard filtered back-projection method. Reconstruction including 20% to 40% ASIR slightly improved the conspicuity of various paediatric cardiac structures in newborns and children with respect to conventional reconstruction (filtered back-projection) alone. (orig.)

Mieville, Frederic A. [University Hospital Center and University of Lausanne, Institute of Radiation Physics, Lausanne (Switzerland); University Hospital Center and University of Lausanne, Institute of Radiation Physics - Medical Radiology, Lausanne (Switzerland); Gudinchet, Francois; Rizzo, Elena [University Hospital Center and University of Lausanne, Department of Radiology, Lausanne (Switzerland); Ou, Phalla; Brunelle, Francis [Necker Children' s Hospital, Department of Radiology, Paris (France); Bochud, Francois O.; Verdun, Francis R. [University Hospital Center and University of Lausanne, Institute of Radiation Physics, Lausanne (Switzerland)

2011-09-15

198

THE STATISTICAL METHOD FOR FINDING THE RESPONSE FOR N RANDOM EXCITATION OF THE INVERTED PENDULUM  

OpenAIRE

We present a method for estimating the power spectral density of the stationary response of oscillatorwith a nonlinear restoring force under external stochastic wide-band excitation. An equivalent linear system isderived, from which the power spectral density is deduced. We consider an inverted pendulum suspendedsubjected to white noise excitation with a random number n random excitations simultaneously applied. Themethod will be briefly discussed in the following sections

Stan, Marinica?; Stan, Petre

2013-01-01

199

THE STATISTICAL METHOD FOR FINDING THE RESPONSE FOR N RANDOM EXCITATION OF THE INVERTED PENDULUM  

Directory of Open Access Journals (Sweden)

Full Text Available We present a method for estimating the power spectral density of the stationary response of oscillatorwith a nonlinear restoring force under external stochastic wide-band excitation. An equivalent linear system isderived, from which the power spectral density is deduced. We consider an inverted pendulum suspendedsubjected to white noise excitation with a random number n random excitations simultaneously applied. Themethod will be briefly discussed in the following sections

Marinic? STAN

2013-05-01

200

An automated method for finding molecular complexes in large protein interaction networks  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Recent advances in proteomics technologies such as two-hybrid, phage display and mass spectrometry have enabled us to create a detailed map of biomolecular interaction networks. Initial mapping efforts have already produced a wealth of data. As the size of the interaction set increases, databases and computational methods will be required to store, visualize and analyze the information in order to effectively aid in knowledge discovery. Results This paper describes a novel graph theoretic clustering algorithm, "Molecular Complex Detection" (MCODE, that detects densely connected regions in large protein-protein interaction networks that may represent molecular complexes. The method is based on vertex weighting by local neighborhood density and outward traversal from a locally dense seed protein to isolate the dense regions according to given parameters. The algorithm has the advantage over other graph clustering methods of having a directed mode that allows fine-tuning of clusters of interest without considering the rest of the network and allows examination of cluster interconnectivity, which is relevant for protein networks. Protein interaction and complex information from the yeast Saccharomyces cerevisiae was used for evaluation. Conclusion Dense regions of protein interaction networks can be found, based solely on connectivity data, many of which correspond to known protein complexes. The algorithm is not affected by a known high rate of false positives in data from high-throughput interaction techniques. The program is available from ftp://ftp.mshri.on.ca/pub/BIND/Tools/MCODE.

Bader Gary D

2003-01-01

201

A method for finding the optimal predictor indices for local wave climate conditions  

Science.gov (United States)

In this study, a method to obtain local wave predictor indices that take into account the wave generation process is described and applied to several locations. The method is based on a statistical model that relates significant wave height with an atmospheric predictor, defined by sea level pressure fields. The predictor is composed of a local and a regional part, representing the sea and the swell wave components, respectively. The spatial domain of the predictor is determined using the Evaluation of Source and Travel-time of wave Energy reaching a Local Area (ESTELA) method. The regional component of the predictor includes the recent historical atmospheric conditions responsible for the swell wave component at the target point. The regional predictor component has a historical temporal coverage ( n-days) different to the local predictor component (daily coverage). Principal component analysis is applied to the daily predictor in order to detect the dominant variability patterns and their temporal coefficients. Multivariate regression model, fitted at daily scale for different n-days of the regional predictor, determines the optimum historical coverage. The monthly wave predictor indices are selected applying a regression model using the monthly values of the principal components of the daily predictor, with the optimum temporal coverage for the regional predictor. The daily predictor can be used in wave climate projections, while the monthly predictor can help to understand wave climate variability or long-term coastal morphodynamic anomalies.

Camus, Paula; Méndez, Fernando J.; Losada, Inigo J.; Menéndez, Melisa; Espejo, Antonio; Pérez, Jorge; Rueda, Ana; Guanche, Yanira

2014-07-01

202

Establishing the soft and hard tissue area centers (centroids) for the skull and introducing a newnon-anatomical cephalometric line  

International Nuclear Information System (INIS)

The purpose of this study was to demonstrate how to establish the area center (centroid) of both the soft and hard tissues of the outline of the lateral cephalometric skull image, and to introduce the concept of a new non-anatomical centroid line. Lateral cephalometric radiographs, size 12 x 14 inch, of fifty seven adult subjects were selected based on their pleasant, balanced profile, Class I skeletal and dental relationship and no major dental malocclusion or malrelationship. The area centers (centroids) of both soft and hard tissue skull were practically established using a customized software computer program called the m-file. Connecting the two centers introduced the concept of a new non-anatomical soft and hard centroids line. (author)

203

The use of multicriteria decision making methods to find the environmental costs of hydropower development alternatives  

International Nuclear Information System (INIS)

The conference paper deals with a decision support system (DSS) developed to find the costs of environmental goods. The system is based on multicriteria decision making and uses pairwise comparisons of two and two criteria. The criteria weights are calculated with linear regression. When one criterion is monetary, all criteria weights can be expressed in monetary units when the weights are known. The DSS has been tested on a hydropower project in the area of Sauda in Norway. To represent the decision makers, three panels each consisting of three persons were formed. The persons were selected from governmental agencies, the developers, the local environmental administration and a local politician. The DSS worked well with the panels. One problem was that impacts of hydropower projects are very site specific and also hard to quantify. Therefore, a considerable amount of time was used in creating a cognitive understanding of the issues involved and how they were represented by quantitative criteria. Some had also difficulties in accepting the principle of expressing environmental goods in monetary units. The results so far are preliminary. This research work is part of the Norwegian research programme Energy, Environment and Development. 3 refs., 4 figs., 2 tabs

204

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results  

CERN Document Server

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. We identify candidates in CFHT/MegaCam i' and z' images using optimised psf-fitting within Source Extractor, and follow them up with pointed near-infrared imaging on several telescopes. We have so far analysed over 350 square degrees and found 770 brown dwarf candidates brighter than z'{AB}=22.5. We currently have J-band photometry for 220 of these candidates, which confirms 37% as potential L or T dwarfs. Some are among the reddest and farthest brown dwarfs currently known, including an independent identification of the recently published ULAS J003402.77-005206.7 and the discovery of a second brown dwarf later than T8, CFBDS J005910.83-011401.3. Infrared spectra of three T dwarf candidates ...

Delorme, Philippe; Forveille, Thierry; Delfosse, Xavier; Reylé, Céline; Bertin, Emmanuel; Albert, Loic; Artigau, Etienne; Robin, Annie C; Allard, France; Doyon, Rene; Hill, Gary J

2008-01-01

205

Continuing medical education in Maritime Canada: the methods physicians use, would prefer and find most effective.  

OpenAIRE

A study of the continuing medical education of practising physicians in Nova Scotia, New Brunswick and Prince Edward Island was conducted in 1979-80 by means of a mailed questionnaire. Most of the responding physicians ranked reading as the method most used to update knowledge (73.3%) and skills (55.7%); courses and informal instruction were in second place for updating knowledge and skills respectively, ranked most used by 9.3% and 17.1%. With unlimited time and funds 38.0% and 20.5% of the ...

Curry, L.; Putnam, R. W.

1981-01-01

206

Comparative personality judgments: replication and extension of robust findings in personality perception using an alternative method.  

Science.gov (United States)

The scientific study of accuracy in personality judgment typically involves the utilization of rating scales to make absolute decisions about a target individual. Although this method has many merits, it restricts some experimental options and is further removed from ecological validity than one would desire. These studies represent an attempt to develop an alternative methodology for the study of personality judgment--specifically for use in explorations of judgment process. A series of photo sets containing pictures of 3 individuals, each representing a different level of a specific personality trait, was created. The participant's task was to select high and low scorers on a dimension from the photos. Study 1 demonstrates that people can select targets with extreme scores from a photo lineup at a rate better than chance across several personality dimensions. Study 2 shows that this ability has some degree of temporal consistency. Study 3 represents an improvement on the general method via enhanced criteria for stimulus selection, incorporating both self and peer reports. PMID:24397492

Beer, Andrew

2014-01-01

207

Application of geo-microbial prospecting method for finding oil and gas reservoirs  

Science.gov (United States)

Microbial prospecting of hydrocarbons is based on the detection of anomalous population of hydrocarbon oxidizing bacteria in the surface soils, indicates the presence of subsurface oil and gas accumulation. The technique is based on the seepage of light hydrocarbon gases such as C1-C4 from the oil and gas pools to the shallow surface that provide the suitable conditions for the development of highly specialized bacterial population. These bacteria utilize hydrocarbon gases as their only food source and are found enriched in the near surface soils above the hydrocarbon bearing structures. The methodology involves the collection of soil samples from the survey area, packing, preservation and storage of samples in pre-sterilized sample bags under aseptic and cold conditions till analysis and isolation and enumeration of hydrocarbon utilizing bacteria such as methane, ethane, propane, and butane oxidizers. The contour maps for the population density of hydrocarbon oxidizing bacteria are drawn and the data can be integrated with geological, geochemical, geophysical methods to evaluate the hydrocarbon prospect of an area and to prioritize the drilling locations thereby reducing the drilling risks and achieve higher success in petroleum exploration. Microbial Prospecting for Oil and Gas (MPOG) method success rate has been reported to be 90%. The paper presents details of microbial prospecting for oil and gas studies, excellent methodology, future development trends, scope, results of study area, case studies and advantages.

Rasheed, M. A.; Hasan, Syed Zaheer; Rao, P. L. Srinivasa; Boruah, Annapurna; Sudarshan, V.; Kumar, B.; Harinarayana, T.

2015-03-01

208

A comparative method for finding and folding RNA secondary structures within protein-coding regions  

DEFF Research Database (Denmark)

Existing computational methods for RNA secondary-structure prediction tacitly assume RNA to only encode functional RNA structures. However, experimental studies have revealed that some RNA sequences, e.g. compact viral genomes, can simultaneously encode functional RNA structures as well as proteins, and evidence is accumulating that this phenomenon may also be found in Eukaryotes. We here present the first comparative method, called RNA-DECODER, which explicitly takes the known protein-coding context of an RNA-sequence alignment into account in order to predict evolutionarily conserved secondary-structure elements, which may span both coding and non-coding regions. RNA-DECODER employs a stochastic context-free grammar together with a set of carefully devised phylogenetic substitution-models, which can disentangle and evaluate the different kinds of overlapping evolutionary constraints which arise. We show that RNA-DECODER's parameters can be automatically trained to successfully fold known secondary structures within the HCV genome. We scan the genomes of HCV and polio virus for conserved secondary-structure elements, and analyze performance as a function of available evolutionary information. On known secondary structures, RNA-DECODER shows a sensitivity similar to the programs MFOLD, PFOLD and RNAALIFOLD. When scanning the entire genomes of HCV and polio virus for structure elements, RNA-DECODER's results indicate a markedly higher specificity than MFOLD, PFOLD and RNAALIFOLD.

Pedersen, Jakob Skou; Meyer, Irmtraud Margret

2004-01-01

209

A Vision based Geometrical Method to find Fingers Positions in Real Time Hand Gesture Recognition  

Directory of Open Access Journals (Sweden)

Full Text Available A novel method to calculate the bended finger’s angle has presented here which could be used to control the electro-mechanical robotic hand. It is assumed that the robotic hand has the human hand like joints and same number of degree of freedom as human hand. In many applications an equipment like human hand is needed, to do the same kind of operation like human do. These days it is easy to make the electro-mechanical robotic hand which has five fingers and same joint but it is not easily controllable as the human hand for accurate work. In our method the hand gesture will be interpreted for controlling the robotic hand. The angles for all the fingers will be calculated and that could be further passed to the robotic hand for controlling its finger. User would perform gesture according to the action as he wants to be done by robotic hand. Here finger positions are detected using geometric modeling of hand in the extracted image Region of interest cropping from the image made the algorithm faster.

Ankit Chaudhary

2012-04-01

210

Combined Calibration Method and its Realization for Direction Finding Antenna Systems with Patch Antennas  

Directory of Open Access Journals (Sweden)

Full Text Available A novel radio channel compensation method aiming to give optimal calibration for microstrip antenna array systems is presented in this paper, realized for an actual DOA measurement antenna system using microstrip antennas to sample the electromagnetic field, operating at 4.5GHz. This new approach considers mismatch between antennas and channel RF ports, channel transmission inequalities, and also decreases the effects of multipath propagation components of calibration reference signals by placing the calibration reference signal feeding network on the microstrip antenna array bearer, directly beside the antenna patches. It is combined with orthogonal spread spectrum calibration signal utility for continuous uninterrupted measurements. The spread spectrum calibration signal is orthogonal to the continuous wave (CW signal to be measured, therefore, the 2 signals can be separated in the receiver, enabling them to be present simultaneously. DOA measurement results are shown, measured with the realized integrated microstrip patch antenna array with calibration network hardware.

R. Seller

2007-09-01

211

A MODIFIED ALGORITHM FOR THRESHOLDING AND DETECTION OF FACIAL INFORMATION FROM COLOR IMAGES USING COLOR CENTROID SEGMENTATION AND CONTOURLET TRANSFORM  

Directory of Open Access Journals (Sweden)

Full Text Available Human face detection plays an important role in many application areas such as video surveillance, human computer interface, face recognition, face search and face image database management etc. In human face detection applications, face region usually form an inconsequential part of images. Preliminary segmentation of images into regions that contain "non-face" objects and regions that may contain "face" can greatly accelerate the process of human face detection. This can be done using skin color segmentation, where given image is segmented based on color as 'skin region' and 'non skin regions'. Thus we can say that the skin regions may contain face and other regions don't. Color information based methods take a great attention, because colors have obviously character and robust visual cue for detection. This paper proposes a method based on RGB color centroids segmentation (CCS for face detection. This paper includes two parts, first part is color image thresholding based on CCS to perform skin color segmentation and the then detection of human face from detected skin regions. CCS method has some shortcomings as it fails when the skin color of the subject lacks chroma. This happens especially with subjects having too darker or too lighter skin tones. This shortcoming of CCS can be overcome using Contourlet Transformation. In this paper, we pursue a two dimensional transform that can capture the intrinsic geometrical structure that is key in visual information.

Sunish Kumar O S

2011-06-01

212

Finding an optimal method for imaging lymphatic vessels of the upper limb  

International Nuclear Information System (INIS)

Lymphoscintigraphy involves interstitial injection of radiolabelled particulate materials or radioproteins. Although several variations in the technique have been described, their place in clinical practice remains controversial. Traditional diagnostic criteria are based primarily on lymph node appearances but in situations such as breast cancer, where lymph nodes may have been excised, these criteria are of limited use. In these circumstances, lymphatic vessel morphology takes on greater importance as a clinical endpoint, so a method that gives good definition of lymphatic vessels would be useful. In patients with breast cancer, for example, such a method, used before and after lymph node resection, may assist in predicting the development of breast cancer-related lymphoedema. The aim of this study was to optimise a method for the visualisation of lymphatic vessels. Subcutaneous (sc) and intradermal (id) injection sites were compared, and technetium-99m nanocolloid, a particulate material, was compared with 99mTc-human immunoglobulin (HIG), which is a soluble macromolecule. Twelve normal volunteers were each studied on two occasions. In three subjects, id 99mTc-HIG was compared with sc 99mTc-HIG, in three id 99mTc-nanocolloid was compared with sc 99mTc-nanocolloid, in three id 99mTc-HIG was compared with id 99mTc-nanocolloid and in three sc 99mTc-HIG was compared with sc 99mTc-HIG was compared with sc 99mTc-nanocolloid. Endpoints were quality of lymphatic vessel definition, the time after injection at which vessels were most clearly visualised, the rate constant of depot disappearance (k) and the systemic blood accumulation rate as measured by gamma camera imaging over the liver or cardiac blood pool. Excellent definition of lymphatic vessels was obtained following id injection of either radiopharmaceutical, an injection route that was clearly superior to sc. Differences between radiopharmaceuticals were less clear, although after id injection, 99mTc-HIG gave images that were marginally but significantly better than those given by 99mTc-nanocolloid. Image quality correlated inversely with time after injection at which the best image was obtained, consistent with the notion that good vessel definition was dependent on a ''narrow'' bolus width. k was approximately three times higher after id injection than after sc injection but it was not significantly different between radiopharmaceuticals for either injection route. Intradermal 99mTc-HIG gave a cardiac blood pool signal that, over the first 60 min, increased about five times faster than that with sc 99mTc-HIG, but no clear difference was observed in the rate of increase in hepatic activity between id 99mTc-nanocolloid and sc 99mTc-nanocolloid. We conclude that id injection provides rapid access of radiotracers to lymphatic vessels, which is ideal for imaging lymphatic vessel morphology. 99mTc-HIG is marginally superior to nanocolloid for this purpose and, in drainage basins from which lymph nodes have been excised, is not handicapped by a potentially inferior ability, compared with radiocolloid, to image lymph nodes. (orig.)

213

Iterative methods for finding optimal quantum measurements under minimum-error and minimax criteria  

Science.gov (United States)

We investigate the problem of computing optimal quantum measurements in both minimal measuring and minimax strategies. A Belavkin weighted square-root measurement (BWSRM) with appropriate weights can represent the measurement that maximizes the correct probability for any given prior probabilities of quantum states. Using this fact, we propose methods for computing optimal solutions by optimizing the weights of the BWSRM. First, we explain the conditions for the BWSRM to be optimal. In particular, we argue that if a BWSRM with certain weights is a minimax measurement, then the minimax probabilities can be immediately obtained. Next, we propose an extension of the iterative algorithm developed by Ježek et al. [Phys. Rev. A 65, 060301 (2002), 10.1103/PhysRevA.65.060301] for maximizing the correct probability. We prove that, for a linearly independent pure state set, Ježek et al.'s algorithm converges to an optimal measurement. We also propose an iterative algorithm for a minimax solution and prove that, for a pure state set, our algorithm monotonically decreases the difference between estimated and true minimax values. Finally the performance of our algorithms is evaluated through numerical experiments.

Nakahira, Kenji; Kato, Kentaro; Usuda, Tsuyoshi Sasaki

2015-01-01

214

A COMPARATIVE STUDY TO FIND A SUITABLE METHOD FOR TEXT DOCUMENT CLUSTERING  

Directory of Open Access Journals (Sweden)

Full Text Available Text mining is used in various text related tasks such as information extraction, concept/entity extraction,document summarization, entity relation modeling (i.e., learning relations between named entities,categorization/classification and clustering. This paper focuses on document clustering, a field of textmining, which groups a set of documents into a list of meaningful categories. The main focus of thispaper is to present a performance analysis of various techniques available for document clustering. Theresults of this comparative study can be used to improve existing text data mining frameworks andimprove the way of knowledge discovery. This paper considers six clustering techniques for documentclustering. The techniques are grouped into three groups namely Group 1 - K-means and its variants(traditional K-means and K* Means algorithms, Group 2 - Expectation Maximization and its variants(traditional EM, Spherical Gaussian EM algorithm and Linear Partitioning and Reallocation clustering(LPR using EM algorithms, Group 3 - Semantic-based techniques (Hybrid method and Feature-basedalgorithms. A total of seven algorithms are considered and were selected based on their popularity inthe text mining field. Several experiments were conducted to analyze the performance of the algorithmand to select the winner in terms of cluster purity, clustering accuracy and speed of clustering.

Dr.M.Punithavalli

2012-01-01

215

Imaging texture and porosity in mudstone and shale : findings from petrographic, secondary, and ion-milled backscatter SEM methods  

Energy Technology Data Exchange (ETDEWEB)

Sea-level cycles are important for shale gas, impacting gas generation, storage and fracture development. The objectives of petrographic studies are to answer questions of sedimentology and geology and to provide a context for interpretations of indirect measurements. This presentation discussed imaging texture and porosity in mudstone and shales. Findings from petrographic, secondary, and ion-milled backscatter scanning electron microscopy (SEM) methods were presented. Important qualitative findings that impacted porosity measurements were offered, including observed pore types; pore size range; and rock matrix, texture and diagenesis. Questions to consider in a post-Darcy universe were identified. Areas of investigation, secondary and argon-ion milled backscatter SEM methods were explored. The presentation noted that secondary electron imaging of the larger area validated that the argon-ion milled area was representative. It was concluded that the relative abundance of pore types and their sizes should be verified by observations and that variations are expected. refs., figs.

Milner, M.; Petriello, J.; McLin, R.; Gathogo, P. [TerraTek Energy Solutions, Courtenay, BC (Canada)

2010-07-01

216

Method for Finding Metabolic Properties Based on the General Growth Law. Liver Examples. A General Framework for Biological Modeling  

OpenAIRE

We propose a method for finding metabolic parameters of cells, organs and whole organisms, which is based on the earlier discovered general growth law. Based on the obtained results and analysis of available biological models, we propose a general framework for modeling biological phenomena and discuss how it can be used in Virtual Liver Network project. The foundational idea of the study is that growth of cells, organs, systems and whole organisms, besides biomolecular machinery, is influenc...

Shestopaloff, Yuri K.

2014-01-01

217

The Pade approximant method for finding the Hilbert-Schmidt eigenvalues and eigenfunctions in two- and three-body problems  

International Nuclear Information System (INIS)

An approach is proposed which makes it possible to obtain the Hilbert-Schmidt (or Sturm-Liouville) eigenvalue and eigenfunctions for two-or three-body systems over the entire domain of analyticity of these functions in energy on the basis of calculations of bound states only. It is shown how this method may be used to find the two- and three-body resonances and the near-threshold states. (orig.)

218

An efficient method to find potentially universal population genetic markers, applied to metazoans  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Despite the impressive growth of sequence databases, the limited availability of nuclear markers that are sufficiently polymorphic for population genetics and phylogeography and applicable across various phyla restricts many potential studies, particularly in non-model organisms. Numerous introns have invariant positions among kingdoms, providing a potential source for such markers. Unfortunately, most of the few known EPIC (Exon Primed Intron Crossing loci are restricted to vertebrates or belong to multigenic families. Results In order to develop markers with broad applicability, we designed a bioinformatic approach aimed at avoiding multigenic families while identifying intron positions conserved across metazoan phyla. We developed a program facilitating the identification of EPIC loci which allowed slight variation in intron position. From the Homolens databases we selected 29 gene families which contained 52 promising introns for which we designed 93 primer pairs. PCR tests were performed on several ascidians, echinoderms, bivalves and cnidarians. On average, 24 different introns per genus were amplified in bilaterians. Remarkably, five of the introns successfully amplified in all of the metazoan genera tested (a dozen genera, including cnidarians. The influence of several factors on amplification success was investigated. Success rate was not related to the phylogenetic relatedness of a taxon to the groups that most influenced primer design, showing that these EPIC markers are extremely conserved in animals. Conclusions Our new method now makes it possible to (i rapidly isolate a set of EPIC markers for any phylum, even outside the animal kingdom, and thus, (ii compare genetic diversity at potentially homologous polymorphic loci between divergent taxa.

Chenuil Anne

2010-09-01

219

The Shortlist Method for fast computation of the Earth Mover's Distance and finding optimal solutions to transportation problems.  

Science.gov (United States)

Finding solutions to the classical transportation problem is of great importance, since this optimization problem arises in many engineering and computer science applications. Especially the Earth Mover's Distance is used in a plethora of applications ranging from content-based image retrieval, shape matching, fingerprint recognition, object tracking and phishing web page detection to computing color differences in linguistics and biology. Our starting point is the well-known revised simplex algorithm, which iteratively improves a feasible solution to optimality. The Shortlist Method that we propose substantially reduces the number of candidates inspected for improving the solution, while at the same time balancing the number of pivots required. Tests on simulated benchmarks demonstrate a considerable reduction in computation time for the new method as compared to the usual revised simplex algorithm implemented with state-of-the-art initialization and pivot strategies. As a consequence, the Shortlist Method facilitates the computation of large scale transportation problems in viable time. In addition we describe a novel method for finding an initial feasible solution which we coin Modified Russell's Method. PMID:25310106

Gottschlich, Carsten; Schuhmacher, Dominic

2014-01-01

220

Healthy bread initiative: methods, findings, and theories--Isfahan Healthy Heart Program.  

Science.gov (United States)

The scientific evidences show that the content, baking methods, and types of bread can make health impacts. Bread, as a major part of Iranian diet, demonstrates a significant potential to be targeted as health promotion subject. Healthy Food for Healthy Communities (HFHC) was a project of Isfahan Healthy Heart Program (IHHP), consisting of a wide variety of strategies, like Healthy Bread (HB) Initiative. The HB Initiative was designed to improve the behaviour of both producers and consumers, mainly aiming at making high-fibre, low-salt bread, eliminating the use of baking soda, providing enough rest time for dough before baking (at least one hour), and enough baking time (at least one minute in oven). A workshop was held for volunteer bakers, and a baker-to-baker training protocol under direct supervision was designed for future volunteers. Cereal Organization was persuaded to provide less refined flour that contained more bran. Health messages in support of new breads were disseminated by media and at bakeries by health professionals. Evaluation of the HB Initiative was done using before-after assessments and population surveys. While HB was baked in 1 (0.01%) bakery at baseline, 402 (41%) bakeries in the intervention area joined the HB Initiative in 2009. Soda was completely eliminated and fibre significantly increased from 4 +/- 0.4 g% before study to 12 +/- 0.6 g% after the intervention (p < 0.001). The preparation and baking times remarkably increased. Wastage of bread decreased from 13 +/- 1.8 g% to 2 +/- 0.5 g% and was expressed as the most important advantage of this initiative by consumers. People who lived in Isfahan city consumed whole bread 6 times more than those who lived in reference area Arak (p < 0.001). The HB Initiative managed to add new breads as a healthy choice that were compatible with local dishes and made a model to solve the longstanding problems of bread. It used various health promotion approaches but was best consistent with Beattie's model. PMID:23617204

Talaei, Mohammad; Mohammadifard, Noushin; Khaje, Mohammad-Reza; Sarrafzadegan, Nizal; Sajjadi, Firoozeh; Alikhasi, Hasan; Maghroun, Maryam; Iraji, Farhad; Ehteshami, Shahram

2013-03-01

221

Healthy Bread Initiative: Methods, Findings, and Theories—Isfahan Healthy Heart Program  

Science.gov (United States)

The scientific evidences show that the content, baking methods, and types of bread can make health impacts. Bread, as a major part of Iranian diet, demonstrates a significant potential to be targeted as health promotion subject. Healthy Food for Healthy Communities (HFHC) was a project of Isfahan Healthy Heart Program (IHHP), consisting of a wide variety of strategies, like Healthy Bread (HB) Initiative. The HB Initiative was designed to improve the behaviour of both producers and consumers, mainly aiming at making high-fibre, low-salt bread, eliminating the use of baking soda, providing enough rest time for dough before baking (at least one hour), and enough baking time (at least one minute in oven). A workshop was held for volunteer bakers, and a baker-to-baker training protocol under direct supervision was designed for future volunteers. Cereal Organization was persuaded to provide less refined flour that contained more bran. Health messages in support of new breads were disseminated by media and at bakeries by health professionals. Evaluation of the HB Initiative was done using before-after assessments and population surveys. While HB was baked in 1 (0.01%) bakery at baseline, 402 (41%) bakeries in the intervention area joined the HB Initiative in 2009. Soda was completely eliminated and fibre significantly increased from 4±0.4 g% before study to 12±0.6 g% after the intervention (p<0.001). The preparation and baking times remarkably increased. Wastage of bread decreased from 13±1.8 g% to 2±0.5 g% and was expressed as the most important advantage of this initiative by consumers. People who lived in Isfahan city consumed whole bread 6 times more than those who lived in reference area Arak (p<0.001). The HB Initiative managed to add new breads as a healthy choice that were compatible with local dishes and made a model to solve the long-standing problems of bread. It used various health promotion approaches but was best consistent with Beattie's model. PMID:23617204

Talaei, Mohammad; Khaje, Mohammad-Reza; Sarrafzadegan, Nizal; Sajjadi, Firoozeh; Alikhasi, Hasan; Maghroun, Maryam; Iraji, Farhad; Ehteshami, Shahram

2013-01-01

222

Centers and centroids of the cone-beam projection of a ball.  

Science.gov (United States)

In geometric calibration of cone-beam (CB) scanners, point-like marker objects such as small balls are imaged to obtain positioning information from which the unknown geometric parameters are extracted. The procedure is sensitive to errors in the positioning information, and one source of error is a small bias which can occur in estimating the detector locations of the CB projections of the centers of the balls. We call these detector locations the center projections. In general, the CB projection of a ball of uniform density onto a flat detector forms an ellipse. Inside the ellipse lie the center projection M, the ellipse center C and the centroid G of the intensity values inside the ellipse. The center projection is invariably estimated from C or G which are much easier to extract directly from the data. In this work, we quantify the errors incurred in using C or G to estimate M. We prove mathematically that the points C, G, M and O are always distinct and lie on the major axis of the ellipse, where O is the detector origin, defined as the orthogonal projection of the cone vertex onto the detector. (The ellipse can only degenerate to a circle if the ball is along the direct line of sight to O, and in this case all four points coincide.) The points always lie in the same order: O, M, G, C which establishes that the centroid has less geometric bias than the ellipse center for estimating M. However, our numerical studies indicate that the centroid bias is only 20% less than the ellipse center bias so the benefit in using centroid estimates is not substantial. For the purposes of quantifying the bias in practice, we show that the ellipse center bias ||CM|| can be conveniently estimated by eA/(? ƒ(?) where A is the area of the elliptical projection, e is the eccentricity of the ellipse and ƒ(?) is an estimate of the focal length of the system. Finally, we discuss how these results are affected by physical factors such as beam hardening, and indicate extensions to balls of non-uniform density. PMID:22048649

Clackdoyle, R; Mennessier, C

2011-12-01

223

Centers and centroids of the cone-beam projection of a ball  

Science.gov (United States)

In geometric calibration of cone-beam (CB) scanners, point-like marker objects such as small balls are imaged to obtain positioning information from which the unknown geometric parameters are extracted. The procedure is sensitive to errors in the positioning information, and one source of error is a small bias which can occur in estimating the detector locations of the CB projections of the centers of the balls. We call these detector locations the center projections. In general, the CB projection of a ball of uniform density onto a flat detector forms an ellipse. Inside the ellipse lie the center projection M, the ellipse center C and the centroid G of the intensity values inside the ellipse. The center projection is invariably estimated from C or G which are much easier to extract directly from the data. In this work, we quantify the errors incurred in using C or G to estimate M. We prove mathematically that the points C, G, M and O are always distinct and lie on the major axis of the ellipse, where O is the detector origin, defined as the orthogonal projection of the cone vertex onto the detector. (The ellipse can only degenerate to a circle if the ball is along the direct line of sight to O, and in this case all four points coincide.) The points always lie in the same order: O, M, G, C which establishes that the centroid has less geometric bias than the ellipse center for estimating M. However, our numerical studies indicate that the centroid bias is only 20% less than the ellipse center bias so the benefit in using centroid estimates is not substantial. For the purposes of quantifying the bias in practice, we show that the ellipse center bias ||CM|| can be conveniently estimated by eA/(\\pi \\skew4\\tilde{f}) where A is the area of the elliptical projection, e is the eccentricity of the ellipse and \\skew4\\tilde{f} is an estimate of the focal length of the system. Finally, we discuss how these results are affected by physical factors such as beam hardening, and indicate extensions to balls of non-uniform density.

Clackdoyle, R.; Mennessier, C.

2011-12-01

224

Relative entropy of cone measures and $L_p$ centroid bodies  

CERN Document Server

Let $K$ be a convex body in $\\mathbb R^n$. We introduce a new affine invariant, which we call $\\Omega_K$, that can be found in three different ways: as a limit of normalized $L_p$-affine surface areas, as the relative entropy of the cone measure of $K$ and the cone measure of $K^\\circ$, as the limit of the volume difference of $K$ and $L_p$-centroid bodies. We investigate properties of $\\Omega_K$ and of related new invariant quantities. In particular, we show new affine isoperimetric inequalities and we show a "information inequality" for convex bodies.

Paouris, Grigoris

2009-01-01

225

Relative entropy of cone measures and $L_p$ centroid bodies  

OpenAIRE

Let $K$ be a convex body in $\\mathbb R^n$. We introduce a new affine invariant, which we call $\\Omega_K$, that can be found in three different ways: as a limit of normalized $L_p$-affine surface areas, as the relative entropy of the cone measure of $K$ and the cone measure of $K^\\circ$, as the limit of the volume difference of $K$ and $L_p$-centroid bodies. We investigate properties of $\\Omega_K$ and of related new invariant quantities. In particular, we show new affine isop...

Paouris, Grigoris; Werner, Elisabeth M.

2009-01-01

226

Microlensed image centroid motions by an exotic lens object with negative convergence or negative mass  

CERN Document Server

Gravitational lens models with negative convergence (surface mass density projected onto the lens plane) inspired by modified gravity theories, exotic matter and energy have been recently examined to discuss possible demagnification of images and gravitational lensing shear, in such a way that a static and spherically symmetric modified spacetime metric depends on the inverse distance to the power of positive $n$ ($n=1$ for Schwarzschild metric, $n=2$ for Ellis wormhole) in the weak-field approximation [Kitamura, Nakajima and Asada, PRD 87, 027501 (2013), Izumi et al. to be published in PRD (2013)]. Some of the exotic lens models cause the attractive force on light rays like a convex lens, whereas the others are repulsive on light rays like a concave lens. The present paper considers microlensed image centroid motions by the exotic lens models. Numerical calculations show that, for large $n$ cases in the convex-type models, the centroid shift from the source position might move on a multiply-connected curve l...

Kitamura, Takao; Nakajima, Koki; Hagiwara, Chisaki; Asada, Hideki

2013-01-01

227

A Viscosity Approximation Method for Finding Common Solutions of Variational Inclusions, Equilibrium Problems, and Fixed Point Problems in Hilbert Spaces  

Directory of Open Access Journals (Sweden)

Full Text Available We introduce an iterative method for finding a common element of the set of common fixed points of a countable family of nonexpansive mappings, the set of solutions of a variational inclusion with set-valued maximal monotone mapping, and inverse strongly monotone mappings and the set of solutions of an equilibrium problem in Hilbert spaces. Under suitable conditions, some strong convergence theorems for approximating this common elements are proved. The results presented in the paper improve and extend the main results of J. W. Peng et al. (2008 and many others.

Plubtieng Somyot

2009-01-01

228

Pipeline structure for real-time centroid calculation of Hartmann wavefront sensor with horizontal multi-channel pixel output  

Science.gov (United States)

In this paper, a real-time pipeline centroid calculating structure based on programmable logic devices is designed for Hartmann wavefront sensor with horizontal multi-channel pixel output. The pipeline consists of modularized cells including multiplier groups, accumulation cells, dividers and corresponding control units. The structure is specially designed to deal with simultaneously output pixels which belong to two adjacent subapertures as well as those pixels belong to the same subaperture. When the number of output channels is 8 and pixels output at 80MHz clock frequency, centroid calculation latency in simulation is less than 0.5?s.

Wang, Shaobai; Wang, Chunhong; Rao, Changhui

2011-08-01

229

Acquisition and Initial Analysis of H+- and H--Beam Centroid Jitter at LANSCE  

International Nuclear Information System (INIS)

During the 2005 Los Alamos Neutron Science Center (LANSCE) beam runs, beam current and centroid-jitter data were observed, acquired, analyzed, and documented for both the LANSCE H+ and H- beams. These data were acquired using three beam position monitors (BPMs) from the 100-MeV Isotope Production Facility (IPF) beam line and three BPMs from the Switchyard transport line at the end of the LANSCE 800-MeV linac. The two types of data acquired, intermacropulse and intramacropulse, were analyzed for statistical and frequency characteristics as well as various other correlations including comparing their phase-space like characteristics in a coordinate system of transverse angle versus transverse position. This paper will briefly describe the measurements required to acquire these data, the initial analysis of these jitter data, and some interesting dilemmas these data presented

230

Path integral centroid molecular dynamics simulations of semiinfinite slab and bulk liquid of para-hydrogen  

Energy Technology Data Exchange (ETDEWEB)

It has been unsuccessful to solve a set of time-dependent Schroedinger equations numerically for many-body quantum systems which involve, e.g., a number of hydrogen molecules, protons, and excess electrons at a low temperature, where quantum effect evidently appears. This undesirable situation is fatal for the investigation of real low-temperature chemical systems because they are essentially composed of many quantum degrees of freedom. However, if we use a new technique called `path integral centroid molecular dynamics (CMD) simulation` proposed by Cao and Voth in 1994, the real-time semi-classical dynamics of many degrees of freedom can be computed by utilizing the techniques already developed in the traditional classical molecular dynamics (MD) simulations. Therefore, the CMD simulation is expected to be very powerful tool for the quantum dynamics studies or real substances. (J.P.N.)

Kinugawa, Kenichi [Nara Women`s Univ., Nara (Japan). Dept. of Chemistry

1998-10-01

231

Path integral centroid molecular dynamics simulations of semiinfinite slab and bulk liquid of para-hydrogen  

International Nuclear Information System (INIS)

It has been unsuccessful to solve a set of time-dependent Schroedinger equations numerically for many-body quantum systems which involve, e.g., a number of hydrogen molecules, protons, and excess electrons at a low temperature, where quantum effect evidently appears. This undesirable situation is fatal for the investigation of real low-temperature chemical systems because they are essentially composed of many quantum degrees of freedom. However, if we use a new technique called 'path integral centroid molecular dynamics (CMD) simulation' proposed by Cao and Voth in 1994, the real-time semi-classical dynamics of many degrees of freedom can be computed by utilizing the techniques already developed in the traditional classical molecular dynamics (MD) simulations. Therefore, the CMD simulation is expected to be very powerful tool for the quantum dynamics studies or real substances. (J.P.N.)

232

Energy Centroids of Spin $I$ States by Random Two-body Interactions  

CERN Document Server

In this paper we study the behavior of energy centroids (denoted as $\\bar{E_I}$) of spin $I$ states in the presence of random two-body interactions, for systems ranging from very simple systems (e.g. single-$j$ shell for very small $j$) to very complicated systems (e.g., many-$j$ shells with different parities and with isospin degree of freedom). Regularities of $\\bar{E_I}$'s discussed in terms of the so-called geometric chaoticity (or quasi-randomness of two-body coefficients of fractional parentage) in earlier works are found to hold even for very simple systems in which one cannot assume the geometric chaoticity. It is shown that the inclusion of isospin and parity does not "break" the regularities of $\\bar{E_I}$'s.

Zhao, Y M; Ogawa, K

2005-01-01

233

VCells: simple and efficient superpixels using Edge-Weighted Centroidal Voronoi Tessellations.  

Science.gov (United States)

VCells, the proposed Edge-Weighted Centroidal Voronoi Tessellations (EWCVTs)-based algorithm, is used to generate superpixels, i.e., an oversegmentation of an image. For a wide range of images, the new algorithm is capable of generating roughly uniform subregions and nicely preserving local image boundaries. The undersegmentation error is effectively limited in a controllable manner. Moreover, VCells is very efficient with core computational cost at O(K?n(c)·N) in which K, n(c), and N are the number of iterations, superpixels, and pixels, respectively. Extensive qualitative discussions are provided, together with the high-quality segmentation results of VCells on a wide range of complex images. The simplicity and efficiency of our model are demonstrated by complexity analysis, time, and accuracy evaluations. PMID:22331852

Wang, Jie; Wang, Xiaoqiang

2012-06-01

234

Use of a Hybrid Edge Node-Centroid Node Approach to Thermal Modeling  

Science.gov (United States)

A recent proposal submitted for an ESA mission required that models be delivered in ESARAD/ESATAN formats. ThermalDesktop was the preferable analysis code to be used for model development with a conversion done as the final step before delivery. However, due to some differences between the capabilities of the two codes, a unique approach was developed to take advantage of the edge node capability of ThermalDesktop while maintaining the centroid node approach used by ESARAD. In essence, two separate meshes were used: one for conduction and one for radiation. The conduction calculations were eliminated from the radiation surfaces and the capacitance and radiative calculations were eliminated from the conduction surfaces. The resulting conduction surface nodes were coincident with all nodes of the radiation surface and were subsequently merged, while the nodes along the edges remained free. Merging of nodes on the edges of adjacent surfaces provided the conductive links between surfaces. Lastly, all nodes along edges were placed into the subnetwork and the resulting supernetwork included only the nodes associated with radiation surfaces. This approach had both benefits and disadvantages. The use of centroid, surface based radiation reduces the overall size of the radiation network, which is often the most computationally intensive part of the modeling process. Furthermore, using the conduction surfaces and allowing ThermalDesktop to calculate the conduction network can save significant time by not having to manually generate the couplings. Lastly, the resulting GMM/TMM models can be exported to formats which do not support edge nodes. One drawback, however, is the necessity to maintain two sets of surfaces. This requires additional care on the part of the analyst to ensure communication between the conductive and radiative surfaces in the resulting overall network. However, with more frequent use of this technique, the benefits of this approach can far outweigh the additional effort.

Peabody, Hume L.

2010-01-01

235

Luminescence properties, centroid shift and energy transfer of Ce3+ in aqueous chloride solutions  

International Nuclear Information System (INIS)

This paper focuses upon three themes: all related to aqueous cerium chloride solutions. First, the features in the absorption spectra of CeCl3 solutions do not shift noticeably with concentration and are at similar energies to bands in the solid-state absorption spectrum of Ce(H2O)93+, with the exception of the weak band at 297 nm which is due to Ce(H2O)83+. The broad emission band in solution is only due to [Ce(H2O)83+]? and the emission quenches at concentrations >0.06 M. Bands in the excitation spectra of aqueous CeCl3 solutions apparently change position with increasing concentration, due to absorption by Ce(H2O)93+ which does not contribute to emission. At concentrations above 1 M, there is total extinction of incident radiation for wavelengths shorter than 310 nm. Second, this system is chosen to illustrate the revised calculation of centroid shift, by taking into account the vibronic nature of spectral features, in contrast with the pure electronic transition of the free ion. Similar calculations are applicable to other Ce3+ systems. Thirdly, excitation spectra are employed to demonstrate the energy transfer occurring from Ce3+ to Tb3+ and Eu3+ in aqueous chloride solutions, which is an unusual energy transfer, occurring from 5d to 4f states and between hydrated lanthanide ions in solution. -- Highlights: • Excitation spectra of aqueous CeCl3 reveal photodissociation and emission only from [Ce(H2O)83+]?. • Revised calculation of centroid shift is given for general cases. • Excitation spectra demonstrate the energy transfer occurring from Ce3+ to Tb3+ and Eu3+ in aqueous chloride solutions. • This is an unusual energy transfer, occurring from 5d to 4f states and between hydrated lanthanide ions in solution

236

Are human service agencies ready for disasters? Findings from a mixed-methods needs assessment and planning project.  

Science.gov (United States)

A mixed-methods design was used to assess the current capacity of human service agencies to provide services in a major disaster, identify challenges and successful strategies for providing those services, and formulate specific recommendations for government planners and the nonprofit sector to promote the integration of human service agencies into emergency preparedness and response. A web-based survey was completed by 188 unique human service agencies, 31 semistructured interviews were conducted with human service agency and government leaders from southeastern Pennsylvania and the mid-Atlantic region, and a collaborative planning meeting was held to review the findings and develop systems-based recommendations. Survey results indicated that human service agencies serve the most vulnerable communities during disasters and would welcome integration into preparedness and response plans, but they currently face challenges that include a lack of real-time communication and opportunities for collaborative planning with government partners. Interview findings were grouped according to 5 themes that emerged: capacity, coordination, communication, training, and leadership. This study identified recommendations to assist human service agencies, local health departments, and emergency management agencies as they work to ensure that needed human services are available during disasters, despite the resource challenges that most agencies face. PMID:25813974

Hipper, Thomas J; Orr, Ashley; Chernak, Esther

2015-01-01

237

Finding possible transition states of defects in silicon-carbide and alpha-iron using the dimer method  

International Nuclear Information System (INIS)

Energetic primary recoil atoms from ion implantation or fast neutron irradiation produce isolated point defects and clusters of both vacancies and interstitials. The migration energies and mechanisms for these defects are crucial to successful multiscale modeling of microstructural evolution during ion-implantation, thermal annealing, or under irradiation over long periods of time. The dimer method is employed to search for possible transition states of interstitials and small interstitial clusters in SiC and ?-Fe. The method uses only the first derivatives of the potential energy to find saddle points without knowledge of the final state of the transition. In SiC, the possible migration pathway for the C interstitial is found to consist of the first neighbor jump via a Si site or second neighbor jump, but the relative probability for the second neighbor jump is very low. In ?-Fe, the possible transition states are studied as a function of interstitial cluster size, and the lowest energy barriers correspond to defect migration along directions. However, this paper addresses whether migrating interstitial clusters can thermally change their direction, and the activation energies and corresponding mechanisms for changing the direction of these clusters are determined

238

Finding possible transition states of defects in silicon-carbide and alpha-iron using the dimer method  

CERN Document Server

Energetic primary recoil atoms from ion implantation or fast neutron irradiation produce isolated point defects and clusters of both vacancies and interstitials. The migration energies and mechanisms for these defects are crucial to successful multiscale modeling of microstructural evolution during ion-implantation, thermal annealing, or under irradiation over long periods of time. The dimer method is employed to search for possible transition states of interstitials and small interstitial clusters in SiC and alpha-Fe. The method uses only the first derivatives of the potential energy to find saddle points without knowledge of the final state of the transition. In SiC, the possible migration pathway for the C interstitial is found to consist of the first neighbor jump via a Si site or second neighbor jump, but the relative probability for the second neighbor jump is very low. In alpha-Fe, the possible transition states are studied as a function of interstitial cluster size, and the lowest energy barriers corr...

Gao Fei; Weber, W J; Corrales, L R; Jonsson, H

2003-01-01

239

Real-time Moment Tensor Inversion and Centroid Location for Large Events from Local and Regional Displacement Records  

Science.gov (United States)

We will present here an algorithm to determine the moment tensor and centroid location for large earthquakes employing local and regional real-time displacement records from GPS or GPS/seismic data. The algorithm extracts the coseismic offset from the displacement waveforms and uses the information to invert for the moment tensor. The Green's functions for a layered Earth are obtained numerically from open source code EDGRN. To determine the centroid multiple inversions are performed simultaneously with different centroid coordinates (inversion nodes), the node with the smallest misfit is then assigned the centroid location. We will show results for two example earthquakes in simulated real-time mode using recorded 1 Hz GPS displacements: the 2003 Mw 8.3 Tokachi-Oki and the 2010 Mw 7.2 El Mayor-Cucapah events. We demonstrate that it is feasible with this methodology to obtain accurate source parameters (magnitude, fault plane geometry and style of faulting) within the first 2-3 minutes after rupture initiation, making this methodology amenable for early detection purposes and rapid source modeling.

Melgar-Moctezuma, D.; Bock, Y.; Crowell, B. W.

2011-12-01

240

Random Centroid Optimization of Phyosphatidylglycerol Stablized Lutein-Enriched Oil-In-Water Emulsions at Acidic pH  

Science.gov (United States)

Lutein has been identified by various studies as a dietary compound that may help delay the onset of macular degeneration. Random centroid optimization was applied to design, prepare, and characterize lutein-enriched oil-in-water (o/w) emulsions containing corn oil (15-25%), whey proteins (1.5-3.5%...

241

A Novel Systematic Error Compensation Algorithm Based on Least Squares Support Vector Regression for Star Sensor Image Centroid Estimation  

Directory of Open Access Journals (Sweden)

Full Text Available The star centroid estimation is the most important operation, which directly affects the precision of attitude determination for star sensors. This paper presents a theoretical study of the systematic error introduced by the star centroid estimation algorithm. The systematic error is analyzed through a frequency domain approach and numerical simulations. It is shown that the systematic error consists of the approximation error and truncation error which resulted from the discretization approximation and sampling window limitations, respectively. A criterion for choosing the size of the sampling window to reduce the truncation error is given in this paper. The systematic error can be evaluated as a function of the actual star centroid positions under different Gaussian widths of star intensity distribution. In order to eliminate the systematic error, a novel compensation algorithm based on the least squares support vector regression (LSSVR with Radial Basis Function (RBF kernel is proposed. Simulation results show that when the compensation algorithm is applied to the 5-pixel star sampling window, the accuracy of star centroid estimation is improved from 0.06 to 6 × 10?5 pixels.

Jingyan Song

2011-07-01

242

Method for finding metabolic properties based on the general growth law. Liver examples. A general framework for biological modeling.  

Science.gov (United States)

We propose a method for finding metabolic parameters of cells, organs and whole organisms, which is based on the earlier discovered general growth law. Based on the obtained results and analysis of available biological models, we propose a general framework for modeling biological phenomena and discuss how it can be used in Virtual Liver Network project. The foundational idea of the study is that growth of cells, organs, systems and whole organisms, besides biomolecular machinery, is influenced by biophysical mechanisms acting at different scale levels. In particular, the general growth law uniquely defines distribution of nutritional resources between maintenance needs and biomass synthesis at each phase of growth and at each scale level. We exemplify the approach considering metabolic properties of growing human and dog livers and liver transplants. A procedure for verification of obtained results has been introduced too. We found that two examined dogs have high metabolic rates consuming about 0.62 and 1 gram of nutrients per cubic centimeter of liver per day, and verified this using the proposed verification procedure. We also evaluated consumption rate of nutrients in human livers, determining it to be about 0.088 gram of nutrients per cubic centimeter of liver per day for males, and about 0.098 for females. This noticeable difference can be explained by evolutionary development, which required females to have greater liver processing capacity to support pregnancy. We also found how much nutrients go to biomass synthesis and maintenance at each phase of liver and liver transplant growth. Obtained results demonstrate that the proposed approach can be used for finding metabolic characteristics of cells, organs, and whole organisms, which can further serve as important inputs and constraints for many applications in biology (such as protein expression), biotechnology (synthesis of substances), and medicine. PMID:24940740

Shestopaloff, Yuri K

2014-01-01

243

Mixed methods evaluation of targeted case finding for cardiovascular disease prevention using a stepped wedged cluster RCT  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background A pilot project cardiovascular prevention was implemented in Sandwell (West Midlands, UK. This used electronic primary care records to identify untreated patients at high risk of cardiovascular disease then invited these high risk patients for assessment by a nurse in their own general practice. Those found to be eligible for treatment were offered treatment. During the pilot a higher proportion of high risk patients were started on treatment in the intervention practices than in control practices. Following the apparent success of the prevention project, it was intended to extend the service to all practices across the Sandwell area. However the pilot project was not a robust evaluation. There was a need for an efficient evaluation that would not disrupt the planned rollout of the project. Methods/design Project nurses will sequentially implement targeted cardiovascular case finding in a phased way across all general practices, with the sequence of general practices determined randomly. This is a stepped wedge randomised controlled trial design. The target population is patients aged 35 to 74, without diabetes or cardiovascular disease whose ten-year cardiovascular risk, (determined from data in their electronic records is ?20%. The primary outcome is the number of high risk patients started on treatment, because these data could be efficiently obtained from electronic primary care records. From this we can determine the effects of the case finding programme on the proportion of high risk patients started on treatment in practices before and after implementation of targeted case finding. Cost-effectiveness will be modelled from the predicted effects of treatments on cardiovascular events and associated health service costs. Alongside the implementation it is intended to interview clinical staff and patients who participated in the programme in order to determine acceptability to patients and clinicians. Practical considerations meant that 26 practices in Sandwell could be randomised, including about 6,250 patients at high risk of cardiovascular disease. This gives sufficient power for evaluation. Discussion It is possible to design a stepped wedge randomised controlled trial using routine data to determine the primary outcome to evaluate implementation of a cardiovascular prevention programme.

Marshall Tom

2012-10-01

244

Luminescence properties, centroid shift and energy transfer of Ce{sup 3+} in aqueous chloride solutions  

Energy Technology Data Exchange (ETDEWEB)

This paper focuses upon three themes: all related to aqueous cerium chloride solutions. First, the features in the absorption spectra of CeCl{sub 3} solutions do not shift noticeably with concentration and are at similar energies to bands in the solid-state absorption spectrum of Ce(H{sub 2}O){sub 9}{sup 3+}, with the exception of the weak band at 297 nm which is due to Ce(H{sub 2}O){sub 8}{sup 3+}. The broad emission band in solution is only due to [Ce(H{sub 2}O){sub 8}{sup 3+}]{sup ?} and the emission quenches at concentrations >0.06 M. Bands in the excitation spectra of aqueous CeCl{sub 3} solutions apparently change position with increasing concentration, due to absorption by Ce(H{sub 2}O){sub 9}{sup 3+} which does not contribute to emission. At concentrations above 1 M, there is total extinction of incident radiation for wavelengths shorter than 310 nm. Second, this system is chosen to illustrate the revised calculation of centroid shift, by taking into account the vibronic nature of spectral features, in contrast with the pure electronic transition of the free ion. Similar calculations are applicable to other Ce{sup 3+} systems. Thirdly, excitation spectra are employed to demonstrate the energy transfer occurring from Ce{sup 3+} to Tb{sup 3+} and Eu{sup 3+} in aqueous chloride solutions, which is an unusual energy transfer, occurring from 5d to 4f states and between hydrated lanthanide ions in solution. -- Highlights: • Excitation spectra of aqueous CeCl{sub 3} reveal photodissociation and emission only from [Ce(H{sub 2}O){sub 8}{sup 3+}]{sup ?}. • Revised calculation of centroid shift is given for general cases. • Excitation spectra demonstrate the energy transfer occurring from Ce{sup 3+} to Tb{sup 3+} and Eu{sup 3+} in aqueous chloride solutions. • This is an unusual energy transfer, occurring from 5d to 4f states and between hydrated lanthanide ions in solution.

Wang, Jiwei; Mei, Yong [Faculty of Physics, Liaoning University, Shenyang 110036 (China); Tanner, Peter A., E-mail: peter.a.tanner@gmail.com [Department of Science and Environmental Studies, The Hong Kong Institute of Education, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong S. A. R. (China)

2014-02-15

245

Kinetic and thermodynamic parameters of biodiesel oxidation with synthetic antioxidants: simplex centroid mixture design  

Scientific Electronic Library Online (English)

Full Text Available A influência da temperatura sobre a oxidação de biodiesel foi avaliada pelos parâmetros cinéticos e termodinâmicos do biocombustível de óleo de soja e gordura suína com antioxidantes sintéticos: 3-terc-butil-4-hidroxianisol (BHA), 3,5-di-terc-butil-hidroxitolueno (BHT), 2-terc-butil-hidroquinona (TB [...] HQ) e galato de propila (PG), de acordo com delineamento de mistura simplex-centróide. Os parâmetros cinéticos foram determinados considerando-se reação de primeira ordem e aplicando a equação de Arrhenius. A adição de antioxidantes promoveu o aumento da energia de ativação (Ea), sendo TBHQ e PG os mais eficientes, apresentando efeito sinérgico. BHT e BHA foram os menos eficientes, assim como suas misturas. Os parâmetros termodinâmicos de ativação, avaliados pela equação de Eyring, não indicaram processos espontâneos (?G‡ > 0) com valores de ?H‡ positivos, e ?S‡ positivos e negativos. O delineamento simplex-centróide indicou valor otimizado de 174,46 kJ mol-1 para a mistura contendo 33,33 e 66,67% de TBHQ e PG, respectivamente. Abstract in english Temperature's influence on biodiesel oxidation was evaluated by kinetic and thermodynamic data in biofuel from soybean oil and lard with synthetic antioxidants: butylatedhydroxyanisol (BHA), butylatedhydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and propylgallate (PG) by simplex centroid mixt [...] ure design. The kinetic parameters ware obtained by Arrhenius equation and showed that addition of antioxidants in all tests increased activation energy (Ea) and that TBHQ and PG were more efficient and presented synergistic effect. BHT and BHA were the least efficient, as well as their mixtures. The thermodynamic activation parameters of the reactions, evaluated by the Eyring equation and based on the theory of the activated complex (ACT), indicated no spontaneous processes (?G‡ > 0) with positive ?H‡ values and positive and negative ?S‡ values. The application of simplex centroid mixture design, using Ea as response, showed the optimised value of 174.46 kJ mol-1 for a mixture containing 33.33 and 66.67% of TBHQ and PG, respectively.

Dionisio, Borsato; Diego, Galvan; Jaqueline L., Pereira; Juliane R., Orives; Karina G., Angilelli; Rodolfo L., Coppo.

1984-19-01

246

12 years of the European-Mediterranean Regional Centroid Moment Tensors and their dissemination  

Science.gov (United States)

The European-Mediterranean Regional Centroid Moment Tensor (RCMT) Catalog collects seismic moment tensor solutions that are routinely computed since 1997 for earthquakes with moderate magnitude (4.5 body and surface waves, but only when the magnitude is greater than 5.0 - i.e. when the signal-to-noise ratio at 40-100 s of period is significant enough to contribute to the inversion. The Catalog is regularly updated a few months behind real time, and reports are published in Phys. Earth Planet. Int. and on the web (http://www.bo.ingv.it/RCMT). RCMTs are also computed in real time. Such preliminary solutions are available within one or a few hours after an earthquake and published as Quick RCMTs. The European-Mediterranean RCMT Catalog currently includes more than 1000 solutions, mainly from the most seismically active areas, such as northern Greece and the Hellenic trench. In the consideration of the size of the Catalog, we constructed a Web Search page that allows to download subsets of data selected on the basis of different parameters. Selections can be made on geographical, time and magnitudes (mb, Ms and Mw) ranges. We consider important as well flags defining the quality of the RCMT and if it is a Definitive or a Quick solution.

Pondrelli, Silvia; Salimbeni, Simone; Morelli, Andrea; Ekstrom, Goran

2010-05-01

247

A new method for the discovery of the best threshold value for finding positive or negative association rules using Binary Particle Swarm Optimization  

OpenAIRE

In association rule mining most of former researches have worked on analytic optimizing method , but finding and specifying the advocate initiation limit influences on association rule mining's quality , which still is important hence this research wants to present a new algorithm for optimizing the analytic efficiency improvement including automatic analyze proper amount for initiation. Through former method this task had been performing based on positive rules but regarding that finding the...

Abdoljabbar Asadi; Azad Shojaei; Salar Saeidi; Salah Karimi; Ebad Karimi

2012-01-01

248

Centroid and Envelope Eynamics of Charged Particle Beams in an Oscillating Wobbler and External Focusing Lattice for Heavy Ion Fusion Applications  

Energy Technology Data Exchange (ETDEWEB)

Recent heavy ion fusion target studies show that it is possible to achieve ignition with direct drive and energy gain larger than 100 at 1MJ. To realize these advanced, high-gain schemes based on direct drive, it is necessary to develop a reliable beam smoothing technique to mitigate instabilities and facilitate uniform deposition on the target. The dynamics of the beam centroid can be explored as a possible beam smoothing technique to achieve a uniform illumination over a suitably chosen region of the target. The basic idea of this technique is to induce an oscillatory motion of the centroid for each transverse slice of the beam in such a way that the centroids of different slices strike different locations on the target. The centroid dynamics is controlled by a set of biased electrical plates called 'wobblers'. Using a model based on moments of the Vlasov-Maxwell equations, we show that the wobbler deflection force acts only on the centroid motion, and that the envelope dynamics are independent of the wobbler fields. If the conducting wall is far away from the beam, then the envelope dynamics and centroid dynamics are completely decoupled. This is a preferred situation for the beam wobbling technique, because the wobbler system can be designed to generate the desired centroid motion on the target without considering its effects on the envelope and emittance. A conceptual design of the wobbler system for a heavy ion fusion driver is briefly summarized.

Ronald C. Davidson and B. Grant Logan

2011-07-19

249

Centroid and Envelope Eynamics of Charged Particle Beams in an Oscillating Wobbler and External Focusing Lattice for Heavy Ion Fusion Applications  

International Nuclear Information System (INIS)

Recent heavy ion fusion target studies show that it is possible to achieve ignition with direct drive and energy gain larger than 100 at 1MJ. To realize these advanced, high-gain schemes based on direct drive, it is necessary to develop a reliable beam smoothing technique to mitigate instabilities and facilitate uniform deposition on the target. The dynamics of the beam centroid can be explored as a possible beam smoothing technique to achieve a uniform illumination over a suitably chosen region of the target. The basic idea of this technique is to induce an oscillatory motion of the centroid for each transverse slice of the beam in such a way that the centroids of different slices strike different locations on the target. The centroid dynamics is controlled by a set of biased electrical plates called 'wobblers'. Using a model based on moments of the Vlasov-Maxwell equations, we show that the wobbler deflection force acts only on the centroid motion, and that the envelope dynamics are independent of the wobbler fields. If the conducting wall is far away from the beam, then the envelope dynamics and centroid dynamics are completely decoupled. This is a preferred situation for the beam wobbling technique, because the wobbler system can be designed to generate the desired centroid motion on the target without considering its effects on the envelope and emittance. A conceptual design of the wobbler system for a heavy ion fusion driver is briefly summarized.

250

Quantum size correction to the work function and the centroid of excess charge in positively ionized simple metal clusters  

Directory of Open Access Journals (Sweden)

Full Text Available  In this work, we have shown the important role of the finite-size correction to the work function in predicting the correct position of the centroid of excess charge in positively charged simple metal clusters with different values . For this purpose, firstly we have calculated the self-consistent Kohn-Sham energies of neutral and singly-ionized clusters with sizes in the framework of local spin-density approximation and stabilized jellium model (SJM as well as simple jellium model (JM with rigid jellium. Secondly, we have fitted our results to the asymptotic ionization formulas both with and without the size correction to the work function. The results of fittings show that the formula containing the size correction predict a correct position of the centroid inside the jellium while the other predicts a false position, outside the jellium sphere.

M. Payami

2003-12-01

251

Partial averaging and the centroid virial estimator for stereographic projection path-integral simulations in curved spaces.  

Science.gov (United States)

We develop and test three different partial averaging theories for the stereographic projection path integral in curved spaces. Additionally, we adapt and test the centroid virial estimator for the kinetic energy in curved spaces. We tested both a confining as well as a nonconfining potential for the particle in a ring. All three partial averaging theories are demonstrated to converge linearly in the asymptotic region with k(-2)max, the number of Fourier coefficients. We use an error estimator to determine the optimal parameters for an extrapolation to infinite kmax. We verify that the centroid virial estimator (derived from the primitive DeWitt path-integral formula) converges to the kinetic energy for both confining and nonconfining potentials. PMID:15945674

Avilés, Michael W; Curotto, E

2005-04-22

252

A Medoid-based Method for Clustering Categorical Data  

OpenAIRE

Medoid-based method is an alternative technique to centroid-based method for partitional clustering algorithms. This method has been incorporated in a recently introduced clustering algorithm for categorical data, called k-Approximate Modal Haplotype (k-AMH) algorithm. This study reports the performance evaluation between the medoid-based method represented by the k-AMH algorithm and the centroid-based method represented by the extended k-Mode algorithm, the k-Po...

Ali Seman; Zainab Abu Bakar; Azizian Mohd. Sapawi; Ida Rosmini Othman

2013-01-01

253

Temnothoraxcrasecundus sp. n. - a cryptic Eurocaucasian ant species (Hymenoptera, Formicidae) discovered by Nest Centroid Clustering.  

Science.gov (United States)

The paper integrates two independent studies of numeric morphology-based alpha-taxonomy of the cryptic ant species Temnothoraxcrassispinus (Karavajev, 1926) and Temnothoraxcrasecundus sp. n. conducted by different investigators, using different equipment, considering different character combinations and evaluating different samples. Samples investigated included 603 individual workers from 203 nests - thereof 104 nest samples measured by Seifert and 99 by Csösz. The material originated from Europe, Asia Minor and Caucasia. There was a very strong interspecific overlap in any of the 29 shape characters recorded and subjective expert determination failed in many cases. Primary classification hypotheses were formed by the exploratory data analysis Nest Centroid (NC) clustering and corrected to final species hypotheses by an iterative linear discriminant analysis algorithm. The evaluation of Seifert's and Csösz's data sets arrived at fully congruent conclusions. NC-Ward and NC-K-means clustering disagreed from the final species hypothesis in only 1.9 and 1.9% of the samples in Seifert's data set and by 1.1 and 2.1% in Csösz's data set which is a strong argument for heterospecificity. The type series of Temnothoraxcrassispinus and Temnothoraxcrasecundus sp. n. were allocated to different clusters with p = 0.9851 and p = 0.9912 respectively. The type series of the junior synonym Temnothoraxslavonicus (Seifert, 1995) was allocated to the Temnothoraxcrassispinus cluster with p = 0.9927. Temnothoraxcrasecundus sp. n. and Temnothoraxcrassispinus are parapatric species with a long contact zone stretching from the Peloponnisos peninsula across Bulgaria northeast to the southern Ukraine. There is no indication for occurrence of interspecifically mixed nests or intraspecific polymorphism. However, a significant reduction of interspecific morphological distance at sites with syntopic occurrence of both species indicates local hybridization. The results are discussed within the context of the Pragmatic Species Concept of Seifert (2014). The taxonomic description and a differential diagnosis of Temnothoraxcrasecundus sp. n. are given. PMID:25685016

Seifert, Bernhard; Csösz, Sandor

2015-01-01

254

Deformation and Geometry of Subducted Lithosphere from an Analysis of Global Centroid Moment Tensor Data  

Science.gov (United States)

We present an analysis of Global Centroid Moment Tensor (CMT) solutions and earthquake hypocenter data to quantitatively constrain geometry and coseismic strain release for slabs associated with 22 different subduction zones. Our primary motivation is to update the results of Isacks and Molnar (1971), who performed a similar analysis based on 204 focal mechanisms, using updated catalogs of 30,633 hypocenters and 2,788 CMT solutions. We constrain slab geometry by fitting polynomial functions to hypocenter data and calculate coseismic deformation within the slabs using moment tensor summations. In general, our results are similar to those of Isacks and Molnar (1971): deep earthquakes (greater than 410 km) are dominantly compressive down-dip, while intermediate depth earthquakes (100-410 km) are generally compressive if the slab is continuous to depths greater than 410 km and extensive otherwise. With the inclusion of more data, it is less likely that exceptions to these patterns (e.g., Ryukyu and Banda slabs) can be explained by outlying data points and we investigate these cases using 3-D numerical models. In contrast to Isacks and Molnar (1971), changes in the deformation that coincide with geometrical changes in the slab dip are also observed, suggesting that geometry may have an observable effect on slab deformation. This is supported by analysis of the summed tensor compensated linear vector dipole (CLVD) components, which are larger close to changes in the slab geometries. An analysis of tensors summed globally for different depth bins shows that for depths greater than 400 km the tensors have a strong CLVD component indicating uniaxial compression and horizontal extension. For depths above 300 km the deformation shows N-S compression and E-W extension. We also present results from 3-D numerical models which compare CMT orientations to stress orientations to constrain the slab and mantle rheology, and possible regional effects that produce the best match to observations.

Alpert, L. A.; Bailey, I. W.; Becker, T. W.

2010-12-01

255

Hybrid Extragradient-Type Methods for Finding a Common Solution of an Equilibrium Problem and a Family of Strict Pseudo-Contraction Mappings  

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes a new hybrid variant of extragradient methods for finding a common solution of an equilibrium problem and a family of strict pseudo-contraction mappings. We present an algorithmic scheme that combine the idea of an extragradient method and a successive iteration method as a hybrid variant. Then, this algorithm is modified by projecting on a suitable convex set to get a better convergence property. The convergence of two these algorithms are investigated under certain assumptions.

Pham Ngoc Anh

2012-10-01

256

Hybrid Extragradient-Type Methods for Finding a Common Solution of an Equilibrium Problem and a Family of Strict Pseudo-Contraction Mappings  

OpenAIRE

This paper proposes a new hybrid variant of extragradient methods for finding a common solution of an equilibrium problem and a family of strict pseudo-contraction mappings. We present an algorithmic scheme that combine the idea of an extragradient method and a successive iteration method as a hybrid variant. Then, this algorithm is modified by projecting on a suitable convex set to get a better convergence property. The convergence of two these algorithms are investigated under certain assum...

Pham Ngoc Anh; Tran Dinh Quoc; Dang Xuan Son

2012-01-01

257

A genetic-algorithm-based method to find unitary transformations for any desired quantum computation and application to a one-bit oracle decision problem  

Science.gov (United States)

We propose a genetic-algorithm-based method to find the unitary transformations for any desired quantum computation. We formulate a simple genetic algorithm by introducing the "genetic parameter vector" of the unitary transformations to be found. In the genetic algorithm process, all components of the genetic parameter vectors are supposed to evolve to the solution parameters of the unitary transformations. We apply our method to find the optimal unitary transformations and to generalize the corresponding quantum algorithms for a realistic problem, the one-bit oracle decision problem, or the often-called Deutsch problem. By numerical simulations, we can faithfully find the appropriate unitary transformations to solve the problem by using our method. We analyze the quantum algorithms identified by the found unitary transformations and generalize the variant models of the original Deutsch's algorithm.

Bang, Jeongho; Yoo, Seokwon

2014-12-01

258

Pseudometrically Constrained Centroidal Voronoi Tessellations: Generating uniform antipodally symmetric points on the unit sphere with a novel acceleration strategy and its applications to Diffusion and 3D radial MRI  

CERN Document Server

Purpose: The purpose of this work is to investigate the hypothesis that uniform sampling measurements that are endowed with antipodal symmetry play an important role when the raw data and image data are related through the Fourier relationship as in q-space diffusion MRI and 3D radial MRI. Currently, it is extremely challenging to generate large uniform antipodally symmetric point sets suitable for 3D radial MRI. A novel approach is proposed to solve this important and long-standing problem. Methods: The proposed method is based upon constrained centroidal Voronoi tessellations of the upper hemisphere with a novel pseudometric. Geometrically intuitive approach to tessellating the upper hemisphere is also proposed. Results: The average time complexity of the proposed centroidal tessellations was shown to be effectively on the order of the product of the number of iterations and the number of generators. For small sample size, the proposed method was comparable to the state-of-the-art iterative method in terms ...

Koay, Cheng Guan

2012-01-01

259

For a reasoned development of experimental methods in information and communication sciences Some epistemological findings of methodological pluralism  

Directory of Open Access Journals (Sweden)

Full Text Available If multidisciplinarity is necessary, first, for studying the widest possible set of communication phenomena (organizational, in groups, interpersonal, media, computer-mediated communication... and, secondly, for grasping the complexity of the different moments of the same phenomenon of communication (production, content, reception, circulation ..., methodological pluralism is also important. However, French research in communication sciences leaves in the shade a number of phenomena and moments of communication that could be better understood thanks to the experimental method. We will underline that the epistemological issues related to rational use of the experimental method in communication sciences are not negligible: it allows the study of objects that cannot be investigated with other methods and offers the opportunity to build knowledge by the refutation of hypotheses and theoretical propositions. We will clarify some epistemological misunderstandings concerning this method. First, it is actually a method of studying complex systems and communication processes. Secondly, its use is not incompatible with constructivism.

Didier COURBET

2013-07-01

260

The centroid shift of the 5d levels of Ce sup 3 sup + with respect to the 4f levels in ionic crystals, a theoretical investigation  

CERN Document Server

The centroid shifts of the 5d level of Ce sup 3 sup + in BaF sub 2 , LaAlO sub 3 and LaCl sub 3 have been calculated using the ionic cluster approach. By applying configuration interaction as extension of the basic HF-LCAO approach the dynamical polarization contribution to the centroid shift was calculated. This was found to be only successful if basis sets are used optimized for polarization of the anions.

Andriessen, J; Eijk, C W E

2002-01-01

261

A fast and versatile wire chamber space point finding processor  

International Nuclear Information System (INIS)

A four plane, four metre square, multiwire proportional counter at the CERN Omega spectrometer is used to digitize the spatial position of charged particles and generate a fast second level trigger. The coordinates of cluster centroids are fed into a modular space point finding processor which can analyse a ten particle event in 40 ?s. The detector and the algorithms are described in the first part of this paper, the hardware implementation and the performance are then discussed. (orig.)

262

PyMGC3: Finding stellar streams in the Galactic Halo using a family of Great Circle Cell counts methods  

Science.gov (United States)

PyMGC3 is a Python toolkit to apply the Modified Great Circle Cell Counts (mGC3) method to search for tidal streams in the Galactic Halo. The code computes pole count maps using the full mGC3/nGC3/GC3 family of methods. The original GC3 method (Johnston et al., 1996) uses positional information to search for 'great-circle-cell structures'; mGC3 makes use of full 6D data and nGC3 uses positional and proper motion data.

Mateu, C.

2014-11-01

263

Using quantitative and qualitative data in health services research – what happens when mixed method findings conflict? [ISRCTN61522618  

OpenAIRE

Abstract Background In this methodological paper we document the interpretation of a mixed methods study and outline an approach to dealing with apparent discrepancies between qualitative and quantitative research data in a pilot study evaluating whether welfare rights advice has an impact on health and social outcomes among a population aged 60 and over. Methods Quantitative and qualitative data were collected contemporaneously. Quantitative data were collected from 126 men and women aged ov...

Howel Denise; Mackintosh Joan; White Martin; Moffatt Suzanne

2006-01-01

264

Direct digital method fast-acting analysis of the correlation-interferometric radio direction-finding with reconstructing of spatial analytical  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction. Nowadays radio control of radio electronic devices must be carried out in the conditions of sticky electromagnetic wicket, large prior uncertainty in relation to the parameters of radiations, and also in the conditions of the real time realization. The use and researches of direct digital methods of correlation-interferometric direction-finding is perspective direction in radio control realization for the indicated terms. Fundamentals of researches. In this paper, the direct digital method fast-acting analysis of the correlation-interferometric radio direction-finding with reconstructing of spatial analytical signal is executed. The estimation of time charges, fast-acting and relative time efficiency of method is executed. Conclusions. It is certain that analyzed direct method of direction-finding provides a spatial selection and simultaneous direction-finding of radiations which get in the pass frequencies band of simultaneous analysis with a width to one hundred ten megahertz real-time with the use of only one signal processor.

V. V. Tsyporenko

2013-04-01

265

A period-finding method for sparse randomly spaced observations or 'How long is a piece of string'  

International Nuclear Information System (INIS)

A string-length method for establishing the period of a variable star from a relatively small number of randomly spaced observations over a long span of time is investigated. Criteria for establishing the validity of indicated periods are presented. The method is particularly suited for determination of periods in the limiting case of relatively few observations of reasonably high accuracy. A revised period and orbital elements for a spectroscopic binary observed by Abt and Levy (17 Lyr) are given. The period given by Abt and Levy for 18 Com is not confirmed; the data are insufficient to determine the correct period. (author)

266

Quantum size correction to the work function and the centroid of excess charge in positively ionized simple metal clusters  

OpenAIRE

In this work, we have shown the important role of the finite-size correction to the work function in predicting the correct positions of the centroid of excess charge in positively charged simple metal clusters with different $r_s$ values ($2\\le r_s\\le7$). For this purpose, firstly we have calculated the self-consistent Kohn-Sham energies of neutral and singly-ionized clusters with sizes $2\\le N\\le 100$ in the framework of local spin-density approximation and stabilized jell...

Payami, M.

2002-01-01

267

Perturbed damped pendulum: finding periodic solutions via averaging method / Perturbações do pêndulo amortecido: encontrando soluções periódicas via método averaging  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Utilizando o modelo do pêndulo amortecido, introduzimos o método "averaging" no estudo de soluções periódicas de sistemas dinâmicos com pequenas perturbações não autónomas. Considerando perturbações do sistema do pêndulo amortecido, fornecemos condições suficientes para a existência de soluções peri [...] ódicas de pequena amplitude. O método "averaging" fornece uma ferramenta útil no estudo de sistemas dinâmicos e é acessível a estudantes de pós-graduação. Abstract in english Using the damped pendulum model we introduce the averaging method to study the periodic solutions of dynamical systems with small non-autonomous perturbation. We provide sufficient conditions for the existence of periodic solutions with small amplitude of the non-linear perturbed damped pendulum. Th [...] e averaging method provides a useful means to study dynamical systems, accessible to Master and PhD students.

Douglas D., Novaes.

2013-03-01

268

Numerical methods for finding periodic points in discrete maps. High order islands chains and noble barriers in a toroidal magnetic configuration  

Energy Technology Data Exchange (ETDEWEB)

We first remind usual physical and mathematical concepts involved in the dynamics of Hamiltonian systems, and namely in chaotic systems described by discrete 2D maps (representing the intersection points of toroidal magnetic lines in a poloidal plane in situations of incomplete magnetic chaos in Tokamaks). Finding the periodic points characterizing chains of magnetic islands is an essential step not only to determine the skeleton of the phase space picture, but also to determine the flux of magnetic lines across semi-permeable barriers like Cantori. We discuss here several computational methods used to determine periodic points in N dimensions, which amounts to solve a set of N nonlinear coupled equations: Newton method, minimization techniques, Laplace or steepest descend method, conjugated direction method and Fletcher-Reeves method. We have succeeded to improve this last method in an important way, without modifying its useful double-exponential convergence. This improved method has been tested and applied to finding periodic points of high order m in the 2D 'Tokamap' mapping, for values of m along rational chains of winding number n/m converging towards a noble value where a Cantorus exists. Such precise positions of periodic points have been used in the calculation of the flux across this Cantorus. (authors)

Steinbrecher, G. [Association Euratom-Nasti Romania, Dept. of Theoretical Physics, Physics Faculty, University of Craiova (Romania); Reuss, J.D.; Misguich, J.H. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

2001-11-01

269

Numerical methods for finding periodic points in discrete maps. High order islands chains and noble barriers in a toroidal magnetic configuration  

International Nuclear Information System (INIS)

We first remind usual physical and mathematical concepts involved in the dynamics of Hamiltonian systems, and namely in chaotic systems described by discrete 2D maps (representing the intersection points of toroidal magnetic lines in a poloidal plane in situations of incomplete magnetic chaos in Tokamaks). Finding the periodic points characterizing chains of magnetic islands is an essential step not only to determine the skeleton of the phase space picture, but also to determine the flux of magnetic lines across semi-permeable barriers like Cantori. We discuss here several computational methods used to determine periodic points in N dimensions, which amounts to solve a set of N nonlinear coupled equations: Newton method, minimization techniques, Laplace or steepest descend method, conjugated direction method and Fletcher-Reeves method. We have succeeded to improve this last method in an important way, without modifying its useful double-exponential convergence. This improved method has been tested and applied to finding periodic points of high order m in the 2D 'Tokamap' mapping, for values of m along rational chains of winding number n/m converging towards a noble value where a Cantorus exists. Such precise positions of periodic points have been used in the calculation of the flux across this Cantorus. (authors)

270

Ground experiments for finding principles and working out methods for preventing adverse effects of weightlessness on the human organism  

Science.gov (United States)

A comparative assessment of the effectiveness of different prophylactic procedures to prevent the adverse effects of weightlessness is presented. It is concluded that: physical training is most effective but no single method by itself produces the full effect, and an adjustment of regimes to one another enhances the effect. The approved complex of prophylactic procedures affected basic changes occurring in hypokinesia: deficit of muscular activity, no or reduced BP hydrostatic component, reduced volume of blood circulation, reduced hydration level, and the application of various prophylactic complexes during 49 day antiorthostatic hypodynamia eliminated or reduced the adverse effects of weightlessness in simulation.

Kakurin, L. I.; Gregoryev, A. I.; Mikhailov, V. M.; Tishler, V. A.

1980-01-01

271

Characterization of a millefiori glass find from Aquincum by SEM-EDX and micro-PIXE methods  

Energy Technology Data Exchange (ETDEWEB)

Research has been focused on the analysis of archaeological glasses from the Roman age and medieval times. Study of ancient millefiori type glasses from the collection of Hungarian Museums has been started. A test measurement, carried out on a glass fragment supposedly part of a dish, was performed by SEM-EDX and micro-PIXE methods. Complementary analytical data were obtained for texture and composition. Results suggest that Roman and Mesopotamian techniques were used together. Our data contribute to data bases of millefiori glasses.

Uzonyi, I., E-mail: uzonyi@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4026 Debrecen, Bem ter 18/C (Hungary); Csontos, K.; Verebes, A. [Budapest History Museum, Aquincum Museum H-8211 Budapest, Zahony u. 4. (Hungary); Cserhati, C. [Department of Solid State Physics, University of Debrecen H-4032 Debrecen, Bem ter 18/B (Hungary); Csedreki, L.; Kis-Varga, M.; Kiss, A.Z. [Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4026 Debrecen, Bem ter 18/C (Hungary)

2011-10-15

272

Improvements and new findings in Monte Carlo method with complex-valued weights for neutron leakage-corrected assembly calculations  

International Nuclear Information System (INIS)

The author of this paper recently proposed a Monte Carlo calculation algorithm to solve a complex transport equation with complex-valued weights. The algorithm enables one to generate neutron leakage-corrected group constants and anisotropic diffusion coefficients for a unit fuel pin cell or assembly. The group constants are subsequently used for multi-group deterministic core calculations. The technique, however, had some limitations in applying itself to general problems. Some improvements have been done in this paper. The reflective boundary condition has newly become available. It has been found that a cumbersome weight cancellation of fission sources with positive and negative weights can be omitted in general fuel assembly geometries. A homogenization method of diffusion coefficients for a fuel assembly has been proposed. (author)

273

A new method for the discovery of the best threshold value for finding positive or negative association rules using Binary Particle Swarm Optimization  

Directory of Open Access Journals (Sweden)

Full Text Available In association rule mining most of former researches have worked on analytic optimizing method , but finding and specifying the advocate initiation limit influences on association rule mining's quality , which still is important hence this research wants to present a new algorithm for optimizing the analytic efficiency improvement including automatic analyze proper amount for initiation. Through former method this task had been performing based on positive rules but regarding that finding the negative ones were though for administrator, this research's privilege is that the initiation level automatically is analyzed for the first time; also it has high efficiency in large data base. Particle Swarm Optimization is observed for any particle's efficiency and as data turned in binary the advocate amount will be found. Results showed Particle Swarm Optimization could present better initiation level, and enhance the former algorithm's result a lot. Consequence will be comparing with Weka and Apriori.

Abdoljabbar Asadi

2012-11-01

274

Automatic NC-Data generation method for 5-axis cutting of turbine-blades by finding Safe heel-angles and adaptive path-intervals  

International Nuclear Information System (INIS)

In this paper, an efficient method for generating 5-axis cutting data for a turbine blade is presented. The interference elimination of 5-axis cutting currently is very complicated, and it takes up a lot of time. The proposed method can generate an interference-free tool path, within an allowance range. Generating the cutting data just point to the cutting process and using it to obtain NC data by calculating the feed rate, allows us to maintain the proper feed rate of the 5-axis machine. This paper includes the algorithms for: (1) CL data generation by detecting an interference-free heel angle, (2) finding the optimal tool path interval considering the cusp-height, (3) finding the adaptive feed rate values for each cutter path, and (4) the inverse kinematics depending on the structure of the 5-axis machine, for generating the NC data

275

The Tourette International Collaborative Genetics (TIC Genetics) study, finding the genes causing Tourette syndrome: objectives and methods.  

Science.gov (United States)

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by recurrent motor and vocal tics, often accompanied by obsessive-compulsive disorder and/or attention-deficit/hyperactivity disorder. While the evidence for a genetic contribution is strong, its exact nature has yet to be clarified fully. There is now mounting evidence that the genetic risks for TS include both common and rare variants and may involve complex multigenic inheritance or, in rare cases, a single major gene. Based on recent progress in many other common disorders with apparently similar genetic architectures, it is clear that large patient cohorts and open-access repositories will be essential to further advance the field. To that end, the large multicenter Tourette International Collaborative Genetics (TIC Genetics) study was established. The goal of the TIC Genetics study is to undertake a comprehensive gene discovery effort, focusing both on familial genetic variants with large effects within multiply affected pedigrees and on de novo mutations ascertained through the analysis of apparently simplex parent-child trios with non-familial tics. The clinical data and biomaterials (DNA, transformed cell lines, RNA) are part of a sharing repository located within the National Institute for Mental Health Center for Collaborative Genomics Research on Mental Disorders, USA, and will be made available to the broad scientific community. This resource will ultimately facilitate better understanding of the pathophysiology of TS and related disorders and the development of novel therapies. Here, we describe the objectives and methods of the TIC Genetics study as a reference for future studies from our group and to facilitate collaboration between genetics consortia in the field of TS. PMID:24771252

Dietrich, Andrea; Fernandez, Thomas V; King, Robert A; State, Matthew W; Tischfield, Jay A; Hoekstra, Pieter J; Heiman, Gary A

2015-02-01

276

A comparison of three clustering methods for finding subgroups in MRI, SMS or clinical data : SPSS TwoStep Cluster analysis, Latent Gold and SNOB  

DEFF Research Database (Denmark)

BACKGROUND: There are various methodological approaches to identifying clinically important subgroups and one method is to identify clusters of characteristics that differentiate people in cross-sectional and/or longitudinal data using Cluster Analysis (CA) or Latent Class Analysis (LCA). There is a scarcity of head-to-head comparisons that can inform the choice of which clustering method might be suitable for particular clinical datasets and research questions. Therefore, the aim of this study was to perform a head-to-head comparison of three commonly available methods (SPSS TwoStep CA, Latent Gold LCA and SNOB LCA). METHODS: The performance of these three methods was compared: (i) quantitatively using the number of subgroups detected, the classification probability of individuals into subgroups, the reproducibility of results, and (ii) qualitatively using subjective judgments about each program's ease of use and interpretability of the presentation of results.We analysed five real datasets of varying complexity in a secondary analysis of data from other research projects. Three datasets contained only MRI findings (n = 2,060 to 20,810 vertebral disc levels), one dataset contained only pain intensity data collected for 52 weeks by text (SMS) messaging (n = 1,121 people), and the last dataset contained a range of clinical variables measured in low back pain patients (n = 543 people). Four artificial datasets (n = 1,000 each) containing subgroups of varying complexity were also analysed testing the ability of these clustering methods to detect subgroups and correctly classify individuals when subgroup membership was known. RESULTS: The results from the real clinical datasets indicated that the number of subgroups detected varied, the certainty of classifying individuals into those subgroups varied, the findings had perfect reproducibility, some programs were easier to use and the interpretability of the presentation of their findings also varied. The results from the artificial datasets indicated that all three clustering methods showed a near-perfect ability to detect known subgroups and correctly classify individuals into those subgroups. CONCLUSIONS: Our subjective judgement was that Latent Gold offered the best balance of sensitivity to subgroups, ease of use and presentation of results with these datasets but we recognise that different clustering methods may suit other types of data and clinical research questions.

Kent, Peter; Jensen, Rikke K

2014-01-01

277

PERFORMANCE OF SELECTED AGGLOMERATIVE HIERARCHICAL CLUSTERING METHODS  

Directory of Open Access Journals (Sweden)

Full Text Available A broad variety of different methods of agglomerative hierarchical clustering brings along problems how to choose the most appropriate method for the given data. It is well known that some methods outperform others if the analysed data have a specific structure. In the presented study we have observed the behaviour of the centroid, the median (Gower median method, and the average method (unweighted pair-group method with arithmetic mean – UPGMA; average linkage between groups. We have compared them with mostly used methods of hierarchical clustering: the minimum (single linkage clustering, the maximum (complete linkage clustering, the Ward, and the McQuitty (groups method average, weighted pair-group method using arithmetic averages - WPGMA methods. We have applied the comparison of these methods on spherical, ellipsoid, umbrella-like, “core-and-sphere”, ring-like and intertwined three-dimensional data structures. To generate the data and execute the analysis, we have used R statistical software. Results show that all seven methods are successful in finding compact, ball-shaped or ellipsoid structures when they are enough separated. Conversely, all methods except the minimum perform poor on non-homogenous, irregular and elongated ones. Especially challenging is a circular double helix structure; it is being correctly revealed only by the minimum method. We can also confirm formerly published results of other simulation studies, which usually favour average method (besides Ward method in cases when data is assumed to be fairly compact and well separated.

Nusa Erman

2015-01-01

278

A colorimetric method for highly sensitive and accurate detection of iodide by finding the critical color in a color change process using silver triangular nanoplates  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: -- Highlights: •Demonstrated a new colorimetric strategy for iodide detection by silver nanoplates. •The colorimetric strategy is to find the critical color in a color change process. •The colorimetric strategy is more accurate and sensitive than common colorimetry. •Discovered a new morphological transformation phenomenon of silver nanoplates. -- Abstract: In this contribution, we demonstrated a novel colorimetric method for highly sensitive and accurate detection of iodide using citrate-stabilized silver triangular nanoplates (silver TNPs). Very lower concentration of iodide can induce an appreciable color change of silver TNPs solution from blue to yellow by fusing of silver TNPs to nanoparticles, as confirmed by UV–vis absorption spectroscopy and transmission electron microscopy (TEM). The principle of this colorimetric assay is not an ordinary colorimetry, but a new colorimetric strategy by finding the critical color in a color change process. With this strategy, 0.1 ?M of iodide can be recognized within 30 min by naked-eyes observation, and lower concentration of iodide down to 8.8 nM can be detected using a spectrophotometer. Furthermore, this high sensitive colorimetric assay has good accuracy, stability and reproducibility comparing with other ordinary colorimetry. We believe this new colorimetric method will open up a fresh insight of simple, rapid and reliable detection of iodide and can find its future application in the biochemical analysis or clinical diagnosis.

Yang, Xiu-Hua; Ling, Jian, E-mail: lingjian@ynu.edu.cn; Peng, Jun; Cao, Qiu-E., E-mail: qecao@ynu.edu.cn; Ding, Zhong-Tao; Bian, Long-Chun

2013-10-10

279

A colorimetric method for highly sensitive and accurate detection of iodide by finding the critical color in a color change process using silver triangular nanoplates  

International Nuclear Information System (INIS)

Graphical abstract: -- Highlights: •Demonstrated a new colorimetric strategy for iodide detection by silver nanoplates. •The colorimetric strategy is to find the critical color in a color change process. •The colorimetric strategy is more accurate and sensitive than common colorimetry. •Discovered a new morphological transformation phenomenon of silver nanoplates. -- Abstract: In this contribution, we demonstrated a novel colorimetric method for highly sensitive and accurate detection of iodide using citrate-stabilized silver triangular nanoplates (silver TNPs). Very lower concentration of iodide can induce an appreciable color change of silver TNPs solution from blue to yellow by fusing of silver TNPs to nanoparticles, as confirmed by UV–vis absorption spectroscopy and transmission electron microscopy (TEM). The principle of this colorimetric assay is not an ordinary colorimetry, but a new colorimetric strategy by finding the critical color in a color change process. With this strategy, 0.1 ?M of iodide can be recognized within 30 min by naked-eyes observation, and lower concentration of iodide down to 8.8 nM can be detected using a spectrophotometer. Furthermore, this high sensitive colorimetric assay has good accuracy, stability and reproducibility comparing with other ordinary colorimetry. We believe this new colorimetric method will open up a fresh insight of simple, rapid and reliable detection of iodide and can find its future application in the biochemical analysis or clinical diagnosis

280

Global pathways to men's caregiving: mixed methods findings from the International Men and Gender Equality Survey and the Men Who Care study.  

Science.gov (United States)

Promoting men's participation in unpaid care work is part of the Programme of Action for the International Conference on Population and Development. However, men's involvement in care work does not mirror the advances women have made in paid work outside the home. This mixed method study explores which men are more involved in caregiving, and what childhood and adulthood factors influence their level of involvement. Quantitative research presents findings from 1169 men across six countries with children aged 0-4, and a qualitative study presents findings from in-depth interviews with 83 men engaged in atypical caregiving practices. Survey research finds that being taught to care for children, witnessing one's father take care of one's siblings, respondents' present attitudes about gender equality and having outside help (or none, in some cases) were all also associated with men's higher level of involvement. Qualitative research reveals that men's experiences of violence, the normalisation of domestic work as children and life circumstances rather than greater-than-average beliefs in gender equality all propelled them into care work. Findings suggest that engaging more men into care work implies changes to policies and structural realities in the workplace coupled with changing gender attitudes. These insights inform policy and practice aimed at promoting greater involvement in care work by men. PMID:24938308

Kato-Wallace, Jane; Barker, Gary; Eads, Marci; Levtov, Ruti

2014-01-01

281

The New Multi-HAzard and MulTi-RIsK Assessment MethodS for Europe (MATRIX) Project - An overview of its major findings  

Science.gov (United States)

Recent major natural disasters, such as the 2011 T?hoku earthquake, tsunami and subsequent Fukushima nuclear accident, have raised awareness of the frequent and potentially far-reaching interconnections between natural hazards. Such interactions occur at the hazard level, where an initial hazard may trigger other events (e.g., an earthquake triggering a tsunami) or several events may occur concurrently (or nearly so), e.g., severe weather around the same time as an earthquake. Interactions also occur at the vulnerability level, where the initial event may make the affected community more susceptible to the negative consequences of another event (e.g., an earthquake weakens buildings, which are then damaged further by windstorms). There is also a temporal element involved, where changes in exposure may alter the total risk to a given area. In short, there is the likelihood that the total risk estimated when considering multiple hazard and risks and their interactions is greater than the sum of their individual parts. It is with these issues in mind that the European Commission, under their FP7 program, supported the New Multi-HAzard and MulTi-RIsK Assessment MethodS for Europe or MATRIX project (10.2010 to 12.2013). MATRIX set out to tackle multiple natural hazards (i.e., those of concern to Europe, namely earthquakes, landslides, volcanos, tsunamis, wild fires, storms and fluvial and coastal flooding) and risks within a common theoretical framework. The MATRIX work plan proceeded from an assessment of single-type risk methodologies (including how uncertainties should be treated), cascade effects within a multi-hazard environment, time-dependent vulnerability, decision making and support for multi-hazard mitigation and adaption, and an assessment of how the multi-hazard and risk viewpoint may be integrated into current decision making and risk mitigation programs, considering the existing single-hazard and risk focus. Three test sites were considered during the project: Naples, Cologne, and the French West Indies. In addition, a software platform, the MATRIX-Common IT sYstem (MATRIX-CITY), was developed to allow the evaluation of characteristic multi-hazard and risk scenarios in comparison to single-type analyses. This presentation therefore outlines the more significant outcomes of the project, in particular those dealing with the harmonization of single-type hazards, cascade event analysis, time-dependent vulnerability changes and the response of the disaster management community to the MATRIX point of view.

Fleming, Kevin; Zschau, Jochen; Gasparini, Paolo

2014-05-01

282

Reliability of change in lumbar MRI findings over time in patients with and without disc prosthesis - comparing two different image evaluation methods  

International Nuclear Information System (INIS)

To assess the reliability of change in lumbar magnetic resonance imaging (MRI) findings evaluated retrospectively by direct comparison of images and by non-comparison. Pre-treatment and 2-year follow-up MRI was performed in 126 patients randomized to disc prosthesis surgery or non-surgical treatment. Two experienced radiologists independently evaluated progress and regress for Modic changes, disc findings, and facet arthropathy (FA) at L3/L4, L4/L5, and L5/S1, both by non-comparison and by comparison of initial and follow-up images. FA was evaluated at all levels, and other findings at non-operated levels. We calculated prevalence- and bias-adjusted kappa (PABAK) values for interobserver agreement. The impact of an adjacent prosthesis (which causes artefacts) and image evaluation method on PABAK was assessed using generalized estimating equations. Image comparison indicated good interobserver agreement on progress and regress (PABAK 0.63-1.00) for Modic changes, posterior high-intensity zone, disc height, and disc contour at L3-S1 and for nucleus pulposus signal and FA at L3/L4; and moderate interobserver agreement (PABAK 0.46-0.59) on decreasing nucleus signal and increasing FA at L4-S1. Image comparison indicated lower (but fair) interobserver agreement (PABAK 0.29) only for increasing FA at L5/S1 in patients with prosthesis in L4/L5 and/or L5/S1. An adjacent prosthesis had no overall impact on PABAK values (p ? 0.22). Comparison yielded higher PABAK values than nrison yielded higher PABAK values than non-comparison (p < 0.001). Regarding changes in lumbar MRI findings over time, comparison of images can provide moderate or good interobserver agreement, and better agreement than non-comparison. An adjacent prosthesis may not reduce agreement on change for most findings. (orig.)

283

Reliability of change in lumbar MRI findings over time in patients with and without disc prosthesis - comparing two different image evaluation methods  

Energy Technology Data Exchange (ETDEWEB)

To assess the reliability of change in lumbar magnetic resonance imaging (MRI) findings evaluated retrospectively by direct comparison of images and by non-comparison. Pre-treatment and 2-year follow-up MRI was performed in 126 patients randomized to disc prosthesis surgery or non-surgical treatment. Two experienced radiologists independently evaluated progress and regress for Modic changes, disc findings, and facet arthropathy (FA) at L3/L4, L4/L5, and L5/S1, both by non-comparison and by comparison of initial and follow-up images. FA was evaluated at all levels, and other findings at non-operated levels. We calculated prevalence- and bias-adjusted kappa (PABAK) values for interobserver agreement. The impact of an adjacent prosthesis (which causes artefacts) and image evaluation method on PABAK was assessed using generalized estimating equations. Image comparison indicated good interobserver agreement on progress and regress (PABAK 0.63-1.00) for Modic changes, posterior high-intensity zone, disc height, and disc contour at L3-S1 and for nucleus pulposus signal and FA at L3/L4; and moderate interobserver agreement (PABAK 0.46-0.59) on decreasing nucleus signal and increasing FA at L4-S1. Image comparison indicated lower (but fair) interobserver agreement (PABAK 0.29) only for increasing FA at L5/S1 in patients with prosthesis in L4/L5 and/or L5/S1. An adjacent prosthesis had no overall impact on PABAK values (p {>=} 0.22). Comparison yielded higher PABAK values than non-comparison (p < 0.001). Regarding changes in lumbar MRI findings over time, comparison of images can provide moderate or good interobserver agreement, and better agreement than non-comparison. An adjacent prosthesis may not reduce agreement on change for most findings. (orig.)

Berg, Linda; Espeland, Ansgar [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Section for Radiology, Department of Surgical Sciences, Bergen (Norway); Gjertsen, Oeivind [Oslo University Hospital, Department of Neuroradiology, Oslo (Norway); Hellum, Christian [Oslo University Hospital, Department of Orthopaedics, Oslo (Norway); University of Oslo, Department of Orthopaedics, Oslo (Norway); Neckelmann, Gesche [Haukeland University Hospital, Department of Radiology, Bergen (Norway); Johnsen, Lars G. [University Hospital of Trondheim, National Centre for Diseases of the Spine, Trondheim (Norway); University Hospital of Trondheim, Orthopaedic Department, Trondheim (Norway); Eide, Geir E. [Haukeland University Hospital, Centre for Clinical Research, Bergen (Norway); University of Bergen, Department of Public Health and Primary Health Care, Bergen (Norway)

2012-12-15

284

A direct truncation method for finding abundant exact solutions and application to the one-dimensional higher-order Schroedinger equation  

International Nuclear Information System (INIS)

We suggest a direct truncation technique for finding exact solutions of nonlinear differential equation, this method is based on the WTC test. As an application, abundant new exact stationary solutions of the one-dimensional higher-order nonlinear Schroedinger equation are obtained. These solutions include bright, dark, kink or anti-kink solitary wave solutions, which are dependent of the model and free parameters in the solutions. Algebraic solitary-like solution and new periodic solutions are also obtained. An interesting fact is that some solitary solutions can convert into the periodic solutions and vice versa when the free parameters are changed

285

Astrometric Image Centroid Displacements due to Gravitational Microlensing by the Ellis Wormhole  

OpenAIRE

Continuing work initiated in an earlier publication (Abe, ApJ, 725 (2010) 787), we study the gravitational microlensing effects of the Ellis wormhole in the weak-field limit. First, we find a suitable coordinate transformation, such that the lens equation and analytic expressions of the lensed image positions can become much simpler than the previous ones. Second, we prove that two images always appear for the weak-field lens by the Ellis wormhole. By using these analytic re...

Toki, Yukiharu; Kitamura, Takao; Asada, Hideki; Abe, Fumio

2011-01-01

286

Segmentation of Renal Calculi Using Squared Euclidean Distance Method  

OpenAIRE

—In this proposed Contour based Squared Euclidean Distance (CSED) segmentation method, initially the preprocessing techniques are applied to reduce the noise from the ultra sound kidney images. Then Squared Euclidean Distance (SED) is determined between the training image centroid values and the selected regions centroid values. In addition, the usage of ANFIS in supervised learning has made the technique more efficient than the previous techniques. Thus the ...

Tamiselvi, Dr P. R.

2013-01-01

287

Finding Colors  

Science.gov (United States)

In this chemistry challenge, learners combine acids and bases in a universal indicator to create five different colors. Using vinegar, washing soda, and Bogen universal indicator, the goal is to find combinations that create red, orange, yellow, green, and blue solutions. Background information explains a little about how acids and bases interact to affect the pH of a solution, and how the indicator changes color based on the pH. Safety notes are included.

Sciencenter

2014-08-27

288

Finding Ground  

OpenAIRE

My thesis called: ”Finding Ground” is an examination of my own artistic expression. Inspi-rations are memories of Finland and inner landscapes. A focus of my examinations lays in the historical background and the ground of my choices for material, technique and col-ours. The practical outcomes are woven objects of paper yarn und paintings in oil on can-vas. Both are speaking a different visual and sensual language, but talking about the same topic, the one of an end of searching and getti...

Rosenstock, Dorothea

2013-01-01

289

Oscar — Using Byte Pairs to Find File Type and Camera Make of Data Fragments  

Science.gov (United States)

Mapping out the contents of fragmented storage media is hard if the file system has been corrupted, especially as the current forensic tools rely on meta information to do their job. If it was possible to find all fragments belonging to a certain file type, it would also be possible to recover a lost file. Such a tool could for example be used in the hunt for child pornography. The Oscar method identifies the file type of data fragments based solely on statistics calculated from their structure. The method does not need any meta data to work. We have previously used the byte frequency distribution and the rate of change between consecutive bytes as basis for the statistics, as well as calculating the 2-gram frequency distribution to create a model of different file types. This paper present a variant of the 2-gram method, in that it uses a dynamic smoothing factor. In this way we take the amount of data used to create the centroid into consideration. A previous experiment on file type identification is extended with .mp3 files reaching a detection rate of 76% with a false positives rate of 0.4%. We also use the method to identify the camera make used to capture a .jpg picture from a fragment of the picture. The result shows that we can clearly separate a picture fragment coming from a Fuji or Olympus cameras from a fragment of a picture of the other camera makes used in our test.

Karresand, Martin; Shahmehri, Nahid

290

Robust seed selection algorithm for k-means type algorithms - Optimal centroids using high density object  

OpenAIRE

Selection of initial seeds greatly affects the quality of the clusters and in k-means typealgorithms. Most of the seed selection methods result different results in different independent runs. Wepropose a single, optimal, outlier insensitive seed selection algorithm for k-means type algorithms asextension to k-means++. The experimental results on synthetic, real and on microarray data setsdemonstrated that effectiveness of the new algorithm in producing the clustering results

Karteeka Pavan, K.; Allam Appa Rao; Dattatreya Rao, A. V.; Sridhar, G. R.

2011-01-01

291

Image motion compensation by area correlation and centroid tracking of solar surface features  

International Nuclear Information System (INIS)

An experimental solar correlation tracker was tested and evaluated on a ground-based solar magnetograph. Using sunspots as fixed targets, tracking error signals were derived by which the telescope image was stabilized against wind induced perturbations. Two methods of stabilization were investigated mechanical stabilization of the image by controlled two-axes motion of an active optical element in the telescope beam, and electronic stabilization by biasing of the electron scan in the recording camera. Both approaches have demonstrated telescope stability of about 0.6 arc sec under random perturbations which can cause the unstabilized image to move up to 120 arc sec at frequencies up to 30 Hz

292

Image motion compensation by area correlation and centroid tracking of solar surface features  

Science.gov (United States)

An experimental solar correlation tracker was tested and evaluated on a ground-based solar magnetograph. Using sunspots as fixed targets, tracking error signals were derived by which the telescope image was stabilized against wind induced perturbations. Two methods of stabilization were investigated; mechanical stabilization of the image by controlled two-axes motion of an active optical element in the telescope beam, and electronic stabilization by biasing of the electron scan in the recording camera. Both approaches have demonstrated telescope stability of about 0.6 arc sec under random perturbations which can cause the unstabilized image to move up to 120 arc sec at frequencies up to 30 Hz.

Nein, M. E.; Mcintosh, W. R.; Cumings, N. P.

1983-01-01

293

A comprehensive method to find RPO trajectory and incentive scheme for promotion of renewable energy in India with study of impact of RPO on tariff  

International Nuclear Information System (INIS)

Renewable Purchase Obligation (RPO) regime in India started in 2011 with the announcement of benchmark RPO (BRPO) of states for the Financial Year (FY) 2011 by respective State Electricity Regulatory Commissions (SERC), to promote Renewable Energy (RE). The report submitted to Forum of Regulators (FoR) in this regard has recommended uniform rate of increase of BRPO of states and studied the impact of RPO on tariff for FY 2011–2015. However, more rigorous analysis is needed for fixing BRPO in a scientific manner and for fair allocation of incentives to promote RE. This paper attempts to evaluate all states on a common platform to find BRPO, giving due weightage to the state-wise energy demand and RE generation, ensuring minimum change in BRPO of consecutive years and hence less impact of RPO on tariff. To encourage the states to align their actual RPO with BRPO, a financial incentive scheme is proposed giving due weightage to RE consumption, RE capacity addition and RPO compliance of the states. The methods are illustrated for the Indian states using real system data. A study of RPO's impact on electricity tariff of Indian states is also conducted and reported for FY 2011–2015, considering Renewable Energy Certificate (REC). - Author-Highlights: • Proposes a comprehensive method to find the BRPO of Indian states for promoting RE. • Minimum change in BRPO of consecutive years hence less impact of RPO on tariff. • Incentive scheme to encourage the states to align their actual RPO with BRPO. • Study of impact of RPO on tariff of Indian states is conducted

294

Experimental Test of Data Analysis Methods from Staggered Pair X-ray Beam Position Monitors at Bending Magnet Beamlines  

International Nuclear Information System (INIS)

Different methods have been proposed to calculate the vertical position of the photon beam centroid from the four blade currents of staggered pair X-ray beam position monitors (XBPMs) at bending magnet beamlines since they emerged about 15 years ago. The original difference-over-sum method introduced by Peatman and Holldack is still widely used, even though it has been proven to be rather inaccurate at large beam displacements. By systematically generating bumps in the electron orbit of the ANKA storage ring and comparing synchronized data from electron BPMs and XBPM blade currents, we have been able to show that the log-ratio method by S. F. Lin, B.G. Sun et al. is superior (meaning the characteristic being closer to linear) to the ratio method, which in turn is superior to the difference over sum method. These findings are supported by simulations of the XBPM response to changes of the beam centroid. The heuristic basis for each of the methods is investigated. The implications on using XBPM readings for orbit correction are discussed

295

Selected imaging methods to assess treatment results in ovarian cancer - ultrasound examination and computed tomography versus '' second-look '' laparotomy findings  

International Nuclear Information System (INIS)

The aim of the study was to establish the correlations between US and CT (analyzed separately and in combination) and relaparotomy findings both in relation to whole abdomen and pelvis examination and to particular anatomical localizations. A retrospective analysis of 102 ovarian cancer patients was performed in order to examine the accuracy of ultrasound examination (US) and computed tomography (CT) for the assessment of treatment results before second-look laparotomy and to evaluate the correlations between imaging and relaparotomy findings. Statistically significant correlation was found between US and CT (analyzed separately and in combination) and relaparotomy findings both in relation to whole abdomen and pelvis examination and to particular anatomical localizations. In subgroup 1 (54 patients after radical tumor excision, radical hysterectomy and partial omentectomy) CT results and combined CT/US results were statistically significantly more accurate than US results in relation to pathologic changes in the parenchymal organs and in the assessment of the presence of intraperitoneal fluid. In subgroup 2 (48 patients after debulking or exploratory surgery) CT and US/CT in combination were statistically significantly superior, as compared to US alone for examination of pelvic structures and combined CT/US - statistically superior when compared to US as far as parenchymal organs of the abdomen are concerned. In both subgroups there was no statistically significant ds there was no statistically significant difference between combined imaging results and CT alone for any anatomic location but combined CT/US results for the whole abdomen and pelvis were more accurate than the results of each modality performed separately - achieving statistical significance. US and CT performed before '' second-look '' laparotomy have high accuracy, which renders them important elements of the ovarian cancer treatment strategy. None of the evaluated methods appeared superior over the other when used separately although the CT results appeared slightly more accurate. A combination of both methods allows obtaining more accurate results than diagnostics based only on one of them. Nevertheless, it is impossible to eliminate '' second-look '' laparotomy from the procedures controlling the results of the ovarian cancer treatment due to the possibility of false negative imaging results. (author)

296

Hide and vanish: data sets where the most parsimonious tree is known but hard to find, and their implications for tree search methods.  

Science.gov (United States)

Three different types of data sets, for which the uniquely most parsimonious tree can be known exactly but is hard to find with heuristic tree search methods, are studied. Tree searches are complicated more by the shape of the tree landscape (i.e. the distribution of homoplasy on different trees) than by the sheer abundance of homoplasy or character conflict. Data sets of Type 1 are those constructed by Radel et al. (2013). Data sets of Type 2 present a very rugged landscape, with narrow peaks and valleys, but relatively low amounts of homoplasy. For such a tree landscape, subjecting the trees to TBR and saving suboptimal trees produces much better results when the sequence of clipping for the tree branches is randomized instead of fixed. An unexpected finding for data sets of Types 1 and 2 is that starting a search from a random tree instead of a random addition sequence Wagner tree may increase the probability that the search finds the most parsimonious tree; a small artificial example where these probabilities can be calculated exactly is presented. Data sets of Type 3, the most difficult data sets studied here, comprise only congruent characters, and a single island with only one most parsimonious tree. Even if there is a single island, missing entries create a very flat landscape which is difficult to traverse with tree search algorithms because the number of equally parsimonious trees that need to be saved and swapped to effectively move around the plateaus is too large. Minor modifications of the parameters of tree drifting, ratchet, and sectorial searches allow travelling around these plateaus much more efficiently than saving and swapping large numbers of equally parsimonious trees with TBR. For these data sets, two new related criteria for selecting taxon addition sequences in Wagner trees (the "selected" and "informative" addition sequences) produce much better results than the standard random or closest addition sequences. These new methods for Wagner trees and for moving around plateaus can be useful when analyzing phylogenomic data sets formed by concatenation of genes with uneven taxon representation ("sparse" supermatrices), which are likely to present a tree landscape with extensive plateaus. PMID:24952317

Goloboff, Pablo A

2014-10-01

297

Low-frequency centroid-moment-tensor inversion from superconducting-gravimeter data: The effect of seismic attenuation  

Science.gov (United States)

After the 2010 Maule and 2011 Tohoku earthquakes the spheroidal modes up to 1 mHz were clearly registered by the Global Geodynamic Project (GGP) network of superconducting gravimeters (SG). Fundamental parameters in synthetic calculations of the signals are the quality factors of the modes. We study the role of their uncertainties in the centroid-moment-tensor (CMT) inversions. First, we have inverted the SG data from selected GGP stations to jointly determine the quality factors of these normal modes and the three low-frequency CMT components, Mrr,(M??-M??)/2 and M??, that generate the observed SG signal. We have used several-days-long records to minimize the trade-off between the quality factors and the CMT but it was not eliminated completely. We have also inverted each record separately to get error estimates of the obtained parameters. Consequently, we have employed the GGP records of 60-h lengths for several published modal-quality-factor sets and inverted only the same three CMT components. The obtained CMT tensors are close to the solution from the joint Q-CMT inversion of longer records and resulting variability of the CMT components is smaller than differences among routine agency solutions. Reliable low-frequency CMT components can thus be obtained for any quality factors from the studied sets.

Zábranová, Eliška; Matyska, Ctirad

2014-10-01

298

Centroid Based Text Clustering  

OpenAIRE

Web mining is a burgeoning new field that attempts to glean meaningful information from natural language text. Web mining refers generally to the process of extracting interesting information and knowledge from unstructured text. Text clustering is one of the important Web mining functionalities. Text clustering is the task in which texts are classified into groups of similar objects based on their contents. Current research in the area of Web mining is tacklesproblems of text data representa...

Priti Maheshwari; Jitendra Agrawal

2010-01-01

299

Accelerated steered response power method for sound source localization via clustering search  

Science.gov (United States)

The steered response power-phase transform (SRP-PHAT) sound source localization algorithm is robust in a real environment. However, the large computation complexity limits the practical application of SRP-PHAT. For a microphone array, each location corresponds to a set of time differences of arrival (TDOAs), and this paper collects them into a TDOA vector. Since the TDOA vectors in the adjacent regions are similar, we present a fast algorithm based on clustering search to reduce the computation complexity of SRP-PHAT. In the training stage, the K-means or Iterative Self-Organizing Data Analysis Technique (ISODATA) clustering algorithm is used to find the centroid in each cluster with similar TDOA vectors. In the procedure of sound localization, the optimal cluster is found by comparing the steered response powers (SRPs) of all centroids. The SRPs of all candidate locations in the optimal cluster are compared to localize the sound source. Experiments both in simulation environments and real environments have been performed to compare the localization accuracy and computational load of the proposed method with those of the conventional SRP-PHAT algorithm. The results show that the proposed method is able to reduce the computational load drastically and maintains almost the same localization accuracy and robustness as those of the conventional SRP-PHAT algorithm. The difference in localization performance brought by different clustering algorithms used in the training stage is trivial.

Zhao, XiaoYan; Tang, Jie; Zhou, Lin; Wu, ZhenYang

2013-07-01

300

Rapid Centroid Moment Tensor (CMT) Inversion in 3D Earth Structure Model for Earthquakes in Southern California  

Science.gov (United States)

Accurate and rapid CMT inversion is important for seismic hazard analysis. We have developed an algorithm for very rapid CMT inversions in a 3D Earth structure model and applied it on small to medium-sized earthquakes recorded by the Southern California Seismic Network (SCSN). Our CMT inversion algorithm is an integral component of the scattering-integral (SI) method for full-3D waveform tomography (F3DT). In the SI method for F3DT, the sensitivity (Fréchet) kernels are constructed through the temporal convolution between the earthquake wavefield (EWF) and the receiver Green tensor (RGT), which is the wavefield generated by 3 orthogonal unit impulsive body forces acting at the receiver location. The RGTs are also the partial derivatives of the waveform with respect to the moment tensors. In this study, our RGTs are computed in a 3D seismic structure model for Southern California (CVM4SI1) using the finite-difference method, which allows us to account for 3D path effects in our source inversion. We used three component broadband waveforms below 0.2 Hz. An automated waveform-picking algorithm based on continuous wavelet transform is applied on observed waveforms to pick P, S and surface waves. A multi-scale grid-searching algorithm is then applied on the picked waveforms to find the optimal strike, dip and rake values that minimize the amplitude misfit and maximize the correlation coefficient. In general, our CMT solutions agree with solutions inverted using other methods and provide better fit to the observed waveforms.

Chen, P.; Lee, E.; Jordan, T. H.; Maechling, P. J.

2009-12-01

301

Combined radioimmunoassay of 17-alpha-hydroxyprogesterone and 11-desoxycortisol, and of dehydroepiandrosterone-sulphate: Methods and some novel clinical findings  

International Nuclear Information System (INIS)

The radioimmunoassay (RIA) methods for determining 17-alpha-hydroxyprogesterone (17HOP), 11-desoxycortisol (Cpd.-S), and dehydroepiandrosterone-sulphate, are reported. The plasma levels of these hormones were measured in a series of 15 diagnostic groups including adrenal diseases, fertility-related problems and human growth hormone (HGH) deficiency states. The relations of DHEA-S and growth hormone were studied in a group of children with growth retardation who presented an absent response to HGH stimulation tests. The DHEA-S level found in these patients was significantly lower than that of their age-matched controls. Furthermore, in an etiologically different entity, i.e. head-injury patients, similar findings were also made. In a single case with HGH deficiency due to antibodies against HGH, DHEA-S levels were not detectable. It is suggested that the determination of DHEA-S plasma levels can provide further insight into the classification of patients with fertility-related problems. Furthermore, it appears that DHEA-S can be taken as an indicator for the availability of bioactive human growth hormone. The various forms of congenital adrenal hyperplasia (CAH) can be successfully screened and detected by the determination of the plasma levels of 17-alpha-hydroxyprogesterone (17HOP), of 11-desoxycortisol (Cpd.-S), and of dehydroepiandrosterone-sulphate (DHEA-S). These tests are also relevant in the investigation of patients with hirsutism, hyperandrogenism, and amenorth hirsutism, hyperandrogenism, and amenorrhea. RIA procedures for the measurement of these hormones are described and new clinical data on DHEA-S are presented in relation to fertility problems both in men and women, such as oligozoospermia, oligomenorrhea and aspermia and, in cases of human growth hormone (HGH), deficiency states such as retarded growth, head-injury patients and, in one case, HGH deficiency due to antibodies directed against HGH. The relations between normo- and hyperprolactinaemia and DHEA-S are also examined

302

H.U.B city steps: methods and early findings from a community-based participatory research trial to reduce blood pressure among african americans  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Community-based participatory research (CBPR has been recognized as an important approach to develop and execute health interventions among marginalized populations, and a key strategy to translate research into practice to help reduce health disparities. Despite growing interest in the CBPR approach, CBPR initiatives rarely use experimental or other rigorous research designs to evaluate health outcomes. This behavioral study describes the conceptual frameworks, methods, and early findings related to the reach, adoption, implementation, and effectiveness on primary blood pressure outcomes. Methods The CBPR, social support, and motivational interviewing frameworks are applied to test treatment effects of a two-phased CBPR walking intervention, including a 6-month active intervention quasi experimental phase and 12-month maintenance randomized controlled trial phase to test dose effects of motivational interviewing. A community advisory board helped develop and execute the culturally-appropriate intervention components which included social support walking groups led by peer coaches, pedometer diary self-monitoring, monthly diet and physical activity education sessions, and individualized motivational interviewing sessions. Although the study is on-going, three month data is available and reported. Analyses include descriptive statistics and paired t tests. Results Of 269 enrolled participants, most were African American (94% females (85% with a mean age of 43.8 (SD = 12.1 years. Across the 3 months, 90% of all possible pedometer diaries were submitted. Attendance at the monthly education sessions was approximately 33%. At the 3-month follow-up 227 (84% participants were retained. From baseline to 3-months, systolic BP [126.0 (SD = 19.1 to 120.3 (SD = 17.9 mmHg; p Conclusions This CBPR study highlights implementation factors and signifies the community's active participation in the development and execution of this study. Reach and representativeness of enrolled participants are discussed. Adherence to pedometer diary self-monitoring was better than education session participation. Significant decreases in the primary blood pressure outcomes demonstrate early effectiveness. Importantly, future analyses will evaluate long-term effectiveness of this CBPR behavioral intervention on health outcomes, and help inform the translational capabilities of CBPR efforts.

Molaison Elaine

2011-06-01

303

An object-oriented C++ implementation of Davidson method for finding a few selected extreme eigenpairs of a large, sparse, real, symmetric matrix  

Science.gov (United States)

A C++ class named Davidson is presented for determining a few eigenpairs with lowest or alternatively highest values of a large, real, symmetric matrix. The algorithm described by Stathopoulos and Fischer is used. The exception mechanism is involved to report the errors. The class is written in ANSI C++, so it is fully portable. In addition a console program as well as a program with graphical user interface for Microsoft Windows is attached, which allow one to calculate the lowest eigenstates of time-independent Schrödinger equation for a given binding potential in one, two or three spatial dimensions. The package contains the classes providing often used potential functions (model atom potential, Coulomb potential, square well potential and Kramers-Henneberger well potential) as well as a possibility to use any potential stored in a file (then any dimensionality of the problem is allowed). The described code is the subject of M.Sc. thesis of T.D. prepared under the supervision of J.M. Program summaryProgram title: Davidson Catalogue identifier: ADZM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3 037 055 No. of bytes in distributed program, including test data, etc.: 20 002 609 Distribution format: tar.gz Programming language: C++ Computer: All Operating system: Any RAM: User's parameters dependent Word size: 32 and 64 bits Supplementary material: Test results for the 2D and 3D cases is available Classification: 4, 4.8 Nature of problem: Finding a few extreme eigenpairs of a real, symmetric, sparse matrix. Examples in quantum optics (interaction of matter with a laser field). Solution method: Davidson algorithm Running time: The test example included in the distribution package (1D matrix) takes approximately 30 minutes to run. 2D matrix calculations can take hours and 3D, days, to run.

Dziubak, Tomasz; Matulewski, Jacek

2007-10-01

304

Finding seed points for organ segmentation using example annotations  

Science.gov (United States)

Organ segmentation is important in diagnostic medicine to make current decision-support tools more effective and efficient. Performing it automatically can save time and labor. In this paper, a method to perform automatic identification of seed points for the segmentation of organs in three-dimensional (3D) non-annotated, full- body magnetic resonance (MR) and computed tomography (CT) volumes is presented. It uses 3D MR and CT acquisitions along with corresponding organ annotations from the Visual Concept Extraction Challenge in Radiology (VISCERAL) banchmark. A training MR or CT volume is first registered affinely with a carefully-chosen reference volume. The registration transform obtained is then used to warp the annotations accompanying that training volume. The process is repeated for several other training volumes. For each organ of interest, an overlap volume is created by merging the warped training annotations corresponding to it. Next, a 3D probability map for organ location on the reference volume is derived from each overlap volume. The centroid of each probability map is determined and it represents a suitable seed point for segmentation of each organ. Afterwards, the reference volume can be affinely mapped onto any non-annotated volume and the mapping applied to the pre-computed volume containing the centroid and the probability distribution for an organ of interest. Segmentation on the non-annotated volume may then be started using existing region-growing segmentation algorithms with the warped centroid as the seed point and the warped probability distribution as an aid to the stopping criterion. The approach yields very promising results.

Joyseeree, Ranveer; Müller, Henning

2014-03-01

305

Aplicação do delineamento simplex-centroide no estudo da cinética da oxidação de biodiesel B100 em mistura com antioxidantes sintéticos The simplex-centroid design applied to study of the kinetics of the oxidation of B100 biodiesel in blend with synthetic antioxidants  

OpenAIRE

Antioxidants are an alternative to prevent or slow the degradation of the biofuel. In this study, it was evaluated the oxidative stability of B100 biodiesel from soybean oil in the presence of three commercial synthetic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ), pure or blended, from the experimental design of simplex-centroid mixture. The reaction order and rate constant were also calculated for all tests. The treatment con...

Dionísio Borsato; Luiz Henrique Dall'Antonia; Guedes, Carmen Lui?sa B.; Maia, Elaine Cristina R.; Heverson Renan de Freitas; Ivanira Moreira; Kelly Roberta Spacino

2010-01-01

306

Granulomatous mastitis: radiological findings  

International Nuclear Information System (INIS)

Purpose: To evaluate the radiological, ultrasonographic, and magnetic resonance imaging (MRI) findings of idiopathic granulomatous mastitis. Material and Methods: Between April 2002 and June 2005, the mammography, ultrasound, color Doppler ultrasound, non enhanced MR, and dynamic MR findings of nine patients with the preliminary clinical diagnosis of malignancy and the final diagnosis of granulomatous mastitis were evaluated. Results: On mammography, asymmetrical focal densities with no distinct margins, ill-defined masses with spiculated contours, and bilateral multiple ill-defined nodules were seen. On ultrasound, in four patients a discrete, heterogenous hypoechoic mass, in two patients multiple abscesses, in one patient bilateral multiple central hypo peripheral hyperechoic lesions, in two patients heterogeneous hypo- and hyperechoic areas together with parenchymal distortion, and in one patient irregular hypoechoic masses with tubular extensions and abscess cavities were seen. Five of the lesions were vascular on color Doppler ultrasound. On MR mammography, the most frequent finding was focal or diffuse asymmetrical signal intensity changes that were hypointense on T1W images and hyperintense on T2W images, without significant mass effect. Nodular lesions were also seen. On dynamic contrast-enhanced mammography, mass-like enhancement, ring-like enhancement, and nodular enhancement were seen. The time-intensity curves differed from patient to patient and from lesiered from patient to patient and from lesion to lesion. Conclusion: The imaging findings of idiopathic granulomatous mastitis have a wide spectrum, and they are inconclusive for differentiating malignant and benign lesions

307

A modified semi-supervised color image segmentation method  

OpenAIRE

The paper proposed a modified color image segmentation method basing on semi-supervised hidden Markov random fields (HMRF) with constraints. Making use of MeanShift algorithm to get supervision information and, cluster number and initial values for cluster centroids, color images can be segmented effectively with the method in this paper by K-Means algorithm. The experimental results are very encouraging.

Chai Fangyong; Wei Hongru

2012-01-01

308

Causation and methods of skull trepanation in the past from the point of view of the latest findings from the Czech territory.  

Czech Academy of Sciences Publication Activity Database

Ro?. 48, ?. 1 (2010), s. 19-32. ISSN 0323-1119 Institutional research plan: CEZ:AV0Z80020508 Keywords : paleopathology * trepanation * trepanation methods * cranial trauma * intracranial hematoma * La Tène period * Middle Ages * Central Europe Subject RIV: AC - Archeology, Anthropology, Ethnology

Likovský, Jakub; Malyková, Drahomíra; Brzobohatá, Hana; Stránská, Petra

2010-01-01

309

Finding Out Critical Points For Real-Time Path Planning  

Science.gov (United States)

Path planning for a mobile robot is a classic topic, but the path planning under real-time environment is a different issue. The system sources including sampling time, processing time, processes communicating time, and memory space are very limited for this type of application. This paper presents a method which abstracts the world representation from the sensory data and makes the decision as to which point will be a potentially critical point to span the world map by using incomplete knowledge about physical world and heuristic rule. Without any previous knowledge or map of the workspace, the robot will determine the world map by roving through the workspace. The computational complexity for building and searching such a map is not more than O( n2 ) The find-path problem is well-known in robotics. Given an object with an initial location and orientation, a goal location and orientation, and a set of obstacles located in space, the problem is to find a continuous path for the object from the initial position to the goal position which avoids collisions with obstacles along the way. There are a lot of methods to find a collision-free path in given environment. Techniques for solving this problem can be classified into three approaches: 1) the configuration space approach [1],[2],[3] which represents the polygonal obstacles by vertices in a graph. The idea is to determine those parts of the free space which a reference point of the moving object can occupy without colliding with any obstacles. A path is then found for the reference point through this truly free space. Dealing with rotations turns out to be a major difficulty with the approach, requiring complex geometric algorithms which are computationally expensive. 2) the direct representation of the free space using basic shape primitives such as convex polygons [4] and overlapping generalized cones [5]. 3) the combination of technique 1 and 2 [6] by which the space is divided into the primary convex region, overlap region and obstacle region, then obstacle boundaries with attribute values are represented by the vertices of the hypergraph. The primary convex region and overlap region are represented by hyperedges, the centroids of overlap form the critical points. The difficulty is generating segment graph and estimating of minimum path width. The all techniques mentioned above need previous knowledge about the world to make path planning and the computational cost is not low. They are not available in an unknow and uncertain environment. Due to limited system resources such as CPU time, memory size and knowledge about the special application in an intelligent system (such as mobile robot), it is necessary to use algorithms that provide the good decision which is feasible with the available resources in real time rather than the best answer that could be achieved in unlimited time with unlimited resources. A real-time path planner should meet following requirements: - Quickly abstract the representation of the world from the sensory data without any previous knowledge about the robot environment. - Easily update the world model to spell out the global-path map and to reflect changes in the robot environment. - Must make a decision of where the robot must go and which direction the range sensor should point to in real time with limited resources. The method presented here assumes that the data from range sensors has been processed by signal process unite. The path planner will guide the scan of range sensor, find critical points, make decision where the robot should go and which point is poten- tial critical point, generate the path map and monitor the robot moves to the given point. The program runs recursively until the goal is reached or the whole workspace is roved through.

Chen, Wei

1989-03-01

310

Assessment of prior learning in vocational education and training : Findings from a study about methods for assessing prior learning in preparation for vocational qualifications (VET)  

DEFF Research Database (Denmark)

The article deals about the results of a study of the assessment of prior learning among adult workers who want to obtain formal qualifications as skilled workers. The study contributes to developing methods for assessing prior learning including both the teachers’ ways of eliciting the students’ knowledge, skills and competences during the students’ performances and the methods that the teachers apply in order to assess the students’ prior learning in relation to the regulations of the current VET-program. In particular the study focuses on how to assess not only the students’ explicated knowledge and skills but also their competences, i.e. the way the students use their skills and knowledge to perform in practice. Based on a description of the assessment procedures the article discusses central issues in relation to the assessment of prior learning. The empirical data have been obtained in the VET programs for gastronomes respectively child-care assistants.

Aarkrog, Vibe; Wahlgren, Bjarne

311

Assessment of prior learning in vocational education and training : Finding from a study about methods for assessing prior learning in preparation for vocational Qualifications (VET)  

DEFF Research Database (Denmark)

The article deals about the results of a study of the assessment of prior learning among adult workers who want to obtain formal qualifications as skilled workers. The study contributes to developing methods for assessing prior learning including both the teachers’ ways of eliciting the students’ knowledge, skills and competences during the students’ performances and the methods that the teachers apply in order to assess the students’ prior learning in relation to the regulations of the current VET-program. In particular the study focuses on how to assess not only the students’ explicated knowledge and skills but also their competences, i.e. the way the students use their skills and knowledge to perform in practice. Based on a description of the assessment procedures the article discusses central issues in relation to the assessment of prior learning. The empirical data have been obtained in the VET programs for gastronomes respectively child-care assistants.

Wahlgren, Bjarne; Aarkrog, Vibe

312

Factors Influencing Choices for Colorectal Cancer Screening Among Previously Unscreened African and Caucasian Americans: Findings from a Triangulation Mixed Methods Investigation  

OpenAIRE

We investigated factors that influence choice of colorectal cancer (CRC) screening test and assessed the most- and least-preferred options among fecal occult blood testing (FOBT), flexible sigmoidoscopy, colonoscopy, and double contrast barium enema among adults with varied race, gender, and geographic region demographics. Mixed methods data collection consisted of 10 focus group interviews and a survey of the 93 focus group participants. Participants were ?50 years of age and reported not ...

Ruffin, Mack T.; Creswell, John W.; Jimbo, Masahito; Fetters, Michael D.

2009-01-01

313

A practical method of active case finding and epidemiological assessment: its origin and application in the leprosy control project in Indonesia.  

Science.gov (United States)

Random sample surveys in the past have revealed high estimated against low registered prevalences for leprosy in several parts of Indonesia. A pilot project showed that the problem of cases that had not yet been detected could not be solved without the active participation of the local authorities, who proved able to overcome the stigma and to convince potential patients to go for examination and treatment. The pilot project was based on the principle of what are called exploration surveys, which were introduced by Sitanala in Indonesia in 1931. The Indonesian government decided to reintroduce these surveys in 1977 under the name of chase or trace surveys. They are carried out within the framework of the leprosy workers' routine duties and no additional expenses are incurred. Since then, thousands of patients of all types and with long case histories have been detected and brought under treatment. Without this "push" it is fair to assume that many would never have sought treatment voluntarily. In view of the experience in Indonesia, one wonders whether leprosy can be eliminated without emphasizing the importance of active case finding, especially in areas in which the disease is still highly endemic. Chase surveys also provide rough information about the local leprosy situation. Although of great value, they are not, in high-endemic regions, an alternative to random sample surveys which reveal, besides a wealth of additional information, the possible unknown sources of infection. PMID:9465159

Louhenapessy, A A; Zuiderhoek, B

1997-12-01

314

MANAGEMENT CONTROL SYSTEM AND THE CASE OF CSR IN THE TUNISIAN INDUSTRIAL COMPANIES: WHAT FINDINGS BY THE METHOD OF STRUCTURAL EQUATION?  

Directory of Open Access Journals (Sweden)

Full Text Available This study aims to the behavior of management control; it is providing a model to the behavior of integration of social responsibility in the management control tools. This model was validated with 306 Tunisian companies in the industrial sector. Through a questionnaire, the data collected are processed using exploratory and confirmatory analysis by the methods of structural equations. The results revealed that the management control system in industrial Tunisia is facing economic responsibility. This is in response to emerging pressures of uncertainty related to the environment, and in enrolling a strategy of domination by cost. In addition, the management control system is designed as a guidance tool actions and behaviors.

Hichem Dkhili

2013-01-01

315

Servicemembers and veterans with major traumatic limb loss from Vietnam war and OIF/OEF conflicts: Survey methods, participants, and summary findings  

Directory of Open Access Journals (Sweden)

Full Text Available Care of veterans and servicemembers with major traumatic limb loss from combat theaters is one of the highest priorities of the Department of Veteran Affairs. We achieved a 62% response rate in our Survey for Prosthetic Use from 298 Vietnam war veterans and 283 servicemembers/veterans from Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF who sustained major traumatic limb loss. Participants reported their combat injuries; health status; quality of life; and prosthetic device use, function, rejection, and satisfaction. Despite the serious injuries experienced, health status was rated excellent, very good, or good by 70.7% of Vietnam war and 85.5% of OIF/OEF survey participants. However, many health issues persist for Vietnam war and OIF/OEF survey participants(respectively: phantom limb pain (72.2%/76.0%, chronic back pain (36.2%/42.1%, residual-limb pain (48.3%/62.9%, prosthesis-related skin problems (51.0%/58.0%, hearingloss (47.0%/47.0%, traumatic brain injury (3.4%/33.9%, depression (24.5%/24.0%, and posttraumatic stress disorder (37.6%/58.7%. Prosthetic devices are currently used by 78.2% of Vietnam war and 90.5% of OIF/OEF survey participants to improve function and mobility. On average, the annual rate for prosthetic device receipt is 10.7-fold higher for OIF/OEF than for Vietnam war survey participants. Findings from this cross-conflict survey identify many strengths in prosthetic rehabilitationfor those with limb loss and several areas for future attention.

Charles Maynard, PhD

2010-08-01

316

Application of Monte-Carlo method for finding of ionization and secondary emission coefficients and volt-ampere characteristics of Townsend discharge in hydrogen  

International Nuclear Information System (INIS)

The coefficients of ? secondary cathode emission for hydrogen is determined experimentally via calculation of the ionization numbers within the gaps by the Monte-Carlo method. In this case, one calculates the ionization frequencies, the Townsend ionization coefficients (demonstrating their nonlocality), the electron drift rate, the probability of the emitted electron return to the cathode. The calculated parameters are in line with the measured ones. One studied the gaps with pd=0.37-17 Torrxcm. It is shown that just for pd within the Paschen curve minimum vicinity the observed negative differential resistance of the Townsend discharge may be associated with the reduction of the probability of the electron return to the cathode at E/N increase

317

Measurement method for finding gas adsorption equilibrium isotherms by employing a gas chromatograph and using its integrator in a new way  

Science.gov (United States)

A method for measuring the adsorption ability of zeolites has been developed. The adsorption can be accurately measured over a wide range of pressures and temperatures. The range usually covered is partial pressures ranging from 0.2 to 20 bar (a) and temperatures from 10 to 50 °C. However, it may be extended to 0.1-25 bar (a) and -40-80°C. When a partial pressure below 2 bar (a) is to be used, the gas is diluted with helium. The method is built around a gas chromatograph (GC) equipped with a thermal conductivity detector (TCD) and having a programming and peak integrating unit. It also has an option using liquid nitrogen to allow work below ambient temperature. The GC has been modified with two special columns to be used alternately for purging with helium and as test chamber for the measurements. It is also equipped with a separate external flow and pressure-handling unit. The GC is used, not as a chromatograph, but instead to integrate suitably interrupted breakthrough curves. The primary measured data are evaluated using a program written in BASIC, which separates the part of the primary measured results that originates from the adsorption from the part that is induced by the measuring equipment. Using a calibration file that can easily be updated from within the program, this separation has achieved a high degree of accuracy. Using the adsorption data from these measurements, Langmuir-type isotherm equations are fitted, which accurately represent the adsorption of the tested gas both with respect to pressure and to temperature. It has been found that adsorption data measured in this way can achieve a standard deviation between measured and calculated data that typically varies around 1% over the whole measured range. In order to do this, however, in the case of nitrogen adsorption the sum of two Langmuir isotherms has to be used. This is not needed with oxygen or argon adsorption.

Eriksson, Tore; Sylwan, Christopher

2005-04-01

318

How possible is the development of an operational psychometric method to assess the presence of the 5-HTTLPR s allele? Equivocal preliminary findings  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Objective The s allele of the 5-hydroxytryptamine transporter-linked promoter region (5-HTTLPR polymorphism of the serotonin transporter gene has been found to be associated with neuroticism-related traits, affective temperaments and response to selective serotonin reuptake inhibitor (SSRI treatment. The aim of the current study was to develop a psychometric tool that could at least partially substitute for laboratory testing and could predict the presence of the s allele. Methods The study included 138 women of Caucasian origin, mean 32.20 ± 1.02 years old. All subjects completed the Hungarian standardised version of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A instrument and were genotyped for 5-HTTLPR using PCR. The statistical analysis included the calculation of the Index of Discrimination (D, Discriminant Function Analysis, creation of scales on the basis of the above and then item analysis and calculation of sensitivity and specificity. Results Four indices were eventually developed, but their psychometric properties were relatively poor and their joint application did not improve the outcome. Conclusions We could not create a scale that predicts the 5-HTTLPR genotype with sufficient sensitivity and specificity, therefore we could not substitute a psychometric scale for laboratory genetic testing in predicting genotype, and also possibly affective disorder characterisation and treatment.

Laszik Andras

2010-05-01

319

Finding Cryptography in Object Code  

Energy Technology Data Exchange (ETDEWEB)

Finding and identifying Cryptography is a growing concern in the malware analysis community. In this paper, a heuristic method for determining the likelihood that a given function contains a cryptographic algorithm is discussed and the results of applying this method in various environments is shown. The algorithm is based on frequency analysis of opcodes that make up each function within a binary.

Jason L. Wright

2008-10-01

320

Radiological findings in angiofibroma  

International Nuclear Information System (INIS)

Surgery after pre-operative embolization has become the main treatment modality in angiofibroma therapy. As surgical planning is based on precise pre-operative tumour evaluation, knowledge of the characteristic growth patterns is of great interest. Analysis of tumour extension and blood supply, as well as methods of controlling intra-operative bleeding, help in determining the appropriate surgical approach. Though benign, angiofibroma demonstrates a locally aggressive nature. This fibrovascular tumour is characterised by typical radiological findings and by predictable growth patterns. The tumour extension and blood supply can be accurately determined by CT, MR imaging and angiography. With classic radiological findings, no pre-operative biopsy is necessary in most angiofibromas. Advances in radiological imaging have contributed to improved surgical planning and tumour resection. The surgeon is able to select the least traumatic approach with secure haemostatic control, which is also critical for avoiding the disturbance of facial skeletal growth in this group of young patients. Embolization, pre-operative autologous donation and the cell saver system for immediate retransfusion of the collected blood after filtration, are important tools for dealing with blood loss in angiofibroma surgery as they minimize homologous blood transfusion

321

Abdominal aspergillosis: CT findings  

Energy Technology Data Exchange (ETDEWEB)

Objective: In order to retrospectively evaluate the CT findings of abdominal aspergillosis in immunocompromised patients. Materials and methods: CT scans were reviewed with regard to the sites, number, morphologic appearance, attenuation, and the contrast enhancement patterns of the lesions in six patients (5 women, 1 man; mean age, 43.4 years; range, 23-59 years) with pathologically proved abdominal aspergillosis by two gastrointestinal radiologists in consensus. Medical records were also reviewed to determine each patient's clinical status and outcome. Results: All patients were immunocompromised state: 4 patients received immunosuppressive therapy for solid organ transplantation and 2 patients received chemotherapy for acute myeloid leukemia. Aspergillosis involved blood vessels (n = 3), liver (n = 2), spleen (n = 2), gastrointestinal tract (n = 2), native kidney (n = 1), transplanted kidney (n = 1), peritoneum (n = 1), and retroperitoneum (n = 1). CT demonstrated solid organ or bowel infarction or perforation secondary to vascular thrombosis or pseudoaneurysm, multiple low-attenuating lesions of solid organs presenting as abscesses, concentric bowel wall thickening mimicking typhlitis, or diffuse or nodular infiltration of the peritoneum and retroperitoneum. Conclusion: Familiarity with findings commonly presenting as angioinvasive features or abscesses on CT, may facilitate the diagnosis of rare and fatal abdominal aspergillosis.

Yeom, Suk Keu, E-mail: pagoda20@hanmail.net [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of); Kim, Hye Jin, E-mail: kimhyejin@amc.seoul.kr [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of); Byun, Jae Ho, E-mail: jhbyun@amc.seoul.kr [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of); Kim, Ah Young, E-mail: aykim@amc.seoul.kr [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of); Lee, Moon-Gyu, E-mail: mglee@amc.seoul.kr [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of); Ha, Hyun Kwon, E-mail: hkha@amc.seoul.kr [Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap2-dong, Songpa-gu, Seoul, 138-736 (Korea, Republic of)

2011-03-15

322

A Two-Stage Method for Scientific Papers Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available A considerable amount of research is being conducted by many people (researchers, graduate students, professors etc everyday. Finding information about aspecific topic is one of the most time consuming activities of those people. People doing research have to search, read and analyze multiple research papers, e-books and other documents and then determine what they contain and discover knowledge from them. Many available resources are in the form of unstructured text format of long text pages which require long time to read and analyze. In this paper we propose a two-stage method for scientific paper analysis. The method uses information extraction to extract the main idea key sentences (mainly needed by the most readers from the paper and the extracted paper’s information is then organized in a structured format and grouped in different clusters according to their topics using a multi-word based clustering method. The proposed method combines different features in paper’s topics extraction and uses multi-word matching feature in selection of initial centroids for clustering. The proposed method can help readers to access and analyze multiple research papers documents timely and efficiently. Conducted experiments show the effectiveness and usefulness of our proposed approach.

Damien Hanyurwimfura

2014-10-01

323

Radiologic findings of sacroiliitis : emphasis on MR findings  

Energy Technology Data Exchange (ETDEWEB)

To compare the characteristic MR findings of infectious sacroiliitis (IS) and ankylosing spondylitis (AS). We retrospectively reviewed MR findings in eight patients with IS (pyogenic in six, tuberculosis in two) confirmed by culture and clinical follow-up, and in six with AS by HLA-B27 typing. AA control group of 13 asymptomatic volunteers was formed, and they underwent MRI Findings were analysed for morphology, degree of bone erosion, and adjacent soft tissue change. CT findings of AS in four patients and IS in four were also compared to MR findings. MR characteristics of IS included unilaterality (100%), abnormal cartilage signal intensity (100%), bone marrow change (100%), contrast enhancement (100%), erosion (63%), and soft tissue change (63%). MR findings of AS showed bilaterality (67%), abnormal cartilage signal intensity (80%), bone marrow change (80%), erosion (80%), contrast enhancement (44%) and soft tissue change (10%). CT scan showed bony sclerosis and erosion (86%), and abnormal joint space (71%). MR findings of sacroiliitis were loss of thin zone of a cartilage and erosions on T1-weighted image, and increased signal intensity on T2-weighted image. MRI is regarded as a useful diagnostic method where conventional diagnosis is difficult, and is able to image cartilage abnormalities directly and noninvasively. Significant differences in MR findings between IS and AS were not noted, however.

Yang, Ik; Park, Hai Jung; Lee, Yul; Chung, Soo Young; Park, Jong Ho [Hallym Univ. College of Medicine, Chunchon (Korea, Republic of)

1997-05-01

324

MRI finding of hemangioblastomas  

International Nuclear Information System (INIS)

The purpose of this study is to evaluate the findings of magnetic resonance imaging (MRI) of posterior fossa hemanangioblastoma and usefulness of contrast enhancement with Gd-DTPA. Seven patients with posterior fossa hemangioblastoma were studied with both pre- and post-enhanced MRI. The MR images were reviewed regarding the location, size, signal intensities of cysts and mural nodules, and their contrast enhancement pattern. Five tumors were located in cerebellar hemisphere, one in vermis, and one in posterior part of medulla. One patient with von Hippel-Lindau disease had a medullary hemangioblastoma with multiple pancreatic cysts. In 6 cases, the major portion of the tumor was cysts and had small mulkal nodules. The solid portion was relatively lange in one cases, cemprising half of the tumor cysts were oval shaped and their sized were 3-6.7 cm in diameter. In five cases(71%), septations were noted within the cysts. Cysts were isointense or slightly hyperintense on T1-weighted image and hyperintense on T2- weighted image compared with cerebrospinal fluid. Mural nodules were oval or rounded radiotherapy had better prognosis than those treated with radiotherapy alwas 0.5-2.5 cm in diameter. Mural nodules were isointense to gray matter. They were detected in five cases on T1-weighted images and one case on T2-weighted images. In two cases, vascular signal void area was noted in mural nodules. On contrast-enhanced T1-weighted images, all mural nodules were intensely enmages, all mural nodules were intensely enhanced. MRI provide to be a good diagnostic method to detect and characterize posterior fossa hemangioblastoma. The most common finding is Cystic posterior fossa lesion with enhancing mural nodule. Contrast enhancement is essential for specific diagnosis

325

MRI finding of hemangioblastomas  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to evaluate the findings of magnetic resonance imaging (MRI) of posterior fossa hemanangioblastoma and usefulness of contrast enhancement with Gd-DTPA. Seven patients with posterior fossa hemangioblastoma were studied with both pre- and post-enhanced MRI. The MR images were reviewed regarding the location, size, signal intensities of cysts and mural nodules, and their contrast enhancement pattern. Five tumors were located in cerebellar hemisphere, one in vermis, and one in posterior part of medulla. One patient with von Hippel-Lindau disease had a medullary hemangioblastoma with multiple pancreatic cysts. In 6 cases, the major portion of the tumor was cysts and had small mulkal nodules. The solid portion was relatively lange in one cases, cemprising half of the tumor cysts were oval shaped and their sized were 3-6.7 cm in diameter. In five cases(71%), septations were noted within the cysts. Cysts were isointense or slightly hyperintense on T1-weighted image and hyperintense on T2- weighted image compared with cerebrospinal fluid. Mural nodules were oval or rounded radiotherapy had better prognosis than those treated with radiotherapy alwas 0.5-2.5 cm in diameter. Mural nodules were isointense to gray matter. They were detected in five cases on T1-weighted images and one case on T2-weighted images. In two cases, vascular signal void area was noted in mural nodules. On contrast-enhanced T1-weighted images, all mural nodules were intensely enhanced. MRI provide to be a good diagnostic method to detect and characterize posterior fossa hemangioblastoma. The most common finding is Cystic posterior fossa lesion with enhancing mural nodule. Contrast enhancement is essential for specific diagnosis.

Park, Seung Cheol; Oh, Min Cheol; Chung, Hwan Hoon; Seol, Hye Young; Lee, Nam Joon; Kim, Jung Hyuk [Korea University College of Medicine, Seoul (Korea, Republic of)

1994-05-15

326

Find a Dermatologist  

Science.gov (United States)

Find a Dermatologist A dermatologist is a doctor who specializes in treating conditions that affect the skin, hair, and ... in reliance on the information contained therein. Find a free SPOT me? skin cancer screening. State: AL ...

327

Find a Doctor  

Science.gov (United States)

Find a Doctor Finding a doctor with special training in movement disorders can make a big difference in your treatment. The DMRF maintains a directory of physicians and healthcare providers with experience ...

328

Modified nonlinearities distribution Homotopy Perturbation method as a tool to find power series solutions to ordinary differential equations / Método modificado de Perturbación Homotópica con distribución de no linealidades como herramienta para encontrar soluciones de ecuaciones diferenciales ordinarias  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish En este artículo, el método modificado de perturbación homotópica con distribución de no linealidades (MNDHPM) es utilizado para encontrar soluciones en series de potencias de ecuaciones diferenciales ordinarias, tanto lineales como no lineales. Se verá que el método es particularmente relevante en [...] algunos casos de ecuaciones con coeficientes no polinomiales e inhomogéneas con términos no homogéneos no polinomiales. Abstract in english In this article, modified non-linearities distribution homotopy perturbation method (MNDHPM) is used in order to find power series solutions to ordinary differential equations with initial conditions, both linear and nonlinear. We will see that the method is particularly relevant in some cases of eq [...] uations with non-polynomial coefficients and inhomogeneous non-polynomial terms.

U., Filobello-Nino; H., Vázquez-Leal; Y., Khan; D., Pereyra-Díaz; A., Pérez-Sesma; A., Díaz-Sánchez; V.M., Jiménez-Fernández; A., Herrera-May; R., López-Martínez; J., Sanchez-Orea.

329

Multiresponse optimisation on biodiesel obtained through a ternary mixture of vegetable oil and animal fat: Simplex-centroid mixture design application  

International Nuclear Information System (INIS)

Highlights: • Mixture experimental design was used which allowed evaluating various responses. • Predictive equation was presented that allows verifying the behavior of the mixtures. • The results depicted that the obtained biodiesel dispensed the use of any additives. - Abstract: The quality of biodiesel is a determining factor in its commercialisation, and parameters such as the Cold Filter Plugging Point (CFPP) and Induction Period (IP) determine its operability in engines on cold days and storage time, respectively. These factors are important in characterisation of the final product. A B100 biodiesel formulation was developed using a multiresponse optimisation, for which the CFPP and cost were minimised, and the IP and yield were maximised. The experiments were carried out according to a simplex-centroid mixture design using soybean oil, beef tallow, and poultry fat. The optimum formulation consisted of 50% soybean oil, 20% beef tallow, and 30% poultry fat and had CFPP values of 1.92 °C, raw material costs of US$ 903.87 ton?1, an IP of 8.28 h, and a yield of 95.68%. Validation was performed in triplicate and the t-test indicated that there were no difference between the estimated and experimental values for none of the dependent variables, thus indicating efficiency of the joint optimisation in the biodiesel production process that met the criteria for CFPP and IP, as well as high yield and low cost

330

Performance analysis of k-means with different initialization methods for high dimensional data  

Directory of Open Access Journals (Sweden)

Full Text Available Developing effective clustering method for high dimensional dataset is a challengingproblem due to the curse of dimensionality. Among all the partition based clusteringalgorithms, k-means is one of the most well known methods to partition a dataset intogroups of patterns. However, the k-means method converges to one of many localminima. And it is known that, the final result depends on the initial starting points(means. Many methods have been proposed to improve the performance of k-meansalgorithm. In this paper, we have analyzed the performance of our proposed method withthe existing works. In our proposed method, we have used Principal Component Analysis(PCA for dimension reduction and to find the initial centroid for k-means. Next we haveused heuristics approach to reduce the number of distance calculation to assign the datapoint to cluster. By comparing the results on iris data set, it was found that the resultsobtained by the proposed method are more effective than the existing method.

Saravanan

2010-10-01

331

Aplicação do delineamento simplex-centroide no estudo da cinética da oxidação de biodiesel B100 em mistura com antioxidantes sintéticos / The simplex-centroid design applied to study of the kinetics of the oxidation of B100 biodiesel in blend with synthetic antioxidants  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english Antioxidants are an alternative to prevent or slow the degradation of the biofuel. In this study, it was evaluated the oxidative stability of B100 biodiesel from soybean oil in the presence of three commercial synthetic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and [...] tert-butylhydroquinone (TBHQ), pure or blended, from the experimental design of simplex-centroid mixture. The reaction order and rate constant were also calculated for all tests. The treatment containing pure TBHQ proved to be the most effective, proven by design, the optimum mix obtained and the rate constant. Binary and ternary mixtures containing TBHQ also showed appreciable antioxidant effect.

332

MEMS AO for Planet Finding  

Science.gov (United States)

This slide presentation reviews a method for planet finding using microelectromechanical systems (MEMS) Adaptive Optics (AO). The use of a deformable mirror (DM) is described as a part of the instrument that was designed with a nulling interferometer. The strategy that is used is described in detail.

Rao, Shanti; Wallace, J. Kent; Shao, Mike; Schmidtlin, Edouard; Levine, B. Martin; Samuele, Rocco; Lane, Benjamin; Chakrabarti, Supriya; Cook, Timothy; Hicks, Brian; Jung, Paul

2008-01-01

333

Find a Plume, Find a Vent  

Science.gov (United States)

This classroom activity gives students an appreciation for the difficulties deep sea researchers must face in order to find hydrothermal vents. Working in small groups, students can complete this Web investigation in a single class period. The printable handout includes a series of inquiry-based questions that prompt students to use what they already know about mid-ocean ridges to hypothesize about how scientists locate deep sea vents, detailed directions for a Web research project that takes them on a virtual deep sea journey investigating hydrothermal vents, and a worksheet that helps students apply their building knowledge to locate a vent in the northern Pacific Ocean.

334

[Explosive "Roman find"].  

Science.gov (United States)

A case of a 40-year-old hobby archeologist is presented who searched for remains from Roman times. After finding an oblong, cylindrical object, he opened it with a saw to examine it, which triggered an explosion killing the man. The technical investigation of the remains showed that the find was actually a grenade from the 2nd World War. The autopsy findings and the results of the criminological investigation are presented. PMID:16529179

Stiel, Michael; Dettmeyer, Reinhard; Madea, Burkhard

2006-01-01

335

Leiomyosarcoma: computed tomographic findings  

International Nuclear Information System (INIS)

The computed tomographic (CT) findings in 118 patients with the diagnosis of leiomyosarcoma were reviewed. The tumor masses visualized in these patients were often quite large; extensive necrotic or cystic change was a frequent finding. Calcification was not observed in these tumors. The liver was the most common site of metastasis in these patients, with marked necrosis of the liver lesions a common finding. Other manifestations of tumor spread included pulmonary metastases, mesenteric or omental metastases, retroperitoneal lymphadenopathy, soft-tissue metastases, bone metastases, splenic metastases, and ascites. Although the CT appearance of leiomyosarcoma is not specific, these findings, when present, suggest consideration of this diagnosis

336

Thoracic textilomas: CT findings  

International Nuclear Information System (INIS)

Objective: the aim of this study was to analyze chest CT scans of patients with thoracic textiloma. Methods: this was a retrospective study of 16 patients (11 men and 5 women) with surgically confirmed thoracic textiloma. The chest CT scans of those patients were evaluated by two independent observers, and discordant results were resolved by consensus. Results: the majority (62.5%) of the textilomas were caused by previous heart surgery. The most common symptoms were chest pain (in 68.75%) and cough (in 56.25%). In all cases, the main tomographic finding was a mass with regular contours and borders that were well-defined or partially defined. Half of the textilomas occurred in the right hemithorax and half occurred in the left. The majority (56.25%) were located in the lower third of the lung. The diameter of the mass was ? 10 cm in 10 cases (62.5%) and > 10 cm in the remaining 6 cases (37.5%). Most (81.25%) of the textilomas were heterogeneous in density, with signs of calcification, gas, radiopaque marker, or sponge-like material. Peripheral expansion of the mass was observed in 12 (92.3%) of the 13 patients in whom a contrast agent was used. Intraoperatively, pleural involvement was observed in 14 cases (87.5%) and pericardial involvement was observed in 2 (12.5%). Conclusions: it is important to recognize the main tomographic aspects of thoracic textilomas in order to include this possibility in the differential diagnosis of chest pain and cough in patients with a history of heart or thoracic surgery, thus promoting the early identification and treatment of this postoperative complication. (author)

337

Generalized Centroid Estimators in Bioinformatics  

OpenAIRE

In a number of estimation problems in bioinformatics, accuracy measures of the target problem are usually given, and it is important to design estimators that are suitable to those accuracy measures. However, there is often a discrepancy between an employed estimator and a given accuracy measure of the problem. In this study, we introduce a general class of efficient estimators for estimation problems on high-dimensional binary spaces, which representmany fundamental problem...

Hamada, Michiaki; Kiryu, Hisanori; Iwasaki, Wataru; Asai, Kiyoshi

2013-01-01

338

A novel method of spectrum stabilization  

International Nuclear Information System (INIS)

A new type of spectrum stabilizer for a scintillation spectrometer is described. A pulse light source DM 160 is used to introduce an artificial peak in the spectrum at a convenient energy. The centroid of pulse spectrum corresponding to artificial peak is compared with that of suitable reference pulses obtained from the DM 160 driver circuit. Any drift in artificial peak produces a d.c. voltage at the output of centroid comparator and this voltage is used to control the gain of variable gain amplifier to counter the drift. With suitable adjustment the effect of any variation in pulse height of DM 160 driving pulse can be compensated so that the spectrometer gain is independent of any variation, drift etc. in the height of pulse driving DM 160 tube. This circuit is simple and gives improved performance compared to 2 channel method of obtaining the control voltage for variable gain amplifier. (author)

339

Radiologic findings of anthracofibrosis  

International Nuclear Information System (INIS)

To evaluate the CT findings of bronchial anthracofibrosis. Fourteen patients with bronchoscopically confirmed anthracofibrosis were involved in this study. CT findings (n=3D12) were retrospectively analysed; the pattern, distri-bution and extent of bronchial and parenchymal abnormalities and additional findings such as mediastinal lymphadenopathy and pleural effusion were assessed. Age, sex, and occupational and disease history were history were also reviewed. Patients were aged between 63 and 95 (mean, 71.3) years, and ten were female. Only one patient had an occupational history, but four had a history of pulmonary tuberculosis. Frequent radiologic findings were bronchial wall thickening(n=3D6), atelectasis(n=3D8), mediastinal lymphad-enopathy(n=3D7) and mass(n=3D4). Other accompanying findings were bronchial wall calcification(n=3D3), consolidation(n=3D2) and pleural effusion(n=3D2). Right upper (n=3D7) and right middle lobe(n=3D7) were the most commonly involved sites, and multifocal involvement (n=3D7) was frequent. Bronchial wall thickening, atelectasis and mediastinal lymphadenopathy were characteristic CT findings of anthracofibrosis. When such findings are noted in older or aged female patients, anthracofibrosis should be included in the differential diagnosis

340

Find a Dentist  

Science.gov (United States)

... information you need from the Academy of General Dentistry Saturday, April 18, 2015 About | Contact Find an ... more. Disclaimer of Liabilities The Academy of General Dentistry's (AGD) Web site provides a listing of members ...

341

Find an Interventional Radiologist  

Science.gov (United States)

... Uterine fibroid embolization (UFE) Varicose veins Vascular screening Venous disease Women's health Last name: (optional) Institution: (optional) Search ... Trauma Uterine Fibroids Varicoceles & Male Infertility Varicose Veins Venous access ... Bibliographies Radiation Safety Find an Interventional ...

342

Videonystagmographic Finding in Meniere's Patients  

Directory of Open Access Journals (Sweden)

Full Text Available Back ground and Objective: Vertigo is the most common complaints of patients who refer to physician and menier's disease is one of the most common causes of it. Diagnose of menier's disease depend on clinical finding. Vestibular tests are affect the treatment method and prognosis of disease, to differentiate it from other causes of vertigo as well. In this study we performed evaluation and analysis of videonystagmoghrapy (VNG finding in menier's disease.Subjects and Methods: Total 61 patients with menier’s disease referred to ENT outpatient department of Imam Khomeini and Apadana Hospitals were evaluated with VNG and Sacade, Smooth pursuit, Optokinetic, Positional and caloric tests. SPSS 16 software for data analysis was used.Results: Directional preponderance was found in 11.44%, unilateral weakness in 39.33% and Latency of sacad in 42.6% with abnormal results.Conclusion: There was no significant correlation between severity of vertigo, severity of hearing loss, duration of Disease and videonysta- gmography finding. Unilateral weakness was most important finding in this study. Sci Med J 2011; 10(3:289-293

Saki Nasser

2011-07-01

343

Study of nuclear giant resonances using a Fermi-liquid method  

CERN Document Server

The nuclear giant resonances are studied by using a Fermi-liquid method, and the nuclear collective excitation energies of different values of $l$ are obtained, which are fitted with the centroid energies of the giant resonances of spherical nuclei, respectively. In addition, the relation between the isovector giant resonance and the corresponding isoscalar giant resonance is discussed.

Sun, Bao-Xi

2012-01-01

344

A comparison of methods for calculating population exposure estimates of daily weather for health research  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background To explain the possible effects of exposure to weather conditions on population health outcomes, weather data need to be calculated at a level in space and time that is appropriate for the health data. There are various ways of estimating exposure values from raw data collected at weather stations but the rationale for using one technique rather than another; the significance of the difference in the values obtained; and the effect these have on a research question are factors often not explicitly considered. In this study we compare different techniques for allocating weather data observations to small geographical areas and different options for weighting averages of these observations when calculating estimates of daily precipitation and temperature for Australian Postal Areas. Options that weight observations based on distance from population centroids and population size are more computationally intensive but give estimates that conceptually are more closely related to the experience of the population. Results Options based on values derived from sites internal to postal areas, or from nearest neighbour sites – that is, using proximity polygons around weather stations intersected with postal areas – tended to include fewer stations' observations in their estimates, and missing values were common. Options based on observations from stations within 50 kilometres radius of centroids and weighting of data by distance from centroids gave more complete estimates. Using the geographic centroid of the postal area gave estimates that differed slightly from the population weighted centroids and the population weighted average of sub-unit estimates. Conclusion To calculate daily weather exposure values for analysis of health outcome data for small areas, the use of data from weather stations internal to the area only, or from neighbouring weather stations (allocated by the use of proximity polygons, is too limited. The most appropriate method conceptually is the use of weather data from sites within 50 kilometres radius of the area weighted to population centres, but a simpler acceptable option is to weight to the geographic centroid.

Dear Keith BG

2006-09-01

345

Hyperfunctioning parathyroid adenoma - radiological findings  

International Nuclear Information System (INIS)

Interest in increasing in the use of imaging methods during the preoperative investigation of patients with primary hyperparathyroidism. The authors report a case of hyper functioning adenoma of the parathyroid that emerged with skeletal manifestation where ultrasonography and scintigraphy were employed with Tc-99m sestamibi in the preoperative study of the parathyroids. In addition, radiologic finding, utilizing conventional radiology and computerized tomography, and the evolutive aspect of the lesions, four months after the beginning of the treatment, are also presented. (author)

346

Finding Communities of Related Genes  

OpenAIRE

We present an automated method of identifying communities of functionally related genes from the biomedical literature. These communities encapsulate human gene and protein interactions and identify groups of genes that are complementary in their function. We use graphs to represent the network of gene cooccurrences in articles mentioning particular keywords, and find that these graphs consist of one giant connected component and many small ones. In addition, the vertex degr...

Wilkinson, Dennis; Huberman, Bernardo A.

2002-01-01

347

A modified semi-supervised color image segmentation method  

Directory of Open Access Journals (Sweden)

Full Text Available The paper proposed a modified color image segmentation method basing on semi-supervised hidden Markov random fields (HMRF with constraints. Making use of MeanShift algorithm to get supervision information and, cluster number and initial values for cluster centroids, color images can be segmented effectively with the method in this paper by K-Means algorithm. The experimental results are very encouraging.

Chai Fangyong

2012-08-01

348

Vehicle Tracking and Speed Estimation using Optical Flow Method  

OpenAIRE

This paper presents a novel velocity estimation method for ground vehicles. The task here is to automatically estimate vehicle speed from video sequences acquired with a fixed mounted camera. The vehicle motion is detected and tracked along the frames using optical flow algorithm. The distance traveled by the vehicle is calculated using the movement of the centroid over the frames and the speed of the vehicle is estimated. The accuracy of our method was calculated by measuring the velocity ma...

S.Indu,; Manjari Gupta; Prof. Asok Bhattacharyya

2011-01-01

349

Convergence of the synaptic weights for the elastic net method, and its application  

Science.gov (United States)

Solution procedures for the traveling salesman problem (TSP), i.e. the problem of finding the minimum Hamiltonian circuit in a network of cities, can be divided into two categories: exact methods and approximate (or heuristic) methods. Since TSP is an NP hard problem, good heuristic approaches are of interest. The neural networks heuristic solutions of TSP was initiated by Hopfield and Tank. One such heuristic called the elastic net method is illustrated by the following, an imaginary rubber band is placed at the centroid of the distribution of n cities. Then some finite number (m greater than n) of points (nodes) on this rubber band changes their positions according to the dynamics of the method. Eventually they describe a tour around the cities. We express the dynamics and stability of the elastic net algorithm. We show that if a unique node is converging to a city, then the synaptic strength between them approaches one. Then we generalize to the case where more than one node converges to a city. Furthermore, a typical application that could make use of the elastic net method (e.g. multi-target tracking) will be pointed out for later studies. In order to verify the proof of the concept and the associated theorems, computer simulations were conducted for a reasonable number of cities.

Ghamasaee, Rahman; Goldberg, Jeffrey B.

1997-06-01

350

Intrathoracic gossypiboma: imaging findings  

International Nuclear Information System (INIS)

The authors report three cases of intrathoracic foreign body that is defined as a cotton matrix mass, mostly retained surgical sponge, a rare complication of a thoracic surgery. The patients were evaluated by chest radiography and computed tomography with the imaging findings confirmed after thoracotomy and anatomopathological study. The mainly imaging findings consisted of intrathoracic masses in patients with previous thoracic surgery that return to hospital with lower respiratory tract symptoms in different period after surgery procedure. The three cases were related with a brief review of the literature. (author)

351

Bronchopulmonary sequestration: radiologic findings  

Energy Technology Data Exchange (ETDEWEB)

Bronchopulmonary sequestration (BPS) is a nonfunctioning bronchopulmonary tissue that is separate from the tracheobronchial tree and receives arterial blood from the systemic circulation. BPS has a wide spectrum of imaging findings. Surgery is generally indicated for the treatment of BPS. It is important to demonstrate the arterial supply and venous drainage of the sequestered segment preoperatively. Today, with the help of noninvasive imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI), preoperative diagnosis of BPS can be made easily, so, invasive techniques such as angiography are not required frequently. In this report, radiological findings of BPS were retrospectively reviewed.

Bolca, Naile E-mail: nailebolca@yahoo.com; Topal, Ugur; Bayram, Sami

2004-11-01

352

Bronchopulmonary sequestration: radiologic findings  

International Nuclear Information System (INIS)

Bronchopulmonary sequestration (BPS) is a nonfunctioning bronchopulmonary tissue that is separate from the tracheobronchial tree and receives arterial blood from the systemic circulation. BPS has a wide spectrum of imaging findings. Surgery is generally indicated for the treatment of BPS. It is important to demonstrate the arterial supply and venous drainage of the sequestered segment preoperatively. Today, with the help of noninvasive imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI), preoperative diagnosis of BPS can be made easily, so, invasive techniques such as angiography are not required frequently. In this report, radiological findings of BPS were retrospectively reviewed

353

An actuator extension transformation for a motion simulator and an inverse transformation applying Newton-Raphson's method  

Science.gov (United States)

A set of equations which transform position and angular orientation of the centroid of the payload platform of a six-degree-of-freedom motion simulator into extensions of the simulator's actuators has been derived and is based on a geometrical representation of the system. An iterative scheme, Newton-Raphson's method, has been successfully used in a real time environment in the calculation of the position and angular orientation of the centroid of the payload platform when the magnitude of the actuator extensions is known. Sufficient accuracy is obtained by using only one Newton-Raphson iteration per integration step of the real time environment.

Dieudonne, J. E.

1972-01-01

354

Finding Pseudo-repetitions  

OpenAIRE

Pseudo-repetitions are a natural generalization of the classical notion of repetitions in sequences. We solve fundamental algorithmic questions on pseudo-repetitions by application of insightful combinatorial results on words. More precisely, we efficiently decide whether a word is a pseudo-repetition and find all the pseudo-repetitive factors of a word.

Gawrychowski, Pawel; Manea, Florin; Mercas, Robert; Nowotka, Dirk; Tiseanu, Catalin

2013-01-01

355

Finding the Sweet Spot  

Science.gov (United States)

In this activity, learners will discover how to find the "sweet spots" on a baseball bat. Whenever an object is struck, it vibrates in response. These vibrations travel in waves up and down the length of the object. At one point, called "the node," the waves always cancel each other out. The "sweet spot" is actually a node!

The Exploratorium

2012-06-26

356

Finding a Donor  

Science.gov (United States)

... marrow or PBSC donation Myths and facts about bone marrow donation Cord blood and transplants Matching patients with donors How donors and patients ... marrow donation works, the steps of a patient transplant, steps of donation, and factors that can impact the likelihood of finding a ... Join the marrow registry Join now Before you ...

357

Helium leak finding plant  

International Nuclear Information System (INIS)

The invention concerns a helium leak finding plant with a mass spectrometer cell on the suction side of a molecular pump and a mechanical pre-pump, where a test sample or a test sensor is connected between the two pumps. The mechanical pre-pump consists of three successive stages. (orig./HP)

358

Imaging findings of tarsal chondroblastoma  

International Nuclear Information System (INIS)

Objective: To analysis the imaging features of the chondroblastoma in the tarsal bone. Methods: The locations of 134 cases of pathologically confirmed chondroblastoma were retrospectively analyzed. Eleven of them were in tarsal bones and their X-ray and CT findings were analyzed. Results: Of the 11 cases of tarsal chondroblastoma, 6 were in talus, 3 were in calcaneus and 2 cases were in navicular bones. They were examined by the X-ray and 5 cases had additional CT scans. The common locations were the posterior portion of the talus and calcaneus. The X-ray findings included expansive destruction (10/11), mild osteosclerosis (11/11), bone ridge (9/11), articular facet destruction (7/11) and spot or patching calcification (6/11). The imaging findings of CT included articular facets destruction (5/5), bone ridge (5/5) and spot or patching calcification (2/5). Conclusion: The talus and the calcaneus are the frequently involved location of tarsal chondroblastoma. Its X-ray and CT findings are characteristic but not exclusive. (authors)

359

Neuroradiological findings in Behcet's disease  

International Nuclear Information System (INIS)

Purpose: We present the typical neuroradiological findings in three patients with neuro-Behcet in comparison with a review of neuroradiological and histopathological findings described in the literature. Material and Methods: In three male patients aged 32-57 years with Behcet's disease and neurological symptoms cranial CT and MRI studies were carried out. Findings were monitored over a period of 6-18 months. Additionally, cerebral and renal DSA were performed in two patients. Results: In two patients we found acute inflammatory lesions located in the brainstem and the periventricular white matter, some of which were associated with an acute inflammatory disruption of the blood-brain barrier. Lesions decreased in size under treatment, but complete resolution was not consistently noted. In the third patient we found a thrombosis of the superior sagittal sinus but no other intracranial abnormalities. Conclusions: Our findings agree with those described in the literature as being typical of Behcet's disease. Inflammatory lesions most commonly occur in the brain stem, followed by the basal ganglia and the cortex and white matter of both the cerebrum and cerebellum. In contrast to venous sinus thrombosis, brainstem atrophy and cortical or cerebellar lesions, white matter lesions have little diagnostic value, irrespective of their location. The definitive diagnosis of Behcet's disease is made on the basis of clinical criteria. (orig.).)

360

O centróide da piscina de água quente do pacífico como um indicador dos fenômenos El Niño e La Niña / The centroid of the pacific warm pool as an index for the El Niño and La Niña phenomena  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os fenômenos oceanográficos El Niño e La Niña foram analisados através do monitoramento da série temporal da componente zonal do centroide da piscina de água quente do Pacífico (PAQ) que descreve movimentos leste-oeste ao longo da faixa intertropical deste oceano. Utilizou-se uma série de dados de t [...] emperatura da superfície do Oceano Pacífico para classificar a PAQ e estimar o seu centroide entre 1981 e 2003. Todos os episódios de El Niño (1982-83; 1986-87; 1990-95; e 1997-98) e La Niña (1984-85; 1988-89; 1998-2000) existentes no período analisado puderam ser observados na série temporal de dados da componente zonal da PAQ (CZPAQ). Os episódios mais intensos de El Niño foram classificados pela ordenação decrescente dos maiores deslocamentos para leste (ranking). A série de dados da CZPAQ se apresentou em fase com o índice de Oscilação Sul e com a anomalia da temperatura superficial do oceano (TSO). As flutuações associadas ao movimento zonal do centroide da PAQ foram observadas no espectro de energia onde ficaram ressaltadas as flutuações interanuais associadas aos fenômenos El Niño e La Niña. Foram observados deslocamentos mais curtos para oeste durante os anos de La Niña, quando comparados aos deslocamentos para leste durante os eventos de El Niño. A migração zonal da PAQ, representada aqui pelo centroide, apresentou-se, portanto, como um indicador dos fenômenos El Niño e La Niña. A principal vantagem dessa técnica é a dependência de um único parâmetro arbitrário, que é o limiar da TSO para delinear a PAQ. Abstract in english The El Niño -La Niña oceanographic phenomena were analized making use of the zonal component of the Pacific warm pool (PAQ) which describes east-west displacements along the intertropical belt of this ocean. We manipulated an ocean surface temperature (TSO) timeseries to classify the PAQ and to esti [...] mate its centroid between 1981 and 2003. All the El Niño (1982-83; 1986-87; 1990-95; e 1997-98) and La Niña (1984-85; 1988-89; 1998-2000) episodes described in the academic literature were eminent in the timeserie of the zonal component of the Pacific warm pool (CZPAQ). The most intense El Niño episodes were ranked according to its furthest eastward displacement. The timeserie of the CZPAQ was in phase with both the TSO anomaly and the Southern Oscillation Index. The fluctuations associated to the CZPAQ were illustraded in the spectrum where interannual oscillations associated to the El Niño -La Niña phenomena were observed. Shorter migrations to the west during the La Niña years were notable in comparison to those eastward moviments during the El Niño events. Therefore, the zonal displacements of the PAQ, represented here by the centroid, were presented as having significant worth to indicate the El Niño and La Niña phenomena. The main advantage of this technique is that it depends on a single arbitrary parameter to represent the PAQ, the threshold of the ocean surface temperature in the Pacific Ocean.

361

[Imaging findings in neurocysticercosis].  

Science.gov (United States)

Neurocysticercosis, caused by the larvae of Taenia solium, is the parasitic infection that most commonly involves the central nervous system in humans. Neurocysticercosis is endemic in practically all developing countries, and owing to globalization and immigration it is becoming more common in developed countries like those in western Europe. The most common clinical manifestations are epilepsy, focal neurologic signs, and intracranial hypertension. The imaging findings depend on the larval stage of Taenia solium, on the number and location of the parasites (parenchymal, subarachnoid, or intraventricular), as well as on the host's immune response (edema, gliosis, arachnoiditis) and on the development of secondary lesions (arteritis, infarcts, or hydrocephalus). The diagnosis of this parasitosis must be established on the basis of the clinical and radiological findings, especially in the appropriate epidemiological context, with the help of serological tests. PMID:22632836

Sarria Estrada, S; Frascheri Verzelli, L; Siurana Montilva, S; Auger Acosta, C; Rovira Cañellas, A

2013-01-01

362

The Great Fossil Find  

Science.gov (United States)

On an imaginary fossil hunt, learners "find" (remove from envelope) paper "fossils" of some unknown creature, only a few at a time. Each time, they attempt to reconstruct the creature, and each time their interpretation tends to change as new pieces are "found." Use this as an introduction to the nature of science inquiry -- scientists don't always have all the information, scientists must form interpretations of the information, scientists must work together to come to consensus about interpretations.

Steve Rendak

1999-01-01

363

MRI Findings in Neuroferritinopathy  

OpenAIRE

Neuroferritinopathy is a neurodegenerative disease which demonstrates brain iron accumulation caused by the mutations in the ferritin light chain gene. On brain MRI in neuroferritinopathy, iron deposits are observed as low-intensity areas on T2WI and as signal loss on T2?WI. On T2WI, hyperintense abnormalities reflecting tissue edema and gliosis are also seen. Another characteristic finding is the presence of symmetrical cystic changes in the basal ganglia, which are s...

Emiko Ohta; Yoshihisa Takiyama

2011-01-01

364

CT findings in leukemia  

International Nuclear Information System (INIS)

Review of 84 computed tomographic (CT) scans in leukemic patients demonstrate a wide spectrum of abnormalities. Findings caused by leukemia were lymphadenopathy, visceral enlargement, focal defects, and tissue infiltration. Hemorrhage was by far the most common complication and could usually be characterized on the noncontrast CT scan. The distinction between old hematomas, foci of infection, and leukemia infiltration could not be made with certainty without CT-guided aspiration. Unusual instances of sepsis, such as microabscesses of the liver and typhlitis, were seen

365

CT findings in leukemia  

Energy Technology Data Exchange (ETDEWEB)

Review of 84 computed tomographic (CT) scans in leukemic patients demonstrate a wide spectrum of abnormalities. Findings caused by leukemia were lymphadenopathy, visceral enlargement, focal defects, and tissue infiltration. Hemorrhage was by far the most common complication and could usually be characterized on the noncontrast CT scan. The distinction between old hematomas, foci of infection, and leukemia infiltration could not be made with certainty without CT-guided aspiration. Unusual instances of sepsis, such as microabscesses of the liver and typhlitis, were seen.

Heiberg, E.; Wolverson, M.K.; Sundaram, M.; Shields, J.B.

1984-12-01

366

Heterotopic pregnancy: Sonographic findings  

Energy Technology Data Exchange (ETDEWEB)

To evaluate the sonographic findings of the heterotopic pregnancy which is increasing recently. Thirty-nine cases of heterotopic pregnancy after ovulation induction and IVF-ET (In Vitro Fertilization-Embryo Transfer) during the recent 3 years were analyzed. They were diagnosed by ultrasonography and proved surgically afterwards. Sonographic findings were analyzed focusing on gestational week of intrauterine pregnancy and location of ectopic pregnancy. In particular, adnexal mass was evaluated with regard to size and the characteristic findings such as ectopic gestational sac (echogenic ring). Also, overian cyst and fluid collection in cul-de-sac space were reviewed carefully. Heterotopic pregnancy was proved surgically by salpingectomy in 33 cases and by resection of cornus in six cases. Sonographic diagnosis using transvaginal ultrasound was made from five weeks to nine weeks two days (six weeks and four days in average) from last menstral period in all 39 cases. Ectopic pregnancy was identified in ampullary part in 29 cases, in the isthmic portion of tube in four cases and in the cornus of uterus in six cases. The intrauterine pregnancy was diagnosed by identifying the intrauterine gestational saccontaining a yolk sac in seven cases and the embryo with fetal heart beat in the remaining 32 cases. Adnexal masses of heterotopic pregnancy were less than 3 cm in diameter in 2 cases (57%), 3-4 cm in 11 cases (28%) and more than 4 cm in 6 cases (15%). A characteristic finding of ectopic mass was echogenic ring which was visible in 33 (84.6%) cases by transvaginal ultrasound. Six cases had pelvic hematosalpinx and two had pelvic hematoma. Of 10 cases (26%) which were identified to have ovarian hyperstimulation syndrome, eight (21%) had large amount of fluid collection in cul-de-sac and abdomen. Ultrasonographic identification of the intrauterine pregnancy and the ectopic chorion ring is effective for the early diagnosis of the heterotopic pregnancy.

Kwon, Tae Hee [CHA General Hospital of Seoul, Pochon CHA University College of Medicine, Seoul (Korea, Republic of)

1999-03-15

367

Acrocallosal syndrome: new findings.  

Science.gov (United States)

We describe a 21-month-old girl with typical manifestations of the acrocallosal syndrome of craniofacial anomalies, agenesis of the corpus callosum, hallucal duplication, severe hypotonia, and psychomotor retardation. Our patient also had the Dandy-Walker malformation, imperforate anus with rectovaginal fistula, hypothalamic dysfunction with hypothyroidism and diabetes insipidus, thick, dysplastic pulmonic valve leaflets, central and obstructive apnea, and pulmonary hypertension. These findings add to the delineation of this syndrome. PMID:2729349

Moeschler, J B; Pober, B R; Holmes, L B; Graham, J M

1989-03-01

368

Finding Monster Waves  

Science.gov (United States)

In this lesson, students learn about the varying sizes of ocean waves, what causes such variation, and where to find giant waves. Students will learn the parts of a wave, and discuss wave height, wavelength, and wave period. They will explore variables that influence wave size through scientific visualizations. They will then experiment with creating waves on the National Geographic Wave Simulator and discuss how geography affects waves.

369

Heterotopic pregnancy: Sonographic findings  

International Nuclear Information System (INIS)

To evaluate the sonographic findings of the heterotopic pregnancy which is increasing recently. Thirty-nine cases of heterotopic pregnancy after ovulation induction and IVF-ET (In Vitro Fertilization-Embryo Transfer) during the recent 3 years were analyzed. They were diagnosed by ultrasonography and proved surgically afterwards. Sonographic findings were analyzed focusing on gestational week of intrauterine pregnancy and location of ectopic pregnancy. In particular, adnexal mass was evaluated with regard to size and the characteristic findings such as ectopic gestational sac (echogenic ring). Also, overian cyst and fluid collection in cul-de-sac space were reviewed carefully. Heterotopic pregnancy was proved surgically by salpingectomy in 33 cases and by resection of cornus in six cases. Sonographic diagnosis using transvaginal ultrasound was made from five weeks to nine weeks two days (six weeks and four days in average) from last menstral period in all 39 cases. Ectopic pregnancy was identified in ampullary part in 29 cases, in the isthmic portion of tube in four cases and in the cornus of uterus in six cases. The intrauterine pregnancy was diagnosed by identifying the intrauterine gestational saccontaining a yolk sac in seven cases and the embryo with fetal heart beat in the remaining 32 cases. Adnexal masses of heterotopic pregnancy were less than 3 cm in diameter in 2 cases (57%), 3-4 cm in 11 cases (28%) and more than 4 cm in 6 cases (15%). A characteristic findcm in 6 cases (15%). A characteristic finding of ectopic mass was echogenic ring which was visible in 33 (84.6%) cases by transvaginal ultrasound. Six cases had pelvic hematosalpinx and two had pelvic hematoma. Of 10 cases (26%) which were identified to have ovarian hyperstimulation syndrome, eight (21%) had large amount of fluid collection in cul-de-sac and abdomen. Ultrasonographic identification of the intrauterine pregnancy and the ectopic chorion ring is effective for the early diagnosis of the heterotopic pregnancy.

370

MELAS syndrome: neuroradiological findings  

International Nuclear Information System (INIS)

To assess the computed tomography (CT) and magnetic resonance (MR) findings in MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) and their contribution to the diagnosis of this entity. We present three patients in which a diagnosis of MELAS syndrome was confirmed by muscle biopsy. CT revealed pathological findings in two patients: bilateral calcifications in the basal nuclei in one and low-attenuation lesions in occipital lobes in the other. Initial or follow-up MR demonstrated pathological findings highly suggestive of MELAS syndrome in all the patients. They consisted of hyperintense lesions in T2-weighted images, located predominantly in the cortex of occipital and parietal lobes. Cerebellar atrophy was also observed in two patients. The clinical signs varied, but epileptic seizures, headache, vomiting, ataxia, muscle weakness and pyramidal involvement were among the major ones. Only one patient presented high lactic acid levels, and in two, the initial muscle biopsy was not conclusive enough to provide the definitive diagnosis. CT and, especially, MR are useful tools in the diagnosis of MELAS syndrome, particularly in those cases in which initial negative laboratory and histological results make diagnosis difficult. (Author) 21 refs

371

Cannabinoid findings in children hair - what do they really tell us? An assessment in the light of three different analytical methods with focus on interpretation of ?9-tetrahydrocannabinolic acid A concentrations.  

Science.gov (United States)

Hair analysis for drugs and drugs of abuse is increasingly applied in child protection cases. To determine the potential risk to a child living in a household where drugs are consumed, not only can the hair of the parents be analyzed but also the hair of the child. In the case of hair analysis for cannabinoids, the differentiation between external contamination and systemic uptake is particularly difficult, since the drug is quite often handled extensively prior to consumption (e.g. when preparing a joint) and smoke causes a further risk for an external contamination. ?9-tetrahydrocannabinolic acid A (THCA-A), the non-psychoactive biogenetic precursor of ?9-tetrahydrocannabinol (THC), is a suitable marker for external contamination since it is not incorporated into the hair matrix through the bloodstream in relevant amounts. In the presented study, hair samples from 41 children, 4 teenagers, and 34 drug-consuming parents were analyzed for THCA-A, THC and cannabinol (CBN) applying methanolic extraction and a fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (Method 1). For comparison, a part of the samples was also analyzed applying alkaline hydrolysis followed by liquid/liquid extraction and gas chromatography-mass spectrometry (GC-M)S (Method 2), or by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) (Method 3). Furthermore, 458 seized marihuana samples and 180 seized hashish samples were analyzed for the same cannabinoids by gas-chromatography-flame ionization detector (GC-FID). In all but one of the hair samples, the concentration of THCA-A was higher than the concentration of THC and in 14 cases no THC could be detected despite the presence of THCA-A, suggesting that in almost all cases a significant external contamination had occurred. Within-family comparison showed a higher THCA-A/THC ratio in hair of children than of their consuming caregivers. Mean and median of this ratio of all hair samples (6.7 and 4.2) were between those of marihuana (11.0 and 8.3) and hashish (2.8 and 2.1) with a large variation in all samples. Comparison of the Methods 1 to 3 showed clearly that the choice of the analytical procedure has a strong influence on the quantitative results, mainly because of decarboxylation of THCA-A during hair hydrolysis by NaOH and other analytical steps, which lead to artifactually elevated THC concentrations. In conclusion, these findings suggest that the major part of the cannabinoids detected in the hair samples from children arose from an external contamination through 'passive' transfer by e.g. contaminated hands or surfaces and not from inhalation or deposition of side stream smoke. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25069954

Moosmann, Bjoern; Roth, Nadine; Hastedt, Martin; Jacobsen-Bauer, Andrea; Pragst, Fritz; Auwärter, Volker

2014-07-28

372

ASGE: Find a Doctor  

Science.gov (United States)

... you can search by any of the following methods: Name, City/State, Zip Code, or Country. Last ... Arabia Senegal Serbia and Montenegro Seychelles Sierra Leone Singapore Slovakia Slovenia Solomon Islands Somalia South Africa South ...

373

Brain venous pathologies: MRI findings  

International Nuclear Information System (INIS)

Purpose: To describe MRI findings of the different brain venous pathologies. Material and Methods: Between January 2002 and March 2004, 18 patients were studied 10 males and 8 females between 6 and 63 years old; with different brain venous pathologies. In all cases brain MRI were performed including morphological sequences with and without gadolinium injection and angiographic venous sequences. Results: 10 venous occlusions were found, 6 venous angiomas, and 2 presented varices secondary to arteriovenous dural fistula. Conclusion: Brain venous pathologies can appear in many different clinical contexts, with different prognosis and treatment. In all the cases brain MRI was the best imaging study to disclose typical morphologic abnormalities. (author)

374

Imaging Findings of Gastric Diverticula  

OpenAIRE

Introduction. Gastric diverticula (GD) are very rare. Computer tomographic findings in GD have been reported only as case reports previously. The aim of this study was to estimate the prevalence of GD on computed tomography (CT) and to analyze their radiological appearances. Materials and Methods. From 2006 to 2013, a total of 14,428 patients were examined by abdominal/thoracic CT at our institution. GD were diagnosed in 18 (0.12%) patients (13 women and 5 men, median age, 64 years). In 9 pat...

Dominik Schramm; Andreas Gunter Bach; Alexander Zipprich; Alexey Surov

2014-01-01

375

CT findings of invasive pulmonary aspergillosis  

International Nuclear Information System (INIS)

Objective: To study the CT findings of IPA. Methods: CT scans were performed in eight cases aged 25-76 years with pathologically proved IPA, two cases underwent second CT after 4 weeks. Results: CT findings includes mass-like infiltrate (n = 3), consolidation (n = 3); multi-nodules (n = 2). Conclusions: Early CT findings of IPA consist of mass-like, consolidation or multi-nodules, the CT halo sign: strongly suggests early diagnosis of IPA

376

Improved primary vertex finding for collider detectors  

CERN Document Server

Primary vertex finding for collider experiments is studied. The efficiency and precision of finding interaction vertices can be improved by advanced clustering and classification methods, such as agglomerative clustering with fast pairwise nearest neighbor search, followed by Gaussian mixture model or k-means clustering.

Sikler, Ferenc

2009-01-01

377

Renal dysplasia: US findings  

Energy Technology Data Exchange (ETDEWEB)

Renal dysplasia is a congenital anomaly with abnormal development of nephrotic and ductal structure and untreatable disease with absent renal function. To determine whether any consistent sonographic patterns exists,the sonograms of 27 pediatric patients with mastocytosis despotically kidney were reviewed. The diagnosis was proved by pathology in 16 cases and other radiologic imaging in 11 cases. In the classical multicystic despotically kidney(pelvoinfundibular atresia type, 10 cases), there were typical findings, such as absent communication between peripherally located variable sized cysts and presence of the largest cyst away from the renal hilum. One case was associated contralateral renal hydronephrosis. There cases were hydro nephrotic type which had medial location of the largest cyst with non communicating peripheral cysts. Segmental dysplasia with double collecting system and ureterocele (5 cases) and dysplasia due to parasite urethral valve (2 cases) showed hydronephrosis without identifiable peripheral cysts. Among the hypoplastic dysplastic kidney (7 cases) including ectopic kidneys (3cases), corticomedullary differentiation were hard to be identified in 2 cases. In conclusion, diagnosis of the renal dysplasia can be obtained by US only or US with other functional studies such as radionuclide scan(99mTc-DMSA or renogram) and IVP. US detection of renal dysplasia is easy, and US findings provide valuable information in the subsequent management

Ha, Doo Hoe; Oh, Ki Keun; Jung, Woo Hee; Yoon, Choon Sik; Ahn, Chang Soo; Kim, Myung Joon [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1993-12-15

378

MRI findings in neuroferritinopathy.  

Science.gov (United States)

Neuroferritinopathy is a neurodegenerative disease which demonstrates brain iron accumulation caused by the mutations in the ferritin light chain gene. On brain MRI in neuroferritinopathy, iron deposits are observed as low-intensity areas on T2WI and as signal loss on T2(?)WI. On T2WI, hyperintense abnormalities reflecting tissue edema and gliosis are also seen. Another characteristic finding is the presence of symmetrical cystic changes in the basal ganglia, which are seen in the advanced stages of this disorder. Atrophy is sometimes noted in the cerebellar and cerebral cortices. The variety in the MRI findings is specific to neuroferritinopathy. Based on observations of an excessive iron content in patients with chronic neurologic disorders, such as Parkinson disease and Alzheimer disease, the presence of excess iron is therefore recognized as a major risk factor for neurodegenerative diseases. The future development of multimodal and advanced MRI techniques is thus expected to play an important role in accurately measuring the brain iron content and thereby further elucidating the neurodegenerative process. PMID:21808735

Ohta, Emiko; Takiyama, Yoshihisa

2012-01-01

379

Climate change: Recent findings  

Energy Technology Data Exchange (ETDEWEB)

In the late eighties several reports have been published on climate change and sea level rise. In the meantime insights may have changed due to the availability of better and more observations and/or more advanced climate models. The aim of this report is to present the most recent findings with respect to climate change, in particular of sea level rise, storm surges and river peak flows. These climate factors are important for the safety of low-lying areas with respect to coastal erosion and flooding. In the first chapters a short review is presented of a few of the eighties reports. Furthermore, the predictions by state of the art climate models at that time are given. The reports from the eighties should be considered as `old` information, whereas the IPCC supplement and work, for example, by Wigley should be considered as new information. To assess the latest findings two experts in this field were interviewed: dr J. Oerlemans and dr C.J.E. Schuurmans, a climate expert from the Royal Netherlands Meteorological Institute (KNMI). Their views are presented together with results published in recent papers on the subject. On the basis of this assessment, the report presents current knowledge regarding predictions of climate change (including sea-level rise) over the next century, together with an assessment of the uncertainties associated with these predictions. 14 figs., 11 tabs., 24 refs.

Hesselmans, G.H.F.M.

1993-08-01

380

CT findings of slilcosis  

International Nuclear Information System (INIS)

To describe chest radiographic and CT findings of silicosis, and to compare their findings. Ten coal miners and six stonemasons were included in this study. All were male and their mean age was 53.1. The mean duration of dust exposure was 15.2 years(range, 5-30 years) in coal miners and 25.3 years(range, 15-35 years) in stonemasons. Chest radiographs(n=16), conventional CT scans(n=4), and high resolution CT(HRCT) scans(n=13) were evaluated. Parenchymal abnormalities were interpreted on the basis of ILO standard films(1980) in chest radiographs and on the basis of CAP(College of American Pathologists, 1979) in CT(HRCT) films. Chest radiographs revealed large opacities(n=8), small opacities(n=6), and normal findings(n=2). Type r(n=4) and category 1/1(n=2) were most common for small opacities, while for large opacities, category B(n=4) and category c(n=4) were most common. These small and large opacities were located predominantly in the area of the upper and middle lung. Associated findings were emphysema(n=7), eggshell nodal calcifications(n=3), pneumothorax(n=3), C-P angle blunting(n=4), and pleural thickening(n=1). CT scans revealed micronodules(n=16), nodules(n=3), and progressive massive fibrosis(PMF, n=8). All these lesions were located in the upper and middle lungs, especially in the central portion of the posterior lung. PMF showed diffuse and homogenous(n=3) and puntate(n=2) calcifications, cavitations(n=5), air bronchograms(n=3), and necrosis(n=1). Peripheral grams(n=3), and necrosis(n=1). Peripheral paracicatrical emphysema was associated with PMF(n=8). Other findings were pneumothorax(n=4), emphysema(n=10), hilar and mediastinal nodal enlargement(n=11) bronchial wall thick- enings(n=6), bronchiectasis(n=1), pleural thickening(n=7), parenchymal fibrosis(n=1), and pulmonary tuberculosis(n=2). Small and large opacities in chest radiographs and micronodules, nodules, and PMFs in CT (HRCT) films were located predominately in the upper and middle lungs, especially in the central portion of the posterior lung in CT films. CT was superior to plain chest radiographs in the following ways : (1) in the early detection of small opacities, including subpleural micronodules, and in the precise evaluation of their concen-tration and topography ; (2) in the detection of cavitation or calcification within conglomerate large opacity lesions ; (3) in the detection of hilar and mediastinal nodal enlargements ; and (4) in quantitative assessment of the severity of emphysema

381

Finding Communities of Related Genes  

CERN Document Server

We present an automated method of identifying communities of functionally related genes from the biomedical literature. These communities encapsulate human gene and protein interactions and identify groups of genes that are complementary in their function. We use graphs to represent the network of gene cooccurrences in articles mentioning particular keywords, and find that these graphs consist of one giant connected component and many small ones. In addition, the vertex degree distribution of the graphs follows a power law, whose exponent we determine. We then use an algorithm based on betweenness centrality to identify community structures within the giant component. The different structures are then aggregated into a final list of communities, whose members are weighted according to how strongly they belong to them. Our method is efficient enough to be applicable to the entire Medline database, and yet the information it extracts is significantly detailed, applicable to a particular problem, and interesting...

Wilkinson, D; Wilkinson, Dennis; Huberman, Bernardo A.

2002-01-01

382

Laser ray-tracing method for optical testing  

OpenAIRE

We have developed a novel laser ray-tracing method to measure aberrations in optical systems. It consists of delivering narrow laser pencils (by a laser scanner), recording the spots that are formed on the image plane (with a CCD camera), and computing the position of each centroid. This approach could be considered an experimental (approximate) implementation of standard numerical ray tracing. Several tests and experiments, including a direct comparison with a Hartmann–Shack wave-front sen...

Navarro, Rafael; Moreno Barriuso, Esther

1999-01-01

383

Characterization of uncertainty in the classification of multivariate assays: application to PAM50 centroid-based genomic predictors for breast cancer treatment plans  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Multivariate assays (MVAs for assisting clinical decisions are becoming commonly available, but due to complexity, are often considered a high-risk approach. A key concern is that uncertainty on the assay's final results is not well understood. This study focuses on developing a process to characterize error introduced in the MVA's results from the intrinsic error in the laboratory process: sample preparation and measurement of the contributing factors, such as gene expression. Methods Using the PAM50 Breast Cancer Intrinsic Classifier, we show how to characterize error within an MVA, and how these errors may affect results reported to clinicians. First we estimated the error distribution for measured factors within the PAM50 assay by performing repeated measures on four archetypal samples representative of the major breast cancer tumor subtypes. Then, using the error distributions and the original archetypal sample data, we used Monte Carlo simulations to generate a sufficient number of simulated samples. The effect of these errors on the PAM50 tumor subtype classification was estimated by measuring subtype reproducibility after classifying all simulated samples. Subtype reproducibility was measured as the percentage of simulated samples classified identically to the parent sample. The simulation was thereafter repeated on a large, independent data set of samples from the GEICAM 9906 clinical trial. Simulated samples from the GEICAM sample set were used to explore a more realistic scenario where, unlike archetypal samples, many samples are not easily classified. Results All simulated samples derived from the archetypal samples were classified identically to the parent sample. Subtypes for simulated samples from the GEICAM set were also highly reproducible, but there were a non-negligible number of samples that exhibit significant variability in their classification. Conclusions We have developed a general methodology to estimate the effects of intrinsic errors within MVAs. We have applied the method to the PAM50 assay, showing that the PAM50 results are resilient to intrinsic errors within the assay, but also finding that in non-archetypal samples, experimental errors can lead to quite different classification of a tumor. Finally we propose a way to provide the uncertainty information in a usable way for clinicians.

Ebbert Mark TW

2011-12-01

384

Ultrasonographic finding of intrahepatic stones  

International Nuclear Information System (INIS)

Correct diagnosis of intrahepatic stone with differentiation from extrahepatic stone is very important because of their different surgical procedure. The ultrasonography is very simple and noninvasive diagnostic method for detection of intrahepatic stone than other method. So the authors analysed the ultrasonographic findings of 30 patients with intrahepatic stones and the results are as follows: 1. Among 30 cases, 13(43.3%) were male, 17(56.7%) were female with predominancy in 5th and 6th decades. 2. 1) In distribution of stones 16 cases(53.5%) were in the left duct, 11 cases(36.7%) in both ducts, 3 cases(10%) in the right duct. 2) In location of intrahepatic stones, 9 cases(30%) were only in the intrahepatic ducts, 21 cases (70%) associated stones in the extrahepatic duct and or GB. 3. In sonography of 30 cases of intrahepatic stones 1) The shape of stone was round in 27 cases(90%) and tubular due to impacted stone in 3 cases (10%) 2) The echogenicity of stones was strong in 25 cases(83.3%) and weak in 5 cases(16.7%). 3) The shadow posterior to stones was strong in 23 cases(76.7%) and weak in 7 cases(23.3%) 4. As associated findings, metastatic lesion in liver 2 cases(6.7%), liver cirrhosis 2 cases(6.7%), hepatic and perihepatic abscess 4 cases(13.3%)were found liver(13.3%) were found

385

FindArticles.com  

Science.gov (United States)

This new service is a partnership between LookSmart and the Gale Group, a publisher of research and reference materials for libraries, businesses, and information technologists. The site offers free access to the full-text of articles published in over 350 magazines and journals dating from 1998. Users can search the database by keyword and by one of the nine subject categories (Arts & Entertainment, Computers & Technology, Reference & Education, Sports, etc.). Search returns include article title, periodical, and short description, with a link to the full-text, which is conveniently and quickly displayed at the FindArticles site, though with numerous advertising banners. Visitors can also view a list of the publications indexed, alphabetically or by subject. Periodical listings include a one-sentence description and a link to their Website. Despite the banners and other commercial content (the bills must be paid, after all) this site is a very useful reference source, indexing many leading journals and magazines.

386

Bayesian models for finding and grouping junctions  

OpenAIRE

In this paper, we propose two Bayesian methods for detecting and grouping junctions. Our junction detection method evolves from the Kona approach, and it is based on a competitive greedy procedure inspired in the region competition method. Then, junction grouping is accomplished by finding connecting paths between pairs of junctions. Path searching is performed by applying a Bayesian A* algorithm that has been recently proposed. Both methods are efficient and robust, and they are tested with ...

Cazorla Quevedo, Miguel A?ngel; Escolano Ruiz, Francisco; Gallardo Lo?pez, Domingo; Rizo Aldeguer, Ramo?n

1999-01-01

387

Calcaneal tendon: imaging findings  

International Nuclear Information System (INIS)

We reviewed the radiological and clinical features of 23 patients with calcaneal tendon diseases, who were submitted to ultrasound or magnetic resonance imaging. The objective of this study was to characterize the lesions for a precise diagnosis of calcaneal tendon injuries. A wide range of calcaneal tendon diseases include degenerative lesions, inflammation of the peritendinous tissue such as peritendinitis and bursitis, and rupture. Imaging methods are essential in the diagnosis, treatment and follow-up of calcaneal tendon diseases. (author)

388

The color doppler ultrasonography findings of leptospirosis  

International Nuclear Information System (INIS)

Objective: To study the color ultrasonography findings of leptospirosis. Methods: The color ultrasonography findings of heart, liver, spleen, kidney, lymph node and gastrocnemius in 51 cases of leptospirosis were studied retrospectively. Results: Changes of the color ultrasonography findings were showed in all cases. The changes of liver, kidney, lymph node and gastrocnemius were conspicuous, and the positive rates were 62%, 47%, 88% and 90%. Conclusion: Changes of the color ultrasonography findings of heart, liver, spleen, kidney, lymph node and gastrocnemius can be found in leptospirosis cases, without specificity. (authors)

389

Moment-Based Methods for Hybrid Optical/digital Pattern Recognition.  

Science.gov (United States)

Optical pre-processing of image data offers the opportunity for a tremendous data compression at rates unattainable through conventional electronic digital computing. Among the most well-known operations of this type is optical feature extraction for pattern recognition. This dissertation has optical feature extraction as its starting point. Taking advantage of the fundamental optical operation of Fourier transformation, the improvement in performance which can be obtained from extracting a set of moment invariants from both an image and its Fourier transform is studied from theoretical and experimental standpoints. Basically, moment invariants of the space domain are useful for distinguishing differences in shape and other gross features while Fourier domain moment invariants are useful for distinguishing differences in fine detail. Taken together, this dual -domain feature set is useful for a wider range of pattern recognition tasks than moment invariants from either domain taken by itself. A compact optical system for extracting the dual-domain complex moments which utilizes polarization and random phase multiplexing techniques is introduced. Feature extraction operations are usually both space-variant and global necessitating some form of scene segmentation and registration prior to extracting the feature. A windowed correlation method for optically locating the centroids of non-overlapping objects in a scene is demonstrated which accomplishes these segmentation and registration functions. It is further shown that this same approach can be used for tracking the movement of rigid and non -rigid objects. The centroid location technique can be extended into a general image understanding tool. Centroids are tracked over a continuous range of window sizes to produce a centroid scale-space map. One of the strongest advantages of the centroid scale-space approach is that the contours which are generated for 2-D inputs take the form of curved lines as compared with complicated surfaces for other well -known scale-space methods. The use of the centroid scale -space maps for obtaining the locations and size distribution of objects in a scene and for obtaining the medial axis transform of a scene is demonstrated. A hybrid optical/digital approach for computing the centroid scale-space maps is suggested.

Freeman, Mark Olmsted

390

Verified scientific findings  

International Nuclear Information System (INIS)

In this essay, the author attempts to enlighten the reader as to the meaning of the term ''verified scientific findings'' in section 13, sub-section 1, sentence 2 of the new Chemicals Control Law. The examples given here are the generally accepted regulations in regards to technology (that is sections 7a and 18b of the WHG (law on water economy), section 3, sub-section 1 of the machine- and engine protection laws) and to the status of technology (section 3, sub-section 6 of the BImSchG (Fed. law on prevention of air-borne pollution)), and to the status of science (section 5, sub-section 2 of the AMG (drug legislation). The ''status of science and technology'' as defined in sections 4 ff of the Atomic Energy Law (AtomG) and in sections 3, 4, 12, 2) of the First Radiation Protection Ordinance (1.StrlSch. VO), is also being discussed. The author defines the in his opinion ''dynamic term'' as the generally recognized result of scientific research, and the respective possibilities of practical utilization of technology. (orig.)

391

Sonographic Findings of Human Fascioliasis  

Directory of Open Access Journals (Sweden)

Full Text Available Background/Objective: Ultrasonography is an imaging modality which is easy to use and less expensive than other imaging methods. It is becoming more widely available in regions of the world where Fasciola hepatica infestation is prevalent. In this report, we described the sonographic findings of hepatic lesions in patients with fascioliasis. Patients and Methods: In this cross-sectional study, 248 patients with confirmed hepatic fascioliasis from Guilan province who were referred by internists or infectious disease specialists to private sonographic offices were studied. Abdominal sonography was performed in supine and left decubitus positions using an Aloka 288 scanner and a 3.5 MHz transducer. Results: Out of 176 hepatobiliary involvement, the right lobe of liver and the periportal area with echoic or hypoechoic lesions, had the most involvement (45.2%. There were lesions in the gallbladder of 34 (13.7% and biliary tracts of 17 (7% patients. There was coincident in-volvement of both liver and biliary tracts in 13 (5.2% patients. Conclusion: Sonography is a useful method to confirm hepatobiliary lesions in human fascio-liasis and can facilitate the diagnosis of this condition, particularly in areas where it is endemic.

F. Mansour Ghanaei

2006-08-01

392

Simple benchmark for complex dose finding studies.  

Science.gov (United States)

While a general goal of early phase clinical studies is to identify an acceptable dose for further investigation, modern dose finding studies and designs are highly specific to individual clinical settings. In addition, as outcome-adaptive dose finding methods often involve complex algorithms, it is crucial to have diagnostic tools to evaluate the plausibility of a method's simulated performance and the adequacy of the algorithm. In this article, we propose a simple technique that provides an upper limit, or a benchmark, of accuracy for dose finding methods for a given design objective. The proposed benchmark is nonparametric optimal in the sense of O'Quigley et al. (2002, Biostatistics 3, 51-56), and is demonstrated by examples to be a practical accuracy upper bound for model-based dose finding methods. We illustrate the implementation of the technique in the context of phase I trials that consider multiple toxicities and phase I/II trials where dosing decisions are based on both toxicity and efficacy, and apply the benchmark to several clinical examples considered in the literature. By comparing the operating characteristics of a dose finding method to that of the benchmark, we can form quick initial assessments of whether the method is adequately calibrated and evaluate its sensitivity to the dose-outcome relationships. PMID:24571185

Cheung, Ying Kuen

2014-06-01

393

Pulmonary hamartoma: imaging findings  

International Nuclear Information System (INIS)

Objective: To investigate the diagnostic value of X-ray film, CT features on pulmonary hamartoma. Methods: The radiographic materials and clinical information of 16 patients with pulmonary hamartoma confirmed by pathology were retrospective reviewed. Results: There were 6 lesions in left lung and 10 lesions in right. Except for 2 lesions with light lobulous margin, all other lesions showed clearly defined round nodule. All of 16 cases were single lesion. Chest plain film of 5 cases and 11 cases of CT showed as nodules with clear boundary. Fat density was found inside the lesion in 9 cases with thin-slice scan, and the lesions showed slightly enhancement after administration of contrast medium. Conclusion: X-ray film can be helpful in detection of hamartoma, thin-slice computed tomography scan and contrast enhancement have higher diagnosis value than plain film. (authors)

394

Radiography can find corrosion  

International Nuclear Information System (INIS)

Some of the advantages and limitations of using X-ray techniques to assess the severity of pitting corrosion in copper plumbing services were encountered recently. In an isolated maximum security area the services were run in basement walkways, the copper pipes being laid on brackets which held them clear of the concrete base. The location was ideal for use of X-ray techniques, which offered a means of checking short sections (18'') of the pipework without interrupting the supply. The radiographs indicated that pitting corrosion was widespread and shows the great value of X-ray examination as an aid to corrosion technology in the field, but also highlights the need for a rational interpretation of results in conjunction with other methods of visual and destructive assessment. (author)

395

Finding Partition Potentials  

Science.gov (United States)

Partition Density Functional Theory is a formally exact approach to partitioning molecules into fragments via functional minimization and constraints on fragment densities. Cohen and Car proposed a Dynamical Optimization Algorithm for Partition Theory inspired by the Car-Parrinello Method of electronic structure [1]. We modify this algorithm to incorporate a reference HOMO wave-function calculation as a guide to obtain the partition potential, a global quantity arising as the Lagrange multiplier that guarantees satisfaction of the density constraint. We report on the implementation of this procedure for one-dimensional systems, and possible implications for linear-scaling electronic-structure calculations.[4pt] [1] M. H. Cohen, and R. Car, J. Phys. Chem. A 2008, 112, 571-575

Nafziger, Jonathan; Cohen, Morrel; Wasserman, Adam

2012-02-01

396

Application of multiattribute decision-making methods for the determination of relative significance factor of impact categories.  

Science.gov (United States)

A relative significance factor (f(i)) of an impact category is the external weight of the impact category. The objective of this study is to propose a systematic and easy-to-use method for the determination of f(i). Multiattribute decision-making (MADM) methods including the analytical hierarchy process (AHP), the rank-order centroid method, and the fuzzy method were evaluated for this purpose. The results and practical aspects of using the three methods are compared. Each method shows the same trend, with minor differences in the value of f(i). Thus, all three methods can be applied to the determination of f(i). The rank order centroid method reduces the number of pairwise comparisons by placing the alternatives in order, although it has inherent weakness over the fuzzy method in expressing the degree of vagueness associated with assigning weights to criteria and alternatives. The rank order centroid method is considered a practical method for the determination of f(i) because it is easier and simpler to use compared to the AHP and the fuzzy method. PMID:12719893

Noh, Jaesung; Lee, Kun Mo

2003-05-01

397

Radiologic findings of epiploic appendagitis  

International Nuclear Information System (INIS)

Full text: Introduction: Epiploic appendagitis is a rare condition characterized by the ischemia and inflammation of the epiploic appendices of the colon. Its clinical features can mimic acute abdominal diseases such as diverticulitis and appendicitis. Objectives: The aim of this report is to present typical ultrasonography (US) and computed tomography (CT) features of this benign disease. Materials and method: A 44 year old man admitted to emergency department with a localized pain to umbilical region. His physical examination revealed rebound tenderness. He had no fever and his laboratory findings were normal. US examination showed a hyperechoic mass with a hypoechoic rim posterior to abdominal wall. Results: He was diagnosed with epiploic appendagitis and CT features confirmed the diagnosis. After a 5-day antibiotic treatment his clinical symptoms resolved. Conclusion: Epiploic appendagitis should be considered in the differential diagnosis of patients with an acute onset, localized pain. Because it is managed medically and has a self limited course, recognition of radiologic findings of this entity is important

398

MR findings of tuberous sclerosis  

International Nuclear Information System (INIS)

Magnetic resonance (MR) imaging of thirteen patients with tuberous sclerosis were reviewed. Seven patients underwent computed tomography (CT). The characteristic MR finding of tuberous sclerosis was those of subependymal nodules which were best seen on short repetition time (TR) spin-echo images. Hypointensities within the nodules consistent with calcification were most evident on long TR images. Contrast enhancing lesions, indicative subependymal giant cell astrocytoma, occurred in four cases. Cortical tubers (n = 11) and white matter lesions (n = 8) exhibited long T1 and T2 relaxation characteristics although reversed pattern was noted in one newborn patient. Cortical tubers and white matter lesions had more irregular shapes in early childhood patients. MR imaging is the sensitive method in detection of gyral tubers and white matter lesions and also valuable in detecting giant cell astrocytoma

399

CT findings in panacinar emphysema  

International Nuclear Information System (INIS)

We analysed the CT images (in vivo) of 5 lobes (right middle lobe, 1; left lower lobe, 1; right lower lobe, 3) with panacinar emphysema (PAE) obtained at autopsy or thoracotomy for solitary lung tumor. The lobes were inflation-fixed by the method of Heitzman and sliced axially for a CT-pathologic correlative study. One lobe with mild PAE had normal appearance on CT; however, the other four lobes with PAE demonstrated low-attenuation areas (LAAs) of various shapes and sizes on CT. LAAs were locally distributed on CT slices in one lobe, dominant in the inner zones in two lobes, and diffuse in one lobe. Relatively normal to diminished vasculature was observed within the LAAs of four lobes. These CT findings differed significantly from those of centriacinar emphysema (CAE) as reported in other studies. We conclude that CT is useful in the clinical diagnosis of PAE and its differentiation from CAE. (author)

400

Arthroscopic findings after shoulder dislocation  

Directory of Open Access Journals (Sweden)

Full Text Available Background/Aim. Recurrent instability of the shoulder joint is frequently difficult to differentiate from diseased or injured rotator cuff or tendon of the forearm flexor (m. biceps brachii. Shoulder joint arthroscopy has been only recently introduced into instable shoulder joint lesion examination. The aim of this study was to present and analyze an arthroscopic finding on instable shoulder joint in order to determine causes and mechanisms of instability, as well as principles of surgical treatment. Methods. Arthroscopy of the shoulder joint was performed in 158 patients with at least one documented shoulder joint dislocation. These patients were divided into two groups. The group I included the patients with one to three dislocations, while the group II those with more than three dislocations. Preoperative diagnosis was based on anamnestic data and clinical examination using specific tests, and on the diagnosis of shoulder joint using radiography or computed tomography. Results. Out of the total number of the patients 138 (87.34% had injury of the anterior patellar brim, 119 (75.32% had failure of the anterior capsule, 126 (79.75% had compressive cartilage injury of the posterior part of the head of the upper arm bone (Hill-Sachs lesion, 102 (64.56% had insufficiency of glenohumeral tendon, 11 (6.96 had complete cut of the rotator cuff, 23 (14.56% had injury of the posterior patellar brim, 12 (7.59% had injury of the upper anterior-posterior patellar brim (SLAP. Conclusion. According to the obtained results it could be concluded that there is no a unique injury that leads to shoulder joint instability. It is necessary to point out to the significance of anamnesis and clinical examination in making diagnosis. Arthroscopic diagnostics is indicated in clinically unreliable findings as an additional method for determining operative treatment.

Medenica Ivica

2009-01-01

401

Hippocampal malrotation: MRI findings  

International Nuclear Information System (INIS)

Purpose: To demonstrate the common features of hippocampus malrotation in patients with epilepsy by volumetric and high-resolution MRI. Material and methods: MRI study was performed in 5 patients (2 females and 3 males) ages ranged between 6-41 years (average: 25 years), all of them with epilepsy diagnosis. MRI was performed with a 1.5 T (GE Signa). The epilepsy protocol include sagittal T1, axial T1 and T2, coronal FLAIR, coronal T2 (high-resolution) and volumetric 3D SPGR IR 1.5 mm thick sequences. Results: The common features found in all patients were: a) Incomplete inversion and round configuration of the hippocampus; b) Unilateral affectation; c) Variable affectation of the hippocampus; d) Normal signal intensity; e) Modification of the inner structure of the hippocampus; f) Abnormal angularity of the collateral sulcus; g) Abnormal position and size of the fornix; h) Normal size of the temporal lobe; and i) Enlargement of the temporal horn with particular configuration. Conclusion: Hippocampus malrotation is a malformation that should be included in the differential diagnosis of the epilepsy patients. MRI provides accurate information for the diagnosis. (author)

402

MR findings of polymyositis / dermatomyositis  

International Nuclear Information System (INIS)

The purpose of this study was to evaluate the MR findings and useful sequences in Polymyositis/ Dermatomyositis, and to correlate MR findings with disease activity. Materials and Methods: The study included nine clinically proven cases of Polymyositis/Dermatomyositis, eight involving the thigh and one, the shoulder (2 cases, 1 follow-up). The contrast between affected and normal muscles and difference in signal intensity ratio in the muscle groups were retrospectively evaluated on Gd-enhanced T1WI and T2WI. We also evaluated the magnitude of involvement of muscle groups, fatty replacement of muscle and change of subcutaneous fat layer, and correlated signal intensity ratio with serum level of muscle enzymes. Differences in signal intensity ratio and the frequency of chemical shift artifact were evaluated on T2WI as active and inactive groups classified according to clinical findings, and the chemical shift artifact was correlated with the finding of Gd-enhanced T1WI. Except in the case of one shoulder, statistical analysis was assessed by the Anova test and-test. Results: On Gd-enhanced T1WI and T2WI contrast was 0.54 and 0.82, respectively and p value was 0.02. With regard to difference in signal intensity ratios of muscle groups, as seen on Gd-enhanced T1WI and T2WI, p valves were 0.07 and < 0.01, respectively. Muscle involvement was thus clearly visualized on T2WI. The order of frequency of involved muscle groups was vastus muscles, gluteus maximus, sartorius muscl muscles, gluteus maximus, sartorius muscles, adductor muscles, gracilis muscle, and hamstring muscles. Fatty replacement and subcutaneous fatty change were visualized in five cases and one, respectively. The correlation coefficient between the signal intensity seen on T2WI and muscle enzymes was 0.59 (CPK) and 0.52 (LDH). The chemical-shift artifact was detected in both clinical groups (four active two inactive) and corresponded to one case of muscle involvement and five of perimuscular edema, as seen on Gd-enhanced T1WI. Conclusion: T2WI is useful for the evaluation of muscle involvement and correlated closely with disease activity; signal intensity ratio could not be substituted for the serum level of muscle enzymes. The group of thigh muscles most affected was the vastus muscles, while the hamstring muscles were least affected. The chemical-shift artifact corresponded mainly to perimuscular edema and did not correlate with disease activity

403

Learning as way-finding  

DEFF Research Database (Denmark)

This paper is based on case study findings from studying undergraduate students’ perceptions of their navigation in a blended learning environment where different learning spaces are offered. In this paper learning is regarded as a multi-level and multi complex concept. In this regard the concept of learning used in this paper is inspired by the latest work of the Danish professor Illeris and the interwoven concept of knowledge development as revealed in the SECI-model generated by the Japanese professors Nonaka and Takeuchi. The empirical investigation, which is the basis of the presented assumptions, is based on the findings from research of the implementation of blended learning in two undergraduate programmes at University College North in Denmark. The data collection methods is based on eighteen focus-group interview collected in a period of the first two years of students enrolment in radiography and teachers education. Furthermore, a survey was conducted after three month of students’ enrolment and some few observations-studies in teachers’ education. The empirical data are interpreted in a narrative form through the use of prefiguration, configuration and refiguration and presented as themes around plots in a narrative form. The findings reveal that students’ use of different learning spaces are challenged by inhabited and embodied practices as well as disruptions. It is argued that learning must be viewed in the light of the new technological possibilities and challenges in spaces. There seem to be “blurred ecotones” between studying, leisure, sociality, identity-seeking and daily life which demands for an extension of the concept of learning. It is stressed that learning are conditioned by contextual orientations-processes in peripersonal spaces. Spaces of learning seem to guide how learning can be afforded and which kinds of learning. It is revealed that learning can be both constructed socially and individually but is constituted by the contextual orientation of the learner/s. Based on these findings it is suggested that learning (both formal and informal) can be conceptualized as way-finding both embodied, emotionally and/or cognitive. Way-finding, is argued, to be a concept for learning processes, knowledge development and identity-shaping where humans learn through motions, feeling and thinking in a world in motion and through combined actions of human and non-human agencies. Furthermore it is argued that cognitive learning-processes are intertwined with embodied learning, and that there are different levels of reflection, cognition and learning driven by outer and inner motifs, meaning, experiences, habits and outer conditions. In the discussion I suggest that learning in this century must take conditions of attention overload into account as an everyday condition which is more than ever actualized by the extended disruptions both by the information technology and other spaces. Based on the discussion areas for future research are suggested.

Dau, Susanne

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