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At least 775 records · Page 43Linked to original sources
PubMed2004

In vivo application of 3D-line skeleton graph analysis (LSGA) technique with high-resolution magnetic resonance imaging of trabecular bone structure.

Over the last several years magnetic resonance (MR) imaging has emerged as a means of measuring in vivo 3D trabecular bone structure. In particular, MR based diagnosis could be used to complement standard bone mineral density (BMD) methods for assessing osteoporosis and evaluating longitudinal changes. The aim of this study was to demonstrate the feasibility of using the 3D-LSGA technique for the evaluation of trabecular bone structure of high-resolution MR images, particularly for assessing longitudinal changes, in vivo. First, the reproducibility of topological 3D-LSGA based measurements was evaluated in a set of seven volunteers, and coefficients of variations ranged from 3.5% to 6%. Second, high-resolution MR images of the radius in 30 postmenopausal women from a placebo controlled drug study (Idoxifene), divided into placebo ( n=9) and treated ( n=21) groups, were obtained at baseline (BL) and after 1 year of treatment (follow-up, FU). In addition, dual X-ray absorptiometry (DXA) measures of BMD were obtained in the distal radius. Standard morphological measurements based on the mean intercept length (MIL) technique as well as 3D-LSGA based measurements were applied to the 3D MR images. Significant changes from BL to FU were detected, in the treated group, using the topological 3D-LSGA based measurements, morphological measures of volume of connected trabeculae and App Tb.N from MIL analysis. The duration of the study was short, and the number of patients remaining in the study was small, hence these results cannot be interpreted with regard to a true therapeutic response. Furthermore, the site (wrist) and the drug (idoxifene) are not optimal for follow-up study. However, this paper demonstrated the feasibility of using 3D-LSGA based evaluation coupled with in vivo high-resolution MR imaging as a complementary approach for the monitoring of trabecular bone changes in individual subjects.

Adult↗
PubMed2001

Calibration graphs for steels by IR laser ablation inductively coupled plasma atomic emission spectrometry.

Infrared laser ablation (IRLA) was studied as a sample-introduction technique for the analysis of steels by inductively coupled plasma atomic emission spectrometry (ICP-AES). A comparison of two IRLA-ICP-AES systems based on Q-switched nanosecond Nd: YAG lasers was performed. The beam of the LINA-Spark atomizer (LSA Sarl, Cully, Switzerland) based on the Surelite 1-20 laser (Continuum, USA) was moved along a circle. A Perkin-Elmer Optima 3000 DV ICP system was used both with lateral and axial viewing modes. A laboratory-made ablation system based on the Brilliant laser (Quantel) was coupled to a Jobin-Yvon 170 Ultrace ICP (lateral viewing, polychromator part employed). A sample was rotated along a circle during ablation. Linearity of calibration plots was verified at least up to 19% Cr and 12% Ni without internal standardization for both LA-ICP-AES systems. Other elements examined were Mo up to 3%, Mn up 1.5%, Si up to 1.7%, and Cu up to 0.15%. The reproducibility was in the range 5-1 %RSD for a mass percentage 0.5-20% of steel constituents. The relative uncertainty of the centroids of the calibration lines was in the range from +/- 4% to +/- 12% for Cr, Ni, Mn, Mo, and Si, and from +/- 8% to +/- 19% for Cu. The lowest determinable quantities were calculated for calibration dependencies. Performances of both the IR-LA-ICP-AES were comparable.

Journal Article↗
PubMed2001

Calibration graphs for Ti, Ta and Nb in sintered tungsten carbide by infrared laser ablation inductively coupled plasma atomic emission spectrometry.

Infrared laser ablation (IR-LA) has been studied as a sample introduction technique for the analysis of sintered cobalt-cemented tungsten carbide materials by inductively coupled plasma atomic emission spectrometry (ICP-AES). Fractionation of cobalt was observed. Linearity of calibration plots was verified at least up to 15% Ti, 8% Ta, and 3% Nb. Above 1% (m/m) Ti, Ta, and Nb, the repeatability of results was better than 3% R.S.D. The relative uncertainty at the centroid of the calibration line was in the range from +/- 3% to +/- 4% for Ti, Ta, and Nb with internal standardization by tungsten and up to +/- 5% without internal standardization. The limits of detection were 0.004% Ti, 0.001% Ta, and 0.004% Nb. Elimination of the cemented hardmetal dissolution procedure is the main advantage of this method.

Journal Article↗
PubMed2005

QSPR modeling of the water solubility of diverse functional aliphatic compounds by optimization of correlation weights of local graph invariants.

The optimization of correlation weights scheme was used to model the water solubility (ln S) of diverse functional aliphatic compounds (n = 193). The optimized descriptor formulated based on the data of a training set (n = 96) generated statistically acceptable relations for the training set (r2 = 0.987), test set (n = 97; r2 = 0.986) and combined set (r2 = 0.987). When the relation of ln S values with the optimized molecular descriptor formulated based on the data of the training set was used for the calculation of ln S values of the training set, r(pred)2 value was found to be satisfactory (0.988), which is indicative of the predictive potential of the scheme. The results indicate the promising potential of the optimization of correlation weights scheme in modeling studies.

Alcohols↗
PubMed2006

ViewPoint and ViewDist: utilities for rapid graphing of linkage distributions and identification of outliers.

ViewPoint and ViewDist are stand alone Java utilities designed to provide an interactive visual representation of data from files which may be created by the user or produced directly from analyses packages such as Mx. ViewPoint is designed for representation of linkage results and can be used for summarizing multiple univariate linkage results or providing detailed comparison of univariate and multivariate results, with optional dynamic sub-plots designed to display the QTL path coefficients at each marker. ViewDist is an easy to use distribution plotter designed for use with raw data or case-wise likelihood statistics. The utility can produce Q-Q plots (assuming either normal or chi(2)-distributions) and by allowing data to be read simultaneously from two files readily produces difference plots allowing comparison of the case-wise likelihood under two competing models.

Chromosome Mapping↗