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Selected AbstractsApplication of Three Dental Methods of Adult Age Estimation from Intact Single Rooted Teeth to a Peruvian SampleJOURNAL OF FORENSIC SCIENCES, Issue 3 2008Douglas H. Ubelaker Ph.D. Abstract:, Methods of estimating adult age at death from such dental features as root translucency, root length, and the extent of periodontosis in intact single rooted teeth have proven useful in studies of modern individuals, especially in estimating age in older adults. Questions remain however, concerning the impact of regional and population variation on accuracy. To examine this issue, three approaches to age estimation were applied to a diverse sample of 100 individuals from Peru. Mean errors of estimation for all three approaches were similar to those originally reported, suggesting minimal impact of population variation of the features measured. A new regression equation, specifically for Peruvian samples, is provided. [source] Estimation of Acute Fluid Shifts Using Bioelectrical Impedance Analysis in HorsesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2007C. Langdon Fielding Background: Multi-frequency bioelectrical impedance analysis (MF-BIA) has been used to evaluate extracellular fluid volume (ECFV), but not fluid fluxes associated with fluid or furosemide administration in horses. If able to detect acute changes in ECFV, MF-BIA would be useful in monitoring fluid therapy in horses. Hypothesis: The purpose of this study was to evaluate the ability of MF-BIA to detect acute fluid compartment changes in horses. We hypothesized that MF-BIA would detect clinically relevant (10,20%) changes in ECFV. Animals: Six healthy mares were used in the study. Methods: This is an original experimental study. Mares were studied in 3 experiments: (1) crystalloid expansion of normally hydrated subjects, (2) furosemide-induced dehydration followed by crystalloid administration, and (3) acute blood loss followed by readministration of lost blood. MF-BIA measurements were made before, during, and after each fluid shift and compared to known changes in volume calculated based on the intravenous fluids that were administered in addition to urinary fluid losses. Mean errors between MF-BIA estimated change and known volume change were compared using nonparametric analysis of variance. Estimated ECFV pre- and post-fluid administration similarly were compared. The level of statistical significance was set at P < .05. Results: Results of the study revealed a statistically significant change in ECFV and total body water during crystalloid expansion and dehydration. Statistically significant changes were not observed during blood loss and administration. Mean errors between MF-BIA results and measured net changes were small. Conclusions and Clinical Importance: MF-BIA represents a practical and accurate means of assessing acute fluid changes during dehydration and expansion of ECFV using isotonic crystalloids with potential clinical applications in equine critical care. [source] Comparison of LiDAR waveform processing methods for very shallow water bathymetry using Raman, near-infrared and green signalsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2010Tristan Allouis Abstract Airborne light detection and ranging (LiDAR) bathymetry appears to be a useful technology for bed topography mapping of non-navigable areas, offering high data density and a high acquisition rate. However, few studies have focused on continental waters, in particular, on very shallow waters (<2,m) where it is difficult to extract the surface and bottom positions that are typically mixed in the green LiDAR signal. This paper proposes two new processing methods for depth extraction based on the use of different LiDAR signals [green, near-infrared (NIR), Raman] of the SHOALS-1000T sensor. They have been tested on a very shallow coastal area (Golfe du Morbihan, France) as an analogy to very shallow rivers. The first method is based on a combination of mathematical and heuristic methods using the green and the NIR LiDAR signals to cross validate the information delivered by each signal. The second method extracts water depths from the Raman signal using statistical methods such as principal components analysis (PCA) and classification and regression tree (CART) analysis. The obtained results are then compared to the reference depths, and the performances of the different methods, as well as their advantages/disadvantages are evaluated. The green/NIR method supplies 42% more points compared to the operator process, with an equivalent mean error (,4·2,cm verusu ,4·5,cm) and a smaller standard deviation (25·3,cm verusu 33·5,cm). The Raman processing method provides very scattered results (standard deviation of 40·3,cm) with the lowest mean error (,3·1,cm) and 40% more points. The minimum detectable depth is also improved by the two presented methods, being around 1,m for the green/NIR approach and 0·5,m for the statistical approach, compared to 1·5,m for the data processed by the operator. Despite its ability to measure other parameters like water temperature, the Raman method needed a large amount of reference data to provide reliable depth measurements, as opposed to the green/NIR method. Copyright © 2010 John Wiley & Sons, Ltd. [source] Simulation of ice phenology on Great Slave Lake, Northwest Territories, CanadaHYDROLOGICAL PROCESSES, Issue 18 2002Patrick Ménard Abstract A one-dimensional thermodynamic lake ice model (Canadian Lake Ice Model or CLIMo) is used to simulate ice phenology on Great Slave Lake (GSL) in the Mackenzie River basin, Northwest Territories, Canada. Model simulations are validated against freeze-up and break-up dates, as well as ice thickness and on-ice snow depth measurements made in situ at three sites on GSL (Back Bay near Yellowknife, 1960,91; Hay River, 1965,91; Charlton Bay near Fort Reliance, 1977,90). Freeze-up and break-up dates from the lake ice model are also compared with those derived from SSM/I 85 GHz passive microwave imagery over the entire lake surface (1988,99). Results show a very good agreement between observed and simulated ice thickness and freeze-up/break-up dates over the 30,40 years of observations, particularly for the Back Bay and Hay River sites. CLIMo simulates the ice thickness and annual freeze-up/break-dates with a mean error of 7 cm and 4 days respectively. However, some limitations have been identified regarding the rather simplistic approach used to characterize the temporal evolution of snow cover on ice. Future model improvements will therefore focus on this particular aspect, through linkage or coupling to a snow model. Copyright © 2002 John Wiley & Sons, Ltd. [source] Estimating missing daily temperature extremes using an optimized regression approachINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2001Robert J. Allen Abstract A variation of a least squares regression approach to estimate missing daily maximum and minimum temperatures is developed and evaluated, specifically for temperature extremes. The method focuses on obtaining accurate estimates of annual exceedence counts (e.g. the number of days greater than or equal to the 90th percentile of daily maximum temperatures), as well as counts of consecutive exceedences, while limiting the estimation error associated with each individual value. The performance of this method is compared with that of two existing methods developed for the entire temperature distribution. In these existing methods, temperature estimates are based on data from neighbouring stations using either regression or temperature departure-based approaches. Evaluation of our approach using cold minimum and warm maximum temperatures shows that the median percentage of correctly identified exceedence counts is 97% and the median percentage of correctly identified consecutive exceedence counts is 98%. The other existing methods tend to underestimate both single and consecutive exceedence counts. Using these procedures, the estimated exceedence counts are generally less than 80% of those that actually occurred. Despite the fact that our method is tuned to estimate exceedence counts, the estimation accuracy of individual daily maximum or minimum temperatures is similar to that of the other estimation procedures. The median absolute error (MAE) using all temperatures greater than or equal to the 90th percentile (T90),1.1°C for ten climatically diverse stations is 1.28°C for our method, while the other methods give MAEs of 1.27 and 1.17°C. In terms of median error, however, the tendency for underprediction by the existing methods is pronounced with ,0.77 and ,0.61°C biases. Our optimized method is relatively unbiased as the resulting mean error is ,0.12°C. Copyright © 2001 Royal Meteorological Society [source] Comparison of solar radiation correlations for ,zmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2002K. Ulgen Abstract In this study, empirical correlations are developed to estimate the monthly average daily global solar radiation on a horizontal surface (H) for the city of ,zmir in Turkey. Experimental data were measured in the Solar,Meteorological Station of the Solar Energy Institute at Ege University. The present models are then compared with the 25 models available in the literature for calculating H based on the main percentage error, root mean error, the main bias error, and correlation coefficient. It can be concluded that the present models predict the values of H for ,zmir better than other available models. Copyright © 2002 John Wiley & Sons, Ltd. [source] Development and psychometric testing of a new geriatric spiritual well-being scaleINTERNATIONAL JOURNAL OF OLDER PEOPLE NURSING, Issue 3 2008Karen S. Dunn PhD Aims and objectives., Assess the psychometric properties of a new geriatric spiritual well-being scale (GSWS), specifically designed for older adults. Background., Religiosity and spiritual wellness must be measured as two distinct concepts to prevent confounding them as synonymous among atheist and agnostic population. Design., A test,retest survey design was used to estimate the psychometric properties. Methods., A convenience sample of 138 community-dwelling older adults was drawn from the inner city of Detroit. Data were collected using telephone survey interviews. Data analyses included descriptive statistics, structural equation modelling, reliability analyses, and point-biserial correlations. Results., The factorial validity of the proposed model was not supported by the data. Fit indices were ,2 = 185.98, d.f. = 98, P < 0.00, goodness-of-fit index of 0.85, comparative fit index of 0.87 and root mean error of approximation of 0.08, indicating a mediocre fit. Reliability statistics for the subscales ranged from being poor (0.36) to good (0.84) with an acceptable overall scale alpha of 0.76. Participants' performance stability and criterion-related validity were also supported. Conclusions., The GSWS is an age-specific assessment tool that was developed specifically to address a population's cultural diversity. Future research endeavors will be to test the psychometric properties of this scale in culturally diverse older adult populations for further instrument development. Relevance to clinical practice., Nurses need to recognize that agnostics/atheists have spiritual needs that do not include religious beliefs or practices. Thus, assessing patients' religious beliefs and practices prior to assessing spiritual well-being is essential to prevent bias. [source] Prediction of cooling time in injection molding by means of a simplified semianalytical equationADVANCES IN POLYMER TECHNOLOGY, Issue 3 2003D. M. Zarkadas Abstract A simplified semianalytical equation, used successfully in food freezing/chilling time prediction, is proposed as a potential simple alternative for cooling time prediction in injection molding of polymer parts, amorphous or semicrystalline. This equation is based on a convective boundary condition for the mold-part interface and requires information on the thermal contact resistance (TCR) or thermal contact conductance (TCC) at this interface, as well as information on the initial and final product temperatures, the mold surface temperature, and the thermal properties of the part. Eighty-five data points for four polymers, Polystyrene (PS), Polycarbonate (PC), Polypropylene (PP), and Polyethylene (PE) were generated with C-MOLDÔ, a commercial injection molding design software, and the performance of the proposed equation was tested. The % mean error and its standard deviation (SD) in cooling time prediction were, respectively, ,11.61 and 2.27 for PS, ,6.04 and 2.13 for PC, ,7.27 and 6.55 for PP, and ,8.88 and 2.93 for PE. It was also shown that the accuracy of the proposed equation is not affected significantly by the exact knowledge of the TCC, provided that the latter is not smaller than 1000,2000 W m,2 K,1. Since in this comparison all necessary temperatures were obtained from C-MOLDÔ, methods of using the proposed equation independently were tested. The use of the inlet melt temperature as the initial product temperature increased the % mean error by mostly 1.5% while its SD remained practically the same. By incorporating a literature based heat balance method in the proposed equation, it was possible to use it as a stand-alone predictor of polymer cooling time. The % mean error and its SD calculated this way were, respectively, ,9.44 and 0.97 for PS, ,9.44 and 0.83 for PC, ,14.22 and 5 for PP, and ,20.12 and 1.38 for PE. The proposed equation, at least in a preliminary stage, can be used successfully to predict the cooling time of the selected semicrystalline or amorphous polymers with the accuracy being higher for amorphous polymers. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 188,208, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10048 [source] Forecasting the price of crude oil via convenience yield predictionsJOURNAL OF FORECASTING, Issue 7 2007Thomas A. KnetschArticle first published online: 14 NOV 200 Abstract The paper develops an oil price forecasting technique which is based on the present value model of rational commodity pricing. The approach suggests shifting the forecasting problem to the marginal convenience yield, which can be derived from the cost-of-carry relationship. In a recursive out-of-sample analysis, forecast accuracy at horizons within one year is checked by the root mean squared error as well as the mean error and the frequency of a correct direction-of-change prediction. For all criteria employed, the proposed forecasting tool outperforms the approach of using futures prices as direct predictors of future spot prices. Vis-à-vis the random-walk model, it does not significantly improve forecast accuracy but provides valuable statements on the direction of change. Copyright © 2007 John Wiley & Sons, Ltd. [source] Improving kp Data Originating from PLP Number DistributionsMACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2006Andreas Kornherr Abstract Summary: Based on certain features, especially the width of the so-called extra peaks in the simulated number-chain-length distribution (CLD) of polymers prepared by pulsed laser polymerization (PLP), it is calculated by which factor the positions of the points of inflections and maxima deviate from the theoretical L0 data that are to be used for the evaluation of kp. These corrections are for slightly chain-length-dependent termination by disproportionation or combination and cover a wide range of chain-lengths and primary radical production. They can be applied either to the point of inflection on the low-molecular weight side of the extra peaks or to the peak maximum. On average, the mean error that is about ,2.5% for uncorrected data from first-order points of inflection is reduced to the order of less than 1% even if no assumption concerning the mode of termination is made. The situation is similar for the positions of the first-order peak maxima where the mean error of about +7% likewise can be cut down to less than 1% if the proper correction function is chosen. Second- and third-order peaks data, which are a priori less falsified, yield still better results after correction. Mass sensitivity of the detection process has comparatively little effect: it is only for unrealistically high extents of chain-length dependence in detection that considerable falsifications are to be expected. As an additional result it turned out that correction functions obtained for number distributions are also applicable to mass spectrometry raw distributions and even for mass distributions x(l),·,l provided Poissonian broadening is the only broadening process. Number distribution xC(l) calculated for termination by combination times attenuation function F1(l). [source] QSAR Models for the Dermal Penetration of Polycyclic Aromatic Hydrocarbons Based on Gene Expression ProgrammingMOLECULAR INFORMATICS, Issue 7 2008Tao Wang Abstract Gene Expression Programming (GEP) is a novel machine learning technique. The GEP is used to build nonlinear quantitative structure activity relationship model for the prediction of the Percent of Applied Dose Dermally Absorbed (PADA) over 24,h for polycyclic aromatic hydrocarbons. This model is based on descriptors which are calculated from the molecular structure. Three descriptors are selected from the descriptors pool by Heuristic Method (HM) to build a multivariable linear model. The GEP method produced a nonlinear quantitative model with a correlation coefficient and a mean error of 0.92 and 4.70 for the training set, 0.91 and 7.65 for the test set, respectively. It is shown that the GEP predicted results are in good agreement with experimental ones. [source] Study of onset time-shift and injection duration in DCE-MRI: a comparison of a reference region model with the general kinetic modelNMR IN BIOMEDICINE, Issue 4 2010Ing-Tsung Hsiao Abstract In dynamic contrast-enhanced MR imaging (DCE-MRI), sampling of the arterial input function (AIF) is required for analysis using the general kinetic model (GKM). Alternatively, the recently proposed reference region model (RRM) may be employed to avoid the need of acquiring the AIF. This study aimed to evaluate the influence of the AIF onset-time shift and the injection duration, under various sampling intervals, on physiological parameter estimation in DCE-MRI using the GKM, and to compare the performance between GKM and RRM. Computer simulations were performed to assess the mean error (ME) and coefficient of variation (CoV) of Ktrans,TOI and ve,TOI from shifted and dispersed AIF with temporal resolution of 1, 5 and 10,s. With 5-s sampling, the maximal ME of Ktrans,TOI was roughly 22% for the GKM and 0.5% for the RRM. With 10-s sampling, they increased to around 28% and 0.7%, respectively. The maximal MEs of ve,TOI for all cases were under 5%. However, owing to the lower SNR in the reference region, the CoV obtained by the RRM were all higher than those by the GKM. The results suggested that with compromised temporal resolution, the RRM was relatively less sensitive to the AIF onset-time shift and the injection duration compared with the GKM. Copyright © 2009 John Wiley & Sons, Ltd. [source] Correlates of peer victimization and achievement: An exploratory modelPSYCHOLOGY IN THE SCHOOLS, Issue 4 2009Tanya Beran This study investigates peer victimization and achievement. Adolescents aged 12,15 years were drawn from the National Longitudinal Survey of Children and Youth, which is a stratified random sample of 22,831 households in Canada. Teachers', children's, and parents' reports were combined in a latent variable path analysis, ,2(51) = 348.54, p < .000. The model converged in six iterations resulting in a Comparative Fit Index = .90, and a standardized residual mean error of .05. The model shows that adolescents who are victimized by their peers are at risk of experiencing poor school achievement if they exhibit disruptive behaviors, receive little support from their teachers, and experience non-nurturing, rejecting behaviors from their parents. © 2009 Wiley Periodicals, Inc. [source] Three-dimensional ultrasound image-guided robotic system for accurate microwave coagulation of malignant liver tumoursTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 3 2010Jing Xu Abstract Background The further application of conventional ultrasound (US) image-guided microwave (MW) ablation of liver cancer is often limited by two-dimensional (2D) imaging, inaccurate needle placement and the resulting skill requirement. The three-dimensional (3D) image-guided robotic-assisted system provides an appealing alternative option, enabling the physician to perform consistent, accurate therapy with improved treatment effectiveness. Methods Our robotic system is constructed by integrating an imaging module, a needle-driven robot, a MW thermal field simulation module, and surgical navigation software in a practical and user-friendly manner. The robot executes precise needle placement based on the 3D model reconstructed from freehand-tracked 2D B-scans. A qualitative slice guidance method for fine registration is introduced to reduce the placement error caused by target motion. By incorporating the 3D MW specific absorption rate (SAR) model into the heat transfer equation, the MW thermal field simulation module determines the MW power level and the coagulation time for improved ablation therapy. Two types of wrists are developed for the robot: a ,remote centre of motion' (RCM) wrist and a non-RCM wrist, which is preferred in real applications. Results The needle placement accuracies were < 3 mm for both wrists in the mechanical phantom experiment. The target accuracy for the robot with the RCM wrist was improved to 1.6 ± 1.0 mm when real-time 2D US feedback was used in the artificial-tissue phantom experiment. By using the slice guidance method, the robot with the non-RCM wrist achieved accuracy of 1.8 ± 0.9 mm in the ex vivo experiment; even target motion was introduced. In the thermal field experiment, a 5.6% relative mean error was observed between the experimental coagulated neurosis volume and the simulation result. Conclusion The proposed robotic system holds promise to enhance the clinical performance of percutaneous MW ablation of malignant liver tumours. Copyright © 2010 John Wiley & Sons, Ltd. [source] Three-dimensional variational assimilation of Special Sensor Microwave/Imager data into a mesoscale weather-prediction model: A case studyTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 626 2007C. Faccani Abstract Assimilation of data from the Special Sensor Microwave/Imager (SSM/I) is performed in order to improve the forecast of a heavy-precipitation case (IOP2b, 20,21 September 1999) of the Mesoscale Alpine Programme 1999. The three-dimensional variational data assimilation technique of the MM5 model is used. Either brightness temperatures or precipitable water and surface wind speed are assimilated. The sensitivity of the model to SSM/I data is also tested by selectively excluding SSM/I frequencies and changing the size of the thinning box. All the experiments are performed using the European Center for Medium range Weather Forecasting (ECMWF) analysis on pressure level. The new initial conditions show considerable underestimation of the surface wind component V, and, even more, of the surface water vapour mixing ratio. This last error is partially corrected by assimilation of precipitable water alone, although these data produce a large increase in the mean error of the other surface variables (U, V and T). However, the forecast with this new set of initial conditions shows a good agreement (high correlation coefficient) with the rain gauge observations for the 1 h accumulated precipitation 3 h after the initial time. With a doubled box size, there is low sensitivity to the density of the observations used. In this case, the effect of the SSM/I data is slight, and the rainfall pattern produced is comparable to that obtained without any data assimilation. The model performance is also degraded if the 22 GHz brightness temperatures are removed from the assimilated measurements: the correlation coefficient for the precipitation is lower than in the case where all the frequencies are assimilated, and it decreases over time. In general, the use of precipitable water and surface wind speed affects the early stages (3 h) of the rainfall forecast, reducing the model spin-up. Brightness temperatures affect the forecast at a longer range (10 h). Copyright © 2007 Royal Meteorological Society [source] Data assimilation of high-density observations.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 605 2005II: Impact on the forecast of the precipitation for the MAP/SOP IOP2b Abstract The impact of the data assimilation of high-density (space and time) data on the precipitation forecast is evaluated by improving the initial conditions of a mesoscale model. The high-frequency data allow for improving the three-hourly initial and boundary conditions as well. The data assimilation is performed using initial objective analysis (Cressman and multiquadric schemes) and 3D-Var. The MM5 (version 3) mesoscale model from Penn State University/National Center for Atmospheric Research is used to evaluate the impact of the improved initial and boundary conditions on the model simulations. The comparison of model results with observations shows: (i) the forecast of the precipitation at high resolution produces better results than those without data assimilation only if three-hourly data are assimilated by multiquadric; (ii) the mean error of the model rainfall largely decreases only if 3D-Var is used, but no comparable improvement in the spatial distribution of the precipitation is found; (iii) the improvement for the rainfall is not as good as it is for the initial conditions for all experiments. Moreover, the observations ingested by objective analysis modify both the amount and the timing of the precipitation on the Po valley. On the other hand, 3D-Var modifies only the amount of the precipitation, but both techniques barely recover large-model failure. Copyright © 2005 Royal Meteorological Society [source] Magnitude of Error Introduced by Application of Heart Rate Correction Formulas to the Canine QT IntervalANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2006Andrew King B.V.M.S. Background: Accurate detection of drug-induced QT interval changes is often confounded by concurrent heart rate changes. Application of heart rate correction formulas has been the traditional approach to account for heart rate,induced QT interval changes, and thereby identify the direct effect of the test article on cardiac repolarization. Despite numerous recent studies identifying the imprecision of these formulas they continue to be applied. Methods: Using a chronic atrioventricular dissociated His-paced canine model, heart rate correction methods were evaluated for their ability to generate a corrected QT interval independent of original heart rate. Additionally, His bundle pacing at a heart rate of 60 beats/min allowed calculation of the magnitude of error introduced by application of heart rate correction formulas. Results: Of the fixed parameter heart rate correction formulas, only Van de Water was able to predict corrected QT values independent of the original heart rate. The magnitude of error discovered by application of heart rate correction formulas varied, but in many cases was very large. Bazett's formula was associated with a mean overcorrection of 67.9 ms; Fridericia's 28.7 ms. Van de Water was the best fixed parameter formula with a mean error of 10.8 ms. As expected, group and individual corrections derived from linear regression of the HR-QT data offered improvement over the traditional formulas. Both were able to predict QTc values independent of the heart rate. However, errors of the magnitude of 10 and 6 ms, respectively, were still introduced. Conclusion: Van de Water and linear regression correction methods were superior to others in this study, but all methods generated QTc errors equal to or much greater than the magnitude of interest for drug safety evaluation. [source] Dispersion and Accuracy of Simulated Phosphene Positioning Using Tactile BoardARTIFICIAL ORGANS, Issue 12 2009Leilei Zhang Abstract The evaluation of phosphene is one of the most important things after the electrode array's implantation. Some experiments have been used to study the basic rules on people using their tactile perception in describing the characteristics of simulated phosphenes, such as the dispersion, accuracy, and response time. In order to describe the simulated phosphenes more systematically and scientifically, an improved phosphene-positioning method using tactile board was designed in this study. Using tactile board to guide the tactile perception, the dispersion was limited to less than 6 mm, while the largest mean error was 8.1 mm, which was nearly equal to the minimal resolution of tactile board (8 mm). The response time greatly increased because of the standard processes in using tactile board. Moreover, the long-term experiment to repeat the procedure could improve and sustain the subjects' performance in good results. [source] An analytical method for cyclosporine using liquid chromatography,mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Srividya V. Kanduru Abstract A liquid chromatographic mass spectrometric (LC-MS) assay has been developed for cyclosporine A (CyA) in rat plasma using amiodarone as internal standard (IS). Rat plasma (100,µL) containing drug and IS were extracted using liquid,liquid extraction with 4,mL of 95:5 ether:methanol. After evaporation of the organic layer the residue was reconstituted with 500,µL of water. Then the aqueous layer was transferred to LC-MS sample vials. A 10,µL volume was injected. The analysis was performed on a C8 column 3.5,µm (2.1 × 50,mm) heated to 60°C with a mobile phase consisting of acetonitrile:methanol:0.2% NH4OH (60:20:20) at an isocratic flow-rate of 0.2,mL/min. The ions used for quantitation of CyA and IS were m/z 1202.8 and 645.9, with retention times of 3.35 and 4.72,min, respectively. Linear relationships (r2,>,0.99) were achieved between plasma or blood concentration and peak height ratios (drug:IS) over the concentration range 50,5000,ng/mL. The CV% and mean error were <19%. Based on validation data, the lower limit of quantification for the assay was 50,ng/mL. The reported assay method displayed high measures of linearity, sensitivity, reliability and precision, allowing its applicability in pharmacokinetic studies in rat. Copyright © 2009 John Wiley & Sons, Ltd. [source] A stereospecific high-performance liquid chromatographic assay for the determination of ketoconazole enantiomers in rat plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 5 2008Dalia A. Hamdy Abstract A stereospecific high-performance liquid chromatographic assay was developed for the quantitation of ketoconazole enantiomers (KTZ) in rat plasma. After protein precipitation of 100 µL plasma using acetonitrile, a wash step was performed using hexane. The supernatant was removed and KTZ enantiomers and amiodarone, the internal standard, were extracted using liquid,liquid extraction with tert-butyl methyl ether. After transfer and evaporation of the organic layer, the residue was reconstituted in mobile phase and injected into the HPLC through a chiral column. The mobile phase consisted of hexane:ethanol:2-propanol with diethyl amine, pumped at 1.5 mL/min. All components eluted within 18 min. KTZ enantiomers were baseline resolved and peaks were symmetrical in appearance with no interferences. Calibration curves were linear over the range 62.5,5000 ng/mL of enantiomer. The intraday and interday CV% assessments were ,19 and <13%, respectively, and mean error was <4% for both enantiomers. The lower limit of quantitation was 62.5 ng/mL for each enantiomer based on 100 µL rat plasma. In rats, plasma concentrations of (+)-KTZ were higher than those of antipode after single oral doses. The assay was shown to be sensitive and appropriate for use in pharmacokinetics study of KTZ in rat. Copyright © 2008 John Wiley & Sons, Ltd. [source] Comparison of anterior chamber depth measurements taken with the Pentacam, Orbscan IIz and IOLMaster in myopic and emmetropic eyesACTA OPHTHALMOLOGICA, Issue 4 2009Canan Asli Utine Abstract. Purpose:, This study determined to assess the degree of agreement between anterior chamber depth (ACD) measurements obtained using three different devices and to analyse the relationship between ACD and spherical equivalent (SE) refraction. Methods:, In this cross-sectional study, 42 eyes of 42 patients with a mean SE of , 4.69 ± 4.61 D (range 0.00 D to , 14.88 D) were analysed. Measurements of ACD between the corneal epithelium and the anterior surface of the crystalline lens, obtained using the Pentacam, Orbscan IIz and IOLMaster, were compared. The relationships between SE and ACD measurements obtained with different devices were also investigated. The results were analysed using Bland,Altman analyses, single-sample t -test and Pearson's correlation test. Results:, Orbscan ACD measurements were an average of 0.05 mm less than Pentacam measurements (p = 0.01). IOLMaster measurements were an average of 0.06 mm less than Orbscan measurements (p < 0.001). None of the ACD values measured by any of the devices were correlated with increasing SE (p > 0.05 for all). There was a weak positive correlation between SE and the difference in ACD measurements with Pentacam and Orbscan (p = 0.04); however, the differences between Pentacam and IOLMaster ACD measurements and Orbscan and IOLMaster ACD measurements seemed to be independent of SE (p = 0.17 and p = 0.54, respectively). Conclusions:, The ACD in clinically normal eyes is measured differently by various non-ultrasonic devices. However, the observed mean error between these modalities is too small to create any noticeable difference in refractive outcome. No significant relationship was found between SE and ACD measurements obtained by Pentacam, Orbscan or IOLMaster. [source] Prediction intervals in linear regression taking into account errors on both axesJOURNAL OF CHEMOMETRICS, Issue 10 2001F. Javier del Río Abstract This study reports the expressions for the variances in the prediction of the response and predictor variables calculated with the bivariate least squares (BLS) regression technique. This technique takes into account the errors on both axes. Our results are compared with those of a simulation process based on six different real data sets. The mean error in the results from the new expressions is between 4% and 5%. With weighted least squares, ordinary least squares, the constant variance ratio approach and orthogonal regression, on the other hand, mean errors can be as high as 85%, 277%, 637% and 1697% respectively. An important property of the prediction intervals calculated with BLS is that the results are not affected when the axes are switched. Copyright © 2001 John Wiley & Sons, Ltd. [source] Automatic model-based evaluation of magnetic resonance-guided radio frequency ablation lesions with histological correlationJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2004Roee S. Lazebnik PhD Abstract Purpose To develop a model-based method for automatic evaluation of radio frequency (RF) ablation treatment using magnetic resonance (MR) images. Materials and Methods RF current lesions were generated in a rabbit thigh model using MR imaging (MRI) guidance. We created a 12-parameter, three-dimensional, globally deformable model with quadric surfaces that delineates lesion boundaries and is automatically fitted to MR grayscale data. We applied this method to in vivo T2 - and contrast-enhanced (CE) T1 -weighted MR images acquired immediately post-ablation and four days later. We then compared results to manually segmented MR and three-dimensional registered corresponding histological boundaries of cellular damage. Results Resulting lesions featured a two-boundary appearance with an inner region and an outer hyperintense margin on MR images. For automated vs. manual MR boundaries, the mean errors over all specimens were 0.19 ± 0.51 mm and 0.27 ± 0.52 mm for the inner surface, and ,0.29 ± 0.40 mm and ,0.12 ± 0.17 mm for the outer surface, for T2 - and CE T1 -weighted images, respectively. For automated vs. histological boundaries, mean errors over all specimens were 0.07 ± 0.64 mm and 0.33 ± 0.71 mm for the inner surface, and ,0.27 ± 0.69 mm and 0.02 ± 0.43 mm for the outer surface, for T2 - and CE T1 -weighted images, respectively. All boundary errors compared favorably to MR voxel dimensions, which were 0.7 mm in-plane and 3.0 mm thick. Conclusion The method is accurate both in describing MR-apparent boundaries and in predicting histological response and has applications in lesion visualization, volume estimation, and treatment evaluation. J. Magn. Reson. Imaging 2004;19:245,254. © 2004 Wiley-Liss, Inc. [source] Investigation of in vivo 6DOF total knee arthoplasty kinematics using a dual orthogonal fluoroscopic systemJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2006George R. Hanson Abstract Fluoroscopic techniques have been recently used to detect in vivo knee joint kinematics. This article presents a technique that uses two fluoroscopes to form a dual orthogonal fluoroscopic system for accurately measuring in vivo 6DOF total knee arthoplasty (TKA) kinematics. The system was rigorously validated and used to investigate in vivo kinematics of 12 patients after cruciate-retaining TKA. In a repeatability study, the pose of two different TKA components was reproduced with standard deviations (SD) of 0.17 mm and 0.57° about all three axes. In an accuracy study, the reproduced component positions were compared to the known component positions. Position and rotation mean errors were all within 0.11 mm and 0.24°, with SD within 0.11 mm and 0.48°, respectively. The results of this study show that the matching process of the imaging system is able to accurately reproduce the spatial positions and orientations of both the femoral and tibial components. For CR TKA patients, a consistent anterior femoral translation was observed with flexion through 45° of flexion, and thereafter, the femur translated posteriorly with further flexion. The medial,lateral translation was measured to be less than 2 mm throughout the entire flexion range. Internal tibial rotation steadily increased through maximum flexion by approximately 6°. Varus rotation was also measured with flexion but had a mean magnitude less than 2.0°. In conclusion, the dual orthogonal fluoroscopic system accurately detects TKA kinematics and is applicable towards other joints of the musculoskeletal system, including the wrist, elbow, shoulder, ankle, and spine. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] | ||||||||||||||||||||||