Root-mean Error Research Articles

Algorithmic dimensionality reduction for molecular structure analysis.

Dimensionality reduction approaches have been used to exploit the redundancy in a Cartesian coordinate representation of molecular motion by producing low-dimensional representations of molecular motion. This has been used to help visualize complex energy landscapes, to extend the time scales of simulation, and to improve the efficiency of optimization. Until recently, linear approaches for dimensionality reduction have been employed. Here, we investigate the efficacy of several automated algorithms for nonlinear dimensionality reduction for representation of trans, trans-1,2,4-trifluorocyclo-octane conformation--a molecule whose structure can be described on a 2-manifold in a Cartesian coordinate phase space. We describe an efficient approach for a deterministic enumeration of ring conformations. We demonstrate a drastic improvement in dimensionality reduction with the use of nonlinear methods. We discuss the use of dimensionality reduction algorithms for estimating intrinsic dimensionality and the relationship to the Whitney embedding theorem. Additionally, we investigate the influence of the choice of high-dimensional encoding on the reduction. We show for the case studied that, in terms of reconstruction error root mean square deviation, Cartesian coordinate representations and encodings based on interatom distances provide better performance than encodings based on a dihedral angle representation.

Development and psychometric testing of a new geriatric spiritual well‐being scale

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 χ(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.

Mathematical modelling of convection drying of green table olives

This paper presents a study of the mathematical modelling of green table olives (Olea europaea L. Domat variety) drying. Calibrated olive samples (140–180 kg−1) were used for the drying tests performed in the laboratory with various temperatures (40, 50, 60 and 70 °C) at a constant air velocity of 1.0 m s−1 and relative humidity of 15±2%. Drying to 5% (db) moisture content in the dryer took about 37.5, 24.0, 17.5 and 11.5 h at air temperatures of 40, 50, 60 and 70 °C, respectively. Thirteen different mathematical drying models were compared based on the correlation coefficient, root mean error, main bias error and reduced mean square of the deviation to estimate drying curves. It was concluded that a proposed drying model in this study could sufficiently describe convection drying of green table olives under the conditions studied.

The Relationship Between Organizational Support, Work-Family Conflict, and the Job-Life Satisfaction of University Coaches

This study examined the relationship between organizational support, work-family conflict, and job and life satisfaction among coaches. Data from collegiate head coaches with families (N = 253) were gathered through a mailed questionnaire. Results from a series of covariance structure models indicated that a partially mediated model was the best fitting model, χ2 = (255, N = 253) 461.20, p < .001; root mean error of approximation = .05; comparative fit index = .95; parsimonious normed fit index = .71. In partial support of the study hypotheses, the results supported full mediation of the direct effect from organizational support to life satisfaction. Work-family conflict partially mediated the relationship between organizational support and job satisfaction. Job satisfaction partially mediated the effect of organizational support and work-family conflict to life satisfaction.

Development of a chemometric correlation technique to estimate acid–base descriptors for cationic acids in non-aqueous media

We propose a procedure for estimating acid–base constants in organic solvents or mixture of solvents from the corresponding p K a values in aqueous medium and from certain properties of the organic solvents that characterize them. To accomplish this, we developed and validated a chemometric correlation for the calculation of the acid–base constants of different cationic acids in a broad variety of non-aqueous solvents. The parameters chosen for building the model were as follows: the acid–base constant of the compound in aqueous medium and those corresponding to the polarity–polarizability, basicity and acidity scales of the solvent. The results of the fitting were significant ( p < 0.01), with a root mean error in cross-validation of 18%, with no overfitting. The prediction of the acid–base constants for an external set of compounds had a mean absolute prediction error value of less than 0.8 p K a units.

Proper motions and CCD-photometry of stars in the region of the open cluster Trumpler 2

The results of a complex study of the galactic open cluster Trumpler 2 are presented. In order to obtain the proper motions, the positions of approximately 3000 stars up to the limit magnitude mag in the area around the cluster were measured on 6 plates with a maximal epoch difference of 63 years. The root-mean error of the relative proper motions is 4.2 mas yr-1. The catalogue of magnitudes of all the stars in the investigated area was compiled. The selection of the cluster members within the region of from the center of the cluster was made. Altogether, 148 stars were considered to be cluster members by both astrometrical and photometrical criteria. We present the estimated age ( yr) and physical parameters of the cluster and append the catalogues of the proper motions and of the photometry of the stars.

Validation of a combined corneal topographer and aberrometer based on Shack-Hartmann wave-front sensing.

A corneal aberrometer based on Shack-Hartmann wave-front sensing was developed and validated by using calibrated aspheric surfaces. The aberrometer was found to accurately measure corneal reflective aberrations, from which corneal topography and corneal refractive aberrations were derived. Measurements of reflective aberrations correlated well with theory (R2 = 0.964 to 0.994). The sag error root mean square (RMS) was small, ranging from 0.1 to 0.17 microm for four of the five calibrated surfaces with the fifth at 0.36 microm as a result of residual defocus. Measured refractive aberrations matched with theory and whole-eye aberrometry to within a small fraction of a wavelength. Measurements on three human corneas revealed very large refractive astigmatism (0.65-1.2 microm) and appreciable levels of trefoil (0.08-0.47 microm), coma (0.14-0.19 microm), and spherical aberration (0.18-0.25 microm). The mean values of these aberrations were significantly larger than the RMS in repeated measurements.

Comparison of solar radiation correlations for ?zmir, Turkey

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 İzmir 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 İzmir better than other available models. Copyright © 2002 John Wiley & Sons, Ltd.

Comparison of traditional and multivariate calibration techniques applied to complex matrices using inductively coupled plasma atomic emission spectroscopy

Univariate and multivariate (partial least squares 1, PLS1) calibration techniques are compared for the determination of Pt, Pd and Rh in a complex sample matrix. The univariate techniques utilised either pure standards, pure standards with interelement correction factors applied, or matrix matched standards. Univariate calibration yielded relative root mean square errors (RRMSEs) of prediction for Pt, Pd and Rh of 19, 15, and 54% and 13, 18, and 88% for test solutions and real samples, respectively. Univariate calibration with matrix matching proved the most accurate method with RRMSEs for Pt, Pd and Rh of 2.5, 3.7 and 2.4% for a series of synthetic test solutions, and 12, 2.3 and 8.0% for real samples, respectively. In comparison, the multivariate calibration method yielded relative root mean errors for Pt, Pd and Rh of 5.8, 3.0 and 3.5% in the test solutions, and 32, 7.4 and 76% in the real samples. The relative error for the matrix matching and PLS1 techniques was dependent upon analyte concentration.

Impact of modified physics in limited area model forecasts

A number of physical factors have been introduced to improve limited area model forecasts. The factors include land surface fluxes, shallow convection and radiation. The model including these additional physical factors (modified physics) is run for five cases of monsoon depression which made landfall over the Indian coast, and the results are compared with those of the control run. The forecasts are verified by computing the root mean square and mean errors. The differences in these skill scores between the two model runs are tested for their statistical significance. It is found that the modified physics has a statistically significant effect on the model skill with the maximum impact on the mean sea level pressure and the temperature.

Poor correlation between published methods to predict creatinine clearance and measured creatinine clearance in asymptomatic HIV infected individuals

The purpose of this study was to evaluate the predictive ability of six published creatinine clearance (CCr) equations in healthy human immunodeficiency virus (HIV) infected individuals. A 24-h urine collection to determine CCr was done on an out patient basis in 18 subjects. Predicted CCr was compared with the measured values, and the predictive performance was assessed with percentage mean error (bias) and percentage root mean error (precision). Mean ± standard deviation measured CCr was 107 ± 35 mL/min/1.73 M2. CCr determined using each of the published equations correlated poorly with measured values. CCr determined using Hull methods was significantly different from the measured values. Though Cockcroft and Gault and Jelliffe methods had the lowest mean bias and greater precision, a significant range of difference from measured CCr was observed (-12 to + 28%). All methods over estimated the measured CCr in HIV-infected individuals. Until other approaches are developed, a 24 h urine collection may be the best approach for assessing renal function in HIV-infected individuals, especially in those receiving medications with narrow therapeutic indices that are cleared by the kidney.

MALDI FTMS analysis of polymers: improved performance using an open ended cylindrical analyzer cell

Improvements in the matrix assisted laser desorption/ionization analysis of polymers are obtained with Fourier transform mass spectrometry by using an open-ended cylindrical analyzer cell. These improvements include a reduced sensitivity to experimental parameters in determining the oligomer molecular weight distribution, and better mass accuracy. Ion trajectory calculations and experimental data show that the open-ended cylindrical cell is less sensitive to changes in gated trapping time for capturing a range of masses. For poly(ethylene)glycol 1000, a shift of only 20 Da is observed for a 200 μs change in gated trapping time and shift of 100 Da for the weight average is observed for a 540 μs change. The mass accuracy for determinations of end-group and repeat unit masses are presented for internal and external calibration of polymer samples. Using a linear regression method, repeat group masses were determined to within 0.1 mmu and 0.7 mmu for internal and external calibration at 2000 Da. The mass accuracy at high molecular weight with external calibration was tested with poly(methyl) methacrylate 6000, which yielded a mean squared error of 8.1 mmu for the repeat mass and 23.6 mmu for the end-group mass. Space charge is shown to affect mass accuracy. By accounting appropriately for this effect, a root mean error of 1.4 ppm is obtained for nine peaks in an externally calibrated poly(methyl) methacrylate 6000 mass spectrum.

Automated assessment of numerical chromosomal aberrations in paraffin embedded prostate tumor cells stained by in situ hybridization.

We investigated the feasibility of automated counting of in situ hybridization signals (ISH) in interphase cells isolated from paraffin embedded prostate tissue. In total, 34 specimens from 7 patients with prostate cancer were stained with probes specific for the centromeric regions of chromosomes Y, 1, 7, 8, 10, and 15, using an immunoperoxidase based technique suitable for bright-field microscopy. Enumeration of the number of ISH spots of 500 nuclei per specimen was performed (1) using an automatic system developed without any human intervention and (2) using the same system, but including verification of the counts based on visual inspection of the stored images. As reference from each specimen, 200 cell nuclei were evaluated manually, using conventional microscopy. A typical analysis procedure (including user verification) took 35 min. The difference (root mean error) between the automated counting and the counting after visual interaction was relatively small (15%). The percentage of cells with incorrect counts by automated analysis was 20.2%, a number that could easily be improved by user interaction. Detection of cells with aneusomy proved to be more sensitive compared to the routine manual counting, in cases where aberrant frequencies were low. Automated counting of samples with low frequencies (< 10%) resulted in a higher frequency of aberrant cells in 9 of 11 cases, probably due to the fact that an unbiased cell selection is guaranteed. Automated assessment of ISH signals is considered useful for the evaluation of chromosomal aberrations in prostate tumor cells, provided that the counts are visually confirmed.

Automated assessment of numerical chromosomal aberrations in paraffin embedded prostate tumor cells stained by in situ hybridization

We investigated the feasibility of automated counting of in situ hybridization signals (ISH) in interphase cells isolated from paraffin embedded prostate tissue. In total, 34 specimens from 7 patients with prostate cancer were stained with probes specific for the centromeric regions of chromosomes Y, 1, 7, 8, 10, and 15, using an immunoperoxidase based technique suitable for bright-field microscopy. Enumeration of the number of ISH spots of 500 nuclei per specimen was performed (1) using an automatic system developed without any human intervention and (2) using the same system, but including verification of the counts based on visual inspection of the stored images. As reference from each specimen, 200 cell nuclei were evaluated manually, using conventional microscopy. A typical analysis procedure (including user verification) took 35 min. The difference (root mean error) between the automated counting and the counting after visual interaction was relatively small (15%). The percentage of cells with incorrect counts by automated analysis was 20.2%, a number that could easily be improved by user interaction. Detection of cells with aneusomy proved to be more sensitive compared to the routine manual counting, in cases where aberrant frequencies were low. Automated counting of samples with low frequencies (<10%) resulted in a higher frequency of aberrant cells in 9 of 11 cases, probably due to the fact that an unbiased cell selection is guaranteed. Automated assessment of ISH signals is considered useful for the evaluation of chromosomal aberrations in prostate tumor cells, provided that the counts are visually confirmed. © 1996 Wiley-Liss, Inc.